THERMALLY STABILIZED COMBUSTION AS A MEANS OF STUDYING THE DEVOLATILIZATION OF COAL

Thermally stabilized combustion of premixed ethane and air in a ceramic tube results in a virtual step function in temperature, composition, and velocity at the flame front. If the mixture is fuel-rich, the burned gas consists almost wholly of CO, CO2, H2O, and N2. For a tube greater than 30 mm in diameter, the stable range of flow is in the turbulent regime both upstream and downstream from the flame front. An experimental technique exploiting this environment for study of the devolatilization of coal is described, and illustrative results are presented. As compared with other techniques using heated grids or entrainment, the conditions outside a particle are more uniform and the rate of heating is greater, but the velocity and temperature of the particle must be determined from momentum and energy balances rather than by direct measurement.