Effects of coburning of municipal sludge and bituminous coal washery tailing on particulate matter emission characteristics under fluidized bed conditions

The combustion of sludge/coal washery tailing as high ash and low calorific value fuel is an effective means of reducing the above two substances on a large scale，and with the growing problem of haze，particular attention needs to be paid to their particulate emissions in the process.Based on a fluidized bed test bench，using a selfdesigned particulate collection device，BT9300HT laser particle size analyzer and Xray fluorescence spectrometer(XRF)，this study obtained the particle size distribution and the chemical composition of the generated particles respectively revealed the generation characteristics of the particles of sludge/coal washery tailing combustion alone，and sludge/coal washery tailing mixed combustion.The results show that when sludge and coal washery tailingLMwere burned separately in a fluidized bed，the particle size distribution of particulate matter showed a significant difference at around 800 ℃，and the volume fraction emission of PM 2.5/PM 10 was consistent with the peak particle size distribution.It was caused by the interaction of the fixed adsorption of tar to particles，the melting and agglomeration of alkali metals and the gasification，collision，and fragmentation of minerals during the combustion process.The main components of PM 2.5 produced by combustion are K，Mg，S，Cl and P.PM 10 are mainly composed of Si，Al，Fe，Ca.The K，Mg，S，Cl，P in PM 2.5 of sludge are higher than that of coal slime，and the Si，Al，Fe，and Ca in PM 10 of coal washery tailing are higher than that of sludge.The combustion temperature and sludge/coal washery tailing blending ratio can affect the emission characteristics of particulate matter，the increase in combustion temperature leads to a tendency for the peak corresponding to coarse modal particulate matter to move in the direction of the small particle size and upwards.The experimental values of particulate matter under different blending ratio conditions differ significantly from the linear summation values，and blending significantly reduces the postcombustion PM 2.5 emissions，which was attributed to the interactions between the easily gasifiable elements(K，Cl，P，S，etc.) from the sludge and minerals and coke from the coal washery tailing during combustion.