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Adiabatic calorimeters (ARCs) are critical in thermal analysis and thermal hazard assessment. As testing equipment continually improves, analyzing changes in physical fields in sample pools during thermal decomposition reactions is increasingly essential. Therefore, this study analyzed the thermal decomposition of tert-butyl peroxyacetate (TBPA). On the basis of the computational fluid dynamics (CFD) numerical simulation method and the kinetic model of TBPA thermal decomposition, a full-scale model of an adiabatic reactor for the thermal decomposition of TBPA was constructed. The temperature rise curve obtained after monitoring the temperature of the system during thermal decomposition was compared with that obtained during the experiment; thus, the rationality of the CFD model was verified. Accordingly, the temperature field, temperature rate, and velocity field in the reactor were analyzed. The temperature distribution of the system was relatively uniform during thermal decomposition under completely adiabatic conditions, resulting in an effectively nonexistent temperature gradient. At the same time, the self-heat rate (dT/dt) of the system in the process of thermal decomposition was analyzed. It was found that self-heat rate (dT/dt) of the system in the full sensing state was much larger than that in the experimental process, maximum self-heat rate ((dT/dt)max) reaching 15℃/min, while in the experimental process was only 1.074℃/min.

The synthesis of Grignard reagents, which are formed by the reaction of magnesium and organic halides (RX), is hazardous because of the highly exothermic nature of this reaction. In this work, calorimetry and infrared (IR) spectroscopy were used to identify the exothermic mechanism and process hazards for the synthesis of n-butylmagnesium bromide Grignard reagent (n-BuMgBr) in diethyl ether (DE), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), cyclopentylmethyl ether (CPME), and diethylene glycol butyl ether (DGBE). The latter three solvents were chosen by the substitution principle of the “inherent safety” design concept, which aims to reduce the risk of the target reaction in a fundamental manner. An EasyMax102 calorimeter was used to characterize the exothermic behavior of the reactions using isothermal and isoperibolic experiments carried out in a semi-batch glass reactor coupled with an IR probe to monitor changes in the species and concentrations during the reaction process. An adiabatic TAC-500A calorimeter was also used to understand the adiabatic decomposition behavior of the products obtained in the isothermal experiments under the worst-case (cooling failure and thermal runaway) scenario. Meanwhile, density functional theory calculations were performed to understand the reaction pathway and associated energies based on the experimental data. Further, the risk assessment of thermal runaway was analyzed using a risk matrix and a Stoessel criticality diagram. The results indicate that the risk of the reactions when using 2-MeTHF, CPME, and DGBE are all class 1, making reactions in these solvents inherently safer than those using DE or THF, which were both class-3 risks. These findings provide further evidence that 2-MeTHF, CPME, and DGBE are safer than the typical solvents used for the industrial production of Grignard reagents.

We attempted to prevent the thermal risk of a runaway reaction of polymerization in a batch reactor and to realize online monitoring and emergency inhibition of the thermal runaway behavior. Styrene thermal initiation of bulk polymerization was studied. A full-size model of the styrene polymerization reactor was constructed by referring to the reactor model of the Mettler Toledo automatic calorimeter, which was combined with the kinetic and thermodynamic models of styrene polymerization. The DIV thermal runaway critical criterion based on chaos divergence theory was used to judge the thermal runaway reaction. The critical point of the runaway reaction was determined and used to inhibit the thermal runaway of styrene polymerization by injecting cooling diluents at the liquid surface. The influence of injection rate ( v c = 0.5 、 0.8 、 1 m / s ), injection position (in-1、in-2、in-3), and amount of cooling diluents (no add、50 %、70 %、100 %) injected on the thermal runaway inhibition of the reaction was investigated and elucidated. The results indicated that a better inhibiting effect can be obtained by injecting the inhibitors at higher rates near the edge of the paddle blade. Moreover, appropriately increasing the injection amount of the inhibitors can achieve better inhibition of the runaway reaction.

Three-phase foam, namely surfactant-particle stabilized foam is a promising material in pool fire extinguishment. However, its effectiveness has not been validated. In this study, a research-scale three-phase jet foam generator, which allowed adjustments of foam slurry composition, nozzle type, air flow rate and screen aperture, was developed. In order to optimize the foaming condition, a three-factor three-level Box–Behnken design (BBD) was adopted. Fly ash (FA) particles were used as the solid phase to generate three-phase foams. As a result, the FA supported foam exhibited better stability over conventional fire-fighting foam, especially when the particle concentration exceeded a threshold value. In addition, the BBD results presented a good agreement between experimental data and fitted models. The optimal foaming condition was determined by numerical optimization. Small-scale fire extinguishing experiments were carried out and three-phase foam manifested better burnback performance compared to conventional fire-fighting foam. The design in this work can be used to study the firefighting efficiency of different three-phase foams and serve as a prototype to develop better generators for both lab research and practical application.

The modified Stoessel criticality diagram was present in this research. The final temperature under adiabatic condition was considered for thermal hazard assessment. We reported the systematic thermal hazard assessment of synthesis of tert-butyl peracetate, preparation of hydroxylamine and synthesis of 2,6-diethyl-4-methylPhenylpropanamide and discussed their classification according to the modified Stoessel criticality diagram. The process temperature, maximum temperature of synthesis reaction, maximum temperature for technical reasons, temperature at which TMRad is 24 h and the final temperature under adiabatic condition(Tp, MTSR, MTT, TD24, Tf) were obtained by experiments and calculation. The evaluation results by the modified Stoessel criticality are more rational and conforms to reality.

Thermal runaway is a hazardous problem frequently occurring in the chemical productions. An effective way to avoid accidents caused by thermal runaway is preliminary hazard analysis which can help determine the comparatively safe operating condition in the design phase. In this paper, a series of batch reactor thermal runaway scenarios based on esterification of isopropyl propionate has been studied and according to mixing law the optimal inhibitor injection location has been confirmed. The reactor model is established by computational fluid dynamics (CFD) technology and verified by RC1e test. The effect of cooling temperature, cooling velocity and stirring speed are investigated in detail. Based on the failure status analyses, the appropriate location of temperature probe was then determined by the divergence (DIV) criterion. Finally, the inhibitory mixing performances were evaluated by a global mixing criterion. The results indicated the mixing time and inhibitory region were greatly influenced by the injection location.

Leakage in pressurized pipelines is a serious problem in petrochemical plants because it might cause a fire or an explosion. The negative pressure wave (NPW) method is a practical method of locating leaks in a pipeline, and it has been used widely in the energy distribution industry. However, it is difficult to obtain the pressure wave velocity accurately and to localize leakage by using NPW method because of the complexity of real pipeline components, especially in assembled pipeline. Thus, in this study, the influence of assembly rubber washer on pressure wave velocity is analyzed; in addition, considering the effect of the rubber washer, a numerical method for calculating the velocity of pressure wave propagation in liquid pipelines is proposed. Then, the propagation velocity of NPWs is measured experimentally to verify the feasibility of the improved method on a self-made pipeline leak detection test platform. The results show that the presence of rubber washers in an assembled pipeline decreases the propagation velocity of NPWs and that the correction model established in this study can adequately modify the propagation velocity of NPWs. The improved method containing the modified formula can improve the accuracy of leak localization for assembled pressurized liquid pipelines.

The effect of one obstacle on the explosion intensity of a methane–air mixture in connected vessels was studied. The experimental results suggested that the blockage ratio and the position of obstacles played a great role in this intensity. The obstacles could increase the reaction speed. When the blockage ratio reaches a certain value, the disturbance effect on the flame is at its highest, and the turbulence intensity and explosion intensity are at their strongest. If the obstacle’s blockage ratio is greater than or less than this value, the explosion intensity is weaker. If the obstacles are closer to the initiating container, the combustion pressure will rise earlier both in the initiating container and in the connecting pipe. However, the effect of the obstacle position on the peak combustion pressure is limited. The conclusions provided an important reference for the safety design of explosion venting and explosion resistance.