Thermal hazard evaluation of styrene polymerization by accelerating rate calorimetry

Abstract

The thermal polymerization of inhibited styrene monomer is investigated by Accelerating Rate Calorimetry (ARC). The time-temperature-pressure data generated by this technique are utilized in evaluating the thermal hazards associated with the industrial processing of styrene monomer. Several examples are given on the interpretation and application of ARC data to environments ranging from lab to plant-scale conditions including discussions concerning the similarities and dissimilarities between the ARC and large-scale equipment. The polymerization of styrene monomer is also used to evaluate the performance of the ARC over a broad temperature range, 80-300 ~ The data indicate that removal of the radiant heater assembly yields better agreement between the heat of polymerization of styrene as measured by the ARC and corresponding values from the literature. This effect is believed to be observable only under conditions of low reaction rates for long periods of time such as in the case of styrene monomer.The evaluation of thermal and pressure hazards associated with the manufacture, transport, and storage of chemicals is an important area of research in the chemical industry. The engineering design of equipment to prevent, control or withstand runaway reactions which result in pressure increase is of great concern from a safety and loss point of view. In order to design a piece of equipment which will operate safely during an emergency situation, it is necessary to have data on the kinetics, thermodynamics, and physical properties of the potential runaway reaction.Several approaches have been utilized in the past to obtain information on the kinetics of exothermic reactions. One of the most commonly used techniques in thermal hazard evaluation is differential scanning calorimetry (DSC) which can yield both the heat of reaction and the kinetics of the reaction of interest [1 ]. A modification of the sample container used in DSC has been developed to handle volatile chemicals or materials which generate gaseous products on decomposition, conditions which are common in the chemical industry [2]. However, one limitation to the DSC methods for hazard evaluation is the difference in experimental conditions compared to normal operating conditions in a chemical plant. DSC data are obtained at a fixed heating rate which forces the reaction to occur at higher temperatures in the DSC than would be experienced during processing or storage. As a result, the experimental data often must be extrapolated to normal

Probing into Styrene Polymerization Runaway Hazards: Effects of the Monomer Mass Fraction

“…This multipeak exothermic curve denoted a complex reaction pathway of thermal polymerization of styrene and had been observed in many other studies. 15,18 Liao 7 reported similar peak behavior for TBC inhibited styrene and performed kinetic modeling on each peak. It was identified that the first peak was typical of an autocatalytic behavior while the second peak was an n th order regarding styrene with a reaction order around 1.8–2.…”

“…A considerable amount of the literature has been published on the assessment of the thermal hazards of the undesirable thermally initiated styrene polymerization using calorimeters. Whiting and Tou 15 evaluated the thermal behavior of inhibited styrene in an accelerating rate calorimeter (ARC) to address the effects of the system thermal inertia. Gibson et al 16 tested the runaway reaction of inhibited styrene starting from 150 °C in an adiabatic Dewar and calculated the relief valve size.…”

Influence of organic acid on the thermal behavior of dimethyl sulfoxide

“…It can measure self-heat rate, pressure, and pressure rate in the adiabatic condition, which is the worst case to analyze and assess thermal hazards [21,22]. In this study, ARC (TIAX) was used to analyze the influence of organic acid on the thermal behavior of DMSO.…”

A modified accelerating rate calorimeter (ARC®) with capabilities for handling gaseous samples under vacuum or an inert atmosphere

“…The original ARC 1 used here is an ARC 1 2000 TM from Arthur D. Little, Inc. Since the details of the design, operation and performance of the ARC 1 have been published [1][2][3][4], and are clearly described in the instrument manual [5], only a description of the instrumental modifications will be given here. The tubing used here is 1/8 in.…”