Numerical Simulation of Oxy-Fuel Combustion with Different O₂/CO₂ Fractions in a Large Cement Precalciner

Abstract

The cement industry is one of the world’s largest sources of the anthropogenic CO2 emissions. Thus, it is very urgent to develop new methods to reduce CO2 emissions produced by the cement production. In this paper, the oxy-fuel combustion in large-scale cement precalciners was investigated by the large-scale parallel computational fluid dynamics (CFD) numerical simulations. The effects of pulverized coal combustion on the distribution of the velocity field, temperature field, material components, and NOx concentration were analyzed under O2/CO2 molar fractions of 21/79, 25/75, 29/71, 33/67, and 37/63. The results showed that the peak of the temperature is gradually increased, which was beneficial for the decomposition of CaCO3. The high-purity CO2 at the outlet can be captured and recycled directly to reduce CO2 emission. Moreover, the relatively pure CO2 atmosphere in the furnace significantly reduced the thermal NOx. The concentration of NO (125–189 mg/m3) during the O2/CO2 combustion was much lower than that of conventional air combustion (>800 mg/m3).