Application of post-combustion ultra-low NO_x emissions technology on coal slime solid waste circulating fluidized bed...

In order to achieve thermal treatment of coal slime and depth control of NO_x, a 75 t/h circulating fluidized bed (CFB) boiler arranging post-combustion air is constructed. In the experiment, the combustion atmosphere and the ratio of primary air and secondary air are adjusted to decrease the NO_x emissions below 50 mg/m³ (dry basis at 6% O₂). Compared with conventional CFB combustion, the post-combustion technology decreases the NO_x emissions from 92.9 to 65.4 mg/m³ by adjusting the combustion atmosphere. Then, the primary air volume is adjusted to decrease the NO_x emissions further. On the one hand, decreasing primary air volume contributes to inhibiting the NO_x generation in the dense phase. On the other hand, it is proved that the combination of the cyclone and a post-combustion chamber plays a crucial role in the de-NO_x process of post-combustion technology. More char particles are brought to the cyclone as the primary air volume decreases. The NO_x reduction in the cyclone and the post-combustion chamber is promoted. Finally, the NO_x emissions are decreased to 42.6 mg/m³ when the ratio of primary air and secondary air is 50.0%. In addition, the SO₂ emissions and the combustion efficiency during the ultra-low NO_x condition are 23.2 mg/m³ and 98.3%, respectively.