Fuel gasification system

Abstract

A fuel gasification system including a gasification furnace including a fluidized bed formed by fluidizing reactant gas for gasifying fuel charged into gasification gas and flammable solid content, a combustion furnace for combustion of the flammable solid content into which the flammable solid content produced in the furnace is introduced together with bed material and that includes a fluidized bed formed by fluidizing reactant gas, a material separator such as hot cyclone that separates bed material from exhaust gas introduced from the combustion furnace, the separated bed material being fed through a downcorner to the gasification furnace, and a tar decomposing mechanism that heats the gasification gas produced in the furnace to decompose tar contained in the gasification gas.

1 . A fuel gasification system comprising tar decomposing means for heating gasification gas produced in a gasification furnace to decompose tar contained in said gasification gas. 
     
     
         2 . A fuel gasification system as claimed in  claim 1 , wherein the tar decomposing means is constituted by a double-pipe heat exchanger comprising coaxially arranged inner and outer pipes, exhaust gas from a combustion furnace and separated in a material separator being introduced into an exhaust gas passage in the inner pipe while gasification gas is introduced into a gasification gas passage between the inner and outer pipes and is heated by the exhaust gas from the combustion furnace. 
     
     
         3 . A fuel gasification system as claimed in  claim 1 , wherein the tar decomposing means is constituted by a double-pipe heat exchanger comprising coaxially arranged inner and outer pipes, gasification gas being introduced into a gasification gas passage in the inner pipe while exhaust gas from the combustion furnace and separated in a material separator is introduced into an exhaust gas passage between the inner and outer pipes, said gasification gas being heated by the exhaust gas from the combustion furnace. 
     
     
         4 . A fuel gasification system as claimed in  claim 2 , further comprising additional heating means for elevating in temperature the exhaust gas introduced into the exhaust gas passage. 
     
     
         5 . A fuel gasification system as claimed in  claim 3 , further comprising additional heating means for elevating in temperature the exhaust gas introduced into the exhaust gas passage. 
     
     
         6 . A fuel gasification system comprising
 a gasification furnace which has a fluidized bed formed by fluidizing reactant gas to gasify charged fuel into gasification gas and flammable solid content,   a combustion furnace into which the flammable solid content generated in the gasification furnace is introduced together with bed material and which has a fluidized bed formed by fluidizing reactant gas to burn the flammable solid content and   a material separator for separating bed material from the exhaust gas introduced from the combustion furnace to feed the separated bed material to said gasification furnace,   said fuel gasification system comprising tar decomposing means for heating the gasification gas produced in the gasification furnace to decompose tar contained in the gasification gas.   
     
     
         7 . A fuel gasification system as claimed in  claim 6 , wherein the tar decomposing means is constituted by a heat exchanger comprising an gasification gas passage formed on an inner surface of the combustion furnace, the gasification gas being introduced into the gasification gas passage and heated by heat of the combustion furnace. 
     
     
         8 . A fuel gasification system as claimed in  claim 6 , wherein the tar decomposing means is constituted by a heat exchanger comprising a gasification gas passage formed on an outer surface of the combustion furnace, the gasification gas being introduced into the gasification gas passage and heated by heat of the combustion furnace. 
     
     
         9 . A fuel gasification system as claimed in  claim 6 , wherein the tar decomposing means is constituted by a heat exchanger comprising a gasification gas passage formed on an outer surface of a downcorner for guiding bed material separated in a material separator to the gasification furnace, the gasification gas being introduced into the gasification gas passage and heated by heat of the downcorner. 
     
     
         10 . A fuel gasification system as claimed in  claim 8 , wherein, on an outer surface of the heat exchanger comprising the gasification gas passage, an exhaust gas passage is formed into which introduced is the exhaust gas from the combustion furnace and elevated in temperature by additional heating means. 
     
     
         11 . A fuel gasification system as claimed in  claim 9 , wherein, on an outer surface of the heat exchanger comprising the gasification gas passage, an exhaust gas passage is formed into which introduced is the exhaust gas from the combustion furnace and elevated in temperature by additional heating means. 
     
     
         12 . A fuel gasification system as claimed in  claim 2 , wherein the gasification gas passage is a spiral passage. 
     
     
         13 . A fuel gasification system as claimed in  claim 12 , wherein the gasification gas passage is arranged vertically. 
     
     
         14 . A fuel gasification system as claimed in  claim 3 , wherein the gasification gas passage is a spiral passage. 
     
     
         15 . A fuel gasification system as claimed in  claim 4 , wherein the gasification gas passage is a spiral passage. 
     
     
         16 . A fuel gasification system as claimed in  claim 5 , wherein the gasification gas passage is a spiral passage. 
     
     
         17 . A fuel gasification system as claimed in  claim 7 , wherein the gasification gas passage is a spiral passage. 
     
     
         18 . A fuel gasification system as claimed in  claim 8 , wherein the gasification gas passage is a spiral passage. 
     
     
         19 . A fuel gasification system as claimed in  claim 9 , wherein the gasification gas passage is a spiral passage. 
     
     
         20 . A fuel gasification system as claimed in  claim 10 , wherein the gasification gas passage is a spiral passage. 
     
     
         21 . A fuel gasification system as claimed in  claim 11 , wherein the gasification gas passage is a spiral passage. 
     
     
         22 . A fuel gasification system as claimed in  claim 14 , wherein the gasification gas passage is arranged vertically. 
     
     
         23 . A fuel gasification system as claimed in  claim 15 , wherein the gasification gas passage is arranged vertically. 
     
     
         24 . A fuel gasification system as claimed in  claim 16 , wherein the gasification gas passage is arranged vertically. 
     
     
         25 . A fuel gasification system as claimed in  claim 17 , wherein the gasification gas passage is arranged vertically. 
     
     
         26 . A fuel gasification system as claimed in  claim 18 , wherein the gasification gas passage is arranged vertically. 
     
     
         27 . A fuel gasification system as claimed in  claim 19 , wherein the gasification gas passage is arranged vertically. 
     
     
         28 . A fuel gasification system as claimed in  claim 20 , wherein the gasification gas passage is arranged vertically. 
     
     
         29 . A fuel gasification system as claimed in  claim 21 , wherein the gasification gas passage is arranged vertically.