Study on Coal Plasma Ignition and Combustion in a Primary Combustor

To evaluate performance a coal plasma ignition primary combustor, an axis-symmetry numerical simulation was carried out to study flow and combustion field. The gaseous phase is described within the framework of the Eulerian representation and the solid phase, the Lagrangian representation. It is found that less volatile matter requires higher temperature for the volatile emission, therefore high power plasma torch required. Volatile content, coal/air weigh ratio, plasma power, and operating velocity are key parameters for plasma ignition coal. For 20 m/s velocity, coal/air weight ratio 0.3 kg/kg, 100 KW air plasma torch, 20% volatile matter, the primary combustor can provide stable and effective combustion. As air and coal mixture velocity increasing or decreasing plasma power, the wall temperature of primary combustor decreases. However, the flame goes downstream and its stabilization becomes weak. Reduced mixture velocity and strong swirl velocity will help flame spread in radial direction, however, this leads to increasing pressure drop and high wall temperature of primary combustor. It is also concluded that the effect of detailed chemistry must be introduced into numerical model to study plasma coal ignition characteristics.