| 摘要 |
996,929. Cold separation of gas mixtures. SOC. D'ETUDES DU TRANSPORT ET DE LA VALORISATION DES GAZ NATURELS DU SARAHA S.E.G.A.N.S. April 1, 1963 [April 5, 1962], No. 12766/63. Heading F4P. A process for separating a liquefied natural hydrocarbon gas mixture containing volatile inert gases such as nitrogen and helium into a sub-cooled liquid fraction and into a gaseous combustible fraction comprises expanding feed liquid from lines 1, 2, Fig. 1, into a flask B 1 , withdrawing the liquid fraction so produced through a line 3 and sub-cooling it in exchangers E 2 , E 3 arranged in cascade, withdrawing the combustible gaseous fraction through a line 6 and partially condensing it in exchangers E 5 , E 6 also arranged in cascade followed by further cooling the product liquid fraction and liquefying the combustible fraction in exchangers E 4 , E 7 cooled by a return flow of liquid combustion gas after expansion at a valve in a line 8; product liquid fraction being withdrawn through a line 5 and product combustion gas containing inert gas being withdrawn through a line 9. As shown, liquid feed in line 1 is sub-cooled in an exchanger E 1 which forms the high pressure stage of a threestage methane refrigerant cycle, the medium and low pressure stages of which comprise exchangers E 2 , E 5 and E 3 , E 6 respectively. The inert volatile gas content of the liquid hydrocarbon product may be reduced by substituting a column V 1 , Fig. 4, in place of the flask B 1 and inert gases are separated from the combustible gas in line 6 by means of a separating column V 2 from which liquefied combustible gas is withdrawn through a line 10 and after being sub-cooled in cascade exchanger E 6 and in exchangers E 7a , E 7b in counterflow to expanded gas the latter is discharged as product through line 9. A portion of liquid combustion gas leaving exchanger E 7b through line 8 is diverted along a line 11 and cools the head of column V 2 from which inert gases are withdrawn through a line 13 and are passed through a molecular sieve 14. The carbon-dioxide content of the mixture of liquid hydrocarbons withdrawn from the base of column V 1 through line 3 and having been sub-cooled in exchanger E 2 is removed by expansion into flasks B 3 , B 4 , Fig. 6 (not shown) having filter screens therein. |
