Question: Consider the process shown in Fig. In the reactor, the principal reaction is A + 2B → Product; two other reactions, A + B * Inert and A * Heavies, also occur but at a lesser rate. All the reactions occur in the gas phase. Enough cooling is accomplished in the cooler to condense and separate the heavies. What is left is separated in the separation column. The gases leaving the column contain A, B, and inerts. The purge is manipulated to maintain the composition of inerts in the recycle stream at some desired value, 1 mole %. In the recycle stream there is a temperature transmitter, TTl; a volumetric flow transmitter, FT3; and two continuous infrared analyzers. One of the analyzers, ATl, gives the mole fraction of A, yAR, and the other analyzer, AT2, gives the mole fraction of B, yBR. The process has been designed to have very little pressure drop between the column and the compressor. The reactants A and B are pure components and are assumed to be delivered to the valves at some constant pressure and temperature. (a) Design a control scheme to control the composition of inerts in the recycle stream at 1 mole %.

(b) Design a control scheme to control the supply pressure to the compressor. It is also very important for the process to maintain the molal ratio of B to A entering the compressor at 2.6. There is one infrared analyzer at the exit of the compressor that provides a signal indicating the mole ratio of B to A.