JP5569766B2 - Raw material grinding method - Google Patents

Description

  The present invention mainly relates to a pulverization method and a pulverization system for a raw material used as a fuel for a combustion apparatus by pulverizing combustibles such as coal, petroleum coke, or biomass raw material such as lignite and lignite as raw materials. The present invention relates to a pulverization method and a pulverization system suitable for finely pulverizing a granular raw material which has been artificially manufactured by once molding and granulating the combustible material.

Conventionally, coal such as bituminous coal and sub-bituminous coal is generally pulverized and used as a fuel for a combustion apparatus in power plants, cement plants, and the like.
As a pulverizer for pulverizing minerals such as coal, a pulverizer called a vertical pulverizer (sometimes referred to as a vertical mill) is known, and in particular, coal such as bituminous coal and subbituminous coal. As a pulverizer suitable for finely pulverizing slag, a vertical pulverizer is widely used.

  By the way, in recent years, from the viewpoint of effective utilization of resources, it has been increasingly demanded to use so-called low-grade coal such as lignite and lignite as fuel for the combustion apparatus instead of bituminous coal and sub-bituminous coal. Similarly, from the viewpoint of effective use of resources, combustible materials such as petroleum coke and biomass raw materials have been increasingly used as raw materials for combustion devices.

However, many of the combustible materials such as the low-grade coal and biomass materials described above often contain a large amount of moisture.
The vertical crusher mentioned above is an excellent device that dehydrates the raw material with hot gas at the same time as pulverization, but if you try to forcibly dehydrate high-moisture raw material in the machine, you must raise the temperature of the hot gas. As a result, there is a problem that the risk of ignition or explosion is increased in the aircraft.
Therefore, when the amount of water in the raw material is extremely large, it is not possible to sufficiently dehydrate, and the raw material containing a large amount of water may be discharged out of the machine as a pulverized product.
Therefore, when combustible material with high moisture content is pulverized as it is with a vertical pulverizer and used as a fuel for the combustion apparatus, there is a risk that the efficiency of the combustion apparatus cannot be increased.

In addition, when using high-moisture raw materials as raw materials for combustion equipment, the most serious problem is necessary for transporting high-moisture raw materials from mining or sampling sites to power plants and plant factories with combustion equipment. Cost.
For example, it is generally well known that lignite has a very high moisture content in the interior, and the proportion of carbon content related to combustion is extremely low with respect to the weight of the entire lignite. If a low-grade coal with a moisture content of 50% is transported, half of the transport weight is moisture, and from the viewpoint of transporting fuel, transport is extremely inefficient.
In other words, in order to burn a low-grade coal such as lignite with a very high water content and obtain the same heat as a high-grade coal such as bituminous coal with a low water content, a higher amount of low-grade coal than a high-grade coal. It is necessary to burn the charcoal. In addition, there is a concern that raw materials with a high volatile content may ignite or explode during transportation.
In this way, the low-grade coal has a very low transport efficiency because the transport amount increases compared to the high-grade coal. Further, for the same reason, when a combustible material such as a biomass material containing a lot of moisture is used as a material for the combustion apparatus, the efficiency is extremely low.

  In order to solve the two problems described above, the moisture in the combustible material may be dehydrated and removed near the mining or sampling site. However, the combustible material such as the low-grade coal and biomass material described above is used. In general, it is difficult to sufficiently dehydrate the shape as it is mined or collected, and the internal moisture cannot be removed sufficiently.

For the above reasons, when using the above-mentioned combustible materials such as low-grade coal and biomass raw materials as fuel, combustible materials are once pulverized and dehydrated near the mining or collection site of combustible materials. In recent years, a technique has been proposed in which moisture is removed, and then molded into a predetermined shape and granulated, and then transported to a factory with a combustion apparatus.
With this method, even when using a high-moisture combustible as a fuel, it is only necessary to transport the combustible after removing the internal moisture, and the combustible that has been crushed and dehydrated is efficient. Even if it is powdery and bulky as it is and there is a risk of explosion during transportation, if the raw material after granulation is transported, the risk of explosion is small.

  As a technology for improving the safety and reducing the transportation cost by once transporting the powdered fuel after granulating it with a granulator, for example, the technology disclosed in Patent Document 1 etc. There is.

JP 2007-23239 A

The technique disclosed in Patent Document 1 is a biomass raw material supply system, and discloses a technique for reducing the transportation cost by once granulating a raw material pulverized by a pulverizer with a granulator.

In the case of granulating low-grade coal such as lignite, there is known a method of granulating by compacting with a pressing device such as a roll press.
If the powder is consolidated by a press device such as a roll press, the bulk of the raw material after pulverization can be drastically reduced, and the strength of the raw material body after granulation is remarkably improved. The risk of explosion is greatly reduced because it is difficult to break during transportation and dust is not easily generated.

However, in order to carry out the transportation method described above, the shape of the raw material that has been granulated by an artificial method is rounded so that the granulation is easy to granulate and is difficult to break during transportation. The surface is smooth.
For example, when the raw material after pulverization is compacted and granulated with a press device such as a roll press in order to increase the bulk density, the shape is usually approximately spherical or approximately almond so that it can be easily removed from the press mold. (Or rugby ball shape), and its surface is strongly consolidated, resulting in a hard and smooth surface. In other words, the raw material after granulation has an extremely slippery shape and a shape having a surface.

In order to improve the combustion efficiency of the combustion apparatus, for example, it is advantageous to pulverize the raw material such as coal as much as possible. Therefore, in the above-described vertical pulverizer, the raw material is disposed between the pulverizing roller and the rotary table. The material is pulverized so that it is crushed with a pulverizing roller. However, when the raw material is pulverized by the pulverizing roller, the raw material after granulation described above has a slippery shape and a shape having a surface, so that the raw material is not sandwiched between the pulverizing roller and the rotary table. As a result, sufficient pulverization could not be performed, and as a result, the pulverization efficiency was lowered.

  The present invention has been made in view of the above requirements, and relates to a pulverization method and a pulverization system suitable for efficiently pulverizing raw materials after granulation.

In order to achieve the above object, the raw material grinding method according to the present invention comprises:
(1) The granulated raw material is obtained by crushing or pulverizing lignite or lignite once, removing moisture and drying, and then molding and granulating with a granulator, which is substantially spherical Or a granulator that is granulated in a substantially almond shape and has a maximum dimension of 10 mm or more, and a crusher that crushes the raw material with a cutting blade, a movable plate, or a hammer, and a variable speed rotational speed of the raw material. by using the rotary table as the vertical pulverizing apparatus for pulverizing the pulverizing rollers, substantially spherical by the granulator, or the raw material was granulated in a substantially almond-shaped, crushed and fed to the crusher, the angular shape Then, it is supplied to the vertical crusher and pulverized.

Since the raw material after granulation has many corners and has a smooth and rounded shape, as it is, the raw material is not easily caught by the grinding roller and is difficult to grind.
In the present invention, the granulated raw material is crushed by a crusher in advance and formed into a shape that can be easily bitten by a crushing roller, and then pulverized by a crushing roller.
According to the present invention, slippage is unlikely to occur between the pulverizing roller and the raw material, and the raw material is efficiently sandwiched and caught by the pulverizing roller, so that efficient pulverization is possible.

  In particular, the raw material that has been compacted, molded, and granulated by a pressing device such as a roll press has a substantially spherical or almost almond shape so that the raw material after being granulated from the press mold can be easily removed. The shape is rounded), and the surface is hard and slippery, and the effect of the application of the present invention is great.

Moreover, when the size of the raw material after granulation is 10 mm or more, it may be easily caught and caught in a gap between the grinding roller and the rotary table.
In the present invention, the raw material granulated in advance with a crusher is crushed and reduced, and at the same time, it is supplied between the crushing roller and the rotary table by forming a fractured surface and increasing the number of squared or uneven surfaces. Increase the coefficient of friction of the raw material to make it difficult for the grinding roller and the raw material to slip.

  In addition, when granulated after pulverizing and dewatering lignite and lignite, a significant improvement in transportation efficiency can be expected, but lignite and lignite are particularly hard and slippery when compacted, The effects of the present invention described above are remarkable.

Moreover, even if vibration occurs for some reason during operation, vibration can be suppressed by arbitrarily changing the rotation speed of the rotary table.

Hereinafter, a preferred example of an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram for explaining a configuration of a grinding system according to the present embodiment. FIG. 2 is a cross-sectional view of the vertical crusher used in the present embodiment, and FIG. 3 is a cross-sectional view of the main part of the jaw crusher used in the present embodiment. FIG. 4 is an explanatory diagram for explaining the configuration of the roll press, and FIG. 5 is a conceptual diagram for explaining the appearance of the granulated raw material granulated using the roll press. FIG. 6 is a conceptual diagram illustrating a change in shape when the granulated raw material is crushed by a crusher. FIG. 7 is a diagram for comparing particle size distributions, where (B) shows the particle size distribution of the granulated raw material, and (A) shows the particle size distribution when the granulated raw material is crushed.

Hereinafter, an example of a preferable configuration of the grinding system 10 according to the embodiment of the present invention will be described.
In the embodiment of the pulverization system shown in FIG. 1, the crusher includes a jaw crusher 50 and the vertical pulverizer 1 as a pulverizer, and the raw material after granulation (granulated raw material) stored in the raw material hopper 20 is The jaw crusher 50 is put through the bucket elevator 25 and the belt conveyor to be crushed. Also,
The raw material crushed by the jaw crusher 50 is put into the vertical pulverizer 1 and pulverized, and the raw material pulverized by the vertical pulverizer 1 is supplied to the burner 84 as fuel.
Note that the vertical crusher 1 used in the present embodiment is a variable speed vertical crusher 1 that includes an inverter power source as a drive power source and can freely change the rotation speed of the rotary table during operation.

Hereinafter, the granulation process of the raw material will be briefly described by taking a case of lignite as an example.
In the present embodiment, lignite is exemplified as a preferred example, but the raw material that can be used in the present invention is not limited to this, and lignite, or in the range not departing from the scope of the present invention, Other known combustible materials such as petroleum coke and biomass raw materials may be used as raw materials.

The lignite mined from the mining site contains a lot of moisture and the like inside. Since lignite containing a lot of moisture has a small amount of effective fixed carbon and a high transportation cost, it is necessary to remove moisture in order to improve the proportion of fixed carbon.
As for the moisture inside the lignite, since the lignite cannot be removed even if it is dehydrated as it is, it is once crushed by a crusher or crusher to make the particle size finer, and then dehydrated. To remove. The lignite after removing moisture becomes lighter in weight, but it is powdery and bulky, so it is molded into a predetermined shape and granulated using a press granulator such as a roll press. Increase transportation efficiency.

In addition, the conceptual diagram of the roll press 60 used for this embodiment is shown in FIG. As can be seen from the AA diagram in FIG. 4B, a plurality of elliptical recesses 68 are formed on the surfaces of the two rolls 64. In the roll press 60 shown in FIG. 4, the raw material supplied from the raw material inlet 61 at the top of the roll press 60 and flowing between the two rollers 64 is consolidated in the mold portion of the concave portion 68 of the roll 64. Then, it is granulated and discharged from the lower outlet 63.

  About the granulated raw material, the typical shape is shown to FIG. 5 (1)-(4). The granulated raw material is large in size and shaped like a so-called large pellet, so the volume (bulk) during transportation can be reduced, dust is difficult to fly, and there is a risk of explosion. It has the advantage of being small. In particular, the shape of the raw material that has been strongly compacted and granulated by a two-axis roll press 60 is shown in FIGS. In order to improve the granulation property by the roll press, the shape is smooth, almost spherical or almost almond with few corners.

The size of the granulated raw material is a substantially almond-shaped raw material shown in FIG. 6 (1), and the approximate dimensions are about 40 mm for the major axis and about 20 mm for the minor axis. Similarly, in all of the devices shown in FIGS. 6 (2) to 6 (4), the long diameter portion is 10 mm or more.
Although it depends on the size of the pulverizer, the dimensions of the raw material after granulation are not limited in the present invention except for a granulated raw material that is so large that it cannot be physically pulverized in the pulverizer of the size to be used. However, when the granulated raw material has a large portion of 10 mm or more, a phenomenon that the raw material after granulation becomes difficult to be caught between the pulverizing roller and the rotary table tends to occur.

  Moreover, as the shape of the raw material after granulation, as shown in (1) to (3) of FIG. 6, an oval and rounded material is particularly difficult to bite into the grinding roller. Further, in the case of lignite and lignite containing carbon, the surface is strongly consolidated, and in particular, it tends to be slippery.

  Hereinafter, an example of a preferred embodiment of the granulating raw material pulverization method according to the present invention will be described.

First, as a first step, the granulated raw material stored in the raw material hopper 20 is passed through a bucket elevator 25 and a belt conveyor from a raw material charging port (not shown) disposed on the upper portion of the jaw crusher 50, and then the jaw crusher. 50 is supplied inside.
Here, the jaw crusher 50 includes a fixed plate 55 and a movable plate 56. The fixed plate 55 is fixed to the frame of the jaw crusher 50, and the movable plate 56 is attached to the eccentric rotating shaft 53 and fixed. It is configured to move back and forth toward 55.
The raw material after granulation supplied to the jaw crusher 50 flows into a gap portion between the fixed plate 55 and the movable plate 56 provided in the jaw crusher 50. And the raw material after granulation is crushed by the movable plate 56 moving back and forth with respect to the fixed plate 55 in a state where the raw material after granulation enters the gap. The granulated raw material is crushed and then discharged from the lower outlet 63 disposed at the lower portion of the jaw crusher 50.

  The shape of the granulated raw material before being crushed by the jaw crusher 50 and the granulated raw material after being crushed are shown in FIG. Prior to crushing, the granulated raw material (1) having a substantially almond shape with a smooth surface becomes a raw material (2) having a smooth, square fractured surface, after breaking into a plurality of pieces. .

In the present embodiment, the jaw crusher 50 is used as a crusher. However, the crusher applicable to the present invention is not limited to this, and may be, for example, a rotary blade without departing from the spirit of the present invention. It may be a crusher of the type that cuts and crushes the raw material, or may be a hammer type crusher or other known type of crusher. It may be a crusher capable of efficiently crushing the raw material and dividing the raw material into a plurality of pieces to generate a fracture surface.
In the present application, a jaw crusher type crusher is exemplified as one of preferable crushers capable of efficiently crushing substantially spherical or substantially almond-shaped pellets.

  Normally, the granulation raw material as described above can be put into the vertical pulverizer 1 and pulverized without preliminarily pulverizing with a pulverizer. However, in the present invention, the granulated raw material that has been preliminarily pulverized and pretreated in advance is pulverized by the vertical pulverizer 1 particularly for the purpose of adjusting the frictional force between the pulverizing roller and the rotary table.

Next, as a second step, the granulated raw material crushed by the jaw crusher 50 is fed into the raw material inlet 35 of the vertical crusher 1 through a belt conveyor.
As an example of the vertical pulverizer used in this embodiment, the vertical pulverizer 1 as shown in FIG. 2 is used. However, the structure of the vertical pulverizer 1 that can be used in the present invention is not limited thereto. Of course, other types of vertical crushers may be used as long as they do not depart from the scope of application of the present invention. For example, a type that does not include a classifier inside. Alternatively, it may be a tire type vertical grinder having a spherical shape of the grinding roller.

  The raw material supplied from the raw material charging port 35 to the central portion of the rotary table 2 through the raw material charging chute 13 moves toward the outer peripheral portion of the rotary table 2, is sandwiched between the rotary table 2 and the crushing roller 3, and is bitten. And crushed.

  Part of the raw material that is pulverized by being squeezed between the rotary table 2 and the pulverizing roller 3 passes over the dam ring provided around the outer edge of the rotary table, and the gap between the outer peripheral portion of the upper surface of the rotary table 2 and the lower casing. It heads for the annular passage 30 which is.

During operation of the vertical pulverizer 1, gas is introduced into the machine from the annular passage 33 provided at the lower part of the pulverizer using the exhaust fan 89, and the introduced gas passes through the classifier 14. It is discharged out of the machine through a product outlet 39 provided above the crusher.
As a result, in the casing of the vertical crusher 1, a gas flow from the lower side of the rotary table 2 toward the classifier 14 is generated, and a part of the raw material that has reached the annular passage 30 over the dam ring is It is blown up by the gas flow and rises in the casing.

The airflow rising in the casing is influenced by the rotating classifying blade 14A of the classifier 14 and is an airflow rising while turning.
Among the raw materials blown up by the air current, the raw material having a large diameter and a large weight falls below the casing due to its weight, or deviates from the air current due to the centrifugal force generated in the raw material itself by swirling and moves below the casing. It cannot pass through the classification blade 14A of the classifier 14 due to falling or the like.

  The material that has failed to pass through the classification blade 14A and has fallen is again caught in the crushing roller 3 and pulverized, or dropped from the annular passage 30 to the lower side of the rotary table, and the vertical crusher 1 from the lower outlet 34. After being taken out, the material is introduced again from the material inlet 35 of the mold crusher 1 through a conveyor such as a bucket elevator (not shown) and pulverized.

The raw material that has passed through the classification blade 14A is taken out of the apparatus together with the gas from the product outlet 39 and fed to the burner 84 as fuel for the combustion apparatus.

  In the prior art, when the raw material charged into the vertical crusher 1 is, for example, an almond-shaped granulated raw material, when the raw material is sandwiched between the crushing roller 3 and the rotary table 2, the crushing efficiency is reduced. Make it worse.

According to the present embodiment, the raw material after granulation by the roll press 60 has a shape that can be easily bitten by the crushing roller by crushing by the jaw crusher 50 as the first stroke, and then the process proceeds to the second stroke. Finely pulverize with a vertical crusher 1.
Therefore, since the raw material put into the vertical crusher 1 has a shape having an angular portion, it is difficult to slip when sandwiched between the crushing roller 3 and the rotary table 2 and the crushing efficiency is improved. . In particular, as in this embodiment, the raw material compacted and granulated by the roll press 60 has a substantially spherical or almost almond shape, and has a large effect because the surface is hard and slippery.

Further, if the size of the raw material after granulation is 10 mm or more in a large portion as in this embodiment, there is a possibility that it becomes caught and resisted when it is caught in the gap between the grinding roller and the rotary table. . In the present embodiment, since the raw material granulated in advance by the jaw crusher 50 is crushed to reduce the size of the raw material supplied between the crushing roller and the rotary table, the above-described resistance hardly occurs.

  In addition, when lignite or lignite is compacted, the surface is particularly hard and slippery, so the effects of the present invention described above are remarkable.

In general, the size of general coal pulverized by a vertical pulverizer is usually 50 mm or less. Since the raw material after granulation is usually produced at 50 mm or less, it is not a size that cannot be pulverized by a vertical crusher even if preliminarily crushed.
However, the artificially granulated raw material has a very narrow particle size distribution as shown in FIG. 7, for example, as the data of the granulated curve (B) shows a very sharp rise. Concentrated on, it has a uniform shape.
Therefore, the granulated raw materials that are layered on the rotary table create a large gap between each other, and as a result, they are only in partial contact with each other, so that they are in a slippery state, and thus pulverized. The friction coefficient suitable for

In the present invention, the granulated raw material is crushed in advance, for example, by widening the particle size distribution of the raw material, as shown by the curve (A) in FIG. As a result, it can be expected that the grinding roller and the raw material are less likely to slip. In addition, the raw material that has been crushed in advance has many fracture surfaces and has many squares and irregularities on the surface, so that the coefficient of friction increases, and as a result, the grinding roller and the raw material slip. Since it can be reduced, vibration can be reduced.
In addition, the figure shown in FIG. 7 is a figure which shows the passage rate of a sieve, and has described the magnitude | size of the sieve mesh to be used as a particle diameter. For example, when the particle diameter is described as 20 mm, it indicates the passing rate of a sieve having a sieve mesh size (wire inner dimension) of 20 mm long × 20 mm wide.

Further, with the configuration of the present embodiment, even if vibration occurs for some reason during operation, vibration can be suppressed by arbitrarily changing the rotation speed of the rotary table.

As described above, the pulverization method and the pulverization system according to the present invention are useful when finely pulverizing a granular raw material, which is obtained by granulating a combustible material once and artificially manufacturing it.

It is explanatory drawing for demonstrating the structure of the grinding | pulverization system concerning this embodiment. It is sectional drawing of the vertical crusher used for this embodiment. It is sectional drawing of the jaw crusher used for this embodiment. It is explanatory drawing for demonstrating the structure of a roll press. It is a conceptual diagram explaining the external appearance of the granulation raw material granulated using the roll press. It is a conceptual diagram explaining the change of the shape at the time of crushing a granulation raw material with a crusher. It is a comparison figure of particle size distribution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical crusher 2 Rotary table 3 Crushing roller 10 Crushing system 13 Raw material input chute (raw material chute)
14 Classifier 14A Classifying blade 20 Raw material hopper 25 Bucket elevator 30 Annular passage 34 Lower outlet 35 Raw material inlet 39 Product outlet 50 Jaw crusher 53 Rotating shaft 55 Fixed plate 56 Movable plate 60 Roll press 84 Burner

Claims (1)

The granulated raw material is lignite or lignite, once crushed or pulverized, then dried by removing moisture, and then molded and granulated by a granulator,
In the case of being granulated in a substantially spherical shape or a substantially almond shape, the maximum dimension is 10 mm or more,
Using a crusher that crushes the raw material with a cutting blade, a movable plate, or a hammer, and a vertical crusher that crushes the raw material with a rotary table with a variable rotational speed and a crushing roller,
Substantially spherical by the granulator, or the raw material was granulated in a substantially almond-shaped, crushed and fed to the crusher, after the angular shape, grinding the raw material to be pulverized is supplied to該竪pulverizer Method.

Images