| 摘要 |
1,254,968. Separating straight chain hydrocarbons by adsorption. TEXACO DEVELOPMENT CORP. 28 Oct., 1969 [31 Oct., 1968], No. 52643/69. Heading B1L. [Also in Division C5] Gaseous straight chain hydrocarbons are separated from a petroleum fraction, e.g. C 10 -C 20 , using a molecular sieve, e.g. Type 5A. e.g. sodium calcium aluminosilicate, in a cyclic vapour phase process which includes the steps of adsorption, purging and desorption, the latter two steps being carried out using the same medium, viz one comprising a straight chain hydrocarbon mixture composed of a major amount of at least one straight chain hydrocarbon having 5 to 7 carbon atoms less than the lightest straight chain hydrocarbon of the petroleum fraction, and a minor amount of a straight chain hydrocarbon having 1 to 3 carbon atoms less than the lightest straight chain hydrocarbon. Examples of the medium given are n-heptane and n-undecane. As shown a mixture of straight and non- straight hydrocarbons is fed from pipe 10 to adsorption tower 14 mounted at elevated temperature and pressure. The straight chain components are selectively adsorbed while effluent exits via pipe 16 to a fractionater 18. The non-straight hydrocarbons exit via line 21 whereas any desorbing medium (from a previous desorption step) is recycled via line 19. At the purge stage 14A the tower is depressurised and the adsorbent is purged countercurrently with desorbing medium added from lines 40, 42, 44. Purge effluent is collected in purge accumulator 54 before being recycled. At the desorption stage 14B the tower is repressurised above that used in the adsorption step and desorbing medium added via line 43. The effluent is separated by fractionator 60 into desorbing material which is recycled via line 62, and straight chain hydrocarbons which are collected via line 64. Three towers may be used or each stage may have more than one tower in parallel. |
