贫燃条件下氢气比例对甲烷/氢气预混气火焰传播的影响

Effect of hydrogen ratio on flame propagation of CH_(4)-H_(2) premixed gas under fuel-lean conditions

为探究贫燃条件下氢气对甲烷/氢气混合气体火焰传播和传爆能力的影响,测定了甲烷/氢气混合气体的最大试验安全间隙(MESG),在安装波纹板阻火器的DN80管道试验装置上开展火焰传播试验。结果表明:在贫燃条件下,火焰速度受Ф和当量比的控制,当Ф增大时,当量比为主导因素,火焰速度降低;随Ф增加,混合气体的整体活性增大且在Ф小于25%时,火焰传播速度曲线变化相似,在Ф大于30%时,火焰传播速度曲线稳定性较弱,MESG快速下降,临界阻火速度降低,火焰无法在阻火器内淬熄,IIA类爆燃阻火器无法满足阻火需求。

This paper aims to investigate the effect of hydrogen on the flame propagation and explosive transmission capacity of methane/hydrogen mixture under the condition of low-burning,the maximum experimental safety gap value(MESG)of methane/hydrogen mixture was determined,and the explosion test was carried out on the DN80 pipeline test device with corrugated plate flame arrester.The safety velocity of preventing flame transmission at different initial pressures and gas component mixtures was gained.The experimental results indicate that the safety velocity of preventing flame transmission of the fuel-lean premixed gas mixture is varied from hydrogen addition ratio Ф and equivalence ratio.As the hydrogen concentration increases,the equivalence ratio becomes the dominant factor that affects the flame velocity,but the overall flame velocity in the pipeline decreases.Under the disturbance action of a flame arrestor fitted with a single layer fire core,the flame propagation accelerates with the increase of initial pressure,the maximum velocity of preventing flame transmission appears negative correlation with hydrogen addition ratio Ф.Whereas,the maximum pressure of preventing flame transmission decrease first and then increases gradually.The activity of the mixture increases with hydrogen addition ratio Ф.The variation tendency of flame propagation velocity curves is similar when the value of Ф is less than 25%,while their stabilities tend to be weaker when Ф is above 30%.According to the Maximum Experimental Safe Gap(MESG)experiments,the MESG of the premixed mixture decreases rapidly with the increases of hydrogen addition ratio Ф,which indicates the activity of the premixed mixture is enhanced.The change of flame velocity and MESG can clearly reflect the effect of the hydrogen addition on methane/hydrogen/air mixture explosion.Therefore,the deflagration flame arrester fails faster as the volume fraction of hydrogen increases,the explosive flame of methane mixed hydrogen and air generated in the pipeline could not be quenched by installing a Class IIA deflagration flame arrester.