Liquid-liquid extraction tower having center feed inlet and process

Abstract

This invention relates to a liquid-liquid extraction tower comprising a feed inlet and a plurality of stages and an area for collection of the extract; at least one stage comprising a mixing zone having a driven center horizontal impeller positioned between a pair of horizontal annular shroud baffles having open centers, the impeller having a center impeller plate; wherein the feed inlet is positioned adjacent the center impeller plate. This invention also relates to an improved liquid-liquid extraction process comprising symmetrically introducing the feed adjacent the center impeller plate.

1 . A liquid-liquid extraction tower comprising:
 at least one feed inlet, at least one extraction solvent inlet, at least one extract outlet, and at least one raffinate outlet;   wherein the tower further has a plurality of stages and an area for collection of the extract;   at least one stage comprising a mixing zone having a driven center horizontal impeller positioned between a pair of horizontal annular shroud baffles having open centers, the impeller having a center impeller plate;   the stage further having openings between the pair of horizontal annular shroud baffles and the side of the tower;   wherein the feed inlet is positioned adjacent the center impeller plate.   
     
     
         2 . The liquid-liquid extraction tower of  claim 1 , wherein the vertical distance between the feed inlet and the center impeller plate is one inch or less. 
     
     
         3 . The liquid-liquid extraction tower of  claim 1 , wherein the feed inlet is a sparger having vertical and/or angled orifices. 
     
     
         4 . The liquid-liquid extraction tower of  claim 1 , wherein the feed inlet is a substantially vertically-oriented tube located on the centerline of the extraction tower. 
     
     
         5 . The liquid-liquid extraction tower of  claim 4 , wherein the vertical distance between the feed inlet and the center impeller plate is less than one feed inlet tube diameter. 
     
     
         6 . The liquid-liquid extraction tower of  claim 1 , wherein the feed inlet is two or more tubes symmetrically distributed around the centerline of the extraction tower. 
     
     
         7 . The liquid-liquid extraction tower of  claim 1 , wherein the feed inlet is two or more vertically-oriented tubes that are angled or bent toward either the center of the mixing zone or the horizontal impellers of the mixing zone. 
     
     
         8 . The liquid-liquid extraction tower of  claim 6 , wherein the vertical distance between the feed inlet and the center impeller plate is less than one feed inlet tube diameter. 
     
     
         9 . The liquid-liquid extraction tower of  claim 1 , wherein the mixing zone including the pair of shroud baffles is positioned between an additional set of annular flow baffles that direct flow from the side of the tower. 
     
     
         10 . In a process for liquid-liquid extraction of an extract from a feed using an extraction solvent, using a liquid-liquid extraction tower having at least one feed inlet, at least one extraction solvent inlet, at least one extract outlet, and at least one raffinate outlet;
 and wherein the tower further has a plurality of stages and an area for collection of the extract;   and at least one stage having a mixing zone having a driven center horizontal impeller positioned between a pair of horizontal annular shroud baffles having open centers, the impeller having a center impeller plate; the stage further having openings between the pair of horizontal annular shroud baffles and the side of the tower;   the improvement comprising symmetrically introducing the feed adjacent the center impeller plate.   
     
     
         11 . The process of  claim 10 , wherein the feed is introduced within one inch or less of the center impeller plate. 
     
     
         12 . The process of  claim 10 , wherein the feed is introduced within one feed inlet tube diameter of the center impeller plate. 
     
     
         13 . The process of  claim 10 , wherein the feed is introduced by use of a sparger having vertical and/or angled orifices; a vertical tube; or a plurality of vertically-oriented, angled, or bent tubes. 
     
     
         14 . The process of  claim 10 , wherein the feed is directed through the open center of one of the horizontal annular shroud baffles and into the annular inlet of the mixing zone. 
     
     
         15 . The process of  claim 14 , wherein the feed is symmetrically directed through the open center by use of a sparger having vertical and/or angled orifices; a vertical tube; or a plurality of vertically-oriented, angled, or bent tubes.