共查询到17条相似文献,搜索用时 156 毫秒
1.
木粉最低着火温度的实验研究 总被引:1,自引:0,他引:1
为评价木粉着火爆炸危险性,保证安全生产,采用GodbertGreenwald恒温炉研究粉尘浓度、粒径及分散压力对木粉尘云最低着火温度的影响。结果表明:木粉着火敏感质量浓度为424 g/m3,此浓度下最低着火温度为402℃;粉尘粒径从38μm变化到45μm时,木粉最低着火温度由474℃升高到541℃;粉尘质量恒定为100 mg,分散压力由20 kPa升高到50 kPa,木粉最低着火温度由402℃变化为440℃。 相似文献
2.
《中国粉体技术》2017,(6):40-46
以某纤维板生产线的速生杨、马尾松、南方硬杂木的混合砂光粉尘作为研究对象,在分析粉尘粒径及其分布、可挥发分及形貌特征的基础上,采用20 L爆炸球对砂光粉尘进行燃爆实验,探索砂光粉尘的浓度对粉尘燃爆特征的影响,并对爆炸前、后粉尘的热稳定性和特征官能团进行探讨。结果表明,当砂光粉尘质量浓度增加到1 000 g/m3,最大爆炸压力达到最大值0.761 MPa;此后,粉尘浓度的增加反而使砂光粉的最大爆炸压力减小;当粉尘质量浓度增加到1 250 g/m3时,爆炸指数达到最大值17.62 MPa·m/s,且爆炸危险分级为St1(弱爆炸)。实验还采用最小点火能测试系统、热板炉和GodbertGreenwald炉研究了砂光粉尘的燃烧特性,结果表明,粉尘最小点火能为30~100 m J,粉尘层最低着火温度为300℃,粉尘云最低着火温度为420℃。 相似文献
3.
为了全面地认识玉米淀粉粉尘爆炸的敏感性和爆炸破坏效应,分别采用粉尘云着火温度装置、20 L球粉尘爆炸装置和粉尘云火焰传播装置对玉米淀粉的粉尘云着火温度、爆炸下限质量浓度、爆炸压力、爆炸氧极限浓度以及粉尘云火焰传播过程进行了研究。结果表明:玉米淀粉粉尘云最低着火温度在380~390℃之间;粉尘云爆炸氧极限浓度(体积分数)在10%~11%之间;爆炸下限质量浓度和最大爆炸压力随着化学点火具质量的增加而呈现出不同的变化特征,随着化学点火具质量的增加,玉米淀粉的爆炸下限质量浓度逐渐降低,而玉米淀粉爆炸压力逐渐升高。在不同的粉尘质量浓度条件下,粉尘云火焰传播速度和火焰温度有一定的变化,在粉尘质量浓度为500 g/m3时,火焰传播速度和火焰温度均达到最大值,分别为13.81 m/s和1 107℃。 相似文献
4.
为研究锆金属粉尘云燃烧的基础特性参数,从而为其安全性能提供依据,采用哈特曼管试验系统和最低着火温度测定系统分别对锆金属粉尘云的最小点火能(MIE)和最低着火温度(MIT)开展试验研究。分别研究了锆金属粉尘云质量浓度、点火延迟时间和喷粉压力对MIE的影响,以及粉尘云质量浓度对MIT的影响。结果得出:中位径为33.49 μm的锆金属粉尘云的MIE在1~3 mJ之间;在50~500 g/m3质量浓度范围下,随着质量浓度增大,MIE先减小后增大,在质量浓度为400 g/m3时达到最小;点火延迟时间从10 ms增至180 ms,MIE先减小后增大,在60 ms时达到最小;喷粉压力从0.4 MPa增至1.0 MPa,MIE先减小后增大,在0.6~0.8 MPa间达到最小。该粒度锆金属粉尘云的MIT为210 ℃左右,在一定浓度范围下,MIT随粉尘浓度的增加而减小。 相似文献
5.
《中国粉体技术》2017,(6)
为了研究烟草粉尘阴燃发生的影响因素,运用锥形量热仪测定粉尘的热释放速率,改进现有的粉尘层最低着火温度测试仪,将3组不同粒径的的烟草粉尘置于热表面上进行阴燃实验研究。结果表明:制丝粉、切片粉、卷包烟末热释放速率峰值分别为90、91、75 k W/m2,切片粉火焰传播速度最快。峰值最低的卷包烟末于50 s左右率先热释放,切片粉制丝粉随后分别于75、80 s左右进行热释放;阴燃过程可进行阶段性分析,其中水分蒸发燃料氧化放热阶段粉尘温度相对稳定攀升,于氧化放热阶段温度突变,因此控制阴燃的产生,必须于水分蒸发燃料氧化放热阶段之前控制其发展趋势,做出相应有效的预警方案;粉尘顶层率先发生阴燃,随后阴燃逐渐向下传播直至粉尘完全燃尽;粉尘层达到阴燃温度时,顶层升温速率最高,中层底层在未发生阴燃时,顶层阴燃有预热作用;阴燃时间和实验持续时间都是随着粒径的增大而增大;粒径越小阴燃各阶段持续时间越短,致使阴燃越迅速越难控制。 相似文献
6.
7.
为了研究粒径对煤粉云最低着火温度特性的影响,采用粉尘云最低着火温度测试装置测试了不同粒径下煤粉云的最低着火温度,并结合ReaxFF分子动力学对其反应机理进行了微观层面的探讨。结果表明:当煤粉中位径在34 μm时,煤粉云的最佳着火质量浓度为750 g/m3,最低着火温度为550 ℃;随着煤粉粒径的增加,煤粉云最低着火温度逐渐增大,当煤粉中位径达到124 μm,煤粉云最低着火温度上升至650 ℃。通过ReaxFF分子动力学对煤粉热解过程的计算结果表明:随着反应的进行,大分子煤结构逐步分解,芳香环、C—C键、C—O键和C—H键等断裂,产生更小的分子结构,其中,H2、H2O、CO2和CH2O等小分子产生的数量逐渐增多;H·自由基和OH·自由基在反应初期有明显的数量变化,且其含量对于最终稳定产物有重要影响。 相似文献
8.
9.
《中国粉体技术》2015,(5):93-96
为了评价惰性介质对煤粉着火爆炸危险性的影响,保证安全生产,采用Godbert-Greenwald恒温炉装置研究分散压力,惰性介质NH4H2PO4、KH2PO4、Ca(H2PO4)2、CaCO3粉体的含量及NH4H2PO4、CaCO3粉体的粒径对煤粉尘云最低着火温度的影响。结果表明:高分散压力对煤粉尘云的影响更显著,最佳分散压力为0.03 MPa,此时煤粉尘云的最低着火温度最低,为594℃;随着惰性介质含量的增大,煤粉尘云的最低着火温度升高,并且存在突变浓度,NH4H2PO4、KH2PO4、Ca(H2PO4)2粉体的突变浓度(质量分数)为28.6%,CaCO3的为33.3%;惰性介质按对煤粉尘云最低着火温度的抑制效果由强到弱的顺序为NH4H2PO4、Ca(H2PO4)2、KH2PO4、CaCO3;煤粉尘云的最低着火温度随惰性介质粒径的减小而升高,CaCO3粉体粒径变化对抑制效果的影响大于NH4H2PO4的。 相似文献
10.
《工程爆破》2022,(3)
为了研究石松子粉火焰传播特征,采用哈特曼管装置对石松子粉在燃烧管中进行试验,利用高速摄影和红外热成像技术记录石松子粉火焰传播过程,并对石松子粉火焰传播速度和火焰温度变化情况进行了分析。结果表明:点火能量为200mJ,粉尘浓度在125500g/m500g/m3范围内,火焰在燃烧管中向上传播所达到的最大速度随着粉尘浓度的增加先增大后减小;在石松子粉浓度为250g/m3范围内,火焰在燃烧管中向上传播所达到的最大速度随着粉尘浓度的增加先增大后减小;在石松子粉浓度为250g/m3时达到最大速度11.08m/s;火球的面积随着时间变化呈现先增大后减小的趋势,在60ms时达到最大,同时达到最高温度1100℃;随着火焰的向上传播,火焰的最高温度区域也随之向上移动。 相似文献
11.
Yi Yin Jinhua Sun Yibin Ding Song Guo Xuechao He 《Journal of hazardous materials》2009,170(1):340-344
To reveal the mechanisms of flame propagation through the hardly volatile metal dust clouds clearly, the flame propagating through zirconium particle clouds has been examined experimentally. A high-speed video camera was used to record the propagation process of the flame. Combustion zone temperature was detected by a fine thermocouple. Based on the experimental results, structure of flame and combustion courses of zirconium particles were analyzed, the combustion propagation in zirconium dust was investigated, and the velocity and temperature characteristics of the combustion zone were also elucidated. The combustion zone propagating through zirconium particle clouds consists of luminous particles. Particle concentration plays an important role in the combustion zone propagation process. With the increase of zirconium particle concentration, the maximum temperature of the combustion zone increases at the lower concentration, takes a maximum value, and then decreases at the higher concentration. It is also found that the propagation velocity of the combustion zone has a linear relationship with its maximum temperature. 相似文献
12.
为研究水雾对自由堆积状态黏塑性炸药PBXN-5粉末燃烧的抑制作用,搭建了开放式燃烧试验装置,选用了粒度范围D98=425 μm的PBXN-5粉末,分别对无水雾、喷水压力为0.5 MPa和2.0 MPa 3种条件下堆积状态PBXN-5的燃烧过程进行了试验,获得了火焰传播过程及火焰温度随时间的分布曲线。结果表明:在水雾喷水压力为0.5 MPa 和2.0 MPa时,堆积状态PBXN-5的燃烧持续时间分别是自由燃烧时的32.6%和31.8%,说明水雾对于PBXN-5燃烧有很好的抑制作用;灭火时间分别为377.011 ms和115.004 ms,而且2.0 MPa时火焰的最高下降速率较0.5 MPa时有所增加,表明对于堆积状态PBXN-5火焰抑制效果来说,雾动量的影响较雾滴粒径强。 相似文献
13.
《Advanced Powder Technology》2020,31(8):3570-3581
A vertical dust combustion pipeline with high-speed photography, micro-thermocouple and pressure sensor was built to investigate the influence of ceramic foam on the wheat dust explosion flame. Ceramic foams with different parameters were adopted in this paper, and compared with metal mesh. The chemical structures of dust explosion residue were characterized by X-ray photoelectron spectroscopy. Results indicate that the wheat dust flame propagation and structure were significantly destroyed by ceramic foam. With the decreasing aperture or increasing layer, the blocking effect of ceramic foam was aggravated on the dust flame. The flame cannot pass through the ceramic foam with 20 PPI and 3 layers. On the upper end of ceramic foam, the flame temperature is positively proportional to the aperture but inversely proportional to the layers. With the PPI and layers of ceramic foam increases, the combustion pressure firstly increases and then decreases when the dust combustion intensity is strong. Ceramic foam shows the incentive effect to some extent on the combustion pressure, but the continuous inhibition effect is found for the metal mesh. 相似文献
14.
《Advanced Powder Technology》2022,33(6):103619
The bag type dust collector will accumulate dust during long-term operation, and the high temperature during operation will cause dust explosion. In this paper, with the dust removal system involved in the “8·2” Kunshan dust explosion accident taken as the research background, the minimum ignition temperature and lower explosion limit experiments are carried out on aluminum powder with different particle sizes (10–60 μm) by using the lowest ignition temperature test device and the 20 L near-spherical explosive device. The dust concentration distribution and temperature field in the bag type dust collector are analyzed through the CFD-FLUENT software. Through the analysis of the experimental results, it is found that when the particle size of aluminum powder is 19 μm, the minimum ignition temperature is 585 °C, and the lower explosion limit of concentration is 0.04 kg/m3. The simulation results indicate that the dust particles gather in the dust collecting bucket, and the aluminothermic reaction occurs in the dust collecting bucket. The temperature of the upper and right parts in the dust collecting bucket is above 600 °C, which exceeds the minimum ignition temperature. At the interface between the dust hopper and the dust collecting bucket, the concentration of aluminum powder reaches 0.126 kg/m3, which exceeds the lower explosion limit of aluminum powder. 相似文献
15.
煤尘爆炸是矿井安全开采的主要危险源之一。以褐煤煤尘为研究对象,探究煤尘粒径对煤尘火焰传播过程的影响。用高速摄影装置记录火焰的传播过程,进而分析不同粒径下煤尘爆炸火焰传播的高度和速度。为进一步分析煤尘燃烧过程中的化学反应机理,借助反应分子动力学方法对煤分子燃烧中的初始热分解过程进行了模拟。研究结果表明:爆炸火焰传播高度呈先增加、后稳定的趋势,传播速度呈先增大、后减小的趋势;随着煤尘粒径的减小,火焰传播高度和传播速度均呈增大的趋势;当煤尘粒径为10.5 μm时,火焰传播高度和传播速度的峰值分别为623 mm和4.3 m/s;煤尘热分解主要产物为H2、H2O、CO2和CH2O,这些产物进一步与氧气的结合会促进煤尘燃烧和火焰传播过程,使得整个体系燃速加快。为煤尘热分解和燃烧提供了较为充分的数据基础。 相似文献
16.
17.
Explosibility and ignitability studies of air/cork dust mixtures were conducted in a near-spherical 22.7 L explosibility test chamber using pyrotechnic ignitors and in a furnace of 1.23 L. The suspension dust burned as air-dispersed dust clouds and the uniformity of the dispersion inside the chamber was evaluated through optical dust probes. The range of tested particle sizes went from a mass median diameter of 47.4 to 438.3 microm and the covered dust cloud concentration was up to 700-800 g/m(3). Measured explosion parameters included minimum explosible concentration, maximum explosion pressure, maximum rate of pressure rise and minimum autoignition temperature. The effect of dust particle size on flammability was evaluated and it was found that the minimum explosible concentration is around 40 g/m(3) and it is relatively independent of particle size below 180 microm. Maximum explosion pressure of 7.2 bar and maximum rate of pressure rise of 179 bar/s were detected for the smallest tested sizes. The limitations on the rates of devolatilization of the solid particles became rate controlling at high burning velocities, at high dust loadings and for large particle sizes. The effect of initial pressure on the characteristic parameters of the explosion was studied by varying the initial absolute pressure from 0.9 bar to 2.2 bar, and it was found that as initial pressure increases, there is a proportional increase of minimum explosion limit, maximum explosion pressure, and maximum rate of pressure rise. The influence of the intensity of the ignition energy on the development of the explosion was evaluated using ignition energies of 1000 J, 2500 J and 5000 J, and the experimental data showed that the value of 2500 J is the most convenient to use in the determination of minimum explosion concentration. The behavior of the cork dust explosion in hybrid methane air mixtures was studied for atmospheres with 2% and 3.5% (v/v) of methane. The effect of methane content on the characteristic parameters of the explosions was evaluated. The conclusion is that, the hazard and explosion danger rise with the increase of methane concentration, characterized by the reduction of the minimum dust explosion concentration. The minimum autoignition temperature obtained with the thermal ignition tests was 540 degrees C and the results have shown that this value is independent of particle size, for particles with mass median diameters below 80 microm. 相似文献