Problem 1 [15 marks]
A gas mixture containing 90 mol% acetone and 10 mol% nitrogen is to be processed to recover
the acetone in a two-step absorption-distillation system. In the first step, 1000 kmol/h of the feed
mixture enters an absorption column, where 95% of the entering acetone is recovered into
500 kmol/h of liquid methyl-isobutyl-ketone (MIBK). The nitrogen can be assumed to be
insoluble in the MIBK stream, but 2% of the entering MIBK is lost to the gas stream leaving the
absorber. In the second step of the process, the liquid stream leaving the absorber is sent to a
distillation column. This column produces a distillate stream containing 98 mol% acetone and a
bottoms stream containing 99 mol% MIBK.
a) Draw a labelled block flow diagram for the separation process.
b) Calculate the total flow rate and composition of each stream in the system. Also
determine the overall recovery of acetone in the system.
