不同初始压力下可爆预混气体通过波纹板阻火器的淬熄特性研究

阻火器是一种应用广泛的爆炸阻隔装置。为了深入理解影响阻火器性能的因素,通过实验方法探究了不同初始压力下可爆预混气体通过波纹板阻火器的淬熄特性。结果表明,可燃气的活性、体积分数和初始压力均会影响火焰速度稳定性、传播模式以及淬熄难度。实验发现火焰传播具有3种模式:直接淬熄、穿过阻火单元后逐渐淬熄、淬熄失败。可淬熄的最大初始压力p_lim用以表征火焰淬熄难度,虽然其最小值位于化学计量比,但仍在一定体积分数范围内保持恒定。此外,基于传热作用得到密闭管道中丙烷-空气预混气爆燃阻火速度公式,并进行了实验验证。

On quenching characteristics of combustible premixed gas through a crimped-ribbon flame arrester at different initial pressures

The crimped flame arrester is a common disaster prevention and control device. Most of the research focuses on the higher-pressure working conditions instead of the pressure lower than 0.1 MPa when it applies in special areas or environments. This paper explores the quenching characteristics of different combustible gas-air mixtures passing through crimped ribbon flame arresters at different initial pressures to replenish the low-pressure protection test and understand the factors affecting the performance of the flame arrester deeply. The experiments were carried out in the DN80 circular pipe. And the crimped ribbon plate slit channel with a cross-section of an approximately equilateral triangle is 38 mm long and 0.8 mm high. The experimental gases are premixed propane-air with a volume fraction of 4.2% and premixed ethylene-air with different concentrations obtained according to the partial pressure method. The ignition voltage is 10 kV. It is found that the activity, concentration, and initial pressure of combustible gas will affect the stability of flame velocity, propagation mode, and quenching difficulty. The results show that there are three modes of flame propagation: direct quenching, quenching after passing through the flame retardant unit, and quenching failure. They can be explained as the flame not passing through the slits, the flame passing through the slits but being extinguished before reaching the pipe end, and the flame keeps spreading until the pipe end. Also, the velocity oscillation occurs on the unprotected side of the pipeline, and the velocity rises incredibly when the quenching failed flame passes through the protected side. The formula of deflagration flame quenching velocity of premixed propane-air in a closed pipe was established based on the heat transfer effect and verified by the quenching experiment of premixed gas with a volume fraction of 4.2%. The maximum initial pressure is defined as the limit pressure that quenching would fail at initial pressure higher than it. It is proposed to use the limit pressure to characterize the degree of quenching difficulty. It is worth remarking that quenching is the most difficult at stoichiometric concentration, where the limit pressure is the smallest, and the limit pressure will remain constant within a certain concentration range.