JP4338747B2 - Production method and production system of wood pellet fuel - Google Patents

Description

  The present invention relates to a wood pellet fuel using wood as a raw material, a method and a production system for wood pellet fuel.

In recent years, fuels using biomass resources have been researched and developed in order to reduce carbon dioxide. Among the biomass fuels, wood pellet fuel made from large sawdust, thinned wood, and driftwood, which are industrial wastes conventionally incinerated, is attracting attention as an alternative to petroleum.
Wood pellet fuel is a wood-based solid fuel, is easier to handle than other biomass fuels, and is suitable for long-distance transportation. Moreover, since it is heat-treated, it can be stored for a long time.

Conventional wood pellets are provided with so-called white pellets made only of wood excluding the bark (herein simply referred to as “wood”) and pellets made of only the bark (commonly called bark pellets). (For example, Patent Document 1).
The wood pellets are formed by compressing large sawdust, thinned wood, and pulverized driftwood (oga powder) into granules. It is formed into a pellet by melting and fixing lignin, which is a component of wood, with heat (for example, Patent Document 2).
JP 2006-266546 A JP 2007-40542

  However, conventional wood pellets have a drawback in that they generate less heat than petroleum and require a larger storage volume than petroleum.

  In order to solve the above-mentioned drawbacks, an object of the present invention is to provide a wood pellet fuel having a higher calorific value than a conventional wood pellet fuel.

Method for producing a wood pellet fuel of the present invention, sieving sawdust obtained by crushing the raw material wood pellets large sawdust small sawdust and particle size granularity, drying the particle size small sawdust, the Carbonize large- sized oga powder, mix a predetermined amount of the carbonized oga powder into the dried oga powder, and pelletize the mixture by extrusion using a pellet forming machine for white pellets. it is obtained by the so that to produce wood pellets with reduced moisture.

Manufacturing system wood pellet fuel of the present invention includes: a crusher for crushing the raw material wood pellets, a sieve machine for sieving sawdust produced by the grinder large sawdust small sawdust and particle size particle size, A mixer that mixes the large- sized sawdust and water, a carbonization furnace that heats and carbonizes the sawdust produced by the mixer, and a dryer that dries the small- sized sawdust. A waste heat fan for sending waste heat from the carbonization furnace to the dryer, and white pellets that are made by mixing the oga powder carbonized in the carbonization furnace and the oga powder dried in the dryer and pelletized by extrusion. a pelleting machine, is obtained by the so that to produce wood pellets with a reduced water content of the white pellet.

Since the wood pellet fuel of the present invention is a fuel using biomass resources (wood), it can reduce carbon dioxide and is an excellent fuel from the viewpoint of environmental protection. Moreover, the pellet fuel of the calorific value higher than the conventional wood pellet fuel can be obtained by making charcoal contain in a wood pellet. Thereby, the storage volume of the wood pellet fuel can be saved. Moreover, a fuel with strong thermal power can be provided to pellet stoves, boilers and the like. Furthermore, by containing charcoal in a conventional wood pellet made of only wood, a wood pellet with less moisture than the conventional wood pellet can be obtained. As a result, it is possible to store for a longer period than conventional wood pellet fuel, and it is suitable for large-scale storage, so that a stable supply of fuel is also possible.
As described above, according to the present invention, carbon dioxide can be reduced and a fuel that can be used as an alternative fuel for petroleum can be provided.

The production method and production system for wood pellet fuel of the present invention carbonizes a part of sawdust obtained by pulverizing wood as a raw material to produce charcoal (pulverized coal). According to the present invention, wood pellet fuel, which is a material for wood pellet fuel, can be produced simultaneously with charcoal, so mass production of wood pellets is possible, and there is no need for capital investment to separately manufacture and pulverize charcoal. Can reduce the installation burden.
Moreover, the wood pellet fuel of this invention dries the sawdust for pellets with the waste heat which arises in the case of the said carbonization. By the above drying, it becomes possible to produce a wood pellet fuel at a low cost.

  The present invention improves the calorific value of conventional wood pellet fuel and provides a wood pellet fuel that can be used as an alternative fuel for petroleum.

White pellets made of wood have features such as a higher calorific value than bark pellets, a small amount of ash after combustion, and no occurrence of crunkers that solidify ash. Among them, it has been the most used fuel.
Therefore, the inventor of the present patent application considered that a new wood pellet fuel having a higher calorific value than that of the conventional white pellets was produced by adding charcoal having a high calorific value to the white pellets.
In addition, a wood pellet fuel manufacturing method and system capable of mass-producing wood pellet fuel containing charcoal in white pellets and capable of producing at low cost were considered.

Here, the manufacturing process of the conventional wood pellet is demonstrated based on FIG. FIG. 1 is a diagram illustrating a process in which wood pellets are molded in a pellet molding machine.
The wood pellet 10 is produced as a product through production processes such as crushing, drying, and pelletizing the raw material 14.
In the crushing process of the raw material 14, the raw material 14 is crushed into small pieces of uniform sawdust using a conventionally known crusher (not shown). Next, the crushed raw material 14 is dried to a predetermined moisture by a conventionally known rotor drum dryer (not shown). The dried raw material 14 is pelletized with a pellet molding machine 12 (FIG. 1).
In the pellet molding machine 12, when the dried raw material 14 is charged into the material charging port 15, the charged raw material 14 is provided innumerably on a forming die (ring die) 18 with a pressure roller (press roll) 16. Forcibly pushed into the die hole 20.
The raw material 14 pushed into the die hole 20 is pushed out of the die hole 20 and pelletized. In the pelletizing process, the lignin of the raw material 14 is melted by frictional heat and serves as an adhesive, and the raw material 14 is solidified. The raw material 14 extruded from the die hole 20 and pelletized is cut into a predetermined size (length) by a cutter 22 provided below the forming die 18 to become a wood pellet 10. In addition, the wood pellet 10 cut | disconnected with the cutter 22 is cooled in order to harden lignin.

In this embodiment, as raw material 14, sawdust (wood) 14a and pulverized coal (charcoal) 14b for wood pellets are charged into a pellet molding machine 12 at a predetermined ratio to generate wood pellets containing charcoal. . Then, the weight ratio (mixing ratio) of the wood 14a and the charcoal 14b was changed, and it was experimented whether the pelletization by the raw material 14 was possible. Table 1 shows whether or not pelletization is possible with respect to the content (weight%) of 14a of charcoal and suitability of the hardness of the wood pellets.
In the above experiment, a pellet molding machine (pellet mill) 12 manufactured by Miike Steel Corporation with a die hole diameter of 6 mm and a die thickness of 60 mm was used. The rotation speed of the pressure roller 16 of the pellet molding machine 12 was set to 200 rotations per minute.
The raw material 14 to be fed into the pellet molding machine 12 is crushed cedar wood into 3 mm, crushed wood pellet 14a with moisture adjusted to 9% to 12%, and cedar wood into 5 mm, It is charcoal (pulverized coal) 14b having a water content of 10% produced by carbonizing the sawdust.

  In this experiment, the case where only the charcoal 14b was used as the material without the wood 14a was not performed. The wood pellet fuel of the present invention is intended to be pelletized using lignin, which is a component of wood, as an adhesive, and excludes wood pellet fuel that is pelletized using various adhesives.

First, the mixing amount of the charcoal 14b was set to 90% by weight of the entire material 14, and thereafter the pelletization with the material 14 containing the charcoal 14b was confirmed while gradually decreasing the mixing amount of the charcoal 14b. However, in Experimental Examples 1 to 6 in Table 1 in which the mixing amount of the charcoal 14b is 90 wt% to 40 wt%, the rotation of the pressure roller 16 of the pellet molding machine 12 is remarkably reduced, and the raw material 14 is diced. Even if the raw material 14 was pushed into the die hole 20 without being pushed into the hole 20, it was not pelletized.
The inventors of the present application determined from Experimental Examples 1 to 6 that the reason why pelletization cannot be performed is that the lignin of the wood 14a does not play the role of an adhesive in the pelletizing process and the amount of the wood 14a is small. did.

  Therefore, pelletization was attempted by further reducing the amount of charcoal 14b. In Experimental Example 7 and Experimental Example 8 in Table 1 in which the mixing amount of the charcoal 14b is 30 wt% to 20 wt%, pelletization is possible, and the pressure roller 16 of the pellet forming machine 12 also rotates at the set rotation speed. It was way. However, the pelletized wood pellets are insufficient in hardness and are unsuitable as fuel (product).

  In the experiment example 9 in Table 1 in which the experiment was further continued and the amount of the charcoal 14b was reduced to 10% by weight, the wood pellets 10 having sufficient hardness as fuel could be obtained for the first time.

Next, wood pellets 10 (Experimental Example 9 in Table 1) made of 10% by weight of charcoal and 90% by weight of wood and conventional white pellets made of 100% of wood (Comparative Example in Table 1) were used as samples. Then, measurement tests such as calorific value were conducted. Table 2 shows the measurement results of the two samples.
In Table 2, the amounts of carbon C, hydrogen H, and nitrogen N for the two samples were measured using a CHN element analyzer. The amount of oxygen O is a calculated value obtained by subtracting the amount of carbon C, hydrogen H, nitrogen N (wt%) and ash (wt%) from the total amount of the sample (100 wt%). The ash content is the residue when the sample is burned at 600 ° C. The total calorific value (J / g or cal / g) was measured by a JIS M8814 MOKEN automatic cylinder calorimeter method.

According to the above measurement, the total calorific value of the white pellets was 18,790 J / g (4,490 cal / g). In contrast, the total calorific value of the wood pellets of the present invention is 19,160 J / g (4,580 cal / g), and has a calorific value that is 2% higher than the total calorific value of the white pellets. I understood.
In addition, the above two samples were burned with a pellet stove, and a thermal sensation test was performed with a monitor. All the participating monitors felt that the pellet stove using the wood pellets of the present invention as fuel was much warmer than the pellet stove using the white pellets as fuel. It was also confirmed that the thermal power of the wood pellets of the present invention was clearly stronger than that of the white pellets.

  As described above, the wood pellet of the present invention can obtain a higher calorific value than the conventional white pellet. Therefore, space saving of the storage volume of pellet fuel becomes possible. Moreover, since the thermal power is stronger than conventional white pellets, it can be used not only for small-scale energy systems such as pellet stoves but also for large-scale energy systems such as boilers.

Moreover, the water | moisture-content test of the said pellet was done about the wood pellet of this invention and the conventional white pellet (Table 3). In the measurement test, moisture measurement was performed on five samples of the two pellet samples, and an average value of moisture of each sample was obtained.
The method for measuring the moisture content of the pellets is based on the standards of the Japan Fuel Equipment Inspection Association (standards for woody biomass pellets), and the measurement is based on JIS Z7302-3 (“Waste Solidified Fuel Part 3: Moisture Content”). Measurement test method ").

According to the above measurement, the moisture content of the white pellets was 9.49% (average value) of the total amount of the sample. In contrast, the water content of the wood pellets of the present invention was 6.8% (average value) of the total amount of the sample, and was found to be significantly less than the water content of the white pellets.
As described above, the wood pellets of the present invention have a lower moisture content than conventional white pellets. Therefore, the wood pellets of the present invention can be stored for a longer period of time than conventional white pellets and become a product suitable for mass storage. A stable supply of fuel is also possible, and it can be used as an alternative fuel for oil.

  In the above embodiment, cedar is used as a raw material for the wood pellets, but other conifers or hardwoods may be used.

Next, the manufacturing method of the wood pellet fuel of this invention is demonstrated.
The manufacturing method of the wood pellet fuel of this invention produces | generates the wood pellet fuel containing charcoal by mixing pulverized coal with the sawdust for wood pellets, etc.
The pulverized coal may be obtained by pulverizing charcoal or carbonized sawdust for pulverized coal described later.

In addition, sawdust obtained by pulverizing the raw material (wood) is divided into a predetermined ratio of sawdust for wood pellets and sawdust for pulverized coal, and the sawdust for pulverized coal is carbonized and produced by the carbonization. By mixing pulverized coal with sawdust for wood pellets, wood pellet fuel can be produced at low cost and at a low cost.
If charcoal is manufactured separately and the pulverized powder of charcoal is mixed with pelleted sawdust, not only will it take time to produce charcoal, but it will also take time to crush and transport the charcoal. Is difficult and bears an economic burden. By dividing the sawdust obtained by pulverizing the raw material (wood) into sawdust for pulverized coal and sawdust for pellets, and carbonizing the sawdust for pulverized coal, it is used as a material for wood pellet fuel. Necessary wood pellets and pulverized coal can be prepared at the same time. Thereby, mass production becomes possible.

Next, an example of a wood pellet fuel production system for implementing the wood pellet fuel production method of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram of the production system of the wood pellet fuel 10 of the present invention. FIG. 3 is a schematic view of a main part X of the manufacturing system of FIG.
The wood pellet fuel production system 24 includes a crusher 28 that crushes the raw material 26 of the wood pellet 10, and the sawdust 30 produced by the crusher 28, the sawdust 30 a for wood pellets, and the sawdust 30 b for pulverized coal. A sieving machine 32, a mixer (hopper mixer) 36 for mixing the powdered sawdust 30 b and water 34, and a carbonization furnace 38 for carbonizing the powdered sawdust 30 b generated by the mixer 36. And a dryer 42 for drying the wood pellet sawdust 30a with the waste heat 40 of the carbonization furnace 38, a pulverized coal 14b generated in the carbonization furnace 38, and a wood pellet pellets generated in the dryer 42. A pellet molding machine 12 for molding the wood pellet 10 made of the powder 14a is provided.
In FIG. 2, the raw material 26, sawdust 30, 30 a, 30 b, 14 a and pulverized coal 14 b are conveyed to each of the above components by the belt conveyor 44 and the chain conveyor 45 that are conveying means. In addition to the transport means, a transport means (or transport means) such as a forklift, an air feed fan, and an elevator may be used.

  The pulverizer 28 is a known pulverizer used in the production of conventional white pellets, and pulverizes the raw material 26 (coniferous or hardwood wood) into a predetermined particle size.

  The sieving machine 32 has a classification function, and divides the sawdust 30 produced by the grinder 28 into sawdust 30a for wood pellets and sawdust 30b for pulverized coal. For example, when producing the sawdust 14a for wood pellets having a particle size of 3 mm and the sawdust 14b for coal powder having a particle size of 5 mm used in the above-described example, the raw material 30 is used for 3 mm wood pellets using a 6 mm sieve. It is classified into sawdust 30a and sawdust 30b for 5mm pulverized coal. The sieve machine 32 is a known one.

  The mixer (hopper mixer) 36 has a material charging port for sawdust 30b for pulverized coal and a water injection pipe 48 for pouring water into the tank 36a of the mixer 36, and the sawdust 30b and water 34 for pulverized coal Are mixed in the tank 36a. Thereby, the water 34 penetrates into the sawdust 30b for pulverized coal put into the tank 36a, and the sawdust 30b can be effectively carbonized in the carbonizing furnace 38 described later. That is, sawdust 30b can be made into charcoal. In addition, when the sawdust 30b is put into the carbonization furnace 38 without allowing the water 34 to penetrate into the sawdust 30b for dust coal, the sawdust 30b is not carbonized (that is, does not become charcoal) and burns out and becomes ash (yes) End up. Injecting water into the tank 36a of the mixer 36 prevents the sawdust 30b from becoming ash.

  The carbonization furnace 38 carbonizes the sawdust 30b for pulverized coal in a short time and can adjust the humidity in the furnace. By adjusting the humidity of the carbonization furnace 38, pulverized coal 14b having a predetermined moisture can be generated.

  The dryer 42 dries the pelleted sawdust 30a put into the tank with hot air. Moreover, the waste heat of the carbonization furnace 38 is used for the hot air.

Subsequently, the main part X of the wood pellet fuel production system of the present invention shown in FIG. 2 will be described with reference to FIG.
The wood pellet oga powder 30a and the pulverized coal saw powder 30b classified by the sieving machine 32 of FIG. 2 are put into a supply hopper 46 and a mixer (hopper mixer) 36, respectively. The wood pellet sawdust 30a charged into the supply hopper 46 is conveyed to the dryer 42 by the belt conveyor 44 and is charged into the charging port 42a.

Water 34 is supplied from a water injection pipe 48 to the tank portion 36 a of the mixer 36. The sawdust 30b for pulverized coal charged in the mixer 36 is mixed with water 34. The sawdust 30b containing the water 34 is conveyed to the carbonization furnace 38 by the belt conveyor 44, and is charged into the charging port 38a. The carbonization furnace 38 has a built-in heater (for example, a burner) (not shown), and the inside 38b of the furnace is heated to a predetermined temperature. In addition, the furnace 38b has an airflow generation mechanism that generates a spiral airflow 50 (a vigorous airflow around a spiral). The sawdust 30b charged into the carbonization furnace 38 rides on the hot air flow 50 generated in the furnace 38b, is carbonized up to the discharge port 38c, is discharged from the discharge port 38c onto the chain conveyor 45, and is made of wood pellet fuel. Ten materials, pulverized coal 14b, are conveyed to the pellet molding machine 12 (FIG. 1).

  On the other hand, the waste heat 40 in the furnace of the carbonization furnace 38 is sent into the tank 40b of the dryer 42 through the waste heat discharge pipe 50 and the waste heat fan 52 (blower). The wood pellet sawdust 30a charged in the tank 42b of the dryer 42 is dried by the airflow of the waste heat 40 flowing in a vortex in the tank 42b, discharged to the chain conveyor 45 from the discharge port 42c, and the wood pellet fuel. 10 materials, wood pellet pellets 14a are conveyed to the pellet molding machine 12 (FIG. 1).

Since the dryer 42 and the carbonization furnace 38 produce the materials 14a and 14b of the wood pellet fuel 10 in a short time, the main part X of the wood pellet fuel production system of the present invention enables mass production of the wood pellet fuel 10. Become.
Further, by sending out the waste heat 40 of the carbonization furnace 38 to the dryer 42 via the waste heat fan 52 (blower), the utility cost for drying the wood pellets 30a can be reduced or reduced. it can. Furthermore, the conventional dryer for white pellets is provided with a fuel combustion device for supplying hot air into the tank, but by drying with the waste heat 40, the fuel combustion device becomes unnecessary. . Thus, by utilizing the waste heat 40 of the carbonization furnace 38, the equipment burden of the wood pellet fuel production system of the present invention can be reduced, and the wood pellet fuel 10 can be produced at low cost.

It is a figure showing the process in which a pellet is shape | molded in a pellet molding machine. It is a block diagram of the manufacturing system of the wood pellet fuel of this invention. It is the schematic of X of the manufacturing system of the wood pellet fuel of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wood pellet 14 Raw material 14a Wood 14b Charcoal 24 Wood pellet fuel production system 26 Raw material 28 Pulverizer 30 Oga powder 32 Sieve machine 36 Mixer 38 Carbonization furnace 40 Waste heat 42 Dryer 54 Waste heat fan

Claims (2)

Oga powder obtained by pulverizing the raw material of the wood pellets is screened into small-sized oga powder and large-sized oga powder, dried the small-sized particle, and carbonized the large-sized particle. A predetermined amount of dried sawdust is mixed with the dried sawdust, and the mixture is pelletized by extrusion using a pellet forming machine for white pellets to produce wood pellets with reduced water content of the white pellets. A method for producing a wood pellet fuel, which is characterized. A pulverizer that pulverizes the raw material of wood pellets, a sieve that screens the oga powder produced by the pulverizer into small sized oga powder and large sized oga powder, and the large sized oga powder mixed with water A mixer that heats the sawdust produced in the mixer with a built-in heater and carbonizes it, a dryer that dries the small-sized sawdust, and the waste heat of the carbonization furnace to the dryer. A waste heat fan to be fed, and a pellet forming machine for white pellets that mixes the sawdust carbonized in the carbonization furnace and the sawdust dried in the dryer and pelletizes by extrusion molding, A wood pellet fuel production system for producing wood pellets with reduced water content.