Numerical simulation on pulverized coal combustion process in a tangential firing furnace

The computational fluid dynamics (CFD) code, PHOENICS 3.5, is employed to evaluate horizontal pulverized coal bias combustion process in a 200 MW tangential firing boiler. Multi-fluid two-phase model and coal comprehensive combustion model are integrated in the code. Gas temperature, particle distribution, gas species concentration and radiation heat flux at different sections of furnace are obtained from the numerical simulation at different secondary air (SA) vertical distribution. The calculation results show that a high particle concentration and high gas temperature zone exist, together with the separation of particle and gas downstream primary air (PA) nozzles, which ensure suitable ignition time, high temperature level of PA mixture and resistance to slag on the water-cooled walls. The calculated burnout of coal particles, O2 concentration at furnace exit and gas averaged temperature in furnace are compared with in situ measurement data, resulting in good agreement. The simulation results of staged SA distribution case show that gas temperature of down part of furnace increase and the final burnout of char is decreased for the postponing mixing between fuel and oxygen. Simulation results are also compared with in situ measurement data, resulting in good agreement with each other. Thus the comprehensive coal combustion model has reasonably simulated PF combustion process in large boiler furnace, which is benefit for optimizing unit operation conditions and reducing pollutants emission.