Calcination and desulfurization characteristics of calcium carbonate in pressurized oxy-combustion

Pressurized oxy-combustion is one of the most promising and efficient CO₂ capture technologies for coal-fired power plants, which could reduce energy consumption for carbon capture. However, due to the effects of pressurization and flue gas recirculation, the partial pressure of sulfur oxides (SO_x) in pressurized oxy-combustion is significantly higher than that of air-combustion, which leads to the corrosion risks and environment hazards. It is essential to investigate the SO_x control in pressurized oxy-combustion. In this paper, the in-furnace calcination and desulfurization characteristics of calcium carbonate in pressurized oxy-combustion were carried out in a pressurized drop tube furnace. The findings show that the sulfation reaction in pressurized oxy-combustion is direct sulfation and the sulfation rate increases with the increase of temperature and pressure. The desulfurization efficiency in pressurized oxy-combustion is lower than that in atmospheric air atmosphere below 950 °C, but it reverses above 950 °C, indicating that the minimum desulfurization temperature in the furnace of the pressurized oxy-combustion is higher than that of atmospheric air atmosphere. Therefore, limestone can still be used as a sorbent in the pressurized oxy-combustion furnace. This study could contribute to the design of dry desulfurization systems in pressurized oxy-combustion combustors that use fossil fuel energies with high efficiency and low SO_x emissions.