DUAL TEMPERATURE EXCHANGE SYSTEMS

摘要

The present invention provides in a method for producing a fluid containing a first material concentrated therein, by exchanging at two different temperatures said first material with a second material between chemically different first and second fluid phases which are physically separable from each other and which are each capable of containing each of said materials, said method being of the type in which said second fluid phase is passed through each of the second and first units, in that order, of a pair of exchange units, and in which flows said first fluid phase are passed in countercurrent contact with said second fluid phase in said first and second units of said pair, said first and second units being maintained at different temperatures to cause said second fluid phase to become enriched in said first material in passing through said second unit, and to become impoverished in said first material in passing through said first unit of said pair, and to cause the first fluid phase to become enriched in said first material in passing through said first unit and to become impoverished in said first material in passing through said second unit of said pair of units, and in which a part of at least one of the enriched fluids passing between said units is withdrawn; the improvement which comprises: delivering a first flow of said first fluid phase containing said materials from a source thereof and passing said flow in countercurrent exchange with said impoverished second fluid in a first delivery-to-discharge path through a portion only of said second unit proximate to its end at which said fluids are most impoverished in said first material, and passing a second flow of first fluid phase in a second delivery-to-discharge path in countercurrent exchange with said second fluid phase in other portions of said first unit and second unit of said pair of units and as an enriched flow between said units, said second flow of first fluid phase being at least in part a cyclic flow recirculated from said second unit to said first unit.