JP7212837B1 - Semi-carbonized fuel production method and semi-carbonized fuel production apparatus - Google Patents

Abstract

A method for producing semi-carbonized fuel and an apparatus for producing semi-carbonized fuel are provided that make it possible to semi-carbonize woody biomass more efficiently. A method for producing semi-carbonized fuel by semi-carbonizing woody biomass (1), comprising the steps of storing said woody biomass (1) in a heating furnace (10), and semi-carbonizing said woody biomass (1) by irradiating microwaves on said woody biomass (1). A heat insulating material 15 is provided on the inner wall of the heating furnace 10, and the frequency band of the microwave is 2.45 GHz. [Selection drawing] Fig. 1

Description

The present invention relates to a semi-carbonized fuel production method and a semi-carbonized fuel production apparatus.

From the viewpoint of carbon neutrality, there is known a technique for co-firing a few percent of woody biomass instead of coal in a coal-fired power plant. However, since woody biomass has a smaller calorific value than coal and is inferior in crushability, it is technically difficult to improve the mixing ratio of woody biomass.

On the other hand, there is a semi-carbonization technology as a processing technology aimed at improving the drawbacks of woody biomass described above and using it as a fuel equivalent to coal (see Patent Document 1). Semi-carbonization technology is a technology that aims at both dissipation of moisture and suppression of energy loss by stopping heating before woody biomass is carbonized. For example, methods of increasing the temperature of the object to be heated by heat transfer from the outside, such as heating with high-temperature gas generated by burning fuel, are widely used. There is concern that this may occur.

Japanese Patent No. 3837490 Japanese Patent No. 6344988

Microwave heating, which is a heating method using electric power, can be mentioned as a semi-carbonization technique that suppresses the generation of carbon dioxide. Patent Document 2 discloses a technique for semi-carbonizing woody biomass using microwave heating, but it requires processes such as crushing, drying, mixing with charcoal, and pressure molding, and the process is complicated. Besides, it requires a lot of energy. Therefore, a method for semi-carbonizing woody biomass more efficiently is desired.

The present invention has been made in view of such circumstances, and provides a method for producing semi-carbonized fuel and an apparatus for producing semi-carbonized fuel, which makes it possible to semi-carbonize woody biomass more efficiently. for the purpose.

(1) In order to achieve the above objects, the present invention has taken the following measures. That is, the method for producing semi-carbonized fuel of the present invention is a method for producing semi-carbonized fuel by semi-carbonizing woody biomass, comprising the steps of storing the woody biomass in a heating furnace and applying microwaves to the woody biomass. and a step of irradiating to semi-carbonize, and a heat insulating material is provided inside the heating furnace.

Since the heat insulating material is provided inside the heating furnace, the woody biomass can be efficiently heated. This reduces the energy required for torrefaction and reduces costs.

(2) In addition, in the method for producing semi-carbonized fuel described in (1) above, the frequency band of the microwave is 2.45 GHz band.

The 2.45 GHz band, which is the frequency band used in many microwave ovens, can directly act on water molecules to heat them. Therefore, since the frequency band of microwaves is the 2.45 GHz band, woody biomass can be semi-carbonized by microwave irradiation without drying in advance.

(3) In the method for producing semi-carbonized fuel according to (1) or (2) above, the heating furnace has a nested structure of an outer wall in contact with the outside and an inner wall for storing the woody biomass, In the semi-carbonizing step, the gas flows into the inner wall, and the gas generated by heating flows out from between the outer wall and the inner wall.

As a result, the gas can be circulated inside the heating furnace, and heating by the gas can be performed in addition to microwave irradiation. Therefore, the woody biomass can be efficiently heated and semi-carbonized efficiently as compared with the case of heating only by microwave irradiation. In addition, since it becomes easy to remove water vapor, wood gas, pyroligneous acid, and wood tar generated from woody biomass, semi-carbonized fuel suitable for coal-fired power generation can be produced.

(4) Further, in the method for producing torrefaction fuel according to any one of (1) to (3) above, in the torrefaction step, electric power supplied by renewable energy is used to generate the microwave. It is characterized by generating

In recent years, the development of photovoltaic power generation has progressed, and in 2018, output control was performed for the first time in Japan in Kyushu, and in April 2019, about 130 million kWh of power was controlled. This is because the demand for electricity is low during periods when the amount of power generated by photovoltaic power generation is high, so the power generated by photovoltaic power generation is left over.

By using the electric power to produce the semi-carbonized fuel during periods when the electric power demand is low, the electric power generated by the photovoltaic power generation can be effectively utilized.

(5) Further, a semi-carbonized fuel production apparatus of the present invention is an apparatus for producing semi-carbonized fuel by semi-carbonizing woody biomass, comprising: a microwave oscillator for generating microwaves; A heating furnace for semi-carbonizing the woody biomass by microwaves is provided, and a heat insulating material is provided inside the heating furnace.

Since the heat insulating material is provided inside the heating furnace, the woody biomass can be efficiently heated. This reduces the energy required for torrefaction and reduces costs.

(6) In the apparatus for producing semi-carbonized fuel described in (5) above, the frequency band of microwaves generated by the microwave oscillator is 2.45 GHz.

The 2.45 GHz band, which is the frequency band used in many microwave ovens, can directly act on water molecules to heat them. Therefore, since the frequency band of microwaves is the 2.45 GHz band, woody biomass can be semi-carbonized by microwave irradiation without drying in advance.

(7) In the apparatus for producing torrefaction fuel according to (5) or (6) above, the heating furnace has a nested structure of an outer wall in contact with the outside and an inner wall for storing the woody biomass, Gas flows into the inner wall, and gas generated by heating flows out from between the outer wall and the inner wall.

As a result, the gas can be circulated inside the heating furnace, and heating by the gas can be performed in addition to microwave irradiation. Therefore, the woody biomass can be efficiently heated and semi-carbonized efficiently as compared with the case of heating only by microwave irradiation. In addition, since it becomes easy to remove water vapor, wood gas, pyroligneous acid, and wood tar generated from woody biomass, semi-carbonized fuel suitable as fuel for coal-fired power generation can be produced.

(8) Further, in the apparatus for producing semi-carbonized fuel described in (5) to (7) above, the heating furnace is provided with a transport mechanism for transporting the woody biomass in and out. .

As a result, the woody biomass can be automatically carried in and out by applying a belt conveyor or a screw inside the heating furnace, so that the woody biomass can be efficiently semi-carbonized.

According to the present invention, woody biomass can be semi-carbonized more efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram showing an example of the configuration of a semi-carbonized fuel production apparatus according to a first embodiment of the present invention; 1 is a flow chart showing an example of a method for producing semi-carbonized fuel according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram showing an example of the configuration of a semi-carbonized fuel production apparatus according to a second embodiment of the present invention. FIG. 5 is a conceptual diagram showing an example of the configuration of a semi-carbonized fuel production apparatus according to a modification of the second embodiment of the present invention. FIG. 4 is a conceptual diagram showing an example of the configuration of a semi-carbonized fuel production apparatus according to a modification of the first embodiment of the present invention; FIG. 4 is a diagram showing wood before heating in a microwave oven; FIG. 3 shows wood after heating in a microwave oven;

An embodiment of the present invention will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same components in each drawing, and overlapping descriptions are omitted. In addition, in the configuration diagram, the size of each component is conceptually represented, and does not necessarily represent the actual size ratio.

[First embodiment]
[Device for producing semi-carbonized fuel]
FIG. 1 is a conceptual diagram showing the configuration of a semi-carbonized fuel production apparatus according to the present invention. The semi-carbonized fuel production apparatus 100 heats the woody biomass 1 by irradiating it with microwaves, and stops the heating before carbonization, thereby obtaining semi-carbonized fuel in which the woody biomass 1 is semi-carbonized.

The woody biomass 1 refers to biomass derived from wood. Specifically, wood left over from sawmills, wood generated from construction, unused thinned wood, and the like can be mentioned, but wood harvested for use as fuel in power plants is particularly preferable. Waste materials from sawmills, etc. are leftover materials such as bark and sawdust and lumber scraps generated at sawmills. Unused thinned timber refers to cut thinned timber, end trees, branches, and roots that are left in the forest without being used among timber cut by thinning or main cutting. The woody biomass 1 may be crushed or dried in advance, but it is not necessary.

A semi-carbonized fuel production apparatus 100 includes a heating furnace 10 , a microwave oscillator 20 , a waveguide 30 , a solar power generation 40 , and a gas circulation facility 50 .

The heating furnace 10 has an inner wall 11 capable of storing the woody biomass 1 and an outer wall 12 provided at a certain distance from the inner wall 11 and having an outer surface in contact with the outside. is provided. That is, the inner wall 11 and the outer wall 12 have a nested structure. The heating furnace 10 may be provided with, for example, a hinged door so that the woody biomass 1 can be directly stored inside the inner wall 11 . Further, since the upper portion of the inner wall 11 of the heating furnace 10 is open, the space surrounded by the inner wall 11 and the space surrounded by the outer wall 12 communicate with each other.

The heat insulating material 15 may be made of a material that transmits microwaves but does not allow heat to escape. Examples thereof include alumina fiber and foamed alumina. In addition, the position where the heat insulating material 15 is provided may be provided not only on the inner surface of the inner wall 11, but also on the bottom surface or the top surface, or may be provided only on the bottom surface or the top surface, but may be provided only on the inner surface. It is preferable to provide Further, the heat insulating material 15 may be provided in the shape of a box inside the inner wall 11 without being directly provided on the inner wall 11 . Alternatively, it may be provided between the outer wall 12 and the inner wall 11 or inside the outer wall 12 . The point is that the heat insulating material 15 should be provided inside the heating furnace 10 .

The microwave oscillator 20 uses the supplied power to generate microwaves. Moreover, the microwaves generated by the microwave oscillator 20 are configured to irradiate the woody biomass 1 . The power supplied to the microwave oscillator 20 is preferably power generated by photovoltaic power generation, but may be power generated by other methods.

The frequency band of the microwaves generated by the microwave oscillator 20 is preferably the 2.45 GHz band. The 2.45 GHz band, which is the frequency band used in many microwave ovens, can directly act on water molecules to heat them. Therefore, by setting the microwave frequency band to the 2.45 GHz band, it is expected that woody biomass can be easily semi-carbonized by microwave irradiation without drying in advance.

Waveguide 30 is a hollow metal tube for transmitting microwaves. The microwaves generated by the microwave oscillator 20 are transmitted into the heating furnace 10 through the waveguide 30 and irradiated to the woody biomass 1 .

A solar power generator 40 powers the microwave oscillator 20 . Photovoltaic power generation may be any facility capable of generating electricity using sunlight, such as a solar panel. Moreover, the photovoltaic power generation 40 may not be provided in the semi-carbonized fuel manufacturing apparatus 100, and may be independent as an external facility. Furthermore, power may be supplied to the microwave oscillator 20 not only by photovoltaic power generation but also by renewable energy utilizing natural forces such as wind power generation and geothermal power generation.

The gas circulation equipment 50 is equipment for circulating gas in the heating furnace 10 . The gas circulation equipment 50 is composed of an inflow pipe 51 , an outflow pipe 52 and a steam valve 55 . The gas circulation equipment 50 discharges the gas generated by heating through the outflow pipe 52, and reintroduces the recovered wood gas such as carbon dioxide through the inflow pipe 51 to make the furnace oxygen-deficient. Furthermore, by supplying warm gas from the inflow pipe 51 and letting cold gas flow out from the outflow pipe 52, it is possible to heat the woody biomass 1 not only with microwaves but also with gas.

The inflow pipe 51 is a hollow pipe that supplies gas to the space surrounded by the inner wall of the heating furnace 10 . Therefore, it must be provided at a position where the gas can be supplied to the space surrounded by the inner wall of the heating furnace 10, and is more preferably provided on the lower surface of the heating furnace 10 as shown in FIG. When the gas flowing in from the inflow pipe 51 is warm, the warm gas moves from bottom to top. Therefore, by providing the inflow pipe 51 on the lower surface of the heating furnace 10 , the woody biomass 1 can be uniformly heated by the gas flowing in from the inflow pipe 51 . Note that the inflow pipe 51 does not necessarily have to be provided on the lower surface of the heating furnace 10, but it is preferably provided at least on the lower surface. At least the lower part means "the part located below the center of the heating furnace 10".

The outflow pipe 52 is a hollow pipe through which the gas staying inside the heating furnace 10 flows out. The outflow pipe 52 may be provided at a position where the gas staying inside the heating furnace 10 can flow out, but it should be provided at a position where the gas staying in the space surrounded by the inner wall 11 and the outer wall 12 can flow out. is preferred. Moreover, it is preferable not only to be located at a position where the gas remaining in the space surrounded by the inner wall 11 and the outer wall 12 can flow out, but also to be provided on the lower surface of the heating furnace 10 as shown in FIG. It should be noted that, like the inflow pipe 51, the outflow pipe does not necessarily have to be provided on the bottom surface of the heating furnace 10, and may, for example, extend horizontally from the bottom of the side surface. Since the cold air stays below, the gas staying in the space surrounded by the inner wall 11 and the outer wall 12 can flow out. gas can escape.

The steam valve 55 discharges steam, wood gas, pyroligneous acid, and wood tar from the gas discharged from the outflow pipe 52 . By venting the steam via the steam valve 55, the moisture content in the semi-carbonized fuel is reduced. Since the calorific value decreases as the moisture content increases, it is possible to produce semi-carbonized fuel suitable for coal-fired power generation by suppressing the moisture content. Also, wood vinegar and wood tar can be recovered from the steam valve 55 . On the other hand, by re-supplying the wood gas discharged from the steam valve 55 into the heating furnace 10, the inside of the furnace can be made into an oxygen-deficient atmosphere.

Moreover, the gas circulation equipment 50 is preferably configured so that the inflow pipe 51 is warmed by external heat. In particular, it is preferable that the inflow pipe 51 is warmed by factory exhaust heat. As a result, the exhaust heat from the factory can be effectively used to heat the gas supplied to the inside of the heating furnace.

[Method for producing semi-carbonized fuel]
Next, a method for producing semi-carbonized fuel will be described below. FIG. 2 is a flow chart showing an example of a method for producing semi-carbonized fuel.

First, woody biomass is stored in a space surrounded by inner walls of a heating furnace (step S1). Then, the woody biomass is semi-carbonized by irradiating the woody biomass with microwaves generated from the microwave oscillator 20 and circulating the gas in the heating furnace (step S2). It is possible to semi-carbonize woody biomass by stopping heating by microwaves and gas before carbonization.

[Second embodiment]
Next, a second embodiment of the invention will be described. The second embodiment differs from the first embodiment in that it has a transport mechanism inside the heating furnace and that it does not have a gas circulation facility, but otherwise has the same configuration.

FIG. 3 shows an apparatus for producing semi-carbonized fuel in the second embodiment. The semi-carbonized fuel production apparatus 200 shown in FIG. configured to

The semi-carbonized fuel production apparatus 200 includes an inlet 61 through which the woody biomass 1 can be introduced into the heating furnace, and an outlet 62 through which the semi-carbonized woody biomass 1 can be discharged. The input port 61 is provided in the upper part of the heating furnace 10 and configured so that the input woody biomass 1 is arranged at one end of the transport mechanism 60 . A discharge port 62 is provided in the lower portion of the heating furnace 10 and enables the woody biomass 1 conveyed by the conveying mechanism 60 to be discharged.

The transport mechanism 60 is a mechanism capable of horizontally transporting the woody biomass 1 input from the inlet 61 toward the outlet 62 . The conveying mechanism 60 may be any mechanism capable of horizontally conveying in one direction, and although a screw is depicted as the conveying mechanism 60 in FIG. 3, it may be a belt conveyer as shown in FIG. Also, the transport mechanism 60 may be a roller conveyor, a chain conveyor, or the like.

Further, the semi-carbonized fuel manufacturing apparatus 200 of FIG. Specifically, a microwave oscillator 20 is provided above the heating furnace 10 , and a waveguide 30 is provided between the microwave oscillator 20 and the top surface of the heating furnace 10 . Further, it is preferable that the microwave is irradiated near the center of the transport mechanism 60 . As a result, microwaves are transmitted from the top surface of the heating furnace 10 toward the inside, so that the woody biomass 1 is semi-carbonized while being transported by the transport mechanism 60 .

Further, in the semi-carbonized fuel manufacturing apparatus 200 of FIG. The heat insulating material 15 may be provided on all of the top surface and bottom surface of the heating furnace 10, but is preferably provided only at positions where microwaves are particularly present. As a result, the cost of manufacturing the semi-carbonized fuel manufacturing apparatus 200 can be reduced.

In the first embodiment, the microwave oscillator 20 is provided on the side surface of the heating furnace, and in the second embodiment, the microwave oscillator 20 is provided on the top surface of the heating furnace 10. , the microwave oscillator 20 may be provided at any portion of the heating furnace 10 . Also, the heat insulating material may be provided at a position where heat can be efficiently transferred to the woody biomass 1 according to the position where the microwave oscillator 20 is provided and the structure of the heating furnace.

Further, the transport mechanism 60 is not limited to the second embodiment, and may be applied to the first embodiment shown in FIG. At this time, it is desirable to provide an inlet so that the woody biomass 1 does not enter between the inner wall 11 and the outer wall 12 . For example, as shown in FIG. 5, it is effective to provide an inlet 61 at a position penetrating the opening of the inner wall 11 or to provide a partition 63 between the inlet 61 and the inner wall 11 . It is preferable that the partition 63 is provided with pores so as to allow gas to pass through but prevent woody biomass 1 from entering.

It goes without saying that the present invention is not limited to the above-described embodiments, but extends to various modifications and equivalents within the spirit and scope of the present invention. Also, the structure, shape, number, position, size, etc. of the constituent elements shown in each drawing are for convenience of explanation, and may be changed as appropriate.

[Example]
The present inventor heated wood using a microwave oven in order to verify the effect of the heat insulating material by irradiating the wood with microwaves while the wood was covered with the heat insulating material.
The items used for verification are as follows.
Microwave: YAMAZEN YRT-S177 (W) 5
Insulation: Alumina fiber

Figure 6 shows the wood before heating. As shown in FIG. 6, wood of the same size and shape was prepared, wrapped in a heat insulating material and heated in a microwave oven as an example, and a comparative example was heated without being wrapped in a heat insulating material. bottom. The lumber before heating had a diameter of about 5 mm and a length of about 30 mm. Heating with a microwave oven was performed at 500 W for 5 minutes.

FIG. 7 shows the wood after heating. The wood on the right side of the page is an example, and the wood on the left side of the page is a comparative example. As shown in FIG. 7, the wood in Example is blackened, indicating that it is semi-carbonized or carbonized. On the other hand, in the comparative example, the color of the wood did not change, and it appeared that it was semi-carbonized or not carbonized. From the above, it is considered that woody biomass can be semi-carbonized with a small amount of electric power by using a heat insulating material.

1 Woody Biomass 10 Heating Furnace 11 Inner Wall 12 Outer Wall 15 Heat Insulating Material 20 Microwave Oscillator 30 Waveguide 40 Photovoltaic Power Generation 50 Gas Circulation Equipment 51 Inflow Pipe 52 Outflow Pipe 55 Steam Valve 60 Transport Mechanism 61 Inlet 62 Outlet 63 Partition 100 , 200 Apparatus for producing semi-carbonized fuel

Claims (7)

A method for producing semi-carbonized fuel by semi-carbonizing woody biomass,
storing the woody biomass in a furnace;
at least a step of semi-carbonizing the woody biomass by irradiating it with microwaves;
The heating furnace has an outer wall that contacts the outside and an inner wall that stores the woody biomass, and has a nested structure in which a part of the inner wall is open and a space surrounded by the inner wall communicates with a space surrounded by the outer wall. A heat insulating material is provided inside the heating furnace ,
A method for producing semi-carbonized fuel , wherein in the semi-carbonizing step, gas is circulated in the heating furnace . A method for producing semi-carbonized fuel by semi-carbonizing woody biomass,
storing the woody biomass in a furnace;
at least a step of semi-carbonizing the woody biomass by irradiating it with microwaves;
The heating furnace includes an outer wall that contacts the outside and an inner wall that stores the woody biomass, the outer wall and the inner wall have a nested structure, and a heat insulating material is provided inside the inner wall ,
A method for producing semi-carbonized fuel , wherein in the semi-carbonizing step, gas is circulated in the heating furnace . 2. The gas is circulated in the heating furnace by causing gas to flow into the interior of the inner wall and causing gas generated by heating to flow out from between the outer wall and the inner wall. Or the method for producing semi-carbonized fuel according to claim 2. An apparatus for producing semi-carbonized fuel by semi-carbonizing woody biomass,
a microwave oscillator for generating microwaves;
a heating furnace for semi-carbonizing the woody biomass by microwaves generated by the microwave oscillator;
The heating furnace has an outer wall that contacts the outside and an inner wall that stores the woody biomass, and has a nested structure in which a part of the inner wall is open and a space surrounded by the inner wall communicates with a space surrounded by the outer wall. A heat insulating material is provided inside the heating furnace ,
An apparatus for producing semi-carbonized fuel, further comprising gas circulation equipment for circulating gas in the heating furnace . An apparatus for producing semi-carbonized fuel by semi-carbonizing woody biomass,
a microwave oscillator for generating microwaves;
a heating furnace for semi-carbonizing the woody biomass by microwaves generated by the microwave oscillator;
The heating furnace includes an outer wall that contacts the outside and an inner wall that stores the woody biomass, the outer wall and the inner wall have a nested structure, and a heat insulating material is provided inside the inner wall ,
An apparatus for producing semi-carbonized fuel, further comprising gas circulation equipment for circulating gas in the heating furnace . The gas circulation equipment circulates the gas in the heating furnace by causing gas to flow into the inner wall and causing gas generated by heating to flow out from between the outer wall and the inner wall. 6. The apparatus for producing semi-carbonized fuel according to claim 4 or 5 . 6. The apparatus for producing semi - carbonized fuel according to claim 4 , wherein the heating furnace is internally provided with a transport mechanism for transporting the woody biomass in and out.

Images