Compressors for LNG Import Facility in the UK

Paul Boughton

Burckhardt Compression will deliver two Labys to Dragon LNG Limited for its liquefied natural gas (LNG) import facility at Milford HavenUK. The Laby has an ultra-low maintenance piston sealing design and is therefore ts suitable solution for boil-off gas applications. The gastight casing reduces gas emission and losses to the environment to zero.   

Delivery of the compressors will take place in the second half of 2006. Laby  compressors are used for liquid gas transport and storage as well as in the chemical and  petrochemical industries.

Labys compress bone-drydirtyabrasive and other gases with no  contamination and without oilwith a discharge pressure up to 300 bar (4350 psi)flow up to  11 000 Nm3/h (6500 scfm) and shaft power up to 2100 kW (2800 HP).

The compressors easily manages the compression of LNG boil-off  gas at suction temperatures down to minus 160°C (250°F). The compressors will be used to reliquefy boil-off gas which forms during LNG unloading of the LNG carriers and to maintain the LNG  storage temperature at minus 162°C.    

Natural gas is cooled in a large refrigeration system to minus 162°C (260°F)at either the point of  origin (gas production field) or the point of departure (LNG off loads terminal).     

LNG is formed by cooling natural gas to very low temperatures (minus 162°C (260°F)) at which  point the gas condenses into a liquidcommonly referred to as LNG. By  liquefyingit is possible to reduce the bulk or volume of the gas by a factor of about 600thus  enabling large amounts to be transported over great distances by tanker.

During transport the LNG  is carried in specially insulated tanks at atmospheric pressure. On landLNG is stored at nominally atmospheric pressure in large insulated tanks that are designed to minimise any heat ingress. Before the LNG can be exported to the gas transmission network it must be pressurised to network  pressure (up to 94 bar g) and converted back to natural gas; this is accomplished by heating the LNG in a series of submerged combustion vaporisers.

Burckhardt Compression AG  is based in WinterthurSwitzerland. www.burckhardtcompression.com

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