System and method for densification of renewable coal replacement fuel

Abstract

A method may include heating biomass to generate torrefied biomass. The method may also include applying a liquid to the torrefied biomass in order to cool the torrefied biomass and increase moisture content of the torrefied biomass. The method may further include densifying the torrefied biomass into pieces having a second specific density greater than a first specific density of the torrefied biomass prior to densification.

What is claimed is: 
     
         1 . A system, comprising:
 a torrefaction reactor configured to heat biomass to generate torrefied biomass;   a stabilizer/conditioner configured to:
 receive the torrefied biomass from the torrefaction reactor; and 
 apply a liquid to the torrefied biomass in order to cool the torrefied biomass and increase moisture content of the torrefied biomass; and 
   a densifier configured to:
 receive the torrefied biomass from the stabilizer/conditioner; and 
 densify the torrefied biomass into pieces having a second specific density greater than a first specific density of the torrefied biomass upon receipt of the torrefied biomass by the densifier. 
   
     
     
         2 . A system according to  claim 1 , wherein the liquid is water. 
     
     
         3 . A system according to  claim 1 , wherein the application of the liquid to the torrefied biomass generates steam within the stabilizer/conditioner. 
     
     
         4 . A system according to  claim 1 , wherein the torrefaction reactor is configured to heat the biomass at a torrefaction temperature sufficient to torrefy the biomass without substantially devolatizing lignin present in the biomass. 
     
     
         5 . A system according to  claim 4 , wherein the torrefaction temperature is between approximately 230° C. and approximately 280° C. 
     
     
         6 . A system according to  claim 1 , the densifier configured to decrease moisture content of the torrefied biomass. 
     
     
         7 . A system according to  claim 1 , the densifier configured to heat the biomass to an operating temperature at or above a melting point of lignin present in the torrefied biomass. 
     
     
         8 . A system according to  claim 7 , wherein the operating temperature is between approximately 165° C. and approximately 190° C. 
     
     
         9 . A system according to  claim 1 , wherein the densifier comprises an extruder configured to densify the torrefied biomass into logs. 
     
     
         10 . A system according to  claim 9 , further comprising a first sizer configured to split the logs into pieces of random sizes. 
     
     
         11 . A system according to  claim 10 , further comprising a screen configured to separate pieces meeting a specification from pieces not meeting the specification. 
     
     
         12 . A system according to  claim 11 , further comprising a second size configured to resize pieces not meeting the specification to sizes meeting the specification. 
     
     
         13 . A method, comprising:
 heating biomass to generate torrefied biomass;   applying a liquid to the torrefied biomass in order to cool the torrefied biomass and increase moisture content of the torrefied biomass; and   densifying the torrefied biomass into pieces having a second specific density greater than a first specific density of the torrefied biomass prior to densification.   
     
     
         14 . A method according to  claim 13 , wherein the liquid is water. 
     
     
         15 . A method according to  claim 13 , wherein applying liquid to the torrefied biomass generates steam within the stabilizer/conditioner. 
     
     
         16 . A method according to  claim 13 , wherein heating the biomass comprises heating the biomass at a torrefaction temperature sufficient to torrefy the biomass without substantially devolatizing lignin present in the biomass. 
     
     
         17 . A method according to  claim 16 , wherein the torrefaction temperature is between approximately 230° C. and approximately 280° C. 
     
     
         18 . A method according to  claim 13 , wherein densifying the torrefied biomass comprises decreasing moisture content of the torrefied biomass. 
     
     
         19 . A method according to  claim 13 , wherein densifying the torrefied biomass comprises heating the biomass to an operating temperature at or above a melting point of lignin present in the torrefied biomass. 
     
     
         20 . A method according to  claim 19 , wherein the operating temperature is between approximately 165° C. and approximately 190° C. 
     
     
         21 . A method according to  claim 13 , wherein densifying the torrefied biomass comprises extruding the torrefied biomass into logs. 
     
     
         22 . A method according to  claim 21 , further comprising splitting the logs into pieces of random sizes. 
     
     
         23 . A method according to  claim 22 , further comprising screening to separate pieces meeting a specification from pieces not meeting the specification. 
     
     
         24 . A method according to  claim 23 , further comprising resizing pieces not meeting the specification to sizes meeting the specification. 
     
     
         25 . A system, comprising:
 a torrefaction reactor configured to heat biomass to generate torrefied biomass;   a densifier configured to:
 receive the torrefied biomass from the torrefaction reactor; and 
 apply a liquid to the torrefied biomass in order to cool the torrefied biomass and increase moisture content of the torrefied biomass; and 
 densify the torrefied biomass into pieces having a second specific density greater than a first specific density of the torrefied biomass upon receipt of the torrefied biomass by the densifier.