hysys tutorial

2.4 Update

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Copyright NoticeThe copyright in this manual and its associated computer program are the property of Hyprotech Ltd. All rights reserved. Both this manual and the computer program have been provided pursuant to a License Agreement containing restrictions on use.

Hyprotech reserves the right to make changes to this manual or its associated computer program without obligation to notify any person or organization. Companies, names and data used in examples herein are fictitious unless otherwise stated.

No part of this manual may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any other language, in any form or by any means, electronic, mechanical, magnetic, optical, chemical manual or otherwise, or disclosed to third parties without the prior written consent of Hyprotech Ltd., Suite 800, 707 - 8th Avenue SW, Calgary AB, T2P 1H5, Canada.

© 2001 Hyprotech Ltd. All rights reserved.

HYSYS, HYSYS.Plant, HYSYS.Process, HYSYS.Refinery, HYSYS.Concept, HYSYS.OTS, HYSYS.RTO, DISTIL, HX-NET, HYPROP III and HYSIM are registered trademarks of Hyprotech Ltd.

Microsoft® Windows®, Windows® 95/98, Windows® NT and Windows® 2000 are registered trademarks of the Microsoft Corporation.

This product uses WinWrap® Basic, Copyright 1993-1998, Polar Engineering and Consulting.

Documentation CreditsAuthors of the current release, listed in order of historical start on project:

Sarah-Jane Brenner, BASc; Conrad, Gierer, BASc; Chris Strashok, BSc; Lisa Hugo, BSc, BA; Muhammad Sachedina, BASc; Allan Chau, BSc; Adeel Jamil, BSc; Nana Nguyen, BSc; Yannick Sternon, BIng; Kevin Hanson, PEng; Chris Lowe, PEng.

Since software is always a work in progress, any version, while representing a milestone, is nevertheless but a point in a continuum. Those individuals whose contributions created the foundation upon which this work is built have not been forgotten. The current authors would like to thank the previous contributors.

A special thanks is also extended by the authors to everyone who contributed through countless hours of proof-reading and testing.

Contacting HyprotechHyprotech can be conveniently accessed via the following:

Website: www.hyprotech.comTechnical Support: [email protected] and Sales: [email protected]

Detailed information on accessing Hyprotech Technical Support can be found in the Technical Support section in the preface to this manual.

Table of Contents

Plant Tutorials&ApplicationsTOC.fm Page iii Monday, February 26, 2001 9:22 AM

1 HYSYS Tutorials ...............................................1-1Unique Concepts............................................................... 1-2

Powerful Engineering Tools ............................................ 1-11

Primary Interface Elements ............................................. 1-12

Pre-Tutorial...................................................................... 1-15

Starting HYSYS............................................................... 1-26

2 Dynamic Fundamentals Tutorial ......................2-1

3 Gas Processing Tutorial...................................3-1

4 Refining Tutorial...............................................4-1

5 Chemicals Tutorial ...........................................5-1

6 Dynamic Gas Processing Tutorial....................6-1

7 Dynamic Refining Tutorial................................7-1

8 Dynamic Chemicals Tutorial ............................8-1

HYSYS Applications ............................................. i

Example Application Layout ............................... v

G1 Acid Gas Sweetening with DEA .................... G1-1

R1 Atmospheric Crude Tower .............................R1-1

R2 Sour Water Stripper........................................R2-1

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Plant Tutorials&ApplicationsTOC.fm Page iv Monday, February 26, 2001 9:22 AM

P1 Propylene/Propane Splitter ............................P1-1

C2 Ethanol Plant ..................................................C2-1

C4 Synthesis Gas Production..............................C4-1

X1 Case Linking...................................................X1-1

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HYSYS Tutorials 1-1

1 HYSYS Tutorials

This manual presents you with seven independent Tutorial sessions. Each of these Tutorials guide you step-by-step through the complete construction of a HYSYS simulation. The Tutorial(s) you choose to work through will likely depend on the simulation topic that is most closely related to your work, your familiarity with HYSYS and the types of simulation cases you anticipate on creating in the future.

Regardless of which Tutorial you work through first, you will gain the same basic understanding of the steps and tools used to build a HYSYS simulation. After building one of these Tutorial cases, you might choose to build one or several more, or begin creating your own simulations.

The first tutorial is a jump-start into HYSYS.Plant dynamics. It provides a fundamental look at the methods and parameters associated with building a HYSYS case in Dynamics mode, rather than taking a Steady State Model and transferring it over to a Dynamic Model. This tutorial assumes a general knowledge f HYSYS nomenclature and methods.

The remaining six tutorials are classified based on three general areas of interest:

1. Gas Processing

2. Refining

3. Chemicals

All completed Tutorial cases are included with your HYSYS package, and are available to be called up from disk.

If you are new to HYSYS, it is recommended that you begin with the Steady State tutorials. These tutorials explicitly detail each step required to complete the simulation. In steps where more than one method is available to complete a particular action, all methods are outlined. The Dynamic tutorials (which can only be attempted when using HYSYS.Plant) are also presented in a step-by-step manner, but are less detailed in their explanations. They assume a rudimentary knowledge of the HYSYS interface and methods.

If you are familiar with HYSYS and want to learn to build cases in Dynamic mode, begin with the first tutorial.

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Each area has an associated Steady State and Dynamic tutorial. The Dynamic tutorials use the Steady State cases and add control schemes and dynamic specifications required to run the case in Dynamic mode. If you are only interested in Steady State simulation, go through the Steady State tutorial(s) that most interest you. However, you may be strictly interested in learning to apply Dynamic simulation methods and do not wish to go through building the Steady State simulation. In this situation, simply use the pre-built Steady State base case, included with HYSYS, as the starting point for your Dynamic tutorial case.

Prior to starting the Tutorials, this chapter provides a brief introduction to the structure of HYSYS, as well as the underlying engineering philosophy upon which that structure is based.

The basis of this structure is discussed in terms of three important topics:

• Unique Concepts that define the basic manner in which you build a HYSYS simulation.

• Powerful Engineering Tools that define the way HYSYS performs its calculations.

• Primary Interface Elements used to interact with HYSYS.

Although these topics are discussed individually, together they define the interactive, intuitive approach to modelling with HYSYS.

Unique ConceptsHYSYS is built upon a number of important concepts that make the most efficient use of your simulation time. Two of these concepts are especially worth noting, as they define the basic manner in which you build a HYSYS simulation:

• The Concept of Flowsheets and Sub-Flowsheets • The Concept of Environments

Flowsheet ArchitectureThe concept of Flowsheets and Sub-Flowsheets provides you with a flexible, intuitive method of building your simulation. Suppose you are simulating a large processing facility with a number of individual process units. Instead of installing all process streams and unit

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operations into a single, cumbersome flowsheet, you can simulate each process unit inside its own dedicated Sub-Flowsheet.

HYSYS Flowsheets are defined in terms of the Flowsheet Components they possess:

From the perspective of the simulation’s Main Flowsheet, the Sub-Flowsheets contained within are seen as discrete unit operations with feed and product streams. If you are interested only in the inlet streams to and the outlet streams from a Sub-Flowsheet, you can simply work from the Main Flowsheet. However, if you wish to concentrate only on the objects in the Sub-Flowsheet, you can go "inside" the Sub-Flowsheet.

For instance, consider the Main Flowsheet for a Sour Water Stripper simulation.

The unit operation names appear in uppercase letters, namely PREHEAT, EXCHANGER and SW STRIPPER. From the perspective of the Main Flowsheet, the distillation column SW STRIPPER appears as any other unit operation, with feed and product streams (e.g., Feed, Off Gas, Bottoms). However, the column is also a Sub-Flowsheet with

Flowsheet Component

Description

An independent Fluid Package

Consists of a Property Package (e.g., an equation of state) and Components (e.g., Methane, Ethane, Propane, Water).

Flowsheet Objects Unit operations and/or streams (material and/or energy streams).

PFD A HYSYS view (window) presenting a graphical representation of the flowsheet topology, showing connections between the Flowsheet Objects.

Workbook A HYSYS view presenting tabular information describing the Flowsheet Objects.

A dedicated Desktop

The main HYSYS work space where the views for the flowsheet are displayed.

Figure 1

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streams and operations of its own. You can go "inside" the column Sub-Flowsheet, which has its own Workbook and PFD, allowing you to focus on the information pertaining to the Sub-Flowsheet only.

In the Column Sub-Flowsheet, the tray section (Main TS), Reboiler and Condenser exist as individual unit operations. Similarly, the streams attaching these operations are also distinct (e.g., To Condenser, Reflux, Boilup, To Reboiler). The only Sub-Flowsheet streams of interest to the Main Flowsheet are the inlet (Feed), outlets (Off Gas, Bottoms) and utility streams (Cooling Water, Steam). These streams are "attached" to the Main Flowsheet to facilitate the transfer of information to and from the Sub-Flowsheet.

The multi-flowsheet architecture of HYSYS provides a number of technical and functional advantages. For instance, you can:

• Break a large or complex process into smaller, more concise components.

Figure 2

Note that flowsheets never hide information from one another; you can still access or change information for Sub-Flowsheet objects from the Main Flowsheet. However, if you wish to change a Sub-Flowsheet’s topology (by adding streams and/or operations, or revising connections), you must make the changes inside the particular Sub-Flowsheet.

There is no limit (except available memory) to the number of flowsheets contained in a HYSYS simulation.

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• Use an independent Fluid Package for each flowsheet.• Build a process unit as a Flowsheet Template (e.g., a

refrigeration loop or a decanter system) and store it to disk. You can then install the Template into another simulation, and simply attach the necessary feed and product streams as you would with any other unit operation.

• Use nested flowsheets, i.e. have Sub-Flowsheets inside other Sub-Flowsheets. The only restriction on nesting is with columns; that is, you cannot create Sub-Flowsheets inside column Sub-Flowsheets.

Whether your problem requires the use of multiple property packages, or involves modelling large or complex processes, multi-flowsheeting is the ideal solution.

Multi-Flowsheet NavigationThe multi-flowsheet architecture of HYSYS can be likened to a directory structure. Flowsheets and Sub-Flowsheets are directories and sub-directories, while the streams and operations are the files in that directory. The process information associated with the streams and operations is then, in essence, the contents of the files.

HYSYS has special tools, called Navigators, which have been designed to take advantage of this directory-like structure. Within a single window, you can quickly and easily access a stream, operation or process variable from any flowsheet in your simulation.

Figure 1

Navigator Button

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EnvironmentsThe second important concept upon which HYSYS is based is that of Environments. The HYSYS Environments allow you to access and input information in a certain area or "environment" of the program, while the other areas are put on "hold" until you are finished working in the area of interest.

There are five Environments in HYSYS:

• Basis• Oil Characterization• Main Flowsheet• Sub-Flowsheet• Column

Basis Environment

Whenever you begin a HYSYS simulation, you automatically start in the Basis environment. Here you can create, define and modify Fluid Packages to be used by the simulation flowsheets. In general, a Fluid Package contains at minimum a Property Package, as well as library and/or hypothetical components. A Fluid Package may also contain other information such as reactions and interaction parameters.

Oil Characterization Environment

The Oil environment allows you to characterize petroleum fluids by creating and defining Assays and Blends. The Oil Characterization procedure will generate petroleum pseudo-components for use in your Fluid Package(s). The Oil environment is unique in that it is accessible only from the Basis environment.

Main Flowsheet Environment

The Main Flowsheet environment is where you do the majority of your work – defining the topology of the Main Simulation Flowsheet by installing and defining streams, unit operations and Sub-Flowsheets.

The Main Flowsheet is said to be the parent flowsheet for the Sub-Flowsheets it contains. A Sub-Flowsheet can also be a parent flowsheet if it contains other Sub-Flowsheets.

The environments help you maintain peak efficiency while you are working with your simulation, by avoiding the execution of redundant calculations.

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Sub-Flowsheet Environment

The Sub-Flowsheet environment is where you define the topology of a particular Sub-Flowsheet. This environment is similar to the main build environment in that you can install streams, operations and other Sub-Flowsheets.

Column Environment

Similar to the Sub-Flowsheet environment, the Column environment is where you define the topology of a particular Column Sub-Flowsheet. Examples of unit operations contained in a Column Sub-Flowsheet include tray sections, condensers, reboilers and side strippers.

HYSYS contains a number of pre-built Column Sub-Flowsheet Templates which allow you to quickly install a typical type of column and then customize it accordingly.

How the Environments are Related

Each environment has its own Desktop space. Whenever you move from one environment to another, your Desktop will be redrawn with the same views as the last time you were working in that environment.

The diagram in Figure 1 shows the relationships among the various environments. The arrows indicate the directions in which you would normally move between the environments as you are building a HYSYS simulation.

The typical process for building a simulation is as follows:

1. Create a new simulation case, and you will be in the Basis Environment.

2. Inside the Basis Environment, you may:

• choose a property method and pure components from the HYSYS pure component library

• create and define any hypothetical components• define reactions

At this point, you have two options. If you have a petroleum fluid to characterize, proceed to Step 3. If not, proceed to Step 5.

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In order to access the Oil Environment, you must first be inside the Basis Environment.

3. Enter the Oil Characterization Environment, where you

• define one or more Assays and Blends• generate petroleum pseudo components to represent the oil

4. Return to the Basis Environment

5. Enter the Main Flowsheet environment, where you

• define the topology of the Main Flowsheet by installing streams and unit operations

• install Column and/or Template Sub-Flowsheets 6. Enter the Column or Sub-Flowsheet Environment, where you

define the topology of a particular Sub-Flowsheet. Remember that if you wish to change any Flowsheet’s topology, you must make the changes inside the environment of the particular flowsheet.

Keep in mind that you can move between the environments at any time during the simulation. The arrows in the diagram of Figure 1 show that

Figure 1

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the Column and Sub-Flowsheet environments are accessible only from the Main Flowsheet. However, this is only the typical way of moving between the environments. The Navigator allows you to move directly from one flowsheet to any another. The only restriction is that the Oil Environment can only be accessed from inside the Basis Environment.

Advantages of Using Environments

To illustrate the advantages of the Environments approach, consider the creation of a new HYSYS simulation case. When you start HYSYS, you will be placed in the Simulation Basis Environment. Here you define a Fluid Package by choosing a property method and components. When finished, you enter the Main Flowsheet Environment, and proceed to install streams and unit operations.

Suppose you now realize that you are missing some components in the Main Flowsheet. You can return to the Simulation Basis Environment, and all flowsheets will be placed in Holding mode until you return. This prevents calculations from taking place until you have made all changes to the Fluid Package. Flowsheet calculations will not resume until you instruct HYSYS to do so upon returning to the Main Flowsheet.

For Sub-Flowsheets, the concept of Holding Steady State calculations works according to the hierarchy of the flowsheets in the simulation. When you are working inside a particular flowsheet, only that Flowsheet and any others below it in the hierarchy will automatically calculate as you make changes. All other flowsheets will hold until you move to their Flowsheet’s Simulation Environment, or one directly above them on the hierarchical tree.

This approach helps you make the most of your simulation time by eliminating the execution of time-consuming, extraneous calculations.

With each time-step, Dynamic calculations proceed from the front to back of the flowsheet in an orderly propagation. This is not affected by the Flowsheet Environments. Dynamics calculate in a flat” Flowsheet space.

Press the Active (green) button to resume calculations.

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Consider the diagram shown in Figure 2. Suppose you want to change the number of trays for a column in Sub-Flowsheet F. You would enter the environment for this Sub-Flowsheet, make the necessary change, then instruct HYSYS to re-calculate the column. As there are no Flowsheets below F in the hierarchy; all other flowsheets will be on hold while you work on the column. You could continue making changes until you reach a satisfactory solution for F. When you then return to the Main Flowsheet Environment, all Flowsheets would automatically be re-calculated based on the new Sub-Flowsheet solution.

Suppose that you now wish to make changes in Sub-Flowsheet D, so you move to its environment. Since D is above E in the hierarchy, all flowsheets will be on hold except D and E. Once you reach a new solution for D, you might move up to C, which will then resume calculations. When you finally return to the Main Flowsheet, all other Flowsheets (Main, A, B and F) will resume calculations.

If, on the other hand, you move directly from D to A, HYSYS will automatically "visit" the Main Flowsheet for you so that Flowsheet A

Figure 2

HYSYS Tutorials 1-11

has the most up to date information when you transfer there. Any transfer to a Flowsheet not on your "branch" of the tree will force a full recalculation by HYSYS.

Powerful Engineering ToolsAt the core of HYSYS are a number of features which provide you with a great degree of flexibility in the way you supply information. These features make the process of building a simulation both interactive and intuitive, just as if you were solving the flowsheet by hand.

• Event Driven - HYSYS combines completely interactive calculation with instantaneous access to information. Whenever you supply a new piece of information, HYSYS automatically re-calculates all items affected by the change, and immediately displays the updated information in all locations.

• Built-in Intelligence - The HYSYS property packages know when enough information is available and perform the correct flash calculation automatically.

• Modular Operations - Each unit operation or stream can perform all necessary calculations, whether the information is specified in the operation itself, or communicated from the attached streams. Whether complete or partial, results are passed bi-directionally (forwards and backwards) through the flowsheet.

• Non-Sequential Solution Algorithm - You are not required to build a flowsheet in a specific manner or direction, nor are you required to instruct unit operations to begin calculations. Based on the flowsheet topology and supplied information, every stream and unit operation affected by a change is automatically calculated.

Note that the concept of Holding only applies to steady-state calculations. In Dynamic mode, calculations proceed from the front to the back of each flowsheet in an orderly propagation with each time step. Dynamic calculations are not affected by the Flowsheet Environments.

These features, in combination with the easy-to-use interface, maximize your return on simulation time. With immediate calculation and instant access to information, you gain process understanding as you build the model.

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Primary Interface ElementsThere is no restriction on which interface elements – PFD, Workbook, or Property Views – can be open at any time. All displayed information is automatically updated with the most current information.

Information can be supplied and accessed in a variety of manners throughout HYSYS. The three primary interface elements for interacting with HYSYS are:

• PFD• Workbook• Property View

PFD

The PFD is a graphical representation of your flowsheet, showing the connections among the streams and operations. You can use the PFD to, among other things, build and examine your flowsheet, and display detailed process information using customizable Material Balance Tables. A sample PFD is shown in the following figure.

Figure 1


Workbook

Information is shared among all these interface elements, so no matter which one(s) you have open on your screen, each will display the most current data.

The Workbook is a collection of pages that display information in a tabular format. Each Workbook page displays information about a specific object type, such as streams or unit operations. You can install multiple pages for a given object type, displaying information in varying levels of detail. A sample Workbook is shown Figure 2.

Figure 2

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Property View

The property view contains multiple views of "properties" for a stream or operation with each view accessed via a tab. Within each tab there are several pages that contain the relevant property information. A sample property view for a material stream is shown in Figure 3.

These and other interface elements are discussed in more detail in the actual Tutorial sessions that follow.

Figure 3

Pages

Tabs


Pre-TutorialIn the chapters that follow, example problems are used to illustrate some of the basic concepts of building a simulation in HYSYS. Seven complete Tutorials are presented:

1. Dynamic Fundamental Tutorial - Introduces and illustrates the steps required to build simulations strictly using HYSYS.Plant dynamics. The tutorial details the steps to building and running a debutanizer column in Dynamic mode. This tutorial assumes a rudimentary knowledge of HYSYS methods and nomenclature.

1. Gas Processing Steady State - Models a sweet gas refrigeration plant consisting of an inlet separator, gas/gas heat exchanger, chiller, low-temperature separator and de-propanizer column.

2. Refining Steady State - Models a crude oil processing facility consisting of a pre-flash drum, crude furnace and an atmospheric crude column.

3. Chemicals Steady State - Models a propylene glycol production process consisting of a continuously-stirred-tank reactor and a distillation tower.

4. Gas Processing Dynamics - models the Gas Processing tutorial case in Dynamic mode. This tutorial makes use of the recommendations of the Dynamic Assistant when building the case.

5. Refining Dynamics - Models the Refining example problem in Dynamic mode.

6. Chemicals Dynamics - Models the Chemicals example problem in Dynamic mode. This tutorial make use of the recommendations of the Dynamic Assistant when building the case.

Each of these Tutorials will guide you step-by-step through the complete construction of a HYSYS simulation. The Tutorial you choose first will likely depend on which one is most closely related to your work, or that you feel most comfortable with.

Regardless of the tutorial you work through first, you will gain the same basic understanding of the steps and tools used to build a HYSYS simulation. Each example contains detailed instructions for choosing a property package and components, installing and defining streams, unit operations and columns, and using various aspects of the HYSYS interface to examine the results while you are creating the simulation. If you are new to HYSYS, it is recommended that you begin with one of these tutorials in order to familiarize yourself with the initial steps required to build a HYSYS simulation.

There are also several HYSYS courses available. Contact Hyprotech for more information.

If you don’t want to work through the Steady State cases, you can use the pre-built Steady State tutorial cases available with HYSYS as a starting point for the Dynamic tutorials.

All complete Tutorial cases are included with your HYSYS package in the HYSYS\SAMPLES directory.

The first tutorial is stored in the file debDyn.hsc.

The Steady State case are stored in the TUTOR1.hsc through TUTOR3.hsc files.

The Dynamic tutorials following the Steady State cases are stored in the files Dyntut1.hsc through Dyntut3.hsc.

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Often in HYSYS, more than one method exists for performing a task or executing a command. Many times you can use the keyboard, the mouse, or a combination of both to achieve the same result. The Steady State tutorials attempt to illustrate HYSYS’ flexibility by showing you as many of these alternative methods as possible. You can then choose which approach is most appropriate for you.

Except for the first tutorial, the Dynamics tutorial use the Steady State solution as a basis for building the dynamic case. If you wish, you can build the Steady State case and then proceed with the Dynamic solution, or you can simply call up the Steady State case from disk and begin the Dynamic modeling.


Conventions Used in the Manuals

Conventions used in the Manuals

The following section lists a number of conventions used throughout the documentation.

Keywords for Mouse Actions

As you work through various procedures in the manuals, you will be given instructions on performing specific functions or commands. Instead of repeating certain phrases for mouse instructions, keywords are used to imply a longer instructional phrase.

Keywords Action

Point Move the mouse pointer to position it over an item. For example, point to an item to see its Tool Tip.

Click

Position the mouse pointer over the item, and rapidly press and release the left mouse button. For example, click Close button to close the current window.

Right-ClickAs for click, but use the right mouse button. For example, right-click an object to display the Object Inspection menu.

Double-Click

Position the mouse pointer over the item, then rapidly press and release the left mouse button twice. For example, double-click the HYSYS icon to launch the program.

Drag

Position the mouse pointer over the item, press and hold the left mouse button, move the mouse while the mouse button is down, and then release the mouse button. For example, you drag items in the current window, to move them.

Tool Tip

Whenever you pass the mouse pointer over certain objects, such as tool bar icons and flowsheet objects, a Tool Tip will be displayed. It will contain a brief description of the action that will occur if you click on that button or details relating to the object.

These are the normal (default) settings for the mouse, but you can change the positions of the left- and right-buttons.

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A number of text formatting conventions are also used throughout the manuals:

Format Example

When you are asked to access a HYSYS menu command, the command is identified by bold lettering.

‘Select File-Save from the menu to save your case.’

When you are asked to select a HYSYS button, the button is identified by bold, italicized lettering.

‘Click the Close button to close the current view.’

When you are asked to select a key or key combination to perform a certain function, keyboard commands are identified by words in bolded small capitals (small caps).

‘Press the F1 key on the keyboard to open the context sensitive help.’

The name of a HYSYS view (also know as a property view or window) is indicated by bold lettering.

‘Selecting this command opens the Session Preferences view.’

The names of pages and tabs on various views are identified in bold lettering.

‘Click Composition page on the Worksheet tab to see all the stream composition information.’

The name of radio buttons, check boxes and cells are identified by bold lettering.

‘Click the Ignored check box to ignore this operation.’

Material and energy stream names are identified by bold lettering.

Column Feed, Condenser Duty

Unit operation names are identified by bold lettering.

Inlet Separator, Atmospheric Tower

When you are asked to provide keyboard input, it will be indicated by bold lettering.

‘Type 100 in the cell to define the stream temperature.’

Note that blank spaces are acceptable in the names of streams and unit operations.


Bullets and Numbering

Bulleted and numbered lists will be used extensively throughout the manuals. Numbered lists are used to break down a procedure into steps, for example:

1. Select the Name cell.

2. Type a name for the operation.

3. Press ENTER to accept the name.

Bulleted lists are used to identify alternative steps within a procedure, or for simply listing like objects. A sample procedure that utilizes bullets is:

1. Move to the Name cell by doing one of the following:

• Select the Name cell• Press ALT+N

2. Type a name for the operation.

3. Press ENTER to accept the name.

Notice the two alternatives for completing Step 1 are indented to indicate their sequence in the overall procedure.

A bulleted list of like objects might describe the various groups on a particular view. For example, the Options page of the Simulation tab on the Session Preferences view has three groups, namely:

• General Options• Errors• Column Options

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Callouts

A callout is a label and arrow that describes or identifies an object. An example callout describing a graphic is shown below.

Annotations

Text appearing in the outside margin of the page supplies you with additional or summary information about the adjacent graphic or paragraph. An example is shown to the left.

Shaded Text Boxes

A shaded text box provides you with important information regarding HYSYS’ behaviour, or general messages applying to the manual. Examples include:

The use of many of these conventions will become more apparent as you progress through the manuals.

Figure 1

HYSYS Icon

Annotation text appears in the outside page margin.

The resultant temperature of the mixed streams may be quite different than those of the feed streams, due to mixing effects.

Before proceeding, you should have read the introductory section which precedes the example problems in this manual.


Terminology

The following list describes some of the HYSYS interface terminology:

• View - Any “windowed” graphical representation found on the HYSYS Desktop. Examples include the property view for a stream (like Energy Stream C3Duty shown above) or unit operation, or an error message window.

• Property View - A view with multiple pages accessed via tabs. Property views are used extensively in HYSYS, and provide access to all information associated with an object (e.g., a stream or unit operation). The view shown here for Energy Stream C3Duty is an example of a property view.

• Modal View - Has a thick solid border, and is without one or both of the Minimize/Maximize buttons in the upper right corner. You cannot move outside a modal view until you close it, or provide the required input. The purpose of a modal view is generally to focus your attention on the current task before allowing you to perform your next task. Both the Energy Stream C3Duty and Stream 1: Compositional Basis views shown above are examples of modal views.

• Modal Property View - A property view as described above, with a thick solid border, and a Pin button in the upper right corner. A modal property view behaves similarly to a modal view as described above, in that you cannot move outside the

Figure 2

Pin buttonModal Views Property View

The modal property view is designed to prevent a "clutter" of views on your Desktop by encouraging you to focus on the current task, then close the view before moving on. When you become a more experienced user, you may wish to turn this option off by clearing the Use Modal Property Views check box on the Session Preferences view.

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view until you close it. However, a modal property view can be converted to a non-modal view by pressing the Pin button. The Energy Stream C3Duty view is a modal property view.

• Non-Modal View - Has one or both of the Minimize/Maximize buttons and a normal border. When a non-modal view is open, you can access other objects on the Desktop.

• Button - Invokes a command when pressed. An example is the Delete button in the above view.

• Tabs - In views with multiple pages of information, such as property views and Workbooks, the pages are accessed by tabs at the bottom of the view. In the figure above, Design, Reactions, Rating, Workbook and Dynamics are the tabs.

• Pages - Most tabs have associated page views. These are listed in the column on the left-hand side of the view. Above they are Connections , Parameters , User Variables and Notes .

• Drop-Down List - A list of available options for a certain input cell, indicated by the arrow at the end of an input cell.

• Input Cell - A location inside a view where information is supplied and/or displayed. Examples include stream names, temperatures, etc. In many cases an Input Cell has an associated a drop-down.

• Matrix - A group of cells in tabular format, through which you can manoeuvre with the mouse or the keyboard arrow keys.

Figure 3

Non-Modal View

Button

Maximize/Minimize Buttons

Tabs

Pages

Drop-Down List

Matrix

Check Box


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• Check Box - Items or settings which are either On or Off. Clicking on a blank check box will turn the function On. Clicking on it again turns it Off. The Ignored check box in the above view is Off.

• Edit Bar -Found at the top of a view, is used for entering or selecting numerical or text input.

• Active Highlighted Location - the current active location on a particular view is always indicated by highlighting.

• Unit Box - associated with the Edit Bar, this provides a drop-down list of units which are applicable for the parameter type of the current input cell.

• Object Status Indicator- found at the bottom of each property view, it shows the calculation status of the associated object. The indicator displays a status message with an appropriately coloured background (red for a missing parameter, yellow for a warning message and green for OK).

• Group Box - an organizational border within a page that groups related functions together. Each group box has its own active location.

Figure 4

Unit Box

Object Status Indicator Radio Button

Active Highlighted Location

Edit Bar

Group Box

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1-24

• Radio Button - A set of options, of which only one can be active at a time. Radio buttons are always found in groups of at least two.

• Close Button - The X button in the upper right corner of a view, used to close the view.

• Minimize/Maximize Buttons - In the upper right corner of a view, allows you to iconize (minimize) the current view, or expand a view to its full size.

• Scroll Bar - Clicking inside the scroll bar allows you to access information which cannot be displayed in the current size of a menu or view. The scroll bar in the above window is horizontal.

• Scroll Button - Clicking and dragging the scroll button up/down or left/right also allows you to access information which cannot be displayed in the current size of a menu or view.

• Icon - A minimized view. Double-clicking on an icon opens the view. The HYSYS icon is shown to the left.

Figure 5

Close Button

Maximize/Minimize Buttons

Scroll BarScroll Button

HYSYS Icon


You’re Ready!

We believe you will find that HYSYS is simply the best process modelling solution available. Beyond the advanced technical features, the inherent approach to modelling in HYSYS will make the best use of your simulation time.

Now that we have introduced you to some of the basics of HYSYS and this manual, you are ready to start HYSYS and begin building a simulation.

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1-26 Starting HYSYS

1-26

Starting HYSYSWith Windows NT 4.0 or Windows 95/98, the installation process creates a short-cut to HYSYS in the Start Menu under Programs...AEA Technology. To start HYSYS.Plant (or HYSYS.Process or HYSYS.Refinery).

1. Select the Start Menu.

2. Move from Programs to AEA Technology to HYSYS.Plant.

3. Select HYSYS.Plant.

When you start HYSYS, the HYSYS Desktop will appear:

Note that this view has been resized; your Desktop view should appear larger than this when initially opened. To re-size the view, click and drag the outside border. To make the view full size, press the Maximize button in the upper right hand corner.

Figure 1

HYSYS Icon

Maximize ButtonMenu BarButton Bar

Status Bar Object Status Window Trace Window Performance Slider


Some of the main features of the HYSYS Desktop are described below:

Before proceeding, the simulation preferences will be discussed.

Preferences

The session preferences are accessed via the Tools menu. To activate the menu, do one of the following:

• Select Tools on the Menu Bar.• Press ALT T

Desktop Component Description

Menu Bar

Provides access to most commands in HYSYS. Under each Menu Bar item is a list of options, some of which invoke commands (e.g., Save), others which open another view (e.g., Preferences).

Button BarProvides quick access to the most common commands. Simply select the appropriate button to invoke the associated command.

Object Status Window

Displays the status of the input information for objects (streams and unit operations) in the simulation. This window is useful for tracking unknown information for objects.

Trace Window

Displays solving messages for various objects as they are calculated. The Trace Window provides a scrolling, permanent record of these solving messages.

Status Bar

Displays Fly-By descriptions of a HYSYS button or menu when the cursor is placed over the button, or when the menu item is currently highlighted. The Status Bar also shows a single-line display of the current solving message in the Trace Window.

In HYSYS, menu items have one letter underlined, e.g., Tools. Whenever you see a label with an underlined letter, you can access the item by holding down the ALT key and pressing the letter. For menus, this command will open the associated drop-down menu. For input cells, it will move you to the cell of interest. For buttons, it will invoke the command associated with the button.

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1-28 Starting HYSYS

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A drop down menu of available items appears:

To access the Session Preferences, do one of the following:

• Press the down arrow key to move the highlight to Preferences, then press ENTER.

• Press P, the underlined letter of the item you want to open.• Click on Preferences.

The Session Preferences property view will appear:

Figure 2

Figure 3

The Menu Bar command is the only means of accessing the Session Preferences.

If you open the incorrect menu, you can either select any blank area of the Desktop, or press ESC.


Using the terminology outlined previously, some characteristics of the Session Preferences view are:

• It is a property view, as indicated by the multiple tabs.• It is currently a modal view, as indicated by the thick border and

the Pin button in the upper right corner.• It has three Groups on the Variables page, namely General

Options, Errors and Column Options.• The current active location (indicated by the highlight) is the

Allow Multiple Stream Connections selection in the General Options group.

The Preferences section in HYSYS is used to specify default information for the simulation case. This information includes Automatic Naming Formats, Units, Colours, Fonts, Icons, etc., for the simulation. Session Preferences can be saved for use in other simulations.

Common to each tab are the two buttons along the bottom of the view:

Some of the more frequently accessed preference setting views are discussed in the following section. For a detailed description of all the Session Preferences tabs and related pages, see the User’s Guide, Chapter 7 - Menu Bar Options.

You can save multiple Session Preferences.

Command Description

Save Preference SetSaves the Preferences to a file. You can provide a new file name and/or location to which the Preferences are saved.

Load Preference Set This button allows you to Load Preferences saved from a previous HYSYS session.

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1-30 Starting HYSYS

1-30

Simulation Tab

Options Page

The Options page shown in Figure 4 contains three groups: General Options, Errors, and Column Options.

The General Options group is a set of six check boxes:

Figure 4

Option Description

Allow Multiple Stream Connections

This check box, which is not activated by default, controls whether lists of streams should be filtered to only those that are not currently connected. For example, suppose you use the drop-down list of streams when selecting a feed to an operation. If this check box is not activated, only streams that are not already connected as a feed to an operation will be shown in the list. If the check box is activated, HYSYS displays all the streams in the Flowsheet, including the ones that you cannot connect as feed streams.

View New Streams Upon Creation

If activated, the property view for the stream will automatically appear when you add a new stream.

Use Modal Property Views

When this box is activated, all property views are displayed as Modal (with a Pin). If the check box is not activated, all property views are Non-Modal. When Views are Modal, you have the options of individually making each property view Non-Modal by selecting the Pin in the upper corner of the view.


The Errors group contains two check boxes that, when activated, will send the specified errors to the Trace Window. When these radio check boxes are activated, you will not be prompted to acknowledge errors.

The Column Options group contains two check boxes. The Expand Tray Sections box will, when active, show a fully expanded column in the column environment PFD. When the check box is inactive, the column is displayed with the minimum required number of trays; those trays which have streams (inlet or outlet) attached to them.

Desktop Page

The Desktop page shown in Figure 5 contains two groups: Initial Build Home View and Face Plates.

Use Input Experts

Column operations have an optional installation guide built in to assist you in the installation. When this check box is activated, you will be guided through the Column installation.

Confirm Deletes

When this is activated, HYSYS prompts you for confirmation before deleting an object. If the check box is not activated, HYSYS will delete the object as soon as the instruction is given. It is advised to keep this option activated.

Confirm Mode Switches

When activated, HYSYS prompts for confirmation when you change to or from Dynamic mode.

Option Description

Figure 5

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1-32 Starting HYSYS

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The Initial Build Home View group contains radio buttons which allow you to specify which of the three main interfaces, Workbook, PFD, or Summary, appears first when you enter a new Environment. This does not restrict you to what you can access within that environment, as the Workbook, PFD, and Summary views can all be open at the same time. This setting only establishes which view should be opened by default.

The Face Plates group involves the placement of face plates on the Desktop. When you have a large number of face plates open in a case and you select Arrange Desktop under Window in the Menu Bar, the face plates will be organized according to your specifications in the Face Plates group.

Naming Page

The Automatic Naming of Flowsheet Objects group dictates how HYSYS names streams and operations when they are installed. You can specify the naming convention for each type of operation. For each Flowsheet object, you can specify a naming convention and a starting number. For example, in the view shown, Energy Streams are indicated as Q-%d, with a Starting Number of 100. The first energy stream installed using the Add Energy Stream command will be named Q-100, the second Q-101, and so on. The automatic naming function is provided merely for convenience. You can change any default name at any time within the Flowsheet.

Figure 6

There are no restrictions in naming streams and operations. You can use more than one word (separated by spaces if desired) to provide the best possible description.


Variables Tab

Units Page

HYSYS has three default unit sets: Field, SI, and EuroSI, these are displayed in the list of Available Unit Sets. These three sets are fixed, in that none of the units can be changed. Since you may wish HYSYS to display information in units other than the default, you are able to create your own custom sets.

In the Units matrix below this list, the right column shows the unit for each corresponding variable in the left column. SI is currently highlighted in the Available Unit Set list, and the appropriate SI unit is displayed for each variable in the matrix. For example, kPa is the default unit for Pressure.

The units displayed in the simulation are dependent on your Current Unit Set. To activate one of the other two default unit sets, select the desired set in the Available Unit Sets list. The current set appears highlighted, and the units matrix is updated to display the default units associated with that set.

Figure 7

Contains the default unit set in HYSYS. These cannot be changed or deleted.

Field is the Current Unit Set for the case.

Used to add a new custom unit set to the Preferences.

Used to delete a custom unit set from the preferences.

Displays the variable and the unit according to the highlighted Unit Set.

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Although HYSYS displays a single unit for each parameter, you can supply a value for a process variable in any one of a number of applicable units. For example, suppose you want to specify the pressure of a stream to be 1 atm but you are using the Field set. There is no need to manually convert the pressure to the default unit - HYSYS will automatically perform the conversion for you. You can enter the pressure as either 1 atm, 101.325 kPa, 14.69 psia, 0.99 bar, or any of the other available units. Your input will be converted and displayed in the default unit.

Notice the Clone button in the Available Units Sets group. Although the three HYSYS Unit Sets cannot be modified, you can make a copy (clone) of any Unit Set, then modify the cloned set to display the units of your choice.

In each of the Steady State tutorials, you will be instructed as to which default Unit Set to choose.

Formats Page

On this page you can specify how variables will be displayed. Double clicking on the format cell of a variable will bring up the Real Format Editor view.

Figure 8


There are three buttons located on the Formats page:

Get Started

You are now ready to begin building a HYSYS simulation, so proceed to the Tutorial of your choice.

Button Description

Format Opens the Real Format Editor, which allows you to change the format specification for the unit selected, as well as specify the number of significant figures for that specification.

Reset Returns the selected variable to the default format.

Reset All Returns all the variables to their default formats.

If you are new to HYSYS, it is recommended that you begin with the Steady State tutorials in Chapter 3,4 or 5.

Tutorial Tutorial Book Chapter Samples Case Name

Dynamic Fundamentals

Chapter 1 debutdyn.hsc

Gas Processing Steady State

Chapter 3 TUTOR1.HSC

Refining Steady State Steady State


Chemicals Steady State


Gas Processing Dynamics

Chapter 6 dyntut1.hsc

Refining Dynamics Chapter 7 dyntut2.hsc

Chemicals Dynamics Chapter 8 dyntut3.hsc

Once you have completed one or more tutorials, you may want to examine at the Applications binder for other examples that may be of interest.

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1-36 Starting HYSYS

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Dynamic Fundamentals Tutorial 2-1

2 Dynamic Fundamentals Tutorial

This tutorial introduces you to the fundamental concepts and procedures required to build a simulation case using HYSYS.Plant Dynamics. Its detailed instructions guide you through the steps of building a basic dynamic case, to creating a more complex rating model of the simulation. As you build the flowsheet, you will learn a systematic method of setting up a dynamic simulation case. This tutorial demonstrates how the equipment and pressure-flow specifications should be set.

As you work through this tutorial, you will gain a solid understanding of the workings of HYSYS.Plant Dynamics. You can then apply this knowledge towards creating your own dynamic simulation cases.

This tutorial demonstrates the modelling of a distillation tower using two very different levels of detail. The design dynamics section will show how to prepare a simplified column model. The simplified model consists of a tray section and single unit operations representing the condenser and the reboiler. In the rating dynamics section, the single unit operation condenser will be replaced by an overhead system consisting of valves, a heat exchanger, a vapour bypass stream, an accumulator, a pump and appropriate PID controllers.

The DeButanizer column setup in this tutorial presents a general procedure for simulating towers and can be adapted to model other types and configurations of columns using HYSYS.Plant Dynamics. The

Note that this tutorial assumes that you have previous experience using HYSYS. If you are new to HYSYS, it is strongly recommended that you start with one of the Steady State tutorials to familiarize yourself with the program.

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2-2 Dynamic Fundamentals Tutorial

2-2

detailed procedure for the column setup is given, but the dynamic behaviour is not illustrated. With so many possible ways to manipulate the flowsheet, it is left as an open exercise for you to set up variables in the Databook, make changes to key variables and observe the dynamic behaviour of the model. The tutorial is designed such that at the end of both the Design and Rating sections, the process variables will line out in a minimal amount of time and the flowsheet will be ready for manipulation.

Figure 2.1

Figure 2.2


Creating a New Unit Set

The first step in building the simulation case is choosing a unit set. HYSYS will not allow you to change any of the three default unit sets listed. However, you can create a new unit set by cloning an existing one. For this example, you should make a new unit set based on the HYSYS Field set, then customize the new set:

1. Select Preferences from the Tools menu bar. The Session Preferences view should appear.

2. Select the Units page of the Variables tab.

3. Click on the Field in the Available Unit Sets list to ensure it is the active set.

4. Using the vertical scroll bar, scroll down the units matrix until Liq. Vol. Flow is visible in the left column of the matrix.

Notice the default unit for Liq. Vol. Flow is in barrel/day. A more appropriate unit for this example is ft3/hr.

5. Press the Clone button. A new unit set named NewUser will appear and become automatically highlighted, making it the Current Unit Set. If you wish, you can enter a new name in the Unit Set Name cell. You can now change the units for any variable associated with this new unit set.

6. Move to the Liq. Vol. Flow cell by clicking on barrel/day.

Figure 2.3

2-3


2-4

7. Open the drop-down list of available units in the Edit Bar by clicking on , or by pressing the F2 key then the i key.

8. Click on ft3/hr, or scroll down to it by pressing the i key then press ENTER.

Your new unit set is now defined. Press the Close button to begin the simulation.

Beginning the Simulation9. Start a new case by pressing the New Case button.

10. Create a fluid package using the following property package and components:

11. Enter the Simulation Environment.

Figure 2.4

Notice that all commands accessed via the Button Bar are also available as Menu items.

New Case Button

Property Package Components

Peng Robinson Propane, i-Butane, n-Butane, isobutene, i-Pentane, n-Pentane, n-Hexane, n-Heptane, n-Octane


12. Create the two feed streams in the Workbook using the Material Streams and Compositions tabs:

13. Add a DISTILLATION COLUMN to the case. Provide the following information:

14. On the Specs page of the DeButanizer property view, add a Column Component Fraction specification and a Column Component Recovery specification. The completed views for the specifications are shown in Figure 2.5:

Stream Name Feed 1 Feed 2

Temperature [F] 300.0 140.0

Pressure [psia] 220 350

Mass Flow [lb/hr] 18000 9000

Mass Fraction [propane] 0.012 0.020

Mass Fraction [i-butane] 0.170 0.190

Mass Fraction [n-butane] 0.170 0.200

Mass Fraction [i-butene] 0.008 0.220

Mass Fraction [i-pentane] 0.140 0.160

Mass Fraction [n-pentane] 0.140 0.210

Mass Fraction [n-hexane] 0.110 0.000

Mass Fraction [n-heptane] 0.130 0.000

Mass Fraction [n-octane] 0.120 0.000

Tab [Page] Input Area Entry

Design [Connections]

Column Name DeButanizer

Number of Stages 15

Feed Stream (Feed Stage) Feed 2 (4)

Feed Stream (Feed Stage) Feed 1 (8)

Condenser Type Partial

Ovhd Vapour Outlet Vent Control

Ovhd Liquid Outlet Butanes

Bottoms Liquid Outlet C5+

Reboiler Energy Stream Reb Q

Condenser Energy Stream Cond Q

Condenser Pressure [psia] 205

Condenser Delta P [psi] 3

Reboiler Pressure [psia] 215

Design [Monitor] Ovhd Vap Rate Specified Value [lbmole/hr]

0

2-5


2-6

15. On the Monitor page of the Debutanizer property view, deactivate the Active check box for both the Reflux Ratio and Distillate Rate specifications.

16. Activate the Active check box for both new specifications, C5s in Top and Butane Recovery.

The column will begin solving.

17. Tighten the purities on the tower by changing the specified values of C5s in Top and Butane Recovery to 0.018 and 0.951 respectively.

The tower is producing a higher purity product, but the trade-off is increased operating costs arising from higher condenser and reboiler duties.

18. Close the DeButanizer column property view.

19. Save the case as DFTutSS.hsc. Open the File menu and select Save As. Type in the file name as DFTutSS.hsc and click the Save button.

Dynamic Specifications20. Switch to Dynamic mode. When asked if you want to resolve the

items identified by the dynamics assistant, click the No button.

Figure 2.5

Dynamic Mode Button


To summarize the pressure-flow specifications for this case, one pressure-flow specification will be set around the condenser and one will be set on each of the flowsheet boundary streams:

• Feed 1• Feed 2• Vent Control• Butanes• C5+

In addition, the condenser, reboiler and tray section will be sized, using the steady state flows for the design.

Condenser Specification

For the flowsheet created in this example, the liquid product stream from the condenser, Butanes, is a flowsheet boundary stream and will have a flowrate specification. With this in mind, one other condenser specification will define the pressure-flow relationship within the condenser. You have two options for this specification:

• Flow of the stream Reflux• Reflux Rate as a ratio of total liquid from the unit

For this case, the reflux rate as a ratio of total liquid will be specified.

21. Open the Object Navigator by pressing F3.

22. Select the UnitOps radio button in the Filter group.

23. Select DeButanizer in the Flowsheets group and Condenser in the Unit Operations group.

Figure 2.6

A condenser for a refluxed tower increases the flowsheet degrees of freedom by one and thus, requires an additional pressure-flow specification.

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2-8

24. Press the View button.

25. On the Condenser property view, select the Dynamics tab, and then the Specs page.

Since the steady state reflux ratio was approximately 4.5, the rate of Reflux was 4.5 times the rate of Butanes. There was no overhead vapour so the reflux ratio compares only the two liquid streams. By dividing 4.5/5.5, the reflux rate as a ratio of total liquid flow is obtained.

26. In the Dynamic Specification group box, activate the check box for the Reflux Flow/Total Liq Flow specification and input a value of 0.82.

Sizing the Condenser

Using the flows that were calculated in steady state as a design basis, the condenser will now be sized.

27. Select the Worksheet tab and Conditions page on the Condenser property view and make a note of the liquid volume flow of the stream To Condenser.

For a quick sizing calculation, use a flow of 1750 ft3/hr, a 20 minute residence time and a liquid operating level of 50%.

28. Select the Specs page of the Dynamics tab in the Condenser property view.

29. Delete the value in the Volume field.

30. Input a Diameter of 10 ft and a Length of 15 ft to obtain a vessel volume that approaches 1180 ft3.

1750ft3hr-------

1hr60min----------------× 20min

10.5-------×× 1167ft3=


The completed Specs page should appear as shown:

Condenser Utility Valve

31. Select the Duty page on the Dynamics tab of the Condenser property view.

32. Press the Initialize Duty Valve button.

This initialization provides a UA value, a flow range for the utility fluid and an inlet temperature for the fluid according to the current flow of material into the condenser.

33. Close the Condenser property view.

Boundary Stream Specifications

For the stream Feed 1, set a dynamic flow specification on a volume basis as follows:

34. Open the property view for Feed 1 by double clicking on the Feed 1 cell in the Workbook.

35. Select the Dynamics tab.

Figure 2.7

2-9


2-10

36. Deactivate the Pressure specification.

37. Change the Flow specification basis to Ideal Liq Vol, by selecting the corresponding radio button. To do this, you may have to deactivate this specification, select the radio button, and then reactivate the specification.

The Dynamics tab should appear as in Figure 2.8:

38. Close the stream property view.

39. Repeat steps #34 to #38 for Feed 2.

Now you can set a volume basis dynamic flow specification on stream Butanes. Proceed through the following steps:

40. Open the property view for stream Butanes.

41. Choose the Dynamics tab.

Since the pressure and flow of stream Butanes were not specified in steady state, neither is used as an active pressure-flow specification.

42. Activate the Flow specification and select IdealLiqVol as the flow basis.

The Dynamics tab should appear as shown in Figure 2.9:

Figure 2.8



44. Repeat steps #40 and #43 for the stream C5+.

The last pressure-flow specification will be a dynamic pressure specification on the stream Vent Control.

45. Open the property view for the stream Vent Control.

46. Select the Dynamics tab.

47. Activate the Pressure specification.

If you open the Workbook to the Material Streams tab, you will notice that the only pressure and flow values that are shown in blue are the ones that were just selected as dynamic specifications.


Reboiler Specifications

Using the flows that were calculated in steady state as a design basis, the reboiler, will now be sized.

49. Press F3 to open the Object Navigator.

50. In the Flowsheets group, select DeButanizer.

Figure 2.9

2-11


2-12

51. In the Unit Operations group, choose Reboiler.


53. Select the Worksheet tab, Conditions page on the Reboiler property view and make a note of the liquid volume flow of the stream To Reboiler.

For a quick sizing calculation, use a flow of 1800 ft3/hr, a 10 minute residence time and a liquid operating level of 50%.

54. On the Dynamics tab, Specs page of the Reboiler property view, delete the value in the Volume field.

55. Input a Diameter of 8 ft and a Length of 12 ft. This will enable you to obtain a volume of approximately 600 ft3.

56. A horizontal unit will be used for the Reboiler. Ensure that Horizontal cylinder is selected for the Level Calculator.

57. Close the reboiler property view.

1800ft3hr-------

1hr60min----------------× 10min

10.5-------×× 600ft3=

Figure 2.10


Test the Model

At this point, the condenser and reboiler have both been sized and enough pressure-flow specifications have been set to reduce the degrees of freedom to zero. You can confirm that all the necessary pressure flow specifications have been added using the Equation Summary View view.

58. Select the Equation Summary View from the Simulation drop down menu.

59. On the Summary page, press the Full Analysis button to confirm that the case is properly defined for dynamic simulation.

60. Close the Equation Summary View view.

Tray Section

For the sizing of the tray section, a quick Auto-Section will be performed using the Tray Sizing utility. HYSYS will determine a tray diameter based on Glitsch design parameters for valve trays.

Using the Tray Sizing Utility

61. Use the hot key combination CTRL U to open the Utilities view.

62. Select Tray Sizing from the list of utilities and press the Add Utility button.

63. On the Tray Sizing property view, press the Select TS button to attach the DeButanizer tray section.

64. Select DeButanizer from the Flowsheet group and Main TS from the Object group on the Select Tray Section dialog.

65. Press the OK button.

66. Press the Auto Section button on the Tray Sizing property view.

For this tray sizing analysis, all HYSYS defaults will be used. This will provide a good initial estimate of the tray diameter required for the DeButanizer tower.

67. Press the Next button on the Auto Section Information view.

You can review the default design parameters on the Tray Section Information view.

68. Since all default design parameters will be used for this analysis, press the Complete AutoSection button.

Note that the Valve has been selected as the default tray type.

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2-14

69. On the Results page of the Performance tab, you will notice the Section Pressure Drop that HYSYS has calculated. This value is less than the original pressure profile input for the tower DeButanizer. You will modify this later.

70. In the same table, notice that HYSYS has calculated a section diameter of 4.5 feet.

71. Close the Tray Sizing utility view first and then the Available Utilities view.

Modifying the Tray Section Parameters72. Press F3 to open the Object Navigator.

73. In the Flowsheets group, select DeButanizer.

74. In the Unit Operations group, choose Main TS.

75. Click on the View button.

Figure 2.11

Figure 2.12


76. On the Main TS property view, select the Rating tab, Sizing page.

77. Supply a tray Diameter of 4.5 feet in the Tray Dimensions group.

78. Close the Main TS tray section view.

The pressure profile of the tray section will be modified to match more closely the results obtained from the tray sizing utility.

79. Open the DeButanizer column property view and select the Profiles page of the Parameters tab.

80. Change the pressure in the Reboiler to 211 psia.

81. Change the pressure of 15_Main TS (tray 15) to 209 psia.

82. Close the column property view.

Setting up the Controllers

Controllers will be added to the flowsheet to control the levels in the condenser and reboiler. Although these controllers are not required to run in Dynamic mode, they will increase the realism and provide more model stability.

83. Make sure that you are in the Parent Environment.

84. Add a PID CONTROLLER which will serve as the condenser level controller and specify the following details:

85. Press the Control Valve button on the Cond LC property view.


Connections

Name Cond LC

Process Variable Source

Condenser@COL1 - Liquid Percent Level

Output Target Object Butanes@COL1

Parameters [Configuration]

Action Direct

Kc 2

Ti 5 minutes

PV Minimum 0%

PV Maximum 100%

PID Controller Button

2-15


2-16

86. In the Valve Sizing group on the FCV for Butanes@COL1 view, specify the following:

87. Close the FCV for Butanes view.

88. Press the Face Plate button.

89. Change the controller mode to Auto on the face plate.

90. Input a set point of 50%.

91. Add a PID CONTROLLER which will serve as the reboiler level controller and specify the following details:

92. Press the Control Valve button on the Reb LC property view.

Input Area Entry

Flow Type LiqVolFlow

Min Flow 0 ft3/hr

Max Flow 660 ft3/hr

Figure 2.13

Adjust the red indicatorA

ORDouble click in the PV cell and type in the specified value.


Connections

Name Reb LC


Reboiler@COL1 - Liquid Percent Level

Output Target Object C5+@COL1


Action Direct

Kc 2

Ti 5 minutes

PV Minimum 0%

PV Maximum 100%



93. In the Valve Sizing group on the FCV for C5+@COL1 view, specify the following:

94. Close the FCV for C5+ view.




You may have to re-initialize both controllers by switching the modes to Manual and then back to Automatic.

98. Save the case as DFTut1.hsc.

This case will be used as the starting point for the rating dynamics section.

Monitoring in Dynamics

Now that the model is ready to run in Dynamic mode, a strip chart can be created to monitor the general trends of key variables.

99. Open the Databook by using the hot key combination CTRL D.

100. On the Variables tab, press the Insert button.

101. Add all of the variables that you would like to monitor.

A list of suggested variables is given below:

102. After all variables have been added, close the Variable Navigator.

103. Select the Strip Charts tab from the Databook view.

104. Press the Add button.

Input Area Entry

Flow Type LiqVolFlow

Min Flow 0 ft3/hr

Max Flow 750 ft3/hr

Variables To Manipulate Variables To Monitor

Pressure of Vent Control Condenser Liquid Percent Level

Liquid Volume Flowrate of Feed 1 Reboiler Liquid Percent Level

Liquid Volume Flowrate of Feed 2 Liquid Volume Flowrate of Butanes

SP for Cond LC and/or Reb LC Liquid Volume Flowrate of C5+

2-17


2-18

105. Check the Active check box for each of the variables that you would like to monitor.

106. If required, add more strip charts.

107. Change the configuration of each strip chart by pressing the Setup button.

108. On the Strip Charts tab in the Databook, highlight the data logger and press the Strip Chart button to display each data logger.

109. Close the DataBook view.

110. Start the integrator and allow the variables to line out and then stop the integrator.

111. If you have performed an analysis or manipulation, save your case as DFTut2.hsc and close it.

Rating Dynamics

For the rating dynamics section, the condenser unit operation will be replaced by an overhead system consisting of various pieces of equipment.

112. Open the case DFTut1.hsc.

Start Integrator Button (green)

Stop Integrator Button (red)

These two buttons are side by side on the button bar. The Start Integrator button is on the left and the Stop Integrator button is on the right.

Figure 2.14


This case was saved at a point prior to any extensive design dynamics integration.

Deleting the Condenser

Before the condenser is deleted in the column environment, its associated product streams and energy stream will be removed in the Main Simulation Environment.

113. If the pfd is not already displayed, press the PFD button in the button bar.

114. Use the multiple selection functionality to highlight the streams Vent Control, Cond Q and Butanes and the controller Cond LC.

• Place the mouse pointer on the PFD background. Click and hold down the primary mouse button while dragging the pointer to make a box around the objects you want to select.

115. Press the DELETE key. Press the OK button when asked for confirmation of deletion of all four objects. Press the Yes button for each subsequent object deletion confirmation.

Now enter the column environment:

116. Press F3 to open the Object Navigator.

Figure 2.15

PFD Button

2-19


2-20

117. Select DeButanizer in the Flowsheets group.

118. Press the Build button to enter the Column Sub-Flowsheet environment.

119. If the pfd is not already displayed, press the PFD button on the button bar.

120. Create a new stream and give it the same properties as the To Condenser stream. This may be done by clicking the Define from Other Stream button. Click OK on the Spec Stream As view.

121. Repeat step # 120 for the Reflux stream.

122. Object inspect the condenser and select Delete from the object inspection menu.

123. Confirm that you want to delete the Condenser by pressing the Yes button.

124. Transfer the information back from streams 1 and 2 to the To Condenser and Reflux streams respectively by using the Define from Other Stream button.

125. Delete streams 1 and 2.

Figure 2.16

To quickly re-arrange the PFD, select Auto Position All under PFD in the menu bar.

Object Inspect by selecting the object and then clicking the secondary mouse button.


Adding the Overhead System

Adjusting the Pressure-Flow Specs

It is important to keep track of the pressure-flow specifications for the flowsheet. If specifications are eliminated by deleting streams, an equivalent number of specifications must be added to keep the degrees of freedom at zero. Also, as equipment is added to the flowsheet, the pressure-flow specifications will be correspondingly moved to the boundary streams.

Since product streams and the condenser have been deleted, the flowsheet boundary streams have changed and thus, the pressure-flow specifications must be moved. In this case, two streams that had pressure-flow specifications were deleted so it is only a matter of adding specifications to the flowsheet.

126. Open the property view for the Reflux stream.

127. Select the Dynamics tab, Specs page.

128. De-activate the Pressure and Flow specifications.

129. Select the Ideal Liq Vol radio button.

130. Activate the Flow specification.

131. Close the Reflux property view.

132. Open the property view for the stream To Condenser.

133. Select the Dynamics tab, Specs page.

134. Check that the Flow specification is not active.

135. Activate the Pressure specification.

136. Close the To Condenser view.

Changing the Column Solving Method

Since equipment will be added to the column in the sub-flowsheet environment, the Solving Method of the column should be changed.

137. Open the Object Navigator by pressing F3.

It is recommended that you periodically save your case as equipment is added to the flowsheet. Using different case names will provide snapshots at various stages of building the case.

The Modified HYSIM Inside -Out method is used to allow you to add the MIXER, PUMP, TEE, and VALVE unit operations to the Column Sub-Flowsheet.

2-21


2-22

138. With the Unit Ops radio button selected in the Filter group, choose Case in the Flowsheets group and DeButanizer in the Unit Operations group.


140. Go to the Parameters tab, Solver page, on the DeButanizer property view.

141. In the Solving Method group, select Modified HYSIM Inside-Out, which allows various pieces of equipment to be added to the sub-flowsheet.

142. Close the DeButanizer property view.

Adding a Splitter

A TEE operation will be added to the flowsheet to separate the overhead vapour into a vapour bypass stream and an overhead stream which will be condensed.

Figure 2.17


Adding the Operation

143. Add a TEE operation, which will separate the column overhead into two product streams: a bypass vapour stream and a stream that will be condensed. Provide the following information:

Moving the P-F Specs

With the addition of the Splitter, the pressure-flow specifications must be adjusted.

144. Open the property view for the stream To Condenser.

145. On the Specs page of the Dynamics tab, de-activate the Pressure specification.

146. Close the To Condenser view.

147. Open the Bypass to Valve property view.

148. On the Dynamics tab, Specs page, make sure the pressure specification is deactivated and the Flow specification is activated. Ensure that the Molar flow radio buttons has been selected.

149. On the Worksheet tab, Conditions page, supply a Molar Flow of 50 lbmole/hr.

150. Close the Bypass to Valve view.

151. Open the Ovhd property view.

152. On the Dynamics tab, Specs page, ensure that the Flow specification is inactive and that the Pressure specification is active.

153. Close the Ovhd view.

154. Start the integrator for a few minutes of integration to propagate the values to the boundary streams. If asked to resolve the items identified by the dynamics assistant, click the No button.

155. Stop the integrator.



Name Splitter

Feed To Condenser

Products Bypass to Valve

Ovhd

Dynamics [Specs] Use splits as dynamic flow specs

Inactive

2-23


2-24

Adding Two Valves

156. One VALVE operation will be added to each of the streams exiting the Splitter.

Adding the Operations

157. Add a VALVE and supply the following information:

158. Switch to the Rating tab, Sizing page.

159. Press the Size Valve button.

160. Return to the Dynamics tab, Specs page and de-activate the Total Delta P check box in the Dynamic Specifications group.

The Total Delta P check box was used to initialize a pressure drop for the valve. This pressure drop, along with the flow rate through the equipment was then used by HYSYS to calculate a value of Cv. Since the valve behaviour will be defined using a pressure-flow relationship, the Total Delta P specification was no longer required.

The Specs page on the Dynamics tab should appear as shown in Figure 2.19.

161. Close the valve property view.

Figure 2.18



Name Bypass Valve

Feed Bypass to Valve

Product Vapour Bypass

Dynamics [Specs]Total Delta P Activate check box

Total Delta P 5 psi

VALVE Button

Since the length of time that the integrator is left to run in step #135 will vary, the value of Cv may not be exactly as shown in Figure 2.19, but nonetheless, it should be close.


162. Add another VALVE and supply the following information:

163. Switch to the Rating tab, Sizing page.


165. Return to the Dynamics tab, Specs page and de-activate the Total Delta P check box in the Dynamic Specifications group.


167. Start the integrator for 10 seconds to propagate values to the new streams. If asked to resolve the items identified by the dynamics assistant, click the No button.



With the addition of the two valves, the pressure-flow specifications will be moved to the flowsheet boundary streams.

169. Open the property view for the stream Bypass to Valve.

Figure 2.19



Name Ovhd Valve

Feed Ovhd

Product To Exchanger

Dynamics [Specs]Total Delta P Activate check box

Total Delta P 5 psi

2-25


2-26

170. On the Dynamics tab, Specs page, de-activate the Flow specification.

171. Close the Bypass to Valve view.

172. Open the property view for the stream Ovhd.

173. On the Dynamics tab, Specs page, de-activate the Pressure specification.

174. Close the Ovhd view.

175. Open the Vapour Bypass property view.

176. On the Dynamics tab, Specs page, activate the Pressure specification.

177. Close the Vapour Bypass view.

You may have noticed that a flowrate specification was being used on the stream Bypass to Valve and a pressure specification is now used for the stream Vapour Bypass. This will not have a significant effect on the flow through the Bypass Valve. The Bypass Valve was sized using the formerly specified flow and a set pressure drop of 5 psi, so using the newly calculated outlet pressure as a specification will keep the flowrate through the valve close to its former value.

178. Open the To Exchanger property view.


180. Close the To Exchanger view.


Attaching the Condenser

A HEAT EXCHANGER operation will be used to model the condenser. A propane refrigerant stream will be created and will be used as the shell side coolant.

In general, when a flowsheet boundary stream is directly attached to a piece of equipment that uses Cv or conductance to determine its pressure-flow relationship, use pressure instead of flow as the specification on the boundary stream.

HYSYS.Plant will use the equipment conductance or Cv value combined with the pressures of the inlet and outlet streams to determine a flow though the equipment.


Adding the Propane Stream

182. In the Workbook, create a new material stream named Propane In.

183. Open the property view for Propane In.

Since the model is in Dynamic mode, the stream is initialized by HYSYS. The temperature, pressure and flowrate are specifiable and are shown in blue. For the Propane In stream, the parameters to be input for defining the stream include the vapour fraction, pressure and flowrate. To change the flash specifications, follow these steps:

184. On the Worksheet tab, Composition page, specify a propane mass fraction of 1.0.

185. On the Worksheet tab, Conditions page, delete the temperature specification.

186. Enter the following:

The Conditions page for Propane In should appear as shown:


Adding a Valve

A pressure-flow relationship will be applied to the propane refrigerant stream by adding a VALVE unit operation to the coolant stream.

Figure 2.20


Worksheet [Conditions]

Vapour/Phase Fraction 0.0000

Pressure 160 psia

Molar Flow 2200 lbmole/hr

2-27


2-28

188. Add a VALVE to the flowsheet and provide the following information:

HYSYS provides a sizing flow rate, which is the mass flow through the valve. The sizing pressure drop does not appear because a pressure drop has not been set for the unit.

189. Input a Sizing Delta P of 15 psi.


Figure 2.21



Name Propane Valve

Feed Propane In

Product Shell In

Rating [Sizing(dynamics)]

Delta P 15 psi


The Rating tab, Sizing page should appear as shown:


Adding the Condenser

192. Add a HEAT EXCHANGER unit operation.

193. Complete the property view with the details given in the following table:

194. Close the heat exchanger property view.

Figure 2.22



Name Condenser

Tube Side Inlet To Exchanger

Tube Side Outlet To Accumulator

Shell Side Inlet Shell In

Shell Side Outlet Propane Out

Rating [Sizing]

Tube Side Delta P 0.45 psi

Shell Side Delta P 0.45 psi

UA 1.6E+05 Btu/F-hr

Dynamics [Model]

Model Basic

Tube Volume 10 ft3

Shell Volume 50 ft3

2-29


2-30


With the addition of the valve and heat exchanger, the pressure-flow specifications will be moved to the flowsheet boundary streams. Also, the heat exchanger will use conductance values instead of fixed pressure drops.

195. Start the integrator for a few integration minutes to propagate information to the new streams. If asked to resolve the items identified by the dynamics assistant, click the No button.


For the streams:

197. Open the property view for the stream To Exchanger.

198. On the Dynamics tab, Specs tab, de-activate the Pressure specification.

199. Close the To Exchanger view.

200. Open the property view for the stream To Accumulator.


202. Close the To Accumulator view.

203. Open the property view for Propane In.

204. On the Dynamics tab, specs page, de-activate the Flow specification and ensure that the Pressure specification is activated.

205. Close the Propane In view.

206. Open the property view for Propane Out.


208. Close the Propane Out view.

The refrigerant stream is passing through a valve, which is using a Cv for its pressure-flow relationship, and the shell side of a heat exchanger, which will be using a conductance for its pressure-flow relationship. Therefore, the boundary streams of the refrigerant (propane) process both use pressure specifications, which allows HYSYS.Plant to determine the flow through the equipment.

For the Condenser:

209. Open the property view for the Condenser.


210. On the Dynamics tab, Specs page, press the Calculate k button.

The conductance values for both the Shell Side and Tube Side are calculated according to the specified pressure drops and flowrates through the specific sides of the exchanger.

211. For both the Shell Side and Tube Side, de-activate the Delta P check box and activate the k check box.

212. Start the integrator for a few integration minutes and observe the pressures and flowrates of Propane Out, To Accumulator and Vapour Bypass. If asked to resolve the items identified by the dynamics assistant, click the No button.



Adding the Accumulator

A SEPARATOR unit operation will be used as the overhead accumulator. Both the vapour bypass stream and the cooled overhead stream will be used as feeds to the unit. Since one feed is vapour and the other is liquid, non-equilibrium phase behaviour will be taken into account by lowering the vapour phase efficiencies of the separator. When the two feeds enter, the liquid will immediately fall and the vapour will rise, so the lowered efficiencies will incorporate these mass transfer effects into the calculations. The size of the accumulator will be the same as that of the condenser in the design dynamics section.

Stream properties can be seen by placing the cursor over the stream icon in the PFD.

Figure 2.23

2-31


2-32


215. Add a SEPARATOR and provide the following information:

The vapour phase efficiencies will now be changed for the accumulator:

216. On the Dynamics tab, Holdup page of the Accumulator, press the Advanced button.

217. For all relevant vapour efficiencies on the Efficiencies tab, provide a value of 1%.

Since there is no vapour for the product stream Sep Liquid, the efficiency is left at 100%. The completed Efficiencies tab is shown in Figure 2.24.



Name Accumulator

Feeds Vapour Bypass

To Accumulator

Vapour Outlet Sep Vapour

Liquid Outlet Sep Liquid

Dynamics [Specs]

Level Calculator Horizontal Cylinder

Diameter 10 ft

Length 15 ft

Holdup Initialization Dry Startup

Figure 2.24


218. Close the Accumulator views.


Since the Accumulator is being modelled with a dry startup initialization, the pressure-flow specifications will be moved and the integrator will be started so that the vessel fills with liquid.

219. Open the property view for the stream To Accumulator.

220. On the Dynamics tab, Specs tab, de-activate the Pressure specification.

221. Close the To Accumulator view.

222. Open the property view for the stream Sep Liquid.

223. On the Dynamics tab, Specs tab, activate the Flow specification and input a flow rate of 0.0 lbmole/hr

With no liquid flow exiting the separator, the liquid level in the vessel will begin to rise when the integrator is started.

224. Close the Sep Liquid view.

225. Start the integrator. If asked to resolve the items identified by the dynamics assistant, click the No button.

On the PFD, place the cursor over the Accumulator to monitor the liquid percent level.

226. Stop the integrator when the level reaches approximately 65%.

Adding the Vapour Product Valve

A VALVE unit operation will be added to the flowsheet so adjustments can be made to the vapour stream from the Accumulator.


227. Add a VALVE and provide the following information:228. Close the valve property view.

The pressure-flow relation will be temporarily replaced by a fixed pressure drop specification so that information can be propagated to the Vent Control stream and so that the Vent Valve can be sized.

229. Start the integrator for a few seconds.

2-33


2-34


231. Open the property view for Vent Valve.

232. On the Rating tab, Sizing page, press the Size Valve button.

233. On the Dynamics tab, Specs page, activate the Pressure flow relation check box and de-activate the Pressure drop check box.


Changing the P-F Specs

Now that the Accumulator has been filled and the Vent Valve has been sized, the pressure-flow specifications can be modified. The pressure specification on the vapour bypass will be replaced by a pressure specification on the Vent Control stream. Also, stream information will be propagated to the stream Sep Liquid by increasing its flow specification.

235. Open the property view for the stream Vapour Bypass.

236. On the Dynamics tab, Specs page, de-activate the Pressure specification.

Figure 2.25



Name Vent Valve

Feed Sep Vapour

Product Vent Control

Dynamics [Specs]

Pressure flow relation De-activate check box

Pressure drop Activate check box

Pressure drop 15 psi


237. Close the Vapour Bypass view.

238. Open the property view for the stream Vent Control.


240. On the Worksheet tab, Conditions page, specify a Pressure of 180 psia.

241. Close the Vent Control view.


243. On the Worksheet tab, Conditions page, specify a Molar Flow of 1075 lbmole/hr.


245. Start the integrator for about 10 seconds to propagate values to the Sep Liquid stream.



Adding a Liquid Splitter

Add a TEE operation to the flowsheet. The liquid product from the Accumulator will be split into streams that will eventually form the distillate and reflux streams.

Figure 2.26

2-35


2-36


248. Add a TEE and provide the following information:


With the addition of the Liquid Splitter, the pressure-flow specification on the Sep Liquid stream will be moved to the Liquid Splitter outlet streams.


250. On the Dynamics tab, Specs page, de-activate the Flow specification.


252. Open the property view for the stream To Distillate.

253. On the Dynamics tab, Specs page, activate both the Pressure and Flow specifications.

254. Select the Ideal LiqVol radio button.

255. On the Worksheet tab, Conditions page, specify a Pressure of 195 psia and a Liquid Volume Flow of 350 ft3/hr.

256. Close the To Distillate view.

257. Start the integrator for 10 seconds.


Adding a Liquid Product Valve

A VALVE unit operation will be added to the flowsheet so adjustments



Name Liquid Splitter

Feed Sep Liquid

Products To Distillate

To Pump

Dynamics [Specs] Use splits as dynamic flow specs

Deactivate check box

TEE Button


can be made to the vapour stream from the Accumulator.


259. Add a VALVE and provide the following information:

The pressure-flow relation will be temporarily replaced by a fixed pressure drop specification so that information can be propagated to the Butanes stream and so that the Distillate Valve can be sized.

260. Close the Distillate Valve property view.



263. Open the property view for Distillate Valve.



266. Close the Distillate Valve property view.

Figure 2.27



Name Distillate Valve

Feed To Distillate

Product Butanes

Dynamics [Specs]




2-37


2-38


The Distillate Valve has been sized so the pressure-flow specifications can be modified.

267. Open the property view for the stream To Distillate.

268. On the Dynamics tab, Specs page, de-activate both the Pressure and Flow specifications.

269. Close the To Distillate view.

270. Open the property view for the stream Butanes.


272. Close the Butanes view.

273. Open the property view for To Pump.

274. On the Dynamics tab, Specs page, activate the Flow specification.

275. On the Worksheet tab, Conditions page, specify a Molar Flow of 925 lbmole/hr.

276. Close the To Pump view.



279.Save the case as DFTut6.hsc.

Check the molar flow of the stream Reflux. The flow specification for the stream To Pump should closely match this value, since the two streams will eventually be joined. Model stability will be enhanced if the flows are similar.


Adding the Pump

A PUMP unit operation will be added to the flowsheet to increase the pressure of the stream returning to the tower.


280. Add a PUMP operation and provide the following information:

281. On the Dynamics tab, Specs page, de-activate the check box for Pressure rise.

282. Activate the check box for Head.

283. Specify a Head of 100 ft.

The Dynamics Info group should appear as shown:

284. Close the Reflux Pump property view.

The pressure-flow specifications will be left as they are.

285. Open the Accumulator property view.

Figure 2.28



Name Reflux Pump

Inlet To Pump

Outlet Pump Outlet

2-39


2-40

286. Open the Dynamics tab, Specs page and specify a Liquid Volume Percent of 50%.

287. Close the Accumulator property view.

To propagate stream information into Pump Outlet, the integrator will be started.



Figure 2.29

If the Liquid Volume Percent in the Accumulator falls too low (i.e. below 20%), just open the property view and re-specify it as 50%.

If required, adjust the Head specification such that the Pressure of Pump Outlet is at least 5 psi great than that of Reflux.


Adding a Reflux Valve

A VALVE unit operation will be added to the flowsheet to connect the streams Pump Outlet and Reflux. This last piece of equipment will close the overhead condenser loop.



291. Close the Reflux Valve property view.

The pressure-flow relation will be temporarily disabled so that information can be propagated through the Reflux Valve. You will notice that the Pressure drop check box does not need to be activated since there are already two P-F specifications downstream of the Liquid Splitter. By activating the Pressure drop check box for the Reflux Valve, the pressure flow solver would be overspecified.



Figure 2.30



Name Reflux Valve

Feed Pump Outlet

Product Reflux

Dynamics [Specs] Pressure flow relation De-activate check box

HYSYS.Plant assists you when you connect the Reflux Valve. The P-F specification for volume flow on Reflux is eliminated as soon as the product is attached to the valve. Open the Reflux property view to check this.

2-41


2-42

Sizing the Reflux Valve

294. Open the property view for Reflux Valve.

295. On the Dynamics tab, Specs page, activate the Pressure flow relation check box.

296. On the Rating tab, Sizing page press the Size Valve button.

Now that the pressure-flow relationship has been activated for the Reflux Valve, the pressure-flow solver is overspecified.


With the Reflux Valve using its pressure-flow relationship as a specification, one specification must be eliminated from the flowsheet.

297. Open the property view for the stream To Pump.

298. On the Dynamics tab, de-activate the Flow specification.

299. Close the To Pump property view.

Now that the overhead system is in place, a current list of the pressure-flow specifications can be provided. Since the dynamic behaviour of all pieces of equipment in the overhead system will be defined by pressure-flow relationships, there should be one pressure-flow specification per flowsheet boundary stream. The one extra specification that arose due to the splitting of the liquid stream from the Accumulator into reflux and distillate was no longer needed when Pump Outlet was connected to Reflux. The stream Reflux ceased being a flowsheet boundary stream and became an internal flowsheet stream, eliminating the requirement of maintaining the pressure-flow specification.

The current P-F specifications are listed:

Spec Holder P-F Specification

Feed 1 Molar Flow

Feed 2 Molar Flow

Vent Control Pressure

Butanes Pressure

C5+ Molar Flow


Add A Top Pressure Controller

A PID CONTROLLER will be added to the flowsheet to stabilize the model. The pressure of the stream To Condenser will be controlled by manipulating the Ovhd Valve.

First, you can delete the Reboiler LC since other controllers will be added to the model further on in the tutorial. You must return to the Main Environment to delete the controller.

Deleting the Old Reboiler Controller

All controllers will be added to the column sub-flowsheet, so the controller for the reboiler level that was created in the design dynamics section will be deleted.

300. Press the Parent Simulation Environment button to return to the Main Environment.

301. On the PFD, select the controller REB LC.

302. Press the DELETE key.

303. Press the Yes button to confirm the deletion of the controller.

304. Return to the Column Environment.

Adding the Top Stage Pressure Controller

305. Add a PID CONTROLLER which will serve as the top stage pressure controller and specify the following details:



Enter Parent Simulation Environment Button

To return to the Column Environment, press F3 to open the Object Navigator. Select DeButanizer in the Flowsheets column and press the Build button.


Connections

Name Top PC


To Condenser; Pressure

Output Target Object Ovhd Valve


Action Direct

Kc 1

Ti 5 minutes

Pv Minimum 182 psia

PV Maximum 232 psia

2-43


2-44

308. Input a set point of 207 psia.

Allow the Model to Stabilize

309. Start the integrator and allow it to run until the top stage pressure set point is reached.



Adding Valves to the Feeds and Bottoms Product

For the sake of completeness, a VALVE unit operation will be added to each of the feed streams and to the bottoms stream from the reboiler.

Figure 2.31


Adding the Bottoms Valve

The first valve that will be added is that for the bottoms stream.

312. On the PFD, object inspect the stream line between the Reboiler and the stream C5+.

313. Select Break Connection.


315. Close the Bottom Valve property view.

Figure 2.32



Name Bottoms Valve

Feed From Reboiler

Product C5+

Dynamics [Specs]




2-45


2-46

316. To connect the stream From Reboiler to the Reboiler proceed as follows or as illustrated in Figure 2.33:

317. With the PFD open, press and hold down the CTRL key.

318. Place the cursor over the stream From Reboiler and you will see its inlet connection square.

319. Place the cursor over the inlet connection square.

320. Press and hold the primary mouse button as you drag the cursor toward the liquid outlet of the Reboiler. As you approach the Reboiler, its outlet connection square will become available.

Move the cursor over the Reboiler liquid outlet connection square and release the mouse button.

321. Open the C5+ stream property view.


323. Close the C5+ property view.

324. Start the integrator for 10 seconds to propagate values to C5+.


Figure 2.33


326. Open the property view for the Bottoms Valve.On the Rating tab, Sizing page, press the Size Valve button.



Adding the Feed Valves

Feed 2

To break the feed connections from the PFD, you must be in the Column Sub-Flowsheet environment.

329. On the PFD, break the connection between Feed 2 and the Main TS.


331. Open the property view for Main TS.

332. On the Design tab, Connections page, attach the stream Feed 2 to Tower in the Optional Feeds group and specify 4_Main TS as the entry tray.

333. Close the Main TS property view.

334. Start the integrator for 10 seconds to propagate information.


336. Open the property view for Feed 2 Valve.



339. Open the Feed 2 Valve property view.



Name Feed 2 Valve

Feed Feed 2

Product Feed 2 to Tower

Dynamics [Specs]




2-47


2-48

Feed 1

340. On the PFD, break the connection between Feed 1 and the Main TS.


342. Open the property view for Main TS.

343. On the Design tab, Connections page, attach the stream Feed 1 to Tower in the Optional Feeds group and specify 8_Main TS as the entry tray.


345. Start the integrator for 10 seconds to propagate information.


347. Open the property view for Feed 1 Valve.



350. Close the Feed 1 Valve property view.


The flow specifications for both feeds and the bottoms product will be replaced by pressures specifications. With pressures being specified, HYSYS.Plant will use the sized valves that were just added to determine the flowrates of the corresponding streams.

351. Return to the Main Environment by pressing the Parent Simulation Environment button.

352. Open the property view for Feed 1.

353. On the Dynamics tab, de-activate the Flow specification and activate the Pressure specification.

354. Close the Feed 1 view.



Name Feed 1 Valve

Feed Feed 1

Product Feed 1 to Tower

Dynamics [Specs]





355. Repeat steps #352 to #354 for Feed 2.

356. Open the property view for C5+.

357. On the Dynamics tab, activate the Pressure specification.

358. Close the C5+ view.

359. Return to the column sub-flowsheet environment.


Adding the Controllers

Five more PID CONTROLLERS will be added to the Column Sub-Flowsheet to control various aspects of the model. Controlled variables include:

• Reboiler liquid level• Accumulator liquid level• Tray 6 temperature• Pressure of the vapour bypass• Reflux flow rate

Adding the Accumulator Level Controller

361. Add a PID CONTROLLER, which will serve as the Accumulator level controller and specify the following details:





Connections

Name Accumulator LC


Accumulator - Liquid Percent Level

Output Target Object Distillate Valve


Action Direct

Kp 2

Ti 5 minutes

PV Minimum 0%

PV Maximum 100%

2-49


2-50

Adding the Reboiler Level Controller

365. Add a PID CONTROLLER, which will serve as the Reboiler level controller and specify the following details:




Adding the Reflux Flow Controller

369. Add a PID CONTROLLER, which will serve as the Reflux flow controller and specify the following details:



372. Input a set point of 610 lbmole/hr.


Connections

Name Reboiler LC


Reboiler - Liquid Percent Level

Output Target Object Bottoms Valve


Action Direct

Kp 2

Ti 5 minutes

PV Minimum 0%

PV Maximum 100%


Connections

Name Reflux FC


Pump Outlet - Molar Flow

Output Target Object Reflux Valve


Action Reverse

Kp 0.2

Ti 0.1 minutes

PV Minimum 0 lbmole/hr

PV Maximum 1300 lbmole/hr


Adding the Tray 6 Temperature Controller

373. Add a PID CONTROLLER which will serve as the tray 6 temperature controller and specify the following details:

374. Press the Control Valve button on the Tray 6 TC property view.

375. In the Direct Q group on the FCV for Reb Q view, specify the following:

376. Close the FCV for Reb Q view.



379. Input a set point of 235 F.



Now that the model is ready to run in Dynamic mode, a strip chart can be created to monitor the general trends of key variables.


382. On the Variables tab, press the Insert button.

383. Add all of the variables that you would like to monitor.


Connections

Name Tray 6 TC


Main TS - Stage Temperature - Tray 6

Output Target Object Reb Q


Action Reverse

Kp 0.5

Ti 5 minutes

PV Minimum 225 F

PV Maximum 245 F

Input Area Entry

Min Available 0 Btu/hr

Max Available 1.2E+07 Btu/hr

2-51


2-52



385. Select the Strip Charts page from the Databook view.

386. Press the Add button.


388. If required, add more strip charts.


390. On the Strip Charts tab in the Databook, press the Strip Chart button to view each strip chart.

391. Close the DataBook view.

392. Start the integrator and allow the variables to line out.

393. Perform an analysis by manipulating variables and viewing the responses of the other variables.

Variables To Manipulate Variables To Monitor

Pressure of Vent Control Accumulator Liquid Percent Level

Liquid Volume Flowrate of Feed 1 Reboiler Liquid Percent Level

Liquid Volume Flowrate of Feed 2 Stage 6 Temperature

SP for Accumulator LC and/or Reboiler LC

Vapour Bypass Pressure

Temperature of Feed 1 or Feed 2

Gas Processing Tutorial 3-1

3 Gas Processing Tutorial

The simulation will be built using these basic steps:

1. Create a unit set.

2. Choose a property package.

3. Select the components.

4. Create and specify the feed streams.

5. Install and define the unit operations prior to the column.

6. Install and define the column.

In this Tutorial, a natural gas stream containing N2, CO2, and C1 through nC4 is processed in a refrigeration system to remove the heavier hydrocarbons. The lean, dry gas produced will meet a pipeline hydrocarbon dew point specification. The liquids removed from the rich gas are processed in a depropanizer column, yielding a liquid product with a specified propane content. A flowsheet for this process is shown below.

The following pages will guide you through building a HYSYS case for

This complete case has also been pre-built and is located in the file TUTOR1.HSC in your HYSYS\SAMPLES directory.

Figure 3.1

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3-2 Gas Processing Tutorial

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modelling this process. This example will illustrate the complete construction of the simulation, from selecting a property package and components, to installing streams and unit operations, through to examining the final results. The tools available in HYSYS interface will be utilized to illustrate the flexibility available to you.

Beginning the Simulation1. To start a new simulation case, do one of the following:

• Select New Case from the File menu.• Press the New Case button.

The Simulation Basis Manager appears:

2. You need to set your Session Preferences before building a case. To access the Session Preferences view, open the Tools menu.

3. Select Preferences. The Session Preferences view appears.

Figure 3.2


New Case Button

Notice that HYSYS displays the current Environment and Mode in the upper right corner of the view. Whenever you begin a new case, you are automatically placed in the Basis Environment, where you can define your property package and components.

The Simulation Basis Manager allows you to create, modify, and otherwise manipulate Fluid Packages in your simulation case. Most of the time, as with this example, you will require only one Fluid Package for your entire simulation.


4. You are now on the Options page of the Simulation tab. De-activate the Use Modal Property Views by clicking on the check box.


The first step in building the simulation case is choosing a unit set. HYSYS does not allow you to change any of the three default unit sets listed. However, you can create a new unit set by cloning an existing one. For this example, a new unit set will be made based on the HYSYS Field set, which you can then customize. To create a new unit set:

1. Click on the Variables tab in the Session Preferences view.

2. Select the Units page if it is not already selected.

3. In the Available Unit Sets group, select Field to make it the active set.

4. Press the Clone button. A new unit set named NewUser appears and becomes automatically highlighted, making it the Available Unit Set. If you wish, you can enter a new name in the Unit Set Name cell. You can now change the units for any variable associated with this new unit set.

5. In the Display Units group, notice the default unit for Flow is lbmole/hr. A more appropriate unit for this example is MMSCFD.

Figure 3.3

The default Preference file is named HYSYS.prf. When you modify any of the preferences, you can save the changes in a new Preference file by pressing the Save Preference Set button. HYSYS prompts you to provide a name for the new Preference file, which you can load into any simulation case by pressing the Load Preference Set button.

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6. At the top of the Session Preferences view is a drop-down list of available units in the Edit Bar by clicking on or by pressing the F2 key and then the i key.

7. Scroll through the list and select MMSCFD, or scroll down using the arrow keys and press ENTER.

Your new unit set is now defined. Close the view using the close button (in the top right corner) to begin the simulation.

Figure 3.4

Figure 3.5


Creating a Fluid Package

The next step is to create a Fluid Package. As a minimum, a Fluid Package contains the components and property method (for example, an Equation of State) to be used by HYSYS in its calculations for a particular flowsheet. Depending on what is required in a specific flowsheet, a Fluid Package may also contain other information, such as reactions and interaction parameters.

1. Press the Add button, and the property view for your new Fluid Package appears.

The property view is divided into a number of tabs to allow you to supply all the information necessary to completely define the Fluid Package. For this example, only the first two tabs, Prop Pkg and Components will be used.

2. The choice of Property Package is made on the Prop Pkg tab. Notice the position of the highlight in the Base Property Package Selection group (currently located on <none>). There are a number of ways to select a base property package, in this case Peng Robinson. Do one of the following:p

• Start typing Peng Robinson, and HYSYS will find the match to your input.

• Use the h and i keys to scroll down the list of available property packages until Peng Robinson is highlighted.

Figure 3.6

HYSYS has created a Fluid Package with the default name Basis-1. You can change the name of this fluid package by typing a new name in the Name cell at the bottom of the view.

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• Use the vertical scroll bar to move down the list until Peng Robinson becomes visible, then click on it.

Notice that the Property Pkg indicator at the bottom of the view now indicates Peng Robinson as the current property package for this Fluid Package.

As an alternative, you could have selected the EOSs radio button as the Property Pkg Filter, producing a list of only those property packages which are Equations of State. Peng Robinson could have then been chosen from this filtered list, as shown here.

You should normally leave the Component Selection Control at its default setting, Only Property Package Compatible Components. HYSYS will then filter the library components to include only those appropriate for the selected Property Package.

Selecting Components

Now that you have chosen the property package to be used in the simulation, the next step is to select the components.

Figure 3.7

Figure 3.8


1. Move to the Components tab by clicking on it, or by pressing CTRL SHIFT N.

There are a number of ways to select components for your simulation. One method is to use the matching feature. Notice that each component is listed in three ways:

At the top of each of these three columns is a corresponding radio button. Based on the selected radio button, HYSYS will locate the component(s) that best match the input you type in the Match cell.

For this example, N2, CO2, C1, C2, C3, iC4 and nC4 will be used as the components. To add nitrogen using the match feature:

2. Ensure the FullName/Synonym radio button is picked, and the Show Synonyms check box is checked.

3. Move to the Match cell by clicking it, or by pressing ALT M.

Figure 3.9

Matching Method Description

SimName The name appearing within the simulation.

FullName/Synonym IUPAC name (or similar), and synonyms for many components.

FormulaThe chemical formula of the component. This is useful when you are unsure of the library name of a component, but know its formula.

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4. Type N2. HYSYS will filter as you type, displaying only those components that match your input.

5. Now that Nitrogen is highlighted, add it to the Current Composition List by doing one of the following:

• Press the ENTER key.• Press the Add Pure button.• Double-click on Nitrogen (note that Nitrogen need not be

highlighted for this option).

In addition to the Match criteria radio buttons, you can also use the Family Filter to display only those components belonging to certain families. To add CO2 to the component list:

Figure 3.10

Figure 3.11


6. Ensure the Match cell is empty by pressing ALT M then the DELETE key.

7. Click on the Use Filter check box, then press the Family Filter button, and the Families view will appear.

8. CO2 does not fit into any of the standard families, so click on the Miscellaneous check box.

9. Scroll down the filtered list until CO2 is visible

10. Add CO2 to the component list by double-clicking on it. Note that the Match feature remains active when you are using a family filter, so you could also type CO2 in the Match cell and then add it to the component list.

To add the remaining components C1 through nC4, clear the Miscellaneous check box, and check the Hydrocarbons box. A quick way to add components which appear consecutively in the library list is to:

1. Click on the first component (in this case, C1).

2. Do one of the following:

• Hold down the SHIFT key and click on the last component, in this case nC4. All components C1 through nC4 will now be highlighted. Release the SHIFT key.

• Click and hold on C1, drag down to nC4, and release the mouse button. C1 through nC4 will be highlighted.

3. Press the Add Pure button. The highlighted components are transferred to the Current Component List.

The completed component list is shown below.

Figure 3.12

To highlight consecutive components, use the SHIFT key. To highlight non-consecutive components, use the CTRL key.

A component can be removed from the Current Components List by selecting it, and pressing the Remove Comps button or the DELETE key.

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Viewing Component Properties

To view the properties of one or more components, highlight the component(s) and press the View Comp button. HYSYS opens the property view(s) for the component(s) you selected. For example:

1. Click on CO2 in the Current Component List.

2. Press and hold the CTRL key.

3. Click on n-Butane. These two components should now be highlighted.

4. Release the CTRL key.

5. Press the View Comp button. The property views for these two components appears.

The Component property view provides you with complete access to the pure component information for viewing only. You cannot modify any parameters for a library component; however, HYSYS has an option for cloning a library component into a Hypothetical component, which can then be modified as desired. See Chapter 2 - Hypotheticals in the Simulation Basis manual for more information on cloning library components.

Close each of these component views to return to the Fluid Package. You could continue to add information to the Fluid Package, such as

Figure 3.13


interaction parameters and reactions. However, for the purposes of this example, the Fluid Package is now completely defined. Close the Fluid Package view to return to the Simulation Basis Manager.

Notice that the list of Current Fluid Packages displays the new Fluid Package, Basis-1, showing the number of components (NC) and property package (PP). The new Fluid Package is assigned by default to the main flowsheet, as shown in the Flowsheet-Fluid Pkg Associations group. Now that the Basis is defined, you can install streams and operations in the Main Simulation Environment.

To enter this environment and leave the Basis environment, do one of the following:

• Press the Enter Simulation Environment button on the Simulation Basis Manager view.

• Press the Simulation Environment button on the button bar.

Entering the Simulation Environment

When you enter the Simulation Environment, the initial view that appears is dependent on your current preference setting for the Initial Build Home View. Three initial views are available:

1. PFD

2. Workbook

3. Summary

Figure 3.14

If the Simulation Basis Manager is not visible, select the Home View button from the button bar.

Enter Simulation Environment Button

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Any or all of these can be displayed at any time; however, when you first enter the Simulation Environment, only one is displayed. For this example, the initial Home View is the PFD (HYSYS default setting).

You will notice several things about the Main Simulation Environment. In the upper right corner, the Environment has changed from Basis to Case (Main). A number of new items are now available on the Menu and Button Bar, and the PFD and Object Palette are open on the

Figure 3.15


Desktop. These latter two objects are described below.

Before proceeding any further to install streams or unit operations, it is a good idea to save your case.

Do one of the following:

• Click the Save button on the button bar.• Open the File menu and select Save.• Press CTRL S.

As this is the first time you have saved your case, the Save Simulation Case As dialog box will appear.

By default, the File Path is the Cases sub-directory in your HYSYS directory. To save your case:

1. In the File Name cell, type a name for the case, for example GASPLANT. You do not have to enter the .hsc extension; HYSYS will automatically add it for you.

Objects Description

PFD

The PFD is a graphical representation of the flowsheet topology for a simulation case. The PFD view shows operations and streams and the connections between the objects. You also have the option of attaching information tables or annotations to the PFD. By default, the view has a single tab. If you wish, you can add additional PFD pages to the view in order to focus in on the different areas of interest.

Object Palette A floating palette of buttons which can be used to add streams and unit operations.

Figure 3.16

You can toggle the palette open or closed by pressing F4, or by choosing Open/Close Object Palette from the Flowsheet menu.

Save Button

When you choose to open an existing case by pressing the

Open Case button , or by selecting Open Case from the File menu, a view similar to the one shown in Figure 3.16 will appear. The File Filter drop-down list will then allow you to retrieve backup (*.bk*) and HYSIM (*.sim) files in addition to standard HYSYS (*.hsc) files.

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2. Once you have entered a file name, press the ENTER key or the Save button. HYSYS will now save the case under the name you have given it when you save in the future. The Save As dialog box will not appear again unless you choose to give it a new name using the Save As command.

Before beginning stream or operation installation, the simulated process is summarized in the following section.

Process Description

This example will model a natural gas processing facility that uses propane refrigeration to condense liquids from the feed, and a distillation tower to process the liquids. The flowsheet for this process is shown below.

The combined feed stream enters an inlet separator, which removes the free liquids. Overhead gas from the SEPARATOR is fed to the gas/gas exchanger, where it is pre-cooled by already refrigerated gas. The cooled gas is then fed to the chiller, where further cooling is accomplished through exchange with evaporating propane (represented by the C3Duty stream). In the chiller, which will be modelled simply as a COOLER, enough heavier hydrocarbons condense such that the eventual sales gas meets a pipeline dew point specification. The cold stream is then separated in a low-temperature separator (LTS). The dry, cold gas is fed to the gas/gas exchanger and then to sales, while the condensed liquids are mixed with free liquids from the inlet separator. These liquids are processed in a depropanizer column to produce a low-propane-content bottoms product.

If you enter a name that already exists in the current directory, HYSYS will ask you for confirmation before over-writing the existing file.

Figure 3.17


Once the results for the simulation have been obtained, you will have a good understanding of the basic tools used to build a HYSYS simulation case. At that point, you can either proceed with the Optional Study presented at the end of the example, or begin building your own simulations.

In this example, three logical operations will be installed in order to perform certain functions that cannot be handled by standard physical unit operations:

The BALANCE operation will be installed in the main example. In the study, the ADJUST and SPREADSHEET operations will be installed to investigate the effect of the LTS temperature on the sales gas heating value.

The two primary building tools, Workbook and PFD, will be used to install the streams and operations and to examine the results while progressing through the simulation. Both of these tools provide you with a large amount of flexibility in building your simulation, and in quickly accessing the information you need.

The Workbook will be used to build the first part of the flowsheet, starting with the feed streams, up to and including the gas/gas heat exchanger. The PFD will be used to install the remaining operations, starting with the chiller, through to the column.

Using the Workbook

The Workbook displays information about streams and unit operations in a tabular format, while the PFD is a graphical representation of the flowsheet. Press the Workbook button on the button bar to ensure the Workbook window is active.

Logical Flowsheet Function

BALANCETo duplicate the composition of the SalesGas stream, in order to calculate its dew point temperature at pipeline specification pressure.

ADJUST To determine the required LTS temperature which gives a specified SalesGas dew point.

HYSYS SPREADSHEET

To calculate the SalesGas net heating value.

Workbook Button

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Installing the Feed Streams

In general, the first step when you enter the Simulation environment is to install one or more feed streams. To create a new stream:

1. Type the new stream name Feed 1 in the cell labelled **New** on the Material Streams tab of the Workbook. Note that HYSYS accepts blank spaces within a stream or operation name.

2. Press ENTER, and HYSYS will automatically create the new stream with the name you have given it. Your Workbook should appear as shown in .

The next step is to define the feed conditions. Notice that when you pressed ENTER after typing in the stream name, HYSYS automatically advanced the active cell down one, to Vapour Fraction.

1. Move to the Temperature cell for Feed 1 by clicking it, or by pressing the i key.

Figure 3.18


2. Type 60 in the Temperature cell, and notice your input appears in the Edit Bar at the top of the view.

In the Unit Box, HYSYS displays the default units for temperature, in this case F.

3. Since this is the correct unit, press the ENTER key or the Accept button, and HYSYS will accept the temperature.

Your active location should now be the Pressure cell for Feed 1. Suppose you know the stream pressure in another unit besides the default of psia, and you do not have quick access to the conversion factor. HYSYS will accept your input in any one of a number of different units, and automatically convert to the default for you. For example, the pressure of Feed 1 is 41.37 bar and to enter this pressure:

1. Type 41.37.

2. Press SPACE to move into the Units box and click on to open a scroll list of units.

3. Either scroll through the list to find bar, or begin typing it. HYSYS will now match your input to locate the unit of your choice.

4. Once bar is highlighted, press the ENTER key or the Accept button, and HYSYS will accept the pressure. Notice that it will automatically be converted to the default unit, psia.

Figure 3.19

Figure 3.20

Accept button

Edit bar

Units box

Accept Button

Active cell

Edit BarAccept button

Unit box

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The Molar Flow cell for Feed 1 should be selected in your Workbook. The next step is to enter the stream flow rate of 6 MMSCFD. Since the default Molar Flow unit for our unit set is MMSCFD, simply type 6 and press ENTER.

Providing Compositional Input

Now that the stream conditions have been specified, the next step is to input the composition:

1. Close the Workbook view. Now the PFD is visible with a light blue arrow on it. That arrow is the stream Feed 1 that we just created. Double-click on it to define its composition. The Feed 1 dialog appears.

2. Move to the Compositions page. The components are listed by Mole Fraction by default.

3. Move to the input cell for the first component, Nitrogen.

4. Type .01 press ENTER. HYSYS will display the Input Composition for Stream view, allowing you to complete the compositional input.

This view provides you with access to certain features designed to streamline the specification of a stream composition. Some of these features are:

Figure 3.21

The Input Composition for Stream view is Modal, indicated by the thick border and the absence of the Minimize/Maximize buttons in the upper right corner. When a Modal view is visible, you will not be able to move outside the view until you finish with it, by pressing either the Cancel, OK button.


1. Move to the input cell for CO2, type .01 and press ENTER. You are automatically advanced down by one cell each time you ENTER a new component fraction.

Composition Input Feature Description

Composition Basis Radio Buttons

You can input the stream composition in some fractional basis other than Mole Fraction, or by component flows, by picking the appropriate radio button before providing your input.

Normalizing

The Normalizing feature is useful when you know the relative ratios of components; for example, 2 parts N2, 2 parts CO2, 120 parts C1, etc. Rather than manually converting these ratios to fractions summing to one, simply enter the individual numbers of parts and press the Normalize button. HYSYS will compute the individual fractions totalling 1.0.

Normalizing is also useful when you have a stream consisting of only a few components. Instead of specifying zero fractions (or flows) for the other components, simply enter the fractions (or the actual flows) for the non-zero components, leaving the others <empty>. Then press the Normalize button, and HYSYS will force the other component fractions to zero.

Calculation status/colour

As you input the composition, the component fractions (or flows) initially appear in red, indicating the final composition is unknown. These values will become blue when the composition has been calculated. Three scenarios will result in the stream composition being calculated:

• Input the fractions of all components, including any zero components, such that their total is exactly 1.0000. Then press the OK button.

• Input the fractions (totalling 1.000), flows or relative number of parts of all non-zero components. Then press the Normalize button then the OK button.

• Input the flows or relative number of parts of all components, including any zero components, then press the OK button.

Note that these are the default colours; yours may appear differently depending on your settings on the Colours page of the Session Preferences view.

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2. Continue entering the fractions as shown in Figure 3.22. When you have entered the fraction of each component, the total at the bottom of the view will equal 1.00000.

3. Press the OK button, and HYSYS accepts the composition. The stream is now completely defined, so HYSYS flashes it at the conditions given to determine its remaining properties.

Close this view and return to the Workbook by clicking on the Workbook button. Ensure that the Streams tab is active by clicking on it. The properties of Feed 1 are shown below. Notice that the values you specified are a different colour (blue) than the calculated values (black).

Figure 3.22

Figure 3.23

If you wish to delete a stream, double-click on it from the PFD, click the Name cell for the stream, and click the Delete button. HYSYS will ask for confirmation of your action before deleting.


Alternatively to installing streams via the Workbook, there are a number of ways to create a new stream with a default name. The Object Palette should be visible; if not, press F4.

To add the other feed stream, do any one of the following:

• Press F11.• From the Flowsheet menu, select Add Stream.• Double-click the Material Stream button on the Object Palette.• Press the Material Stream button on the Object Palette, then

click on the Palette's Add Object button.

Each of these four methods displays the property view for the new stream, which will be named according to the Automatic Naming of Flowsheet Objects setting on the Naming page on the Simulation tab, (which is accessed through Preferences). The default setting will name new material streams with numbers, starting at 1 (and energy streams starting at Q-100).

The Conditions page on the Worksheet tab is the active page when the view is initially accessed. The Stream Name cell is active, as indicated by the thick border around this cell, as well as the appearance of the name 1 in the Edit Bar. To define this second feed stream:

1. Replace the name by typing Feed 2, which will immediately appear in the Edit Bar, and press ENTER.

Add Object Button

Material Stream Button

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2. Enter 60, 600 and 4 in the Temperature, Pressure, and Molar Flow cells, respectively. Note that all these variables are in the default units.

3. Move to the Composition page to begin the compositional input for the new feed stream.

Figure 3.24

Figure 3.25


4. Press the Edit button near the bottom of the Composition page, and the Input Composition for Stream view appears. Note that the current Composition Basis setting is Preferences’ Default. It is required to enter the stream composition on a mass basis.

5. Change the Composition Basis to Mass Fractions by picking the appropriate radio button, or by pressing ALT N.

6. Click on the compositional cell for Nitrogen, type 6 for the number of parts of this component, then press ENTER.

7. Press the i key to move to the input cell for Methane, as this stream has no CO2.

8. Input the number of mass parts for the remaining components as shown above, pressing ENTER after typing each one.

Figure 3.26

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9. Press the Normalize button once you have entered the parts, and HYSYS will convert your input to component mass fractions.

10. Press the OK button to close the view and return to the stream property view.

HYSYS has performed a flash calculation to determine the unknown properties of Feed 2, as shown by the status indicator displaying OK. You can view the properties of each phase using the horizontal scroll bar in the matrix on the property view. For example, to view the vapour and liquid compositions for Feed 2, scroll to the right by clicking the right scroll arrow, or by clicking and dragging the scroll button.

Figure 3.27

Notice for CO2 (the component you left <empty>), the Mass Fraction was automatically forced to zero.


Note that the compositions are currently displayed by Mass Fraction. You can change this by pressing the Basis button and choosing another Composition Basis radio button.

1. To view the calculated stream properties, return to the Conditions page by clicking on it. Instead of scrolling inside the matrix, you can display the properties of all phases by re-sizing the property view.

2. Place the cursor over the right border of the view. The cursor changes to a double-ended sizing arrow.

3. With the sizing arrow visible, click and drag to the right until the horizontal scroll bar disappears, leaving the entire matrix visible.

New or updated information is automatically and instantly transferred among all locations in HYSYS.

Figure 3.28

Scroll bar

Sizing Arrow Cursor

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Viewing a Phase Diagram

You can view a phase diagram for any material stream using the HYSYS Envelope Utility:

1. Move to the Utilities page of the property view for stream Feed 2 by clicking on the Attachments tab and selecting the Utilities page from the index.

2. To create a phase envelope for the stream, press the Create button. The Available Utilities view appears, presenting you with a list of HYSYS utilities.


• Select Envelope, and press the Add Utility button.• Double-click on Envelope.

Figure 3.29


HYSYS creates and displays a phase envelope for the stream. Just as with a Stream, a Utility has its own property view containing all the information needed to define the utility. Initially, the Plots tab of the envelope is displayed. To make the envelope more readable, maximize or re-size the view.

The default Envelope Type is PT. To view another type, simply pick the appropriate radio button. Depending on the type of envelope, you can specify and display Quality curves, Hydrate curves, Isotherms, and Isobars. You can also view data in tabular format by pressing the Table button.

Figure 3.30

Figure 3.31

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The Connections tab allows you to change the name of the Utility and the stream that it is attached to, and view Critical Values and Maxima. Note that a Utility is a separate entity from the stream to which it is attached; if you Delete it, the stream will not be affected. Likewise, if you delete the stream, the Utility will remain but will not display any information until you attach another stream using the Select Stream button.

Close this Utility view since it is no longer required. See Chapter 8 - Utilities in the User’s Guide for more information.

Installing Unit Operations

Now that the feed streams are known, the next step is to install the necessary unit operations for processing the gas.

Installing the Mixer

The first operation that will be installed is a MIXER, used to combine the two feed streams. As with most commands in HYSYS, installing an operation can be accomplished in a number of ways. One method is through the Unit Ops tab of the Workbook. To install the MIXER:

1. Click the Workbook button to ensure the Workbook window is active.

2. Move to the Unit Ops tab of the Workbook.

Figure 3.32

Workbook Button


3. Press the Add UnitOp button. The UnitOps view appears, listing all available unit operations. When you press the Add button or the ENTER key inside this view, HYSYS adds the operation that is currently highlighted.

4. Highlight MIXER by doing one of the following:

• Start typing mixer• Press the i key to scroll down the list of available operations to

Mixer• Scroll down the list using the vertical scroll bar, and click on

Mixer5. With MIXER highlighted, click the Add button, or the ENTER key.

Alternatively, you could have produced a filtered list by picking the Piping Equipment radio button under Categories, then using one of the above methods to install the operation. Double-clicking on a listed operation can also be used instead of the Add button or the ENTER key.

Figure 3.33

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The property view for the MIXER is shown in Figure 3.34. As with a stream, a unit operation property view contains all the information defining the operation, organized into different views which are available on different pages sorted in tabs. The four tabs shown for the MIXER, namely Design, Rating, Worksheet and Dynamics, appear in the property view for most operations. Property views for more complex operations contain more tabs. Notice that HYSYS has provided the default name MIX-100 for the MIXER. As with streams, the default naming scheme for unit operations can be changed on the Session Preferences tab.

Many operations, like the MIXER, accept multiple feed streams. Whenever you see a matrix like the one for Inlets, the operation will accept multiple stream connections at that location. When the Inlets matrix has focus, you can access a drop-down list of available streams in the Edit Bar.

To complete the Connections page:

1. Click on the **Stream** cell to ensure the Inlets matrix is active.

The status indicator at the bottom of the view shows that the operation needs a feed stream.

Figure 3.34

See Chapter 7 - Menu Bar Options in the User’s Guide for detailed information on setting your Session Preferences.


2. Open the Edit Bar drop-down list of feeds by clicking on or by pressing the F2 key and then the i key.

3. Select Feed 1 from the list. The stream is transferred to the list of Inlets, and **Add Stream** is automatically moved down to a new empty cell.

4. Repeat steps 1 and 2 to connect the other stream, Feed 2.

The status indicator now displays Requires a product stream. To assign a product stream:

1. Move to the Outlet cell by clicking on it, or by pressing TAB.

2. Type MixerOut in the cell, and press ENTER. Since no outlet streams have been created to attach, HYSYS recognizes that there is no existing stream with this name, so it will create the new stream with the name you have supplied.

Figure 3.35

Figure 3.36

Alternatively, you could have made the connections by typing the exact stream name in the cell, followed by ENTER.

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The status indicator has now changed to a green OK, showing that the operation and attached streams are completely calculated.

1. With the Connections page complete, move to the Parameters page by clicking on it.

2. Leave the Automatic Pressure Assignment at its default setting of Set Outlet to Lowest Inlet. HYSYS has calculated the outlet stream by combining the two inlets and flashing the mixture at the lowest pressure of the inlet streams. In this case, both inlets have the same pressure (600 psia), so the outlet stream is set to 600 psia.

3. To view the calculated outlet stream, go to the Worksheet tab and click on the Conditions page.

Figure 3.37

Figure 3.38

The Conditions page is a condensed Workbook page, displaying only those streams attached to the operation.


4. Now that the MIXER is completely known, close the view to return to the Workbook. The new operation is displayed in the matrix on the Unit Ops tab of the Workbook.

The matrix shows the operation Name, its Object Type, the attached streams (Feeds and Products), whether it is Ignored, and its Calculation Level. When you click the View UnitOps button, the property view for the operation occupying the current row in the matrix is opened. Alternatively, double-clicking on any cell (except Feeds and Products) associated with the operation also opens its property view.

You can also open the property view for a stream directly from the Unit Ops tab of the Workbook. When any of the Name, Object Type, Ignored or Calc. Level cells are active, the box at the bottom of the Workbook displays all streams attached to the current operation. Currently, the Name cell for MIX-100 has focus, and the box displays the three streams attached to this operation. To open the property view for one of the streams attached to the MIXER, for example Feed 1, do one of the following:

• Double-click on Feed 1 in the box at the bottom of the Workbook.

• Double-click on the Feeds cell for MIX-100. The property view for the first listed feed stream, in this case Feed 1, is opened.

Figure 3.39

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Installing the Inlet Separator

The inlet separator splits the two-phase MixerOut stream into its vapour and liquid phases. In the Workbook, the Unit Ops tab should again be active. To install and define the SEPARATOR:

1. Click the Add UnitOps button, and the UnitOps view appears. (The Unit Ops view can also be accessed by pressing F12 from the Workbook.)

2. Select the Vessels radio button in the Categories group.

3. In the list of Available Unit Operations, choose Separator.

4. Click the Add button. The SEPARATOR property view appears, and the Connections page on the Design tab is active.

5. Change the name from its default (V-100) by typing InletSep in the Name cell, then press ENTER.

6. Move to the Inlets list by clicking on the << Stream>> cell, or by pressing ALT L.

7. Open the drop-down list of available feed streams in the Edit Bar.

8. Select the stream MixerOut by doing one of the following:

• Click on the stream name in the drop-down list• Press i key to highlight the stream name, then press ENTER

9. Move to the Vapour Outlet cell by doing one of the following:

• Click on the cell.• Press ALT V.

Figure 3.40


10. Create the vapour outlet stream by typing SepVap. Press ENTER.

11. Select the Liquid Outlet cell and type the name SepLiq. The completed Connections page is shown in Figure 3.40.

Note that an Energy stream could be attached to heat or cool the vessel contents. However, for the purposes of this example, the energy stream is not required.

1. Advance to the Parameters page by clicking on it. The default Delta P (pressure drop) of zero is acceptable for this example. The Volume, Liquid Volume and Liquid Level (which in general applies only to vessels operating in dynamic mode or with reactions attached), are also acceptable at their default value.

2. To view the calculated outlet stream data, move to the Conditions page of the Worksheet tab. The matrix appearing on this page is shown below. When finished, click the Close button to close the view.

Figure 3.41

Figure 3.42

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3-36

Installing the Heat Exchanger

The next operation to install is the gas/gas exchanger. The Object Palette should be visible; if not, press F4. To install and define a new HEAT EXCHANGER:

1. On the Object Palette, double-click on the Heat Exchanger button. The HEAT EXCHANGER property view appears, and the Connections page is active.

2. Change the operation Name from its default E-100 to Gas/Gas.

3. Attach the inlet and outlet streams as shown below, using the methods discussed previously. Note that you will have to create all streams except SepVap, which is an existing stream that can be selected from the Tube Side Inlet drop-down list. Create the new streams by moving to the appropriate input cell, typing in the name, and pressing ENTER.

On the Parameters page:

1. The Exchanger Design (End Point) is the acceptable default setting for the Heat Exchanger Model for this tutorial.

Heat Exchanger Button

Figure 3.43


2. Enter a pressure drop of 10 psi for both the Tube Side Delta P and Shell Side Delta P. Note that the default units (shown in the Edit Bar) are psi, so simply type 10 in each cell, and press ENTER.

3. Change the value of Tube Passes per Shell, found on the Sizing page of the Rating tab, to 1 to model Counter Current Flow.

Figure 3.44

Figure 3.45

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4. Close the HEAT EXCHANGER property view to return to the Workbook.

5. Move to the Streams tab of the Workbook, shown in Figure 3.46.

Stream CoolGas has not yet been flashed, as its temperature is unknown. CoolGas is flashed when a temperature approach is specified for the Gas/Gas heat exchanger, later

Workbook Features

Before installing the remaining operations, a number of features of the Workbook will be illustrated which allow you to access information quickly and change how information is displayed.

Accessing Unit Operations from the Workbook

There are a number of ways to open the property view for an operation directly from the Workbook. In addition to using the Unit Ops tab, you can use the following method:

• When your current location is a Workbook streams tab, such as any one of the Material Streams, Compositions and Energy Streams tabs, the box at the bottom of the Workbook view displays the operations to which the current stream is attached. For example, click on any cell associated with the stream

Figure 3.46

Notice how partial information is passed (for stream CoolGas) throughout the flowsheet. HYSYS always calculates as many properties as possible for the streams based on the available information.

Any utilities attached to the stream with the Workbook active will also be displayed in (and are accessible through) this box.


SepVap. The box displays the names of the two operations, InletSep and Gas/Gas, to which this stream is attached. To access the property view for either of these operations, double-click on the corresponding operation name.

Adding a Tab to the Workbook

Notice that when the Workbook has focus, the Workbook item appears in the HYSYS menu. This item allows you to customize the Workbook according to the information you would like to be displayed.

Suppose you wish to create a new Workbook tab that displays only stream pressure, temperature, and flow. To add a new tab:


• From the Workbook menu item, select Setup.• Object inspect (right-click) the Material Streams tab in the

Workbook, then select Setup from the menu that appears.

Figure 3.47

Stream SepVap is the current Workbook location

The operation to which SepVap is attached are displayed in this box. You can access the property by double-clicking on the corresponding operation name.

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The Workbook Setup view appears.

Notice that the four existing tabs are listed in the Workbook Pages group. When you add a new tab, it will be inserted before the highlighted tab (currently Material Streams). Add the new tab before the Compositions tab.

1. Click on the Compositions tab in the list of Workbook tabs.

2. Click the Add button. The New Object Type view appears.

Figure 3.48

Figure 3.49

Currently, all variables are displayed with four significant figures. You can change the display format or precision of any Workbook variables by pressing the Format button.


3. Click on Stream to expand it into Material Stream and Energy Streams. Select the Material Stream and click the OK button, or double-click on Material Stream. You will return to the Setup view, and the new tab is added after the existing Material Streams tab.

4. Click on the Name cell in the Object group, and change the name for the new tab from the default Material Streams 2 to P,T,Flow in order to better describe the tab contents.

The next step is to customize the tab by removing the variables that are irrelevant.

1. Click on the first variable, Vapour Fraction.


3. Click on the other variables, Mass Flow, Heat Flow and Molar Enthalpy. These four variables are now highlighted.


5. Click the Delete button to remove them from this Workbook tab only. If you wish to remove variables from another tab, you must edit each tab individually. The finished Setup is shown in Figure 3.51.

Figure 3.50

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Close the view to return to the Workbook and view the new tab.

Figure 3.51

Figure 3.52

The new tab displays only these four Variables.

The new tab now appears in the list of Workbook Pages, in the same order as it will appear in the Workbook.


At this point, it is probably a good idea to save your case by doing one of the following:

• Press the Save button on the button bar.• Select Save from the File menu.• Press CTRL S.

Using the PFD

Besides the Workbook, the PFD is the other home view in the Simulation Environment. To open the PFD, press the PFD button on the button bar. The PFD item appears in the HYSYS menu whenever the PFD is active. Your PFD view should appear as below, with all streams and unit operations visible. If not, choose Auto Position All from the PFD menu item. HYSYS now displays all streams and operations, arranging them in a logical manner according to the setup of your flowsheet.

As a graphical representation of your flowsheet, the PFD shows the connections among all streams and operations, also known as "objects". Each object is represented by a symbol or "icon". A stream icon is an arrow pointing in the direction of flow, while an operation icon is a graphic representing the actual physical operation. The object name or "label", appears near each icon.

Figure 3.53

PFD Button

PFD Button Bar Material Stream arrow

Stream/Operation labels

Unit Operation icon for a SEPARATOR

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Like any other non-modal view, the PFD view can be re-sized by clicking and dragging anywhere on the outside border. Among other functions that can be performed while the PFD is active, you can:

• Access commands and features through the PFD Button Bar.• Open the property view for an object by double-clicking on its

icon.• Move an object by clicking and dragging it to the new location.• Access fly-by summary information for an object simply by

placing the cursor over it.• Change an icon's size by pressing the Size button, clicking on

the icon, then clicking and dragging the sizing "handles".• Display the Object Inspection menu for an object by placing the

cursor over it and right-clicking. This menu provides access to a number of commands associated with the particular object.

• Zoom in and out, or display the entire flowsheet in the PFD window by pressing the zoom buttons at the bottom left of the PFD view.

Some of these functions will be illustrated here; for further information, see Chapter 3 - PFD in the User’s Guide.

Calculation Status

Before proceeding, a feature of the PFD will be described which allows you to trace the calculation status of the objects in your flowsheet. Recall the status indicator at the bottom of the property view for a stream or operation. This indicator displays three different states for the object:

Indicator Status Description

Red Status

A major piece of defining information is missing from the object. For example, a feed or product stream is not attached to a SEPARATOR. The status indicator is red, and an appropriate warning message is displayed.

Yellow Status

All major defining information is present, but the stream or operation has not been solved because one or more degrees of freedom is present. For example, a COOLER whose outlet stream temperature is unknown. The status indicator is yellow, and an appropriate warning message is displayed.

Green StatusThe stream or operation is completely defined and solved. The status indicator is green, and an OK message is displayed.

Fly-By Information

Size Button

Zoom Out 25%

Display Entire PFD

Zoom In 25%

Keep in mind that these are the HYSYS default colours; you may change the colours in the Session Preferences.


When you are in the PFD, the streams and operations are "colour-coded" to indicate their calculation status. The mixer and inlet separator are completely calculated, so their normal colours are displayed. For heat exchanger Gas/Gas, however, the conditions of the tube-side outlet and both shell-side streams are unknown. Therefore, the exchanger has a yellow outline indicating its current status.

A similar colour scheme is used to indicate the status of streams. For material streams, a dark blue icon indicates the stream has been flashed and is entirely known. A light blue icon indicates the stream cannot be flashed until some additional information is supplied. Similarly, a dark red icon is for an energy stream with a known duty, while a light red icon indicates an unknown duty.

Installing the Chiller

The Chiller will be modelled as a COOLER. You can install streams or operations by dropping them from the Object Palette onto the PFD. Make sure the Object Palette is displayed; if it is not, press F4. The Chiller will be added to the right of the LTS, so make some empty space available by scrolling to the right using the horizontal scroll bar. To install and connect the Chiller:

1. Click the Cooler button on the Object Palette. If you press the wrong button, click the Cancel button.

2. Position the cursor over the PFD. The cursor changes to a special cursor with a plus (+) symbol attached to it. The symbol indicates the location of the operation icon.

Figure 3.54

Notice that the icons for all streams installed to this point are dark blue, except for the HEAT EXCHANGER shell-side streams LTSVap and SalesGas, and tube-side outlet CoolGas.

Cooler Button

Cancel Button

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3. Click to "drop" the COOLER onto the PFD. HYSYS creates a new COOLER with a default name, E-100. Notice that the COOLER has red status (colour), indicating that it requires feed and product streams.

4. Press the Attach Mode button on the PFD toolbar to enter Attach mode. The Attach Mode button has a different shading to show that it is "pressed".

5. Position the cursor over the right end of the CoolGas stream icon. A small transparent box appears at the cursor tip. Through the transparent box, you can see a square connection point, and a pop-up description attached to the cursor tail. The pop-up "Out" indicates which part of the stream is available for connection, in this case the stream outlet.

6. With the pop-up "Out" visible, left-click and hold. The transparent box becomes solid black, indicating that you are beginning a connection.

7. Move the cursor toward the left (inlet) side of the COOLER. A trailing line appears between the CoolGas stream icon and the cursor, and a connection point appears at the COOLER inlet.

8. Place the cursor near the connection point, and the trailing line snaps to that point. As well, a solid white box appears at the cursor tip, indicating an acceptable end point for the connection.

9. Release the left mouse button, and the connection is made to the connection point at the COOLER inlet.

Figure 3.55

Figure 3.56

When you are in Attach mode, you will not be able to move objects in the PFD. To return to Move mode, click the Attach button again. You can temporarily toggle between Attach and Move mode by holding down the CTRL key.

.

Attach Mode Button


To connect the COOLER:

1. Position the cursor over the right end of the COOLER icon. The connection point and pop-up "Product" appears.

2. With the pop-up visible, left-click and hold. The transparent box again becomes solid black.

3. Move the cursor to the right of the COOLER. A large stream icon appears, with a trailing line attached to the COOLER outlet. The stream icon indicates that a new stream will be created after step 4 is completed.

4. With the large stream icon visible, release the left mouse button. HYSYS creates a new stream with the default name 1.

5. Repeat steps 1-4 to create the COOLER energy stream, originating the connection from the arrowhead on the COOLER icon. The new stream is automatically named Q-100, and the COOLER has yellow (warning) status. This status indicates that all necessary connections have been made, but the attached streams are not entirely known.

6. Press the Attach Mode button again to return to Move mode. The Attach Mode button returns to its normal appearance.

The COOLER material streams, as well as the energy stream, are unknown at this point, so they are light blue and light red, respectively. Double-click on the COOLER icon to open its property view. On the Connections page, notice that the names of the Inlet, Outlet and Energy streams that were attached previously appear in the appropriate cells.

Figure 3.57

Figure 3.58

Break Connection Button

If you make an incorrect connection:

1. Press the Break Connection button on the PFD button bar.

2. Move the cursor over the stream line connecting the two icons. A check mark attached to the cursor appears, indicating an available connection to break.

3. Click once to break the connection.

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1. Change the operation Name from the default to Chiller.

2. Click on the Parameters page, and specify a Pressure Drop of 10 psi.

3. When you are finished, close this view.

At this point, the Chiller has two degrees of freedom; one of these will be exhausted when HYSYS flashes the CoolGas stream after the exchanger temperature approach will be specified. To use the remaining degree of freedom, either the Chiller outlet temperature, or the amount of duty in the Chiller energy stream can be specified. The

Figure 3.59

Figure 3.60


3-49

amount of chilling duty which is available is unknown, so an initial "guess" of 0oF for the Chiller outlet temperature will be provided. Later, this temperature can be adjusted to provide the desired sales gas dew point temperature.

4. Double-click on the outlet stream icon (1) to open its property view. Change the Name from the default to ColdGas, then specify a temperature of 0oF.

The remaining degree of freedom for this stream has now been used, so HYSYS flashes ColdGas to determine its remaining properties. Press the Close button to return to the PFD. The Chiller still has yellow status, because the temperature of CoolGas is unknown.

5. Double-click on the energy stream icon (Q-100) to open its property view.

The required chilling duty (in the Heat Flow cell) is calculated by HYSYS when the HEAT EXCHANGER temperature approach is specified.

Figure 3.61


3-50

6. Rename this stream C3Duty, then close the view.

Installing the LTS

Now that the chiller has been installed, the next step is to install the low-temperature separator (LTS) to separate the gas and condensed liquids in stream ColdGas. To install and connect the SEPARATOR:

1. Make some empty space available to the right of the Chiller using the horizontal scroll bar.

2. Position the cursor over the Separator button on the Object Palette.

3. Right-click and hold. Position the cursor over the PFD, to the right of the Chiller. The cursor changes to a special "bulls-eye" cursor. The bulls-eye indicates the location of the operation icon.

4. Release the secondary mouse button to "drop" the SEPARATOR onto the PFD. HYSYS will create a new SEPARATOR with a default name V-100.

5. Click the Attach button on the PFD toolbar to enter Attach mode.

6. Position the cursor over the right end of the ColdGas stream icon. The connection point and pop-up "Out" appears.

7. With the pop-up visible, left-click and hold.

8. Move the cursor toward the left (inlet) side of the SEPARATOR, and multiple connection points will appear at the SEPARATOR inlet.

Figure 3.62

Separator Button

Multiple connection points appear because the SEPARATOR accepts multiple feed streams.


9. Place the cursor near the inlet area of the SEPARATOR, and a solid white box appears at the cursor tip.

10. Release the mouse button, and the connection is made.

The SEPARATOR has two outlet streams, liquid and vapour. The vapour outlet stream LTSVap have already been created, which is the shell side inlet stream for Gas/Gas. The liquid outlet will be a new stream. To complete the attachments for the SEPARATOR:

1. Position the cursor over the top of the SEPARATOR icon. The connection point and pop-up "Vapour Product" appears.


3. Move the cursor toward the LTSVap stream icon, and a connection point appears at the stream inlet.

4. Place the cursor over the LTSVap stream icon, and a solid white box appears at the cursor tip.

5. Release the mouse button, and the connection is made.

6. Position the cursor over the bottom of the SEPARATOR icon. The connection point and pop-up "Liquid Product" appears.


8. Move the cursor to the right of the SEPARATOR. A large stream icon appears with a trailing line attached to the SEPARATOR liquid outlet.

9. With the large stream icon visible, release the mouse button. HYSYS creates a new stream with the default name 1.

10. Press the Attach button to leave Attach mode.

Figure 3.63

Figure 3.64

Attach Mode Button

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11. Double-click on the stream icon 1 to open its property view.

12. Enter the new name LTSLiq in the Name cell, then press the Close button.

Now that the LTS connections are complete, select Auto Position All from the PFD menu item. Your PFD appears similar to the one shown in Figure 3.65.

1. Double-click on the icon for the new SEPARATOR (V-100) to open its property view. Change its name from the default to LTS, then click the Close button.

At this point, the outlet streams from heat exchanger Gas/Gas are still unknown.

Figure 3.65

Streams LTSVap and LTSLiq are now known, as shown by the change in their PFD colour from light blue to dark blue.


2. Double-click on the Gas/Gas icon to open the exchanger property view, then move to the Specs page on the Design tab.

This page allows you to input specifications for the HEAT EXCHANGER and view its calculation status. The Solver group on this page shows that there are two (2) Unknown Variables and the Number of Constraints is one (1), so the remaining Degrees of Freedom is one (1). HYSYS provides two default constraints in the Specifications group, although only one has a value:

Adding a Heat Exchanger Specification

To exhaust the remaining degree of freedom, a 10oF minimum temperature approach to the hot side inlet of the exchanger will be specified. To create the specification:

Figure 3.66

Specifications Description

Heat Balance The tube side and shell side duties must be equal, so the heat balance must be zero (0).

UA

This is the product of the overall heat transfer coefficient (U) and the area available for heat exchange (A). HYSYS does not provide a default UA value, so it is unknown at this point. It will be calculated by HYSYS when another constraint is provided.

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1. Click the Add button, and the ExchSpec (Exchanger Specification) view appears.

2. Change the Name from the default to Hot Side Approach. The default specification Type is Delta Temp, which allows you to explicitly specify a temperature difference between two streams. The Stream (+) and Stream (-) cells correspond to the warmer and cooler streams, respectively.

3. In the Stream (+) cell, select SepVap from the drop-down list in the Edit Bar.

4. In the Stream (-) cell, select SalesGas from the drop-down list in the Edit Bar.

5. Enter 10 (oF) in the Spec Value cell. HYSYS will converge on both specifications and the unknown streams will be flashed.

6. Click the Close button to return to the Gas/Gas property view. The new specification will appear in the Specifications group on the Specs page.

Figure 3.67

Figure 3.68


7. Move to the Conditions page on Work Sheet tab to view the calculated stream properties.

Using the 10oF approach, HYSYS has calculated the temperature of CoolGas as 42.94oF. All streams in the flowsheet are now completely known. Next, move to the Details page on the Performance page, where HYSYS displays the Overall Performance and Detailed Performance.

Figure 3.69

Figure 3.70

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3-56

Two parameters of interest are the UA and Lmtd (logarithmic mean temperature difference), which HYSYS has calculated as 2.08e4 Btu/×F-hr and 22.6oF, respectively.

1. When you are finished viewing the results, click the Close button to leave the Gas/Gas property view.

Checking the Sales Gas Dew Point

Now that the gas stream has been processed, the SalesGas must be checked in order to meet a dew point temperature specification at the pipeline flowing pressure to ensure no liquids form in the transmission line. A typical pipeline dew point specification is 15 oF at 800 psia, which will be used for this example.

The current dew point can be checked by creating a stream whose composition is identical to SalesGas, specifying the dew point pressure, and having HYSYS flash the new stream to calculate its dew point temperature. This can be accomplished by installing a BALANCE operation as follows:

1. Double-click on the Balance button on the Object Palette. The property view for the new operation appears.

2. Type in the new name DewPoint, then press ENTER.

3. Move to the **Stream** cell under Inlet Streams.

4. Open the drop-down list of available streams in the Edit Bar, and select SalesGas.

Figure 3.71

Balance Button


5. Move to the **Stream** cell under Outlet Streams.

6. Create the outlet stream by typing SalesDP, then press ENTER.

7. Move to the Parameters tab and click on Mole radio button in the BALANCE types field.

8. Click on the Auto Calculation check box. HYSYS performs a mole balance between the two streams, duplicating the composition of SalesGas into SalesDP.

Next, move to the Worksheet tab of the BALANCE property view. The vapour fraction and pressure of SalesDP can now be specified, and HYSYS will perform a flash calculation to determine the unknown temperature.

To specify a dew point calculation at 800 psia for SalesDP, enter a Vapour fraction of 1.0 and a Pressure of 800 psia in the appropriate cells. HYSYS flashes the stream at these conditions, returning a dew point Temperature of 9.99oF, which is well within the pipeline specification of 15oF. Close the view to return to the PFD.

Figure 3.72

Note that changes made to the vapour fraction, temperature or pressure of stream SalesDP will not affect the rest of the flowsheet. However, changes which affect SalesGas will cause SalesDP to be re-calculated because of the molar balance between these two streams.

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When HYSYS created the BALANCE and new stream, their icons were likely placed in the far right of the PFD. If desired, you can click and drag the BALANCE and SalesDP icons to a more appropriate location, such as immediately to the right of stream SalesGas.

Installing the Second Mixer

The second MIXER is used to combine the two liquid streams, SepLiq and LTSLiq, into a single feed for the DISTILLATION COLUMN. To install and connect the MIXER:

1. Make some empty space available to the right of the LTS using the horizontal scroll bar.

2. Click the Mixer button on the Object Palette.

3. Position the cursor over the PFD, to the bottom right of the LTSLiq stream icon.

4. Click to "drop" the MIXER onto the PFD. HYSYS creates a new MIXER with the default name MIX-101.

5. Press and hold the CTRL key to temporarily enable Attach mode while you make the MIXER connections.

6. Position the cursor over the right end of the LTSLiq stream icon. The connection point and pop-up "Out" appears.

7. With the pop-up visible, click and drag the cursor toward the left (inlet) side of the MIXER, and multiple connection points appear at the MIXER inlet.

Figure 3.73

Mixer Button

Again, multiple connection points appear because the MIXER accepts multiple feed streams.


8. Place the cursor near the inlet area of the MIXER, and when the solid white box appears at the cursor tip, release the left mouse button to make the connection.

9. Repeat steps 14-16 to connect SepLiq to the MIXER.

10. Position the cursor over the right end of the MIXER icon. The connection point and pop-up "Product" will appear.

11. With the pop-up visible, click and drag to the right of the MIXER. A large stream icon will appear, with a trailing line attached to the MIXER outlet.

12. With the large stream icon visible, release the primary mouse button. HYSYS will create a new stream with the default name 1.

13. Release the CTRL key to leave Attach mode.

14. Double-click on the outlet stream icon 1 to access its property view. When you created the MIXER outlet stream, HYSYS automatically combined the two inlet streams and flashed the mixture to determine the outlet conditions, shown here.

15. Rename the stream to TowerFeed, then press the Close button.

Installing the Column

HYSYS has a number of pre-built column templates that you can install and customize by changing attached stream names, number of stages and default specifications. For this example, a DISTILLATION COLUMN will be installed. Before installing the column, select Preferences from the HYSYS Tools menu. On the Simulation tab, ensure that the Use Input Experts check box is selected (checked), then Close the view.

To install the column:

1. Double-click on the Distillation Column button on the Object Palette, and the first page of the Input Expert appears.

Figure 3.74

Distillation Column Button

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When you install a column using a pre-built template, HYSYS supplies certain default information, such as the number of stages. The current active cell is Numb of Stages (Number of Stages), indicated by the thick border around this cell, and the presence of 10 (default number of stages) in the Edit Bar at the top of the view. Some points worth noting are:

• These are theoretical stages, as the HYSYS default stage efficiency is one. If you wish to specify real stages, you can change the efficiency of any or all stages later.

• The Condenser and Reboiler are considered separate from the other stages, and are not included in the Numb Stages field.

For this example, 10 theoretical stages will be used, so leave the Number of Stages at its default value.

2. Advance to the Inlet Streams list by clicking on the <Stream> cell, or by pressing TAB.

3. Open the drop-down list of available feeds in the Edit Bar by clicking it, or by pressing F2 then i.

4. Select TowerFeed as the feed stream to the column. HYSYS will supply a default feed location in the middle of the Tray Section (TS), in this case stage 5 (indicated by 5_Main TS). This default location is used, so there is no need to change the Feed Stage.

This column has Overhead Vapour and Bottoms Liquid products, but no Overhead Liquid (distillate) product.

Figure 3.75

The Input Expert is a logical sequence of input views which guide you through the initial installation of a Column. Completion of the steps will ensure that you have provided the minimum amount of information required to define the column.


1. In the Condenser group, pick the Full Rflx radio button, and the distillate stream disappears. In effect, this is the same as leaving the Condenser as Partial and later specifying a zero distillate rate.

2. Enter the stream and Column names as shown below. When you are finished, the Next button becomes active, indicating sufficient information has been supplied to advance to the next page of the Input Expert.

3. Click the Next button to advance to the Pressure Profile page.

Figure 3.76

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3-62

4. Enter 200 psia and 205 psia as the Condenser Pressure and Reboiler Pressure, respectively. The Condenser Pressure Drop can be left at its default value of zero.

5. Press the Next button to advance to the Optional Estimates page.

Figure 3.77

Although HYSYS does not require estimates to produce a converged column, good estimates will usually result in a faster solution.


6. Provide Condenser and Reboiler Temperature Estimates of 40 °F and 200 °F, respectively.

7. Press the Next button to advance to the fourth and final page of the Input Expert. This page allows you to supply values for the default column specifications that HYSYS has created.

In general, a DISTILLATION COLUMN has three default specifications. However, by specifying zero overhead liquid flow (Full Reflux Condenser) one degree of freedom was eliminated. For the two remaining default specifications, overhead Vapour Rate is an estimate only, and Reflux Ratio is an active specification.

1. Enter a Vapour Rate of 2.0 MMSCFD and a Reflux Ratio of 1.0. Note that the Flow Basis applies to the Vapour Rate, so leave it at the default of Molar.

Figure 3.78

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2. Click the Done button, and the DISTILLATION COLUMN property view appears.

Figure 3.79

Figure 3.80


You are automatically placed on the Connections page on the Design tab of the Column view.

1. Move to the Monitor page on the Design tab by clicking on it.

The main feature of this page is that it displays the status of your column as it is being calculated, updating information with each iteration. You can also change specification values, and activate or de-activate specifications used by the Column solver, directly from this page.

Adding a Column Specification

Notice that the current Degrees of Freedom is zero, indicating the column is ready to be Run. However, the Vapour Rate that was specified in the Input Expert is currently an Active specification, and it is desired to use this only as an initial estimate for the solver. Click the Active check box for the Ovhd Vap Rate to clear it, leaving it as an Estimate only. The Degrees of Freedom will increase to 1, indicating that another active specification is required. For this example, a 2% propane mole fraction in the bottoms liquid will be specified.

To add the new specification:

2. Move to the Specs page by clicking on it. The Specs, (or specification), page lists all the Active and non-Active specifications which are required to solve the column.

3. Click the Add button in the Column Specifications group box. The Add Specs view appears.

Figure 3.81

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4. Select Component Fractions as the Column Specification Type.

5. Click the Add Spec(s) button, and the Comp Frac Spec view appears.

6. Change the specification Name to Propane Fraction by editing the default name.

7. Move to the Stage cell, and choose Reboiler from the list of available stages displayed in the Edit Bar.

8. Move to the Spec Value cell, and enter .02 as the liquid mole fraction specification value.

Figure 3.82

Figure 3.83


9. Move to the first cell in the Components list, indicated by <<Component>>, and select Propane from the drop-down list of available components in the Edit Bar.

10. Close the view to return to the Column property view.

The new specification appears in the list of Column Specifications on the Specs page. Return to the Monitor page, where the new specification may not be visible (unless you scroll down the matrix) because it has been placed at the bottom of the Specifications list. For convenience, click the Group Active button to bring the new specification to the top of the list, directly under the other Active specification. Note that HYSYS automatically made the new specification active when you created it.

Figure 3.84

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3-68

The Degrees of Freedom has returned to zero, so the column is ready to be calculated.

Running the Column

1. Click the Run button to begin calculations, and the information displayed on the page is updated with each iteration. The column converges quickly, in three iterations.

Figure 3.85


The converged temperature profile is currently displayed in the upper right corner of the view. To view the pressure or flow profiles, pick the appropriate radio button. You can access a more detailed stage summary by moving to the Summary page on the Performance tab.

Figure 3.86

This matrix displays the Iteration number, Step size, and Equilibrium error and Heat/Spec error.

The column temperature profile is shown here.You can view the pressure or flow profiles by picking the appropriate radio button.

The status indictor has changed from Unconverged to Converged.

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Moving to the Column Subflowsheet

When considering the column, you might wish to focus only on the column subflowsheet. You can do this by entering the column environment. Press the Column Environment button at the bottom of the property view. While inside the column environment, you might want to:

• View the column subflowsheet PFD by pressing the PFD button.

• View a Workbook of the column subflowsheet objects by pressing the Workbook button.

• Access the "inside" column property view by pressing the Column Runner button. This property view is essentially the same as the "outside", or main flowsheet, property view.

The column subflowsheet PFD and Workbook are shown on the next page.

Figure 3.87

PFD Button

Workbook Button

Column Runner Button


Figure 3.88

Figure 3.89

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2. When you are finished in the column environment, return to the main flowsheet by pressing the Parent Simulation Environment button.

Results1. Open the Workbook to access the calculated results for the main

flowsheet. The Material Streams and Compositions tabs of the Workbook are shown below.

Parent Simulation Environment Button

Figure 3.90

Figure 3.91


Using the Object Navigator

Now that results have been obtained, you may wish to view the calculated properties of a particular stream or operation. The Object Navigator allows you to quickly access the property view for any stream or unit operation at any time during the simulation. To open the Navigator, do one of the following:

• Press F3.• From the Flowsheet menu, select Find Object.• Double-click on any blank space on the HYSYS Desktop.• Choose the Navigator button.

The Object Navigator view appears:

The UnitOps radio button in the Filter group is currently picked, so only the Unit Operations appear in the list of objects. To open a property view, select the operation in the list, then click the View button, or double-click on the operation. You can change which objects are displayed by picking a different Filter radio button. For example, to list all streams and unit operations, pick the All button.

You can also search for an object by pressing the Find button. When the Find Object view appears, enter the Object Name, then click the OK button. HYSYS opens the property view for the object whose name you entered.

Using the Databook

The HYSYS Databook provides you with a convenient way to examine your flowsheet in more detail. You can use the Databook to monitor key variables under a variety of process scenarios, and view the results in a tabular or graphical format.

Figure 3.92

Navigator Button

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Before opening the Databook, close the Object Navigator or any property view you might have opened using the Navigator. To open the Databook, do one of the following:

• Press CTRL D.• Open the Tools menu, and Select Databook.

The Databook appears below.

The first step is to add the key variables to the Databook using the Variables tab. The Variable Navigator is used extensively in HYSYS for locating and selecting variables. The Navigator operates in a left-to-right manner-the selected Flowsheet determines the Object list, the chosen Object dictates the Variable list, and the selected Variable determines whether any Variable Specifics are available.

For this example, the effects of LTS temperature on the sales gas dew point and flow rate, and liquid product flow rate will be investigated. To add the variables to the Databook:

1. Click the Insert button, and the Variable Navigator view appears.

2. Pick the UnitOps radio button in the Object Filter group. The Object list will be filtered to show unit operations only.

3. Click on LTS in the Object list, and the Variable list available for the LTS appears to the right of the Object list.

Figure 3.93


4. Select Vessel Temperature in the Variable list. HYSYS displays this variable name in the Variable Description cell.

5. The new variable LTS Temp appears in the Databook.

To add the next variable:

1. Press the Insert button, and the Variable Navigator appears.

2. Pick the Streams radio button in the Object Filter group. The Object list is filtered to show streams only.

3. Click on SalesDP in the Object list, and the Variable list available for material streams appears to the right of the Object list.

4. Select Temperature in the Variable list.

Figure 3.94

Figure 3.95

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5. Change the Variable Description to Dew Point, then click the OK button. The variable now appears in the Databook.

6. Repeat steps 1-5 to add the other variables to the Databook. Add the Molar Flow variable for stream SalesGas and Liquid Volume Flow for stream LiquidProd. Change the Variable Description for these variables to Sales Gas Production and Liquid Production. The completed Variables tab of the Databook appears below.

After the key variables have been added to the Databook, the next step is to create a data table to display those variables:

7. Move to the Process Data Tables tab by clicking on it.

Figure 3.96

Figure 3.97


8. Click the Add button in the Available Process Data Tables group. HYSYS creates a new table with the default name ProcData1.

9. Change the default name from ProcData1 to Key Variables by editing the Process Data Table cell.

Notice that the four variables that were added to the Databook appear in the matrix on this tab.

1. Activate each variable by clicking on the corresponding Show check box.

Figure 3.98

Figure 3.99

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2. Click the View button to view the new data table, which is shown below.

This table will be accessed again later to demonstrate how its results are updated whenever a flowsheet change is made. For now, click the Minimize button in the upper right corner of the Key Variables Data view. HYSYS reduces the view to an icon and places it at the bottom of the Desktop.

Suppose you now want to make changes to the flowsheet, but you would like to record the current values of the key variables before making any changes. Instead of manually recording the variables, you can use the Data Recorder to automatically record them for you. To record the current values:

1. Move to the Data Recorder tab in the Databook by clicking on it. This tab appears below.

Figure 3.100

Figure 3.101


When using the Data Recorder, you first create a Scenario containing one or more of the key variables, then record the variables in their current state.

2. Click the Add button in the Available Scenarios group, and HYSYS creates a new scenario with the default name Scenario 1. It is desired to include all four key variables in this scenario.

3. Activate each variable by clicking on the corresponding Include check box.

4. Click the Record button to record the variables in their current state. The New Solved State view appears, prompting you for the name of the new state.

5. Enter the new name Base Case, then click OK. You return to the Databook.

6. In the Available Display group, pick the Table radio button.

Figure 3.102

Figure 3.103

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7. Press the View button, and the Data Recorder appears, showing the values of the key variables in their current state.

Now you can make the necessary flowsheet changes and these current values remain as a permanent record in the Data Recorder unless you choose to erase them.

1. Click the Minimize button to reduce the Data Recorder to an icon.

2. Double-click on the Key Variables Data icon to restore the view to its full size.

The temperature of stream ColdGas (which determines the LTS temperature) is changed and the changes are viewed in the process data table:

1. Click the Navigator button on the button bar.

2. Pick the Streams radio button in the Filter group.

Figure 3.104

Navigator button


3. Click on ColdGas, then click the View button. The ColdGas property view appears.

4. Ensure that you are on the Conditions page of the property view.

5. Arrange the two views as shown below by clicking and dragging on their title bars. If you need to move the data table, you will first have to click the Pin button on the stream property view.

Currently, the LTS temperature is 0oF. The key variables will be checked at 10oF.

1. Enter 10 in the Temperature cell for ColdGas, and HYSYS automatically recalculates the flowsheet. The new results are shown in Figure 3.107.

Figure 3.105

Figure 3.106

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As a result of the change,

• The sales gas flow rate has increased.• The liquid product flow rate has decreased.• The sales gas dew point has increased to 15.9oF. Note that this

temperature no longer satisfies the dew point specification of 15oF.

Click the Close button on the ColdGas stream property view to return to the Databook. You can now record the key variables in their new state:

1. Move to the Data Recorder tab in the Databook.

2. Click the Record button, and HYSYS provides you with the default name State 2 for the new state.

3. Change the name to 10 F in LTS, then press the OK button to accept the new name.

Figure 3.107


4. Click the View button and the Data Recorder appears, displaying the new values of the variables.

5. Click the Close button on the Data Recorder, then on the Databook and finally on the Process Data Table.

The basic simulation for this example has now been completed. You can continue with this example by proceeding to the Optional Study, or you can begin building your own simulation case. In the Optional Study, some of the other tools available in HYSYS are explained which will be used to examine the process in more detail.

Optional Study

In this study, the effects of the LTS temperature on the SalesGas dew point and heating value are determined. Before proceeding, re-specify the temperature of ColdGas back to its original value of 0oF:

1. Click the Workbook button on the button bar.

2. On the Material Streams tab of the Workbook, click on the Temperature cell for stream ColdGas.

3. Type 0 and press the ENTER key.

Figure 3.108

Workbook Button

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Using the HYSYS Spreadsheet to Calculate the Heating Value

HYSYS has a SPREADSHEET operation that allows you to import stream or operation variables, perform calculations, and export calculated results.

1. To install a SPREADSHEET and display its property view, double-click on the Spreadsheet button in the Object Palette.

On the Connections tab, change the name from its default to Heating Value. The heating value of the sales gas is calculated by importing the stream composition into the SPREADSHEET, and multiplying the mole fraction of each component by its individual heating value. To import the first variable:

1. Click the Add Import button, and the Select Import view appears.

2. Choose the Object, Variable and Variable Specific as shown. Note that NO2 and CO2 are not included in the calculation, as their individual heating values are negligible.

3. Click the OK button.

Figure 3.109

Spreadsheet Button


4. Repeat steps 1 and 2 for Ethane and Propane. For illustration purposes, the two remaining components will be added using an alternative method.

Notice that HYSYS assigned the imported variables to SPREADSHEET cells A1 through A3, by default. Change these cell locations to B3 through B5 as shown; the reason for doing so will become apparent on the Spreadsheet tab.

No information is required on the Parameters and Formulas tabs, so advance directly to the Spreadsheet tab.

The HYSYS SPREADSHEET behaves similarly to commercial spreadsheet packages; you enter data and formulas in the cells, and calculated results are returned. To complete the SPREADSHEET:

1. Enter the row and column headings as shown. You can move to a cell by clicking it, or by pressing the arrow keys.

Figure 3.110

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2. Enter the component net heating values in the Comp Heat Value column as shown.

The next task is to import the remaining two variables, iC4 and nC4 mole fractions in the sales gas.

1. Position the cursor over the empty SPREADSHEET cell (B6) reserved for iC4 mole fraction.

2. Right-click once. From the menu that appears, select Import Variable.

3. Select SalesGas, Comp Mole Frac, and i-Butane as the Object, Variable and Variable Specific, respectively, on the view that is displayed.

4. Click the OK button to accept the input and close the view.

5. Repeat steps 2 - 4 for nC4, importing into cell B7.

The next task is entering the formulas for calculating the component and total sales gas heating values.

1. Move to cell D3.

2. Type +b3*c3 then press ENTER (or i to automatically advance to the cell below) to multiply the Methane mole fraction by its Net Heating Value. Notice that the formula must be preceded by a +.

Figure 3.111


3. Repeat steps 1 and 2 for cells D4 through D7, multiplying each component mole fraction by its respective heating value.

4. In cell C9, enter the label Sales Gas NHV.

5. Move to cell D9.

6. Enter +d3+d4+d5+d6+d7 in cell D9 to sum the individual heating values. The result is the NHV of SalesGas in Btu/scf.

Figure 3.112

Figure 3.113

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The current heating value of the sales gas is 1080 Btu/scf. Now, whenever flowsheet changes are made (which result in re-calculation of stream SalesGas), the compositional changes will be automatically transferred to the SPREADSHEET, and the heating value updated accordingly. Click the Close button to continue with the study.

Installing an Adjust for Calculating the LTS Temperature

Suppose the market price of your liquid product is currently unfavourable. You might want to raise the LTS temperature in order to leave more of the heavier components in the gas phase. This will increase the sales gas heating value, resulting in a bonus from the transmission company. The sales gas must, however, still comply with the dew point specification.

An ADJUST operation can be used to adjust the temperature of the LTS (i.e. of stream ColdGas) until the sales gas dew point is within a few degrees of the pipeline specification. In effect, this increases the gas heating value, while still satisfying the dew point criteria.

To install, connect, and define the ADJUST:

1. Press the PFD button to display the PFD. The Object Palette should also be visible; if not, press F4.

2. Click the Adjust button on the Object Palette.

Figure 3.114

Note that you could add the value of Sales Gas NHV to the Databook:

1. Move to the Parameters tab of the Heating Value property view.

2. In the Exportable Cells matrix, enter a Variable Name for cell D9 (for example NHV).

3. Close the Heating Value property view.

4. Open the Databook by pressing CTRL D.

5. On the Variables tab, Insert the variable, selecting the Heating Value operation as the Object and NHV as the variable.

The ADJUST operation performs automatic trial-and-error calculations until a target value is reached.

Adjust Button


3. Position the cursor over the PFD, to the right of the SalesDP stream icon.

4. Click to "drop" the ADJUST onto the PFD. HYSYS will create a new ADJUST with the default name ADJ-1.

5. Click the Attach Mode button on the PFD toolbar to enter Attach mode.

6. Position the cursor over the left end of the ADJ-1 icon. The connection point and pop-up "Adjusted Object" appears.

7. With the pop-up visible, left-click and drag toward the ColdGas stream icon.

8. When the solid white box appears at the cursor tip, release the mouse button. The Select Adjusted Variable view appears.

At this point, HYSYS knows that the ColdGas should be adjusted in some way to meet the required target. An adjustable variable for the ColdGas must now be selected from the Select Adjusted Variable view.

1. Select Temperature from the Variable list.


3. Position the cursor over the right end of the ADJ-1 icon. The connection point and pop-up "Target Object" appears.

4. With the pop-up visible, left-click and drag toward the SalesDP stream icon.

5. When the solid white box appears at the cursor tip, release the mouse button. The Select Target Variable view appears.

It is desired to target the sales gas dew point temperature.

Figure 3.115

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1. Select Temperature from the Variable list.


3. Click the Attach button to leave Attach mode.

4. Double-click on the ADJ-1 icon to open its property view.

Notice that the connections made in the PFD have been transferred to the appropriate cells in the property view.

The next step is providing a value for the target variable, in this case the dew point temperature. A 5°F safety margin will be used on the pipeline specification of 15°F, so the desired dew point is 10°F.

1. Enter 10 in the Specified Target Value cell.

2. Move to the Parameters tab.

Figure 3.116


3. Replace the default Tolerance and Step Size with 0.1 (°F) and 5 (°F), respectively. No values will be entered in the Minimum and Maximum field, as these are optional parameters.

4. Move to the Monitor tab.

5. Click the Start button. The ADJUST converges on the target value within the specified tolerance in four iterations. An LTS temperature (adjusted variable) of 4.4°F gives a sales gas dew point (target variable) of 10°F.

The ADJUST has changed the LTS temperature from the original value of 0°F to the current 4.4°F. The new sales gas heating value can now be compared to the previous value to see the effect of this change. Click the Close button on the ADJUST property view. Open the SPREADSHEET using the Object Navigator:

1. Press F3 to access the Navigator.

2. Pick the UnitOps radio button.

3. Double-click on the Heating Value operation in the list of Unit Operations.

Figure 3.117

Figure 3.118

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The NHV has increased to 1091 Btu/scf.

Results of the Study

Open the Workbook to access the calculated results for the entire flowsheet. The Material Streams and Compositions tabs of the Workbook are shown below.

Figure 3.119

Figure 3.120


Figure 3.121

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Refining Tutorial 4-1

4 Refining Tutorial

In this Tutorial, crude oil is processed in a fractionation facility to produce naphtha, kerosene, diesel, atmospheric gas oil, and atmospheric residue products. Preheated crude (from an upstream preheat train) is fed to a pre-flash drum where vapours are separated from the liquids, which are heated in a furnace. The pre-flash vapours bypass the furnace and are recombined with the hot crude from the furnace. The combined stream is then fed to the atmospheric crude column for fractionation. The main flowsheet for this process is shown below.

The crude column consists of a refluxed absorber with three side strippers and three cooled pump around circuits. The column subflowsheet is shown below.

This complete case has also been pre-built and is located in the file TUTOR2.HSC in your HYSYS\SAMPLES directory.

Figure 4.1

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4-2 Refining Tutorial

4-2

The following pages will guide you through building a HYSYS case for modelling this process. This example illustrates the complete construction of the simulation, from selecting a property package and components, characterizing the crude oil, to installing streams and unit operations, through to examining the final results. The tools available in HYSYS are utilized to illustrate the flexibility available to you.

Start HYSYS and create a new case. You need to set your Session Preferences:

1. Open the Tools menu and select Preferences. The Session Preferences view appears.

2. You are now on the Simulation tab with the Options page open. Uncheck Use Modal Property Views by clicking on the check box.

3. Click on the Variables tab (the Units page should be open).

Figure 4.2


1. Create a unit set

2. Choose a property package

3. Select the non-oil components

4. Characterize the Oil

5. Create and specify the preheated crude and utility steam streams

6. Install and define the unit operations in the pre-fractionation train

7. Install and define the crude fractionation column Before proceeding, you should have read Chapter 1 - HYSYS

Tutorials which precedes the Tutorials in this manual.



The first step in building the simulation case is choosing a unit set. HYSYS does not allow you to change any of the three default unit sets listed. However, you can create a new unit set by cloning an existing one. For this example, a new unit set will be made based on the HYSYS Field set, and customized for the new set:

1. In the Available Unit Sets list, click on Field.

2. In the Display Units group, use the vertical scroll bar to select Standard Density (visible in the left column of the matrix).

Notice the default unit for Standard Density is lb/ft3. A more appropriate unit for this example would be API_60.

3. Click the Clone button. A new unit set named NewUser appears and is automatically highlighted, making it the current unit set. If you want, you can enter a new name in the Unit Set Name cell. You can now change the units for any variable associated with this new unit set.

4. Move to the Standard Density cell by clicking on lb/ft3.

5. Open the drop-down list of available units in the Edit Bar by clicking on , (or by pressing the F2 key then the i key).

Figure 4.3

The default Preference file is named HYSYS.prf. When you modify any of the preferences, you can save the changes in a new Preference file by clicking the Save Preference Set button. HYSYS prompts you to provide a name for the new Preference file, which you can later recall into any simulation case by clicking the Load Preference Set button.

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4-4

6. Click on API_60, or scroll down to it by pressing the i key then press ENTER.

7. Repeat steps 4-6 to change the Mass Density units to API as well.

Your new unit set is now defined. Exit this window to define the Simulation Basis Manager.

Figure 4.4

Figure 4.5



Beginning the Simulation

From the Simulation Basis Manager view, you need to define a Fluid Package. A Fluid Package contains the components and property

method (for example, an Equation of State) to be used by HYSYS in its calculations for a particular flowsheet. Depending on what is required in a specific flowsheet, a Fluid Package may also contain other information, such as a petroleum fluid characterization.


Define the Fluid Package:

1. Click the Add button to add a Fluid Package. The Basis-1 view appears.

2. Scroll through the list and choose the Peng Robinson Property Package.

3. Select the non-oil components, including the Light Ends, from the pure component library (H2O, C3, iC4, nC4, iC5, nC5).

4. Characterize the Petroleum Fluid by supplying Assay data, then cutting the Assay into pseudocomponents.

Figure 4.6

Notice that HYSYS displays the current Environment and Mode in the upper right corner of the view. Whenever you begin a new case, you are automatically placed in the Basis Environment, where you can choose the property package and non-oil components.


The Fluid Package for this example will contain the Property Package (Peng Robinson), the pure components (H2O, C3, iC4, nC4, iC5, nC5), and the hypothetical components which will be generated in the Oil characterization.

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5. Add the petroleum pseudocomponents to the Fluid Package.

On the Simulation Basis Manager view, click the Add button. The Fluid Package property view appears.

The property view is divided into a number of tabs to allow you to supply all the information necessary to completely define the Fluid Package. For this example, only the first two tabs, Prop Pkg and Components, are used.

Choosing a Property Package

On the Prop Pkg tab, notice the highlight in the Base Property Package Selection area (currently selecting <none>). Before you begin characterizing your petroleum fluid, you must choose a Property Package that can handle hypothetical components. There are a number of ways to select the desired base property package, in this case Peng Robinson. Do one of the following:

• Type Peng Robinson, and HYSYS finds the match to your input.

• Use the arrow keys i and h to scroll through the list of available property packages until Peng Robinson is highlighted.

• Use the vertical scroll bar to move down the list until Peng Robinson becomes visible, and click on it.

Notice the Property Pkg indicator at the bottom of the view now

Figure 4.7



indicates Peng Robinson is the current property package for this Fluid Package.

As an alternative, you could have selected the EOSs radio button as the Property Pkg Filter, producing a list of only those property packages that are Equations of State. Peng Robinson could have then been chosen from this filtered list, as shown in Figure 4.9.

You should normally leave the Component Selection Control at its default setting (Only Property Package Compatible Components). HYSYS filters the library components to include only those appropriate for the selected Property Package.

Selecting the Non-Oil Components

Now that you have chosen the property package to be used in the simulation, the next step is to select the non-oil components, including the Light Ends:

Figure 4.8

Figure 4.9

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4-8

1. Click on the Components tab in the Fluid Package property view

There are a number of ways to select components for your simulation. One method is to use the matching feature. Notice that each component is listed in three ways:

Atop each of these three columns is a corresponding radio button. Based on the selected radio button, HYSYS locates the component(s) that best match the input you type in the Match cell.

For this example, H2O, C3, i-C4, n-C4, i-C5 and n-C5 are used as the non-oil components. To add H2O using the match feature:

1. Ensure the FullName/Synonym radio button is selected, and the Show Synonyms check box is checked.

2. Move to the Match cell by clicking on it, or by pressing ALT M.

3. Begin typing water. HYSYS filters through its library as you type, displaying only those components that match your input.

Figure 4.10

Naming Convention Description

SimName The name appearing within the simulation.

FullName/Synonym IUPAC name (or similar), and synonyms for many components.

Formula The chemical formula of the component. This is useful when you are unsure of the library name of a component, but know its formula.

Press CTRL SHIFT N to move between the tabs.


4. Now that Water is highlighted, add it to the Current Component List by doing one of the following:

• Press the ENTER key• Click the Add Pure button• Double-click on Water.

In addition to the Match criteria radio buttons, you can also use the Family Filter to display only those components belonging to certain families. For illustration purposes, Propane will be added to the component list using a Family Filter:

1. Ensure the Match cell is empty.

2. Check the Use Filter check box. Click the Family Filter button, and the Families view appears.

3. Since the remaining components are known to be hydrocarbons, check the Hydrocarbons check box. Propane appears near the top of the filtered list.

4. Add Propane to the component list by double-clicking on it. Note that the Match feature remains active when you are using a family filter, so you could have also typed C3 in the Match cell and then added it to the component list.

The next step is to add the remaining Light Ends components i-C4 through n-C5. A quick way to add components that appear consecutively in the library list is to:

1. Click on the first component to be added (in this case, i-C4).


• Hold down the SHIFT key and click on the last component, in this case n-C5. All components i-C4 through n-C5 are now highlighted. Release the SHIFT key.

Figure 4.11

To highlight consecutive components, use the SHIFT key. To highlight non-consecutive components, use the CTRL key.

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4-10

• Click and hold on i-C4, drag down to n-C5, and release the mouse button. i-C4 through n-C5 are highlighted.

3. Click the Add Pure button. The highlighted components are transferred to the Current Component List.

The complete list of non-oil components is shown here. Now that the property package and non-oil components have been selected, the next step is to characterize the oil.

Figure 4.12

Figure 4.13

A component can be removed from the Current Components List by selecting it, and clicking the Remove Comps button or the DELETE key.


Characterizing the Oil

The following laboratory Assay data is available:

Bulk Crude Properties

MW 300.00

API Gravity 48.75

Light Ends Liquid Volume Percent

i-Butane 0.19

n-Butane 0.11

i-Pentane 0.37

n-Pentane 0.46

TBP Distillation Assay

Liquid Volume Percent Distilled

Temperature (F) Molecular Weight

0.0 80.0 68.0

10.0 255.0 119.0

20.0 349.0 150.0

30.0 430.0 182.0

40.0 527.0 225.0

50.0 635.0 282.0

60.0 751.0 350.0

70.0 915.0 456.0

80.0 1095.0 585.0

90.0 1277.0 713.0

98.0 1410.0 838.0

API Gravity Assay

Liq Vol % Distilled API Gravity

13.0 63.28

33.0 54.86

57.0 45.91

74.0 38.21

91.0 26.01

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The HYSYS Oil Characterization procedure is used to convert the laboratory data into petroleum pseudocomponents. Return to the Simulation Basis Manager by clicking on any part of the open view or by clicking the Home View button.

Notice that the list of Current Fluid Packages displays the new Fluid Package, Basis-1, showing the number of components (NC) and property package (PP). The new Fluid Package is assigned by default to the main flowsheet, as shown in the Flowsheet-Fluid Pkg Associations group.

To begin characterizing the oil, move to the Oil Manager tab shown

Viscosity Assay

Liquid Volume Percent Distilled

Viscosity (cP) 100°F Viscosity (cP) 210°F

10.0 0.20 0.10

30.0 0.75 0.30

50.0 4.20 0.80

70.0 39.00 7.50

90.0 600.00 122.30

Figure 4.14Home View button


below.

The Simulation Basis Manager drop-down list indicates which Fluid Package will be used for the oil characterization. Since there is only one Fluid Package, HYSYS has made Basis-1 the Associated Fluid Package. The text box on the right side of the view indicates that before entering the Oil Environment, two criteria must be met:

• at least one Fluid Package must be present. In this case, only one Fluid Package, Basis-1, is selected.

• the Property Package must be able to handle Hypothetical Components. In our case, the Property Package is Peng Robinson, which is capable of handling Hypothetical components.

Since both criteria are satisfied, the oil will be characterized in the Oil Environment. Do one of the following:

• click the Enter Oil Environment button on the Oil Manager tab• click the Oil Environment button on the Button Bar

Figure 4.15

Oil Environment button

The Oil Characterization view allows you to create, modify, and otherwise manipulate the Assays and Blends in your simulation case. For this example, the oil will be characterized using a single Assay.

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The Oil Characterization view appears.

In general, three steps must be completed when you are characterizing a petroleum fluid:

1. Supply data to define the Assay.

2. Cut the Assay into hypothetical components by creating a Blend.

3. Install the hypothetical components into the Fluid Package.

Defining the Assay

On the Assay tab of the Oil Characterization view, click the Add button to create and view a new Assay. The Assay property view appears.

Figure 4.16


When the property view for a new Assay is opened for the first time, the view contains minimal information. Depending on the Assay Data Type you choose, the view will be modified appropriately. For this example, the Assay is defined based on TBP data. Open the Assay Data Type drop-down list by clicking on it. Select TBP, and the view is customized for TBP data.

Figure 4.17

Figure 4.18

HYSYS has given the new Assay the default name of Assay-1. You can change this by typing a new name in the Name cell.

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The next step is to enter the composition of the Light Ends in the Assay. To input the composition:

1. From the Light Ends drop-down list, select Input Composition.

2. In the Input Data group, click on the Light Ends radio button.

3. Ensure that Liquid Volume % is selected from the Light Ends Basis drop-down list.

4. Choose the Composition cell for i-Butane.

5. Type 0.19, then press the ENTER key. You are automatically advanced down one cell to n-Butane.

6. Type the remaining compositions as shown. The total Percent of Light Ends in Assay is calculated and displayed at the bottom of the view.

The following laboratory assay data should be supplied:

• bulk molecular weight and density• TBP Distillation assay data• dependent molecular weight assay data• independent density assay data• independent viscosity assay data (at two temperatures)

Prior to entering any of the assay data, the molecular weight, density and viscosity curves must be activated by choosing appropriate curve

Figure 4.19


types in the matrix above the radio buttons. Currently, these three curves are not used. To activate these curves:

1. Open the Bulk Properties drop-down list and select Used.

2. Open the Molecular Weight drop-down list and select Dependent. A new radio button labelled Molecular Wt Curve appears under the existing radio buttons.

3. Repeat step 2 for the Density and Viscosity curves, selecting Independent as the curve type for both. Note that for Viscosity, two radio buttons are added as HYSYS allows you to input viscosity assay data at two temperatures.

Your view now has a total of seven radio buttons in the Input Data group. The laboratory data will be input in the same order as the radio buttons appear.

Entering Bulk Property Data

The two bulk properties of the Assay, a molecular weight of 300 and a density of 48.75°API, are known. To enter this data:

1. Pick the Bulk Props radio button, and the bulk property matrix appears to the right of the radio buttons.

2. Choose the Molecular Weight cell in the matrix. Type 300 and press ENTER. You are automatically advanced down one cell, to the Standard Density cell.

3. Type 48.75 and press SPACE. Your input appears in the Edit Bar at the top of the view. To the right of the Edit Bar, the Unit Box displays the current default unit associated with the active matrix

Figure 4.20

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cell. When the new unit set was created, the default unit for standard density was specified as API_60, which appears in the Unit Box.

4. Since this is the correct unit, press ENTER, and HYSYS accepts the density.

No bulk Watson UOPK or Viscosity data is available for this assay. Notice that HYSYS provides two default temperatures (100°F and 210°F) for entering bulk viscosity. These temperature values are ignored unless corresponding viscosities are provided. Since the value for bulk viscosity is not supplied, there is no need to delete or change the temperature values.

Entering Boiling Temperature (TBP) Data

The next step is to enter the TBP distillation data:

1. On the Calculation Defaults tab, select Lagrange from the Distillation drop-down list.

2. Return to the Input Data tab.

3. Pick the Distillation radio button, and the corresponding TBP data matrix appears. HYSYS displays a message under the matrix, stating that At least 5 points are required before the assay can be calculated.

4. Click on the Edit Assay button. The Assay Input Table view appears.

Figure 4.21


5. Click on the top cell in the Assay Percent column of the matrix.

6. Type 0 then press the ENTER key. You are automatically advanced to the corresponding empty Temperature cell.

7. Type 80 then press the ENTER key. You are automatically advanced down to the next empty Assay Percent cell.

8. Repeat steps 5 and 6 to enter the remaining Assay Percent and Temperature values as shown.

9. Click the OK button to return to the Assay property view.

Entering Molecular Weight Data

Pick the Molecular Wt radio button, and the corresponding assay matrix appears. Since the Molecular Weight assay is Dependent, the Assay Percent column displays the same values as those you entered for the Boiling Temperature assay. Therefore, you need only enter the Molecular Weight value for each assay percent:

1. Click the Edit Assay button and the Assay Input Table view appears.

2. Click on the first empty cell in the Mole Wt column.

3. Type 68, then press the i key.

Figure 4.22

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4. Type the remaining Molecular Weight values as shown.

5. Click the OK button when you are finished.

Entering Density Data

Pick the Density radio button, and the corresponding assay matrix appears. Since the Density assay is Independent, you must input both the Assay Percent and Density values. Using the same method as for the previous assays, enter the API gravity curve data as shown here.

Figure 4.23

Figure 4.24


Entering Viscosity Data

To enter the viscosity data:

1. Pick the Viscosity 1 radio button, and the corresponding assay matrix appears. Two drop-down lists appear above the assay matrix, allowing you to specify the Assay Basis, and Viscosity Type (Kinematic or Dynamic). The Temperature field is for each of the two viscosity curves.

2. Input the Viscosity 1 assay data as shown here. This viscosity curve corresponds to Temperature 1, 100°F.

3. Choose the Viscosity 2 radio button and enter the assay data corresponding to Temperature 2, 210°F, as shown.

The Assay is now completely defined based on our available data, so click the Calculate button at the bottom of the Assay view. HYSYS calculates the Assay, and the status message at the bottom of the view changes to Assay Was Calculated. Move to the Working Curves tab of the Assay property view to view the calculated results.

Figure 4.25

Figure 4.26

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HYSYS has calculated 50 points for each of the Assay Working Curves. You can use the vertical scroll bar to view the properties of the points that are not currently visible. To view the data you input for the Assay in a graphical format, move to the Plots tab. The input curve that appears is dependent on the current variable in the Property drop-down list in the Property Selection group. By default, HYSYS plots the BoilingPt (TBP) data. This plot is shown in Figure 4.28.

Figure 4.27

Figure 4.28


Note that the view shown above has been re-sized to make the plot more readable. To re-size the view, do one of the following:

• click and drag the outside border to the new size• click the Maximize button

The independent (x-axis) variable is the Assay percent, while the dependent variable is the TBP in °F. You can view any of the other input curves by selecting the appropriate variable in the Property drop-down list.

The remaining tabs in the Assay property view provide access to information which is not required for this tutorial. Click the Close button to return to the Oil Characterization view. Now that the assay has been calculated, the next step is to cut the assay into individual petroleum pseudocomponents.

Generating Pseudocomponents (Creating the Blend)

Advance to the Cut/Blend tab of the Oil Characterization view. Press the Add button, and HYSYS creates a new Blend and displays its property view.

Figure 4.29

Maximize button

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In the list of Available Assays, select Assay-1. Click the Add button, and there are two results:

• The Assay is transferred to the Oil Flow Information matrix. (Note that when you have only one Assay, there is no need to enter a Flow Rate in this matrix.)

• A Blend (Cut) is automatically calculated based on the current Cut Option.

In this case, the Blend was calculated based on Auto Cut, the default Cut Option. HYSYS calculated the Blend based on the following default values for the boiling point ranges and number of cuts per range:

• IBP to 800°F: 25°F per cut, generating [(800-IBP)/25] pseudocomponents

• 800 to 1200°F: 50°F per cut, generating 8 pseudocomponents• 1200 to 1400°F: 100°F per cut, generating 2

pseudocomponents

Notice that the IBP, or initial boiling point, is the starting point for the first temperature range. The IBP is the normal boiling point (NBP) of the heaviest component in the Light Ends, in this case n-Pentane. The NBP of n-Pentane is 96.9°F, so the first range results in the generation of (800-96.9)/25 = 28 pseudo components. All the cut ranges together have resulted in a total of 28+8+2 = 38 pseudo components. Move to the Tables tab to view the calculated properties of these pseudocomponents.

Figure 4.30


These components could be used in the simulation. Suppose, however, that you do not want to use the IBP as the starting point for the first temperature range. You could specify another starting point by changing the Cut Option to User Ranges. For illustration purposes, 100°F will be used as the initial cut point.

To specify the new initial cut point:

1. Return to the Data tab by clicking on it.

2. Click on the Cut Option Selection drop-down list.

3. Select User Ranges from the drop-down list, and the Ranges Selection group appears.

4. Enter 100 in the Initial Cut Point cell. This is the starting point for the first range, in °F. The same values as the HYSYS defaults will be used for the other temperature ranges.

5. Click on the top cell, labelled <empty>, in the Cut Point T column in the matrix. The value entered in this cell is the upper cut point temperature for the first range (and the lower cut point for the second range).

6. Type 800, then press i.

7. Enter the remaining cut point temperatures and the Num. of Cuts as shown.

Figure 4.31

Since the NBP of the heaviest Light Ends component is the starting point for the cut ranges, these pseudocomponents were generated on a "light-ends-free" basis. That is, the Light Ends are calculated separately and are not included in these pseudocomponents.

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8. Once you have entered the data, click the Submit button to calculate the Blend based on the current initial cut point and range values. The completed Data tab of the Blend property view is shown in Figure 4.32.

Move to the Tables tab to view the properties of the petroleum pseudocomponents.

You can use the vertical scroll bar to view the components which are not currently visible in the Component Physical Properties matrix.

Figure 4.32

Figure 4.33

Notice that HYSYS has provided the Initial Boiling Point (IBP) and Final Boiling Point (FBP). The IBP is the normal boiling point (NBP) of the heaviest component in the Light Ends (in this case, n-Pentane). The FBP is calculated by extrapolating the TBP Assay data to 100% distilled.


Viewing the Oil Distributions

To view the distribution data, select Oil Distributions from the Table Type drop-down list. The Tables tab is modified as shown below.

At the bottom of the Cut Input Information group, the Straight Run radio button is selected, and HYSYS provides default TBP cut point temperatures for each Straight Run product. The Cut Distributions matrix shows the Fraction of each product in the Blend. Since Liquid Vol is the current Basis in the Table Control group box, the products are listed according to liquid volume fraction.

These fractions can be used to estimate the product flow rates for the fractionation column. For example, the Kerosene liquid volume fraction is 0.128. With 100,000 bbl/day of crude feeding the tower, the Kerosene production is expected at 100,000 * 0.128=12,800 or roughly 13,000 bbl/day.

If you want, you can investigate other reporting and plotting options by selecting another Table Type or by moving to the other tabs in the Blend property view. When you are finished, click the Close button on the Blend view to return to the Oil Characterization view. Now that the Blend has been calculated, the next step is to install the oil.

Figure 4.34

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Installing the Oil

The last step in the oil characterization procedure is to install the oil, which will accomplish the following:

• the petroleum pseudocomponents will be added to the Fluid Package

• the calculated Light Ends and Oil composition will be transferred to a material stream for use in the simulation

To install the oil:

1. Move to the Install Oil tab of the Oil Characterization view.

2. Click on the top blank cell in the Stream Name column.

3. Type the name Preheat Crude, then press the ENTER key. HYSYS creates a new stream named Preheat Crude in the flowsheet associated with the fluid package associated with this oil.

In this case, there is only one Fluid Package (Basis-1) and one flowsheet (the main flowsheet), so the stream will be created in the main flowsheet. HYSYS assigns the composition of the calculated oil and light ends to stream Preheat Crude. The properties of the new stream will be viewed from the Simulation environment.

The characterization procedure is now complete.

1. Return to the Basis environment by clicking the Return to Basis

Figure 4.35

Return to Previous Environment button


Environment button.

2. Highlight the listed property package (Peng Robinson) and click on the View button (on the Fluid Pkgs tab) to open the Fluid Package property view.

3. Click on the Components tab. The pseudocomponents generated during the oil characterization procedure now appear in the Current Component List. Hypothetical components are indicated by a * after the component name.


To view the properties of one or more components, highlight the component(s) and press the View Comp button. HYSYS opens the property view(s) for the component(s) you selected. For example:

1. Click on H2O.


3. Click on a hypothetical component, such as NBP[0]110*. These two components should now be highlighted.


Figure 4.36

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5. Click the View Comp button. The property views for these two components appears.

The Component property view provides you with complete access to the component information. For pure components (like H2O), the information is provided for viewing only. You cannot modify any parameters for a library (pure) component; however, HYSYS has an option for cloning a library component into a Hypothetical component, which can then be modified as desired. See Chapter 2 - Hypotheticals in the HYSYS Simulation Basis guide for more information on cloning library components.

The petroleum pseudocomponent shown here is an example of a hypothetical component. You can modify any of the parameters listed for this component. For this example, the properties of the hypothetical components generated during the oil characterization will not be changed. Close each of these two component property views.

The Fluid Package is now completely defined, so close the Fluid Package view. The Simulation Basis Manager should again be visible; if not, click the Basis Manager button to access it. Return to the Fluid Pkgs tab to view a summary of the new Fluid Package.

Notice that the list of Current Fluid Packages displays the new Fluid

Figure 4.37

Basis Manager button


Package, Basis-1, showing the number of components (NC) and property package (PP). The Fluid Package has a total of 44 components:

• 6 library (pure) components (H2O plus five Light Ends components)

• 38 petroleum pseudocomponents

The new Fluid Package is assigned by default to the Main Flowsheet, as shown in the Flowsheet-Fluid Pkg Associations group. Now that the Basis is defined, you can install streams and operations in the Main Simulation Environment. To enter this environment and leave the Basis environment, do one of the following:

• click the Enter Simulation Environment button on the Simulation Basis Manager

• click the Simulation Environment button

Simulation Environment

When you enter the Simulation Environment, the initial view that appears is dependent on your current preference setting for the Initial Build Home View. Three initial views are available, namely the PFD, Workbook and Summary. Any or all of these can be displayed at any time; however, when you first enter the Simulation Environment, only one will be displayed. For this example, the initial Home View is the Workbook (HYSYS default setting).

Figure 4.38

Simulation Environment button

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You will notice several things about the Main Simulation Environment. In the upper right corner, the Environment has changed from Basis to Case (Main). A number of new items are now available on the Menu and Button Bar, and the Workbook and Object Palette are open on the Desktop. These latter two objects are described below.

Also notice that the name of the stream (Preheat Crude) you created

Figure 4.39

You can toggle the palette open or closed by pressing F4, or by choosing Open/Close Object Palette from the Flowsheet menu.

Objects Description

Workbook

A multiple-tab view containing information regarding the objects (streams and unit operations) in the simulation case. By default, the Workbook has four tabs, namely Material Streams, Compositions, Energy Streams and Unit Ops. You can edit the Workbook by adding or deleting tabs, and changing the information displayed on any tab.



during the Oil characterization procedure appears in the Workbook, and the Object Status window shows that the stream has an unknown pressure. While specifying the conditions of Preheat Crude, the message displayed in the Object Status window will be updated appropriately. Before specifying the feed conditions, the stream composition can be viewed, which was calculated by the Oil characterization.

Viewing the Feed Composition

In the Workbook, click on the Compositions tab to view the composition of the streams.

The light ends and petroleum pseudocomponents are listed by Mole Fraction. To view the components which are not currently visible, use the keyboard arrow keys i and h or the vertical scroll bar to advance down the component list.

Before proceeding any further to install streams or unit operations, it is probably a good idea to save your case.


• Click the Save button on the button bar• Select Save from the File menu• Press CTRL S

As this is the first time you have saved your case, the Save

Figure 4.40

Save button

Open Case button

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Simulation Case As dialog box appears. By default, the File Path is the cases sub-directory in your HYSYS directory.

2. In the File Name cell, type a name for the case, for example REFINING. You do not have to enter the .hsc extension; HYSYS adds it automatically.

3. Once you have entered a file name, press the ENTER key or the OK button. When you click the Save button, HYSYS saves the case under the name you gave it. The Save As dialog box does not appear again unless you choose to give it a new name using the Save As command.

Before specifying the feed conditions or installing any operations, the simulated process will be summarized.

Process Description

This example models a crude oil processing facility consisting of a pre-fractionation train used to heat the crude liquids, and an atmospheric crude column to fractionate the crude into its straight run products. The Main Flowsheet for this process is shown on the next page.

Preheated crude (from a preheat train) is fed to the pre-flash drum, modelled as a SEPARATOR, where vapours are separated from the crude liquids. The liquids are then heated to 650°F in the crude furnace, modelled as a HEATER. The pre-flash vapours bypass the furnace and are re-combined, using a MIXER, with the hot crude stream. The combined stream is then fed to the atmospheric crude column for separation.

The crude column is modelled as a RELUXED ABSORBER, equipped

When you choose to open an existing case by clicking the Open Case button, or by selecting Open Case from the File menu, a view similar to the one shown here appears. The File Filter drop-down list then allows you to retrieve backup (*.bk*) and HYSIM (*.sim) files in addition to standard HYSYS (*.hsc) files.


Figure 4.41


with three pump-around and three side-stripper operations. The Column Sub-Flowsheet is shown on the next page.

The main column consists of 29 trays plus a partial condenser. The TowerFeed enters on stage 28, while superheated steam is fed to the bottom stage. In addition, the trim duty is represented by an energy stream feeding onto stage 28. The Naphtha product, as well as the water stream WasteH2O, are produced from the three-phase condenser. Crude atmospheric Residue is yielded from the bottom of the tower.

Each of the three-stage side strippers yields a straight run product. Kerosene is produced from the reboiled KeroSS side stripper, while Diesel and AGO (atmospheric gas oil) are produced from the steam-stripped DieselSS and AGOSS side strippers, respectively.

The two primary building tools, Workbook and PFD, will be used to install the streams and operations and to examine the results while progressing through the simulation. Both of these tools provide you with a large amount of flexibility in building your simulation, and in quickly accessing the information you need.

The Workbook will be used to build the first part of the flowsheet, starting with specifying the feed conditions, then creating the utility

Figure 4.42

The Workbook displays information about streams and unit operations in a tabular format, while the PFD is a graphical representation of the flowsheet.

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steam streams, through to installing the pre-flash separator. The PFD will then be used to install the remaining operations, starting with the crude furnace, through to the column.

Using the Workbook

Click the Workbook button on the button bar to ensure the Workbook window is active.

Specifying the Feed Conditions

In general, the first step when you enter the Simulation environment is to install one or more feed streams. However, the new stream Preheat Crude was already installed during the oil characterization procedure.

At this point, your current location should be the Compositions tab of the Workbook. To define the feed conditions:

1. Click on the Material Streams tab. The preheated crude enters the pre-fractionation train at 450°F and 75 psia.

2. Click on the Temperature cell for Preheat Crude.

3. Type 450 in the Temperature cell, and your input appears in the Edit Bar at the top of the view. In the Unit Box, HYSYS displays the default units for temperature, in this case F.

4. Since this is the correct unit, press the ENTER key or the Accept button, and HYSYS accepts the temperature. Notice that when you pressed ENTER after typing in the stream temperature, HYSYS automatically advanced the active cell down one, to Pressure. Suppose you know the stream pressure in another unit besides the default of psia, and you do not have quick access to the conversion factor. HYSYS will accept your input in any one of a number of different units, and automatically convert to the default for you. For example, the pressure of Preheat Crude is 5.171 bar. To enter this pressure:

5. Type 5.171.

Figure 4.43

Workbook button

When you press ENTER after entering a stream property, you are advanced down one cell in the Workbook only if the cell below is <empty>. Otherwise, the active cell will remain in its current location.


6. Press SPACE or click on .

7. The unit box becomes active. HYSYS now matches your input to locate the unit of your choice.

8. Begin typing bar. The unit box opens and scrolls down to the unit(s) most closely matching your input.

9. Once bar is highlighted, press the ENTER key or the Accept button, and HYSYS accepts the pressure. Notice that it automatically converts to the default unit, psia.Alternatively to steps 8 and 9, you could have specified the unit simply by selecting it in the drop-down list.The Molar Flow cell for Preheat Crude should now be your active Workbook location. The stream flow is entered on a volumetric basis, in this case 100,000 bbl/day.

10. Advance to the Liquid Volume Flow cell for Preheat Crude by clicking on it or by pressing the i key.

11. Type 1e5 (the volumetric flow in scientific notation). Change the units for liquid volume flow to barrel/day.

12. Press the ENTER key.

The stream is now completely defined, so HYSYS will flash it at the conditions given to determine the remaining properties. The properties of Preheat Crude are shown below. Notice that the values you specified are a different colour (blue) than the calculated values (black).

Figure 4.44

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The next step is to install and define the utility steam streams which will be later attached to the fractionation tower.

Installing the Utility Steam Streams

To create and define the new streams:

1. Click on the cell labelled **New** on the Material Streams tab of the Workbook.

2. Type the new stream name Bottom Steam. Note that HYSYS accepts blank spaces within a stream or operation name.

3. Press ENTER, and HYSYS automatically creates the new stream with the name you have given it as shown below.

Figure 4.45


4. Define the steam conditions by entering the steam Temperature as 375°F and the Pressure as 150 psia.

5. The Molar Flow cell for Bottom Steam should now be your current Workbook location. Type the Mass Flow of this utility stream as 7500 lb/hr.

6. Press the ENTER key or the Accept button.

7. Repeat steps 2 - 6 for the next utility stream, naming it Diesel Steam. The conditions of this stream are 300°F, 50 psia and 3000 lb/hr. Your Workbook appears as shown below.


Now that the utility stream conditions have been specified, the next task is to input the compositions:

1. Move to the Compositions tab in the Workbook. The components

Figure 4.46

Figure 4.47

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are listed by Mole Fraction by default.

2. Move to the input cell for the first component, H2O, associated with stream Bottom Steam.

3. Since the stream is all water, type 1 for the H2O mole fraction, and press ENTER. HYSYS displays the Input Composition for Stream view, allowing you to complete the compositional input.


Figure 4.48

The Input Composition for Stream view is Modal, indicated by the thick border and the absence of the Minimize/Maximize buttons in the upper right corner. When a Modal view is visible, you are unable to move outside the view until you finish with it, by clicking either the Cancel or OK button.

Features Description

Compositional Basis Radio Buttons



This stream is pure water, therefore, there is no need to enter fractions for any other components.

4. Click the Normalize button, and all other component fractions are forced to zero.

5. Click the OK button, and HYSYS accepts the composition. You are returned to the Workbook.

The stream is now completely defined, so HYSYS flashes it at the conditions given to determine the remaining properties.

6. Repeat steps 2 - 5 for the other utility stream, Diesel Steam.

Return to the Material Streams tab. The calculated properties of the

Normalizing

The Normalizing feature is useful when you know the relative ratios of components; for example, 2 parts N2, 2 parts CO2, 120 parts C1, etc. Rather than manually converting these ratios to fractions summing to one, simply enter the individual numbers of parts and click the Normalize button. HYSYS computes the individual fractions totalling 1.0.

Normalizing is also useful when you have a stream consisting of only a few components. Instead of specifying zero fractions (or flows) for the other components, simply enter the fractions (or the actual flows) for the non-zero components, leaving the others <empty>. Then click the Normalize button, and HYSYS will force the other component fractions to zero.


As you input the composition, the component fractions (or flows) initially appear in red, indicating the final composition is unknown. These values become blue when the composition has been calculated. Three scenarios result in the stream composition being calculated:

• Input the fractions of all components, including any zero components, such that their total is exactly 1.0000. Then click the OK button.

• Input the fractions (totalling 1.000), flows or relative number of parts of all non-zero components. Then click the Normalize button then the OK button.

• Input the flows or relative number of parts of all components, including any zero components, and then click the OK button.


Note that these are the default colours; yours may appear differently depending on your settings on the Colours page of the Session Preferences view.

If you want to delete a stream, move to the Name cell for the stream, then press DELETE. HYSYS will ask for confirmation of your action.

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two utility streams are displayed here.

Alternatively to installing streams via the Workbook, there are a number of ways to create a new stream with a default name. To add the third utility stream, do any one of the following:

• Press F11• From the Flowsheet menu, select Add Stream• Double-click the Material Stream button on the Object Palette• Click the Material Stream button on the Object Palette, then


Each of these four methods displays the property view for the new stream, which is named according to the Auto Naming setting in your Preferences. The default setting names new material streams with numbers, starting at 1 (and energy streams starting at Q-100).

Conditions is the active page when the view is initially accessed. The Stream Name cell is active, as indicated by the thick border around this cell, as well as the appearance of the name 1 in the Edit Bar.

To define this stream:

1. Replace the name by typing AGO Steam. Press ENTER.

2. Type 300 and 50 in the Temperature and Pressure cells, respectively. Note that both of these parameters are in the default units, so you do not need to provide a unit with the values. (Do not enter a flow, it will be entered through the Composition page.)

Figure 4.49

Add Object button

Material Stream button


3. Move to the Composition page to begin the compositional input for the new stream.

4. Click the Edit button (under the compositions matrix), and the Input Composition for Stream view appears. Note that the current Composition Basis setting is set to the Preferences Default of Mole Fractions. The stream composition will be entered on a mass basis.

Figure 4.50

Figure 4.51

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5. Change the Composition Basis to Mass Flows by picking the appropriate radio button, or by pressing ALT A.

6. Click on the compositional cell for H2O. Type 2500 for the steam mass flow, and press ENTER. As there are no other components in this stream, the compositional input is complete.

7. Click the Normalize button, and HYSYS forces all other component flows to zero.

Figure 4.52


8. Click the OK button to close the view and return to the stream property view.

HYSYS has performed a flash calculation to determine the unknown properties of AGO Steam, as shown by the status indicator displaying OK. You can view the properties of each phase using the horizontal scroll bar in the matrix or by re-sizing the property view. In this case, the stream is superheated vapour, so no Liquid phase exists and the Vapour phase is identical to the overall phase. To view the vapour compositions for AGO Steam, scroll to the right by clicking the right scroll arrow, or by clicking and dragging the scroll button.

Note that the compositions are currently displayed by Mass Flows. You can change this by clicking the Basis button and choosing another Composition Basis radio button.

Figure 4.53

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Now that the feed and utility streams are known, the next step is to install the necessary unit operations for processing the crude oil.

Installing the Separator

The first operation is a SEPARATOR, used to split the feed stream into its liquid and vapour phases. As with most commands in HYSYS, installing an operation can be accomplished in a number of ways. One method is through the Unit Ops tab of the Workbook. To install the separator:

1. Click the Workbook button to ensure the Workbook is the active view.


3. Click the Add UnitOp button. The UnitOps view appears listing all available unit operations.

4. In the Categories group, select the Vessels radio button. HYSYS produces a filtered list of unit operations, showing only those in the current category.

Figure 4.54

Workbook button


5. Add the separator by doing one of the following:

• select Separator in the list of Available Unit Operations, and click the Add button or the ENTER key

• double-click on Separator

The property view for the separator is shown here. As with a stream, a unit operation property view contains all the information defining the operation, organized into pages on different tabs. The three tabs shown for the separator, namely Design, Rating and Worksheet, are contained in the property view for most operations. Property views for more complex operations contain more tabs. Notice that HYSYS has provided the default name V-100 for the separator. As with streams, the default naming scheme for unit operations can be changed in your Session Preferences.

Figure 4.55

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Many operations, like the separator, accept multiple feed streams. Whenever you see a matrix like the one for Inlets, the operation will accept multiple stream connections at that location. When the matrix is active, you can access a drop-down list of available streams in the Edit Bar.


1. Double-click on the Name cell to ensure it is active. The existing name is highlighted.

2. Type the new name PreFlash, and press ENTER.

3. Click on the <<Stream>> cell to make the Inlets matrix active. The status indicator at the bottom of the view is showing that the operation needs a feed stream.

4. Open the Edit Bar drop-down list of available streams by clicking on it, or by pressing F2.

Select Preheat Crude from the list. The stream is transferred to the list of Inlets, and <<Stream>> is automatically moved down to a new empty cell. Alternatively, you could have made the connection by typing the exact stream name in the cell, and pressing ENTER.

Figure 4.56


The status indicator now displays Requires a product stream.

5. Move to the Vapour Outlet cell by pressing TAB, or by clicking on it.

6. Type PreFlashVap in the cell, and press ENTER. HYSYS recognizes that there is no existing stream with this name, so it creates this new stream.

7. Repeat steps 5 and 6 for the Liquid Outlet, naming the new stream PreFlashLiq.

Figure 4.57

Figure 4.58

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Note that an Energy stream could be attached to heat or cool the vessel contents. However, for the purposes of this example, the energy stream is not required.

Advance to the Parameters page by clicking on it. The default Delta P (pressure drop) of zero is acceptable for this example. The Liquid Level is also acceptable at its default value. Since there is no energy stream attached to the separator, no Optional Heat Transfer information is required.

To view the calculated outlet streams, move to the Worksheet tab. This is a condensed Workbook displaying only those streams attached to the

Figure 4.59


operation.

Now that the separator is completely known, close the view to return to the Workbook. The new operation is displayed in the matrix on the Unit Ops tab of the Workbook.

The matrix shows the operation Name, its Object Type, the attached streams (Feeds and Products), whether it is Ignored, and its Calculation Level. When you click the View UnitOp button, the property view for the operation occupying the active row in the matrix opens. Alternatively, by double-clicking on any cell (except Feeds and

Figure 4.60

Figure 4.61

Close View button

Note that the Workbook shown here contains a tab called P,T,Flow. You will be shown how to add this tab later on in this tutorial.

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Products) associated with the operation, you also open its property view.

You can also open the property view for a stream directly from the Unit Ops tab of the Workbook. When any of the Name, Object Type, Ignored or Calc. Level cells are active, the box at the bottom of the view displays all streams attached to the current operation. Currently, the Name cell for PreFlash is active, and the box displays the three streams attached to this operation. To open the property view for one of the streams attached to the separator (such as Preheat Crude), do one of the following:

• double-click on Preheat Crude in the box at the bottom of the view

• double-click on the Feeds cell for PreFlash. The property view for the first listed feed stream is opened. In this case, Preheat Crude is the only feed stream, so its property view also opens.

Workbook Features

Before installing the remaining operations, a number of Workbook features that allow you to access information quickly and change how information is displayed will be shown. Return to the Material Streams tab of the Workbook.



• When your current location is a Workbook streams tab (such as any one of the Material Streams, Compositions and Energy Streams tabs), the box at the bottom of the Workbook view displays the operations to which the current stream is attached. For example, click on any cell associated with the stream Preheat Crude. The box displays the name of the only operation, PreFlash, to which this stream is attached. To access the property view for this operation, double-click on the corresponding operation name.

Adding a tab to the Workbook

Notice that when the Workbook is active, the Workbook item appears in

Any utilities attached to the stream with the Workbook active are also displayed in (and are accessible through) this box.


the HYSYS menu. This item allows you to customize the Workbook according to the information you want to display.

Suppose you want to create a new Workbook tab that displays only stream pressure, temperature, and flow. To add a new tab:


• From the Workbook menu, select Setup.• Object inspect (right-click once) the Material Streams tab in

the Workbook, and select Setup from the menu that appears.

Figure 4.62

The operation to which Preheat Crude is attached is displayed in this box. You can access the property view for the operation view by double-clicking on the operation name.

Stream Preheat Crude is the current Workbook location.

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The Workbook Setup view appears.

Notice that the four existing tabs are listed in the Workbook Pages area. When you add a new tab, it will be inserted before the highlighted tab (currently Material Streams). A new tab will be added before the Compositions tab.

2. Click on the Compositions tab in the list of Workbook tabs.

Figure 4.63

Currently, all variables are displayed with four significant figures. You can change the display format or precision of any Workbook variables by clicking the Format button.


3. Click the Add button in the Workbook Pages group. The New Object Type view appears.

4. Click on Material Stream and click the OK button. You return to the Setup view, and the new tab is added after the existing Material Streams tab.

5. In the Object group, click on the Name cell. Change the name for the new tab from the default Material Streams 2 to P,T,Flow to better describe the tab contents.

The next task is to customize the tab by removing the variables that are not required.



Figure 4.64

Figure 4.65

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3. Click on the other variables, Molar Flow, Mass Flow, Heat Flow and Molar Enthalpy. These four variables are now highlighted.


5. Click the Delete button to remove them from this Workbook tab only. If you want to remove variables from another tab, you must edit each tab individually. The finished Setup is shown below.

Figure 4.66

The new tab displays only these three Variables.

The new tab now appears in the list of Workbook pages, in the same order as it will appear in the Workbook.


Click the Close button to return to the Workbook and view the new tab.

At this point, it is a good idea to save your case by doing one of the following:

• click the Save button on the button bar• select Save from the File menu• press CTRL S

Using the PFD

Besides the Workbook, the PFD is the other main view in HYSYS. To open the PFD, click the PFD button on the button bar. The PFD item appears in the HYSYS menu whenever the PFD is active.

When you open the PFD view, it appears similar to the one shown below, except some stream icons will be overlapping each other.

Figure 4.67

Save button

PFD button

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As a graphical representation of your flowsheet, the PFD shows the connections among all streams and operations, also known as "objects". Each object is represented by a symbol, also known as an "icon". A stream icon is an arrow pointing in the direction of the flow, while an operation icon is a graphic representing the actual physical operation. The object name, also known as a "label", appears near each icon.

The PFD shown above has been rearranged by moving the three utility stream icons below and to the left of the SEPARATOR. To move an icon, simply click and drag it to the new location. Note that you can click and drag either the icon (arrow) itself, or the label (stream name), as these two items are grouped together.

Figure 4.68

PFD Button Bar Stream/Operation labels

Unit Operation icon for a Separator

Material Stream icon



• access commands and features through the PFD Button Bar.• open the property view for an object by double-clicking on its

icon.• move an object by clicking and dragging it to the new location.• access "pop-up" summary information for an object simply by

placing the cursor over it.• change an icon's size by clicking the Size button, clicking on

the icon, and clicking and dragging the sizing "handles" that appear.

• display the Object Inspection menu for an object by placing the cursor over it, and right-clicking. This menu provides access to a number of commands associated with the particular object.

• zoom in and out, or display the entire flowsheet in the PFD window by clicking the zoom buttons at the bottom left of the PFD view.

Some of these functions are illustrated here; for further information, see Chapter 3 - PFD in the HYSYS User’s Guide.

Calculation Status


Size Mode button

Zoom Out 25%

Display Entire PFD

Zoom In 25%

Status Description

Red Status


Yellow Status


Green Status The stream or operation is completely defined and solved. The status indicator is green, and an OK message is displayed.


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When you are in the PFD, the streams and operations are "colour-coded" to indicate their calculation status. The inlet separator is completely calculated, so its normal colours are displayed. While installing the remaining operations through the PFD, their colours (and status) will change appropriately as information is supplied.


Installing the Crude Furnace

The furnace will be modelled as a HEATER. You can install streams or operations by dropping them from the Object Palette onto the PFD. Make sure the Object Palette is displayed (if it is not, press F4). The furnace will be added to the right of the PreFlash Separator, so make some empty space available by scrolling to the right using the horizontal scroll bar. To install and connect the Furnace,

1. Click the Heater button on the Object Palette.

2. Position the cursor over the PFD, to the right of the separator. The cursor changes to a special cursor, with a box and plus (+) symbol attached to it. The box indicates the size and location of the operation icon.

Notice that the icons for all streams installed to this point are dark blue, indicating they have been flashed.

Heater Button (Red icon)

Cooler Button (Blue icon)

Figure 4.69

Attach button


3. Click to "drop" the heater onto the PFD. HYSYS will create a new heater with a default name, E-100. Notice that the heater has red status (colour), indicating that it requires feed and product streams. The heater icon can be changed from its default to one more closely resembling a furnace.

4. Object inspect the heater icon by placing the cursor over it and right-click. The object inspection menu appears.

5. Select Change Icon from the object inspection menu, and the Select Icon view appears.

6. Click on the WireFrameHeater5 icon (scroll to the right), then press the OK button. The newly selected icon will appear in the PFD.

7. Press the Attach button on the PFD toolbar to enter Attach mode.

8. Position the cursor over the right end of the PreFlashLiq stream icon. A small box appears at the cursor tip. At the square connection point, a pop-up description appears attached to the cursor. The pop-up "Out" indicates which part of the stream is available for connection, in this case, the stream outlet.

9. With the pop-up "Out" visible, left-click over it. The transparent box becomes solid black, indicating that you are beginning a connection.

10. Move the cursor toward the left (inlet) side of the heater. A trailing line appears between the PreFlashLiq stream icon and the cursor, and a connection point appears at the heater inlet.

Figure 4.70

Figure 4.71

Furnace Icon

Attach Mode button

When you are in Attach mode, you will not be able to move objects in the PFD. To return to Move mode, press the Attach button again. You can temporarily toggle between Attach and Move mode by holding down the CTRL key.

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11. Place the cursor near the connection point, and the trailing line snaps to that point. As well, a solid white box appears at the cursor tip, indicating an acceptable end point for the connection.

12. Release the left mouse button, and the connection is made to the connection point at the heater inlet.

13. Position the cursor over the right end of the heater icon. The connection point and pop-up "Product" appears.


15. Move the cursor to the right of the heater. A large stream icon appears, with a trailing line attached to the heater outlet. The stream icon indicates that a new stream will be created when you complete the next step.


17. Repeat steps 13-16 to create the heater energy stream. Originate the connection from the bottom left connection point labelled "Energy Stream" on the heater icon, and drag below and to the left of the furnace. The new stream is automatically named Q-100, and the heater now has yellow (warning) status. This status indicates that all necessary connections have been made, but the attached streams are not entirely known.

18. Click the Attach button again to return to Move mode.

Figure 4.72

Figure 4.73

Figure 4.74


The heater outlet and energy streams are unknown at this point, so they are light blue and light red, respectively. Double-click on the heater icon to open its property view. On the Connections page, notice that the names of the Inlet, Outlet and Energy streams appear in the appropriate cells. Change the operation name from the default to Furnace, then click on the Parameters page. Specify a Delta P of 10 psi, and close the view.

The Furnace has one available degree of freedom; either the outlet stream temperature, or the amount of duty in the energy stream can be specified. In this case, the outlet temperature will be specified.

Figure 4.75

Figure 4.76

Break Connection button


1. Click the Break Connection button on the PFD button bar.

2. Move the cursor over the stream line connecting the two icons. A check mark attached to the cursor appears, indicating an acceptable connection to break.


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Double-click on the outlet stream icon (1) to open its property view. Change the Name from the default to Hot Crude, then specify a temperature of 650°F.

The remaining degree of freedom in the Furnace has now been used, so HYSYS can flash Hot Crude and determine its remaining properties. Close the view to return to the PFD. The Furnace now has green status, and all attached streams are known.

Double-click on the energy stream icon (Q-100) to open its property view. The required heating duty calculated by HYSYS is displayed in the Heat Flow cell. Rename this stream Crude Duty, and close the property

Figure 4.77


view.


The MIXER is used to combine the hot crude stream with the vapours bypassing the furnace. The resulting stream is the feed for the crude column. To install and connect the mixer,

1. Make some empty space available to the right of the Furnace using the horizontal scroll bar.

2. Press the Mixer button on the Object Palette.

3. Position the cursor over the PFD (to the right of the Hot Crude stream icon).

4. Click to "drop" the mixer onto the PFD. HYSYS creates a new mixer with the default name MIX-100.

5. Press and hold the CTRL key to temporarily enable Attach mode while you make the mixer connections.

6. Position the cursor over the right end of the PreFlashVap stream icon. The connection point and pop-up "Out" appears.

7. With the pop-up visible, click and drag the cursor toward the left (inlet) side of the mixer, and multiple connection points appear at the mixer inlet.

8. Place the cursor near the inlet area of the mixer, and when the solid white box appears at the cursor tip, release the left mouse button to make the connection.

9. Repeat steps 6-8 to connect Hot Crude to the mixer.

10. Position the cursor over the right end of the mixer icon. The connection point and pop-up "Product" appears.

Figure 4.78

Mixer button

Multiple connection points appear because the MIXER accepts multiple feed streams.

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11. With the pop-up visible, click and drag to the right of the mixer. A large stream icon appears, with a trailing line attached to the mixer outlet.


13. Release the CTRL key to leave Attach mode.

Double-click on the outlet stream icon 1 to access its property view. When you created the mixer outlet stream, HYSYS automatically combined the two inlet streams and flashed the mixture to determine the outlet conditions, shown here. Rename the stream to TowerFeed, and close the view.

Finally, double-click on the mixer icon, MIX-100. Change the name from its default to Mixer. Now that the Mixer connections are complete,

Figure 4.79

Figure 4.80


make the PFD view more readable by first resizing its view by clicking and dragging the outside border. Then press the Zoom All button to fill the PFD window, including any objects that may not have been visible previously. The resized PFD is shown on the next page.

If you want to resize the furnace icon:

1. Click the Size Mode button on the PFD button bar.

2. Click on the Furnace icon in the PFD, and a box with sizing handles appears around the icon.

3. Place the cursor over one of the sizing handles, and the cursor changes to a double-ended sizing arrow.

4. With the sizing arrow visible, click and drag to the new icon size.

Zoom All button

Figure 4.81

Figure 4.82

Size Mode button

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5. Click the Size Mode button again to return to Move mode.

Prior to installing the column, an energy stream must be created to represent the trim duty on stage 28 of the main tower. To create the energy stream:

6. Double-click on the Energy Stream button on the Object Palette. HYSYS creates a new energy stream with the default name Q-100 and display its property view.

7. Change the Name from its default to Trim Duty.

8. Close this view.

Again, it is a good idea to save your case by doing one of the following:

• press CTRL S• from the File menu, select Save• click the Save button


HYSYS has a number of pre-built column templates that you can install and customize by changing attached stream names, number of stages and default specifications, and adding side equipment. One of these templates is going to be used for this example: a crude column with three side strippers. However, a basic REFLUXED ABSORBER column with a total condenser will be installed and customized in order to illustrate the installation of the necessary side equipment.

Before installing the column, select Preferences from the HYSYS Tools menu. On the Options page of the Simulation tab, check the Use Input Experts check box, and close the view.


1. Double-click on the Refluxed Absorber button on the Object

Energy Stream button

Save button

If you choose to use the pre-built crude column template, you still have to customize the column by modifying the various draw and return stages and default specifications. Although using the template eliminates the majority of the work over the next few pages, it is recommended to work through these pages for the first time you build a crude column in HYSYS. Once you are comfortable working with side equipment, then try using the template. Instructions on using the crude column template are given below.


Palette, and the first page of the Input Expert appears. When you

install a column using a pre-built template, HYSYS supplies certain default information, such as the number of stages. The current active cell is # Stages (Number of Stages), indicated by the thick border around this cell, and the presence of 10 (default number of stages) in the Edit Bar at the top of the view. Some points worth noting are:

• These are theoretical stages, as the HYSYS default stage efficiency is one.

• If present, the Condenser and Reboiler are considered separate from the other stages, and are not included in the # Stages field.

For this example, the main column will have 29 theoretical stages.

2. Enter 29 in the Numb of Stages cell.

3. Advance to the Bottom Stage Inlet cell by clicking on it or by pressing TAB.

4. Open the drop-down list of available feeds for this cell by clicking on next to the cell, or by pressing the i key.

5. Select Bottom Steam as the bottom feed for the column.

6. Advance to the Optional Inlet Streams list by clicking on the <<Stream>> cell, or by pressing TAB.

7. Open the drop-down list of available feeds by clicking on next to the Edit Bar, or by pressing the F2 key then the i key.

Figure 4.83

Refluxed Absorber button

The Input Expert is a Modal view, indicated by the thick border and absence of the Maximize/Minimize buttons. You cannot exit or move outside the Expert until you supply the necessary information, or click the Cancel button.

To install this column using the pre-built crude column template:

1. Double-click on the Custom Column button on the Object Palette.

2. On the view that appears, click the Read an Existing Column Template button. The Available Column Templates view appears, listing the template files *.col that are provided in your HYSYS\template directory. Both 3- and 4-side stripper crude column templates are provided.

3. Select 3sscrude.col and click the OK button. The property view for the new column appears. You can now customize the new column

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8. Select Tower Feed as the feed stream to the column. HYSYS supplies a default feed location in the middle of the Tray Section (TS), in this case stage 15 (indicated by 15_Main TS). However, it is required to feed this stream onto stage 28.

9. Click on the Inlet Stage cell for TowerFeed.

10. Type 28 and press ENTER, or select 28_Main TS from the drop-down list of stages in the Edit Bar.

11. Click on <<Stream>>, which was automatically advanced down one cell when you attached the feed stream.

12. Repeat steps 7 - 10 to attach the Trim Duty stream, which is also fed to stage 28.

In the Condenser group, notice that the default condenser type is Partial. To the right of this group, there are two Overhead Outlets, vapour and liquid. In this case, the overhead vapour stream has no flow, and two liquid phases (hydrocarbon and water) are present in the condenser. The hydrocarbon liquid product is attached in the liquid Overhead Outlets cell, while the water draw is attached using the Optional Side Draws matrix.

Figure 4.84

Figure 4.85


Although the overhead vapour product will have zero flow, do not change the condenser to Total. At this time, only the Partial radio button allows you to specify a three-phase condenser.

1. Advance to the top Ovhd Outlets cell by clicking on it or by pressing TAB twice.

2. Enter Off Gas as the name of the overhead vapour product stream, and HYSYS creates and attaches a new stream with this name.

3. Press TAB again to move to the bottom Ovhd Outlets cell, and enter the new stream name Naphtha.

The next task is to attach the water draw stream to the condenser.

1. Click on the cell labelled <<Stream>> in the Optional Side Draws matrix.

2. Enter the name of the draw stream, WasteH2O. HYSYS automatically places a hydrocarbon liquid (indicated by the L in the Type column) draw on stage 15. It is required to change this to a condenser water draw.

3. Click on the Type cell (the L) for the WasteH2O stream.

4. Specify a water draw by typing W then ENTER, or by selecting W from the drop-down list in the Edit Bar.

5. Click on the Draw Stage cell (15_Main TS) for the WasteH2O stream.

Figure 4.86

Overhead vapour product cell

Overhead liquid product cell

The water draw will be attached using this matrix

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6. Select Condenser from the drop-down list in the Edit Bar. The condenser will now be three-phase.

7. Enter the Column Name, and the Bottoms Liquid Outlet and Condenser Energy Stream names as shown below. The Next button now becomes available, indicating sufficient information has been supplied to advance to the next page of the Input Expert.

8. Click the Next button to advance to the Pressure Profile page.

Figure 4.87

Figure 4.88

All stream attachments made on this page result in the creation of Column Subflowsheet streams with the same names. For example, when the Main Flowsheet stream BottomSteam was attached as a feed, HYSYS automatically created an identical stream named BottomSteam to be used in the Column Subflowsheet.


9. Enter 19.7 psia, 9 psi and 32.7 psia as the Condenser Pressure, Condenser Pressure Drop and Bottom Stage Pressure, respectively.

10. Click the Next button to advance to the Optional Estimates page. Although HYSYS does not usually require estimates to produce a converged column, good estimates result in a faster solution.

11. Provide Condenser, Top Stage and Bottom Stage Temperature Estimates of 100°F, 250°F and 700°F, respectively.

Figure 4.89

Figure 4.90

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12. Click the Next button to advance to the fourth and final page of the Input Expert. This page allows you to supply values for the default column specifications that HYSYS has created.

In general, a refluxed absorber with a partial condenser has two degrees of freedom, for which HYSYS provides two default specifications. For the two specifications given, overhead Vapour Rate is used as an active specification, and Reflux Ratio as an estimate only.

13. All flow specifications are provided in barrels per day, so change the basis to Volume by selecting it in the Flow Basis drop-down list.

14. Enter a Vapour Rate of 0 and a Reflux Ratio of 1.0.

Figure 4.91


15. Click the Done button, and the Column property view appears.

Move to the Monitor page on the Design tab by clicking on it. The main feature of this page is that it displays the status of your column as it is being calculated, updating information with each iteration. You can also change specification values, and activate or de-activate specifications used by the Column solver, directly from this page.

Notice that the current Degrees of Freedom is one, indicating that only two specifications are Active. As noted earlier, a Refluxed Absorber with a partial condenser has two degrees of freedom and, therefore, requires two Active specifications. In this case, however, a third degree of freedom was created when the Trim Duty stream was attached as a feed, whose heat flow is unknown. HYSYS has not made a specification for the third degree of freedom, therefore you need to add a water draw spec called WasteH2O Rate to be the third Active specification.

1. Click on the Specs page to remove two specifications and add one new specification.

2. In the Column Specifications group, click on Reflux Rate to highlight it and then click the Delete button.

3. Delete the Btms Prod Rate specification also.

Figure 4.92

The basic column has three available degrees of freedom. Currently, three Specifications are Active, so the overall Degrees of Freedom is zero. The number of available degrees of freedom increases with the addition of side equipment.

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4. Now add the WasteH2O Rate specification by clicking on the Add button. The Add Specs view appears.

5. Click on Column Draw Rate and click on the Add Spec(s)... button. The Draw Spec property view appears.

6. Type the name as shown below. No further information is required as this specification will be de-activated and only estimated when you run the column.

7. Close the view. You now see the new specification in the Column Specifications group. Notice also that the degrees of freedom are now zero.

Figure 4.93

The Draw Spec is entered so that the Degrees of Freedom are kept at zero throughout this tutorial. It is good practice to keep the degrees of freedom at zero as you modify your column so that you may solve the column after every modification.


Before proceeding, move to the Connections page.

This page is similar to the first page of the Input Expert. Currently, the column is a standard type, so this page shows a column schematic with the names of the attached streams. When the side equipment is added to the column, it will become non-standard. There are a large number of possible non-standard columns based on the types and numbers of side operations that are added. Therefore, HYSYS modifies the Connections page to be organized in a tabular format, rather than a schematic format, whenever a column becomes non-standard. The side equipment that was added is illustrated on the Connections page to how it was modified.

The side equipment will be added now.

Figure 4.94

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Installing the Side Strippers

Move to the Side Ops tab of the Column property view.

On this tab, you can Install, View, Edit or Delete all types of Side Equipment. The matrix displays summary information for a given type of side operation, depending on the page you are currently on. To install and define the side strippers:

1. Ensure that you are on the Side Strippers page.

2. Click the Add button, and the Side Stripper view appears.

Figure 4.95

Figure 4.96

When you install side equipment, it resides in the Column Subflowsheet. You can build a complex column in the Subflowsheet while in the Main Flowsheet, the column appears as a single operation. You can then transfer any needed stream information from the Subflowsheet by simply attaching the stream to the Main Flowsheet.


3. Change the Name from its default to KeroSS.

This is a reboiled 3-stage stripper with a 0.75 boil up ratio, so leave the Configuration radio button at Reboiled, and the k = and Boil Up Ratio cells at their defaults.

4. Select stage 9 (9_Main TS) from the Draw Stage drop-down list.

5. Select stage 8 (8_Main TS) from the Return Stage drop-down list.

6. Pick the Volume radio button in the Flow Basis group.

7. Move to the Product Stream cell, and enter Kerosene.

Recall the straight run product distribution data calculated during the Oil Characterization, shown here. The Kerosene liquid volume fraction is 0.128. For 100,000 bbl/day of crude fed to the tower, Kerosene production can be expected at 100,000 * 0.128 = 12,800 or approximately 13,000 bbl/day.

Figure 4.97

Kerosene Liquid Volume Fraction

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8. Enter 13000 in the Product Rate cell. The completed Side Stripper view is shown below.

9. Click the Install button, and a view summarizing your input appears.

10. Click the Close button to return to the Column property view. Summary information for the new side operation appears in the matrix on the Side Ops tab.

11. Repeat steps 1 - 10 to install the two remaining side strippers DieselSS and AGOSS. Note that these are both Steam Stripped, so choose the appropriate Configuration radio button and create the Steam Feed and Product streams as shown. Remember the @COL1 suffix is added automatically. The completed DieselSS side

Figure 4.98

Figure 4.99

Close View button


stripper view is shown below.

The completed AGOSS side stripper view is shown below.

Figure 4.100

Figure 4.101

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The completed Side Stripper Summary matrix is shown here.

Return to the Monitor page of the Design tab. The Specifications matrix on this page has a vertical scroll bar, indicating that new specifications have been created below the default ones. You can examine the entire matrix by re-sizing the view. Click and drag the bottom border down until the scroll bar disappears, making the entire matrix visible.

The installation of the side strippers created four additional degrees of freedom, so HYSYS created a Prod Flow (product flow) specification for each side stripper, plus a BoilUp Ratio specification for the Kerosene side stripper. The new specifications were automatically made Active to exhaust the four degrees of freedom, returning the overall Degrees of Freedom to 0.

Figure 4.102

Figure 4.103

Although not a requirement, the names of the Steam Feed streams created for these side strippers are identical to the names of the utility steam streams that were created previously in the Main Flowsheet. The conditions of these Steam Feed streams, which reside in the Column Subflowsheet, are unknown at this point. The conditions of the Main Flowsheet streams are duplicated into these Subflowsheet streams when the stream attachments are performed.

The addition of the side strippers has created four more degrees of freedom above the basic column, resulting in a total of seven available degrees of freedom. Currently, seven Specifications are Active, so the overall Degrees of Freedom is zero.


Installing the Pump Arounds

Return again to the Side Ops tab and select the Pump Arounds page. The matrix is cleared and its title changes to Liquid Pump Around Summary. To install the pump arounds:

1. Click the Add button, and the initial Pump Around view appears.

2. Select stage 2 (2_Main TS) from the Draw Stage drop-down list.

3. Select stage 1 (1_Main TS) from the Return Stage drop-down list.

4. Click the Install button, and a more detailed Pump Around view appears.

Each cooled pump around circuit has two specifications associated with it. The default Pump Around Specifications are circulation rate and temperature drop (Dt) between the liquid draw and liquid return. For this example, the Dt specification will be changed to a Duty specification for the pump around cooler.

The pump around rate is 50,000 bbl/day.

5. Enter 5e4 in the blank cell under the PA_1_Rate(Pa) specification.

Figure 4.104

Figure 4.105

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6. Double-click in the blank space under the PA_1_Dt(Pa) specification, and the Spec view appears.

7. Change the Spec Type from Temperature Drop to Duty in the drop-down list.

8. Enter -55e6 in the Spec Value cell. Note that the negative sign convention indicates cooling.

9. Click the Close button to return to the Pump Around view.

The remainder of the information on this view is calculated by the Column solver.

10. Click the Close View button on the main Pumparound view to return to the Column property view.

Figure 4.106

Figure 4.107


11. Repeat steps 1 - 10 to install the two remaining pump arounds. Enter Rate specifications of 3e4 barrel/day and Duty specifications of -3.5e7 Btu/hr for both of these pump arounds. The completed Pump Around views and Liquid Pump Around Summary matricies are shown below.

Figure 4.108

Figure 4.109

Figure 4.110

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Return to the Monitor page, and re-size the property view again so the entire Specifications matrix is visible. Note that the addition of each pump around created two additional degrees of freedom. As with the side strippers, the specifications for the pump arounds have been added to the list and were automatically made Active.

Move to the Connections page of the column property view.

Figure 4.111

The addition of the pump arounds has created six more degrees of freedom, resulting in a total of 13 available degrees of freedom. Currently, 13 Specifications are Active, so the overall Degrees of Freedom is zero.

Figure 4.112


The Connections page of a standard refluxed absorber property view is essentially identical to the first page of the refluxed absorber Input Expert, with a column schematic showing the feed and product streams. However, side equipment have been added to the standard refluxed absorber, making the column non-standard. The Connections page has therefore been modified to show tabular summaries of the Column Flowsheet Topology (i.e. all equipment), Feed Streams and Product Streams.

The column has 40 Total Theoretical Stages:

• 29 in the main tray section• 1 condenser for the main column• 9 in the side strippers (3 side strippers with 3 stages each)• 1 reboiler for the Kerosene side stripper

This topology results in 4 Total Tray Sections—one for the main column and one for each of the three side strippers.

Completing the Column Connections

When the stream attachments were made on the initial page of the Input Expert, HYSYS automatically created Column Subflowsheet streams with the same names. For example, when Bottom Steam was attached as a column feed stream, HYSYS created an identical Subflowsheet stream named Bottom Steam. In the Feed Streams matrix on the Connections page, the Main Flowsheet stream is the External Stream, while the Subflowsheet stream is the Internal Stream.

If you scroll down the list of Feed Streams, notice that the two side stripper steam streams, DieselSteam and AGOSteam, are Internal and External, meaning that these streams are attached to the Main Flowsheet streams that were created earlier.

For the purposes of this tutorial, it is not required to export the pump

Figure 4.113

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around duty streams PA_1_Q, PA_2_Q and PA_3_Q to the Main Flowsheet, so their External Stream cells will remain <<empty>>.

Adding Column Specifications

Return to the Monitor page of the Column property view. Notice that the current Degrees of Freedom is zero, indicating the column is ready to be Run. However, it is required to replace two of the Active specifications, Waste H2O Rate and KeroSS BoilUp Ratio, with the following new ones:

• an Overflash specification for the feed stage (Tray Net Liquid Flow specification)

• a Kerosene side stripper reboiler duty specification

To add the Overflash specification:

1. On the Design tab, move to the Specs page.

Figure 4.114


2. In the Column Specifications area, click the Add button. The Column Specifications view appears.

3. Select Column Liquid Flow as the Column Specification Type.

4. Click the Add Spec(s)... button, and the Liq Flow Spec view appears.

5. Change the Name from its default to Overflash.

6. Move to the Stage cell, and choose 27_Main TS from the list of available stages displayed in the Edit Bar.

A typical range for the Overflash rate is 3-5% of the total feed to the column. In this case, the total feed rate is 100,000 barrels/day. For the Overflash specification 3.5%, or 3,500 barrels/day will be used.

Figure 4.115

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1. Enter 3500 in the Spec Value cell.

2. Close the view to return to the Column property view. The new specification appears in the list of Column Specifications on the Specs page.

To add the Duty specification:

1. Click the Add button again to add the second new specification.

2. Select Column Duty as the Column Specification Type, and click the Add Spec(s)... button. The Duty Spec view appears.

3. Change the Name from its default to Kero Reb Duty.

4. Move to the Energy Stream cell, then select KeroSS_Energy @COL1 from the drop-down list in the Edit Bar.

5. Enter 7.5e6 (Btu/hr) in the Spec Value cell.

Figure 4.116

Figure 4.117


6. Close the view to return to the Specs page of the Column property view. The completed list of Column Specifications is shown here.

Running the Column

Return to the Monitor page to view the Specifications matrix again. The Degrees of Freedom is again zero, so the column is ready to be calculated. However, a value for the distillate (Naphtha) rate specification must be supplied initially. In addition, it is required to use some specifications which are currently Active as Estimates only, and vice versa. To make the final changes to the specifications:

1. Enter 2e4 (bbl/day) in the Specified Value cell for the Distillate Rate specification.

2. Activate the Overflash specification by clicking its Active check box.

3. Activate the Kero Reb Duty specification.

4. De-activate the Reflux Ratio specification by clicking its checked Active check box.

5. Activate the Vapour Prod Rate specification.

6. De-activate the Waste H2O Rate specification.

7. De-activate the KeroSS BoilUp Ratio specification.

Click the Run button to begin calculations, and the information displayed on the page is updated with each iteration. The column should converge in approximately eight iterations (as shown in the Iter

Figure 4.118

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column of the matrix in the upper left corner of the view).

The converged temperature profile is currently displayed in the upper right corner of the view. To view the pressure or flow profiles, select the appropriate radio button. You can access a more detailed stage summary by moving to the Summary page on the Performance tab. In the Flow Basis group near the top of the view, pick the Std Liq Vol radio button to examine the tray vapour and liquid flows on a volumetric basis. The detailed stage summary is shown in Figure 4.120.

Figure 4.119

This matrix displays the Iteration number, Step size, Equilibrium error and Heat/Spec error.

The column temperature profile is shown here. You can view the pressure or flow profiles by picking the appropriate radio button.

The status indicator has changed from Unconverged to Converged.


Viewing Boiling Point Profiles for the Product Stream

You can view boiling point curves for all the product streams on a single graph:

1. On the Performance tab, click on the Results page (in the column

Figure 4.120

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4-94

property view).

2. In the Refinery Assay Curves group, click on Boiling Point Assay.

3. Click the View Graph button, and the Boiling Point Properties view appears.

No data is plotted on the graph, since there is currently No Tray Attached, as shown in the title bar.

Figure 4.121

Figure 4.122


4. Click the Profile Data Control button, and the Data Control view appears as shown in Figure 4.123.

Pick the Multi Tray radio button in the Style group. The Data Control view is modified, showing a matrix of column stages with a check box for each stage.

1. Activate the following stages by clicking on their blank check boxes:

• Condenser (Naphtha product stage)• 29_Main TS (Residue)• KeroSS_Reb (Kerosene)• 3_DieselSS (Diesel)• 3_AGOSS (AGO)

The TBP profile for the light liquid phase on each stage will be viewed, on a liquid volume basis.

2. Select TBP in the drop-down list under the tray matrix in the Style group.

3. In the Basis group, pick the Liquid Vol radio button.

4. Click on the blank Liq Light check box in the phase group to activate it.

Figure 4.123

You can view boiling point properties of a single tray or multiple trays. The boiling point properties of all stages, from which products are drawn, are important for this Tutorial.

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5. Leave the Visible Points at its default setting of 15 Points. You can display more data points for the curves by selecting the 31 Points radio button. The completed Data Control view is shown in Figure 4.124.

6. Click on the Close button in the upper right corner of the Data Control view to close it. You return to the Boiling Point Properties view, which nows display the TBP curves.

7. Make the Boiling Point Properties view more readable by clicking the Maximize button in the upper right corner of the view, or by clicking and dragging its border to a new view size.

Figure 4.124

The independent (x-axis) variable is the Assay Volume Percent, while the dependent (y-axis) variable is the TBP in °C.


8. Move the graph legend by double-clicking inside the plot area, then clicking and dragging the legend to its new location. The Boiling Point Properties view is shown below.

When you are finished viewing the profiles, click the Close button.


When considering the column, you might want to focus only on the column Subflowsheet. You can do this by entering the column environment. Click the Column Environment button at the bottom of the property view. While inside the column environment, you might want to:

• view the Column Subflowsheet PFD by clicking the PFD button• view a Workbook of the Column Subflowsheet objects by

clicking the Workbook button• access the "inside" column property view by clicking the

Column Runner button. This property view is essentially the same as the "outside", or Main Flowsheet, property view of the column.

Figure 4.125

PFD button

Workbook button

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The Column Subflowsheet PFD is shown below.

Customizing the Column PFD

You can customize the PFD shown above by re-sizing the column and "hiding" some of the column trays to improve the overall readability of the PFD. To hide some of the trays in the main column:

1. Click the PFD button to ensure the column PFD is active.

2. C lick the Maximize button in the upper right corner of the PFD view to make it full-screen.

3. Click the Zoom All button at the bottom left of the PFD view to fill the re-sized PFD window.

Figure 4.126

Maximize button

Zoom All button


4. Object inspect (right-click once) the main column tray section, and the object inspection menu appears.

5. Select Show Trays from the object inspection menu. The Stage Visibility view appears.

6. Select the Selected Expansion radio button.

7. Hide stages 4, 5, 6, 11, 12, 13, 14, 24, 25 and 26 by clearing their Shown check boxes.

8. Click the Close button on the Stage Visibility view to return to the PFD. The routing of some streams in the PFD may be undesirable. You can improve the stream routing by completing the next step.

Figure 4.127

Figure 4.128

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9. From the PFD menu item, select Auto Position, and HYSYS rearranges the PFD in a logical manner.

The next task in customizing the PFD is to enlarge the icon for the main column:

1. Click on the icon for the main tray section (Main TS).

2. Click the Size button on the PFD button bar, and a box with eight sizing handles appears around the tray section icon.

3. Place the cursor over the handle at the middle right of the icon, and the cursor changes to a double-ended sizing arrow.

4. With the sizing cursor visible, click and drag to the right. An outline appears, showing what the new icon size will be when you complete the next step.

5. When the outline indicates a new icon size of about 1.5 to 2 times the width of the original size, release the mouse button. The tray section icon is now re-sized.

6. Click the Size button again to return to Move mode.

The final task is to customize the PFD by moving some of the streams and operation labels (names) so they do not overlap. To move a label:

Figure 4.129

Size button


1. Click on the label you want to move.

2. Right-click and select Move/Size Label.

3. Move the label to its new position by clicking and dragging it, or by pressing the arrow keys.

You can also move the iconon its own simply by clicking and dragging it to the new location.

When you are finished working with the maximized Column PFD, click the Restore button for the PFD (not for the HYSYS Application Window) in the upper right corner of the view of the PFD. The PFD returns to its previous size. You can manually resize the view, and expand the PFD to fill the new size by again clicking the Zoom All button in the lower left corner of the PFD view.

For more information on customizing the PFD, refer to Chapter 3 - PFD in the HYSYS User’s Guide. The customized PFD is shown below.

To view the workbook for the column:

Figure 4.130

Restore button

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1. Click the Workbook button.

When you are finished working in the Column environment, return to the Main Flowsheet by clicking the Parent Simulation Environment button. Open the PFD for the Main Flowsheet, then select Auto Position All from the PFD menu item. HYSYS arranges the Main Flowsheet PFD in a logical manner according to the layout of the flowsheet. The PFD shown on the next page has been manually rearranged by moving some of the stream icons, and by enlarging the column icon.

Figure 4.131

Parent Simulation Environment button


Results

Open the Workbook to access the calculated results for the Main Flowsheet. The Material Streams tab of the Workbook is shown in Figure 4.133.

Figure 4.132

Figure 4.133

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Now that results have been obtained, you may want to view the calculated properties of a particular stream or operation. The Object Navigator allows you to quickly access the property view for any stream or unit operation at any time during the simulation. To open the Navigator, do one of the following:

• press F3• from the Flowsheet menu, select Find Object• double-click on any blank space on the HYSYS Desktop• click the Navigator button


The UnitOps radio button in the Filter group is currently picked, so only the Unit Operations appear in the list of objects. To open a property view, select the operation in the list, and click the View button, or double-click on the operation. You can change which objects are displayed by picking a different Filter radio button. For example, to list all streams and unit operations, click the All button.

You can also search for an object by clicking the Find button. When the Find Object view appears, enter the Object Name, and click the OK button. HYSYS opens the property view for the object whose name you entered.

Using a Boiling Point Curves Utility

Previously, the boiling point profiles for the product streams was viewed using the Plots page in the column property view. You can also view boiling point curves for a product stream using HYSYS’ BP Curves

Figure 4.134

Navigator button


Utility. To create a Boiling Point curves utility for the Kerosene product:

1. Open the Navigator using one of the methods described above.

2. Pick the Streams radio button.

3. Scroll down the list of Streams and select Kerosene.

4. Click the View button, and the property view for stream Kerosene appears.

5. On the Attachments tab, move to the Utilities page of the stream property view.

6. Click the Create button. The Available Utilities view appears, presenting you with a list of HYSYS utilities.

7. Scroll down the list until BP Curves is visible, then do one of the following:

• Select BP Curves, then click the Add Utility button• Double-click on BP Curves

8. HYSYS creates the utility and displays its BP Curves tab, which presents the Boiling Point data in tabular format.

9. Change the Name of the utility from the default Boiling Point Curves-1 to Kerosene BP Curves.

Figure 4.135

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10. Change the curve basis to Liquid Volume by selecting it in the Basis drop-down list.

Figure 4.136Note that a Utility is a separate entity from the stream it is attached to; if you Delete it, the stream will not be affected. Likewise, if you delete the stream, the Utility will remain but will not display any information until you attach another stream using the Select Object button.


You can scroll through the matrix of data to see that the TBP ranges from 267°F to 498°F by selecting the Parameters tab.

This boiling range predicted by the utility is slightly wider than the ideal range calculated during the Oil characterization procedure for Kerosene, 356°F to 464°F.

Select Plots from the Parameters tab of the utility property view to view the data in graphical format.

Figure 4.137

Figure 4.138

Ideal boiling range calculated during Oil Characterization.

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When you move to the Plots view, the graph legend may be overlapping the plotted data. The legend in the above plot has been moved to the middle of the plot. To move the legend, double-click anywhere in the plot area then click and drag the legend to its new location. When you are finished viewing the Boiling Point Curves, click the Close button.

Alternative to using the Utilities page of a stream property view, you can also install a utility using the Available Utilities view. Another BP Curves utility will be installed for stream Residue. This utility will be used for the case study in the next section. To install the utility:


• press CTRL U• from the Tools menu, select Utilities

Figure 4.139

To make the envelope more readable, maximize or resize the view.


The Available Utilities view appears.

2. Scroll down the list of available utilities until BP Curves is visible.

3. Select BP Curves, and click the Add Utility button. The Boiling Point Curves view appears, opened to the BP Curves tab.

Figure 4.140

Figure 4.141

Figure 4.142

Notice the name of the utility created previously, Kerosene BP Curves, appears in the Available Utilities view.

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4. Change the Name from its default Utility-1 to Residue BP Curves.

5. Change the Basis to Liquid Volume by selecting it in the drop-down list.

The next task is to attach the utility to a material stream.

1. Click the Select Object button, and the Select Process Stream view appears.

2. Select Residue in the Object list, then click the OK button. HYSYS calculates the boiling point curves. The completed BP Curves tab is shown below.

Figure 4.143

Figure 4.144

Notice that the stream name Residue now appears in the Stream cell.


3. Click the Close button on the Residue BP Curves view, and then on the Available Utilities view.

Using the Databook

The HYSYS Databook provides you with a convenient way to examine your flowsheet in more detail. You can use the Databook to monitor key variables under a variety of process scenarios, and view the results in a tabular or graphical format. To open the Databook, do one of the following:

• press CTRL D• from the Tools menu, select Databook

The Databook appears below.

The first step is to add the key variables to the Databook using the Variables tab. For this example, the Overflash specification is varied and examined to investigate its effect on the following variables:

• D1160 Boiling Temperature for 5% volume cut point of stream Residue

• heat flow of energy stream TrimDuty• column reflux ratio

To add the variables to the Databook:

Figure 4.145

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1. Click the Insert button, and the Variable Navigator view appears.

2. Select the UnitOps radio button in the Object Filter group. The Object list is filtered to show unit operations only.

3. Click on Atmos Tower in the Object list, and the Variable list available for the column appears to the right of the Object list.

4. Select Spec Calc Value in the Variable list, then Reflux Ratio in the Variable Specifics list.

HYSYS duplicates this variable name in the Variable Description cell. If you want, you can edit the default description. To edit the default description:

1. Click inside the Variable Description cell and delete the default

Figure 4.146

The Variable Navigator is used extensively in HYSYS for locating and selecting variables. The Navigator operates in a left-to-right manner—the selected Flowsheet determines the Object list, the chosen Object dictates the Variable list, and the selected Variable determines whether any Variable Specifics are available.


name.

2. Type a new description, such as Reflux Ratio, and click the OK button. The variable now appears in the Databook.

3. To add the next variable, click the Insert button, and the Variable Navigator again appears.

4. Pick the Streams radio button in the Object Filter group. The Object list is filtered to show streams only.

5. Scroll down and click on Trim Duty in the Object list, and the Variable list available for energy streams appears to the right of the Object list.

6. Select Heat Flow in the Variable list.

7. Change the Variable Description to Trim Duty, and click the OK button. The variable now appears in the Databook.

Figure 4.147

Figure 4.148

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8. Click the Insert button again to add the third variable, the ASTM D1160 cut point from the Residue BP Curves utility.

9. Select the Utility radio button in the Navigator Scope group.

10. Select Residue BP Curves in the Object list.

11. Select ASTM1160 - VAV in the Variable list.

12. Select the fifth item listed in the Variable Specifics column. This corresponds to the 5% volume cut point.

13. In the Variable Description cell, change the variable name to ASTM 1160 - Vac 5% Residue, and click the OK button.

14. The completed Variables tab of the Databook appears below.

Now that the key variables to the Databook have been added, the next

Figure 4.149

Figure 4.150


task is to create a data table to display those variables:

1. Move to the Process Data Tables tab by clicking on its tab.

2. Click the Add button in the Available Process Data Tables group. HYSYS creates a new table with the default name ProcData1.


Notice that the three variables added to the Databook appear in the matrix on this tab.

1. Activate each variable by clicking on the corresponding Show

Figure 4.151

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check box.


This table is accessed later to demonstrate how its results are updated whenever a flowsheet change is made. For now, click the Minimize button in the upper right corner of the Key Variables Data view. HYSYS reduces the view to an icon and place it at the bottom of the Desktop.


Figure 4.152

Figure 4.153


Move to the Data Recorder tab by clicking on it.


1. Click the Add button in the Available Scenarios group, and HYSYS creates a new scenario with the default name Scenario 1. It is required to include all three key variables in this scenario.


Figure 4.154

Figure 4.155

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4. Change the Name for New State from the default State 1 to 3500 O.F. (denoting 3500 bbl/day Overflash). Click the OK button, and you return to the Databook.

5. In the Available Display group, select the Table radio button.

6. Click the View button, and the Data Recorder appears, showing the values of the key variables in their current state.

Now you can make the necessary flowsheet changes and these current values remain as a permanent record in the Data Recorder unless you choose to erase them. Click the Minimize button to reduce the Data Recorder to an icon.

The value of the Overflash specification is going to be changed in the column and the changes will be viewed in the process data table:

Figure 4.156

Figure 4.157



2. Pick the UnitOps radio button in the Filter group.

3. Click on Atmos Tower, and click the View button. The Atmos Tower property view appears.

4. Ensure you are on the Design tab at the Monitor page of the column property view.

5. Scroll down to the bottom of the Specifications matrix so the Overflash specification is visible.

6. If the view is modal, click the Pin button in the upper right corner of the column property view to make the view non-modal. You now are able to access other items on the Desktop, such as the Key Variables data table, without having to close the column view.

A typical range for the Overflash rate is 3-5% of the tower feed. A slightly wider range will be examined: 1.5-7.5%, which translates to 1500-7500 bbl/d.

1. Change the Specified Value for the Overflash specification from its current value of 3500 barrel/day to 1500 barrel/day. HYSYS automatically recalculates the flowsheet.

2. Double-click on the Key Variables Data icon to restore the view to its full size. The updated key variables are shown below.

Figure 4.158

Figure 4.159

Navigator button

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As a result of the change:

• the Trim Duty has decreased• the Residue D1160 Vacuum Temperature 5% cut point has

decreased• the column reflux ratio has decreased

3. Press CTRL D to make the Databook active again. You can now record the key variables in their new state:



6. Change the name to 1500 O.F., and click the OK button to accept the new name.


Figure 4.160


8. Repeat steps 1 and 3 - 5 to record the process variables for Overflash rates of 5500 and 7500 barrels/day. Enter names for these variable states of 5500 O.F. and 7500 O.F., respectively. The final Data Recorder is shown below.

Figure 4.161

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Chemicals Tutorial 5-1

5 Chemicals Tutorial

In this Tutorial, a flowsheet for the production of propylene glycol is presented. Propylene oxide is combined with water to produce propylene glycol in a continuously-stirred-tank reactor (CSTR). The reactor outlet stream is then fed to a distillation tower, where essentially all the glycol is recovered in the tower bottoms. A flowsheet for this process is shown below.

The following pages will guide you through building a HYSYS case for modelling this process. This example will illustrate the complete construction of the simulation, from selecting a property package and components, defining the reaction, to installing streams and unit operations, through to examining the final results. The tools available in HYSYS interface will be utilized to illustrate the flexibility available to you.

Start HYSYS and create a new case. You will need to set your Session Preferences:

1. Open the Tools menu and select Preferences. The Session

The complete case for this tutorial has been pre-built and is located in the file TUTOR3.HSC in your HYSYS\SAMPLES directory.

Figure 5.1

Before proceeding, you should have read the Chapter 1 - HYSYS Tutorials which precedes the Tutorials in this manual.


1. Create a unit set.

2. Choose a property package.

3. Select the components.

4. Define the reaction.

5. Create and specify the feed streams.

6. Install and define the MIXER and REACTOR.

7. Install and define the DISTILLATION COLUMN.

5-1

5-2 Chemicals Tutorial

5-2

Preferences view appears.

2. You are now on the Simulation tab with the Options page open. Uncheck the Use Modal Property Views by clicking on the check box.

3. Click on the Variables tab and open the Units page.


The first step in building the simulation case is choosing a unit set. HYSYS does not allow you to change any of the three default unit sets listed. However, you can create a new unit set by cloning an existing one. For this example, a new unit set will be made based on the HYSYS Field set, and customized for the new set:

1. Click on Field in the Available Unit Set list to ensure it is the active set. Notice the default unit for Liq. Vol. Flow (liquid volume flow) is barrel/day; we will change the Liq. Vol. Flow unit’s to USGPM for this example.

2. Click the Clone Unit Set button. A new unit set named NewUser appears in the Available Unit Sets list, and is automatically highlighted, making it the current unit set. If you want, you can enter a new name in the Unit Set Name cell and can now change the units for any variable associated with this new unit set.

3. Move to the Liq. Vol. Flow cell by clicking on barrel/day.

Figure 5.2

The default Preference file is named HYSYS.prf. When you modify any of the preferences, you can save the changes in a new Preference file by clicking the Save Preference Set button. HYSYS prompts you to provide a name for the new Preference file, which you can later recall into any simulation case by clicking the Load Preference Set button.


4. Open the drop-down list of available units in the Edit Bar by clicking on or by pressing the F2 key then the i key.

5. Click on USGPM, or scroll down to it by pressing the i key then ENTER.

Your new unit set is now defined. Exit this screen to begin your simulation.

Figure 5.3

Figure 5.4

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5-4

The Simulation Basis Manager appears.

The next step is to create a Fluid Package. A Fluid Package, at minimum, contains the components and property method (for example, an Activity Model) to be used by HYSYS in its calculations for a particular flowsheet. Depending on what is required in a specific flowsheet, a Fluid Package may also contain other information, such as reactions and interaction parameters.

Notice that all commands accessed via the Button Bar are also available as menu items.

Figure 5.5

Notice that HYSYS displays the current Environment and Mode in the upper right corner of the view. Whenever you begin a new case, you are automatically placed in the Basis Environment, where you can define your property package and components.



Click the Add button, and the property view for your new Fluid Package appears.

The property view is divided into a number of tabs to allow you to supply all the information necessary to completely define the Fluid Package. For the purpose of this example, the four tabs: Prop Pkg (Property Package), Components, Binary Coeffs (Binary Coefficients), and Rxns (Reactions).

The choice of Property Package is made on the Prop Pkg tab. Notice the position of the highlight in the Base Property Package Selection area (currently located on <None>). There are a number of ways to select the desired base property package, in this case UNIQUAC. Do one of the following:

• Begin typing UNIQUAC, and HYSYS finds the match to your input.

• Use the arrow keys h and i to scroll through the list of available property packages until UNIQUAC is highlighted.

Figure 5.6



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• Use the vertical scroll bar to move down the list until UNIQUAC becomes visible, then click on it.

Notice the Property Pkg indicator at the bottom of the view, which now indicates UNIQUAC as the current property package for this Fluid Package. As an alternative, you could have picked the Activity Models radio button as the Property Pkg Filter, producing a list of only those property packages which are Activity Models. UNIQUAC could have then been chosen from this filtered list, as shown here.

You should normally leave the Component Selection Control at its default setting, Only Property Package Compatible Components. HYSYS then filters the library components to include only those appropriate for the selected Property Package.

Figure 5.7

Figure 5.8


Selecting Components

Now that you have chosen the property package to be used in the simulation, the next step is to select the components. Move to the Components tab in the Fluid Package property view by clicking on it, or by pressing CTRL SHIFT N.

There are a number of ways to select components for your simulation. One method is to use the matching feature. Notice that each component is listed in three ways, by its:

Atop each of these three columns is a corresponding radio button. Based on the selected radio button, HYSYS locates the component(s) that best match the input you type in the Match cell.

Figure 5.9

Feature Description

SimName The name appearing within the simulation

FullName/Synonym

IUPAC name (or similar), and synonyms for many components

Formula The chemical formula of the component. This is useful when you are unsure of the library name of a component, but know its formula.

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For this example, propylene oxide, propylene glycol and H2O are used as the components. To add Propylene Oxide to the component list:

1. Ensure the FullName/Synonym radio button is picked, and the Show Synonyms check box is checked.


3. Start typing propyleneoxide. HYSYS filter through the list as you type, displaying only those components that match your input.

4. Once PropyleneOxide is highlighted, add it to the Current Component List by doing one of the following:

• Press the ENTER key.• Click the Add Pure button.• Double-click on PropyleneOxide.

The component now appears in the Current Component List.

Figure 5.10

Figure 5.11


In addition to the Match criteria radio buttons, you can also use the Family Filter to display only those components belonging to certain families. To add Propylene Glycol to the component list:

1. Ensure the Match cell is empty by pressing ALT M and then the DELETE key.

2. Click on the Use Filter check box, then click the Family Filter button, and the Families view appears.

3. Since Propylene Glycol is an alcohol, click on the Alcohols check box.


5. Begin typing propyleneglycol. HYSYS filters as you type, displaying only the alcohols that match your input.

6. When Propylene Glycol is highlighted, press the ENTER key to add it to the component list.

Finally, to add the component H2O:

1. Clear the Alcohols check box by clicking on it.

2. H2O does not fit into any of the standard families, so click on the Miscellaneous check box.

Figure 5.12

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3. Scroll down the filtered list until H2O is visible, then double-click on H2O to add it to the Current Component List.

The final component list is shown below.


To view the properties of one or more components, highlight the component(s) and click the View Comp button. HYSYS opens the property view(s) for the component(s) you select. For example:

1. Click on 12C3diol in the Current Component List.


3. Click on H2O. These two components should now be highlighted.


Figure 5.13

Figure 5.14A component can be removed from the Current Components List by selecting it, and clicking the Remove Comps button or the DELETE key.


5. Click the View Comp button. The property views for these two components appear.

The Component property view provides you with complete access to the pure component information for viewing only. You cannot modify any parameters for a library component; however, HYSYS has an option for cloning a library component into a Hypothetical component, which can then be modified as desired. See Chapter 2 - Hypotheticals in the Simulation Basis guide for more information on cloning library components. Click the Close button on each of these two component views to return to the Fluid Package.

The next step in defining the Fluid Package is providing the binary interaction parameters.

Figure 5.15

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Providing Binary Coefficients

To examine the binary interaction coefficients, move to the Binary Coeffs tab on the Fluid Package view by clicking on it.

In the Activity Model Interaction Parameters group, the Aij interaction matrix is displayed by default. HYSYS automatically inserts the coefficients for any component pairs that library data is available. You can change any of the values provided by HYSYS if you have data of your own.

In this case, the only unknown coefficients in the matrix are for the 12C3Oxide/12-C3diol pair. You have the option of entering these values if you have available data. However, for this example, one of HYSYS’ built-in estimation methods will be used. In this case, the UNIFAC VLE estimation method will be used to estimate the unknown pair:

1. Ensure the UNIFAC VLE radio button is picked.

2. Click the Unknowns Only button, and HYSYS provides values for the unknown pair. The final Activity Model Interaction Parameters matrix for the Aij coefficients is shown below.

Figure 5.16

Figure 5.17


To view the Bij coefficient matrix, pick the Bij radio button. For this example, all the Bij coefficients will be left at the default value of zero.

Defining the Reaction

Return to the Simulation Basis Manager by clicking on its title bar, or by clicking the Basis button. Move to the Reactions tab, which provides a convenient location where you can define all the reactions for the flowsheet.

The reaction between water and propylene oxide to produce propylene glycol is as follows:

Selecting the Reaction Components

The first step in defining the reaction is choosing the components that will be participating in the reaction. In this Tutorial, all the components which were selected in the Fluid Package are also participating in the reaction, so the easiest way to add the reaction components is to simply add all of the Fluid Package components.

1. Click the Add Comps button in the Rxn Components group, and the Reaction Components Selection view appears.

Figure 5.18

Basis button

H2O + C3H6O � C3H8O2 (8.1)

These steps will be followed in defining our reaction:

1. Select the components participating in the Reaction.

2. Create and define a Kinetic Reaction.

3. Create a Reaction Set containing the reaction.

4. Activate the Reaction set to make it available for use in the flowsheet.

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2. Ensure the FPkg Pool (Fluid Package Pool) radio button in the Add Comps group is selected. This radio button allows you to utilize the components previously selected in the Fluid Package. The Components Associated with the Fluid Packages group should be visible on the right side of the view.

For the Fluid Package that is highlighted in the list of Available Fluid Pkgs, the components contained in that Fluid Package appear in the Associated Components list. Since there is only one Fluid Package, Basis-1, the three components that were added to this Fluid Package appear in the list of Associated Components.

3. Click the Add This Group of Components button, and all of the components listed as the Associated Components are duplicated in the list of Selected Reaction Components.

Figure 5.19

Figure 5.20

You can remove a component from the Selected Reaction Component list by selecting it, and pressing the DELETE key.


4. Return to the Simulation Basis Manager by exiting from this view.

The three components are now listed in the Rxn Components group on the Reactions tab of the Simulation Basis Manager.

Creating the Reaction

Now that the reaction components have been chosen, the next task is to create the reaction:

1. In the Reactions group, click the Add Rxn button. This opens the Reactions view.

Figure 5.21

Figure 5.22

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2. Select the Kinetic reaction type, and click the Add Reaction button. The Kinetic Reaction property view appears, opened to the Stoichiometry tab.

On the Stoichiometry tab, you specify which of the Rxn Components are involved in the particular reaction, as well as the stoichiometry and the reaction order.

3. Click on the cell labelled **Add Comp** in the Component column.

4. Select Water as a reaction component by doing one of the following:

• Open the drop-down list in the Edit Bar, and choose H2O from the list of available reaction components.

• Type H2O and HYSYS filters as you type, highlighting the component which matches your input. When H2O is highlighted, press the ENTER key to add it to the Component list.

Repeat steps 3 and 4 to add 12C3Oxide and 12-C3diol to the component list.

The next step is to enter the stoichiometric information. A negative stoichiometric coefficient indicates that the component is consumed in the reaction, while a positive coefficient indicates the component is produced.

5. Click on the cell in the Stoich Coeff column corresponding to H2O.

6. Type -1 and press the ENTER key.

Figure 5.23

Often you will have more than one reaction occurring in your simulation case. On the Stoichiometry tab of each reaction, you select only the Rxn Components participating in that reaction.


7. Repeat steps 5 - 6 to enter the coefficients for the remaining components, as shown here in the Kinetic Reaction view:

Once the stoichiometric coefficients are supplied, the Balance Error will be zero, indicating that the reaction is mass balanced. HYSYS will also calculate and display the heat of reaction in the Reaction Heat cell. In this case, the Reaction Heat is negative, indicating that the reaction produces heat (exothermic).

HYSYS provides default values for the Forward Order and Reverse Order based on the reaction stoichiometry. The kinetic data for this Tutorial is based on an excess of water, so the kinetics are first order in Propylene Oxide only.

1. Change the Forward Order of H2O to 0 to reflect the excess of water.

The Stoichiometry tab is now completely defined and appears below.

Figure 5.24

Figure 5.25

Notice that the default values for the Forward Order and Reverse Order appear in red, indicating that they are suggested by HYSYS. When you enter the new value for H2O, it will be blue, indicating that you have specified it.

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The next step is to define the reaction basis. Advance to the Basis tab by clicking on it. To complete this tab:

1. Leave the Basis at its default value of Molar Concn.

2. Click on the Base Component cell. By default, HYSYS has chosen the first component listed on the Stoichiometry tab, in this case H2O, as the base component. The base component will be changed to Propylene Oxide.


• Open the drop-down list of components in the Edit Bar by clicking on it, and choose 12C3Oxide.

• Begin typing 12C3Oxide, and HYSYS filters as you type. When 12C3Oxide is highlighted, press the ENTER key.

4. Select CombinedLiquid for the Rxn Phase using the drop-down list in the Edit Bar. The completed Basis tab is shown below.

The Min. Temperature, Max. Temperature, Basis Units and Rate Units are acceptable at their default values.

To complete the reaction, advance to the Parameters tab in the Kinetic Reaction property view. On this tab you provide the Arrhenius parameters for the kinetic reaction. In this case, there is no Reverse Reaction occurring, so you only need to supply the Forward Reaction parameters:

1. Enter 1.7e13 for the pre-exponential factor A.

2. Enter 3.24e4 (Btu/lbmole) for the activation energy E.

Figure 5.26

You can have the same reaction occurring in different phases with different kinetics and have both calculated in the same REACTOR.


The status indicator at the bottom of the Kinetic Reaction property view changes from Not Ready to Ready, indicating that the reaction is completely defined. The final Parameters tab is shown in Figure 5.27.

Leave the Kinetic Reaction property view by clicking the Close button. Also, you must close the Reactions view that was used to define the reaction as a Kinetic reaction.

Click the Basis button to ensure the Simulation Basis Manager is active. On the Reactions tab, the new reaction, Rxn-1, now appears in the Reactions group.

Figure 5.27

Figure 5.28

Basis button

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The next task is to create a reaction set that will contain the new reaction. Notice in the Reaction Sets list, HYSYS provides the Global Rxn Set (Global Reaction Set) which contains all of the reactions you have defined. In this Tutorial, since there is only one REACTOR, the default Global Rxn Set could simply be attached to it. However, for illustration purposes, a new reaction set will be created.

Creating a Reaction Set

Reaction Sets provide a convenient way of grouping related reactions. For example, consider a flowsheet in which a total of five reactions are taking place. However, in one REACTOR operation, suppose only three of the reactions are occurring (one main reaction and two side reactions). You can group the three reactions into a Reaction Set, then simply attach the set to the appropriate REACTOR unit operation.

To add the Reaction Set:

1. Click the Add Set button in the Reaction Sets group, and the Reaction Set property view appears. HYSYS has given the set the default name Set-1.

Figure 5.29

Note that the same reaction(s) can be in multiple Reaction Sets.


2. Click on the cell labelled <empty> in the Active List.

3. Open the drop-down list in the Edit Bar, which contains all reactions in the Global Reaction Set. Currently, Rxn-1 is the only reaction defined, so it is the only available choice.

4. Add Rxn-1 to the Active List by selecting it in the drop-down list. A check box labelled OK automatically appears next to the reaction in the Active List. The reaction set status changes from Not Ready to Ready, showing that the new reaction set is complete.

Figure 5.30

Figure 5.31

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5. Click the Close button to return to the Simulation Basis Manager. The new reaction set named Set-1 now appears in the Reaction Sets group.

Making the Reaction Set Available to the Fluid Package

The final step is to make the set available to the Fluid Package, which also makes it available in the flowsheet. To add the reaction set to our Fluid Package:

1. Click on Set-1 in the Reaction Sets group on the Reactions tab.

2. Click the Add to FP button, and the Add ’Set-1’ view appears.

This view prompts you to select the Fluid Package that you would like to add the reaction set. In this example, there is only one Fluid Package, Basis-1.

Figure 5.32

Figure 5.33


3. Click on Basis-1, and click the Add Set to Fluid Package button.

Move to the Fluid Pkgs tab that displays a summary of the completed Fluid Package.

Notice that the list of Current Fluid Packages displays the new Fluid Package, Basis-1, showing the number of components (NC) and property package (PP). The new Fluid Package is assigned by default to the Main Simulation, as shown in the Flowsheet-Fluid Pkg Associations area. Now that the Basis is defined, you can install streams and operations in the Simulation Environment (also known as the Parent Simulation Environment or Main Simulation Environment).

Figure 5.34

Figure 5.35

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To enter this environment and leave the Basis environment, do one of the following:

• Click the Enter Simulation Environment button on the Simulation Basis Manager.

• Click the Enter Simulation Environment button in the button bar.

Simulation Environment

When you enter the Simulation Environment, the initial view that appears is dependent on your current preference setting for the Initial Build Home View. Three initial views are available, namely the PFD, Workbook and Summary. Any or all of these can be displayed at any time; however, when you first enter the Simulation Environment, only one is displayed. For this example, the initial Home View is the Workbook (HYSYS default setting).

Figure 5.36


You will notice several things about the Main Simulation Environment. In the upper right corner, the Environment has changed from Basis to Case (Main). A number of new items are now available on the Menu and Button Bar, and the Workbook and Object Palette are open on the Desktop. These two latter objects are described below.

Before proceeding any further to install streams or unit operations, it is probably a good idea to save your case.


• Click the Save button on the button bar.• From the File menu, select Save.• Press CTRL S.

As this is the first time you have saved your case, the Save Simulation Case As dialog box appears.

By default, the File Path is the Cases sub-directory in your HYSYS directory.


Workbook

A multiple-tab view containing information regarding the objects (streams and unit operations) in the simulation case. By default, the Workbook has four tabs, namely Material Streams, Compositions, Energy Streams and Unit Ops. You can edit the Workbook by adding or deleting tabs, and changing the information displayed on any tab.


You can toggle the palette open or closed by pressing F4, or by choosing Open/Close Object Palette from the Flowsheet menu

Figure 5.37

Save button

Open Case button

When you choose to open an existing case by clicking the Open Case button, or by selecting Open Case from the File menu, a view similar to the one shown here appears. The File Filter drop-down list then allows you to retrieve backup (*.bk*) and HYSIM (*.sim) files in addition to standard HYSYS (*.hsc) files.

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2. In the File Name cell type a name for the case, for example GLYCOL. You do not have to enter the .hsc extension; HYSYS automatically adds it for you.

3. Once you have entered a file name, press the ENTER key or the OK button. HYSYS will now save the case under the name you have given it when you Save in the future. The Save As dialog box will not appear again unless you choose to give it a new name using the Save As command.

Before any streams or operations are installed, the simulated process will be summarized.

Process Description

The process being modelled in this example is the conversion of propylene oxide and water to propylene glycol in a CSTR REACTOR. The reaction products are then separated in a distillation tower. A flowsheet for this process is shown below.

The propylene oxide and water feed streams are combined in a MIXER. The combined stream is fed to a REACTOR, operating at atmospheric pressure, in which propylene glycol is produced. The REACTOR product stream is fed to a distillation tower, where essentially all the glycol is recovered in the bottoms product.

The two primary building tools, Workbook and PFD, are used to install the streams and operations, and to examine the results while progressing through the simulation. Both of these tools provide you with a large amount of flexibility in building your simulation, and in quickly accessing the information you need.


Figure 5.38

The Workbook displays information about streams and unit operations in a tabular format, while the PFD is a graphical representation of the flowsheet.


The Workbook is used to build the first part of the flowsheet, including the feed streams and the mixer. The PFD is then used to install the reactor, and a special sequence of views called the Input Expert to install the distillation column.

Using the Workbook

Click the Workbook button on the button bar to make the Workbook active.

Installing the Feed Streams

In general, the first step when you enter the Simulation environment is to install one or more feed streams. To create a new stream:

1. Type the new stream name Prop Oxide in the cell labelled **New** on the Material Streams tab of the Workbook. Note that HYSYS accepts blank spaces within a stream or operation name.

Press ENTER, and HYSYS automatically creates the new stream with the name you have given it.

The next step is to define the feed conditions, in this case 75°F and 1.1 atm. Notice that when you pressed ENTER after typing in the stream name, HYSYS automatically advanced the active cell down one cell, to Vapour Fraction.

2. Move to the Temperature cell for Prop Oxide by clicking on it, or by pressing the i key.

Figure 5.39

Workbook button

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3. Type 75 in the Temperature cell, and notice your input appears in the Edit Bar at the top of the view. In the Unit Box, HYSYS displays the default units for temperature, in this case F.

4. Since this is the correct unit, press ENTER or the Accept button (the green check beside the Edit bar), and HYSYS accepts the temperature.

Your location should now be the Pressure cell for Prop Oxide. Suppose you know the stream pressure in another unit besides the default of psia, and you do not have quick access to the conversion factor. HYSYS will accept your input in any one of a number of different units, and automatically convert to the default for you. For example, the pressure of Prop Oxide is 1.1 atm. To enter this pressure:

1. Type 1.1.

2. Press the SPACEBAR or click on . HYSYS now matches your input to locate the unit of your choice. Begin typing atm. The drop-down list of units opens and you can scroll down to the unit(s) most closely matching your input.

3. Once atm is highlighted, press the ENTER key or the Accept button, and HYSYS accepts the pressure. Notice that it automatically converts to the default unit, psia.

Alternatively to steps 2 and 3, you could have specified the unit simply by selecting it in the unit box drop-down list.

Figure 5.40

Figure 5.41


The Molar Flow cell for Prop Oxide should now be your active Workbook location. The next step is to enter the stream flow rate, 150 lbmole/hr. Since the default Molar Flow unit for our unit set is lbmole/hr., simply type 150 and press ENTER.


Now that the stream conditions have been specified, the next step is to input the composition:

1. Double-click on the Molar Flow cell of the Prop Oxide stream to open the Input Composition for Stream view, allowing you to complete the compositional input.


Figure 5.42

The Input Composition for Stream view is Modal, indicated by the thick border and the absence of the Minimize/Maximize buttons in the upper right corner. When a Modal view is visible, you will not be able to move outside the view until you finish with it, by clicking either the Cancel or OK button.


Compositional Basis Radio Buttons


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2. Move to the input cell for the first component, 12C3Oxide. This stream is 100% propylene oxide.

3. Type 1 for the mole fraction, and press ENTER.

In this case, 12C3Oxide is the only component in the stream.

Normalizing

The Normalizing feature is useful when you know the relative ratios of components; for example, 2 parts N2, 2 parts CO2, 120 parts C1, etc. Rather than manually converting these ratios to fractions summing to one, simply enter the individual numbers of parts and click the Normalize button. HYSYS computes the individual fractions totalling 1.0.

Normalizing is also useful when you have a stream consisting of only a few components. Instead of specifying zero fractions (or flows) for the other components, simply enter the fractions (or the actual flows) for the non-zero components, leaving the others <empty>. Then click the Normalize button, and HYSYS forces the other component fractions to zero.


As you input the composition, the component fractions (or flows) initially appear in red, indicating the final composition is unknown. These values become blue when the stream composition is calculated. Three scenarios result in the stream composition being calculated:

• Input the fractions of all components, including any zero components, such that their total is exactly 1.0000. Click the OK button.

• Input the fractions (totalling 1.000), flows or relative number of parts of all non-zero components. Click the Normalize button and the OK button.

• Input the flows or relative number of parts of all components, including any zero components, and click the OK button.


Note that these are the default colours; yours may appear differently depending on your settings on the Colours page of the Session Preferences.


4. Click the Normalize button to force the other values to zero. The composition is now defined.

5. Click the OK button, and HYSYS accepts the composition. The stream specification is now complete so HYSYS will flash it at the conditions given to determine the remaining properties.

Notice that the values you specified are a different colour (blue) than the calculated values (black).

Alternatively to installing streams via the Workbook, there are a number of ways to create a new stream with a default name. To add the second feed stream, do any one of the following:

Figure 5.43

Figure 5.44

If you wish to delete a stream, move to the Name cell for the stream, then press DELETE. HYSYS asks for confirmation of your action.

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• Press F11.• From the Flowsheet menu, select Add Stream.• Double-click the Material Stream button on the Object Palette.• Click the Material Stream button on the Object Palette, then


A new stream appears and is named according to the Auto Naming setting in your Preferences. The default setting names new material streams with numbers, starting at 1 (and energy streams starting at Q-100).

Conditions is the active page when the stream is initially accessed. To define this second feed stream:

1. Replace the default stream name with Water Feed.

2. Type 75 and 16.17 in the Temperature and Pressure cells, respectively. Note that these parameters are in default units, so there is no need to supply the units.

Figure 5.45

Add Object button

Material Stream button


3. Move to the Composition page to begin the compositional input for the new feed stream.

4. Click the Edit button near the bottom of the Composition page, and the Input Composition for Stream view appears. Note that the current Composition Basis setting, you want to enter the stream composition on a mass flow basis.

5. Change the Composition Basis to Mass Flows by picking the appropriate radio button, or by pressing ALT A.

6. Click on the compositional cell for H2O.

Figure 5.46

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7. Type 11000 (lb/hr), and press ENTER.

8. Since this stream has no other components, click the Normalize button. The other component mass flows are forced to zero.

9. Click the OK button to close the view and return to the stream property view.

HYSYS performs a flash calculation to determine the unknown properties of Water Feed, as shown by the status indicator displaying OK. You can view the compositions of each phase using the horizontal scroll bar in the matrix on the property view. For example, to view the aqueous phase compositions for Water Feed, scroll to the right by clicking the right scroll arrow, or by clicking and dragging the scroll button.

Figure 5.47


Note that the compositions are currently displayed in Mass Flow. You can change this by clicking the Basis button and choosing another Composition Basis radio button.

To view the calculated stream properties, click on the Conditions page. You can display the properties of all phases by resizing the property view:

1. Place the cursor over the right border of the view. The cursor changes to a double-ended sizing arrow.

2. With the sizing arrow visible, click and drag to the right until the horizontal scroll bar disappears, leaving the entire matrix visible.

Figure 5.48

Sizing Arrow button

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In this case, the aqueous phase is identical to the overall phase. Click the Close button on the Water Feed property view to return to the Workbook.


Now that the feed streams are known, the next step is to install the necessary unit operations for producing the glycol.


The first operation is a MIXER, used to combine the two feed streams. As with most commands in HYSYS, installing an operation can be accomplished in a number of ways. One method is through the Unit Ops tab of the Workbook. To install the MIXER:

1. Click the Workbook button to ensure the Workbook is active.


3. Click the Add UnitOp button. The UnitOps view appears, listing all available unit operations. When you click the Add button or press ENTER inside this view, HYSYS adds the operation that is currently highlighted.

Figure 5.49

New or updated information is automatically and instantly transferred among all locations in HYSYS.

Workbook button


4. Highlight Mixer by doing one of the following:

• Start typing mixer.• Press i to scroll down the list of available operations to Mixer.• Scroll down the list using the vertical scroll bar, and click on

Mixer.

5. With Mixer highlighted, click the Add button, or press ENTER.

Alternatively, you could have produced a filtered list by picking the Piping Equipment radio button in the Categories group, then using one of the above methods to install the operation. Double-clicking on a listed operation can also be used instead of the Add button or the ENTER key.

The property view for the MIXER is shown here. As with a stream, a unit operation property view contains all the information defining the operation, organized into different pages on tabs. The four tabs shown for the MIXER, namely Design, Rating, Work Sheet and Dynamics, are contained in the property view for most operations. Property views for more complex operations contain more tabs. Notice that HYSYS has provided the default name MIX-100 for the MIXER. As with streams, the default naming scheme for unit operations can be changed in your Session Preferences.

Figure 5.50

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Many operations, like the MIXER, accept multiple feed streams. Whenever you see a matrix like the one for Inlets, the operation will accept multiple stream connections at that location. When the Inlets matrix is active, you can access a drop-down list of available streams in the Edit Bar.


1. Click on the <<Stream>> cell to ensure the Inlets matrix is active. The status indicator at the bottom of the view is showing that the operation needs a feed stream.

Figure 5.51


2. Open the Edit Bar drop-down list of inlets by clicking on or by pressing the F2 key then the i key.

3. Select Prop Oxide from the list. The stream is transferred to the list of Inlets, and <<Stream>> automatically moves down to a new empty cell.

4. Repeat steps 2 and 3 to connect the Water Feed stream. Alternatively, you could have made the connections by typing the exact stream name in the cell, followed by ENTER. The status indicator now displays Requires a product stream.

5. Move to the Outlet cell by pressing TAB, or by clicking in it.

6. Type Mixer Out in the cell, and press ENTER. Since an outlet stream has not been created, HYSYS recognizes that there is no existing stream with this name, so it creates the new stream with the name you have supplied.

Figure 5.52

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With the Connections page complete, move to the Parameters page. Leave the Automatic Pressure Assignment at its default setting of Set Outlet to Lowest Inlet. HYSYS has calculated the outlet stream by combining the two inlets and flashing the mixture at the lowest pressure of the inlet streams. In this case, both inlets have the same pressure (16.17 psia), so the outlet stream is set to 16.17 psia.

Figure 5.53

Figure 5.54


To view the calculated outlet stream, move to the Worksheet tab in the MIX-100 property view. This tab is a condensed Workbook tab displaying only those streams attached to the operation.

Now that the MIXER is completely solved, click the Close button to return to the Workbook. The new operation is displayed in the matrix on the Unit Ops tab of the Workbook.

The matrix shows the operation Name, its Object Type, the attached streams (Feeds and Products), whether it is Ignored, and its Calc. Level. When you click the View UnitOp button, the property view for the operation occupying the current row in the matrix is opened. Alternatively, by double-clicking on any cell (except Feeds and Products) associated with the operation, you will also open its property view.

Figure 5.55

Figure 5.56

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You can also open the property view for a stream directly from the Workbook Unit Ops tab. When any of the cells Name, Object Type, Ignored or Calc. Level are active, the box at the bottom of the view displays all streams attached to the current operation. Currently, the Name cell for MIX-100 has focus, and the box displays the three streams attached to this operation. To open the property view for one of the streams attached to the MIXER, for example Prop Oxide, do one of the following:

• Double-click on Prop Oxide in the box at the bottom of the view.

• Double-click on the Inlets cell for MIX-100. The property view for the first listed feed stream, in this case Prop Oxide, is opened.

Workbook Features

Before installing the remaining operations, a number of features of the Workbook are illustrated that allow you to access information quickly and change how information is displayed.



When your current location is a Workbook streams tab, such as any one of the Material Streams, Compositions and Energy Streams tabs, the box at the bottom of the Workbook view displays the operations that the current stream is attached. For example, click on any cell associated with the stream Prop Oxide. The box displays the name of the mixer operation, MIX-100.

If stream Prop Oxide was also attached to another unit operation, both unit operations would be listed in the box. To access the property view for the MIXER, double-click on its name in the box.

Any utilities attached to the stream with focus in the Workbook are also displayed in (and are accessible through) this box.


Adding a Tab to the Workbook

Notice that when the Workbook is active, the Workbook item appears in the HYSYS menu. This item allows you to customize the Workbook according to the information you would like to be displayed.

Suppose you want to create a new Workbook tab that displays only stream pressure, temperature, and flow. To add a new tab:


• From the Workbook menu item, select Setup.• Object inspect (right-click) the Material Streams tab in the

Workbook, then select Setup from the menu that appears.The Workbook Setup view appears.

Figure 5.57

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Notice that the four existing tabs are listed in the Workbook Tabs area. When you add a new tab, it is inserted before the highlighted tab (currently Material Streams). Add the new tab before the Compositions tab.

2. Click on the Compositions tab in the list of Workbook tabs. Click the Add button. The New Object Type view appears.

3. Select Material Stream and click the OK button. You return to the Setup view, and the new tab added after the existing Material Streams tab.

Figure 5.58

Figure 5.59


4. Click on the Name cell in the Object group, and change the name for the new tab from the default Material Streams 2 to P,T,Flow in order to better describe the tab contents.

The next task is to customize the tab by removing the variables that are irrelevant:



3. Click on the other variables, Mass Flow, Heat Flow and Molar Enthalpy. These three variables are now highlighted.


5. Click the Delete button to remove them from this Workbook tab only. If you want to remove variables from another tab, you must edit each tab individually. The finished Setup is shown on the following figure.

Figure 5.60

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Click the Close button to return to the Workbook and view the new tab.

At this point, it is a good idea to save your case by doing one of the following:

• Click the Save button on the button bar.• From the File menu, select Save.• Press CTRL S.

Figure 5.61

Figure 5.62

Save button


Using the PFD

Besides the Workbook, the PFD is the other main view in HYSYS. To open the PFD, click the PFD button on the button bar. The PFD item appears in the HYSYS menu whenever the PFD has focus.

When you open the PFD view, it appears similar to the one shown below.

As a graphical representation of your flowsheet, the PFD shows the connections among all streams and operations, also known as "objects". Each object is represented by a symbol, also known as an "icon". A stream icon is an arrow pointing in the direction of flow, while an operation icon is a graphic representing the actual physical operation. The object name, also known as a "label", appears near each icon.

The PFD shown above has been rearranged by moving the Prop Oxide feed stream icon up slightly so it does not overlap the other Water Feed icon. To move an icon, simply click and drag it to the new location. Note that you can click and drag either the icon (arrow) itself, or the label (stream name), as these two items are grouped together.

Figure 5.63

PFD button

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• Access commands and features through the PFD Button Bar.• Open the property view for an object by double-clicking on its

icon.• Move an object by clicking and dragging it to the new location.• Access "fly-by" summary information for an object simply by

placing the cursor over it.• Size an object by clicking the Size button, selecting the object,

then clicking and dragging the sizing "handles" that appear.• Display the Object Inspection menu for an object by placing the

cursor over it, and right-clicking. This menu provides access to a number of commands associated with the particular object.

• Zoom in and out, or display the entire flowsheet in the PFD window by clicking the zoom buttons at the bottom left of the PFD view.

Some of these functions will be illustrated here; for further information, see Chapter 3 - PFD in the User’s Guide.

Calculation Status


Fly-by information

Size button

Zoom Out 25%

Display Entire PFD

Zoom In 25%

Indicator Status

Description

Red Status


Yellow Status


Green Status The stream or operation is completely defined and solved. The status indicator is green, and an OK message is displayed.



When you are in the PFD, the streams and operations are "colour-coded" to indicate their calculation status. The MIXER is completely calculated, so its normal colours are displayed. However, if the conditions of an attached stream were not entirely known, the MIXER would have a yellow outline indicating its current status.


Installing the Reactor

For this example, a continuously-stirred-tank reactor operation (CSTR) will be used. You can install streams or operations by dropping them from the Object Palette onto the PFD. Make sure the Object Palette is displayed; if it is not, press F4. The CSTR is added to the right of the MIXER, so if you need to make some empty space available, scroll to the right using the horizontal scroll bar. To install and connect the CSTR:

1. Click the CSTR Reactor button.

2. Position the cursor over the PFD, to the right of the Mixer. The cursor changes to a special cursor with a plus (+) symbol attached to it. The symbol indicates the location of the operation icon.

Notice that the icons for all streams installed to this point are dark blue.

CSTR button

Cancel button

Figure 5.64

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5-50

3. Click to "drop" the REACTOR onto the PFD. HYSYS creates a new REACTOR with a default name, CSTR-100. Notice that the REACTOR has red status (colour), indicating that it requires feed and product streams.

4. Click the Attach Mode button on the PFD toolbar to enter Attach mode. The Attach Mode button has a different shading to show that it is activated.

5. Position the cursor over the right end of the Mixer Out stream icon. A small transparent box appears at the cursor tip. Through the transparent box, you can see a square connection point, and a pop-up description is attached to the cursor tail. The pop-up "Out" indicates which part of the stream is available for connection, in this case the stream outlet.

6. With the pop-up "Out" visible, click and hold the mouse button. The transparent box becomes solid black, indicating that you are beginning a connection.

7. Move the cursor toward the left (inlet) side of the REACTOR. A trailing line appears between the Mixer Out stream icon and the cursor, and multiple connection points appear at the REACTOR inlet.

8. Place the cursor near the connection point. The trailing line snaps to that point, as well, a solid white box appears at the cursor tip, indicating an acceptable end point for the connection.

9. Release the mouse button, and the connection is made to the connection point at the REACTOR inlet.

10. Position the cursor over the REACTOR icon. Move the cursor over the connection point at top right hand corner to display the pop-up "Vapour Product".

Figure 5.65

Figure 5.66

Attach button

When you are in Attach mode, you will not be able to move objects in the PFD. To return to Move mode, click the Attach button again. You can temporarily toggle between Attach and Move mode by holding down the CTRL key.

Multiple connection points appear because the REACTOR accepts multiple feed streams.



12. Move the cursor to the right of the REACTOR. A large stream icon appears, with a trailing line attached to the REACTOR outlet. The stream icon indicates that a new stream is created when you complete the next step.


14. Repeat steps 10 to 13 to create the REACTOR liquid product. Originate the connection from the bottom right connection point labelled "Liquid Product". The new stream is given the default name 2.

15. Repeat steps 10 to 13 to create the REACTOR energy stream. Originate the connection from the bottom left connection point labelled "Energy Stream" on the REACTOR icon, and drag below and to the left of the REACTOR. The new stream is automatically named Q-100, and the REACTOR recieves a yellow warning status. This status indicates that all necessary connections have been made, but that the attached streams are not entirely known.

16. Click the Attach Mode button again to return to Move mode. The Attach Mode button will return to its normal appearance.

17. Double-click on the steam icon 1 to open its property view.

18. Enter the new name Reactor Vent in the Name cell, and click the Close button.

19. Repeat steps 17 and 18 for stream 2, renaming it Reactor Prods.

Figure 5.67

Figure 5.68

Break Connection button


1. Click the Break Connection button on the PFD button bar.

2. Move the cursor over the stream line connecting the two icons. A check mark attached to the cursor appears, indicating an available connection to break.


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20. Repeat steps 17 and 18 for energy stream Q-100, renaming it Coolant.

The REACTOR outlet and energy streams are unknown at this point, so they are light blue and light red, respectively. Double-click on the REACTOR icon to open its property view. On the Connections page, notice that the names of the Inlet, Outlet and Energy streams that were attached before appear in the appropriate cells. Change the operation Name from the default to Reactor.

To complete the Reactor specifications:

1. Move to the Parameters page. For now, Delta P and the Volume parameters are acceptable at the default values.

Figure 5.69


2. Select the Cooling radio button. This reaction is exothermic (produces heat), so cooling is needed.

3. Move to the Reactions tab and attach the Reaction Set that was created in the Basis Environment.

Figure 5.70

Figure 5.71

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Open the Reaction Set drop-down list and select Set-1. The completed Reactions tab is shown below.

The next task is to specify the Vessel Parameters. In this Tutorial, the reactor has a volume of 280 ft3 and is 85% full.

4. On the Specs page of the Dynamics tab, enter the Vessel Volume of 280 and Liquid Volume Percent of 85. HYSYS automatically calculates the Liquid Volume in the vessel (280 ft3 x 85% full = 238 ft3), displayed on the Parameters page.

Figure 5.72


Move to the Worksheet tab in the Reactor property view.

At this point, the Reactor product streams, as well as the energy stream Coolant, are unknown. This is because the REACTOR has one degree of freedom. At this point, either the outlet stream temperature or the cooling duty can be specified. For this example, the outlet temperature will be specified.

Initially the Reactor is assumed to be operating at isothermal conditions, therefore the outlet temperature is equivalent to the feed temperature, 75°F.

1. Click on the Temperature cell for Reactor Prods. Type 75 and press ENTER. HYSYS solves the Reactor.

Figure 5.73

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5-56

There is no phase change in the Reactor under isothermal conditions, since the flow of the vapour product stream Reactor Vent is zero. In addition, the required cooling duty has been calculated and is represented by the Heat Flow of stream Coolant.

The next step is to examine the Reactor conversion as a function of temperature.

Figure 5.74


2. Return to the Reactions tab and select the Results page of the property view, where the conversion is shown in the Reactor Results Summary matrix.

Under the current conditions, the Actual Percent Conversion (Act. % Cnv.) in the Reactor is 40.3%. The REACTOR temperature is adjusted until the conversion is in the 85-95% range.

3. Return to the Worksheet tab in the Reactor property view.

4. Change the Temperature of Reactor Prods to 100°F.

5. Return to the Reactions tab again to check the conversion, which has increased to 72.3% as shown below.

6. Return again to the Worksheet tab, and change the Temperature of Reactor Prods to 140°F.

Figure 5.75

Figure 5.76

5-57


5-58

7. Move back to the Reactions tab again and check the conversion.

The conversion at 140°F is approximately 95%, which is acceptable.

8. Click the Close button to close the Reactor property view.


HYSYS has a number of pre-built column templates that you can install and customize by changing attached stream names, number of stages and default specifications. For this example, a DISTILLATION COLUMN will be installed. Before installing the column, select Preferences from the Tools menu. On the Simulation tab, click on the Options page and ensure that the Use Input Experts check box is selected (checked), and close the view.


1. Double-click on the Distillation Column button on the Object Palette, and the first page of the Input Expert appears.

Figure 5.77

Figure 5.78

Distillation Column button


2. When you install a column using a pre-built template, HYSYS supplies certain default information, such as the number of stages. The current active cell is Numb of Stages with 10 (default number of stages) in the Edit Bar at the top of the view. Some points worth noting are:

• These are theoretical stages, as the HYSYS default stage efficiency is one.

• The Condenser and Reboiler are considered separate from the other stages, and are not included in the Num of Stages field.

For this example, 10 theoretical stages are used, so leave the Numb of Stages at its default value.

3. Advance to the Inlet Streams list by clicking on the <<Stream>> cell, or by pressing TAB.

4. Open the drop-down list of available inlet streams in the Edit Bar by clicking it, or by pressing the F2 key then the i key.

5. Select Reactor Prods as the feed stream to the column. HYSYS supplies a default feed location in the middle of the Tray Section (TS), in this case stage 5 (indicated by 5_Main TS).

6. In the Condenser group, ensure the Partial radio button is selected, as the column will have both Vapour and Liquid Overhead Outlets.

7. Enter the stream and Column names as shown below. When you are finished, the Next button becomes active, indicating sufficient information has been supplied to advance to the next page of the Input Expert.

Figure 5.79

The Input Expert is a logical sequence of input views that guide you through the initial installation of a Column. Completion of the steps will ensure that you have provided the minimum amount of information required to define the column.

The Input Expert is a Modal view, indicated by the thick border and absence of the Maximize/Minimize buttons. You cannot exit or move outside the Expert until you supply the necessary information, or click the Cancel button.

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5-60

8. Click the Next button to advance to page 2, the Pressure Profile page.

9. Enter 15 psia and 17 psia as the Condenser Pressure and Reboiler Pressure. The Condenser Pressure Drop can be left at its default value of zero.

10. Click the Next button to advance to the Optional Estimates page. Although HYSYS does not require estimates to produce a converged column, you should provide estimates for columns that are difficult to converge. For this example, no estimates are provided.

11. Click the Next button to advance to the fourth and final page of the Input Expert. This page allows you to supply values for the default column specifications that HYSYS has created.

In general, a DISTILLATION COLUMN has three default specifications. The overhead Vapour Rate and Reflux Ratio will be used as active specifications, and later you will create a glycol purity specification to exhaust the third degree of freedom. The third default specification, overhead Liquid Rate, will not be used.

Figure 5.80


12. Enter a Vapour Rate of 0 lbmole/hr. and a Reflux Ratio of 1.0. Note that the Flow Basis applies to the Vapour Rate, so leave it at the default of Molar.

13. Click the Done button, and the DISTILLATION COLUMN property view will appear.

Figure 5.81

Figure 5.82

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5-62

Click on the Monitor page of the Column property view. The main feature of this page is that it displays the status of your column as it is being calculated, updating information with each iteration. You can also change specification values, and activate or de-activate specifications used by the Column solver, directly from this page.

Adding a Column Specification

Notice that the current Degrees of Freedom is zero, indicating the column is ready to be Run. However, the Distillate Rate (Overhead Liquid Rate for which no value was provided in the Input Expert) is currently an Active specification, and has a Specified Value of <empty>. Since it is not desired to use this specification, click the Active check box for the Distillate Rate to clear it. The Degrees of Freedom increase to 1, indicating that another active specification is required. For this example, a water mole fraction of 0.005 is specified in the glycol product stream. To add the new specification:

1. Click on the Specs page.

2. Click the Add button in the Column Specifications area. The Column Specifications view appears.

Figure 5.83


3. Select Column Component Fraction as the Specification Type.

4. Click the Add Spec(s)... button, and the Comp Frac Spec view appears.

5. Change the specification Name to H2O Fraction by editing the default name.

6. Move to the Stage cell, and choose Reboiler from the list of available stages displayed in the Edit Bar.

7. Move to the Spec Value cell, and enter .005 as the liquid mole fraction specification value.

Figure 5.84

Figure 5.85

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5-64

8. Move to the first cell in the Components list, indicated by <<Component>>, and select H2O from the drop-down list of available components in the Edit Bar.

9. Click the Close button to return to the Column property view.

The new specification appears in the list of Column Specifications on the Specs page. Return to the Monitor page, where the new specification may not be visible (unless you scroll down the matrix) because it has been placed at the bottom of the Specifications list. For convenience, click the Group Active button to bring the new specification to the top of the list, directly under the other Active specifications. Scroll to the top of the list to view all active specifications. If you want to view the entire Specifications matrix, re-size the property view by clicking and dragging its border.

Figure 5.86


The Degrees of Freedom has returned to zero, so the column is ready to be calculated.

Running the Column

1. Click the Run button to begin calculations, and the information displayed on the page is updated with each iteration. The column converges quickly, in five iterations.

Figure 5.87

Note that HYSYS automatically made the new specification Active when you created it.

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The converged temperature profile is currently displayed in the upper right corner of the view. To view the pressure or flow profiles, choose the appropriate radio button. You can access a more detailed stage summary by moving to the Summary page on the Performance tab.

Figure 5.88



When considering the column, you might want to focus only on the column Subflowsheet. You can do this by entering the column environment. Click the Column Environment button at the bottom of the property view. While inside the column environment, you might wish to:

• View the column Subflowsheet PFD by clicking the PFD button.• View a Workbook of the column Subflowsheet objects by

clicking the Workbook button.• Access the "inside" column property view by clicking the

Column Runner button. This property view is essentially the same as the "outside", or Main Flowsheet, property view of the column.

The column Subflowsheet PFD and Workbook are shown below and on the next page.

Figure 5.89

PFD button

Column Runner button

Workbook button

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5-68

Figure 5.90

Figure 5.91


When you are finished in the column environment, return to the Main Flowsheet by clicking the Enter Parent Simulation Environment button. Open the PFD for the Main Flowsheet and select Auto Position All from the PFD menu. HYSYS arranges your PFD in a logical manner according to the layout of your flowsheet.

The PFD shown below has been customized by moving some of the stream icons. To move an icon, simply click and drag it to the new location.

You can also move a stream or operation label (name):

1. Click on the label you want to move.

2. Press the L key, and a box appears around the label.

3. Move the label to its new position by clicking and dragging it, or by pressing the arrow keys.

Figure 5.92

Enter Parent Simulation Environment button

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Results

Click the Workbook button to access the calculated results for the Main Flowsheet. The Material Streams and Compositions tabs of the Workbook are shown below.

Figure 5.93

Figure 5.94



Now that results have been obtained, you may want to view the calculated properties of a particular stream or operation. The Object Navigator allows you to quickly access the property view for any stream or unit operation at any time during the simulation. To open the Navigator, do one of the following:

• Press F3.• From the Flowsheet menu, select Find Object.• Double-click on any blank space on the HYSYS Desktop.• Click the Navigator button.


The UnitOps radio button in the Filter group is currently selected, so only the Unit Operations appear in the list of objects. To open a property view, select the operation in the list, and click the View button, or double-click on the operation. You can change which objects are displayed by selecting a different Filter radio button. For example, to list all streams and unit operations, select the All button.

You can also search for an object by clicking the Find button. When the Find Object view appears, enter the Object Name, and click the OK button. HYSYS opens the property view for the object whose name you entered.

Figure 5.95

Navigator button

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Using the Databook

The HYSYS Databook provides you with a convenient way to examine your flowsheet in more detail. You can use the Databook to monitor key variables under a variety of process scenarios, and view the results in a tabular or graphical format.

Before opening the Databook, close the Object Navigator or any property view you might have opened using the Navigator. To open the Databook, do one of the following:

• Press CTRL D.• From the Tools menu, select Databook.

The Databook view appears:

The first step is to add the key variables to the Databook using the Variables tab. For this example, the effects of the Reactor temperature on the Reactor cooling duty and Glycol production rate will be examined. To add the variables to the Databook:

1. Click the Insert button, and the Variable Navigator appears.

2. Pick the UnitOps radio button in the Object Filter group. The Object list is filtered to show unit operations only.

3. Click on Reactor in the Object list, and the Variable list available for the Reactor appears to the right of the Object list.

Figure 5.96


4. Select Vessel Temperature in the Variable list. HYSYS duplicates this variable name in the Variable Description cell. You can edit the default variable description.

5. Click in the Variable Description cell to make it active.

6. Type a new description, such as Reactor Temp, and click the OK button. The variable now appears in the Databook.

7. To add the next variable, click the Insert button, and the Variable Navigator again appears.

8. Select the Streams radio button in the Object Filter group. The Object list is filtered to show streams only.

9. Click on Coolant in the Object list, and the Variable list available for energy streams appears to the right of the Object list.

Figure 5.97

Figure 5.98

The Variable Navigator is used extensively in HYSYS for locating and selecting variables. The Navigator operates in a left-to-right manner—the selected Flowsheet determines the Object list, the chosen Object dictates the Variable list, and the selected Variable determines whether any Variable Specifics are available.

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10. Select Heat Flow in the Variable list.

11. Change the Variable Description to Cooling Duty, and click the OK button. The variable now appears in the Databook.

12. Repeat steps 7 - 11 to add the Liquid Volume Flow variable for stream Glycol to the Databook. Change the Variable Description for this variable to Glycol Production. The completed Variables tab of the Databook appears below.

Now that the key variables have been added to the Databook, the next step is to create a data table to display those variables:

Figure 5.99

Figure 5.100


1. Move to the Process Data Tables tab by clicking on it.

2. In the Process Data Tables group, click the Add button. HYSYS creates a new table with the default name ProcData1.


Notice that the three variables that were added to the Databook appear in the matrix on this tab.

4. Activate each variable by clicking on the corresponding Show check box.

Figure 5.101

Figure 5.102

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5-76


This table will be accessed again later to demonstrate how its results are updated whenever a flowsheet change is made. For now, click the Minimize button in the upper right corner of the Key Variables Data view. HYSYS reduces the view to an icon and places it at the bottom of the Desktop.


1. Move to the Data Recorder tab in the Databook by clicking on it. This page appears below.

Figure 5.103

Figure 5.104

To edit any of the Objects in the Databook:

1. Select the Object you want to edit.

2. Click the Edit button.



1. Click the Add button in the Available Scenarios group, and HYSYS creates a new scenario with the default name Scenario 1. Include all three key variables in this scenario.



4. Change the Name for New State from the default State 1 to Base Case, and click OK. You return to the Databook.

5. In the Available Display group, select the Table radio button.

Figure 5.105

Figure 5.106

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6. Click the View button, and the Data Recorder appears, showing the values of the key variables in their current state.

Now you can make the necessary flowsheet changes and these current values remain as a permanent record in the Data Recorder unless you choose to erase them. Click the Minimize button to reduce the Data Recorder to an icon.

Double-click on the Key Variables Data icon to restore the view to its full size. The temperature of stream Reactor Prods (which determines the Reactor temperature) will be changed and the changes can be viewed in the process data table:


2. Select the Streams radio button in the Filter group.

3. Click on Reactor Prods, and click the View button.

Figure 5.107

Figure 5.108

Navigator button


The Reactor Prods property view appears.

1. Ensure you are on the Conditions page of the property view.

2. Arrange the two views as shown below by clicking and dragging on their title bars.

Currently, the Reactor temperature is 140°F. The key variables will be checked at 180°F.

Figure 5.109

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3. Enter 180 in the Temperature cell for Reactor Prods, and HYSYS automatically recalculates the flowsheet. The new results are shown below.

As a result of the change, the required cooling duty decreased and the glycol production rate increased. Click the Close button on the Reactor Prods stream property view to return to the Databook. You can now record the key variables in their new state:



3. Change the name to 180 F Reactor, and click the OK button to accept the new name.

Figure 5.110



Click the Close button on the Data Recorder, then on the Databook, and finally on the Process Data Table.

This completes the HYSYS Chemicals tutorial. If there are any aspects of this case that you would like to explore further, feel free to continue working on this simulation on your own.

Further Study

For other chemical case examples, see the Applications binder. Applications beginning with “C” explore some of the types of chemical simulations that can be built using HYSYS.

Figure 5.111

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Dynamic Gas Processing Tutorial 6-1

6 Dynamic Gas Processing Tutorial

In this tutorial, the dynamic capabilities of HYSYS.Plant will be incorporated into a basic steady state gas plant model. The plant takes two different natural gas streams containing carbon dioxide and methane through n-butane, combines and processes them in a simple refrigeration system. A series of separators and coolers removes the heavier hydrocarbon components from the natural gas stream, allowing it to meet a pipeline dew point specification. The heavier liquid component of the gas stream is processed in a depropanizer column, yielding a liquid product with a specified propane content.

The Dynamics Assistant will be used to make pressure-flow specifications and size pieces of equipment in the simulation flowsheet. Note that this is only one method of preparing a steady state case for Dynamic mode. It is also possible to set your own pressure-flow specifications and size the equipment without the aid of the Dynamics Assistant.

The steady-state gas plant simulation used as a starting point for this dynamics tutorial is identical to the one built by the Steady State Gas Processing Tutorial in Chapter 3 - Gas Processing Tutorial of this guide.

A completed version of the steady-state starting point for this tutorial is located in the file TUTOR1.hsc, in the

Figure 6.1

6-1

6-2 Dynamic Gas Processing Tutorial

6-2

This tutorial will comprehensively guide you through the steps required to add dynamic functionality to a steady-state gas plant simulation. To help navigate these detailed procedures, the following milestones have been established for this tutorial:

1. Modify the steady-state model so that a pressure-flow relation exists between each unit operation.

2. Implement a tray sizing utility for sizing the Depropanizer column.

3. Use the Dynamics Assistant to set pressure flow specifications and size the equipment in the simulation case.

4. Install and define the appropriate controllers.

5. Set up the Databook. Make changes to key variables in the process and observe the dynamic behaviour of the model.

Modifying the Steady State Flowsheet

It is necessary to add unit operations, such as valves, heat exchangers, or pumps, which define pressure flow relations between unit operations that have no pressure flow relation. In this tutorial, valve operations will be added between Separators, Mixer and Column operations.

A Heater operation will also be added between the Mixer and Column operation for dynamic simulation purposes. Installing a heater allows you to vary the temperature of the feed entering the column.

Valves will be added to the following material streams:

• SepLiq• LTSLiq• TowerFeed• LiquidProd

1. Open the pre-built case file TUTOR1.hsc. The steady state Gas Processing simulation file TUTOR1.hsc is located in your HYSYS\SAMPLES directory.

2. Select Preference from the Tools menu to opens the Session Preference view.

A completed dynamic case has been pre-built and is located in the file DynTUT1.hsc in the HYSYS\SAMPLES directory.

In this Tutorial, you will follow this basic procedure in building the dynamic model.

Before proceeding, it is suggested that you complete Chapter 2 - Dynamic Fundamentals Tutorial to gain a firm understanding of dynamic simulation methods.

In this tutorial, you will be working with Field units. The units may be changed using the Session Preferences property view. To open the view select Tools on the menu bar and then Preferences. On the Units page of the Variables tab, specify Field in the Current Unit Set group box.


3. Move to the Assistant page on the Simulation tab and uncheck both the Perform checks when switching to dynamics or starting the integrator and the Set dynamic stream specifications in the background options.

4. Close the Session Preference view along with all the open views on the HYSYS desktop (except for the PFD view) by clicking the Close button in the top right hand corner of each view.

In the PFD, the stream pressure for Feed 2 will be deleted so that it will be calculated by the MIX - 100 in dynamic mode.

5. Open the feed 2 property view by double clicking on the stream icon.

6. On the Conditions page of the Worksheet tab remove the stream pressure.


The pressure setting for the MIX - 100 will be changed so that the whole pfd can be simulated.

8. Open the MIX - 100 property view.

9. On the Parameters page of the Design tab click on the Equalize All radio button in the Automatic Pressure Assignment group.

10. Close the mixer property view.

Figure 6.2

Close Button

6-3


6-4

A Valve operation will be inserted between the SepLiq stream and the MIX-101 unit operation.

11. Click the Break Connection button in the PFD button bar.

12. Position the mouse pointer over the SepLiq stream (to the right of the stream arrow). When the mouse pointer has a check mark beside it, click the primary mouse button and the stream will disconnect from the MIX-101.

13. Open the Object Palette by pressing F4.

14. Click on the Valve button on the Object Palette with the secondary mouse button and then position the bull’s-eye pointer beside the SepLiq stream.

15. Click the mouse button to place the VALVE onto the PFD. An icon for the VALVE will appear where the bull’s-eye pointer was.

16. Double click on the VALVE icon on the PFD to open its property view and specify the following connections:

Break Connection Button

Valve Button



Name Sep Valve

Inlet SepLiq

Outlet SepExit

Design [Parameters] Delta P 25 psi

Figure 6.3


17. Close the VALVE property view by clicking the Close button in the top right hand corner of the view.

18. Connect the SepExit stream to the inlet of the MIX-101 unit operation by clicking on the PFD Attach Mode button and then positioning the mouse pointer at the tip of the SepExit stream arrow.

19. Press and drag the pointer to the MIX-101 and HYSYS will automatically connect the stream to the unit operation. Release the mouse button to complete the connection.

20. Click the Attach Mode button again to exit from the attaching mode.

Next, a Valve operation will be inserted between the LTSLiq stream and the MIX-101 unit operation.

21. Break the line between the LTSLiq stream and the MIX-101 unit operation.

22. Install a second VALVE operation. Position this valve beside the LTSLiq stream.

23. Open the second VALVE property view and specify the following connections:

Figure 6.4

Attach Mode Button



Name LTS Valve

Inlet LTSLiq

Outlet LTSExit


6-5


6-6

24. Close the VALVE property view.

25. Using the Attach Mode button, connect the LTSExit stream to the inlet of the MIX-101 unit operation.

Next, add a Valve operation between MIX-101 unit operation and the TowerFeed stream.

26. Using the Break Connection button, break the line between the TowerFeed stream and the MIX-101 unit operation. Be sure to break the line to the left of the TowerFeed stream arrow.

27. Install a third VALVE operation with the following connections:

28. Close the VALVE view.

29. Using the Attach Mode button, connect the TowerIn stream to the exit of the MIX-101 unit operation.

30. Install a HEATER operation and position it near the Tower Valve and the DePropanizer.

31. Open the HEATER property view and specify the following connections:



Name Tower Valve

Inlet TowerIn

Outlet TowerInlet




Name Heater

Inlet TowerInlet

Outlet TowerFeed

Energy Heater Q


Note that you can use the scroll bars to navigate around the PFD. You can also use the PAGE UP and PAGE DOWN keys to zoom in and out of the PFD, respectively.


Figure 6.5

Figure 6.6

6-7


6-8

32. Open the Worksheet tab of the HEATER property view. The Conditions page should be open. Specify the temperature of the TowerFeed stream to be 24.73°F.

33. Close the HEATER property view.

When considering pieces of equipment associated with the column, it may be necessary to enter the Column Sub-Flowsheet environment. Since a valve is to be added to the LiquidProd stream, you must enter the Column Sub-Flowsheet.

Figure 6.7


34. Open the DePropanizer column property view by double clicking on the DePropanizer icon.

35. Click the Column Environment button to enter the Column Sub-Flowsheet environment.

Next, a Valve operation will be inserted between the LiquidProd stream and the Reboiler unit operation.

36. In the PFD of the Column Sub-Flowsheet, break the connection between the LiquidProd stream and the Reboiler unit operation.

37. Press F4 to open the Object Palette.

38. Install a VALVE operation in the same way as in the Parent Environment. Specify the following connections:

39. Close the VALVE property view.

40. Using the Attach Mode button, connect the LiquidExit stream to the liquid exit of the Reboiler unit operation.

Figure 6.8

Notice that the Object Palette in the Column Environment has fewer available unit operations than the Object Palette in the Parent Environment.



Name Reboil Valve

Inlet LiquidExit

Outlet LiquidProd


6-9


6-10

41. Click the Run Column Solver button in the button bar. The column will solve with the existing column specifications and the added valve unit operation.

It is necessary to delete unit operations that have no impact on the Dynamic solver. The MOLE BALANCE and ADJUST unit operations have no impact on the Dynamic solver.

42. Return to the Main Flowsheet environment by clicking the Enter Parent Simulation Environment button in the button bar.

The ADJ-1 and Dewpoint logical operations have calculated the Cold Gas stream temperature required to achieve a 10 °F dewpoint in the SalesGas stream.

43. Close the DePropanizer column property view.

Figure 6.9Run Column Solver Button



44. Open the ColdGas stream property view by double clicking on the ColdGas stream in the PFD.

45. Record the temperature of the ColdGas material stream so that it may be controlled in Dynamic mode:

46. Close the Cold Gas property view.

47. Delete the ADJ-1 logical operation by selecting the icon in the PFD and pressing the DELETE key.

48. Delete the Dewpoint logical operation and the SalesDP material stream from the flowsheet.

49. Save the case as DynTUT1-1.hsc. Open the File menu and select Save As. Type in the file name as DynTUT1-1.hsc and click the Save button.

Figure 6.10

Variable Value

Cold Gas Stream Temperature 4.43 F

When you delete a stream, unit or logical operation from the flowsheet, HYSYS will ask you for confirmation of the deletion. If you want to delete the object, click on the Yes button. If not, click the No button.

6-11


6-12

Column Sizing

In preparation for Dynamic operation, the column and surrounding equipment must be sized. The steady state column pressure drop is user-specified. In dynamics, it is calculated using dynamic hydraulic calculations. Complications will arise in the transition from steady state to dynamics if the steady state pressure profile across the column is very different from that calculated by the dynamics pressure-flow solver.

Column Tray Sizing

50. Open the Utilities property view by pressing CTRL U. The Available Utilities view will appear.

51. Scroll down the list of available utilities until the Tray Sizing utility is visible.

Figure 6.11


52. Select Tray Sizing, then click the Add Utility button. The Tray Sizing view will appear.

53. Highlight the default name in the Name field and type in Deprop TS as the new name.

54. Click the Select TS button. The Select Tray Section view appears.

55. Select the Main TS Object in the DePropanizer flowsheet. Press OK.

Figure 6.12

Figure 6.13

6-13


6-14

56. Click the AutoSection button in the Tray Sizing view, the AutoSection view appears. The default tray internal types are displayed as follows:

57. Keep the default values by clicking Next. The next view displays the specific dimensions of the valve-type trays. Keep the default values and press the Complete AutoSection button.

Figure 6.14

Figure 6.15


HYSYS calculates the Main TS tray sizing parameters based on the steady state flow conditions of the column and the desired tray types. HYSYS labels the DePropanizer tray section as Section_1. The dimensions and configuration of the trays for Section_1 appears on the Results page of the Performance tab.

58. Confirm the following tray section parameters for Section_1, which will be used for the Main TS tray sections.

Note the Max DP/Tray on this page as well as the Pressure profile of the column, which is available on the Table page.

59. Move to the Setup page on the Design tab and click in the Active check box.

60. Move back to the Results page and click the Export Pressures button. At this time ignore all the warnings by clicking the OK button on the warning’s view.

Variable Value

Section Diameter 2.5 ft

Weir Height 2 in

Tray Spacing 24 in

Total Weir Length 25.38 in

Figure 6.16

6-15


6-16

61. Close the Tray Sizing property view and the Available Utilities view.

62. Double click on the DePropanizer icon to open the Column property view. Click the Column Environment button to enter the Column Sub-Flowsheet.

63. Enter the Main TS property view by double clicking on the Main TS Column in the PFD.

64. On the Sizing page of the Rating tab, enter the tray section parameters as recorded in the above table (on the previous page): Section Diameter, Tray Spacing, Weir height, and Weir length.

65. Change the tray type setting to Valve in the Internal Type group.

The complete Main TS tray section property view is shown below:


67. Access the Column property view by clicking the Column Runner button.

Be aware that the units for each tray section parameter may not be consistent with the units provided in the tray sizing utility. You can select the units you want to input by selecting it from the drop-down menu beside the edit bar at the top of the property view.

Figure 6.17

Open this drop-down menu to select the proper units for your input.



68. In the Profiles page of the Parameters tab, note the steady state pressure profile across the column.

The theoretical top and bottom stage pressure should be calculated so that the pressure on stage 5_Main TS (the Tower Feed stage) is 202.1 psi, while the total pressure drop across the column is 0.6 psi.

69. In the Pressure column of the Profiles group, highlight the value in the Pressure cell for the Condenser and press the DELETE key. Highlight the Reboiler pressure cell and press the DELETE key.

70. Place the cursor in the Pressure cell for the top stage (1_Main TS) and input a value of 201.8 psi. The bottom stage pressure (10_Main TS) should be specified as 202.4 psi.

71. Start the column solver by clicking the Run button at the bottom of the column property view.

72. Return to the Parent (Main) Simulation Environment.

73. Save the case as DynTUT1-2.hsc.

Using the Dynamics Assistant

Before the simulation case can be run in Dynamic mode, the degrees of freedom for the flowsheet must be reduced to zero by setting the pressure-flow specifications. It is also necessary to size the existing valves, vessels, coolers, and heat exchangers in the Main Flowsheet and the Column Sub-flowsheet. The following sizing parameters must be specified for these unit operations:

The Dynamics Assistant makes recommendations as to how the flowsheet topology should change and what pressure-flow specifications are required in order to run a case in Dynamic mode. In addition, it automatically sets the sizing parameters of the equipment in the simulation flowsheet. You should be aware that not all the suggestions that the Dynamics Assistant offers need to be followed.

The Dynamics Assistant will be used to:

• Add Pressure-Flow specifications to the simulation case.• Size the Valve, Vessel, and Heat Exchange operations.

Unit Operation Sizing Parameter

Valves Cv value

Vessels Volume

Coolers/Heat Exchangers k-values

6-17


6-18

74. Click the Dynamics Assistant button. Browse through each tab in the Dynamics Assistant view to inspect the recommendations.

All recommendations the Dynamics Assistant suggests are defaulted to be implemented since the OK check boxes are activated. You can choose which recommendations will be executed by the Assistant by activating or deactivating the OK check boxes by each recommendation.

75. Select the Streams tab. The Streams tab contains a list of recommendations regarding the setting or removing of pressure-flow specifications in the flowsheet.

76. For each page in the Streams tab, set the following recommendations as active or inactive according to the table shown below:

Figure 6.18

Tab [Page] Recommendation Stream OK Check Box

Streams [Pressure Specs]

Remove Pressure Specifications

Feed 1 Active

Set Pressure Specifications

LiquidProd Active

SalesGas Active

Streams [Flow Specs]

Remove Flow Specifications

Feed 1 Inactive

Feed 2 Inactive

Dynamics Assistant Button

An Active recommendation will be implemented by the Dynamics Assistant

An Inactive recommendation will not be implemented by the Dynamics Assistant.

If some of the columns or rows on the pages are not visible, just use the scroll bars beside or under the information area to bring the columns or rows into view.


77. Click on the Pressure Flow Specs tab.

This tab contains a list of unit operations which can use a Pressure Flow or Pressure Drop specification. Typically, all unit operations in Dynamic mode should use the Pressure Flow specification. Ensure that all the recommendations in this page are active:

Streams [Insert Valves]

Insert Valves

Feed 1 Inactive

Feed 2 Inactive

Ovhd Inactive

Streams [Int. Flow Spec]

Set Internal Flow Specification

Reflux Active

Figure 6.19

Tab [Page] Recommendation Unit Operation OK Check Box

Pressure Flow Specs [PF versus DP]

Pressure Flow Spec instead of Delta P

Chiller Active

Gas/Gas Active

Heater Active


6-19


6-20

78. Select the Unknown Sizes tab.

The Unknown Sizes tab in the Dynamics Assistant view contains a list of the unit operations in the flowsheet that require sizing.

• The Valve operations are sized based on the current flow rate and pressure drop across the valve. The valves are sized with a 50% valve opening.

• The Vessel operation volumes are determined based on the liquid exit volumetric flow rate and a 10 minute residence time.

• The Heat Exchanger operations are sized based on the current flow rate and pressure drop across the equipment.

You can modify any of the default sizing parameters in the Unknown Sizes tab. Once a modification has been made to a sizing parameter, the piece of equipment is automatically sized and the volume, Cv, or k-value displayed.

79. For each page in the Unknown Sizes tab, ensure that all the recommendations are active:

Figure 6.20

Use the scroll bar to view more columns that aren’t currently visible.


Unknown Sizes [Volumes]

Vessel Sizing

Chiller Active

Gas/Gas (Tube) Active

Gas/Gas (Shell) Active


80. Next open the Tray sections tab by clicking on it.

This tab identifies tray sections and streams whose total steady state pressure drops are inconsistent with the total pressure drop calculated according to the dynamics rating model.

For the purpose of this example, recommendations on this tab will be ignored.

81. Select the Other tab.

This tab contains a list of miscellaneous changes that should to be made in order for the Dynamic simulation case to run effectively.

82. Activate the following recommendations:

83. Press the Make Changes button once. All the active suggestions in the Dynamics Assistant are implemented. Close the Dynamics Assistant view.

Unknown Sizes [k values]

Heat Exchanger Sizing

Chiller Active

Gas/Gas (Tube) Active

Gas/Gas (Shell) Active

Figure 6.21


Other [Misc]Set Equalize Option Mixers

Mixer-101 Active


6-21


6-22

84. Switch to Dynamic mode by pressing the Dynamic mode button. When asked “Are you sure you want to switch to dynamics?”, click the Yes button.

You can specify the exit temperature of the HEATER operation in Dynamic mode. The duty of the heater is back calculated to make the temperature specification.

85. Enter the Heater property view by double clicking on the Heater operation in the PFD.

86. In the Specs page of the Dynamics tab, select the Product Temp Spec radio button in the Model Details group box.

87. Close the view.


Adding Controller Operations

Key control loops will be identified and implemented using PID Controller logical operations. Although these controllers are not required to run in Dynamic mode, they will increase the realism of the model and provide more stability.

The PFD of the main Flowsheet environment after all the controllers have been added is shown on the next page:

Figure 6.22

Dynamic Mode Button



The PFD of the Column Sub-Flowsheet after the controllers have been added is shown as follows:

Figure 6.23

Figure 6.24

6-23


6-24

Level Control

Level controllers will be added to both the Main Flowsheet and Column Sub-Flowsheet to control the liquid levels of each vessel operation.

89. In the Main Flowsheet environment, add a PID Controller operation by pressing and dragging the PID Controller button from the Object Palette to the PFD. This controller will serve as the InletSep level controller. Follow the steps below to specify the information shown in this table:

90. In the Connections tab, change the Name of the PID Controller operation to Sep LC.



Connections

Name Sep LC


InletSep, Liquid Percent Level

Output Target Object Sep Valve


Action Direct

Kc 2

PV Minimum 0%

PV Maximum 100%

Figure 6.25


91. For the Process Variable Source group box, supply the required information by pressing the Select PV button and selecting the information as shown in the figure below. Press the OK button when you’ve finished selecting the information.

92. For the Output Target Object group box, supply the required information by pressing the Select OP button and selecting the information as shown in the figure below. Press the OK button when you’ve finished making your selection.

Figure 6.26

Figure 6.27

6-25


6-26

93. Supply the following in the Configuration page of the Parameters tab:

94. Press the Face Plate button at the bottom of the property view.

95. Change the controller mode to Auto on the face plate by opening the drop-down menu and selecting Auto.

96. Add a PID Controller operation that will serve as the LTS level controller. Specify the following details:

97. Click the Face Plate button. Change the controller mode to Auto on the face plate.

Input Area Entry

Action Direct

Kc 2

PV Minimum 0%

PV Maximum 100%

Figure 6.28


Connections

Name LTS LC


LTS, Liquid Percent Level

Output Target Object LTS Valve


Action Direct

Kc 2

PV Minimum 0%

PV Maximum 100%


Enter the Column Sub-Flowsheet environment.

98. Instead of entering through the Column property view, click the Object Navigator button in the button bar.

99. Double click on DePropanizer in the Flowsheet group box to enter the Column Sub-Flowsheet environment.

100. Add a PID Controller operation that will serve as the Condenser level controller. Specify the following details:

101. Click the Control Valve button.

102. Enter the following details in the Valve Sizing group box of the FCV for Reflux view:

103. Close the FCV for Reflux view.


Object Navigator Button


Connections

Name Cond LC


Condenser, Liquid Percent Level

Output Target Object Reflux


Action Direct

Kc 1

Ti 5 minutes

PV Minimum 0%

PV Maximum 100%

Input Area Entry

Flow Type Molar Flow

Minimum Flow 0 lbmole/h

Maximum Flow 500 lbmole/h

6-27


6-28

105. Add a PID Controller operation which will serve as the Reboiler level controller. Specify the following details:

106. Click the Control Valve button. Select the Direct Q radio button in the Duty Source group box, if it is not already selected.

107. Enter the following details in the Direct Q group box of the FCV for RebDuty view:

108. Close the FCV for RebDuty view.


Temperature Control

Temperature control is important in this dynamic simulation case. A temperature controller will be placed on the ColdGas stream to ensure that the SalesGas stream makes the 10 F dewpoint specification. Temperature control will be placed on the top and bottom stages of the depropanizer to ensure product quality and stable column operation.

110. Enter the Main Flowsheet environment by clicking the Enter Parent Simulation Environment button.


Connections

Name Reb LC


Reboiler, Liquid Percent Level

Output Target Object Reb Duty


Action Direct

Kc 0.1

Ti 3 minutes

PV Minimum 0%

PV Maximum 100%

Input Area Entry

Min Available 0 Btu/h

Max Available 6x106 Btu/h



111. Add a PID Controller operation that will serve as the ColdGas temperature controller. Specify the following details:

112. Click the Control Valve button. Select the Direct Q radio button in the Duty Source group box.

113. Enter the following details in the Direct Q group box of the FCV for C3Duty view:

114. Close the FCV for C3Duty view.


116. Enter the Column Sub-flowsheet environment.

117. Add a PID Controller operation that will serve as the Depropanizer Top Stage temperature controller. Specify the following details:


Connections

Name Cold TC


ColdGas, Temperature

Output Target Object C3Duty


Action Direct

Kc 1

Ti 10 minutes

PV Minimum -20 oF

PV Maximum 20 oF


Input Area Entry


Max Available 2 x 106 Btu/h


Connections

Name Top Stage TC


Main TS, Top Stage Temperature

Output Target Object CondDuty


Action Direct

Kc 1

Ti 5 minutes

PV Minimum 50 oF

PV Maximum 130 oF

6-29


6-30

118. Click the Control Valve button. Select the Direct Q radio button in the Duty Source group box.

119. Enter the following details in the Direct Q group box of the FCV for CondDuty view:

120. Close the FCV for CondDuty view.

121. Click the Face Plate button. Change the controller mode to Auto on the face plate and input a set point of 86 oF.

122. Add a PID Controller operation that will serve as the Depropanizer 9th stage temperature controller. Specify the following details:

123. Click the Face Plate button. Change the controller mode to Auto on the face plate and input a set point of 184 oF.

124. You should be able to run the integrator at this point without any problems. However, you will probably want to monitor important variables in the dynamic simulation using strip charts.

125. Return to the Parent Environment and save the case as DynTUT1-4.hsc.

Input Area Entry


Max Available 3x106 Btu/hr


Connections

Name Stage9 TC


Main TS, Stage Temperature (9_Main TS)

Output Target Object Reboil Valve


Action Direct

Kc 2

Ti 5 minutes

PV Minimum 110 oF

PV Maximum 260 oF



Now that the model is ready to run in Dynamic mode, a strip chart can be created to monitor the general trends of key variables. The following is a general procedure to install strip charts in HYSYS.


Add all of the variables that you would like to manipulate or model. Include feed and energy streams that you wish to modify in the dynamic simulation. Include unit operation temperature, levels and pressures, that you wish to monitor and record.

A list of suggested variables is shown in the table below:

Set up a simple strip chart using the following method.

Figure 6.29

Variables to Manipulate Variables to Monitor

Tower Feed Molar Flow Ovhd Molar Flow

Heater Q Utility Outlet Temperature LiquidProd Molar Flow

Feed 1 Molar Flow InletSep Liquid Percent Level

Feed 2 Molar Flow LTS Liquid Percent Level

6-31


6-32

127. On the Variables tab, click the Insert button. The Variable Navigator is displayed:

128. Select the Flowsheet, Object and Variable for any of the suggested variables.

129. Click the Add button to add the selected variable to the Variables page.

130. Repeat steps #127 to #129 to add any remaining variables to the Databook.



133. Click the Add button in the Available Strip Charts group box to add a strip chart. HYSYS will create a new strip chart with the default name DataLogger1. You may change the default name by editing the Logger Name cell.

Figure 6.30

The purpose of selecting manipulated and monitored objects is to see how the monitored objects will respond to the changes you make to the manipulated variable.



135. If required, add more strip charts by repeating steps #133 to #134.

136. You can change the configuration of each strip chart by pressing the Setup button.


138. Before starting the integrator, open up the property view for the Ovhd stream in the Column Sub-Flowsheet. Open the Dynamics tab and ensure that the Pressure specification is Active and the Molar Flow specification is Inactive.

139. Start the Integrator by pressing the Integrator Active button in the button bar and allow the variables to line out on the strip chart.

140. Perform an analysis by manipulating the variables (via their property views) and viewing the response of monitored variables.

Figure 6.31

In order to make the strip chart easier to read, it is advisable that you activate no more than six variables per strip chart.

Integrator Active Button (green)

6-33


6-34

Dynamic Refining Tutorial 7-1

7 Dynamic Refining Tutorial

In this tutorial, the dynamic capabilities of HYSYS.Plant will be incorporated into a basic steady state oil refining model. A simple fractionation facility produces naphtha, kerosene, diesel, atmospheric gas oil, and atmospheric residue products from a heavy crude feed. In the steady state refining tutorial, preheated crude was fed into a pre-flash drum which separated the liquid crude from the vapour. The liquid crude was heated in a furnace and recombined with the vapour. The combined stream was then fed to the atmospheric crude column for fractionation. The dynamic refining tutorial will only consider the crude column. That is, the crude preheat train will be deleted from the flowsheet and only the crude column in the steady state refining tutorial will be converted to dynamics.

This complete case has also been pre-built and is located in the file DynTUT2.hsc in your HYSYS\SAMPLES directory

Figure 7.1

7-1

7-2 Dynamic Refining Tutorial

7-2

The main purpose of this tutorial is to provide you with adequate knowledge in the conversion of an existing steady state column to a dynamics column. The tutorial provides a single way of preparing a steady state case for dynamics mode. However, you may also choose to use the Dynamic Assistant to set pressure specifications, size the equipment in the plant, and/or add additional equipment to the simulation flowsheet.

This tutorial will comprehensively guide you through the steps required to add dynamic functionality to a steady state oil refinery simulation. To help navigate these detailed procedures, the following milestones have been established for this tutorial.

1. Obtain a simplified steady-state model to be converted to dynamics.

2. Implement a tray sizing utility for sizing the column and the sidestripper tray sections.

3. Install and define the appropriate controllers.

4. Add the appropriate pressure-flow specifications.


Simplifying the Steady State Flowsheet

The preflash train in the steady state simulation case R-1.hsc will be deleted in this section:

1. Open the pre-built case file R-1.hsc. The crude column simulation file R-1.hsc is located in your HYSYS\SAMPLES directory.

For the purpose of this example, the Session Preference will be set so that the Dynamic Assistant would not manipulate the dynamic specifications.

2. Select Preference from the Tools menu to open the Session Preference view.

3. Move to the Dynamics page on the Simulation tab and uncheck the Set dynamic stream specifications in the background option.

In this Tutorial, you will follow this basic procedure in building the dynamic Model

Before proceeding, it is suggested that you complete Chapter 2 - Dynamic Fundamentals Tutorial to gain a firm understanding of dynamic simulation methods.

In this tutorial, you will be working with SI units. The units may be changed by entering the Preferences property view in the Tools menu bar. In the Units tab, specify SI in the Current Unit Set group box.



5. Add the material stream STORE which will be used to store information from the Atm Feed stream.

Figure 7.2

Figure 7.3

Close Button

7-3


7-4

6. In the STORE stream property view, select the Define from other Stream button. In the Spec Stream As property view, select Atm Feed from the Available Streams group box.

7. Click on the OK button to copy the Atm Feed stream information to the STORE stream.

8. Close the STORE stream view.

Figure 7.4


9. Delete all material streams and unit operations upstream of the Atm Feed stream. The following eight items should be deleted:

10. With the deletion of the above items, stream Atm Feed will be not be fully specified. Enter the Atm Feed stream property view. Select the Define from other Stream button. In the Spec Stream As property view, select STORE from the Available Streams group box and click on OK.

11. Close the Atm Feed stream view.

12. Delete stream STORE.

Figure 7.5

Items to be deleted

Material Streams

Hot Crude

Pre Flsh Liq

Pre Flsh Vap

Raw Crude

Energy Streams

Crude Duty

Unit Operations

Pre Flash Separator

Crude Heater

Mixer


7-5


7-6

This steady state case now contains the crude column without the preflash train. Since the identical stream information was copied to stream Atm Feed, the crude column should operate the same as before the deletion of the preflash train.

13. Save the case as DynTUT2-1.hsc. Open the File menu and select Save As. Type in the file name as DynTUT2-1.hsc and click the Save button.

Equipment and Column Sizing

In preparation for dynamic operation, the column and side stripper tray sections and surrounding equipment must be sized. The steady state column pressure drop is user specified. In dynamics, it is calculated using dynamic hydraulic calculations. Complications will arise in the transition from steady state to dynamics, if the steady state pressure profile across the column is very different from that calculated by the Dynamic Pressure-Flow solver.

The COOLER operations in the pumparounds will not be specified with the Pressure Flow or Delta P option. However, each cooler must be specified with a volume in order to run properly in Dynamic mode.

Figure 7.6


Column Tray Sizing

14. Open the Utilities property view by pressing and releasing CTRL U. The Available Utilities view will appear.

15. Scroll down the list of available utilities until the Tray Sizing utility is visible.

16. Select Tray Sizing, then click on the Add Utility button. The Tray Sizing view, as shown on the next page, will appear.

17. Change the Name from its default Tray Sizing-1 to Main TS.

Figure 7.7

Figure 7.8

7-7


7-8

18. Click on the Select TS button. The Select Tray Section view appears.

19. Select the Main TS Object in the T-100 flowsheet. Click on OK.

20. Select the Always Yes option from the Use Tray Vapour to Size drop down box.

Figure 7.9

Figure 7.10


21. Click on the AutoSection button in the Tray Sizing view and the AutoSection view appears. The default tray internal types are displayed as follows:

22. Keep the default values by pressing Next. The next view displays the specific dimensions of the valve-type trays. Keep the default values and press the Complete AutoSection button.

Figure 7.11

Figure 7.12Note that the Valve tray type is selected as the default option. This option will be entered into the Main TS property view.

7-9


7-10

HYSYS calculates the Main TS tray sizing parameters based on the steady state flow conditions of the column and the desired tray types.

23. On the Specs page of the Design tab type the Number of Flow Paths as 3.

24. Two tray section sizes, Section_1 and Section_2, appear in the Setup page of the Design tab. Section_1 includes trays 1 to 27; Section_2 includes trays 28 and 29. Since there are different volumetric flow conditions at each of these sections, two different tray section types are necessary.

25. Move to the Results page of the Performance tab to display the dimensions and configuration of the trays for Section_1 and Section_2. Since Section_1 is sized as having the largest tray diameter, its tray section parameters should be recorded. Confirm the following tray section parameters for Section_1 that will be used for the Main TS tray sections.

26. Notice that the number of flow paths for the vapour is 3. The Actual Weir length is therefore the Weir Length recorded/3. Calculate the Actual Weir length:

Figure 7.13

Variable Value

Section Diameter 5.334 m

Weir Height 0.0508 m

Tray Spacing 0.6096 m

Weir Length 12.66 m

Variable Value

Actual Weir Length (Weir Length/3) 4.22 m


27. Confirm the Maximum Pressure Drop/Tray and note the number of trays in the Main TS column. The Total Section Pressure drop is calculated by multiplying the number of trays by the Maximum Pressure Drop/Tray.

28. Close the Tray Sizing:Main TS and Available Utilities views by pressing the Close button in the upper right hand corner of the window.

29. Enter the Column Sub-Flowsheet by double clicking on the Column T-100 and then selecting the Column Environment... button from the bottom of the Column property view.

30. On the PFD, enter the Main TS property view by double-clicking on the Main TS Column in the PFD.

31. On the Sizing page of the Rating tab, enter the following tray section parameters: Diameter, Tray Space, Weir Height, Actual Weir Length. Input the Actual Weir length calculated from the number of flow paths in the Sizing page.

32. Select the tray type as Valve from the Internal Type group.

Variable Value

Maximum Pressure Drop/Tray 0.816 kPa

Number of Trays 29

Total Section Pressure Drop 23.66 kPa

Close Button

Be aware that the units for each tray section parameter may not be consistent with the units provided in the tray sizing utility. You can select the units you want to input by selecting it from the drop-down menu beside the edit bar at the top of the property view.

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7-12


34. Access the Column property view by pressing the Column Runner button in the button bar.

35. In the Profiles page of the Parameters tab, note the steady state pressure profile across the column.

Figure 7.14

Figure 7.15



Record the top stage pressure (1_Main TS). Calculate the theoretical bottom stage pressure as follows:

36. In the Pressure column of the Profiles group, specify a bottom stage pressure (29_Main TS) of 221.56kPa.

37. Converge the Column Sub-Flowsheet by pressing the Run Column Solver button in the button bar.

38. Close the Column property view.

Side Stripper Tray Sizing

In this section, the following side stripper operations will be sized using the tray sizing utility as described in the Column Tray Sizing section.

• Kero_SS• Diesel_SS• AGO_SS

39. Open the Utilities property view by selecting Utilities from the Tools menu bar.

40. Select the Tray Sizing utility by double clicking on it.

41. On the Tray Sizing view change the name from its default Tray Sizing to Kero_SS TS.

42. Click on the Select TS button. From the Select Tray Section view select the Kero_SS Object in the T-100 flowsheet by pressing OK.

Bottom Stage Pressure = Top Stage Pressure + Total Section Pressure Drop

(8.2)

Variable Value

Top Stage Pressure 197.9 kPa

Total Section pressure drop 23.66 kPa

Bottom Stage Pressure 221.56 kPa

Figure 7.16

Run Column Solver Button

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7-14

43. Press the AutoSection button in the Tray Sizing view. On the AutoSection view: First press the Next button, then press the Complete AutoSection button to calculate the Kero_SS TS tray sizing parameters.

44. Record the following tray section parameters available on the Results page of the Performance tab:

45. Close the Kero_SS TS tray sizing utility.

46. Size the Diesel_SS and AGO_SS side strippers by repeating steps #33 to #39.

The following tray section parameters are calculated by the Tray Sizing utility for the Diesel_SS and AGO_SS side stripper unit operations:

The pressure drop rating information found in the side stripper tray sizing utilities will not be used to specify the pressure profile of the Side Stripper unit operations. Since there are only three trays in each side stripper, the pressure drop across their respective tray sections is small. Keeping the pressure profile across the side strippers constant will not greatly impact the transition from steady state mode to dynamics.

47. Close the Available Utilities view.

48. You should still be in the Column Sub-Flowsheet environment. If not, enter the Column Sub-Flowsheet by double clicking on the Column T-100 and then selecting the Column Environment... button from the bottom of the Column property view.

Variable Kero_SS

Section Diameter 1.676 m

Weir Height 0.0508 m

Tray Spacing 0.6096 m

Weir Length 1.362

Number of Flow Paths 1

Actual Weir Length 1.362

Variable Diesel_SS AGO_SS

Section Diameter 1.676 m 0.9144 m

Weir Height 0.0508 m 0.0508 m

Tray Spacing 0.6096 m 0.6096 m

Weir Length 3.029 m 0.777 m

Number of Flow Paths 2 1

Actual Weir Length 1.515 m 0.777 m


49. Enter the Kero_SS property view by double clicking on the Kero_SS side stripper in the PFD.

50. In the Sizing page of the Rating tab of the Kero_SS property view, specify the following tray section parameters that were calculated in the above table:

• section diameter• tray spacing• weir height• actual weir length

51. Close the Kero_SS property view.

52. Specify the tray rating information for the Diesel_SS and AGO_SS side strippers by repeating steps #40 to #42.

53. After the column has been specified with the tray rating information, converge the column by pressing the Run Column Solver button in the button Bar.


Figure 7.17

Run Column Solver Button

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7-16

Vessel Sizing

The Condenser and Kero_SS_Reb operations require proper sizing before they can operate effectively in dynamic mode. The volumes of these vessel operations are determined based on a 10 minute liquid residence time.

55. Enter the Condenser property view.

56. In the Conditions page of the Worksheet tab, confirm the following Liquid Volumetric Flow of the following streams:

Figure 7.18

Liquid Volumetric Flow Rate (m3/h) Value

Reflux 106.7

Naphtha 152.4

Waste Water 5.7

Total Liquid Exit Flow 264.8


57. Calculate the vessel volume as follows, assuming a 50% liquid level residence volume and a 10 min. residence time:

The vessel volume calculated for the Condenser is 88.3 m3.

58. On the Specs page of the Dynamics tab, specify the Vessel volume as 88.3 m3 and the Level calculator as a Vertical Cylinder in the Model Details group.

59. Close the Condenser property view.

60. Enter the Kero_SS_Reb property view.

(8.3)Vessel VolumeTotal Liquid Exit Flow Residence Time⋅

0.5-------------------------------------------------------------------------------------------------------------=

Figure 7.19

Figure 7.20

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7-18

61. In the Conditions page of the Worksheet tab, confirm the following Liquid Volumetric Flow of the following streams:

62. Assume a 10 minute of residence time and a 50% liquid level residence volume. The vessel volume calculated for the Kero_SS_Reb is 20.5 m3.

63. On the Specs page of the Dynamics tab, specify the Vessel volume as 20.5 m3 and the Level calculator as a Horizontal Cylinder in the Model Details group.

64. Close the Kero_SS_Reb property view.

Cooler Volume Sizing

HYSYS assigns a default volume to each COOLER unit operation in the Column Sub-Flowsheet. Modify each pumparound cooler to initialize with a default vessel volume.

65. Enter the PA_1_Cooler Property view by double-clicking on the PA_1_Cooler operation in the PFD.

66. In the Specs page of the Dynamic tab, click on the Volume cell in the Model Details group box.

67. Press DELETE.

A default volume of 0.10 m3 is displayed.

68. Check if all the specifications in the Dynamic Specifications group are unchecked.

No dynamic specifications should be set for the pumparound coolers. The Dynamic Specifications group box for the PA_1_Cooler should be

Liquid Volumetric Flow Rate Value

Kerosene 61.61 m3/h

Figure 7.21


displayed as follows:

69. Close the PA_1_Cooler view

70. Specify the volumes of the PA_2_Cooler and the PA_3_Cooler operations by repeating steps #60 to #64.



Controller operations may be added before or after the transition to dynamic mode. Key control loops will be identified and controlled using PID Controller logical operations. Although these controllers are not required to run in Dynamic mode, they will increase the realism of the model and provide more stability.

Level Control

Level controllers will be added to the simulation flowsheet to control the levels of the condenser and reboiler.

72. Add a PID Controller operation by pressing and dragging the PID Controller button from the Object Palette to the PFD. This controller will serve as the Condenser level controller.

73. On the Connections tab of the controller property view, change the Name of the Controller to Cond LC.

Figure 7.22


For more information regarding PID Controller, see Section 10.2 - PID Controller of the Dynamics Modelling guide.

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7-20

74. For the Process Variable Source group box, supply the required information by pressing the Select PV button and selecting the information as shown in the figure below. Click on the OK button when you’ve finished selecting the information.

75. For the Output Target Object group box, supply the required information by pressing the Select OP button and selecting the information as shown in the figure below. Click on the OK button when you’ve finished making your selection.

Figure 7.23

Figure 7.24


76. Supply the following in the Configuration page of the Parameters tab:

77. Click on the Control Valve button. Complete the Valve Sizing group box of the FCV for Reflux view as shown below:

78. Close the FCV for Reflux view.

79. Click on the Face Plate button at the bottom of the property view. The Face Plate for Reactor LC is displayed.

80. Change the controller mode to Auto on the face plate by opening the drop down menu and selecting Auto.

Input Area Entry

Action Direct

Kc 4

Ti 5 minutes

PV Minimum 0%

PV Maximum 100%

Figure 7.25

Figure 7.26

Figure 7.27

For more information regarding Face Plates, see Section 10.1 - PID Controller of the Dynamics Modelling

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7-22

81. Double click on the PV window and input the set point to be 50%.

82. Add a PID Controller operation which will serve as the Kero_SS_Reb level controller. Specify the following details:

83. Click on the Control Valve button.

84. Enter the following details in the Valve Sizing group box of the FCV for Kero_SS_Draw view:

85. Close the FCV for Kero_SS_Draw view.

86. Click on the Face Plate button. Change the controller mode to Auto on the face plate and input a setpoint of 50%.

Flow Control

Flow controllers will be added to the product streams of the column. These controllers will ensure that sufficient material is leaving the column.

Figure 7.28


Connections

Name Reb LC


Kero_SS_Reb, Liquid Percent Level

Output Target Object Kero_SS_Draw


Action Reverse

Kc 1

Ti 5 minutes

PV Minimum 0%

PV Maximum 100%

Input Area Entry

Flow Type MolarFlow

Minimum Flow 0 kgmole/h

Maximum Flow 1000 kgmole/h


87. Add a PID Controller operation which will serve as the Off Gas flow controller. Specify the following details:

88. Click on the Control Valve button. Make sure that the Direct Q radio button in the Duty Source group is selected.

89. Enter the following details in the Direct Q group box of the FCV for Atmos Cond view:

90. Close the FCV for Atmos Cond view.

91. Click on the Face Plate button. Change the controller mode to Auto on the face plate and input a setpoint of 5 kgmole/h.

92. Add a PID Controller operation which will serve as the Diesel flow controller. Specify the following details:



Connections

Name Off Gas FC


Off Gas, Molar Flow

Output Target Object Atmos Cond


Action Direct

Kc 0.01

Ti 5 minutes

PV Minimum 0 kgmole/h

PV Maximum 100 kgmole/h

Input Area Entry

Minimum Available 0 kJ/h

Maximum Available 2 x 108 kJ/h


Connections

Name Diesel FC


Diesel, Liquid Volume Flow

Output Target Object Diesel_SS_Draw


Action Reverse

Kc 1

Ti 5 minutes

PV Minimum 0 m3/h

PV Maximum 250 m3/h

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7-24

94. Enter the following details in the Valve Sizing group box of the FCV for Diesel_SS_Draw view:

95. Close the FCV for Diesel_SS_Draw view.

96. Click on the Face Plate button. Change the controller mode to Auto on the face plate and input a setpoint of 127.5 m3/h.

97. Add a PID Controller operation which will serve as the AGO flow controller. Specify the following details:


99. Enter the following details in the Valve Sizing group box of the FCV for AGO_SS_Draw view:

100. Close the FCV for AGO_SS_Draw view.

101. Click on the Face Plate button. Change the controller mode to Auto on the face plate and input a setpoint of 29.8 m3/h.


Input Area Entry

Flow Type MolarFlow




Connections

Name AGO FC


AGO, Liquid Volume Flow

Output Target Object AGO_SS_Draw


Action Reverse

Kc 0.7

Ti 3 minutes

PV Minimum 0 m3/h

PV Maximum 60 m3/h

Input Area Entry

Flow Type MolarFlow




Adding Pressure-Flow Specifications

Before integration can begin in HYSYS, the degrees of freedom for the flowsheet must be reduced to zero by setting the pressure-flow specifications. Normally, you should make one pressure-flow specification per flowsheet boundary stream. However, there are exceptions to the rule. One extra pressure flow specification is required for every condenser or side stripper unit operation attached to the main column. This rule applies only if there are no pieces of equipment attached to the reflux stream of the condenser or the draw stream of the side strippers. Without other pieces of equipment (i.e. pumps, coolers, valves) to define the pressure flow relation of these streams, they must be specified with a flow specification.

Pressure-flow specifications for this case will be added to the following boundary streams:

• Atm Feed• Main Steam• AGO Steam• Diesel Steam• Off Gas• Waste Water• Naphtha• Kerosene• Diesel• AGO• Residue

This simplified column has all the feed streams specified with a flow specification. The Off Gas stream has a pressure specification which defines the pressure of the condenser and consequently, the entire column. The liquid exit streams of the column and the side stripper operations require pressure specifications since there are no attached pieces of equipment in these streams. All the other exit streams associated with the column require flow specifications.

The following pumparound streams require flow specifications since both the Pressure Flow and the Delta P specifications are not set for the pumparound coolers. Flow specifications are to be made on the following streams:

• PA_1_Draw• PA_2_Draw• PA_3_Draw

For more information regarding Pressure Flow specifications in Column unit operations see Chapter 8 - Column Operation in Dynamic Modelling guide.

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7-26

The following streams have their flow specifications defined by PID Controller operations. They must be set with flow specification:

• Reflux• Kero_SS_Draw• Diesel_SS_Draw• AGO_SS_Draw

103. Enter the Main Flowsheet environment.

104. Switch to Dynamic mode by pressing the Dynamic Mode button. When asked if you want to allow dynamics assistant to identify items which are needed to be addressed before proceeding into dynamics, click on the No button.

Every material stream in the Main Flowsheet requires either a pressure or flow specification. Use the following procedure to set a pressure-flow specification for a general material stream:

105. Double-click on the material stream to enter the material stream’s property view.

106. In the Specs page of the Dynamics tab, activate the flow and/or the pressure of the material stream.

Once a pressure or flow specification has been made active, the stream value turns blue and can be modified by the user.

Figure 7.29

Return to Parent Simulation Environment Button

Dynamic Mode Button


107. Activate the following pressure or flow specifications for the following streams in the Main Flowsheet.

108. Enter the Column Subflowsheet environment using the Object Navigator and then double clicking on T-100 in the Flowsheet group.

Every material stream in the column environment also requires either a pressure or flow specification. Use the following procedure to set a pressure-flow specification for a general material stream:

109. Double-click on the material stream to enter the material stream’s property view.

Material Stream Pressure Specification Flow Specification Value

Atm Feed Inactive Molar Flow 2826 kgmole/h

Main Steam Inactive Molar Flow 188.8 kgmole/h

AGO Steam Inactive Molar Flow 62.95 kgmole/h

Diesel Steam Inactive Molar Flow 75.54 kgmole/h

Off Gas Pressure Inactive 135.8 kPa

Waste Water Inactive Molar Flow 317.7 kgmole/h

Naphtha Inactive Ideal LiqVol Flow 152.4 m3/h

Kerosene Inactive Ideal LiqVol Flow 61.61 m3/h

Diesel Pressure Inactive 212.5 kPa

AGO Pressure Inactive 217.1 kPa

Residue Pressure Inactive 223.4 kPa

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7-28

110. In the Specs page of the Dynamics tab, activate the flow and/or the pressure of the material stream.

Activate the following pressure or flow specifications for the following streams in the Column Subflowsheet.


112. You can close all the views except the face plates.

113. To arrange the face plates, select the Arrange Desktop option from the Windows menu

Figure 7.30

Material StreamPressure-Flow Specification

Value

PA_1_Draw Molar Flow 2183 kgmole/h

PA_2_Draw Molar Flow 830.1 kgmole/h

PA_3_Draw Molar Flow 648.9 kgmole/h

Reflux Molar Flow 883.5 kgmole/h

Kero_SS_Draw Molar Flow 426.6 kgmole/h

Diesel_SS_Draw Molar Flow 616.9 kgmole/h

AGO_SS_Draw Molar Flow 124.8 kgmole/h


114. The integrator can be run at this point. When you are given the option to run dynamic assistant, select No. When the integrator is initially run, HYSYS will detect that no vapour phase exist in the Condenser at the specified process conditions. It will display the following message:

HYSYS recommend that you increase the temperature setting to create a vapour phase. You can also create a non-equilibrium vapour phase or set the liquid level to be 100%. For the sake of this example, select the default recommendation.

115. Click on the Increase Temperature button.

116. Let the integrator run for few minutes, so that all the values have propagated through the column.

117. Stop the integrator using the Stop Integrator button.


Now that the model is ready to run in Dynamic mode, the next step is installing a strip chart to monitor the general trends of key variables. The following is a general procedure to install strip charts in HYSYS.

Figure 7.31

Integrator Buttons

7-29


7-30


119. On the Variables tab, click on the Insert button which will display the Variable Navigator view.

120. Select the Column T-100 from the Flowsheet group by clicking on it.

121. Pick the UnitOps radio button in the Object Filter group. The Object list will be filtered to show unit operations only.

122. Click on the Condenser in the Object list, and the Variable list available for the column will appear for the column will appear to the right of the Object list.

123. Select Liquid Percent Level in the Variable list.

124. Click on the OK button. The variable will now appear in the Databook.

Figure 7.32

Figure 7.33

The Variable Navigator is used extensively in HYSYS for locating and selecting variables. The Navigator operates in a left-to-right manner-the selected Flowsheet determines the Object list, the chosen Object dictates the Variable list, and the selected variable determines whether any Variable Specifics are available.


Add all of that variables that you would like to manipulate or model. A list of suggested variables is shown below:

125. Repeat steps #114 to #119 to add the remaining variables to the Databook as shown in the table below. You may choose to click on the top variable in the list of Available Data Entries before inserting a new variable so that the new variable is always added to the top of the list.

Now that the key variables have been added to the Databook, the next task is to create a Strip Chart to monitor the dynamics behaviour of those variables:


127. Click on the Add button, and HYSYS will create a new Strip Chart with the default name DataLogger1.

128. Activate the Cond Liq Level (%) variable in the Strip Chart by clicking on its blank Active check box.

129. Repeat step #123 to activate the other variables as shown below.

130. Click on the DataLogger1 in the list of Available Strip Charts group and click on the Setup button to open the Strip Chart SetUp view. This view allows you to customize how the data is displayed on the Strip Chart.

Object Variable

Kero_SS_Reb Liquid Percent Level

Off Gas Molar Flow

Condenser Vessel Temperature

Figure 7.34

For more detailed on the Strip Chart setup, refer to Section 5.3.3 - Strip Charts Tab in the User’s Guide.

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7-32

131. On the Strip Charts tab in the Databook, click on the Strip Chart button to view each strip chart.

You are now ready to begin dynamics calculations. The Column Key Variables view should be visible on your Desktop.

132. Start the Integrator by pressing the green Start Integrator button.

133. Allow the variables to line out.

134. Perform an analysis by manipulating variables and viewing the response of other variables.

Start Integrator Button

Dynamic Chemicals Tutorial 8-1

8 Dynamic Chemicals Tutorial

In this tutorial, the dynamic capabilities of HYSYS.Plant will be incorporated into a basic steady state chemicals model. In the steady state Chemicals Tutorial, a continuously-stirred tank reactor (CSTR) converted propylene oxide and water into propylene glycol. The reactor products were then fed into a distillation tower where the glycol product was recovered in the tower bottoms.

The Dynamic Chemicals Tutorial will take the steady state CSTR simulation case and convert it into dynamic mode. If you have not built the simulation for the steady state Chemicals tutorial, you can open the pre-built case included with your HYSYS package.

A flowsheet of the completed Dynamic Chemicals Tutorial is shown as follows:

A completed dynamic case has been pre-built and is located in the file DynTUTOR3.hsc in your HYSYS\SAMPLES directory Before proceeding, it is suggested that you complete Chapter 2

- Dynamic Fundamentals Tutorial to gain a firm understanding of dynamic simulation methods.

Figure 8.1

8-1

8-2 Dynamic Chemicals Tutorial

8-2

Only the CSTR reactor will be converted to dynamic mode. The COLUMN operation will be deleted from the simulation flowsheet.

The Dynamics Assistant will be used to make pressure-flow specifications, modify the flowsheet topology, and size pieces of equipment in the simulation flowsheet. Note that this is only one method of preparing a steady state case for dynamic mode. It is also possible to set your own pressure-flow specifications and size the equipment without the aid of the Dynamic Assistant.

This tutorial will comprehensively guide you through the steps required to add dynamic functionality to a steady state chemicals simulation. To help navigate these detailed procedures, the following steps will be taken to set up the dynamic simulation case:

1. Obtain a simplified steady-state model to be converted to dynamic mode.

2. Use the Dynamic Assistant to set pressure-flow specifications, modify the flowsheet topology, and size the equipment.

3. Modify the Reactor vent stream to account for reverse flow conditions.

4. Set up temperature and level controllers around and in the Reactor vessel.


Simplifying the Steady State Flowsheet

The distillation column in the Chemicals Tutorial will be deleted in this section.

1. Open the pre-built case file TUTOR3.hsc. The Chemicals Processing simulation file TUTOR3.hsc is located in your HYSYS\SAMPLES directory.

2. Delete all material streams and unit operations downstream of the Reactor Prods stream. The following 6 items should be deleted:

In this tutorial, you will be working with Field units. The units may be changed by entering the Preferences property view in the Tools menu bar. In the Units tab, specify Field in the Current Unit Set group box.


3. The steady state simulation case should solve with the deletion of the above items. The PFD for the dynamic tutorial should look like the following:

Before entering dynamics, the pressure specification on the Water Feed stream should be removed so that the MIX-100 unit operation can calculate it’s pressure based on the Prop Oxide stream specification.

4. Open the Water Feed stream property view by double clicking on the stream icon.

5. On the Conditions page of the Worksheet tab delete the pressure setting.


7. Open the MIX-100 property view.

8. On the Parameters page of the Design tab, switch to Equalize All option in the Automatic Pressure Assignment group.

9. Close the mixer property view.

10. Save the case as DynTUTOR3-1.hsc. Open the File menu and select Save As. Type in the file name as DynTUT3-1.hsc and click the Save button.

Items to be deleted

Material Streams

Ovhd Vap

RecyProds

Glycol

Energy Streams

CondDuty

RebDuty

Unit Operations

Tower

Figure 8.2


8-3


8-4

Using the Dynamic Assistant

The Dynamic Assistant makes recommendations as to how the flowsheet topology should change and what pressure-flow specifications are required in order to run a case in dynamic mode. In addition, it automatically sets the sizing parameters of the equipment in the simulation flowsheet. You should be aware that not all the suggestions the Dynamic Assistant offers need to be followed.

The Dynamic Assistant will be used to:

• Add Pressure Flow specifications to the simulation case.• Add Valves to the Boundary Feed and Product streams.• Size the Valve, Vessel, and Heat Exchange operations.

For the purpose of this example, the Session Preference will be set so that the Dynamic Assistant would not manipulate the dynamic specifications.

11. Select Preference from the Tools menu to open the Session Preference view.

12. Move to the Dynamics page on the Simulation tab and uncheck the Set dynamic stream specifications in the background option.


Figure 8.3

Close Button


Now, the Dynamic Assistant can be initiated to evaluate the specifications required to run in dynamic simulation

14. Press the Dynamic Assistant button. Browse through each tab in the Dynamic Assistant view to inspect the recommendations.

All recommendations the Dynamic Assistant suggests are defaulted to be implemented since the OK check box is activated. You can choose which recommendations will be executed by the Dynamic Assistant by activating or deactivating the OK check boxes beside each recommendation.

15. Select the Streams tab. The Streams tab contains a list of recommendations regarding the setting or removing of pressure-flow specifications in the flowsheet.

Figure 8.4

Figure 8.5

Dynamic Assistant Button

An Active recommendation will be implemented by the Dynamic Assistant.

An Inactive recommendation will not be implemented by the Dynamic Assistant.

8-5


8-6

16. For each page in the Streams tab, activate or deactivate the following tabulated recommendations:

The Dynamic Assistant will insert valves on all the boundary flow streams except the Reactor Vent stream. This recommendation was deactivated since it is assumed that the CSTR reactor is exposed to the open air. Therefore, the pressure of the reactor is constant. A constant pressure can be modelled in the CSTR reactor by setting the Reactor Vent stream with a pressure specification. A valve should not be inserted on this stream.

17. Select the Other tab. This tab contains a list of miscellaneous changes that should to be made in order for the Dynamic simulation case to run effectively. Activate the following recommendations:

18. Press the Make Changes button once. All the active suggestions in the Dynamic Assistant are implemented. Close or cancel the Dynamic Assistant view.

19. Switch to Dynamic mode by pressing the Dynamic mode button. When asked if you want to let the dynamics assistant evaluate your process before moving into dynamics, click on the No button.

Since the suggestion to insert a valve on the Reactor Vent stream was deactivated, you must set a pressure specification on this stream.


Streams [Pressure Specs]

Remove Pressure Specifications

Prop Oxide Active

Streams [Flow Specs]

Remove Flow Specifications

Prop Oxide Active

Water Feed Active

Streams [Insert Valves]

Insert Valves

Prop Oxide Active

Reactor Prods Active

Reactor Vent Inactive

Water Feed Active


Other Specs [Misc]

Set Equalize Option Mixers

MIX-100 Active

Dynamic Mode Button


20. Enter the Reactor Vent stream property view by double-clicking on the Reactor Vent stream in the PFD.

21. On the Specs page of the Dynamics tab, activate the pressure specification.

22. Close the Reactor Vent stream property view.

23. The PFD for the dynamic tutorial (before the addition of the controllers) should look like the following:


Modelling a CSTR open to the atmosphere

The CSTR reactor is open to the atmosphere and the liquid level of the reactor can change in dynamic mode. This means that the vapour space in the liquid reactor also varies with the changing liquid level. In order to model this effect, the Reactor Vent stream was set with a constant pressure specification. However, one additional modification to the Reactor Vent stream is required.

Since the liquid level in the CSTR can move up and down, regular and reverse flow can be expected in the Reactor Vent stream. When vapour exits the reactor vessel (regular flow), the composition of the Reactor Vent stream is calculated from the existing vapour in the vessel. When vapour enters the vessel (reverse flow), the composition of the vapour

In order for the CSTR to operate in steady state and dynamic mode, the vessel must be specified with a volume. Since the Dynamic Assistant detected that a volume was already specified for the CSTR reactor, it did not attempt to size it.

Figure 8.6

8-7


8-8

stream from the atmosphere must be defined by the Product Block attached to the Reactor Vent stream. It is therefore necessary to specify the Product Block composition.

The original steady state Chemicals tutorial used a Fluid Package which did not include any inert gases. Therefore, it is necessary to return to the Simulation Basis Manager and add any desired components to the Fluid Package.

25. Enter the Simulation Basis Manager view by clicking on the Enter Basis Environment button.

26. In the Current Fluid Packages group box, the Fluid Package associated with the Chemical Tutorial is displayed:

27. Highlight the fluid package and press the View button.

Figure 8.7

Enter Basis Environment Button

The Simulation Basis Manager allows you to create, modify, and otherwise manipulate Fluid Packages in your simulation case.


28. The Fluid Package: Basis-1 property view appears. Select the Components tab.

29. Select the FullName/Synonym radio button. Move to the Match cell by clicking it, or by pressing and releasing ALT M.

30. Start typing Nitrogen and press the ENTER key. Nitrogen is added to the Current Component List.

31. Close the Fluid Package: Basis-1 property view. In the Simulation Basis Manager view, click on the Return to Simulation Environment button.

32. On the PFD, enter the Reactor Vent stream property view by double-clicking on the Reactor Vent stream.

Figure 8.8

8-9


8-10

33. Enter the Product Block view by clicking on the Product Block button on the Specs page of the Dynamics tab. You can also enter the Product Block view of the Reactor Vent stream by pressing the View Downstream Operation button.

34. Select the Composition tab in the ProductBlock_Reactor Vent view. Specify the composition of the reverse flow stream as follows:

Figure 8.9

View Downstream Operation Button.

Component Mole Fraction

12C3Oxide 0.0

12-C3diol 0.0

H2O 0.0

Nitrogen 1.0


35. Select the Conditions tab in the ProductBlock_Reactor Vent view. Select the Temperature radio button in the Flow Reversal Conditions group box. Input a temperature of 77 oF. These stream conditions will be used to flash the pure nitrogen stream when the Reactor Vent flow reverses.

36. Close the ProductBlock_Reactor Vent view.

37. Close the Reactor Vent stream property view.



Key control loops will be identified and implemented using PID Controller logical operations. Although these controllers are not required to run in dynamic mode, they will increase the realism of the model and provide more stability.

Level Control

A level controller will be used to control the liquid level in the CSTR Reactor operation.

39. Add a PID Controller operation by clicking and dragging the PID Controller button from the Object Palette to the PFD. This controller will serve as the Reactor level controller.

Figure 8.10


8-11


8-12

40. In the Connections tab, change the Name of the controller to Reactor LC.

41. For the Process Variable Source group box, supply the required information by clicking on the Select PV button and selecting the information as shown in the figure below. Click on the OK button when you’ve finished selecting the information.

42. For the Output Target Object group box, supply the required information by clicking the Select OP button and selecting the information as shown in the figure below. Click on the OK button when you’ve finished making your selection.

Figure 8.11

Figure 8.12


43. Supply the following on the Configuration page of the Parameters tab:

44. Click on the Face Plate button at the bottom of the property view. The Face Plate for Reactor LC is displayed.

45. Change the controller mode to Auto on the face plate by opening the drop down menu and selecting Auto.

46. Double-click on the PV window and input the set point to be 85%.

Input Area Entry

Action Direct

Kc 2

Ti 10 minutes

PV Minimum 0%

PV Maximum 100%

Figure 8.13

Figure 8.14

8-13


8-14

Flow Control

Flow controllers will be added to the feed streams in the process.

47. Add a PID Controller operation which will serve as the Prop Oxide flow controller. Specify the following details:

48. Click on the Face Plate button. Change the controller mode to Auto on the face plate and input a set point of 8712 lb/hr.

49. Add a PID Controller operation which will serve as the Water Feed flow controller. Specify the following details:


Connections

Name PropOxide FC


Prop Oxide, Mass Flow

Output Target Object VLV-Prop Oxide


Action Reverse

Kc 0.1

Ti 5 minutes

PV Minimum 0 lb/hr

PV Maximum 18000 lb/hr


Connections

Name WaterFeed FC


Water Feed, Mass Flow

Output Target Object VLV-Water Feed


Action Reverse

Kc 0.1

Ti 5 minutes

PV Minimum 0 lb/hr

PV Maximum 22000 lb/hr


50. Click on the Face Plate button. Change the controller mode to Auto on the face plate and input a set point of 11000 lb/hr.

Temperature Control

A temperature controller will be used to control the temperature of the CSTR reactor. The control will be implemented using a energy utility stream.

51. Add a PID Controller operation which will serve as the Reactor temperature controller. Specify the following details:

52. Click on the Control Valve button. Select the Direct Q radio button in the Duty Source group box.

53. Enter the following details in the Direct Q group box of the FCV for Coolant view:

54. Close the FCV for Coolant view.

55. Click on the Face Plate button. Change the controller mode to Auto on the face plate and input a set point of 140 oF.



Connections

Name Reactor TC


Reactor, Vessel Temperature

Output Target Object Coolant


Action Direct

Kp 1.75

Ti 5 minutes

PV Minimum 70 oF

PV Maximum 300 oF

Input Area Entry

Minimum Energy Flow 0 Btu/h

Maximum Energy Flow 1 x 107 Btu/h

8-15


8-16

57. The integrator can be run at this point. When you are given the option to run the dynamic assistant first before running the integrator, click on the No button. When the integrator is initially run, HYSYS will detect that the Reactor does not have a vapour phase at the specified process conditions. You have the option to select either the default, which is the Increase Temperature, or the 100% Liquid in the Reactor.

58. Select the default setting, Increase Temperature.

59. Stop the Integrator. You will probably want to make changes to key variables in the process, and observe the dynamic behaviour of the model. It is possible to monitor important variables in dynamics using strip charts.

Figure 8.15

Integrator Button



Now that the model is ready to run in dynamic mode, a strip chart can be created to monitor the general trends of key variables.

60. Open the Databook by using the hot key combination CTRL D. The following is a general procedure to install strip charts in HYSYS.

Add all of the variables that you would like to manipulate or model. Include feed and energy streams that you wish to modify in the dynamic simulation.


Setup a simple strip chart in dynamics using the following method.

Figure 8.16

Variables to Manipulate Variables to Monitor

Prop Oxide Mass Flow

Water Feed Mass Flow

Reactor Vessel Temperature

Reactor Prods Comp Molar Flow 12C3Oxide

Reactor Liquid Percent Level

8-17


8-18

61. On the Variables tab, click on the Insert button. The Variable Navigator is displayed:

62. Select the Flowsheet, Object and Variable for any of the suggested variables.

63. Click on the OK button to return to the Databook. The variable will now appear on the Variables page.

64. Repeat steps # 66 to #68 to add any remaining variables to the Databook.

65. After all the variables have been added, close the Variable Navigator.


Figure 8.17

Figure 8.18


67. Click on the Add button. HYSYS will create a new strip chart with the default name DataLogger1.You may change the default name by editing the Logger Name cell.


69. If required, add more strip charts by repeating steps #69 and #70.



72. Start the Integrator and allow the variables to line out.

73. Perform an analysis by manipulating variables and viewing the response of other variables.

8-19


8-20

HYSYS Applications i

HYSYS Applications

This binder contains examples that illustrate many of the features of HYSYS. The applications include aspects of Conceptual Design, Steady State modeling and Optimization. All aspects are not illustrated in every example, so the areas of interest in each application are highlighted below.

The HYSYS Applications describe, in general terms, how to completely model particular processes using various features of HYSYS - detailed methods of constructing the models are not provided. If you require detailed descriptions on how to construct models in HYSYS, a comprehensive Tutorial manual is provided in the documentation package for this purpose.

The examples in the Applications binder provide a broad range of problems related to various segments of industry and are organized as follows:

Gas Processing

G-1 Acid Gas Sweetening with DEA – Steady State Modelling, Optional Amines Package

A sour natural gas stream is stripped of H2S and CO2 in a Contactor (absorber) tower. The rich DEA (diethanolamine) is regenerated in a Stripping tower and the lean DEA is recycled back to the Contactor. To solve this example, you must have the Amines property package, which is an optional property package. A spreadsheet is employed to calculate various loadings and verify that they are within an acceptable range.

The Amines Property Package is an optional property package. It is not included in the base version of HYSYS.

i

ii HYSYS Applications

Refining

R-1 Atmospheric Crude Tower – Steady State Modelling, Oil Characterization

A preheated (450 F) light crude (29 API) is processed in an atmospheric fractionation tower to produce naphtha, kerosene, diesel, atmospheric gas oil (AGO) and atmospheric residue products. A complete oil characterization procedure is part of this example application.

R-2 Sour Water Stripper - Steady State Modelling, Sour Thermo Options, Case Study

Sour water is fed to a distillation tower for NH3 and H2S removal. The use of the Sour Peng Robinson (Sour_PR) is highlighted. HYSYS’s built-in Case study tool is used to examine the effects of varying column feed temperatures.

Petrochemicals

P-1 Propane/Propylene Splitter – Steady State Modelling, Column Sub-Flowsheet

The individual Stripper tower and Rectifier tower components of a propane/propylene splitter system are modelled. Two separate towers in the same Column Sub-Flowsheet are used in this example to illustrate the simultaneous solution power of HYSYS’s Column Sub-Flowsheet.

Chemicals

C-2 Ethanol Plant – Steady State Modelling

An ethanol production process is modelled right from the fermentor outlet through to the production of low grade and high grade (azeotropic) ethanol products.

ii

HYSYS Applications iii

C-4 Synthesis Gas Production - Steady State Modelling, Reaction Manager, Reactors

Synthesis gas (H2/N2 on a 3:1 basis) is the necessary feedstock for an ammonia plant. The traditional process for creating synthesis gas is explored in this example. Air, steam, and natural gas are fed to a series of reactors, which produces a stoichiomtrically correct product. Extensive use of HYSYS’s Reaction Manager is illustrated as four individual reactions are grouped into three reaction sets that are used in five different reactors. This example also demonstrates the use of an Adjust operation to control a reactor outlet temperature. The case is then converted to a dynamics simulation by adding valves and assigning pressure flow specifications on the boundary streams (you require to HYSYS.Plant to perform this step). Reactors are sized using the actual gas flow and the residence time. A spreadsheet operation imports the H2/N2 molar ratio to a ratio controller, controlling the Air flowrate. Temperature controllers are used to achieve the reactors setpoint by manipulating the duty streams.

HYSYS Extensibility

X-1 Case Linking - Steady State Modelling

This case explores the use of the User Unit Operation to link two HYSYS simulation cases such that the changes made to the first case are automatically and transparently propagated to the second case. Within each User Unit Op, two Visual BasicTM macros are used. The Initialize() macro sets the field names for the various stream feed and product connections and created two text user variables. The Execute() macro uses the GetObject method to open the target link case and then it attempts to locate the material stream, in the target case, named by the Initialize() macro.

iii

iv HYSYS Applications

iv

Example Application Layout v

Example Application Layout

All of the applications in this binder are presented using a similar format. On the first page, a process flow diagram (PFD) of the entire process is displayed, followed by a brief engineering overview of the process. The second page contains a PFD representing the individual Sub-Flowsheets as well as Column Sub-Flowsheets PFD, when applicable. The first part consists of setting up the fluid package and selecting components. In the Main Simulation Environment, the Steady State case is built. To complete the application, the complete results of the simulation, taken from the Workbook, are shown.

Operation Summaries

In most of the examples, the unit operations are summarized in text boxes similar to the one shown below. The name and type of operation will always be shown at the top of the summary. In this case the operation is a Compressor named K-100.

COMPRESSOR [K-100]



Inlet 24

Outlet 25

Energy 70

Design [Parameters]

Adiabatic Efficiency

75

CommentsAdd this Compressor between the Separator S-100 and the Ovhd stream.

v

vi Example Application Layout

The table displays all the information applicable to the operation, organized in three columns. The first column contains the tab and page of the unit operation where the information is required. The Compressor, for example, has five tabs; Design, Rating, Worksheet, Performance and Dynamics. Each tab has related pages. The property view for the Compressor K-100 would appear as shown below.

Note that the summary does not state whether the Enable Curves box should be checked. Because this information is not included in the summary, the box is left the at the default value. Generally, if an item on a page (or a tab) is not included in the summary, it should be left at its default. If an entire page (or tab) is not included in the summary, leave all parameters on that page (or tab) at their defaults.

In some of the summaries you will see the heading Comments in the first column. The comment will indicate a specific action in the simulation relating to the operation, such as adding new unit operations between the existing unit operations and streams, or specifying a parameter of a connected stream. In this example, the Comment indicates that a Compressor should be added between the Separator S-100 and the Ovhd stream.

Figure 1

.

vi

Acid Gas Sweetening with DEA G1-1

G1 Acid Gas Sweetening with DEA

G1.1 Process DescriptionIn this example, a typical acid gas treating facility is simulated. A water-saturated natural gas stream is fed to an amine contactor. For this example, Diethanolamine (DEA) at a strength of 28 wt% in water is used as the absorbing medium. The contactor consists of 20 real stages. The rich amine is flashed from the contactor pressure of 1000 psia to 90 psia before it enters the rich/lean amine exchanger, where it is heated to the regenerator feed temperature of 200 F. The regenerator also consists of 20 real stages. Acid gas is rejected from the regenerator at 120 F, while the lean amine is produced at approximately 260 F. The lean amine is cooled and recycled back to the contactor.

Figure G1.1

G1-1

G1-2

Recommended amine strength ranges:

There are two basic steps in this process simulation:

1. Setup - The Component list includes C1 through C7 as well as N2, CO2, H2S, H2O and DEA.

2. Steady State Simulation - The case will consist of an absorber scrubbing the inlet gas using DEA solution, which will be regenerated in a distillation column. Sweet gas will leave the top whereas the bottom stream will be sent to a regenerator column. An analysis on both the SWEET GAS and the ACID GAS will be performed to satisfy the specified criterion.

Lean Amine Strength in Water

Amine Wt %

MEA 15-20

DEA 25-35

TEA, MDEA 35-50

DGA 45-65

Figure G1.2 Figure G1.3

G1-2


G1.2 SetupThe Amines property package is required to run this example problem. This is a D.B. Robinson proprietary property package that predicts the behaviour of amine-hydrocarbon-water systems. The components to be selected are N2, CO2, H2S, C1, C2, C3, i-C4, n-C4, i-C5, n-C5, C6, C7, H2O, and DEA.

Clone the Field unit set. Change the default units for the Liquid Volume Flow to USGPM and the Molar Flow to MMSCFD.

G1.3 Steady State Simulation

The following major steps will be taken to setup this case in steady state:

1. Installing the DEA Contractor - A 20 stage absorber column will be used to scrub the SOUR GAS with DEA solution(DEA TO CONT). The SWEET GAS will leave from the tower from the top whereas the pollutant rich liquid will be flashed before entering REGENERATOR.

2. Regenerating the DEA - The liquid stream from the absorber will be regenerated in a 18 stage distillation column. The ACID GAS will be rejected from the top and the regenerated DEA will be send back to the DEA CONTACTOR.

G1.3.1 Installing the DEA CONTACTOR

Feed Streams

Before the amine contactor can be calculated, an estimate of the lean amine feed (DEA TO CONT) and the inlet gas stream (SOUR GAS) must be provided. The stream specifications are shown here. The DEA TO CONT values will be updated once the recycle operation is installed and has been calculated.

MATERIAL STREAM [DEA TO CONT]

Input Area Entry

Temperature 95 F

Pressure 995 psia

Liquid Volume Flow 190 USGPM

CO2 Mass Frac. 0.0018

Water Mass Frac. 0.720

DEA Mass Frac. 0.280

G1-3

G1-4

Any free water carried with the gas is first removed in a separator operation (V-100):

DEA Contactor

Before installing the column, select Preferences from the HYSYS Tools menu. On the Simulation tab, ensure that the Use Input Experts check box is selected (checked), then Close the view.

MATERIAL STREAM [SOUR GAS]

Input Area Entry

Temperature 86.0000 F

Pressure 1000.0000 psia

Molar Flow 25 MMSCFD

N2 Mole Frac. 0.0016

CO2 Mole Frac. 0.0413

H2S Mole Frac. 0.0172

C1 Mole Frac. 0.8692



iC4 Mole Frac. 0.0026

nC4 Mole Frac. 0.0029

iC5 Mole Frac. 0.0014




H2O Mole Frac. 0.005

DEA Mole Frac. 0.000

SEPARATOR [V-100]


Design [Connections

Feed SOUR GAS

Vapour Outlet GAS TO CONTACTOR

Liquid Outlet FWKO

Design [Parameters] Pressure drop 0 psi

G1-4


The contactor can now be simulated. An Absorber column operation is installed with the specifications shown below. The Amines property package requires that real trays be assumed in the contactor and regenerator operations but in order to model this, component specific efficiencies are required for H2S and CO2 on a tray by tray basis. These proprietary efficiency calculations are provided in the column as part of the Amines package. Tray dimensions must be supplied to enable this feature.

Using this information, the component specific tray efficiencies can be calculated. Run the Column, and once it has converged move to the Efficiencies page on the Parameters tab. Click on the Component radio button and make note of the efficiency values for CO2 and H2S on each tray. HYSYS provides the component tray efficiencies but allows you to specify the desired efficiencies.

ABSORBER COLUMN [DEA CONTACTOR]

Page Input Area Entry

Connections

No. of Stages 20

Top Stage Inlet DEA TO CONT

Bottom Stage Inlet GAS TO CONTACTOR

Ovhd Vapour Outlet SWEET GAS

Bottoms Liquid Outlet RICH DEA

Pressure ProfileTop 995 psia

Bottom 1000 psia

Temperature Estimates

Top Temperature 100 F

Bottom Temperature 160 F

G1-5

G1-6

The Stream RICH DEA from the absorber is directed to valve VLV-100, where the pressure is reduced to 90 psia, which is close to the regenerator operating pressure.

Gases that are flashed off from Rich DEA are removed using the rich amine flash tank (FLASH TK) which is installed as a Separator operation.

Figure G1.4

VALVE [VLV-100]



Inlet RICH DEA

Outlet DEA TO FLASH TK


Pressure (DEA TO FLASH TK) [psia]

90

SEPARATOR [FLASH TK]



Inlet DEA TO FLASH TK

Vapour Outlet FLASH VAP

Liquid Outlet RICH TO L/R

G1-6


G1.3.2 Regenerating the DEA

The Regenerator

The stream RICH TO L/R is heated to 200 F (REGEN FEED) in the lean/rich exchanger (E-100) prior to entering the regenerator (which is represented by a distillation column). Heat is applied to break the amine-acid gas bonds, thereby permitting the DEA to be recycled to the contactor.

The amine regenerator is modelled as a distillation column. There are 20 real stages - 18 stages in the Tray Section plus a Reboiler and Condenser.

HEAT EXCHANGER [E-100]



Tube Side Inlet RICH TO L/R

Tube Side Outlet REGEN FEED

Shell Side Inlet REGEN BTTMS

Shell Side Outlet LEAN FROM L/R

Design [Parameters]Tubeside Delta P 10 psi

Shellside Delta P 10 psi

Rating [Sizing] Tube Passes per Shell 1


Temperature (REGEN FEED)

200 F

DISTILLATION COLUMN [REGENERATOR]


Connections

No. of Stages 18

Feed Streams (Stage) REGEN FEED (4)

Condenser Type Full Reflux

Ovhd Vapour ACID GAS

Bottoms Liquid REGEN BTTMS

Reboiler Duty RBLR Q

Condenser Duty COND Q

Pressure Profile

Condenser Pressure 27.5 psia

Cond Delta P 2.5 psi

Reboiler Pres. 31.5 psia

G1-7

G1-8

For this tower, the component efficiencies will be setup to be constant at 0.80 for H2S and 0.15 for CO2. The efficiencies of the condenser and reboiler must remain at 1.0, so enter the efficiencies for stages 1-18 only. To set the new efficiencies press the Reset H2S CO2 button, and then type the new efficiencies into the matrix. Specify a Damping Factor of 0.40 on the Solver page, Parameters tab, to provide a faster, more stable convergence.

Add a new column specification called Reboiler Duty via the Specs page of the Design tab, as well as set the default specifications as shown below and delete the Reflux Rate and Bttms Prod Rate specifications from the Column Specification list in the Column property view.

DISTILLATION COLUMN [REGENERATOR]


Parameters [Efficiencies]

Condenser 1.0

Reboiler 1.0

1_TS to 18_TS CO2 0.15

1_TS to 18_TS H2S 0.80

Parameters [Solver] Damping Factor 0.40

REGENERATOR Specifications


Design [Specs]

Name

Stage

Spec Value

T Top

Condenser

179.6 F

Name

Energy Stream

Spec Value

Reboiler Duty

RBLR Q

1.356e7 BTU/hr

Name

Stage

Flow Basis

Spec Value

Reflux Ratio

Condenser

Molar

0.5

Name

Draw

Flow Basis

Spec Value

Ovhd Vap Rate

ACID GAS

Molar

2.0 MMSCFD

G1-8


The T Top and Reboiler Duty specifications should be Active; the Reflux Ratio and Ovhd Vap Rate should be set as Estimates only.

The reboiler duty is based on the guidelines provided below, which should provide an acceptable H2S and CO2 loading in the lean amine.

Water make-up is necessary, since water will be lost in the absorber and regenerator overhead streams. A MIXER operation combines the lean amine from the regenerator with a water make-up. These streams mix at the same pressure. Define the composition of MAKEUP H2O as being all water, and specify its temperature to be 70oF. Specify its flowrate and pressure to be 2.195 USGPM and 21.5 psia, respectively.

When you have finished specifying the Makeup H2O stream you will receive a warning message stating that the temperature exceeds the range of the property package and the stream will turn yellow. Since there is no DEA present in this stream the warning can be ignored without negatively affecting the results of this case.

Recommended Steam Rates

lb Steam / USGAL Lean Amine

(based on 1000 BTU / lb Steam)

Primary Amine (e.g. MEA) 0.80

Secondary Amine (e.g. DEA) 1.00

Tertiary Amine (e.g. MDEA) 1.20

DGA 1.30

MIXER [MIX-100]



Inlets MAKEUP H2O

LEAN FROM L/R

Outlet DEA TO COOL

Design [Parameters] Automatic Pressure Assignment

Set Outlet to Lowest Inlet


Temperature (MAKEUP H2O)

70 F

Pressure (MAKEUP H2O)

21.5 psia

Liq. Vol. Flow

(MAKEUP H2O)

2.195 USGPM

Worksheet [Composition]

H2O Mass Frac.

(MAKEUP H2O)

1.0

G1-9

G1-10

Cooler E-101 cools the lean DEA on its way to the main pump. Pump P-100 transfers the regenerated DEA to the Contactor. A recycle is installed in the Flowsheet between the Pump and the Contactor.

Use a Set operation (SET-1) to maintain the pressure of stream DEA TO RECY to be 5 psi lower than the pressure of the gas feed to the absorber

At this point the recycle inlet stream is fully defined, and a Recycle operation is installed with stream DEA TO RECY as the inlet and DEA TO CONT as the outlet. The lean amine stream, which was originally estimated, will be replaced with the new, calculated lean amine stream and the contactor and regenerator will be run until the recycle loop converges. To ensure an accurate solution, reduce the sensitivities for Flow and Composition.

PUMP [P-100]



Inlet DEA TO PUMP

Outlet DEA TO RECY

Energy PUMP Q


Temperature [F] (DEA TO RECY)

95

.COOLER [E-101]



Inlet DEA TO COOL

Outlet DEA TO PUMP

Energy Stream COOLER Q

Design [Parameters]

Pressure Drop 5 psi

SET [SET-1]


Connections

Target DEA TO RECY

Target Variable Pressure

Source GAS TO CONTACTOR

ParametersMultiplier 1

Offset -5

RECYCLE [RCY-1]


ConnectionsFeed DEA TO RECY

Product DEA TO CONT

Parameters [Tolerance]

Flow 1.0

Composition 0.1

The Cooler and the Pump operations will remain unconverged until the Set operation has been installed.

G1-10


G1.4 Simulation AnalysisThe incoming sour gas contained 4.1% CO2 and 1.7% H2S. For the inlet gas flowrate of 25 MMSCFD, a circulating solution of approximately 28 wt.% DEA in water removes virtually all of the H2S and most of the CO2. The conventional pipeline gas specifications is no more than 2.0 vol.% CO2 and 4 ppm (volume) H2S. Looking at the property view of the Sweet Gas stream you will see the sweet gas produced easily meets these criteria.

G1.5 Calculating Lean and Rich Loadings

Concentrations of acid gas components in an amine stream are typically expressed in terms of loading of the amine - defined as moles of the particular acid gas divided by moles of the circulating amine. The Spreadsheet in HYSYS is well-suited for this calculation. Not only can the loading be directly calculated and displayed, but it can be incorporated into the simulation to provide a "control point" for optimizing the amine simulation. Also for convenience, the CO2 and H2S volume compositions for the Sweet Gas stream are calculated.

The following variables were used for the loading calculations.

Figure G1.5

G1-11

G1-12

G1-12

The following formulas will produce the desired calculations.

The acid gas loadings can be compared to values recommended by D.B. Robinson, shown to the right.

Figure G1.6

Maximum Acid Gas Loadings(moles acid gas / mole of amine)

CO2 H2S

MEA,DGA 0.5 0.35

DEA 0.45 0.30

TEA,MDEA 0.30 0.20

Atmospheric Crude Tower R1-1

R1 Atmospheric Crude Tower

R1.1 Process DescriptionAfter passing through a preheat train, 100,000 barrel/day of 29o API crude is fed into a pre-flash separator operating at 450o F and 75 psia. The vapour from this separator bypasses the crude furnace and is re-mixed with the hot (650o F) pre-flash liquids leaving the furnace. The combined stream is then fed to the atmospheric crude column.The column operates with a total condenser, three coupled side strippers, and three pump around circuits.

Figure R1.1

R1-1

R1-2

A naphtha product is produced overhead, a kerosene product is produced from the first reboiled side stripper, a diesel product is produced from the second steam-stripped side stripper, and an atmospheric gas oil (AGO) is produced from the third steam-stripped side stripper.

Figure R1.2

R1-2


The following Assay data is used to characterize the oil for this example:


1. Setup -The component list must include C1 to C4 light ends components as well as the pseudo components that will be used to represent the C5+ portion of the crude oil. The Oil Characterization procedure in HYSYS will be used to convert the laboratory data into petroleum pseudo components.

2. Steady State Simulation - This case will be modelled using a Pre-Fractionation Train consisting of a Separator and Heater. The Outlet stream will then fed to an Atmospheric Crude Fractionator. The results will be displayed.

Light Ends Liq Volume %

Methane 0.0065

Ethane 0.0225

Propane 0.3200

i-Butane 0.2400

n-Butane 0.8200

H2O 0.0000

Bulk Properties

Standard Density 29o API

Assay Liq Volume %Boiling Temperature (°F)

0.0 15.0

4.5 90.0

9.0 165.0

14.5 240.0

20.0 310.0

30.0 435.0

40.0 524.0

50.0 620.0

60.0 740.0

70.0 885.0

76.0 969.0

80.0 1015.0

85.0 1050.0

Any other library components necessary for the overall simulation (e.g., H2O) should be selected as well.

R1-3

R1-4

R1.2 SetupEstablish the Property Package and Component Basis that will be used in the simulation.

R1.2.1 Fluid PackageDefine a Fluid Package with Peng-Robinson as the Property Package, and select methane, ethane, propane, i-butane, n-butane and water as components.

R1.2.2 Oil CharacterizationSelect the Oil Environment toolbar button to enter the Oil Characterization Environment, using the Fluid Package you just created. Three steps are required in characterizing the oil:

1. Define the Assay

2. Create the Blend

3. Install Oil in Flowsheet

Define Assay

On the Assay page of the Oil Characterization view, select the Add button. This will create a new Assay, and you will see the Assay view. Change the Bulk Properties setting to Used. Complete the Bulk Properties, on the right hand side of the view, as follows:

Since the TBP data is supplied, select TBP from the Assay Data Type drop down menu. Select the Edit Assay button and enter the data as follows.

Figure R1.3

This example will be developed in Field units.

Oil Environment Button

R1-4


Change the Light Ends Setting to Input Composition. Enter the light ends data as follows.

Once you are done characterizing the Assay, select the Calculate button. HYSYS will calculate the Working Curves, which can be views on the tab of the same name:

Figure R1.4

Figure R1.5

You can scroll through this table to view all 50 points of the Working Curve.

R1-5

R1-6

Create Blend (Cut the Oil)

Move back to the Oil Characterization view, and on the Cut/Blend page select the Add button. This will create a new Blend, and you will see the new Blend view.

On the Data tab, highlight the Assay you created (it will appear in the Available Assays column). Select the Add button, and HYSYS will transfer that Assay to the Oil Flow Information table.

As a guideline, each Outlet stream from the crude column should contain a minimum of 5 pseudo components whose composition is greater than 1.0%. Therefore, a total of 30 components should fulfil this requirement. From the Cut Option Selection drop down, select User Points, and specify the Number of Cuts to be 30.

HYSYS will calculate the pseudo components, which can be viewed on the Tables page. Select Molar Compositions from the Table Type group drop down list.

Figure R1.6

Figure R1.7

R1-6


Install Oil in Flowsheet

The final step is to install the oil in the flowsheet - on the Install Oil page of the Oil Characterization view, simply enter the name of the stream (Raw Crude) in to which you would like to "install" this oil.

You can now close the Oil Characterization view and return to the Basis Manager. Press the Enter Simulation Environment button on the Simulation Basis Manager view to enter the Main Environment.

R1.3 Steady StateThe following major steps will be taken to set up this case in steady state:

1. Simulate the Pre-Fractionation Train - This determines the feed to the atmospheric fractionator, and includes the pre-flash separation, crude furnace and mixer which recombines the pre-flash vapour and furnace outlet stream.

2. Install the Atmospheric Crude Fractionator - Add the column steam Inlets to the flowsheet and install the crude fractionator using the rigorous distillation column operation.

R1.3.1 Simulate the Pre-Fractionation Train

Inlet Stream

Specify the Inlet stream as shown here. The temperature is 450o F, the pressure 75 psia, and the Liquid Volume Flow is 100000 barrel/day. Because the composition has been transferred from the Oil Characterization, the stream is automatically flashed.

Name [Raw Crude]

Input Area Entry

Temperature [F] 450.0000

Pressure [psia] 75.0000

Liq Vol Flow [barrel/day]

100000.0000

R1-7

R1-8

Pre-Flash Operations

Install the SEPARATOR, HEATER and MIXER as shown:

The Pre-Fractionation Train is as follows; stream Atm Feed has the calculated specifications shown to the left.

SEPARATOR [PreFlash]



Inlet Raw Crude

Vapour Outlet PreFlash Vap

Liquid Outlet PreFlash Liq

Design [Parameters]

Delta P 0 psi

HEATER [Crude Heater]



Inlet PreFlash Liq

Outlet Hot Crude

Energy Crude Duty

Design [Parameters]

Delta P 10.0000 psi


Temperature (Hot Crude)

650 °F

MIXER [Mixer]



Inlets Hot Crude

PreFlash Vap

Outlet Atm Inlet

Design [Parameters]

Pressure Assignment

Set Outlet to Lowest Inlet

Figure R1.8

MATERIAL STREAM [Atm Feed]

Vapour Frac 0.60412

Temperature [F] 613.18


Molar Flow [lbmole/hr]

6855.2

Mass Flow [lb/hr] 1.2850e+06

Liq Vol Flow [barrel/day]

1.000e+05

Heat Flow [Btu/hr] -7.5559e+08

R1-8


R1.3.2 Install Atmospheric Crude Fractionator

Steam and Trim Duty Streams

Before simulating the atmospheric crude tower, the steam feeds as well as the energy stream (Q-Trim - representing the side exchanger on stage 28) to the column must be defined. Three steam streams are fed to various locations in the tower. Specify the steam streams as follows (composition of H2O = 1.0000). The Q-Trim stream does not require any specifications, this will be calculated by the Column.

Column

The main column, Atms Tower, is represented by 29 ideal stages (not including the condenser). The overhead condenser operates at 19.7 psia and the bottom stage at 32.7 psia. The condenser experiences a 9 psi pressure drop. The temperature estimates for the condenser, top stage, and bottom stage are 100o F, 250o F and 600o F, respectively. Condensed water is removed via a side water draw from the three-phase condenser.

HYSYS comes with a 3 Stripper Crude Column template, the Refluxed Absorber template could also be use, but this would add the procedure of installing the Side Strippers and Pump Arounds. For this example we will install the HYSYS 3 Stripper Crude Column custom template.

Press the Custom Column button in the Object Palette, and select Read an Existing Column Template button. Open the 3sscrude.col template file; your column has now been installed.

The 3sscrude.col template installed 40 trays, 29 in the Main Tray section, 3 trays in each of the 3 Side Strippers (1 reboiled and 2 steam stripped), a reboiler, and a condenser.

Name Main SteamDiesel Steam

AGO Steam

Temperature [F] 375.0000 300.0000 300.0000

Pressure [psia] 150.0000 50.0000 50.0000

Mass Flow [lb/hr] 7500.0000 3000.0000 2500.0000

An energy stream can be installed by selecting the appropriate icon from the palette, or a material stream converted to an energy stream via the Util page of the stream property view.

Note that these streams could be installed inside the Column Build Environment as well. By taking this approach, you will need to "attach" these streams to the Column Flowsheet so that they can be used in the calculations.

Note that Input Experts (Preferences) have been turned Off, and the Column is being configured directly through the Property View

Custom Column Button

R1-9

R1-10

On the Connections page, Design tab, of the Column Property view connect the Inlet and Outlet streams to the column Sub-Flowsheet.

The Draw and Return stages of the Pump Arounds and Side Strippers can be modified on the Side Strippers page and Pump Arounds page respectively, SideOps tab, of the Column Runner view.

Figure R1.9

Figure R1.10

Column Runner is another name for the ColumnProperty View

R1-10


In the Atmos Tower Column Runner view, specify the column information below.

Specifications

Move to the Monitor page, Design tab, of the Column Runner. Input the following values into the default set of specifications supplied with the pre-built 3-Side Stripper Column. Note that the Pump Around delta T specification must be changed to a Duty specification. Also, the Basis of each Pump Around Rate specification must be changed to Volume Basis.

For this example, you need to do the following:

1. Delete the Kero SS BoilUp Ratio and the Residue Rate specs (Press the View button and select Delete in the specification property view).

2. Specify the Reflux Ratio spec to have a value of 1, and make it an Estimate only.

3. Change the following default set of specification.

COLUMN [Atms Tower]


Parameters [Profiles]

Condenser Pressure 19.7 psia

1_Main TS Pressure 28.7 psia

29_Main TS Pressure 32.7 psia

Condenser Temperature

100 F

1_Main TS Temperature

250 F

29_Main TS Temperature

600 F

Specification Flow Basis Spec Type Spec Value

Kero_SS Prod Flow Volume 9300 barrel/day

Diesel_SS Prod Flow Volume 1.925e+04 barrel/day

AGO_SS Prod Flow Volume 4500 barrel/day

PA_1_Rate(Pa) Volume 5.000e+04 barrel/day

PA_1_Duty(Pa) Duty -5.500e+07 Btu/hr


R1-11

R1-12

4. Add a new specification (move to the Specs page, and press the Add button in Column Specifications group). Select Column Liquid Flow from the list of available specifications. Complete this specification as shown here. This is an Overflash specification for the feed stage.

5. Add a new specification, select Column Duty from the list of available specifications. Complete the Kero Reb Duty specification as shown below.




Naptha Prod Rate Volume 2.300e+04 barrel/day

Specification Flow Basis Spec Type Spec Value

Figure R1.11

Figure R1.12

R1-12


6. Add a new specification, select Column Vapour Flow specification from the list of available specifications. Complete the Vap Prod Flow specification as shown below.

The final specification list will appear as shown below:

Once you have provided all of the specifications, select the Run button.

Figure R1.13

Figure R1.14

R1-13

R1-14

R1.3.3 Results

Workbook Case(Main) - Material Streams Tab

Workbook Case (Atms Tower) - Material Stream Tab

Figure R1.15

Figure R1.16

R1-14

Sour Water Stripper R2-1

R2 Sour Water Stripper

R2.1 Process DescriptionThe sour water stripper configuration shown in the above PFD is a common unit in refineries. It processes sour water which comes from a variety of sources including hydrotreaters, reformers, hydrocrackers and crude units. The sour water is often stored in crude tanks, thereby eliminating the need for special vapour recovery systems.

A sour water stripper either uses the direct application of stripping steam (usually low quality, low pressure) or a steam-fired reboiler as a heat source. The intent is to drive as much H2S and NH3 overhead in the stripper as possible. The sizing of a sour water stripper is of great importance since its capacity must equal or exceed the normal

Figure R2.1

R2-1

R2-2

production rates of sour water from multiple sources in the refinery. Often refiners find their strippers undersized due to a lack of allowance for handling large amounts of sour water which can result from upset conditions (like start-up and shutdown). Consequently, one often finds a backlog of sour water waiting to be processed in the stripper. With the increasing importance of environmental restrictions, the sour water stripper plays a greater role in the overall pollution reduction program of refiners.

R2.2 IntroductionThe Sour Water feed stream goes through a feed/effluent exchanger where it recovers heat from the tower bottoms stream (Stripper Bottoms). This new stream (Stripper Feed) enters on tray 3 of an 8 tray distillation tower with a reboiler and a total reflux condenser. A quality specification of 10 ppm wt. ammonia on the tower bottoms (Stripper Bottoms) is specified. The tower bottoms, Stripper Bottoms, exchanges heat with the incoming feed and exits as Effluent.


1. Setup - The Sour Peng-Robinson package will be used and the

Figure R2.2

R2-2


components to be selected are H2S, NH3 and H2O.

2. Steady State Simulation - The case will consist of an 8 stage stripper, used to separate H2S and NH3, and a heat exchanger to minimize heat loss.

R2.3 SetupThe Sour Peng-Robinson property package is required to run this example problem. It combines the PR equation of state and Wilson’s API-Sour model for handling sour water systems. The components to be selected are H2S, NH3 and H2O.

R2.4 Steady State Simulation

The following major steps will be taken to setup this case in steady state:

1. Installing the SW Stripper - An 8 stage distillation column will be used to strip the sour components from the feed stream. The liquid leaving the bottom of the column heats the incoming feed stream in a heat exchanger.

2. Case Study - A case study will be performed to obtain steady state solutions for a range of stripper feed temperatures.

R2.4.1 Installing the SW Stripper

Feed Stream

Specify the feed stream as shown on the side.

MATERIAL STREAM SourH2O Feed

Input Area Entry

Temperature [F] 100

Pressure [psia] 40

Liq Vol Flow [barrel/day] 50000

Comp Mass Frac [H2S] 0.0070

Comp Mass Frac [NH3] 0.0050

Comp Mass Frac [H2O] 0.9880

R2-3

R2-4

Operations

The HEAT EXCHANGER Specifications are shown below.

Before installing the column, select Preferences from the HYSYS Tools menu. On the Options page of the Simulation tab, ensure that the Use Input Experts check box is selected(checked). Next, install the column. Use the Distillation button to create the column. This column will have both a reboiler and an overhead condenser.

The Column configuration is shown below:

On the Specs page of the Design tab in the Column property view, use the Add button to install the new specifications. Uncheck the Active

HEAT EXCHANGER Feed Bottoms

Tab[Page] Input Area Entry


Tube Side Inlet SourH2O Feed

Tube Side Outlet Stripper Feed

Shell Side Inlet Stripper Bottoms

Shell Side Outlet Effluent

Design [Parameters]

Tube Side Pressure Drop

10 psi

Shell Side Pressure Drop

10 psi


Temperature (Stripper Feed)

200 °F

COLUMN SW Stripper


Connections

No. of Stages 8

Feed Stream Stripper Feed

Feed Stage 3

Condenser Type Full Reflux

Ovhd Vapour Off Gas

Bottoms Liquid Stripper Bottoms

Reboiler Duty Q-Reb

Condenser Duty Cond Q

Pressure ProfileCondenser Pressure 28.7 psia

Reboiler Pressure 32.7 psia

R2-4


checkbox for the Ovhd Vap Rate specification.

Change the Fixed Damping Factor from its default value to 0.4 on the Solver page of the Parameters tab. A damping factor will speed up tower convergence and reduce the effects of any oscillations in the calculations (the default value is 1.0). The damping factor can be set on the Parameters tab. For more information on which damping factor is recommended for different systems, please refer to the Chapter 7 - Column of the Steady State Modelling Guide.

COLUMN SW Stripper


Design [Specs]

1. Liquid Mass Frac.

Stage

Spec Value

Component

Active

Reboiler

0.000010

NH3

2. Reflux Ratio

Spec Value

Active

10 Molar

Figure R2.3

Figure R2.4

R2-5

R2-6

R2.4.2 Results

Workbook Case (Main)

R2.4.3 Case StudyThe simulation can be run for a range of Stripper Feed temperatures

Figure R2.5

Figure R2.6

Figure R2.7

R2-6


(e.g. 190o F through 210o F in 5 degree increments) by changing the temperature specified for Stripper Feed in the worksheet. You can automate these changes by using the Case Studies feature in the DataBook. In the DataBook property view, enter the variables shown on the Variables page.

Move to the Case Studies tab, use the Add button in the Available Case Studies group to create Case Study 1. Next, check the Independent and Dependent Variables as shown below.

To automate the study, the Dependent Variable a range and Step Size must be given. Press the View button to access the Case Studies Setup view. A complete view with a range and step size for the Stripper Feed Temperature is shown in Figure R2.9.

To begin the Study, press the Start button. Press the Results button, to view the variables. Note, if the results are in graphical form, you must click the Table radio button on the Case Studies view.

Flowsheet Object Variables Variables Description

Case

Cond Q Heat Flow Cooling Water

Q-Reb Heat Flow Steam

Stripper Feed Temperature Temperature

Feed Bottoms UA UA

T-100

Main TS Stage Liq Net Mass Flow (2__Main TS)

Liq MF Tray 2

Main TS Stage Liq Net Mass Flow (7__Main TS)

Liq MF Tray 7

Main TS Stage Vap Net Mass Flow (2__Main TS)

Vap MF tray 2

Main TS Stage Vap Net Mass Flow (7__Main TS)

Vap MF Tray 7

R2-7

R2-8

The results of this study are shown below.

Figure R2.8

Figure R2.9

Figure R2.10

R2-8

Propylene/Propane Splitter P1-1

P1 Propylene/Propane Splitter

P1.1 Process DescriptionA propylene-propane splitter is generally an easy column to converge. However, the critical factor in producing the results is not the ease of solution, but rather the prediction of the relative volatility of the two key components. Special consideration was given to these components, along with others, in developing the binary interaction coefficients for the Peng Robinson and SRK Equations of State to ensure that these methods correctly model this system.

These splitters have many stages, and are often built as two separate columns. This simulation will contain two Columns, a Stripper and a Rectifier. The Stripper is operated as a Reboiled Absorber and contains 94 theoretical stages. The Rectifier is a Refluxed Absorber containing 89 theoretical stages. The Stripper contains two feed steams, one is the known stream, FEED, and the other is the bottoms from the Rectifier. Propane is

Figure P1.1

P1-1

P1-2

recovered from the Stripper bottoms (95%) and Propene is taken off the top of the Rectifier (99%).


1. Setup - The Soave Redlich Kwong (SRK) property package will be used and the component list includes Propane and Propene.

2. Steady State Simulation - The case will consist of an column divided into two tray sections: a Refluxed Absorber as a Rectifier and a Reboiled Absorber as a Stripper.

P1.2 SetupChoose Soave Redlich Kwong (SRK) as the property method for this example. The only two components required are Propane and Propene. For this example use Field units.

Figure P1.2

P1-2


P1.3 Steady State Simulation

The case will be setup in steady state using the Custom Column option. Both the Rectifier and Stripper columns will be built in the same column environment.

P1.3.1 Starting the Simulation

Feed Stream

The conditions and compositions of the Feed stream are shown on the left. Enter this stream in the Main Simulation Environment.

Installing the column

The next step is to install the column. Press the Custom Column button on the Object Palette. The Custom Column will be used to build both columns in a single column environment.

Press the Starting with a Blank Flowsheeet button. You will be placed in the Column Runner view in the Main Environment. Open the Setup page on the Flowsheet tab. Enter stream Feed as an External Feed Stream, making this stream accessible to the Template Environment.

For this example, you will need a Condenser, Reboiler and two Tray Sections. A Tray Section and a Condenser will be used for the Refluxed Absorber (RECTIFIER), a Reboiler and another Tray Section will be used for the Reboiled Absorber (STRIPPER). The overhead product from the STRIPPER will serve as the feed to the RECTIFIER, and the bottoms product from the RECTIFIER provides a second feed to the STRIPPER, entering on stage 1.

P1.3.2 STRIPPER (Reboiled Absorber)

The Reboiled Absorber is installed first. This column has 94 ideal stages and a Reboiler. You should be inside the Column Environment; the

Material Stream [Feed]

Input Area Entry

Vapour Frac 1.0000


Molar Flow [lbmole/hr] 1322.7600

Comp Mole Frac [Propane] 0.4000

Comp Mole Frac [Propene] 0.6000

P1-3

P1-4

Column Runner view and the Column object palette should be displayed.

Installing the Tray Section

For this Column a new Tray Section has to be installed. Select the Tray Section button from the palette. Open the Tray Section property view and supply the following information on the Connections and the Pressures pages, Design tab.

Close the Tray Section view.

TRAY SECTION [STRIPPER]


Design [Parameters] Number of Trays 94


Liquid Inlet Rect Out

Vapour Inlet Boilup

Vapour Outlet To Rect

Liquid Outlet To Reboiler

Optional Feeds Stream

Feed

Tray Number 47

Design [Pressures]Tray 1 290 psia

Tray 94 300 psia

Column Property view is another name for the Column Runner view.

Tray Section Button

P1-4


Installing the Reboiler

The Reboiler for the Absorber must be installed with the Stripper Column. Select the Reboiler button and supply the inputs shown here on the Connections page of the Reboiler property view.

P1.3.3 RECTIFIER (Refluxed Absorber)

The RECTIFIER is installed next. This column has 89 ideal stages and a Partial Condenser.

Installing the Tray Section

Again, a new Tray Section must be installed for the Absorber. Select the Tray Section button on the Object Palette. Open the Tray Section property view and supply the parameters shown below.

Close the Tray Section view.

REBOILER [Reboiler]



Boilup Boilup

Feeds To Reboiler

Bottoms Product Propane

Energy Reboiler Duty

TRAY SECTION [RECTIFIER]



Liquid Inlet Reflux

Vapour Inlet To Rect

Vapour Outlet To Condenser

Liquid Outlet Rect Out

Design [Parameters] Number of Trays 89

Design [Pressures]Tray 1 280 psia

Tray 89 290 psia

Reboiler Button

P1-5

P1-6

Installing the Total Condenser

A Total Condenser is required for the column. Select the Total Condenser button from the palette, and supply the following parameters.

P1.3.4 Adding the SpecificationsTwo specifications are required for this Column.

1. Flow of the RECTIFIER Distillate (Propene) is 774.14 lbmole/hr.

2. RECTIFIER Top Stage Reflux Ratio is 16.4.

TOTAL CONDENSER [Condenser]



Feeds To Condenser

Distillate Propene

Reflux Reflux

Energy Condenser Duty

Figure P1.3

Total Condenser Button

P1-6


P1.3.5 Results

Workbook T-100 (COL1)

Material Streams Tab

Composition Tab

Energy Streams

Figure P1.4

Figure P1.5

Figure P1.6

P1-7

P1-8

P1-8

Ethanol Plant C1-1

C1 Ethanol Plant

C1.1 Process DescriptionTypically an ethanol fermentation process produces mainly Ethanol plus small quantities of several by-products: methanol, 1-propanol, 2-propanol, 1-butanol, 3-methyl-1-butanol, 2-pentanol, acetic acid, and CO2.

The CO2 produced in the fermentation vessel carries some ethanol. This CO2 stream is washed with water in a vessel (CO2 Wash) to recover the Ethanol, which is recycled to the fermentor.

Figure C1.1

Ethanol and Water form an azeotropic mixture at 1 atm. Therefore, with simple distillation, the ethanol and water mixture can only be concentrated up to the azeotropic concentration.

C1-1

C1-2

The Ethanol rich product stream from the fermentor is sent to a concentration (Conc) tower. An absorber with a side vapour draw can be used to represent this tower. The top vapour is fed to a light purification tower (Lights) where most of the remaining CO2 and some methanol is vented. The bottoms of this light tower is fed to the Rectifier.

The side vapour draw from the Concentrator is the main feed for the Rectifier. The Rectifier is operated as a conventional distillation tower. The product of this tower is taken from Stage 2 so to have an azeotropic ethanol product with a lesser methanol contamination. Methanol concentrates towards the top stages, so a small distillate draw is provided at the condenser. Also, a small vent for CO2 is provided at the condenser.

Figure C1.2

Fusel oils are a mixture of propanols, butanols and pentanols, with a potential value superior to that of Ethanol. Accumulation of fusel oils in the Rectification Tower can cause the formation of a second liquid phase and subsequent deterioration of performance for these trays, so small side liquid draws of fusel oils are installed on the rectifier to avoid this problem.

Figure C1.3 Figure C1.4

C1-2

Ethanol Plant C1-3

Another interesting point is the concentration of heavy alcohols in the interior of the Rectifier. These alcohols are normally referred to as Fusel oils, and small side liquid draws are provided in the Rectifier to recover these components.


1. Setup - The NRTL property package and the UNIFAC VLE fluid package will be used for this case. The Components list includes Ethanol, H2O, CO2, Methanol, Acetic Acid, 1- Propanol, 2-Propanol, 1-Butanol, 3-M-1-C4ol, 2-Pentanol and Glycerol.

2. Steady State Simulation - This case will be setup using a separator, two absorber, a refluxed absorber and a distillation column.

C1.2 SetupAny activity model (except Wilson, which cannot predict two liquid phases) can be used to solve this problem. Select NRTL as the Property Package. The necessary components are shown in the FromFerm stream.

On the Binary Coeffs tab of the Fluid Package property view use UNIFAC VLE estimation method and press the Unknowns Only button to estimate the missing interaction parameters.

Figure C1.5

For this Application, use SI units.

C1-3

C1-4

C1.3 Steady State Simulation

C1.3.1 Beginning the SimulationInput the material streams required for the flowsheet. They are shown below.

Name Wash H2O FromFerm Steam A

Input Area Entry Entry Entry

Temperature [C]

25.0000 30.0000 140.0000

Pressure [kPa] 101.3250 101.3250 101.3250

Molar Flow [kgmole/hr]

130.000 2400.0000

Mass Flow [kg/hr]

11000.00

Comp Mole Frac [Ethanol]

0.0000 0.0269 0.0000

Comp Mole Frac [H2O]

1.0000 0.9464 1.0000

Comp Mole Frac [CO2]

0.0000 0.0266 0.0000

Comp Mole Frac [Methanol]

0.0000 2.693e-05 0.0000

Comp Mole Frac [Acetic Acid]

0.0000 3.326e-06 0.0000

Comp Mole Frac [1-Propanol]

0.0000 9.077e-06 0.0000

Comp Mole Frac [2-Propanol]

0.0000 9.096e-06 0.0000

Comp Mole Frac [1-Butanol]

0.0000 6.578e-06 0.0000

Comp Mole Frac [3-M-1-C4ol]

0.0000 2.148e-05 0.0000

Comp Mole Frac [2-Pentanol]

0.0000 5.426e-06 0.0000

Comp Mole Frac [Glycerol]

0.0000 6.64e-06 0.0000

Note: Once you have entered the Mole Fractions for the stream FromFerm, the Mole Fractions will not add up to 1.00. Click on the Normalize button and the total Mole Fraction will equal 1.00.

C1-4

Ethanol Plant C1-5

CO2 Vent Separator

The CO2Vent Separator separates the products from the fermentor. The bottoms liquid of the separator are sent to the distillation section of the plant (Concentrator Tower), while the overhead vapour goes to the CO2Wash Tower. Install a Separator and make the connections shown here.

CO2 Wash Tower

Water is used to strip any Ethanol entrained in the off gas mixture, thus producing an overhead of essentially pure CO2. The bottoms product from the tower is recycled to the Fermentor (however the recycle is not a concern in this example).

Before installing the column, select Preferences from the HYSYS Tools menu. On the Units page of the Simulation tab, ensure that the Use Input Experts checkbox is selected (checked), then Close the view.

The CO2 Rejection Tower is a simple Absorber.

Press the Run button in the Column property view to calculate the CO2 Wash Tower product streams.

SEPARATOR [CO2_Vent]



Feed FromFerm

Vapour Outlet To_CO2Wash

Liquid Outlet Beer

ABSORBER [CO2WASH]


Connections

No. of Stages 10

Feed Streams (Stage)

Wash_H2O (Top Stage)

To_CO2Wash (Bottom Stage)

Ovhd Vapour CO2_Stream

Bottoms Liquid To_Fermentor

Pressure ProfileStage 1 101.325 kPa

Stage 10 101.325 kPa

C1-5

C1-6

Concentrator

This tower removes most of the Methanol from the Fermentor products. The Concentrator is an Absorber with a side vapour draw.

Specify the following specification to fully specify the column and press the Run button in the Column property view to calculate the Concentrator product streams.

ABSORBER [CONC]


Connections

No. of Stages 17


Beer (Top Stage)

Steam A (Bottom Stage)

Ovhd Vapour To_Light

Bottoms Liquid Stillage_A

Side Draw Vapour Rect_Feed (Stage 6)

Pressure ProfileCondenser 101.325 kPa

Reboiler 102.325 kPa


Condenser Temperature

90°C

Reboiler Temperature 110°C

Specifications


Design [Specs]

1. Comp Recovery

Draw

SpecValue

Component

Active

Rect Feed

0.95

Ethanol

2. Draw Rate 1

Draw

Flow Basis

Spec Value

Estimate

Rect Feed

Mass

5000 kg/h

3. Draw Rate 2

Draw

Flow Basis

Spec Value

Estimate

To_Light

Molar

1000 kgmole/h

C1-6

Ethanol Plant C1-7

Lights

The Lights Tower is a purification tower, modelled as a Refluxed Absorber.

Add the following column specification on the Specs page, Design tab, of the Column property view and delete the default Btms Prod Rate and Reflux Ratio specifications from the Column Specification group. Press the Run button in the Column property view to calculate the Light Tower product streams.

REFLUXED ABSORBER [LIGHTS]


Connections

No. of Stages 5


To_Light (Bottom Stage)


Ovhd Vapour Light_Vent

Ovhd Liquid 2ndEtOH

Bottoms Liquid To_Rect

Cond. Energy CondDuty

Pressure ProfileCondenser Pressure 101.325 kPa

Reboiler Pressure 101.325 kPa

Specifications


Design [Specs]

1. Vap Prod Rate

Draw

Flow Basis

Spec Value

Active

Light_Vent

Molar

1.6 kgmole/hr

2. Comp Fraction

Stage

Flow Basis

Phase

Spec Value

Component

Active

Condenser

Mass Fraction

Liquid

0.88

Ethanol

C1-7

C1-8

Rectifier

The primary product from a plant such as this would be the azeotropic mixture of ethanol and water. The Rectifier serves to concentrate the water/ethanol mixture to near azeotropic composition. The Rectifier is operated as a conventional distillation tower. It contains a partial condenser as well as a reboiler.

Specifications


Design [Specs]

3. Reflux Ratio

Stage

Flow Basis

Spec Value

Estimate

Condenser

Molar

5.00

4. Distillate Rate

Draw

Flow Basis

Spec Value

Estimate

2ndEtOH

Molar

2.10 kgmole/hr

COLUMN [RECT]


Connections

No. of Stages 29


To_Rect (19)

Rect_Feed (22)


Ovhd Vapour Rect_Vap

Ovhd Liquid Rect_Dist

Bottoms Liquid Stillage B

Reboiler Duty Rect_RebQ

Condenser Duty Rect_CondQ

Side Draw Liquid (Stage)

1st Prod (2)

Fusel (20)

Pressure ProfileCondenser Pressure 101.325 kPa

Reboiler Pressure 101.325 kPa


Condenser 79°C

Reboiler 100°C

C1-8

Ethanol Plant C1-9

The following specifications, required to run the column, should be given on the Specs page, Design tab, on the Column property view. Also set the damping factor to accelerate the convergence. Delete the default Btms Prod Rate and Reflux Rate specification before running the column.

Specifications


Design [Specs]

1. Reflux Ratio

Stage

Flow Basis

Spec Value

Active

Condenser

Molar

7100

Design [Specs]

2. Ovhd Vap Rate

Draw

Flow Basis

Spec Value

Active

Rect_Vap

Molar

0.100 kgmole/hr

3. Distillate Rate

Draw

Flow Basis

Spec Value

Active

Rect _Dist

Mass

2.00 kg/hr

4. Comp Frac

Stage

Flow Basis

Phase

Spec Value

Component

Active

2_Main TS

Mass Fraction

Liquid

0.95

Ethanol

5. Fusel Draw Rate

Draw

Flow Basis

Spec Value

Active

Fusel

Mass

3.00 kg/hr

6. 1stProd Draw Rate

Draw

Flow Basis

Spec Value

Estimate

1stProd

Molar

68.00 kgmole/hr

Parameters [Solver]

Damping Factor

Enable

0.25

Azeotrope Check ON

C1-9

C1-10

C1.4 Draw Stream LocationThe side liquid draw, Fusel, is added at stage 20. To determine if this is an appropriate stage to recover the heavy alcohols you can view the stage by stage composition profile. To examine this information move to the Parameters tab in the Column Runner. Select the Estimates page. In this view you can see the Composition Estimates of each tray. (See Figure C1.6).

We wish to view the 1-Propanol composition on Tray 20. Scroll through the group until you can see Tray 20 and the 1-Propanol component.

Stage 20 has a high concentration of 1-Propanol (which has the greatest concentration among the heavy alcohols). Therefore, we have selected the appropriate stage for the Fusel draw.

Figure C1.6

C1-10

Ethanol Plant C1-11

C1.5 Results


Material Streams

Figure C1.7

Figure C1.8

C1-11

C1-12

Compositions

Energy Streams

Figure C1.9

Figure C1.10

C1-12

Synthesis Gas Production C2-1

C2 Synthesis Gas Production

C2.1 Process DescriptionThe production of synthesis gas is an important and interesting part in the overall process of synthesizing ammonia. The conversion of natural gas into the feed for the ammonia plant is modelled using three conversion reactions and an equilibrium reaction. To

Figure C2.1

C2-1

C2-2

facilitate the production of ammonia, the molar ratio of hydrogen to nitrogen in the synthesis gas is controlled near 3:1. This ratio represents the stoichiometric amounts of the reactants in the ammonia process.

In a typical synthesis gas process, four reactors are needed. In the model which will be built, five reactors must be used, since conversion and equilibrium reactions cannot be placed in the same reaction set and thus cannot be placed in the same reactor. The Combustor is separated into a conversion reactor and an equilibrium reactor.

Desulfurized natural gas, which is the source of hydrogen in the example, is reformed in a conversion reactor (Reformer) when it is combined with steam. Air is added to the second reactor at a controlled flowrate such that the desired ratio of H2:N2 in the synthesis gas is attained. The oxygen from the air is consumed in an exothermic combustion reaction while the inert nitrogen passes through the system. The addition of steam serves the dual purpose of maintaining the reactor temperature and ensuring that the excess methane from the natural gas stream is consumed. In the last two reactors, the water-gas shift equilibrium reaction takes place as the temperature of the stream is successively lowered.


1. Setup - In this step the Fluid Package, Reaction sets and Reactions Components will be selected. The Reaction Component list includes CH4, H2O, CO, CO2, H2, N2 and O2.

2. Steady State Simulation - The case will be setup in steady state with the following key unit ops:

• Reformer - A conversion reactor in which most of the methane is reacted with steam to produce hydrogen, carbon monoxide and carbon dioxide.

• Combustor - Second conversion reactor, which takes the product of Reformer, an Air stream and a Comb. Steam as feeds.

• Shift Reactors - A series of equilibrium reactors within which the water gas shift reaction occurs.

C2-2


C2.2 SetupFirst, select the Field units.

Build a Fluid Package by choosing the Peng-Robinson equation of state and the required components as shown. Close the Fluid Package property view.

Defining the ReactionsOn the Reactions page of the Simulation Basis Manager, you can organize the reaction information by defining the required reactions and attaching them to reaction sets.

Selecting Reaction ComponentsPressing the Add Components button will make the Reaction Component Selection view appear. In this view, select the FPkg Pool radio button and press the Add This Group of Components button. Selection of the components is simplified as only the components that were attached to the Fluid Package are shown as Associated Components. You can remove nitrogen from the Selected Reaction Components list since it is not involved in any of the reactions. Highlight Nitrogen in the Selected Reaction Components group and press the Remove Comps button. Close this property view.

Figure C2.2


1. Property Package Equation of State - PR

2. Components Methane, Water, Carbon Monoxide, Carbon Dioxide, Hydrogen, Nitrogen, Oxygen

3. Interaction Parameters

Use Library Defaults

4. Rxns Page Attach Global Rxn Set

Refer to Chapter 4 - Reactions of the Basis Manager for explanations on how to define reactions and reaction sets.

The FPkg Pool radio button shows only the components associated with the Fluid Package(s).

If you define a reaction using library or hypothetical components which are not present in an existing Fluid Package, the new components will automatically be added once the reaction set is attached to the fluid package.

If you add library components from here (which are not present in an existing Fluid Package) the new components will automatically be added to any Fluid Package which uses the reaction.

C2-3

C2-4

ReactionsIn this example, there are three conversion reactions and one equilibrium reaction.

Conversion Reactions

Reforming Rxns:

Combustion Rxn:

The equilibrium reaction can be added from the Library page of the Equilibrium Reaction property view. HYSYS provides the equilibrium data and all other pertinent information for the reaction.

(2.1)

(2.2)

CH4 H2O+ CO 3H2+→

CH4 2H2O+ CO2 4H2+→

(2.3)CH4 2O2+ CO2 2H2O+→

Figure C2.3

C2-4


Equilibrium Reaction

Water-Gas Shift Reaction: You can also define reactions and attach reaction sets in the Main Environment by selecting Reaction Package under Flowsheet in the main menu.

(2.4)CO H2O+ CO2 H2+↔

REACTION [Rxn-1]

Reactions Dialog Box

TypeConversion

Tab Input Area Entry

StoichiometryComponent (Stoich. Coeff.)

Methane (-1)

Water (-1)

CO (1)

Hydrogen (3)

Basis

Base Component

Methane

Conversion 40%

Rxn Phase VaporPhase

Comments CH4 + H2O g CO + 3H2

REACTION [Rxn-2]


Type Conversion


Stoichiometry

Component (Stoich. Coeff.)

Methane (-1)

Water (-2)

CO2 (1)

Hydrogen (4)

Basis

Base Component

Methane

Conversion 30%


Comments CH4 + 2H2O g CO2 + 4H2

REACTION [Rxn-3]


Type Conversion


Stoichiometry

Component (Stoich. Coeff.)

Methane (-1)

Oxygen (-2)

CO2 (1)

Water (2)

Basis

Base Component

Methane

Conversion 100%


Comments CH4 + 2O2 g CO2 + 2H2O

REACTION [Rxn-4]


Type Equilibrium

Tab Reaction

Library CO + H2O = CO2 + H2

C2-5

C2-6

Reaction SetsIn HYSYS, each reactor operation may have only one reaction set attached to it. However, a reaction may appear in multiple reaction sets. Thus, you only have to provide 3 reaction sets for all 5 reactors. Note that in the table of reaction sets, RXN-1 and RXN-2 appear in both the first and second reaction sets.

Attaching Reaction Sets to the Fluid PackageOn the Reactions page of the Basis Manager, highlight a Reaction Set and press the Add to FP button. The Add to Fluid Package view will appear, from which you must highlight a Fluid Package and press the Add Set to Fluid Package button.

You can close the view and repeat the procedure for the other two reaction sets.

You may now Enter the Main Simulation Environment, where the streams and unit operations will be installed.

Reaction Set Name Active Reactions

Reformer Rxn Set Rxn-1, Rxn-2

Combustor Rxn Set Rxn-1, Rxn-2, Rxn-3

Shift Rxn Set Rxn-4

Figure C2.4

C2-6


C2.3 Steady State

Installing Streams

There are two feed streams to the first reactor, a Natural Gas stream and a Reformer Steam stream. The other steam stream, Comb. Steam and the Air stream will be defined also. The pressures of the steam and air streams will be specified later using SET operations. Install the streams as shown.

C2.3.1 Building the Flowsheet

ReformerThe Reformer is a conversion reactor, in which most of the methane is reacted with steam to produce hydrogen, carbon monoxide, and carbon dioxide. The outlet gas will also contain the unreacted methane and excess water vapour from the steam. The overall conversion of the two reactions in the Reformer is 70%. Rxn-1, which produces carbon monoxide and hydrogen has a conversion of 40%, while Rxn-2 has a conversion of 30%.

Name Natural Gas Reformer Steam Air Comb. Steam

Temperature[F] 700.0 475.0 60.0 475.0

Pressure [psia] 500.0 <empty> <empty> <empty>

Molar Flow [lbmole/hr] 200.0 520.0 200.0** 300.0**

Comp Mole Frac [CH4] 1.0000 0.0000 0.0000 0.0000

Comp Mole Frac [H2O] 0.0000 1.0000 0.0000 1.0000

Comp Mole Frac [CO] 0.0000 0.0000 0.0000 0.0000

Comp Mole Frac [CO2] 0.0000 0.0000 0.0000 0.0000

Comp Mole Frac [H2] 0.0000 0.0000 0.0000 0.0000

Comp Mole Frac [N2] 0.0000 0.0000 0.7900 0.0000

Comp Mole Frac [O2] 0.0000 0.0000 0.2100 0.0000

COMMENTS: ** signifies initialized values; the molar flows of Air and Comb. Steam will be manipulated by Adjust-2 and Adjust-1 respectively.

C2-7

C2-8

The two reforming reactions are endothermic, so heat must be supplied to the reactor to maintain the reactor temperature. Specify the temperature of the outlet stream, Combustor Feed at 1700 °F, so that HYSYS will calculate the required duty.

CombustorThe second conversion reactor is the Combustor, which has the Reformer product, an Air stream and a Comb. Steam stream as feeds. Air is the source of the nitrogen for the required H2:N2 ratio in the synthesis end product. The oxygen in the air is consumed in the combustion of methane. Any remaining methane is eliminated by its reaction with the entering steam.

HYSYS automatically ranks the three reactions in the Combustor Rxn Set. Since H2O is a reactant in the combustion reaction (Rxn-1) and is a product in the two reforming reactions (Rxn-2 and Rxn-3), HYSYS provides a lower rank for the combustion reaction. An equal rank is given to the reforming reactions. With this ranking in place, the combustion reaction proceeds first until its specified conversion is met or a limiting reactant is depleted. The reforming reactions then proceed based on the remaining methane.

CONVERSION REACTOR [Reformer]

Tab [Page] Input Entry


Feeds Natural Gas

Reformer Steam

Vapour Outlet Combustor Feed

Liquid Outlet Reformer Liq

Energy Reformer Q

Design [Parameters] Optional Heat Transfer

Heating


Combustor Feed Temperature

1700 °F

Reactions [Details] Reaction Set Reformer Rxn Set

CommentsCH4 + H2O g CO + 3H2

CH4 + 2H2O g CO2 + 4H2

C2-8


Set OperationsThe following Set operations are used to specify the pressures of the steam and air streams.

CONVERSION REACTOR [Combustor]



Feeds Combustor Feed

Air

Comb. Steam

Vapour Outlet Mid Combust

Liquid Outlet Mid Liq

Reactions [Details] Reaction Set Combustor Rxn Set

Reactions [Results]

Rxn-1 Conversion 35%



Comments

CH4 + H2O g CO + 3H2

CH4 + 2H2O g CO2 + 4H2

CH4 + 2O2 g CO2 + 2H2O

Reactions of equal ranking can have an overall specified conversion between 0% and 100%.

An alternative method for setting the steam and air pressures is to import the Natural Gas pressure to a Spreadsheet, copy the value for each of the other streams and export the copied values to the streams.

SET [SET-1]


Connections

Target Object Reformer Steam


Source Object Natural Gas


Offset 0

SET [SET-2]


Connections

Target Object Comb. Steam


Source Object Natural Gas


Offset 0

SET [SET-3]


ConnectionsTarget Y Air Pressure

Source X Natural Gas


Offset 0

C2-9

C2-10

Shift Reactors

All three of the shift reactors are equilibrium reactors within which the water-gas shift reaction occurs. In Combustor Shift, the equilibrium shift reaction, which would occur with the reactions in the Combustor, takes place. A separate reactor must be used in the model because equilibrium and conversion reactions cannot be combined within a reaction set. Install the following three equilibrium reactors as shown below:

Since lower temperatures favour the production of hydrogen, heat is removed from Shift Reactor 1 and Shift Reactor 2. The reactor outlet temperature, which equals the vessel temperature, is specified in both cases.

EQUILIBRIUM REACTOR [Combustor Shift]



Feeds Mid Combust

Vapour Outlet Shift1 Feed

Liquid Outlet Mid Com Liq

Reactions [Details]

Reaction Set Shift Rxn Set

Comments Reaction: CO + H2O n CO2 + H2

EQUILIBRIUM REACTOR [Shift Reactor 1]



Feeds Shift1 Feed

Vapour Outlet Shift2 Feed

Liquid Outlet Shift1 Liq

Energy Shift1 Q

Design [Parameters]

Optional Heat Transfer

Cooling


Shift2 Feed Temperature

850°F

Reactions [Details]



EQUILIBRIUM REACTOR [Shift Reactor 2]



Feeds Shift2 Feed

Vapour Outlet Synthesis Gas

Liquid Outlet Shift2 Liq

Energy Shift2 Q

Design [Parameters]

Optional Heat Transfer

Cooling


Synthesis Gas Temperature

750°F

Reactions [Details]



C2-10


C2.3.2 Adjust Operations

Steam FlowrateTo control the temperature of the combustion reaction, the flowrate of steam to the Combustor is adjusted. Since the Combustor is modelled as two separate reactors, target the temperature of the equilibrium reactor, Combustor Shift. An ADJUST operation is used to manipulate the Comb. Steam flowrate to maintain the Combustor Shift temperature at 1700°F.

Press the Start button to begin the Adjust operation.

Air FlowrateTo control the H2:N2 molar ratio in the Synthesis Gas, we need to calculate the ratio in a Spreadsheet and then use an ADJUST operation. The Synthesis Gas should have an H2:N2 molar ratio slightly greater than 3:1. Prior to entering the ammonia plant, hydrogen is used to rid the synthesis gas of any remaining CO and CO2.

In the Spreadsheet, change the Spreadsheet Name to SSRatio and import the following variables:

• Synthesis Gas Comp. Molar Flow of Hydrogen• Synthesis Gas Comp. Molar Flow of Nitrogen

ADJUST [ADJ-1]


Connections

Adjusted Object Comb. Steam

Adjusted Variable Molar Flow

Target Object Combustor Shift

Target Variable Vessel Temp.

Spec. Target Value 1700°F

Parameters

Method Secant

Tolerance 0.1°F

Step Size 50 lbmole/hr

Maximum Iterations 25

C2-11

C2-12

A spreadsheet cell (B4) is used for the calculation of the H2:N2 ratio. The ratio is calculated using the following format:

+’cell that contains flow of H2’/ ’cell that contains flow of N2’

For the H2:N2 ratio cell provide a name for the ratio, such as H2N2Ratio. Go to the Parameters tab and enter the Variable name for the B4 cell as H2N2Ratio.

It is necessary to create a "dummy stream" to export the ratio created in the spreadsheet. To do so, create a stream called "Dummy Stream" and export the ratio to the molar flow of the dummy stream.

Now you can install the ADJUST operation as shown.

Press the Start button to begin the ADJUST operation.

Notice that the Secant method is used for both ADJUST operations, even though each adjusted variable will have an effect on the other operation’s target variable. Please note that the close proximity of the logical operations in the flowsheet increases the possibility of cycling behaviour if the Simultaneous method is used. Therefore, it is advantageous to attempt to iterate on one ADJUST and then solve the other.

ADJUST [ADJ-2]


Connections

Adjusted Variable Air Molar Flow

Target Variable Sprdsht-1 Cell (molar flow of dummy stream)

Spec. Target Value 3.05

Parameters

Method Secant

Tolerance 0.005 lbmole/hr

Step Size 39.68 lbmole/hr

Maximum Iterations 20

To export the ratio, go to the Connections tab of the Spreadsheet. Press the Add Export button, and select the destination of the exported variable. The cell number that appears on the Connections tab beside the destination description, should be that of the exported value.

C2-12


C2.3.3 Results


Material Stream Tab

Composition Tab

Energy Stream Tab

Figure C2.5

Figure C2.6

Figure C2.7

C2-13

C2-14

C2-14

Case Linking X1-1

X1 Case Linking

X1.1 Process DescriptionThis example exploits the User Unit Operation to link two HYSYS simulation cases together such that changes made to the first case (LinkCase1) are automatically and transparently propagated to the second (LinkCase2). More succinctly, this application will demonstrate a method for copying the contents of a stream from one case to another automatically.

The User Unit Op is pre-configured with Visual Basic™ code. Inside the User Unit Op you will define two subroutines: the Initialize() and Execute() macros. The Initialize() macro sets the field names for the various stream feed and product connections and creates two Text user variables: LinkCase and LinkStream. LinkCase contains the path and file name of the target case to be linked. If the variable contains no value, the Initialize() code will set it to be the path to the currently open case and the file name LinkCase2.hsc. LinkStream names a stream in

Figure X1.1

X1-1

X1-2

the second case that will have the T, P, Flow and composition copied to it from the User Unit Op’s feed stream. The target case and stream may optionally be changed explicitly from the Variables page of the User Unit Op.

The Execute() macro uses the GetObject method to open the target link case, which will initially be hidden. It then attempts to locate the material stream named by the LinkStream variable in the target case. If a stream is attached to the Feeds1 nozzle of the User Unit Op, the stream conditions and compositions are then copied between the streams.

Also note that the definition of User Unit Op usually involves the definition of three macros: Initialize(), Execute() and the StatusQuery() subroutines. For this example, the StatusQuery() macro is commented-out to avoid the overhead of having that macro called. Removing the StatusQuery() code entirely would accomplish the same thing, but it is highly recommended that StatusQuery() be implemented to provide valuable user feedback. This implementation is left as an exercise for the reader

X1.2 Building Flowsheet 1The first flowsheet will be modelled using the Peng Robinson Stryjek Vera (PRSV) property package. Select the components and specify stream feed and cold_liq2 as shown here.

Enter the Simulation Environment and add the following unit operations to the flowsheet.

Note that all the stream names are not capitalized.

Note that the use of the DuplicateFluid method to copy the stream parameters requires identical property packages in both simulation cases. The example code instead uses a technique of explicitly copying T and P and then searches for components by name in order to copy their molar flow. Components that are not available in the target case are simply ignored.

Stream Name feed

Input Area Entry

Temperature [C] 11

Pressure [kPa] 5066

Molar Flow [kgmole/h] 100

Comp Mole Frac [C1] 0.5333



Comp Mole Frac [i-C4] 0.0667

Stream Name cold_liq2

Input Area Entry

Temperature [C] -98

Pressure [kPa] 152

Molar Flow [kgmole/h] 7.5




Comp Mole Frac [i-C4] 0.1062

X1-2

Case Linking X1-3

The case should converge immediately. Save the Case as LinkCase1.hsc.

SEPARATOR V-100



Inlet feed

Vapour Outlet feed_vap

Liquid Outlet feed_liq

Design [Parameters]

Delta P 0 kPa

SEPARATOR V-101



Inlet precooled

Vapour Outlet cooled_vap

Liquid Outlet cooled_liq

Design [Parameters]

Delta P 0 kPa

HEAT EXCHANGER

E-100



Tube Side Inlet feed_vap

Tube Side Outlet precooled

Shell Side Inlet cold_liq2

Shell Side Outlet rich gas

Design [Parameters]

Heat Exchanger Model

Exchanger Design (End Point)

Heat Leak/Loss none

Tube Side Delta P

15 kPa

Shell Side Delta P

15 kPa

UA 4000 KJ/C-h

Shell Passes Counter Current

EXPANDER K-100



Inlet cooled_vap

Outlet expanded

Energy shaft work

Design [Parameters]

Efficiency (Adia) 75%


Pressure (Stream expanded)

152 kPa

RECYCLE RCY-1



Inlet cold_liq

Outlet cold_liq2

SEPARATOR V-102



Inlet expanded

Vapour Outlet cold_vap

Liquid Outlet cold_liq

Design [Parameters]

Delta P 0 kPa

COMPRESSOR K-101



Inlet cold_vap

Outlet compressed

Energy shaft work

Design [Parameters]


X1-3

X1-4

X1.3 Building the Flowsheet 2

You must now create the target case for our linked case. This case will use the same property package (PRSV) however contain one extra component, H2O. Enter the Simulation Environment and enter the following unit operations. Please note that because the stream compressed is not specified, the case will not solve. This stream will be specified by the link you will create in the next section.

COMPRESSOR K-100



Inlet compressed

Outlet hot33atm

Energy q1

Design [Parameters]



Pressure (Stream hot33atm)

3344.725 kPa

COMPRESSOR K-101



Inlet cool33atm

Outlet hot100atm

Energy q2

Design [Parameters]



Pressure (stream: hot100atm)

10150 kPa

HEAT EXCHANGER

E-100



Tube Side Inlet hot33atm

Tube Side Outlet cool33atm

Shell Side Inlet wtr1

Shell Side Outlet wtr1b

Design [Parameters]



Tube Side Delta P 15 kPa

Shell Side Delta P 15 kPa


Worksheet

[Conditions]

Temperature

(stream: cool33atm)

17 °C

Temperature

(stream: wtr1b)

25 °C

HEAT EXCHANGER

E-101



Tube Side Inlet hot100atm

Tube Side Outlet sales

Shell Side Inlet wtr2

Shell Side Outlet wtr2b

Design [Parameters]



Tube Side Delta P 15 kPa

Shell Side Delta P 15 kPa


Worksheet

[Conditions]

Temperature

(stream: sales)

20 °C

Temperature

(stream: wtr2b)

25 °C

X1-4

Case Linking X1-5

Once you have completed specifying this flowsheet, save the case as LinkCase2.hsc and close it.

X1.4 Creating a User Unit Operation

Now that both cases have been created, you may begin creating the link between them. Open LinkCase1.hsc again. Add a User Unit Op to the flowsheet. Defining the User Unit Op will consist of writing two different subroutines.

• Initialize - defines material and energy feed/product streams and creates user variables

• Execute - opens target case, finds target stream and copies the stream conditions from the main case.

The definition of the User Unit Op will be done through the Edit Existing User Variable view. You may access this view by selecting the Edit button on the Code page of the Design tab.

X1.4.1 Initializing User Unit OpThe following table contains a listing of the code required to implement this operation, along with a brief description of what is meant by the code. Please note that partitions placed in the code are merely made to clearly associate the relevant code with the explanation. Also note that indentations made in the code are common with standard programming practices.

TEE T-100



Feed cooling water

Product wtr2

wtr1

Worksheet

[Conditions]

Temperature

(stream: cooling water)

11 °C

Pressure (stream: cooling water)

202.6 kPa

Worksheet [Composition]

H2O (stream: cooling water)

1.0000

X1-5

X1-6

Code Explanation

Sub Initialize () Signifies the Start of the initialization subroutine. You do not have to add it as it should already be there.

ActiveObject.Feeds1Name = "Feed"ActiveObject.Products1Name = "Unused Prod1"ActiveObject.Feeds2Name = "Unused Feed2"ActiveObject.Products2Name = "Unused Prod2"

You are setting the names that will be associated with the energy and material (primary and secondary) inlet and exit connections.

ActiveObject.Feeds2Active = FalseActiveObject.Products2Active = FalseActiveObject.EnergyFeedsActive = FalseActiveObject.EnergyProductsActive = False

Deactivates the secondary inlet and exit connections as well as the energy inlet and exit connections. After the initialization subroutine has been successfully implemented, the check boxes associated with the secondary material connections and energy connections should be deactivated as shown in the figure above.

Dim LinkCase As ObjectSet LinkCase = ActiveObject.CreateUserVariable("LinkCase", "LinkCase",

uvtText,utcNull, 0)Dim LinkStream As ObjectSet LinkStream = ActiveObject.CreateUserVariable("LinkStream", "LinkStream",

uvtText,utcNull, 0)

Creates two Text user variables called LinkCase and LinkStream. They will appear on the Variables page of the Design tab along with their current values.

Set myVarWrapper = ActiveObject.GetUserVariable("LinkCase")myVarWrapper.Variable.Value = ActiveObject.Flowsheet.Parent.Path +

"LinkCase2.hsc"

Creates a reference to the LinkCase user variable called myVarWrapper. The value of myVarWrapper is set to a string containing the path of the current case and the new case name. Since myVarWrapper is a reference, this value is also carried over to the LinkCase variable.

Set myVarWrapper = ActiveObject.GetUserVariable("LinkStream")Changes the reference of myVarWrapper to the LinkStream user variable.

X1-6

Case Linking X1-7

Once this is entered, press the OK button to close the Edit Existing User Variable view. Go to the Code page of the Design tab and select the Initialize button. The Connections page of the design tab should contain their new designations. On the Variables page you should see the user variable LinkCase contain the case LinkCase2 including the path. If the feed drop list on the Connections page is empty, value of LinkStream variable should currently be feed.

X1.4.2 Operation Execution

If ActiveObject.Feeds1.Count > 0 Then myVarWrapper.Variable.Value = ActiveObject.Feeds1.Item(0).nameElse myVarWrapper.Variable.Value = "feed"End If

If the number of streams specified in the primary feed drop-down is greater than 0 (i.e. at least one stream), the value of myVarWrapper (hence the value of the LinkStream user variable) is the name of the first item that appears in the list of primary feed streams.

If the primary feed drop-down list is empty, the LinkStream variable will be set to the default name “feed”

End Sub Signifies the end of the initialization subroutine. This line does not need to be added.

Code Explanation

Code Explanation

Sub Execute ()Signifies the Start of the operation execution subroutine. You do not have to add this line as it should already be there.

On Error Goto EarlyGraveIf an error occurs during the execution of this subroutine, go to the line of code designated EarlyGrave.

If ActiveObject.Feeds1.Count <> 1 Then Exit SubEnd If

If the number of streams specified in the Feed list is not 1 then exit the subroutine.

Dim Case2 As ObjectSet Case2 = GetObject(ActiveObject.GetUserVariable(“LinkCase”).Variable.Value)

Creates a reference to the LinkCase user variable called Case2.

Dim Case2FS As ObjectSet Case2FS = Case2.Flowsheet

Creates a reference to the flowsheet inside Case2 (LinkCase) called Case2FS.

Dim Case1FS As ObjectSet Case1FS = ActiveObject.Flowsheet

Creates a reference to the current flowsheet called Case1FS.

Dim Case2Strm As ObjectSet Case2Strm = Case2FS.MaterialStreams.Item(ActiveObject.GetUserVariable

(“LinkStream”).Variable.Value)

Creates a reference to a stream in the other case. The stream’s name is the value of the user variable LinkStream.

Dim Case1Strm As ObjectSet Case1Strm = ActiveObject.Feeds1.Item(0)

Creates a reference to stream currently in the primary feed list.

X1-7

X1-8

Once you are finished, you may activate the view by simply selecting the compressed stream as the Feed on the Connections page of the Design tab.

Case2Strm.TemperatureValue = Case1Strm.TemperatureValueCase2Strm.PressureValue = Case1Strm.PressureValue

Sets the Temperature and Pressure values of Case2Strm to those of Case1Strm.

Dim Case1CMFs As VariantCase1CMFs = Case1Strm.ComponentMolarFlowValue

Creates an array containing the molar flow of Case1Strm. Note that Set was not used so changes made to Case1CMFs will not affect Case1Strm.

Dim Case2CMFs As VariantCase2CMFs = Case2Strm.ComponentMolarFlowValue

Creates an array containing the molar flow of Case2Strm. Note that Set was not used so changes made to Case2CMFs will not affect Case2Strm.

On Error GoTo NoCompFor i = 0 To Case2FS.FluidPackage.Components.Count - 1 Case2CMFs(i) = 0.0 n = Case1FS.FluidPackage.Components.index(Case2FS.FluidPackage.Components.

Item(i).name) Case2CMFs(i) = Case1CMFs(n)NoComp:Next i

For every component i in the Case2FS, you set the molar flow of component i in the Case2CMFs array to the flow of the same component in Case1CMFs array.

On Error GoTo EarlyGraveCase2Strm.ComponentMolarFlowValue = Case2CMFs

This passes the value of Case2CMFs to the Case2Strm.

ActiveObject.SolveCompleteSignifies the Unit Operation has solved. It is used to minimize the number of times the User Unit Op’s Execute() is called.

EarlyGrave: Marker

End Sub Signifies the end of the initialization subroutine. This line does not need to be added.

Code Explanation

X1-8

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