Experimental study on preheating and combustion characteristics of pulverized anthracite coal

Anthracite, with low volatile content, has difficulties in ignition, stabilization, and burn out, especially under conditions of low boiler load. A new technique for preheating pulverized anthracite by a circulating fluidized bed was adopted. Experiments on preheated anthracite combustion were carried out in a down-fired combustor. Process of anthracite preheating, combustion characteristics, and NOX emissions were studied. The results show that preheated anthracite has a smaller mean size with a larger specific surface area. There is a uniform temperature profile along the axis of the down-fired combustor, and the combustion efficiency is 96.5%. The NOX emission in the exhaust is 256 mg/N m3 (@ 6% O2) and the conversion ratio of fuel-N to NOX is 24.3%.