GB1340170A - Temperature control and measurement process and apparatus - Google Patents

Abstract

1340170 Automatic control of temperature and pressure MONSANTO CO 20 April 1972 18424/72 Heading G3R The temperature in a reaction vessel is controlled in accordance with a calculated temperature signal derived from measurements of the actual temperature and pressure in the vessel. Using a signal with a pressure component enables changes in the reaction temperature to be rapidly detected and corrected. In the arrangement of Fig.1, liquid and vapour phases are present in a closed reaction vessel. The pressure of the vapour phase is continuously measured, and the resulting signal multiplied by a pressure compensation constant and added to a variable correction factor. The output from the adder circuit is compared with the actual measured temperature signal to produce an error signal which is time-integrated and divided by a time constant to form the variable correction factor. The adder output also constitutes a calculated temperature signal which is compared with the desired temperature set signal, forming an error signal which controls heat flow from the reaction vessel. The signals may be transmitted by pneumatic, hydraulic or electrical connections and the calculations and comparisons may be performed by a digital or analog computer. The temperature of the liquid phase may be measured by a thermistor bridge, and temperature control may be effected by varying flow in a cooling jacket, using a reflux condenser, or adding or removing catalysts, inhibitors, reactants or products. The system is suitable for use in controlling polymerization reactions.