JP6911550B2 - Vertical roller mill - Google Patents

Description

The present invention relates to a vertical roller mill.

Conventionally, a vertical roller mill is known as an apparatus for pulverizing an object to be pulverized such as pulverized coal or cement to a desired particle size and classifying the object. In this vertical roller mill, the object to be crushed is crushed in the crushing section, the crushed material is put on an air flow to be raised, and the raised crushed material is classified by a classifier provided above the crushing section. In such a vertical roller mill, the classification performance for classifying the particles (crushed matter) mixed in the air flow according to the particle size is important.

As a classifying machine used for a vertical roller mill, there is a rotary classifying machine using a blade train that rotates around a vertical axis. The principle of classifying particles in this rotary classifier is that the particles rotate by subtracting the fluid resistance that acts when the gas flow hits the particles and the centrifugal force that acts due to the swirling behavior that occurs with the rotation of the rotary classifier blades. It is said that there are centrifugal separation in which classification is performed depending on whether or not the particles can pass through, and collision classification in which particles collide with the surface of the rotary classification blade and are ejected.

In the prior art, the classification performance is improved by devising measures such as controlling the shape of the rotary classifier and the inflow direction of the gas flow. For example, in Patent Document 1 below, the inside of the mill is divided by an inverted conical structure called a guide cone around the rotary classifier, and an ascending current that blows up the outer circumference of the inside of the mill and a descending flow near the center of the mill. It forms a circulating flow. As a result, the airflow that blows up the outer circumference of the inside of the mill is deflected so that the particles flow in the direction toward the rotary classification blade, and the classified particles (coarse particles) are dropped through the inside of the guide cone to re-crush. conduct.

Japanese Unexamined Patent Publication No. 2009-189909

However, the prior art has the following problems.
In the prior art, an inverted conical guide cone is provided in order to return the classified particles to the center of the crushing table, an ascending flow flows outside the guide cone, and a descending flow is formed inside the guide cone. In this configuration, coarse particles that cannot pass through the rotary classifier can be received, moved to the center of the mill, and returned to the rotary table.
In recent years, from the viewpoint of reducing carbon dioxide emissions, a technique for using woody biomass as a fuel in a coal-fired power plant has been desired. Compared to coal, woody biomass is fibrous and therefore has the characteristic of being less likely to become fine, but it is known that it exhibits combustibility comparable to that of coal (pulverized coal) of several tens of μm with a particle size of about 1 mm. If the coal can be discharged from the vertical roller mill in a coarse state without being finely crushed, the crushing capacity can be increased.
However, since woody biomass is fibrous, if the above-mentioned conventional coal mill is used as it is, there is a concern that coarse particles may be deposited inside the guide cone. Therefore, when crushing woody biomass, it is necessary to modify the guide cone or the like, and the operation must be stopped every time the fuel is switched, which causes a problem that the time during which power generation cannot be generated is extended.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vertical roller mill capable of operating objects to be crushed having different properties such as coal and woody biomass without major modification.

In order to solve the above problems, the present invention has a cylindrical housing, a chute that supplies an object to be crushed to the center of the housing, and a crushing that is provided below the chute to crush the object to be crushed. A vertical roller mill having a section, a rotary classifier provided above the crushing section, and a transport mechanism for forming an air flow for transporting the crushed material crushed by the crushing section to the rotary classifier. , A cylindrical rectifying member surrounding the rotary classifier and a return that guides the rising flow of the airflow formed on either the inside or the outside of the rectifying member to the other side and forms the falling flow of the airflow. A configuration is adopted in which a flow path and an opening / closing device for opening and closing the return flow path are provided.

Further, in the present invention, when woody biomass is supplied from the chute as the object to be crushed, the switchgear closes the return flow path, and coal is supplied from the chute as the object to be crushed. If so, the switchgear adopts a configuration in which the return flow path is opened.

Further, in the present invention, a condensing flow path for narrowing the flow path area of the air flow is provided between the crushing portion and the rectifying member, and the condensing flow path is provided in the central portion of the housing. A configuration is adopted in which the first condensing ring is formed between the first condensing ring and the second condensing ring provided so as to project from the housing toward the center thereof.

Further, in the present invention, a configuration is adopted in which the crushing portion and the rectifying member have an airflow guiding portion that protrudes from the inner wall of the housing and guides the rising airflow to the inside of the rectifying member.

Further, in the present invention, crushed material induction that guides the crushed material contained in the air flow that protrudes from the inner wall of the housing between the crushed portion and the rectifying member and descends outside the rectifying member to the crushed portion. Adopt a configuration that has a part.

According to the present invention, it is possible to obtain a vertical roller mill that can be used for operating objects to be crushed having different properties such as coal and woody biomass without major modification.

It is a schematic block diagram of the vertical roller mill 1 which shows the state at the time of crushing coal in embodiment of this invention. It is a schematic block diagram of the vertical roller mill 1 which shows the state at the time of crushing the woody biomass in embodiment of this invention. It is (a) perspective view and (b) plan sectional schematic view which shows the structure of the switchgear 50 in embodiment of this invention. It is a perspective view which shows the structure of the switchgear 50A in one modification of the Embodiment of this invention. It is a perspective view which shows the structure of the switchgear 50B in one modification of the Embodiment of this invention. It is a perspective view which shows the structure of the switchgear 50C in one modification of the Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a vertical roller mill 1 showing a state when coal is crushed according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a vertical roller mill 1 showing a state when woody biomass is crushed according to an embodiment of the present invention.
The vertical roller mill 1 of the present embodiment crushes the material to be crushed, classifies the crushed material having a desired particle size, and discharges the crushed material in an air flow. The reference numeral C shown in FIG. 1 indicates coal (material to be crushed), the crushed material is indicated, and the reference numeral F indicates an air flow. Further, the reference numeral P shown in FIG. 2 indicates a woody biomass (object to be crushed) solidified into pellets, and the reference numeral F indicates an air flow.

As shown in FIGS. 1 and 2, the vertical roller mill 1 is provided with a cylindrical housing 2, a chute 3 for supplying an object to be crushed to the center of the housing 2, and an object to be crushed below the chute 3. A crushing unit 4 for crushing the material, a rotary classifier 5 provided above the crushing unit 4, a transport mechanism 6 for forming an air flow for transporting the crushed material crushed by the crushing unit 4 to the rotary classifier 5, and a transport mechanism 6 described later. The rectifying member 20 and the opening / closing device 50, which will be described later, are provided.

The housing 2 has a cylindrical shape that is erected along the vertical direction, and has a lid 7 that covers the upper end opening thereof. A cylindrical chute 3 is inserted through the lid 7 at the center thereof. The chute 3 is arranged along the vertical direction, the upper end opening is arranged outside the lid 7, and the lower end opening is arranged below the rotary classifier 5 inside the housing 2. .. A raw material supply device (not shown) is connected to the chute 3, whereby a predetermined amount of the object to be crushed is supplied to the inside of the housing 2.

Further, a rotary classifier 5 is attached to the back surface side of the lid body 7. The rotary classifier 5 has a large number of rotary classifiers 8 arranged at equal intervals in the circumferential direction on a rotary rotor provided at the center of the lid 7, and is rotated by rotating the rotary rotor by a drive device. The classification blade 8 is rotated at a predetermined rotation speed. The crushed material that has passed through the rotary classification blade 8 is discharged to the outside of the vertical roller mill 1 from the discharge pipe 9 provided at the upper part of the housing 2.

The crushing portion 4 is configured to include a rotary table 11 provided at the bottom of the housing 2 and a plurality of crushing rollers 12 that roll on the rotary table 11.
The rotary table 11 is configured to rotate at a relatively low speed on a horizontal plane.
The crushing roller 12 is brought into pressure contact with the rotary table 11 by a roller pressurizing device, and the rotary table 11 rotates in that state to roll on the rotary table 11.

Based on such a configuration, the crushing unit 4 moves the object to be crushed supplied from the chute 3 to the central portion of the rotary table 11 to the outer peripheral side by the centrifugal force of the rotary table 11, and the upper surface of the rotary table 11 is moved. It is bitten between the crushing roller 12 and the crushing roller 12 and crushed by a compressive force and a shearing force.

The transportation mechanism 6 includes an air introduction portion 13 provided on the side surface of the bottom of the housing 2 and an air introduction means for introducing external air from the introduction port 13a of the air introduction portion 13, by means of the air introduction means. The air is guided to the outer edge of the rotary table 11 and then the inside of the housing 2 is raised so as to flow into the discharge pipe 9. Based on such a configuration, the transport mechanism 6 generates an air flow from the bottom side of the housing 2, that is, the rotary table 11 side, toward the upper side of the housing 2, that is, the discharge pipe 9 side, and puts the air flow on the air flow. (Accompanied), the crushed material is transported to the rotary classifier 5.

The vertical roller mill 1 having the above configuration is provided with a tubular rectifying member 20 that surrounds the outside of the rotary classifier 5. The rectifying member 20 is supported by the housing 2 by a beam member (not shown). As shown in FIG. 1, the rectifying member 20 guides an ascending flow in a direction along the rotary classification vane 8, and has a guide surface 21 arranged at a certain interval from the rotary classifier 8. The rotary classification blade 8 of the present embodiment is inclined so as to expand in the radial direction toward the upper side, and the guide surface 21 is formed in a correspondingly inverted conical shape (funnel shape). The upper end portion 20a of the rectifying member 20 is arranged at a height of more than half of the total height of the rotary classification blade 8.

The rectifying member 20 forms a flow path through which an air flow flows between the blades of the rotary classification blade 8 from the lower 8b to the upper 8a of the rotary classification blade 8. That is, it is preferable that the distance between the guide surface 21 and the rotary classification blade 8 is set narrow. For example, the guide surfaces 21 may be arranged at intervals so as to be in sliding contact with the rotary classification blade 8. The rectifying member 20 has a diameter-expanded portion 22 that attracts an air flow rising toward the lower end 8b1 of the rotary classification blade 8. The lower end 8b1 of the rotary classification vane 8 forms the inlet of the inter-blade flow path of the rotary class vane 8. The enlarged diameter portion 22 extends downward from the lower end of the guide surface 21. The diameter-expanded portion 22 is formed in a conical shape in which the diameter gradually increases toward the bottom.

A return flow path 15 is formed between the upper end portion 20a of the rectifying member 20 and the partition wall portion 2b of the housing 2. The partition wall portion 2b of the housing 2 is a ceiling wall of the housing 2 extending in the horizontal direction, and is a space before passing through the rotary classifier 5 (a space on the crushing section 4 side) and a space after passing through the rotary classifier 5. (Space on the 9 side of the discharge pipe) is separated from the space. The return flow path 15 is a ring-shaped flow path that guides the ascending flow of the airflow formed inside the rectifying member 20 to the outside of the rectifying member 20 to form a descending flow of the airflow.

The vertical roller mill 1 has an air flow guiding portion 31 provided so as to project from the inner wall 2a of the housing 2 between the crushing portion 4 and the rectifying member 20, and a crushed material guiding portion 32. The airflow guiding portion 31 guides the airflow rising along the inner wall 2a of the housing 2 to the inside of the rectifying member 20. The crushed material guiding unit 32 guides the crushed material contained in the airflow descending outside the rectifying member 20 to the crushed material 4. The airflow guiding portion 31 and the pulverized material guiding portion 32 are provided in the second condensing ring 30, which will be described later.

The airflow guiding portion 31 is provided in a ring shape on the lower side of the second contraction ring 30, and has an inclined surface that is inclined diagonally upward. On the other hand, the crushed material guiding portion 32 is provided in a ring shape on the upper side of the second condensing ring 30, and has an inclined surface that is inclined obliquely downward. The crushed material guiding unit 32 has a larger inclination angle than the airflow guiding unit 31 so that the crushed material can easily slide off. As described above, in the second condensing ring 30, the inclined surface inclined diagonally upward of the airflow guiding portion 31 and the inclined surface inclined obliquely downward of the crushed material guiding portion 32 are integrally formed in the vertical direction with the backs facing each other. It is provided.

The vertical roller mill 1 having the above configuration has a reduced flow path 10 that narrows the flow path area of the air flow between the crushing section 4 and the rectifying member 20. The condensate flow path 10 accelerates the flow velocity of the air flow and improves the discharge property of a relatively large crushed material (particularly woody biomass) that tends to stay in the housing 2. The condensing flow path 10 includes a first condensing ring 40 provided at the center of the housing 2 and a second condensing ring 30 provided so as to project from the housing 2 toward the center. It is formed between.

The first condensing ring 40 is provided around the chute 3. The first condensing ring 40 is provided in the region from the lower end of the rotary classifier 5 to the lower end of the chute 3. The first condensing ring 40 projects (extends) from the chute 3 toward the inner wall 2a of the housing 2 in the radial direction of the housing 2.

The second contraction ring 30 is provided on the inner wall 2a of the housing 2. The second condensing ring 30 is provided at a height facing the first condensing ring 40 in the radial direction of the housing 2. The second contraction ring 30 projects (extends) inward in the radial direction of the housing 2 from the inner wall 2a of the housing 2 toward the chute 3.

The second condensing ring 30 has an inner diameter larger than the outer diameter of the first condensing ring 40. That is, the second condensing ring 30 faces the first condensing ring 40 with a gap in the radial direction of the housing 2. This gap becomes the contraction flow path 10. In the present embodiment, the condensing flow path 10 is formed in a region outside 1/2 of the radius of the housing 2. Further, the inner diameter of the second contraction ring 30 is smaller than the diameter of the inner wall 2a of the housing 2. That is, the condensing flow path 10 is formed in a region inside the inner wall 2a of the housing 2.

The facing surface 42 of the first condensing ring 40 facing the second condensing ring 30 is formed flat. The facing surface 42 formed on the first condensing ring 40 is vertically provided vertically downward from the lower end 8b1 of the rotary classification blade 8 at a predetermined distance. A flat surface (tip portion) vertically downward from the lower end of the crushed material guiding portion 32 is also provided on the facing portion (tip portion) of the second condensing ring 30 facing the first condensing ring 40 (a flat surface). (Not shown) is formed parallel to the facing surface 42. At the lower part of the first contraction ring 40, an inclined surface 41 that inclines upward toward the second contraction ring 30 is formed. The inclined surface 41 is formed from the lower end of the facing surface 42 to the lower end of the chute 3.

The vertical roller mill 1 having the above configuration includes a switchgear 50 that opens and closes the return flow path 15. The switchgear 50 has a plurality of plate-shaped members 51 provided so as to be openable and closable between the upper end portion 20a of the rectifying member 20 and the partition wall portion 2b of the housing 2. As shown in FIG. 1, when coal C is supplied from the chute 3 as the object to be crushed, the switchgear 50 opens the return flow path 15. Further, as shown in FIG. 2, when the woody biomass P is supplied from the chute 3, the switchgear 50 closes the return flow path 15.

FIG. 3 is a perspective view (a) and a schematic plan sectional view (b) showing the configuration of the switchgear 50 according to the embodiment of the present invention. Note that, in FIG. 3A, a part (region surrounded by reference numeral A) of the ring-shaped return flow path 15 shown in FIG. 3B is conceptually represented.
The switchgear 50 has a rotation shaft 52 that rotates the plate-shaped member 51 around an axis extending in the vertical direction. The lower end of the rotating shaft 52 is rotatably supported by the upper end portion 20a of the rectifying member 20, and the upper end of the rotating shaft 52 is rotatably supported by the partition wall portion 2b of the housing 2.

A plurality of such plate-shaped members 51 are provided in the circumferential direction along the upper end portion 20a of the rectifying member 20. The plurality of plate-shaped members 51 can be opened and closed from the outside by a link mechanism (not shown). For example, a variable vane mechanism may be adopted as such a link mechanism. The variable vane mechanism is, for example, a plurality of plate-shaped members engaged with the ring member by engaging each of the pieces fixed to the upper end of the rotating shaft 52 with the ring member and rotating the ring member in the circumferential direction. The opening / closing angle of 51 is adjusted.

Returning to FIGS. 1 and 2, in order to crush the object to be crushed by the vertical roller mill 1 having such a configuration, classify the crushed object having a desired particle size, and discharge it from the discharge pipe 9, shoot in the same manner as before. The object to be crushed is supplied from No. 3, the crushing unit 4 is driven, and the transport mechanism 6 and the rotary classifier 5 are driven, respectively. Then, the object to be crushed is crushed in the crushed portion 4 to become a crushed product containing fine particles and coarse particles.

The crushed material crushed in the crushing unit 4 is put on the air flow generated by the transport mechanism 6 and carried from the rotary table 11 of the crushing unit 4 to the upper side of the housing 2. When the airflow passes through the outer edge of the rotary table 11, a swirling component is applied, and the centrifugal force causes the airflow to flow along the inner wall 2a of the housing 2, whereby the airflow rises in the vicinity of the inner wall 2a. .. When this airflow rises to some extent along the inner wall 2a of the housing 2, it is guided to the condensing flow path 10 by the airflow guiding portion 31 below the second condensing ring 30. The condensate flow path 10 increases the flow velocity by narrowing the flow path area of the air flow, and improves the discharge property of the crushed material.

When this airflow passes through the contracted flow path 10, it is guided to the inside of the rectifying member 20. Since the airflow guiding portion 31 of the present embodiment projects toward the central portion of the housing 2, the airflow rising along the inner wall 2a can be guided to the inside of the rectifying member 20. The rectifying member 20 is provided so as to surround the outside of the rotary classifier 5, and guides the ascending current in the direction along the rotary classifier 8. According to this configuration, the crushed material is classified in the middle of ascending, and it is not necessary to blow up all the crushed material containing coarse particles to the uppermost part before the classification, and the load on the transport mechanism 6 is reduced. Inside the rectifying member 20, the crushed material is classified from the lower portion 8b to the upper portion 8a of the rotary classification blade 8. The fine particles that have passed through the rotary classification blade 8 are discharged from the discharge pipe 9 to the outside of the housing 2.

As shown in FIG. 1, when coal C is supplied from the chute 3 as an object to be crushed, the return flow path 15 is opened by the switchgear 50. The return flow path 15 guides the ascending flow of the airflow formed inside the rectifying member 20 to the outside of the rectifying member 20 to form a descending flow of the airflow. Therefore, the coarse particles that have not passed through the rotary classification blade 8 reach the upper end portion 20a of the rectifying member 20 and descend outside the rectifying member 20, so that they are separated from the airflow rising inside the rectifying member 20. .. Therefore, it is possible to reduce the probability that the classified coarse particles accidentally pass through the rotary classification blade 8 while being pushed back by the ascending current and approaching the rotary classifier 5 many times. The coarse particles descending from the outside of the rectifying member 20 are returned to the central portion of the rotary table 11 by the crushed material guiding portion 32 protruding from the inner wall 2a of the housing 2. As a result, the time required for the re-grinding step of the coarse particles can be shortened.

On the other hand, as shown in FIG. 2, when the woody biomass P is supplied from the chute 3 as the object to be crushed, the return flow path 15 is closed by the switchgear 50. As described above, it is known that the woody biomass P has a particle size of about 1 mm and exhibits the same level of flammability as coal C having a particle size of several tens of μm. If it can be discharged from the vertical roller mill 1 in a coarse state without being finely crushed, the crushing capacity can be increased. Therefore, by closing the return flow path 15 and pushing back the classified coarse particles by the ascending current to approach the rotary classifier 5 many times, the discharge property of the coarse particles can be promoted. Further, by closing the return flow path 15, it is possible to prevent the fibrous woody biomass P from being entangled and accumulating on the outside of the rectifying member 20. In this case, the rotation of the rotary classifier 5 may be stopped in order to promote the discharge of coarse particles.

As described above, according to the above-described embodiment, the cylindrical housing 2, the chute 3 that supplies the object to be crushed to the central portion of the housing 2, and the chute 3 provided below the chute 3 to crush the object to be crushed. A vertical mold having a crushing unit 4, a rotary classifying machine 5 provided above the crushing unit 4, and a transport mechanism 6 for forming an air flow for transporting the crushed material crushed by the crushing unit 4 to the rotary classifying machine 5. A return that is a roller mill 1 and has a tubular rectifying member 20 surrounding the rotary classifier 5 and guides an ascending flow of airflow formed inside the rectifying member 20 to the outside of the rectifying member 20 to form a descending flow of airflow. By adopting a configuration having a flow path 15 and an opening / closing device 50 for opening and closing the return flow path 15, objects to be crushed having different properties such as coal and woody biomass can be operated without major modification. A vertical roller mill 1 is obtained.

Although the preferred embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the above embodiment. The various shapes and combinations of the constituent members shown in the above-described embodiment are examples, and can be variously changed based on design requirements and the like within a range that does not deviate from the gist of the present invention.

For example, the following modifications can be adopted as one aspect of the embodiment of the present invention. In the following description, the same or equivalent configurations as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be simplified or omitted.

FIG. 4 is a perspective view showing the configuration of the switchgear 50A in a modified example of the embodiment of the present invention.
In the switchgear 50A shown in FIG. 4, the rotation shaft 52A of the plate-shaped member 51A is rotatably supported around an axis extending in the horizontal direction. According to this configuration, the return flow path 15 is opened and closed by rotating the plate-shaped member 51A around an axis extending in the horizontal direction.

FIG. 5 is a perspective view showing the configuration of the switchgear 50B in a modified example of the embodiment of the present invention.
In the switchgear 50B shown in FIG. 5, plate-shaped members 51B rotating around an axis extending in the horizontal direction are arranged in a blind shape. The rotation shaft 52B of the plate-shaped member 51B is connected so that the angle can be adjusted by a tilt pole or a cord (not shown). According to this configuration, the return flow path 15 is opened and closed by rotating the plurality of plate-shaped members 51B around an axis extending in the horizontal direction.

FIG. 6 is a perspective view showing the configuration of the switchgear 50C in a modified example of the embodiment of the present invention.
In the switchgear 50C shown in FIG. 6, a through hole 2b1 into which the plate-shaped member 51C can be inserted and removed is formed in the partition wall portion 2b of the housing 2. According to this configuration, the return flow path 15 is opened and closed by inserting and removing the plate-shaped member 51C into the through hole 2b1.

Further, for example, in the above embodiment, an ascending flow is formed inside the tubular rectifying member 20 and a descending flow is formed outside the rectifying member 20, but the rectifying member 20 is an inverted cone as in the conventional technique described above. When the shaped guide cone is provided, an ascending flow may be formed on the outside of the guide cone and a descending flow may be formed on the inside of the rectifying member 20.

Further, for example, in the above-described embodiment, coal and woody biomass are exemplified as the objects to be crushed. Can be applied.

1 Vertical roller mill 2 Housing 2a Inner wall 3 Chute 4 Crusher 5 Rotational classifier 6 Transport mechanism 10 Condensed flow path 15 Return flow path 20 Rectifier member 30 Second condensing ring 31 Airflow guiding section 32 Crushed material guiding section 40 1 constriction ring 50 switchgear

Claims (4)

A cylindrical housing, a chute for supplying an object to be crushed to the center of the housing, a crushing portion provided below the chute to crush the object to be crushed, and a rotation provided above the crushing portion. A vertical roller mill having a classifier and a transport mechanism for forming an air flow for transporting the crushed material crushed by the crushing unit to the rotary classifier.
A tubular rectifying member surrounding the rotary classifier and
A return flow path that guides the ascending flow of the airflow formed on either the inside or the outside of the rectifying member to the other side and forms the descending flow of the airflow.
Have a opening and closing device for opening and closing the return flow path,
When woody biomass is supplied from the chute as the object to be crushed, the switchgear closes the return flow path.
A vertical roller mill characterized in that, when coal is supplied from the chute as the object to be crushed, the switchgear opens the return flow path. A condensing flow path for narrowing the flow path area of the air flow is provided between the crushing portion and the rectifying member.
The condensing flow path is formed between a first condensing ring provided in the center of the housing and a second condensing ring protruding from the housing toward the center. vertical roller mill according to claim 1, wherein in that, it is. The vertical according to claim 1 or 2, wherein the crushing portion and the rectifying member have an airflow guiding portion that projects from the inner wall of the housing and guides the rising airflow to the inside of the rectifying member. Type roller mill. It is characterized by having a crushed material guiding portion that projects from the inner wall of the housing between the crushed portion and the rectifying member and guides the crushed material contained in the airflow descending outside the rectifying member to the crushed portion. The vertical roller mill according to any one of claims 1 to 3.

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