Characteristics of dust explosion relief flame under high activation pressure

doi:10.16085/j.issn.1000-6613.2020-1995

Abstract

Abstract:

In order to obtain the flame propagation characteristics during the dust release process under high activation pressure conditions, a 20L spherical explosive device was used to carry out the explosion research under the dust concentration of 400—900g/m³ and the activation pressure of (0.78—2.1)×10⁵Pa. The experimental results show that the flame release process is divided into five stages: ignition and film breaking, under-expanded jet flame, turbulent jet flame, turbulent combustion flame, and flame back-burning. The maximum flame width appears in the second stage, and the maximum flame length appears in the third stage. The length and propagation speed of the vent flame vary with time, which first increase and then decrease at different activation pressures. The variation range of the maximum width of the vent flame is 0.146—0.269m, and the variation range of the maximum length of the vent flame is 0.41—0.666m. The predicted maximum possible range of released flame was S_max1=0.179m². The possible maximum range of the release flame calculated by the MATLAB software was S_max2=0.122m², andthe flame area of S_max2was 68% S_max1.

Key words: dust explosion, venting, flame propagation, activation pressure, flame area

摘要：

为得到高开启压力条件下粉尘泄爆过程中火焰传播特性，采用20L球形爆炸装置，在开启压力为(0.78~2.1)×10⁵Pa的条件下对粉尘浓度为400~900g/m³的玉米粉尘开展爆炸泄放试验研究。结果表明：火焰泄放过程分为点火与破膜、欠膨胀射流火焰、湍流射流火焰、湍流燃烧火焰、火焰回燃5个阶段，最大火焰宽度出现在火焰泄放过程的第2阶段，最大火焰长度出现在火焰泄放过程的第3阶段；不同开启压力下，泄爆火焰长度和火焰传播速度随时间先增大后减小；泄放火焰最大宽度变化范围为0.146~0.269m，泄放火焰的最大长度变化范围为0.41~0.666m。通过预测计算得出泄放火焰可能出现的最大范围为S_max1=0.179m²，采用MATLAB软件定量计算求得的泄放火焰可能出现的最大范围的横截面积为S_max2=0.122m²，定量计算得到的S_max2达到预测值S_max1的68%。

关键词: 粉尘爆炸, 泄爆, 火焰传播, 开启压力, 火焰面积

CLC Number:

X932

CHENG Fangming, NAN Fan, WANG Jiayi, LYU Xiao’an, GE Tianjiao, QI Ke. Characteristics of dust explosion relief flame under high activation pressure[J]. Chemical Industry and Engineering Progress, 2021, 40(8): 4135-4143.

程方明, 南凡, 王家祎, 吕晓安, 葛天娇, 齐柯. 高开启压力条件下粉尘爆炸泄压火焰特性[J]. 化工进展, 2021, 40(8): 4135-4143.

Figures/Tables 12

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火焰形态	火焰模型	火焰图像（1.45×10⁵Pa，600g·m^-3）
点火与破膜
欠膨胀射流火焰（出现最宽火焰）
湍流射流火焰（出现最长火焰）
湍流燃烧火焰
火焰回燃

火焰形态	火焰模型	火焰图像（1.45×10⁵Pa，600g·m^-3）
点火与破膜
欠膨胀射流火焰（出现最宽火焰）
湍流射流火焰（出现最长火焰）
湍流燃烧火焰
火焰回燃

开启压力 /Pa	火焰最大长度/m
开启压力 /Pa	400g·m^-3	500g·m^-3	600g·m^-3	700g·m^-3	800g·m^-3	900g·m^-3
0.78×10⁵	0.426	0.41	0.427	0.416	0.492	0.56
1.13×10⁵	0.496	0.448	0.51	0.439	0.481	0.422
1.45×10⁵	0.425	0.461	0.534	0.464	0.436	0.461
1.8×10⁵	0.41	0.544	0.49	0.491	0.53	0.485
2.1×10⁵	0.476	0.506	0.494	0.666	0.644	0.647

开启压力 /Pa	火焰最大长度/m
开启压力 /Pa	400g·m^-3	500g·m^-3	600g·m^-3	700g·m^-3	800g·m^-3	900g·m^-3
0.78×10⁵	0.426	0.41	0.427	0.416	0.492	0.56
1.13×10⁵	0.496	0.448	0.51	0.439	0.481	0.422
1.45×10⁵	0.425	0.461	0.534	0.464	0.436	0.461
1.8×10⁵	0.41	0.544	0.49	0.491	0.53	0.485
2.1×10⁵	0.476	0.506	0.494	0.666	0.644	0.647

开启压力 /10⁵Pa	火焰最大宽度/m
开启压力 /10⁵Pa	400g·m^-3	500g·m^-3	600g·m^-3	700g·m^-3	800g·m^-3	900g·m^-3
0.78	0.146	0.158	0.163	0.151	0.174	0.149
1.13	0.156	0.15	0.184	0.139	0.269	0.2
1.45	0.182	0.182	0.19	0.147	0.174	0.22
1.8	0.161	0.147	0.198	0.218	0.217	0.213
2.1	0.189	0.167	0.197	0.191	0.188	0.25