预热燃料在无焰燃烧模式下的NO_x排放特性

Flameless combustion and NO_x emissions of preheated fuel

采用燃料预热燃烧工艺,在30kW煤粉无焰燃烧实验台上探索高温预热燃料的无焰燃烧可行性,及其燃烧和NOx排放特性。结果表明:高挥发分的神木烟煤和低挥发分的气化细粉灰均能在该实验系统上实现稳定的无焰燃烧;煤粉经过预热过程,部分挥发份析出,部分焦炭气化,产生高温煤气和煤焦;高温预热燃料(煤焦和煤气)经燃料喷口进入燃烧室,进行分级燃烧,有效降低燃烧温度的峰值,燃烧温度分布更均匀,燃烧温度波动均低于10%;NOx主要来源于焦炭氮,在燃烧室的下游被焦炭的异相反应所还原;对于神木烟煤和气化细粉灰,NOx排放分别为90.4、96.7mg/m3(O2体积分数为6%时,@6%O2)。

Pulverized coal preheating combustion was on a 30 kW pulverized coal flameless combustion test rig to explore the feasible of solid fuel,and the characteristics of combustion and NOx emissions.It is shown that stable flameless combustion for Shenmu bitumite with high volatile matter and coal gasification fly ash with low volatile matter can be achieved in the test rig.During the preheating process,a part of volatile matter is released and a part of char is gasified,and then high temperature preheated fuel (gas and char) enter into a down-fired combustor through a fuel nozzle forming staged combustion.It decrease effectively the temperature peak and make the temperature profile more uniform.Fluctuation of the combustion temperature in the down-fired combustor is less than 10%.NOx was mainly derived from char-N and is released with the combustion of char.NOx emission is 90.4 mg/m3 and 96.7mg/m3 (@ 6% O2) for Shenmu bitumite and coal gasification fly ash,respectively.