Modelling of an opposite wall fired furnace for different operating conditions
Modelling of an opposite wall fired pulverised coal furnace using commercial CFD code Fluent is presented in this paper. The mathematical model is based on a Eulerian description for the continuum phase and a stochastic Lagrangian description for the coal particles. A three-dimensional combustor model is used to determine the temperature and heat flux profiles and other thermal characteristics for a typical 500 MW boiler with medium volatile coal. The predicted temperature profiles for a 100% boiler load and different reduced boiler loads are considered. Particle trajectories are analysed to identify the causes of operational problems such as fouling on burners due to recirculation of coal particles and temperatures achieved in various parts of the boiler during the combustion process. The effects of particle size and excess air on the furnace temperature pattern are also studied. The results are compared with measurements obtained in the simulated pilot-scale combustion rig as well as power station boiler, which lay a foundation for the boiler operating expert system. The results obtained from the study are also of practical value to optimize the performance of boilers.