Method for producing fuel pellets and other lignocellulosic products with reduced hemicellulose, alkali metal and chlorine contents

Abstract

At least one embodiment of the disclosure is directed to a method of producing a lignocellulose-based product with reduced contents of hemicellulose, chlorine, sulfur and alkali and alkaline earth metals. A biomass having up to 60% by weight of moisture prior to steam treatment is steam treated. A lignocellulose-based product with reduced contents of hemicelluloses, chlorine, sulfur and alkali and alkaline metals is produced.

What is claimed: 
     
         1 . A method of producing pellets with reduced contents of hemicellulose, chlorine, sulfur and alkali and alkaline earth metals from a biomass material, comprising the steps of:
 providing a biomass having between 0% and 60% by weight of moisture into a reactor; and   injecting steam at a temperature of at least 300° F. into the reactor containing the biomass material;   maintaining a pressure for between 1 and 30 minutes; and   forming the treated biomass material having reduced contents of hemicelluloses, chlorine, sulfur and alkali and alkaline metals into pellets.   
     
     
         2 . The method of  claim 1  wherein the pressure is at least 52 psig. 
     
     
         3 . The method of  claim 1  further comprising:
 adding up to 8% by weight of a swelling agent for lignin during steam treatment to the biomass material. 
 
     
     
         4 . The method of  claim 3  wherein the swelling is added prior to injecting steam. 
     
     
         5 . The method of  claim 3  wherein the swelling agent has a boiling point greater than 100° C. 
     
     
         6 . The method of  claim 3  wherein the swelling agent is a fatty acid, a triglyceride, glycerol or a glycol. 
     
     
         7 . The method of  claim 1  further comprising:
 evacuating the reactor before injecting the steam. 
 
     
     
         8 . The method of  claim 7  wherein the reactor is evacuated such that the total free oxygen content of gas in the reactor is between 3% and 10% by volume. 
     
     
         9 . The method of  claim 1  further comprising:
 adding between 0% and 5% by weight of an acid catalyst to the biomass material. 
 
     
     
         10 . The method of  claim 8  wherein the acid catalyst has a boiling point of less than 200° C. 
     
     
         11 . The method of  claim 8  wherein the acid catalyst is added prior to injecting the steam. 
     
     
         12 . The method of  claim 1  further comprising:
 washing the pellets formed from the treated material. 
 
     
     
         13 . The method of  claim 12  further comprising:
 drying the washed pellets to less than 10% moisture by weight. 
 
     
     
         14 . The method of  claim 13  further comprising:
 adding between 3% and 20% by weight of an oil. 
 
     
     
         15 . The method of  claim 14  further comprising:
 compressing the treated material in a molding or extrusion process. 
 
     
     
         16 . The method of  claim 12  further comprising:
 adding between 3% and 20% by weight of an oil. 
 
     
     
         17 . The method of  claim 16  wherein the oil contains at least 20% by weight unsaturated fatty acid compounds. 
     
     
         18 . The method of  claim 1  further comprising:
 adding between 0% and 60% by weight of a brittle carbon source. 
 
     
     
         19 . The method of  claim 18  wherein the brittle carbon source is thermally degraded biomass. 
     
     
         20 . The method of  claim 1  wherein the surface temperature of the pellets is greater than 95° C.