GB716264A - Improvements in and relating to sulphur recovery - Google Patents

Abstract

In the production of sulphur by partial combustion of hydrogen sulphide, the mixture of hydrogen sulphide and sulphide dioxide formed being passed through a plurality of stages of catalytic conversion and the reaction product from each stage of conversion being treated for the recovery of sulphur, the concentration of sulphur dioxide is increased before any stage of catalytic conversion by recycling sulphur dioxide recovered from the waste gases so that the molecular ratio of hydrogen sulphide to sulphur dioxide is less than 2. The sulphur dioxide concentration is preferably increased immediately before the final catalytic stage. The sulphur dioxide is recovered from the waste gases leaving the system by absorption in a medium from which it may be regenerated and is recycled, preferably in an amount equivalent to up to 25 per cent. of the sulphur in the original hydrogen sulphide. In the drawing pure <PICT:0716264/III/1> hydrogen sulphide is split by flow controller 1 into two streams, one of which passes through a boiler 3 together with air to completely oxidize the hydrogen sulphide therein to sulphur dioxide, which sulphur dioxide rejoins the undiverted portion of the main stream and enters a first catalytic converter 4 at 600 DEG F. The mixture leaving the converter is then passed to a heat exchanger 5 and cooled to a temperature just above its dew point before being admitted to a molten sulphur scrubber 6. The gases leaving the scrubber 6 are passed through heat exchanger 5 thereby being heated to about 550 DEG F. and passed to the second converter 7. A stream of sulphur dioxide recovered from the waste tail gases joins the stream of gases leaving the scrubber 6 to enter the converter 7 via heat exchanger 5. The gases from the converter 7 are scrubbed with sulphur in scrubber 8 and passed to a tower 9 for cooling, and to a leadlined tower 10 containing iron oxide which removes hydrogen sulphide. The gases from tower 10 then pass to an absorber 11 where the sulphur dioxide is absorbed by dimethylaniline. The residual gases pass to the atmosphere and the dimethylaniline is regenerated at 13 to free the sulphur dioxide which is passed to the heat exchanger 5 as referred to above. Specification 716,244 is referred to.