JP2012206046A - Vertical roller mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical roller mill having improved classification efficiency of a classifier that improves the classification efficiency of a classifier and uniforms the classification performance from the top to the bottom of the classifier by equalizing the flow rate distribution of fine powder flowing into the classifier.SOLUTION: In the vertical roller mill 1 that includes a housing 3 defining a classification chamber 16, a grinding table 5 provided on the bottom of the classification chamber 16, a pressure roller 11 pressed to the grinding table 5 to grind a bulk material, and a classifier 36 located in the upper part of the classification chamber 16 and arranged so as to pass ground powder in a state of a flow mixed with air, the classifier 36 has a rotation part 35 rotating around a vertical axis, the rotation part 35 has a predetermined number of blades 44 extending vertically and arranged with a predetermined pitch in the circumferential direction, and rectifier rings 45 are provided at positions vertically dividing the blade 44 into plural parts.

Description

  The present invention relates to a vertical roller mill that pulverizes massive coal, limestone, etc., and supplies it as a fine powder and as a fuel for boilers or as a raw material for cement.

  In a coal-fired boiler using coal as fuel, massive coal is pulverized by a vertical roller mill to form pulverized coal having a predetermined particle diameter, and the pulverized coal is supplied to a burner that is a combustion apparatus together with carrier air.

  The vertical roller mill supplies massive coal on a grinding table, grinds massive coal with a roller that rolls on the grinding table, and the pulverized pulverized coal is conveyed by conveying air, but is supplied to the burner. The pulverized coal is classified by a classifier provided inside the vertical roller mill so as to have a predetermined diameter.

  The classifier is arranged at a predetermined pitch in the circumferential direction, and rotates the blade provided so as to extend in the vertical direction around the vertical axis, thereby applying centrifugal force to the pulverized coal passing through the blade. The pulverized coal is classified by the balance between the centrifugal force and the inflow velocity of the pulverized coal.

  Conventionally, there is one in which the blade is inclined so as to expand its diameter upward so that pulverized coal uniformly flows into the blade.

  As described above, the classifier uses the centrifugal force that the blade exerts on the fluid and pulverized coal, and the inclination of the blade causes a difference between the rotating radius of the lower part of the blade and the rotating radius of the upper part of the blade. As a result, there is a difference in centrifugal force between the lower part and the upper part of the classifier, which may affect the classification performance.

  In the classifier shown in Patent Document 1, the blades are divided into two stages, upper and lower, and the receding angle of the upper blade and the receding angle of the lower blade are made different to make the classifying performance equal.

  On the other hand, the pulverized coal flowing into the classifier has a tendency that the fluid flows in the lower part of the blade in large quantities due to the property that the fluid passes through the path having a small flow resistance. For this reason, a non-uniform flow distribution occurs in the pulverized coal flowing into the blade. For this reason, only a part of the blade contributes to the classification, and the performance of the classifier cannot be exhibited sufficiently. Even in Patent Document 1, no particular reference is made to the flow rate distribution of pulverized coal.

JP-A-4-349944

  In view of such a situation, the present invention equalizes the flow distribution of fine powder flowing into the classifier, improves the classification efficiency of the classifier, and achieves uniform classification performance from the upper part to the lower part of the classifier. The present invention provides a vertical roller mill with improved classification efficiency.

  The present invention includes a housing that defines a classification chamber, a pulverization table provided at a lower portion of the classification chamber, a pressure roller that is pressed by the pulverization table and pulverizes a lump, and an upper portion of the classification chamber. And a classifier equipped with a classifier disposed so that the pulverized powder passes as an air-mixed flow, the classifier has a rotating portion that rotates about a vertical axis, The rotating part has a predetermined number of blades extending in a vertical direction and arranged at a predetermined pitch in a circumferential direction, and relates to a vertical roller mill in which a rectifying ring is provided at a position where the blades are divided into a plurality of vertical directions. Is.

  Further, the present invention relates to a vertical roller mill in which the rectifying ring is inclined so as to become higher toward the center of the classifier.

  Further, the present invention relates to a vertical roller mill in which the rectifying ring is horizontal.

  Further, the present invention relates to a vertical roller mill in which the vertical space defined by the rectifying ring and the inclination of the rectifying ring are set so that the deviation of the flow distribution of the air mixed flow flowing into the blade is reduced. It is.

  According to the present invention, the housing that defines the classification chamber, the pulverization table provided in the lower portion of the classification chamber, the pressure roller that is pressed by the pulverization table and pulverizes the lump, and the upper portion of the classification chamber And a classifier arranged to pass the pulverized powder as an air mixed flow, the classifier has a rotating part that rotates about a vertical axis. The rotating portion has a predetermined number of blades extending in the vertical direction and arranged at a predetermined pitch in the circumferential direction, and a rectifying ring is provided at a position where the blade is divided into a plurality of vertical portions. The mixed flow flowing into the machine is divided in the height direction and equalized, and the classifying effect by the blade is increased, and the classifying effect is improved.

1 is an elevational sectional view of a vertical mill according to a first embodiment of the present invention. It is the elements on larger scale of the classifier in this 1st Example. (A) is a partially enlarged view of the classifier of the second embodiment, (B) is a partially enlarged view of the classifier of the third embodiment, and (C) is a partially enlarged view of the classifier of the fourth embodiment. It is.

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

  A vertical roller mill 1 according to a first embodiment of the present invention will be described with reference to FIG. Moreover, in the following explanatory drawing, the case where a to-be-ground material is coal is shown.

  In the figure, the solid line indicates the flow of the carrier air, and the dotted line indicates the flow of coal.

  A cylindrical housing 3 is erected on a base 2 having a hollow structure or a leg structure, and a sealed space is formed by the housing 3. In the lower part of the space, a crushing table 5 is erected via a speed reducer 4, the speed reducer 4 is driven by a crushing table motor 6, and the crushing table 5 is rotated at a constant speed or a variable speed by the speed reducer 4. Is done.

  On the upper surface of the pulverizing table 5, a table segment 8 having a concave groove 7 having an arcuate cross section is provided.

  A required number of, for example, three sets of pressure roller units 9 are provided at 120 ° intervals radially from the center of rotation of the crushing table 5. The pressure roller unit 9 has a pressure roller 11 and is tiltable about a horizontal support shaft 12. In addition, three sets of roller pressing devices 13 that penetrate radially are provided in the lower portion of the housing 3. The roller pressure device 13 includes an actuator, for example, a hydraulic cylinder 14, and presses the pressure roller 11 against the concave groove 7 by the hydraulic cylinder 14.

  A carrier air chamber 15 is formed below the pulverization table 5, and a classification chamber 16 is provided above the pulverization table 5 inside the housing 3.

  A carrier air supply port 17 is attached to the lower part of the housing 3. The carrier air supply port 17 communicates with the carrier air chamber 15 and is supplied with carrier air through the carrier air supply port 17. Around the pulverization table 5, a blowout port 21 for the carrier air is provided on the entire circumference, and the carrier air is blown up from the blowout port 21 to the classification chamber 16.

  In addition, at the lower part of the pulverizing table 5, there are two foreign substance discharge scrapers 22 that can rotate integrally with the pulverizing table 5, and a coal discharge mechanism (not shown) is provided at the bottom of the conveying air chamber 15. A connected foreign matter discharge chute 23 is provided.

  A coal supply / discharge portion 24 is provided on the upper side of the housing 3. A pipe-shaped supply pipe 25 is provided so as to penetrate the center of the coal supply / discharge portion 24. It extends into the housing 3 and its lower end is located above the center of the grinding table 5. Coal is supplied to the coal supply pipe 25, and the supplied coal falls to the center of the crushing table 5.

  In the coal supply pipe 25, a rotary pipe 26 is rotatably provided on a rotary pipe support portion 27 via a bearing 28. The rotary tube 26 is rotated by a classifier motor 34 via a pulley 29 and a belt 32 spanned between the pulley 31 and a speed reducer 33 provided with the pulley 31.

  A classifier 36 is constituted by the rotary pipe 26, the pulley 29, the pulley 31, the belt 32, the speed reducer 33, the classifier motor 34, and the rotating portion 35.

  A pulverized coal feed pipe 37 that feeds the pulverized pulverized coal is connected to the coal supply / discharge unit 24. The pulverized coal feed pipe 37 is connected to a boiler burner (not shown), and feeds the pulverized coal classified by the classifier 36 to the burner.

  The classifier 36 will be further described with reference to FIG.

  The rotating portion 35 is provided on the rotating tube 26 so as to rotate integrally with the rotating tube 26 about a vertical axis. The rotating part 35 is mainly composed of an upper support ring 41, a support part 42, a lower support ring 43, a blade 44 and a rectifying ring 45.

  Furthermore, it demonstrates concretely. A required number of blade support arms 38 are provided radially on the rotary tube 26, an upper support ring 41 is provided at the tip of the blade support arm 38, and a conical shape is provided below the blade support arm 38 of the rotary tube 26. The support part 42 is provided, and the lower support ring 43 is provided on the support part 42. The lower end of the blade 44 may be supported by the support portion 42, and the lower support ring 43 may be omitted. Here, the center diameter of the upper support ring 41 is larger than the center diameter of the lower support ring 43.

  A strip-shaped blade 44 is provided across the upper support ring 41 and the lower support ring 43, and a predetermined number (for example, 20 to 60) of the blades 44 is disposed at a predetermined pitch in the circumferential direction. . Therefore, the blade 44 is inclined so as to be separated from the rotary tube 26 upward, and the angle formed with the horizontal is θ.

  A plurality of rectifying rings 45 a, 45 b and 45 c are provided in the middle of the blade 44. The rectifying rings 45a, 45b, 45c have a required plate width, that is, a width that can exert a rectifying effect on the flow of pulverized coal.

  The relationship between the rectifying rings 45a, 45b and 45c and the blade 44 is such that the blade 44 is a passing member and a circular arc member obtained by dividing the rectifying rings 45a, 45b and 45c is provided between the blades 44 and 44. Also good. Alternatively, the blade 44 may be used as a through member, and the rectifying rings 45a, 45b, 45c may be fixed to the inner diameter side or the outer diameter side of the blade 44. The rectifying rings 45a, 45b, and 45c may be appropriately supported by ring support arms 46a, 46b, and 46c provided on the rotary tube 26, respectively. The rectifying rings 45a, 45b and 45c are supported by the ring support arms 46a, 46b and 46c, so that the rectifying rings 45a, 45b and 45c are reinforced, and the rectifying rings 45a, 45b and 45c can be thinned and lightened. Can be planned.

  The distance between the lower support ring 43 and the rectifying ring 45a, the distance between the rectifying rings 45a, 45b, and 45c, and the distance between the rectifying ring 45c and the upper support ring 41 may be equal. It may be widened from the top to the top. As will be described later, the rectifying rings 45a, 45b and 45c have a rectifying function and a flow resistance to adjust the flow distribution.

  Next, the operation of the vertical mill 1 will be described.

  The pulverizing table 5 is rotated by the pulverizing table motor 6 via the speed reducer 4, and the carrier air around 200 ° C. fed from an air duct (not shown) is supplied from the carrier air supply port 17 to the carrier air chamber. 15 is introduced.

  When massive coal is introduced from the coal supply pipe 25, the massive coal flows from the lower end of the coal supply pipe 25 to the center of the grinding table 5 and is supplied onto the grinding table 5. The coal on the pulverization table 5 moves in the outer peripheral direction by centrifugal force generated by the rotation of the pulverization table 5, and is pulverized into pulverized coal composed of pulverized coal and pulverized coal by the pressure roller 11 and further centrifuged. Move to the outer periphery by force.

  The carrier air introduced into the carrier air chamber 15 from the carrier air supply port 17 blows up from the outlet 21 of the pulverizing table 5, and the pulverized charcoal that has crossed the table segment 8 by centrifugal force is the outlet. The outer peripheral portion of the classification chamber 16 rises along the wall surface of the housing 3 as a mixed air flow on the carrier air blown up from 21.

  The pulverized coal rising on the outer circumference of the classification chamber 16 by carrying air is such that some coarse pulverized coal having a large particle size falls on the pulverization table 5 due to its own weight while rising, and the remaining pulverized coal and pulverized coal are The classification chamber 16 is further lifted by riding on the carrier air.

  Coarse pulverized coal and pulverized coal flow (air mixed flow) rising in the classification chamber 16 flows into the classifier 36 together with the carrier air.

  Coarse and pulverized coal flows flowing into the classifier 36 are divided in the vertical direction by the rectifying rings 45a, 45b, and 45c, and further perpendicular to or perpendicular to the blade 44 by the rectifying rings 45a, 45b, and 45c. Rectified to approach. Further, by being divided, the lower support ring 43 on the lower side and the rectifying ring 45a and the rectifying rings 45a and 45b, the rectifying rings 45b and 45c, and the rectifying ring 45c and the upper supporting ring 41 are separated. As a result of the action of uniformly directing the pressure balance in each interval, the flow rate distribution passing through the blade 44 is made uniform.

  When the pulverized coal and the pulverized coal flow cross the blade 44 rotated by the classifier motor 34, the pulverized coal having a predetermined particle diameter or more is pushed back to the outside by the centrifugal force of rotation or collides with the blade 44. And is dropped onto the crushing table 5. Further, the pulverized coal having a predetermined particle size or less rides on the carrier air, crosses the blade 44, is sent out from the pulverized coal feeding pipe 37, and is supplied to a boiler burner (not shown).

  The pulverized coal blown off by the blade 44 falls on the pulverizing table 5, and the pulverized coal that has fallen moves to the concave groove 7 by the rotational centrifugal force of the pulverizing table 5, and is pressed by the pressure roller 11. It is crushed again.

  The distance between the lower support ring 43 and the rectifying ring 45a, the distance between the rectifying rings 45a, 45b, and 45c, and the distance between the rectifying ring 45c and the upper support ring 41 are increased from the bottom to the top. May be. Since the flow resistance becomes larger when the interval is narrower, by reducing the lower interval of the classifier 36, the amount of distribution to the upper side of the pulverized coal flow is further increased, and the flow distribution is further equalized. .

  Thus, since the entire length of the blade 44 contributes to classification, classification efficiency increases.

  FIG. 3A shows a second embodiment.

  In the second embodiment, the rectifying rings 45a, 45b and 45c are angled. The angles of the rectifying rings 45a, 45b, 45c are set to be perpendicular to the blade 44, for example. By providing an angle to the rectifying rings 45a, 45b, 45c, the shape of the rectifying rings 45a, 45b, 45c is a conical curved surface cut into a ring shape.

  FIG. 3B shows a third embodiment. In the third embodiment, the rectifying rings 45a, 45b, 45c are provided with an angle, and the angle is set to be larger as it goes upward. For example, the lowermost rectifying ring 45a is horizontal, the angle formed by the rectifying ring 45b is horizontal, α is the angle formed by the rectifying ring 45c is horizontal, and the like. The angles of the rectifying rings 45a, 45b, and 45c may be set so that the uneven flow distribution is eliminated.

  In the third embodiment, since the angle at the lower stage becomes smaller, the angle relative to the fluid flow direction becomes larger, the flow path resistance is increased accordingly, and the amount of fluid distributed upward is increased. Although not shown, the intervals between the rectifying rings 45a, 45b, 45c may be changed, and the angle may be changed.

  FIG. 3C shows a fourth embodiment. In the fourth embodiment, the angle .theta. Of the blade 44 is 90.degree., That is, vertical. By adjusting the intervals and angles of the rectifying rings 45a, 45b and 45c, the blade 44 extends over the entire length. The flow distribution is made uniform. By making the blade 44 vertical, the rotation radii at the upper and lower portions of the blade 44 are the same, and the difference in centrifugal force is eliminated, so that there is no variation in classification performance.

  In the above embodiment, the inflow portion of the classifier is divided into four parts vertically by the three rectifying rings 45a, 45b, 45c, but it may be divided into two or three parts, or five or more parts. If the number of divisions is too large, the flow path resistance becomes too large. Further, since there are problems such as an increase in weight, practically, 3 to 5 divisions are preferable.

  The widths (radial dimensions) of the rectifying rings 45a, 45b, and 45c are appropriately determined according to the rectifying effect. Further, the outer circumferences of the rectifying rings 45a, 45b, 45c need not be the same as the outer ends of the blades 44, and may protrude outward. In this case, it is up to about 1/3 of the blade 44. Further, the amount of protrusion to the center side needs to be at least 1/2 of the length of the blade 44 in consideration of the rectifying effect.

  The angle of the rectifying rings 45a, 45b, 45c may be an angle up to a tilt angle +15 degrees with respect to the blade 44 from a right angle. By providing a downward angle toward the outside in accordance with the inclination of the blade 44 of the classifier 36, an effect of smoothing the inflow of fluid and rectifying the blade 44 in the vertical direction is expected.

DESCRIPTION OF SYMBOLS 1 Vertical roller mill 3 Housing 5 Grinding table 9 Pressure roller unit 11 Pressure roller 15 Carrying air chamber 16 Classifying chamber 26 Rotating pipe 35 Rotating part 36 Classifier 41 Upper support ring 42 Support part 43 Lower support ring 44 Blade 45 Current regulating ring

Claims (4)

  A housing that defines a classification chamber, a pulverization table provided at a lower portion of the classification chamber, a pressure roller that is pressed against the pulverization table and pulverizes a lump, and an upper portion of the classification chamber that is pulverized. The classifier has a rotating part that rotates about a vertical axis, and the rotating part has a rotating part that rotates around a vertical axis. A vertical roller mill having a predetermined number of blades extending in a vertical direction and arranged at a predetermined pitch in a circumferential direction, and a rectifying ring provided at a position where the blades are divided into a plurality of vertical portions.   The vertical roller mill according to claim 1, wherein the rectifying ring is inclined so as to become higher toward a center of the classifier.   The vertical roller mill according to claim 1, wherein the rectifying ring is horizontal.   The vertical roller mill according to claim 2, wherein a vertical interval defined by the rectifying ring and an inclination of the rectifying ring are set so as to reduce a deviation in a flow distribution of an air mixed flow flowing into the blade.

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