Tutorial 4

Tutorial 4 - 2 and 21 mol% O 2 . 2. Lactic acid (CH 3...

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CHBE 241 Material and Energy Balances Department of Chemical and Biological Engineering The University of British Columbia Tutorial 4 Wednesday, 5 November 2008, HENN 200, 3–5pm 1. A synthetic fiber plant uses a variety of volatile solvents. An analysis of waste solvent vapours showed that the gas contained 20 mol% CH 4 , 20 mol% CS 2 , 10 mol% SO 2 and 50 mol% H 2 O. It has been proposed that the gas be combusted and then emitted to the air. Two combustion reactions are CH 4 + 2O 2 CO 2 + 2H 2 O CS 2 + 3O 2 CO 2 + 2SO 2 Local air pollution regulations limit the SO 2 concentration in stack gases to no more than 2 mol% on a dry basis. What is the minimum percent excess oxygen that must be used to meet these requirements, assuming complete combustion? What is the composition of the combustion gases? The waste solvent vapours stream flow rate is 100 mol/min. Assume air contains 79 mol% N
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Unformatted text preview: 2 and 21 mol% O 2 . 2. Lactic acid (CH 3 CHOHCOOH) reacts with hydrogen to give 1,2-propanediol (CH 3 CHOHCH 2 OH) and water. The reaction, which takes place in the gas phase, is: CH 3 CHOHCOOH + 2H 2 = CH 3 CHOHCH 2 OH + H 2 O The reactor feed rate is 50 mol/h lactic acid, 150 mol/h H 2 , and 100 mol/h of an inert. The reactor pressure is 5 atm and at the reactor temperature, K a = 3 . 2atm-1 . (a) What is the fractional conversion of lactic acid if the reactor outlet is at equilibrium? (b) If you want to increase the fractional conversion of lactic acid at equilibrium would you recommend increasing or decreasing the reactor pressure? (c) If you decreased the inert feed rate, would the fractional conversion at equilibrium increase, decrease, or remain unchanged? 1...
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