超低浓度煤层气在流态化蓄热装置中的燃烧特性

A numerical study on the ultra-low concentration coalbed gas combustion in a fluidized-bed regenerative combustion device

超低浓度煤层气中甲烷体积分数低于5%,常规技术很难加以利用,而含有石英砂颗粒的流态化蓄热装置对超低浓度煤层气的燃烧利用提供了平台。为此,采用数值模拟的方法,研究了含有不同甲烷浓度的超低浓度煤层气在流态化蓄热装置中的燃烧特性,并和绝热燃烧时的工况进行了对比,分析了燃烧特性、蓄热特性、氮氧化物生成等变化规律。结果表明,流态化蓄热装置在煤层气的体积分数不低于3%时可以维持燃烧;与采用绝热工况相比,采用蓄热颗粒之后,燃烧反应向布风板方向移动,并主要发生在蓄热颗粒组成的床层以内;燃烧后氮氧化物排放量极少。

The volume ratio of methane in ultra-low coalbed gas is less than 5%,so it is difficult to be utilized by conventional technologies.However,its combustion and utilization are found to be valuable in a regenerative combustion device with fluidized-bed reactor filled by quartz grains.Therefore,a numerical study was carried out to analyze the combustion characteristics of the ultra-low concentration coalbed gases with different volume ratios of methane in a fluidized-bed regenerative combustion device,and a comparison analysis was made on the combustion features,heat-accumulating performance,and the generation of nitrogen oxides under two conditions of adiabatic combustion and regenerative combustion.This study results show that the limit of methane concentration is not less than 3%,under the condition of which the combustion of ultra-low content coalbed methane can be maintained in this device.In comparison with adiabatic combustion,the regenerative combustion moves to the air distributor and mainly occurs within the fluidized bed reactor filled by quartz grains.After combustion,nitrogen oxides are found to be discharged in a very tiny quantity.