GB716244A - Improvements in and relating to sulphur recovery - Google Patents

Abstract

<PICT:0716244/III/1> In a process for the production of sulphur by partial combustion of hydrogen sulphide the mixture of hydrogen sulphide and sulphur dioxide thereby produced being passed through a plurality of stages of catalytic conversion and the reaction products from each stage of the conversion being treated for the recovery of sulphur, the concentration of hydrogen sulphide is increased before any stage of catalytic conversion by recycling hydrogen sulphide recovered from the waste gases so that the molecular ratio of hydrogen sulphide to sulphur dioxide is greater than 2. The concentration is preferably increased immediately before the final catalytic stage. Residual amounts of sulphur dioxide are removed from the gases leaving the final catalytic stage by washing with water in a lime-stone packed tower, and the hydrogen sulphide remaining is recovered by absorption in a medium from which it may be regenerated for recycling. The amount of regenerated hydrogen sulphide is preferably between 10 and 20 per cent. of the total hydrogen sulphide fed. In the drawings, hydrogen sulphide passes through flow controller 1 which diverts one-third of the stream to a combustion apparatus 3 to which air is also supplied to oxidize all the hydrogen sulphide to sulphur dioxide. The combustion products are mixed with the undiverted stream of gas and enter the first catalyst stage 4 at a temperature of about 600 DEG F. The mixture leaving the converter is cooled in heat exchanger 5 to a temperature just above its dew point by heat exchange with the gas mixture to be admitted to the second stage catalytic converter 7. The sulphur vapour is then removed by scrubbing with molten sulphur in the scrubber 6, the exit gas from which, together with hydrogen sulphide recovered from the tail gases by scrubbing with aqueous organic amine solution and regeneration therefrom, are passed to the heat exchanger 5 and heated therein to about 550 DEG F. before admission to the second converter 7. The sulphur vapour from the gases leaving converter 7 is removed by washing with liquid sulphur in a scrubber 8 and the mixture is passed to an absorber 9 packed with lime-stone to remove sulphur dioxide by water washing. The hydrogen sulphide remaining is led to an absorber 10 for removal by an organic amine solution and the exit gases pass through an oxide purifier 11 to remove last traces of hydrogen sulphide. The amine solution is passed to regenerator 13 and the hydrogen sulphide liberated therefrom is recycled to the exit line from scrubber 6 as above referred to.