Explosion Suppression Research Articles

Gas explosion suppression performance of modified gel-type dry waters

In this paper, the gas explosion (methane-air mixture explosion) suppression properties of the gel and modified dry water powders were investigated using a transient flame propagation system. The results revealed that the moisturising ability of dry water powders containing gel or ammonium dihydrogen phosphate (the chemical formula is NH4H2PO4, and its abbreviation is MAP) has been improved. The optimal explosion suppression performance was achieved when the concentration of MAP in the aqueous solvent was 10% and the dry water concentration was 520 g/m3. In a 10 vol% gas explosion, the gellan gum gel dry water, calcium alginate gel dry water, 10 mass% MAP–modified dry water, 10 mass% MAP–modified gellan gum dry water, and 10 mass% MAP–modified calcium alginate dry water decreased the maximum flame propagation velocity by 17.50%, 20.63%, 25.62%, 26.76%, and 28.44%, respectively; decreased the maximum flame temperature (as measured at a point in the lower part of the pipeline) by 37.84%, 42.47%, 45.55%, 46.31%, and 53.71%, respectively; and decreased the maximum explosion venting pressure by 6.43%, 9.16%, 13.77%, 16.50%, 21.08%, and 36.70%, respectively. According to thermogravimetric analysis, the mass losses of the MAP-modified dry waters during pyrolysis were greater than those of the unmodified dry waters. Studies have revealed that MAP-modified calcium alginate dry water can effectively suppress explosions and has a stable particle structure.

Performance and mechanism of bentonite in suppressing methane explosions in a pipeline network

Methane explosions threaten the safety of industrial security in modern society. To suppress such explosions, experiments were made through using different masses of bentonite power driven by CO2 within a pipe network set up in an independent way. The three factors, including the peak over-pressure of an explosion, the index of the explosion power, and the time length within which the first wave of flames reached the pipe network’s outlet, were measured to evaluate the performance. Moreover, an analysis on the mechanism of suppressing explosions was also conducted. According to the results, a gradual increase of the powder mass from 20 to 50 g could promote the effect of explosion suppression, but a further increase from50 g to 60 g only led to a slight improvement of the performance. Thus, it was concluded that the use of 50 g of bentonite powder worked best for the suppression of methane explosions when environmental conservation, energy saving as well as practicality were all taken into consideration. What was found in this study is supposed to shed theoretical light on how to transport methane safely with disaster risks reduced effectively.

A novel dry water with perfluorohexanone for explosion suppression of AlH3

AlH3 is a promising candidate for hydrogen storage, but has high explosion risk. To prevent the accident of AlH3, the novel dry water (DW) was applied to the suppression of AlH3 explosion, and the addition of perfluorohexone improved the suppression effect significantly. When the mass fraction of 16.70wt% perfluorohexanone-modified dry water (PMDW) was added with 700 g/m3, the maximum explosion pressure decreased by 54.37 %, and the maximum explosion pressure rising rate dropped by 98.80 %. The 3-dimensional network structure of silica, adsorbing flame radicals and preventing heat transfer, was proved to play a pivotal role in the explosion suppression by HRTEM and NMR. The evaporation and decomposition of the internal solution would greatly improve the cooling effect. CF2 captured H, O, and OH radicals in the flame and interrupted the free radical chain reaction. Our work is a step towards the application of eco-friendly DW in the field of explosion suppression.

Partial suppression of acetaminophen dust explosion by synergistic multiphase inhibitors

Drug powder explosions pose a potential threat to the process safety of pharmaceutical companies in the processing and storage of products. To explore a reasonable and efficient technology to prevent and mitigate the explosion of combustible drug dust, an experimental system of vertical combustion pipeline equipped with a partial suppression device was built, and the performance of N2 and CO2 loaded with hydrophobic SiO2 encapsulated SiO2 gel (HSESG) respectively to synergistically suppress the explosion of acetaminophen powder was investigated. The results demonstrated that N2/HSESG and CO2/HSESG were effective in reducing the flame average velocity (Vavg), maximum velocity (Vmax), velocity to the top of the pipe (Vtop), and maximum flame temperature (Tmax). N2 loaded with 60 wt% HSESG reduced the Vmax, Vavg, and Vtop of the explosion flame by 68.1%, 66.7%, and 81.3%, respectively, and Tmax by 58.7%. Acetaminophen dust explosion could be completely suppressed by CO2/40 wt% HSESG with 83.7%, 73.0%, and 85.7% decrease in Vmax, Vavg, and Vtop values, respectively, and 80.7% decline in Tmax. The results of thermal decomposition tests and residues characterization indicated that the partial suppression of N2/HSESG and CO2/HSESG was mainly accomplished through the synergistic interaction among thermodynamic, kinetic, and non-homogeneous chemical effects. Subsequently, the reason for the more pronounced suppression effect under the impact of CO2/HSESG was further explained.

Experimental study on CO2/CF3I suppression of methane-air explosion and flame propagation

To explore the inhibitory effects of CF3I and CO2 gas on the explosion pressure and flame propagation characteristics of 9.5% methane, a spherical 20 L experimental explosion device was used to study the effect of the gas explosion suppressants on the maximum explosion pressure, maximum explosion pressure rise rate and flame propagation speed of methane. The results indicated that with a gradual increase in the volume fraction of the gas explosion suppressant, the maximum explosion pressure of methane and maximum explosion pressure rise rate gradually decreased, and the time taken to reach the maximum explosion pressure and maximum explosion pressure rise rate was gradually delayed. At the same time, the flame propagation speed gradually decreased. Additionally, the time taken for the flame to reach the edge of the window and the time taken for a crack as well as a cellular structure to appear on the flame surface was gradually delayed. The fluid dynamics uncertainty was suppressed. The explosion pressure and flame propagation processes were markedly suppressed, but the flame buoyancy instability was gradually enhanced. By comparing the effects of the two gas explosion suppressants on the pressure and flame propagation characteristics, it was found that at the same volume fraction, trifluoroiodomethane was significantly better than carbon dioxide in suppressing the explosion of methane. By comparing the reduction rates of the characteristic methane explosion parameters at a volume fraction of 9.5%, it was observed that the inhibitory effect of 4% trifluoroiodomethane on the maximum explosion pressure was approximately 4.6 times that of the same amount of carbon dioxide, and the inhibitory effect of 4% trifluoroiodomethane on the maximum explosion pressure rise rate and flame propagation speed was approximately 2.7 times that of the same amount of carbon dioxide. The addition of 0.5%–1.5% trifluoromethane to 4% and 8% carbon dioxide can improve the explosion suppression efficiency of carbon dioxide. This enhancing phenomenon is a comprehensive manifestation of the oxygen-decreasing effect of carbon dioxide and the trifluoroiodomethane-related endothermic effect and reduction in key free radicals.

Study on flame propagation characteristics of coal dust explosion in horizontal straight pipe

AbstractCoal dust explosion is one of the common accidents in mines. The flame generated in the explosion process spreads rapidly, and the high-temperature flame will cause personal injury and equipment damage in the working environment. In order to study the flame propagation characteristics of coal dust explosion, four kinds of coal dust explosion flame propagation experiments were carried out by using the intelligent coal dust explosion identification device, and the flame propagation process was simulated by computational fluid dynamics (CFD) simulation. The results show that the flame length of lignite dust explosion is obviously longer than that of long flame coal, non-caking coal and gas coal. From the ignition of lignite coal dust, the flame length increases continuously, reaches the maximum of 52 cm at a certain time and then gradually decreases to 0. While the flame length increases, the flame propagation rate also experiences the propagation process of accelerating and decelerating. By comparing the explosion flame length obtained by CFD numerical simulation with the experimental results, it is found that the simulation error is within the acceptable range. Further statistical analysis is made on the simulation results of overpressure generated by explosion, and it is found that the change law is consistent with the theoretical formula, so as to further verify the feasibility of numerical simulation for explosion research. The research results lay a theoretical foundation for predicting the disaster scope of coal dust explosion accidents, and have practical significance for taking explosion suppression and flameproof measures in mines.

Gas explosion suppression by ammonium dihydrogen phosphate-modified dry water powder

Dry water materials have high-efficiency and green characteristics. Dry water powder was prepared, and explosion suppression experiments were conducted using a flame propagation experimental system. The influence of dry water powder quality and MAP concentration on gas explosion characteristics were investigated. According to the experimental results, compared with unmodified dry water powder, MAP-modified dry water powder had an 11.66% higher moisture retention rate, 14.27% lower thermogravimetric mass loss, and 8.43% lower maximum mass loss rate. When the dry water powder concentration exceeded 260 g/m3, the gas explosion inhibition effects increased with the dry water powder concentration. When the MAP concentration was 0%–20%, the gas explosion suppression effect increased and then decreased as the MAP concentration increased. When the MAP concentration was 10%, the optimal explosion suppression effect was achieved. Adding 520 g/m3 MAP (10 mass%)–modified dry water powder reduced the maximum flame temperature at thermocouples #1 and #2 by 39.11% and 43.95%, respectively, and Vmax decreased by 20.63%. The MAP-modified dry water powder had a physical–chemical inhibition mechanism, and the gas explosion suppression performance was substantially enhanced. Thus, a new high-efficiency gas explosion suppression material was obtained. This research highlighted the importance of coal mine safety in relation to gas explosions and supported dry water material use in coal mines.

Wireless Sensor Network-based Detection of Poisonous Gases Using Principal Component Analysis

This work utilizes a statistical approach of Principal Component Analysis (PCA) towards the detection of Methane (CH4)-Carbon Monoxide (CO) Poisoning occurring in coal mines, forest fires, drainage systems etc. where the CH4 and CO emissions are very high in closed buildings or confined spaces during oxidation processes. Both methane and carbon monoxide are highly toxic, colorless and odorless gases. Both of the gases have their own toxic levels to be detected. But during their combined presence, the toxicity of the either one goes unidentified may be due to their low levels which may lead to an explosion. By using PCA, the correlation of CO and CH4 data is carried out and by identifying the areas of high correlation (along the principal component axis) the explosion suppression action can be triggered earlier thus avoiding adverse effects of massive explosions. Wireless Sensor Network is deployed and simulations are carried with heterogeneous sensors (Carbon Monoxide and Methane sensors) in NS-2 Mannasim framework. The rise in the value of CO even when CH4 is below the toxic level may become hazardous to the people around. Thus our proposed methodology will detect the combined presence of both the gases (CH4 and CO) and provide an early warning in order to avoid any human losses or toxic effects.

Suppression effect of CaCo3, NaCl, and NH4H2PO4 on gas-fat coal dust explosion pressure and flame characteristics

Coal dust explosion is a major accident affecting the safety of coal mine production. In order to control coal dust explosion, using inert dust to suppress explosion is one of the effective methods. Taking the gas-fat coal as the research object and CaCO3, NaCl, and NH4H2PO4 as the inert dust, the suppression effect of inert dust on gas-fat coal dust explosion pressure and flame is studied. It is found that when the gas-fat coal dust particle size is 48~58 ?m, both the maximum pressure and the farthest distance of flame reach the maximum value. Among the three inert dusts, NH4H2PO4 has the best suppression effect, followed by NaCl, and CaCO3 has the worst suppression effect on explosion. The smaller the particle size of

Study on inhibition effect and mechanism of NH4H2PO4 on explosion of titanium powder

In order to effectively inhibit the explosion of titanium powder, this study used the Hartmann tube experimental system and the 20 L explosion tank experimental system to carry out flame propagation and explosion overpressure experiments, respectively, and the effect of NH4H2PO4 on the explosion suppression of titanium powder was studied. The results show that when the addition of NH4H2PO4 powder is 50%, the flame propagation velocity and explosion pressure can be reduced to the minimum, and the explosion pressure can be basically suppressed. Finally, the inhibition mechanism of NH4H2PO4 on the explosion of titanium powder was analyzed. The endothermic decomposition of NH4H2PO4 absorbed the energy needed by the explosion of titanium powder. Oxides produced by the decomposition of NH4H2PO4 powder cover the surface of titanium powder, increase the thickness of the oxide film, and play a role of heat insulation; the gaseous water produced by the decomposition of NH4H2PO4 powder reduces the concentration of oxygen in the air and increases the difficulty of the explosion reaction. NH4H2PO4 powder traps the free radicals needed for the explosion to block the chain reaction.

Study of Methane Explosion Suppression Characteristics of N2 and CO2 in Variable Cross-Section Ducts.

To investigate the effect of concentration of N2 and CO2 (0, 10, 20, 30, 40, and 50%) on the flame propagation characteristics of CH4/air premixed gases with stoichiometric ratios in variable cross-section ducts, experiments were conducted in four combinations of ducts at initial conditions of 298 K and 1 atm. The results show that the flame propagation velocity, propagation time, and overpressure are greater in the suddenly contracted duct than in the suddenly expanded duct if the dimensions of the ducts are kept constant. However, an increase in inert gas concentration leads to a decrease in flame propagation speed, an increase in flame propagation time, and changes in flame structure and pressure. "Tulip" flames appeared when a duct with a cross section of 100 mm × 100 mm was combined with a duct with a cross section of 70 mm × 70 mm, whether N2 or CO2 was added or what its concentration was. However, when a duct with a cross section of 140 mm × 140 mm was combined with a 70 mm × 70 mm duct, a "tulip" flame is formed only at a CO2 concentration of 50%. As the concentration of inert gas increases, the explosion pressure first decreases and then stabilizes, while the rate of pressure increase showed a monotonically decreasing trend. The explosion pressure is minimized when the concentration of CO2 and N2 is 30 and 40%, respectively.

Experimental Study of the Metal Foam Suppression Effect on the Gas Deflagration and Detonation

ABSTRACT The study investigated the deflagration and detonation suppression effect by different thicknesses of metal foam. The results show that the gas explosion suppression effect of metal foam is related to the explosion stage and the metal foam thickness. In the deflagration stage, the flame could be quenched by 10 mm, 20 mm, and 30 mm thick metal foam. In the flame acceleration stage, the flame can only be quenched by the 30 mm thick metal foam. In the detonation stage, detonation could be completely quenched by 20 mm or 30 mm thick metal foam. Ten-millimeter-thick metal foam could make detonation stage convert into deflagration stage and overpressure decreases obviously. Different propagation mechanisms of deflagration and detonation lead to different suppression effects of foam metal.

Analysis on research trends with dust explosions by bibliometric approach

Highly destructive combustible dust explosions, which is prone to cause secondary explosion, has been a concern in industrial processes. To understand the current development and status of research on dust explosions, 1276 publications related to dust explosions from 1998 to 2021 were indexed through the Web of Science Core Collection database. CiteSpace and VOSviewer were used to visualize and analyze the collected literature information. The number of articles related to dust explosions has increased from 12 in 1998 to 191 in 2021. China, the United States, and Canada are the major contributors in this field. Dalhousie University, Beijing Institute of Technology, and Dalian University of Technology are at the core of dust explosion research. Wei Gao, Paul Amyotte, and Chi-Min Shu are the most prolific researchers. Journal of Loss Prevention in the Process Industries, Powder Technology, and Process Safety and Environmental Protection are the major sources of publications related to dust explosions. The research topic of dust explosions mainly evolves into four aspects: explosion characteristics and influencing factors, research media, explosion suppression, and numerical simulation. New research hotspots have appeared related to gas–dust hybrid mixtures, nanomaterials, and powder suppressants. The results can help researchers in the dust explosion field to quickly determine the research frontier and the overall situation.

Experimental study on methane explosion suppression by heptafluoropropane drived modified ABC powder

The accidental methane explosion accident will not only pose a serious threat to the safety of industrial processes, but also cause serious environmental pollution with excessive carbon emissions and greenhouse effect. Therefore, this paper has studied the inhibition effect of modified ABC powder driven by heptafluoropropane on methane explosion. Multiple methane explosion suppression experiments were carried out using a 3.2 L horizontal experimental pipeline under various working condition. The experimental results demonstrate that the modified ABC powder has a certain inhibitory effect on methane explosions, but the explosive suppression effect of the powder improves when heptafluoropropane is used as the driving gas. When 3∼4 % heptafluoropropane is used as the driving gas, the flame is obviously inhibited. The deformation degree of flame shape is the largest at 4 % concentration. The flame totally folds inward at this point, forming an uneven finger flame. When 4 % concentration of heptafluoropropane drives the powder, there is a critical value of the concentration of the powder, which is 0.06 g/L. According to the characterization results, the average particle size of the modified ABC powder is less than 5 µm. It has good dispersibility and pyrolysis effect and is not easy to agglomerate. Under the driving action of heptafluoropropane, the powder will form aerosol, which can fully contact and react with the flame. The inert gas around the powder will reduce the forward speed of the flame and ensure that the flame and powder can fully contact and react. The combination of the two has a good synergistic effect and can effectively inhibit methane explosion.

Experimental study on the suppression of coal dust explosion by silica aerogel

Silica aerogel (SiA) is prepared using environmentally friendly material diatomaceous earth and its effect on coal dust explosion is studied. The coal dust explosion characteristics experiments are carried out in a 20 L spherical explosion tank and dust explosion flame propagation experimental system, and the coal dust explosion products are analyzed by FTIR and XPS test methods. The results showed that after adding 50% SiA, the maximum explosion pressure of coal samples decreased from 0.3813 MPa to 0.1854 MPa, (dp/dt)max decreased from 10.955 Mpa/s to 4.082 Mpa/s, weakening by 62.74%, and the flame propagation height decreased from 567.57 mm to almost no flame propagation observed; using the Coats- Redfern method to calculate the activation energy of coal and SiA in the slow reaction stage of 30.353 kJ/mol and 21.159 kJ/mol, indicating that SiA preferentially consumes oxygen in the confined space, slowing down the oxidative pyrolysis of coal; SiA attenuates the impact energy generated by the explosion, protects part of the functional groups of coal from being destroyed, and inhibits the decomposition of some C elements in coal; proposes reduce the thermal radiation effect and decompression deceleration coupling effect to describe the inhibition mechanism of SiA on coal dust explosion.

Explosion Flame and Pressure Characteristics of Nonstick Coal Dust and the Inhibition of Explosion Suppressants

Nonstick coal is widely distributed in the world and is an important resource for human beings. The explosion characteristics and explosion suppression of nonstick coal dust are increasingly concerning. In this paper, the flame and pressure characteristics of a nonstick coal dust explosion are studied, and the suppression effect of SiO2, KCl, and NH4H2PO4 on the explosion is analyzed. It is concluded that the maximum propagation distance of a nonstick coal dust explosion flame is 0.59 m, the maximum pressure is 0.63 MPa, and the maximum pressure rise rate is 40.79 MPa/s. The explosion suppression effect of SiO2 is worse than that of KCl, but the inhibition effect of NH4H2PO4 is the best among the three kinds of explosion suppressants. When the mass percentage of NH4H2PO4 dust mixed with coal dust is 70%, the coal dust explosion is completely suppressed. It absorbs a certain amount of heat to promote the chemical reaction, which plays a certain role in controlling the explosion process, and its explosion suppression mechanism includes both physical and chemical explosion suppression.

Experimental study on the multi-level suppression of N2 and CO2 on hydrogen-air explosion

The multi-level suppression of the hydrogen-air explosion by non-premixed N2 and CO2 in a closed duct was experimentally investigated. The multi-level suppression effect of inert gas on hydrogen-air explosion was discussed by comparing explosion parameters such as explosion pressure, the rate of pressure rise, combustion duration and flame propagation. The results showed that the inert gas adjacent to the explosion zone played a major role in explosion suppression. Compared to single-level explosion suppression, the multi-level explosion suppression was not obvious for inhibitors on the same side, while the multi-level explosion suppression was most efficient for inhibitors on different sides. Moreover, the turbulent development of the flame would exacerbate the explosive reaction, which could not be avoided. The experiment in this paper had great practical significance, and the experimental results could provide data support and theoretical guidance for the safe utilization of hydrogen and the effective suppression of hydrogen-air explosion.

Explosion suppression range and the minimum amount for complete suppression on methane-air explosion by heptafluoropropane

A visual explosion test system consisting of a 20 L explosion vessel and a horizontal pipeline of 6.5 m in length was adopted. The effects of heptafluoropropane (CF3CHFCF3) on methane-air explosion pressure, explosion flame structure and propagation velocity under different spraying ranges and amounts were systematically studied, and the suppression mechanism of CF3CHFCF3 on the methane-air explosion was analyzed. The experimental results show that the spraying range and amount of CF3CHFCF3 have a significant impact on the methane-air explosion. The presence of CF3CHFCF3 can promote the propagation of methane flame and increase the flame brightness under certain conditions. The reasonable setting of the spraying range and amount of CF3CHFCF3 can significantly weaken the explosion pressure of various parts in the pipeline. In the case of the same spraying amount of CF3CHFCF3, a larger CF3CHFCF3 spraying range not necessarily achieves the better the explosion suppression effect. Experimental analysis shows that in this experimental system, the explosion suppression effect of different spraying ranges from strongest to weakest at 1.72, 2.32 and 1.12 m, the minimum spraying amounts that can prevent 9.5 % methane-air premixed gas in the explosion suppression zone explosion flame propagation are 300, 300 and 360 mL, respectively.

Experimental and numerical study on the explosion suppression of hydrogen/dimethyl ether/methane/air mixtures by water mist containing NaHCO3

The explosion suppression effect of NaHCO3 water mist on the H2/DME/CH4/air mixtures was experimentally investigated. Pressure data and flame images were recorded by a pressure sensor and a high-speed camera, respectively. The suppression mechanism of NaHCO3 water mist was further studied using a developed kinetic model. Results showed that the normalized laminar flame speed calculated by kinetic model agreed well with the experimental data. The suppression effect of NaHCO3 water mist on the H2/DME/CH4/air mixtures explosion was significantly affected by fuel compositions, equivalence ratios and NaHCO3 concentrations. For stoichiometric mixtures (Φ = 1.0), the decreasing rate of the average flame propagation speed of CH4-enriched flames can be up to 84.9%, which is higher than that of DME-enriched flames and the H2-enriched flames. For DME-enriched flames, the decreasing rate of the average flame propagation speed of fuel-lean flames can also be up to 70%. Meanwhile, the maximum explosion pressure of the CH4-enriched flames and fuel-lean flames are more sensitive to the NaHCO3 water mist. The NaHCO3 water mist can suppress hydrodynamic instability while it has little effect on diffusional-thermal instability. The chemical kinetic model revealed that both the adiabatic flame temperature and the maximum mole fraction of (H + OH) can be decreased noticeably by NaHCO3 water mist. Sensitivity analysis indicated that NaOH + H = Na + H2O and Na + OH + M = NaOH + M are the dominant reactions of sodium-containing species for suppressing laminar flame speed. Reaction pathway analysis indicated that Na <=> NaOH suppression cycle is effective to reduce H and OH free radicals.

Study on mechanism and dynamics of inert powder explosion inhibitor inhibiting aluminum powder explosion

• The suppression of aluminum powder explosion by inert powder is compared for the first time. • The comparative study shows the advantages of synergistic inhibition of MPP powder. • The modal free function method is used to calculate and verify the dynamic model for the first time. • The inhibition mechanism of MPP explosion inhibitor on aluminum powder explosion is revealed. In order to study the suppression performance and action mechanism of inert powder on aluminum powder explosion flame, using the dust explosion flame propagation test system, five kinds of common inert powder and two kinds of aluminum dust with different particle sizes were selected for explosion flame suppression and overpressure suppression experiments. Combined with the thermal characteristic curve of inert powder, the inhibition performance and action mechanism of inert powder on aluminum powder explosion were systematically studied. The results show that the inhibition effect of MPP dry powder on aluminum dust is better than that of NaHCO 3 , CaCO 3 , Al(OH) 3 and NH 4 H 2 PO 4 ; The inhibition mechanism model of inert powder on aluminum powder explosion flame is established, and the action mechanism is analyzed. The oxidation process of aluminum dust with and without MPP dry powder was analyzed by Coats Redfern (C-R) method, and the activation energy and kinetic models of different stages were obtained. The results were verified by Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) methods. The research results can provide a theoretical basis and basis for the explosion suppression design of aluminum dust and the development of explosion suppression powder.