分散度对煤粉爆炸特性的影响

煤矿工作面煤尘呈多分散性,因此采用单一粒径的煤样评估煤尘爆炸风险存在缺陷。为了研究分散度对煤尘爆炸特性的影响规律,找出合适的平均粒径表示方式来评估分散度对爆炸风险的影响,以5种粒径分布范围相同但分散度不同的煤样为研究对象,采用20 L爆炸球实验装置,测量样品的最大爆炸压力P_(ex)、最大爆炸压力上升速率(dp/dt)_(ex)、开始点火至最大爆炸压力的时间段t_1和开始点火至最大爆炸压力上升速率的时间段t_2四个参数。后续采用热值分析、扫描电镜试验方法探究不同分散度煤尘的反应程度。借助方差分析和斯皮尔曼相关性分析研究测量结果组间的差异性、不同粒径表示方式与爆炸特性参数的相关性。实验结果表明:对于具有相同粒径分布的煤粉,分散度对煤粉爆炸反应速率影响较大。小粒径煤尘颗粒的质量分数越大,反应速率越快,反应越充分,释放的能量越大。当小粒径煤尘质量分数达到30%时,最大爆炸压力上升速率显著增大,t_1和t_2明显减小。粒径最小的原始样品3的爆炸产物热值最低,且爆炸产物表面形成了较为丰富的孔洞结构,说明小粒径煤尘较快的脱挥发速率能增加爆炸的反应程度。D_(10),D_(25)(为投影面积的10%和25%的颗粒直径)、D_(3,2)(索特尔直径)与最大爆炸压力上升速率、t_1和t_2三个参数的斯皮尔曼相关系数均落在高度相关和显著相关的区间,呈现出较好的相关性。对于多分散性的煤尘,D_(10),D_(25)和D_(3,2)可以较好的评估分散度对煤尘爆炸特性的影响。     

静电点火下煤粉爆炸特性研究

为完善粉尘爆炸测试方法,建立了一套基于20L球形爆炸装置的煤粉爆炸特性参数的测试系统。实验采用大能量静电点火对不同粒径的煤粉-空气混合物的爆炸特性进行了研究,测得了不同实验条件下煤粉的爆炸特性参数。实验结果表明,随着煤粉浓度的增加,爆炸压力、压力上升速率等爆炸参数先增大后减小;煤粉粒径对其爆炸特性影响很大,煤粉粒度越小,爆炸烈度越强烈;随着点火能量的增大,爆炸压力、爆炸压力上升速率等爆炸参数逐渐增大,当点火能量增大到一定值时,这些参数又趋于稳定。     

点火能量对煤粉爆炸行为的影响

为了探明点火能量对煤粉爆炸特性参数的影响,利用20 L球形爆炸装置进行试验测试,试验研究了不同点火能量对煤粉爆炸行为的影响,对煤粉爆炸猛度(最大爆炸压力和最大升压速率)及惰性介质的抑爆效力随点火能量的变化规律进行了重点探讨。结果表明:随着点火能量的增加,爆炸压力随着煤粉浓度的增加呈现先上升后下降的趋势,在同一浓度下,粉尘最大爆炸压力和最大升压速率呈线性上升,在高浓度下,粉尘爆炸压力受点火能量的影响更显著;惰性介质抑爆效力随点火能量增加而下降,建议采用5~10 kJ点火能量考察惰性介质对煤粉爆炸的抑制效力。     

外部条件对煤粉爆炸特性的影响

为了探明外部条件对煤粉爆炸特性参数的影响,利用20 L球形爆炸装置进行试验测试,探讨了不同点火能量对爆炸的影响,对比CaCO_3和Al(OH)_32种惰性介质的抑爆效果,不同含水量煤粉的燃烧爆炸行为。结果表明:随着点火能量的增加,粉尘最大爆炸压力呈线性上升,爆炸压力随着煤粉浓度的增加呈现先上升后下降的趋势;添加CaCO_3和Al(OH)_3能够降低煤粉的爆炸压力,相对于CaCO_3的物理抑爆而言,Al(OH)_3的物理-化学抑爆效果更佳;煤粉爆炸最大爆炸压力随粉尘含水量降低而不断增大。     

焦坪矿区油气伴生特性及其对瓦斯爆炸极限的影响

焦坪矿区属于典型的煤油气共生矿区,特殊的瓦斯赋存,使得该矿区的瓦斯防治工作难度加大。通过理论分析计算和实测瓦斯含量,得出了瓦斯爆炸极限的变化趋势,为矿区的瓦斯防治提供了依据。     

外部条件对煤粉爆炸特性的影响北大核心

为了探明外部条件对煤粉爆炸特性参数的影响,利用20 L球形爆炸装置进行试验测试,探讨了不同点火能量对爆炸的影响,对比CaCO_3和Al(OH)_32种惰性介质的抑爆效果,不同含水量煤粉的燃烧爆炸行为。结果表明:随着点火能量的增加,粉尘最大爆炸压力呈线性上升,爆炸压力随着煤粉浓度的增加呈现先上升后下降的趋势;添加CaCO_3和Al(OH)_3能够降低煤粉的爆炸压力,相对于CaCO_3的物理抑爆而言,Al(OH)_3的物理-化学抑爆效果更佳;煤粉爆炸最大爆炸压力随粉尘含水量降低而不断增大。     

矿井特殊气体对瓦斯爆炸特性的影响

瓦斯爆炸是煤矿重大灾害之一。矿井火区中微量气体成分对瓦斯爆炸极限及其它爆炸参数有显著影响,利用自行研制的配气系统和20 L球形爆炸系统,选用3种特殊气体成分作为代表气体,通过实验进行了对比研究。实验结果表明,氢气、异丁烷、正己烷都会对瓦斯爆炸特性产生较大影响,其中正己烷对甲烷爆炸下限影响较大,氢气对甲烷爆炸上限影响较小,最大爆炸压力指数影响的顺序为氢气>正己烷>异丁烷。     

煤粉对泡沫金属抑制爆炸火焰传播速度的影响分析

针对煤粉对泡沫金属抑制爆炸火焰传播速度的影响进行了相关实验,着重分析了煤粉在管道内有抑爆介质时的运移规律和对其抑爆效果的影响机理。管道内煤粉在爆炸冲击波的影响下分为3个部分:未被扬起滞留在抑爆材料前一部分;滞留在抑爆材料上一部分;穿过抑爆材料逸散一部分。煤粉对泡沫金属抑爆性能的影响主要体现在:当煤粉粒径一定时,煤粉质量过大或过小对泡沫金属抑爆性能影响不大。煤粉质量过小时,大部分煤粉经过泡沫金属逸出,对其抑爆性能影响较小;而当煤粉质量过大时,局部区域氧气浓度不足,滞留在泡沫金属上的煤粉不易燃烧,对泡沫金属的抑爆性能影响也较小。当煤粉质量一定,粒径越接近泡沫金属孔径,煤粉越易滞留在泡沫金属上,对其抑爆性能影响也越大。     

环境温度对预混瓦斯气体爆炸特性的影响

为了研究不同环境温度条件下预混瓦斯气体爆炸特性参数的变化和危险性,利用20 L爆炸特性实验装置,采用夹层和内腔双加热、高压放电点火的方法,对不同环境温度(20～200℃)瓦斯爆炸压力特性、爆炸燃烧特性参数、爆炸极限等参数进行了测试。研究表明:在实验条件下,爆炸最大压力、爆炸反应时间、爆炸点火延迟时间均随环境温度的升高而逐渐降低或减少;当环境温度升高至200℃时,爆炸最大压力降低了43.8%,而爆炸反应时间、点火延迟时间分别减少了54、14.4 ms;压力上升速率受温度影响较小;随环境温度升高,分子内能增加,原来稳定的不燃系统越容易变成可燃、可爆系统,爆炸极限范围变宽。     

低浓度瓦斯对煤尘爆炸下限的影响研究

采用20 L钢制近球形爆炸特性测试系统,对低浓度瓦斯参与条件下、3种不同煤尘的爆炸下限变化规律进行了试验研究。研究发现:在本试验条件下,煤尘的爆炸下限浓度随瓦斯浓度的增加而逐渐下降;当瓦斯浓度在0~1.0%范围内,煤质组成成分对爆炸下限影响较大,相应的瓦斯和煤尘共存的爆炸复合体系表现为"强煤尘"性;当瓦斯浓度大于1%时,煤尘爆炸下限浓度的数值差异不大,煤质成分对煤尘爆炸下限的影响不再明显,相应的瓦斯煤尘共存的复合爆炸体系表现为"强瓦斯"性。     

Numerical investigation on the spraying and explosibility characteristics of coal dust

This paper utilises FLUENT software to simulate the spraying and explosion of coal dust in a spherical explosion chamber. The influence of particle size on coal dust spraying is analysed. Explosion easily develops for small particle sizes under the same conditions of coal dust concentration and ignition temperature. For large-size coal dust particles, the speeds of release and transmission reduce dramatically due to lack of oxygen inside. Explosion is very difficult to develop in such conditions. Coal dusts with smaller particle size distribute uniformly in the chamber, whereas larger particles concentrate in parts of the chamber. The influence of coal dust concentration, ignition temperature and particle size on the pressure of coal dust explosion is also studied. The results show that, when ignition temperature is less than a certain value, the maximum pressure increases rapidly with the growth of ignition temperature. As ignition temperature is larger than the value, the change of the maximum pressure is small. The maximum explosion pressure increases first and then decreases with the increase of coal dust concentration. Because the inside of large size particles burn only partially due to lack of oxygen and slow combustion heat release and transfer, the decrease of the maximum explosion pressure is proportional with the increase of particle size.     

Mechanism research of gas and coal dust explosion

Combined with the experimental results from the large tunnel of the Chongqing Research Institute, the mechanism of gas and coal dust explosion was studied. Some concepts about gas and coal dust explosion were introduced such as the form condition and influential factors. Gas and coal dust explosion propagation was researched and the lifting process of coal dust was simulated. When an explosion occurred due to great mixture of gas and air, the maximum explosion pressure appeared in the neighborhood of the explosion source point. Before it propagated to the tunnel of the deposited coal dust, the maximum explosion pressure appeared to be in declining trend. Part of the energy was lost in the process of raising the deposited coal dust through a shock wave, so the maximum explosion pressure was smallest on the foreside of the deposited coal dust sector. On the deposited coal dust sector, the explosion pressure rapidly increased and dropped off after achieving the largest peak value. Because of coal dust participation in the explosion, the flame velocity rose rapidly on the deposited coal dust and achieved a basic stable value; coal dust was ignited to explode by initial laminar flame, and the laminar flame transformed into turbulent flame. The turbulence transformed the flame fold into a funnel shape and the shock wave interacted with the flame, so the combustion rate rose and the pressure wave was further enhanced. The regeneration mechanism between the flame combustion rate and the aerodynamic flowing structure achieved the final critical state for forming the detonation. Supported by the National Basic Research Program (973) (2005CB221506); National Natural Science Foundation of Chongqing (CSTC, 2007BA6018); National Key Technology R&D Program (2006ABK03B04)     

管道中煤尘爆炸特性实验

在长度为32.4 m、内径为199 mm的圆形管道中采用强点火方式对甲烷-空气混合物及甲烷-煤尘-空气混合物爆炸超压传播规律及爆速进行了研究。研究结果表明：强点火条件下甲烷－空气混合物的最大爆压和爆速分别为4 MPa、1 766 m/s,在标准状态瓦斯爆炸极限浓度外2.5%、4.1%、15.2%时也出现稳定爆轰。相同浓度甲烷-煤尘-空气混合物爆炸超压及爆速要大于甲烷-空气、煤尘-空气混合物,甲烷-煤尘-空气混合物在爆炸当量浓度时,随着煤尘浓度越大,瓦斯浓度越小,爆炸超压和爆速越小。     

煤尘组分对瓦斯/煤尘复合爆炸下限的影响研究

瓦斯和煤尘复合爆炸是煤矿井下爆炸灾害的主要形式之一,研究瓦斯/煤尘复合爆炸下限变化规律,是有效防治煤矿爆炸灾害的必备条件。为研究煤尘组分对瓦斯/煤尘复合爆炸下限的影响,特选用2种组分不同的煤尘(烟煤和无烟煤)。依据EN 14034标准,使用10 kJ化学点火头在标准20L球形爆炸容器中,分别对2种煤尘的最小爆炸浓度、相同试验条件下的瓦斯爆炸下限以及煤尘与瓦斯的复合爆炸下限进行了测量。试验测得烟煤和无烟煤的最小爆炸浓度分别为50 g/m^3和70 g/m^3,瓦斯爆炸下限为4%。当煤尘中分别通入1%、2%、3%、4%的瓦斯后,烟煤最小爆炸浓度分别降低至40、20、5、0 g/m^3,无烟煤最小爆炸浓度分别降低至50、20、5、0 g/m^3。基于上述测量结果,对比分析了煤尘组分对瓦斯/煤尘复合爆炸下限变化规律的影响,并探讨了Le Chatelier、Bartknecht、Jiang等气粉复合爆炸下限预测模型对瓦斯/煤尘复合体系的适用性。结果表明:2种煤尘的最小爆炸浓度均随瓦斯浓度的增大而降低,但挥发分含量低的煤尘降幅更大,即瓦斯对低挥发分煤尘最小爆炸浓度的影响更为显著。Jiang模型预测值远远偏离实际测量值;Le Chatelier模型预测值高于实际测量值,且误差随瓦斯浓度的增大而增大;Bartknecht模型适用性相对较好,且更适用于低挥发分瓦斯/煤尘复合体系。     

瓦斯爆炸诱导沉积煤尘参与爆炸作用模式

应用连续相、颗粒相计算方法对瓦斯爆炸诱导沉积煤尘参与爆炸的传播过程进行数值模拟,并以此对爆炸作用模式及其异同进行研究。根据模拟结果,从不同煤尘云点火机理在爆炸过程中所起主导作用将爆炸模式分别确定为沉积煤尘扬尘爆炸和沉积煤尘火焰燃烧。进一步分析表明：不同爆炸作用模式显著改变冲击波和火焰传播规律,影响小规模诱导火焰区的长度...     

矿井瓦斯煤尘爆炸传播实验研究

煤矿中瓦斯爆炸容易引起煤尘参与爆炸,且掘进工作面是瓦斯煤尘爆炸事故的多发区域。在与实际矿井环境、几何条件相似的大型地下试验巷道中,进行了独头巷道瓦斯煤尘爆炸火焰、冲击波传播试验。试验中,瓦斯煤尘爆炸火焰到达各测点的时间与测点距离呈对数函数关系;爆炸火焰的传播速度在铺有煤尘段迅速上升,过了煤尘段开始下降;火焰区长度约为煤尘区长度的2倍;爆炸冲击波压力在铺有煤尘段前端降到最低值,然后迅速上升到最大值后下降。实验结论为煤矿隔抑爆装置的研制和安装提供了理论基础。瓦斯煤尘爆炸与单纯瓦斯爆炸相比,最大爆炸压力峰值大,火焰传播速度快;瓦斯煤尘爆炸的威力和破坏程度,要远远大于单纯瓦斯爆炸。因此,在煤矿实施防尘降尘技术,具有十分重要的意义。     

Experiment study on the propagation laws of gas and coal dust explosion in coal mine

The experiment of gas and coal dust explosion propagation in a single laneway was carried out in a large experimental roadway that is nearly the same with actual environment and geometry conditions. In the experiment, the time when the gas and coal dust explosion flame reaches test points has a logarithmic function relation with the test point distances. The explosion flame propagation velocity rises rapidly in the foreside of the coal dust segment and comes down after that. The length of the flame area is about 2 times that of the original coal dust accumulation area. Shock wave pressure comes down to the rock bottom in the coal dust segment, then reaches the maximum peak rapidly and comes down. The theoretical basis of the research and assemble of across or explosion is supplied by the experiment conclusion. Compared with gas explosion, the force and destruction degree of gas and coal dust explosion is much larger. Supported by the National Basic Research Program (973) (2005CB221506); the Open Research Fund Program of Shandong University of Science and Technology (MDPC0611)     

瓦斯煤尘爆炸传播特性的实验研究

在断面为7.2 m²、长为658 m的实验巷道内,用cs2092H多通道动态数据采集分析仪,模拟煤矿掘进巷道,对瓦斯、煤尘爆炸过程中的爆炸冲击波能量、传播速度、衰减规律以及爆炸灾害的波及范围进行了实验研究.结果表明,瓦斯、煤尘爆炸压力波衰减慢,爆炸传播距离远,且传播距离随瓦斯数量以及瓦斯、煤尘分布的变化而变化.与瓦斯爆炸相比,煤尘爆炸的剧烈程度强,坑道中煤尘的焦化明显,且可燃物灼烧情况可作为瓦斯煤尘爆炸的爆源点确认判据.     

Research on numerical emulator of mine methane and coal dust explosion

The mathematical physics model of mine methane and coal dust explosion propagation was established in the research, by using continuous phase, combustion, particulate equations of mathematical physics. Based upon the data from mine methane drainage roadway explosion, and mine methane and coal dust explosion propagation experimental studies, the numerical emulator system of mine methane and coal dust explosion software was developed by using prevalent flow simulation platform, which can be used to simulate the explosion accidents process effectively. In addition, the system can also be used to determine whether coal dust involved in the explosion, and to simulate accurately the transition from deflagration to detonation in methane explosion, propagation velocity of explosion shock, attenuation pattern, and affected area of explosion.