Simulation and experiment of plasma ignition of low-grade coal

Abstract

A plasma-coal burner is studied utilizing a model of plasma thermochemical preparation of coal for combustion, implemented in the PlasmaKinTherm program. For boiler start-up and coal combustion stabilization, plasma-coal burners do not require fuel oil or gas. The PlasmaKinTherm program combines thermodynamics and kinetics to describe the thermochemical preparation of fuel in the plasma-coal burner volume. The purpose of the simulation was to determine the conditions for plasma ignition of low-grade coal. A numerical study was carried out of the influence of the plasmatron power on the ignition of the air mixture (coal + air). High-ash Ekibastuz coal was used in the calculations. The distributions of temperature and velocity of gas and coal particles and concentrations of products of plasma thermochemical preparation of coal for combustion along the length of the burner were calculated. As a result of the analysis of the processes of plasma ignition of coal, their main patterns were revealed, including the shift of the maximum temperatures and velocities of the products of thermochemical preparation of coal for combustion upstream (towards the plasma torch), as well as the fact that the maximum values of temperatures and velocities of the products do not depend on power plasmatron. At the plasmatron power determined by kinetic modeling, experiments were conducted to test and validate the ignition and combustion conditions for a highly reactive two-component fuel torch. The assumptions made during the development of the mathematical model were confirmed by comparing the calculations with experimental data.