Operating characteristics and ultra-low NOx emission of 75 t/h coal slime circulating fluidized bed boiler with post-combustion technology

Coal slime was a kind of industrial solid waste and it was hard to utilize. To realize the resource utilization of coal slime, a 75 t/h circulating fluidized bed (CFB) boiler with post-combustion technology was built. The operating and emission characteristics during mono-combustion of coal slime were investigated in detail. The fuel characteristics of coal slime and feeding from the top of the furnace resulted in the temperatures at the top and the bottom were higher than the middle of the furnace. When the furnace differential pressure increased, the furnace temperature and the main steam temperature both decreased, but the main steam flow increased. The main steam temperature could significantly increase after the soot blowing. The post-combustion air (PCA) was an effective means to adjust the main steam parameters. The main steam temperature increased as PCA increasing. The average SO2 emissions were only 8.4 mg?m? 3 benefited from the excellent desulfurization effect of the combination of dry and semi-dry desulfurization. Nevertheless, due to the fluctuations of coal slime characteristics, the standard deviation of SO2 emission reached 8.6 mg?m? 3. Under the conditions without desulphurization and SNCR, the NOx emissions of coal slime could be decreased to 38 mg?m? 3 and reach the ultra-low NOx emission when post-combustion technology was used.

Automated summary

The study focused on investigating the operating and emission characteristics during mono-combustion of coal slime in a 75 t/h circulating fluidized bed boiler. The temperature distribution in the furnace was influenced by the fuel characteristics of coal slime and feeding location.