in order to describe the invention in greater detail , reference is made to the accompanying schematic drawing . fig2 illustrates the invention in conjunction with a multi - stage condensation procedure . all values mentioned are calculated or exemplary . moreover , the invention will be described with use of a partitioned accumulation zone , although those skilled in the art will recognize that a non - partitioned zone may be employed . more particularly , numeral ( 1 ) designates a distillation column , preferably a fractionating column for a naphtha top product . the feed e . g ., crude oil , enters column ( 1 ) through line ( 2 ), and is fractionated in a known fashion . various draw - offs are provided ( not shown ), and overhead vapor exits column ( 1 ) through line ( 3 ) at a temperature of about 340 ° f . the overhead vapor is divided at ( 4 ) into major and minor portions , the major portion proceeding through line ( 5 ) to condenser ( 6 ). a minor portion , in this case about 10 percent by weight , based on the total weight of the overhead fraction , is removed via line ( 7 ), a more fully discussed hereinafter . in condenser ( 6 ) the bulk of the major portion is condensed . for purposes of this illustration , the overhead is assumed to have a condensation range of about 200 ° f ., e . g ., to condense between about 340 ° f . and 140 ° f . at column operating pressure . the amount condensed is that sufficient to provide reflux for column ( 1 ) and adequate product recovery . those skilled in the art may readily determine the amount to be condensed to satisfy these requirements . any suitable type of condenser or heat exchange system may be employed , as will also be evident to those skilled in the art . preferably , the vapor may be partially condensed , either by indirect heat exchange with another process stream , by air cooling , or by direct contact with condensate that has been cooled by exchange . from unit ( 6 ), the vapor - liquid stream is passed through line ( 8 ) to the separator ( 9 ). in separator ( 9 ) vapor and liquid are separated , vapor either being passed overhead ( dotted line ) or being forwarded via line ( 10 ) to a contactor ( 11 ). unit ( 6 ) may also be operated as a total condenser in which case the stream in line ( 8 ) is all liquid and there is no vapor flow from separator ( 9 ). a minor portion of liquid [ say 10 percent by weight , based on the total weight of liquid condensed in unit ( 6 )] is forwarded via line ( 12 ) to contactor ( 11 ), the remainder passing via line ( 13 ) to an accumulation zone ( 14 ). the external design of accumulating zone ( 14 ) may vary considerably , but preferably the accumulation zone is provided with a barrier ( 15 ) which divides the zone into two separate liquid - containing sections . at the same time , barrier ( 15 ) is constructed so that it does not limit vapor flow in accumulating zone ( 14 ). accordingly , the liquid stream in line ( 13 ) enters accumulating section ( a ) formed by the walls of unit ( 14 ) and barrier ( 15 ). if a second liquid phase is likely to be present , such as water , barrier ( 15 ) should be constructed so that the lower phase does not accumulate . alternatively , a separate drawoff can be provided for lower phase from accumulation section ( a ). the minor portion of vapor , in line ( 7 ), is fed to section ( a ) of accumulator ( 14 ) by means of sparging devices . therein , by means of the sparging devices , the vapor exchanges heat with the liquid in section ( a ), raising the temperature thereof to about 160 ° f . vapor is free to occupy the entire open volume of unit ( 14 ). liquid from section ( a ) may overflow barrier ( 15 ) to section ( b ) of unit ( 14 ), and reflux is returned via line ( 16 ) to column ( 1 ). product may also be removed via line ( 16 ), or may be removed separately from accumulation zone ( 14 ). vapor from zone ( 14 ) is passed through line ( 17 ) to vent contactor ( 11 ). contactor ( 11 ) serves to absorb and condense additional components from the vapor in lines ( 10 ) and ( 17 ). contactor ( 11 ) may be of any suitable type , but is preferably a small tray contactor having , e . g ., 3 to 5 trays . the vapor leaving contactor ( 11 ) suitably has a temperature only slightly higher than the liquid feed to the contactor . as illustrated , the liquid recovered in contactor ( 11 ) i . e ., condensate , passes or flows to , and collects , via line ( 18 ), in the accumulating section ( b ) of zone ( 14 ) through a sealed dip leg ( 19 ) to counterbalance the pressure drop of vapor flowing between accumulation zone ( 14 ) and contactor ( 11 ). any &# 34 ; non - condensables &# 34 ; from vent contactor ( 11 ) may be processed by conventional techniques via line ( 20 ). while a minor portion of the vapor in the open space above section ( b ) will condense , such condensation is not of major significance . in fig2 similar numbers represent similar features . as illustrated , the procedure of fig2 employs the accumulator or accumulation techniques of my aforementioned patent , although this is not critical , and adds a third section in the accumulator . accordingly , the feed enters column ( 1 ) through line ( 2 ), and is fractionated in a manner known to those skilled art . the overhead vapor fraction in line ( 3 ), at a temperature of about 380 ° f . ( hotter than for fig1 because of staged condensing ) is condensed in condensation zone ( 30 ), preferably in a series of condensation stages . for example , condensation zone ( 30 ) may comprise shell and tube heat exchangers wherein a colder process stream is heated . preferably , the overhead fraction is cooled to about 340 ° f ., thus providing sufficient condensate to reflux column ( 1 ). those skilled in the art may readily determine the amount to be condensed for adequate reflux of the distillation column . from the last stage , a liquid vapor stream is forwarded via line ( 31 ) to separation zone ( 32 ) where vapor and liquid are separated . separation zone ( 32 ) may comprise merely an enlarged section of line , a centrifugal separator , or other well - known means for separating vapor and liquid . separation zone ( 32 ) may be incorporated into the last condensation stage . liquid is removed from zone ( 32 ) via line ( 33 ), and is forwarded to accumulator ( 34 ). accumulator ( 34 ) may vary considerably in external design , but follows generally the principles describe in u . s . pat . no . 4 , 235 , 706 . more particularly , accumulator ( 34 ) is provided with barriers ( 35 ) and ( 36 ) which divide the accumulator into three separate liquid - containing sections , there being only limited liquid communication between the sections , as will be illustrated later . at the same time , barriers ( 35 ) and ( 36 ) are constructed so that they do not limit vapor flow in accumulating zone ( 34 ). accordingly , the liquid stream in line ( 33 ) enters accumulating zone ( 34 ), as shown , where it settles in accumulation section ( a ) formed by the walls of unit ( 34 ) and barrier ( 36 ). vapor may occupy the entire open volume of unit ( 34 ). the temperature of liquid in section ( a ) will be about 340 ° f . liquid from section ( a ) may be returned via line ( 37 ) to column ( 1 ) to provide the reflux mentioned previously . vapor from zone ( 34 ) may be passed through line ( 17 ) to vent contactor ( 11 ). concomitantly , the vapor removed in separator ( 32 ) is divided , in line ( 28 ) into major and minor portions . the major portion proceeds to condensation zone ( 6 ) via line ( 5 ). a minor portion , which represents about 10 percent of the total vapor , is removed via line ( 7 ) , a more fully discussed hereinafter . in condensation zone ( 6 ) the bulk of the major portion is condensed . for purposes of this illustration , the vapor to condensation zone ( 6 ) is assumed to have a condensation range of about 200 ° f ., i . e ., to condense between about 340 ° f . and 140 ° f . at column operating pressure . the amount condensed is approximately equal to the top product flow while at the same time providing for enhanced heat recovery of the energy utilized in the distillation . condensation units and techniques similar to those illustrated in connection with fig1 may be employed , as will be evident to those skilled in the art . from zone ( 6 ), the vapor - liquid stream is passed through line ( 8 ) to separation zone ( 9 ). as discussed in relation to fig1 vapor and liquid are separated in separator ( 9 ), vapor being passed overhead ( dotted line ) or forwarded via line ( 10 ) to contactor ( 11 ). as also discussed , the stream from condenser ( 6 ) may be all liquid and vapor flow in line ( 10 ) would then be zero . a minor portion of liquid [ 10 percent by weight , based on the total weight of liquid condensed in unit ( 6 )] is forwarded via line ( 12 ) to contactor ( 11 ), the remainder passing via line ( 13 ) to section ( c ) of accumulation zone ( 34 ). liquid from ( 13 ) accumulates in section ( c ), and liquid from ( 18 ) and ( 19 ) collects in section ( b ). vapor in line ( 7 ) is forwarded to section ( c ) of accumulator ( 34 ), where it is sparged into the liquid . barrier ( 35 ) functions in a manner similar to that of barrier ( 15 ) in fig . ( 1 ). the barrier ( 36 ) separating zone ( 34 ) into sections ( a ) and ( b ) is limited so that the sections have open vapor communication to allow vapor flow and pressure equalization between the sections . preferably , barrier ( 36 ) is provided further with an opening ( 37 ) near or at the bottom thereof , as described in my aforementioned patent , for liquid level balance and for flow of heavy second liquid phase to a boot for separate drawoff . the size of the opening is determined by the volumes of liquid to be balanced , keeping in mind that significant mixing of the liquids in sections ( a ) and ( b ) is not desired . the &# 34 ; opening &# 34 ; may , as will be understood by those skilled in the art , be a multiplicity of smaller openings , the total cross - sectional area of the openings being such as to fulfill the requirements noted . barrier ( 36 ) may be constructed of any suitable impermeable material , such as steel or ceramic , and the opening ( if present ) should be baffled to prevent convection flow . as will be recognized by those skilled in the art , the key to the invention is the contacting of a cool liquid portion of the overhead with the warmer vapor portion of the overhead . this permits operation of the product - containing sections of the accumulator at a higher temperature , and less heat will be required for further processing of the top - product . the detailed description exemplifies a column overhead vapor composed of a mixture of compounds of differing boiling points , so that there is a temperature spread between the bubble and dew points of the mixture . the invention is most advantageously applied to such a mixture , particularly in the arrangement of fig2 . however , it is also useful , as noted , for the distillation of mixtures producing pure or nearly pure compound as top product . it is not practical to operate the condenser of such a column to produce liquid product at its bubble point without loss of some product as vapor . therefore , out of practical necessity , condensers of such columns are operated to subcool the product to prevent this loss of vapor . use of this invention will allow the reheating of product to the bubble point without vapor loss .