Apparatus and process for torrefaction of ligno-cellulosic biomasses and mixtures with liquid

Abstract

A method and apparatus for treating a biomass material to produce a torrefied fuel comprising the steps of preheating the biomass material with a hot liquid flowing counter to the direction of travel of the biomass material at a temperature up to 200° C., superheating the preheated biomass material with a liquid flowing counter-current to the direction of travel of the biomass material to a temperature ranging up to 300° C. for a period sufficient to obtain full torrefaction of the biomass material, and cooling the torrefied biomass material with liquid flowing counter to the direction of travel of the torrefied biomass material.

1 . A method of treating a biomass material to continuously produce a torrefied product comprising the steps of:
 a. transporting a biomass material through a first processing station containing moving heated liquid and immersing said biomass material in said heated liquid preheating said biomass until said biomass material reaches a desired preheated temperature to remove the moisture from the biomass until the biomass material has a maximum equilibrium water content of about 10%;   b. transporting said preheated biomass material from said first station to a second torrefaction station;   c. applying a flow of heated torrefaction liquid in said second station in a continuous liquid flow circuit opposite to the direction of travel of said biomass material to transfer heating energy to preheated biomass material until said biomass material reaches a temperature suitable to create torrefaction of said biomass material;   d. transporting said torrefied biomass material from said second station to a third cooling station;   e. cooling said torrefied biomass material in said third station with a moving flow of cooler liquid in a chamber separate from said torrefaction liquid flow circuit by transporting said biomass material in a counter-current direction to that of the moving cooling liquid; and   f. transporting heated liquid from the downstream flow area of the carried biomass of said third station chamber to said first station to transfer heat generated by said torrefied biomass material to said first station.   
     
     
         2 . A method as claimed in  claim 1  wherein said biomass material is pre-formed pellets. 
     
     
         3 . A method as claimed in  claim 1  wherein each station is an upper open ended receptacle. 
     
     
         4 . A method as claimed in  claim 3  wherein said receptacle is a trough with an open upper section. 
     
     
         5 . A method as claimed in  claim 1  wherein said second station is additionally heated with micro-wave radiation having a frequency of 5.8 GHz. 
     
     
         6 . A method as claimed in  claim 1  wherein said torrefaction liquid is contained in a closed flow circuit including a housing defining a torrefaction chamber, a pump for moving liquid out of said torrefaction chamber to a heater for heating said liquid from about 230° C. to about 300° C. and conduit means for returning said heated liquid from said heater back to said housing. 
     
     
         7 . A method of treating biomass material as claimed in  claim 1  wherein said torrefaction liquid has its flow directed in a counter-current direction opposite to the direction of travel said biomass material during said preheating, torrefaction and cooling steps. 
     
     
         8 . A method of treating biomass material as claimed in  claim 1  wherein the heating liquid for each of the steps a), c) and e) is separately filtered and regenerated. 
     
     
         9 . A method of treating biomass material as claimed in  claim 1  wherein gases and waste products emitted during the heating of said biomass material are collected by a plurality of continuous collection chimneys mounted over said first and second stations. 
     
     
         10 . A method of treating biomass material as claimed in  claim 1  wherein said torrefaction temperature is at least 300° C. 
     
     
         11 . A method of treating biomass pellet feedstock by torrefaction to produce a refilled solid bio-fuel comprising the steps of:
 a. loading biomass pellet feedstock into a continuous feed container for depositing said pellets into a preheating receptacle;   b. preheating the biomass pellets in said preheating receptacle with a recycled heated liquid moving in a counter-current flow to that traveled by the biomass feedstock to a temperature less than about 200° C.;   c. applying a heated liquid substantially contained in a closed flow circuit to the preheated biomass pellets which have been transported to a second receptacle heating said biomass pellets until the pellets reach a temperature of up to about 300° C. for sufficient time allowing uniform torrefaction of said pellets;   d. cooling the torrefied biomass pellets outside of said torrefaction closed flow circuit which have been transported to a third receptacle with a cooler liquid moving in a counter-current flow in respect of the pellets;   e. recycling the liquid used to cool the pellets in step d. to the biomass pellets of step b); and   f. transporting the cooled pellets from said third receptacle to a draining station.   
     
     
         12 . A method of treating biomass pellets as claimed in  claim 11  wherein said heated liquid is taken from a group of liquids consisting of one or more of the following liquids: silicone oil, vegetable oil, petroleum based oil, synthetic oil, used oil, coal/peat distilled liquid, low temperature metals. 
     
     
         13 . A method of treating biomass pellets as claimed in  claim 11  wherein said liquid in contact with said pellets is agitated in step c). 
     
     
         14 . Apparatus for torrefaction of biomass material using a liquid for torrefaction comprising:
 a. a biomass feed housing;   b. a preheating receptacle defining a preheating chamber with an open upper section adapted to hold liquid and receive biomass from said feed receptacle and conveyor means mounted in said preheating receptacle for carrying biomass material through said preheating receptacle and the liquid contained therein;   c. a torrefaction receptacle defining a chamber with an open upper section positioned downstream of said preheating receptacle, conveyor means mounted in said torrefaction receptacle to received preheated biomass material from said preheating conveyor means and carry biomass material through said torrefaction receptacle;   d. a closed fluid circuit means connected to said torrefaction receptacle, heater means connected to said fluid circuit to heat liquid passing through said fluid circuit and pump means to pump liquid through said fluid circuit from one section of said torrefaction receptacle back to another section of said torrefaction receptacle;   e. a cooling receptacle defining a cooling chamber with an upper open section positioned downstream of said torrefaction receptacle, conveyor means mounted in said cooling receptacle for carrying torrefied biomass material received from said torrefaction receptacle through said cooling receptacle; and   f. discharge means discharging said torrefied biomass material from said cooling receptacle.   
     
     
         15 . Apparatus as claimed in  claim 14  including heat exchange means connecting said cooling chamber with said preheating chamber and carrying liquid from said cooling chamber to said preheating chamber. 
     
     
         16 . Apparatus as claimed in  claim 14  wherein said biomass feed housing is a feed hopper with a heat exchange means mounted thereto. 
     
     
         17 . Apparatus as claimed in  claim 16  wherein a heat exchange means in the form of a coil shaped conduit is mounted in said biomass feed housing. 
     
     
         18 . Apparatus as claimed in  claim 17  wherein at least one pump is connected to coil shaped conduit leading to or away from said feed hopper. 
     
     
         19 . Apparatus as claimed in  claim 16  wherein said heat exchange means comprises a conduit means with one end connected to the proximal end of said cooling receptacle and communicates with said cooling chamber, another end connected to said preheating receptacle and communicating with said preheating chamber and a pump mounted to said conduit means to transport liquid from said cooling chamber back to said preheating chamber. 
     
     
         20 . Apparatus as claimed in  claim 16  including separation columns mounted over various sections of said preheating receptacle and said torrefaction receptacle to collect by products from said biomass material when the same is subjected to different liquid temperatures. 
     
     
         21 . Apparatus as claimed in  claim 16  including a liquid reservoir receptacle activated by sensor means in one of said receptacles to replenish liquid into said cooling receptacle. 
     
     
         22 . Apparatus as claimed in  claim 21  wherein said sensor means is mounted to said cooling receptacle to sense the liquid level in cooling chamber. 
     
     
         23 . Apparatus as claimed in  claim 15  wherein said torrefaction receptacle has microwave generating means mounted thereto to provide 5.8 GHz microwaves. 
     
     
         24 . Apparatus for torrefaction of biomass material using a liquid for torrefaction comprising:
 a. a biomass feed receptacle with a first heat exchange means mounted thereto communicating with a preheating receptacle and a cooling receptacle;   b. a preheating receptacle comprising an open ended trough housing defining a preheating chamber adapted to hold liquid and receive biomass from said feed receptacle and conveyor means mounted in said preheating receptacle for carrying biomass material through said preheating receptacle and the liquid contained therein;   c. a torrefaction receptacle comprising an open ended trough housing defining a chamber positioned downstream of said preheating receptacle, conveyor means mounted in said torrefaction receptacle to received preheated biomass material from said preheating conveyor means and carry biomass material through said torrefaction receptacle;   d. a closed fluid circuit means connected to said torrefaction receptacle, heater means connected to said fluid circuit to heat liquid passing through said fluid circuit and pump means to pump liquid through said fluid circuit from an end of said torrefaction receptacle back to the other end of said torrefaction receptacle so that biomass material is transported by said torrefaction conveyor means against the flow of liquid heated by said heater means;   e. a cooling receptacle comprising an open ended trough housing defining a cooling chamber positioned downstream of said torrefaction receptacle, conveyor means mounted in said cooling receptacle for carrying biomass material received from said torrefaction receptacle through said cooling receptacle; a second heat exchange means connecting said cooling chamber with said preheating chamber and carrying liquid from said cooling chamber to said preheating chamber.   
     
     
         25 . An apparatus as claimed in  claim 24  wherein said agitation means is mounted to said torrefaction receptacle housing.