Abstract: Green coal is charred in pre- and post- treatment carbonizers, then crushed, mixed with pitch, briquetted, tempered in a tempering oven, recirculated with succeeding green coal to char in a reducing atmosphere through only the latter part of the pre-treatment carbonizer and through the post-treatment carbonizer, cooled, and separated from the as yet unbriquetted char. The pre-treatment carbonization is characterized by having air updrafted through all the airbox zones under the travelling grate.

Abstract: Carbonaceous raw material, such as lignite coal, having first been passed successively through a moving grate stoker furnace, a shaft furnace and a quench chamber is screened so as to remove from the end product substantially all +12 mesh and larger particles which are then crushed to -12 mesh screen size and recirculated into the stream of raw material enroute through the moving grate stoker.

Abstract: Green petroleum coke is partly devolatilized by transporting horizontally in static bed form through a furnace over a series of air box zones including a minority of zones adjacent the input end of the furnace and a majority remote from the input end and further devolatilized by soaking in a shaft furnace until at least most of the residual volatiles are driven off. From the shaft furnace the devolatilized coke is water quenched and steam produced in the quencher is mixed with downdrafted gases from said furnace to cool the same and prevent premature combustion.

Abstract: Coal devolatized and partially gasified in a travelling grate reactor is dropped into a shaft furnace to form a downwardly moving stack which moves then downwardly to and through a fixed bed gasifier, wherein it is burned to ash. A gas stream from the travelling grate reactor is down-drafted through the shaft furnace and a gas stream is up-drafted through the fixed bed gasifier, and the two streams combined are drawn through a heat exchanger and fed to a gas burner, combustion air for the gas burner being heated in the heat exchanger.