Experimental study on PM10 formation characteristics of co-combustion with pulverized coal and sludge

Abstract

At present, the output of municipal sludge in China is increasing year by year, and co-combustion of sludge and pulverized coal for power generation is a means to treat sludge in large quantities. However, the co-combustion of sludge and pulverized coal will generate a lot of particulate matter (PM). In this paper, the formation characteristics of particulate matter (PM10) produced by the co-combustion of sludge and pulverized coal were studied. The effect of the furnace temperature and the sludge mixing ratio on the mass-based particle size distribution and elemental composition of PM10 in sludge, coal combustion and co-combustion was discussed. The experiment results show that the mass-based particle size distribution of PM10 produced by pulverized coal and sludge combustion are both bimodal, while the elemental composition and particle size distribution of PM10 are different. Whether burning alone or co-firing, increasing the furnace temperature will increase the mass yield of PM10. Increasing the temperature promotes particle fragmentation more than the melting aggregation of particulate minerals, increasing PM0.4–10 yield. The mass yield of PM10 produced by coal combustion is higher than that of sludge. In the sludge addition ratio range ≤ 30%, increasing the sludge addition ratio will reduce the mass yield of PM10. The synergistic effect exists between sludge and pulverized coal co-combustion. Compared to the weighted calculation results, the content of main elements Si, Ca, Fe and S in PM0.4 decreases, while in PM0.4–10 the content of Si decreases and the content of Ca, Fe, Al, and P increases. At a low sludge addition ratio of 10%, the elemental composition of PM10 with the particle size distribution trend is consistent with that of pulverized coal, and sludge co-firing takes negligible effect on PM10 formation.