Numerical simulation of furnace process in a 600 MW ultra supercritical boiler utilizing selective noncatalytic reduction technology

Numerical simulation of flow, heat transfer, and combustion process in a 600 MW ultra supercritical pulverized coal boiler is performed using Computational Fluid Dynamics (CFD) code Fluent. The average temperature and concentration of gas composition at the furnace outlet are in a good consistent with the designed value, which indicates that mathematical models and calculation method are valid. NO formation is low because of Mitsubishi Advanced combustion technology and PM burner, and partial of NO produced is deoxidizated. NO emission at furnace outlet is 216 mg/kg, which meets the initial NO concentration requirement of Selective Noncatalytic Reduction Technology (SNCR) process. According to the 'temperature window' requirement of SNCR process, the proper region for SNCR process is around 67 meters high horizontal cross section in the furnace. The NO concentration in the region decreases gradually from near the water wall to the center of the furnace, which is benefit for injecting reducing agent from water wall. Unburned CO is very little and exists only in limited zones near the two lateral water walls, which has small influence on NO removal. According to temperature profile and gas species as well as the arrangement of superheaters, an approach for injecting the reducing agent of SNCR process is suggested.