Method and System for Hydrolytic Saccharification of a Cellulosic Biomass

Abstract

A method and system for hydrolyzing cellulose and/or hemicellulose contained in a biomass into monosaccharides and oligosaccharides by using high-temperature and high-pressure water in a subcritical condition is provided. In hydrolyzing cellulose or hemicellulose into saccharides by using high-temperature and high-pressure water in a subcritical condition, a large amount of slurry is cooled into a condition below the subcritical condition by subjecting the slurry contained in a pressure vessel under a high-temperature and high-pressure condition to flash evaporation in a pressure vessel charged with a slurry of a cellulosic biomass and heated halfway. It is possible to prevent saccharides from degrading into organic acids and to save energy by recovery of thermal energy. The cellulosic biomass is charged into a water-permeable vessel and then the water-permeable vessel is encapsulated into the pressure vessel together with water.

1 . A method of hydrolytic saccharification of a cellulosic biomass with use of plural pressure vessels, the method comprising a charging step, a heating-up step, a hydrolyzing step, a temperature lowering step, and a discharging step, which are performed sequentially by each of said pressure vessels, wherein:
 said charging step is a step of charging a slurry prepared by grinding said cellulosic biomass and then mixing said cellulosic biomass thus ground with water into each of said pressure vessels;   said heating-up step is a step of hermetically closing the pressure vessel and heating up said slurry;   said hydrolyzing step is a step of hydrolyzing cellulose and/or hemicellulose contained in said cellulosic biomass into saccharides by an oxidative power of high-temperature and high-pressure water;   said temperature lowering step is a step of flash-evaporating the high-temperature and high-pressure slurry contained in the pressure vessel to lower the temperature thereof;   said discharging step is a step of removing the slurry out of the pressure vessel;   while any one of said plural pressure vessels performs said charging step, any one of the other pressure vessels performs said discharging step so as to allow heat exchange to occur between the slurry to be charged into the pressure vessel performing the charging step and the slurry to be discharged from the pressure vessel performing said discharging step; and   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing the temperature lowering step to the pressure vessel performing the heating-up step.   
     
     
         2 . A method of hydrolytic saccharification of a cellulosic biomass with use of plural pressure vessels, the method comprising a charging step, a heating-up step, a hydrolyzing step, a temperature lowering step, and a discharging step, which are performed sequentially by each of said pressure vessels, wherein:
 said charging step is a step of charging said cellulosic biomass into a water-permeable vessel and then encapsulating said water-permeable vessel and water into each of said pressure vessels;   said heating-up step is a step of hermetically closing the pressure vessel and heating up said cellulosic biomass and water;   said hydrolyzing step is a step of hydrolyzing cellulose and/or hemicellulose contained in said cellulosic biomass into saccharides by an oxidative power of high-temperature and high-pressure water;   said temperature lowering step is a step of flash-evaporating high-temperature and high-pressure water contained in the pressure vessel to lower the temperature thereof;   said discharging step is a step of removing said water and said water-permeable vessel out of said pressure vessel;   while any one of said plural pressure vessels performs said charging step, any one of the other pressure vessels performs said discharging step no as to allow heat exchange to occur between water to be charged into the pressure vessel performing said charging step and high-temperature water to be discharged from the pressure vessel performing said discharging step; and   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing said temperature lowering step to the pressure vessel performing said heating-up step.   
     
     
         3 . The method according to  claim 1 , wherein equal time is required to complete respective of all the five steps and the number of the pressure vessels used is a multiple of five. 
     
     
         4 . The method according to  claim 1 , wherein: equal time is required to complete respective of all the four steps other than said hydrolyzing step; the time required to complete said hydrolyzing step is n times (where n is a natural number) as long as the time required to complete each of the other four steps; and the number of the pressure vessels used is a multiple of (4+n). 
     
     
         5 . The method according to  claim 1 , wherein said hydrolyzing step is performed at a temperature of not lower than 140° C. and not higher than 180° C. to hydrolyze hemicellulose into saccharides. 
     
     
         6 . The method according to  claim 2 , wherein said hydrolyzing step is performed at a temperature of not lower than 140° C. and not higher than 180° C. to hydrolyze hemicellulose into saccharides. 
     
     
         7 . The method according to  claim 5 , wherein: the slurry resulting from said discharging step is subjected to solid-liquid separation; a slurry comprising a solid content obtained after dissolution of hydrolyzed hemicellulose in water is prepared; the slurry obtained after the solid-liquid separation is subjected to said charging step again; and said hydrolyzing step is performed at a temperature of not lower than 240° C. and not higher than 280° C. to hydrolyze cellulose into saccharides. 
     
     
         8 . The method according to  claim 6 , wherein said water-permeable vessel having been subjected to said discharging step is subjected to said charging step again and said hydrolyzing step is performed at a temperature of not lower than 240° C. and not higher than 280° C. to hydrolyze cellulose into saccharides. 
     
     
         9 . The method according to  claim 1 , wherein said hydrolyzing step is performed at a temperature of not lower than 240° C. and not higher than 280° C. to hydrolyze cellulose into saccharides. 
     
     
         10 . The method according to  claim 1 , wherein said charging step includes addition of ethanol in an amount of not less than 2 mol % and not more than 10 mol % to the raw slurry. 
     
     
         11 . The method according to  claim 2 , wherein said charging step includes addition of ethanol in an amount of not less than 2 mol % and not more than 10 mol % to said water. 
     
     
         12 . A method of hydrolytic saccharification of a cellulosic biomass with use of plural pressure vessels, the method comprising a discharging and charging step, a heating-up step, a hydrolyzing step, and a temperature lowering step, which are performed sequentially by each of said pressure vessels, wherein:
 said discharging and charging step is a step of removing a slurry out of each of said pressure vessels after said temperature lowering step and charging a slurry prepared by grinding said cellulosic biomass and mixing said cellulosic biomass thus ground with water into the same pressure vessel;   said heating-up step is a step of hermetically closing the pressure vessel and heating up the pressure vessel;   said hydrolyzing step is a step of hydrolyzing cellulose and/or hemicellulose contained in said cellulosic biomass into saccharides by an oxidative power of high-temperature and high-pressure water;   said temperature lowering step is a step of flash-evaporating the high-temperature and high-pressure slurry contained in the pressure vessel to lower the temperature thereof; and   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing the temperature lowering step to the pressure vessel performing the heating-up step.   
     
     
         13 . A method of hydrolytic saccharification of a cellulosic biomass with use of plural pressure vessels, the method comprising a discharging and charging step, a heating-up step, a hydrolyzing step, and a temperature lowering step, which are performed sequentially by each of said pressure vessels, wherein:
 said discharging and charging step is a step of removing a cellulosic biomass residue out of each of said pressure vessels after said temperature lowering step and encapsulating water and a water-permeable vessel charged with said cellulosic biomass into the same pressure vessel;   said heating-up step is a step of hermetically closing the pressure vessel and heating up the pressure vessel;   said hydrolyzing step is a step of hydrolyzing cellulose and/or hemicellulose contained in said cellulosic biomass into saccharides by an oxidative power of high-temperature and high-pressure water;   said temperature lowering step is a step of flash-evaporating high-temperature and high-pressure water contained in the pressure vessel to lower the temperature thereof; and   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing said temperature lowering step to the pressure vessel performing said heating-up step.   
     
     
         14 . The method according to  claim 12 , wherein equal time is required to complete respective of all the four steps and the number of the pressure vessels used is a multiple of four. 
     
     
         15 . The method according to  claim 12 , wherein: equal time is required to complete respective of all the three steps other than said hydrolyzing step; the time required to complete said hydrolyzing step is n times (where n is a natural number) as long as the time required to complete each of the other three steps; and the number of the pressure vessels used is a multiple of (3+n). 
     
     
         16 . The method according to  claim 12 , wherein said hydrolyzing step is performed at a temperature of not lower than 140° C. and not higher than 180° C. to hydrolyze hemicellulose into saccharides. 
     
     
         17 . The method according to  claim 13 , wherein said hydrolyzing step is performed at a temperature of not lower than 140° C. and not higher than 180° C. to hydrolyze hemicellulose into saccharides. 
     
     
         18 . The method according to  claim 16 , wherein: the slurry resulting from said discharging and charging step is subjected to solid-liquid separation; a slurry comprising a solid content obtained after dissolution of hydrolyzed hemicellulose in water is prepared; the slurry obtained after the solid-liquid separation is subjected to said discharging and charging step again; and said hydrolyzing step is performed at a temperature of not lower than 240° C. and not higher than 280° C. to hydrolyze cellulose into saccharides. 
     
     
         19 . The method according to  claim 17 , wherein said water-permeable vessel having been subjected to said discharging step is subjected to said charging step and said hydrolyzing step is performed at a temperature of not lower than 240° C. and not higher than 280° C. to hydrolyze cellulose into saccharides. 
     
     
         20 . The method according to  claim 12 , wherein said hydrolyzing step is performed at a temperature of not lower than 240° C. and not higher than 280° C. to hydrolyze cellulose into saccharides. 
     
     
         21 . The method according to  claim 12 , wherein said discharging and charging step includes addition of ethanol in an amount of not less than 2 mol % and not more than 10 mol % to the raw slurry. 
     
     
         22 . The method according to  claim 13 , wherein said discharging and charging step includes addition of ethanol in an amount of not less than 2 mol % and not more than 10 mol % to water to be encapsulated into the pressure vessel. 
     
     
         23 . A system for hydrolytic saccharification of a cellulosic biomass, comprising plural pressure vessels each configured to perform sequential steps including:
 a charging step of charging a slurry prepared by grinding said cellulosic biomass and then mixing said cellulosic biomass thus ground with water into the pressure vessel;   a heating-up step of hermetically closing the pressure vessel and heating up the pressure vessel;   a hydrolyzing step of hydrolyzing cellulose and/or hemicellulose contained in said cellulosic biomass into saccharides by an oxidative power of high-temperature and high-pressure water;   a temperature lowering step of flash-evaporating the high-temperature and high-pressure slurry contained in the pressure vessel to lower the temperature thereof; and   a discharging step of removing the slurry out of the pressure vessel, wherein:   while any one of said plural pressure vessels performs said charging step, any one of the other pressure vessels performs said discharging step no as to allow heat exchange to occur between the slurry to be charged into the pressure vessel performing said charging step and the slurry to be discharged from the pressure vessel performing said discharging step; and   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing said temperature lowering step to the pressure vessel performing said heating-up step.   
     
     
         24 . A system for hydrolytic saccharification of a cellulosic biomass, comprising plural pressure vessels each configured to perform sequential steps including:
 a charging step of encapsulating water and a water-permeable vessel charged with said cellulosic biomass into the pressure vessel;   a heating-up step of hermetically closing the pressure vessel and heating up the pressure vessel;   a hydrolyzing step of hydrolyzing cellulose and/or hemicellulose contained in said cellulosic biomass into saccharides by an oxidative power of high-temperature and high-pressure water;   a temperature lowering step of flash-evaporating high-temperature and high-pressure water contained in the pressure vessel to lower the temperature thereof; and   a discharging step of removing a residue of said cellulosic biomass out of the pressure vessel, wherein:   while any one of said plural pressure vessels performs said charging step, any one of the other pressure vessels performs said discharging step so as to allow heat exchange to occur between water to be charged into the pressure vessel performing said charging step and high-temperature water to be discharged from the pressure vessel performing said discharging step; and   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing said temperature lowering step to the pressure vessel performing said heating-up step.   
     
     
         25 . The system according to  claim 23 , wherein equal time is required to complete respective of all the five steps and the number of the pressure vessels used is a multiple of five. 
     
     
         26 . The system according to  claim 23 , wherein: equal time is required to complete respective of all the four steps other than said hydrolyzing step; the time required to complete said hydrolyzing step is n times (where n is a natural number) as long as the time required to complete each of the other four steps; and the number of the pressure vessels used is a multiple of (4+n). 
     
     
         27 . A system for hydrolytic saccharification of a cellulosic biomass, comprising plural pressure vessels each configured to perform sequential steps including:
 a discharging and charging step of removing a slurry out of the pressure vessel after a temperature lowering step and charging a slurry prepared by grinding said cellulosic biomass and then mixing said cellulosic biomass thus ground with water into the same pressure vessel;   a heating-up step of hermetically closing the pressure vessel and heating up the pressure vessel;   a hydrolyzing step of hydrolyzing cellulose and/or hemicellulose contained in said biomass into saccharides by an oxidative power of high-temperature and high-pressure water; and   the temperature lowering step of flash-evaporating the high-temperature and high-pressure slurry contained in the pressure vessel to lower the temperature thereof, wherein   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing said temperature lowering step to the pressure vessel performing said heating-up step.   
     
     
         28 . A system for hydrolytic saccharification of a cellulosic biomass, comprising plural pressure vessels each configured to perform sequential steps including:
 a discharging and charging step of removing a cellulosic biomass residue out of the pressure vessel after a temperature lowering step and encapsulating water and a water-permeable vessel charged with said cellulosic biomass into the pressure vessel;   a heating-up step of hermetically closing the pressure vessel and heating up the pressure vessel;   a hydrolyzing step of hydrolyzing cellulose and/or hemicellulose contained in said cellulosic biomass into saccharides by an oxidative power of high-temperature and high-pressure water; and   the temperature lowering step of flash-evaporating high-temperature and high-pressure water contained in the pressure vessel to lower the temperature thereof, wherein   while any one of said plural pressure vessels performs said heating-up step, any one of the other pressure vessels performs said temperature lowering step and allows heat recovery to be made by supplying flash vapor discharged from the pressure vessel performing said temperature lowering step to the pressure vessel performing said heating-up step.   
     
     
         29 . The system according to  claim 27 , wherein equal time is required to complete respective of all the four steps and the number of the pressure vessels used is a multiple of four. 
     
     
         30 . The system according to  claim 27 , wherein: equal time is required to complete respective of all the three steps other than said hydrolyzing step; the time required to complete said hydrolyzing step is n times (where n is a natural number) as long as the time required to complete each of the other three steps; and the number of the pressure vessels used is a multiple of (3+n).