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Linde Aktiengesellschaft

Oystein Sorensen

Manfred Steinbauer

Arne Olav Fredheim

Pentti Paurola

Christian Pfeiffer

Rudolf Stockmann

Wolfgang G Forg

Manfred Bolt

Manfred B&ouml;lt

Wolfgang F&ouml;rg

In the liquefaction of a hydrocarbon by indirect heat exchange with the refrigerant mixture of a refrigerant mixture cycle, the refrigerant mixture being compressed in multiple stages, the compressed refrigerant mixture ( ) is at least partially condensed (E ) downstream of the penultimate compressor stage and is fractionated (D ) into a higher-boiling liquid fraction ( ) and a lower-boiling gas fraction ( ). The lower-boiling gas fraction ( ) is compressed to the final pressure, partially condensed (E ) and fractionated (D ) into a lower-boiling gas fraction ( ) and a higher-boiling liquid fraction ( ). The higher-boiling liquid fraction ( ) is added to the partially condensed refrigerant mixture stream ( ), and the gas fraction ( ) forms the lower-boiling refrigerant mixture fraction and the liquid fraction ( ) forms the higher boiling refrigerant mixture fraction of the refrigerant mixture cycle. Alternatively, the compressed refrigerant mixture ( ) can be partially condensed (E , E , E ) after each compressor stage and fractionated in each case into a lower-boiling gas fraction ( ) and a higher-boiling liquid fraction ( ). Only the gas fraction ( ) from the partial condensation (E , E ) in each case is further compressed and the liquid fractions ( ) from the second fractionation (D , D ) are added to the partially condensed stream ( ) from the first compressor stage upstream of its fractionation (D ). The gas fraction ( ) from the final fractionation (D ) forms the lower-boiling refrigerant mixture fraction and the liquid fraction ( ) from the first fractionation (D ) forms the higher-boiling refrigerant mixture fraction of the refrigerant mixture cycle.

Process for liquefying a hydrocarbon-rich stream

The invention relates to a method for liquefying a stream rich in hydrocarbons, especially a stream of natural gas, by the indirect exchange of heat with the refrigerants in a closed-circuit cascade of mixed refrigerants. According to the invention, said closed-circuit cascade of mixed refrigerants consists of at least 3 circuits of mixed refrigerants, with each circuit comprising different refrigerants. The first of the three mixed refrigerant circuits is used for pre-cooling (E,), the second for liquefying E,), and the third for super-cooling (E,) the hydrocarbon-rich stream (,) to be liquefied. The method provided for in the invention reduces specific energy consumption and investment costs since the three circuits of mixed refrigerants are or can be optimally adjusted to the enthalpy temperature curves of the hydrocarbon-rich stream to be liquefied and the refrigerant mixtures.

Method for liquefying a stream rich in hydrocarbons

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Trondheim, Norway

Oystein Sorensen