Numerical and experimental investigation on co-combustion characteristics of hydrothermally treated municipal solid waste with coal in a fluidized bed

This research describes numerical and experimental studies on the co-combustion characteristics of hydrothermally treated municipal solid waste (HT MSW) with coal by utilizing a bubbling fluidized bed (BFB) reactor. The developed model is supported by some experimental test on co-combustion of coal with HT MSW to simulate the combustion process in a BFB and to evaluate the possibility of co-combustion application in a BFB reactor with different MSW blending ratios. HT MSW mixing ratios of 10, 20, 30, and 50% are chosen and examined at 700, 800, and 900 °C to determine at which temperature coal could be substituted with the HT MSW regarding emissions, such as CO, SO2 and HCl. Emissions of NO, N2O, NH3 and HCN from the mixtures are measured, simulated, and contrasted with the results of only combustion of coal. Hydrodynamics and heat and mass transfer, along with reactions during combustion, e.g., coal/waste devolatilization, volatile combustion and char combustion, are taken into account. The results obtained in this part of the study ensure the possibility of accepting the mixing ratio of the hydrothermally treated MSW, co-combusted with coal up to 30% (wt.%) without major modification of the coal-fired BFB reactor. The simulation results are compared with experimental data, which show that the gas species versus time at different heights from the fluidized bed is reasonably simulated. This indicates that the numerical model presented is valid and provides a promising way to simulate the combustion of solid waste in a BFB, which is the predominant technology for co-combustion of waste. The advantage of the theoretical study lies in its ability to reveal features of the detailed structure of the combustion process inside a solid bed.