The invention relates to a system, method and apparatus for processing natural gas in an LNG facility. A natural gas feed is introduced into a heavies removal unit. The heavies removal system includes a heavies removal column and a distillation column. The heavies removal column and the distillation column are connected via a purge/recovery line. One or more components of the natural gas feed is purged from the heavies removal column to the distillation column via the purge/recovery line to obtain a specified concentration or concentration range of heavy components feeding into the distillation column.

The invention relates to a process and apparatus for separation of gas mixtures with reduced maintenance costs. The process and the apparatus consist of a feed stream separation stage (1), and a retentate separation stage (2), of which both are membrane separation stages, wherein the first retentate stream (7) is heated to temperature higher than the temperature of the feed stream (5), before it is introduced to the retentate separation stage (2), and the total capacity of the membranes used in the retentate separation stage (2) is higher than the total capacity of the membranes used in the feed stream stage (1).

Disclosed herein are scavenging and antifouling compositions useful in applications relating to the production, transportation, storage, and separation of crude oil and natural gas. Also disclosed herein are methods of using the compositions as scavengers and antifoulants, particularly in applications relating to the production, transportation, storage, and separation of crude oil and natural gas.

A treatment composition for remediating for remediating H.sub.2S, CO.sub.2 and other contaminant(s) in a fluid mixture of contaminated liquids and gasses comprising: a hydrocarbon based liquid; and at least one hydroxide compound dispersed or dissolved into the hydrocarbon based liquid. The at least one hydroxide compound dispersed or dissolved into the hydrocarbon based liquid constitutes 30-50 wt % of the treatment composition, the at least one hydroxide compound includes at least one of potassium hydroxide and sodium hydroxide, and a pH of the treatment composition is in a range of 13-14.0.

Cavitand compositions that comprise void spaces are disclosed. The void spaces may be empty, which means that voids are free of guest molecules or atoms, or the void spaces may comprise guest molecules or atoms that are normally in their gas phase at standard temperature and pressure. These cavitands may be useful for industrial applications, such as the separation or storage of gasses. Novel cavitand compounds are also disclosed.

Cavitand compositions that comprise void spaces are disclosed. The void spaces may be empty, which means that voids are free of guest molecules or atoms, or the void spaces may comprise guest molecules or atoms that are normally in their gas phase at standard temperature and pressure. These cavitands may be useful for industrial applications, such as the separation or storage of gasses. Novel cavitand compounds are also disclosed.

A methane hydrate production method comprising a step of performing a reservoir grouting process. The reservoir grouting process comprises: injecting a grouting agent into a frozen soil reservoir on the land or a seabed reservoir for targeting methane hydrate existing within sand particles of the target reservoirs; or injecting a filling material into cavities naturally or artificially occurred in a frozen soil reservoir on the land or a seabed reservoir for targeting methane hydrate existing within sand particles of the target reservoirs, and enabling a grouting body being constructed.

A feed containing methane and nitrogen gas is processed in a three-stage membrane system, each stage of which is selective for methane over nitrogen. The methane enriched permeate from the first stage is removed as product gas. The methane-depleted residue from the second stage is purified in second and third cascaded stages to provide second and third permeates and second and third residues. The third stage permeate is recycled to the feed.

A biogas-utilizing methanation system includes: a solid oxide fuel cell using a to-be-treated gas as a fuel gas; a hydrogen production device capable of producing hydrogen by using power of a renewable energy power generation device; and a methanation device capable of methanating carbon dioxide in the system with the hydrogen produced by the hydrogen production device. The carbon dioxide in the system can be stored in a storage device on the basis of the supply amount of the to-be-treated gas or the power of the renewable energy power generation device.

The present disclosure relates to a gas hydrate inhibitor composition, comprising A) a compound according to formula (1) ##STR00001## wherein R1 is an alkyl group having from 1 to 5 carbon atoms; R2 is hydrogen or an alkyl group having from 1 to 5 carbon atoms; R3 is present or not as hydrogen and organic moieties having from 1 to 20 carbon atoms; R4 is selected from —(CH.sub.2).sub.t—, —[CH.sub.2—CHR.sup.6).sub.t]—, —(CH.sub.2—CHR.sup.6O).sub.u—(CH.sub.2).sub.t— and combinations thereof; R5 is an alkyl or alkenyl group having 4 to 22 carbon atoms; R6 is hydrogen or an alkyl group having from 1 to 4 carbon atoms; R7 is hydrogen or an alkyl group having from 1 to 4 carbon atoms; R8 is present or not as hydrogen or organic moieties having from 1 to 20 carbon atoms; t is 2, 3 or 4; u is an integer between 0 and 100; n is 0 or 1 m is 0 or 2 o is 0 or 2, p is 0 or 1 X.sup.− is an anion, and a synergistic cationic surfactant which is selected from quaternary benzyl ammonium salts having besides the benzyl group at least one C.sub.8-C.sub.18-alkyl group bound to the nitrogen atom.