Chi-Min Shu

Thermal explosion hazards on 18650 lithium ion batteries with a VSP2 adiabatic calorimeter

Thermal abuse behaviors relating to adiabatic runaway reactions in commercial 18650 lithium ion batteries (LiCoO(2)) are being studied in an adiabatic calorimeter, vent sizing package 2 (VSP2). We select four worldwide battery producers, Sony, Sanyo, Samsung and LG, and tested their Li-ion batteries, which have LiCoO(2) cathodes, to determine their thermal instabilities and adiabatic runaway features. The charged (4.2V) and uncharged (3.7 V) 18650 Li-ion batteries are tested using a VSP2 with a customized stainless steel test can to evaluate their thermal hazard characteristics, such as the initial exothermic temperature (T(0)), the self-heating rate (dT/dt), the pressure rise rate (dP/dt), the pressure-temperature profiles and the maximum temperature (T(max)) and pressure (P(max)). The T(max) and P(max) of the charged Li-ion battery during the runaway reaction reach 903.0°C and 1565.9 psig (pound-force per square inch gauge), respectively. This result leads to a thermal explosion, and the heat of reaction is 26.2 kJ. The thermokinetic parameters of the reaction of LiCoO(2) batteries are also determined using the Arrhenius model. The thermal reaction mechanism of the Li-ion battery (pack) proved to be an important safety concern for energy storage. Additionally, use of the VSP2 to classify the self-reactive ratings of the various Li-ion batteries demonstrates a new application of the adiabatic calorimetric methodology.

Modeling solid thermal explosion containment on reactor HNIW and HMX.

2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (HNIW), also known as CL-20 and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), are highly energetic materials which have been popular in national defense industries for years. This study established the models of thermal decomposition and thermal explosion hazard for HNIW and HMX. Differential scanning calorimetry (DSC) data were used for parameters determination of the thermokinetic models, and then these models were employed for simulation of thermal explosion in a 437L barrel reactor and a 24 kg cubic box package. Experimental results indicating the best storage conditions to avoid any violent runaway reaction of HNIW and HMX were also discovered. This study also developed an efficient procedure regarding creation of thermokinetics and assessment of thermal hazards of HNIW and HMX that could be applied to ensure safe storage conditions.

Thermal explosion analysis of methyl ethyl ketone peroxide by non-isothermal and isothermal calorimetric applications

In the past, process incidents attributed to organic peroxides (OPs) that involved near misses, over-pressures, runaway reactions, and thermal explosions occurred because of poor training, human error, incorrect kinetic assumptions, insufficient change management, and inadequate chemical knowledge in the manufacturing process. Calorimetric applications were employed broadly to test organic peroxides on a small-scale because of their thermal hazards, such as exothermic behavior and self-accelerating decomposition in the laboratory. In essence, methyl ethyl ketone peroxide (MEKPO) is highly reactive and exothermically unstable. In recent years, it has undergone many thermal explosions and runaway reaction incidents in the manufacturing process. Differential scanning calorimetry (DSC), vent sizing package 2 (VSP2), and thermal activity monitor (TAM) were employed to analyze thermokinetic parameters and safety index. The intent of the analyses was to facilitate the use of various auto-alarm equipments to detect over-pressure, over-temperature, and hazardous materials leaks for a wide spectrum of operations. Results indicated that MEKPO decomposition is detected at low temperatures (30-40 degrees C), and the rate of decomposition was shown to exponentially increase with temperature and pressure. Determining time to maximum rate (TMR), self-accelerating decomposition temperature (SADT), maximum temperature (T(max)), exothermic onset temperature (T(0)), and heat of decomposition (DeltaH(d)) was essential for identifying early-stage runaway reactions effectively for industries.

Investigation of the flammability zone of o-xylene under various pressures and oxygen concentrations at 150 °C

Abstract Knowledge of material safety properties is essential for safe handling during unit operations, as incidents in plants can often be traced to an insufficient knowledge of the hazardous properties of combustible or flammable substances. If determined carefully and applied properly, safety-related properties will provide information on the reaction behaviors and possible fire and explosion hazards of the specific substance. The aim of this study was to investigate the safety-related properties of o -xylene (e.g., flammability limits, minimum oxygen concentration, maximum explosion overpressure, and flammability zone). These properties were determined with a 20-L-Apparatus at a mixing operation temperature of 150 °C and under initial pressures of 760, 1520 mmHg, and 2280 mmHg, respectively. An empirical equation was established from the experimental results for the effects of initial pressure on flammability limit. Potential hazards of unit processes in phthalic anhydride plants are also mentioned.

Isothermal hazards evaluation of benzoyl peroxide mixed with benzoic acid via TAM III test

Isothermal microcalorimetry can be used to investigate the thermokinetic parameters for reactive mechanisms. Benzoyl peroxide (BPO), a typical organic peroxide, undergoes an autocatalytic reaction under isothermal decomposition. It requires intrinsically safer design of preparation, manufacturing, transportation, storage, and even disposal. The scope of this study was to describe the exothermic reaction and reaction model of BPO and mixed with benzoic acid by the thermal activity monitor III (TAM III). The results showed the isothermal kinetic parameters, such as activation energy (Ea), frequency factor (A), heat of decomposition (ΔHd), and time to maximum rate under isothermal conditions (TMRiso), which were necessary and useful to insure safe storage or transportation for self-reactive substances applied in the process industries.

Spontaneous combustion in six types of coal by using the simultaneous thermal analysis-Fourier transform infrared spectroscopy technique

Using simultaneous thermal analysis-Fourier transform infrared spectroscopy, we analyzed the oxidation and exothermic behaviors of six types of coal based on various factors, such as characteristic temperature, heat release, and gas release, to establish a foundation for prevention and control of spontaneous combustion in six types of coal in China. According to the experimental results, a decrease in the metamorphic grade of coal causes an increase in the amount of volatile matter, the heat release rate, and the total heat released. The apparent exothermic onset temperature and initial temperature for the release of H2O, CO2, CO, and CH4 during the nonisothermal oxidation process of coal took place earlier, indicating that the oxidation reaction occurred more easily in lower-grade coal, increasing the hazards of spontaneous combustion. Moreover, when decomposing, coal releases large amounts of CH4, which may cause gas explosions in coal mines. Therefore, technology facilitating the detection of CH4 and prevention of explosions should be developed for use in the coal industry.

The synthesis and characterization of graphene oxides based on a modified approach

Graphene (G), and its derivatives, is an ideal two-dimensional material. It is comprised of a single sheet of hexagonally packed carbon atoms. Graphene has attracted significant research interest because of its excellent elastic, optical, electrical, thermal, and mechanical properties. Currently there are some synthesis methods regarding graphene production on the macroscopic-scale level; however, these methods, such as chemical vapor deposition, are expensive. A method for large-scale growth of graphene using widely accessible equipment is currently not an option. In this report, we select an approach based on the Modified Hummer’s method. A comparison is given between the Hummer’s method and the modified Hummer’s method based on extended characterizations using TG for their thermal stability, FTIR for their functional groups, TEM for their surface diagram, UV–Vis for their photo-activity, Raman spectroscopy for the identification of GO quality, and electrochemical methods for their reduction potentials.

Thermal hazard analyses of organic peroxides and inorganic peroxides by calorimetric approaches

Organic peroxides (OPs) and inorganic peroxides (IPs) are usually employed as an initiator for polymerization, a source of free radicals, a hardener, and a linking agent in low density polyethylene (LDPE), polyvinyl chloride (PVC), controlled-rheology polypropylene (CR-PP), and styrene industries. Worldwide, due to their unstably reactive natures, OPs and IPs have caused many serious thermal explosions and runaway reaction incidents. This study was conducted to elucidate its essentially hazardous characteristics. To analyze the runaway behavior of OPs and IPs in the traditional process, thermokinetic parameters including heat of decomposition (ΔHd), exothermic onset temperature (T0), self-accelerating decomposition temperature (SADT), time to maximum rate (TMR), critical temperature (Tc), etc., were measured by calorimetric approaches involving differential scanning calorimetry (DSC), vent sizing package 2 (VSP2), and calculation method. Safety and health handling information of hazardous materials and toxic substances is noted in material safety data sheets (MSDS) and was applied to analyze in process safety management (PSM) in the chemical industries, but MSDS are not providing important handling indicators concerning the SADT, TMR, Tc, etc. In view of loss prevention, more useful indicators must be provided in the sheets or guide book.

Thermal polymerization of uninhibited styrene investigated by using microcalorimetry

Calorimetric studies on the bulk polymerization of uninhibited styrene monomer under low temperature conditions from 50 to 85 degrees C were reported. Various thermograms acquired by either dynamic scanning or isothermal ageing were characterized by differential scanning calorimetry (DSC) or thermal activity monitor (TAM). Isothermal curve demonstrating an autocatalytic phenomenon associated with a characteristic induction time was detected. Heat of thermal polymerization of styrene between 50 and 85 degrees C was measured to be 670+/-11 J g(-1). The findings of this study include: (1) Exothermic phenomenon of thermal-initiation and chain transfer steps in thermal polymerization were corroborated by using calorimetric investigation extended to the temperature as low as 50 degrees C; (2) activation energies in the steps of thermal-initiation and chain transfer were determined to be 125+/-6 and 60+/-5 kJ mol(-1) by using Arrhenius plot, respectively; (3) apparent activation energy was verified to be 84 kJ mol(-1) related to the individual steps of thermal-initiation and chain transfer conformed. These kinetic parameters work well in simulating the adiabatic runaway behaviors of uninhibited styrene and in good agreement with other studies.

Thermal analysis of the pyrolysis and oxidation behaviour of 1/3 coking coal

Pyrolysis is the initial stage of coal conversion during processes including combustion, gasification, and liquefaction. It has a direct effect on coal’s subsequent transformation. Pyrolysis plays a vital role in the efficiency of coal’s use and, like oxidation, can create hazards during non-combustion processing (such as during mining or transportation). Indeed, the spontaneous combustion of coal (a coal–oxygen reaction) can impact human health, lead to material damage and wasted resources, and damage the environment. To better understand this phenomenon, samples of bituminous 1/3 coking were taken from four different coal mines in Huainan (Anhui, China) and analysed. Thermogravimetry and differential scanning calorimetry are adopted to explore the samples’ thermal behaviour. The complex kinetics of the pyrolysis process are divided into four stages, while that of oxidation is divided into five. The influence of heating rates is analysed separately for oxidation and pyrolysis. Furthermore, the apparent activation energy is calculated for the combustion stage of the oxidation process, and curve fitting is used to identify the most probable mechanism function.