Numerical Investigation of Gas-Solid Two-Phase Flow in a Tiny-Oil Ignition Cyclone Burner for a 300-MW Down-Fired Pulverized Coal—Fired Boiler

Abstract

In this work, a tiny-oil ignition cyclone burner is proposed for a 300-MW down-fired pulverized coal-fired boiler to reduce oil consumption during the start up and low load operation of the boiler. Numerical simulations are carried out to investigate the gas-solid two-phase flow in the burner. The Reynolds stress model (RSM) is employed to model the swirling gas flow in a cyclone burner, and the stochastic Lagrangian method is used to calculate the movement of the particle. A Foster Wheeler (FW) cyclone burner is also simulated to compare with the tiny-oil ignition cyclone burner. The results show that the gas flow characteristics in the FW cyclone burner agree well with previous studies, indicating that the calculation models employed for the swirling flow is reasonable and acceptable. The tiny-oil ignition cyclone burner has the same operation characteristics with the FW cyclone burner in the industrial applications, as the differences of the vent air ratio and the separation efficiency between the two burners are less than 10%. But the tiny-oil ignition cyclone burner would produce a more favorable effect on the coal particle ignition, coal combustion, and the NOx reduction than FW cyclone burner.