Method for extracting biomass

Abstract

Method for extraction of biomass with water in order to separate hemicelluloses from a fibrous structure. The biomass is impregnated under reduced pressure with the extraction fluid in order to prevent the degradation of the components to be extracted. During extraction the extract is circulated through the fiber matrix in order to remove unwanted components from the extract. The extract is reused for extracting untreated biomass in order to increase the consistency of the extract.

1 . Method of treating biomass containing a fibrous structure and polysaccharides, comprising:
 subjecting the biomass to extractive treatment in which it is heated in aqueous phase at a pressure below 8 bar and at a temperature under 160° C., preferably at about 150° C., in order to separate the polysaccharides from the biomass;   characterized in that
 the biomass is impregnated with the extraction water under reduced pressure, of at least 0.3 bar under pressure, prior to extraction 
 keeping the oxygen gas level at a minimum throughout the extraction 
 by continuous recirculation of the extract through the biomass 
 the polysaccharide rich extract is separated from the biomass into a oxygen gas reduced environment as a first fraction 
 the fibrous structure of the biomass is recovered as a second fraction 
 the extract is reused for the extraction of un-extracted biomass 
 at least one of the fractions is subjected to further treatment. 
   
     
     
         2 . Method according to  claim 1 , where the carbohydrate extract is separated in the form of oligomers and polymers. 
     
     
         3 . Method according to  claim 2 , where the carbohydrate extract is hydrolyzed or used as food for microbes in the production of fuel or as raw material for chemical products. 
     
     
         4 . Method according to  claim 1 , where the fibrous fraction is subjected for the separation of lignin from the fibrous structure. 
     
     
         5 . Method according to  claim 1 , where the fibrous fraction is used for the production of paper and cardboard. 
     
     
         6 . Method according to  claim 1 , where the fibrous fraction is used for the production of pellets or as raw material for fuel. 
     
     
         7 . Method according to  claim 1 , where the fibrous fraction is used for the production of particle board (chipboard). 
     
     
         8 . Method according to  claim 1 , wherein the biomass is wood-based, in particular chips or sawdust, preferably crushed chips. 
     
     
         9 . Method according to  claim 1 , wherein the biomass is non-wood, in particular bagasse and straw.