Process for beneficiating and cleaning biomass

Abstract

A process for cleaning and beneficiating biomass is described which may allow removal of entrained salts and light volatiles from biomass materials. The process may also minimize energy use through capturing steam and flue gases for re-use. The process may generally comprise the following steps: prewashing and/or preheating a biomass, pressurizing the biomass in a steam explosion vessel, rapidly depressurizing the steam explosion vessel, releasing the steam from the steam explosion vessel entrained with fine lignin-enriched particles into a cyclone-type gas expansion vessel, routing the steam from the gas expansion vessel to the input hopper, subjecting the biomass to a second washing step, mechanically removing a portion of the water from the biomass, and evaporatively heating the biomass.

What is claimed is: 
     
         1 . A method for removing at least one of salts and light volatile organic compounds from a disrupted biomass, the method comprising the following steps:
 passing the disrupted biomass from the reaction vessel to a separate wash chamber; and   washing the disrupted biomass within the separate wash chamber to remove at least 5 percent of the salts derived from the disrupted biomass.   
     
     
         2 . The method of  claim 1 , wherein the step of washing the disrupted biomass comprises agitating the disrupted biomass with clean water in the separate wash chamber to contact the clean water with the biomass. 
     
     
         3 . The method of  claim 2 , wherein the step of agitating the disrupted biomass with clean water in the separate wash chamber comprises agitating by compressed air. 
     
     
         4 . The method of  claim 1 , wherein the step of washing the disrupted comprises removing at least 10 percent of at least one of the salts and light volatile organic compounds. 
     
     
         5 . The method of  claim 1 , wherein the step of washing the disrupted biomass comprises removing at least 20 percent of at least one of the salts and light volatile organic compounds. 
     
     
         6 . The method of  claim 1 , wherein the step of washing the disrupted biomass comprises removing at least 30 percent of the at least one of the salts and light volatile organic compounds. 
     
     
         7 . The method of  claim 1 , wherein the separate wash chamber comprises a dynamic trommel, and wherein the step of washing the disrupted biomass comprises contacting water with disrupted biomass being conveyed on an auger. 
     
     
         8 . The method of  claim 1 , wherein the steps are taken in the order presented. 
     
     
         9 . The method of  claim 1 , further comprising the step of mechanical drying through vibratory separation followed by compression in a screw press. 
     
     
         10 . The method of  claim 9 , further comprising the step of removing additional amounts of water in a continuous roller press to form a friable biomass from the disrupted biomass. 
     
     
         11 . The method of  claim 1 , wherein the reaction vessel comprises an inner perforated screen separating the biomass from the main body of the reaction vessel and one or more perforated screen fingers disposed within the reaction vessel and positioned within the biomass to increase exposure of the biomass to steam. 
     
     
         12 . The method of  claim 1 , wherein the salts and one or more light volatile organics are reduced by 80 to 98 percent of their starting concentrations in the biomass. 
     
     
         13 . The method of  claim 10 , further comprising the step of forming a pellet from the friable biomass. 
     
     
         14 . An apparatus for pretreating a biomass, the apparatus comprising:
 a reaction vessel for pressurizing and rapidly depressurizing a biomass within the reaction vessel,   wherein the reaction vessel comprises an inner perforated screen separating the biomass from a wall of the reaction vessel,   wherein the inner perforated screen further comprises one or more perforated screen fingers positioned within the biomass during pressurization of the biomass to increase exposure of the biomass to steam.   
     
     
         15 . The apparatus of  claim 14 , wherein the one or more perforated screen fingers are positioned away from a wall defining the reaction vessel. 
     
     
         16 . The apparatus of  claim 14 , further comprising a separate wash chamber, the separate wash chamber being apart from the reaction vessel. 
     
     
         17 . A system for pretreating a biomass before forming a pellet the system comprising:
 a reaction vessel comprising an inner perforated screen for separating the biomass from the main body of the reaction vessel; and   a separate washing container configured to remove at least one of salts and light volatile organic compounds derived from the biomass.   
     
     
         18 . The system of  claim 17 , further comprising a mechanical continuous water removal mechanism configured to remove water from the biomass to produce a biomass having less than about 50% water by weight; and
 an evaporative heating chamber configured to evaporatively remove an additional portion of the water from the biomass and produce a friable biomass, wherein the friable biomass comprises less than about 25% water by weight.   
     
     
         19 . The system of  claim 18 , further comprising a routing and fan-driven system for routing remaining volatile organic compounds to an air input of a boiler for incineration. 
     
     
         20 . The system of  claim 17 , further comprising one or more perforated screen fingers disposed within the reaction vessel and positioned within the biomass to increase exposure of the biomass to steam.