Seminar 5 (Spring-Summer 2019) with solutions.pdf -...

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DEPARTMENT OF CHEMICAL & MATERIALS ENGINEERING Seminar 5 June 12 th 2019 ChE 316 Equilibrium Stage Processes Spring 2019 1 Q1. Trays for a known Murphree efficiency A 50 mol% mixture of acetone in isopropanol is to be distilled to produce a distillate of 80 mol% acetone and a bottoms of 25 mol%. The feed is a saturated liquid, the column is operated with a reflux ratio of 0.5, and the Murphree vapor efficiency is 50%. How many actual stages are required? Assume a total condenser, partial reboiler, saturated-liquid reflux, and optimal feed stage. The vapor-liquid equilibrium data are: Liquid 0 2.6 5.4 11.7 20.7 29.7 34.1 44.0 52.0 63.9 74.6 80.3 86.5 90.2 92.5 95.7 100.0 Vapor 0 8.9 17.4 31.5 45.6 55.7 60.1 68.7 74.3 81.5 87.0 89.4 92.3 94.2 95.5 97.4 100.0 Q2. Open steam using McCabe Thiele method A distillation column is separating 1000 mol/h of a 32 mol% ethanol, 68 mol% water mixture. The feed enters as a sub-cooled liquid that will condense 1 mole of vapour on the feed plate for every 4 moles of feed. The column has a partial condenser and uses open steam heating. We desire a distillate product y D =0.75 and a bottoms product of x B = 0.10. Constant molal overflow is valid. The steam used is pure saturated vapour. The y-x diagram is enclosed. (a) Draw the sketch of the column (b) Find the minimum external reflux ratio. (c) Use L/D = 2.0(L/D) min , and find the number of stages and the optimum feed location. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y x Ethanol - water Equilibrium data at 1 atm (y-x in mole fraction of ethanol)
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