Biomass hydrothermal decomposition system and saccharide-solution production method using biomass material

1. A biomass hydrothermal decomposition system comprising:

a biomass feeding unit that feeds a biomass material containing cellulose, hemicellulose, and lignin under a normal pressure to put it under an increased pressure;

a hydrothermal decomposition unit that hydrothermally decomposes the biomass material by pressurized hot water and dissolves a lignin component and a hemicellulose component in the pressurized hot water, the hydrothermal decomposition unit including a hot-water effluent outlet from which a hot-water effluent containing the lignin component and the hemicellulose component is discharged;

a biomass solid discharging unit that discharges a biomass solid from the hydrothermal decomposition unit;

a slurrying vessel comprising:

a biomass solid inlet that communicates with the biomass solid discharging unit and introduces the biomass solid;

a water inlet that introduces water; and

an outlet that discharges a slurried biomass solid composed of the introduced water and the introduced biomass solid;

a first saccharification tank that is provided downstream of the slurrying vessel and saccharifies the slurried biomass solid with a first enzyme so as to produce a first saccharide solution;

a hot-water effluent feed line that communicates with the hot-water effluent outlet of the hydrothermal decomposition unit; and

a second saccharification tank that saccharifies the hot-water effluent with a second enzyme via the hot-water effluent feed line so as to produce a second saccharide solution,

wherein the biomass solid inlet is provided at an upper portion of the slurrying vessel, and the outlet is provided at a lower portion of the slurrying vessel, so that the biomass hydrothermal decomposition system is configured to provide a liquid seal between a gas-liquid interface of the slurried biomass solid in the slurrying vessel and a gas-liquid interface of hot water of the hydrothermal decomposition unit, and

wherein the biomass hydrothermal decomposition system further comprises:

a first solid-liquid separation device that is provided downstream of the first saccharification tank and separates a first solid residual liquid containing lignin from the first saccharide solution; and

a second solid-liquid separation device that is provided downstream of the second saccharification tank and separates a second solid residual liquid containing lignin from the second saccharide solution

wherein the biomass hydrothermal decomposition system further comprises a pH measuring device provided downstream of the slurrying vessel, the pH measuring device measures pH in the slurried biomass solid, and

wherein the biomass hydrothermal decomposition system is configured to, on a basis of the measured pH, control at least one of the following:

(i) a feed amount of the pressurized hot water;

(ii) a feed amount of the biomass material;

(iii) a conveying rate of the biomass material by a screw means;

(iv) a liquid level of the gas-liquid interface of the hydrothermal decomposition unit; and

(v) a discharge amount of the hot-water effluent.

2. The biomass hydrothermal decomposition system according to claim 1 , wherein

the hydrothermal decomposition unit transports the biomass material fed thereto from a lower side to an upper side in an apparatus body by transportation unit, feeds the pressurized hot water from an upper side different from a feed position of the biomass material into the apparatus body, performs hydrothermal decomposition while bringing the biomass material into countercurrent contact with the pressurized hot water, and transfers a hot-water soluble component into the hot-water effluent, thereby separating the lignin component and the hemicellulose component from the biomass material.

3. The biomass hydrothermal decomposition system according to claim 1 , further comprising:

a first water separation device that is provided downstream of the first solid-liquid separation device and removes water from the first saccharide solution; and

a second water separation device that is provided downstream of the second solid-liquid separation device and removes water from the second saccharide solution.

4. The biomass hydrothermal decomposition system according to claim 3 , further comprising:

a second return line for recycling the water separated by the first water separation device or a second water separation device to either one or both of the slurrying vessel and a cooling unit of temperature adjustment unit of the hydrothermal decomposition apparatus.

5. The biomass hydrothermal decomposition system according to claim 3 , wherein

the water separated by the first water separation device a second water separation device is made to be pressurized hot water by pressurization and heating unit, and a third return line for recycling the pressurized hot water to the pressurized hot water of the hydrothermal decomposition apparatus is provided.

6. The biomass hydrothermal decomposition system according to claim 5 , further comprising:

a biological treatment device in the first return line, a second return line, or a third return line, wherein the biological treatment device is a methane fermentation biological treatment device that performs a biological treatment on a reaction inhibiting substance contained in water and recovers methane.