Processing of carbonaceous material

Abstract

A method for processing carbonaceous material in a reactor. Carbonaceous material, such as sawdust, plant residues from forestry or agricultural processes, municipal solid waste and refuse derived fuel, is fed into the riser section ( 10 ) of a reactor ( 10 - 15 ) in which it is contacted with inorganic particulate material and reactor walls at an elevated temperature essentially in the absence of oxygen in order to convert the carbonaceous material at least mainly into gaseous processed products, whereby a gas phase is obtained, containing fluidization gas and processed products. According to the invention a dense suspension is formed into the riser space ( 10 ) of the reactor, containing based on the particle number 7×10 8 to 3×10 11 particles/m 3 (about 2×10 7 -1×10 10 particles/ft 3 ), and the mass ratio between the particulate matter bringing heat into the reactor and the carbonaceous material is in the range of 1:1 to 10:1. By the invention, the mixing of the heat transfer medium and the feed is improved, and coarser and less uniform feed can be used than conventionally.

1 . A method for processing carbonaceous material in a reactor, according to which method 
 carbonaceous material is fed into the riser section ( 10 ) of a reactor ( 10 - 15 ) in which it is contacted with inorganic particulate material and reactor walls at an elevated temperature essentially in the absence of oxygen in order to convert the carbonaceous material at least mainly into gaseous processed products, whereby a gas phase is obtained, containing fluidization gas and processed products,    the particulate material is separated from the gas phase in a separation unit ( 12 ),    the inorganic particulate material is recirculated into the riser space ( 10 ),    the processed products are recovered and    optionally at least a part of the processed products are condensed into liquid products, characterized in that    a dense suspension is formed into the riser space ( 10 ) of the reactor, containing based on the particle number 7×10 8  to 3×10 11  particles/m 3  (about 2×10 7 -1×10 10  particles/ft 3 ), and    the mass ratio between the particulate matter bringing heat into the reactor and the carbonaceous material is in the range of 1:1 to 10:1.    
     
     
         2 . The method according to  claim 1 , wherein gas phase products obtained from condensation of the processed products is recycled to the riser space ( 10 ) in the form of circulation gas.  
     
     
         3 . The method according to  claim 2 , wherein the amount of the circulation gas is, expressed as gas volumes, 0.5- to 2-fold the amount of the uncondensed processed products.  
     
     
         4 . The method according to any of  claims 1  to  3 , wherein 
 the inorganic particulate material forming the reactor bed material ( 15 ) is treated with an oxygeneous gas in a separate oxidation unit ( 16 - 18 ,  33 ) comprising a fluidized bed reactor ( 33 ),  
 the material fed ( 18 ) into the oxidation unit is fluidized with an oxygeneous gas in order to burn off the combustion residue attached to the material, and  
 the material obtained from the oxidation unit ( 16 - 18 ,  33 ) is recycled to the reactor ( 10 - 15 ).  
 
     
     
         5 . The method according to  claim 4 , wherein the bed material is conducted from the separation unit ( 16 ) of the solid materials to the reactor by using the oxidation unit as a pneumatic conveyor of the bed material.  
     
     
         6 . The method according to  claim 4  or  5 , wherein the oxidation unit ( 16 - 18 ,  33 ) comprises a circulating bed reactor.  
     
     
         7 . The method according to  claim 6 , wherein the oxidation unit comprises an internal circulation for adjustment of the residence time and the regeneration degree.  
     
     
         8 . The method according to  claim 4  or  5 , wherein the oxidation unit comprises a bubbling bed reactor.  
     
     
         9 . The method according to any of  claims 4  to  8 , wherein the uncondensed gases produced by the process are also conducted ( 29 ) into the oxidation unit, where they are at least partially combusted.  
     
     
         10 . The method according to any of  claims 4  to  9 , wherein the oxidation unit comprises a circulating fluidized bed reactor, which is dimensioned primarily for achieving only removal of combustion residue from the bed material and for producing heat to the extent needed by the thermal treatment.  
     
     
         11 . The method according to  claim 10 , wherein final burning-off of the combustion residue, recovery of excess heat and treatment of flue gases are accomplished with another boiler unit ( 20 ).  
     
     
         12 . The method according to any of the preceding claims, wherein the separation unit ( 12 ;  16 ) used for separating solid materials from gaseous materials comprises a multiport cyclone.  
     
     
         13 . The method according to  claim 12 , wherein the separation unit ( 12 ;  16 ) comprises a cyclone cascade of cyclones wherein there at least one other cyclone, selected from single inlet cyclones and multi inlet cyclones, placed in serial arrangement with the multiport cyclone.  
     
     
         14 . The method according to  claim 13 , wherein the cascade of cyclones ( 12 ;  16 ) comprises a first separation stage which is formed by a single inlet cyclone, and a second separation stage which is formed by a multi inlet cyclone.  
     
     
         15 . The method according to any of  claims 4  to  14 , wherein the reactor and the oxidation unit are mounted together such that the hot part of both the reactor and the oxidation unit each have a common wall whereby at least a part of the heat needed in the reactor is brought through the common wall.  
     
     
         16 . The method according to any of the preceding claims, wherein mass flow ratio of the particulate material bringing heat into the reactor and the carbonaceous material is 1:1 to 10:1.  
     
     
         17 . The method according to  claim 16 , wherein the heat is brought into the reactor partially by using a heat transfer medium and partially directly via the common wall of the reactor and the oxidation unit.  
     
     
         18 . The method according to any of the preceding claims, wherein the reactor comprises internal vanes for increasing the turbulence of the reactor flow.  
     
     
         19 . The method according to any of the preceding claims, comprising using for separation of the solid matter a cyclone that has an outer surface, which can be cooled and/or heated.  
     
     
         20 . The method according to any of the preceding claims, comprising using 
 a reactor, which comprises a riser having an axially annular cross-section which is provided with a multiport cyclone for separation of the particulate matter, and    an oxidation unit which comprises a riser having an axially annular cross-section which is fitted concentrically inside the reactor, whereby said oxidation unit is provided with a multiport cyclone for separation of the treated particulate material.    
     
     
         21 . The method according to any of the preceding claims, wherein the solid matter is separated in two stages, whereby a first portion mainly comprising solid matter is separated in a first stage and recycled to an oxidation unit, and a second portion mainly comprising combustion residue is separated in a second stage and used in a separate process.  
     
     
         22 . Method of processing carbonaceous material in a reactor, according to which method 
 a carbonaceous material is fed into the riser ( 10 ) of a reactor ( 10 - 15 ) in which it is contacted with a bed formed by inorganic particulate material at an elevated temperature essentially in the absence of oxygen in order to convert the carbonaceous material at least mainly into gaseous processed products, whereby a gas phase is obtained, containing fluidization gas and processed products,    the particulate material is separated from the gas phase in a separation unit ( 12 ),    the inorganic particulate material is recirculated into the riser space ( 10 ),    the processed products are recovered and    optionally at least a part of the processed products are condensed into liquid products, characterized in that    the velocity of the fluidization gas in the reactor is maintained in a range which allows for fluidization in the regime of turbulent or rapid fluidization, whereby the velocity ratio between the gas and the particles is smaller than about 2 along the whole length of the riser space.    
     
     
         23 . The method according to  claim 22 , wherein the residence time in the reactor is about 0.01 to 10 s.  
     
     
         24 . The method according to  claim 22  or  23 , wherein the bed ( 15 ) contains a particle number of 7×10 8 -3×10 11  particles/m 3  (about 2×10 7 -1×10 10  particles/ft 3 ).  
     
     
         25 . The method according to any of the preceding claims, wherein the average particles size of the solid matter particles is 50 to 120 micrometer.