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Due to the complex effects of combined loadings on complete steel structures, the combined effects of high-velocity projectile impact and heat radiation due to a pool-fire on a vertical Q345 steel tank have not been generally considered. In this study, a consecutive coupling approach is established. The combined effects of projectile perforation and heat radiation on the failure modes and fire resistance of a vertical steel tank are investigated. Additionally, the effects of the projectile size, projectile shape, and separation distance are analyzed. The results indicate that compared with a fixed-roof tank without impact, the perforation results in stress concentrations in the plastic deformation zone. The stress level of the perforated tank is higher, and the fire resistance of the perforated tank is lower. Additionally, as the perforation size increases, the stress level triggering the thermal buckling of the perforated tank decreases outside of the plastic deformation zone. Additionally, the fire resistance decreases. Moreover, as the separation distance decreases, the stress level of the cylindrical shell increases. The fire resistance of the perforated tank decreases dramatically. By understanding the failure mode, this study is able to suggest fire and explosion protection measures in petrochemical industries to decrease or eliminate the domino effect risk and incident damage. Additionally, the fire resistance data can help improve guidelines and understanding for fire and rescue services, which would undoubtedly play a vital part in emergency response and rescue, and enhance the process safety level overall.

Knowledge of flammability limits values, including both the lower flammability limit (LFL) and upper flammability limit (UFL), is essential to maximise safety in process design and operational procedures. This study aims to develop theoretical models for predicting both lower and upper flammability limits for fuel mixtures from molecular structures with the same molecular descriptors. All samples were collected from a single reference and the “compounds out” strategy was employed to divide the training and the test set. Descriptors for pure compounds were calculated by Gaussian 16 and Multiwfn package. The developed LFL and UFL models were validated with rigorous internal and external validations. The results indicated the robustness, validity, and satisfactory predictivity of the established models. The applicability domain (AD) of the model was also defined. The established LFL and UFL models demonstrated that the higher dipole moment and van der Waals volume are, the higher LFL and lower UFL values are. The proposed models can be expected to predict the LFL and UFL values for other fuel mixtures for which experiment values are unknown, only based on molecular structures.

To improve the properties of Zr powder for specific applications in aerospace and military fields, Zr powders were coated with ferrite nanoparticles, namely FeOOH, Fe2O3, and Fe3O4. An instantaneous flame propagation system and scanning electron microscopy, X-ray diffraction, thermogravimetry, and differential scanning calorimetry techniques was used to characterized the flame propagation characteristics, micromorphology, phase composition, crystal structure, thermal stability, and reactivity of the three types of nano ferrite-coated Zr particles. The results showed that, the flame propagation velocity and maximal temperature exhibited the following order: Fe2O3-coated > FeOOH-coated > Fe3O4-coated Zr dust cloud. With an increase in the proportion of coating materials, the combustion characteristics all decreased. The contrastive analysis of surface, ingredient and heating process revealed that, during combustion, in addition to inducing oxidation–reduction, inner Zr led to a replacement reaction with the outside ferrite coating layer, and then, Fe generated was oxidized at a high temperature.

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.

Hazardous materials are stored in the large tanks in the industry, e.g., a single LNG tank can be as large as 230,000 m3. Therefore, a catastrophic tank failure can cause a disastrous incident. A secondary containment, such as a bund, is required by regulations to control the risk; however, the released liquid may overtop from the bund due to its high kinetic energy converted from potential energy. Computational Fluid Dynamic (CFD) is a proper tool for the bund overtopping study, but there has been significant discrepancy among previous CFD studies. This work developed 2D CFD models of bund overtopping using the axisymmetric approach. A screening study on several turbulence models was performed, and RNG k-e Standard Wall Functions (RNG k-e SWF1) and Large Eddy Simulation WALE (LES WALE) were selected for a detailed comparison in terms of overtopping fraction and flow dynamic behaviour. Both RNG k-e and LES models were systematically validated against experimental data, and the results indicate that LES model is slightly better than RNG k-e model, and both models are acceptable based on the criteria of statistical performance measures.

Thermal runaway is a common hazard leading to process safety-related accidents. Uncontrolled release of chemical energy poses extreme risks for batch reactors. In this study, we fabricated encapsulated phase change materials (PCMs) with silica shells as inhibitors to improve the thermal management of reactors and mitigate reaction thermal runaway. The prepared encapsulated PCMs had core-shell microstructures and spherical morphologies, with an average particle diameter of 980 nm and a silica shell thickness of 100 nm. A series of inhibition experiments were conducted with 0.5 and 1 g of encapsulated PCMs. Three stages were identified from the inhibition experiments. Kinetic parameters of esterification of propionic anhydride with 2-butanol, catalyzed by sulfuric acid, were estimated based on an autocatalytic parallel reaction model. An inhibition effect-kinetic model was proposed to simulate the inhibition process of the thermal runaway reaction. The results revealed that thermal storage and heat transfer intensification of encapsulated PCMs play a crucial role in the inhibition process. The effect of stirring rate, dispersity of encapsulated PCMs, and warning temperature of thermal runaway while optimizing the injection strategy of inhibitors was assessed. The inhibition of thermal runaway under adiabatic conditions was relatively low.

Mixed carbon materials composed of carbon nanotubes and graphene were applied as fire retardant filler in the fire resistive coating. The fire resistance, thermal stability, water resistance and mechanical properties were investigated respectively. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) were used to study the morphology and composition of the carbon chars. The results indicated that the combination of graphene and carbon nanotubes could have a synergistic effect on fire protection and thermal stability. Additionally, when the weight ratio of graphene and carbon nanotubes was 3:1, the coating exhibited “Excellent” fire resistance and flame retardancy index (FRI) was over 10. SEM, EDS, XRD analysis demonstrated that the carbon content of dense carbon layer achieved 40.97% and titanium pyrophosphate was generated. The coating with higher content of graphene exhibited better water resistance, mechanical properties and adhesion level.

We investigated the thermal hazard of triacetone triperoxide (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane, TATP) due to the influence of ionic liquid (IL). First, cyclic TATP was purified with a solvent mixed with methanol and 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF4]). Second, gas chromatography/mass spectrometry (GC/MS) and Fourier transform infrared spectrometry (FTIR) were utilised to analyze the composition of the products. It was proved that the samples matched with the purchased sample to a greater extent. The thermal decomposition process of TATP was investigated by differential scanning calorimetry (DSC), thermogravimetry analyser (TGA) and vent sizing package 2 (VSP2). Based upon the data of DSC tests, the apparent activation energy (Ea) of these three samples was worked out and compared with the Starink calculation method. The maximum peak temperature (Tmax) and the average decomposition heat (ΔHd) of TATP became lower when the concentration of the [BMIM][BF4] increased because of the mixed solvent. The results of the TG experiments were consistent with those of the DSC tests. Based upon the VSP2 data, the thermal hazard data pertaining to Tmax, the maximum pressure (Pmax), self-heating rate, and the pressure rise rate were obtained. The data derived from this regard decreased when [BMIM][BF4] was added to the mixed solvent. We explored the effects of [BMIM][BF4] on the thermal decomposition hazard of TATP. The decomposition mechanism of TATP was studied when the [BMIM][BF4] was added. Moreover, the bond dissociation energy of TATP molecule was 113.13 kJ/mol calculated by Gaussian software simulation.

The two-phase flow evolution, internal pressure, and thermodynamics responses during a BLEVE (boiling liquid expanding vapor explosion) process with water are assessed. Various initial pressures ranging from 1.7 to 5.7 barg, liquid fills load and different pressure relief ways were tested. Results show that after the pneumatic valve was opened, the rise velocity of the bubble increased first, and then decreased until the rupture or collision of the bubbles. The countercurrent flow reversed to the mainstream was experimentally observed and inhibited the expansion flow to reduce the boiling intensity. Thus, as the initial pressure increased, the average rate of pressure rose first increased, then slightly decreased due to the competitive effects of expansion flow and countercurrent flow. The interactions between the rarefaction wave driven by a sudden opening of a valve and the medium degree of superheat, control the pressure response, and the delay of boiling can be classified into the rarefaction wave control region (dp/dt 0). And the effect of the liquid fill level on the rate of pressure rise was not affected by the countercurrent flow. The boiling explosion after the crack formed was intensified with pressure relief action caused by a separate piece of equipment, due to the enhanced heterogeneous boiling on the inner wall.

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.

Thermal pyrolysis and decomposition products of flufenacet and sulfentrazone powders were tested by thermogravimetric analysis (TGA), TGA coupled with Fourier transform infrared spectroscopy and pyrolysis-gas chromatography/mass spectrometry. Besides, the explosion sensitivity (minimum ignition temperature, minimum ignition energy, minimum explosion concentration) and explosion severity (maximum explosion pressure, and the maximum rate of pressure rise) were measured in standard 20-L spherical chamber, Hartmann apparatus and Godbert-Greenwald Furnace apparatus. Moreover, the effect of thermal pyrolysis characteristics on the explosion sensitivity and severity of flufenacet and sulfentrazone dust clouds were analyzed. The results indicated that flufenacet had lower decompose temperature, and smaller activation energy than sulfentrazone. Both flufenacet and sulfentrazone expressed flammable and toxic substance during their decomposition. Greater amount of products with higher flammability were expressed from flufenacet compared with sulfentrazone. The flufenacet had lower explosion sensitivity than sulfentrazone In addition, the flufenacet’s explosion severity was higher than sulfentrazone, which was mainly determined by the larger number of combustible gases from flufenacet. What’s more, both the two herbicide powders can lead to serious dust explosion accidents due to their explosive and toxic characteristics.

Impinging jet fire of high exit momentum is frequently reported to induce the domino effect in industry fires. Less literature is available for the flame extension area and temperature distribution over a vertical plate impinged by the horizontal jet flame. Thus, this paper conducts a systematic experiment to reveal the effect of nozzle exit velocity, exit diameter and exit-plate spacing on the horizontally impinging jet fire. Experimental observation shows the evolution of flame pattern and color with an increase of exit velocity and a decrease of exit-plate spacing. The flame extension area induced by the horizontal jet flame impingement was measured by a novel method that combines the picture processing technique and the thermal imaging technique. By physical analysis, a new correlation coupling the turbulent Karlovitz stretch factor and the ratio of nozzle exit diameter to exit-plate spacing, was developed for the flame extension area of both horizontally and vertically impinging jet fire. The variation of maximum temperature in the impinging zone with the exit-plate spacing still fits the classic correlation of centerline temperature in the continuous and intermittent flames. However, the horizontally impinging jet fire plume holds a shorter intermittent flame region due to the flame upward bending. It is found that the temperature profile holds a big difference in the upward and downward directions along the vertical plate. A new uniform correlation, with the plume radius as the characteristic length scale, is proposed to well collapse all the temperature data in the impinging zone.