JP2010149052A - Vertical mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve improvement of grinding efficiency and inhibition of self-excited vibration in a vertical mill by improving a biting rate of supplied coal. <P>SOLUTION: The vertical mill includes the housing 3 forming a classification chamber 9, a grinding table 6 accommodated in the lower part of the housing and rotated and driven, a plurality of roller pressure devices 12 each for pressing the pressure roller 16 to the grinding table to grind coal on the grinding table, and a coal supply pipe 23 vertically installed in the center of the housing for supplying lump coal between the pressure rollers of the grinding table. <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.

  The vertical mill has a crushing table that rotates at a predetermined number of revolutions, and a pressure roller that is pressed against the crushing table, and in the crushing table, lump coal is fed from a coal supply pipe to the center of the crushing table. Dropped and supplied. The supplied massive coal moves to the outer periphery by the rotational centrifugal force of the grinding table.

  In the process of moving the coal to the outer periphery of the pulverizing table, the coal is pulverized by being caught between the pressure roller and the pulverizing table. The pulverized pulverized coal rises from the primary air blowout port around the pulverization table, and is supplied to the burner together with the primary air.

  As described above, the lump coal supplied to the crushing table is supplied to the center of the crushing table and is engaged with the pressure roller and crushed in the process of moving to the outer periphery by centrifugal force. All of the lumped coal is not immediately caught by the pressure roller, part of it jumps on the table, passes between the pressure rollers, or smoothly moves to the outer periphery of the grinding table. Failure to do so causes a time delay between supply and pulverization, that is, a reduction in the biting rate. Furthermore, the reduction in the biting rate causes a reduction in the grinding efficiency.

  The pulverization layer formed on the pulverization table functions as a buffer. When the pulverization layer is thin, self-excited vibration of the pressure roller is generated. Or since the biting of massive coal is reduced, the particle size of the pulverized layer is uniform, and self-excited vibration is likely to occur.

  Accordingly, the reduction of the biting rate decreases the pulverization efficiency, and further the self-excited vibration of the pressure roller is likely to occur. When the self-excited vibration is generated, the pulverization efficiency is remarkably reduced.

JP 2007-7594 A

  In view of such a situation, the present invention improves the biting rate of coal supplied in a vertical mill, improves the pulverization efficiency, and suppresses self-excited vibration.

  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. The present invention relates to a vertical mill that includes a roller pressure device and a coal supply pipe that supplies massive coal between the pressure rollers of the crushing table.

  According to the present invention, the coal supply pipe is provided vertically at the center of the housing, the lower end portion of the coal supply pipe branches into a plurality of coal supply branch pipes, and the lower end portion of the coal supply branch pipe is the pressurizing member. A vertical mill that opens between a roller and a pressure roller; and the coal supply pipe relates to a vertical mill that is provided to penetrate between the roller pressure devices of the housing, and the crushing The present invention relates to a vertical mill in which a jump preventing member that bounces off massive coal that has jumped on a table is disposed between the roller pressurizing devices, and the shaft center of the lower end of the coal supply branch pipe is the press roller This relates to a vertical mill inclined toward the biting position.

  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. Since it has a plurality of roller pressurizing devices and a coal supply pipe for supplying the bulk coal between the pressure rollers of the grinding table, the supplied bulk coal is immediately crushed by the pressure roller and bitten The rate and the pulverization efficiency can be improved, and the bulk coal is supplied so as to be directly bitten by the pressure roller, so that self-excited vibration is suppressed.

  According to the invention, the coal supply pipe is provided vertically in the center of the housing, the lower end of the coal supply pipe branches into a plurality of coal supply branch pipes, and the lower end of the coal supply branch pipe is Since it opens between the pressure roller and the pressure roller, and the coal supply pipe is provided so as to penetrate between the roller pressure devices of the housing, lump coal is directly placed on the grinding table. It becomes possible to supply.

  Further, according to the present invention, since the jump preventing member that repels the bulk coal jumped from the grinding table is disposed between the roller pressurizing devices, the bulk coal jumped from the grinding table is immediately added. By being caught by the pressure roller, the biting rate can be improved and the pulverization efficiency can be improved.

  Further, according to the present invention, the shaft center at the lower end of the coal supply branch pipe is inclined toward the pressure roller engagement position, so that the supplied massive coal is more easily engaged with the pressure roller. Excellent effects such as improvement of biting rate can be achieved.

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

  1 and 2 are schematic views showing an example of a vertical mill 1 in which the present invention is implemented.

  A cylindrical housing 3 is erected on a base 2 having a hollow structure or a leg structure, and a coal feeder 4 is provided on the upper side of the housing 3.

  A table driving device 5 is accommodated in the base 2, and the crushing table 6 is rotated at a constant speed or a variable speed by the table driving device 5. The crushing table 6 is housed in the lower part of the housing 3, the upper end of the base 2 and the lower end of the housing 3 are partitioned, and a primary air chamber 7 is formed around the crushing table 6, A classification chamber 9 is provided above the grinding table 6 inside the housing 3.

  A primary air supply port 8 is attached to the lower portion of the housing 3, and the primary air supply port 8 communicates with the primary air chamber 7. An air port 11 is formed around the pulverizing table 6, and the air port 11 communicates with the primary air supply port 8 and the classification chamber 9 and functions as a primary air outlet.

  In the lower part of the housing 3, a plurality of, for example, three sets of roller pressurizing devices 12 penetrating radially are provided, and the roller pressurizing devices 12 are provided at intervals of 120 ° and are mainly pressurizing cylinders. The pressure roller unit 15 is rotatable up and down about a cylinder 13 and a horizontal shaft 14, and the pressure roller unit 15 further includes a pressure roller 16 that is rotatable. A coal shield (coal collision plate) 19 is provided on the lower surface of the pressure roller unit 15 at a position facing the air port 11, and the coal shield 19 has an inclined surface that is separated from the horizontal plane toward the center. ing. The call shield 19 collides with coal blown up with the primary air passing through the air port 11, and has a function of returning massive coal onto the crushing table 6, and the call shield 19 has the pressure roller unit 15. Coal collision is prevented, and wear of the pressure roller unit 15 is prevented.

  A table segment 17 that forms a recess on the ring is provided on the upper surface of the grinding table 6, and the pressure roller 16 is pressed against the recess of the table segment 17 by the pressure cylinder 13.

  The jump preventing plate 18 does not interfere with a coal supply branch pipe 28 to be described later at a required position of the inner wall of the housing 3, a position where the circumference is equally divided into three in the drawing (an intermediate position between the roller pressure devices 12, 12). Provided. The jump prevention plate 18 is supported by a support plate 21 attached to the inner wall of the housing 3. The support plate 21 has a plate shape and is provided vertically so as not to hinder the flow of primary air that passes through the air port 11 and blows up.

  The jump prevention plate 18 is a rectangular plate having a horizontal length that substantially closes the gap between the pressure rollers 16 and 16, and is inclined so that the upper end is tilted toward the center side. The massive coal that collides with the jump prevention plate 18 is effectively dropped onto the table segment 17. In addition, since it is sufficient to rebound the lump coal to the table segment 17, it may be vertical without being inclined.

  Further, the lower end of the jump preventing plate 18 is located at least on the center side with respect to the air port 11 and has a gap between the upper surface of the crushing table 6.

  The coal feeder 4 is connected to a coal outlet housing 22 and a pipe-shaped coal feeder pipe 23 that penetrates the coal outlet housing 22 and extends into the housing 3.

  The lower end of the coal output housing 22 is open and communicates with the classification chamber 9. In addition, a pulverized coal feed pipe 24 is connected to the coal outlet housing 22, and the pulverized coal feed pipe 24 is connected to a burner (not shown) of a boiler. The coal supply pipe 23 is on an extension of the rotation center of the crushing table 6, and the upper end of the coal supply pipe 23 is connected to the coal feeder 4.

  The lower portion of the coal supply pipe 23 is branched into three coal supply branch pipes 28, and the lower end of the coal supply branch pipe 28 is positioned between the pressure rollers 16 and 16, and the table segment 17 A gap is formed between the lower end of the coal supply branch pipe 28 and the upper surface of the table segment 17, and the gap is a crushing layer formed on the table segment 17. The thickness is further greater than the maximum thickness so that the lower end of the coal supply branch pipe 28 does not contact the pulverized layer.

  A classifier 26 is provided in the middle of the coal supply pipe 23, and the classifier 26 is located above the classifying chamber 9 and is adjacent to the lower end opening of the coal outlet housing 22. The classifier 26 is connected to the rotation drive unit 25 and is rotated by the rotation drive unit 25.

  In the classifier 26, strip-shaped blades 27 are arranged at a required pitch in the circumferential direction and supported by the coal supply pipe 23, and the blades 27 rotate on the circumference. .

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

  The pulverizing table 6 is rotated by the table driving device 5, and lump coal is supplied from the coal feeder 4 to the coal supply pipe 23 in a state where primary air is introduced from the primary air supply port 8. The

  The massive coal that has flowed down the coal supply pipe 23 is branched by the coal supply branch pipes 28, flows down the respective coal supply branch pipes 28, and falls between the pressure rollers 16 and 16 of the table segment 17. To do.

  The massive coal that has fallen immediately before the pressure roller 16 is immediately caught by the pressure roller 16 and crushed.

  The coal pulverized by the pressure roller 16 becomes powdery, and the powdered coal rises on the primary air blowing up the air port 11.

  Further, when falling, the lump of coal that bounces on the crushing table 6 and tries to jump over the crushing table 6 is bounced by the jumping prevention plate 18 and returned to the crushing table 6 to be crushed immediately. Is done. Accordingly, the time from when the massive coal is supplied from the coal supply branch pipe 28 to the pulverization table 6 and caught by the pressure roller 16 is remarkably shortened, and the biting rate is improved.

  In addition, the massive coal is directly supplied to the biting position of the pressure roller 16, and the pressure roller 16 is always in a state of pulverizing the massive coal, so that the self-excited vibration of the pressure roller 16 is generated. Is suppressed.

  The pulverized coal passes between the upper surface of the pulverization table 6 and the jump prevention plate 18 and rises on the primary air blowing up the air port 11 (hereinafter referred to as primary). Called mixed air). As described above, at least the outer end of the jump preventing plate 18 is located inside the air port 11 so as not to disturb the flow of primary mixed air, and the support plate 21 that supports the jump preventing plate 18 is also provided. Moreover, it is provided vertically so as not to obstruct the flow of the primary mixed air.

  The primary mixed air blown up from the air port 11 at the portion facing the call shield 19 collides with the call shield 19, and among the pulverized coal in the primary mixed air, the one having a large particle diameter is pulverized. It falls on the table 6 and is further pulverized.

  Therefore, the lump coal that has jumped over the crushing table 6 is returned to the crushing table 6 by the jump prevention plate 18 and pulverized, and the particle size of the powdered coal in the primary mixed air is reduced. Are separated by the call shield 19, so that classification is performed more quickly and efficiently than classification by gravity in the process of ascending the classification chamber 9.

  The raised primary mixed air flows into the classifier 26 across the blade 27 rotating around the coal supply pipe 23, and further from the lower end opening of the coal output portion housing 22. 22 flows into the interior.

  When the primary mixed air crosses the blade 27, the coal powder having a large particle size collides with the blade 27 and falls. Only pulverized coal with a small particle diameter rides on the primary mixed air and flows into the classifier 26, and further through the coal outlet housing 22, is discharged from the pulverized coal feed pipe 24, and the boiler burner ( (Not shown).

  Next, the shape of the lower end portion of the coal supply branch pipe 28 will be described.

  FIG. 3A shows a horizontal cut at the lower end of the coal supply branch pipe 28. FIG. 3 (B) shows the bottom end of the coal supply branch pipe 28 inclined so that the center side is separated from the pulverizing table surface, and the pipe wall 28a on the outer peripheral side is vertical, and the flowed-down lump-like shape. The coal collides with the pipe wall 28a and falls vertically. FIG. 3C shows a case where the lower end portion of the coal supply branch pipe 28 is curved so that the axial center at the lower end is vertical or substantially vertical.

  By making the lower end portion of the coal supply branch pipe 28 as shown in FIGS. 3 (B) and 3 (C), falling lump coal falls vertically, and jumping in the outer peripheral direction can be prevented. Further, if the shaft center of the lower end portion of the coal supply branch pipe 28 is inclined so as to incline toward the biting position of the pressure roller 16, the lump coal is dropped toward the biting position. Biting property is improved.

  As a method for supplying coal between the pressure rollers 16 and 16, a coal supply pipe penetrating the housing 3 in the horizontal direction is provided between the roller pressure devices 12 and 12, and a screw feeder or the like. You may make it supply lump coal with the supply apparatus of.

  The illustrated coal supply branch pipe 28 has three branches. However, when the number of the pressure rollers 16 is two, the number of the pressure rollers 16 may be branched. To.

It is an elevation sectional view showing an embodiment of the invention. It is A arrow directional view of FIG. (A) (B) (C) is explanatory drawing which shows the shape of a coal-feeding branch pipe lower end part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical mill 5 Table drive device 6 Grinding table 8 Primary air supply port 9 Classification chamber 11 Airport 12 Roller pressurization device 16 Pressurization roller 18 Jump prevention plate 19 Call shield 22 Carburization part housing 23 Coal supply pipe 24 Fine powder Charcoal feed pipe 25 Rotation drive part 26 Classifier 28 Coal feed branch pipe 28a Pipe wall

Claims (5)

  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 feed pipe for supplying the bulk coal between the pressure rollers of the crushing table.   The coal supply pipe is vertically provided at the center of the housing, and a lower end portion of the coal supply pipe branches into a plurality of coal supply branch pipes, and a lower end portion of the coal supply branch pipe includes the pressure roller and the pressure roller. The vertical mill according to claim 1, which opens between the two.   The vertical mill according to claim 1, wherein the coal supply pipe is provided so as to penetrate between the roller pressing devices of the housing.   The vertical mill according to claim 1, wherein a jump preventing member that repels the massive coal that has jumped on the crushing table is disposed between the roller pressure devices.   The vertical mill according to claim 2, wherein an axis of a lower end of the coal supply branch pipe is inclined toward a biting position of the pressure roller.

Images