Coal Combustion Efficiency in Circulation Fluidized Bed

It is well known that the unburned carbon content in fly ash in a coal-fired circulating fluidized bed boiler has been a major problem. It contributes to a loss of combustion and boiler efficiency. The combustion of six kinds of coal was investigated in a bench scale circulating fluidized bed rig, which results were compared with that in circulating fluidized bed boiler burnt the same coal, and also correlated with the TAG dates. The results shows that the unburned carbon content in fly ash is affected not only by operation parameters, such as bed temperaure, excess air ratio, combustion air supply, bed inventory and its quality, but also by the coal characteristics, which is believed the key fact. With the TGA data, it is possible to predict the e unburned carbon content in fly ash when the coal is burnt in a circulating fluidized bed boiler.