Torrefaction systems and methods including catalytic oxidation and/or reuse of combustion gases directly in a torrefaction reactor, cooler, and/or dryer/preheater

Abstract

A method for torrefying biomass comprises using an oxidation catalyst to combust gas produced by torrefaction, and thereby produce combustion flue gas. The method also comprises introducing the combustion flue gas into a torrefaction reactor and/or a cooler.

What is claimed is: 
     
         1 . A method relating to biomass torrefaction, the method comprising:
 producing combustion gases, which includes using an oxidation catalyst; and   introducing the resultant combustion gases into a torrefaction reactor.   
     
     
         2 . The method of  claim 1 , wherein the method includes using the resultant combustion gases introduced into the torrefaction reactor to support direct heating and/or torrefying of the biomass in the torrefaction reactor. 
     
     
         3 . The method of  claim 1 , wherein the method includes introducing the resultant combustion gases into the torrefaction reactor such that the resultant combustion gases contact the biomass in the torrefaction reactor. 
     
     
         4 . The method of  claim 1 , wherein the method includes:
 introducing the resultant combustion gases into the torrefaction reactor such that the resultant combustion gases contact the biomass in the torrefaction reactor, and thereby support direct heating and/or torrefying of the biomass in the torrefaction reactor; and/or   introducing the resultant combustion gases into a cooler such that the resultant combustion gases contact torrefied biomass in the cooler, and thereby support direct cooling of the torrefied biomass in the cooler; and/or   introducing the resultant combustion gases into a dryer/preheater such that the resultant combustion gases contact biomass in the dryer/preheater, and thereby support direct preheating, extraction of moisture, and/or drying of the biomass in a dryer/preheater; and/or   using the resultant combustion gases in a condensation jacket of a dryer/preheater to support indirect heating of biomass in the dryer/preheater.   
     
     
         5 . The method of  claim 1 , wherein producing combustion gases includes:
 using an oxidation catalyst that provides a low residual-oxygen flue gas stream usable directly in the torrefaction reactor; and/or   using a fixed-bed catalyst for low-temperature oxidation of torrefaction byproducts.   
     
     
         6 . The method of  claim 1 , wherein the resultant combustion gases flow countercurrent to the biomass in the torrefaction reactor. 
     
     
         7 . The method of  claim 1 , wherein the resultant combustion gases introduced into the torrefaction reactor comprise a combination of superheated steam from process moisture, superheated steam and carbon dioxide which are byproducts of catalytic oxidation combustion, and residual nitrogen from combustion air. 
     
     
         8 . A method relating to biomass torrefaction, the method comprising:
 producing combustion gases, which includes using an oxidation catalyst; and   introducing the resultant combustion gases into a cooler.   
     
     
         9 . The method of  claim 8 , wherein the method includes using the resultant combustion gases introduced into the cooler to support direct cooling of torrefied biomass in the cooler. 
     
     
         10 . The method of  claim 8 , wherein the method includes introducing the resultant combustion gases into the cooler such that the resultant combustion gases contact the torrefied biomass in the cooler. 
     
     
         11 . The method of  claim 8 , wherein the method includes:
 introducing the resultant combustion gases into the cooler such that the resultant combustion gases contact the torrefied biomass in the cooler, and thereby support direct cooling of the torrefied biomass in the cooler; and/or   introducing the resultant combustion gases into a torrefaction reactor, such that the resultant combustion gases contact biomass in the torrefaction reactor, and thereby support direct heating and/or torrefying of the biomass in the torrefaction reactor; and/or   introducing the resultant combustion gases into a dryer/preheater such that the resultant combustion gases contact biomass in the dryer/preheater, and thereby support direct preheating, extraction of moisture, and/or drying of the biomass in a dryer/preheater; and/or   using the resultant combustion gases in a condensation jacket of a dryer/preheater to support indirect heating of biomass in the dryer/preheater.   
     
     
         12 . The method of  claim 8 , wherein producing combustion gases includes using an oxidation catalyst that produces an inert gas stream that allows integration of the cooler with a torrefaction reactor; and wherein the cooler and the torrefaction reactor are integrated into a single unit that includes both the cooler and the torrefaction reactor. 
     
     
         13 . The method of  claim 8 , wherein producing combustion gases includes:
 using an oxidation catalyst that provides low residual-oxygen combustion gases usable directly in the cooler for safely cooling hot torrefaction products in the cooler; and/or   using a fixed-bed catalyst for low-temperature oxidation of torrefaction byproducts.   
     
     
         14 . The method of  claim 8 , wherein the method includes recovery of heat from the cooler such that heat integration is improved by direct use of low residual-oxygen combustion gases resulting from catalytic oxidation of torrefaction byproducts. 
     
     
         15 . The method of  claim 8 , wherein the resultant combustion gases flow countercurrent to the biomass in the cooler. 
     
     
         16 . A system for biomass torrefaction comprising a catalyst system including an oxidation catalyst, whereby resultant combustion gases produced thereby are directly reusable by the system to support torrefaction of biomass and/or to support cooling of torrefied biomass. 
     
     
         17 . The system of  claim 16 , wherein:
 the catalyst system comprises a fixed-bed catalyst system operable for low-temperature, low residual oxygen catalytic oxidation of the resultant combustion gases; and/or   the oxidation catalyst of the catalyst system comprises a platinum/palladium catalyst.   
     
     
         18 . The system of  claim 16 , further comprising:
 a torrefaction reactor configured to receive the resultant combustion gases to thereby support direct heating and/or torrefying of the biomass in the torrefaction reactor;   a dryer/preheater configured to receive the resultant combustion gases to thereby support direct preheating, extraction of moisture, and/or drying of the biomass; and   a cooler configured to receive the resultant combustion gases to thereby support direct cooling of torrefied biomass in the cooler.   
     
     
         19 . The system of  claim 18 , wherein:
 the system is configured such that resultant combustion gases flow countercurrent to biomass in the torrefaction reactor, the dryer/preheater, and the cooler; and/or   the dryer/preheater includes a condensation jacket configured to receive the resultant combustion gases to support indirect heating of biomass in the dryer/preheater.   
     
     
         20 . The system of  claim 16 , wherein:
 the system further comprises a fluidized-bed torrefaction reactor configured such that the biomass flows downward through the torrefaction reactor by gravity without requiring pneumatic or mechanical conveying of the biomass and such that the resultant combustion gases flow countercurrent to the biomass; and/or   the system further comprises an integrated unit including a torrefaction reactor and a cooler; and/or   the system is operable for selectively producing torrefied biomass or non-torrefied biomass.