TURBULENT NATURAL-CONVECTION FLOW DUE TO COMBINED BUOYANCY FORCES DURING UNDERGROUND GASIFICATION OF THIN COAL LAYERS

During the process of gasifying thin coal layers underground. an open channel structure might exist. In this channel, chemical reactions wil l have an effect on both the temperature and the concentration distrib ution. The resulting temperature and concentration gradients give rise to opposing buoyant forces. The resulting flow field determines the h eat and mass transfer and the product gas composition. Results for the two-dimensional numerical prediction of the flow field and the produc t gas composition are given for a number of situations. The amount of air injected as well as the radiation extinction coefficient of the ga s are varied. The predictions show that the process will produce usefu l gases for certain air inlets. The solution of the equations is time dependent for some situations: its periodicity is presented and discus sed in this paper.