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Greener refining

January 27, 1999, 08:00 CET

A new plant planned for Statoil's Danish refinery at Kalundborg near Copenhagen will cut pollution and save energy.

This facility is based on a patent-pending process developed by Denmark's Haldor Topsøe engineering company, which has contracted with Statoil to build what will be the first installation of its kind in the world.

The plant will allow Kalundborg to produce ammonium thiosulphate (ATS), a liquid fertiliser, from waste flows containing sulphur and ammonia.

Volumes of hydrogen sulphide and ammonia left over after desulphurisation of petrol, diesel oil and heating oil are on the increase as demands for reducing the sulphur content of these refined products get tighter.

Most of the hydrogen sulphide is normally converted to sulphur and transferred to other businesses for such applications as sulphuric acid production. The rest, and the ammonia, are incinerated to sulphur dioxide and nitrogen oxides for release to air in a very energy-intensive process.

With the new process, overall emissions from the refinery are reduced by 60-65 per cent for sulphur dioxide and 35 per cent for nitrogen oxides. Electricity consumption will also be cut.

The Danish authorities have promised to contribute DKK 12 million to the ATS process. Investment for the refinery will come to DKK 70 million, with production due to start in the spring of 2000.

ATS is primarily used to produce the liquid fertilisers which are increasingly replacing solid variants in industrial farming and market gardening. Achieving accurate dosages is easier with liquids, which makes them suitable for use with irrigation.