The co-combustion of torrefied municipal solid waste and coal in bubbling fluidised bed combustor under atmospheric and elevated pressure

Abstract

Municipal solid waste (MSW) is considered a valuable energy source that can be applied as a secondary (co-combustion) or even primary fuel in a power plant. Torrefaction of MSW led to significant benefits related to reduced chlorine and mercury content. The aim of this paper is to investigate the co-combustion of torrefied municipal solid waste and coal in a bubbling fluidised bed combustor under atmospheric and elevated pressure. Torrefaction of pelletised MSW was carried out using a rotary kiln reactor under inert atmosphere (N2) and synthetic flue gas (mixture of CO2 – ∼11 v.%, O2 – ∼4,35 v.%, and N2– as balance). The pelletisation was carried out using a pelletiser with the rotating rollers in contact with the matrix. The pressurised co-combustion of hard coal and MSW (5% and 15% by weight) was carried out under a total pressure of 3 bar and a temperature bed of 850 °C. The main component of the experimental setup was a fluidised bed combustor (bubbling regime). The increase in pressure in the combustion chamber caused significant benefits in terms of the emission of gaseous pollutants. Lower emissions of NO (by ∼56%) and SO2 (by ∼35%) were observed for pressurised combustion.