Aspen Plus Reaction Kinetics
Nayra Waddles
This simulation uses AspenPlus to model the plug flow reactordesign created in the Matlab program plugr1, which simulates aplug flow reactor. Although a detaileddescription of building an Aspen model may be found elsewhere,this section briefly covers building a model of a reactor inAspen.
After the flowsheet is complete, it is time to specify the model.On the "Setup.Main" page, we let Aspen know that we would like toview the products as both mole flows and mole fractions. The"Components" window for this setup should look like this.
For the property set, choose ideal since the Matlab model of thisreactor is based on ideal thermodynamics. When specifying the feedstream to the reactor, fill in your window such that it resemblesthis one. Keep in mind that these are the same conditions that may befound in the feed stream of the Matlab plug flow model.
The next page of importance to appear is the "Rplug.Main" page.Note the section on this page entitled "Reactions." Since we aregoing to specify the reactions and the kinetics of the reactions thatare going to occur in the reactor, we need to create a database onthese reactions before we complete the "Rplug.Main" page. The firstthing we have to do, though, is determine the kinetics of thesystem.
Using kinetics, the following two rate equations may be written.Keep in mind that the first equation applies to the forward-onlymethane reaction, while the second equation incorporates both theforward and reverse reactions of the water-gas shift reaction.
Once this has been determined, we need to make sure that thecorrect units are being employed. When using powerlaw equations inAspen, the units used for the equation as a whole are based on theunits used in the concentration variables. One of the choices Aspenhas is molarity, which allows us to use kgmol/m3. To getk1 in the right units, we must do the following.
Now that we have determined the reaction rate equation for thefirst reaction, we need to do the same for the second and thirdreactions. The second reaction is the forward reaction of thewater-gas shift.
The next thing to do is enter the reaction data. Double click onthe "Reactions" folder in the input section of the Flow Sheet window.The menu now present should have "Chemistry" and "Reactions." Clickon "Reactions" to bring up a window where you can enter informationabout the reactions. Click on the "New" button in that window.
By selecting "New" we are telling Aspen that we want to define aset of reactions that is going to take place in one of the units inthe model. From the "Object Type" menu that just appeared, select"Powerlaw." Next, name your reaction set in the "Create" window thatjust appeared. This example will use the default name, "R-1." We canthen edit the reaction window for the first reaction to make it looklike.
Notice that the reactor diameter is different from the reactordiameter in the Matlab example. In the Matlab example, the porosity(phi) is 0.48. To account for the porosity, we use the followingrelation:
We are now ready to execute the system. To dothis, first "View" the Control Panel and execute with the "Run"button under the "Run" menu.. When Aspen has finished thecalculations, pull up the results under the Data menu: ResultsSummary: Streams to see:
To allow you to see how the results compare, the following graphcompares the mole fraction of water in both systems. The dotted blueline represents the Matlab data while the solid red line correspondsto the Aspen data.
I am trying to compile USER2 block subroutines for describing reaction kinetic in Aspen PlusI had install visual studio 12/2013 and Intel Fortran compiler 2013SP1 for working with Aspen Plus10..........the file is also compiled in aspen simulation engine using aspcomp, asplink to create the dynamic link library without any error encountered. However, when I run the simulation, the calculation aborts with this error :
What you are asking for is impossible. You may have built a DLL using source code that you have not shared with us, built by an agent (Aspen Plus) using scripts that are unknown to us, and something went wrong. The possibilities as to what went wrong are too numerous to ponder.
If there is a forum reader (FortranFan?) who uses Aspen Plus, that user may respond. Otherwise, please take the matter up with the makers of Aspen Plus and their user support groups. You may need to provide full details of the build process, including log/message files such as _2249hqg.ld .
If I read what she wrote correctly, the DLL was built with no linker errors, but the ASPEN PLUS software is trying to do a DllLoad/GetProcAddress for some routine named TGREACT and didn't find it. I assume that this routine is supposed to be in the Fortran code. If so, Geetanjali should make sure that there is a:
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In the field of chemical engineering, process design plays a crucial role in developing efficient and cost-effective manufacturing processes. With advancements in technology, software tools have become indispensable in this process. Two popular software solutions used in process design are Aspen Hysys and Aspen Plus. These powerful tools offer a wide range of advantages that help engineers streamline their design process, optimize operations, and enhance overall efficiency. In this article, we will explore the advantages of using Aspen Hysys and Aspen Plus software in process design, discuss their differences, highlight their major advantages and disadvantages in the chemical industry, and briefly describe other notable software options for process design in the chemical processing industry.
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Aspen Hysys is primarily used for steady-state process simulation and is well-suited for conceptual design and optimization studies. It excels in analyzing and optimizing large-scale, continuous processes with a high degree of complexity. On the other hand, Aspen Plus is specifically designed for dynamic and rigorous process simulation. It offers more advanced features for detailed modeling of chemical reactions, phase equilibrium calculations, and comprehensive heat and mass balance analysis. Aspen Plus is commonly employed in the design and optimization of batch processes and processes involving complex chemical reactions.
Aspen Hysys has a more user-friendly and intuitive interface compared to Aspen Plus. It provides a graphical drag-and-drop environment that simplifies the process of building and manipulating process flow diagrams. Aspen Plus, while more powerful in terms of modeling capabilities, has a steeper learning curve due to its complex user interface and extensive options. Engineers with less experience in process simulation may find Aspen Hysys more accessible, whereas those seeking advanced modeling capabilities may prefer Aspen Plus.
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