Torrefaction Process

Abstract

A process for producing compacted torrefied biomass from pre-processed biomass. The process includes drying the pre-processed biomass in a dryer with heater exhaust gas from a heater, yielding dried biomass; torrefying the dried biomass with heat generated by the heater; compacting and pre-cooling the torrefied biomass in a cooling compactor and further cooling the compacted torrefied biomass in a cooling tunnel, yielding the compacted torrefied biomass.

What is claimed is: 
     
         1 . A process for producing compacted torrefied biomass from pre-processed biomass, the process comprising:
 drying the pre-processed biomass in a dryer, comprising a pre-dryer and a main dryer, with heater exhaust gas from a heater, yielding dried biomass;   torrefying the dried biomass in a torrefaction processor, comprising a torrefaction reactor and a cooling compactor, with heat generated by the heater, yielding pre-cooled compacted torrefied biomass; and   combusting syngas from torrefaction processor with support fuel in a heater, yielding heat for the dryer and torrefaction reactor.   
     
     
         2 . The process according to  claim 1 , wherein the dryer consists essentially of a pre-dryer and a main dryer. 
     
     
         3 . The process according to  claim 1 , wherein the torrefaction processor consists essentially of a torrefaction reactor and a cooling compactor. 
     
     
         4 . The process according to  claim 1 , wherein drying the pre-processed biomass comprises pre-drying the pre-processed biomass in a pre-dryer with the exhaust gas from the main dryer. 
     
     
         5 . The process according to  claim 4 , wherein pre-drying the pre-processed biomass with the exhaust gas from the main dryer: filters dust fines from the exhaust gas from the main dryer, condenses volatile organic compounds from the exhaust gas from the main dryer, or both filters dust fines and condenses volatile organic compounds from the exhaust gas from the main dryer. 
     
     
         6 . The process according to  claim 1 , wherein drying the pre-processed biomass comprises flash drying the pre-processed biomass in a flash dryer with the heater exhaust gas, and wherein the exhaust gas is obtained from the flash dryer. 
     
     
         7 . The process according to  claim 6 , wherein exhaust gas from the flash dryer is used to pre-dry the pre-processed biomass in a pre-dryer. 
     
     
         8 . The process according to  claim 7 , wherein pre-drying the pre-processed biomass with the exhaust gas from the flash dryer: filters dust fines from the hot exhaust gas from the flash dryer, condenses volatile organic compounds from the exhaust gas from the flash dryer, or both filters dust fines and condenses volatile organic compounds from the hot exhaust gas from the flash dryer. 
     
     
         9 . The process according to  claim 1 , wherein the heater is a combustion heater, torrefying the dried biomass yields syngas, and the syngas is used as a fuel in the combustion heater. 
     
     
         10 . The process according to  claim 9 , wherein natural gas and syngas are used as fuels in the combustion heater. 
     
     
         11 . The process according to  claim 10 , wherein the dilution air is added to the heater in order to have heat capacity of the exhaust gas for drying requirements 
     
     
         12 . The process according to  claim 1 , wherein torrefying the dried biomass comprises heating the dried biomass to temperature between 220 and 280° C. for between 15 and 30 minutes in a low-oxygen environment. 
     
     
         13 . The process according to  claim 1 , wherein the torrefied biomass is processed into pre-cooled compacted torrefied biomass in a cooling compactor, directly connected to the torrefaction reactor thus maintaining the low-oxygen environment. 
     
     
         14 . The process according to  claim 12  further comprising adding a liquid binder. 
     
     
         15 . The process according to  claim 13  wherein the pre-cooled compacted biomass is cooled in a cooling tunnel 
     
     
         16 . The process according to  claim 14  wherein the cooling tunnel pre-heats the dilution air 
     
     
         17 . The process according to  claim 1 , wherein the heater comprises a burner, the burner generates combustion gases, and dilution air is added to the combustion gases to yield the heater exhaust gas. 
     
     
         18 . The process according to  claim 1 , wherein the heat generated by the heater is delivered to the torrefaction reactor by a thermal transfer fluid. 
     
     
         19 . The process according to  claim 1 , wherein the pre-processed biomass is agricultural waste or woody biomass. 
     
     
         20 . The process according to  claim 17 , wherein the pre-processed biomass is woody biomass, the woody biomass is wood or wood waste, and the process further comprises processing the wood or wood waste into wood chips or hog fuel, and sizing the wood chips or hog fuel into wood particles. 
     
     
         21 . The process according to  claim 1 , wherein the process is a continuous process and operating parameters of the process are determined based on measurements obtained from at least one gauge in the process. 
     
     
         22 . The process according to  claim 19 , wherein the process is automatically controlled with Programmable Logic Control. 
     
     
         23 . The process according to  claim 1 , wherein the heater exhaust gas and the dryer exhaust gas are in fluid communication and are moved using a fan and a booster fan. 
     
     
         24 . A process for producing compacted torrefied biomass from pre-processed biomass, the process comprising:
 pre-drying the pre-processed biomass in a pre-dryer, yielding pre-dried biomass;   flash drying the pre-dried biomass in a flash dryer with heater exhaust gas from a heater, yielding flash dried biomass and exhaust gas from the dryer;   torrefying the flash dried biomass in a torrefaction reactor with heat generated by the heater, yielding torrefied biomass; compacting and pre-cooling the torrefied biomass in a cooling compactor with the cooling water, yielding the pre-cooled torrefied biomass, and:   further cooling the pre-cooled compacted torrefied biomass in a cooling tunnel, yielding compacted torrefied biomass and preheated dilution air.