초록 ▼

Method and apparatus for cooling a gaseous mixture wherein a fractional condensation of said mixture is carried out under a high pressure by using at least a first stage and a last stage of fractional condensation, the penultimate and the last condensed fractions are expanded down to a low pressure

Method and apparatus for cooling a gaseous mixture wherein a fractional condensation of said mixture is carried out under a high pressure by using at least a first stage and a last stage of fractional condensation, the penultimate and the last condensed fractions are expanded down to a low pressure forming a main refrigerating stream, and at least the first condensed fraction of the cycle mixture is expanded down to an intermediate pressure between said high pressure and said low pressure forming an auxiliary refrigerating stream.

대표청구항 ▼

A method of liquifying and subcooling under pressure a gaseous mixture (NG) by means of a single refrigerating, closed-loop cycle with a cycle mixture comprising a plurality of components, said cycle mixture being compressed from a low pressure to a high pressure, refrigerated under said high pressu

A method of liquifying and subcooling under pressure a gaseous mixture (NG) by means of a single refrigerating, closed-loop cycle with a cycle mixture comprising a plurality of components, said cycle mixture being compressed from a low pressure to a high pressure, refrigerated under said high pressure by an external coolant and thereafter expanded down to a lower pressure, wherein said refrigerating cycle comprises the steps of: a. fractionally condensing under said high pressure and cycle mixture by successively: 1. partially condensing said cycle mixture, which has been compressed (at 1″) to said high pressure, through indirect heat exchange with said external coolant while said cycle mixture is thermally separated from and independent of said gaseous mixture in a first stage (2) of fractional condensation, 2. separating (at 4) the resulting partially condensed cycle mixture (4a) into a first condensed fraction (4c) and a first vapor fraction (4b), 3. subjecting said first vapor fraction (4b) to at least one further stage of fractional condensation (60; 17) at a temperature lower than that of the preceding stage of fractional condensation, said further stage of fractional condensation comprising the steps of: i. partially condensing (at 10a; 17a) the vapor fraction being processed; ii. separating (at 5; 18) the partially condensed fraction (5a, 18a) into a following condensed fraction (5c; 18c) and a following vapor fraction (5b; 18b), iii. expanding (at 11; 19) the preceding condensed fraction (4c) to a lower pressure which is intermediate said low pressure and said high pressue of said cycle, iv. spraying the resulting expanded fraction as at least one part of an intermediate refrigerating vapor stream (60; 10b, 17b) in counter-current indirect heat exchanging relationship with said preceding condensed fraction (10a, 17a) to subcool said preceding condensed fraction, thereby forming a reheated intermediate refrigerating vapor stream (15) consisting of those condensed fractions (17d, 10d) which had been expanded (at 19, 11) to said intermediate pressure and sprayed (at 17b, 10b, 107), and also consisting of the whole cycle mixture less said last (9d) and last but one (5c) condensed fractions, v. recovering from the last stage of said further stage of fractional condensation (60) and separation (5), a last but one condensed fraction (5c) and a last vapor fraction (5b), 4. expanding (at 12) said last but one condensed fraction (5c) to said low pressure and spraying the resulting expanded fraction as at least one part of a final refrigerating vapor stream (6; 8b) in counter-current indirect heat exchanging relationship with i. said last but one condensed fraction (6; 8d) to subcool same, and ii. with said last vapor fraction (6; 8a) to condense same as a last condensed fraction (6; 9d), 5. expanding (at 13) the last condensed fraction (6; 9d) to said low pressure and spraying the resulting expanded fraction as another part of said final refrigerating vapor system (6; 9b, 98) in counter-current indirect heat exchanging relationship with i. said last condensed fraction (6; 9d) to subcool same, and ii. with the last but one condensed fraction (6; 8d) to further subcool same in added relation to said one part of a final refrigerating vapor stream (14) consisting of the added last (9d) and last but one (15c9 condensed fractions which have been expanded (at 13, 12), respectively, to said low pressure, 6. cooling, liquifying and subcooling the gaseous mixture (NG) under pressure (at 6; 7c, 8c, 9c) through heat exchange with at least said last condensed fraction (6; 8a, 9d) and in counter-current indirect heat exchanging relationship with at least said final refrigerating stream, the respective heat exchanges at said low pressure vaporizing and reheating the respective condensed fractions to form a reheated final refrigerating vapor stream (14); b. recompressing (at 1′) said reheated final refrigerating vapor stream (14) to raise the pressure thereof from said low pressure (1′a) to said intermediate pressure (1′b); and c. combining said final refrigerating vapor stream (14), after its compression to said intermediate pressure (1′b), with said reheated intermediate refrigerating vapor stream (15), and recompressing the resulting combined vapor stream (1″a) to raise its pressure from said intermediate pressure to said high pressure of cycle.