In future the sulphur production industries are associated with industrial pollution control aspects. Mainly chemical plant that produce harmful hydrogen sulfide as by-product and release it to the atmosphere. Sour gas and petroleum industries convert hydrogen sulphide to sulphur by combustion. They use hydrogen sulphide as a fuel in fired heater. However, the flue gases released from the combustion are accumulated with sulphur dioxide gas (a green house gas). This becomes more dangers.
A wise option to prevent hydrogen sulphide pollution is by converting it to solid sulphur and water. Sulphur, so obtained can be used for fertilizer industries to produce ammonium sulphate. For example sulphur dioxide is sprightly converted to fertilizer when reacted with ammonia. There are techniques to convert sulphur dioxide to some useful products.
A process description sulphur recovery process (harmful hydrogen sulfide gas is converted to molten sulphur):
Sulphur recovery can be done when hydrogen sulphide is burned with air. H2S which is recovered from the desulphurisation plants by means of scrubbing undergo oxidation and reduction chemical reaction in a catalytic fixed bed reactor as show below.
- 2H2S + 3O2 ↔ 2SO2 + 2H2O -247.89 Kcal
- 4H2S + 2SO2 ↔ S6 + 4H2O -42.24 Kcal
The above reactions are exothermic in nature. On the surface of bauxite catalyst the reaction is carried forward yielding about 70-80% conversion. Finally with series of condensers and scrubbers the molten sulphur is obtained for shipping. The process conditions and operation procedure is given in a process flow sheet which contains the stream of unit operation involved in the hydrogen sulphide conversion.
Investing in chemical refining and petrochemical industries in future depend on the smooth running of plant that meets the environmental pollution specification of hydrogen sulphide removal and storage. This process makes the chemical plant turning into green technology.
Process flow-sheet of hydrogen sulphide treatment for sulphur recovery: