高温预热煤粉的无焰燃烧特性

Flameless combustion of high preheated pulverized coal

为减少煤粉燃烧中的NO_x排放,提出采用预热燃烧工艺,实现煤粉的无焰燃烧,在30kW煤粉无焰燃烧实验台上以神木烟煤粉为燃料进行相关研究,探讨煤粉的预热特性及无焰燃烧中烟气成分的变化规律。结果表明:神木烟煤在预热燃烧器中可以被预热至800℃以上,预热后产生的高温煤气为强还原性气体,其主要成分为CO、H_2、CH_4、N_2和CO_2;预热燃料在下行燃烧室中能实现稳定无焰燃烧,且燃烧室内温度分布均匀,峰值温度低; NO_x在燃料喷口附近生成,在主燃烧区被大量还原,最终NO_x排放为107. 64 mg/m^3(@6%O_2,尾部烟气成分以体积分数为6%的O2为基准),通过合理组织燃烧,能有效控制NO_x生成,减少NO_x排放。

A fuel preheating technique was proposed to achieve coal flameless combustion and de-NOx emissions. Experimental research was carried out with Shenmu bitumite,and coal preheated characteristic and variation law of flue gas compositions in flameless combustion were discussed. The results show that Shenmu bitumite can be preheated up to above 800 ℃,and the high-temperature coal gas generated by coal preheating has strong reducing action,which contains mainly CO,H2,CH4,N2 and CO2. Stable flameless combustion can be achieved with preheated fuels in down-fired combustor,and the temperature distribution is uniform and the peak temperature is low in combustor. NOxis generated near the fuel nozzle and reduced mainly in the main combustion zone,and the final NOx emission value is 107. 64 mg/Nm3(@6% O2). The generation of NO can be controlled and NOx yield can be reduced by rational combustion organization.