This specification relates to operating industrial facilities, for example, crude oil refining facilities or other industrial facilities that include operating plants that process natural gas or recover natural gas liquids.

A method for liquefying a feed gas stream. A refrigerant stream is cooled and expanded to produce an expanded, cooled refrigerant stream. Part or all of the expanded, cooled refrigerant stream is mixed with a make-up refrigerant stream in a separator, thereby condensing heavy hydrocarbon components from the make-up refrigerant stream and forming a gaseous expanded, cooled refrigerant stream. The gaseous expanded, cooled refrigerant stream passes through a heat exchanger zone to form a warm refrigerant stream. The feed gas stream is passed through the heat exchanger zone to cool at least part of the feed gas stream by indirect heat exchange with the expanded, cooled refrigerant stream, thereby forming a liquefied gas stream. The warm refrigerant stream is compressed to produce the compressed refrigerant stream.

Methods and systems for liquefying natural gas using environmentally-friendly low combustibility refrigerants are provided. Methods of liquefaction include cooling a fluid in an LNG facility via indirect heat exchange with an environmentally-friendly low combustibility refrigerants that are propane, ethane and methane mixed with small amounts of fluorinated olefin, but still within close proximity to the boiling points of the pure refrigerants such that the mixed refrigerants can still be used in an optimized cascade process.

A liquefaction system and method for producing liquefied natural gas (LNG) is provided. The liquefaction system may include a heat exchanger to cool natural gas to LNG, a first compressor to compress and combine first and second portions of a single mixed refrigerant from the heat exchanger, a first cooler to cool the single mixed refrigerant from the first compressor to a first liquid phase and a gaseous phase, and a first liquid separator to separate the first liquid phase from the gaseous phase. The liquefaction system may also include a second compressor to compress the gaseous phase, a second cooler to cool the compressed gaseous phase to a second liquid phase and the second portion of the single mixed refrigerant, a second liquid separator to separate the second liquid phase from the second portion of the single mixed refrigerant, and a pump to pressurize the first liquid phase.

A sinusoidal corrugated tube-type spiral wounded heat exchanger suitable for FLNG, wherein a top of an outer cylinder has a shell-side refrigerant inlet and a bottom thereof has a shell-side refrigerant outlet; a sinusoidal corrugated tube-type liquid distributor is below the shell-side refrigerant inlet, a first sinusoidal corrugated winding tube bundle and a second sinusoidal corrugated winding tube bundle, which are heat exchanger tubes with a sinusoidal wave shape, are inside the outer cylinder, and peaks and troughs of the first sinusoidal corrugated winding tube bundle and the second sinusoidal corrugated winding tube bundle are in staggered correspondence one by one from top to bottom; a sinusoidal corrugated tube-type liquid distributor includes a one-into-two-type tube, a two-into-four-type tube, two sinusoidal corrugated tube-type liquid distribution tubes from top to bottom.

A method is provided for operating a system for the liquefaction of gas of the type comprising a main heat exchange vessel, a bundle for the gas to be liquefied extending through said MCHE and a refrigerant compression circuit of which a first end leads evaporated refrigerant from the vessel towards a compressor and a second end supplies the compressed and cooled refrigerant from the compressor towards the MCHE. For avoiding problems during heat up or during start up of the heat exchanger the pressure within the liquefaction system is controlled by regulating the amount of evaporated refrigerant in the liquefaction circuit.

A distillation apparatus includes a first distillation column and one or more second distillation columns. A higher-pressure part of the first distillation column includes at least part of a rectifying section, and performs gas-liquid contact at a relatively high pressure. A lower pressure-part of the first distillation column includes at least part of a stripping section and performs gas-liquid contact at a relatively low pressure. A vapor line, which includes a pressurizing means, directs a vapor discharged from a column top of the lower-pressure part to a column bottom of the higher-pressure part. A liquid line directs a liquid discharged from the column bottom of the higher-pressure part to the column top of the lower pressure part. Corresponding heat exchange structures transfer heat in both directions between the rectifying section of the first distillation column and at least one second distillation column.

Implementations described and claimed herein provide systems and methods for processing liquefied natural gas (LNG). In one implementation, a dry feed gas is received. The dry feed gas is chilled with clean vapor from a heavies removal column to form a chilled feed gas. The chilled feed gas is partially condensed into a vapor phase and a liquid phase. The liquid phase retains freezing components. The freezing components are extracted using a reflux stream in the heavies removal column. The freezing components are removed as a condensate. The vapor phase is compressed into a clean feed gas. The clean feed gas is free of the freezing components for downstream liquefaction.

A gas liquefaction apparatus includes at least a source-gas supply line that supplies source gas; a room-temperature heat exchanger, a preliminary-cooling heat exchanger, and a liquefaction/supercooling heat exchanger that are provided in series sequentially in the source-gas supply line and that cool the source gas; a separation drum that separates the source gas containing a condensate, which has been cooled by heat exchange up to a liquefaction temperature of the source gas or below, into a gas component and a liquefied component; and a refrigerant-gas supply line that uses a gas component separated by the separation drum as refrigerant gas to supply the refrigerant gas in a direction opposite to a supply direction of the source gas, in order of the liquefaction/supercooling heat exchanger, the preliminary-cooling heat exchanger, and the room-temperature heat exchanger.

A system for the regeneration of nitrogen energy within a closed loop cryogenic system is described. A liquid nitrogen storage is provided in fluid communication with a first flow line. A pump pumps liquid nitrogen from the liquid nitrogen storage to the first flow line. At least one cryogenic cooling loop is provided in fluid communication with the first flow line. The cryogenic cooling loop has an nitrogen intake and a nitrogen outlet with the nitrogen outlet being positioned downstream of the nitrogen intake. The cryogenic cooling loop has a heat exchanger between the nitrogen intake and the nitrogen outlet. A turbo expander used for re-cooling the nitrogen flowing through the first flow line and the at least one cryogenic cooling loop has an inlet and an outlet. The inlet is provided in fluid communication with the first flow line. The turbo expander is connected to a power source. A second flow line connects the outlet of the turbo expander to the liquid nitrogen storage.