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Aspen Tech Handbook: A Technical Aide for Chemical Engineering Process Design Students

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Contents

For information on the contents of any section, read the opening paragraph of that section, or use the alphabetical index in the back of the handbook for easier searching.

Chapter 1 2 3 4 5 6 7 8 9 Computer Management Multicomponent Flash Drums Generating Graphs in Aspen Modeling Distillation Columns Modeling Reactors Using RateFrac for Rate-Based Simulations Putting Everything Together Using Aspen Icarus for your Cost Estimate Using Aspen Pinch For Your Heat Integration

Title

Page 2 6 10 13 20 22 26 34 39

Appendix A Appendix B Appendix C

Thermodynamic Property Tree References Index

47 48 49

Note: The makers of the AspenTech, Inc.s Aspen Plus simulation engine have no affiliation with this tutorial. This tutorial was produced for educational purposes and any distribution of this material without the expressed written consent of Cornell University is strictly prohibited. Possible side effects of using this software include: blurred vision, self-induced hair loss, hours of frustration, and the realization that you probably never need to use activity coefficients again. Please consult your physician before operating the simulation engine.

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Preface to the Manual

Over the last several years, we have introduced modern Chemical Engineering software to the Unit Operations and Design Courses. Even more recently, we have introduced AspenPlus simulation to the Separations Course and we hope this "downward" integration will continue. The value to the senior courses has been enormous and many graduates have expressed that knowing something about these computer techniques has been helpful in their jobs. Unfortunately, as the programs get more able to predict real processes and equipment, they become more complicated. The "Help" manuals are not easy (although they are complete) and step-by-step tutorials are non-existent. Keep in mind that we are being provided with several hundred thousand dollars worth of software and licenses for a tiny fraction of the normal price. While Aspen does provide technical service, we cannot expect them to answer our specific questions overnight. In the spring of '01, Brock Tuczynski was a TA for Separations and wrote a very nice tutorial for getting started with Aspen. I had written several sets of instructions for solving various problems with Aspen and Icarus and, over the years, we had assembled lots of specific but unorganized answers to questions. Over the summer of '03, Josh Banke and Meghan Cuddihy put together this tutorial. They edited Brock's original work, tied together all we had and wrote many new sections. They have tried to make this into a comprehensive user's guide to the Aspen and Icarus software and have added quite a bit of material about the computer lab organization and setup that I hope you will find useful. Good luck as you become more proficient with the simulations and remember that these are difficult and complicated programs to use. Patience is important. One last piece of advice: the fundamentals of Chemical Engineering are the most important tools you have. I have seen many, many flash drums that were not adiabatic, columns with a reflux ratio below the minimum( try a McCabe-Thiele Diagram for starters), and overall material balances that were not right. Start every problem with a sketch, a material balance and a heat balance and you will spend a lot less time trying to get yo ur process to converge. Ken Ackley

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Chapter 1: Computer ManagementThe purpose of this chapter is mainly to demonstrate how to setup a shared folder on the computer lab network, how to optionally set up one from your home, as well as to discuss some of the more pertinent issues regarding managing and securing the integrity of your computer that are useful to know. Windows XP File Sharing Windows XP lets you share a computer's disks and folders with other computers on the network, using a method called Simple File Sharing. If a disk or folder is shared, everyone with whom you give permissions to the file may access it from the network. This can be useful for several reasons: a shared folder will make it easy for all members of the group to access any saved Process Design or UO files; it obviates a need for writing files to discs or other data transfer media; and it can ward off any answer predators, who might want access to your Aspen or Icarus files. Probably the simplest method for going about this is to share and set permissions on a folder in your account on the Instruct Domain. Here is a brief explanation of how to do that. o Note: The computers in the computer lab in Olin Hall should have Windows XP Professional, if not the latest operating system, installed and running, so we will try to base our example on that assumption. In our example, we've used Windows Explorer to browse to the directory of the My Documents folder, which should be located on the desktop. o In the right-hand pane, right-click, select New and then Folder, and enter the name Shared Folder (or whatever you feel comfortable naming it). o Note: For maximum compatibility with all versions of Windows, use 1-12 characters. o Now, you should specify sharing options for the folder you have created. To do this, rightclick the folder and select Sharing and Security. o On the Sharing tab, select Share this folder and enter a share name. You can add a comment that describes the share on other computers on the same network. o Leave the User limit alone. On XP professional, the maximum limit is 10. o You should probably set some password permissions, so that only you or your group members can access it. To do this: o Click Permissions. Notice that, by default, the group Everyone has Full Control. This means that all users can read, write, and even delete files. That's not what we want at all! o Click Add, and then choose Object Types. Un-check Built-in security principles and Groups, because we only want to see Users. Click OK. o Choose Advanced, and click Find Now. Click on the users who should have access to this share. This should include your group partners and you. You can repeat this to add additional users. When you are done, click OK. o You should be back at the Permissions List. By default, the newly-added users have read-only access. You may want them to have read/write access, meaning each user who logs in can alter files as well as read them, so tick the Change box. You should repeat this for each user as you see fit. A powerful alternative is to set up a share at home, if you dont want to worry about being in the lab to access the shared folder. This way, you and your partners can telecommute and can exchange ideas and work without being physically present. You would just need to drop your work on the shared folder and it would be accessible by all members of your group. But this method has some issues with compatibility that need to be taken into account first. Important! Making Sure You Can Set Up a Shared Folder at Home The process for setting up a shared folder that is accessible from another connection is not necessarily easy. There are a few requirements that need to be met first. Before setting up a shared folder that can be easily accessed from home, either you need to be on the Resnet Domain, or you should have a direct connection to the internet with what is called a static IP given to you by your internet service provider. Being on Resnet automatically allows you to access your computer easily from home, but if you live off campus, and want to set up a share that you can access from outside home, you will need to make sure you have a static IP. Your IP address is essentially the identifying address that your computer uses to interact with the internet, and, as the name suggests, a static IP address is one that doesnt change. If you are not sure whether you have a static IP or its counterpart, a dynamic DHCP-based address, there is a way to check.

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o First you need to know what your IP is, if you dont already know it. There are a number of ways to go about this. One way is to hit the Start button, then click the Run button. Type in cmd and hit enter. This should bring up what is called a command prompt or a dos prompt. o At the prompt, type in ipconfig, and the result should be a listing of numbers, but the one you will need to actually take note of will be the number labeled by IP Address. Keep this prompt open. To make IP address changes from within a script, you can use Win2K's multipurpose Net Shell (Netsh) command. This command provides several functions that relate to viewing and changing IP addressing on a Win2K system. For example, to switch from DHCP to static IP, enter the following command: netsh interface ip set address "[connection name]" static [ip address] [netmask] [gateway] [metric] o Netmask is the subnet mask (e.g. 255.255.255.0) associated with the IP address, gateway is the default gateway on the command prompt, and metric is the numerical difference between the IP and the default gateway. For example, to change to the static IP address 192.168.0.4, mask 255.255.255.0, and gateway 192.168.0.1 (metric 3), you would type: netsh interface ip set address "local area connection" static 192.168.0.4 255.255.255.0 192.168.0.1 3 o If you still have access to the internet, then your ISP supplied you with a static IP but if you no longer have access to the internet, then you dont have a static IP. To switch back to DHCP-based addressing, you need to merely enter into the command prompt: netsh interface ip set address "" dhcp If you do not have Resnet or a static IP it isnt the end of the world. You have 3-4 members per group, so there is a good chance that someone in the group has a direct internet connection with a static IP.