JP5931349B2 - Vertical roller mill - Google Patents

Description

  The present invention relates to a vertical roller mill comprising a combination of a rotary table rotating in the circumferential direction and a plurality of vertical rollers arranged at fixed positions on the table at intervals in the rotary table rotation direction. The present invention relates to a versatile vertical roller mill suitable for fine pulverization of coal and petroleum coke, pulverization of raw materials in which pulverized fine powder such as limestone easily adheres to the pulverized surface.

  Many boilers for power generation still use coal or petroleum coke as fuel. This is because fuel costs are low and the amount of power generation can be easily adjusted. Of course, China and other developing countries rely on coal and petroleum coke for a considerable portion of the amount of power generation. . However, coal and petroleum coke have the major drawback of high carbon dioxide emissions.

  Japan pledged to reduce 25% of carbon dioxide emissions in 1990 by 2020 worldwide. This commitment is an extremely difficult figure that the public and industry have to bear a great responsibility to achieve, but after making a commitment, we must strive toward that goal. To that end, it is very important to reduce the amount of carbon dioxide generated from coal and petroleum coke used in power generation boilers.

  In other words, the use of coal or petroleum coke as a fuel for power generation has an extremely large amount of carbon dioxide emissions, and therefore, the carbon dioxide emissions have been evaluated as the source of various evils. However, it is impossible for Japan without resources to immediately stop the use of coal among fossil fuels. At least until nuclear power generation or clean alternative energy is prepared, its use cannot be stopped because of its economic efficiency, convenience, reserves, and difficulty in depletion.

  Therefore, how to control the amount of carbon dioxide emitted from these fossil fuels will be an important technical issue in the future, and the development of new technologies to solve this issue is an extremely important theme. Become. As part of this, it is worth considering the coal supplied to the boiler and the pulverization of petroleum coke at the stage of pulverization, thereby reducing the amount of carbon dioxide generated. Of course, the reduction effect achieved by one crushing mill is insignificant, but the total number of units used in the world is innumerable, and when combined, this can contribute to a huge reduction in carbon dioxide emissions. Is possible. In advanced countries, especially Japan, which is a technology-based country, it is considered that its mission and responsibility are to take the initiative in pulverization with a grinding mill.

The present inventor has paid attention to this from an early stage and worked on measures for pulverization in a pulverizing mill, and has also achieved great results. A typical technique is the improvement of the roller grinding surface shape described in Patent Documents 1 and 2, especially the development of a slit roller. The slit roller is formed by forming slit grooves in the center line direction (a direction perpendicular to the roller circumferential direction) at predetermined intervals in the circumferential direction on the outer circumferential surface, which is the grinding surface of the grinding roller. As a result, in the vertical roller mill field, compared to existing mills, the biting property of the pulverized material has been improved and the fine powder rate has been improved.

  In other words, in the case of a thermal power plant, the average coal pulverization particle size is 200 mesh passing and 75% average, but this pulverization particle size is further reduced, and 200 mesh passing and 75% over fine powder is larger than the conventional mill. By making it possible to collect it, it has succeeded in improving the combustion efficiency in the boiler and, as a result, enabling complete combustion and contributing to the reduction of carbon dioxide emissions.

  In addition, pig iron is produced in a blast furnace at a smelter, but a large amount of coke reducing gas is generated and used to reduce and dissolve iron ore, but because coke is produced from expensive caking coal, it is very In order to reduce the amount used, pulverized coal that is cheaper than the blast furnace tuyere is blown to reduce coke consumption and reduce pig iron production costs.

  Many of the slit rollers developed by the present inventor have been adopted in blast furnace pulverized coal blowing equipment, which greatly contributes to cost reduction. At the Sakai Works, the cost reduction effect is said to reach 600 to 700 million yen per year. When the production amount of fine powder of 200 mesh or less including 200 mesh is increased by about 20% or more compared to the conventional mill, the blast furnace combustion efficiency is increased, which contributes to further reduction of coke consumption. In other words, the reduction of coke consumption leads to the reduction of carbon dioxide generated during coke production, and makes a great contribution to the reduction.

  A vertical roller mill is often used as a coal pulverizer in a power generation boiler. A vertical roller mill consists of a combination of a rotary table rotating in the circumferential direction and a plurality of vertical rollers arranged at fixed positions on the table at intervals in the rotary table rotation direction. The material is caught between the vertical rollers and pulverized. The pulverized material is air-carryed upward by a carrier air-flow and classified by a classifier. The coal having the required particle size is captured and conveyed to the subsequent stage, and the coal having a larger particle size is returned to the inside of the mill again.

The vertical roller mill for coal crushing is a Roche mill type in which the shape of the crushing roller is a trapezoidal shape (simply called a trapezoidal type), and the annular crushing part on the upper surface of the rotary table is a horizontal surface, and the outer peripheral surface of the crushing roller in the rotational direction It is roughly classified into a tire type type which is curved in a direction convex toward the outer peripheral side within a right-angled surface, and an annular groove having a cross-sectional arc shape is formed on the upper surface of the rotary table to fit the outer peripheral surface of the grinding roller. The tire type crushing roller is further divided into a convex type tire having a ratio of the maximum diameter D to the radius of curvature R in a plane perpendicular to the rotation direction of the tire crushing surface of 4.3 or more, and a flat type tire having a ratio of less than 4.3. Be divided. When this inventor investigated D / R of the tire type | mold roller marketed, average D / R of the former convex type tire is 4.5-5.0, and the average of the latter flat type tire Since the typical D / R was in the range of 3.8 to 4.1, D / R = 4.3 is appropriate as a branch point between the two.

  Apart from slit rollers, the inventor has also continued research on screw rollers. A screw roller is provided with a plurality of screw grooves (spiral grooves) inclined with respect to the roller circumferential direction in parallel on the roller outer peripheral surface (Patent Documents 3 and 4). The slit groove in the direction parallel to the roller shaft (perpendicular to the circumferential direction of the roller) is excellent in raw material biting performance, but has an extremely high ability to scatter to the outside. On the other hand, in the circumferential groove in the direction perpendicular to the roller shaft (roller circumferential direction), the pulverized raw material cannot be bitten. On the other hand, if the slit groove is screw-shaped and formed in the direction in which the pulverized raw material is scraped back to the center side of the table, the amount of crushed raw material inserted in the pulverization space formed between the roller and the table increases Even in the case of the same roller clearance, the contact friction force with the roller is increased, and it can be expected that mill vibration is effectively prevented during low load operation in a thermal power plant.

However, there is a problem common to both the pulverizing roller in which the slit groove for improving the biting property is formed on the entire pulverizing surface of the vertical pulverizing roller and the pulverizing roller in which the screw groove having excellent pulverizing raw material transportability is formed. This has become clear from many years of experience and experimental studies by the present inventors. That is, in the case of a roller with a slit groove and a roller with a screw groove, with respect to a pulverized raw material having a high hardness, there is a situation where the effective use of the excellent added value that it has cannot be fully exhibited due to the occurrence of extreme wear. It is.

The present inventor has confirmed that even when crushing an adhesive substance such as limestone, there is a situation in which the effective use of excellent added value possessed by a grooved roller such as a slit roller or a screw roller cannot be exhibited 100%. doing. In order to efficiently grind adhesive substances such as limestone, it has already been proposed to provide a slit groove that intersects the rotation direction on the grinding surface of the rotary table surface, but the grinding roller is a flat roller with a smooth surface. (Patent Document 5).

  Under such circumstances, the present inventor has continuously searched for a method for maximizing the effectiveness of the grooved roller. If this is realized, the crushing roller with slit groove and the crushing roller with screw groove can be used for all materials of high hardness material, high moisture content material, adhesion and adhesive material, except for any crushing material, i.e. ignitable material. However, it is possible to achieve a finished shape of a vertical mill roller having a performance capable of exerting the true value of the grindability.

Therefore, the inventor decided to go back to the basics, elucidate the true function and action of the existing grinding roller, and fundamentally develop a new grinding surface. For this purpose, the present inventor first investigated the problems common to the slit grooved roller and the screw grooved roller. As a result, the following two problems with respect to the roller circumferential direction and the roller axial direction emerged.

The first problem is a problem related to the wear form in the roller circumferential direction (rotation direction) of the grinding roller grinding surface. Details are as follows . When grinding hard materials, the slit groove has a major drawback that it tends to cause premature wear. That is, conventionally, slit grooves are formed on the entire roller grinding surface. In such a crushing roller, when a soft raw material is crushed, the wear of the soft ribs forming the slit grooves gradually proceeds, and the slit grooves start to be formed, and the wear-resistant hardened metal interposed between the soft ribs is the gear. Appear in the form. However, since the pulverized raw material is soft, the edges of the hardened metal that has emerged remain almost at right angles without being worn, and as a result, they show excellent biting and wear resistance, and they have a long period of time. Maintains effects and longevity and gives satisfactory use results. In the case of pulverizing such a soft raw material, even if slit grooves and screw grooves were formed on the entire surface of the roller pulverization surface, the effect could be exhibited.

  For example, in the case of coal pulverization with an HGI of 45 or less or in slag pulverization of blast furnace slag, it was possible to exert a remarkable effect in improving productivity and extending the life.

  On the other hand, when grinding very hard grinding raw materials, the soft ribs forming the slit grooves will wear out early, and the wear resistant metal will appear like a gear in a short period of time, and the corner of the wear resistant metal will be While hard materials are efficiently ground to improve grinding efficiency, the hard gears are subject to extreme wear and the sharp gear shape changes to a chevron shape at an early stage. Phenomenon that forced to replace in a short period of time caused by excessive wear. The wear speed is extremely short compared with the existing circumferentially wound fill roller.

  For example, in the case of a cement raw material crushing roller used in a cement factory, the production amount per unit time has improved by about 20% or more, but the life has become less than half of the life of the existing build-up roller. The wear rate also increased dramatically when grinding very hard silica stones and ceramics, unweathered blast furnace slag, and low grade coal containing a large amount of ash.

From these phenomena, the present inventor found that the service life of rollers with slit grooves and rollers with screw grooves is not only dependent on the wear resistance of the wear-resistant metal employed, but also greatly on the shape of the grinding surface to be crushed. Judged to be dependent. As a result of numerical analysis, as a result of the analysis of the hardened metal having the same wear resistance, the edge portion of the gear shape in the roller with slit groove is larger than that in the case of the smooth pulverized surface circumferentially wound by the tire type roller. It has been found that the contact pressure increases about three times.

In general, it is said that the wear is proportional to the power of the surface pressure received by the wear surface, so that it is estimated that the wear received by the edge receives 2 to 4 times or more of the surface pressure compared to the smooth surface. Therefore, even when pulverizing hard pulverized raw materials, a new pulverized surface that can achieve high-efficiency pulverization of slit grooves and can ensure the same life as a smooth pulverized surface even when using the same wear-resistant metal is developed. The need is urgently needed.

The second problem is a problem relating to the wear form of the grinding roller grinding surface in the roller axial direction. That is, when the wear shape of the crushing roller is observed in detail, a deep wear groove is generated on the large diameter side and wear is generated on the small diameter side with respect to the trapezoidal roller crushing surface when the crushing efficiency is reduced and replaced. The shape that has not been shown. A convex roller (D / R = 5) with a tire type roller having a small curvature, like a trapezoid type roller, tends to generate maximum wear mainly on the large diameter side, and a flat type roller with a tire type roller having a large curvature. With regard to (D / R = 4), there was a tendency for maximum wear to occur on the small diameter side.

The grinding part that generates the maximum wear is the part that contributes most to the grinding among the grinding surfaces of all rollers, and is the area where the grinding work is the largest. it can. The other pulverized surfaces naturally pulverize fine powder, but rather than finely pulverizing because of less wear, the pulverized raw material supplied to the center of the rotary table is sent to the main pulverized surface together with centrifugal force. It was assumed that it was a transfer surface that played a role. This transfer pulverization surface is a part where the raw material is first bitten and has a major purpose of crushing the raw material having a large particle size. However, if the material transferability on this transfer pulverization surface is promoted by any means, the fine powder is pulverized. It was speculated that the sex could be greatly improved. At the stage of developing the slit groove, the emphasis was mainly on biting, but in crushing adhesive substances such as limestone, we developed a screw groove that is effective for effective crushing without causing adhesion to the rollers. Since then, I have noticed the importance of material transferability on the grinding surface.

Theoretically roller grinding surface was considered to be composed mainly main grinding surface of the area to be milled, the two grinding surfaces of the transfer surface of the region for feeding the raw material into the main grinding surface. By clarifying the division of roles for each individual grinding surface, it is possible to reliably and reliably transfer the raw material to the main grinding surface regardless of the type of raw material. This reduces the waste of wasted energy required for crushing, enables the design of a crushing surface that can perform crushing operations more efficiently, and also serves as a countermeasure against wear on the main crushing surface. We were able to recognize it based on experience and trial and error.

Thus, one of the important roles of the pulverizing surface is the transportability of the raw material. It turns out that the current smooth surface roller does not actually play its role. When pulverizing hard pulverized raw materials or pulverized raw materials with a lot of moisture, the pulverized surface is a smooth surface, so the biting property and transportability are inferior. As a result, the production of fine powder decreases. If excessive surface pressure is applied to the roller in order to suppress the slip and vibration of the roller, the shaft current of the mill increases and a large power loss occurs.

Japanese Patent No. 1618574 Japanese Patent No. 2863768 Japanese Utility Model Publication Sho 63-11939 International Publication WO2009 / 157335 Specification JP 2009-142809 A

An object of the present invention is to provide a high-performance and economical vertical roller mill that can solve both the circumferential and axial problems of the grinding roller grinding surface and can maintain excellent grinding performance for a long period of time. .

Theoretically, the grinding surface that plays the most important role in the productivity of fine powder is the main grinding surface. In order to make the fine powder crushing action more effective, it is possible to improve the fine powder crushing efficiency by increasing the effective crush area if there are no extra grooves such as slit grooves and screw grooves on the main crush surface. It is self-explanatory. If the main pulverized surface can be changed to a smooth surface, naturally, the unique phenomenon of severe wear on the gear-shaped hardened metal edge disappears, and a long life is achieved in the same way as the smooth surface. If you take into account the increase, you can get both. This is the first step in providing a complete solution.

However, the effect of improving the pulverization amount of the fine powder cannot be obtained only by changing the main pulverized surface to a smooth surface. If the pulverized raw material is not stably supplied continuously to the main pulverized surface, it becomes difficult to improve the productivity of fine powder. Thus, the complementary action of the grinding surface other than the main grinding surface is required, the transfer of the feed to any type of raw material will we reliably main grinding surface even if the action is to be determined as the complement activity.

When a large amount of raw material is fed to the pulverization surface, the raw material layer thickness naturally increases in the pulverization chamber formed between the roller and the table, the grinding action between the raw materials becomes remarkable, and the productivity of fine powder is improved. When the load surface pressure on the roller is constant, the layer thickness increases as the amount of biting increases, and as a result, the axial current of the mill increases due to the increase in work amount, but the pulverization amount of fine powder also increases. In comparison with the power intensity obtained by dividing the amount of power used by the amount of fine powder sampled to be obtained, the larger the denominator, the lower the power intensity, contributing to energy saving. Speaking of the correlation between the roller grinding area and the power consumption, as the roller surface area increases, the frictional resistance increases and the power consumption also tends to increase, so the main grinding surface is a 100% smooth surface. However, since the contact area cannot be reduced, the transfer surface is not mainly pulverized, so it is possible to reduce the contact area by forming a groove.

In the vertical roller mill, crushing rollers and the main grinding surface that mainly pulverized fine powder in one of the grinding surface, given by sharing the two roles of the grinding surface to transport the pulverized starting material in the main grinding surface, grinding function of the roller It becomes very easy to understand. As an example, consider a trapezoidal roller. The main pulverization surface that mainly pulverizes the fine powder is located on the large diameter side, and the small diameter side can be clearly described as a pulverization surface for transferring the raw material to the large diameter side. Originally, the crushing action is not clearly divided in this way. For vertical roller mills, the pulverized raw material is supplied from the center of the mill and is driven out of the table by the centrifugal force generated by the table rotation. During that time, the coarse raw material is caught in the gap between the roller and the table and moves outward. As the process proceeds, the pulverization progresses in stages from coarse grains to fine grains. Of course, fine pulverization is also performed on the small diameter side, but the frequency is very high on the large diameter side, and coarse particles are mainly bitten on the small diameter side, and the large diameter side is gradually pulverized into fine particles. The fine powder is pulverized mainly in the main pulverization zone. As evidence, the grinding surface on the large diameter side, which has the most pulverizing action, shows an extreme wear region, and the actual progress is that the progress of wear is not observed on the small diameter side.

These facts, coexistence of the verification, the inventors have a main grinding surface mainly performing grinding of fines in a single roller milling surface, the raw material reliably in the main grinding surface, in each other and stably feeding the raw material transporting surface It was theoretically and empirically derived that an effective pulverizing effect could not be obtained if either one was missing.

  In raw material crushing with low adhesion, slit grooves that are parallel to the roller shaft or have an angle of up to 45 degrees are effective for improving biting properties. The screw groove with an angle of 45 degrees or more and 85 degree which improves the transportability is effective, and the improvement of the grindability for all grinding raw materials is established by including two kinds of grooves Was verified by grinding experiments.

On the basis of such a verification result, the present inventors have While considered separately in the surface of the main grinding surface and the other surface of the previously pulverized roller, and the smooth surface of the main grinding surface, grinding other than the main grinding surface A vertical roller mill having a hybrid grinding surface structure in which slit grooves inclined at an angle of 45 ° or more perpendicular to the roller circumferential direction or screw grooves inclined at an angle of 45 ° or less with respect to the roller circumferential direction are formed on the surface While the use grinding roller was proposed by No. PCT / JP2010 / 62546, the grinding surface of the rotary table likewise while the smooth surface of the main grinding surface, the grinding surface other than the main grinding surface with respect to the table rotation direction hybrid grinding surface structure forming a right angle or 45 degrees greater than angle inclined slit grooves, or inclined screw groove at an angle of less than 45 degrees 5 degrees or more with respect to the table rotation direction It was found that effective.

The vertical roller mill of the present invention has been developed on the basis of such knowledge, and the table is spaced from the rotating table rotating in the circumferential direction and the rotating direction of the rotating table (that is, the direction of rotation , the same applies hereinafter ) on the table. of the vertical roller mill comprising a combination of a plurality of vertical pulverizing rollers arranged in a fixed position, it consists of a main grinding surface and grinding surface other than the main grinding surface the roller grinding surfaces primarily for fine grinding, the grinding roller of turntable grinding surface opposite to a surface, the main grinding surface of the rotary table side facing is a smooth surface in the main grinding surface of the grinding roller, the rotary table grinding surface other than the main grinding surface with respect to the table rotation direction Ha right angle or slit grooves inclined at an angle less than 45 degrees than 90 degrees, or angled screw groove at an angle of less than 45 degrees 5 degrees or more with respect to the table rotation direction is formed Has Brides grinding surface structure on the rotary table side.

In the vertical roller mill of the present invention, among the rotary table grinding surface opposed to the surface of the grinding roller, the main grinding surface of the rotary table side opposite to the main grinding surface of the grinding roller is a smooth surface, other than the main grinding surface since hybrid grinding surface structures slit groove or screw grooves are formed in the rotary table grinding surface is imparted to the rotary table, the effective milling area ratio in the main grinding surface while leaving the transfer due to the slit groove and the screw groove 100 As a result, it is possible to further improve the pulverizing effect by providing slit grooves and screw grooves on the pulverizing surface of the rotary table.

The types of grooves provided on the rotary table grinding surface other than the main grinding surface, white the raw material transfer property Whether the biting property, not enough of the impact depends on the type of differences in the grooves provided on the grinding surface of the grinding roller. For this reason, the kind of groove | channel by the kind of grinding | pulverization raw material does not need to be exact | strict. A slit groove may be used for pulverization of limestone, or a screw groove may be used. Moreover, a slit groove | channel may be used for the grinding | pulverization of coal, and a screw groove | channel may be used. Since some coals, like Lexsei coal, have a lot of moisture and high adhesion, the distinction between the two becomes more gradual.

On the other hand, with respect to direction of crushing rollers, the type of grooves are formed in the grinding surface does not essentially limited, and may but the entire grinding surface as smooth surface, in order to enhance the grinding property, the type of grinding material The selection of the corresponding groove type is important. That is, when the pulverized raw material has little adhesion, a slit groove having a large angle with respect to the circumferential direction of the roller for improving the biting property on the pulverized surface or a screw groove having an angle close to the circumferential direction of the roller for improving the transportability is provided. It is good to form. When the pulverized raw material is an adhesive substance, a screw groove that is inclined at an angle of 45 ° to 85 ° with respect to the roller shaft (5 ° to 45 ° with respect to the roller circumferential direction) is limitedly formed. It is good. The reason for this is that when the groove angle is parallel to the roller axis or less than 45 degrees, the biting property is exerted and adhesion or transfer occurs on the roller surface, making the pulverization operation difficult. A groove angle that exhibits transportability is desirable, specifically, 45 to 85 degrees, and particularly an average angle of 60 to 70 degrees is desirable as the screw groove angle.

In addition, as described above, there are three types of grinding rollers. The position of the main grinding surface differs depending on the type of grinding roller. In the trapezoidal roller, the pulverized surface of the large diameter portion becomes the main pulverized surface. In the tire type roller, the main crushing surface of the flat type roller having a large tire R exists in one of the small diameter portions on both sides in operation, but is present in the small diameter portion on both sides in terms of wear due to reverse use. A convex roller with a small tire R has a main pulverized surface in the center (large diameter) of the tire for operation, so that it can be reversed, but it is also mainly in the center of the tire (large diameter) in terms of wear. There is a grinding surface. Accordingly, the position of the main grinding surface on the rotary table grinding surface also varies depending on the type of grinding roller to be combined. By the way, the main grinding surface in each grinding roller is a region showing wear of 2/3 or more of the maximum wear amount on the outer peripheral surface of the roller, and is a region of 30 to 40% expressed by the axial length of the roller. is there.

Preferred grinding rollers are listed as follows. The limestone is very soft and the roller wear is very low, so the trapezoidal roller, tire convex roller and tire flat roller are all effective. Since it is harder than limestone and has severe roller wear, a tire convex roller and a tire flat roller capable of reversing the grinding surface are particularly effective from the viewpoint of cost merit.

[1] This is a trapezoidal roller, and the entire grinding surface including the main grinding surface on the large diameter side forms a screw groove in the material discharge direction (ie, the discharge promotion direction, the same applies hereinafter) that forcibly conveys the ground material from the inside to the outside. A transporting trapezoidal roller that is a raw material transport surface.
[2] A tire convex roller, and the entire pulverized surface including the main pulverized surface of the central large-diameter portion is a material transfer surface formed with a screw groove in the material discharge direction for forcibly conveying the pulverized material from the inside to the outside. Transport type tire convex roller.
[3] A tire flat roller, and the entire grinding surface including the main grinding surfaces on both sides located in the small-diameter portions on both sides with reverse use (that is, changing the mounting direction of the roller) A reverse feed type tire flat roller which is a raw material transfer surface in which a screw groove in a reverse direction for reverse feed is formed.
[4] A tire flat roller, and the entire grinding surface including the main grinding surfaces on both sides located at the small-diameter portions on both sides with reverse use (that is, changing the mounting direction of the roller) A transfer-type tire flat roller that is a material transfer surface on which screw grooves are formed in the material discharge direction for forced conveyance.

The vertical roller mill of the present invention is based on a novel pulverization theory even in the world, and the main pulverized surface that receives the most wear can be made smooth to avoid the occurrence of extreme wear unique to slit grooves, and at least smooth Since the surface can be improved to the same level of wear and the effective pulverization area can be made 100%, it can contribute to the improvement of the production amount of fine powder.

Regarding the power consumption of the crusher, it is possible to reduce the wasteful power consumption by reducing the surface area of the raw material transfer surface and reducing the contact area compared to the smooth surface roller by sharing the function of the crushing surface. It is.

For the present inventor who has continued research on the grinding surface shape for many years, the establishment of a complete grinding surface technology including two forms of slit grooves and screw grooves is one ultimate goal. However, by further enhancing the effect of the screw groove, we have succeeded in developing a finished shape of a pulverized surface that provides a further excellent effect that is not seen in the practical world. The result is a revolutionary grinding surface forms described above.

It is a front view of the mill principal part which shows the basic structure of the vertical roller mill of this invention about the Roche mill using a trapezoid type roller. BRIEF DESCRIPTION OF THE DRAWINGS It is a front view of the grinding | pulverization roller used for the vertical roller mill of this invention, (a) is a trapezoid type roller for limestone grinding, (b) is a tire type flat roller for limestone grinding, (c) is a tire convex type for limestone grinding. Each roller is shown. It is a top view of the rotary table used for the vertical roller mill of the present invention, (a) is a rotary table combined with a trapezoidal roller for limestone grinding, (b) is a rotary table combined with a flattened roller for limestone grinding, (C) has shown the rotary table combined with the tire convex roller for limestone grinding | pulverization, respectively. It is a front view of another crushing roller used for the vertical roller mill of the present invention, (a) shows a tire flat type roller for coal crushing, and (b) shows a tire convex roller for coal crushing. It is a top view of another rotary table used for the vertical roller mill of this invention, (a) is a rotary table combined with the tire flat type roller for coal grinding, (b) is combined with the tire convex roller for coal grinding. Each of the rotary tables is shown. It is a vertical side view which shows a table groove | channel shape. It is a block diagram of the experimental small crusher.

  Embodiments of the present invention will be described below with reference to the drawings.

  The vertical mill roller shown in FIG. 1 is a Roche mill that uses a trapezoidal roller 10A as a grinding roller. The trapezoidal rollers 10A are arranged at equal intervals in the circumferential direction on a horizontal rotary table 20A driven in the circumferential direction. The pulverized raw material supplied onto the central portion of the rotary table 20A is caught between the pulverizing rollers as the rotary table 20A rotates, is pulverized and discharged to the outer peripheral side, and the material discharged to the outer peripheral side is It is well known that airflow is conveyed upward by the carrier airflow, classified by a classifier, the material having the required particle size is captured and conveyed to the subsequent stage, and the material having a larger particle size is returned to the inside of the mill again. is there.

The outer peripheral surface of the trapezoidal roller 10A is a grinding surface 11A. The crushing surface 11A is roughly divided into a main crushing surface 11A ′ on the large diameter side and a sub crushing surface 11A ″ other than that, and a plurality of screw grooves are formed on the entire crushing surface including the main crushing surface 11A ′. 12A is formed at equal intervals in the roller axis direction, and the inclination direction of the screw groove 12A is a raw material discharge direction in which the pulverized raw material is positively transferred to the outer peripheral side with rotation, and the inclination angle is The angle of inclination with respect to the roller axis is 67.5 degrees , and the angle of inclination with respect to the circumferential direction of the roller is 22.5 degrees The outer peripheral surface of the rotary shaft of the trapezoidal roller 10A is that of the lower rotary table 20A. Inclined to be parallel to the surface.

In the rotary table 20A combined with the trapezoidal roller 10A, an annular outer peripheral portion facing the trapezoidal roller 10A is a grinding surface 21A. Of grinding surface 21A, a main grinding surface 11A of the trapezoidal roller 10 'outermost peripheral portion that faces the main grinding surface 21A', an outer circumferential surface (grinding surface other than the main grinding surface 21A opposed to the secondary grinding surface 11A " ) Is the sub- grinding surface 21A ″. The sub- grind surface 21A ″ is provided with a slit groove 22A that is perpendicular to the table rotation direction or slightly inclined with respect to the perpendicular line, and the main grinding surface 21A ′ has neither the slit groove 22A nor the screw groove. It is a smooth surface.

By making the main pulverizing surface 21A ′ of the rotary table 20 a smooth surface, the effective pulverization area ratio on the main pulverizing surface 21A ′ is set to 100% while leaving the material transferability by the slit groove 222A, and the pulverization efficiency is drama. As described above, the improvement is achieved.

  Next, the type of grinding roller used in the vertical roller mill of the present invention will be described.

FIGS. 2A to 2C are pulverizing rollers suitable for pulverizing limestone. The grinding roller in FIG. 2A is the trapezoidal roller 10A shown in FIG. 1, and a plurality of screw grooves 12A are formed at equal intervals in the roller axial direction on the entire grinding surface 11A including the main grinding surface 11A ′. Has been. The inclination direction of the screw groove 12A is a raw material discharge direction in which the pulverized raw material is positively transferred to the outer peripheral side as it rotates and is sent to the main pulverized surface 11A ′. The inclination angle here is an inclination angle θ with respect to the roller shaft. 67.5 ° expressed, in the inclination angle with respect to the roller circumferential direction is 22.5 degrees.

The grinding roller shown in FIG. 2B is a flat roller 10B (D / R = 4) that is a tire-type roller and has a large curvature. In the tire flat type roller 10B, by reversing the roller 10B, both small diameter sides of the outer peripheral surface, that is, both side portions become the main grinding surfaces 11B ′ and 11B ′, and the central portion becomes the sub grinding surface 11B ″. in operation, the main grinding surface 11B of the table center side 'is the main grinding surface of the functional. both sides of the main grinding surface 11B', 11B 'and the entire central portion of the grinding surface 11B including the sub grinding surface 11B " A plurality of screw grooves 12B are formed at equal intervals in the roller axis direction. The inclination direction of the screw groove 12B is a raw material discharge direction in which the pulverized raw material is positively transferred to the outer peripheral side with rotation, and the inclination angle is 67.5 degrees expressed here as an inclination angle θ with respect to the roller shaft. The inclination angle with respect to the roller circumferential direction is 22.5 degrees .

The crushing roller shown in FIG. 2C is a convex roller 10C (D / R = 5) which is a tire type roller and has a small curvature. In the tire convex roller 10C, the large-diameter side of the outer peripheral surface, that is, the central portion is the main grinding surface 11C ′, and the small-diameter side ends on both sides are the sub- grinding surfaces 11C ″ and 11C ″. A plurality of screw grooves 12C are formed at equal intervals in the roller axis direction on the entire grinding surface 11C including the central main grinding surface 11C ′ and the auxiliary grinding surfaces 11C ″ and 11C ″ on both sides. The inclination direction of the screw groove 12C is a raw material discharge direction in which the pulverized raw material is positively transferred to the outer peripheral side with rotation, and the inclination angle is represented here as an inclination angle θ with respect to the roller shaft, 85 degrees , The inclination angle with respect to the direction is 15 degrees .

The main crushing surfaces 11A ', 11B', 11C 'are areas where wear of 2/3 or more of the maximum wear amount of the roller outer peripheral surface occurs, and the axial length of the main crushing surfaces 11A', 11B ', 11C' That is, the lateral width of the main grinding surfaces 11A, 11B ', 11C' is normally about 30 to 40% of the entire width of the roller, and is 1/3 here.

  The rotary table combined with these crushing rollers will be described below with reference to FIGS.

The turntable 20A shown in FIG. 3A is combined with the trapezoidal roller 10A shown in FIG. 2A, and corresponds to the turntable 20A shown in FIG. Of the surface of the rotary table 20A, an annular outer peripheral portion to which the trapezoidal roller 10A is opposed is a grinding surface 21A. Of grinding surface 21A, a main grinding surface 11A of the trapezoidal roller 10 'outermost peripheral portion that faces the main grinding surface 21A', an outer periphery of the other outer peripheral portions (the main grinding surface 21A opposed to the secondary grinding surface 11A " Surface) is the sub- grinding surface 21A ″. The sub- pulverized surface 21A ″ is provided with slit grooves 22A perpendicular to the table rotation direction, and the main pulverized surface 21A ′ is a smooth surface without the slit grooves 22A and screw grooves.

The lateral width (length in the table radial direction) of the main grinding surface 21A ′ is suitably 30 to 40% of the lateral width of the grinding surface 21A corresponding to the lateral width of the grinding surface 21A in the trapezoidal roller 10A. It is set to 3.

The cross-sectional shape of the slit groove 22A is one of the table grinding surface shapes suitable for limestone grinding presented by JP 2009-142809 A, as shown in FIG. Inclined groove shape of an acute edge inclined with respect to the table surface so that the angle (edge angle θ ′) of the slit edge located on the downstream side in the rotation direction of the turntable 20 is an acute angle, preferably less than 90 degrees and 45 degrees or more. Here, the inclined groove shape has a 60- degree acute edge with an edge angle θ ′ of 60 degrees .

The turntable 20B shown in FIG. 3B is combined with the tire flat roller 10B shown in FIG. Of the surface of the rotary table 20B, an annular outer peripheral portion to which the tire flat roller 10B faces is a grinding surface 21B. Of the pulverized surface 21B, the inner peripheral portion facing the functionally pulverized main pulverized surface 11B ′ of the tire flat roller 10B in the operation is the main pulverized surface 21B ′, and the central portion facing the auxiliary pulverized surface 11B ″ and the outer peripheral portion minute (grinding surface other than the main grinding surface 21B ') is a secondary grinding surface 21B ". The sub- pulverized surface 21B ″ is provided with slit grooves 22B perpendicular to the table rotation direction, and the main pulverized surface 21B ′ is a smooth surface without the slit grooves 22B and screw grooves.

The lateral width (length in the table radial direction) of the main grinding surface 21B ′ is suitably 30 to 40% of the lateral width of the grinding surface 21B corresponding to the lateral width of the grinding surface 21B in the flat tire roller 10B. / 3. The cross-sectional shape of the slit groove 22A is a concave groove shape perpendicular to the table surface.

The turntable 20C shown in FIG. 3C is combined with the tire convex roller 10C shown in FIG. Of the surface of the rotary table 20C, an annular outer peripheral portion to which the tire convex roller 10C faces is a grinding surface 21C. Of grinding surface 21C, the main grinding surface 11C of the tire convex roller 10C is 'central portion facing the main grinding surface 21C', secondary grinding surface 11C ", 11C" outer peripheral portion and inner peripheral portion partial facing the ( the main grinding surface 21C 'non-grinding face) is by-milled surface 21C ", 21C" is. The sub- grinding surfaces 21C ″ and 21C ″ are respectively provided with slit grooves 22C and 22C perpendicular to the table rotation direction, and the main pulverizing surface 21C ′ is a smooth surface having neither slit grooves 22C nor screw grooves. .

The lateral width (length in the table radial direction) of the main grinding surface 21C ′ is suitably 30 to 40% of the lateral width of the grinding surface 21C corresponding to the lateral width of the grinding surface 21C in the tire convex roller 10C. / 3. The cross-sectional shape of the slit groove 22C is a concave groove shape perpendicular to the table surface.

  4 (a) and 4 (b) are pulverizing rollers suitable for pulverizing coal.

The grinding roller shown in FIG. 4A is a flat roller 10B (D / R = 4) that is a tire-type roller and has a large curvature. In the tire flat type roller 10B, by reversing the roller 10B, both small diameter sides of the outer peripheral surface, that is, both side portions become the main grinding surfaces 11B ′ and 11B ′, and the central portion becomes the sub grinding surface 11B ″. in operation, the main grinding surface 11B of the table center side 'is the main grinding surface of the functional. both sides of the main grinding surface 11B', 11B 'and the entire central portion of the grinding surface 11B including the sub grinding surface 11B " A plurality of screw grooves 12B are formed at equal intervals in the roller axis direction. The inclination direction of the screw groove 13B is a raw material discharge direction for discharging the pulverized raw material to the outer peripheral side as it rotates, and the inclination angle is 45 degrees expressed here as an inclination angle θ with respect to the roller shaft, and is inclined with respect to the roller circumferential direction. The angle is also 45 degrees .

The grinding roller shown in FIG. 4B is a convex roller 10C (D / R = 5) which is a tire type roller and has a small curvature. In the tire convex roller 10C, the large-diameter side of the outer peripheral surface, that is, the central portion is the main grinding surface 11C ′, and the small-diameter side ends on both sides are the sub- grinding surfaces 11C ″ and 11C ″. A plurality of screw grooves 13C are formed at equal intervals in the roller axial direction on the entire grinding surface 11C including the central main grinding surface 11C 'and the auxiliary grinding surfaces 11C "and 11C" on both sides. The inclination direction of the screw groove 12C is a raw material scraping direction in which the pulverized raw material is returned to the inner peripheral side with rotation, and the inclination angle is 45 degrees , expressed here as an inclination angle θ with respect to the roller shaft, in the roller circumferential direction. The inclination angle with respect to the angle is 45 degrees .

The main pulverizing surfaces 11B 'and 11C' are areas where wear of 2/3 or more of the maximum wear amount on the outer peripheral surface of the roller occurs. The length of the main pulverizing surfaces 11B 'and 11C' in the axial direction of the roller, that is, the main pulverizing surface The width of 11B 'and 11C' is normally about 30 to 40% of the entire width of the roller, and is 1/3 here.

  The rotary table combined with these crushing rollers will be described below with reference to FIGS. 5 (a) and 5 (b).

The turntable 20B shown in FIG. 5 (a) is combined with the tire flat roller 10B shown in FIG. 4 (a). Of the surface of the rotary table 20B, an annular outer peripheral portion to which the tire flat roller 10B faces is a grinding surface 21B. Of grinding surface 21B, an inner peripheral portion partial facing the main grinding surface 11B on features in the operation of the tire flat roller 10B '(main grinding surface 110B of the inner circumferential side') is located in the main grinding surface 21B ' , secondary grinding surface 11B "central portion and peripheral portion partial facing the (grinding surface other than the main grinding surface 21B ') is by-milled surface 21B" is. Then, the sub grinding surface 21B ", and a screw groove 23B which is inclined in a direction back scraping material at 67.5 degree angle θ with respect to the table radius direction is provided, the main grinding surface 21B 'is also slit grooves screw It is a smooth surface in which no groove 23B exists.

The lateral width (length in the table radial direction) of the main grinding surface 21B 'is suitably 30 to 40% of the lateral width of the grinding surface 21B corresponding to each lateral width of the main grinding surfaces 11B' and 11B 'in the flat tire roller 10B. Here, it is set to 1/3. The cross-sectional shape of the screw groove 23B is a concave groove shape perpendicular to the table surface.

The turntable 20C shown in FIG. 5 (b) is combined with the tire convex roller 10C shown in FIG. 4 (b). Of the surface of the rotary table 20C, an annular outer peripheral portion to which the tire convex roller 10C faces is a grinding surface 21C. Of grinding surface 21C, the main grinding surface 11C of the tire convex roller 10C is 'central portion facing the main grinding surface 21C', secondary grinding surface 11C ", 11C" outer peripheral portion and inner peripheral portion partial facing the ( the main grinding surface 21C 'non-grinding face) is by-milled surface 21C ", 21C" is. Then, the sub-milled surface 21C ", 21C", the screw groove 23C inclined in a direction back scraping material at 67.5 degree angle θ with respect to the table radius direction, 23C are provided respectively, the main grinding surface 21C 'Is a smooth surface in which neither slit grooves nor screw grooves 23C exist.

The lateral width (length in the table radial direction) of the main grinding surface 21C ′ is suitably 30 to 40% of the lateral width of the grinding surface 21C corresponding to the lateral width of the grinding surface 21C in the tire convex roller 10C. / 3. The cross-sectional shape of the screw groove 23C is a concave groove shape perpendicular to the table surface.

〔Experimental device〕
In order to investigate the effectiveness of the present invention, a small pulverizer for experiments was prepared. As shown in FIG. 7, this crusher has a structure in which a crushing roller 2 faces the outer peripheral surface of a horizontal rotary table 1 that is a base member. Here, the crushing roller 2 is a trapezoidal roller, and is inclined so that the large diameter side is the outer peripheral side and the small diameter side is the central side, and the facing surface with the table 1 is horizontal. Replacement with a roller or a tire convex roller is also possible. The number of rollers was one because it was an experimental machine.

In the rotary table 1, the outer peripheral portion facing the crushing roller 2 is an annular crushing portion 3, and the annular crushing portion 3 is a tester, and thus can be attached to and detached from the table body 4. As the circular crushing section 3, various removable tables such as those with a smooth surface and slit grooves and screw grooves provided on the surface are prepared, and all rollers and tables are tested with one testing machine. Designed to be possible. Further details of the testing machine will be described later.

Incidentally, as a grinding unit 3 in cyclic 7, the outer peripheral portion is a smooth surface facing the main grinding surface of the trapezoidal roller, grinding unit 3 is shown provided with a slit groove 6 to the other surface.

The crushing roller 2 is attached to the support mechanism 5 so as to be rotatable and movable up and down so that the clearance with the crushing unit 3 can be adjusted arbitrarily. In order to apply a predetermined pressing force to the pulverized raw material, the pulverizing roller 2 is urged by a spring in a direction to be pressed against the pulverizing unit 3.

  As the rotary table 1 rotates, the rotary table 1 and the crushing roller 2 perform a relative turning motion. In this experiment, in order to confirm the pulverization performance of the roller itself, no classification device using air of the pulverized raw material is installed. Accordingly, the crushed raw material is discharged from the inside of the rotary table to the outside due to the discharge capability of the roller and the centrifugal force of the table rotation. Therefore, the collection container 8 that can completely collect the discharged raw material is provided outside the rotary table. Equipped.

[Crushing raw material]
When the pulverizing roller was actually used by dividing the pulverizing surface of the pulverizing roller into the main pulverizing surface and the raw material transfer surface, the pulverization amount of fine powder formed the conventional slit grooves and screw grooves over the entire pulverizing surface. It was clarified using a small crushing tester whether or not it increased compared with the case. As the pulverized raw materials used in the confirmation experiment, two types of coal were selected: 1) limestone having high adhesion and adhesion, and 2) coal having less adhesion and adhesion than limestone.

[Crushing experiment of limestone]
When pulverizing limestone, screw grooves were formed to prevent the limestone from adhering to the roller surface and transferring. For the screw groove, an intermediate range of 67.5 degrees and 85 degrees with the largest angle were selected from an angle range of 45 degrees to 85 degrees with respect to the roller axis. It has already been found that when slit grooves up to 45 degrees are used for limestone crushing, the slit grooves have excellent ability to scrape the raw material, resulting in adhesion and transfer of limestone on the roller surface, making the grinding operation difficult. Therefore, it was decided to form a screw groove having an angle of 45 degrees or more. In particular, the screw groove of 45 degrees or more reduces the performance of scraping the raw material, and is excellent in transportability for feeding the raw material. As the angle increases, the transportability is further improved, and the transfer and adhesion of limestone to the roller surface is improved. There is a property to reduce. In particular, 67.5 degrees with a large oblique gradient was assumed to be the most excellent inclination angle.

  The crushing rollers employed in the experiment are the trapezoidal roller shown in FIG. 2A, the flat tire roller (D / R = 4) shown in FIG. 2B, and the tire convexity shown in FIG. Three types of mold rollers (D / R = 5) were used.

An annular crushing portion to be combined with these was assumed to be a rotary table shown in FIGS. 3 (a), 3 (b), and 3 (c). Specifically, for the trapezoidal roller shown in FIG. 2 (a), the main grinding surface (outer peripheral portion) shown in FIG. 3 (a) is a smooth surface, and the secondary grinding surface (central portion and inner peripheral portion). ) Was combined with a pulverized portion with a 60 degree acute angle edge right angle slit. For comparison, a pulverized portion in which the entire pulverized surface is provided with a 60-degree acute-angle edge right angle slit was combined. In addition, a combination in which both the trapezoidal roller and the pulverized surface were smooth was also tested. Effectiveness of smoothing the main grinding surface of the rotary table by measuring the difference between the amount of fine powder of 200 mesh under and the amount of power consumption of this grinding tester for each combination and comparing the power intensity. Were compared for the case of using a trapezoidal roller.

Similarly, with respect to the tire flat roller shown in FIG. 2 (b) (D / R = 4), the main grinding surface shown in FIG. 3 (b) (inner peripheral portion) is a smooth surface, sub grinding surface A pulverized part in which (center part and outer peripheral part) are provided with a grooved right angle slit was combined. For comparison, a pulverized portion in which the entire pulverized surface is provided with a concave right angle slit was combined. In addition, a combination in which the flat surface of the tire flat roller and the pulverized portion were smooth was also tested. Effectiveness of smoothing the main grinding surface of the rotary table by measuring the difference between the amount of fine powder of 200 mesh under and the amount of power consumption of this grinding tester for each combination and comparing the power intensity. Were compared for the case of using a tire flat roller.

Further, with respect to the tire convex roller shown in FIG. 2 (c) (D / R = 5), the main grinding surface (middle portion) is a smooth surface as shown in FIG. 3 (c), sub-grinding surface (outer periphery The pulverized part in which the groove part and the inner peripheral part are provided with concave right angle slits were combined. For comparison, a pulverized portion in which the entire pulverized surface is provided with a concave right angle slit was combined. In addition, a combination in which the flat surface of the tire flat roller and the pulverized portion were smooth was also tested. Effectiveness of smoothing the main grinding surface of the rotary table by measuring the difference between the amount of fine powder of 200 mesh under and the amount of power consumption of this grinding tester for each combination and comparing the power intensity. Were compared for the case of using a tire convex roller.

  The dimensions of the trapezoidal roller, the tire flat roller, and the tire convex roller, the dimensions of the annular pulverized portion assuming the rotary table, and other pulverizing conditions are summarized below.

Grinding roller dimensions:
Trapezoidal roller Large diameter: 200mm, Small diameter: 170mm, Width 57mm
Tire flat roller (D / R = 4)
Large diameter: 200 mm, tire R: 50 mm, width 74 mm
Tire convex roller (D / R = 5)
Large diameter: 200 mm, tire R: 40 mm, width: 66 mm

Rotary table dimensions (grinding part dimensions):
For trapezoidal rollers Outer diameter: 410mm, Inner diameter: 280mm,
For tire flat type roller Outer diameter: 420 mm, inner diameter: 220 mm, groove R: 50 mm
For tire convex roller Outer diameter: 410mm, Inner diameter: 230mm, Groove R: 50mm

Peripheral speed: 30 RPM (left rotation)
Roller pressure: 23.5kg
Clearance between roller and table: 0mm
Test time: 30 minutes Limestone supply: +/- 1500 g / 30 minutes Limestone supply method: Continuous supply screw feeder system temperature, humidity: 12-18 ° C, 60-89%

Limestone used in the test Particle size: 1-3mm
Particle size distribution (measured value after drying for 30 minutes)
More than 10 mesh 46.0g
More than 16 mesh 44.0g
More than 30 mesh 9.0g
60 mesh or more Tr
P 0.5g

  In a grinding experiment assuming three types of vertical roller mills, the amount of limestone discharged to the outer periphery of the table, the remaining amount of limestone in the table, and the weight ratio of particles passing through 200 mesh and −235 mesh under the total grinding amount were investigated. In this experiment, for convenience, only one crushing roller is used for crushing. In the actual machine, 2 to 4 rollers are used, and a classification device for collecting fine powder is installed. Although the numerical value is different from the pulverization amount, since the same testing machine is used, the obtained tendency is highly reliable.

  In the particle size measurement, after the 30-minute grinding test was completed, the entire amount of limestone discharged from the table to the collector 8 was accurately collected, and the limestone remaining in the table was also collected in the same manner. After measuring the weight of each collected limestone, three samples were collected for particle size measurement from arbitrary locations of the collected limestone. In order to ensure accuracy, the average value of three data was adopted for the particle size measurement results.

  The power measuring instrument used for measuring the power consumption of the small crushing tester is “Clamp on Power HiTester 3168” manufactured by Hioki Electric Co., Ltd. The power consumption is an average value of numerical values measured in units of one second. In this experiment, an average value for 30 minutes was measured. This small experimental pulverizer has a three-phase 220V power consumption of 750 W / H. The reason for measuring the power consumption is as follows. Limestone was fed to the mill with a screw feeder, but often caused clogging, resulting in variable amounts for quantitative cutting. If there is a difference in the supply amount, it is impossible to obtain an accurate result by simply comparing the pulverized amount of 200 mesh under powder. Therefore, the amount of power consumed in each test pulverization was measured, and the fine powder of 200 mesh under obtained at that time The accuracy was maintained by comparing by the power unit divided by the amount of grinding.

The total pulverization amount for 200 mesh under is measured within 30 minutes of the pulverization test time, and the power consumption (Wh) required for the pulverization is measured. Using the numerical value divided by the unit of electric power, various combinations of roller and table grinding surfaces were obtained and compared.

[Comparative test results]
Table 1 shows the results when the pulverizing roller is a trapezoidal roller, that is, when the pulverizing roller is a combination of FIG. 2 (a) and FIG. 3 (a).

In the test (3) in which the main grinding surface of the rotary table is a smooth surface and the right grinding grooves are provided on the other grinding surfaces, that is, the secondary grinding surfaces, the 200 mesh under amount is a right-angle slit groove on the entire grinding surface of the rotary table. Compared with the test (2) provided with about 12.5%, it was improved about 14.3% when compared with the combination of the smooth surfaces of the test (1). The electric power consumption unit is a comparison with the total pulverization amount. In test (1), it is 0.075 Wh / g, in test (2) is 0.078 Wh / g, and in test (3) is 0.071 Wh / g. Test (3) showed a reduction of about 5.3% for test (1) and a reduction of about 9% for test (2).

  Table 2 shows the results when the crushing roller is a flat tire type roller, that is, when the crushing roller is a combination of FIG. 2B and FIG. 3B.

In the test (3) in which the main grinding surface of the rotary table is a smooth surface and the right grinding grooves are provided on the other grinding surfaces, that is, the secondary grinding surfaces, the 200 mesh under amount is a right-angle slit groove on the entire grinding surface of the rotary table. Compared with the test (2) provided with approximately 48%, the smooth surface was improved by approximately 42.4% when compared with the combination of the smooth surfaces of the test (1). The electric power consumption unit is a comparison with the total pulverization amount. In test (1), 0.073 Wh / g, test (2) is 0.068 Wh / g, and test (3) is 0.063 Wh / g. Test (3) showed a reduction effect of about 13.7% for test (1) and a reduction effect of about 7.4% for test (2).

  Table 3 shows the results when the crushing roller is a tire convex roller, that is, the combination of FIG. 2C and FIG. 3C.

In the test (3) in which the main grinding surface of the rotary table is a smooth surface and the right grinding grooves are provided on the other grinding surfaces, that is, the secondary grinding surfaces, the 200 mesh under amount is a right-angle slit groove on the entire grinding surface of the rotary table. Compared with the test (2) provided with about 46.5%, it was improved about 36% when compared with the combination of the smooth surfaces of the test (1). The electric power consumption unit is a comparison with the total pulverization amount. In test (1), 0.061 Wh / g, test (2) is 0.062 Wh / g, and test (3) is 0.064 Wh / g. Test (3) showed an increase of about 4.7% over test (1) and an increase of about 3.1% over test (2).

In the test with the vertical roller mill using the trapezoidal roller (1) and the test with the vertical roller mill using the flat tire roller (2), the power unit between the smooth surfaces is the highest, and the main surface of the rotary table grinding surface is the main. In the case of a combination of a roller and a table in which only the pulverized surface is a smooth surface, the basic unit of electric power is the smallest, resulting in a large difference. On the other hand, in the test (3) using the vertical roller mill using the tire convex roller, a slight reverse tendency was shown. This is because the former grinding is speaking face milling as either, the latter grinding, since a strong convex tendency of the curvature radius is small grinding surface of the grinding roller is close to the line grinding, impact grinding surface shape It is assumed that it was difficult to receive. However, the latter case is not a bad evaluation because it is considered that the power intensity has simply increased as the production of 200 mesh under increases.

[Coal crushing experiment]
There are two types of grinding rollers employed in the experiment: a tire flat roller (D / R = 4) shown in FIG. 4A and a tire convex roller (D / R = 5) shown in FIG. 4B. It was.

The annular crushing part combined with these assumed the rotary table shown to Fig.5 (a) (b). Specifically, for the tire flat roller (D / R = 4) shown in FIG. 4A, the main grinding surface (inner peripheral portion) shown in FIG. A pulverized portion having a pulverized surface (center portion and outer peripheral portion) with a 45-degree scraping screw groove was combined. For comparison, a pulverized portion in which the entire pulverized surface has a 45-degree scraping screw groove was combined. In addition, a combination in which the flat surface of the tire flat roller and the pulverized portion were smooth was also tested. Effectiveness of smoothing the main grinding surface of the rotary table by measuring the difference between the amount of fine powder of 200 mesh under and the amount of power consumption of this grinding tester for each combination and comparing the power intensity. Were compared for the case of using a tire flat roller.

For tire convex roller shown in FIG. 4 (b) (D / R = 5), the main grinding surface (middle portion) is a smooth surface as shown in FIG. 5 (b), sub-grinding face (the outer peripheral portion and The crushing part whose inner peripheral part) has a 45-degree discharge direction screw groove is combined. For comparison, a pulverizing part in which the entire pulverized surface has a 45-degree discharge direction screw groove was combined. In addition, a combination in which the flat surface of the tire flat roller and the pulverized portion were smooth was also tested. Effectiveness of smoothing the main grinding surface of the rotary table by measuring the difference between the amount of fine powder of 200 mesh under and the amount of power consumption of this grinding tester for each combination and comparing the power intensity. Were compared for the case of using a tire convex roller.

  The dimensions of the tire flat roller and the tire convex roller and the dimensions of the annular pulverized portion assuming the rotary table are as described above. Other grinding conditions are summarized below.

Coal used: Steel mill raw coal particle size range -G-: 7 mm x 7 mm ≥ G ≥ 0.5 mm x 0.5 mm
Initial particle size distribution:
20g or more 40g
More than 60 mesh 34g
120g or more 3g
13 mesh over 200 mesh
235 mesh or more 2g
P 9g
5% moisture
Roller clearance: 0mm
Roller surface pressure: 23.5Kg
Table rotation speed: 60 RPM
Coal supply amount: 2,530 to 2,850 g / 30 minutes Coal supply method: Screw feeder continuous supply system Test temperature and humidity: 18 to 34 ° C., 62 to 78%

[Comparative test results]
Table 4 shows the results when the grinding roller is a flat tire roller, that is, when the combination shown in FIGS. 4A and 5A is used.

In the test (3) in which the main pulverized surface of the rotary table is a smooth surface and the other pulverized surface, that is, the secondary pulverized surface is provided with a 45-degree scraping direction screw groove, the amount of 200 mesh under is the entire pulverized surface of the rotary table. Compared with the test (2) in which the screw groove was provided on the surface, it was improved by about 41%, and when compared with the combination of the smooth surfaces in the test (1), it was improved by about 18.4%. The reason for the smaller amount of fine grinding in Test (2) compared to Test (1) is that the main grinding surface of the roller is on the small diameter side of the roller. As a result, the effective grinding area is originally small and 45 degrees in the scraping direction. since the screw groove is formed to the main grinding surface, the main grinding surface that performs pulverization actually at the same time effective grinding surface necessary for grinding coal is very low, the coal is returned scraped into the center of the table side This is because the work of grinding is further reduced. In comparison, the smooth surface roller had a larger effective pulverization area and a larger amount of fine powder than the test (2).

  The electric power consumption with respect to the total pulverization amount decreased about 12% in the test (3) compared to the test (1), but increased about 1.7% compared to the test (2). However, the amount of pulverization in Test (3) is 41% higher than the amount of pulverization in Test (2). Considering the amount of work, the power consumption in Test (3) is very high. Excellent numerical value. Since test (2) originally has a small amount of pulverization work, it is natural that the power consumption is also reduced proportionally.

  Table 5 shows the results when the grinding roller is a tire convex roller, that is, when the grinding roller is a combination of FIG. 4B and FIG. 5B.

In the test (3) in which the main pulverization surface of the rotary table is a smooth surface and the other pulverization surface, that is, the secondary pulverization surface is provided with a 45-degree screw groove in the discharge direction, the amount of 200 mesh under is the entire pulverization surface of the rotary table. Compared with the test (2) provided with a 45-degree screw groove in the discharge direction, the improvement was about 7.7%, and when compared with the combination of smooth surfaces in the test (1), the improvement was about 20.4%. The power unit for the total amount of grinding was reduced by about 6.3% in the test (3) compared to the test (1), but increased by about 3.4% compared to the test (2). This is because the amount of grinding work in 3) increased by about 7.7% compared to test (2). Considering the increase, test (3) is about power consumption compared to test (2). Is also an advantage.

Thus, the rotary table grinding surface divided into a main grinding surface and the other sub-grinding surface, the slit groove and the screw groove is provided only in the secondary grinding surface, when the main grinding surface is a smooth surface, the main grinding surface The secondary pulverization surface having an effective pulverization area of 100% and not contributing significantly to other pulverization works as a transfer action surface of the pulverized raw material, resulting in an increase in pulverization efficiency.

10A trapezoidal roller 11A grinding surface 11A ′ main grinding surface 11A ″ sub grinding surface 12A slit groove 10B tire flat roller 11B grinding surface 11B ′ main grinding surface 11B ″ sub grinding surface 12B slit groove 10C tire convex roller 11C grinding surface 11C 'Main grinding surface 11C "Sub grinding surface 12C Slit groove 20A, 20B, 20C Rotary table 21A, 21B, 21C Grinding surface 21A', 21B ', 21C' Main grinding surface 21A", 21B ", 21C" Sub grinding surface 22A, 22B, 22C Slit groove 22B, 22C Screw groove

Claims (5)

In a vertical roller mill consisting of a combination of a rotary table rotating in the circumferential direction and a plurality of vertical grinding rollers arranged at fixed positions on the table at intervals in the rotational table rotation traveling direction,
The rotary table facing the main grinding surface of the grinding roller among the grinding surfaces of the rotary table, the roller grinding surface comprising a main grinding surface that mainly performs fine grinding and a grinding surface other than the main grinding surface, and facing the outer peripheral surface of the grinding roller The main grinding surface on the side is a smooth surface that is 30 to 40% of the rotary table grinding surface expressed by the radial length of the rotary table, and the table rotation progresses on the rotary table grinding surface other than the main grinding surface. A hybrid grinding surface structure in which slit grooves that are inclined at right angles to the direction or at angles greater than 45 degrees and less than 90 degrees, or screw grooves that are inclined at an angle of 5 degrees to 45 degrees with respect to the direction of table rotation are formed. On the rotary table side,
The pulverization roller is a trapezoidal roller, and the entire pulverization surface including the main pulverization surface on the large diameter side is a raw material transfer surface on which screw grooves are formed in a discharge promoting direction for forcibly conveying the pulverized raw material from the inside to the outside. Vertical roller mill. In a vertical roller mill consisting of a combination of a rotary table rotating in the circumferential direction and a plurality of vertical grinding rollers arranged at fixed positions on the table at intervals in the rotational table rotation traveling direction,
The rotary table facing the main grinding surface of the grinding roller among the grinding surfaces of the rotary table, the roller grinding surface comprising a main grinding surface that mainly performs fine grinding and a grinding surface other than the main grinding surface, and facing the outer peripheral surface of the grinding roller The main grinding surface on the side is a smooth surface that is 30 to 40% of the rotary table grinding surface expressed by the radial length of the rotary table, and the table rotation progresses on the rotary table grinding surface other than the main grinding surface. A hybrid grinding surface structure in which slit grooves that are inclined at right angles to the direction or at angles greater than 45 degrees and less than 90 degrees, or screw grooves that are inclined at an angle of 5 degrees to 45 degrees with respect to the direction of table rotation are formed. On the rotary table side,
The crushing roller is a tire convex roller, and the entire crushing surface including the main crushing surface on the large diameter side is a raw material transfer surface in which screw grooves in the discharge promotion direction for forcibly conveying the crushing raw material from the inside to the outside are formed. A vertical roller mill. In a vertical roller mill consisting of a combination of a rotary table rotating in the circumferential direction and a plurality of vertical grinding rollers arranged at fixed positions on the table at intervals in the rotational table rotation traveling direction,
The rotary table facing the main grinding surface of the grinding roller among the grinding surfaces of the rotary table, the roller grinding surface comprising a main grinding surface that mainly performs fine grinding and a grinding surface other than the main grinding surface, and facing the outer peripheral surface of the grinding roller The main grinding surface on the side is a smooth surface that is 30 to 40% of the rotary table grinding surface expressed by the radial length of the rotary table, and the table rotation progresses on the rotary table grinding surface other than the main grinding surface. A hybrid grinding surface structure in which slit grooves that are inclined at right angles to the direction or at angles greater than 45 degrees and less than 90 degrees, or screw grooves that are inclined at an angle of 5 degrees to 45 degrees with respect to the direction of table rotation are formed. On the rotary table side,
The crushing roller is a flat tire type roller, and the whole crushing surface including the main crushing surfaces on both sides located at the small-diameter portions on both sides in accordance with the change in the mounting direction of the roller reversely feeds the crushing raw material from the outside to the inside. A vertical roller mill which is a raw material transfer surface on which screw grooves in the scraping direction are formed. In a vertical roller mill consisting of a combination of a rotary table rotating in the circumferential direction and a plurality of vertical grinding rollers arranged at fixed positions on the table at intervals in the rotational table rotation traveling direction,
The rotary table facing the main grinding surface of the grinding roller among the grinding surfaces of the rotary table, the roller grinding surface comprising a main grinding surface that mainly performs fine grinding and a grinding surface other than the main grinding surface, and facing the outer peripheral surface of the grinding roller The main grinding surface on the side is a smooth surface that is 30 to 40% of the rotary table grinding surface expressed by the radial length of the rotary table, and the table rotation progresses on the rotary table grinding surface other than the main grinding surface. A hybrid grinding surface structure in which slit grooves that are inclined at right angles to the direction or at angles greater than 45 degrees and less than 90 degrees, or screw grooves that are inclined at an angle of 5 degrees to 45 degrees with respect to the direction of table rotation are formed. a rotary table side,
The crushing roller is a flat tire type roller, and the entire crushing surface including the main crushing surfaces on both sides located at the small-diameter portions on both sides is forcibly conveyed from the inside to the outside as the mounting direction of the roller is changed. A vertical roller mill which is a raw material transfer surface on which screw grooves in the discharge promotion direction are formed.   The vertical roller mill according to any one of claims 1 to 4, wherein a main pulverizing surface of the pulverizing roller is a region of the outer peripheral surface of the roller that is an area exhibiting 2/3 or more of the maximum wear amount.

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