Method of upgrading biomass, upgraded biomass, biomass water slurry and method of producing same, upgraded biomass gas, and method of gasifying biomass

Abstract

This method of upgrading a biomass comprises: an upgrading step for performing upgrading treatment of a cellulose based biomass with an oxygen / carbon atomic ratio of at least 0.5, in presence of water and under a pressure of at least saturated water vapor pressure, and reducing said oxygen / carbon atomic ratio of said biomass to no more than 0.38, and a separation step for separating an upgraded reactant obtained from said upgrading step into a solid component and a liquid component.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of upgrading a cellulose based biomass, a method of converting a cellulose based biomass into a slurry, and a method of gasifying upgraded biomass. BACKGROUND ART [0002] Slurries formed by crushing solid fuels such as coal and then adding water and additives are known as CWM or CWF (Coal Water Mixture / Coal Water Fuel), and are consequently attracting considerable attention as new fuels. [0003] From the viewpoint of handling, a slurry fuel requires a viscosity of no more than 1,500 mPa·s (rotary viscometer, 25° C., shear rate value of 100 [l / sec], these settings also apply below). Furthermore, with the demand in recent years for higher heating values and higher combustion efficiency, heating values of at least 16.5 MJ / kg (4,000 kcal / kg) are required. [0004] The increase in carbon dioxide gas emissions as a result of the huge consumption of fossil fuels is a significant cause of global warming, and is leading to increase...

AI Technical Summary

Benefits of technology

[0011] The inventors of the present invention discovered that by using a cellulose based biomass with an original oxygen / carbon atomic ratio of at least 0.5 as a raw material, and then upgrading the biomass to reduce this oxygen / carbon atomic ratio to no more than 0.38, a fuel having a superior quality can be stably produced with a high heating value for the solid component of the upgraded reactant of at least 25.1 MJ / kg (6,000 kcal / kg).

[0013] From an upgraded biomass of the present invention, a biomass water slurry having a heating value which is adequate as an alternative fuel to heavy oil or coal can be easily produced with a high solid fraction concentration. The upgraded biomass can be used as a solid fuel in the same manner as coal without further upgrading process, and can also be used as a soil conditioner or an adsorbent.

[0015] According to a method of producing a biomass water slurry of the present invention, a slurry with a high solid fraction concentration and a heating value which is adequate as an alternative fuel to heavy oil or coal, which does not lose slurry characteristics even on long term storage, and with a viscosity which enables transportation by pipe can be produced with good stability using a cellulose based biomass, which conventionally has not been effectively utilized, as the raw material.

[0017] A biomass water slurry of the present invention has a high solid fraction concentration, a heating value which is adequate as an alternative fuel to heavy oil or coal, and a viscosity which enables transportation by pipe. The slurry can be stored with good stability, and even if stored for extended periods, the solid fraction and liquid within the slurry will not separate.

[0018] A biomass water slurry of the present invention and a method of producing such a slurry can utilize, as a raw material, a biomass formed from cellulose products which are conventionally ineffectively used, including wood based biomass such as timber thinnings, wood scraps from wood processing such as sawdust, chips and mills ends, prunings from roadside trees, wood based waste from construction, bark, and driftwoods; biomass from grasses such as rice straw, wheat or barley straw and bagasse; as well as bamboo, bamboo grass, burdock and used paper. Accordingly, resources can be utilized more effectively, and non-fossil based renewable energy considered to produce zero carbon dioxide emissions can be obtained, providing an effective countermeasure against environmental problems such as increases in carbon dioxide gas emissions. Furthermore, because the ash content and the sulfur content are extremely low, the investment costs for combustion facilities can also be reduced.

[0021] According to a gasification method of the present invention, the quantity of oxygen supplied during direct oxidation can be reduced in comparison with the case in which a raw biomass is directly gasified, and the efficiency of the coolant gas can be improved. In addition, the concentration of H2 and CO, which represent the active ingredients within the gasified product which is generated, can also be increased.

Problems solved by technology

The increase in carbon dioxide gas emissions as a result of the huge consumption of fossil fuels is a significant cause of global warming, and is leading to increased pressure for reductions in carbon dioxide gas emissions.

However, the solid fraction concentration of the slurry reported by the University of North Dakota was no more than a maximum of approximately 48 mass %, and slurries of higher concentrations could not be produced.

If an attempt is made to increase the solid fraction concentration in order to increase the heating value, then the slurry solidifies and cannot be handled as a slurry.

In the case of a direct gasification of a biomass, if the reaction temperature is less than 800° C., then the quantities of tar, soot and char produced increase, and operation of the gasification furnace becomes difficult.

A further problem arose in that the concentration of H2 and CO, which represent the active ingredients within the targeted product gas, also decreases.

Furthermore, in a method in which a raw material biomass is crushed to form chips, because the production of chips smaller than a certain size is impossible, performing the gasification reaction within a pressurized system was problematic.

In addition, because the biomass cannot be reduced to small enough particles, the rate of the partial oxidation reaction by oxygen is slow.