Method of liquefaction of natural gas
AssigneeCompagnie Francaise d'Etudes et de Construction "Technip"
InventorHenri Paradowski
Life of this patent
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Abstract
A method of liquefying natural gas, wherein the gas (1) is cooled and separated into a liquid phase (6) and a gaseous phase (8) which is expanded (9) and added to the liquid phase in the column (7), at the head of which the gas enriched with methane (21) is separated and recompressed (27) and carried to the liquefaction (32, 33, 34) whereas the liquid phase from the bottom of column (7) is expanded and rectified in column (14); the head effluent (19) being condensed (20) and conveyed as a reflux (25) to column (7); the pressure in column (7) being higher than that of column (14); the C.sub.3 + hydrocarbons from the bottom (16) being separated and the methane liquefaction (33, 34) being conventional.
Claims9
Method of liquefaction of natural gas, comprising the steps of
- cooling a natural gas containing methane and a hydrocarbon heavier than methane under a pressure P.sub.1 so as to form at least one gaseous phase G.sub.1,
- expanding the gaseous phase G.sub.1 to lower its pressure and to bring it to a pressure P.sub.2 lower than the pressure P.sub.1,
- carrying the product of the expansion under the pressure P.sub.2 into a first contact fractionating zone,
- drawing off residual gas G.sub.2 enriched with methane from the head of the first fractionating zone,
- drawing off a liquid phase L.sub.2 from the bottom of the first fractionating zone,
- conveying the liquid phase L.sub.2 into a second zone for fractionating through distillation,
- drawing off at least one liquid phase L.sub.3 enriched with hydrocarbons heavier than methane from the bottom of the second fractionating zone,
- drawing off a gaseous phase G.sub.3 from the head of said second fractionating zone,
- condensing at least one part of the gaseous phase G.sub.3 drawn off from the head of the second fractionating zone to produce a condensed phase L.sub.4,
- raising the pressure of at least one portion of the condensed phase L.sub.4,
- carrying said at least one portion of the condensed phase L.sub.4 to the first fractionating zone as a reflux,
- cooling the residual gas G.sub.2 under a pressure at least equal to the pressure P.sub.2 in a methane liquefaction zone so as to obtain a liquid rich in methane, and
- operating the second fractionating zone under a pressure P.sub.4 which is lower than the pressure P.sub.2 of the first fractionating zone.
Dependencies are inferred from the claim text.