Explosion Suppression Research Articles

A modified phosphorus-based inhibitor for dry water inhibitor and its chemical mechanisms in preventing benzoyl peroxide explosion

Dust explosions caused by benzoyl peroxide (BPO) pose a significant risk to the chemical industry, making the development of high-performance inhibitors essential. The effect of a novel inhibitor on the explosion behavior of BPO dust was studied through experiments and simulations. The chemical mechanism behind the suppressed BPO dust explosion was clarified. The primary explosion hazard of BPO stems from the instability of the oxygen–oxygen bond. To address this, a novel phosphorus-based dry water powder inhibitor, MAP-DW, was prepared which effectively captures key reactive radicals involved in the chain reaction. At the optimal explosion concentration of BPO, a concentration of 400 g/m3 of MAP-DW reduced the maximum explosion pressure and the maximum explosion pressure rise rate by 96.48 % and 99.58 %, respectively. The suppression effects of MAP-DW on the explosion of BPO dust include heat absorption, oxygen dilution, thermal insulation, and capture of key free radicals. The kinetic simulation results showed that the suppression cycle between phosphorus-containing substances captured key chain reaction radicals, and the coupled suppression among NH3, H2O, and phosphorus-containing substances dominated the suppression mechanism of MAP-DW on BPO dust explosion. This study provides new insights into the characterization and suppression of BPO dust explosion, while also supplying crucial data for the safe utilization of peroxides.

The characteristics and mechanism of NaHCO3 compound fly ash in suppressing gas explosions in pipeline networks

Gas has been widely concerned due to its importance in the industrial and energy fields. In order to improve the inhibition effect of gas explosion, under the self-constructed pipe network system, the inhibition of gas explosion by composite inhibitor of fly ash and NaHCO3 with different ratios was investigated, and the microscopic inhibition mechanism of the two kinds of powders on the explosion of gas was investigated based on the method of density functional theory and transition state theory from the perspective of molecular dynamics. The results show that: the composite powder explosion suppression is better than a single powder, explosion suppression effect with the increase in the proportion of the mass of NaHCO3 significantly improve the 5 groups of conditions NaHCO3 loading of 40% (by mass) is the best, this time, the explosion of the peak overpressure, the peak flame propagation velocity, the peak flame temperature compared to the maximum reduction in the percentage of the measures taken for the maximum of 74.42%, 81.93%, 68.71%. In addition, NaHCO3, fly ash effectively inhibit the key primitive reaction of gas explosion. When the temperature reaches a certain point, the two and O*, O2, OH* and H* reaction rate higher than the rate of CH4 oxidation chain reaction, the dominant reaction, the maximum difference in rate constants of 70.95, 58.81, 60.06, 44.94. The study of the transition from the macro-scale to the molecular level of the study, in-depth understanding of the mechanism of explosion suppression, to reduce the risk of explosion from the ground up, and enriches the Gas explosion prevention and control of the theoretical system, for the operators to provide a strong technical guarantee for safe production.

Experimental exploration of methane-coal dust explosion suppression by expandable graphite: From the point of view of pressure, flame, spectrum, and flow field

Expandable graphite (EG) has been proposed as a more efficient material for suppressing methane-coal dust explosions. The suppression effect was evaluated based on pressure, flame, spectrum, and flow field. The influence of particle size, expansion ratio, and suppressant concentration on the suppression effect was considered, and the suppression mechanism was analyzed. The explosion characteristics and OH* emission spectrum indicated that EG effectively suppressed methane-coal dust explosions. Higher concentrations, smaller particle sizes, and higher expansion ratios resulted in a stronger suppression effect. The influence of EG parameters on suppression effectiveness was ranked from highest to lowest in terms of the concentration, particle size, and expansion ratio. Schlieren imaging showed that EG can partially suppress the initial flame. However, the significant suppression effect occurs during the pressure-increase stage. The flow field was also analyzed using proper orthogonal decomposition. The results showed that EG suppressed flow-field fluctuations, with the mode coefficient trends aligned closely with the pressure-change curve.

Phase change materials as hydrogen explosion suppressants: An experimental and kinetic investigation

To investigate the potential application of phase change materials as H2 explosion suppressants, in the present work, the inhibition effect of Na2HPO4·12H2O, K2HPO4·3H2O, and Na2CO3·10H2O on H2 explosion were experimentally studied. The corresponding explosion suppression mechanism was calculated by using a comprehensive combustion model. Results showed that the selected phase change materials inhibited the H2 explosion, and Na2CO3·10H2O has the most significant effect for fuel-lean H2-air mixtures when 12 g was added. Of which the maximum explosion pressure (Pmax) and maximum rate of pressure rise (dp/dt)max were reduced by 26.6 % and 28.1 %, and maximum pressure increase time (tb) and peak pressure time(tc) were increased by 112.2 % and 120.3 %. The inhibition mechanism of Na2CO3·10H2O on H2 was revealed by numerical simulation. The adiabatic flame temperature (AFT) and laminar burning velocity (LBV) of H2-air mixture decrease with increasing hydrated salt addition, the free radicals H, O and OH have a decisive influence on the explosion process during which H decreases by 86.4 % at most. The chain initial reaction O + H2 ⇌ H + OH and the sodium-containing primitive reaction NaO + H + M ⇌ NaOH + M have the most significant influence on the combustion processes. The results of present work give a theoretical foundation for application the phase change materials in H2 explosion safety industry.

Experimental study on inhibiting methane-coal dust explosion by APP-diatomite composite explosion suppressant in the pipe network

To prevent and control the methane/coal dust compound explosion disaster, the APP-diatomite composite powder inhibition of methane/coal dust compound explosion experiments were carried out in the self-constructed pipe network. The composite powder was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The change rules of methane/coal dust composite explosion pressure and flame propagation velocity were analyzed using different compounding ratios of powders in several monitoring points. The results show that the composite powder exhibited irregular morphology and the APP powder is uniformly distributed on the diatomite porous mesh structure. When the APP loading on the surface of diatomite is 40 wt%, composite powder has the best effect on explosion suppression, with the peak maximum explosion overpressure and the peak maximum flame propagation velocity reduced by 71.5% and 92.2%, respectively. The explosion suppression mechanism is revealed through pyrolysis properties, explosion products, and chain reaction.

Suppression characteristics of water mist containing alkali metal compounds in natural gas explosions

The natural gas explosion in semi-constrained spaces seriously jeopardize public safety. Water mist containing additive is an important method to reduce the disaster intensity. However, in actual scenarios, the explosion usually propagates for a certain distance before entering the mist area, which is more difficult to suppress the explosion. Therefore, the self-designed experimental system was used to recognize the suppression effect of water mist containing alkali metal compounds under the simulated scenario. The results show that the flame propagation distance was significantly reduced, the shortest overfire range was decreased by 40.0 % compared with the water mist condition. The peak overpressure and pressure rise rate also showed a significant decrease, the maximum pressure drop rate reached 72.3 %. When the explosion flame entered the atomized region, the turbulent disturbance generated by the atomization accelerated the mixture of combustion zone and the unburned area, which increases the possibility of consuming free radicals. Compared with the KCl and NaCl, the mist containing K2CO3 and Na2CO3 share higher suppression capacity. This study provides scientific guidance for the practical application of water mist explosion suppression.

Explosion characteristics and suppression analysis of AlSi12 powder used in additive manufacturing

To prevent explosion accidents of AlSi12 powder during additive manufacturing, a 20- L spherical explosion apparatus was used to investigate the explosion characteristics of AlSi12 and the suppression effects of NaHCO₃. Additionally, thermal analysis, chemical composition, and surface morphology analysis of the explosion residues were conducted to clarify the suppression mechanisms. The results indicated that the explosion hazard of AlSi12 powder reached its maximum at a concentration of 750 g/m³, with an explosion pressure of 0.710 MPa and an explosion temperature of 801 °C. The addition of NaHCO3 at an inerting ratio of 2.6 effectively suppressed explosions across all concentrations of AlSi12 powder. NaHCO3 showed better inhibitory effects on higher concentrations of AlSi12, with greater suppression of explosion temperature compared to explosion pressure. Furthermore, incorporating NaHCO3 effectively inhibited the oxidation of AlSi12 dust clouds, increasing the apparent activation energy of AlSi12, thereby reducing the probability of explosion. Combined experimental analyses revealed that NaHCO3 effectively inhibits AlSi12 powder explosions through mechanisms such as heat absorption, prevention of heat transfer, radical capture, and reactant consumption. The consumed reactants are primarily the Al element in the alloy powder, while the Si element is largely unaffected. These findings provide valuable experimental data and theoretical support for preventing and controlling AlSi12 powder explosions.

Piperazine pyrophosphate-functionalized Ni-MOF metal framework: Fabrication and synergistic explosion suppression mechanisms

Dust explosion suppression is crucial for ensuring safe industrial operations. To explore composite explosion suppression powders with higher performance, piperazine pyrophosphate (PAPP)-functionalized nickel-based metal–organic framework (PAPP@Ni-MOF) synergistic suppression materials were designed and synthesized. The effectiveness of this suppressant in inhibiting the explosion flame and intensity of polypropylene (PP) dust was investigated using explosion flame propagation and explosion pressure test apparatus. The results indicate that the combination of N/P elements and Ni-MOF exhibits excellent catalytic carbonization performance. Adding 50 wt% PAPP@Ni-MOF can completely inhibit the propagation of PP explosion flames and the rise in explosion pressure. The maximum propagation distance of the explosion flame was reduced by 78.07 %, the overall flame propagation speed decreased by 84.54 %, and the maximum explosion pressure was reduced by 76.87 %. Through characterization experiments, the products before and after the explosion were analyzed. Combined with molecular dynamics (MD) simulation results, the efficient synergistic explosion suppression mechanism of PAPP@Ni-MOF for PP dust was revealed from the perspectives of thermal conduction isolation, key radical recombination, and volatile gas adsorption.

Effect of hydrogen concentration, initial pressure and temperature on mechanisms of hydrogen explosion in confined spaces

Hydrogen as a renewable clean energy raises industrial safety and environmental issues. Studying the mechanism of hydrogen explosion in confined space is significant for guiding the risk assessment and efficient use of hydrogen energy. This paper used a 20 L explosion chamber to explore the effect of initial concentration changes on the hydrogen explosion and verify the model, the CHEMKIN simulation software was used to qualitatively and quantitatively evaluate the dynamic behavior characteristics of hydrogen explosion in confined space under different initial conditions, and the variation law of physical process of hydrogen explosion under different influencing factors in confined space was revealed from macro-micro perspectives. This study shows that the maximum explosion temperature and pressure under fuel-rich conditions are generally higher than those under fuel-lean conditions. The induction period of the hydrogen explosion reaction gradually shortens as the initial pressure increases, there is a negative temperature coefficient effect of ignition delay at the initial temperature of 800 K. In addition, compared with the initial pressure, higher explosion temperature and faster reactant mixing speed significantly affect the gas explosion reaction rate. The molar fractions of free radicals H, O, and OH show an inverted V-shaped relationship with the initial hydrogen concentration, and there is a hysteresis phenomenon in the final molar fraction peak of H free radicals; Sensitivity analysis indicates that free radicals are mainly responsive to the intermediate reaction R16 (forward direction) and R9 (reverse direction), thereby affecting parameters such as explosion pressure and temperature. These research findings can provide theoretical support for developing hydrogen explosion suppression technology.

Experimental study of NaHCO3/modified vermiculite composite powder for methane explosion suppression

Using a self-constructed experimental platform with 9.5 % methane as the explosive gas, the effects of various masses of NaHCO3, vermiculite, and NaHCO3/modified vermiculite composite powders on the explosion pressure, flame propagation shape, and flame propagation velocity of methane were investigated. The composite powders’ thermal stability and surface microstructure were examined, along with the mechanism of explosion suppression, using thermogravimetric analysis, XRD analysis, and particle size analysis. By comparing various data, 50 wt% NaHCO3/modified vermiculite composite powder with a mass of 360 mg showed the best detonation suppression effect, with Pmax and (dP/dt)max reduced by 53.3 % and 87.1 %, respectively, and Pmax arrival time extended by 142.9 %. The flame disappearance time reached 467 ms, which increased by 165.3 %, and the maximum flame propagation speed decreased by 40 %. Methane explosion suppression is achieved by adding NaHCO3/modified vermiculite composite powder, which prevents flame propagation and breaks the methane explosion chain reaction by chemical and physical suppression of methane explosion.

Experimental and simulation studies on suppressing gas explosions with diverse atomized liquid droplets: Insights for improved safety in mining

Gas explosions represent a prevalent thermodynamic hazard in coal mining, significantly endangering worker safety and the operation's overall safety. Water mist stands out among various explosion suppression techniques due to its high heat absorption capacity and environmental sustainability, offering a promising avenue for application. This study introduces a custom-built pipeline gas explosion testing apparatus to investigate the suppression effects of different atomized liquid droplets on gas explosions. By collecting and analyzing experimental data from pressure sensors under varying conditions within the pipeline, we conduct a thorough comparison of the explosion suppression characteristics attributed to different atomized droplets. Based on this foundation, the Fluent software was used for numerical simulation research to further analyze the explosion suppression effects of different atomized droplets. Additionally, numerical simulations were conducted to optimize the nozzle arrangement. Our findings reveal that an increase in atomization pressure, leading to smaller droplet sizes, significantly mitigates the impulse of the gas explosion shock wave. This indicates a marked inhibitory effect of atomized droplets on gas explosions, with finer droplets showing enhanced suppression capabilities. The simulation results from the optimized nozzle arrangement can provide valuable guidance for on-site deployment. Through a combination of experimental and simulation data, this study conducts a qualitative and quantitative analysis of the suppression mechanisms offered by different atomized droplets, considering parameters such as explosion impulse, blast energy, and explosion indices. The insights gained provide a theoretical foundation for reducing the ring-breaking effect of gas explosions and enhancing explosion suppression strategies, which are crucial for ensuring the safety of coal mining operations.

Explosion suppression efficiency of gaseous phlegmatizing agents in suppressing outbreaks of methane-air mixture in the gas transmission system of coal mines

Explosion suppression efficiency of gaseous phlegmatizing agents in suppressing outbreaks of methane-air mixture in the gas transmission system of coal mines

Experimental Study on Explosion Characteristics of LPG/Air Mixtures Suppressed by CO2 Synergistic Inert Powder

In order to study the explosion suppression characteristics of LPG/air mixture by CO2 synergistic inert powder, explosion suppression experiments were conducted in a 20 L explosion device. The results show that the explosion suppression effect of NaHCO3 powder is prior to Al(OH)3 powder under the condition of no CO2 synergy. As the mass concentration of inert powder increases, the peak value of explosion pressure Pex and the peak value of the pressure rise rate (dP/dt)ex decrease, and the explosion suppression effect gradually enhances. Gas–solid two-phase inhibitors exhibit more significant inhibitory effects than single-phase inhibitors. Increasing the volume fraction of CO2 or the mass concentration of inert powder can improve the explosion suppression effect. The explosion suppression effect of CO2/NaHCO3 is significantly better than that of CO2/Al(OH)3. The research results have certain significance for the prevention and control of LPG explosion accidents.

Characteristics analysis of flame propagation and its coupling effect with other parameters in LPG pipeline

AbstractTo study the flame propagating characteristic and its coupling effect with other parameters in the LPG pipeline, a typical pipeline model with two equal‐length branches perpendicular to each other is designed for experiment and simulation. Then, gas explosion scenarios are experimentally tested and numerically simulated, which is followed by the analysis of flame shape changing with time and peak temperature changing with space. Results show that when passing through the bifurcation, flame propagates to vertical branch B in a sharp knife shape affected by the strong vortex, reflected airflow, and compressed pressure wave in the pipeline with a diameter of 0.125 m. At the monitoring point that is 0.4 m away from the bifurcation point, the peak temperature of the vertical branch B is 57.87% bigger than that of the horizontal branch C, and its arrival time is 80% longer than that of the horizontal branch C, due to the existence of flame in vertical branch B. What's more, in both branches, the coupling results between peak temperature and peak velocity agree very well with the growth function, while the coupling results between peak temperature and peak pressure agree well with the decay function, providing aids to the optimal layout design of industrial pipeline branches as well as to the explosion suppression measures.

Influence of sodium hydrogen carbonate, ammonium dihydrogen phosphate, and lignin-based explosion inhibitors on the sensitivity of coal dust explosion

In order to prevent coal dust explosions, this study developed a targeted environmentally friendly and efficient lignin-based explosion inhibitor. The effects of NaHCO3, NH4H2PO4, and lignin-based explosion inhibitors on the sensitivity parameters of coal dust explosions were investigated using a 20 L spherical vessel and a Hartmann tube for comparison. Furthermore, the explosion inhibition mechanisms of the three inhibitors were elucidated through SEM, conductivity, In Situ FTIR, TGA-DTG/DSC, and other testing methods. The results indicate that from the perspective of explosion sensitivity, ZA-L-NP exhibits better explosion inhibition effects than NaHCO3 and NH4H2PO4. The zeolite carrier of the composite explosion inhibitor has a fine porous structure, with some materials filling the pores of the zeolite, resulting in a rough surface of ZA-L-NP. The use of ZA-L-NP for explosion suppression has a minimal impact on the turbulent combustion rate of coal dust. Its poor conductivity provides an advantage in inhibiting coal dust explosions. All three inhibitors exhibit significant inhibitory effects on the OH functional groups in coal dust, with inhibition effects decreasing in the order of ZA-L-NP, NH4H2PO4, and NaHCO3. Using classical kinetic models, the activation energy (E) and pre-exponential factor (A) of coal dust with and without added explosion inhibitors were calculated. Analysis was conducted from the perspective of kinetic parameters such as mass residual, maximum burning rate, average burning rate, flammability discrimination index, and comprehensive combustion characteristic index. It was found that the zeolite and modified lignin (L-NP) in ZA-L-NP synergistically increased the activation energy of coal dust. The research results can provide theoretical basis for the effective prevention of coal dust explosions.

Modified space suspension bentonite-based powder for suppression dust explosion in moist conditions: Experimental testing and validations

Bentonite, a non-metallic mineral mainly composed of montmorillonite, has been found to be effective in preventing explosion propagations. However, it is prone to absorbing water, leading to the issue of solidifying into lumps (caking problems) and reducing its ability to entrain in the pressure front of an explosion for stopping propagation. In this paper, three different dispersion modification technologies for bentonite are proposed. The corresponding modified bentonite samples are prepared and treated in various moist environments to assess their moisture absorption properties. Subsequently, space suspension testing is performed using a designed dispersion test device. Additionally, pipeline explosion suppression tests are conducted for different samples. The flame length, flame development time and flame peak velocity of various modified bentonite-based powders are measured. Through comparisons, the optimal modified explosion suppression bentonite used in mines is selected. It is determined that the use of calcium-based bentonite with a cation exchange capacity 0.75 times modified by bisdodecyldimethylammonium chloride for insertion exhibits better dispersion effects. Such modified bentonite-based powder can also demonstrate effective explosion suppressions and holds potential for widespread application in practices of explosion controls in the future.

Real-time concentration detection of Al dust using GRU-based Kalman filtering approach

Kalman filter algorithms have been widely used in dust environment concentration detection systems. However, in industrial environments, methods such as KF and median filtering usually require about 10 s of detection time, which cannot meet the requirements of online real-time detection. For this reason, this present study proposes a framework that combines a gated recirculation unit (GRU) with the KF method to achieve online real-time detection of dust concentration. In this framework, the GRU is mainly responsible for handling dynamic and nonlinear characteristics and capturing instantaneous concentration trends. On the other hand, the Kalman filter utilizes its superior state estimation capability to provide more accurate system state estimation by fusing real-time predictions from GRU and sensor measurements. The results show that the KFGRU method is superior to the conventional linear filtering method with a response time of less than 2 s and can detect dust concentration online in real-time. In terms of prediction accuracy, the deviation value of the curve processed by the KFGRU method is only 0.334, which is a significant breakthrough compared with the Kalman filter algorithm 0.755, the sliding average method 0.843, and the median filter method 0.849 (the smaller the deviation value, the higher the prediction accuracy). This study provides a comprehensive and innovative approach for dust concentration monitoring in dust reduction and explosion suppression systems, which not only meets the real-time requirement but also makes important progress in explosion safety management. This will provide more reliable and advanced technical support for dust control and safety in industrial production processes.

Experimental study on the methane explosion suppression by ultra-fine water mist containing bacteria under degradation for five times.

In a semi-closed visualization pipeline, this experiment studied the inhibitory effect of ultra-fine pure water mist, ultra-fine water mist containing inorganic salt and ultra-fine water mist containing bacteria-inorganic salt on 9.8% methane explosion under five different quality of spray volume. Combined with the methane explosion suppression experiment, the ability of methane-oxidizing bacteria to degrade 9.8% of methane was studied in a simulated pipeline. Experiments showed that the addition of inorganic salt and the degradation of methane-oxidizing bacteria could improve the suppression explosion effect of ultra-fine water mist, and the suppression explosion effect was related to the volume of water mist. Under the same ultra-fine water mist condition, with the increase of the volume of water mist, the explosion suppression effect was improved. Compared with pure methane, pure water ultra-fine water mist, and inorganic salt ultra-fine water mist, the maximum explosion overpressure and flame propagation speed under the condition of bacteria-inorganic salt ultra-fine water mist were significantly reduced. Compared with the explosion of pure methane, due to the degradation of methane by methane-oxidizing bacteria, when the degradation time was 10 h, and the volume of ultra-fine water mist containing bacteria-inorganic salt was 12.5 mL, the maximum explosion overpressure dropped significantly from 0.663 to 0.343 MPa, a decrease of 48.27%. The appearance time of the maximum explosion overpressure was delayed from 208.8 to 222.6 ms. The peak flame velocity was 4 m s-1, which was 83.3% lower than that of 9.8% pure methane explosion. This study will contribute to the development of efficient ultrafine water mist synergistic inhibitors for the prevention of methane explosion disasters.

Comparative effectiveness of C3-Hydrocarbons and their mixtures on suppression of hydrogen-air explosions

The next-generation energy economy relies heavily on hydrogen. Handling hydrogen during production, storage, and transportation requires risk mitigation. In this regard, the application of halide-free additives is very crucial. The present study experimentally and theoretically investigates the individual and combined inhibiting effect of propane and propene on hydrogen-air explosions. The experiments are carried out at 298 K and 1 bar, with additives ranging from 0.5 to 5% for the individual and 1–2% each for the combined effect in the 20–50% hydrogen-air mixture. Experimentally, the additive content in the stoichiometric and rich mixture decreases the explosion pressure, maximum pressure rise (MPR) rate, laminar burning velocity (LBV), and flame temperature, while increasing minimum ignition energy. For instance, the addition of 2% propane in a 50% hydrogen-air mixture, reduces the MPR rate by 98%, whereas such an effect is observed with 2.5% propene. Theoretical study shows that 3% equivalent additive augments inhibiting reactions, countering the main flame-promoting reaction R1 (H + O2O + OH) and thereby reducing LBV. Due to its low activation energy, propene consumes the active radicals twice the rate of propane, while propane not only scavenges the active radicals but also promotes oxygen consumption in the prior phase of combustion, weakening flame propagation. Overall, this approach exhibits a significant step forward in harnessing the potential of hydrogen while mitigating the safety risks associated with its use.

NUMERICAL JUSTIFICATION OF THE LABORATORY TECHNIQUE FOR TESTING OF FIRE-EXTINGUISHING POWDERS

Improvement of firefighting means and methods for measuring their effectiveness are important tasks in the field of fire safety. The paper presents the results of experimental measurements of the minimum extinguishing concentration of powder mixtures that can be applied as effective explosion-suppressing barriers. Measurements of the minimum extinguishing concentration of the investigated powders were carried out using a laboratory method with their pulsed delivery to a microfire of class B using compressed air. In order to justify and assess possible errors of the mentioned laboratory method for measuring extinguishing efficiency, numerical 3D modeling of the interaction of a multiphase flow with a model combustion focus was performed. The analysis of the numerical modeling results has shown that, for the applied laboratory method, almost the entire portion of the investigated powder enters the combustion zone. Additionally, the numerical calculations indicate that under the specified experimental conditions, the particle size of the powder has no noticeable effect on their loss into the surrounding flame space. Thus, these results justified the use of the mentioned laboratory method for he comparative evaluation of fire-extinguishing powders with a wide range of dispersity. The application of this laboratory method for assessing the effectiveness of the fire-extinguishing powder allowed for the development of an optimal powder composition for explosion suppression, incorporating inert mineral particles as the main component and an additive of a chemically active potassium-containing combustion inhibitor.