CHP 372 CAT2 2017 End of topic assessment of the student level of understanding. PDF

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End of topic assessment of the student level of understanding....

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CHP 372: Mass Transfer 1 CAT 2 Question one (30 marks) A distillation to separate a process stream containing 40 mole% chloroform (CHCl 3) and 60 mole% toluene is in operation. The distillate contains 92% CHCl3 and the bottoms 2% CHCl3. Data are as follows: Feed composition Feed quality Distillate composition Bottoms composition Reflux ratio Heat of vaporization of CHCl3 Heat of vaporization of C7H8

0.40 Saturated liquid XD 0.92 XB 0.02 RD 2.0 32,400 37,600

mole fraction of 1 mole fraction of CHCl3 mole fraction of CHCl3 kJ/kmol kJ/kmol

CASE I: Calculate: a) b) c) d) e) f)

The theoretical number of stages, using the attached X-Y plot; The flow rates of the top streams: D, L and V; The flow rates of the bottom streams: B, and ; The equations for the top (rectifying) and bottom (stripping) operating lines; The heat added to the reboiler at the bottom; The heat removed in the condenser at the top.

CASE II: As part of a proposed plant up-grade, the feed stream will now be available as 85% vapor with the same composition. Assuming that the distillate composition, number of stages and reflux ratio are to remain the same, discuss the difference in operation of the system with regard to the bottoms composition and the heat effects in the condenser and reboiler. The X-Y equilibrium plot is attached....