hysys dynamics, software

7/24/2019 HYSYS Dynamics, Software

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2010 Aspen Technology, Inc. All rights reserved

Wim Van Wassenhove

Aspentech

HYSYS Dynamics

Why Dynamic Modeling and howdoes it work?


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2010 Aspen Technology, Inc. All rights reserved | 2

Why dynamic simulation?

A properly operating plant = Increased benefits

Some of the common plant problems

Start-ups taking too long

Too much off-spec product

Capacity limited because of operability problems

Violating environmental law can be very expensive

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Why dynamic simulation?

Overdesign of security equipment to ensure safety

Energy efficient plants are usually less stable

Finding out the problems late is expensive

Tuning operation directly on the plant is

Less effective or VERY expensive

Potentially dangerous and source of more problems

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Throughout the plant lifecycle

Process design

Hazop type studies

Pre start-up preparations

Process modifications

Analyse / Troubleshoot operability problems

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What does HYSYS Dynamics offer?

Seamless transition from Steady State to Dynamic

Versatile solver, integrator and flash

Rich choice between simple and detailed modeling

A comprehensive library of operations

Event scheduler

Dynamics extensibility

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Completely integrated with HYSYSSteady State

Same program

Same GUI

Same Thermodynamic models

All input data are shared

Steady State results can be used as initialisation fordynamic simulation

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Steady State

Dynamic mode


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Interactive Environment

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Solver, integrator and flash

Layered integration approach Pressure flow solver uses implicit Euler integration

Flash efficiencies for real vessel behaviour

Real nozzle behaviour

Forward and backward flow

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Rich choice between simple and detailedmodeling options

A linear valve with instant action

or

An equal percentage valve with

an actuator with linear rate

an actuator with a defined fail mode

a holdup

An offset to simulate leaking

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Rich choice between simple and detailedmodeling options

A vessel with only the volume given

or

A vessel with

Height and width

Vessel elevation defined Nozzle positions defined

Heat losses defined

Entrainment modeling

Level taps

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A comprehensive library of operations

Vessels

Piping

Reactors

Heat transfer

Distillation columns

Rotating equipment

Logical operations

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Control features in HYSYS Dynamics

Boolean Gates:

And, Or, delay,

latch, counter,

Split Range Controller

Ratio Controller

PID Controller

and Feedforward

Generic

MPC Controller

DMCplus Controller

Cause&Effect Matrix

Transfer Function:

Lag, Lead, ramp,

Integrator, 2ndorder,

sine wave,

Override Selector

On/Off ControllerSpreadsheet for

custom calculationsAnti-surge

Controller



Spreadsheet

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Event scheduler

Timed and logical execution ofcommands

Applicable to

Shut-down logic

Batch recipes

Repeating scenarios

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User Models

Two Options: Modules developed in a programming language via ActiveX

technology

Modules developed in Aspen Custom Modeler

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Dynamics extensibility

If the model library does not supply the model

Programmable in any OLE-compliant language

Ready built blocks can be used

Legacy code can be integrated

Shares the same interface as the HYSYS models

Can use HYSYS properties

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OLE client and server

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User created unit operation


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Transition from Steady State to DynamicsFive Steps to Get There

Add missing Equipment

Size all Equipment

Set the Pressure Flow Specifications

Add Process Control

Set up visualisation and possibly scenarios


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Add Missing Equipment

A Steady State Model is like a PFD

A Dynamic Model is like a P&ID

Number one missing items are valves

Keep in mind the purpose of the model

If no shutdown modelling is required, why add block valves?


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Equipment Sizing

Sizing info is almost always on the Rating or Dynamics Tabs

Use actual information as much as possible

HYSYS can estimate some data, but only use if no data

Valve Sizing

Pump Curve Generation

Vessel sizing

Level of detail required in sizing depends on model purpose

No need to add level taps unless level measurement is key

For very fast processes, valve dynamics may be essential


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Pressure Flow Specs

Pressure-flow specifications and relationships

Material Streams

Pressure specification

Flow specification

Select one of the two Usually only on boundary streams

Equipment

Fixed Pressure drop (Rarely used)

Pressure/Flow equation (prefererd, it is more realistic)

Resistance calculation (for valves)

Conductance Calculation (for process equipment)


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Add Process Control

A model can run without controllers But can your process run without them?

Usually essential to keep the process operating

Liquid levels are usually the first ones to control

Enter controllers as on the P&ID

Make sure you have sensor ranges (= PV Range)

Make sure you have the controller tunings

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