An experimental study of propane combustion in a fluidized-bed gasifier

This paper reports an experimental study of the combustion of volatiles fro m coal, simulated by propane, and its interaction with char gasification re actions in a fluidized-bed coal gasifier (FBG). Experiments were performed under conditions of propane pyrolysis tin a bed fluidized by nitrogen and s team), propane reacting with oxygen and steam (in a bed fluidized by air an d steam), char gasification only (in a bed fluidized by air and steam witho ut propane) and in char gasification (in a bed fluidized by air and steam w ith propane). Axial concentration profiles of various species were obtained at 750, 850 and 950 degreesC. It was observed that the combustion of propa ne in an FBG, but without char, behaves as reported in the literature for f luidized-bed combustion (FBC). However, upon introducing char into the bed to simulate the reducing atmosphere in an FBG, oxygen was rapidly consumed within a short distance of the distributor; by significant partial oxidatio n of both propane and its decomposition products to carbon monoxide. The ch ar was found to aid the pyrolysis of propane, limiting the amount of hydroc arbons surviving into the freeboard. The experimental results reported here are believed to be the first observations on the combustion of volatiles u nder conditions in an FBG. (C) 2001 by The Combustion Institute.