Oxy-coal combustion in a 30 kWth pressurized fluidized bed: Effect of combustion pressure on combustion performance, pollutant emissions and desulfurization

Oxy-coal combustion with pressuriz ed fluidiz ed beds has recently emerged as a promising carbon capture and storage (CCS) technology for coal-fired power plants. Although a large number of energy efficiency analyses have shown that an increase in combustion pressure can further increase the net plant efficiency, there are few experimental studies of pressurized oxy-coal combustion conducted on fluidized bed combustors/boilers with continuous coal feeding. In this study, oxy-coal combustion experiments with lignite and anthracite were conducted with a 30 kW(th) pressuriz ed fluidiz ed bed combustor within the pressure range of 0.1 MPa to 0.4 MPa. The investigation focused on the elucidation of the impacts of combustion pressure on the combustion performance, pollutant emissions and desulfurization of oxy-coal combustion in fluidized beds. The results showed that an increase in pressure increased the combustion efficiency and combustion rate of coal particles, and the promoting effect of pressure increase was more significant for the high rank coal with smaller particle size and the high O-2 concentration atmosphere. For both coals, NOx emissions decreased with pressure but N2O emissions increased with pressure and accounted for a considerable part of the nitrogen oxide pollutants under high pressure oxy-coal combustion conditions. The pressure had insignificant impact on the SO2 emissions of oxy-coal combustion but an increase in pressure enhanced the direct desulfurization of limestone. (c) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

Experimental studies on pressurized oxy-coal combustion in fluidized bed combustors/boilers with continuous coal feeding are limited, but have shown that an increase in pressure can significantly improve combustion efficiency and combustion rate of coal particles, with a more pronounced effect on high rank coal and high O2 concentration. Under high pressure oxy-coal combustion conditions, NOx emissions decrease while N2O emissions increase, with SO2 emissions minimally impacted by pressure but direct desulfurization of limestone enhanced with pressure.