PVDF球形多孔材料的抑爆性能研究

为分析聚偏氟乙烯(PVDF)球形多孔材料对管道内甲烷-空气预混气体的抑爆性能，自主搭建气体爆炸测试平台，试验研究球形多孔材料填充密度及填充方式等因素对甲烷-空气预混气体爆炸的影响机制。结果表明：与空爆相比，填充多孔材料后，管道内爆炸超压及最大爆炸超压上升速率均明显降低；对甲烷-空气的抑制效果与材料的填充密度呈正相关，当填充密度为0.077 g/cm³时，球形多孔材料对爆炸超压的抑制率达到54.7%,最大爆炸超压上升速率降低了58.3%;改变材料的填充方式显著影响管道内的气体爆炸超压，采用分散填充的方式增强了多孔材料对最大爆炸超压的抑制作用，在填充密度(为0.038 5 g/cm³时)不变的情况下，对管道末端气体最大爆炸超压的抑制率达到66%。说明改变材料填充密度和填充方式均会影响多孔材料对甲烷-空气预混气体爆炸的抑制效果。     

CO_2抑制甲烷-空气链式爆炸微观机理的仿真分析

为从分子角度研究CO2在甲烷爆炸过程中的作用以及抑制机理,应用Gaussian 09软件,运用密度泛函(DFT)理论的B3LYP/6-31G方法,对用相关基元反应作仿真定量分析和仿真热力学与动力学分析。通过假设和验证,初步揭示CO2在甲烷爆炸过程中的抑制机理。结果表明,CO2是以稳定的第三体存在,未参与原子交换反应,但CO2促进了甲烷爆炸链引发中的甲基自由基的结合反应,降低了关键自由基甲基的浓度,中断了甲烷爆炸链,同时乙烷的氧化反应不会强化甲烷的爆炸反应。     

草酸盐粉体抑制甲烷爆炸的试验研究

为了研究草酸盐粉体抑制甲烷爆炸特性,选取草酸钾、草酸钠、草酸亚铁3种较为常见的草酸盐粉体作为抑爆材料,分析了草酸盐粉体作用下的甲烷爆炸特性。结果表明,3种草酸盐粉体均具有一定的甲烷爆炸抑制作用,其抑爆作用由强到弱依次为草酸钾、草酸钠、草酸亚铁。草酸钾、草酸钠和草酸亚铁的最佳抑爆粉体质量浓度分别为0.22g/L、0.26 g/L和0.26 g/L,最大爆炸压力的降幅分别为33.25%、30.03%和20.83%。结合热重分析和甲烷爆炸抑制特性,探讨了草酸盐粉体的甲烷抑爆作用机理。     

纳米粉体抑制矿井瓦斯爆炸的实验研究

针对目前粉体抑爆剂抑制矿井瓦斯爆炸的局限性,采用自主改进的20 L近球型瓦斯抑爆实验系统进行纳米粉体的抑爆实验。其结果表明:同微米级粉体相比,纳米粉体的抑爆效果更好,甲烷最大爆炸压力、压力上升平均速率分别下降了70.5%和90%以上,爆炸压力峰值时间延长了3倍多;依据纳米粉体表面效应理论,从对爆炸过程中自由基的抑制作用分析了纳米粉体特殊的阻燃抑爆作用,并对纳米粉体及相关技术抑爆进行了展望。     

甲烷含量对塑料粉尘空气混合物爆炸特性的影响

为探究可燃气体的添加对塑料粉尘/空气混合物爆炸特性的影响,以聚甲基丙烯酸甲酯(PMMA)和热塑性聚氨酯弹性体(TPU)2种塑料粉尘为研究对象,在对其进行热重分析(TG)的基础上,利用20 L球形爆炸试验装置,研究甲烷体积分数对这2种塑料粉尘/空气混合物爆炸压力、爆炸压力上升速率、爆炸下限等特征参数的影响。热重试验结果表明:PMMA粉体分解速率高,在外界供热条件下易发生燃烧,而TPU粉体分解所需能量更多,分解更加困难。爆炸试验结果表明:在试验选定的粉尘浓度条件下,2种粉尘爆炸压力及压力上升速率均随粉尘浓度呈现先升高后降低的变化趋势;当甲烷体积分数从0增加到4%时,塑料粉尘爆炸的猛度和敏感度随之增加,其中PMMA粉尘爆炸猛度受甲烷影响更大,而TPU粉尘基本不受影响,但其爆炸下限下降更明显。     

氩气协同超细水雾抑制甲烷爆炸试验研究

为加强超细水雾对甲烷爆炸的抑制效果,搭建小尺寸半封闭甲烷爆炸试验平台,开展氩气协同超细水雾抑制甲烷爆炸试验。通过单因素和曲面优化试验,测试氩气、超细水雾以及两者的协同作用对甲烷爆炸的抑制效果;从火焰特性、最大爆炸超压和平均升压速率3个方面探究氩气和超细水雾协同抑爆的优越性。结果表明:氩气和超细水雾协同抑制甲烷爆炸效果显著;随着氩气体积分数和超细水雾喷雾量的增加,火焰冲出管道的时间逐渐延长,最大爆炸超压和平均升压速率逐渐降低;其中氩气体积分数10%、超细水雾喷雾量4.2 m L的工况抑制效果最佳;甲烷最大爆炸超压较氩气和超细水雾单独作用下分别下降6.15和2.68 k Pa,说明氩气和超细水雾抑止甲烷爆炸具有协同效应。     

ABC干粉抑制瓦斯爆炸的实验研究

为测定ABC干粉对瓦斯爆炸的抑制作用,采用容积为20L的近球形抑爆实验系统,粒径为20.76μm,主要成分为高聚合度磷酸铵盐的ABC干粉进行瓦斯抑爆实验。实验结果表明：ABC干粉的添加能够降低瓦斯爆炸的压力;粉体浓度为0.10g/L时,抑爆效果最好;粉体的抑爆效果,不仅与粉体浓度有关,还与爆炸性混合气体中的甲烷浓度有关;点火延迟时间越长,粉体抑爆效果越差。     

喷粉压力对KHCO_3冷气溶胶甲烷抑爆效果影响研究

为实现主动式喷粉抑爆系统的最佳抑爆效果,基于5 L管道爆炸试验平台,测试喷粉压力对碳酸氢钾(KHCO_3)冷气溶胶分散状况的影响,并开展KHCO_3冷气溶胶对于9.5%甲烷-空气预混气体爆炸的抑制试验,考察了不同喷粉压力下形成的KHCO_3冷气溶胶对甲烷爆炸压力及火焰传播的抑制效果。结果表明:喷粉压力显著影响KHCO_3冷气溶胶的分散状况,进而影响其甲烷抑爆效果,KHCO_3冷气溶胶在低喷粉压力下难以分散且抑爆效果不佳,仅对前期火焰产生抑制作用;随着喷粉压力增加,KHCO_3冷气溶胶抑爆效果逐渐提升,甲烷爆炸火焰传播减缓,最大爆炸压力降低;但当KHCO_3冷气溶胶得到充分分散时,继续增加喷粉压力对其抑爆效果提升很小。     

湍流状态下甲烷爆炸特性的实验研究

利用20L近球形气体爆炸反应装置,测试甲烷在宏观静止和湍流两种不同状态下的爆炸特性。实验结果表明:甲烷的爆炸极限受其流动状态的影响不明显;湍流状态下甲烷爆炸压力Pm和爆炸压力上升速率(dp/dt)m较宏观静止状态明显增大,爆炸压力峰值时间tm明显缩短,其中爆炸压力上升速率受湍流影响较为显著;甲烷浓度不同,其爆炸受湍流影响的程度也不同,较高浓度(11%～16%)时的Pm受湍流的影响程度较大,越靠近最佳浓度(dp/dt)m和tm受湍流的影响程度越大;同一浓度下Pm和(dp/dt)m随着湍流的加强而增大,tm则缩短。该研究表明,避免和减少湍流对矿井瓦斯爆炸过程的抑制具有重要作用。     

基于Gaussian的甲烷爆炸微观反应计算分析*

为从微观热力学及动力学角度更深入了解甲烷爆炸微观反应机理,应用Gaussian软件DFT理论,B3LYP-D3(BJ)/6-31+G*水平对利用敏感性分析方法得出的甲烷爆炸反应简化机理中各驻点进行结构优化与频率计算,在M06-2X/def2-tzvpp水平上计算单电能,得到反应物、中间体、过渡态、产物的稳定构型及其参数、热力学数据,并计算得到各反应的焓变、吉布斯自由能变及自由能垒。研究结果表明:甲烷爆炸微观反应机理中基元反应1,9无过渡态,其他反应存在过渡态;基元反应1,4等为反应体系提供热量,保证甲烷氧化反应不断进行,反应1放热最多,焓变为-433.7 kJ·mol-1;关键自由基OH·的生成是反应3 O2+H·→OH·+O·与反应4 O·+H2→OH·+H·相互协同与促进的结果;反应3 O2+H·→OH·+O·为该甲烷爆炸机理的决速步,自由能垒为312.4 kJ·mol-1。研究结论可为深入研究甲烷爆炸微观反应机理和化学抑爆机理提供借鉴。     

Synergistic suppression effects of flame retardant,porous minerals and nitrogen on premixed methane/air explosion

A novel composite inhibitor based on porous mineral materials and conventional flame retardant of ammonium polyphosphate (APP) is prepared to suppress the premixed methane/air explosion. Taking advantages of gas and powder inhibitor, N₂ and the prepared composite inhibitor are combined to use. The suppression performance of N₂-composite inhibitor on methane explosion is investigated on a 20-L spherical experimental explosion apparatus and the characteristic pressure data are obtained. The combined inhibition effects of N₂ and the prepared composite inhibitor are greater than either acting alone. Thermal decomposition behavior and gaseous products of composite inhibitor are analyzed with thermogravimetric analysis and thermogravimetric-mass spectrometry, respectively. Based on physical and chemical actions, the inhibition mechanisms of N₂-composite inhibitor system are proposed. This work provides a reference to prepare high-performance gas explosion inhibitor based on the synergism of binary or multiple components.     

Inhibition effects of Al(OH)3 and Mg(OH)2 on Al-Mg alloy dust explosion

To identify a superior explosion suppressant for Al-Mg alloy dust explosion, the inhibition effects of Al(OH)₃ and Mg(OH)₂ powders on Al-Mg alloy explosion were investigated. A flame propagation suppression experiment was carried out using a modified Hartmann tube experimental system, an explosion pressure suppression experiment was carried out using a 20-L spherical explosion experimental system, and the suppression mechanisms of the two kinds of powders on Al-Mg alloy dust explosion were further investigated. The results demonstrate that by increasing the mass percentages of Al(OH)₃ and Mg(OH)₂, the flame height, flame propagation speed and explosion pressure of deflagration can be effectively reduced. When 80% Mg(OH)₂ powder was added, the explosion pressure was reduced to less than 0.1 MPa, and the explosion was restrained. Due to the strong polarity of the surface of Mg(OH)₂, agglomeration easily occurs; hence, when the added quantity is small, the inhibition effect is weaker than that of Al(OH)₃. Because the Mg(OH)₂ decomposition temperature is higher, the same quantity absorbs more heat and exhibits stronger adsorption of free radicals. Therefore, to fully suppress Al-Mg alloy explosion, the suppression effect of Mg(OH)₂ powder is better.     

Experimental study on the suppression of gas explosion using the gas–solid suppressant of CO2/ABC powder

Gas explosion is the leading accident in underground coal mining in China. Using the self-improved 20 L spherical experimental system, the impacts of 8% CO₂, ABC powder at various concentrations and mixture of them on the suppression of mine gas explosion were investigated. The results indicate that cooperative synergism exists between ABC powder and CO₂. Their combination has a better effect than each of the two components acting alone, especially for the gas of larger concentration. When 0.25 g/L ABC powder was mixed with 8% CO₂, the explosion limits were reduced by about 55%, the time to reach the peak explosion pressure was prolonged 3.56 times on average. Meanwhile, the maximum explosion pressure declined on an average of 59.4% and the maximum explosion overpressure rising rate decreased on an average of 91.1%. A combination of 0.20 g/L ABC powder and 8% CO₂ completely suppressed 11% gas explosion. The explosion suppression mechanism of CO₂ and ABC powder were probed theoretically. CO₂ plays a key part in the whole explosion processes, and it can effectively suppress the forward reaction between gas and oxygen. While it is during the middle-later period of explosion processes that ABC powder plays a critical role. The particles decomposed from heated ABC powder such as nitrogen and phosphor will react with free radicals rapidly. Besides, atoms as N, P are capable of participating in chain reaction and reacting with active groups, significantly suppressing the gas explosion.     

Experimental study on the inhibition of methane/air explosion by modified attapulgite powder

In order to explore the influence of attapulgite powder on the methane explosion, a small-size semi-closed visual explosion experiment platform was built, and experiments were carried out. The effect of spraying powder on the whole process of methane explosion was studied when methane concentration was 7%, 8%, 9.5%, 11% and 12%, respectively. When the methane concentration was 11%, the maximum explosion overpressure dropped by modified spraying attapulgite powder was as high as 33.26%, and at the same time, the reduction rate of flame propagation velocity reached the maximum value of 36.65%. Furthermore, when the methane concentration was 9.5%, the experimental results when the powder spraying amount of modified attapulgite was 120 mg, 160 mg, 200 mg, 240 mg and 280 mg showed that when the powder spraying was 240 mg, the maximum explosive overpressure decreased by 33.14%, and the reduction rate of the peak flame propagation velocity reached the maximum value of 33.73%. Through the video images recorded by the high-speed camera, the flame structure, shape, color, etc. Were analyzed. The characterization analysis illustrated that the modified attapulgite powder has a small particle size, relatively large porosity and specific surface area. Also, it has a high weight loss rate. Combined with the results of characterization analysis, the explosion suppression mechanism of modified attapulgite powder was discussed. It was found that the modified attapulgite powder could effectively absorb the active free radicals generated in the explosion, and the modified new chemical components have a better thermal decomposition and endothermic effect and a better suppression of methane explosions.     

Experimental and theoretical investigation of dry-water containing phosphoric acid for new fire suppressant

To overcome the shortcomings of phosphorus-containing compounds (PCCs, not widely used) in fire suppression, the dry water powder containing phosphoric acid was analyzed for a new fire suppressant (SiO₂-P). First, the fine conditions (solid-to-liquid ratio, stirring time and stirring speed) were determined to prepare the new powder. The particle size distributions and XPS of SiO₂-P powder were analyzed. The TG tests were conducted to study the decomposition of powder, and there was a major decomposition peak. Second, the extinguishing time of SiO₂-P powder was tested, which showed that the SiO₂-P powder containing phosphorus species could significantly improve the fire suppression ability. In addition, the kinetic parameters of powder decomposition reaction were determined by genetic algorithm based on TG results. Last, based on the decomposition products and kinetic parameters, the burning velocity and mass fraction of free radicals of CH₄/air flame with SiO₂-P powder addition were studied theoretically. The results indicated that SiO₂-P powder had great ability of reducing the burning velocity and scavenging free radicals. Furthermore, the suppression effects were analyzed, which indicated that the cooperation of H₂O and P suppression effect dominated the suppression mechanism and resulted in the good suppression efficiency.     

Preparation and performance of novel APP/NaY–Fe suppressant for coal dust explosion

Coal dust explosion occurs easily in the coal chemical industry. To ensure safety in industrial production, NaY zeolite was used as carrier modified with Fe ions and combined with ammonium polyphosphate (APP) to prepare a novel composite suppressant for coal dust explosion. The explosion suppression performance of novel APP/NaY–Fe suppressant was investigated by flame propagation inhibition experiments. The results show that Fe ion modification can effectively improve the explosion suppression performance. By increasing content, the explosion suppression performance of the explosion suppressant increases. The maximum explosion pressure P_max of coal dust drops to 0.13 MPa when 50 wt% explosion suppressants were added, and the coal dust explosion cannot continue to expand. Complete suppression of explosion could be achieved by adding 66 wt% explosion suppressants. Combined with XRD, SEM and TG results, the explosion suppression mechanism was proposed. The novel explosion suppressant has high thermal stability, good dispersity and its explosion suppression components distribute uniformly. It shows good explosion suppression performance by the synergistic effect among explosion-suppression components.     

煤矿瓦斯爆炸阻隔爆技术现状及展望

煤矿主要采用隔爆水棚或岩粉棚来抑制瓦斯爆炸火焰传播,但此类技术仅针对一次性瓦斯爆炸,而缺乏对多次及连续瓦斯爆炸的有效阻隔爆手段。仅注重对燃烧波的淬熄作用,对造成很大破坏的冲击波的衰减效果不足。多孔介质的淬熄火焰和衰减冲击波的效能已得到国内外专家的重视,实验研究了多层丝网和多孔材料如泡沫铝和泡沫陶瓷的阻隔爆效果。泡沫陶瓷作为一种多孔介质,具有开孔率大、耐高温、抗冲击力强的优点。理论分析和实验研究表明,由于壁面的多次撞击效应,多孔介质可以有效地销毁瓦斯燃烧化学反应产生的自由基数量,抑制化学反应的放热,使化学反应不能自持进行,进而淬熄燃烧火焰传播;可以大幅衰减瓦斯爆炸的冲击波强度,起到同时淬熄燃烧火焰和衰减冲击波的作用。多孔介质有望成为煤矿井下一种新型的瓦斯爆炸阻隔爆材料和方法。     

水蒸气抑制甲烷燃烧和爆炸实验研究与数值计算

在爆炸激波管中对水蒸气抑制甲烷燃烧和爆炸进行较系统的实验研究,并对其抑燃、抑爆化学动力学作用机理进行数值计算分析。结果表明:加入一定量的水蒸气后,可以有效降低CH4-O2混合气体的燃烧速度和爆炸强度;当水蒸气量达到某临界值时,CH4-O2混合气体将不能被点燃。化学动力学数值计算结果表明:在混合气体中加入水蒸气后,增大了甲烷的点火延迟时间,降低了燃烧温度和H,O和OH等高活性自由基的浓度。水蒸气能有效抑制甲烷燃烧和爆炸,其作用效果源于其物理抑制和化学阻化的综合效应。     

Synergistic inhibition of aluminum dust explosion by gas–solid inhibitors

The inhibition mechanism of gas-solid inhibitors on Al dust explosion was investigated experimentally in a closed cuboid chamber. The variation of parameters concerning flame propagation characteristic and explosion severity used to reflect the synergistic inhibition effect of gas-solid inhibitors on Al dust explosion were elucidated. The results showed that flame propagation velocity and explosion overpressure were inhibited with the increase of gas-solid inhibitors. The inhibition curves of gas-solid inhibitors within the experimental range were further obtained. The reason concerning the SEEP phenomenon was revealed through the GC-MS analysis. The combustion of ammonia enhanced the explosion overpressure when solid inhibitors performed at low concentration. The gas-phase product could be regarded as the inert gas as long as enough amount of inhibitors were added. To comprehend the inhibition mechanism of gas-solid inhibitors, X-ray diffraction was applied to figure out the crystal structure of explosion residue. The results indicated that both physical and chemical inhibition effects were imposed on Al dust explosion by gas-solid inhibitors, including endothermic decomposition, dilution of oxidizer, coverage of Al dust, and scavenger of free radicals. The results of this study will provide a scientific basis for the design of inhibition technology for the dust explosion.