ABSTRACT
Polymerization processes in the chemical industry require careful temperature control, and are often carried out in jacketed kettles6 as in Fig. 4-6. The kettle is loaded with monomer, catalyst, and water, and is initially heated to start the reaction. A constant desired temperature is maintained by proportioning the flow rates of steam and cold water to the kettle jacket. This temperature control becomes particularly difficult when the reaction becomes exothermic (producing heat rather than requiring heat addition), because this situation is inherently unstable; more heat produces higher temperature, which causes a faster reaction, which produces more heat, etc. The control system stabilizes this process by providing just the right amount of cooling to maintain an essentially constant temperature, as desired.
