Co-firing of Thai lignite and municipal solid waste (MSW) in a fluidised bed: Effect of MSW moisture content

Co-firing investigation of a high-moisture-content municipal solid waste (MSW) with Thai lignite have been performed in a laboratory-scale fluidised bed to study the effects of MSW moisture content on the combustion and emission characteristics of major gaseous pollutants. In this study the comparison of 35%- and 60%-moisture MSWs were tested. The results show that the bed temperature in the case of 35%-moisture content is higher than for in case of 60%-moisture content due to the difference of physical properties of the fuel. The combustion efficiency for the case of 35%-moisture MSW is higher than that for 60%-moisture MSW due to higher bed temperature at lower waste moisture content. The synergistic effect of the co-firing of lignite with MSW reduces the emission of CO leading to increase in combustion efficiency. CO concentration for the case of 35%-moisture content is generally lower, and is much less sensitive to the level of excess air. Both the concentration values of SO2 and the fuel-S converted are lower for lower moisture content waste, particularly at high mass fraction of waste. The fuel mixture with low-moisture in waste gives higher fuel-N conversion to NO whereas the fuel-N conversion to N2O is higher for higher moisture content waste, particularly at high excess air.

Research highlights
► The moisture content in waste has affected to both combustion and emission characteristics.
► The higher moisture content in waste concerned, the higher bed temperature and the higher combustion efficiency achieved.
► Gaseous emissions, such as CO and SO2, are lower for lower moisture content waste.
► Low moisture content waste gives higher fuel-N conversion to NO whereas this effect is reversed when moisture content increases.