Process for Preparing Torrefied Biomass Material Using a Combustible Liquid

Abstract

A process for preparing torrefied densified biomass and/or torrefied densified biosolids comprising about 2% to about 25% w/w combustible liquid is disclosed. The process involves densifying biomass and/or biosolids, or providing a densified biomass and/or densified biosolids, and submerging the densified material in a hot combustible liquid for about 2 to about 120 minutes until the densified material is torrefied. The combustible liquid may be derived from any source exemplified by an oil such as those derived from plant, marine and animal sources, or alternatively, a petroleum product. The combustible liquid is heated to a temperature in the range of about 160° C. to about 320° C. prior to submersion of the densified biomass material. Also disclosed is a biomass torrefied densified biomass and/or torrefied densified biosolid comprising about 2% to about 25% w/w combustible liquid.

1 . A torrefied densified biomass prepared by torrefying a densified biomass feedstock in a combustible liquid, the torrefied densified biomass comprising about 2% to about 25% w/w of the combustible liquid. 
     
     
         2 . The torrefied densified biomass of  claim 1 , wherein the combustible liquid is a plant-derived oil. 
     
     
         3 . The torrefied densified biomass of  claim 2 , wherein the plant-derived oil is canola oil, linseed oil, sunflower oil, safflower oil, corn oil, peanut oil, palm oil, soybean oil, rapeseed oil, cottonseed oil, palm kernel oil, coconut oil, sesame seed oil, olive oil, or a combination thereof. 
     
     
         4 . The torrefied densified biomass of  claim 1 , wherein the combustible liquid is a petroleum-based oil or a bitumen-based oil. 
     
     
         5 . The torrefied densified biomass of  claim 4 , wherein the petroleum-based oil or a bitumen-based oil is a synthetic motor oil, a synthetic engine oil, a hydraulic fluid, a transmission fluid, an automatic transmission fluid, a chainsaw bar and chain oil, a gear oil, a diesel fuel, a paraffin wax, or a combination thereof. 
     
     
         6 . The torrefied densified biomass of  claim 1 , wherein the densified biomass feedstock is derived from a plant material. 
     
     
         7 . The torrefied densified biomass of  claim 6 , wherein the plant material is wood waste from wood-processing operations, sawdust, wood chips, straw, bagasse, waste streams from plant processing operations, processed from crops, or a combination thereof. 
     
     
         8 . The torrefied densified biomass of  claim 1 , wherein the densified biomass feedstock comprises biosolids. 
     
     
         9 . The torrefied densified biomass of  claim 1 , having a heat energy value of about 6,000 BTU per pound to about 13,000 BTU per pound. 
     
     
         10 . The torrefied densified biomass of  claim 1 , having a heat energy value of about 22 gigajoules per metric tonne (GJ/T) to about 27 GET on a bone dry basis. 
     
     
         11 . The torrefied densified biomass of  claim 1  having a carbon content of about 54 carbon % to about 63 carbon % on a bone dry basis. 
     
     
         12 . A process for preparing a torrefied densified biomass, comprising the steps of:
 (a) densifying a supply of a biomass feedstock to obtain a densified biomass material;   (b) submerging the densified biomass material in a combustible liquid, the combustible liquid at a temperature between about 160° C. and about 320° C.;   (c) torrefying the densified biomass material in the combustible liquid for about 2 minutes to about 120 minutes to produce the torrefied densified biomass; and   (d) recovering the torrefied densified biomass;   wherein the torrefied densified biomass comprises about 2% to about 25% w/w of the combustible liquid.   
     
     
         13 . A process for preparing a torrefied densified biomass, comprising the steps of:
 (a) providing a supply of densified biomass material;   (b) submerging the densified biomass material in a combustible liquid, the combustible liquid at a temperature between about 160° C. and about 320° C.;   (c) torrefying the densified biomass material in the combustible liquid for about 2 minutes to about 120 minutes to produce the torrefied densified biomass; and   (d) recovering the torrefied densified biomass;   wherein the torrefied densified biomass comprises about 2% to about 20% w/w of the combustible liquid.   
     
     
         14 . A process for producing torrefied pellets, comprising the steps of:
 (a) densifying a supply of a biomass feedstock and extruding therefrom densified pellets;   (b) conveying the densified pellets into and through an input end of a torrefusion reactor;   (c) submerging the densified pellets in a combustible liquid contained within the torrefusion reactor, the combustible liquid having a temperature between about 160° C. and about 320° C.;   (d) conveying the submerged densified pellets from the input end to an output end of the torrefusion reactor for a period of time from about 2 minutes to about 120 minutes, wherein the densified pellets are torrefied and heat and gases are produced during torrefaction;   (e) discharging the torrefied pellets from the output end of the torrefusion reactor and conveying the torrefied pellets into and through a cooler; and   (f) cleaning the cooled torrefied pellets to produce cleaned torrefied pellets, the cleaned torrefied pellets comprising about 2% to about 20% w/w of the combustible liquid.   
     
     
         15 . The process of any of  claims 12 - 14 , wherein the supply is provided continuously, or semi-continuously, or in batches. 
     
     
         16 . The process of  claim 14 , wherein the cleaning step (f) comprises a screening process to separate fines from the cooled torrefied pellets. 
     
     
         17 . The process of  claim 14 , wherein the cooler of step (e) is a water cooler and the cleaning step (f) comprises washing the cooled torrefied pellets in water contained within the water cooler to remove residual combustible liquid from outer surfaces of the cooled torrefied pellets. 
     
     
         18 . The process of any of  claims 12 - 14 , further comprising the steps of:
 (a) combining in a torgas heater the torrefusion gases and heat produced during torrefusion, and combusting therein to produced heated air; and   (b) using the heated air to heat the combustible liquid contained within the torrefusion reactor.   
     
     
         19 . The process of  claim 16 , further comprising the steps of:
 (a) producing thermal energy from the separated fines;   (b) combining in a torgas burner the thermal energy with the torrefusion gases and heat produced during torrefusion;   (c) combusting the combined thermal energy and torrefusion gases and heat in the torgas burner to produce heated air; and   (d) heating the combustible liquid contained within the torrefusion reactor using the heated air.   
     
     
         20 . The process of  claim 16 , wherein the wash water is used to desalinate a biomass feedstock.