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1-Ethyl-2, 3-dimethylimidazolium nitrate [C2mmim][NO3] is a typical solvent for industrial applications. Under inappropriate temperatures, [C2mmim][NO3] may present a flammability hazard due to thermal decomposition. This study investigated the thermal stability and flammability of [C2mmim][NO3] via simultaneous thermogravimetric analyzer, homemade combustion test device (CTD) with high speed camera, and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The thermal decomposition of [C2mmim][NO3] was divided into two parts based upon the dynamic experiments, and the maximum operating temperature was determined to comprehensively estimate the thermal stability of [C2mmim][NO3]. CTD experiments indicated that [C2mmim][NO3] could produce intense combustion when heated. Further TG-FTIR experiments confirmed that [C2mmim][NO3] decomposed to produce a large number of flammable gases, such as ethylene, which might be the reason that [C2mmim][NO3] has prominent flammability.

Using batteries to convert chemical energy into electrical energy is one of the significant technologies that must be enhanced in the 21 st century. In the fuel battery development area, ionic liquids (ILs) are outstanding electrolytes for batteries. According to their thermophysical and phase equilibrium properties, ILs are widely used in different energy fields due to their diversity in the synthesis field. However, there are few detailed thermokinetic studies on ILs. To ensure the thermal safety of ILs in the process of creation, a commonly used IL, 1-butyl-3-methylimidazolium nitrate ([Bmim]NO3), was chosen for exploration. In this study, thermal decomposition characteristics were obtained by differential scanning calorimetry. The obtained data were input into the thermokinetic equation to determine the basic thermal hazards of [Bmim]NO3. In addition, based on thermal equilibrium theoretical models, the reaction kinetics and critical safety parameters were extrapolated for consideration. The influences of the sample mass and the overall heat transfer coefficient were simulated and discussed in 25.0 g and 50.0 g packages. The results showed that [Bmim]NO3 had a shorter TMRad and TCL (

Azo compounds, which are commonly used in radical polymerization reactions, readily demonstrate their self-reactive properties. Because of their sensitive thermal decomposition properties, azo compounds have been responsible for many accidents. To avoid unexpected thermal decomposition in the workplace, information about the thermal stability and other properties of azo compounds should be provided to on-site personnel in industries that use these materials. In this study, the target substance, 2,2′-azobis-(2,4-dimethylvaleronitrile) (ABVN), is shown to have a higher reactivity than other azo compounds, and its thermal decomposition characteristics are discussed based on a literature review and results from differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC). A thermokinetic analysis of ABVN is conducted using DSC and ARC data. The results can provide process-control data and explain the effects of thermal runway for ABVN. In addition, based on applied numerical methods, critical runaway temperatures, stable temperatures, and the required heat dissipation rate for the prevention of the thermal runaway reactions are calculated using a process deviation analysis. The results show that the reactant quantities and the process parameters must be strictly controlled to achieve the desired reaction.

Coal, a flammable substance, is affected by spontaneous weathering and can be hazardous when exposed to thermally unstable conditions. Over the past few decades, numerous chemical disasters involving coal have occurred, resulting in many deaths. Therefore, strategies for the prevention of such disasters must be implemented to ensure human safety, avoid financial losses, and minimise adverse environmental effects. This study determined the thermal safety parameters and thermal hazards of lignitous and long flame coal by using thermogravimetry and differential scanning calorimetry. The characteristics of the functional groups in coal and treated coal were observed through Fourier transform infrared spectrometry. The structures of coal and coal treated with an ionic liquid, namely 1-butyl-3-methylimidazolium, were observed through scanning electron microscopy. Finally, theoretical kinetic models were applied to calculate thermokinetic parameters and identify the degree of thermal hazard present during periods of thermal instability. The results revealed that 1-butyl-3-methylimidazolium nitrate considerably reduced the probability of coal spontaneous combustion and the degree of hazard for long flame coal. Therefore, this ionic liquid could serve as an effective inhibitor of spontaneous combustion in long flame coal.

As a key initiator of polymerization, azo compounds (azos) can supply abundant energy to the polymerization process. Although polymerization can be implemented more smoothly and the product can be modified, the use of azos also increases the probability of process hazards caused by high heat accumulation and release. To preserve the thermal safety of using azo initiators in the synthesis process, the frequently used azo initiators dimethyl 2,2′-azobis(2-methyl propionate) (AIBME) and 2,2′-azobis(2,4-dimethylvaleronitrile) (ABVN) were chosen for investigation. Under process conditions, initiators are essential for evolving and monitoring chemical reactions on both the laboratory scale and process environment. The assessment, control, and mitigation of reaction hazards are primarily based on kinetic models, which are used to estimate multiple critical safety parameters, such as TMRad in process safety and TCL and SADT in storage and transportation operation. The data from the adiabatic calorimeter correspond to real process situations are combined with the nonlinear adiabatic kinetic model, which is rarely applied to analyze the thermal hazard properties of azos. The results indicated that the kinetic model of azos in the actual process, the thermal hazard characteristics, and simulation of the runaway mode of azos in setting boundary conditions should also be investigated.

A severe manufacturing accident involving 2,2′-azobis (isobutyronitrile) (AIBN) occurred in China on April 14, 2011, which created high-pressure gas release killing nine people and severely damaging equipment and buildings. Eliminating chemical catastrophes in the petrochemical industry is a global concern. A new approach, which combines non-isothermal kinetic modeling, runaway reaction, and product analysis, was employed to determine decomposition mechanisms of AIBN by separately using differential scanning calorimetry, simultaneous thermogravimetric analyzer, vent sizing package 2, and gas chromatography/mass spectrometer. The results indicated that azo compound AIBN exhibits higher level of thermal decomposition with a maximum temperature of 294 °C and maximum pressure of 367 psig in comparison to the other azos. Moreover, various critical thermokinetic parameters, such as time to maximum rate, exothermic onset temperature, adiabatic temperature rise, and pressure gradients were obtained. A combination of thermal hazards and reaction pathways was subsequently employed to investigate the thermokinetics and mechanisms of AIBN decomposition.

1,3-Dimethylimidazolium nitrate ([Mmim]NO3), an ionic liquid, is a versatile and novel solvent for the petrochemical industry. Nevertheless, under high temperature conditions or thermal upset scenarios, [Mmim]NO3 can be decomposed in a manner that produces an explosion or other serious safety problems. The aim of this research was to investigate the thermal stability of [Mmim]NO3 by simultaneous thermogravimetric analyzer and high pressure differential scanning calorimetry. Isothermal experiments indicated that [Mmim]NO3 would be decomposed at a temperature substantially lower than the onset temperature. A pseudo-zero-order rate expression was applied to characterize the thermal decomposition kinetics of [Mmim]NO3, and related thermokinetic parameters were further obtained. Moreover, the temperature at which the thermal decomposition of ILs reached 10.0% for a given time of 10.0 h (T0.1/10h) was defined to assess the long-term thermal stability, which can be used as the maximum operating temperature of [Mmim]NO3. The results of this study may provide relevant processes for safer control based on the thermal hazard assessment of [Mmim]NO3.

Azo compounds (azos) possess diverse exothermic properties that enable their application in numerous industrial processes, but these properties also engender a corresponding diversity of thermal hazard profiles. This study employed an innovative approach to determine the specific thermal reactions and decomposition hazard profiles of azos. Four typical azos (AIBN, AMBN, ABVN, and AIBME) were assessed using three thermal calorimetry techniques, and results were subsequently analyzed using a nonlinear optimization model. Thermal hazard analysis of small-scale experiments indicated that AIBN had a heat decomposition of 1247 J/g and a maximum pressure increase of 367 psig and thus exhibited more hazardous characteristics than did AMBN, ABVN, and AIBME. This study also obtained the relevant process safety parameters, time to maximum rate, onset and peak temperature, adiabatic temperature rise, and rate of pressure increase to use for later scaled-up applications. The findings of this study can be used to develop a predictive model for the thermal behavior of azos and to provide the necessary basis for the design and selection of precise treatment and appropriate safety systems.

The effect of particle size polydispersity (σD) on coal dust explosibility was studied using a 20-L spherical explosion test apparatus. Four kinds of blends with a fixed median diameter (D50) of 95 μm but varying σD of 1.18, 1.70, 1.96 and 2.40, were prepared by mixing original coal samples with relative low σD. Experimental results showed that the values of maximum pressure rise (Pex) and maximum rate of pressure rise ((dP/dt)ex·V1/3) of coal blends with the same D50 of 95 μm varied largely with different σD, and bigger σD produced larger Pex and (dP/dt)ex·V1/3 values. The Sauter mean diameter (D3,2) presented the best correlation between particle size and the explosion parameters for the blended coal samples. Risk assessment evaluation of coal dust should be reported in terms of D3,2 and σD to avoid serious underestimation.

Accidents related to pesticides have occurred with increasing frequency in recent years. One such accident, involving O,O–dimethyl phosphoramidothioate (DMPAT), which is an essential pesticide intermediate in the manufacture of organophosphorus pesticides, occurred in Taichung, Taiwan, in 2016. The results of thermogravimetric analyzer, differential scanning calorimetry, and vent sizing package 2 experiments revealed that the atmosphere, heating rate, and stirring conditions of DMPAT affect its thermal stability. Multiple thermokinetic methods were adopted to determine the values of thermal safety parameters. Through multiple linear regression, a reaction model of DMPAT was developed. The time to conversion limit and self-accelerating decomposition temperature were determined. The results of this study provide a reference for ensureing the thermal safety of DMPAT processing, use, storage, and transport and preventing thermal decomposition accidents.

The flame propagation through TiH2 dust cloud at near constant pressure condition is studied in a series of experiments using an apparatus with transparent latex balloons. The influential factors for the combustion performance of TiH2 dust cloud, including dust concentration, particle size, scale of isobaric space and oxygen content are investigated. Results show that the burning velocity increases with dust concentration in the fuel-lean mixtures, and then plateaus after crossing the stoichiometric condition, while the trend of flame speed changing with dust concentration varies for different mean particle sizes (D50) of 48 and 106 μm. The flame propagation speed of dust cloud is positively correlated to the isobaric space scale and oxygen content. The burning mechanism of TiH2 dust is thought to be mainly controlled by diffusion regime, the appearance of hydrogen gas accelerates the combustion rate of TiH2 particles and also makes the TiH2 dust changed from a discrete media to a continuum, which may account for the phenomenon that the flame speed in dust cloud of TiH2 is larger than that of Ti at the same concentration no matter in air or oxygen atmosphere.

A flammable gas could be ignited only if its concentration in air is over a threshold concentration, which is known as the lower flammability limit (LFL). Therefore, predicting LFLs of flammable gases is indispensable for safely handling such flammable gases. The Le Chatelier’s mixing rule for the LFL is the prevailing method for estimating the LFLs of mixtures with multiple flammable components. In this work, a novel derivation for this rule is proposed based on the threshold temperature concept. It is found that the important assumption required to reach this mixing rule is that the adiabatic flame temperature rises at LFL are approximately the same for each flammable component. As the adiabatic flame temperature rise is in a sense the required energy gap to initiate a combustion, it should not change while adding/removing inert gas into/from the system. Therefore, it is also the required perquisite to predict the LFLs of inertized mixture or the LFLs in oxygen atmosphere.

In the petrochemical industry, estimation methods based on isothermal micro-calorimetry are used to precisely analyze the thermal hazards and risks associated with chemicals and to develop an inherently safer design (ISD). Here, a thermal activity monitor III (TAM III) was used under various isothermal conditions to obtain the thermokinetics parameters of reaction mechanisms. Cumene hydroperoxide (CHP), a typical organic peroxide, is decomposed by the action of sulfuric acid to yield phenol and acetone in equimolar quantities. CHP undergoes multiple complex reactions when an autocatalytic reaction occurs under isothermal decomposition. The following reaction scheme was considered in this study: A + nB ⇌ (n + 1) B, A ⇌ B, B → C. This type of reaction generally accelerates as the reactant is consumed, and an autocatalytic substance is produced. As a result, an ISD is required for preparation, manufacturing, transportation, storage, and even elimination. The rich behavioral patterns of these autocatalytic reactions were revealed through multiple specific illustrations.

Ionic liquids (ILs) possess negligible vapor pressure, a low toxicity, a low melting point, and a vast liquid temperature range, rendering them as favorable candidates for new alternative solvents. However, some recent studies showed that ILs are flammable during thermal upsets. To explore the overall spontaneous combustion under upset conditions, we propose a safer method to investigate the IL’s thermal hazards. Gas chromatography/mass spectrometry, Fourier transform infrared spectrometry, and flash point analysis results indicated that 1-butylimidazolium nitrate ([BIM][NO3]) exhibits combustible characteristics and low thermal stability at high temperatures (over ca. 150.0 °C) during thermal decomposition. Meanwhile, differential scanning calorimetry, thermogravimetry, and vent sizing package 2 (VSP2) tests were used to describe the thermal properties of [BIM][NO3]. The thermokinetic parameters were further acquired by using an isoconversional method. The results demonstrate that the suitable combination of anion and cation might yield energetic ILs.

Azo compounds (azos) are vital basic initiators used in chemical plants that also possess thermally active properties. Azos may trigger serious accidents because of their intense exothermicity. We applied a specific method to characterize the reaction kinetics of azos using data from differential scanning calorimetry (DSC). Specifically, this method was used to analyse the thermal decomposition of 2,2-azobis(2-methylbutyronitrile) (AMBN). The exothermic peak temperature, exothermic final temperature, and heat of decomposition were determined. The data obtained from the experiments were utilized to predict the self-accelerating decomposition temperature, control temperature, and emergency temperature. Experiments conducted to explore the runaway phenomenon of AMBN during the overall decomposition process interfered with the thermal analysis studies. We utilized a process simulation model to mimic the decomposition of AMBN, ensuring that the simulation results were realistic and practical. The results are worthy of being applied to thermal analysis, for example, for application in proactive loss prevention.

Low-temperature azo compounds are a new class of self-reactive materials commonly used as initiators and blowing agents. However, their structure contains a bivalent azo bond, which is quickly released at a high ambient temperature. Self-accelerating decomposition can result in a runaway reaction, fire, or explosion. Therefore, the main issue of this study was to ensure the thermal safety of 2,2′-azobis(2-methylpropionate) (AIBME) by itself and when dissolved in different solvents during manufacturing, storage, or transportation. Adiabatic experiments were performed to investigate the pressure and temperature stress effects on heat accumulation, runaway reaction, and catastrophic conditions. To perform a robust evaluation, both nonisothermal and isothermal conditions were employed to investigate the thermal stability of AIBME against potential hazards. The corresponding kinetic and thermokinetic parameters were obtained using the experimental data and a computational model. Finally, we determined experimentally an apparent activation energy of 109.0 kJ/mol under nonisothermal conditions, which can be used as a reference value for hazard prevention to minimize the cost of accidents caused by uncontrolled temperature conditions.

Ionic liquids (ILs), as a type of salt that is liquid at room temperature, break the entrenched views on salt when it was proved that some of them could be ignited. In this research, an innovative method was used to evaluate the thermal stability of such special salts and speculated their ignition mechanism based upon gas analysis. Four typical representative imidazole ILs (BMIMBF4, BMIMDCN, BMIMNO3, and BMIMOAc) were selected, and their thermal decomposition characteristics and thermal effect were obtained by simultaneous thermogravimetric analyser (STA) and differential scanning calorimetry (DSC), respectively. Furthermore, their decomposition products were investigated by thermogravimetry coupled with Fourier-transform infrared spectroscopy (TG-FTIR). It is noteworthy that they behaved diversely in DSC experiments and exhibited a radically different thermal effect in their decomposition. In addition, there exists positive feedback in the mechanism of the exothermic phenomenon of selected ILs in the air. Nevertheless, TG curves of four selected ILs were almost the same under air or nitrogen conditions. Series TG-FTIR experiments confirmed that the initial decomposition products of BMIMBF4 and BMIMDCN under air or nitrogen are extremely different. The decomposition products of BMIMNO3 and BMIMOAc in the air atmosphere have more oxidative products than nitrogen. The results denoted that the thermal decomposition mechanism of the four selected ILs in the air were the same as under nitrogen. The reducibility of the decomposition products induced the peculiar thermal effects of these imidazole ILs under the different gas environments. This study was innovative in researching the thermal effect and mechanism of imidazole ILs’ decomposition and provided certain safety guidance for the process safety and loss prevention of imidazole ILs.

Azo compounds are widely involved in the industrial processes of dyes, pigments, initiators, and blowing agents. Unfortunately, these compounds have a bivalent unstable –N N– composition, which can be readily broken when the ambient temperature is elevated. Self-accelerating decomposition might cause a runaway reaction and lead to a fire, explosion, or leakage when the cooling system fails or other events occur. This study investigated the explosion properties, thermal stability parameters, and thermal hazard and mechanism of 2,2′–azobisisobutyronitrile (AIBN) and 2,2′–azobis–2–methylbutyronitrile (AMBN). We used a 20-L apparatus, vent sizing package 2, synchronous thermal analysis, and differential scanning calorimetry under explosive, adiabatic, and dynamic conditions to acquire the explosive curves, thermal curves, and thermodynamic parameters of the substances. Moreover, the differential isoconversional method (Friedman method) and ASTM E698 equation were employed to obtain the apparent activation energy Ea. All the experimental results revealed that AIBN is more dangerous than AMBN. The Ea of AIBN was lower than that of AMBN. The results can be used to construct an azo compound thermal hazard database for use for searches and reference examples by industry and related research areas.

The polymerization reaction can lower the threshold of the required energy by the initiator to improve the efficiency of the overall process reaction. Emerging polymerization initiators are also a major focus of process improvement and technological progress. Azo compounds (azos), which used in dyeing applications, are subsequently used in polymerization reactions due to their highly exothermic reaction characteristics. Although higher heat release can promote polymerization and modify the product, heat generation may also cause process hazards. These thermal hazard parameters were studied by selecting dimethyl 2,2′-azobis(2,4-dimethylvaleronitrile) (ABVN), 2,2′-azobis(2-methyl propionate) (AIBME), 2,2′-azobis(2-methylpropionamide) dihydrochloride (AIBA), and 2,2′-azobis(isobutyronitrile) (AIBN), which are common azo initiators at present. Thermal hazards are closely related to the reaction kinetics of the substance itself. The form of the reaction, the apparent activation energy and the thermodynamic parameters of the exothermic mode were also obtained. Kinetic analysis of the actual process using the experimental data of the isothermal calorimetry model is rarely used in the evaluation of related thermal hazard characteristics. The simulation results revealed the kinetic azo models and were further applied to calculate the runaway situations of azo under specific boundary conditions.

The pure decomposition behavior of 2,2′-azobis (isobutyronitrile) (AIBN) and its physical phase transformation were examined and discussed. The thermal decomposition of this self-reactive azo compound was explored using differential scanning calorimetry (DSC) to elucidate the stages in the progress of this chemical reaction. DSC was used to predict the kinetic and process safety parameters, such as self-accelerating decomposition temperature (SADT), time to maximum reaction rate under adiabatic conditions (TMRad), and apparent activation energy (Ea), under isothermal and adiabatic conditions with thermal analysis models. Moreover, vent sizing package 2 (VSP2) was applied to examine the runaway reaction combined with simulation and experiments for thermal hazard assessment of AIBN. A thorough understanding of this reaction process can identify AIBN as a hazardous and vulnerable chemical during upset situations. The sublimation and melting of AIBN near its apparent onset decomposition temperature contributed to the initial steps of the reaction and explained the exothermic attributes of the peaks observed in the calorimetric investigation.

The reaction of propylene with adsorbents such as BASF selexsorb CD and UOP of various sizes was studied. Adiabatic runaway tests were conducted on propylene mixed with various adsorbents to obtain knowledge on the thermal profile of each. Thermokinetic data were obtained from non-isothermal calorimetric study from the oligomerized reaction between propylene and various adsorbents. A detailed distribution of sorbent product from the adsorber has been analyzed for carbon product greater than 6 ( >C 6 ) using gas chromatography/mass spectrometry results. The test revealed oligomerization and carbonaceous deposit formation of the adsorbent products. The reason for over-temperature of the reactor wall can be anticipated from the agglomeration of carbonaceous deposit disrupting the normal flow of propylene stream causing channeling and lowering the carry-away of heat-accumulated. This approach of real conditions, along with the simulation of process design and operation using computational fluid dynamics (CFD) studies, can render safer process information for avoiding the occurrence of similar runaway explosion induced industrial disaster.

To investigate thermal runaway behaviors of three azo compounds (2,2’-azobis isobutyronitrile, 2,2’-azobisisobutyramidine hydrochloride, and 2,2’-azobis-2-methylbutyronitrile), this study focused on a green approach in adopting the usage of resources, reducing pollution, and protecting the environment. Azo compounds are widely used as dyes, pigments, blowing agents, and initiators. We analyzed the thermal hazards and incompatibilities of azo compounds using differential scanning calorimetry and thermal activity monitor III under dynamic and isothermal scanning tests. This study devised an effective method for predicting thermal hazards, runaway conditions, and thermal properties for a reactor containing azo compounds of interest. The thermokinetic parameters were then simulated in a hierarchical group of kinetic reaction models by adopting the advanced kinetics and technology solutions approach. The apparent activation energies were compared with that reported the literature. These results are highly relevant because they represent important parameters for a safer process design and feasible optimization.

O,O-dimethylphosphoramidothioate (DMPAT) is widely used as the vital intermediate in pesticides to synthesize acephate, chlorine methamidophos, and methamidophos. February, 2016, a serious explosion and fire occurred in Taichung, Taiwan, resulting from DMPAT decomposition, causing one death and injuring one employee. To explore the thermal hazard of DMPAT, we applied various instruments of thermal analysis. Combustion phenomena and decomposed products were identified by combustion test and gas chromatography-mass spectrometry. Differential scanning calorimetry and thermogravimetry were used to analyze the thermal stability parameters, and mass loss conditions under five heating rates illustrating decomposition. Vent sizing package 2 was used to simulate stirring or unstirring system failure in a practical process. The apparent activation energy of DMPAT and self-accelerating decomposition temperature were, respectively, 92.4 ± 3.2 kJ/mol calculated by Starink equation, and 66.0 °C by simulated approach. The findings of these results are vital for inherently safer measures during production, storage, and transportation.

2-(1-Cyano-1-methylethyl)azocarboxamide (CABN) is a representative of new-type azo initiator in the radical polymerization industry. The peculiar water and oil soluble characters make it a versatile rising star for the industry to initiate the polymerization of monomers in either polar or nonpolar solvents based continuous phases. This paper decodes the effect of acylamino and cyan groups on thermal stability and hazards of CABN via advanced thermokinetic analysis and numerical simulation. Initially, simultaneous thermogravimetric analyzer was employed to evaluate the thermal stability of CABN and its two structurally similar azo compounds (azos), azobisisobutyronitrile (AIBN) and azodicarbonamide (AC). Followed with calorimetric experiments by differential scanning calorimetry, the effect of two functional groups on thermal behavior parameters, such as decomposition temperature, melting point, and heat of decomposition was estimated. The results indicated that the acylamino group can improve the thermal stability of CABN but with bulkier heat release. Ultimately, through the medium of thermokinetic analysis, the thermal hazard of AIBN, CABN, and AC was simulated based on auto-ignition and thermal explosion theory. The research results would provide references for the synthesis of new-type azo initiators and process safety parameters to the polymerization industry.

The thermal hazards of dicumyl peroxide (DCP) and benzoyl peroxide (BPO), self-reactive chemicals are identified and characterized using high-pressuredifferential scanning calorimeter, and simultaneous thermogravimetric analyzer, a C80 micro-calorimeter is used. The apparent exothermic onset temperature of DCP is found to be between the range of 112–122 °C for different heating rates in DSC tests. There are two coupled peaks of BPO around 105 °C at both the heating rates of 4.0 and 8.0 °C/min while no endothermic peak showed at lower heating rates. Furthermore, another endothermic peak appears immediately after the exothermic peak at about 211 °C of DCP under high-pressure conditions. For BPO, the endothermic peak before the exothermic peak disappears as the pressure increases to 1.0 and 1.5 MPa. The average values of apparent activation energy calculated by Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods during the conversion rate between 15 and 75% of DCP are 80.69 and 74.05 kJ/mol, and that of BPO are 119.96 and 112.93 kJ/mol, respectively. According to the isothermal tests, the thermal decomposition of DCP behaviors is an n-th order reaction while BPO conforms to the laws of autocatalytic reaction.

Spontaneous combustion of secondary oxidation coal seriously affects the safety of goaf in coal mine. To investigate the effect of nitrogen on secondary oxidation coal, thermal analysis and temperature-programmed methods were adopted to explore the thermal behavior and extinguishing ability. The combustion process was divided into the heating process and extinguishing process. Simultaneous thermal analyses performing connected with a Fourier transform infrared spectroscopy analyzer, were applied to the heating process. A temperature-programmed system was employed for extinguishing process. The results demonstrated that nitrogen concentration inhibited the oxidized decomposition and solid-phase reaction. As the nitrogen concentration increased, characteristic temperatures were delayed, and the activation energy of the secondary oxidation coal combustion stage elevated from 138.6 to 158.6 kJ/mol. The nitrogen concentration had little effect on the product H2O, CO, and CO2, while change of the nitrogen concentration mainly inhibited the generation of oxygen-containing functional groups and decomposition of aliphatic hydrocarbons. When the nitrogen concentration increased to 50% during the extinguishing process, the time required for the temperature to decrease from 400 to 30 °C was 39.0% shorter than that during natural extinction, and CO disappeared 42.1% faster. Reaction kinetics were used to analyze the fire extinguishing process of secondary oxidation coal and its spontaneous combustion. The heating process is conducive to determining the combustion characteristics of secondary oxidation coal. The extinguishing process experiments can monitor the changes after extinguishing the spontaneous combustion of coal in a closed fire zone.

Ionic liquids (ILs) are known as room temperature molten salts, which are considered green replacement to traditional organic solvents. The fire hazards of traditional organic solvents mainly depend on the combustibility of their vapors, thus ILs are generally regarded as nonflammable owing to their low volatility. However, recent studies show that ILs may combust due to the potential hazards of thermal decomposition, indicating the issue of fire and explosion of ILs are eager to be evaluated during the applications. In this study, the fire and explosion hazards of IL 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6mim][NTf2]) are explored in different aspects. The traditional definition of the flammability for the common organic solvent is not thoroughly applicable to [C6mim][NTf2] due to the low volatility. Furthermore, the common definition of reactivity for traditional organic solvents also fails to apply, because the decomposition reaction is indeed an endothermic reaction. However, the auto-ignition of some decomposition products will result in fire and explosion hazards for [C6mim][NTf2]. Therefore the application of such data in safety purposes should be very careful.

Azo compounds, which are commonly used as initiators and blowing agents, are also typical self-reactive materials capable of undergoing runaway reaction during storage and transportation, which can cause severe fires and accidents. To ensure the thermal safety of azo compounds in the process, transportation, and applications, this study investigated 2-cyanopropan-2-yliminourea, which can also be called V-30. First, thermal decomposition characteristics under the non-isothermal conditions were obtained using differential scanning calorimetry. Second, the collected data were combined with a mathematical model to evaluate the primary thermal hazard during the process for V-30. Then, based on a heat-transfer model, the self-accelerating decomposition temperature (SADT) was extrapolated for consideration and non-consideration of consumption of chemicals. The results showed that SADT of V-30 was less than 80 °C. Therefore, it is essential to avoid a temperature beyond SADT or the cooling system will fail. The influence of consumption was also considered for SADT in this study.

Azo-peroxyester, a multifunctional elemental energetic material, has low efficiency when indirectly acting on the target product in a reaction. If azo-peroxyester is dissolved in an appropriate solvent, the yield is greatly improved. With the aim of perfecting the safety of diethyl azodicarboxylate (DEAD) in industrial process applications, this study evaluated the inherent safety of DEAD when dissolved in different reagents by using differential scanning calorimetry and a thermal activity monitor III. The thermokinetic parameters, exothermic onset temperature (To), time to maximum rate under isothermal conditions (TMRiso), and apparent activation energy (Ea), were determined in order to reveal factors influencing the reaction mechanism. Comparing with pure DEAD, T0 was lower when DEAD was dissolved in three ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl)imide. Additionally, Ea and TMRiso were considerably higher, indicating there was an improvement in both efficiency and thermal safety of DEAD for the reaction process. These results support the applications of DEAD in industrial process safety, and set a foundation for future laboratory investigation.

Polymers are salient participants in the current world, and roughly more than 40%–45% of all industrial polymers were produced by free radical polymerization. Azo-initiators now have been the foremost radical initiator with the virtue of low tendency to undergo chain transfer reactions. Nevertheless, azo-initiators are readily to decompose and release an immense amount of heats and gases under elevated ambient temperature. 2-(1-Cyano-1-methylethyl)azocarboxamide (CABN) was deliberately picked as an example for identifying the hazardous scenarios in the application of azo-initiators. Initially, thermal analysis technologies were used to investigate the thermal decomposition characteristics of CABN, and selected decomposition mechanism functions were verified for the best-fitting thermokinetic model. Subsequently, thermokinetic-based numerical simulations were implemented to evaluate the thermal hazards of CABN under the ideal adiabatic scenario. Process safety parameters under adiabatic conditions including time to maximum rate as well as induction period were consequently retrieved. Furthermore, inherent safety recommendations for free-radical polymerization were established to forestall the process accidents in storage and the applications of azo-initiator.

To reduce costs, high-purity chemical suppliers wash and reuse HDPE containers collected from users. To determine the lifetime of a container, the appearance of that container and the manufacturer's recommendations for its lifetime are generally considered. Guidelines for determining the lifetime of an HDPE container have not been clearly defined. The lack of these specifications may result in the leakage of high-purity chemicals in the storage, transportation and use of HDPE containers. To understand the effects of using high-purity chemicals (sulfuric acid (H2SO4) and nitric acid (HNO3)) on HDPE, this study revealed its effects by mechanical and thermal performance tests. According to the mechanical properties test results, the ductility and tensile strength of HDPE soaked H2SO4 and HNO3 decreased. HDPE immersed in HNO3 exhibited the lowest thermal stability by thermal performance testing. In summary, the degradation of HDPE is affected by storage conditions. For this study, HDPE only needs 60 days of immersion in HNO3, and its ductility and tensile strength will decline obviously. This study shows that when these containers are used for long-term storage of high purity chemicals, the mechanical properties (including ductility, ductility, and tensile strength) of HDPE containers tend to decrease. To decrease accidental leakage of chemicals due to aging of HDPE, comprehensive and approved regulations should be established for the loading, transport, and storage of HDPE containers.

Microalgae produce increased lipid content accompanied by a significant decrease in cell density with decreasing nitrate concentration. Magnetic fields (MF) have been reported as a factor that could accelerate metabolism and growth in microalgae culture. Thus, this study aimed to optimize the influence of MF and nitrate concentration (sodium nitrate, N) on the growth and lipid productivity of Nannochloropsis oculata. A single-factor experiment integrated with response surface methodology (RSM) via central composite design (CCD) was performed. The results showed that the maximum specific growth rate (0.24 d−1) and maximum lipid productivity (38 mg L−1 d−1) obtained in this study were higher than those of the control culture (by 166% and 103%, respectively). This study also found that the two-way interaction term MF × N had a significant effect on cell growth but not on lipid production. It was concluded that to design appropriate MF for enhanced lipid productivity due to cell growth, further research must focus on developing an understanding of the relationship between the bioeffects of the magnetic field and the proteomic changes involved in lipid accumulation strategies. This approach would enable the design of conditions to obtain inexpensive high-value products from N. oculata.

A new approach was used to monitor the autocatalytic reaction of benzoyl peroxide (BPO) by non-isothermal and isothermal kinetic models constructed using differential scanning calorimetry and thermal activity monitor III analyses, respectively. Autocatalytic reactions generally start slowly and then accelerate as the reactant is consumed and the autocatalyst is produced. Consequently, an autocatalytic reaction may require special design considerations to avoid certain upset conditions, such as runaway exothermic reactions. We conducted a thermal hazard analysis of various products, including benzoic acid, benzene, and phenol, which were deliberately selected and individually mixed with BPO to investigate their thermal hazards. Model fitting can be applied to predict the amount of time required to achieve the maximum rate under isothermal conditions at any temperature of interest. The proposed procedure was effective and accurate for evaluating the autocatalytic reaction of BPO.

In 2011, a large petrochemical complex in Taiwan incurred several fire and explosion accidents, which had considerable negative impact for the industry on both environmental and safety issues. Reactive substances are widely used in many chemical industrial fields as an initiator, hardeners, or cross-linking agents of radical polymerization process with unsaturated monomer. However, the unpredictable factors during the process having risk to runaway reaction, thermal explosion, fire, and exposure to harmful toxic chemicals release due to the huge heat and gas products by thermal decomposition could not be removed from the process. This study used differential technology of thermal analysis to characterize the inherent hazard behaviors of azo compounds and organic peroxides in the process, to seek the elimination of the source of the harmful effects and achieve the best process safety practices with zero disaster and sound business continuity plan.

Organic peroxides (OPs) are commonly used in many industrial fields as initiators, hardeners, or cross-linking agents of radical polymerization with unsaturated monomers. However, OPs contain the bivalent O O structure which can incur exothermic decomposition that involves the splitting of the peroxide bond with a huge heat release and gas products that may cause an explosion under an uncontrollable upset. Differential scanning calorimetry (DSC) and thermal activity monitor III (TAM III) were used to analyze the thermal hazards and incompatibilities (H2SO4, NaOH, and Na2SO3) of cumene hydroperoxide (CHP), benzoyl peroxide (BPO), and dicumyl peroxide (DCPO). Dynamic and isothermal scanning tests were performed to compare the exothermic behaviors in a process. The thermokinetic data obtained via vent sizing package 2 (VSP2) were applied for evaluation, and the effects of thermal runaway hazard were compared for OPs conducted by acids and alkalis. These results are critically important in safer process design for producing and using OPs.