Method and apparatus for drying of fuel

Abstract

A method and apparatus for drying of fuel, in which a moving fuel bed is formed on a conveyor, to which fuel bed a hot, gaseous medium is fed perpendicularly to the travel direction of the fuel bed. The fuel is heated before forming the fuel bed, while the fuel is flowing substantially downward, by means of a hot gaseous medium flow perpendicular to the fuel flow.

1 . A method for drying of fuel, in which method a moving fuel bed is formed of fuel on a conveyor, to which fuel bed a hot, gaseous medium is fed perpendicularly to the travel direction of the fuel bed, wherein the fuel is heated before forming the fuel bed, while the fuel flows substantially downward, by means of a hot, gaseous medium flow perpendicular to the fuel flow.  
   
   
       2 . The method according to  claim 1 , wherein the fuel is heated with a hot, gaseous medium flow that is fed to the fuel flow from the middle and/or edges of the same.  
   
   
       3 . The method according to  claim 1 , wherein the fuel is heated to the drying temperature of fuel, or at least close to it.  
   
   
       4 . The method according to  claim 1 , wherein the fuel bed is formed of a heated fuel flow that flows substantially downward and is discharged downward.  
   
   
       5 . The method according to  claim 1 , wherein the fuel bed travels substantially horizontally.  
   
   
       6 . The method according to  claim 1 , wherein the hot, gaseous medium is fed to the fuel bed from below the fuel bed, via an opening system arranged in the conveyor.  
   
   
       7 . The method according to  claim 1 , wherein the fuel is heated in a heating section and dried in a drying section comprising the conveyor.  
   
   
       8 . The method according to  claim 7 , wherein the exhaust steam produced in the heating and drying of fuel is removed from the heating section and from the drying section.  
   
   
       9 . The method according to  claim 8 , wherein the exhaust steam is removed from the heating section by sucking it from the middle or edges of the fuel flow.  
   
   
       10 . The method according to  claim 7 , wherein the exhaust steam is fed back to the heating section and to the drying section.  
   
   
       11 . The method according to  claim 10 , wherein the exhaust steam is heated before it is fed to the heating section and to the drying section.  
   
   
       12 . The method according to  claim 1 , wherein the moisture content of the fuel is adjusted by changing at least one of the following: delay time of the fuel on the conveyor, temperature of the hot gaseous medium or the amount of fuel on the conveyor.  
   
   
       13 . The method according to  claim 1 , wherein the moisture content of the dried fuel is adjusted by feeding cooling water or another liquid to the fuel bed.  
   
   
       14 . The method according to  claim 1 , wherein the hot, gaseous medium of one of the following: hot air, steam, dry steam, exhaust steam produced in the heating section and/or in the drying section or flue gases of a power boiler.  
   
   
       15 . An apparatus for drying of fuel, said apparatus comprising a drying section equipped with a conveyor on top of which a fuel bed moving along with the movement of the conveyor is arranged to be formed of fuel, and means for feeding a hot gaseous medium to the fuel bed perpendicularly to the travel direction of the fuel bed, wherein the apparatus comprises a heating section arranged before the drying section, in which heating section fuel is arranged to flow substantially downward, and which comprises means for heating fuel, of which means at least one is arranged to feed the hot gaseous medium perpendicularly to the fuel flow.  
   
   
       16 . The apparatus according to  claim 15 , wherein the means for heating the fuel flow are arranged in the middle and/or edges of the fuel flow.  
   
   
       17 . The apparatus according to  claim 15 , wherein the heating section and the drying section are connected to each other and that the heating section is arranged in an angle of 90 degrees with respect to the drying section.  
   
   
       18 . The apparatus according to  claim 15 , wherein in the heating section the fuel forms a dense, downward discharging layer, which is arranged to discharge on the conveyor and which forms a fuel bed.  
   
   
       19 . The apparatus according to  claim 15 , wherein the conveyor is provided with an opening system via which the hot, gaseous medium is  
   
   
       20 . The apparatus according to  claim 15 , wherein conveyor is arranged in a substantially horizontally.  
   
   
       21 . The apparatus according to  claim 15 , wherein the heating section and the drying section comprise means for removing exhaust steam produced in the heating and drying processes.  
   
   
       22 . The apparatus according to  claim 21 , wherein the apparatus comprises means for sucking exhaust steam from the heating section via means arranged in the middle or at the edges of the fuel flow.  
   
   
       23 . The apparatus according to  claim 21 , wherein the exhaust steam is arranged to be fed back to the heating section and to the drying section.  
   
   
       24 . The apparatus according to  claim 23 , wherein the apparatus comprises means for heating exhaust steam.  
   
   
       25 . The apparatus according to  claim 15 , wherein the moisture content of the fuel is arranged to be adjusted by changing at least one of the following: delay time of the fuel on the conveyor, temperature of the hot gaseous medium or the amount of fuel on the conveyor.  
   
   
       26 . The apparatus according to  claim 15 , wherein the apparatus comprises means for feeding cooling water or another liquid to the fuel bed and that the moisture content of the fuel is arranged to be adjusted by adjusting the feeding of cooling water or another liquid.  
   
   
       27 . The apparatus according to  claim 15 , wherein the hot, gaseous medium of one of the following: hot air, steam, dry steam, exhaust steam produced in the heating section and/or in the drying section or flue gases of a power boiler.