Numerical Study of Selective Non-Catalytic Reduction Process in Large Utility Boiler

To provide a theoretical guidance for the application of selective non-catalytic reduction (SNCR) in a large capacity utility boiler, numerical study of SNCR process in a 600 MW utility boiler was performed based on computational fluid dynamics (CFD) code Fluent. Good agreement of the calculation results with the industrial test data confirms the reliability of the calculation model. It is found that the NO removal efficiency is low and NH3-slip is high, because the injected reducing agent could not mix with the flue gas adequately, and the furnace temperature is not uniform in utility boiler with large furnace size. Aiming at this problem, the commissioning scheme for reducing agent injection system was optimized, and CO was added together with the reducing agent. As a result, NO removal efficiency increases from 19% to 27%, and NH3-slip decreases from 59 ppm to 13 ppm.