REDUCING PM10 EMISSIONS THROUGH CO-COMBUSTION OF COAL WITH SEWAGE SLUDGE USING LAB-SCALE DROP TUBE FURNACE

摘要

In this study, the physical and chemical properties of PM10 (Particulate matter less than 10μm in diameter) were determined to investigate the effect of transformation behaviors of minerals on the formation of PM and further on the reduction of the emission of PM10 during the co-combustion of coal with sewage sludge. Combustion experiments were carried out at 1200°C using a lab scale drop tube furnace (DTF). PM samples were collected by the combination of a 13-stage low-pressure impactor (LPI) with a cyclone. PM10+ refers to the coarse particles greater than 10 μm in diameter. PM1-10 includes the particles ranging from 1μm to 10μm in diameter. Laser particle analyzer, XRF, SEM-EDX, TEM-EDX and CCSEM have been used to analyze the particle size, elemental content, morphology, and chemical form of PM. According to these results, the effect of interactions of minerals on the reduction of PM10 has been clarified. Transformations of fine Al-Si (<10μm) in coal into PM10+ are responsible for the reduction of PM10 during co-combustion process. These transformed fine Al-Si particles are captured by larger Ca-Fe-Al-Si/Ca-Fe-P-Al-Si, which are mainly generated from sludge combustion, to form PM10+ of Ca-Fe-Al-Si/Ca-Fe-P-Al-Si. In addition, the vaporized elements, such as Na, K, Si, dominant in PM1 emitted from sludge, are captured by such melted Ca-Fe-bearing particles( >1μm ) as well, and therefore the emission of PM1 are reduced.