Abstract Closely boiling hydrocarbon mixtures in which one of the components forms a solid phase, e.g. crystals, preferably xylene and/or ethylbenzene mixtures, are separated by providing a threephase zone. One of the phases comprises the crystals of desired product. Another phase is organic material from which the crystals have separated; and the third phase is an immiscible phase. The material constituting the immiscible phase is chosen so that it is lighter than the crystals but heavier than the remaining organic component. Moreover, it must be able to withstand crystallization itself at the subzero temperatures utilized to form the organic crystals. Specifically, paraxylene is separated from a mixture of xylene isomers utilizing water plus methyl alcohol or water plus methyl alcohol plus glycol as the immiscible phase.
A process according to claim 1 wherein said crystals are concentrated by centrifugal force and whereby mother liquor is not forced through said concentrated crystals.
Claim 2
Dependent Claim
16 words
A process according to claim 2 wherein said centrifugal force is applied within a disc-type centrifuge.
Claim 3
Dependent Claim
17 words
A process according to claim 2 wherein said centrifugal force is applied in a solid-bowl type centrifuge.
Claim 4
Dependent Claim
12 words
A method according to claim 1 wherein said alcohol is methyl alcohol.
Claim 5
Dependent Claim
12 words
A method according to claim 1 wherein said polyol is ethylene glycol.
Claim 6
Dependent Claim
12 words
A process according to claim 1 wherein said polyol is propylene glycol.
Claim 7
Dependent Claim
20 words
A process according to claim 1 wherein the density of the mother liquor is controlled by the addition of pentene.
Claim 8
Dependent Claim
20 words
A process according to claim 1 wherein the density of the mother liquor is controlled by the addition of ethylene.