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Sulphur
Many of the world’s oil and gas fields still to be developed are increasingly rich in sulphur. Yet tighter environmental regulations call for less sulphur in fuels. We are finding innovative ways to use this product.
As a vital nutrient for many crops, sulphur has been added to fertilisers for a long time to boost plant growth. Our fertiliser technology, Shell Thiogro, works to enhance this process. We are also putting the increased amount of sulphur produced along with oil and gas to use in other ways.
Good uses for sulphur
Pastilles of solid sulphur
Fertiliser produced with our new technology enables plants to more easily absorb sulphur. More effective sulphur use in fertiliser could increase yields by 14% on average in sulphur responsive soils, as illustrated in Shell Thiogro tests on crops by Shell and The Sulphur Institute in the USA. An example of recent technological advance is a biological desulphurisation process, developed in co-operation with Dutch firm Paques, which produces a biological, water-soluble form of sulphur that could be directly applied as fertiliser.
We have also been developing sulphur-enhanced concrete, Shell Thiocrete, that helps concrete manufacturers and other users benefit from sulphur’s properties in a growing number of ways. It is stronger and more resistant to acidic and salty conditions than conventional concrete, making it suitable for sea defences and waterworks. Its smooth surface is easily painted for use in road construction and garden tiles, while its production emits less CO2 than Portland cement and does not need any water.
Another use for sulphur is in the construction industry – for example, adding sulphur pellets to asphalt makes road surfaces more durable and resistant to extreme temperatures. We have already conducted extensive Shell Thiopave trials in the USA, Canada, India and China.
Processing sulphur
Sulphur occurs as hydrogen sulphide in natural gas, and in many different forms in crude oil. Shell technologies captures sulphur in its different compound forms: in the Sulfinol or ADIP processes an amine-based solution captures hydrogen sulphide; in biological desulphurisation bacteria “eat” hydrogen sulphide to produce sulphur; and in the Cansolv process sulphur dioxide is captured at the source or at the end of processing from gas in the smokestack.
Once captured the various sulphur compounds pass through two special units – the Claus unit and the Shell Claus Offgas Treating unit – where catalysts convert up to 99.99% of it to liquid sulphur. Finally the pure, or elemental, sulphur is cooled into a solid, bright yellow sulphur material that can be stored safely in stockpiles, or sent for industrial use or further processing to manufacture fertiliser, sulphur concrete or sulphur asphalt.
