Torrefaction and partial pyrolysis to produce fuel pellets with counter current flow of tar

Abstract

The present application discloses a continuous process for the preparation of fuel pellets, said process comprising the steps of a) feeding 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) directing the evolved volatile fraction as counter current stream relative to the stream of the feedstock, and at least partially condensing the volatile fraction on the incoming feedstock so as to obtain a tar-rich fraction combined with the incoming feedstock; and c) pelletization of the combined solid char/tar-rich fraction so as to obtain said fuel pellets. Novel fuel pellets are also disclosed.

1 . A continuous process for the preparation of fuel pellets, said process comprising the steps of
 a. feeding a feedstock to a torrefaction and partial pyrolysis step in a reactor at a temperature in the range from 250° C. to 500° C., whereby a solid char and a volatile fraction are obtained, said volatile fraction comprising a tar fraction;   b. directing the evolved volatile fraction as a counter current stream in the reactor relative to the stream of the incoming feedstock, and at least partially condensing the volatile fraction on the incoming feedstock so as to obtain a tar-rich fraction combined with the feedstock; and   c. pelletization of the combined solid char and (reheated) tar-rich fraction so as to obtain said fuel pellets.   
     
     
         2 . The process according to  claim 1 , wherein the gas is released near the solid feedstock inlet. 
     
     
         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.