JP2003268394A - Wooden fuel and its production process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wooden fuel which can realize the effective utilization of coconut husks and waste wooden materials hitherto discarded as scraps and which can be used as a coal substitute fuel, to provide its production process and its utilization method. <P>SOLUTION: A raw material wood preliminarily crushed to a prescribed size is fed through a supply tube toward the center of a grinding table of a vertical grinder equipped with a two-stage classifying rotary separator and is ground with multiple rollers driven with the rotation of the grinding table. The ground material is discharged from the periphery of the grinding table, dried and conveyed by a gas blown out from the lower side of the periphery of the grinding table, and introduced into the two-stage classifying rotary separator installed on the upper side of the grinding table, where it is classified into a fine powder component and a coarse powder component. The fine powder component is discharged out of the grinder, giving an objective product. The coarse powder component is returned to the center of the grinding table through the supply tube present close to the grinding table. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood fuel, a method for producing the wood fuel, and a method for using the wood fuel, and more particularly to a technology for effectively using palm shells and wood waste materials / chips as a coal alternative fuel.

[0002]

2. Description of the Related Art As a method for finely crushing palm shells and wood waste materials / chips, a system in which a drying device, a crushing device (hammer mill) and a vibrating screen are combined is considered. However, in this case, the equipment becomes large in size, and the vibrating screen also becomes clogged in a very short time, making stable continuous operation difficult, and there is a problem in practical use. In addition, as a method other than this, a method of dry crushing using a conventional rigid mill can be considered, but in this case most of the pre-crushed products of palm shell and wood waste material with low density and wood chips are crushed into rollers. Expected to float inside the mill without being bitten and settle without being crushed.Because pre-crushed coconut shells and wood waste and wood chips are elastic, mutual destruction of raw materials due to pressure is expected. For the reason that it cannot be done, efficient crushing was not possible. Also, in the case of the conventional two-stage classification separator (plate type with one fixed vane on the outer periphery), the lightweight wood-based pulverized product has a small inertial force, so most of the product pulverized product is Pushed back by centrifugal force,
If it floats in the mill and exceeds the limit amount, it causes an increase in the resistance of the gas flow ejected from below the outer periphery of the table (mill differential pressure), making it difficult to operate the mill.

On the other hand, the following three cases are envisioned as the usage of the finely pulverized wood fuel. That is, (1) In the coal-fired thermal power generation currently performed, coal is crushed by a hard crusher, fine powder and coarse powder are classified by a rotary separator, and only fine powder is dried by hot air gas. , Transported to a boiler and burned. In this method, wood fuel is not used, and only coal is used as fuel. The present invention enables the use of wood fuel as an alternative fuel to coal in this method. (2) Coal is mainly used as the fuel for the calcining furnace for the raw material of the kiln for burning cement. In the case of this calcination furnace fuel, the pulverized coal and the appropriately pulverized wood fuel are once stored in the tank, so the crusher and burner are not directly connected. In addition, the above-mentioned conventional pulverization method for wood fuel has a size of about 50% remaining on a 5 mm sieve, and this size is the limit for industrial pulverization. When the wood fuel is used as the fuel for the calcining furnace in such a pulverized state, the residence time in the combustion space becomes a problem, and it is not at a satisfactory level from the viewpoint of the amount of the wood fuel used. That is,
The wood fuel was incompletely burned and could not be used as fuel for the calciner. On the other hand, as fuel for kiln,
Since the conventional crushing technology was not able to satisfy the purpose (making a flame and making a high temperature combustion state) as a kiln fuel, it was not used at all. (3) It is possible to use only wood fuel for a general combustion furnace, but in the conventional crushing method, it is in a crushed state where about 50% remains with a 5 mm sieve, and it burns in a stoker furnace for a relatively long time. Except for possible combustion furnaces, complete combustion of woody fuel cannot be expected, so it has hardly been put to practical use.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and effectively uses palm shells and wood waste materials that have been treated as scrap until now as thermal energy, and as an alternative fuel for coal. The object is to provide a wood fuel that can be used, a method for producing the same, and a method for using the same.

[0005]

In order to solve the above-mentioned problems, in the first invention, the wood raw material is crushed by a hard crusher and the residue rate becomes 10% or less with a 2.83 mm sieve. I did it. In the second invention, the woody raw material in the first invention is coconut shell. Further, in the third invention, a wood raw material preliminarily crushed to a predetermined size is supplied through a supply pipe to the center of the crushing table of a rigid crusher having a two-stage classification rotary separator, and the wood raw material is supplied to the crushing table. Is crushed by a plurality of rollers driven by the rotation of the crushing table and discharged from the outer circumference of the crushing table, the crushed material is dried and conveyed by the gas ejected from below the outer circumference of the crushing table, and the two-stage classification is arranged above the crushing table. Introduced into the rotary rotary separator to classify into fine powder component and coarse powder component, the fine powder component is discharged to the outside of the crusher to be a product, and the coarse powder component is passed through the supply pipe adjacent to the crushing table to the crushing table. I decided to return it to the center.

Further, in the fourth and fifth inventions,
The distance between the tip of the supply pipe in the third invention and the crushing table is 0.2 to 0.8 times the diameter of the crushing table, and the rotation speed of the crushing table in the third invention is the outer diameter of the crushing table. The centrifugal force was constant. Further, in the sixth invention, a wood raw material preliminarily crushed to a predetermined size is supplied through a supply pipe to the center of the crushing table of a rigid crusher with a two-stage classification rotary separator, and the wood raw material is supplied to the crushing table. Is crushed by a plurality of rollers driven by the rotation of the crushing table and discharged from the outer circumference of the crushing table, the crushed material is dried and conveyed by the gas ejected from below the outer circumference of the crushing table, and the two-stage classification is arranged above the crushing table. Introduced into the rotary separator to classify into fine powder component and coarse powder component, return the coarse powder component to the center of the pulverizing table through the supply pipe close to the table, and supply the gas containing the fine powder component to the boiler combustion device. It was decided to.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The following items are conditions for efficiently crushing a preliminary crushed wood waste material having a small density, wood chips, palm shells, etc. with a rigid crusher (roller mill). The present invention has been made by discovering that is important. This item will be described below. (1) A structure capable of reliably returning the coarse powder component scraped off by the rotary separator to the center of the crushing table and preventing it from floating in the mill. For this purpose, the distance (distance) between the supply pipe and the grinding table is important. (2) The rotation speed of the crushing table is increased as compared with the case of general crushed material such as coal, and the amount of the crushed object that is caught in the crushing roller within a certain time is increased to increase the table layer thickness (crushed material). Layer thickness). As a result, the crushing pressure is effectively applied to the object to be crushed, which is an elastic body, so that the crushing efficiency is improved. (3) By making the crushing pressure of the crushing roller higher than that of a general crushed product such as coal, it is possible to promote mutual destruction of the pre-crushed product of the elastic material such as the palm shell and the wood waste material. (4) The cross-sectional area of the space (gap) between the inner peripheral portion of the crusher casing (outer cylinder) and the outer peripheral portion of the cone (inverted truncated cone) arranged below the rotary separator is directed upward. By smoothly changing the speed of the ascending airflow inside the mill, it should be a structure that smoothes the airflow and eliminates stagnation. (5) As a separator, a two-stage classification type rotary separator with a coarse particle capturing pocket (this is referred to as a capturing pocket) that can efficiently separate a coarse powder component and a fine powder component is adopted, and a pulverized fine powder component (product) is used. To be quickly discharged from the inside of the crusher. This capture pocket is more effective when the density of the ground material is low.

Next, the structure of a rigid crusher with a two-stage classification type rotary separator used in the present invention is shown in FIGS. 1 and 11.
Will be described. 1 is a crusher casing (outer cylinder), 2
Is a crushing table (rotary table), 3 is a crushing roller, 4
Is a two-stage classification type rotary separator, 5 is a supply pipe (center chute), 6 is a guide vane, 7 is a cone having an inverted truncated cone shape, and the supply pipe 5 is provided at the lower tip of the cone 7 and the crushing table 2 is provided. Is arranged in close proximity to. A crushing table 2 is supported on a pedestal (not shown) so as to be rotatable about a vertical axis, and the crushing table 2 is arranged in a lower portion of a casing (outer cylinder) 1. Then, the crushing table 2 is rotationally driven by an electric motor. The space surrounded by the inner surface of the casing 1 and the upper surface of the grinding table 2 is a grinding chamber 1
1 to 2, and 2 to 4 crushing rollers 3 for pressing and crushing the object to be crushed on the crushing table 2 are arranged on the crushing table 2. These crushing rollers 3 are supported on the gantry side via a link mechanism (arm), and the pressing pressure can be adjusted by a hydraulic cylinder or a spring via the link mechanism. Further, a nozzle (not shown) is formed between the outer peripheral surface of the crushing table 2 and the lower inner peripheral surface of the casing 1,
The nozzle is formed so that gas (often hot air) is jetted upward from the nozzle in the casing 1 to form a swirling flow.

On the other hand, an outlet 13 for the gas flow to the outside of the mill is formed in the upper part of the casing (outer cylinder) 1 of the crusher.
A two-stage classification type rotary separator 4 is arranged in the casing 1 corresponding to the discharge port 13.
Rotates coaxially with the grinding table 2 about its axis.
The lower part of the separator 4 is covered with an inverted (inverted) truncated cone 7. This cone (inverted truncated cone)
A plurality of guide vanes 6 are provided at equal intervals in the circumferential direction between the upper edge of the casing 7 and the ceiling surface of the casing 1. The guide vanes 6 are obliquely attached so as to create a swirling flow toward the center of the mill. Further, in the guide vanes 6, coarse particles classified along the vertical direction are dropped along the vertical wall to the lower truncated cone-shaped cone (trapped pocket) 10 for dropping the coarse particles. Is provided.

Next, the material to be crushed is supplied from the supply chute (center chute or side chute) 9 through the supply pipe 5 to almost the center of the crushing table 2. And
When the crushing table 2 is rotated, the object to be crushed is crushed by being pressed between the upper surface of the crushing table 2 and the crushing roller 3. The powder pulverized in this way is blown up while swirling upward with the gas flow (often hot air) ejected from below the outer periphery of the pulverizing table 2. The spatial cross-sectional shape formed by the inner surface of the casing 1 and the outer periphery of the cone 7 is determined so that the rising gas flow speed is gradually increased and stagnation does not occur. The mixed flow of the gas flow and the pulverized powder becomes a uniform flow and is guided to the guide vanes 6 arranged above the inside of the casing 1.

The mixed flow containing the powder thus pulverized becomes a uniform flow, and passes through the guide vanes 6 while swirling around the cone 7. At this time, the relatively heavy coarse powder component collides with the guide vanes 6 and most of them fall downward along the coarse-grain capturing pocket 10 to slide down the inner surface of the cone 7 and pass through the supply pipe. It is returned to the crushing table 2. This is the primary classification by the guide vane 6. Next, the mixed flow passing through the guide vanes 6 is sent to the rotary separator 4. Since this mixed flow (powder) still contains a coarse particle component, the rotary separator 4 secondarily classifies this powder into a coarse powder component and a fine powder component. Then, the coarse powder component is repelled by the rotary vane (rotary blade) 8 of the separator 4, passes through the inside of the cone 7 and drops on the crushing table 2 again to be pulverized, and the fine powder component passes through the discharge port 13. The product is discharged from the crushing chamber 11 to the outside and becomes a product.

Here, the crushing method of the present invention will be described. First, the distance between the tip of the supply pipe and the crushing table will be described. The crushed wood material is swirling in the crushing chamber by the gas ejected from below the outer circumference of the crushing table.
The mixed flow of the pulverized powder and the gas is guided by the guide vanes 6 and the rotary vanes 8, and the relatively heavy coarse powder component is dropped downward and returned to the pulverization table through the supply pipe. here,
If the distance (distance) between the supply pipe and the crushing table is large, the swirling flow in the crushing chamber causes the particles to float on the table without falling. In order to prevent this, it is necessary to keep the distance between the tip of the supply pipe and the crushing table as short as possible. If the length is made too short, the supply pipe will be clogged and will come into contact with the crushing table. Therefore, a distance with a proper distance from the layer thickness of the crushed material before crushing is appropriate. Specifically, as shown in FIG. 6, when the distance is larger than 0.8 times the diameter of the table, the processing capacity is remarkably reduced. Therefore, this interval is preferably 0.2 to 0.8 times the diameter of the grinding table. Next, the rotation speed of the crushing table will be described. The rotation speed of the coal crushing mill is 0.6-
A range of 1.5 g (depending on the plant) is a general value. In the case of the wood raw material crushing mill of the present invention, it is difficult to define the mass of the raw material, and therefore the above definition cannot be made. Therefore, the rotation speed is set as follows. That is, the behavior of the raw material (the locus drawn by the raw material) on the crushing table is set to be the same for each mill size. Therefore, the following formula 1 is used for calculation so that the centrifugal force on the outer circumference of the crushing table is constant.

[Equation 1] Here, N is the rotation speed of the crushing table, a is a constant,
In the case of a wood raw material, the value is (80 to 100), and D is the diameter of the crushing table (rotary table). FIG. 7 showing the results of a crushing test with a wood raw material (survey of the influence of the table rotation speed).
As is clearer, the crushing processing capacity increases as the table rotation speed increases up to about 1.4 times the standard rotation speed, and at a rotation speed higher than this, the processing capacity has a substantially constant value. Therefore, in the pulverization of the wood raw material, the value is set to be a constant value within the table rotation speed range of 1.0 to 1.4 times the standard rotation speed for coal mills and the like.

Finally, the relationship between the 6-degree surface pressure and the roller pressing pressure will be described with reference to FIG. The roller surface pressure includes an average surface pressure and an effective surface pressure. The roller average surface pressure is the pressing force of the roller on the crushing table divided by the projected area of the roller on the crushing table. If the crusher (mill) to be used is determined, the roller average surface pressure is the pressing force of the roller. It is the same (pressing force is obtained by multiplying the roller average surface pressure by the projected area), and since the average surface pressure does not show the actual crushing condition of the crushed object, it is not generally used. Therefore,
In the present invention, the effective surface pressure is used to represent the actual crushed state. This effective surface pressure is substantially the pressing force (F) of the roller when the layer thickness of the material to be crushed on the table (biting angle into the roller / α in FIG. 3) is formed during steady operation. It is determined by the relationship with the range (area A) acting on the object to be ground. When this relationship is expressed by a mathematical expression, the following mathematical expression 2 is obtained.

[Equation 2] Here, A is the area where the pressing force actually acts on the crushed object, F is the pressing force of the roller, and α is the biting angle into the roller. In the embodiment of the present invention, the biting angle into the roller (α in FIG. 3) is set to 6 degrees, and the pressing pressure (6 degree surface pressure) of the crushing roller based on this is 200 to
It was set to 300 kg / cm ² . If it exceeds 300 kg / cm ² , the strength member of the mill body becomes large, which is not economical. On the other hand, if it is less than 200 kg / cm ² , the pulverization efficiency will deteriorate. FIG. 8 shows the crushing test results (relationship between the roller surface pressure and the processing capacity) on the wood raw material. From FIG. 8, it can be seen that the treatment capacity is remarkably improved when the 6-degree surface pressure is in the range of 200 to 300 kg / cm ² .
Further, the tire mounted on the outer periphery of the roller has a linear protrusion formed in parallel with the width direction of the tire (roller axial direction) as shown in FIG. It is more effective if it is shaped like.

For reference, one embodiment of the flow of the entire system of the present invention is shown in FIG. The system shown in FIG. 2 is intended to produce a wood-based fuel for a cement kiln calciner burner fuel. Ground object storage 101
The object to be crushed received in the above is provided under the storage and is supplied to the vertical crusher 103 by the raw material feeder 102 in a fixed amount, and is crushed by being caught between the roller and the table on the table. At the same time as the pulverization, the gas is introduced from the blade ring on the outer circumference of the table to be dried in the pulverizer. The crushed wood fuel is a bag filter fan (exhaust fan) 1
After being guided to the classifier on the upper side of the crusher by the air flow that 08 sucks, it is classified into coarse powder and fine powder by the rotating separator,
The coarse powder descends along the inner wall of the classifier, falls on the table of the crusher, and is crushed again. Here, the object to be crushed having a size that cannot be lifted by the gas flowing from the blade ring is returned to the object to be crushed storage again by the external circulation facility (bucket elevator) 100. On the other hand, the fine powder is guided to the bag filter 106 along with the exhaust air of the crusher, is collected, and is stored in the crushed material storage by the discharger. The stored fine powder is weighed by a metering device and blower (fine powder delivery blower) 1
It is supplied to the calcination furnace burner 111 by the air flow from 09.

[0015]

[Examples] Next, a pre-ground product of palm shells and wood waste, a wood chip crushing test, and a combustion state confirmation test were performed using the above-described solid crusher. The test results will be described. . Confirmation test 1 The coconut shell was crushed with a solid crusher, and the openings were 2.
The particle size was adjusted with a sieve of 83 mm, 3.35 mm and 4.0 mm so that the residue rate was 10%. FIG. 9 shows the results of measuring the burning rate of these pulverized products which were placed in a combustion furnace. The size of the combustion furnace used at this time was 200,00
It is 0 kcal / m ³ h. The criterion for complete combustion (unburned rate is 0.2% or less) in the combustion furnace used in this experiment is that the residence time on the horizontal axis is within 2 seconds. As is clear from FIG. 9, the crushed product with a residue rate of 10% on the 2.83 mm sieve is within the range of complete combustion, and the crushed product with a residue rate of 10% on the 3.35 mm and 4.0 mm sieves is It was not a complete burn. The data of pulverized coal is also shown for reference, and 2.
The pulverized product with a residue rate of 10% through a 83 mm sieve was in a state of combustion similar to that of pulverized coal.

Confirmation Test 2 Next, the wood was crushed by a hard crusher so that the residue rate was 10% with sieves having openings of 2.83 mm, 3.35 mm and 4.0 mm, respectively. FIG. 10 shows the results of an experiment similar to the case of using coconut shells for these crushed products.
As is clear from FIG. 10, the crushed product with a residue rate of 10% was in the range of complete combustion with a 2.83 mm sieve, and 3.3.
The pulverized product having a residue rate of 10% with 5 mm and 4.0 mm sieves was not completely burned.

Confirmation Test 3 The coconut shell was crushed with a rigid crusher and adjusted to a particle size such that the residue rate was 10% with a 2.83 mm sieve. A temporary burner was attached near the cement kiln burner, and a combustion test was conducted in which the crushed coconut shell was continuously blown from this burner. As a result, the palm shell with the above-mentioned particle size is about 5 m from the burner nozzle.
It was confirmed that the flame was formed and stable combustion was possible.

Finally, the particle size distribution of the crushed particle size and the residual ratio of the sieve size will be described with reference to FIG. When the residue ratio of the same pulverized product was measured with different sieve sizes, the results shown in FIG. 4 are obtained. That is, point P (sieve size is 2.83 mm) and the residue rate is 10% and point Q (sieve size is 0.8 mm)
In the case of a residue rate of 50%, the degree of crushing is the same. Therefore, the content described in claim 1 follows the particle size distribution of the crushed particle size in FIG. The size of the calcining furnace (combustion furnace) in the present invention is 100,000 to 300,000.
A range of 0 kcal / m ³ h is assumed.

[0019]

According to the method of the present invention, the density is low and the particles are easily floated, and the palm shell and the pre-ground product of wood waste, which are elastic bodies, and wood chips are continuously burned to a level at which they can be completely burned. It became possible to dry and crush efficiently. This makes it possible to substitute coal as fuel for firing in power generation boilers and cement kiln calcination furnaces, and the palm shell and wood waste that are now field burned can be reused as an effective energy source. In addition, since it can be used as an alternative fuel for coal (it is possible to replace fossil fuel with biomass fuel), it has become possible to reduce CO ₂ from coal.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rigid crusher equipped with a two-stage classification type rotary separator according to the present invention.

FIG. 2 is a flow chart of an embodiment of pulverizing a wood raw material.

FIG. 3 is an explanatory diagram of 6-degree surface pressure.

FIG. 4 is an explanatory diagram of a particle size distribution of a pulverized product, showing a relationship between a sieve size and a residue rate.

FIG. 5 is a width direction of a roller tire (roller axis direction).
It is a drawing of the crushing roller which formed the linear protrusion in the.

FIG. 6 is experimental data showing the relationship between the crushing capacity and the “distance between the supply pipe and the table”.

FIG. 7 is experimental data showing the relationship between the pulverization processing capacity and the table rotation speed.

FIG. 8 is a crushing capacity and roller surface pressure (tension hydraulic pressure).
It is the experimental data showing the relationship with.

[Fig. 9] Fig. 9 is data of a combustion experiment for a crushed product obtained by crushing a palm shell and having a residue rate of 10% at each sieve size.

FIG. 10 is data obtained from a combustion experiment for a crushed product obtained by crushing chips and having a residue rate of 10% at each sieve size.

11 is an explanatory view of a pocket for capturing coarse particles in a cross section A in FIG. 1. FIG.

[Explanation of symbols]

1 Crusher casing (outer cylinder) 2 Grinding table (rotary table) 3 rolls (crushing rolls) 4 Two-stage classification rotary separator 5 supply pipes 6 guide vanes 7 cones (reverse truncated cones) 8 rotating vanes (rotating blades) 9 Supply chute (center chute) 10 Coarse grain capture pocket (capture pocket) 11 crushing room 13 outlet 100 bucket elevator 101 wood raw material tank 102 wood raw material feeder 103 Hard crusher (roller mill) 104 hot gas 105 wood raw material 106 bag filter 107 crushed product tank 108 bag filter fan 109 blower 110 burner feeder 111 burner

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsuneo Matsuhashi             1980 U, a mountain off the coast of Ogushi, Ube City, Yamaguchi Prefecture             Department Techno Engineering Co., Ltd. (72) Inventor Hirokazu Fujita             1980 U, a mountain off the coast of Ogushi, Ube City, Yamaguchi Prefecture             Department Techno Engineering Co., Ltd. (72) Inventor Hirofumi Kasai             1980 U, a mountain off the coast of Ogushi, Ube City, Yamaguchi Prefecture             Department Techno Engineering Co., Ltd. F-term (reference) 4D063 EE03 EE12 EE21 GA10 GC12                       GC19 GD24                 4H015 AA13 AB01 BA01 BB10

Claims (6)

[Claims] 1. A wood raw material is crushed by a rigid crusher,
A wood fuel that has a residue rate of 10% or less with a 2.83 mm sieve. 2. The woody fuel according to claim 1, wherein the woody raw material is palm shell. 3. A wood material preliminarily crushed to a predetermined size is supplied through a supply pipe to the center of a crushing table of a rigid crusher with a two-stage classification rotary separator, and the wood material is driven by the rotation of the crushing table. Are crushed by a plurality of rollers and discharged from the outer circumference of the crushing table, and the crushed material is dried and conveyed by the gas ejected from below the outer circumference of the crushing table to a two-stage classification type rotary separator disposed above the crushing table. The fine powder component is introduced and classified into a fine powder component and a coarse powder component, and the fine powder component is discharged to the outside of the pulverizer by gas to form a product, and the coarse powder component is passed through the supply pipe adjacent to the pulverization table to the center of the pulverization table. A method for producing a wood fuel, which comprises returning the wood fuel. 4. The method for producing a wood fuel according to claim 3, wherein the distance between the tip of the supply pipe and the crushing table is 0.2 to 0.8 times the diameter of the crushing table. 5. The method for producing a wood fuel according to claim 3, wherein the rotation speed of the pulverizing table is set so that the centrifugal force at the outer diameter of the pulverizing table is constant. 6. A wood material preliminarily crushed to a predetermined size is supplied through a supply pipe to the center of a crushing table of a rigid crusher with a two-stage classification rotary separator, and the wood material is driven by the rotation of the crushing table. Are crushed by a plurality of rollers and discharged from the outer circumference of the crushing table, and the crushed material is dried and conveyed by the gas ejected from below the outer circumference of the crushing table to a two-stage classification type rotary separator disposed above the crushing table. Characterized by introducing and classifying into a fine powder component and a coarse powder component, returning the coarse powder component to the center of the pulverizing table through the supply pipe adjacent to the table, and supplying a gas containing the fine powder component to the boiler combustion device. How to use wood fuel.