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Unformatted text preview: Homework 4 Problem 1 Aspen Plus™ Water-Gas-Shift
20 points possible due Tuesday September 27, 2011 Grader: Israel Problem Statement: The water‐gas shift reaction produces hydrogen gas and carbon dioxide by reacting carbon monoxide and water according to the balanced reaction: CO + H2O CO2 + H2 The water‐gas shift reaction is important for a number of chemical processes where the relative amounts of CO, CO2, and H2 need to be adjusted or shifted. Suppose the feed to a reactor contains 1.00 mole CO, 2.00 moles of H2O, and no CO2 or H2. The reaction mixture comes to equilibrium at 1105 K, where the equilibrium constant, K (T) = 1.0. Calculate the equilibrium composition. Method of Solution: Use the Equilibrium Reactor Operation in Aspen PlusTM with an equilibrium reaction to solve the system. Solution: 1) Open the AspenTM program and start a new case. 2) Add an equilibrium reactor from the Reactors heading to the flowsheet and connect 3 material streams to the feed and product streams of the unit as shown below: Rename the process streams by right clicking the stream and select Rename Stream. Enter the new name in the popup window and click OK to save. This problem is based on Felder and Rousseau’s Elementary Principles of Chemical Processes 1Example 4.6‐2 3) Open the Data Browser by clicking on the icon on the toolbar. First, add the system components. Click on the Components section of the Data Browser. Under the Selection section click Find. The Find window will appear. Type “water” and click Find now. Select WATER and click Add. Now add carbon monoxide, carbon dioxide, and hydrogen in the same fashion. Close the Find window. Note: If you add a component by mistake, right‐click on the row to delete and select delete row from the drop down menu. 4) The components can be renamed by clicking in the Component ID box, type the new name, click <Enter>, and the click the Rename button. Rename the components H2O, CO, CO2, and H2. 5) Open the Properties section by clicking on the folder. Click on Specifications. On the Global tab, under Base method, select Peng‐Robinson. This problem is based on Felder and Rousseau’s Elementary Principles of Chemical Processes 1Example 4.6‐2 button to automatically fill in the missing binary interaction Click the next parameters. 6) Open the feed stream and enter the operating temperature, pressure, and component flowrates. 7) Open the Blocks, B1, and Input Specifications folders. Enter the reactor operating pressure, 101.3 kPa, and temperature, 1105 K. This problem is based on Felder and Rousseau’s Elementary Principles of Chemical Processes 1Example 4.6‐2 8) Open the Reactions tab and click the new button to add a new reaction to the block. Select carbon monoxide and water from the reactants drop down menus with stoichiometric coefficients of ‐1. Select carbon dioxide and hydrogen as the products with stoichiometric coefficients of 1. The temperature approach radio button should be selected as the products generation method. Close the reaction window. 9) The system has been fully defined. Press F5 or click the run button to run the simulation. 10) Open the Results Summary Streams to view the default stream results. Felder & Rousseau report the mole fraction results, which are not shown under the default stream results. Open the Setup Specifications folder and change the Units of measurement to scientific (SI). This problem is based on Felder and Rousseau’s Elementary Principles of Chemical Processes 1Example 4.6‐2 Next open the Setup Report Options folder and the Streams tab. Check the mole fractions radio box to report the stream mole fractions. to reset the simulation. Two popup windows will
Click the reinitiate button
appear, click OK on both windows to reinitialize. This problem is based on Felder and Rousseau’s Elementary Principles of Chemical Processes 1Example 4.6‐2 Rerun the simulation and check the results under the Results Summary Stream folder. Results/Considerations: The composition of the vapor in the Composition Workbook Table displays the equilibrium composition, the solution to the problem statement. Comparing the simulation results to the Felder & Rousseau example solution: H2O
CO CO2 H2 F&R Aspen
0.444 0.446 0.111 0.112 0.222 0.221 0.222 0.221 Also, note that no liquid flow is generated. This problem is based on Felder and Rousseau’s Elementary Principles of Chemical Processes 1Example 4.6‐2 ...
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This note was uploaded on 11/14/2011 for the course CHEN 4520 at Colorado.