生物质/烟煤粉体燃料在空气分级燃烧下NO排放特性研究

Study on NO emission characteristics of biomass/bituminous coal pulverized fuel in air staged combustion

为了对小型生物质/煤粉工业锅炉低氮燃烧提供理论指导,采用两段式滴管炉试验系统模拟粉体工业锅炉热态环境,研究了生物质与煤在不同配风燃烧方式下的NO排放特性,考察了掺混生物质种类、生物质质量掺混比、配风比、过量空气系数等因素对NO排放量、燃料氮转化率以及对燃烧效率的影响。结果表明:在分级配风和单极供风条件下,煤粉掺烧生物质粉都有助于降低燃料氮向NO的转化率。相对于单级供风,分级配风可以降低燃料氮向NO的转化率,且存在NO排放最低的最佳配风比。但分级配风对燃料燃尽有负面影响,分级配风对粉煤燃尽的影响程度要大于对生物质粉的影响程度。对于分级配风和单级供风,增加过量空气系数有助于各种燃料的燃尽,但各燃料氮转化率均随过量空气系数的增加而上升。

In order to provide theoretical guidance for low-nitrogen combustion in small biomass/pulverized coal industrial boilers,a two-stage dropper furnace test system was used to simulate the thermal environment of powder industrial boilers,and the NO of biomass and coal in different air distribution combustion methods were studied.For emission characteristics,the effects of factors such as the types of blended biomass,biomass mass blending ratio,air distribution ratio,and excess air coefficient on NO emissions,fuel nitrogen conversion rate,and combustion efficiency were investigated.The results showed that under the condition of graded air distribution and unipolar air supply,the blending of pulverized coal with biomass powder could help reduce the conversion rate of fuel nitrogen to NO.It was compared with single-stage air supply,staged air distribution can reduce the conversion rate of fuel nitrogen to NO,and there was an optimal air distribution ratio with the lowest NO emission.However,the graded air distribution had a negative impact on the fuel burnout,and the graded air distribution had a greater degree of influence on the burnout of pulverized coal than on biomass powder.For graded air distribution and single-stage air supply,increasing the excess air coefficient helps to burn out various fuels,but the nitrogen conversion rate of each fuel increases with the increase of the excess air coefficient.