Method and Device for Refining Pellets

Abstract

A method for refining pellets, in which, in a first step, pellets that have been pressed from a biomass are provided. A heat treatment is carried out, involving heating the pellets to a temperature between 210° C. and 390° C. The heat treatment takes a period of time of between 1 minute and 30 minutes. Also described is a device that is suitable for carrying out the method. The pellets treated in this way are water-repellent and so can be stored outdoors.

1 . A method for refining pellets, comprising the following steps:
 a. providing pellets pressed from biomass,   b. carrying out a heat treatment of the pellets with the following parameters:
 i. the pellets are heated to a temperature of between 210° C. and 390° C.; 
 ii. the heat treatment extends over a period of time of between 1 min and 30 min. 
   
     
     
         2 . The method as claimed in  claim 1 , characterized in that the pellets are heated by a suitably temperature-controlled air stream. 
     
     
         3 . The method as claimed in  claim 2 , wherein the air stream has a power, characterized in that the power of the air stream is such that the pellets are set into motion by the air stream. 
     
     
         4 . The method as claimed in  claim 1 , characterized in that the pellets are treated batchwise. 
     
     
         5 . The method as claimed in  claim 4 , characterized in that the heat treatment takes place with an air stream of 6 m 3  to 20 m 3  per kilogram of pellets. 
     
     
         6 . The method as claimed in  claim 1 , characterized in that the heat treatment is carried out in an atmosphere with a reduced content of oxygen. 
     
     
         7 . The method as claimed in  claim 1 , characterized in that the heat treatment extends over a period of time of between 3 min and 16 min. 
     
     
         8 . The method as claimed in  claim 1 , characterized in that the pellets are heated to a temperature of between 250° C. and 300° C. 
     
     
         9 . The method as claimed in  claim 1 , characterized in that the pellets provided in step a. have a diameter of between 4 mm and 20 mm. 
     
     
         10 . The method as claimed in  claim 1 , characterized in that the pellets provided in step a. have a moisture content of between 5% by weight and 15% by weight. 
     
     
         11 . The method as claimed in  claim 1 , characterized in that the pellets are quenched after the heat treatment. 
     
     
         12 . A device for refining pellets, wherein the device comprises:
 a. a treatment chamber which has a supporting floor for the pellets and a first side wall and a second side wall, wherein the supporting floor is provided with a plurality of apertures, wherein the first side wall and the second side wall are adjacent to the supporting floor on opposite sides, and wherein the second side wall has a chute which leads onto the supporting floor;   b. a channel for an air stream, said channel leading below the supporting floor;   c. a heating device and a driving device for the air stream, in order to conduct a heated air stream from below through the apertures in the support floor;   d. a deflecting surface arranged above the supporting floor such that the air stream and pellets entrained by the air stream are deflected in a direction of movement which points from the first side wall in the direction of the second side wall,   
       characterized in that
 e. a baffle plate is arranged between the first side wall and the second side wall such that the pellets move upward between the first side wall and the baffle plate. 
 
     
     
         13 . The device as claimed in  claim 12 , characterized in that the distance between the baffle plate and the first side wall is adjustable. 
     
     
         14 . The device as claimed in  claim 12 , characterized in that the apertures in a vicinity of the first side wall are of larger dimensions than in a vicinity of the second side wall. 
     
     
         15 . The device as claimed in  claim 12 , characterized in that the supporting floor is arranged in an inclined manner. 
     
     
         16 . The device as claimed in  claim 13 , characterized in that the apertures in a vicinity of the first side wall are of larger dimensions than in a vicinity of the second side wall. 
     
     
         17 . The device as claimed in  claim 13 , characterized in that the supporting floor is arranged in an inclined manner. 
     
     
         18 . The device as claimed in  claim 14 , characterized in that the supporting floor is arranged in an inclined manner. 
     
     
         19 . The device as claimed in  claim 16 , characterized in that the supporting floor is arranged in an inclined manner. 
     
     
         20 . The method as claimed in  claim 2 , characterized in that the pellets are treated batchwise.