Tar yield in fluidized bed coal gasifier.

Tar yielded in a fluidized bed coal gasifier was analyzed. Taiheiyo coal of size 0.64 and 1.00mm was fed continuously to a 0.083 m diameter fluidized bed and gasified using mixtures of steam and air.Tar Quantity in produced gas decreased rapidly as the bed temperature became higher. Molecular weight of tar became smaller and ratio of methane and ethane in produced gas increased at higher temperature. Tar yield decreased as the tempera-ture of freeboard region just above the bed became higher. But the gas residence time in freeboard region had no effects upon tar yield.