基于化学动力学的煤气化掺氨着火燃烧特性研究

Study on combustion characteristics of coal gasification gas doped with ammonia-based on chemical kinetics

掺氨燃烧是一种降低燃料含碳量的有效技术途径。采用详细化学动力学计算对煤化气合成气掺混氨气的着火延迟时间以及反应敏感性分析进行研究。结果表明,不同温度下,掺氨比变化对混合气着火时刻起相反的作用;高掺氨比在较高初始温度处会抑制燃料的着火进程,在较低初始温度下反之,转换点温度为988K。较高的初始压力和温度对掺氨混合气的反应活性起明显的促进作用;在中温环境下,压力由6 MPa提高至8 MPa、当量比由0.8提高到1.2均可显著加速着火过程,着火延迟时间分别降低0.96 ms和0.60 ms。化学反应敏感性分析发现,初始温度的提高会导致抑制燃料反应的低温体系基元反应转变为利于燃烧进程。

The addition of ammonia is a promising technological approach to reduce the carbon content in fuels.This study investigates the ignition delay time and reaction sensitivity of coal gasification synthesis gas blended with ammonia based on detailed chemical kinetic calculations.The results indicate that the ammonia content has contrasting effects on ignition delay time at different ambient temperatures.Higher ammonia content inhibits the ignition process at higher ambient temperatures but accelerates it at lower ambient temperatures,with a transition point temperature of 988 K.Higher initial ambient pressure and temperature significantly promote the reactivity of ammonia-mixed gases.Under the medium-temperature environment,elevating the pressure from 6 MPa to 8MPa and the equivalence ratio from 0.8 to 1.2 can significantly accelerate the ignition process,and the ignition delay time would be shortened by 0.96 ms and 0.60 ms,respectively.Chemical reaction sensitivity analyses found that an increase in initial temperature leads to a shift in the primitive reactions of the low-temperature regime that inhibit fuel reactions to favor combustion processes.