Validation and application of CPFD model in simulating gas-solid flow and combustion of a supercritical CFB boiler with improved inlet boundary conditions

Abstract

Uniformity of coal and air has always been an important problem in the operation of large-scale CFB boilers. The selection of inlet boundary conditions is close related to the simulation accuracy, but seldom considered in the previous literatures. In this paper, a new method to estimate the distributions of coal supply was proposed, which was used as the boundary condition together with the experimental data to carry out combustion simulations on a 600 MW supercritical CFB boiler by using the Computational Particle Fluid Dynamics (CPFD) method. The simulation results were validated against the critical measured data including solid concentration, gas/solid circulation flow rate, gas temperature, oxygen concentration, etc., indicating that the model using the proposed boundary conditions could predict the combustion characteristics more accurately than that with common uniform boundary conditions. Based on the simulation results, the influence of air/coal distribution on the combustion in the furnace under different loads was investigated, a series of non-uniform problems were also found and analyzed. The research method and results of this paper can provide meaningful reference for the combustion simulation and operation optimization of large-scale CFB boilers.