Comparison of different methods for estimating TMRad from dynamic DSC measurements with ADT 24 values obtained from adiabatic Dewar experiments

Abstract

Recently, a method for estimating the time to maximum rate under adiabatic conditions (TMRad) from non-isothermal DSC measurements was presented by Keller, A., Stark, D., Fierz, H., Heinzle, E., & Hungerbühler, K. (1997). J. Loss. Prev. Process. Ind., 10, 31–41. The method was tested on the basis of isoperibolic data only, because data from adiabatic experiments were not available. In this study we used results from 180 Dewar vessel experiments with an adiabatic shield and the corresponding dynamic DSC measurements provided by Aventis Research and Technologies (former Hoechst AG) to test the estimation method suggested. The data were obtained for reaction mixtures, bottom residuals, reaction residuals, and products. We found that in all cases the predicted TMRad at a given temperature was shorter than the experimental value determined from adiabatic measurements. This result shows that the TMRad estimation method is useful as a screening tool for the assessment of thermal risk. Furthermore, the estimation method introduced by Keller et al., is more on the safe side than other common and often applied estimation methods like the so-called 100 degree rule or the 50 degree rule. We also describe how to derive adiabatic induction times for different temperatures by using a minimum number of adiabatic experiments.