Process for increasing a diesel recovery from a fractionation column

Abstract

A process for recovering diesel from fractionation column bottoms stream. The bottoms stream from the fractionation column is passed to a vacuum column. The vacuum column includes various packed sections which separate the diesel in the fractionation column bottoms from the other components. The diesel will rise as though the lower sections of the vacuum column, and most will condense in the upper section of the vacuum column. A recovered diesel from the vacuum column can be combined with the diesel recovered from the fractionation column. A venturi jet nozzle, such as a liquid jet eductor, can be used with a sidecut pumparound stream from the fractionation column as a motive fluid to achieve the desired operating pressure of the vacuum column.

What is claimed is: 
     
         1 . A process of increasing the yield of diesel from a fractionation column downstream of a hydroprocessing zone, the process comprising:
 separating a bottoms stream from a fractionation column in a vacuum column into a vapor stream, a diesel stream, and a bottoms stream;   removing the vapor stream from the vacuum column with an eductor;   compressing the vapor stream from the eductor to the fractionation column.   
     
     
         2 . The process of  claim 1  further comprising:
 separating a feed stream in the fractionation column into one or more transportation fuel streams and the bottoms stream. 
 
     
     
         3 . The process of  claim 1  further comprising:
 separating a feed stream in the fractionation column into at least a diesel stream and the bottoms stream. 
 
     
     
         4 . The process of  claim 3  further comprising:
 combining the diesel stream from the fractionation column with the diesel stream from the vacuum column. 
 
     
     
         5 . The process of  claim 1  further comprising:
 removing a sidedraw stream from the fractionation column; and, 
 passing the sidedraw stream through the eductor. 
 
     
     
         6 . The process of  claim 1  further comprising:
 heating the bottoms stream from the fractionation column. 
 
     
     
         7 . The process of  claim 6  wherein heating the bottoms stream from the fractionation column comprises:
 passing the bottoms stream from the fractionation column to a charge heater to provide a heated bottoms stream; and, 
 passing the heated bottoms stream to the vacuum column. 
 
     
     
         8 . The process of  claim 6  wherein heating the bottoms stream from the fractionation column comprises:
 heating the bottoms stream from the vacuum column in a reboiler to provide a heated vacuum bottoms stream; and, 
 passing the heated vacuum bottoms stream to the vacuum column. 
 
     
     
         9 . The process of  claim 1  further comprising:
 cooling a portion of the diesel stream from the vacuum column; and, 
 passing the cooled portion of the diesel stream back to the vacuum column. 
 
     
     
         10 . The process of  claim 1  further comprising:
 passing a first portion of the diesel stream one back to the vacuum column; and, 
 recovering a second portion of the diesel stream as a product stream. 
 
     
     
         11 . A process of increasing a yield of diesel from a fractionation column downstream of a hydroprocessing zone, the process comprising:
 separating a feed stream in a fractionation column into at least one naphtha stream, a diesel stream, and a bottoms stream;   separating the bottoms stream from the fractionation column in a vacuum column into a vapor stream, a diesel stream, and a bottoms stream, wherein vacuum column includes at least three packed sections and an inlet for the bottoms stream from the fractionation column disposed above a first packed section and below two other packed sections;   removing the vapor stream from the vacuum column with a venturi jet nozzle; and,   passing the vapor stream of the vacuum column from the eductor to the fractionation column.   
     
     
         12 . The process of  claim 11  further comprising:
 stripping diesel from the bottoms stream of the fractionation column in the vacuum column by passing steam into the vacuum column. 
 
     
     
         13 . The process of  claim 12  wherein an inlet in the vacuum column for the steam is disposed below the inlet for the bottoms stream from the fractionation column. 
     
     
         14 . The process of  claim 13  further comprising:
 passing a portion of the bottoms stream from the vacuum column to a reboiler to provide a heated vacuum column bottoms stream; and, 
 passing the heated vacuum column bottoms stream to the vacuum column. 
 
     
     
         15 . The process of  claim 14  wherein the vacuum column further comprises an inlet for the heated vacuum column bottoms stream disposed below the three packed beds in the vacuum column. 
     
     
         16 . The process of  claim 11  further comprising:
 heating the bottoms stream from the fractionation column in a charge heater to provide a heated bottoms stream; and, 
 passing the heated bottoms stream to the vacuum column. 
 
     
     
         17 . The process of  claim 11  wherein a motive fluid for the venturi jet nozzle comprises steam. 
     
     
         18 . The process of  claim 11  wherein a motive fluid for the venturi jet nozzle comprises a liquid stream from the fractionation column. 
     
     
         19 . The process of  claim 18  wherein the motive fluid for the venturi jet nozzle comprises a sidedraw pumparound stream from the fractionation column. 
     
     
         20 . The process of  claim 11  wherein a portion of the vapor stream from the vacuum column comprises diesel.