Testing Novel Short-Cut Methods for Complex Kinetic Characterisation in Early Safety Assessment of a Chemical Process

Abstract One of the hazards of most concern in the chemical industry is the thermal hazard , which is governed by the thermodynamics and kinetics of the usually complex chemical reactions. To develop risk analysis indices the approximate knowledge of the reaction path, kinetics and thermal effects are crucial elements. While standardised tests to experimentally determine the ‘thermal stability data’ and assessment procedures for runaway reactions are developed, their interpretation is difficult to be generalised because they have been developed in the context of a specific process, and they often contain empirical as well as rationally deduced elements and rules. This paper illustrates major advantages and result improvements in thermal risk analysis when two short-cut techniques are combined: the experimental ‘Differential Scanning Calorimetry’ ( DSC ) and the numerical ‘Modified Integral Transformation Procedure’ ( MIP ). The DSC is useful in investigating the n -th order kinetics and overall thermal effect of a reaction following an elaborated strategy; attempts to fit more complex kinetics fail especially in the model discrimination step. The MIP ( Maria and Rippin, 1997 ) performs a short-cut kinetic model identification by considering previous information stored in databanks and incomplete information about the process. By coupling the DSC and MIP techniques quick identification of a (reasonable) complex chemical kinetics becomes possible. Exemplification is made for an auto-catalytic process with incomplete data by obtaining: i) a more exact evaluation of the safety index TMR ad compared with those derived from classical DSC ; ii) a more robust estimate of the kinetics by using the databank information in overcoming poor-conditioning due to incomplete data.