Abstract: Improved operation of an LPG fractionating facility having a deethanizer, depropanizer and debutanizer is obtained by operating the deethanizer at a lower pressure than conventional, (e.g., less than 500 psig), thereby reducing the temperature of the deethanizer bottoms such that the debutanizer operated at greater than conventional pressure (e.g., over 100 psig) produces a mixed butane overhead at a higher temperature than the deethanizer bottoms whereby the mixed butane overhead is condensed and cooled by indirect contact with the deethanizer bottoms thereby heating the bottoms and supplying a substantial portion of the energy required for the fractionation in the deethanizer. The energy reduction for the three column system through the improved heat recovery system is 10% to 50% depending upon the feed composition.

Abstract: An n-butane/isobutane splitter is operated by compressing the isobutane overhead to increase its condensing temperature, using the compressed overhead to heat bottoms in a reboiler, which is operated to condense the overhead and cooling the condensed overhead to a temperature no lower than the temperature on the top tray of the splitter and no higher than 20.degree. F. above the temperature on the top tray, whereby the throughput of the splitter is increased by 10 to 20%.

Abstract: A propane-propylene splitter is operated by compressing the propylene overhead to increase its condensing temperature, using the compressed overhead to heat bottoms in a reboiler, which is operated to condense the overhead and remove a maximum amount of heat from the condensed overhead, additionally cooling the condensed overhead to a temperature no lower than the temperature on the top tray of the splitter and no higher than 15.degree. F. above the temperature on the top tray, whereby the throughput of the splitter is increased by 10 to 20%.