JPH08281135A - Roller mill - Google Patents

Abstract

PURPOSE: To control the self-excited vibration of a roller mill. CONSTITUTION: This roller mill is so designed as to finely crush a raw material to be crushed by the interlocked action between a circular rotating table 203 which is driven to rotate by an electric motor and a plurality of crushing rollers 201 which rotate in such a state that the rollers 201 are pressed against a groove part notched on the outer periphery of the rotating table 203. In addition, the rotating center shaft 207 of each of the crushing rollers 201 is tilted to the normal 209 of the rotating table 203.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller mill for finely pulverizing a solid fuel such as coal or a solid raw material such as limestone, and mainly suppresses the occurrence of self-excited vibration to achieve wide-range load / multi-coal operation. The present invention relates to a roller mill that can be used.

[0002]

2. Description of the Related Art Pulverized coal burning boilers for thermal power generation and general industries are subjected to low-pollution combustion (low NOx, reduction of unburned ash content) and wide-area load operation, which is accompanied by pulverized coal machines (mills).
High performance is also required.

As one type of mill for finely crushing agglomerates such as coal, cement raw material or new raw material, a vertical roller mill for finely pulverizing by the interlocking action of a rotating table and a plurality of tire rollers is widely used. It has come to be used and is commonly used in large-scale new thermal power plants.

This type of mill has a substantially circular disk type rotary table which is located at the bottom of a vertical cylindrical housing (casing), is driven by an electric motor, and rotates at a low speed through a speed reducer, and the rotary table. A plurality of tire-shaped crushing rollers that rotate by being pressed by a hydraulic pressure or a spring or the like are provided at positions equally divided in the circumferential direction on the upper surface of the outer peripheral portion.

The pulverized raw material supplied from the raw material supply pipe (chute) to the center of the rotary table moves to the outer periphery of the table due to centrifugal force on the rotating table, and is caught between the pulverizing race surface of the table and the pulverizing rollers. Then, it is compressed and crushed by a crushing roller.

At the lower part of the mill housing, hot air of 200 to 300 ° C. is introduced through a duct, and this hot air passes through an air throat between the table and the housing,
It is being blown up to the crushing section in the mill.

The crushed powder is dried in the process of rising in the housing by the hot air blown from the air throat. Coarse particles out of the powder particles transported to the upper part of the housing fall due to gravity (primary classification), and are crushed again by a crushing roller in a crushing unit. The slightly fine particles that have passed through the primary classifying section and transported further upward are again subjected to centrifugal classification by a cyclone separator (fixed type) or a rotary separator (rotary classifier) provided on the upper part of the housing ( Secondary classification). Fine powder having a particle size smaller than a predetermined particle size is conveyed by an air flow and is sent to a pulverized coal burner in a boiler or a fine powder storage bin for blast furnace injection in a steel process.

The coarse powder having a predetermined particle size or more that has not passed through the classifier eventually falls onto the rotary table due to gravity, and is crushed again together with the raw material just fed into the mill or the coarse particles after the primary classification. To be done. By the above operation, the pulverization is repeated in the mill, and fine powder satisfying a predetermined particle size is generated.

[0009]

When the roller mill is operated under a low load or is stopped, the problem is the vibration of the mill. This vibration phenomenon is a kind of frictional vibration caused by the slip between the coal bed and the roller, and is a kind of self-excited vibration as the type of vibration. As shown in FIG. 14, with ordinary coal, this vibration often becomes severe during low-load operation (conditions where there is little coal hold-up in the mill), but depending on the type of coal, it also occurs at considerably high load. Sometimes.

FIG. 12 is a sectional view showing a supporting structure of a crushing roller in a conventional roller mill, a sectional view taken along the line AA of FIG. 13, and FIG. 13 is a plan view taken along the line BB of FIG. Is.

In this type of roller mill, a crushing roller 1201 is swingably supported by a roller pivot 1206 via a roller bracket 1204 as a spindle. This swinging function is very important, and when the crushing roller 1201 bites in a foreign substance such as an iron piece that is difficult to be crushed, the crushing roller 1201 can avoid an impact by shaking its head. Further, when the crushing roller 1201 and the crushing race 1211 are worn and deformed, this swinging function also has an action of automatically finding an appropriate pressing position (positional relationship between the crushing roller 1201 and the crushing race 1211). In the figure, 1202 is a roller shaft, 1203 is a roller rotating shaft, 1205 is a pivot block, 1207 is a pressure frame, 1208 is a crushing load,
1209 is a rotary table, 1210 is a table ring,
1212 is a compressed powder layer, 1213 is a table rotating shaft, 12
Reference numeral 14 is a raw material powder layer, and 1215 is a pivot axis. FIG.
In 3, the indication of the raw material powder layer is omitted.

Generally, at the time of high load crushing, the crushing roller 1
201 has almost no pendulum movement. As described above, when the crushing roller 1201 actively engages the raw material when the mill is started or when the load is increased, the crushing roller 1201 shakes its head, but this pendulum operation is directly linked to the occurrence of self-excited vibration. do not do.

On the other hand, when the crushing roller 1201 vibrates violently under self-excitation, as shown in FIG.
All three 01 are laterally displaced outward at substantially the same time (β), and then vibrate vertically as shown in FIG. 16 (γ). The three crushing rollers 1501 vertically vibrate together synchronously (in phase). When one crushing roller 1501 causes a laterally-displaced swinging motion (β) and vertical vibration (γ) of the crushing roller 1501 occurs, this movement causes the three crushing rollers 1501 to move.
1 is a pressurizing frame for supporting 1 from above (FIG. 12).
Of the pressurizing frame 1207) or the table and the powder layer on the table, and instantly propagates to other crushing rollers. This is the self-excited vibration of the crushing roller.

Incidentally, in FIG. 15 and FIG.
Is a roller pivot, 1503 is a rotary table, 1504
Is a crushing ring, 1505 is a crushing race, 1506 is a table rotary shaft, 1507 is a raw powder layer, 1508 is a compressed powder layer, 1509 is a roller rotary shaft, 1510 is a vertical shaft, 15
Reference numeral 11 is a central axis of the cross section.

As shown in FIG. 13, in the conventional roller supporting method, in the roller pivot 1206, which is a supporting point for transmitting the crushing load to the roller bracket 1204, the pivot shaft core 1215 connecting the pair thereof has the roller rotating shaft 120.
It was configured to be at a right angle (90 °) with respect to 3. According to this structure, a pendulum-like lateral displacement operation of the crushing roller that triggers the occurrence of self-excited vibration [(β) in FIG. 15]
Is likely to occur.

From the above, in order to suppress the vibration of the mill by devising the hardware of the crushing section, the three crushing rollers move in synchronism, that is, the pendulum shape of the crushing roller which is the trigger of this behavior. It turns out that it is important not to cause movement.

Based on the above idea, an object of the present invention is to provide a roller mill which can prevent lateral pendulum motion of a crushing roller and enable operation over a wide range of loads or various raw materials without causing vibration. It is in.

[0018]

In order to solve the above problems, the present invention employs the following means.

In the roller bracket having a structure in which the shaft of the crushing roller is supported from the rear of the crushing roller, it is provided symmetrically with respect to the axis of the roller and serves as a load transmitting point and at the same time a pendulum operation supporting shaft of the crushing roller. Change the installation configuration of the roller pivot as follows.

A pair of roller pivots is installed so that the rotary shaft center of the crushing roller is inclined with respect to the normal line of the rotary table so that the tip of the crushing roller in the rotational direction faces the inner side, that is, the central axis side of the rotary table.

Moreover, this angle θt is set within the range of 0.6 ° ≦ θt ≦ 2.4 ° (1), more preferably, 1.2 ° ≦ θt ≦ 1.8 (2).

The pair of roller pivots are arranged on one straight line perpendicular to the rotation axis of the crushing roller and symmetrically with respect to the rotation axis. The roller pivot is a simple cylindrical body or a shape similar to this, but specifically, a member called a pivot block into which this roller pivot is inserted has a roller bracket of the roller bracket so as to have the structure as described above. Place on top and bottom of pressure frame.

[0023]

By tilting the tip of the crushing roller in the direction of rotation inward by the means as described above, the lateral pendulum motion (see FIG. 15) of the crushing roller, which triggers the occurrence of self-excited vibration, is suppressed. Excited vibration is less likely to occur.

Further, since the inclination angle of the crushing roller is set in the optimum range, the raw material is satisfactorily caught at the tip of the crushing roller in the rotating direction, and an excessive load is not applied to the rotation of the crushing roller. Power does not rise, either. In other words, crushing capacity (fine powder generation performance) is secured,
The reduction of the pulverization efficiency (the ratio between the fine powder generation capacity and the pulverization power) is not brought about.

For example, if the inclination angle θt is (1),
If it is smaller than the range expressed by the formula (2), the vibration suppressing effect is poor.

On the other hand, if the inclination angle θt is made too large compared to the conditions expressed by the equations (1) and (2), the space between the crushing roller and the crushing race in the biting portion is reduced, and the crushing roller The biting performance decreases. Also, θ
If t is too large, when the wheel is idling (the crushing roller and the crushing race touch the metal), the crushing roller slides down when it rides on the side of the crushing race, and the shocking fall to the center of the crushing race occurs. Appears occasionally.

In this case, a collision noise is generated in accordance with the vibration of the crushing roller, and an impact force is exerted on the peripheral equipment, which is a problem. Furthermore, the crushing roller and crushing race are inside (rotating table side) even under steady and stable crushing conditions.
There is a possibility that uneven wear may occur due to the contact at.

Therefore, if the inclination angle θt is optimized,
The above problems are not likely to occur, and suppression of self-excited vibration is achieved in a state where the crushing capacity and the crushing efficiency are sufficiently secured.

Since the method according to the present invention does not newly install a special member, it is highly reliable and does not impair the structural integrity of the mill. Furthermore, since no external power is used, it can be said to be advantageous in terms of operating costs. Further, since the structure is simple, that is, only the installation position of the pivot block is changed, the manufacturing cost can be kept low. Since the inclination angle θt is appropriate, members such as the cylindrical roller pivot and the pivot block into which the cylindrical pivot is inserted do not suffer from damage such as uneven wear and cracks (cracks) accompanied by extreme deformation.

[0030]

FIG. 1 is a vertical cross-sectional view of a structure of a roller mill embodying a roller rotation supporting structure according to an embodiment of the present invention, which passes through the central axis of the entire mill.

The crushing section of this roller mill is roughly composed of the crushing roller 4 and the rotary table 3 which are the main elements. Among these main elements, the feature of the present invention lies in the rotation supporting structure of the crushing roller 4, so that this will be described first.

FIG. 2 is a view from above the crushing section,
It shows the support structure of the crushing roller.

The crushing roller 201 is the roller bracket 2
It is supported by a pressure frame 206 via roller pivots 204 provided symmetrically on both shoulders above 02.

A crushing load by hydraulic pressure (crushing load 11 in FIG. 1) is applied to the pressure frame 206, and the roller pivot 204 serves as a transmission point of the crushing load. The roller pivot 204 also serves as a support shaft when the crushing roller 201 makes a pendulum motion, and plays a very important role.

In the prior art, this roller pivot 204
Is a straight line 21 perpendicular to the normal 209 of the rotary table
It was installed so that it would be on top of 0. In the present invention, the pivot shaft core 208 connecting both roller pivots 204 is tilted by an angle θt with respect to the conventional shaft core 210.
The inclination direction is the tip 20 of the crushing roller 201 in the rotation direction.
1 ′ is the inside, that is, the rotation center 2 of the rotary table 203
Turn to face 11.

As described above, when the crushing roller 201 is supported, the rotary shaft 207 of the crushing roller 201 is also inclined by the angle θt with respect to the normal line 209 of the rotary table 203. The roller pivots 204 are inserted into the pivot blocks 205, and are arranged symmetrically on one pivot shaft 208, which is a straight line, with the roller rotation shaft 207 interposed therebetween.

The principle of the present invention will be described with reference to FIG. 3 which shows the movement of the roller which is the starting point of the invention in which the method of inclining the rotary shaft of the crushing roller as in the present invention is invented.

Pressure frame (pressure frame 10 of FIG. 1,
The pressure frame 206) of FIG.
It is assumed that the contact point between 2 and the grinding roller 301 changes from 0 to 0 '. 0'is the rotary table 310 and the crushing roller 3
It corresponds to the “upstream side” for the rotation of 01.

Such a movement actually occurs in the roller mill, which is a trigger for the self-excited vibration (see FIG. 15).

Now, at the moment when the contact point 0 shifts with respect to the rotation direction of the table, or as shown in FIG. A velocity component as shown by is generated.

When the velocity component 304 in the lateral slip direction and the component 305 in the rolling direction are combined, the outside (rotating table 3
A velocity vector 306 that the crushing roller 301 receives from the rotary table 310 so as to face the outside of 10, ie, the mill housing side) is generated.

This combined velocity vector 306 is inclined by the angle θt with respect to the component 305 in the rolling direction.

Since the component of this composite velocity vector 306 acts so as to cause self-excited vibration, the angle θ that points outward
It is the essence of the present invention that it is directed inward in advance in order to cancel only t.

In FIG. 3, the position of the crushing roller 301 is such that the front end 301 'in the rotating direction faces the outside (mill housing side) by the angle -θt. Therefore, the crushing roller 301 is prevented from coming to such a position.
In the roller supporting method shown in FIG. 2, the contact point 0 between the crushing race 302 and the crushing race 302 is previously displaced in the direction opposite to 0 '.

In the figure, reference numeral 303 is a contact point, 307 is a roller rotating shaft, and 308 is a table rotating shaft.

As shown in FIG. 4, when the tip end 401 'of the crushing roller 401 in the rotation direction is tilted inward (in the direction of the table rotation shaft 405), the space for the raw material biting portion 404 becomes narrow. Therefore, unless the inclination angle is set to an appropriate condition, the crushing performance is also affected.

On the other hand, since the crushing roller 401 rotates while being inclined with respect to the rotary table 402 which is the drive source, the rotational load may increase. Therefore, it is important to optimize the inclination angle θt, and this setting method is the point of the present invention. In the present invention, this inclination angle θt is set to 0.6 ° ≦ θt ≦ 2.4 ° (1) ′ [(1)
Same as the formula]. More preferably, 1.2 ° ≦ θt ≦ 1.8 (2) ′ [(2)
The same as the formula] can be selected.

This optimization condition was confirmed by experiments as will be described later. If the formula (1) 'or the formula (2)' is satisfied, the pulverization power is not increased and the fine powder particle size is not reduced. Self-excited vibration can be suppressed while ensuring a constant efficiency.

Although the order is reversed, the entire construction of the roller mill adopting the roller rotation support according to the embodiment of the present invention will be described with reference to FIG.

The raw material 1 is supplied from a raw material supply pipe (center chute) 2 located on the central axis of the upper part of the mill, and drops onto a rotary table 3 rotating at the lower part of the mill. Centrifugal force acts on the raw material on the rotary table 3 and the raw material is supplied onto the crushing ring 12 on the outer periphery of the rotary table 3 to generate the crushing ring 1.
On the crushing race 13 which is engraved on the upper surface of 2 and has a substantially arc-shaped cross section, it is compressed and crushed by the crushing roller 4.

As described above, in the roller mill of this embodiment, the tip of the crushing roller 4 in the rotational direction is inclined inward (toward the central axis of the rotary table 3) by a proper angle θt.

The powder produced by crushing in this crushing unit penetrates between the throat vanes 17, is dried by the hot air 16 blown into the mill, and is transported above the mill.

The coarse particles fall on the rotary table 3 due to gravity (primary classification), and are crushed again in the crushing section. The particles passing through the primary classifying section are centrifugally classified by the rotary classifier 19 (secondary classification). The relatively coarse particles pass between the blades of the rotary classifier 19 and are discharged from the fine powder duct 22 as product fine powder. In the case of coal, it is sent directly to the pulverized coal burner (the hot air 16 becomes the primary air for combustion) or is collected in a storage bin.

In the figure, 5 is a roller bracket, 6 is a roller shaft, 7 is a roller rotating shaft, 8 is a pivot box,
Reference numeral 9 is a roller pivot, 11 is a crushing load, 14 is a raw material powder layer, 15 is a compressed powder layer, 18 is a table rotating shaft, 20 is a mill housing, 21 is a dam ring, and 23 is product fine powder.

Here, the process of finding the proper inclination angle θt of the crushing roller in the present invention will be described based on the experimental results.

FIG. 5 is a characteristic diagram showing test results using a batch (batch) type crushing section model device.

This characteristic diagram summarizes the change in the vibration amplitude δ _oc with respect to the crushing load M. The crushing load M on the horizontal axis was made dimensionless by using the load M (*) under the rated crushing conditions. Also, the amplitude δ _{oc on the} vertical axis was made dimensionless by dividing it by the amplitude δ _oc (*) of the conventional technique [when the inclination angle θt = 0 and the load was M = M (*)].

As shown in the figure, when no countermeasure is taken (roller inclination angle θt = 0 °), the amplitude sharply increases with the load. When the inclination angle θt = 0.8 °, the amplitude decreases when compared with the same load M, but the effect is not always sufficient. When the inclination angle θt = 1.5 °, 0 ≦
Although the amplitude gradually increases in the region of M / M (*) ≦ 1.0, it is suppressed to a considerably low level at the amplitude level. 1.0
In the range of ≦ M / M (*) ≦ 1.5, the characteristic that the amplitude is lowered also appears. The amplitude characteristic of the tilt angle θt = 1.5 ° is substantially the same as that of the tilt angle θt = 3.0. From the above results, it can be summarized as follows.

(1) By setting the roller inclination angle θt = 1.5 °, it is possible to sufficiently reduce the amplitude.

(2) Even if the inclination angle θt = 3.0 °,
The vibration level is the same as when the tilt angle θt = 1.5 °, and the tilt angle θt = 1.5 ° is appropriate considering the increase in the rotation resistance by increasing the tilt angle θt.

FIG. 6 also shows the results of basic experiments using a batch-type crushing unit model device, which summarizes changes in the crushing torque T with respect to the crushing load M. Grinding torque T on the vertical axis
Is M = M in the conventional technology (tilt angle θt = 0 °).
The crushing torque T (*) in the case of (*) is used to make it dimensionless.

The crushing torque T increases substantially linearly with the load, but the crushing torque T at the inclination angles θt = 0.8 ° and 1.5 ° is the same as that when the inclination angle θt = 0 ° which is the conventional method. It is almost equivalent. On the other hand, the tilt angle θt = 3.0
If the angle is °, the torque T also increases linearly with the load M, but the slope [T / T (*)] /
[M / M (*)] is larger than the other conditions. In other words, when the inclination angle θt = 3.0 °, an excessive rotational load will occur. To summarize the above, (1) The rotational load does not increase at least when the inclination angle θt is up to 1.5 °.

(2) If the tilt angle θt is 3.0 °, the rotational load increases, so it cannot be said that the tilt angle is appropriate.

Such characteristics may be eliminated by changing the size of the crushing roller (for example, thinning),
Since the pulverizing ability is reduced due to this, it can be said that the characteristics of the inclination angle θt described above are generally appropriate for a mill having a predetermined pulverizing ability.

FIG. 7 is a characteristic diagram summarizing the results of basic experiments for investigating the ability to generate fine powder.

By the batch type pulverization method, the increase characteristic of the grain size with respect to the cumulative rotation number r of the rotary table was obtained, and the influence of the inclination angle θt was compared. Cumulative rotation speed r is the reference condition r
(*) Represents dimensionlessly. Also, the grain size q on the vertical axis
Is also expressed as a relative value q / q (*) by the particle size q (*) obtained when r = r (*) under the condition of the inclination angle θt = 0 °.

In general, the grain size becomes finer as the rotation speed r increases. Within the range of the inclination angle θt according to the present invention described above, the particle sizes are the same within the range of the substantial variation. On the other hand, when the tilt angle θt is made larger than the region specified in the present invention, the grain size q / q (*) is generally coarse. Therefore, if the inclination angle θt is excessively large, the fine powder generation capability obviously decreases. From the above, if the inclination angle θt is too large, the crushing torque T increases and the fine powder particle size also decreases, so the crushing efficiency also decreases.

The reason for this is the following two points.

(A) Increase in rotational load by increasing the tilt angle θt.

(B) As shown in FIG. 4, the space for the biting portion of the crushing roller is reduced, and the ability to bite the raw material is reduced.

FIG. 8 is a characteristic diagram showing test results using a pilot scale roller mill.

The change in the amplitude δ _oc during coal crushing depending on the inclination angle θt of the crushing roller is shown. Amplitude δ on the vertical axis
_oc was expressed as dimensionless by using the amplitude δ _oc (*) at the time of crushing at the inclination angle θt = 0 ° (prior art). Amplitude δ
_oc sharply decreases as the tilt angle θt increases, and it decreases by 1 °.
It becomes the lowest in the range of <θt <2 °, but the inclination angle θt
The amplitude δ _oc tends to increase again as is increased.

From the above, it can be seen that the amplitude can be sufficiently reduced within the proper range of the tilt angle θt according to the present invention [Equations (1) and (2)].

FIG. 9 is a characteristic diagram showing the results of a test using a pilot scale roller mill as in FIG.
We are paying attention to the vibration when the crushing roller and crushing race are in a metal touch state during idle rotation. The amplitude δ _oc (m−t) is summarized as a change with respect to the inclination angle θt of the crushing roller. θ _oc (m−t) is the tilt angle θt = 0 °
It is expressed as dimensionless by dividing by the amplitude δ _oc (m−t) in (prior art). In the figure, q is a fine powder particle size, q (*) is a reference fine powder particle size, m is a power consumption unit, and m (*) is a reference power consumption unit. If the tilt angle θt is at least less than 2 °, no increase in θ _oc (m−t) is seen and there is no particular problem.

However, if the tilt angle θt> 2.4 °, θ _oc (m−t) rapidly increases. Although this violent vibration does not occur reproducibly, it is vibration due to the stabilization of the contact position between the crushing roller and the crushing race as described above, and when it occurs, a considerably large impact occurs. Therefore, the inclination angle θt of the crushing roller is 2.4.
It turns out that it must be below °.

FIG. 10 shows the test results of continuous crushing of coal with various amounts of coal feeding in a pilot scale roller mill, which shows the particle size of pulverized coal and the power unit (a value obtained by dividing the crushing power by the crushing amount). It shows a relationship.

The power unit m (*) on the vertical axis is made dimensionless by using the reference power unit when the inclination angle θt = 0 ° at the rated coal feed rate. A larger m value means that the pulverization power required to pulverize a certain amount of coal is high, and the pulverization efficiency is low. The pulverized coal particle size q on the horizontal axis was expressed as a relative value by dividing by the particle size q (*) under the standard conditions (tilt angle θt = 0 °, rated coal feed rate).

Comparing with the same grain size, the inclination angle θ with respect to the power unit m value at the inclination angle θt according to the present invention is compared.
It can be seen that if t is too large, the m value increases. From this result, it can be said that it is proved that if the set amount of the inclination angle θt is adopted as in the present invention, the crushing capacity hardly changes.

Therefore, it was confirmed that by carrying out the present invention, the reduction of self-excited vibration is achieved while the crushing ability is kept constant.

FIG. 11 summarizes changes in the amplitude of vibration with respect to coal hold-up in the mill and compares the embodiment of the present invention with the prior art.

The amplitude δ _{oc on the} vertical axis is made dimensionless by dividing by the amplitude δ _oc (*) when the crushing roller and the crushing race make a metal touch when rotating idle. On the other hand, the holdup W on the horizontal axis is made dimensionless by dividing by the holdup W (*) when the mill is operated at the rated coal feed rate.

The results of this experiment were obtained when pulverizing coal, which is apt to cause a relatively violent vibration due to the influence of coal quality. In the conventional technology (FIG. 13), the low load range (W
/W(*)≦0.38), the amplitude significantly increases, whereas it was demonstrated that the roller mill equipped with the rotary table having the shape embodying the present invention can significantly reduce the amplitude. . Even in the case of the embodiment of the present invention, the amplitude becomes slightly larger in the vicinity of W / W (*) ≦ 0.38 than other hold-up conditions, but this vibration is not self-amplifying self-excited vibration. , One type of forced vibration.

The roller mill that embodies the roller rotation support structure according to the present invention is not limited to the roller mill for coal-fired boilers described in the embodiments, but the same solid fuel mill for oil coke and finely crushed limestone for desulfurization. Mill for milling milling hard slag such as steel slag and non-ferrous refining slag Mill for milling cement clinker Cement finishing mill Mill for milling raw materials of various chemical products Industry of FRP (fiber reinforced plastic) waste materials, etc. It can be applied as a self-excited vibration suppression technology in a mill of fine pulverization for reuse of waste.

[0084]

The effects of implementing the present invention can be summarized as follows.

(1) Self-excited vibration of the mill can be prevented. The present invention is also effective in preventing vibration when the mill is stopped, which tends to become more violent than self-excited vibration that occurs during low load operation.

(2) With respect to the above effect (1), the reliability and durability of the mill itself and the plant equipment around the mill are improved.

(3) With respect to the above effect (1), the discomfort of the employees in the plant is eliminated, and the work efficiency is improved.

(4) Since vibration of the mill can be suppressed during low load operation, wide load operation of the apparatus becomes possible.

(5) Turning on / off the mill (one of the mills having a plurality of units stops, and the other one starts)
And the operability of the device is greatly improved.

(6) Coal species and solid fuel, which are likely to cause self-excited vibration, can be used without any problem.

As a result, the applicability of the pulverized raw material to the mill is greatly expanded.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the overall configuration of a roller mill that employs a roller rotation support structure according to an embodiment of the present invention.

FIG. 2 is a plan view of a crushing unit of the roller mill shown in FIG.

FIG. 3 is a diagram showing a behavior of a crushing roller.

FIG. 4 is a diagram showing a change in the state of a crushing unit by carrying out the present invention.

FIG. 5 is a characteristic diagram showing an experimental result using a small device.

FIG. 6 is a characteristic diagram showing an experimental result using a small device.

FIG. 7 is a characteristic diagram showing experimental results using a small device.

FIG. 8 is a characteristic diagram showing test results using large equipment.

FIG. 9 is a characteristic diagram showing test results using large equipment.

FIG. 10 is a characteristic diagram showing test results using large equipment.

FIG. 11 is an amplitude characteristic diagram comparing a conventional technique with an example of the present invention.

FIG. 12 is a sectional view showing a conventional roller rotation support structure.

FIG. 13 is a plan view showing a conventional roller rotation support structure.

FIG. 14 is a characteristic diagram showing a condition for generating self-excited vibration.

FIG. 15 is an explanatory diagram showing the behavior of the roller when self-excited vibration occurs.

FIG. 16 is an explanatory diagram showing the behavior of the roller when self-excited vibration occurs.

[Explanation of symbols]

 1 Raw Material 3 Rotating Table 4 Grinding Roller 7 Roller Rotating Shaft 12 Grinding Ring 13 Grinding Race 14 Raw Material Powder Layer 18 Table Rotating Shaft 201 Grinding Roller 203 Rotating Table 207 Roller Rotating Axis 209 Rotating Table Normal 210 Right Angle to Rotating Table Normal Line 211 Center of rotation of rotary table θt Inclination angle of grinding roller

Front page continuation (72) Eiji Murakami Eiji Murakami 3-36 Takaracho, Kure-shi, Hiroshima Babkotuku Hitachi Co., Ltd. Kure Laboratory (72) Hiroaki Kanemoto 6-9 Takara-cho, Kure-shi, Hiroshima Babkotuku Hitachi Kure Factory (72) Inventor Tadashi Hasegawa 6-9 Takara-cho, Kure City, Hiroshima Prefecture Bab Kotuku Hitachi Kure Factory (72) Inventor Kihachiro Tanaka, 502, Jinmachi-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd.

Claims (2)

[Claims] 1. A crushing raw material by the interlocking action of a circular rotary table driven by an electric motor to rotate, and a plurality of crushing rollers rotating while being pressed by grooves engraved on the outer periphery of the rotary table. In the roller mill for finely pulverizing, the rotation center axis of the pulverizing roller is inclined with respect to the normal line of the rotary table. 2. The roller mill according to claim 1, wherein the inclination angle is regulated within a range of 0.6 ° to 2.4 °.