Reaction inhibition in the control of exothermic runaway

A research programme has been undertaken into the use of chemical inhibition techniques as a basis of safety for the control of exothermic runaway reaction hazards. The principal element of the research has been the design and running of a series of pilot scale trials at the Health and Safety Laboratories into the inhibition of an uncontrolled styrene monomer polymerisation with associated laboratory and analytical work to plan the tests safely. Pilot scale experiments on the uncontrolled polymerisation of styrene have demonstrated the effectiveness of the injection of the inhibitor para tertiary butyl catechol at two different agitation speeds and under conditions immediately following agitation failure. Modelling of the experiments using a network-of-zones approach has shown some inadequacies with the reproduction of the pilot scale data, notably in the inability to simulate the jet mixing effects that dominate in small scale plant with the conditions employed. The present modelling results do, however, underpredict the mixing efficiency, thereby leading to a more conservative design for the cases studied.