Abstract A process for prefractionation of a feed mixture comprised of at least two components prior to introduction to the main fractionation zone, wherein substantially liquid feed maintained at pressures higher than that prevailing in the fractionation zone is cooled by indirect heat exchange, part or all of said cooled feed is flashed at a pressure at least above that of the fractionation zone, to produce flashed material having a liquid phase and vapor phase. The refrigeration potential of the flashed material is utilized for cooling of the feed by indirect heat exchange with a liquid or mixed phase portion of said flashed material thereby increasing the vapor-to-liquid ratio of the latter prior to its introduction to the fractionation zone at a suitable point. Remaining feed is introduced to the fractionation zone at one or more other suitable points. Preferred feeds disclosed are nitrogen-containing mixtures, such as mixtures comprising nitrogen and methane, nitrogen and argon, nitrogen, methane and argon. A specific example is included as to the application of the invention to the separation of the individual components of an ammonia synthesis purge gas and to the recovery of argon in either liquid or gaseous form.
In a process for the fractionation of a feed mixture of at least two components, the method of prefractionation of at least part of the feed mixture prior to its introduction to the fractionation zone, which comprises: cooling in a heat exchange zone a portion of the feed mixture; reducing the pressure of said portion of feed mixture to at least that of the fractionation zone; feeding said portion of feed mixture to the fractionation zone; flashing the remaining portion of the feed mixture at a pressure at least above that of the fractionation zone to obtain a vapor phase and a liquid phase; withdrawing a portion of said liquid phase; vaporizing at least part of the portion of said liquid phase by indirect heat exchange with the portion of the feed mixture cooling in said heat exchange zone; feeding the at least partially vaporized portion of said liquid phase to the fractionation zone; feeding the portion remaining liquid of said liquid phase to the fractionation zone; and feeding the vapor phase to the fractionation zone.
Claim 2
Dependent Claim
176 words
In a process for the fractionation of a feed mixture of at least two components, the method of prefractionation of at least part of the feed mixture prior to its introduction to the fractionation zone, which comprises: cooling in a heat exchange zone a portion of the feed mixture; reducing the pressure of said portion of feed mixture to at least that of the fractionation zone; feeding said portion of feed mixture to the fractionation zone; flashing the remaining portion of the feed mixture at a pressure at least above that of the fractionation zone to obtain a vapor phase and a liquid phase; withdrawing a portion of said liquid phase; vaporizing at least part of the portion of said liquid phase by indirect heat exchange with the portion of the feed mixture cooling in said heat exchange zone; feeding the at least partially vaporized portion of said liquid phase to the fractionation zone; feeding the portion remaining liquid of said liquid phase to the fractionation zone; and feeding the vapor phase to the fractionation zone.
Claim 3
Dependent Claim
16 words
A process according to claim 1, in which one component of the feed mixture is nitrogen.
Claim 4
Dependent Claim
16 words
A process according to claim 1, in which one component of the feed mixture is methane.
Claim 5
Dependent Claim
16 words
A process according to claim 1, in which one component of the feed mixture is argon.