PROBLEM 3 (30 POINTS) A waste gas stream, flowing at 1,000 mols/hr, contains 55 mol\% DMF (dimethyiformamide - a common solvent) in air. A purification unit is avallable that can remove a fraction of the DMF in the feed to the unit. Some of the material leaving the purification unit is recycled back to the inlet. The block diagram for the process is shown below. The system is designed such that the fractional recovery in the separator, defined as the fraction of DMF fed to the separator that is recovered in stream 3 , is equal to 0.67 and the DMF content of the exit gas (stream 5 ) must be reduced to at least 10 mol\%. (a) Perform a degrees of freedom analysis for the entire process diagram. (10 points) (b) Calculate the flows (and mole fractions of air and DMF) for streams 2,3,4,5 and 6. (15 points) (c) For a more stringent DMF exit concentration in stream 5 (L.e. well below 5\%), would you expect the value of the fractional recovery to be higher, lower or remain the same. Justify your answer. (5 points)