Torrefaction and partial pyrolysis of material for fuel pellet production

Abstract

The present application discloses a process for the preparation of fuel pellets, said process comprising the steps of a) subjecting a feedstock (e.g. a biomass material) to a torrefaction and partial pyrolysis step at a temperature in the range from 250° C. to 500° C., whereby a solid char and volatile fraction are obtained, said volatile fraction comprising a tar fraction; b) at least partially condensing the volatile fraction so as to obtain a tar-rich fraction, wherein the tar-rich fraction is condensed onto the solid char; and pelletization of the combined solid char/tar-rich fraction so as to obtain said fuel pellets. Novel fuel pellets are also disclosed.

1 . A process for the preparation of fuel pellets, said process comprising the steps of
 a. subjecting a feedstock to a torrefaction and partial pyrolysis step at a temperature in the range from 250° C. to 500° C., whereby a solid char and volatile fraction are obtained, said volatile fraction comprising a tar fraction;   b. at least partially condensing the volatile fraction so as to obtain a tar-rich fraction, wherein the tar-rich fraction is condensed onto the solid char, whereby the solid char is combined with at least a part of the tar-rich fraction; and   c. pelletization of the combined solid char/tar-rich fraction so as to obtain said fuel pellets.   
     
     
         2 . The process according to  claim 1 , wherein the condensation of the volatile fraction in step b) is conducted at a temperature of in the range from 50° C. to 150° C. 
     
     
         3 . The process according to  claim 1 , wherein the process further comprises size reduction of the solid char, wherein the size reduction takes place as a part of step a) and/or immediately subsequent to step a). 
     
     
         4 - 6 . (canceled) 
     
     
         7 . The process according to  claim 2 , wherein the process further comprises size reduction of the solid char, wherein the size reduction takes place as a part of step a) and/or immediately subsequent to step a). 
     
     
         8 . The process according to  claim 1 , wherein the water in an amount of up to 0-15 wt % by weight of the solid char is combined with the solid char in step c). 
     
     
         9 . The process according to  claim 2 , wherein the water in an amount of up to 0-15 wt % by weight of the solid char is combined with the solid char in step c). 
     
     
         10 . The process according to  claim 3 , wherein the water in an amount of up to 0-15 wt % by weight of the solid char is combined with the solid char in step c). 
     
     
         11 . The process according to  claim 7 , wherein the water in the amount of up to 0-15 wt % by weight of the solid char is combined with the solid char in step c). 
     
     
         12 . The process according to  claim 1 , wherein additives are provided in the pellets so as to modify the properties of the pellets. 
     
     
         13 . The process according to  claim 2 , wherein additives are provided in the pellets so as to modify the properties of the pellets. 
     
     
         14 . The process according to  claim 3 , wherein additives are provided in the pellets so as to modify the properties of the pellets. 
     
     
         15 . The process according to  claim 8 , wherein additives are provided in the pellets so as to modify the properties of the pellets. 
     
     
         16 . A fuel pellet comprising a solid char, a tar, and, optionally, one or more additives, said solid char and tar being obtained by torrefaction and partial pyrolysis of a feedstock at a temperature from 250° C. to 500° C., wherein said pellet has a tensile strength of at least 100 kPa.