GAS-PARTICLE FLOWS AND COAL COMBUSTION IN A BURNER COMBUSTOR WITH HIGH-VELOCITY JETS

Coflowing high-velocity jets have been used in a burner/combustor to stabilize a coal flame, instead of swirlers or baffles, for burning low-grade coals. The LDV measurements and three-dimensional numerical simulation of gas-particle flows in these combustors show a large and strong reverse-flow zone induced by the high-velocity jets, high particle concentrations in the reverse-flow zone, high velocity slip between two phases and also high mixing rates due to high turbulence, favorable to ignition and coal-flame stabilization. The three-dimensional numerical simulation of coal combustion indicates the important role of the central reverse-flow zone in volatile ignition and combustion. Numerical modeling has been used for seeking optimal geometrical sizes and flow parameters for practical combustors by creating a strong gas recirculation zone to stabilize the combustion of anthracite in tangentially fired furnaces without supporting oil and without slagging. In fact, the total amount of oil saved is about 10000 tons/yr for a 410 T/h boiler.