Study On Deflagration Inhibition Of Hydrogen/Methane Premixed Gas By Gas-solid Two-phase Medium

Flammable gas explosion prevention and control is an important element in the field of industrial safety and production.Hydrogen/methane mixed fuel,as a key step towards hydrogen energy,have proven their effectiveness in utilisation,but have attracted the attention of many scholars in terms of their safe use.Therefore,this paper takes hydrogen/methane mixed fuel as the research object,using experimental research as the main and theoretical analysis as the auxiliary means to carry out the research.Therefore,this paper takes the hydrogen/methane premixed gas as the research object,and carries out the research by means of experimental research,theoretical analysis and numerical calculation.The experimental study on hydrogen/methane deflagration and explosion suppression was carried out by using 20L spherical explosive device combined with schlieren meter and spectrometer.By changing the volume fraction of inert gas,the mass concentration of powder and the ratio of gas/solid two-phase inhibitor,the effects of single-phase inert gas,powder and gas/solid two-phase inhibitor on hydrogen/methane deflagration characteristics were carried out.The variation rules of explosion limit parameters,pressure parameters,flame structure parameters,laminar flame propagation velocity and free radicals in the process of hydrogen/methane deflagration are analyzed,and the key control parameters of explosion suppression are obtained.the coupling effect of inert gas and powder on hydrogen/methane explosion is analyzed,and the synergistic mechanism of gas-solid two-phase medium inhibiting hydrogen/methane explosion is revealed.It provides scientific support for the development of explosion suppressants and explosion suppression technology in active explosion suppression devices.In terms of hydrogen/methane deflagration parameters,the explosion limit parameters,pressure parameters,flame structure parameters,laminar flame propagation velocity and free radicals in the deflagration process are obtained.With the addition of inert gas,the explosion upper limit of hydrogen/methane premixed gas decreases and the lower limit increases.When the hydrogen addition ratio is less than 30%,the explosion risk of hydrogen/methane premixed gas is less.Under the condition of rich oxygen,the higher the proportion of hydrogen in hydrogen/methane premixed gas,the easier it is to produce cellular flame.When the hydrogen addition ratio is more than 30%,the explosive destructive force begins to increase,and this law does not change with the change of hydrogen/methane premixed gas equivalent ratio.The hydrogen addition ratio in hydrogen/methane premixed gas plays a leading role in flame laminar propagation,while the change of equivalent ratio plays a secondary role.The laminar flame propagation velocity calculated in this paper is basically consistent with the laminar flow velocity of hydrogen/methane premixed gas calculated by GRI Mech 3.0.In the deflagration reaction kinetics of hydrogen/methane premixed gas,R38:H+O2=O+OH and R84:OH+H2=H+H2O are the key reaction steps in the deflagration process of hydrogen/methane premixed gas,which play a key role in the whole reaction.OH radical can be used as the key free radical in the process of hydrogen/methane deflagration.In the case of single inert gas suppression of hydrogen/methane deflagration,the hydrogen/methane premixed gas laminar flame is affected by buoyancy instability when the inert gas addition exceeds 15%in the presence of inert gas.Carbon dioxide suppresses the laminar flame propagation rate of hydrogen/methane premixed gases better than nitrogen.At 10%inert gas addition,the effect of inert gas addition on the peak hydrogen/methane premixed gas deflagration pressure is largely independent of changes in the proportion of hydrogen added.In the initial stages of flame development,the addition of inert gas reduces the rate of propagation of the stretching flame and the rate of stretching.The higher the inert gas addition ratio,the lower the initial stretching rate.The inert gas has less effect on the deflagration of hydrogen/methane premixed gases with hydrogen addition ratios above 70%.In terms of deflagration parameters such as deflagration limit,laminar burning rate and deflagration index,the hydrogen/methane premixed gas undergoes a sudden change at hydrogen addition ratios above 70%,that is,?=0.7 is the turning point in the explosive characteristics of the hydrogen/methane premixed gas.For the inhibition of hydrogen/methane deflagration by two-phase inhibitors,the best inhibition concentrations for pure methane were 65 g/m3,225 g/m3,500 g/m3,500 g/m3 and 500 g/m3 for fumed silica,ammonium polyphosphate powder,pure dry water material,10%APP modified dry water material and 20%APP modified dry water material,respectively.No complete inhibition under all operating conditions.For CO2-ammonium polyphosphate two-phase inhibitors,complete inhibition is not possible with less than 5%CO2 addition,complete inhibition is possible with 10%CO2 addition at less than 30%hydrogen addition,and complete inhibition is possible with 15%CO2 addition at less than 50%hydrogen addition.In the CO2-dry water materials under the action of two-phase inhibitor,hydrogen addition ratio of 70%of the premixed gas deflagration index is small,that is,the danger is small;hydrogen addition ratio of less than 30%,the size of the deflagration index basically does not change,the explosion risk is basically unchanged;all three dry water materials are under the 15%CO2 addition,when the hydrogen addition ratio of less than 30%can be completely inhibited.In addition,when the hydrogen addition ratio does not exceed 70%,the actual inhibition effect of the gas-solid two-phase inhibitor on the hydrogen/methane premixed gas is greater than the theoretical superposition value;the inhibition effect of the two-phase inhibitor on the hydrogen addition ratio of 70%of the hydrogen/methane premixed gas deflagration is equivalent to the inhibition effect of the two single-phase inhibitor superposition.Combined with the overall situation,the deflagration characteristics of hydrogen/methane premixed fuel can be divided into two turning points:30%and 70%hydrogen addition according to deflagration limit,laminar propagation speed,explosion hazard and inhibitor inhibition effect.that is,the three stages are 0-30%hydrogen content in the premixed fuel,30-70%and more than 70%respectively.Under the action of two-phase inhibitor,the radiation intensity of OH characteristic wavelength decreases during the deflagration of hydrogen/methane premixed fuel with different amount of hydrogen,which is shown by the gradual delay of the occurrence time of radiation signal,the decrease of the peak radiation intensity and the delay of peak time.The two-phase inhibitor reduces the production of OH during hydrogen/methane premixed gas deflagration,which directly reflects the inhibition of the hydrogen/methane deflagration reaction.In addition,there is a temporal agreement between the peak time of the pressure rise rate and the peak time of the OH radical signal during hydrogen/methane premixed gas deflagration and inhibition.