Fresh halibut livers containing 25.7% oil are to be extracted with pure ethyl ether to remove 95% of the oil in a counter current multistage leaching process. The feed rate is 1000 kg of fresh livers per hour. The final exit overflow solution is to contain 70wt% oil. The retention of solution by inert solids (oil-free liver) of the liver varies as follows, where N is kg inert (solid/kg) solution retained and yA is kg oil/kg solution.
N y
4.88 0
3.50 0.2
2.47 0.4
1.67 0.6
1.39 0.81
Calculate the amounts and compositions of the exit streams and the total number of theoretical stages.