JPH0210698B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vertical roller mill incorporating a rotary vane classifier.

Vertical roller mills are known as pulverizers that are equipped with a rotating table and rollers that roll on the table, and that pulverize raw material, which is powder or granule, that is supplied between the two.

A feature of this pulverizer is that it employs an air conveyance system for powder and granules to perform classification and drying at the same time as pulverization within the pulverizer.

In this type of pulverizer, the supplied raw material is caught between a rotating table and rotating rollers, pulverized, and extruded onto the outer periphery of the rotating table. on the other hand,
An air outlet is placed on the outer periphery of the rotary table, from which air is blown upward.
Among the raw materials that have been crushed and pushed out to the outer periphery, the coarse ones are blown back into the middle of the table, and the fine ones are carried by the airflow and reach the classifier installed at the top of the mill, where they are classified. After the powder has reached a predetermined level of powder, it is carried as a product out of the pulverizer by airflow and collected by a dust collector. On the other hand, the coarser powder separated by the classifier is returned to the rotary table of the mill, and pulverized repeatedly until it reaches a predetermined fineness. As a result, a circulating flow of highly concentrated powder and granules is generated inside the mill, which increases the pressure loss of the air conveying the powder and increases power consumption. For example, in a large vertical roller mill that crushes cement raw materials, the electric motor of the exhaust fan that generates the ventilation force inside the crusher is larger than the electric motor of the crusher.

The present invention was made to eliminate the above-mentioned conventional drawbacks, and aims to reduce pressure loss,
It is an object of the present invention to provide a vertical roller mill configured to suppress power consumption and increase grinding efficiency.

To this end, in the present invention, a rotary table for pulverizing the raw material and a rotary roller that rolls on the rotary table are provided in the lower part of the casing, and a classifier is installed in the upper part of the casing to separate coarse powder and fine powder using rotating blades. In the vertical roller mill, a chute is provided below the outer periphery of the rotary table to discharge coarse particles of the crushed raw material to the outside of the machine, and a chute is provided in the lower part of the casing surrounding the rotary blades of the classifier from the outer periphery. , a plurality of take-out parts for the coarse powder separated by the classifier to the outside of the machine are provided around the casing, and the coarse powder take-out passage of the coarse powder take-out parts is connected to the part of the casing surrounding the rotary blades of the classifier. The casing is provided in communication with the inner wall surface, and is formed so that the diameter of the casing surrounding the crushing section is smaller than the diameter of the casing surrounding the classifier at the installation height position of the coarse powder extraction section. Another chute was connected to the lower end outlet of the powder extraction part, and the above two types of chute were connected to a raw material supply chute for supplying new raw materials via a transporter outside the crusher to form a vertical roller mill. .

Hereinafter, details of the present invention will be explained with reference to the drawings.

FIG. 1 illustrates an embodiment of the present invention.
In the figure, a vertical roller mill, designated as a whole by reference numeral 1, is composed of a lower casing 2 and an upper casing 3. And lower casing 2
A rotary table 4 is arranged in the center of.
This rotary table 4 is rotated at a predetermined speed via a reducer 5 connected to an electric motor (not shown).

A plurality of rollers 6 are disposed on the rotary table 4 so as to be rotatable and in contact with the surface of the rotary table 4. The pressure with which the roller 6 is pressed onto the rotary table can be adjusted by a hydraulic device (not shown).

A classifier 9 is disposed within the upper casing 3 connected to the lower casing 2. The classifier 9 is rotated by an electric motor 10 via a shaft 11.
A large number of blades 13 are attached to the lower end of this shaft 11 via support members 12. Further, a discharge port 3a is protruded from the side of the upper end of the upper casing 3, and the pulverized product is taken out from the discharge port 3a together with the discharged air. An annular air outlet 21 is provided below the lower casing 2 between the outer periphery of the rotary table 4 and the lower casing 2, as shown in FIGS. 2 and 3. A gas conduit 20 that supplies cold air or hot air is connected below the annular air outlet 21 . A chute 19 is provided below the lower casing 2 for discharging the coarse raw material that has fallen through the annular air outlet 21 to the outside of the machine. A rotary valve 19a is provided in the middle of the chute 19 to discharge the raw material while maintaining airtightness. The lower end of the chute 19 is connected to the transport aircraft 16.

Further, as shown in FIGS. 2 and 4, a protruding dam ring 2 is provided on the outer periphery of the upper surface of the rotary table 4.
2 is provided, and an attempt is made to place the raw material on the rotary table 4 as much as possible and crush as much as possible, but considering that the raw material contains iron particles, one part of the dam ring 22 is Notches 23 are provided at several places in the section, so that the iron powder accumulated on the rotary table 4 can be quickly discharged to the outside of the rotary table 4.

On the other hand, the pulverized material that reaches the classifier 9 on the airflow ejected from the annular air outlet 21 is separated into coarse powder and fine powder, and the fine powder (product) passes through the classifier and exits from the discharge port 3a. It is sent to the product collection device along with the gas. The coarse powder is in the upper casing 3.
A plurality of coarse powder extraction parts 14 are installed around the
It is collected into a transport machine 16 through a chute 15 from its lower end outlet 14a. The plurality of coarse powder extracting portions 14 are formed in the lower part of the upper casing 3 in a portion surrounding the rotary blades 13 of the classifier 9 from the outer circumferential side, and the coarse powder extracting passages of the coarse powder extracting portions 14 are formed as described above. , and is formed in communication with the inner wall surface of the upper casing 3 in a portion surrounding the rotating blade 13 from the outer peripheral side. Then, this coarse powder extraction section 1
At the installation height position 4, the diameter of the lower casing 2, which is the casing surrounding the crushing section consisting of the crushing rollers and rotary table, that is, the diameter of the upper end portion of the lower casing 2 is equal to the diameter of the rotating blades 13 of the classifier 9. The diameter of the lower part of the upper casing 3 is smaller than the diameter of the part surrounding the upper casing 3 from the outer peripheral side. A rotary valve 15a is provided in the middle of the chute 15 for discharging coarse powder while maintaining airtightness. Shoot 15, 19
Contaminants such as iron particles are removed from the coarse powder etc. discharged from the transporter 16 by an electromagnet 16a provided at the tip of the transporter 16, and the material is transported to a chute for supplying raw materials by a bucket elevator 17, which is a type of transporter. It will be returned to 7. A chute 7 is provided on the side of the lower casing 2 to supply raw materials from the outside of the vertical roller mill 1 onto the rotary table 4 . A rotary valve 7a is provided above the chute 7 to supply raw materials while keeping it airtight. 18 is a transport aircraft that transports new raw materials to the chute.

Next, the operation of this embodiment configured as above will be explained.

When the electric motors 5 and 10 are started and the roller table 4 and classifier 9 rotate, material to be crushed is fed onto the roller table 4 via the chute 7.

On the other hand, an exhaust fan (not shown) operates, and air flows into the lower casing 2 and the upper casing 3 as shown by the chain lines.
It is sent out to the next process from the discharge port 3a formed at the upper end of.

As the rotary table rotates, the raw material is crushed between the rotary table 4 and the rollers 6. Among the pulverized raw materials, coarse raw materials or iron particles with large specific gravity that do not get on the jet of the annular air outlet 21 fall through the annular air outlet 21 and are sent to the chute 19.
The raw material is discharged to the outside of the machine, impurities such as metals are removed by the electromagnet 16a, and returned to the chute 7 for supplying raw materials, where it is supplied together with new raw materials onto the rotary table 4 and pulverization is repeated.

On the other hand, among the crushed products that are guided upward by the rising air current, relatively coarse ones cannot completely ride the air current, and some of them are carried away by their own weight and are placed on the rotary table as shown by the solid line in Figure 1. It falls and is re-pulverized. Also, among the crushed products that have reached the classifier 9 on the air current, the coarser ones (coarse powder) are transported to the rotating blade 13.
The rotor is struck by the rotary blade 13 and is blown to the inner wall surface of the upper casing 3 located on the outer circumferential side of the rotating blade 13, where it stalls and descends along the inner wall surface, communicating with this inner wall surface. The powder flows smoothly and reliably as it is into the coarse powder extraction channels of the coarse powder extraction sections 14 located in plurality in the circumferential direction of the upper casing 3.
In this case, since the diameter of the upper end portion of the lower casing 2 is formed to be smaller than the diameter of the upper casing 3 at the attachment portion of the coarse powder extractor 14, the coarse powder separated by the classifier 9 is When descending along the inner wall surface of the upper casing 3 and flowing into the coarse powder extraction flow path of the coarse powder extraction section 14 communicating with this inner wall surface, the upper end portion rises within the lower casing 2 The coarse powder flows smoothly and reliably into the coarse powder extraction channel of the coarse powder extraction section 14 without being hindered by the dust-containing gas flow that flows into the upper casing 3 and is introduced into the classifier 9. . Also,
Lower casing 2 at the attachment part of the coarse powder extraction part 14
By making the diameter relationship between the upper casing 3 and the upper casing 3 as described above, the coarse powder falling downward along the inner wall surface of the upper casing 3 flows from the lower casing 2 into the upper casing 3 and into the classifier 9. Not easily disturbed by dust-containing gas flow. In this way, the coarse powder moved to the inner circumferential surface of the upper casing 3 by the rotary vane 13 descends along the inner wall surface, and the coarse powder that has descended is moved to the coarse powder extractor 14.
The inflow operation into the machine is carried out smoothly and reliably, and the action of taking out the coarse powder out of the machine is carried out smoothly and reliably. Note that, by taking out the coarse powder in this manner, the coarse powder that descends along the inner wall surface of the upper casing 3 and flows into the coarse powder extraction section 14 causes the rise of the coarse powder that flows into the classifier 9. The airflow is not easily disturbed, there is no pressure loss due to such turbulence in the gas flow, and the dust-containing gas flow smoothly passes through the rotating blades 13 of the classifier 9.
The classification action in the classifier 9 is also performed smoothly.

In this way, the coarse powder that has flowed into the coarse powder extractor 14 exits from the lower end outlet 14a, passes through the coarse powder extractor chute 15, and is returned onto the rotary table 4 by the transporters 16 and 17 outside the machine. The material is crushed again in the crushing section. Of course, if fine iron powder is included in the coarse powder falling through the coarse powder removal chute 15, it is removed by the action of the electromagnet 16a. The fine powder is
It passes through the classifier 9 on an air current, is discharged from the discharge port 3a, and is recovered as a product. The powderiness of the product is mainly controlled by the rotation speed of the classifier and the amount of ventilation in the mill. Since the present invention is constructed and operated as described above, the following effects can be achieved.

(1) In conventional vertical roller mills, most of the pressure loss between the mill inlet and mill outlet occurs at the air outlet (blade ring) provided on the outer periphery of the rotary table. This occurs because the powder extruded to the outer periphery on the rotary table is lifted up by a high-speed air jet.

In order to reduce this pressure loss, the present invention discontinues the blade ring system and provides an annular air outlet with an appropriate cross-sectional shape on the outer periphery of the rotary table. In this way, the jet velocity is reduced and the pressure drop in this area becomes very small. However, on the other hand, since the flow rate is reduced, the coarse raw material falls through the annular air outlet and is discharged out of the mill. The discharged coarse powder is returned to the raw material supply port of the pulverizer using a transport device such as a bucket elevator. As a result, according to the system of the present invention, the power cost of the exhaust fan is much lower than that of the conventional system.

(2) In addition, in the conventional method, among the crushed products that were crushed and reached the classifier on the updraft, the coarse powder separated there was suspended in the mill and increased the mill differential pressure. By taking this out of the machine and mechanically returning it to the mill supply port, the mill differential pressure can be reduced, further reducing the power consumption of the exhaust fan.

(3) When grinding raw materials contaminated with iron, according to the conventional method, iron particles are difficult to grind, so as they circulate inside the mill, the amount gradually increases.
The progress of crushing is inhibited. For this reason, even if an attempt is made to remove iron using an electromagnet before supplying the raw material to a crusher, the reality is that the iron contained in the raw material cannot be completely removed.

However, in the present invention, if an electromagnet is installed in the coarse powder circulation section outside the pulverizer, the iron contained in the raw materials will be pulverized once and discharged in the form of iron particles, etc., so that the electromagnet can be used efficiently. Even raw materials containing large amounts of iron particles can be easily pulverized.

(4) In addition, if there are a large number of iron particles, the dam ring provided on the outer periphery of the rotary table can be cut out in several places to quickly discharge the iron particles that accumulate on the rotary table. .

As is clear from the above description, according to the present invention, the pressure loss is caused by the reduction in the amount of raw material circulating inside the crusher when the coarse powder separated by the rotary vane classifier is taken out of the machine. and the reduction in pressure loss due to the reduction in ventilation speed inside the crusher due to the coarse particles in the pulverized raw material on the rotary table of the crusher being taken out from the bottom of the rotary table outside the machine instead of being lifted up to the top of the crusher. The power consumption of the exhaust fan can be significantly reduced compared to the conventional method, and the crushing capacity is also increased, so it is possible to reduce the power consumption per unit of crushing. . When the coarse powder is taken out of the machine from the classification section, the coarse powder separated by the classifier is passed along the inner wall surface of the casing surrounding the rotary blade from the outer circumferential side to the coarse powder extraction section. can be smoothly and reliably removed from the machine. That is, the operation of the coarse powder descending along the inner wall surface of the casing;
The operation of the descending coarse powder flowing into the coarse powder take-out section is not easily hindered by the rising gas flow that rises from the crushing section to the classification section, so the action of taking out the coarse powder outside the machine is reduced. is carried out smoothly and reliably.
In this way, by reliably taking out the coarse powder to the outside of the machine, the pressure loss can be stably and reliably reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, FIG. 2 is a cross-sectional view thereof, FIG. 3 is a partially enlarged sectional view of FIG. 1, and FIG. 4 is a partially enlarged sectional view of FIG. FIG. 1...Roller mill, 2...Lower casing, 3
... Upper casing, 4 ... Rotary table, 5,
10...Electric motor, 6...Roller, 7, 15, 19
... Shoot, 9 ... Classifier, 14 ... Coarse powder extraction section, 16, 18 ... Transport machine, 16a ... Electromagnet,
17...bucket elevator, 21...annular air outlet, 22...dam ring, 23...notch.

Claims (1)

[Claims] 1 A vertical roller mill equipped with a rotary table that crushes raw materials in the lower part of the casing, a rotary roller that rolls on the rotary table, and a classifier that separates coarse powder and fine powder with rotating blades in the upper part of the casing. A chute is provided below the outer periphery of the rotary table to discharge coarse particles of the crushed raw material to the outside of the machine, and a chute is installed in the lower part of the casing surrounding the rotary blades of the classifier from the outer periphery to separate the raw materials using the classifier. A plurality of extracting portions for removing coarse powder to the outside of the machine are provided around the casing, and a coarse powder extracting flow path of the coarse powder extracting portions is communicated with an inner wall surface of the casing in a portion surrounding the rotating blades of the classifier. The diameter of the casing on the side surrounding the crushing part is smaller than the diameter of the casing on the side surrounding the classifier at the installation height position of the coarse powder extracting part, and the lower end of the coarse powder extracting part is formed. A vertical roller mill characterized in that the outlet is connected to another chute, and the two types of chute are connected to a raw material supply chute for supplying new raw materials via a transporter outside the crusher.