Experimental Study of Oxy-fuel Combustion and Emission Characteristics Using a 10 kWth Pressurized Fluidized Bed Combustor

Abstract

Pressurized oxy-fuel combustion (POFC) is a promising carbon capture and storage technology because of its ability for efficient CO₂ capture and storage at a relatively low cost. However, the experimental studies conducted on this technology considering pressurized conditions are limited compared with those conducted considering atmospheric conditions. Thus, further investigation on the performance and environmental emissions of oxy-fuel combustion is necessary. In this study, oxy-fuel combustion experiments were conducted using a 10 kW_th fluidized bed combustion (FBC) test rig at pressures ranging from 3 to 8 bar (g). The effects of combustion pressure, oxygen concentration, and cofiring with different fuels on combustion temperature, unburned carbon, combustion efficiency, as well as SO_x and NO_x emissions were examined. The experimental results showed that the CO₂ concentration in the flue gas exceeds 90% in all POFC scenarios, thus facilitating the carbon capture process. In addition, by increasing the combustion pressure, the unburned carbon and CO concentrations in the fly ash are reduced, thereby improving combustion efficiency. Furthermore, the variations in NO, NO₂, N₂O, and SO₂ emissions were measured to assess their environmental impact. Moreover, cofiring tests using biomass under pressurized oxy-fuel conditions (5 bar (g), 30% O₂:70% CO₂) showed that these conditions are more environmentally sustainable and efficient than other combustion methods for producing energy in a fluidized bed by burning a mixture of coal and biomass.