爆轰火焰在管道阻火器内的传播与淬熄特性

在水平封闭的直管中,采用自主研制的阻爆实验系统(包括传感器系统、配气系统、数据采集系统、点火系统等)对不同活性预混气体爆轰火焰在波纹管道阻火器内的传播与淬熄过程进行了实验研究。结果显示当可燃气体接近当量浓度时(丙烷4.2%、乙烯6.6%、氢气28.5%,均为体积分数),预混气体从点燃到火焰淬熄过程历时非常短,总体可分为4个阶段,缓慢燃烧阶段、快速燃烧阶段、加速燃烧阶段和超压振荡阶段。丙烷-空气、乙烯-空气预混气体在D=80 mm的管道阻火器中,爆炸压力峰值较高。当管道直径增加至400 mm时,爆炸压力峰值逐渐降低,其中乙烯-空气预混气体的爆炸压力峰值仅为3 MPa左右;氢气-空气预混气体的爆炸压力峰值随管径的增加呈递增趋势。对爆轰速度的研究结果表明,丙烷-空气、乙烯-空气预混气体爆轰速度数值相差不大,丙烷-空气预混气体甚至稍高些;而氢气-空气的爆轰速度数值较高。而且随着管径的增加,管壁热损失增大及其阻力因素等原因影响使预混气体爆轰速度趋向平稳。最后,从经典传热学理论出发,推导出了阻火单元厚度与爆轰火焰速度之间的关系。并结合实验数据,提出了爆轰安全阻火速度的计算方法,为工业装置阻火器的设计和选型提供更为准确的参考依据。

Detonation flame propagation and quenching characteristics in crimped-ribbon flame arrester

A self-designed explosion suppression experimental system including sensor detection system, gas mixing equipment, data acquisition device and electric spark ignition device was set up to investigate various fuel/air premix detonation flame propagation and quenching by crimped-ribbon flame arresters in horizontal pipe that closed at both ends. Detonation experiment showed that when the concentration of flammable gas was close to the stoichiometric ratio, (4.2% propane, 6.6% ethylene and 28.5% hydrogen, percentage by volume), the evolution process from ignition to flame quenching was very short. It could be divided into four stages: slow rise, quick rise, accelerate rise and pressure fluctuation. The peak detonation pressure for propane-air and ethylene-air was higher in D 80 mm flame arrester than other diameters. When pipe diameter increased to 400 mm, the detonation pressure was decreased gradually, especially for ethylene-air the pressure was only about 3 MPa. However, the peak detonation pressure of hydrogen-air was gradually increased with the increase of the pipe diameter. The result on detonation velocity indicated that its value for the premixed gas of propane-air was quite close to ethylene-air, even a little higher. However, the value of hydrogen-air premixed gas was relatively high. With the increase of the pipe diameter, the detonation velocity tended to be more stable due to the wall heat loss, the resistance factors and some other reasons. At the same time, it might be expected that the detonation safety flame velocity would be proportional to element thickness base on the classic theory of the heat transfer. Then, by using the experimental data, the detonation safety flame velocity calculation method was derived, which would provide more accurate reference for design and selection of crimped-ribbon flame arrester.