煤粉爆炸事故在火电厂、水泥厂等工矿企业时有发生，有效防控煤粉爆炸事故是企业安全生产工作中的重点。爆炸抑制技术是煤粉爆炸防控的重要手段之一。本文采用实验测试与理论分析相结合的研究方法，从爆炸抑制实验-氧化燃烧热效应-爆炸抑制后固态产物微观特征三个方面研究了活性抑爆剂对煤粉爆炸过程的影响，揭示了不同活性抑爆剂的抑制效果及抑制机理，研究结果对提升煤粉爆炸抑制技术具有重要理论意义和现实意义。

利用20L球形爆炸实验装置，研究了惰性抑爆剂碳酸钙（CaCO₃）和不同类型活性抑爆剂碳酸氢钠（NaHCO₃）、磷酸二氢铵（NH₄H₂PO₄）、三聚氰胺氰尿酸盐（MCA）以及三聚氰胺聚磷酸盐（MPP）对煤粉爆炸超压、爆炸特征时间和火焰形态演化过程的影响，得到不同活性抑爆剂的抑制效果。结果表明，随着抑爆剂添加量增加，煤粉最大爆炸压力呈现折线下降，最大爆炸压力上升速率呈现直线下降。添加抑爆剂后煤粉爆炸压力上升速率曲线在点火后出现拐点。当抑爆剂添加量增大时，爆炸压力上升速率曲线呈“双峰曲线”。拐点是抑爆剂抑制效应显现的标志，“双峰曲线”是爆炸即将被完全抑制的标志性特征。添加抑爆剂后，点火初期火焰逐渐被削弱呈现离散状火焰，并且出现无火焰状态。随着粉体抑爆剂添加量增加，火后出现稳定连续的火核团状火焰时间逐渐变长，火焰传播平均速率逐渐减小。离散状火焰和点火后出现无火焰状态是爆炸抑制过程中典型的火焰形态，且无火焰状态与“双峰”型爆炸压力上升速率曲线变化具有统一性。添加抑爆剂后，煤粉爆炸感应时间和爆炸燃烧时间均被延长，爆炸在点火初期被完全抑制。当煤粉爆炸浓度为300g/m³时，惰性抑爆剂CaCO₃粉体和活性抑爆剂NaHCO₃、NH₄H₂PO₄、MCA和MPP粉体的最佳抑制浓度分别为562.5g/m³、787.5g/m³、138.8g/m³、198.3g/m³和78.3g/m³。随着煤粉爆炸浓度逐渐增加，最佳抑制浓度呈现先增加后减小的趋势。通过最大爆炸压力上升速率抑制率和最佳抑制浓度两项指标得到不同抑爆剂抑制效果顺序为MPP>NH₄H₂PO₄>MCA>CaCO₃>NaHCO₃。

基于能量守恒定律，引入煤粉爆炸过程准静态压力计算模型，得到煤粉爆炸准静态压力与煤粉燃烧释放热量成正比关系。并通过同步热分析实验研究了活性抑爆剂和煤粉-抑爆剂混合体系氧化燃烧过程热效应特征。活性抑爆剂NaHCO₃、NH₄H₂PO₄、MCA和MPP粉体开始分解温度分别为140.05℃、198.14℃、320.38℃和353.37℃。惰性抑爆剂CaCO₃粉体开始分解温度为612.31℃。活性抑爆剂NaHCO₃、NH₄H₂PO₄、MCA和MPP粉体分解过程吸收热量分别为595J/g，2493J/g，2017J/g和2908J/g。NH₄H₂PO₄和MPP粉体分解吸热持续时间长，NaHCO₃和MCA粉体吸热持续时间较短。通过分析煤粉-抑爆剂混合体系燃烧过程热效应特征，发现惰性抑爆剂CaCO₃粉体是在煤粉燃烧完成之后开始分解，故其吸热过程和分解中间产物对煤粉爆炸抑制影响很小。活性抑爆剂NH₄H₂PO₄、MCA和MPP粉体分解吸热反应发生在煤粉燃烧阶段，对煤粉爆炸过程影响较大。随着抑爆剂添加量增加，混合体系氧化燃烧的最大质量损失速率、最大热流和释放的热量逐渐减小。混合体系氧化燃烧热量减小导致体系爆炸压力减小。基于热效应特征，发现影响活性抑爆剂抑制效果的因素有抑爆剂吸热量、吸热持续时间以及粉体粒径分布，前两者是影响抑制效果的主要因素，后者是次要因素。选择活性抑爆剂时，“吸热量越大、吸热持续时间越长、粒径越小”的粉体有利于达到更好的抑制效果。

根据煤粉爆炸强迫点火模型、活性抑爆剂分解热效应特征以及煤粉爆炸抑制后固态产物微观特征揭示了活性抑爆剂物理和化学抑制机理。通过对煤粉爆炸抑制后固态产物表面微观形貌和活性抑爆剂的分解热效应特征研究表明，活性抑爆剂的物理抑制机理主要包含隔离阻化过程和分解吸热过程，惰性抑爆剂主要以隔离阻化过程为主。同时，采用电子顺磁共振波谱仪研究了原始煤粉、煤粉爆炸产物和爆炸抑制后产物的自由基变化特征，发现煤粉爆炸过程自由基浓度Ng值降低。纯煤粉爆炸产物的Ng值从原始煤粉的1.992×10¹⁸spin/g减小为8.298×10¹⁶spin/g。随着活性抑爆剂添加量增加，煤粉爆炸抑制后固态产物中自由基浓度逐渐升高并接近原始煤粉，说明煤粉中参与爆炸反应的自由基减小。采用XPS技术研究了煤粉爆炸抑制后固态产物化学组分，分析了活性抑爆剂在爆炸中的分解过程，揭示了活性抑爆剂化学抑制过程是其分解中间产物捕获爆炸过程的关键自由基，破坏煤粉爆炸燃烧的链式反应。根据煤粉爆炸抑制过程，提出活性抑爆剂物理-化学协同抑制作用模型。

Pulverized coal explosions occurred accidentally in thermal power plants, cement plants and others related industries. It is important to prevent pulverized coal explosion effectively during production. Explosion inhibition method is one of essential technologies to control pulverized coal explosion. In this study, the inhibiting effects of different active inhibitors on the pulverized coal explosion were investigated based on explosion characteristics, combustion thermal effect and microscopic characteristics of residues by experimental test and theoretical analysis methods. In addition, the yinhibiting ability and suppression mechanisms of active inhibitors were revealed. The results of this study have important theoretical and practical significance for improving the inhibition technology.

The inhibiting effects of inert inhibitor calcium carbonate (CaCO₃) and active inhibitors including sodium bicarbonate (NaHCO₃), ammonium dihydrogen phosphate (NH₄H₂PO₄), melamine cyanurate (MCA) and melamine polyphosphate (MPP) on explosion overpressure, explosion characteristic time and flame morphology evolution were investigated using a 20 L spherical explosion device, in addition, the inhibiting ability were evaluated. The results show that with the mass fraction of inhibitors increasing, the maximum explosion pressure decreased in sudden, and the maximum pressure rising rate decreased in a straight line. With the addition of inhibitors, an inflection point was appeared on the pressure rising rate curves after ignition, which was the sign that the inhibition effect began to appear. With the amount of inhibitors increasing, a typical “bimodal curve” were presented, which mean that explosion was about to be suppressed. After adding inhibitors, discrete flame was exhibited during the explosion initial stage, and there was no flame after ignition. With the mass fraction of inhibitors increasing, the time to appear stable flame with flame kernel became longer, and the average flame propagation velocity also decreased. Discrete flame and flameless state after ignition were typical flame characteristics during explosion inhibition, and the flameless state was consistent with the change of “bimodal curve” explosion pressure rising rate curve. Both of induction time and explosion time were prolonged, and the pulverized coal explosion was completely suppressed in the initial stage after ignition. When coal dust concentration was 300g/m³, the optimal inhibition concentrations of inert inhibitor CaCO₃ and active inhibitors including NaHCO₃, NH₄H₂PO₄, MCA and MPP were 562.5g/m³, 787.5g/m³, 138.8g/m³, 198.3g/m³ and 78.3g/m³, respectively. With the increasing of coal dust concentration, the optimal inhibition concentration increased first and then decreased. According to the inhibition rate of maximum pressure rising rate and optimal inhibition concentration, the order of inhibiting ability was MPP>NH₄H₂PO₄>MCA>CaCO₃>NaHCO₃.

Based on the conservation of energy, the quasi-static pressure calculation model of pulverized coal explosion was established, which showed that there was positive proportional relationship between explosion pressure and heat released by pulverized coal combustion. Furthermore, the thermal effect of inhibitors and pulverized coal-inhibitor mixtures were detected by synchronous thermal analysis. The decomposition temperatures of NaHCO₃, NH₄H₂PO₄, MCA and MPP powders were about 140.05℃, 198.14℃, 320.38℃ and 353.37℃, respectively. The decomposition temperature of CaCO₃ was 612.31℃. The heat absorbed by NaHCO₃, NH₄H₂PO₄, MCA and MPP during decomposition processes were 595J/g, 2493J/g, 2017J/g and 2908J/g, respectively. The decomposition duration of NH₄H₂PO₄ and MPP powder were longer, while that of NaHCO₃ and MCA powder were shorter. According to the decomposition process of pulverized coal and CaCO₃ powder mixtures, it was found the inert inhibitor CaCO₃ began to decompose after pulverized coal combustion, so its endothermic process and decomposition intermediates had little influence on pulverized coal explosion suppression. The decomposition endothermic reaction of active inhibitors including NH₄H₂PO₄, MCA and MPP powder occurred during pulverized coal combustion, which had a great influence on the pulverized coal explosion. With the concentration increasing, the maximum mass loss rate, maximum heat flow and heat released of the mixtures gradually decreased, which resulted in the decrease of explosion pressure. Based on thermal characteristics, it was found that the factors affecting the inhibition ability included heat absorption, heat absorption duration and particle size distribution, while the first two were the main factors, and the latter was the secondary factor. To find better inhibitor, powder with “high heat absorption, the longer heat absorption duration and the smaller particle size” is conducive to achieve better explosion suppression effect.

According to forced ignition model, thermal characteristics and micro characteristics of solid residues, inhibiting mechanisms were revealed. The micro characteristics and the decomposition endothermic characteristics illustrated that physical inhibition included isolation process and decomposition endothermic process, while the inert inhibitor only consisted isolation. Meanwhile, the free radical characteristics of raw pulverized coal, explosion residue and explosion suppression residues were characterized by electron paramagnetic resonance spectroscopy. It was found that the free radical concentrations Ng decreased after explosion. The Ng value of explosion residues was reduced from 1.992×10¹⁸spin/g to 8.298×10¹⁶spin/g. With the mass fraction of inhibitors increasing, the concentration of free radicals in the solid residues increased gradually and approached to the raw pulverized coal, indicating that the free radicals involved in explosion were reduced. The chemical components of explosion suppression residues were studied by XPS, and the decomposition process of active inhibitor during explosion was analyzed. It was found that the chemical inhibition of active inhibitors were key free radicals consumption by intermediate products, which destroyed the chain reaction of pulverized coal explosion. According to the pulverized coal explosion inhibition, a physical-chemical synergistic inhibition model was proposed.