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.     

Study on the preparation of novel NiB/Hβ-Al2O3 micro-mesoporous suppressant and its inhibition mechanism of coal dust explosion flame

Coal dust explosion is one of the serious accidents in the coal industry. It is of great significance to study the flame suppression of coal dust explosions. In this paper, a novel active component NiB with amorphous structure for explosion suppression was synthesized by the chemical reduction method. Furthermore, the novel explosion suppressant NiB/Hβ-Al₂O₃ was prepared through the kneading method by loading novel amorphous NiB nanoparticles on Hβ-Al₂O₃ with the micro-mesoporous structure as the carrier. The morphology and structure of NiB/Hβ-Al₂O₃ were characterized by XRD, BET, SEM, and FTIR, which showed that the NiB/Hβ-Al₂O₃ has proper pore structure and NiB nanoparticles are uniformly distributed as active components for explosion suppression in suppressant. Hartmann tube was used to evaluate the inhibition of coal dust deflagration. The results showed that the flame propagation distance and velocity decreased with the increase of the explosion suppressant. When the addition of explosion suppressant was 30 wt%, the explosion of coal dust was suppressed effectively. Furthermore, combing with the analysis results of the products after coal dust deflagration, the physical and chemical inhibition mechanism of the novel NiB/Hβ-Al₂O₃ explosion suppressant on coal dust deflagration was put forward.     

散煤运输用膜型抑尘剂的制备及性能研究

采用水溶液聚合法,以氧化淀粉、丙烯酸(AA)、二甲基二烯丙基氯化铵(DMDAAC)为原料,通过接枝共聚制备了一种软膜型抑尘剂(抑尘剂液体干燥后形成具有一定韧性的软膜)。与聚乙烯醇类壳型抑尘剂(干燥后形成很脆的壳层)相比,软膜型抑尘剂提高了煤粉固化层的抗破裂能力。由抗震荡性试验可知,使用膜型抑尘剂后,经过18 h的震荡,煤粉的损失率仅为1.91%,而使用壳型抑尘剂后煤粉的损失率为4.85%。还测定了2种抑尘剂的保湿性和耐破度。利用红外光谱对产物的结构进行了表征,采用SEM观察了该产物在煤粉表面形成的膜层形貌。试验结果表明,散煤运输中膜型抑尘剂在减少煤粉损失和控制扬尘污染方面性能优于壳型抑尘剂。     

不同磁化抑尘剂对煤粉润湿性影响规律的实验研究

针对微小粒径粉尘具有危害大且难润湿的问题,基于润湿剂与磁场对水滴颗粒的耦合改性机理,研究不同磁场强度下各抑尘剂对煤粉润湿性影响,采用座滴法测定磁化试剂的煤粉表面接触角,通过粉尘润湿机理进行分析,煤尘沉降Walker实验进行佐证,得到抑尘剂种类、浓度与磁化强度对煤粉的润湿性规律。结果表明:未经磁化的高于临界胶束浓度值溶液对煤尘的润湿能力变化不大,阴离子表面活性剂溶液对煤样的润湿能力强于非离子表面活性剂溶液和阳离子表面活性剂溶液;磁化强度为500 mT的磁化溶液对煤尘润湿能力达到最佳效果。     

新型高分子抑尘剂的性能实验研究

为了进一步改善抑尘剂抑尘性能,自主研发了新型高分子抑尘剂。以阜新发电厂末煤为实验原型,对8组小煤堆 在自然条件下进行抑尘性能实验。研究其表面固化效果、耐水冲蚀性、抗风蚀性、流动性等主要性能,得出其在不同条 件下的最佳浓度配比。实验结果表明:新型抑尘剂具有良好的抑尘功能,其耐水冲蚀性和抗风蚀性随抑尘剂浓度增加而 增强。在多雨地区,抑尘剂溶液最佳浓度是3%,浓度大于3%时抑尘剂耐水冲蚀性随浓度增加效果不明显;在干燥多风地 区,当煤堆储存在30天以内时,抑尘剂溶液最佳浓度范围为1%~3%,储存30~50天时,最佳浓度范围为3%~4%,储存在50 天以上时,最佳浓度为5%。抑尘剂溶液流动性随浓度增加而降低,高浓度抑尘剂喷洒时不易实现均匀喷洒,浓度超过3% 的抑尘剂喷洒时需提前用低浓度溶液进行预湿润。     

Influences of coal dust components on the explosibility of hybrid mixtures of methane and coal dust

In order to study the influences of coal dust components on the explosibility of hybrid mixture of methane and coal dust, four kinds of coal dust with different components were selected in this study. Using the standard 20 L sphere, the maximum explosion pressure, explosion index and lower explosion limits of methane/coal dust mixtures were measured. The results show that the addition of methane to different kinds of coal dust can all clearly increase their maximum explosion pressure and explosion index and decrease their minimum explosion concentration. However, the increase in the maximum explosion pressure and explosion index is more significant for coal dust with lower volatile content, while the decrease in the minimum explosion concentration is more significant for coal dust with higher volatile content. It is concluded that the influence of methane on the explosion severity is more pronounced for coal dust with lower volatile content, but on ignition sensitivity it is more pronounced for coal dust with higher volatile content. Bartknecht model for predicting the lower explosion limits of methane/coal dust mixture has better applicability than Le Chatelier model and Jiang model. Especially, it is more suitable for hybrid mixtures of methane and high volatile coal dust.     

Recent trends in rock dust modifications for improved dispersion and coal dust explosion mitigation

Underground coal mine explosions is perhaps the most hazardous danger in the coal mining industries. Efforts have been made to abate the coal dust explosion by applying rock dust either dry or wet. Dry dust has the best lift characteristic which efficiently quenches the flame propagation of a potential explosion. As a trade-off, undesired respirable dust particles are thereby generated imposing a severe health hazard on coal miners. Wet dusting is an alternative to dry dusting which significantly reduces the exposure to respirable dust particles. However, wet dust is subject to adverse caking issues which lead to a drastic reduction in the dispersibility of the particles. The present work summarizes the studies conducted to date regarding the surface modification of rock dust particles for the purpose of eliminating or alleviating the problems accompanying coal mine dusting applications, meanwhile improving the dispersive properties of dust particles and the ability to suppress the coal dust explosion.     

基于20L球形爆炸装置的甲烷煤尘混合爆炸实验

利用实验室自行设计的20L球形爆炸装置,对煤尘及甲烷煤尘混合物的爆炸特性进行了研究。结果表明:无论有无甲烷,煤尘的最大爆炸压力随煤尘浓度增加呈现先升高后降低的变化趋势,并且均在在煤尘浓度为600g/m3时均达到最大值。同时,甲烷的加入明显提高了煤尘最大爆炸压力值,而且随着甲烷浓度的增加,最大爆炸压力增幅先增加后降低,在甲烷5%时增幅最大。煤尘的爆炸持续时间随煤尘浓度增加呈现先降低后升高的特点,甲烷存在时有同样规律,但是有甲烷时爆炸持续时间明显降低,而且随着甲烷含量的增加,煤尘的爆炸持续时间降低幅度不断增加,在甲烷5%以后趋于稳定。实验结果对生产实践有一定的指导作用。     

不同含水率煤尘在瓦斯爆炸诱导下爆炸传播规律研究

为了探究不同含水率煤尘在瓦斯爆炸诱导下的爆炸传播规律,利用自行搭建的直管瓦斯爆炸诱导煤尘二次爆炸实验系统,从冲击波压力和火焰传播速度2个方面,研究了不同含水率沉积煤尘在瓦斯爆炸诱导下的爆炸传播规律和原因。研究结果表明:当煤尘含水率小于40%时,管道内沉积煤尘会在瓦斯爆炸诱导下产生二次爆炸,同时沉积煤尘总量一定时,沉积煤尘二次爆炸产生的冲击波超压峰值和火焰传播速度随着煤尘含水率的增加先增大后减小;当沉积煤尘含水率为20% 时,煤尘二次爆炸产生的冲击波超压峰值、火焰传播速度峰值达到最大值,分别为1.657 MPa和468.060 m/s;当沉积煤尘含水率大于40%时,沉积煤尘无法产生二次爆炸,此时爆炸产生的威力小于单一瓦斯爆炸,火焰传播速度衰减较无煤尘的瓦斯爆炸更快,沉积煤尘起到抑制瓦斯爆炸传播的作用。研究结果可以为防治煤尘二次爆炸提供理论依据。     

瓦斯对煤尘爆炸特性影响的实验研究

瓦斯的存在对煤尘爆炸特性的理论计算和数值仿真的结果与实际数据有一定差距,因此,通过不同浓度瓦斯与煤尘共存条件下爆炸实验研究,得出了矿井瓦斯对煤尘的最低着火温度、最小点火能量、爆炸下限浓度、最大爆炸压力和最大爆炸压力上升速度等爆炸特性影响的规律即瓦斯对煤尘最低着火温度影响不大;瓦斯可使煤尘的最小点火能量减小,尤其是对难于点燃的煤尘;混合物的爆炸下限浓度随瓦斯浓度的增加而降低;混合物的最大爆炸压力上升速度由于瓦斯的存在而增强,而最大爆炸压力几乎没有变化。同时研究了瓦斯对无爆炸性煤尘的影响。实验研究的结论对于现场防止煤尘爆炸的发生具有指导意义。     

典型硼化合物与磷酸二氢铵协效阻燃松木的燃烧性能及热解动力学研究

利用木垛法和热重分析法比较研究了硼酸、硼砂与磷酸二氢铵复配阻燃松木的燃烧性能、热解特性及热解反应动力学。结果表明,单种阻燃剂使用时,磷酸二氢铵的阻燃效果优于硼酸和硼砂;两两复配使用具有明显的协效作用,其中阻燃效果:磷酸二氢铵/硼酸＞磷酸二氢铵/硼砂＞硼酸/硼砂,而硼酸与磷酸二氢铵在质量比为2:3时,协效阻燃效果最好。与未处理松木相比,阻燃剂的加入降低了松木在热解阶段的初始分解温度和峰值分解温度,缩短了热解区间,并降低了松木在主要热解阶段的表观活化能,其中热解阶段活化能越低的阻燃松木在燃烧过程中成炭效果和阻燃性能越好。     

甲烷煤尘耦合爆炸传播特性及伤害研究

为探究煤尘质量浓度对甲烷煤尘耦合爆炸传播特性及伤害距离的影响,自制长15 m的爆炸管道系统,用体积分数为7％甲烷分别与质量浓度为0、50、100和200 g/m3的煤尘进行耦合爆炸试验,并根据质量、动量和能量守恒理论推导出最大压力计算公式.结果 表明:不同质量浓度煤尘与甲烷耦合爆炸时,最大压力均随与爆源距离的增加呈现出...     

瓦斯煤尘爆炸特性及抑爆方法研究进展

为探究瓦斯煤尘爆炸特性及抑爆机理,本文通过一系列实验,研究瓦斯、煤尘爆炸的速度和温度等特征,提出利用图像相关系数法和辐射测温原理计算火焰传播速度及温度场变化,定量分析影响煤尘爆炸的因素以及产物变化规律,揭示煤尘爆炸的宏微观机制。结果表明:火焰分形维数可以用来反应瓦斯爆炸强度,即当分形维数更接近2.2937时爆炸反应最为强烈,其爆炸过程中自由基最终生成浓度与CH 4初始浓度呈倒U型关系;当量比对煤粉火焰爆炸压力及速度也有一定影响,在最佳当量比的2倍左右时可以达到最大爆炸压力和最大火焰传播速度。另外本文亦采用泡沫陶瓷对瓦斯的多次爆炸和连续爆炸进行抑爆,发现不同厚度和孔隙的泡沫陶瓷具有不同的抑制效果,孔隙较大的泡沫陶瓷对爆炸能量有较好的抑制作用。     

管道内瓦斯煤尘共混爆炸温度特性

采用瞬态火焰传播实验系统,对7%,8%,9%,10%和11%的瓦斯体积浓度分别与不同浓度的长焰煤煤尘混合,并使用直径25 μm的Pt/Rh13-Pt微细热电偶测量温度,揭示受限空间内瓦斯与煤尘混合爆炸温度特性。结果表明:煤尘浓度一定时,随着瓦斯浓度的增加,爆炸温度先增加后减小;纯瓦斯浓度在10%时爆炸温度最高,加入煤尘后的混合体系中,瓦斯浓度为9%时爆炸温度最高;瓦斯浓度不变时,随着煤尘浓度的增加,爆炸温度一直减小;7%~11%瓦斯分别与130 g/m3煤尘混合爆炸后测得最高温度分别为1 333.6,1 475.4,1 511.4,1 455.6,1 396.4 ℃;与9%纯瓦斯爆炸相比,9%瓦斯与130,260,520,780 g/m3煤尘混合爆炸后测得最高温度分别降低7.2%,11.5%,15.0%和22.9%。结论得到的瓦斯煤尘共混爆炸温度数据可为煤矿灾害高温防护提供参考依据。     

复合型水雾抑尘剂作用机理与优选方法研究*

为有效提高水雾综合除尘性能,基于水雾捕尘过程及抑尘作用机理,从复合抑尘剂润湿、吸湿、黏结作用组分出发,讨论不同性质粉尘与抑尘剂各组分间匹配协同关系,进而研究复合型水雾抑尘剂优选方法。结果表明:湿润组分优选疏水端含有碳碳双键、醚基或链间存在氢键的表面活性剂;通过改变疏水基链长、不饱和度和支链数等方法,使湿润组分亲水、亲油性与粉尘相匹配。吸湿组分优选体心立方晶胞结构、溶解度相对较小的无机盐或混合配方无机盐,或者含极性强、能形成氢键的基团且空间结构复杂的有机吸湿剂。黏结组分优选溶液黏度高、交联网状、结构复杂的高分子聚合物。在上述组分优选的基础上,通过抑尘剂复配性能实验合理确定各组分的最优配比。     

瓦斯爆炸引起沉积煤尘爆炸传播实验研究

运用井下大型实验巷道对瓦斯爆炸诱导沉积煤尘爆炸进行实验研究,并对几次实验结果进行对比分析。通过对爆炸压力以及火焰产生、发展、传播过程进行的分析,得出瓦斯爆炸引起沉积煤尘爆炸过程中压力波存在回传现象;在煤尘刚开始参与爆炸处,爆炸超压有一个较长的持续时间;爆炸火焰的传播速度在铺有煤尘段迅速上升,最后有一平缓的上升阶段,过了煤尘段开始下降;火焰区长度约为煤尘区长度的2倍等规律。实验研究发现的规律为有效的预防瓦斯煤尘爆炸事故提供了理论依据。     

Suppression effects of ammonium dihydrogen phosphate dry powder and melamine pyrophosphate powder on an aluminium dust cloud explosion

Selecting a suitable flame-retardant powder is essential for preventing or reducing the risk of aluminium dust cloud explosions. Two types of retardant materials were studied, namely ABC powder (a flame-retardant powder mainly composed of ammonium dihydrogen phosphate dry powder) and melamine pyrophosphate powder (MPP). A specially designed rectangular pipe was used to examine the influences and mass fractions of the aforementioned flame retardants and the effects of compounds on maximum explosion pressure and maximum explosion pressure rate of increase. The results showed that the explosion-suppression effects of MPP powder were superior to those of ABC powder. Furthermore, the suppression effects of combining ABC and MPP to form compounds in various ratios were explored. The explosion-suppression effects of the single flame-retardant powders and flame-retardant powder compound were compared, which revealed that the effects of the flame-retardant compound were intermediate to those of ABC and MPP used separately. No synergistic effect was observed in the compound retardant. However, component mass fractions influenced the retardant properties of the compound. The suppression mechanism was investigated through thermal analysis, which revealed that the decomposition of the two flame-retardant powders was an endothermic process that generated inert gas. The addition of flame-retardant powder delayed the time required by aluminium to break through its oxide film. However, the thermal analysis curve of the compound overlapped those of the two single powders, and no new chemical reaction occurred. Thus, no change was observed in the efficacy of the flame-retardant properties.     

Experimental study on the minimum explosion concentration of anthracite dust: The roles of O2 mole fraction,inert gas and CH4 addition

The explosion characteristics of anthracite coal dust with/without small amount of CH₄ (1.14 vol %) were investigated by using a 20 L spherical explosion apparatus with an emphasis on the roles of oxygen mole fraction and inert gas. Two methods based on overpressure and combustion duration time were used to determine the minimum explosion concentration (MEC) or the lower explosion limit (LEL) of the pure anthracite coal dust and the hybrid coal-methane mixtures, respectively. The experiment results showed that increasing oxygen mole fraction increases the explosion risk of coal dust: with increasing oxygen mole fraction, the explosion pressure (P_ex) and the rate of explosion pressure rise ((dp/dt)_ex)) increase, while MEC decreases. The explosion risk of anthracite dust was found to be lower after replacing N₂ with CO₂, suggesting that CO₂ has a better inhibition effect on explosion mainly due to its higher specific heat. However, the addition of 1.14% CH₄ moderates the inhibition effect of CO₂ and the promotion effect of O₂ on anthracite dust explosion for some extent, increasing explosion severity and reducing the MEC of anthracite dust. For hybrid anthracite/CH₄ mixture explosions, Barknecht's curve was found to be more accurate and conservative than Chatelier's line, but neither are sufficient from the safety considerations. The experimental results provide a certain help for the explosion prevention and suppression in carbonaceous dust industries.     

煤尘挥发分及粒径对爆炸火焰长度的影响研究

为研究煤尘挥发分及粒径对爆炸火焰长度的影响及其变化规律,选取挥发分含量不同的四种典型烟煤煤样,分别制备成31.5、44、62.5、81.5、119、>150 μm六种粒径,利用煤尘爆炸性鉴定装置测试其爆炸火焰长度,并对其爆炸火焰长度变化规律进行分析。结果表明:随着挥发分含量的增加,不同粒径级别的煤尘爆炸火焰长度均呈增长趋势;在挥发分含量较低的区间,挥发分含量增加对爆炸火焰长度影响不大;在挥发分含量较高的区间,随着挥发分含量的增加其爆炸火焰长度也急剧增加,并且粒径越小增加的越快。对于同一实验煤样,随着粒径的增大,其爆炸火焰长度逐渐减小,粒径增大到150 μm以上时爆炸火焰几乎消失。爆炸火焰长度随粒径变化的变化率根据实验煤样的不同,呈现出两种变化规律,挥发分含量为18.99%和27.52%煤样的爆炸火焰变化率先增加再减小再增加,挥发分含量为32.20%和39.74%的煤样呈现先增加再减小的趋势,但四组实验煤样的爆炸火焰长度变化率都在44～62.5 μm的粒径变化量时达到最大值。     

障碍物对瓦斯煤尘爆炸火焰传播规律的影响

为了进一步探究瓦斯煤尘耦合爆炸火焰的传播规律,用自行搭建的半封闭垂直管道爆炸试验系统,研究障碍物对瓦斯煤尘耦合爆炸火焰传播规律的影响。研究结果表明:障碍物能显著提高瓦斯煤尘爆炸火焰的传播速度,其加速机理主要是障碍物诱导的湍流区会促进火焰的传播;火焰在传播过程中的加速度不是一直增加,随着火焰速度的增加会出现上下波动;煤尘的加入会使瓦斯爆炸产生的火焰传播速度显著增大及速度的最大值距离点火端较远;通过障碍物时爆炸产生的火焰形状发生较大的改变,出现拉伸和褶皱现象。