JP2019000768A - Vertical type roller mill - Google Patents

Abstract

To provide a vertical type roller mill which enables improvement of classification performance.SOLUTION: A vertical type roller mill 1 includes: a cylindrical housing 2; a chute 3 which supplies ground objects to a center part of the housing 2; a grind part 4 which is provided below the chute 3 and grinds the ground objects; a discharge pipe 9 provided above the grind part 4; and a transport mechanism 6 which generates airflow for transporting the ground objects ground by the grind part 4 to the discharge pipe 9. The vertical type roller mill 1 adopts a structure in which a cylindrical flow straightening member 20 is disposed between the grind part 4 and the discharge pipe 9 and the flow straightening member 20 has: an inverted conical part 30 in which a diameter reduces downward; and a cylindrical part 40 extending upward from an upper end 31 of the inverted conical part 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vertical roller mill.

  Conventionally, a vertical roller mill is known as an apparatus for pulverizing and classifying an object to be pulverized such as pulverized coal or cement into a desired particle size. The vertical roller mill pulverizes the object to be crushed in the pulverizing unit, raises the pulverized material on an air stream, and classifies the pulverized material that has been raised by a classifier provided above the pulverizing unit. In such a vertical roller mill, the classification performance for classifying the particles (pulverized material) mixed in the airflow according to the particle diameter is important.

  As a classifier used in a vertical roller mill, there is a rotary classifier using a blade row that rotates around a vertical axis. The principle of classifying particles in this rotary classifier is that the particles are rotated by the subtraction of the fluid drag acting by the gas flow hitting the particles and the centrifugal force acting by the swirling behavior caused by the rotation of the rotating classifying blade. It is said that there are centrifugal separation in which classification is performed depending on whether or not it can pass through and collision classification in which particles collide with the surface of the rotating classification blade and are ejected.

  In the prior art, the classification performance is improved by devising 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 around the rotary classifier by an inverted conical structure called a guide cone, and the upward flow that blows up the outer periphery of the mill and the vicinity of the center of the mill are lowered. A circulating flow is formed. This deflects the airflow that blows up the outer periphery of the mill, causing the particles to flow in the direction toward the rotating classification blade, and drops the classified particles (coarse particles) through the inside of the guide cone for re-grinding. Do.

JP 2009-189909 A

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, and an upward flow is flowed outside thereof and a downward flow is formed inside thereof. In this configuration, the area of the flow path outside the guide cone becomes smaller upward, so that the particles conveyed by the upward flow can be accelerated. However, the upper end of the guide cone communicates with a wide space, and the flow path suddenly increases, so the particle flow rate tends to be non-uniform. If the flow rate of the particles becomes uneven, for example, fine particles with a low flow rate may not pass through the rotary classifier, or conversely, coarse particles with a high flow rate may pass through the rotary classifier. There is a problem of lowering.

  The present invention has been made in view of the above problems, and an object thereof is to provide a vertical roller mill capable of improving the classification performance.

  In order to solve the above-described problems, the present invention provides a cylindrical housing, a chute that supplies a material to be crushed to the center of the housing, and a pulverization that is provided below the chute and crushes the material to be crushed. A vertical roller mill having a portion, a discharge pipe provided above the pulverization unit, and a transport mechanism for forming an air flow for transporting the pulverized material crushed by the pulverization unit to the discharge pipe, A cylindrical rectifying member is disposed between the pulverization part and the discharge pipe, and the rectifying member extends upward from the upper end of the reverse conical part, and an inverted conical part that decreases in diameter downward. The structure of having a cylindrical portion is adopted.

  In the present invention, a rotary classifier is disposed between the rectifying member and the discharge pipe, and the upper end of the rectifying member is at a height equal to or lower than the lower end of the rotary classifying blade of the rotary classifier. The arrangement of being arranged is adopted.

  Moreover, in this invention, the structure of having the deposit fall apparatus which drops the deposit of the said grinding | pulverization material deposited inside the said rectification | straightening member to the said grinding | pulverization part is employ | adopted.

  Moreover, in this invention, the said deposit fall apparatus employ | adopts the structure of having a gas supply means which forms the downward flow which goes to the said crushing part from the lower end opening of the said baffle member.

  Moreover, in this invention, the said deposit fall apparatus employ | adopts the structure of having a mechanical conveyance means to drop the said deposit mechanically from the lower end opening of the said baffle member.

  Moreover, in this invention, the said deposit fall apparatus employ | adopts the structure of having an opening-and-closing means which opens and closes the lower end opening of the said baffle member.

  According to the present invention, the classification performance of the vertical roller mill can be improved.

It is a schematic block diagram of the vertical roller mill 1 in 1st embodiment of this invention. It is a schematic block diagram of the vertical roller mill 1A in 2nd embodiment of this invention. It is a schematic block diagram of the vertical roller mill 1B in another form of 2nd embodiment of this invention. It is a schematic block diagram of the vertical roller mill 1C in another form of 2nd embodiment of this invention.

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

(First embodiment)
FIG. 1 is a schematic configuration diagram of a vertical roller mill 1 in the first embodiment of the present invention.
The vertical roller mill 1 of the present embodiment pulverizes lump coal (raw coal) as a material to be pulverized, classifies pulverized coal (pulverized material) having a desired particle size, and discharges the pulverized coal on an air stream. The code | symbol C shown in a figure shows a to-be-ground material and a pulverized material, and the code | symbol F shows airflow.

  As shown in FIG. 1, the vertical roller mill 1 includes a cylindrical housing 2, a chute 3 that supplies a material to be crushed to the center of the housing 2, and a crushing material that is provided below the chute 3 to crush the material to be crushed. The pulverization unit 4, the discharge pipe 9 provided above the pulverization unit 4, the transport mechanism 6 that forms an air flow for transporting the pulverized material pulverized by the pulverization unit 4 to the discharge pipe 9, , And is configured.

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

  The lid 7 has a rotary classifier 5 attached to the back side thereof. The rotary classifier 5 has a large number of rotary classifying blades 8 arranged at equal intervals in the circumferential direction on a rotary rotor provided at the center of the lid body 7 and is rotated by rotating the rotary rotor by a driving device. The classification blade 8 is rotated at a predetermined rotational speed. An inverted conical guide portion 10 is fixed to the chute 3 below the rotary classifier 5.

The crushing unit 4 includes 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 turntable 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 pressing device, and rotates on the rotary table 11 when the rotary table 11 rotates in this state.

  Under such a configuration, the pulverization unit 4 moves the object to be crushed supplied from the chute 3 to the center 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. Between the pulverizing roller 12 and the pulverizing roller 12, and pulverized by a compressive force and a shearing force.

  The transport mechanism 6 includes an air introduction portion 13 provided on the bottom side surface of the housing 2 and an air introduction means for introducing external air from the introduction port 13a of the air introduction portion 13. The air is guided to the outer edge of the turntable 11, and then the interior of the housing 2 is raised 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 turntable 11 side, toward the upper side of the housing 2, that is, the discharge pipe 9 side. The pulverized material is transported to the discharge pipe 9 side (with accompanying).

  The vertical roller mill 1 having the above-described configuration includes a rectifying member 20 between the pulverizing unit 4 and the discharge pipe 9. The rectifying member 20 is a cylindrical structure having an upper end opening 21 and a lower end opening 22. The inner circumferential surface 20 a of the rectifying member 20 faces the guide portion 10 with a gap, and the outer circumferential surface 20 b of the rectifying member 20 faces the inner wall 2 a of the housing 2 with a gap. The rectifying member 20 is disposed concentrically with the same center as the housing 2 and the rotary classifier 5. The flow regulating member 20 is supported by a plurality of supports (not shown) extending from the inner wall 2 a of the housing 2 and the guide portion 10.

  The rectifying member 20 has an inverted conical portion 30 that is reduced in diameter downward, and a cylindrical portion 40 that extends upward from an upper end 31 of the inverted conical portion 30. The lower end of the inverted conical portion 30, that is, the lower end 24 of the rectifying member 20 is disposed at a height equal to or lower than the lower end opening of the chute 3. The lower end 24 of the rectifying member 20 forms a lower end opening 22 of the rectifying member 20. The lower end opening 22 of the rectifying member 20 is formed larger than the lower end opening of the chute 3. The inverted conical portion 30 occupies about 2/3 of the total height of the flow regulating member 20, and its upper end 31 is located at the height of the middle part of the guide portion 10.

  The cylindrical portion 40 extends upward from the upper end 31 of the inverted conical portion 30 with the same diameter as the upper end 31. The upper end of the cylindrical portion 40, that is, the upper end 23 of the rectifying member 20 is disposed at a height equal to or lower than the lower end 8 a (substantially the same in this embodiment) of the rotary classification blade 8 of the rotary classifier 5. An upper end 23 of the rectifying member 20 forms an upper end opening 21 of the rectifying member 20. The upper end opening 21 of the rectifying member 20 is formed to be larger than the outer diameter of the upper end of the inverted conical guide portion 10 and larger than the outer diameter of the rotating classifier 5 at the lower end 8 a of the rotating classifying blade 8. The cylindrical portion 40 occupies about 1/3 of the total height of the rectifying member 20.

  In order to pulverize the lump coal (raw coal) by the vertical roller mill 1 having such a configuration, classify the pulverized coal having a desired particle size and discharge the pulverized coal from the discharge pipe 9, the lump coal ( The raw coal) is supplied to the inside of the housing 2 to drive the crushing unit 4 and to drive the transport mechanism 6 and the rotary classifier 5 (see FIG. 1). Then, the lump coal is pulverized in the pulverization unit 4 to become coarse coal or pulverized coal.

  Here, in this embodiment, pulverized coal having a particle size of, for example, about 100 μm or less is caused to flow into the rotary classifier 5 together with the airflow that transports the pulverized coal, and larger pulverized coal is moved outside by the centrifugal force of the rotary classifying blade 8. The rotational speed of the rotary classification blade 8 is set so as to push it. This is because, for example, when pulverized coal is used as a fuel for a pulverized coal fired boiler, unburned portions that do not contribute to combustion remain, and energy efficiency is reduced.

  Coarse coal or pulverized coal formed in the pulverization unit 4 is carried on the airflow generated by the transport mechanism 6 and is carried from the rotary table 11 of the pulverization unit 4 to the upper side of the housing 2. When the airflow passes through the outer edge portion of the turntable 11, a swirl component is applied, and the centrifugal force causes the airflow to flow along the inner wall 2a of the housing 2, thereby raising the vicinity of the inner wall 2a.

  This upward flow is guided to the outside of the rectifying member 20. Since the rectifying member 20 has the inverted conical portion 30 whose diameter is reduced downward, the upward flow can be efficiently guided to the outside of the rectifying member 20. In the inverted conical portion 30, the flow area formed between the outer peripheral surface 20 b of the rectifying member 20 and the inner wall 2 a of the housing 2 becomes smaller upward, so that the upward flow can be accelerated. In this way, by accelerating the upward flow for conveying the pulverized material, discharge of the pulverized material from the housing 2 can be promoted.

  The rectifying member 20 has a cylindrical portion 40 that extends upward from the upper end 31 of the inverted conical portion 30. In the cylindrical portion 40, the flow area formed between the outer peripheral surface 20b of the rectifying member 20 and the inner wall 2a of the housing 2 is constant, so that the flow rate of the accelerated upward flow can be adjusted. That is, the pulverized material contained in the upward flow is accelerated outside the inverted conical portion 30 where the flow path area becomes smaller upward, and then flows outside the cylindrical portion 40 with a constant flow path area. Becomes substantially constant.

  The pulverized material that has passed through the upper end 23 of the rectifying member 20 reaches the rotary classifier 5 disposed at the upper portion of the housing 2, and the pulverized material pulverized to a particle size of a predetermined value or less passes through the rotary classifier 5 together with the airflow. It passes through and is discharged. Then, the pulverized product (coarse particles) having a large particle diameter that cannot pass through the rotary classifier 5 falls from the upper end opening 21 of the rectifying member 20 to the inside of the rectifying member 20 by colliding with the rotating classifying blade 8.

  Here, the pulverized product that has passed through the upper end 23 of the flow regulating member 20 is adjusted in flow rate outside the cylindrical portion 40 and reaches the rotary classifier 5 without much variation in the flow rate. It is possible to reduce the probability that the flow rate suddenly increases and the rotary classifier 5 is accidentally passed. Thus, according to the present embodiment, the classification performance of the vertical roller mill 1 can be improved by the rectifying action after acceleration of the upward flow by the cylindrical portion 40 of the rectifying member 20.

  Further, the rectifying member 20 separates the upward flow and the downward flow of the airflow circulating inside the housing 2 between the outside and the inside of the rectifying member 20. As a result, the coarse particles that do not pass through the rotating classification blade 8 descend inside the rectifying member 20, and thus are separated from the upward flow outside the rectifying member 20. For this reason, it is possible to reduce the probability that the classified coarse particles are pushed back by the upward flow and pass through the rotating classifying blade 8 by mistake while approaching the rotating classifier 5 many times. Moreover, since the classified coarse particles fall inside the rectifying member 20 isolated from the upward flow, it is possible to smoothly return to the pulverization unit 4.

  Thus, according to the above-described embodiment, the cylindrical housing 2, the chute 3 that supplies the object to be crushed to the center of the housing 2, and the crushed object that is provided below the chute 3 are crushed. A vertical roller mill 1 having a pulverizing unit 4, a discharge pipe 9 provided above the pulverizing unit 4, and a transport mechanism 6 that forms an air flow for transporting the pulverized material pulverized by the pulverizing unit 4 to the discharge pipe 9. A cylindrical rectifying member 20 is disposed between the pulverizing portion 4 and the discharge pipe 9, and the rectifying member 20 has an inverted conical portion 30 whose diameter is reduced downward, and an upper end of the inverted conical portion 30. By adopting the configuration of having the cylindrical portion 40 extending upward from 31, the classification performance of the vertical roller mill 1 can be improved.

  In the present embodiment, the rotary classifier 5 is disposed between the rectifying member 20 and the discharge pipe 9, and the upper end 23 of the rectifying member 20 is equal to or lower than the lower end 8 a of the rotary classifying blade 8 of the rotary classifier 5. Is arranged at the height of According to this structure, since the distance until the pulverized material that has passed through the upper end 23 of the flow regulating member 20 reaches the rotary classifier 5 is increased, the flow rate of the pulverized material can be intentionally reduced. When the flow rate of the pulverized product is decreased, the rotational speed of the rotary classification blade 8 can be decreased in accordance with the flow rate, so that the running cost of the vertical roller mill 1 can be reduced.

(Second embodiment)
Next, a second embodiment of the present invention will be described. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 2 is a schematic configuration diagram of a vertical roller mill 1A according to the second embodiment of the present invention.
The vertical roller mill 1A according to the second embodiment grinds woody biomass hardened into pellets as a material to be crushed and discharges it on an air current. The code | symbol P shown to a figure shows a pellet (to-be-ground material). Compared with coal, woody biomass is fibrous and has a characteristic that it is difficult to become fine. However, it turns out that it shows combustibility comparable to coal (pulverized coal) with a particle size of about 1 mm and several tens of μm. Therefore, it is preferable to discharge from the mill in a rough state without finely pulverizing.

The woody biomass is preferably classified by accelerating and rectifying by the rectifying member 20 having the inverted conical portion 30 and the cylindrical portion 40 described above, but since it is fibrous and has a low density, There is a problem that it is easy to deposit inside. For this reason, the vertical roller mill 1 </ b> A of the second embodiment has a deposit dropping device 50 that drops the deposit of pulverized material deposited inside the rectifying member 20 onto the pulverization unit 4.
The deposit dropping device 50 shown in FIG. 2 includes a gas supply unit 50A that forms a downward flow F1 from the lower end opening 22 of the flow regulating member 20 toward the pulverization unit 4.

  The gas supply unit 50 </ b> A includes a nozzle 51 that forms a downward flow F <b> 1, a gas supply source 52 that supplies gas to the nozzle 51, and a connection flow path 53 that connects the nozzle 51 and the gas supply source 52. A plurality of nozzles 51 are attached to the lower end of the guide portion 10. The plurality of nozzles 51 are arranged at equal intervals so as to surround the lower end opening of the chute 3. The tip of the nozzle 51 faces the lower end opening 22 of the rectifying member 20. High pressure air is ejected from these nozzles 51. The gas ejected from the nozzle 51 is not limited to air, and may be nitrogen gas, for example.

  The gas supply source 52 includes a blower or a fan that supplies air to the nozzle 51. The gas supply source 52 is disposed outside the housing 2 and is connected to the plurality of nozzles 51 via the connection channel 53. The connection flow path 53 is disposed to the lower end of the guide portion 10 through the inside of a support (not shown) that supports the rectifying member 20. In addition, when a hollow part exists in the inside of the guide part 10, if the gas supply source 52 is installed in the hollow part, the gas supply source 52 and the nozzle 51 can be connected in a short distance. Further, air may be supplied to the nozzle 51 from the air introduction means of the transport mechanism 6 via a flow rate adjustment valve or the like.

  According to such a second embodiment, the downward flow F1 from the lower end opening 22 of the flow regulating member 20 toward the pulverization unit 4 is formed by the gas supply means 50A. The downward flow F <b> 1 suppresses the intrusion of the upward flow from the lower end opening 22 of the rectifying member 20, and drops the deposit accumulated inside the rectifying member 20 to the pulverization unit 4. Thereby, the stable operation of the vertical roller mill 1A for pulverizing the woody biomass is possible without the pulverized material accumulating inside the flow regulating member 20.

  In the second embodiment, a form as shown in FIGS. 3 and 4 can be adopted. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

FIG. 3 is a schematic configuration diagram of a vertical roller mill 1B according to another embodiment of the second embodiment of the present invention.
The vertical roller mill 1B shown in FIG. 3 includes a mechanical transport unit 50B that mechanically drops the deposit inside the rectifying member 20 from the lower end opening 22 of the rectifying member 20 as the deposit dropping device 50.

  This mechanical transport means 50 </ b> B is a rotary valve provided in the lower end opening 22 of the rectifying member 20. The machine conveying means 50B forcibly conveys the deposits accumulated inside the rectifying member 20 to the pulverizing unit 4. Since the lower end opening of the chute 3 is disposed above the machine conveying means 50B and the material to be crushed is input, the rotary valve always rotates, and the deposited material classified with the material to be pulverized is classified. Are preferably dropped onto the pulverizing section 4 at the same time. In addition, as the mechanical conveyance means 50B, you may install conveying apparatuses, such as a screw feeder, instead of a rotary valve.

FIG. 4 is a schematic configuration diagram of a vertical roller mill 1C in another form of the second embodiment of the present invention.
The vertical roller mill 1 </ b> C shown in FIG. 4 has an opening / closing means 50 </ b> C that opens and closes the lower end opening 22 of the flow regulating member 20 as the deposit dropping device 50.

  The opening / closing means 50 </ b> C includes a plurality of opening / closing doors 54 that open / close the lower end opening 22 of the flow regulating member 20. The open / close door 54 is connected to the lower end 24 of the flow regulating member 20 via a hinge mechanism 55, and opens and closes an annular lower end opening 22 formed between the outer peripheral surface of the chute 3. The open / close door 54 is connected to a spring mechanism 56 and opens when the weight of the deposit accumulated inside the flow regulating member 20 exceeds a set value, and then automatically closes.

According to such an opening / closing means 50C, the lower end opening 22 of the rectifying member 20 is normally closed, and the lower end opening 22 of the rectifying member 20 can be opened when deposits are accumulated to some extent inside the rectifying member 20. When the lower end opening 22 of the rectifying member 20 is opened, deposits of a certain weight or more fall at a time, so even if they are slightly affected by the upward flow, the deposits can be dropped without any problem on the pulverization unit 4. it can.
As the opening / closing means 50C, a drive mechanism such as a motor may be installed instead of the spring mechanism 56, and the opening / closing door 54 may be opened / closed at regular intervals. Further, a control device that detects the weight of the deposit accumulated inside the rectifying member 20 with a load cell or the like and controls the drive mechanism so that the opening / closing door 54 is opened when the detected weight exceeds a set threshold value. It may be provided.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, the woody biomass may be crushed in the vertical roller mill of the first embodiment, or the coal may be crushed in the roller mill of the second embodiment. Further, the pulverized product is not limited to coal or woody biomass.

DESCRIPTION OF SYMBOLS 1 Vertical roller mill 2 Housing 3 Chute 4 Crushing part 5 Rotating classifier 6 Transport mechanism 8 Rotating classification blade 8a Lower end 9 Discharge pipe 20 Rectification member 21 Upper end opening 22 Lower end opening 23 Upper end 30 Reverse cone part 40 Cylindrical part 50 Sediment dropping device 50A Gas supply means 50B Machine conveying means 50C Opening / closing means

Claims (6)

A cylindrical housing, a chute for supplying a material to be crushed to the central portion of the housing, a pulverizing portion provided below the chute for pulverizing the material to be crushed, and a discharge provided above the pulverizing portion. A vertical roller mill having a pipe and a transport mechanism for forming an air flow for transporting the pulverized material crushed by the pulverization unit to the discharge pipe,
Between the pulverization part and the discharge pipe, a cylindrical rectifying member is disposed,
The rectifying member is
An inverted conical portion that decreases in diameter downward,
And a cylindrical portion extending upward from the upper end of the inverted conical portion. A rotary classifier is disposed between the flow straightening member and the discharge pipe,
2. The vertical roller mill according to claim 1, wherein an upper end of the rectifying member is disposed at a height equal to or lower than a lower end of a rotary classification blade of the rotary classifier.   3. The vertical roller mill according to claim 1, further comprising a deposit dropping device that drops the pulverized deposit deposited on the inside of the flow regulating member to the pulverization unit.   4. The vertical roller mill according to claim 3, wherein the deposit dropping device includes a gas supply unit that forms a downward flow from a lower end opening of the flow regulating member toward the pulverization unit.   4. The vertical roller mill according to claim 3, wherein the deposit dropping device includes a mechanical conveying unit that mechanically drops the deposit from a lower end opening of the flow regulating member.   The vertical roller mill according to claim 3, wherein the deposit dropping device has an opening / closing means for opening / closing a lower end opening of the flow regulating member.

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