JP2005206468A - Method for producing saccharides and solid fuel using biomass as raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing saccharides and a solid fuel from biomass with high efficiency and low energy. <P>SOLUTION: The method for producing the saccharides or the solid fuel from the biomass as a raw material comprises the following steps. a slurry concentration increasing step of preparing a low-concentration slurry in which the biomass is suspended in high-pressure water heated at 100-250°C, further adding the biomass to the slurry and preparing a high-concentration slurry, a hydrolyzing step of heating the high-concentration slurry at 250-350°C, increasing the pressure to not lower than the vapor pressure of water at the temperature, degrading the biomass and producing the saccharides, a cooling step of cooling the high-concentration slurry passing through the hydrolyzing step, a recovering step of recovering an aqueous solution from the high-concentration slurry cooled in the cooling step and a recovering step of separating the saccharides from the aqueous solution or recovering water-insoluble ingredients from the high-concentration slurry passing through the hydrolyzing step. The water-insoluble ingredients are dehydrated to produce the solid fuel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing saccharides and solid fuel using biomass as a raw material.

  Many technologies that use energy from waste biomass such as forest land residues, construction waste, rice straw, rice husk, livestock waste, sewage, and sewage sludge as raw materials have been proposed from the viewpoint of disposal site shortage countermeasures and the establishment of a recycling-oriented society. ing.

  One of the energy conversion technologies using biomass is a technology for extracting sugars and fuel from plant-derived biomass. For example, (1) acid hydrolysis, (2) enzymatic saccharification, (3) The critical water and supercritical water treatment methods have been proposed.

  The (1) acid hydrolysis method is a method in which a saccharide is obtained by solubilizing and hydrolyzing biomass using sulfuric acid, hydrochloric acid, organic acid, sulfurous acid or the like. This acid hydrolysis method has the merit that the reaction proceeds at a relatively low temperature of 150 to 200 ° C. and the reaction apparatus is simple. However, since the reaction uses an acid, the apparatus is significantly corroded. After the reaction, there is a problem that it is difficult to recover the acid.

  The (2) enzymatic saccharification method is a method for obtaining saccharides by hydrolyzing biomass with enzymes. This method is useful because it does not use chemicals and has a low environmental load, but it takes a long time to complete the reaction.

The (3) subcritical water and supercritical water treatment method is a method for obtaining saccharides and the like by hydrolyzing biomass by bringing it into contact with subcritical or supercritical water. For example, Patent Document 1 discloses a method in which cellulose powder is contacted with water in a subcritical state to hydrolyze to obtain a water-soluble oligosaccharide, and then the oligosaccharide is further enzymatically decomposed to obtain a monosaccharide. ing. As described above, the subcritical water and supercritical water treatment methods are excellent methods capable of obtaining saccharides in a short period of time because of the use of water as a solvent and a low environmental load.
JP-A-10-327900

  However, in order to utilize the properties of subcritical water and supercritical water, it is first necessary to suspend biomass in water to make a slurry. At this time, depending on the type of biomass to be used, a large amount of water may be required. In order to make this water into a subcritical or supercritical state, a large amount of energy must be input, and the biomass processing cost is reduced. There was a problem of rising.

  The present invention has been made paying attention to the above circumstances, and an object thereof is to provide a method for producing saccharides and solid fuel from biomass with high efficiency and low energy.

The method for producing saccharides and solid fuel using the biomass of the present invention as a raw material is to prepare a low-concentration slurry in which biomass is suspended in high-pressure water heated to 100 to 250 ° C., and further adding biomass to this slurry to obtain a high concentration (A) heating the high-concentration slurry to 250-350 ° C., and decomposing biomass to produce a saccharide by decomposing biomass above the vapor pressure of water at the temperature A hydrolysis step, a cooling step for cooling the high-concentration slurry that has undergone the hydrolysis step, a recovery step for recovering the aqueous solution from the high-concentration slurry cooled in the cooling step, and a separation step for separating saccharides from the aqueous solution are provided. However, or
(B) From the high-concentration slurry cooled in the cooling step, wherein the high-concentration slurry is heated to 250 to 350 ° C., and the biomass is hydrolyzed by setting the pressure to be equal to or higher than the vapor pressure of water at the temperature. The present invention is summarized in that a recovery step of recovering a water-insoluble component and a step of dehydrating the water-insoluble component to obtain a solid fuel are provided.

  In the high concentration step, the biomass is suspended in water at atmospheric pressure and less than 100 ° C. to form a low concentration slurry, and the low concentration slurry is heated to a temperature of 100 to 250 ° C. with stirring under pressure, Furthermore, it is preferable that biomass is added to increase the concentration of the slurry.

  In addition, it is recommended to use wood as the biomass.

  According to the method of the present invention, it becomes possible to prepare a high-concentration slurry in which a large amount of biomass above the conventional level is suspended, so that the amount of input energy when using energy conversion as a raw material is significantly reduced. It became possible to make it.

  In addition, it has become possible to efficiently obtain saccharides and solid fuel from biomass that has been treated as waste, most of which is woody biomass.

  When the present inventors decompose biomass using high-temperature / high-pressure water and convert it into energy, etc., under a predetermined condition, if biomass is added / mixed in multiple stages, a high-concentration slurry containing a large amount of biomass As a result, it has been found that useful materials can be produced with a small amount of energy input compared to conventional biomass processing technology, and the present invention has been completed. Hereinafter, the present invention will be described in detail.

  The method for producing saccharides according to the present invention comprises preparing a low-concentration slurry in which biomass is suspended in high-pressure water heated to 100 to 250 ° C. using biomass as a raw material, and further adding biomass to this slurry to form a high-concentration slurry. A step of increasing the concentration of the slurry to be prepared, a hydrolysis step of heating the high-concentration slurry to 250 to 350 ° C. and decomposing biomass by setting the pressure to be equal to or higher than the vapor pressure of water at the temperature to generate saccharides, It has the greatest features in that it includes a cooling step for cooling the high-concentration slurry that has undergone the decomposition step, a recovery step for recovering the aqueous solution from the high-concentration slurry cooled in the cooling step, and a separation step for separating saccharides from the aqueous solution. Is.

  When hydrolyzing biomass in this way, a high concentration slurry having a high biomass content is prepared in advance, so that a large amount of biomass can be treated at one time, and water that is the medium of the slurry. This makes it possible to significantly reduce the amount of energy required for heating and pressurizing to a subcritical or supercritical state.

  The biomass that can be used as a raw material in the method according to the present invention is not particularly limited, and woody biomass, wood fragments, chip dust, sawdust, sawdust, etc., woody biomass, coconut shell, sugarcane bagasse, straw, rice husk, etc. Various biomass such as agricultural biomass and waste biomass such as garbage can be used. Among the above biomass, it is preferable to use woody biomass from the viewpoint of effective use of resources. Examples of the timber pieces include building demolition waste, thinned wood generated during forest cutting, or pruned branches such as parks and roadside trees. As described above, according to the present invention, normally discarded biomass can be effectively used, so that problems such as treatment plants are solved and energy problems are also solved. Hereinafter, a case where woody biomass is used as biomass will be described as an example.

  The biomass is preferably used after being pulverized. The size is preferably in the range of 5 mesh (4000 μm: JIS Z8801) and 200 mesh (74 μm), more preferably in the range of 10 mesh (1680 μm) and 150 mesh (105 μm) with a standard sieve of Tyler. And more preferably in the range of 20 mesh (840 μm) and 100 mesh (149 μm). According to the knowledge of the present inventors, when the size of the biomass is so small that it passes through the sieve shown above as the lower limit, mechanical pulverization tends to be difficult, while the upper limit is exceeded. When it is large, the contact area between the biomass and water tends to be small, and as a result, the yield of saccharides tends to decrease.

  In the method of the present invention, first, the biomass and water are mixed to prepare a low-concentration slurry. What is necessary is just to determine the usage-amount of the wood used at this time suitably by the conditions at the time of processing, such as the kind of wood, and the quantity of the water to be used. However, as described above, since it is difficult to slurry a large amount of wood at a time, it is preferable to add it within a stirrable range while observing the state of the slurry. It is 1 mass% or more with respect to quantity, More preferably, it is 5 mass% or more.

  The water used in preparing the low-concentration slurry may be in a high temperature / high pressure state as described later, or in a normal temperature / normal pressure state. From the viewpoint of energy saving, it is preferable to prepare a low-concentration slurry under normal pressure of less than 100 ° C.

  Next, biomass is further added to the low concentration slurry to prepare a high concentration slurry (high concentration step). The addition of biomass is preferably performed after raising the temperature and pressure of the low-concentration slurry. At this time, the temperature of the low concentration slurry is preferably 100 ° C. or higher and 250 ° C. or lower. More preferably, it is 150 degreeC or more and 200 degrees C or less. This is because if the temperature is lower than the above temperature, the reaction between the biomass and water does not effectively occur, and it is difficult to increase the concentration of the slurry. On the other hand, when the temperature is higher than the above temperature, the decomposition of the biomass as the raw material proceeds excessively, and the saccharide recovery rate tends to eventually decrease.

  The pressure for increasing the concentration of the slurry is preferably not less than the vapor pressure of water at the treatment temperature. This is because when the pressure is lower than the vapor pressure, a liquid phase portion is not formed, and dispersion and solubilization of biomass does not proceed. For example, if the temperature of the slurry is 100 ° C., the pressure is preferably 0.11 MPa or more, if it is 150 ° C., 0.5 MPa or more, if 200 ° C., 1.6 MPa or more, 250 ° C. If it is, it is preferable to set it as 4.0 Mpa or more. The upper limit of the pressure is not particularly limited, and may be set as appropriate in consideration of the equipment used. From the viewpoint of reducing the load on a device such as a pump, it is preferable to employ a pressure close to the lower limit value at each temperature.

  The amount of biomass added at this time is 1% by mass or more, more preferably 5% by mass or more, based on the amount of water used.

  The biomass content in the high-concentration slurry having a high concentration as described above is preferably 10% by mass or more, more preferably 13% by mass or more, further preferably 15% by mass or more, and further 20% by mass. The above is desirable. This is because, when the biomass content is less than the above lower limit, it is possible to perform processing by a conventional method, and it is impossible to find the significance of applying the present invention to obtain sugar at high efficiency and low cost. In addition, the upper limit of biomass content will not be specifically limited if it is a grade which can maintain a slurry state.

  In the above description, the method of adding biomass in two stages and increasing the concentration of the slurry has been described. However, the present invention is not limited to the above description, and the biomass is increased in three or more stages to increase the concentration. It can also be applied to a slurry.

  Next, the high-concentration slurry prepared as described above is brought to a high temperature / high pressure state to hydrolyze biomass (hydrolysis step). The hydrolysis treatment is preferably performed at 250 ° C. or higher and 350 ° C. or lower under pressure. This is because, when the temperature is higher than the above upper limit value, thermal decomposition of saccharides and the like produced by the hydrolysis reaction is predominant rather than biomass decomposition, and the yield of the target saccharide is reduced. On the other hand, when the temperature is lower than the lower limit, the hydrolysis reaction tends to hardly proceed.

  The pressure at the time of hydrolysis is preferably not less than the vapor pressure at the temperature at the time of reaction. This is because it is difficult to maintain the liquid phase when the pressure is less than the vapor pressure at the temperature. For example, if the temperature of the water during the reaction is 250 ° C., the pressure may be 4.0 MPa or more, and if it is 350 ° C., the pressure may be 16.6 MPa or more.

  The hydrolysis reaction is preferably performed in less than 30 minutes.

  The high-concentration slurry is preferably rapidly cooled to 100 ° C. or less (preferably 30 to 70 ° C.) after the hydrolysis reaction (cooling step). By rapidly cooling the slurry in a high temperature state, the saccharide produced in the hydrolysis step can be prevented from being further decomposed by preheating.

  Next, the aqueous solution is recovered from the cooled high-concentration slurry (recovery step). The recovered aqueous solution contains components such as sugar produced in the hydrolysis step. The aqueous solution recovered here is further separated into a solid component and a liquid component, and saccharides are obtained from the liquid component.

  As mentioned above, although the method to manufacture the saccharide | sugar which concerns on this invention was described, this invention also aims at obtaining a solid fuel simultaneously with obtaining saccharide | sugar. That is, the solid fuel production method according to the present invention is similar to the above-described saccharide production method, in which a hydrolysis reaction is performed after preparing a high-concentration slurry using biomass as a raw material and suspending it in water. . And a water-insoluble component is collect | recovered from the high concentration slurry which passed through the hydrolysis process, and this is made into a solid fuel. This water-insoluble component is then sent to the dehydration step, where it can be used as a solid fuel after sufficiently reducing the water content. The water-insoluble component obtained at this time has a lower water content than the raw material biomass and has a high calorific value, so it can also be used as a coal substitute material, and is a solid for blowing into a blast furnace. It is also useful as a solid fuel for steam boilers used for fuel and power generation.

  Next, an apparatus for carrying out the method of the present invention will be described. FIG. 1 shows an apparatus diagram showing an example of an apparatus for carrying out a method for producing a saccharide or solid fuel according to the present invention.

  First, in FIG. 1, in the slurry maker 11, the biomass and water are mixed to prepare a low-concentration slurry, and then biomass is further added to prepare a high-concentration slurry. The obtained high-concentration slurry is discharged from the slurry production device 11 and supplied to the heating reactor 13 by the high-pressure pump 12. At this time, the high-concentration slurry may be supplied to the heating reactor 13 while maintaining the temperature and pressure in the high-concentration step, or may be supplied to the heating reactor 13 after being cooled once. Good. However, from the viewpoint of obtaining saccharides and the like with a smaller amount of energy input, it is preferable to supply to a heating reactor in which hydrolysis is performed while maintaining the temperature in the high concentration step.

  The heating reactor 13 is configured to be able to introduce and discharge slurry, and is provided with a heater 14 for raising the temperature to a temperature suitable for the hydrolysis treatment. The high-concentration slurry supplied to the heating reactor 13 is increased to a predetermined temperature and pressure in the heating reactor 13, and a hydrolysis reaction of biomass is performed. The temperature during the reaction is controlled by the heater 14, and the pressure is controlled by a high-pressure pump 12 provided between the slurry producing device 11 and the heating reactor 13, and a solid-liquid separation filter 18 described later. This is performed by a pressure holding valve 19 provided between the gas-liquid separator 20. That is, when the hydrolysis reaction is performed, the reaction pressure is set by the pressure holding valve 19, the inside of the heating reactor 13 is increased by the high-pressure pump 12, and the high-concentration slurry is heated by the heater 14. What is necessary is just to control so that the inside becomes more than the vapor pressure of the water in the said temperature.

  After completion of the reaction, the high-concentration slurry is discharged from the heating reactor 13, sent to the heat exchanger 16 to which the cooling unit 17 is attached, and cooled to 100 ° C. or lower. By quenching immediately after the hydrolysis treatment, hydrolysis products (oligosaccharides and monosaccharides) can be prevented from being further decomposed by preheating. Further, the heat recovered at this time can be reused in the heating process in the heating reactor 13 and the slurry producing device 11.

  Next, the cooled high-concentration slurry is separated into an aqueous solution and a water-insoluble component by a solid-liquid separation filter 18 provided on the downstream side of the heat exchanger 16. A plurality of filters used at this time may be arranged in parallel. When using multiple filters, the product solution is passed through one filter to separate the water-insoluble components, and the other filter collects the separated water-insoluble components for continuous processing. be able to.

  The above-mentioned filter is not essential for carrying out the method of the present invention. Instead of the filter, a tank (not shown) is provided on the downstream side of the pressure holding valve 19, and the hydrolysis is performed here. The high-concentration slurry that has undergone the process can be separated into a liquid component and a dehydrated water-insoluble component using a dehydrator (for example, a filter, a filter press, a belt press, a centrifugal dehydrator, or the like).

  The aqueous solution separated from the water-insoluble component passes through the pressure holding valve 19 and is sent to the gas-liquid separator 20. When the aqueous solution passes through the pressure holding valve 19, it is rapidly depressurized to the atmospheric pressure, and thus the low boiling point component dissolved in the aqueous solution is vaporized and appears as a gas. These aqueous solutions and gas components are separated in the gas-liquid separator 20, and the gas is recovered in the gas bag 22 and the liquid component is recovered in the liquid recovery unit 21.

  In addition, since the liquid component collect | recovered by the liquid collection | recovery part 21 is the state which the hydrolysis product diluted with water, it is preferable to concentrate useful components with a reverse osmosis membrane etc.

  On the other hand, the water-insoluble component separated by the solid-liquid separation filter 18 can be used as a solid fuel after being dehydrated. Since this solid fuel has a lower moisture content and higher calorific value than biomass, which is a raw material, it can be used as a steam boiler for power generation and blast furnace injection like coal. it can.

Hereinafter, the present invention will be described in more detail with reference to experimental examples. However, the following experimental examples are not intended to limit the present invention, and modifications and implementations without departing from the spirit of the present invention are all included in the technical scope of the present invention. The Hereinafter, “parts” means parts by mass.
[Experimental Example 1]
Low temperature slurry by mixing 100 parts of water and 6 parts of wood flour as biomass (range of 60-80 mesh, type: cedar) in the slurry maker 11 of the apparatus shown in FIG. (Biomass concentration: 5.6% by mass). This low-concentration slurry was heated to 200 ° C. under pressure (2 MPa) and heat-treated for 10 minutes. Thereafter, 6 parts of wood flour was further added to the slurry maker 11 to increase the concentration of the slurry (biomass concentration: 10.7% by mass).

  Next, the high-concentration slurry was continuously supplied under pressure (pressure: 10 MPa) to the tubular reactor 13 maintained at a temperature of 300 ° C. to hydrolyze the wood flour (average residence time: 10 minutes).

  Next, the saccharide-containing slurry was cooled to 60 ° C. by the heat exchanger 16, and then the slurry was separated into an aqueous solution in which the saccharide was dissolved and a water-insoluble component by the solid-liquid separation filter 18. When a small amount of the obtained aqueous solution was collected and analyzed by high performance liquid chromatography, it was confirmed that cellulose and / or hemicellulose, which are wood constituents, were hydrolyzed and sugars such as glucose and cellobiose were produced. .

Glucose 1.1 parts Cellobiose 0.5 parts Cellotriose 0.4 parts The obtained water-insoluble component was dehydrated and molded into a solid fuel. The calorific value of the obtained solid fuel was measured by the following method.

A calorimeter was used. The weighed solid fuel is burned in a pressure-resistant airtight container filled with oxygen, the amount of heat generated is transferred to a certain amount of water, the temperature rise of the water is measured, and the heat generated per kg of solid fuel The amount (J) was determined.
(Processing temperature: 300 ° C., calorific value of solid fuel: 2.80 × 10 ⁷ J / kg).
[Experiment 2]
A high-concentration slurry (biomass concentration: 10.7% by mass) prepared in the same manner as in Example 1 was continuously supplied to the tubular reactor 13 maintained at a temperature of 350 ° C. under pressure (pressure: 17 MPa). The wood flour was hydrolyzed (average residence time 3 minutes).

  After completion of the reaction, the obtained reaction solution was cooled to 60 ° C. by the heat exchanger 16, and then the slurry was separated into an aqueous solution in which saccharides were dissolved and a water-insoluble component by the solid-liquid separation filter 18. A small amount of the obtained aqueous solution was collected and analyzed in the same manner as in Experimental Example 1 above. The results are shown below.

Glucose 1.3 parts Cellobiose 0.4 parts Cellotriose 0.2 parts The obtained water-insoluble component was dehydrated and molded into a solid fuel, and the calorific value of this solid fuel was measured (treatment temperature: 350 ° C. , Solid fuel calorific value: 2.92 × 10 ⁷ J / kg).

  From the results of Experimental Examples 1 and 2, it can be seen that according to the method of the present invention, the slurry can be highly concentrated and sugars and solid fuel can be produced very efficiently.

It is an apparatus figure which shows an example of the apparatus which implements the method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Slurry manufacturing machine 12 High pressure pump 13 Reactor 14 Heater 16 Heat exchanger 17 Cooling unit 18 Solid-liquid separation filter 19 Pressure holding valve 20 Gas-liquid separator 21 Liquid recovery part 22 Gas bag

Claims (4)

A method for producing saccharides using biomass as a raw material,
A slurry concentration increasing step of preparing a low concentration slurry in which biomass is suspended in high pressure water heated to 100 to 250 ° C., and further adding biomass to the slurry to prepare a high concentration slurry,
A hydrolysis step in which the high-concentration slurry is heated to 250 to 350 ° C., and the pressure is set to be equal to or higher than the vapor pressure of water at the temperature to decompose biomass to produce saccharides;
A cooling step for cooling the high-concentration slurry that has undergone the hydrolysis step;
A recovery step of recovering the aqueous solution from the high-concentration slurry cooled in the cooling step; and
A method for producing a saccharide, comprising a separation step of separating the saccharide from the aqueous solution. A method for producing a solid fuel using biomass as a raw material,
A slurry high concentration step of preparing a low concentration slurry in which biomass is suspended in high pressure water heated to 100 to 250 ° C., adding biomass to this slurry to prepare a high concentration slurry,
A hydrolysis step of heating the high-concentration slurry to 250 to 350 ° C. and hydrolyzing biomass by setting the pressure to be equal to or higher than the vapor pressure of water at the temperature;
A cooling step for cooling the high-concentration slurry that has undergone the hydrolysis step;
A recovery step of recovering a water-insoluble component from the high-concentration slurry cooled in the cooling step; and
A method for producing a solid fuel, comprising a step of dehydrating the water-insoluble component into a solid fuel.   After the high concentration step is under atmospheric pressure and less than 100 ° C., the biomass is suspended in water to form a low concentration slurry, and this low concentration slurry is heated to a temperature of 100 to 250 ° C. with stirring under pressure. Furthermore, biomass is added and the said slurry is made high concentration, The manufacturing method of Claim 1 or 2. The manufacturing method according to claim 1, wherein the biomass is wood.

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