生物质气化合成气层流燃烧特性的模拟

Simulation Study on Laminar Combustion Characteristics of Biomass Gasification Syngas

生物质气化合成气层流燃烧特性的研究对低热值合成气有效地用于发动机、锅炉和燃气轮机具有重要意义。基于定容燃烧弹系统,研究了常温常压下、当量比为0.6~1.5范围内、不同组成CO/H_(2)/CH4/CO_(2)火焰的层流燃烧速度。结果显示,增加H_(2)的体积分数,其绝热火焰温度有所下降,而H_(2)体积分数较少CO体积分数较多的F1组分气体,绝热火焰温度达到这5组气体的最高,与层流火焰速度结果相反,层流火焰速度表现为H_(2)体积分数越高,速度越高。与CO相比H_(2)对生物质合成气绝热火焰温度的影响相对较小。随着H_(2)体积分数的增加,相同温度与压力下,正向反应产生的量占主要地位,高活性基O、OH、H的不断产生促进了层流火焰燃烧的速度。H_(2)体积分数不同的合成气,火焰中含量最多的自由基是H基,接着是OH基和O基。随着H_(2)体积分数的增加,H基的浓度略有下降。贫燃混合物火焰更易受热扩散不稳定性的影响且随着氢气体积分数的增加而增强;在常温常压下,富氢燃料在高稀释比下的高热扩散性对火焰传播更重要。

Laminar combustion characteristics of biomass gasification syngas is of great significance for the effective application of low calorific value syngas to engines,boilers and gas turbines.Based on the constant volume combustion system,the laminar combustion velocity of CO/H_(2)/CH4/CO2 flame with different composition in the range of equivalent ratio 0.6-1.5 at room temperature and pressure was studied.The results show that the adiabatic flame temperature decreases with the increase of H_(2)volume fraction,while the adiabatic flame temperature reaches the highest of the five groups of gases for the F1 component gas with less H_(2)volume fraction and more CO volume fraction.Contrary to the results of laminar flame velocity,the laminar flame velocity shows that the higher the H_(2)volume fraction,the higher the speed.H_(2)has less influence on the adiabatic flame temperature of biomass syngas than CO.With the increase of H_(2)volume fraction,at the same temperature and pressure,the amount generated by the forward reaction is dominant,and the continuous production of highly active groups O,OH and H promotes the laminar flame combustion speed.For syngas with different H_(2)volume fractions,the most abundant free radicals in the flame are H group,followed by OH group and O group.With the increase of H_(2)volume fraction,the content of H group decreased slightly.The flame of poor combustion mixture is more susceptible to thermal diffusion instability and increases with the increase of hydrogen concentration.The high thermal dispersion of hydrogen-rich fuel at high dilution ratio is more important for flame propagation at room temperature and pressure.