Saipem S.a.

Saipem Limited

Eric Zielinski

Marc Bonnissel

Bertrand Du Parc

Benjamin Rodier

Nathalie Trichard

Julien Bellande

A process for liquefying a natural gas comprising a mixture of hydrocarbons predominating in methane, the process comprising a first semi-open refrigerant cycle with natural gas in which any natural gas liquids that have condensed are separated from the natural gas feed stream, which stream then passes through a main cryogenic heat exchanger () in order to contribute by heat exchange to pre-cooling a main natural gas stream (F-P) and to cooling an initial refrigerant gas stream (G-), a second semi-open refrigerant cycle with natural gas for contributing to pre-cooling the natural gas and the refrigerant and also to liquefying the natural gas, and a closed refrigerant cycle with refrigerant gas for subcooling the liquefied natural gas and for delivering refrigeration power in addition to the other two cycles. The invention also provides a natural gas liquefaction installation for performing such a process.

Method for liquefying natural gas and for recovering possible liquids from the natural gas, comprising two refrigerant cycles semi-open to the natural gas and a refrigerant cycle closed to the refrigerant gas

A method for liquefying a natural gas primarily including methane, preferably at least 85% of methane, the other components essentially including nitrogen and C2-C4 alkanes, in which the natural gas to be liquefied is liquefied by circulating at a pressure P0 no lower than the atmospheric pressure (Patm), P0 preferably being higher than the atmospheric pressure, in at least one cryogenic heat-exchanger (EC, EC, EC) by a counter-current closed-circuit circulation in indirect contact with at least one stream of coolant gas remaining in the compressed gaseous state at a pressure P1 that is entering the cryogenic heat-exchanger at a temperature T3' that is lower than T3, T3 being the liquefaction temperature of the liquefied natural gas at the pressure P0 at the output of said cryogenic exchanger, characterized in that the coolant gas includes a mixture of nitrogen and at least one other component selected from among neon and hydrogen.

Method for liquefying natural gas with a mixture of coolant gas

A process for liquefying natural gas by; a) causing it to flow through three series connected heat exchangers, where gas is cooled to T; Tis less/equal to the liquefaction temperature of natural gas at atmospheric pressure; and b) causing the closed circuit circulation of a first stream of refrigerant gas at a pressure Plower than Pentering the third exchanger and leaving the first exchanger, the first stream obtained using a first expander to expand a first portion of a second stream at Phigher than P, the second stream flowing relative to the natural gas stream entering the first exchanger and leaving the second exchanger; and a third stream at a pressure Phigher than Pand lower than Pflowing relative to the first stream, entering the second exchanger and leaving the first exchanger; c) the second stream at the pressure Pobtained by compression.

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Versailles, France

Eric Zielinski