JP2011245378A - Vertical mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical mill that achieves improvement of crushing efficiency and inhibition of rise in mill differential pressure by guiding lump coal supplied from a coal feeding apparatus to a position easily bitten into pressure rollers.SOLUTION: The vertical mill includes: a housing 3 in which a classifying chamber 19 is formed; a crushing table 6 housed in the lower part of the housing and rotatably driven by a table driving device 7; a crushing table cover 8 covering the center of the crushing table; a pressure roller unit 13 which has pressure rollers 14 to be pressurized onto the crushing table; a blowing outlet 22 for blowing off primary air from the periphery of the crushing table; and a coal feeding apparatus 23 which supplies the lump coal onto the crushing table cover. A coal guiding part is formed on the crushing table cover, and the coal supplied from the coal feeding apparatus is guided between the pressure rollers by the coal guiding part.

Description

  The present invention relates to a vertical mill that pulverizes lumps such as coal and limestone into fine powder.

  In a coal-fired boiler using coal as fuel, massive coal is pulverized by a vertical mill into pulverized coal, and the pulverized coal is supplied together with primary air to a burner that is a combustion apparatus.

  The vertical mill includes a housing, a crushing table that is housed in the housing and rotates at a predetermined rotational speed, and a table cover is provided at the center, and a pressure roller unit supported by the housing. Has a structure in which a rotatable pressure roller is pressed against the crushing table. Lumped coal is fed into the center of the crushing table from the coal supply pipe and supplied to the crushing table. The supplied massive coal moves to the outer periphery by the rotational centrifugal force of the pulverizing table, and is pulverized by being caught between the pressure roller and the pulverizing table in the process of moving the coal to the outer periphery of the pulverizing table. The pulverized pulverized coal rises from the primary air blowing port around the pulverizing table, and is supplied to the burner together with the primary air.

  However, in the case of a conventional vertical mill, some of the lump coal that has dropped on the crushing table passes between the pressure rollers and reaches the outer periphery of the crushing table without being bitten by the pressure roller.

  The massive coal that has passed between the pressure rollers is blown up to the primary air blown from the primary air outlet without being crushed, and then falls, so it circulates in the vertical mill without being supplied to the burner. As a result, there are problems such as a decrease in grinding efficiency and an increase in mill differential pressure.

  On the other hand, Patent Document 1 proposes adjusting the height of the dam ring to secure a coal bed and improving the pulverizability. Patent Document 2 proposes to increase the coefficient of friction of the raw material by injecting water into the raw material of the grinding roller.

Japanese Patent Laid-Open No. 11-207200 Japanese Patent Laid-Open No. 7-8818

  In view of such circumstances, the present invention guides the lump coal supplied from the coal feeder to a position where it can be easily caught by the pressure roller, thereby improving the crushing efficiency and suppressing the increase in the mill differential pressure. Is to provide.

  The present invention includes a housing forming a classification chamber, a pulverizing table housed in a lower portion of the housing and driven to rotate by a table driving device, a pulverizing table cover that covers the center of the pulverizing table, and a pressure applied to the pulverizing table. A pressure roller unit having a pressure roller, a blow-off port for blowing primary air from the periphery of the pulverization table, and a coal feeder for supplying massive coal onto the pulverization table cover. A coal guide is formed on the table cover, and the vertical guide mill guides the coal supplied from the coal feeder by the coal guide between the pressure roller and the pressure roller.

  According to the present invention, the pulverizing table cover has a conical portion, the same number of the coal guide portions as the pressure roller protrudes from a peripheral surface of the conical portion, and the pressure roller between adjacent coal guide portions. A coal guide path is formed between the pressure roller and the pressure roller, and the coal guide path is used to guide the coal between the pressure roller and the pressure roller. Each has a triangular pyramid portion provided so as to face the pressure roller, and a coal guide path is formed between the pressure roller and the pressure roller between ridge lines of the triangular pyramid portion, The present invention relates to a vertical mill that guides coal between the pressure roller and the pressure roller by a path.

  According to the present invention, the housing forming the classification chamber, the grinding table housed in the lower part of the housing and driven to rotate by the table driving device, the grinding table cover covering the center of the grinding table, and the grinding table A pressure roller unit having a pressure roller to be pressed, a blow-off port for blowing primary air from the periphery of the pulverization table, and a coal supply device for supplying massive coal onto the pulverization table cover, A coal guide part is formed on the pulverizing table cover, and the coal supplied from the coal feeder is guided between the pressure roller and the pressure roller by the coal guide part. Can be guided to a position where it can be easily bitten by the pressure roller, the biting frequency of the pressure roller can be increased, the coal grinding efficiency can be improved, and the unpulverized state can be improved. Since bulk coal can be prevented from passing through the pressure roller, it is possible to lump coal upflow is the primary air, to suppress an increase in mill differential pressure by circulating the classification chamber.

  According to the invention, the pulverizing table cover has a conical portion, and the same number of the coal guide portions as the pressure roller are projected on the circumferential surface of the conical portion, and the pressurizing member is disposed between adjacent coal guide portions. A coal guide path is formed between the pressure roller and the pressure roller, and the coal guide path guides the coal between the pressure roller and the pressure roller. It can be implemented simply by forming it, has a low manufacturing cost, and can be easily applied to a conventional vertical mill.

  Furthermore, according to the present invention, the crushing table cover has a triangular pyramid portion provided such that the ridge line faces each of the pressure rollers, and the pressure roller and the pressure roller are arranged between the ridge lines of the triangular pyramid portion. Since the coal guide path is formed between the pressure roller and the pressure roller, the coal guide path is formed between the pressure roller and the pressure roller. In addition, the manufacturing cost is low, and an excellent effect that it can be easily applied to a conventional vertical mill is exhibited.

It is a general | schematic elevational sectional view of the vertical mill in this invention. 1A is a perspective view of the grinding table cover, FIG. 1B is a plan view of the grinding table cover, and FIG. 1C is a grinding table cover according to the first embodiment of the present invention. Fig. 3 shows a plan sectional view of the cover. FIG. 4 is a modification of the crushing table cover in the first embodiment of the present invention, (A) shows a perspective view of the crushing table cover, (B) shows a plan view of the crushing table cover, (C) Shows a cross-sectional plan view of the grinding table cover. FIG. 2 is a pulverizing table cover according to a second embodiment of the present invention, (A) is a perspective view of the pulverizing table cover, (B) is a plan view of the pulverizing table cover, and (C) is a pulverizing table. Fig. 3 shows a plan sectional view of the cover.

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

  First, referring to FIG. 1, a vertical mill 1 in which the present invention is implemented will be described. In addition, the following description is a case where a lump is 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. A crushing table 6 is rotatably provided in the lower part of the space via a speed reducer 4 and a bearing 5. The crushing table 6 is rotated at a constant speed or a variable speed by a crushing table motor 7 through the speed reducer 4. The

  The crushing table 6 has a hollow structure in which a space 9 whose upper end is open is formed. A shaft 10 is provided concentrically with the crushing table 6, and the shaft 10 is fixedly erected on the speed reducer 4. It passes through the speed reducer 4 and the grinding table 6. A crushing table cover 8 that closes the opening is fixed to the upper end of the shaft 10. Further, as will be described later, the pulverizing table cover 8 is a coal guiding means, the pulverizing table cover 8 is fixed, and the pulverizing table 6 rotates around the pulverizing table cover 8.

  On the upper surface of the pulverizing table 6, a plurality of table segments 12 each having a concave groove 11 having an arcuate cross section are provided in a ring shape.

  A required number of, for example, three sets of pressure roller units 13 are provided radially from the rotation center of the crushing table 6 at 120 ° intervals. The pressure roller unit 13 has a pressure roller 14 and is tiltable about a horizontal support shaft 15. In addition, three sets of roller pressing devices 16 penetrating radially are provided at the lower portion of the housing 3. The roller pressure device 16 includes an actuator, for example, a hydraulic cylinder 17, and presses the pressure roller 14 against the concave groove 11 by the hydraulic cylinder 17.

  A primary air chamber 18 is formed below the pulverization table 6, and a classification chamber 19 is provided above the pulverization table 6 inside the housing 3.

  A primary air supply port 21 is attached to the lower part of the housing 3, and the primary air supply port 21 is connected to a blower (not shown) and communicates with the primary air chamber 18. Around the pulverization table 6, primary air outlets 22 are provided on the entire circumference.

  A coal feeding / discharging part 23 is provided on the upper side of the housing 3, and a pipe-shaped coal feeding pipe 24 is provided so as to penetrate the central part of the coal feeding / discharging part 23. It extends into the housing 3 and its lower end is located above the center of the grinding table 6. Coal is supplied to the coal supply pipe 24, and the supplied coal falls to the center of the crushing table 6.

  In the coal supply pipe 24, a rotary pipe 25 is rotatably provided on a rotary pipe support portion 26 via a bearing 27. The rotary tube 25 is rotated by a classifier motor 33 via a pulley 31 between a pulley 28 and a pulley 29 and a speed reducer 32 provided with the pulley 29.

  The classifier 35 is constituted by the rotary tube 25, the pulley 28, the pulley 29, the belt 31, the speed reducer 32, the classifier motor 33, and the blade 34.

  The blade 34 has a strip shape and is arranged on the inverted conical curved surface in the circumferential direction at a required angular pitch. The blade 34 is inclined from the lower end toward the upper end so as to be separated from the rotary tube 25, and is attached to the rotary tube 25 via a blade support portion 36.

  A pulverized coal feed pipe 37 for feeding the pulverized pulverized coal is connected to the coal supply / discharge unit 23, and the pulverized coal feed pipe 37 is connected to a burner (not shown) of a boiler. Yes.

  Next, the pulverization of coal in the vertical mill 1 will be described.

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

  The pulverization table 6 is rotated by the pulverization table motor 7 via the speed reducer 4, and primary air at around 200 ° C. is introduced into the primary air chamber 18 from the primary air supply port 21. The lump coal is supplied from the coal supply pipe 24. The lump coal flows down from the lower end of the coal supply pipe 24 to the center of the crushing table 6 and is supplied onto the crushing table 6.

  The coal on the pulverizing table 6 is moved in the outer peripheral direction by centrifugal force generated by the rotation of the pulverizing table 6, is pulverized by being bitten by the pressure roller 14, and becomes pulverized coal containing coarse coal and fine coal, It moves to the outer periphery by centrifugal force.

  The primary air introduced into the primary air chamber 18 from the primary air supply port 21 blows up from the outlet 22 of the pulverizing table 6, and the pulverized charcoal that has climbed over the table segment 12 by centrifugal force, It rides on the primary air blown up from the outlet 22 and moves up the outer peripheral portion of the classification chamber 19 along the wall surface of the housing 3.

  As for the pulverized coal rising on the outer periphery of the classification chamber 19 by the primary air, a part of coarse pulverized coal having a large particle size falls on the pulverization table 6 by its own weight while rising, and the remaining coarse pulverized coal and pulverized coal are left. Rides on the primary air and further raises the classification chamber 19.

  Coarse coal and pulverized coal rising in the classification chamber 19 flows into the classifier 35 together with primary air. When the blade 34 rotated by the classifier motor 33 is crossed, coarse coal having a predetermined particle diameter or more collides with the blade 34 and is repelled and falls onto the crushing table 6. The pulverized coal having a predetermined particle size or less rides on the primary air, crosses the blade 34, is sent out from the pulverized coal feed pipe 37, and is supplied to a boiler burner (not shown).

  Coarse pulverized coal blown off by the blade 34 falls on the pulverizing table 6, and the pulverized coal that has fallen moves to the concave groove 11 by the rotational centrifugal force of the pulverizing table 6. It is crushed again.

  Next, the details of the crushing table cover 8 in the first embodiment of the present invention will be described with reference to FIG.

  The crushing table cover 8 includes a cone portion 38 having a substantially conical shape (including a case where the tip is a cone shape or a curved surface) and a coal guide provided at a position equally divided into three by the circumference of the cone surface of the cone portion 38. The conical surface of the conical portion 38 is exposed between the coal guiding portions 41 and 41, and the exposed conical surface 38 a faces the pressure rollers 14 and 14.

  The coal guiding portion 41 has an upper end at a position lower than the apex of the conical portion 38 by a predetermined distance, and a lower end (lower surface) at the same position (level) as the lower surface of the conical portion 38. Therefore, the top of the conical portion 38 is in a state where the conical surface is exposed over the entire circumference.

  The coal guide part 41 has a convex triangular shape in cross section, and the cross section gradually increases from the upper end toward the lower end. The extension of the ridge line 42a of the coal guiding portion 41 faces the pressure roller 14, and inclined surfaces 42b and 42b spread on both sides with the ridge line 42a as a boundary, and the inclined surfaces 42b and 42b reach the exposed conical surface 38a. The coal guide path 43 is formed by the exposed conical surface 38a and the two inclined surfaces 42b and 42b sandwiching the exposed conical surface 38a, and the coal guide path 43 faces between the pressure rollers 14 and 14. .

  When the above pulverization table cover 8 is applied to the vertical mill 1 of the present invention and pulverization of coal is performed, the lump coal introduced from the coal supply pipe 24 is transferred to the pulverization table 6. The lump coal dropped on the crushing table cover 8 provided in the center and dropped on the crushing table cover 8 slides along the curved surface of the conical part 38 and the rotational centrifugal force of the crushing table 6. To move to the outer periphery of the crushing table 6.

  At this time, the lump coal that has dropped onto the exposed conical surface 38a of the crushing table cover 8 moves directly between the pressure rollers 14 and 14 along the curved surface of the exposed conical surface 38a, and the coal guiding portion. The lump coal that has fallen to the place where 41 is formed is distributed to the left and right by the ridge line 42a, is guided to the exposed conical surface 38a by the inclined surface 42b, and moves between the pressure rollers 14 and 14, respectively. .

  The massive coal dropped from the coal supply pipe 24 is distributed to the three coal guide paths 43 by the coal guide section 41, guided by the coal guide paths 43, and moved toward the pressure roller 14. Without moving, it moves to the position between the pressure rollers 14, 14, that is, the position where the pressure roller 14 is easily caught. Therefore, the biting frequency of the pressure roller 14 is increased, and the coal crushing efficiency can be improved.

  Further, the coal guide portion 41 suppresses the fallen coal from moving toward the pressure roller 14 and passing between the pressure rollers 14 and 14 without being crushed, and the pulverized state without being crushed. The primary air blown up from the blow-out port 22 is blown up and circulated through the classification chamber 19, and the increase in the mill differential pressure can be suppressed.

  In the above embodiment, the number of the coal guide portions 41 is three. However, the coal guide portions 41 are formed corresponding to the pressure rollers 14, and when there are two pressure rollers 14, the coal guide portions 41 are formed. There are two guiding portions 41, and when there are four pressure rollers 14, the coal guiding portions 41 are four.

  FIG. 3 shows a modification of the first embodiment.

  In this modification, the upper end of the coal guide path 43 reaches the apex of the conical portion 38, and the coal guide path 43 has a shape extending radially from the center of the crushing table cover 8.

  The coal guide path 43 also has a convex cross-sectional shape, and the flat cross-sectional shape gradually increases from the upper end toward the lower end. The formation of the coal guide path 43 by the two inclined surfaces 42b, 42b is the same as in the first embodiment.

  In the first embodiment and its modification, the plane cross-sectional shape of the coal guide portion 41 is a convex triangle, but the coal introduced from the coal supply pipe 24 is inserted between the pressure rollers 14 and 14. Any other shape may be used as long as a slope for guiding is formed.

  Further, in the first embodiment and the modification thereof, the coal guiding portion 41 is protruded on the circumferential surface of the conical portion 38. However, a concave portion may be formed on the circumferential surface of the conical portion 38. By forming a slope between the peripheral surface of the conical portion 38 and the concave portion, the same effect as that of the coal guiding portion 41 and the coal guiding path 43 can be obtained.

  Next, a second embodiment of the present invention will be described with reference to FIG. 4 that are the same as those in FIG. 2 are given the same reference numerals, and descriptions thereof are omitted.

  The crushing table cover 8 in the second embodiment has a shape in which a triangular pyramid portion 45 having a substantially triangular pyramid shape whose cross-sectional area gradually increases downward and a cylindrical column portion 46 are combined. .

  The triangular pyramid portion 45 is formed by three coal guide portions 47 extending radially from the center at three-divided positions, and the coal guide portion 47 has a triangular cross section. It has a shape that gradually increases from the front end (front end on the outer peripheral side) toward the center, and has inclined surfaces 48 and 48 that spread downward on both sides with the ridge line 47a as a boundary, and the ridge line 47a of the coal guide portion 47 is , They coincide on the axis of the shaft 10.

  The inclined surfaces 48, 48 of the adjacent coal guide portions 47, 47 are joined at the center position between the coal guide portions 47, 47 to form a boundary line 48a. The boundary line 48a recedes toward the center with respect to the plane including the two adjacent ridge lines 47a and 47a, and the inclined surfaces 48 and 48 are coal having a flat triangular section centering on the boundary line 48a. A guide path 49 is formed, and the coal guide path 49 faces between the pressure rollers 14 and 14.

  When the above pulverization table cover 8 is applied to the vertical mill 1 of the present invention and coal is pulverized, the massive coal introduced from the coal supply pipe 24 (see FIG. 1) is: The lump coal dropped on the crushing table cover 8 provided at the center of the crushing table 6 and dropped on the crushing table cover 8 is distributed to the three coal guiding paths 49 by the coal guiding part 47. , And moves between the pressure rollers 14 and 14 along the coal guide path 49.

  Therefore, the lump coal dropped from the coal supply pipe 24 does not move in the direction of the pressure roller 14, that is, between the pressure rollers 14, 14, that is, the position where the pressure roller 14 is easily bitten. Therefore, the frequency of biting of the pressure roller 14 is increased, and the coal crushing efficiency can be improved.

  In the second embodiment, the longitudinal section of the coal guiding portion 47 has a triangular shape. However, the coal introduced from the coal feeding pipe 24 and distributed by the ridge line 47a is disposed between the pressure rollers 14 and 14. Any other shape may be used as long as the inclined surface that leads to the surface is formed.

  The first embodiment and the second embodiment can be carried out only by forming a coal guide portion on the crushing table cover 8, so that the manufacturing cost is low, and further, compared with the conventional vertical mill. Is also easily applicable.

  Furthermore, in the present invention, a vertical mill for pulverizing massive coal has been described, but it goes without saying that the present invention can also be applied to pulverization of massive substances such as limestone.

DESCRIPTION OF SYMBOLS 1 Vertical mill 5 Bearing 6 Crushing table 8 Crushing table cover 9 Space 10 Shaft 14 Pressure roller 19 Classification chamber 41 Coal guide part 43 Coal guide way 47 Coal guide part 49 Coal guide way

Claims (3)

  A housing forming a classification chamber, a grinding table housed in the lower part of the housing and driven to rotate by a table driving device, a grinding table cover that covers the center of the grinding table, and a pressure that is pressed against the grinding table A pressure roller unit having a roller, a blow-off port for blowing out primary air from the periphery of the pulverization table, and a coal feeder for supplying massive coal onto the pulverization table cover. A vertical mill characterized in that a guide part is formed, and the coal supplied from the coal feeder by the coal guide part is guided between the pressure roller and the pressure roller.   The crushing table cover has a conical portion, and the same number of the coal guide portions as the pressure roller protrudes from a peripheral surface of the cone portion, and the pressure roller and the pressure roller are disposed between adjacent coal guide portions. 2. A vertical mill according to claim 1, wherein a coal guiding path is formed between the pressure roller and the pressure roller.   The crushing table cover has a triangular pyramid portion provided such that the ridge line faces each of the pressure rollers, and a coal guide path directed between the pressure roller and the pressure roller is provided between the ridge lines of the triangular pyramid portion. The vertical mill according to claim 1, which is formed and guides coal between the pressure roller and the pressure roller by the coal guide path.

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