Processing biomass

Abstract

Biomass feedstocks (e.g., plant biomass, animal biomass, and municipal waste biomass) are processed to produce useful products, such as fuels. For example, systems are described that can convert feedstock materials to a sugar solution, which can then be fermented to produce a product such as a biofuel.

What is claimed is: 
     
         1 . A wet milling system comprising a tank with one or more jet heads and one or more wet mills disposed within the tank. 
     
     
         2 . The system of  claim 1  wherein the one or more wet mills comprise a head comprising a rotor and a stator. 
     
     
         3 . The system of  claim 2  wherein the rotor and the stator include nesting rings of teeth. 
     
     
         4 . The system of  claim 3  wherein the stator comprises two or more concentric rings of teeth. 
     
     
         5 . The system of  claim 2  wherein the clearance between the rotor and the stator is from about 0.01 to 0.25 inches (0.25 to 6.4 mm). 
     
     
         6 . The system of  claim 3  wherein the spacing between teeth in each ring of teeth is from about 0.1 to 0.3 inch (2.5 to 7.6 mm). 
     
     
         7 . A wet milling system comprising one or more jet heads and one or more wet milling heads in a tank comprising fluid having biomass dispersed therein. 
     
     
         8 . The system of  claim 7  wherein the biomass is selected from the group consisting of wood, particle board, sawdust, agricultural waste, sewage, silage, grasses, rice hulls, bagasse, cotton, jute, hemp, flax, bamboo, sisal, abaca, straw, wheat straw, corn cobs, corn stover, switchgrass, alfalfa, hay, coconut hair, seaweed, algae, and mixtures thereof. 
     
     
         9 . The system of  claim 8  wherein the agricultural waste is selected from the group consisting of: rice hulls, bagasse, straw, corn stover and coconut hair. 
     
     
         10 . The system of  claim 8  wherein the silage is alfalfa. 
     
     
         11 . The system of  claim 7  wherein the biomass comprises a lignocellulosic material. 
     
     
         12 . The system of  claim 11  wherein the recalcitrance of the lignocellulosic material has been reduced by irradiating the biomass. 
     
     
         13 . The system of  claim 12  wherein irradiating comprises exposing the biomass to an electron beam. 
     
     
         14 . The system of  claim 7  wherein the one or more wet milling heads comprise a rotor and a stator. 
     
     
         15 . The system of  claim 14  wherein the rotor and the stator include nesting rings of teeth. 
     
     
         16 . The system of  claim 15  wherein the stator comprises two or more concentric rings of teeth. 
     
     
         17 . The method of  claim 14  wherein the clearance between the rotor and the stator is from about 0.01 to 0.25 inches (0.25 to 6.4 mm). 
     
     
         18 . The method of  claim 15  wherein the spacing between teeth in each ring of teeth is from about 0.1 to 0.3 inch (2.5 to 7.6 mm).