Numerical simulation of oxy-fuel combustion characteristics in a 200 MWe coal-fired boiler

Oxy-fuel combustion in coal-fired plants has become one of the most promising technologies for carbon capture and storage (CCS). Because of the obvious difference between the oxy-fuel combustion medium (O-2/CO2) and air in the atmosphere (O-2/N-2), the characteristics of combustion, heat transfer, etc., under oxy-fuel combustion have changed greatly from those under air combustion. In this paper, computational fluid dynamics (CFD) simulation was used to investigate pulverized coal combustion in a 200 MWe tangentially fired oxy-fuel combustion boiler. Improved models for the gas radiative properties and chemical reaction mechanisms were incorporated into the CFD code. Both conventional air-fired and oxy-fuel combustion were operated. Different flue gas recycling patterns (dry recycling and wet recycling) were also investigated. The temperature distribution in the furnace, the temperature field, and the CO concentration field in each scheme were analyzed, this being relevant to the design of oxy-fuel combustion boilers. It was found that combustion could form a good tangential circle and stable temperature field in the furnace either under air-fired or oxy-fule combustion conditions. The temperature under oxy-fuel combustion was lower than with air combustion. The burnout rate under the air condition was lower than that with the oxy-fuel combustion condition. With oxy-fuel combustion, it is necessary to pay special attention to the slagging tendency of the primary combustion zone in the furnace. (c) 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.