Reheat method for use in sulfur recovery process

Claim 1

In a process for the recovery of free sulfur from a gaseous mixture containing H2S by means of the split flow process wherein only a minor amount of said mixture is diverted into a combustion zone and the H2S in the diverted portion is converted to sulfur dioxide, the H2S content of said gaseous mixture not exceeding about 20 mol percent and wherein a portion of the sulfur dioxide required in said process is supplied by burning free sulfur in said combustion zone, thereafter cooling the resulting combustion products by discharging them into an indirect heat exchange zone, mixing the effluent from the latter with the portion of said gaseous mixture bypassing said combustion zone to give a reaction mixture of H2S and SO2 in a molar ratio of approximately 2:1, respectIvely, and thereafter reacting said H2S and SO2 in the presence of a catalyst for the reaction in a known manner to produce free sulfur, the improvement comprising mixing at least a portion of the undiverted H2S-containing mixture with the hot effluent from said combustion zone upstream from said heat exchange zone, the amount of said gaseous mixture bypassing said combustion zone and mixed with said effluent varying inversely with the H2S content of said gaseous mixture, employing the resulting mixture to prepare a reaction mixture (1) of H2S and SO2 in an approximate molar ratio of about 2:1 having a temperature of from about 425* to 500*F, said temperature being achieved by direct heat exchange with one of the following streams: (1) a portion of said resulting mixture, (2) the remainder of said undiverted H2S-containing mixture, and thereafter subjecting the H2S and SO2 in said resulting mixture to reaction under known conditions to produce free sulfur.