Apparatus for removing a contaminant from a solvent separation process

Abstract

The invention is a process and apparatus for removing a contaminant from an aromatic selective solvent. A feed stream comprising an aromatic hydrocarbon and a non-aromatic hydrocarbon is contacted with the aromatic selective solvent in an extractive distillation zone to produce a raffinate stream comprising the non-aromatic hydrocarbon, and a rich solvent stream comprising the aromatic hydrocarbon and the solvent. The rich solvent stream is separated in a second distillation zone to produce an extract stream comprising the aromatic hydrocarbon, and a lean solvent stream comprising the contaminant and the aromatic selective solvent. At least a portion of the lean solvent stream is washed with a non-aromatic hydrocarbon to produce a clean solvent stream, at least a portion of which is passed to at least one of the extractive distillation zone and the second distillation zone.

1 . An apparatus for removing a contaminant from a solvent separation process comprising:
 (a) an extractive distillation zone;   (b) a feed conduit providing fluid communication to the extractive distillation zone;   (c) a solvent conduit providing fluid communication to the extractive distillation zone;   (d) a raffinate conduit providing fluid communication from the extractive distillation zone;   (e) a rich solvent conduit providing fluid communication from the extractive distillation zone to a second distillation zone;   (f) an extract conduit providing fluid communication from the second distillation zone;   (g) a lean solvent conduit providing fluid communication from the second distillation zone to a lean solvent washing zone;   (h) a washing fluid conduit providing fluid communication to the lean solvent washing zone;   (i) a clean solvent conduit providing fluid communication from the lean solvent washing zone to the extractive distillation zone;   (j) a by-product conduit providing fluid communication from the lean solvent washing zone; and   
       wherein the raffinate conduit provides fluid communication to the lean solvent washing zone. 
     
     
         2 . The apparatus of  claim 1  wherein the lean solvent conduit further provides fluid communication to the extractive distillation zone. 
     
     
         3 . The apparatus of  claim 1  wherein the lean solvent washing zone comprises a counter-current extraction column having a lean solvent inlet in fluid communication with the lean solvent conduit; a washing fluid inlet in fluid communication with the washing fluid conduit; a clean solvent outlet in fluid communication with the clean solvent conduit; and a by-product outlet in fluid communication the by-product conduit; the washing fluid inlet being located below the lean solvent inlet. 
     
     
         4 . The apparatus of  claim 1  wherein the lean solvent washing zone comprises a mixing zone, a separation zone having a separation vessel, and a transfer conduit providing fluid communication from the mixing zone to the separation zone; the lean solvent conduit and the washing fluid conduit providing fluid communication to the mixing zone; and the clean solvent conduit and the by-product conduit providing fluid communication from the separation zone. 
     
     
         5 . The apparatus of  claim 4  wherein the mixing zone comprises a static in-line mixer. 
     
     
         6 . The apparatus of  claim 4  wherein the separation vessel contains a solid media. 
     
     
         7 . The apparatus of  claim 1  further comprising a by-product washing zone, the by-product conduit providing fluid communication to the by-product washing zone; a second solvent conduit providing fluid communication to the by-product washing zone; a second by-product conduit providing fluid communication from the by-product washing zone; and an aqueous solvent conduit providing fluid communication from the by-product washing zone. 
     
     
         8 . The apparatus of  claim 7  wherein the aqueous solvent conduit provides fluid communication to at least one of the extractive distillation zone and the second distillation zone. 
     
     
         9 . The apparatus of  claim 7  wherein the by-product washing zone comprises a second counter-current extraction column having a by-product inlet in fluid communication with the by-product conduit; a second solvent inlet in fluid communication with the second solvent conduit; an aqueous solvent outlet in fluid communication with the aqueous solvent conduit; and a second by-product outlet in fluid communication the second by-product conduit; the by-product inlet being located below the second solvent inlet. 
     
     
         10 . The apparatus of  claim 7  wherein the by-product washing zone comprises a second mixing zone, a second separation zone having a second separation vessel, and a second transfer conduit providing fluid communication from the second mixing zone to the second separation zone; the by-product conduit and the second solvent conduit providing fluid communication to the second mixing zone; and the aqueous solvent conduit and the second by-product conduit providing fluid communication from the second separation zone. 
     
     
         11 . The apparatus of  claim 10  wherein the second mixing zone comprises a second static in-line mixer. 
     
     
         12 . The apparatus of  claim 10  wherein the second separation vessel contains a second solid media. 
     
     
         13 . The apparatus of  claim 7  further comprising a first water conduit providing fluid communication from the extractive distillation zone to the by-product washing zone. 
     
     
         14 . The apparatus of  claim 13  wherein the extractive distillation zone further comprises a water separation zone, the water separation zone comprising an inlet, a first outlet, and a second outlet; the inlet being in fluid communication with a extractive distillation column, the first outlet providing fluid communication to the first water conduit, and the second outlet providing fluid communication to the raffinate conduit. 
     
     
         15 . The apparatus of  claim 14  wherein the water separation zone comprises an overhead receiver. 
     
     
         16 . The apparatus of  claim 7  further comprising a second water conduit providing fluid communication from the second distillation zone to the by-product washing zone. 
     
     
         17 . The apparatus of  claim 16  wherein the second distillation zone further comprises a second water separation zone, the second water separation zone comprising an inlet, a first outlet, and a second outlet; the inlet being in fluid communication with a second distillation column, the first outlet providing fluid communication to the second water conduit, and the second outlet providing fluid communication to the extract conduit. 
     
     
         18 . The apparatus of  claim 17  wherein the second water separation zone comprises an overhead receiver. 
     
     
         19 . An apparatus for removing a contaminant from a solvent separation process comprising:
 (a) an extractive distillation zone;   (b) a feed conduit providing fluid communication to the extractive distillation zone;   (c) a solvent conduit providing fluid communication to the extractive distillation zone c) a solvent conduit providing fluid communication to the extractive distillation zone;   (d) a raffinate conduit providing fluid communication from the extractive distillation zone;   (e) a rich solvent conduit providing fluid communication from the extractive distillation zone to a second distillation zone;   (f) an extract conduit providing fluid communication from the second distillation zone;   (g) a lean solvent conduit providing fluid communication from the second distillation zone to a lean solvent washing zone;   (h) a washing fluid conduit providing fluid communication to the lean solvent washing zone;   (i) a clean solvent conduit providing fluid communication from the lean solvent washing zone to the extractive distillation zone;   (j) a by-product conduit providing fluid communication from the lean solvent washing zone to a by-product washing zone;   (k) a second solvent conduit providing fluid communication to the by-product washing zone;   (l) a second by-product conduit providing fluid communication from the by-product washing zone;   (m) an aqueous solvent conduit providing fluid communication from the by-product washing zone; and   
       wherein the aqueous solvent conduit provides fluid communication to the extractive distillation zone.