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Unformatted text preview: Homework 2 Problem 2 SuperPro Designer™ Soybean Biodiesel
30 points possible due Friday September 9, 2011 Grader: Israel Problem Statement: Soybean oil can be converted biodiesel and used to produce renewable energy. After extracting the oil from the soybean, the oil is reacted with methanol to produce biodiesel and glycerin according to the following reaction: 3 MeOH + Soybean Oil → 3 Biodiesel + Glycerin A mixture of 736 kg methanol, 11.94 kg NaOCH3, and 0.08 kg water at 42.3oC and 64.7 psi is reacted with 4,247 kg of soybean oil at 60oC and 64.7 psi. the reactor will operate under adiabatic thermal conditions and will use steam as the heat transfer agent. The agitator will use 1.4 kW/m3 power. Under these conditions, the reaction will reach 83% conversion with respect to soybean oil. The reaction products are sent to a centrifuge to separate 99.99% of the biodiesel and soybean oil from the remaining methanol and glycerin. The centrifuge removes oil and fats from the product and will consume 18.9 kW of power. Useful Information: 1. The soybean oil used in this reaction has a molecular weight of 885.45 and a vapor pressure of 4.7 bar. 2. The biodiesel has a molecular weight of weight of 296.5 g/mol with a normal boiling point of 344oC, a critical temperature of 491oC, a critical pressure of 12.63 bar, and a liquid density of 874 g/L. 3. NaOCH3 has a molecular weight of 54.02 g/mol with a liquid density of 2,043 g/L, the normal boiling point is 68oC, critical temperature 234oC, and the critical pressure is 26.69 bar. Method of Solution: Use the SuperPro Designer to simulate the batch process. Solution: 1) Open the SuperPro DesignerTM program. 2) Select “Batch Mode” and click OK. Page 1 of 13 3) To register the process components select Tasks → Pure Components →
Register, Edit/View Properties… from the toolbar. 4) Type methanol in the source box, highlight the appropriate component, and click the Register button in the center of the edit window. 5) Next, add soybean oil to the component box. The following error may appear stating that the vapor pressure is missing. Click OK to continue. Page 2 of 13 Change the molecular weight to 885.45 and the vapor pressure to 4.7 bar by highlighting soybean oil and click the View/Edit the Selected Component Properties button, , in the upper right hand corner of the component box. Enter the correct molecular weight and vapor pressure of soybean oil under the Physical (Constant) tab. Click OK to save and close. 6) Add the final pure component glycerin (glycerol) to the component box. 7) Note: If you add a component by mistake, click on the component number and delete the selection by clicking the delete button in the upper right hand corner of the Registered Pure Components box. 8) Components that are not found in the SuperPro DesignerTM databank must be added into the simulation by the user and are therefore considered user define components. To enter a user defined component, click the Add a New Component button , which is in the upper right hand corner of the Registered Pure Components box. Do so now to add in diesel. Page 3 of 13 The New Component Definition window will appear. Type in the component name Diesel, which will automatically fill in the subsequent naming regions of this window, click OK. 9) Highlight diesel and click the View/Edit the Selected Component Properties button . Under the Physical (Constant) tab, enter a molecular weight of 296.5 g/mol with a normal boiling point of 344oC, a critical temperature of 491oC, and a critical pressure of 12.63 bar. 10) Diesel has a liquid density of 874 g/L. under the Physical (T‐dependant) tab enter a=874 and b=0. Page 4 of 13 Click OK to save the changes and close the window. 11) Repeat steps 8 and 10 for NaOCH3, which has a molecular weight of 54.02 g/mol with a liquid density of 2,043 g/L. The normal boiling point is 68oC, critical temperature 234oC, and a critical pressure of 26.69 bar. Page 5 of 13 Click OK to save and close the NaOCH3 properties window. 12) Click OK to close the Register/Edit Pure Components window. All of the process components have been added close the stock mixture window and return to the flowsheet. Save the worksheet before moving forward. 13) Add a continuous reactor to the flowsheet by selecting Unit Procedure → Continuous Reaction → Stoichiometric → in a CSTR from the toolbar menu. 14) After the reactor, add a decanter centrifuge to the flowsheet by selecting Unit Procedure → Centrifugation → Decanter from the toolbar. Page 6 of 13 15) Add 2 feed streams to the reactor by clicking the Connect Mode button, . Connect the reactor product stream to the centrifuge feed. Finally, add 2 product streams to the centrifuge. The process flow diagram should now look like the one shown below: 16) Double click the S‐101 stream line. Add 736 kg of methanol, 11.94 kg of NaOCH3, and 0.08 kg of water to the component box. This stream enters the reactor at a temperature of 42.3oC and a pressure of 64.7 psi. Click OK to exit. Page 7 of 13 17) Open the S‐102 feed stream and add 4,247 kg of soybean oil at 60oC and 64.7 psi. Click OK to save and close. 18) Right click on the vessel reactor and select Operation Data… Page 8 of 13 19) Under the Oper.Cond’s tab select the adiabatic thermal mode and steam for the heat transfer agent. The agitator requires 1.4 kW/m3 power. 20) Open the Reactions tab; enter the reaction extent given in the problem statement as 83.6% in reference to soybean oil. Page 9 of 13 21) Click on the Edit Stoichiometry button, , to add the reaction. Select molar stoichiometric coefficients and add 3 moles of methanol and 1 mole of soybean oil as the reactants from the drop down menu by clicking the . Repeat to add 3 moles of diesel and 1 Add a Reactant button, mole of glycerin as the products. Click OK to save the change and close the window. 22) The reactor is fully defined click OK to save the changes and close the window. Page 10 of 13 23) Open the centrifuge Operating Data… page by right clicking the centrifuge. On the Oper. Cond’s tab, select Oil/Fat Removal and keep all other default values the same. 24) Open the Mat. Balance tab and enter the oil concentration of 850 g/L near the bottom. This centrifuge will be used to separate 99.99% of the diesel and soybean oil from the remaining components. 25) Finally, open the Utilities tab, check the set power consumption radio box, and enter the power 18.9 kW. Page 11 of 13 26) The process has been fully defined. Save the file. 27) Click Task → Solve M&E Balances or click the button to run the process. 28) Open the product stream S‐104 to check the simulation results. You should have the following compositions. 29) Select Reports → Stream & Mat. Balances from the toolbar to view the full report of the process results. Page 12 of 13 Results/Considerations: SuperPro DesignerTM calculated a cycle time of 4 hours per batch. This process produced almost 3,567 kg of biodiesel from 4,247 kg of soybean oil. The centrifuge diesel product stream contains trace (>2%) components and ~16% soybean oil. This stream can be run through the reaction process a second time to react the remaining soybean oil. It will also be purified downstream to remove any remaining components from the final diesel product. Page 13 of 13 ...
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- Fall '11