The present invention relates to a method of cooling and separating a hydrocarbon stream: (a) passing an hydrocarbon feed stream (7) through a first cooling and separation stage to provide a methane enriched vapour overhead stream (110) and a methane depleted liquid stream (10); (b) passing the methane depleted liquid stream (10) to a fractionation column (200) to obtain a bottom condensate stream (210), a top stream enriched in C1-C2 (220) and a midstream enriched in C3-C4 (230), (c) cooling the upper part of the fractionation column (201) by a condenser (206), (d) obtaining a split stream (112) from the methane enriched vapour overhead stream (110) and obtaining a cooled split stream (112) by expansion-cooling the split stream (112), (e) providing cooling duty to the top of the fractionation column (201) using the cooled split stream (112).

A method and apparatus for cooling a hydrocarbon stream such as natural gas. An initial hydrocarbon stream is passed through a first separator to provide an initial overhead stream and a mixed hydrocarbon feed stream. The initial overhead stream is cooled to provide a cooled hydrocarbon stream such as LNG, and at least a C1 overhead stream and one or more C2, C3 and C4 overhead streams are separated from the mixed hydrocarbon feed stream. At least a fraction of at least one of the group comprising: the C2 overhead stream, the C3 overhead stream and the C4 overhead stream is cooled with the C1 overhead stream to provide a cooled stream, which is further cooled against at least a fraction of the cooled, preferably liquefied, hydrocarbon stream to provide an at least partly liquefied cooled stream.

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 (4) 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-0), 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.

An integrated method for the production of liquefied natural gas (LNG) and syngas is provided. The method can include the steps of: utilizing letdown energy of a high pressure natural gas stream that is withdrawn from a natural gas pipeline to provide a warm temperature cooling; utilizing a refrigeration cycle to provide a cold temperature cooling, wherein the refrigeration cycle comprises a refrigerant recycle compressor that is powered utilizing a steam turbine; and cooling a second high pressure natural gas stream using the warm temperature cooling and the cold temperature cooling to produce an LNG product stream. The second high pressure natural gas stream is withdrawn from the natural gas pipeline, and the steam turbine is powered by high pressure steam that is produced from a syngas production facility.

A mixed phase pressurized unstabilized hydrocarbon stream is fed into a stabilizer column at a feed pressure. A liquid phase of stabilized hydrocarbon condensate is discharged from a bottom end of the stabilizer column, while a vapor phase of volatile components from the pressurized unstabilized hydrocarbon condensate stream is discharged from a top end of the stabilizer column. The vapor phase being discharged from the top end of the stabilizer column is compressed and subsequently passed through an ambient heat exchanger wherein partial condensation takes place. The resulting partially condensed overhead stream is separated in an overhead separator into a vapor effluent stream and an overhead liquid stream. After discharging the overhead liquid stream from the overhead separator, it is selectively divided into a liquid reflux stream and a liquid effluent stream. The liquid reflux stream is expanded to the feed pressure and fed into the stabilizer column.

A mixed phase unstabilized hydrocarbon stream is created by partially evaporating an unstabilized hydrocarbon condensate stream, including indirectly heat exchanging the unstabilized hydrocarbon condensate stream against an effluent stream in a feed-effluent heat exchanger. The mixed phase unstabilized hydrocarbon stream is fed into a stabilizer column. A liquid phase of stabilized hydrocarbon condensate is discharged from a bottom end, while an overhead vapor stream consisting of a vapor phase comprising volatile components from the unstabilized hydrocarbon condensate stream is discharged from a top end of the stabilizer column. The overhead vapor stream is passed through an overhead condenser. The resulting partially condensed overhead stream is separated in an overhead separator into a vapor effluent stream and an overhead liquid stream. The effluent stream against which the unstabilized hydrocarbon condensate stream is heat exchanged in the feed-effluent heat exchanger comprises the vapor effluent stream.

A novel method and system for liquefying and distilling raw natural gas into NGL and liquid methane (LNG) product streams, with at least one novel feature including the use of a mixed refrigerant comprising naturally occurring natural gas liquids that were recovered from the inlet gas stream being processed. Heat exchangers and distillation towers are configured to produce high purity liquefied natural gas (LNG) and NGL product streams, utilizing liquid NGL as the process refrigerant for both systems.

A liquefaction system is capable of sequentially or simultaneously liquefying multiple feed streams of hydrocarbons having different normal bubble points with minimal flash. The liquefying heat exchanger has separate circuits for handling multiple feed streams. The feed stream with the lowest normal boiling point is sub-cooled sufficiently to suppress most of the flash. Feed streams with relatively high normal boiling points are cooled to substantially the same temperature, then blended with bypass streams to maintain each product near its normal bubble point. The system can also liquefy one stream at a time by using a dedicated circuit or by allocating the same feed to multiple circuits.

The invention relates to a method and system of preparing a lean methane-containing gas stream (22), comprising: feeding a hydrocarbon feed stream (10) into a separator (100); withdrawing from the separator (100) a liquid bottom stream (12); passing the liquid bottom stream (12) to a stabilizer column (200); withdrawing from the stabilizer column (200) a stabilized condensate stream (13) enriched in pentane, withdrawing from the stabilizer column (200) a stabilizer overhead stream (14) enriched in ethane, propane and butane; splitting the stabilizer overhead stream (14) according to a split ratio into a main stream portion (15) and a slip stream portion (16), passing the slip stream portion (16) to a fractionation unit (300) to obtain an ethane enriched stream (17) and a bottom stream enriched in propane and butane (18).

A system and method for cooling a gas using a mixed refrigerant includes a compressor system and a heat exchange system, where the compressor system may include an interstage separation device or drum with no liquid outlet, a liquid outlet in fluid communication with a pump that pumps liquid forward to a high pressure separation device or a liquid outlet through which liquid flows to the heat exchanger to be subcooled. In the last situation, the subcooled liquid is expanded and combined with an expanded cold temperature stream, which is a cooled and expanded stream from the vapor side of a cold vapor separation device, and subcooled and expanded streams from liquid sides of the high pressure separation device and the cold vapor separation device, or combined with a stream formed from the subcooled streams from the liquid sides of the high pressure separation device and the cold vapor separation device after mixing and expansion, to form a primary refrigeration stream.