煤粉等温燃烧挥发分、焦炭耦合作用及同步NO释放规律

Experimental study on coupling and NO emission of volatiles and coal char during the isothermal combustion of pulverized coal

利用自制的等温热重装置及NO测量系统,对煤粉及煤焦进行了等温燃烧实验,研究了挥发分与焦炭燃烧耦合作用及同步NO释放特性。结果表明:煤粉等温燃烧过程中,挥发分对焦炭燃烧同时存在促燃和"抢氧"作用。随着温度降低,挥发分对焦炭的促燃作用增强,"抢氧"作用减弱。温度升高,挥发分NO和焦炭NO转化率均呈上升趋势,焦炭NO贡献率升高。煤的煤化程度降低,挥发分对焦炭的促燃作用和"抢氧"作用均增强,挥发分NO和焦炭NO转化率均上升,焦炭NO贡献率升高。不同氧气体积分数下,均存在挥发分对焦炭的促燃作用。环境氧气体积分数降低,挥发分的"抢氧"作用时间延长,挥发分燃烧段和焦炭燃烧段出现分离趋势,挥发分NO和焦炭NO转化率均下降,焦炭NO贡献率下降。

The coupling combustion characteristics of volatiles and coal char and the NO emission characteristics were studied using the isothermal thermogravimetric and NO emission monitoring system.The results show that volatiles have effect of promoting burning and robbing oxygen on coke combustion under the isothermal combustion process of pulverized coal.The promoting effect enhances and the robbing oxygen effect reduces with the temperature decreases.Volatile-NO and char-NO conversion increase,and the contribution of char-NO increases with temperature increase.As the coal rank decreases,the promoting burning and robbing oxygen effect of volatiles on coal char become much stronger,volatile-NO and char-NO conversion increase,and the contribution of char-NO increases.Volatiles have promoting effect on coke combustion under different oxygen concentrations.As environmental oxygen concentration decreases,the robbing oxygen time of volatiles become longer,the burning process of volatile and coal char show the tendency of separation.Volatile-NO and char-NO conversion decrease,and the contribution of char-NO decreases.