Abstract: Sulfur dioxide in the stack gas from an industrial process is converted to elemental sulfur in a Claus reactor at low temperature to produce sulfur fume. The sulfur is condensed by direct heat transfer with a continuously flowing countercurrent recirculating catalyst and a substantially sulfur dioxide-free gas is discharged. Catalyst and condensed sulfur are fed into the top of a sulfur recovery column and heated in the top of the column by direct heat transfer with a countercurrent stream of recycle gas. The sulfur and catalyst descend into a vaporization zone of the column where sulfur is vaporized. The vaporized sulfur is carried by the recycle gas back towards the top of the column and condensed to a fume by incoming sulfur bearing catalyst. The sulfur fume is carried from the top of the column in cold recycle gas. Hot catalyst from the vaporization section of the column is cooled by recycle gas entering the bottom of the column. Sulfur fume is recovered conventionally.

Abstract: Hot fuel gas from coal gasification passes countercurrent to cycling heat transfer solids in a tower to lose heat to the solids. The thus cooled fuel gas has sulfur removed and then passes countercurrent in the tower to the now hot solids to cool the solids and reheat the fuel gas. The heated and purified fuel gas is exited from the tower for consumption as in a power plant. The solids are free to flow by gravity but are constricted in the vicinity of the midsection of the tower. This constriction in conjunction with control of gas pressure by monitoring of hot inlet gas pressure and hot but purified fuel gas outlet pressure prevents one or the other of the gases from bypassing the path desired for it.