Homework 3 Problem 4 Aspen Multicompress

Homework 3 Problem - Homework 3 Problem 4 Aspen Plus™ Two-St age Compression with Intercooler 20 points possible due Friday Grader Alan Problem

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Unformatted text preview: Homework 3 Problem 4 Aspen Plus™ Two-St age Compression with Intercooler 20 points possible due Friday September 16, 2011 Grader: Alan , Problem Statement: Use a process simulator to model a two‐stage co mpression system with an intercooler. A feed stream consisting of 95 mol% hydrogen and 5 mol% methane at 100°F and 30 psia with a flow rate of 440 lbmo l/hr is compressed to 569 psia. o The outlet temperature of the intercooler is 100° F a with pressure drop of 2 psia. The centrifugal compressors have an isentropic efficiency of 0.9 and a mechanical efficiency of 0.98. Determine the power requirements and heat rem oved for three intermediate pressures (outlet from the first three stages): 100 , 130, and 160 psia. If using ASPEN PLUS, use the MCOMPR subroutine and the RK‐SO OAVE option. Method of Solution: Use the MCompr unit in AspenPlus to find the p ower and heat removed for the intermediate pressures. Solution: 1) Start the Aspen Plus™ program: All Program s/AspenTe ech/Process Modeling v7.2/Aspen Plus/Aspen Plus User Interface 2) Select “Blank Simulation” and click OK. 3) Eventually, the Process Flowsheet Window sho uld appear. 4) Add a MCOMPR subunit to the flowsheet fro the Pressure Changers tab om e and connect material streams to the feed and product streams of the unit. Page 1 of 8 5) Open the Data Browser by clicking on the icon on the toolbar. First, add the system components. Click on the Compo nents section of the Data Browser. 6) On the Selection tab click Find. The Find window will appear. Type “methane” and click Find now. Select METHANE and click Add. Add the d remaining process component and close the window. ose Note: If you add a component by mistake, clo the Find window, right‐click on the row to delete and select delete row fro m the drop down menu. 7) Next, specify the property package that Aspe n PlusTM will use to define the system. Open the Properties section by click ing on the folder. Click on Specifications. 8) On the Global tab, select All as the process ty pe and then select RK‐SOAVE as the base method. Page 2 of 8 9) Expand the Parameters and Binary Interactions sections and click on RKSKBV‐1, which will automatically change the radio box to a blue check mark signaling that the input is complete for this section. 10) To define the feed stream, double click on Str ream 1. The data browser should open. Under the Specifications tab, set the temperature to 100°F, the r pressure 30 psia, and a total flow of 440 lbmo l/hr. Change the Composition units to Mole‐Frac and enter the feed composition 5% methane, 95% hydrogen. Page 3 of 8 11) To define the compressor, double click on Bl ocks, B1, and Setup. 12) Under the Configuration tab enter 2 for the N umber of stages and select the Isentropic Compressor model. Also select Fix discharge conditions from each stage under Specification type. 13) With the Specs tab selected, create two colum ns for stages one and two. Select the Specification as the Disch Pres in order to define the intermediate pressure of 100, 130 or 160 psia and the final pressure of 569 psia from stage two. Enter Page 4 of 8 the Isentropic and Mechanical Efficiencies fo r each stage as stated in the problem. The Specs tab should now be comp lete. 14) Under the Cooler tab at Stage 1, specify the O utlet Temp and Pressure drop 15) The simulation is now complete. Press F5 or to run. Save the file. 16) To check the simulation results click on the B locks folder, B1, and Results. The power requirements and heat removed a t the intermediate stage can be found under the Profile and Coolers tabs. Page 5 of 8 17) Save the file under a new name to compare a nswers. 18) Change the first stage discharge pressure fro m 100 to 130 psia under the Blocks/Setup/Specs folders. 19) Click the reinitialize button, , to clear the previous results. Rerun the simulation. Compare the results to the previo us run. Page 6 of 8 20) Repeat steps 17‐19 for a discharge pressure o f 160 psia. Page 7 of 8 21) Compare the results. Page 8 of 8 ...
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This note was uploaded on 11/14/2011 for the course CHEN 4520 at Colorado.

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