Risk Of Explosion Research Articles

Damage and deformation behavior of reinforced concrete pipes with varying joints under surface explosion

Reinforced concrete pipes (RCP) are the mainstay of urban water transmission networks. Urban development entails increased potential for blasting activities (such as subway tunneling, excavation, and demolition) as well as the risk of accidental explosions. This paper provides a detailed description of the damage evolution and deformation process of RCP under explosive loads using validated numerical simulation methods. A concise phenomenon-based method is introduced for RCP damage grading. Furthermore, a comparative analysis is conducted on the damage and deformation of RCP resulting from explosions at different locations and with varying weights. At last, this paper especially investigates and explains the impact of four commonly used joint types on the RCP’s response to explosions. The research results help to enhance the understanding of damage evolution and deformation behavior of RCP (or similar structures) induced by explosion, and are also references for protection, repairing and failure identification of segmented structures subjected to explosion.

Integration of a Microchannel Reactor in a CECE Process for H2 Removal from the O2 Stream Produced by the H2 Generator

A hydrogen generator is used in the combined electrolysis catalytic exchange process (CECE) for low-level tritiated water detritiation as a source of H2 (Q2) for the liquid-phase catalytic exchange column(s) within the process. To produce H2, the H2 generator employs an electrolytic process for H2O splitting into H2 and O2, resulting two streams: a hydrogen stream and an oxygen stream. During the detritiation of water, tritium is accumulated in the H2 generator in the form of tritiated water, and the effluent streams (hydrogen and oxygen) show in time an increased tritium concentration in the form of both tritiated water vapors and gas, which need to be recovered. The traditional methods for recovery present a risk of explosion due to the high concentration of hydrogen in oxygen (above 3%, while the explosion limit is 1%). In order to minimize this risk, a microchannel reactor with platinated channels has been developed and tested for the oxidation of tritiated hydrogen from the O2 electrolyzer stream in view of its recovery in a scrubber column and returned as tritiated water to the process. The reactor has been coupled to an electrolyzer and tested with regard to the operating temperature. It has been found that it reaches the highest oxidation efficiency of hydrogen when operated at 200°C. The design of the equipment is presented together with the results of the tests done with the equipment integrated in the CECE process.

Hydrogen carriers for zero-emission ship propulsion using PEM fuel cells: an evaluation

Green hydrogen combined with PEM fuel cell systems is a viable option to meet the demand for alternative maritime fuels. However, hydrogen storage faces challenges, including low volumetric density, fire and explosion risks and transport challenges. We assessed over fifteen hydrogen carriers based on their maritime performance characteristics to determine their suitability for shipboard use. Evaluation criteria included energy density, locally zero-emission, circularity of process, safety, dehydrogenation process, logistic availability and handling. Thus, excluding ammonia and methanol because of these constraints, we found that borohydrides, liquid organic hydrogen carriers and ammoniaborane are the most promising hydrogen carriers to use on ships with PEM fuel cells. Borohydrides, specifically sodium borohydride, have high energy densities but face regeneration issues. The liquid organic hydrogen carrier dibenzyltoluene has a lower energy density but exhibits easy hydrogenation and good handling. Given varying operational demands, we developed a framework to assess the suitability of hydrogen carriers for use in different ship categories. Evaluating the three types of hydrogen carriers, using our framework and considering current practices, shows that these are viable options for almost all ship types. Thus, we have identified three types of hydrogen carriers, which should be the focus of future research.

Rancang Bangun Sistem Monitoring Kebocoran Gas, Suhu, dan Kelembapan pada Dapur Berbasis Internet of Things Menggunakan Mikrokontroler Wemos D1 Mini

This research is about the design of a gas leak monitoring system, temperature, and humidity in an Internet of Things (IoT) based kitchen using a Wemos D1 Mini microcontroller. The system aims to overcome the problem of uncontrolled temperature and humidity that affect the quality of food, as well as the high risk of LPG gas explosion due to leakage. A gas leak monitoring system using MQ2 sensor, monitoring temperature and humidity values using DHT 11 sensor and microcontroller using Wemos D1 Mini. The MQ2 sensor will detect a gas leak from the volume of gas in the room. If the gas value in the room is 300 ppm, the buzzer will sound. The DHT 11 sensor will monitor the temperature and humidity percentage. Then the Wemos d1 mini will send the value to the BLYNK database and will be displayed in the application using Kodular. This research is expected to contribute to the field of IoT-based monitoring systems, improving the safety and comfort of the kitchen environment.

Optimization of membrane thickness for proton exchange membrane electrolyzer considering hydrogen production efficiency and hydrogen permeation phenomenon

Reducing the membrane thickness of Proton exchange membrane (PEM) electrolyzer was found to efficiently promote the hydrogen production rate. However, it can also aggravate the phenomenon of hydrogen permeation, leading to an increased hydrogen content on the anode side and posing a risk of explosions. Thus, optimal design of the membrane thickness of PEM electrolyzer systems is crucial to ensure both safe and efficient hydrogen production. In this paper, we propose two optimization problems for the membrane thicknesses, aiming at achieving a balance between the hydrogen content on the anode side and the hydrogen production rate under constant and varying power input conditions. First, the theoretical model of a PEM electrolyzer is established, and a photovoltaic-PEM electrolyzer system is considered to provide varying power input conditions. Then, the two optimization problems are formulated and resolved using the sequential quadratic programming (SQP) and particle swarm optimization (PSO) algorithms, respectively. Our results reveal that the optimal membrane thickness decreases as the constant input power increases. This suggests that high/low power inputs require thin/thick membranes. For varying power input, we collected one year of solar radiation intensity data from four different regions in China. The findings demonstrate that the selection of the optimal membrane thickness depends not only on the average solar radiation intensity but also on its seasonal variations. By applying these strategies, we effectively optimize the membrane thickness in PEM electrolyzer systems, thereby enhancing the efficiency and safety of hydrogen production. The outcomes provide valuable insights for selecting the appropriate membrane thickness in regions with varying solar radiation intensities and accounting for seasonal variations in solar radiation.

Comprehensive risk assessment for the esterification processes based on Dempster-Shafer evidence theory and cloud model

As a typical chemical process, esterification is usually exothermic and has a high risk of fire and explosion. To recognize and control the risk, it is vital to conduct risk assessment. Therefore, a comprehensive risk assessment method for the esterification process was proposed in this study. By analyzing the characteristics and hazards of the esterification process, a comprehensive evaluation index system was established. It covers four aspects including risk of materials, risk of reaction, possibility of thermal runaway inhibition and risk of process conditions. The improved Dempster-Shafer evidence theory integrates the Hellinger distance and the Pignistic vector angle. It effectively deals with the conflicts between different experts when determining weights. And the cloud model was used to grade index criteria, converting qualitative and quantitative assessment results. This was done to deal with the randomness and ambiguity in the assessment process. Syntheses of butl acetate and tert-butyl peroxyacetate were adopted as case study to validate the proposed method. The assessment results are generally consistent with the Dow's Fire and Explosion Index (F&EI) and the Inherent Benign⁃ness Indicator (IBI). This work will provide a new method for comprehensive risk assessment of the esterification process and can be further used for process optimization.

Investigation on dynamic adhesion characteristics and evolution mechanism of charged particles

Understanding the dynamic characteristics and evolution mechanism of charged particles adhered to the wall is of great significance for strengthening production safety and reducing the risk of explosion caused by adhesion. In this study, experiments and simulations are combined to explore the adhesion characteristics of charged particles and reveal the adhesion mechanism. According to the charge-to-mass ratio and particle size distribution of the adhered particles in the experiment and simulation, the dynamic adhesion characteristics of the adhered particles are explored to verify the accuracy of the simulation model. The evolutionary pattern of adhered particles is obtained by exploring the charge characteristics and size distributions of particles. The forces acting on the adhered particles are analyzed to reveal the adhesion mechanism of the particles. Furthermore, the probability of adhered particles with different particle charge and size is studied and the criterion of particle adhesion is proposed.

A hydrogen-vanadium rebalance cell based on ABPBI membrane operating at low hydrogen concentration to restore the capacity of VRFB

A hydrogen‑vanadium rebalance cell (HVRC) is developed to address the capacity degradation and hydrogen explosion risks in long-term operations of all‑vanadium liquid flow battery (VRFB). Different operating conditions was evaluated in this study to investigate the cell's performance focusing on low hydrogen concentrations (4 %). The HVRC achieved a stable rebalance process with a meager hydrogen stoichiometry ratio of 1.15 at 300 mA cm−2. The use of PFSA membranes was found to be problematic due to the contradictory issues of unstable battery operation without humidification and severe vanadium ion loss with humidification. Therefore, ABPBI membrane was used instead of PFSA membrane to reduce vanadium ion crossover and Pt catalyst corrosion. HVRC based on ABPBI membrane completed a 100 h stability test at 70 mA cm−2 with a stoichiometric ratio of hydrogen of 1.23. The vanadium ion crossover of ABPBI-HVRC was less than 1/6 that of PFSA-HVRC, and no significant platinum dissolution occurred during 100 h operation without humidification. The reliability of the ABPBI-HVRC in intermittent operation mode has also been verified. These results illustrate the HVRC offers a promising measure to eliminate safety issues and restore capacity in VRFB systems. Additionally, incorporating the ABPBI membrane in the HVRC holds greater promise for enhancing its stability.

Explosion risk assessment of a liquid organic hydrogen carrier system by using toluene–methylcyclohexane on varying hydrogen storage scenarios

The effects of phase state, delayed ignition time, mixing ratio, addition of hydrogen, and stoichiometric ratio on the explosion risk of toluene–methylcyclohexane (MCH) mixtures was investigated. Our findings indicated that the addition of 10% hydrogen to the toluene–MCH mixture exhibited a highest explosion risk, compared to other operating conditions. Gaseous toluene–MCH mixtures had a higher explosion risk than did liquid droplets of these mixtures. Of the toluene–MCH mixtures prepared in this study, that with a mass ratio of 7:3 had the highest explosion risk. Although the explosion intensities of the toluene–MCH mixtures were higher than those of their individual components, their explosion sensitivity was lower than that of MCH alone. Toluene had the lowest explosion risk. Toluene or MCH droplets can produce high-intensity explosions even in an oxygen-lean environment. These results indicate that the physical and chemical properties (and thus the combustion performance) of toluene–MCH mixtures are substantially affected by the mixing ratio and operating conditions. Overall, explosion prevention and control measures must be carefully considered when handling toluene–MCH mixtures for various hydrogen storage scenario, such as heating, mixture, or hydrogenation.

Suppressive effects of alkali metal salt modified dry water material on methane-air explosion

As an abundant and efficient energy source, methane has a wide range of applications and development prospects, but it has a high explosion risk. In order to prevent the occurrence of methane explosion accidents, a new type of dry water material (DW) was used to suppress explosion, and alkali metal salts were added to improve the suppression effect. In this work, the optimal DW with complete monomer and uniform structure can be prepared by stirring nano-silica and deionized water at a mass ratio of 1:10 at a speed of 10000 rpm for 60S. The suppression effect of dry water was analyzed by performing methane-air explosion experiments with different powder concentrations in 20L explosion vessel. The results show that under the action of alkali metal modified DW, the Pmax and the deflagration index KG of methane-air explosion were significantly reduced. The improvement effect of potassium salt-dry water (PS-DW) ranked as KCl＞ K2CO3＞ K2C2O4·H2O＞CH3COOK, and the improvement effect of sodium salt-dry water (SS-DW) ranked as Na2CO3>NaCl > NaHCO3>NaH2PO4. Moreover, the explosion suppression mechanism of alkali metal salt modified DW was analyzed from four aspects: heat insulation, cooling, dilution and interruption of chain reaction. The study confirmed the important application potential of DW in preventing natural gas leakage explosion and coal mine gas explosion accidents. The optimal selection of modified additives in alkali metal salts holds significant importance for the widespread application of novel dry water composite materials.

Investigation on the flammability limit and limiting oxygen concentration of propane/propylene mixture at elevated temperature and pressure

With the development of industrial technology, a new process has emerged for the production of acrylic acid using propane as a feedstock. There are few studies on the combustion characteristics of propane/propylene mixtures at elevated temperature and pressure. In this study, a flammability limit test system was used to determine the flammability limit and limiting oxygen concentration of propane and propane/propylene mixture at different initial temperatures (30–120 °C) and pressures (0.1–2 MPa). The results showed that with the increase of initial temperature and pressure, the flammability limit range expanded, and the limiting oxygen concentration reduced. In addition, the flammability limit range of the propane/propylene mixture is greater than that of propane, indicating that the addition of propylene increases the explosion risk. The empirical formula of the experimental gas was fitted to predict the combustion and explosion parameters under different conditions. In addition, the chemical reaction simulation of propane/propylene mixture was also investigated. The results showed that with the propylene ratio increased, the adiabatic flame temperature and adiabatic overpressure increased, the proportion of H-abstraction reaction decreased and the proportion of pyrolysis reaction increased significantly, which promoted the explosive reaction and the increase of explosion temperature.

The technology of suppression containment for the SMR in floating nuclear power plants against hydrogen risk

In the event of loss of coolant accident (LOCA) in small modular reactors (SMRs) in floating nuclear power plants (FNPP), appropriate pressure suppression and hydrogen elimination measures must be taken to ensure small modular reactors' safety. This paper utilizes GASFLOW to analyze the environmental conditions and gas behavior following the implementation of pressure suppression and hydrogen elimination measures in SMRs. The results indicate that: 1) The suppression effect is optimal when the capacity of the suppression pool is 200 m3 and the gas–water ratio is 2.33. 2) When passive autocatalytic recombiners (PARs) are used alone, hydrogen can’t be eliminated quickly, and there is still a hydrogen explosion risk in the containment. 3) Using igniters alone can effectively reduce the hydrogen risk. 4) The combination of PARs and igniters can safely and efficiently eliminate the hydrogen risk, and the temperature inside the containment is lower than when the igniter is used alone.

Prediction of Safe Distance by Radiant Heat Effect Analysis on Plant Concrete Barrier in Fire

As seen in numerous cases of plant accidents, there is a risk of fire and explosion in domestic plants. To mitigate this risk, concrete barriers installed around plant protection facilities are expected to be more effective in reducing fire damage compared to steel barriers. However, it is necessary to assess the temperature and radiant heat effects on the backside of the barriers during a fire. Therefore, in this study, a fire resistance test was conducted on a concrete barrier to evaluate the impact of radiation heat and temperature on the backside of the test specimen, and the range of radiation heat effect was predicted.

Probabilistic risk assessment of fire and explosion of onboard high-pressure hydrogen system

Hydrogen is regarded as a new energy carrier and has broad application prospects. As the leading field of hydrogen energy application, hydrogen fuel cell vehicles (HFCVs) are highly valued in the world. However, due to the flammable and explosive characteristics of hydrogen, its safety issues have attracted much attention, and it is increasingly necessary to understand the possible accident risks of the hydrogen system of HFCVs. In this study, the quantitative risk assessment (QRA) of hydrogen system of HFCV was carried out, and the Bayesian network (BN) analysis model of fire and explosion risk of onboard high-pressure hydrogen system was established. Taking a hydrogen system as an example, BN parameters are quantified based on three quantitative analysis methods: general data, logical judgment and computational simulation, and then the fire and explosion risk and personnel loss degree of the general onboard high-pressure hydrogen system are determined. The results show that when hydrogen release occurs, the probability of explosion is 6.79E-05, the probability of jet fire is 1.53E-04, and the probability of fireball is 5.38E-08. In the case of major damage, there is an 87.15 % probability that an explosion occurred; the reliability of safety protection devices is very important in the process of hydrogen use. It is suggested to optimize the structural layout design of safety components and improve the reliability of protection devices to promote the safe development of hydrogen energy industry such as HFCVs.

Accelerated aerobic oxidative α-hydroxylation of 2-methylcyclohexanone with imidazolium ionic liquids

The great demands of chemical industries for environmental-friendly process draw interests on ionic liquids of high boiling points and low explosion risks. In this work, the aerobic α-hydroxylation of 2-methylcyclohexanone accelerated by 1-alkyl-3-methylimidazolium ionic liquids (ILs) was explored, where the ILs increased the efficiency considerably. ILs could also work as solvent and be separated from reaction mixture by extraction with organic solvents afterwards, where the anion moiety of ILs had a great impact on the reaction. After reaction, ethyl acetate was proved to be well-performed to separate BmimBF4 for next use. Besides, the imidazolium cation moiety was proved to accelerate the reaction via 1HNMR and ATR-FTIR. For mechanistic study, an interaction between imidazolium cation and ketone was proposed and, moreover, supported by ESI-MS. This work should encourage the application and understanding of ionic liquids in aerobic oxidation.

Dynamic response and vibration modes of multi-layer wound cylindrical shell for hydrogen storage under external blast loading

Multi-layer wound cylindrical shells are the preferred structures for storage vessels working in high pressure and hydrogen atmosphere. However, they are susceptible to external blast loads from accidental hydrogen explosions. In order to study the response of such structures under external blast loading, a numerical model was developed, which combined a thermo-viscoplastic constitutive model and a fluid-structure coupling approach, and was subjected to external blast loads of different TNT equivalency weights. The strain responses and initial velocity fields of the structure were analyzed. A rigid-plastic theoretical model was also developed to calculate the maximum displacement of the inner shell and was compared with the simulation results. Moreover, the axial velocity vibration histories and dominant frequencies at different locations of the steel belts were numerically obtained. In addition, four vibration modes of the steel belts were presented in this paper. Furthermore, strain growth was observed in the high-frequency vibration area, and the possible reasons for the strain growth were analyzed and discussed in detail. The results will be useful for predicting the deformation modes of such multi-layer wound cylindrical shell structures under the risk of external hydrogen explosions.

Ventilation arrangement evaluation and proactive goaf inertisation for spontaneous combustion and gas explosion management during longwall panel sealing-off process.

When a longwall face approaches the finish-off line, 1month is normally required to relocate the longwall equipment and seal the longwall panel, during which time the goaf gas atmosphere changes and the risk of spontaneous combustion and gas explosion considerably increases. To minimise the occurrence of these hazards, an improved insight into gas flow dynamics within the longwall panel is essential during the panel sealing-off process. Based on mining conditions of an Australian underground coal mine, three-dimensional computational models were developed and calibrated with onsite gas monitoring data, allowing for evaluating ventilation arrangements and understanding methane dispersion in the longwall workings during the six-stage panel sealing-off process with confidence. The simulation results indicate that nitrogen should be injected on the travel road side at a distance of 120m behind the longwall face at a rate of 0.75 m3/s and the rear of the travel road should be tightly sealed at the final sealing-off stage, resulting in oxygen levels lowering than 5% in the longwall workings and producing desired panel sealing-off performance. In addition, gas sensors should be employed and positioned at the appropriate locations to reliably monitor goaf atmosphere change. This study sheds improved insights into evaluating ventilation arrangements and understanding gas flow dynamics during the panel sealing-off process and provides critical knowledge of effective proactive goaf inertisation strategies, thus minimising the risk of spontaneous heating and gas explosion and reducing environmental pollution induced by these hazards.

Investigations on methyl pentanoate-air mixtures confined explosion and cellularity

Combustible fuels like methyl pentanoate (MPe) could cause accidental explosions and fire. Therefore, MPe explosion characteristics have to be well characterized and understood for its safe and reliable use in industries and combustion devices. Considering this, MPe’s explosion pressure, maximum explosion pressure, rate of pressure rise, maximum rate of pressure rise, heat release rate, etc., were investigated in this study at the initial conditions of 1, 2, and 4 bar and 423 K, 453 K, and 483 K using the equivalence ratios of 0.7–1.4. The maximum explosion pressures and maximum rate of pressure rise of MPe increased as the initial pressures increased but the maximum rate of pressure rise was insignificantly affected by the initial temperature. The explosion duration decreased with a decrease in the initial pressure. The maximum heat release rate and deflagration index increased with increasing initial pressure. The MPe maximum deflagration index was 224.8 bar•m/s, which occurred at a higher initial pressure and fuel-rich mixture. Therefore, the explosion severity of MPe was enhanced at higher initial pressures and fuel-rich mixtures. Moreover, the flame cellularity study showed that MPe unstable flame crack length and cell number were more affected by increments in the initial pressure and equivalence ratio. Therefore, flame instability and cellularity would significantly influence explosion severity at higher pressures and equivalence ratios. This study’s findings provide first-hand data that could be used to further investigate and characterize MPe’s explosion risk.

Investigation on risk fields assessment in the longwall working face with single side roof cutting along the gob

AbstractThe number of mines using roof cutting and pressure relief technology to extract mine deep coal resources is increasing daily. Most of these mines are facing the risk of high gas emission and residual coal spontaneous combustion disasters, and the composite disasters caused by these two risks also threaten the safety of mine production. On the basis of constructing a model for the evolution of porosity and permeability in a single side roof cutting along the gob, this study studied the occurrence locations of gas explosion risk areas, oxidation and heating risk areas, and composite disaster areas under different air supply and gas emission conditions, and summarized the evolution laws of composite disaster risk areas. The research results show that the roof rock collapse caused by roof cutting and pressure relief technology reduces the permeability of porous medium, which significantly reduces the sensitivity of the width of the oxidation temperature rise zone and the composite disaster area to the air supply. The increase in air supply causes the position of the composite disaster risk zone inside the goaf to shift toward the deep part of the goaf, while the width remains basically unchanged. The increase in gas emissions has suppressed the occurrence of coal spontaneous combustion in the goaf, while also keeping the gas concentration in a large area outside the upper limit of gas explosion. The research content enriches the research system of gas and oxygen flow fields in the goaf cutting face, and has positive significance for the promotion and application of goaf cutting technology and the understanding of secondary disasters caused by it.

Research on risk assessment method of dust explosion in electrostatic powder coating firms

Due to the low ignition energy and high explosion pressure of the electrostatic powder coating used, the powder spraying industry is very susceptible to dust explosion. Based on the fundamental concepts of risk assessment and the actual procedure, this study develops a dust explosion risk assessment indicator system for electrostatic powder coating firms to address the shortcomings of existing dust explosion risk assessment methods in handling weight objectivity and information uncertainty. The index system includes three first-level indicators of dust explosion severity, possibility, and safety management, as well as 8 s-level indicators and 26 third-level indicators. The indicator weights are acquired using the Structural Entropy Weighting Method (SEWM), which increases the objectivity of the computing results. D numbers theory is used to handle uncertainty in expert evaluation data in the best possible way. Eventually, a thorough approach for evaluating the dangers of dust explosion in electrostatic powder coating operations is developed. It shows that the procedure is likely to produce assessment results that reflect reality. Therefore, the company's daily safety inspections are underpinned by on-site investigations and risk assessments of powder coating companies. The results are of great significance in improving the dust explosion prevention capability of firms.