Abstract: The invention is a process for liquefying a compound A from a mixture comprising at least compound A and at least one compound B. The mixture is available at a pressure P1 with separation of the at least one compounds B and/or of compound A being performed by distillation at a pressure substantially close to pressure P2 in order to produce at least a stream mainly comprising the compound A and at least a stream F4 comprising most of the at least one compound B. The invention has an application of methane and/or helium extraction during liquefaction of a natural gas.

Abstract: The invention concerns a process for isomerising a feed containing essentially hydrocarbons, preferably paraffins preferably containing 5 and/or 6 carbon atoms per molecule, in which said feed is treated in a distillation zone comprising an exhausting zone and a rectification zone associated with an isomerisation reaction zone, in the presence of an isomerisation catalyst and a gas stream containing hydrogen, characterized in that the reaction zone is at least partially internal to the distillation zone, and wherein the hydrogen-containing gas is fed by a dedicated gas distributor to the bottom of at least one catalytic bed within the isomerization reaction zone.

Abstract: The process allows to liquefy a gaseous mixture consisting at least partly of a mixture of hydrocarbons, such as a natural gas, by using a cooling mixture that is obtained, after a first cooling step, in a state referred to as "condensed single-phase" state.

Abstract: The process comprises a cold absorption step 2 for removing acid gas from natural gas using a solvent phase at a pressure P.sub.2 which delivers a purified gas 5; a step for depressurizing and separating resultant acidic solvent phase containing hydrocarbons (lines 4, 11), at a pressure P.sub.12 which is lower than pressure P.sub.2 in a column-heat exchanger 12 which delivers a purified gaseous effluent 13 overhead and a further solvent phase at the bottom (line 17) which is enriched in hydrogen sulphide; and a solvent phase regeneration step carried out in a distillation column 18 at a pressure P.sub.18 and no higher than pressure P.sub.12. A gas 29 containing essentially hydrogen sulphide which is depleted in hydrocarbons is recovered from column 18 and is a suitable feed for a Claus plant for eliminating H.sub.2 S. The regenerated hot solvent phase 20 indirectly exchanges heat with the cold acidic solvent phase from absorber 2 or separator 6. It is then recycled to the absorbent after cooling.

Abstract: A fluid consisting at least partly of a mixture of hydrocarbons is liquefied by means of the following stages:the mixture under pressure is cooled so as to condense it at least partly to produce a liquid phase and a gas phase, and bringing into contact of at least a fraction of each of said phases is simultaneously achieved at least partly in a countercurrent flow so as to obtain, by matter transfer, a gas phase enriched in light hydrocarbons and a first liquid phase enriched in heavy hydrocarbons, andthe two phases obtained thereby are separated and the gas phase enriched in light hydrocarbons is sent to a second cooling stage in order to obtain a second liquid phase enriched in light hydrocarbons.