"A Strategy For Thermal Hazards Analysis In Batch Chemical Manufacture

The intention of this research is to develop a testing and evaluation strategy for identification of the principal thermal hazards inherent in the batch operation of chemical processes, in conjunction with appropriate test methods and mathematical analyses of experimental data. Experimental studies of thermal decomposition reactions in single component systems are described for four unstable materials, exhibiting a range of physical and thermal characteristics. A variety of commercially available, industrial "in-house", and developed test methods were employed. The comparative sensitivity of the various methods in the detection of exothermic behaviour has been evaluated. Two experimental methods have been developed for the study of thermal decompositions: ie. The Insulated Exotherm Test allows evaluation. of initial temperature, heat generation data and pseudo-kinetic parameters describing the reaction. ii) The Decomposition Pressure Test provides data on the specific volume of gaseous decomposition products. Experimental studies of exothermic reaction in multicomponent liquid systems are described for a hazardous unit’ process’ (tojuene mononitration). This has been evaluated using industrially developed Heat Flow and Modified Dewar Calorimetry. A Power Compensated Dewar Calorimeter has been developed which provides accurate data on the magnitude and rate of heat release, and dimensional kinetic parameters, describing exothermic reaction in multicomponent liquid systems. Representative experimental studies are presented for a calibration system, hazardous unit process and kinetic study system. The effects of scale on experimental data has been considered, and is quantitatively evaluated for selected systems. A strategy is presented which is applicable to both physical and chemical processing, provides a logical framework for the implementation of appropriate test procedures, and allows consideration of additional factors such as materials contamination and operational safety margins. The application of this strategy permits selective identification of specific processing hazards, together with the test procedures by which these may be evaluated.