Methods for the manufacture of fuel pellets and other products from lignocellulosic biomass

Abstract

The present invention is directed to a method for producing products, such as fuel pellets, from lignocellulosic biomass. Lignocellulosic biomass having a moisture content of less than about 30% by weight is introduced into a reactor. A vacuum of less than about 500 torr is applied to the reactor. Steam having a temperature of between about 180° C. and about 235° C. is injected into the reactor. The biomass is maintained in the reactor between about 1 and about 12 minutes. The treated biomass having a moisture content less than about 30% by weight is removed from the reactor. Treated biomass is formed into a pellet.

1 . A method for producing fuel pellets, comprising the steps of:
 introducing a lignocellulosic biomass having a moisture content of less than about 30% by weight into a reactor;   applying a vacuum to the reactor;   injecting steam having a temperature of between about 180° C. and about 235° C. into the reactor;   maintaining the biomass in the reactor between about 1 and about 12 minutes; and   removing the treated biomass from the reactor.   
     
     
         2 . The method of  claim 1  wherein less than about 50 weight % of a carbon source is added to the biomass. 
     
     
         3 . The method of  claim 2  wherein the carbon source is coal dust, coke powder, or unprocessed biomass. 
     
     
         4 . The method of  claim 1  wherein the biomass is dried to a moisture content of less than about 15% by weight before the material passes into the reactor. 
     
     
         5 . The method of  claim 1  wherein the vacuum applied to the reactor is less than 500 torr. 
     
     
         6 . The method of  claim 1  wherein the vacuum applied to the reactor is less than 200 torr. 
     
     
         7 . The method of  claim 1 , further comprising the step of introducing a catalyst into the reactor. 
     
     
         8 . The method of  claim 7  wherein the catalyst is a fatty acid, ester, or triglyceride. 
     
     
         9 . The method of  claim 7  wherein the catalyst is introduced prior to the steam. 
     
     
         10 . The method of  claim 7  wherein the catalyst is introduced together with the steam. 
     
     
         11 . The method of  claim 1  wherein the treated biomass has a moisture content less than about 30% by weight. 
     
     
         12 . The method of  claim 1 , further comprising the step of forming the treated biomass into a pellet. 
     
     
         13 . The method of  claim 12  wherein the treated biomass is extruded into the pellet with a compound extruder. 
     
     
         14 . A pellet used as a fuel source prepared by a process comprising the steps of:
 introducing a lignocellulosic biomass having a moisture content of less than about 30% by weight into a reactor;   applying a vacuum to the reactor;   injecting steam having a temperature of between about 180° C. and about 235° C. into the reactor;   maintaining the biomass in the reactor between about 1 and about 12 minutes; and   removing the treated biomass from the reactor.   
     
     
         15 . The method of  claim 14  wherein less than about 50 weight % of a carbon source is added to the biomass. 
     
     
         16 . The method of  claim 14  wherein the carbon source is coal dust, coke powder, or unprocessed biomass. 
     
     
         17 . The method of  claim 14  wherein the biomass is dried to a moisture content of less than about 15% by weight before the material passes into the reactor. 
     
     
         18 . The method of  claim 14  wherein the vacuum applied to the reactor is less than 500 torr. 
     
     
         19 . The method of  claim 14  wherein the vacuum applied to the reactor is less than 200 torr. 
     
     
         20 . The method of  claim 14 , further comprising the step of introducing a catalyst into the reactor. 
     
     
         21 . The method of  claim 20  wherein the catalyst is a fatty acid, ester, or triglyceride. 
     
     
         22 . The method of  claim 20  wherein the catalyst is introduced prior to the steam. 
     
     
         23 . The method of  claim 20  wherein the catalyst is introduced together with the steam. 
     
     
         24 . The method of  claim 14  wherein the treated biomass has a moisture content less than about 30% by weight. 
     
     
         25 . The method of  claim 14 , further comprising the step of forming the treated biomass into a pellet. 
     
     
         26 . The method of  claim 25  wherein the treated biomass is extruded into the pellet with a compound extruder.