Method for gasifying solid fuel with unified gas purification and gasifier using said method

Abstract

A function of absorbing CO 2 in gas by chemical to accelerate gasifying reaction is made compatible with a catalytic function of reforming tar in gasified gas generated by the gasifying reaction to thereby make it possible to produce clean product gas with high gasification efficiency. Gasification process is divided into three processes: a gasification furnace 10 for carrying out gasification process by pyrolysis and gasification (pyrolysis gasification phase, first process), a combustion furnace 20 for burning char to obtain calcined active chemical (char combustion phase, second process) and a gas purification furnace 30 for purifying gasified gas (gasified gas purification phase, third process). Through heat transmission by fluid heat medium and chemical and through harmony of chemical reactions in respective phases by the chemical, the gasification furnace 10 is independently controlled to a low or medium temperature (773-1073° K) which is required for gasification and which enables absorption of CO 2 ; and the gas purification furnace 30 is controlled to a high temperature (1073° K or more) required for gas purification.

1 . A method for gasifying solid fuel with unified gas purification, characterized in that it comprises
 a first process of feeding solid fuel and a gasifying agent to a reactor of pyrolysis gasification phase where said solid fuel is pyrolyzed in contact with heat medium to generate char which is gasified by said gasifying agent, CO 2  in gasified gas generated by said pyrolysis and gasification being absorbed by active chemical at a reaction temperature of said pyrolysis gasification phase,   a second process of feeding residual char not gasified in said reactor of pyrolysis gasification phase, the heat medium low-temperatured through contribution to the pyrolysis and gasification of said solid fuel, the low-active chemical less-activated through reaction with said CO 2  and newly added inactive chemical to a reactor of char combustion phase where said char is burned by an oxidizing agent to bring about combustion heat with which said low-temperatured heat medium is heated, said low-active and inactive chemicals are calcined to be re-activated and activated, respectively, and   a third process of feeding the heat medium heated in said reactor of char combustion phase, the active chemical activated and said gasified gas from said reactor of pyrolysis gasification phase to a reactor of gasified gas purification phase where said active chemical functions as catalyst to reform tar in said gasified gas at a reaction temperature of said gasified gas purification phase and absorbs H 2 S and HCl in said gasified gas to purify said gasified gas, the active chemical having contributed mainly as catalyst to purifying said gasified gas being circulated together with the heat medium to said reactor of pyrolysis gasification phase.   
     
     
         2 . A method for gasifying solid fuel with unified gas purification as claimed in  claim 1 , characterized in that, in said first process, the reaction temperature in said reactor of pyrolysis gasification phase for said pyrolysis gasification phase is controlled to 773-1073° K in harmony at least with the absorption reaction of CO 2  in said gasified gas by said active chemical. 
     
     
         3 . A method for gasifying solid fuel with unified gas purification as claim in  claim 1 , characterized in that, in said second process, the reaction temperature in said reactor of char combustion phase is controlled to 1073° K or more in harmony at least with the re-activation and activation reactions of said low-active and inactive chemicals, respectively. 
     
     
         4 . A method for gasifying solid fuel with unified gas purification as claimed in  claim 1 , characterized in that, in said third process, the reaction temperature in said reactor of gasified gas purification phase for said gasified gas purification phase is controlled to temperature of 1073° K or more in harmony at least with sufficient exhibition of the catalytic function by said active chemical to said tar reforming reaction, which is lower than the reaction temperature in said reactor of char combustion phase and is higher than the reaction temperature in said reactor of pyrolysis gasification phase for said pyrolysis gasification phase. 
     
     
         5 . A method for gasifying solid fuel with unified gas purification as claimed in any one of  claims 1 - 4 , characterized in that the inactive chemical is mineral which has, as its base, metal carbonate or hydroxide. 
     
     
         6 . A gasifier for solid fuel with unified gas purification, characterized in that it comprises
 a reactor of pyrolysis gasification phase fed with the solid fuel and a gasifying agent, said solid fuel being pyrolyzed in contact with heat medium to generate char gasified by said gasifying agent, CO 2  in gasified gas generated by the pyrolysis and gasification being absorbed by active chemical at a reaction temperature of the pyrolysis and gasification,   a reactor of char combustion phase fed with residual char not gasified in said reactor of pyrolysis gasification phase, the heat medium low-temperatured through contribution to the pyrolysis and gasification of said solid fuel, the low-active chemical less-activated through reaction with said CO 2  and newly added inactive chemical, said char being burned by an oxidizing agent to bring about combustion heat with which said low-temperatured heat medium is heated and said low-active and inactive chemicals are calcined to be re-activated and activated, respectively, and   a reactor of gasified gas purification phase fed with the heat medium heated in said reactor of char combustion phase, the activated active chemical and said gasified gas from said reactor of pyrolysis gasification phase, said active chemical functioning as catalyst to reform tar in said gasified gas at a tar reforming reaction temperature and absorbing H 2 S and HCl in said gasified gas to purify said gasified gas, the active chemical having contributed mainly as catalyst to purifying said gasified gas being circulated together with the heat medium to said reactor of pyrolysis gasification phase.   
     
     
         7 . A gasifier for solid fuel with unified gas purification as claimed in  claim 6 , characterized in that the reaction temperature of said pyrolysis and gasification in said reactor of pyrolysis gasification phase is controlled to 773-1073° K in harmony with at least the absorption reaction of CO 2  in said gasified gas. 
     
     
         8 . A gasifier for solid fuel with unified gas purification as claimed in  claim 6 , characterized in that the reaction temperature in said reactor of char combustion phase is controlled to 1073° K or more in harmony with at least the re-activation and activation reactions of said low-active and inactive chemicals, respectively. 
     
     
         9 . A gasifier for solid fuel with unified gas purification as claimed in  claim 6 , characterized in that the reaction temperature for said tar reformation in said reactor of gasified gas purification phase is controlled to temperature of 1073° K or more in harmony at least with sufficient exhibition of the catalytic function by said active chemical to said tar reforming reaction, which is lower than the reaction temperature in said reactor of char combustion phase and is higher than the reaction temperature of said pyrolysis and gasification in said reactor of pyrolysis gasification phase. 
     
     
         10 . A gasifier for solid fuel with unified gas purification as claimed in any one of  claims 6 - 9 , characterized in that the inactive chemical is mineral which has, at its base, metal carbonate or hydroxide. 
     
     
         11 . A gasifier for solid fuel with unified gas purification as claimed in any one of  claims 6 - 9 , characterized in that said reactor of gasified gas purification phase is larger in horizontal sectional area than said reactor of pyrolysis gasification phase. 
     
     
         12 . A gasifier for solid fuel with unified gas purification as claimed in any one of  claims 6 - 9 , characterized in that said reactor of gasified gas purification phase and said reactor of pyrolysis gasification phase are integrally arranged,
 a particle passage being arranged inside or outside of said integrated reactor of gasified gas purification phase and reactor of pyrolysis gasification phase so as to circulate said heat medium and active chemical from said reactor of gasified gas purification phase to said reactor of pyrolysis gasification phase.