Removal of soluble components from tobacco material and apparatus therefore

Abstract

A multi-stage tobacco extraction process for removal of soluble components from tobacco material, wherein the tobacco material is sequentially substantially submerged in a solvent within a series of extraction tanks, which tanks are each inclined at a negative angle to the horizontal. The present invention also provides extraction apparatus comprising a plurality of inclined extraction tanks.

1 . A multi-stage process for removal of soluble components from tobacco material, wherein tobacco material is sequentially substantially submerged in a solvent within a series of inclined extraction tanks.  
   
   
       2 . A multi-stage process according to  claim 1 , wherein the tobacco material is sequentially substantially submerged in three extraction tanks.  
   
   
       3 . A multi-stage process according to  claim 1  or  claim 2 , wherein each of said extraction tanks is substantially filled with solvent.  
   
   
       4 . A multi-stage process according to  claim 1 , wherein the tobacco material is conveyed through each of said extraction tanks from an upstream to a downstream end of said extraction tank.  
   
   
       5 . A multi-stage process according to  claim 1 , wherein the solvent is sequentially supplied to said series of extraction tanks in a direction opposite to that of the flow of said tobacco material.  
   
   
       6 . A multi-stage process according to  claim 1 , wherein within each of said extraction tanks solvent and tobacco material flow in the same direction.  
   
   
       7 . A multi-stage process according to  claim 6 , wherein said solvent and said tobacco material, within each extraction tank, flow from an upstream to a downstream end of said extraction tank.  
   
   
       8 . A multi-stage process according to  claim 1 , wherein said tobacco material is continuously fed into a first extraction tank before undergoing sequential extraction in said first extraction tank, a second extraction tank and optionally a third extraction tank.  
   
   
       9 . A multi-stage process according to  claim 8 , wherein solvent is continuously fed into said third extraction tank (if present) and is sequentially fed from said third extraction tank into said second extraction tank and said first extraction tank.  
   
   
       10 . A multi-stage process according to  claim 1 , wherein the residence time of said tobacco material in each of said extraction tanks is between about 5 minutes and about 15 minutes.  
   
   
       11 . A multi-stage process according to  claim 10 , wherein said residence time is between about 5 minutes and about 10 minutes.  
   
   
       12 . A multi-stage process according to  claim 11 , wherein said residence time is about 5 minutes.  
   
   
       13 . A multi-stage process according to  claim 1 , wherein the solvent temperature in each of said extraction tanks is in the range of about 70° C. to about 95° C.  
   
   
       14 . A multi-stage process according to  claim 13 , wherein said solvent temperature is between about 80° C. and 85° C.  
   
   
       15 . A multi-stage process according to  claim 1 , wherein said solvent is selected from the group comprising water or water:alcohol mixtures.  
   
   
       16 . A multi-stage process according to  claim 1 , wherein the ratio of total mass flow rate of tobacco material to total mass flow rate of solvent in said series of extraction tanks is between about 1:2 and about 1:30.  
   
   
       17 . A multi-stage process according to  claim 16 , wherein said ration is between about 1:4 and about 1:20.  
   
   
       18 . A multi-stage process according to  claim 17 , wherein said ration is between about 1:4 and about 1:10.  
   
   
       19 . A multi-stage process according to  claim 1 , wherein said tobacco material is cut lamina, stem, dust or fines.  
   
   
       20 . A multi-stage process according to  claim 19 , wherein when said tobacco material is stem, the stem has a particle size of between about ⅞ inches (22 mm) and about 2 inches (51 mm).  
   
   
       21 . An extraction apparatus comprising a plurality of inclined extraction tanks, each extraction tank comprising an extraction housing, conveying means, tobacco material inlet and outlet means, and solvent inlet and outlet means.  
   
   
       22 . An extraction apparatus according to  claim 21 , wherein said apparatus comprises three extraction tanks.  
   
   
       23 . An extraction apparatus according to  claim 21  or  claim 22 , wherein each of said extraction tanks is inclined at a negative angle to the horizontal.  
   
   
       24 . An extraction apparatus according to  claim 23 , wherein said angle is up to about 5°.  
   
   
       25 . An extraction apparatus according to  claim 24 , wherein said angle is between about 30 and 40.  
   
   
       26 . An extraction apparatus according to  claim 21 , wherein said extraction housing is a hollow, substantially cylindrical tube.  
   
   
       27 . An extraction apparatus according to  claim 21 , wherein said conveying means is a screw conveyor.  
   
   
       28 . An extraction apparatus according to  claim 21 , wherein said conveying means is a conveying belt, which conveying belt comprises tobacco material retaining means.  
   
   
       29 . An extraction apparatus according to  claim 21 , wherein said conveying means is disposed within the extraction housing.  
   
   
       30 . An extraction apparatus according to  claim 27 , wherein said screw conveyor is axially aligned with the longitudinal axis of said extraction housing.  
   
   
       31 . An extraction apparatus according to  claim 27 , wherein said screw conveyor is rotatably mounted to said extraction housing.  
   
   
       32 . An extraction apparatus according to  claim 21 , wherein said tobacco inlet means is a hopper or a conveyor belt.  
   
   
       33 . An extraction apparatus according to  claim 21 , wherein said tobacco outlet means is at a downstream end of said extraction tank.  
   
   
       34 . An extraction apparatus according to  claim 33 , wherein said tobacco outlet means comprises dewatering means, by which means tobacco is removed from said extraction tank.  
   
   
       35 . An extraction apparatus according to  claim 34 , wherein said dewatering means is a dewatering screw.  
   
   
       36 . An extraction apparatus according to  claim 35 , wherein said dewatering screw extends into a dewatering means solvent tank, which dewatering means solvent tank forms an integral part of said extraction housing at the downstream end of said housing.  
   
   
       37 . An extraction apparatus according to anyone of claims  35 - 36 , wherein said dewatering screw comprises a hollow, helicoid screw operable to remove tobacco from said extraction tank.  
   
   
       38 . An extraction apparatus according to  claim 35 , wherein said dewatering screw is set at a positive angle to the horizontal such that, in operation, excess solvent flows back into said extraction tank whilst tobacco material is removed from said tank.  
   
   
       39 . An extraction apparatus according to  claim 34 , wherein said dewatering means further comprises a press at an end thereof, which end is distant from said extraction housing.  
   
   
       40 . An extraction apparatus according to  claim 21 , wherein each of said extraction tanks is provided with solvent recycling means.  
   
   
       41 . An extraction apparatus according to  claim 21 , wherein each of said extraction tanks comprises solvent outlet means, which outlet means are located such that solvent exits each extraction housing from the dewatering screw solvent tank.  
   
   
       42 . An extraction apparatus according to wherein the solvent outlet means of one extraction tank is joined to the solvent inlet means of the preceding tank via a solvent pipe.  
   
   
       43 . An extraction apparatus substantially as described hereinabove with reference to  FIGS. 1 and 2 .  
   
   
       44 . A multi-stage process substantially as described hereinabove with reference to Example 1.