A process for obtaining a product gas and product LNG having pressure P1 close to the atmospheric pressure from lean LNG, includes: a) branching the lean LNG to obtain a first flow and a second flow; b) cooling the second flow by using a refrigerant; c) branching a liquid flow derived from the cooled second flow to obtain refrigerant LNG and remaining LNG; d) subjecting the remaining LNG to pressure reduction and gas-liquid separation to obtain a gas phase flow and a liquid phase flow (product LNG) having pressure P1; e) subjecting the refrigerant LNG to pressure reduction; f) using a flow from the step e as the refrigerant; g) joining, before or after the step f, the gas phase flow having pressure P1 to a flow from the step e; h) liquefying a flow resulting from the steps f and g by pressure increase and cooling (through heat exchange with the first flow); i) increasing the first flow in pressure before the step h; j) obtaining the product gas by regasifying the first flow after the steps h and i; and k) joining a flow liquefied in the step h to the second flow.

A process for purifying a gaseous feed stream of natural gas including methane, CO.sub.2 and heavy hydrocarbons including step a): cooling the gaseous feed stream in a heat exchanger; step b): introducing the cooled stream into a phase-separating chamber to produce a liquid stream depleted in methane and enriched in heavy hydrocarbons and a gaseous stream; step c): separating the gaseous stream obtained from step b) in a first membrane producing at least one CO.sub.2-enriched permeate stream and a residual stream enriched in methane; step d): introducing the residual stream obtained from step c) into a phase-separator to produce a liquid stream and a gaseous stream; step e): heating the gaseous stream obtained from step d) by introducing it into the heat exchanger used in step a) counter-currentwise with the feed stream thereby producing a gaseous stream depleted in CO.sub.2 and enriched in methane.

A method for efficiently reducing the energy required to convert natural gas from a natural gas pressure letdown facility at high pressure and pipeline/wellhead temperature to liquid natural gas in close proximity to/collocation with a natural gas pressure letdown/regulation facility using Non-Freezing Vortex Tubes (U.S. Pat. No. 5,749,231) in arrangement with indirect contact heat exchangers. The Non-Freezing Vortex Tubes separate the inlet natural gas into hot flow and cold flow outlet natural gas flows. One portion of the natural gas flow from the high-pressure transmission line/gas wellhead is directed through the Non-Freezing Vortex Tube and the cold outlet flow of the natural gas is directed to the indirect contact heat exchanger(s) to act as the cooling medium. The liquid natural gas plant's required natural gas flow is directed at the existing pipeline/wellhead gas pressure through the heat exchanger and cooled. The already cooled natural gas flow is directed to a turbo expander and refrigeration cold box system where it is further chilled and converted into liquid natural gas at −162° C.

A method is described for removing carbon dioxide during Liquid Natural Gas production from natural gas at gas pressure letdown stations. The above method removes carbon dioxide from a Liquid Natural Gas production stream by using hydrocarbon fractions taken from a gas for consumption stream as a carbon dioxide stripping adsorption agent for a stripping column used to remove carbon dioxide.

Embodiments provide a method for preventing shutdowns in LNG facilities by removing heavy hydrocarbons from the inlet gas supply. According to an embodiment, there is provided an LNG facility treating pipeline quality natural gas that is contaminated with lubrication oil and low concentrations of heavy hydrocarbons. Due to contamination, the behavior of the pipeline quality natural gas is not properly predicted by thermodynamic modeling. In an embodiment, heavy hydrocarbons are removed by a drain system in a heat exchanger. In an embodiment, heavy hydrocarbons are removed by a treatment bed.

Embodiments provide a method for preventing shutdowns in LNG facilities by removing heavy hydrocarbons from the inlet gas supply. According to an embodiment, there is provided an LNG facility treating pipeline quality natural gas that is contaminated with lubrication oil and low concentrations of heavy hydrocarbons. Due to contamination, the behavior of the pipeline quality natural gas is not properly predicted by thermodynamic modeling. In an embodiment, heavy hydrocarbons are removed by a drain system in a heat exchanger. In an embodiment, heavy hydrocarbons are removed by a treatment bed.

Provided are mixed refrigerant systems and methods and, more particularly, to a mixed refrigerant system and methods that provides greater efficiency and reduced power consumption.

The disclosure provides a method for separating components of a gas. A feed gas stream is cooled in a first vessel. The feed gas stream includes methane, water, carbon dioxide, and Natural Gas Liquids. The feed gas stream is cooled in a first vessel. A portion of the water condenses to form a primary liquid stream, resulting in a first depleted gas stream, which is cooled in a second vessel. A portion of the NGLs condense to form a secondary liquid stream, resulting in a second depleted gas stream, which is cooled in a condensing exchanger. A first portion of the methane condenses to form a liquid methane stream, resulting in a third depleted gas stream, which is cooled in a third vessel. A portion of the carbon dioxide condenses, desublimates, or condenses and desublimates as a final product stream, also resulting in a fourth depleted gas stream.

A method of recondensing boil off gas includes receiving liquefied natural gas from a storage tank and increasing the pressure of the received liquefied natural gas to produce increased pressure liquefied natural gas. The method further includes receiving boil off gas from the storage tank at a gas inlet of an ejector, and receiving the increased pressure liquefied natural gas at a liquefied gas inlet of the ejector. The pressure of the increased pressure liquefied gas is used as a motive force to eject combined liquefied natural gas and boil off gas at a pressure greater than that of the boil off gas received at the gas inlet of the ejector. The method additionally includes increasing the pressure of the fluid ejected from the ejector to produce increased pressure ejected fluid.

A process for purifying a gaseous feed stream of natural gas including methane, CO.sub.2 and heavy hydrocarbons including step a): cooling the gaseous feed stream in a heat exchanger; step b): introducing the cooled stream into a phase-separating chamber to produce a liquid stream depleted in methane and enriched in heavy hydrocarbons and a gaseous stream; step c): separating the gaseous stream obtained from step b) in a first membrane producing at least one CO.sub.2-enriched permeate stream and a residual stream enriched in methane; step d): introducing the residual stream obtained from step c) into a phase-separator to produce a liquid stream and a gaseous stream; step e): heating the gaseous stream obtained from step d) by introducing it into the heat exchanger used in step a) counter-currentwise with the feed stream thereby producing a gaseous stream depleted in CO.sub.2 and enriched in methane.