循环流化床锅炉燃烧福建无烟煤炉内脱硫对锅炉热效率及烟气中NO_X排放的影响

用石灰石作脱硫剂在一台35 t/h循环流化床锅炉上进行工业性脱硫试验,结果表明:①添加石灰石脱硫对氮氧化物排放的影响很微弱。在小钙硫比工况下,添加石灰石脱硫会使烟气中NOx排放量上升,但升幅平缓。在大钙硫比情况下(Ca/S>3.0),加入石灰石后使得烟气中的NOx排放量有所下降;②在钙硫比较小的工况下,添加石灰石脱硫会降低烟气中CO的排放浓度,但降幅受钙硫比和石灰石颗粒度分布的影响不明显。在上述大钙硫比工况下,添加石灰石脱硫的前期反而会使烟气中CO的排放浓度升高;③锅炉的飞灰含碳量在添加石灰石脱硫后略有增加,而且添加细颗粒石灰石比添加粗颗粒石灰石时增加更多。另外,添加细颗粒石灰石脱硫还会使炉渣的含碳量同时增加;④由于脱硫效率不高,添加石灰石后使得炉膛内热容量减少并使锅炉的热效率有微小的下降。

Influence of Combustion Desulphurization on NOx Emission and Thermal Efficiency of Circulation Fluidized Bed Boiler for Fujian Anthracite

Using limestone as desulfurisation agent, the industrial experiment was performed on a 35t/h CFB boiler whose fuel is Fujian anthracite. It was showed from the experiment that: (1) There is a very slightly effect on the NOx emission when limestone is added to coal during combustion. In small Ca/S, the NOX Emission would go a slight up when the limestone is added. But in big Ca/S, however, Putting limestone into furnace would lead to a little lower NOx Emission; (2) The CO emission would be decreased when the Ca/S is small, but the range of decrease shows no obviously effected by the variation of Ca/S and LPAD (limestone抯 particle- average- diameter). Contrarily, in big Ca/S, the CO emission would be increased in the earlier stage When limestone is put into furnace; (3) the carbon content in fly ash would be increased to a small extent when adding limestone to combustion, and the big LPAD has showed a evident effect on increasing the carbon content of fly ash than the small LAPD. Besides, adding small LPAD to combustion would also increase the carbon content in slag; (4) Due to relatively lower desulfurisation efficiency, adding limestone to combustion would reduce the furnace抯 thermal capacity and cause a slightly descending in boiler抯 thermal efficiency.