A polymer is produced by the emulsion polymerization of acrylonitrile and methyl methacrylate in a stirred vessel. The monomers and an aqueous solution of catalyst are fed to the polymerization reactor continuously. The product is withdrawn from the base of the vessel as a slurry. 

Devise a control system for this reactor, and draw up a preliminary piping and instrument diagram. The follow points need to be considered: 

1. Close control of the reactor temperature is required. 

2. The reactor runs 90 per cent full. 

3. The water and monomers are fed to the reactor separately. 

4. The emulsion is a 30 per cent mixture of monomers in water. 

5. The flow of catalyst will be small compared with the water and monomer flows. 

6. Accurate control of the catalyst flow is essential.