JP2010201399A - Vertical mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical mill in which pressure loss is reduced by throwing coal off to the center side of a classifying chamber with a classifier and thereby preventing interference with the primary air ascending along the inner wall of a housing. <P>SOLUTION: The vertical mill includes: the housing 3 in which a classifying chamber 16 is formed; a grinding table 5 housed in a lower part of the housing and rotatably driven; a plurality of roller pressurizing devices 13 which pressurize a pressure roller 11 to the grinding table to grind coal thereon; a coal feeding device 19 which feeds coal masses to the grinding table; and a classifier 36 for rotating a blade 28 and classifying the ground coal; wherein the blade is arranged on a conical curved surface with a required angular pitch in the circumferential direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vertical mill for pulverizing coal supplied to a coal-fired boiler.

  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.

  First, an outline of a conventional vertical mill 1 will be described with reference to FIGS.

  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 a circular arc 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 primary air chamber 15 is formed below the crushing table 5, and a classification chamber 16 is provided above the crushing table 5 inside the housing 3.

  A primary air supply port 17 is attached to the lower portion of the housing 3, and the primary air supply port 17 is connected to a blower (not shown) and communicates with the primary air chamber 15. Around the pulverization table 5, primary air outlets 18 are provided on the entire circumference.

  A coal supply / discharge part 19 is provided on the upper side of the housing 3, and a pipe-shaped supply pipe 21 is provided so as to penetrate the central part of the coal supply / discharge part 19. 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 21, and the supplied coal falls to the center of the crushing table 5.

  In the coal supply pipe 21, a rotary pipe 22 is rotatably provided on a rotary pipe support portion 23 via a bearing 10. The rotary tube 22 is rotated by a classifier motor 26 via a pulley 20 and a belt 24 spanned between the pulley 25 and a speed reducer 30 provided with the pulley 25.

  The classifier 27 is constituted by the classifier motor 26, the speed reducer 30, the pulley 25, the pulley 20, the belt 24, the rotary tube 22, and the blade 28.

  The blades 28 have a strip shape and are arranged on the inverted conical curved surface at a required angular pitch in the circumferential direction. The blade 28 is inclined so as to be separated from the rotary tube 22 from the lower end toward the upper end, and is attached to the rotary tube 22 via the blade support portion 37.

  Below the classifier 27, an inverted conical reject chute 31 is disposed so as to partition the classifying chamber 16 up and down, and the reject chute 31 contains pulverized charcoal at a required angular pitch in the circumferential direction. A slit 32 through which primary air passes is formed.

  The upper end of the reject chute 31 is fixed to the housing 3 and is supported by a reject chute support 33 via a bracket 29 fixed to the coal supply pipe 21. The lower end of the reject chute 31 has a cylindrical shape, and the lower end is opened to form an opening 34 between the coal supply pipe 21.

  A pulverized coal feed pipe 35 for feeding the pulverized pulverized coal is connected to the coal feed / discharge unit 19, and the pulverized coal feed pipe 35 is connected to a boiler burner (not shown). 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 pulverizing table 5 is rotated by the pulverizing table motor 6 via the speed reducer 4, and primary air at around 200 ° C. is introduced into the primary air chamber 15 from the primary air supply port 17. Then, lump coal is introduced from the coal supply pipe 21. The lump coal flows down from the lower end of the coal supply pipe 21 to the center of the crushing table 5 and is supplied onto the crushing 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 primary air introduced into the primary air chamber 15 from the primary air supply port 17 blows up from the outlet 18 of the pulverizing table 5, and the pulverized charcoal that has climbed over the table segment 8 by centrifugal force, It rides on the primary air blown up from the outlet 18 and moves up the outer peripheral portion of the classification chamber 16 along the wall surface of the housing 3.

  The pulverized coal rising on the primary air around the outer periphery of the classification chamber 16 falls on the pulverization table 5 due to its own weight while a part of the coarse pulverized coal having a large particle diameter is rising, and a part thereof is the reject chute 31. And is repelled toward the lower outer peripheral side of the classification chamber 16. Coarse pulverized coal bounced by the reject chute 31 falls onto the crushing table 5. The remaining pulverized coal and pulverized coal ride on the primary air, pass through the slit 32, and further move up the classification chamber 16.

  Coarse and pulverized coal that has passed through the slit 32 flows into the classifier 27 together with primary air. When crossing the blade 28 rotated by the classifier motor 26, coarse coal having a predetermined particle size or more collides with the blade 28 and is repelled. Further, since the blade 28 is provided on the inverted conical curved surface, the coarse coal is blown off to the outer peripheral side of the classification chamber 16. Further, pulverized coal having a predetermined particle size or less rides on the primary air, crosses the blade 28, is sent out from the pulverized coal feed pipe 35, and is supplied to a boiler burner (not shown).

  Coarse coal discharged by the blade 28 falls on the outer peripheral portion of the classification chamber 16, slides along the slope of the reject chute 31, and falls from the opening 34 to the center of the pulverizing table 5. . The fallen coarse pulverized coal moves to the concave groove 7 by the rotational centrifugal force of the pulverization table 5 and is pulverized again by the pressure roller 11. A part of the pulverized coal that slides down also falls from the slit 32.

  As described above, since the reject chute 31 is provided, when the primary air passes through the slit 32, the flow path is narrowed to cause pressure loss.

  In addition to the falling from the opening 34, the coarse pulverized coal bounced off by the blade 28 also falls from the slit 32 when sliding along the slope of the reject chute 31. Therefore, the coarse coal falling from the slit 32 collides with the primary air and the pulverized coal flowing from the slit 32 on the primary air, and the pressure loss in the slit 32 increases, and the primary air The mill differential pressure, which is the difference between the pressure of the primary air introduced from the supply port 17 and the pressure of the primary air and pulverized coal discharged from the pulverized coal feed pipe 35, is increased.

  Furthermore, there is a problem that the coarse coal powder falling from the slit 32 is dispersed and dropped on the pulverizing table 5 and the pulverization efficiency is lowered.

  FIG. 5 shows another conventional example. As shown in the figure, the reject chute 31 is removed so as to prevent the pressure loss by narrowing the flow path of the primary air.

  In the illustrated vertical mill 1, since there is no reject chute 31, the coarse pulverized coal blown outward by the blade 28 falls along the inner wall of the housing 3. Therefore, it collides with coarse coal or pulverized coal rising on the primary air blowing up near the inner wall of the housing 3 to cause a large pressure loss, and the pulverization does not fall to the center of the pulverization table 5. It may fall to the periphery of the table 5 and may accumulate without being caught by the pressure roller 11, resulting in a decrease in pulverization efficiency.

JP-A-10-128140

JP-A-11-207202

JP 2002-18360 A

  In view of such circumstances, the present invention is a vertical mill which prevents interference with primary air rising along the inner wall of the housing by blowing coal to the center side of the classification chamber by a classifier and reducing pressure loss. 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, and a plurality of pulverizing coals on the pulverizing table by pressing a pressure roller against the pulverizing table. A roller pressurizing device; a coal feeding device that supplies massive coal to the grinding table; and a classifier that classifies the ground coal by rotating a blade, the blade having a required angular pitch in a circumferential direction on a conical curved surface This relates to a vertical mill arranged in the above.

  In the present invention, a ring-shaped seal plate is welded to the inner wall of the housing, the lower ends of the blades are connected to each other by a lower ring, a bent gap is formed between the seal plate and the lower ring, and the seal The present invention relates to a vertical mill in which a seal is constituted by a plate and the lower ring.

  According to the present invention, the housing forming the classification chamber, the crushing table housed in the lower part of the housing and driven to rotate, and the pressure roller pressed against the crushing table to crush the coal on the crushing table. A plurality of roller pressurizing devices, a coal feeder for supplying massive coal to the pulverizing table, and a classifier for classifying the pulverized coal by rotating a blade, the blade being required in a circumferential direction on a conical curved surface Since the classifier is arranged at an angular pitch, the classifier flips coal with a large particle size toward the center of the classification chamber to prevent interference with coal and primary air rising along the inner wall of the housing. Reduce pressure loss.

  According to the present invention, a ring-shaped seal plate is welded to the inner wall of the housing, the lower ends of the blades are connected to each other by a lower ring, and a bent gap is formed between the seal plate and the lower ring, Since the seal is constituted by the seal plate and the lower ring, it exhibits an excellent effect of preventing the pulverized coal pulverized by the roller pressure device from being sent to the boiler without being classified by the classifier. .

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  The vertical mill according to the present invention will be described with reference to FIGS. The basic configuration of the vertical mill in which the present invention is implemented is the same as that of the vertical mill shown in FIG. 1 to 3, the same components as those shown in FIG. 4 are denoted by the same reference numerals.

  A coal supply / discharge part 19 is provided on the upper side of the housing 3, and a pipe-shaped supply pipe 21 is provided so as to penetrate the central part of the coal supply / discharge part 19, and the supply pipe 21 is connected to the housing. 3, and the lower end is located above the center of the crushing table 5. Coal is supplied to the coal supply pipe 21, and the supplied coal falls to the center of the crushing table 5.

  In the coal supply pipe 21, a rotary pipe 22 is rotatably provided on a rotary pipe support portion 23 via a bearing 10. The rotary tube 22 is rotated by a classifier motor 26 via a pulley 20 and a belt 24 spanned between the pulley 25 and a speed reducer 30 provided with the pulley 25.

  A classifier 36 is constituted by the classifier motor 26, the speed reducer 30, the pulley 25, the pulley 20, the belt 24, the rotary tube 22, and the blade 28.

  The blades 28 are arranged on the conical curved surface at a required angle pitch, and the upper ends of the blades 28 are fixed to the rotary tube 22 via an upper ring 40, and the middle part of the blades 28 is a blade support part 37. It is fixed to the rotary tube 22 via Further, the lower ends of the blades 28 are connected to each other by a lower ring 38. Thus, the rotating portion of the classifier 36 has an umbrella-bone structure.

  The position of the lower ring 38 is a position near the inner wall of the housing 3 and not in contact with the inner wall, and a ring-shaped upper convex portion 39 protruding upward is provided on the upper surface of the outer end portion of the lower ring 38. .

  An outer end portion of a ring-shaped seal plate 41 is welded to the inner wall of the housing 3, and the seal plate 41 is formed so that the inner end portion is bent downward, and the inner end portion is a downward convex portion 42. Is forming.

  The seal plate 41 is positioned near and above the lower ring 38, and the tip of the upper convex portion 39 is positioned above the tip of the lower convex portion 42 so as not to contact the seal plate 41. Is provided. The tip of the lower convex portion 42 is also provided so as not to contact the lower ring 38, and a bent gap is formed between the lower ring 38 and the seal plate 41.

  A ring-shaped convex portion projecting downward is formed on the lower surface of the outer end portion of the lower ring 38, and a convex portion is formed by bending the inner end portion of the seal plate 41 upward. May be provided near and below the lower ring 38 to form a bent gap.

  Hereinafter, the pulverization of coal using the vertical mill of the present invention 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 5 is rotated by the pulverization table motor 6 via the speed reducer 4, and the coal supply is performed in a state where primary air at around 200 ° C. is introduced into the primary air chamber 15 from the primary air supply port 17. Bulk coal is introduced from the pipe 21. The lump coal flows down from the lower end of the coal supply pipe 21 to the center of the crushing table 5 and is supplied onto the crushing table 5.

  The coal on the pulverizing table 5 is moved in the outer peripheral direction by centrifugal force generated by the rotation of the pulverizing table 5, and is pulverized into pulverized coal composed of coarse and pulverized coal by the pressure roller 11. To move to the outer circumference.

  The primary air introduced into the primary air chamber 15 from the primary air supply port 17 blows up from the blowout port 18 of the pulverization table 5, and the pulverized charcoal that has passed over the table segment 8 by centrifugal force is Riding on the primary air blown from the mouth 18, the outer peripheral portion of the classification chamber 16 rises along the wall surface of the housing 3.

  The classifier motor 26 rotates the rotating tube 22 via the speed reducer 30, the pulley 25, the belt 24, and the pulley 20, and the rotating tube 22 rotates the blade 28.

  The pulverized coal that rises in the classification chamber 16 along with the primary air along the wall surface of the housing 3, and coarse pulverized coal with a large particle size falls in the middle due to its own weight while rising, and the blade 28 of the classifier 36 is When crossing, coarse coal having a predetermined particle size or more collides with the blade 28 disposed on the conical curved surface and is repelled. Since the blade 28 is inclined so as to be separated from the rotary tube 22 from the upper end to the lower end, the coarse coal is blown off toward the center of the classification chamber 16. In the case of pulverized coal having a predetermined particle size or less, the pulverized coal rides on the flow of primary air and can be traversed without being blown off by the blade 28. It is sent out and supplied to a boiler burner (not shown).

  Coarse coal that has been blown off toward the center by the blade 28 falls at the center of the classification chamber 16 and falls at the center of the crushing table 5. The fallen coarse pulverized coal moves in the outer peripheral direction by the centrifugal force generated by the rotation of the pulverizing table 5, moves to the concave groove 7 by the rotational centrifugal force of the pulverizing table 5, and is pulverized again by the pressure roller 11. It rides on the primary air blown up from the mouth 18 and is again classified by the classifier 36.

  Also, the primary air rising along the inner wall of the housing 3 is sealed by the lower ring 38 and the sealing plate 41, and the pulverized coal and the pulverized coal are not classified into the classifier 36. The supply pipe 35 is prevented from being supplied to a boiler burner (not shown).

  As described above, by arranging the blade 28 on the conical curved surface, coarse coal having a predetermined particle diameter or larger, which is crushed by the pressure roller 11 and rises on the primary air, is stored in the classification chamber 16. You can play it in the center direction. Therefore, the blown-off coarse pulverized coal is prevented from colliding with the upward flow blowing up the outer peripheral portion of the classification chamber 16, and the pressure of the primary air introduced from the primary air supply port 17 and the pulverized coal are prevented. The mill differential pressure, which is the difference between the primary air discharged from the feed pipe 35 and the pressure of the pulverized coal, can be reduced, and the coarse pulverized coal struck by the blade 28 falls to the peripheral portion of the pulverizing table 5. And since it does not bite into the said pressure roller 11 and does not accumulate, the grinding | pulverization efficiency of pulverized coal can be raised.

  Moreover, since the vertical mill 1 of the present invention classifies pulverized coal using only the classifier 36, the apparatus configuration may be simpler than that of a conventional vertical mill.

It is an elevation sectional view showing an embodiment of the invention. It is a principal part expanded sectional view which shows embodiment of this invention. It is an enlarged view of A of FIG. It is an elevational sectional view showing a conventional vertical mill. It is a principal part expanded sectional view of FIG. It is a principal part expanded sectional view which shows the conventional vertical mill.

DESCRIPTION OF SYMBOLS 1 Vertical mill 3 Housing 5 Grinding table 13 Roller pressurization device 16 Classifying chamber 22 Rotating pipe 27 Classifier 28 Blade 36 Classifier 38 Lower ring 39 Upper convex part 41 Seal plate 42 Lower convex part

Claims (2)

  A housing forming a classification chamber, a crushing table housed in a lower part of the housing and driven to rotate, and a plurality of roller pressurizing devices that crush the coal on the crushing table by pressing a pressure roller against the crushing table And a coal feeder for supplying the lump coal to the pulverizing table, and a classifier for classifying the pulverized coal by rotating a blade, the blades being arranged on a conical curved surface at a required angular pitch in the circumferential direction. A vertical mill characterized by that.   A ring-shaped seal plate is welded to the inner wall of the housing, the lower ends of the blades are connected to each other by a lower ring, and a bent gap is formed between the seal plate and the lower ring. The seal plate and the lower ring The vertical mill according to claim 1, wherein a seal is constituted by.

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