Abstract: A method and apparatus are disclosed relating to the recovery and reuse of heat during fractionation of liquids in a tray-type fractionating tower. According to this method, a portion of the feed to the tower is directed through heat exchange tubing positioned on the trays in such a way that the tubing is in contact with liquid there present so as to bring about an indirect exchange of heat between the said liquid on the trays and the liquid in the tubing, at the same time that there is occurring the normal transfer of heat by direct contact between the vapor and the liquid on the trays and the normal interchange of material components by direct contact between vapor and liquid on the trays, the said heat exchange tubing being serially connected so as to carry liquid from tray to tray.

Abstract: Volatile reactants are heated under reflux in a reactor and form volatile reaction by-products which are continuously removed in a vapor effluent from a reflux column and partial condenser. The effluent, which entrains some of the reactants, is condensed in a first total condenser and is fed to a distillation apparatus for separation of the volatile reactants and by-products and return of the separated reactants to the reactor. Before the condensate reaches the distillation apparatus, it is temporarily stored in a receiver from which it is controllably fed to a pre-heater where it is evaporated and then fed as a vapor to the distillation column of the distillation apparatus for separation. The distillation column includes at one end a reboiler which retains the reactants. The other end of the distillation column is coupled to a second total condenser in which the volatile by-products are condensed and withdrawn through a cooler for disposal.