JP7558508B2 - Wood fuel production system and method - Google Patents

Description

The present invention relates to a wood fuel production system and method.

In recent years, attempts have been made to effectively use waste wood as fuel (see, for example, Patent Document 1).

Patent No. 4998959

Examples of biomass power generation methods that use wood as fuel include the direct combustion method, in which biomass fuel is burned in a boiler to generate steam to drive a steam turbine, and the pyrolysis gas method, in which the fuel is heat-treated to gasify it and drive a gas turbine. In the direct combustion method, biomass fuel is burned in a combustion furnace, and the heat is used to turn the water in the boiler into steam to drive a steam turbine. Therefore, the direct combustion method is adopted in large-scale facilities with a power generation capacity of about several MW in order to achieve a commercial value for the thermal energy conversion efficiency. On the other hand, the pyrolysis gas method heats biomass fuel in a gasification furnace to generate gases such as methane, and the generated gas drives a gas engine or gas turbine. Therefore, the pyrolysis gas method can achieve a commercial value for the thermal energy conversion efficiency even when adopted in a small facility of about several tens of kW.

When using wood as fuel for biomass power generation, if the wood contains a lot of moisture, the temperature inside the combustion furnace or gasification furnace drops, which reduces the thermal energy conversion efficiency of the entire system. For this reason, to use wood as fuel for biomass power generation, it is necessary to convert the moisture contained in the wood into high-quality wood fuel by sufficiently reducing it before putting it into the furnace. For example, the moisture content of green wood is usually around 50-65%, but to use it in a biomass generator that uses pyrolysis gas, the moisture content needs to be reduced to around 15%.

Wood is pyrolyzed and gasified at temperatures of about 300°C or higher, but the lignin contained in the cell walls of plants recombines and becomes denatured tar when the temperature drops below about 500°C after gasification (some literature states that the pyrolysis temperature of wood is about 180°C). For this reason, if the temperature of the combustion furnace or gasification furnace is low, denatured tar accumulates in the furnace and inhibits combustion and gasification. The inhibition of combustion and gasification due to the accumulation of denatured tar leads to various problems such as generator stoppages, reduced power generation efficiency, increased frequency of furnace replacement, and increased maintenance costs. Therefore, in biomass generators that use wood fuel, it is possible to raise the inside of the furnace to about 1000°C or higher to prevent malfunctions caused by the recombination of lignin. However, raising the temperature inside the furnace causes problems with the durability of the furnace. For this reason, there is a demand for wood that is less likely to accumulate denatured tar inside the furnace even if the temperature inside the furnace is not raised.

In order to solve these problems, it is conceivable to dehydrate the wood used in biomass power generation by, for example, heating and drying it, or by applying pressure with a piston. However, in the case of heat drying, it takes a long time to dry the wood to the moisture content level described above, and heat drying of the wood consumes heat energy that can be used for hot water supply and air conditioning. In addition, in the case of applying pressure with a piston, continuous processing is difficult because pressure cannot be applied without reciprocating the piston, and when pressure is released, moisture that seeps out of the wood is absorbed back into the wood as the compressed wood restores its volume, resulting in poor dehydration efficiency.

Therefore, the objective of this application is to provide a wood fuel production system and method for biomass power generation that can efficiently dehydrate wood.

To solve the above problem, the present invention involves compressing wood, the raw material for fuel, with rollers.

In detail, the present invention is a wood fuel production system for biomass power generation, which includes a drying device that dries wood, the raw material for fuel, to a predetermined dryness level that allows it to be fed into the furnace of a biomass power generation facility, and a squeezing device that extracts moisture contained in the wood sent to the drying device by squeezing it with rollers that can continuously apply pressure to the wood.

In the above wood fuel production system, the wood is compressed by the rollers of the compression device, and the moisture remaining in the wood's ducts is dehydrated by squeezing. The wood dehydrated in the compression device is then dried in the drying device. Dehydration by compression using rollers can be completed in an extremely short time compared to dehydration by heating, for example. Therefore, dehydration by compression using rollers consumes less energy than dehydration by heating. Therefore, the above wood fuel production system makes it possible to dehydrate wood efficiently.

The compression device may have an inlet through which wood cut into strips can be fed in the direction of the conduit. In a wood fuel production system having such a compression device, moisture remaining in the wood's conduits is squeezed out of the conduits by the compression of rollers along the longitudinal direction of the conduits, making it possible to dehydrate the wood even more efficiently.

The compression device may also have a first roller that compresses the wood from above and a second roller that compresses the wood from below. A wood fuel production system with such a compression device can compress the wood from above and below with the rollers, making it possible to continuously and efficiently dehydrate the wood.

The rollers may have an outer surface that comes into contact with the wood made of iron. A pressing device using such rollers can efficiently extract the lignin contained in the wood in addition to dehydrating the wood.

The rollers may also have at least one of protrusions and grooves on their outer circumferential surface. A pressing device using such rollers can extract lignin contained in wood more efficiently.

The pressing device may also be one that efficiently removes lignin from wood by continuously pressing the wood with rollers.

The present invention can also be viewed from the perspective of a method. For example, the present invention may be a method for producing wood fuel for biomass power generation, which includes a drying process in which wood, which is a raw material for fuel, is dried to a predetermined dryness level that allows it to be fed into a furnace of a biomass power generation facility, and a squeezing process in which moisture contained in the wood sent to the drying process is extracted by squeezing the wood with rollers that can continuously apply pressure to the wood.

The above-described system and method for producing wood fuel for biomass power generation makes it possible to efficiently dehydrate wood.

FIG. 1 is a diagram showing a wood fuel production system according to an embodiment. FIG. 2 is a diagram showing the internal configuration of the compression device. FIG. 3 is the first diagram illustrating the dehydration process in the compression device. FIG. 4 is a second diagram illustrating the dehydration process in the compression device. FIG. 5 shows electron microscopic images of the structural changes in wood before and after dehydration in a compression device. FIG. 6 is an image showing the structural changes of wood before and after dehydration in a compression device. FIG. 7 shows electron microscope images of the end grain surface of wood before and after dehydration in a compression device. FIG. 8 is a table verifying the difference in the compressing effect when wood and wood chips are compressed using a compression device. FIG. 9 is a diagram showing a modified example of the front guide. FIG. 10 is a diagram illustrating variations in the shape of the squeezing surfaces of the upper roller, the front roller, and the rear roller. FIG. 11 is a table showing the amount of lignin extracted by the pressing device. FIG. 12 is a microscopic image capturing the antiviral effect against influenza virus.

The following describes an embodiment of the present invention. The embodiment described below is an example of one embodiment of the present invention, and does not limit the technical scope of the present invention to the following form.

Figure 1 shows a wood fuel production system 1 according to an embodiment. The wood fuel production system 1 is a system for producing wood fuel for biomass power generation from wood, and includes a compression device 2 and a drying device 3. The compression device 2 compresses wood, which is the raw material for wood fuel for biomass power generation, to squeeze out the moisture contained in the wood. The drying device 3 dries the wood compressed in the compression device 2.

The wood fed into the compression device 2 can be in the form of rods cut into strips, wood chips cut into small pieces of about a few centimeters, or in various other forms. For example, as shown in Figure 1, the wood fed into the compression device 2 is waste wood generated during the process of sawing wood at sawmills 4 located throughout the country.

The wood fuel production system 1 of this embodiment supplies the produced wood fuel to a biomass generator 5. As the biomass generator 5, various types of generators capable of generating electricity using wood fuel can be used. Specific examples of the biomass generator 5 include a pyrolysis gas type biomass generator that heats biomass fuel in a gasification furnace to generate gases such as methane, and uses the generated gas to drive a gas engine or gas turbine, and a direct combustion type biomass generator that burns biomass fuel in a combustion furnace and uses the heat to turn boiler water into steam to drive a steam turbine.

1 illustrates three sawmills 4 for one wood fuel production system 1, but the wood fuel production system 1 is not limited to this configuration. The wood fuel production system 1 may, for example, receive wood sent from two or fewer sawmills 4, or may receive wood sent from four or more sawmills 4. Furthermore, the wood fuel production system 1 is not limited to a configuration in which wood fuel is sent to one biomass generator 5, but may, for example, send wood fuel to multiple biomass generators 5.

Figure 2 is a diagram showing the internal configuration of the compression device 2. As shown in Figure 2, the compression device 2 is a compression device equipped with an upper roller 21, a front roller 22, and a rear roller 23. The upper roller 21 is a roller for compressing the wood input into the input port 2A from above. The front roller 22 and the rear roller 23 are rollers for compressing the wood input into the input port 2A from below. The compression device 2 squeezes the wood input into the input port 2A by sandwiching it between the upper roller 21 and the front roller 22, and further squeezes it by sandwiching it between the upper roller 21 and the rear roller 23, thereby dehydrating the wood input into the input port 2A. The compression device 2 may be equipped with, for example, two rollers or four or more rollers.

The upper roller 21, the front roller 22, and the rear roller 23 are rotated by an electric motor via a power transmission mechanism such as gears. The pressing surfaces (outer peripheral surfaces) of the upper roller 21, the front roller 22, and the rear roller 23 may be provided with teeth or grooves for winding in the wood fed into the feed opening 2A. Details of the shapes of the pressing surfaces of the upper roller 21, the front roller 22, and the rear roller 23 will be described later.

In addition to the above, the compression device 2 is provided with an upper guide 24 and a front guide 25 for forming the inlet 2A. The upper guide 24 is a member that forms the guide surface of the upper part of the inlet 2A. The front guide 25 is a member that forms the guide surface of the lower part of the inlet 2A. Since the compression device 2 is provided with such an upper guide 24 and a front guide 25, when a rod-shaped piece of wood is input into the inlet 2A and wound between the upper roller 21 and the front roller 22, even if the part of the wood before being wound moves up and down, the range of movement is limited to a certain range by the upper guide 24 and the front guide 25. In addition, the upper guide 24 is arranged so that the guide surface for the wood is inclined slightly upwards more than the front guide 25. Therefore, the size of the opening surface of the inlet 2A gradually increases toward the opening direction, making it easy to input wood.

In addition, the pressing device 2 is provided with a front scraper 26 between the front roller 22 and the rear roller 23 for scraping off wood that is pressed onto the pressing surface of the front roller 22. The front scraper 26 also serves to guide the wood that has passed between the upper roller 21 and the front roller 22 toward the space between the upper roller 21 and the rear roller 23.

In addition, the pressing device 2 is provided with an upper scraper 27 for scraping off wood that is pressed onto the pressing surface of the upper roller 21, located at a position behind the upper roller 21 when viewed from the inlet 2A. The upper scraper 27 also serves to guide the wood that has passed between the upper roller 21 and the rear roller 23 so that it heads diagonally downward from the outlet 2B.

In addition, the pressing device 2 is provided with an upper scraper 27 for scraping off wood stuck to the pressing surface of the rear roller 23, located at the rear side of the rear roller 23 when viewed from the inlet 2A. The rear scraper 28 also serves to guide the wood that has passed between the upper roller 21 and the rear roller 23 so that it is placed on the rear guide 29, which forms a guide surface, so that the wood is directed diagonally downward from the outlet 2B.

In addition to the above, the compression device 2 is equipped with an adjustment mechanism for finely adjusting the height of the upper roller 21. The adjustment mechanism is a manual adjustment mechanism having a screw for fine adjustment. The adjustment mechanism is equipped with a spring, and when an excessively thick piece of wood is fed into the feed opening 2A, the spring is compressed, causing the upper roller 21 to move upward.

Figure 3 is the first diagram explaining the dehydration process in the compression device 2. When the electric motor of the compression device 2 is started, the upper roller 21, the front roller 22, and the rear roller 23 rotate. Therefore, as shown in Figure 3 (A), when wood 6 is input into the input port 2A while the compression device 2 is operating, the wood 6 is pulled between the upper roller 21 and the front roller 22. The gap between the upper roller 21 and the front roller 22 is adjusted by the adjustment mechanism so that it is narrower than the thickness of the wood 6. Therefore, when the wood 6 is pulled between the upper roller 21 and the front roller 22, it is compressed. Then, as shown in Figure 3 (B), the wood 6 is also pulled between the upper roller 21 and the rear roller 23 and further compressed, and exits from the discharge port 2B. The wood 6 dehydrated by the compression device 2 is discharged from the discharge port 2B thinner than before dehydration, as shown in Figure 3 (C). The amount of adjustment in the adjustment mechanism depends on the thickness of the wood 6 (approximately 5 to 50 mm) and the type of wood, but it is desirable to adjust it so that a pressure of 15 MPa or more is applied to the wood 6, for example.

Figure 4 is the second diagram explaining the dehydration process in the compression device 2. The compression device 2 can dehydrate not only rod-shaped wood 6 as shown in Figure 3, but also wood chips 7 cut into pieces of about 5 cm in size. When dehydrating wood chips 7, for example, as shown in Figure 4 (A), the wood chips 7 are fed into the inlet 2A while the compression device 2 is operating. The wood chips 7 are then drawn between the upper roller 21 and the front roller 22 and compressed. As shown in Figure 4 (B), the wood chips 7 are also drawn between the upper roller 21 and the rear roller 23 and further compressed, and exit from the outlet 2B. The wood chips 7 dehydrated by the compression device 2 are then discharged from the outlet 2B in a smaller size than before dehydration, as shown in Figure 4 (C). As mentioned above, the pressing device 2 is equipped with a front scraper 26, so even small pieces such as wood chips 7 can be dewatered without falling between the front roller 22 and the rear roller 23.

Figure 5 shows the structural changes in wood before and after dehydration in a compression device, captured by an electron microscope. Figure 6 is an image showing the structural changes in wood before and after dehydration in a compression device. As can be seen from Figures 5 and 6, the lignin that was trapped inside the cellulose before compression flows out of the cellulose when the cellulose is mechanically broken by the pressure of the rollers. The lignin that has flowed into the gaps in the wood fibers then moves in a direction that corresponds to the direction of rotation of the rollers, and is discharged from the end grain surface, etc.

Figure 7 shows the end grain of wood captured by an electron microscope before and after dehydration in the compression device 2. As can be seen from Figure 7 (A), before dehydration in the compression device 2, the xylem fibers that form the wood are honeycomb-shaped, and conduits are formed to transport the moisture absorbed from the roots to the branches and leaves. Therefore, before dehydration, moisture remains in these conduits.

As can be seen from FIG. 7(B), the wood fibers that make up the wood are deformed from a honeycomb shape to a square shape after dehydration in the compression device 2, but the vessels themselves are not destroyed. Therefore, the compression device 2 can be said to be a device that compresses the vessels by compressing the wood 6 and wood chips 7, and discharges the moisture remaining in the vessels from the end openings of the vessels at the buttock surface. Therefore, in order to efficiently discharge the moisture in the vessels by compression in the compression device 2, it is preferable to feed the wood so that the feeding direction is along the longitudinal direction of the vessels. Therefore, although the compression device 2 can also dehydrate the wood chips 7 as shown in FIG. 4, when focusing on the efficiency of dehydration, it is presumed that the dehydration method shown in FIG. 3, that is, feeding the rod-shaped wood 6 along the longitudinal direction of the wood 6 (the longitudinal direction of the vessels) is preferable.

Figure 8 is a table verifying the difference in the compression effect when wood 6 and wood chips 7 are compressed with the compression device 2. As can be seen from the results of "Roller Compressor 1" in Figure 8, when wood chips 7 were compressed, the amount of moisture extracted from the wood chips 7 in the first dehydration was only a small amount, 0.33% by weight of the wood. Therefore, a second dehydration was attempted, but only 2.22% was extracted.

On the other hand, when strip-shaped wood 6 was compressed, the amount of moisture extracted from wood 6 in the first dehydration was 13.27% by weight of the wood. The dimensions of wood 6 were width 100 mm, thickness 10 mm, and length 1000 mm. When a second dehydration attempt was made, the amount was 0.32%. This is presumably because most of the moisture that could be dehydrated by the compression device 2 was dehydrated in the first run.

As can be seen from the results of the "Roller Compressor 2" in Figure 8, tests were also conducted in which the amount of wood chips 7 was increased and two types of wood 6 with alternating thicknesses were prepared. The dimensions of "Rectangular Board A" in Figure 8 are width 100 mm, thickness 10 mm, and length 1000 mm. On the other hand, the dimensions of "Rectangular Board B" are width 100 mm, thickness 15 mm, and length 1000 mm. It was confirmed that wood 6 can be dehydrated more efficiently than wood chips 7, even when the amount of wood chips 7 was increased or the thicknesses were alternating.

Although not shown in the figure, a comparative test was also conducted between a roll-type compressor such as the compression device 2 of this embodiment and a piston-pressure press. However, when using the press, almost no moisture was extracted from the wood chips. This may be due to insufficient pressure applied to the wood chips, but it is believed that the main cause is that the extracted moisture was reabsorbed due to the wood chips regaining their bulk when the piston was contracted. In addition, piston-pressure presses are batch-type machines in order to replace the wood chips, and cannot continuously input wood like the compression device 2 of this embodiment. For this reason, it can be said that the compression device 2 of this embodiment, which uses rollers, can dehydrate wood extremely efficiently compared to piston-pressure presses.

Even if the wood chips 7 are not rectangular boards like the wood 6, the wood chips 7 can be fed into the compression device 2 so that the longitudinal direction of the conduit is aligned with the feeding direction by, for example, modifying the front guide 25 as described below. Figure 9 shows a modified version of the front guide 25. Figure 9 shows the compression device 2 as viewed from above.

In this modified example, it is assumed that the wood chips 7 are cut into rectangular parallelepipeds. It is also assumed that the wood chips 7 are cut into rectangular parallelepipeds with their longitudinal direction aligned with the conduit. In this modified example, the front guide 25 has a loading surface 25A on which the wood chips 7 are loaded, a front inclined surface 25B that forms a downward slope from the loading surface 25A, and a rear inclined surface 25C that has a downward slope and enters the inlet 2A from the front inclined surface 25B. The front inclined surface 25B and the rear inclined surface 25C are provided with guide walls 25D that align the orientation of the wood chips 7 so that the longitudinal direction of the wood chips 7 is aligned with the loading direction. Therefore, the wood chips 7 loaded in an appropriate orientation on the loading surface 25A are aligned by the guide walls 25D and are loaded into the inlet 2A. Therefore, the compression device 2 can efficiently dehydrate wood, even if it is a small piece of wood such as the wood chips 7, in the same way as wood 6.

In the wood fuel production system 1, wood dehydrated by the compression device 2 is dried in the drying device 3. In the drying device 3, the wood is dried by heating. An example of a heating means is heat generated by burning fuel. In the drying device 3, the wood is dried until it reaches a dryness level at which it can be fed into the furnace of the biomass generator 5 (an example of the "predetermined dryness" in this application), for example, until it reaches a moisture content of about 15%. In the wood fuel production system 1,
Since the wood is dehydrated in the compression device 2 before being dried in the drying device 3, the drying time in the drying device 3 is shortened, and the amount of heat energy consumed in the drying device 3 is reduced. Therefore, the heat energy consumed in drying the wood can be effectively utilized for other facilities, such as hot water supply and air conditioning.

In addition, in the wood fuel production system 1, lignin contained in wood can also be extracted by dehydration in the compression device 2. Lignin is recognized to have efficacy as an agricultural chemical that prevents plant diseases and as a medicine that has antitumor effects. Lignin is one of the main components that make up the cell walls of plants and is contained in lignocellulose. Therefore, in order to extract lignin, a process for extracting lignin from lignocellulose is required, and it is not easily extracted by ordinary compression. However, recent research has found that one method of efficiently extracting lignin from lignin-containing materials such as lignocellulose is to bring the lignin-containing material into contact with iron ions. Therefore, in the compression device 2, the compression surfaces of the upper roller 21, front roller 22, and rear roller 23 are made of iron, making it possible to efficiently extract lignin from wood.

Figure 10 is a diagram illustrating variations in the shape of the pressing surface of the upper roller 21, the front roller 22, and the rear roller 23. For example, as shown in Figure 10 (A), the pressing device 2 may have an iron upper roller 21 with spiral projections or grooves on the outer circumferential surface, and iron front roller 22 and rear roller 23 with smooth outer circumferential surfaces without projections or grooves. As shown in Figure 10 (B), the pressing device 2 may have an iron front roller 22 and rear roller 23 with linear projections or grooves on the outer circumferential surface. As shown in Figure 10 (C), the pressing device 2 may have an iron front roller 22 with grooves or projections corresponding to the projections or grooves on the upper roller 21, and projections or grooves that go around the outer circumferential surface. As shown in Figure 10 (C), the pressing device 2 may have an upper roller 21, a front roller 22, and a rear roller 23 with grooves or projections of other shapes.

When the outer peripheral surfaces of the iron upper roller 21, front roller 22, and rear roller 23 are provided with such various types of protrusions and grooves, the contact area of the outer peripheral surface that comes into contact with the lignocellulose is increased compared to when the outer peripheral surfaces are smooth. Thus, by compressing in the compression device 2, the lignocellulose comes into contact with the iron ions of each roller, and lignin can be efficiently extracted. In addition, such protrusions and grooves on the outer peripheral surfaces of the rollers can also have the function of chopping wood fed into the feed port 2A into wood chips of a size suitable for use in the biomass generator 5 (for example, about 20 to 50 mm).

Figure 11 is a table showing the amount of lignin extracted by the compression device 2. As can be seen from the table in Figure 11, lignin can be extracted efficiently when wood is compressed using a compression device 2 having an iron upper roller 21, front roller 22, and rear roller 23. In particular, it can be seen that when rectangular pieces of wood 6 as shown in Figure 3 are fed into the compression device 2, lignin can be extracted extremely efficiently compared to when wood chips 7 as shown in Figure 4 are fed into the compression device 2.

As described above, the wood fuel production system 1 of this embodiment not only reduces the amount of thermal energy consumed for heating in the drying device 3 by the compression device 2, but also makes it possible to extract lignin from wood in the compression device 2. Therefore, the wood fuel production system 1 of this embodiment not only makes it possible to efficiently produce wood fuel for biomass power generation, but also makes it possible to extract lignin, which has been recognized for its various efficacies, from wood in the compression device 2.

An experiment was conducted to verify the efficacy of lignin extract extracted from wood, and the results are shown below. In this verification experiment, the efficacy of lignin extract extracted by squeezing rectangular boards with the wood fuel production system 1 was verified. Lignin extract has been recognized to have various efficacies, but in this verification experiment, the antiviral effect was verified. The verification experiment was conducted using influenza virus PR8 [A/PUERTORICO/8/34 (H1N1)]. Canine renal tubular epithelial cells (MDCK cells) were used as the cells to be infected with the virus strain, and the experiment was conducted with a virus titer of TCID ₅₀ =2.8×10 ⁵ /ml.

In the experiment, a solution of lignin extracted from strips of wood with an equal amount to the virus was reacted at room temperature for 30 minutes, and then adsorbed to MDCK cells in a 96-well plate at 37°C and 5% _CO2 for 45 minutes. After that, 100 μl of infection medium was added to each well, and the cells were cultured at 37°C and 5% _CO2 to observe the cytopathic effect. FIG. 12 is a microscopic image capturing the antiviral effect against influenza virus. As can be seen from FIG. 12, degeneration of MDCK cells was observed due to virus infection in the control group (Ultrapure water), but no degeneration was observed in the lignin solution (1%, 5%) using the lignin extract extracted by squeezing the strips of wood, and the antiviral effect was confirmed. From this result, it can be seen that the lignin extract extracted by squeezing the strips of wood with the wood fuel production system 1 exerts an antiviral effect against influenza virus.

Reference Signs List 1 Wood fuel production system 2 Pressing device 21 Upper roller 22 Front roller 23 Rear roller 24 Upper guide 25 Front guide 25A Placement surface 25B Front inclined surface 25C Rear inclined surface 25D Guide wall 26 Front scraper 27 Upper scraper 28 Rear scraper 29 Rear guide 2A Inlet 2B Discharge outlet 3 Drying device 4 Sawmill 5 Biomass generator 6 Wood 7 Wood chips

Claims (4)

A wood fuel production system for biomass power generation, comprising:
A drying device that dries the wood, which is the raw material for the fuel, to a predetermined dryness level that allows it to be fed into a furnace of a biomass power generation facility;
A compression device that extracts moisture contained in the wood to be sent to the drying device by compressing the wood with a roller that can continuously pressurize the wood ,
The compression device is
The wood is compressed from above by an upper roller, a front roller that compresses the wood from below before the upper roller, and a rear roller that compresses the wood from below after the upper roller,
The wood is fed in a rod-like state along the longitudinal direction, which is the direction of the conduit, and the wood is folded and squeezed by the upper roller between the front roller and the rear roller.
Wood fuel production system. At least one of the rollers has an outer circumferential surface that comes into contact with the wood and is made of iron.
The wood fuel production system of claim 1 . Each of the rollers has at least one of a protrusion and a groove provided on the outer circumferential surface.
The wood fuel production system according to claim 2 . A method for producing wood fuel for biomass power generation, comprising:
A drying process for drying the wood, which is a raw material for the fuel, to a predetermined dryness level that allows the wood to be fed into a furnace of a biomass power generation facility;
A squeezing step in which moisture contained in the wood to be sent to the drying step is extracted by squeezing the wood with a roller capable of continuously applying pressure ,
In the squeezing step,
An upper roller that compresses the wood from above, a front roller that compresses the wood from below before the upper roller, and a rear roller that compresses the wood from below after the upper roller are used,
The wood is fed in a rod-like state along the longitudinal direction, which is the direction of the conduit, and the wood is compressed while being folded by the upper roller between the front roller and the rear roller.
Wood fuel production methods.

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