JP5573078B2 - Vertical mill - Google Patents

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.

  First, referring to FIG. 4, an outline of a conventional vertical mill 1 will be described.

  A crushing table 2 for crushing coal is erected via a table driving device (not shown), and the crushing table 2 is rotated at a constant speed by the table driving device.

  Above the crushing table 2, a plurality of pressure roller units 4 each having a pressure roller 3 are provided radially from the rotation center of the crushing table 2, for example, three at intervals of 120 °. 3 is pressed onto the crushing table 2 by a roller pressure device (not shown).

  A primary air chamber 5 is formed below the pulverizing table 2, and a classification chamber 6 is formed above the pulverizing table 2. A primary air blowing port 7 is provided around the pulverizing table 2 over the entire circumference, and the blowing port 7 communicates the primary air chamber 5 and the classification chamber 6.

  The primary air chamber 5 is provided with a primary air supply port (not shown). The primary air supply port is connected to a primary air supply means (not shown) and communicates with the primary air chamber 5. ing.

  During the coal pulverization process, lump coal is dropped from the coal supply device (not shown) onto the center of the pulverization table 2, and the pulverization table 2 is rotated by the table driving device, and the primary air supply port (not shown) The supplied primary air is discharged from the outlet 7 to the classification chamber 6 through the primary air chamber 5.

  The pressure roller 3 is rotatable and is driven to rotate by the crushing table 2. The coal dropped on the crushing table 2 moves in the outer circumferential direction by the rotation of the crushing table 2, It is pulverized by being bitten by the pressure roller 3.

  The pulverized coal particles are further moved in the outer peripheral direction by the rotation of the pulverizing table 2, and are blown upward by the primary air ejected at a high speed from the blowout port 7, and are shown in the figure through the classification chamber 6. It is fed to the boiler from the feed pipe that does not.

  However, the coal particles blown up from below the pressure roller unit 4 collide with the pressure roller unit 4 at a high speed and wear the pressure roller unit 4.

  As a means for solving the above problem, there is one in which a plate-like call shield 8 inclined inward as shown in FIG. 4 is provided at a position directly above the outlet 7 at the lower part of the pressure roller unit 4. .

  The call shield 8 is configured to flip coal particles blown from below the pressure roller unit 4 in the direction of the crushing table 2, and the coal particles collide with the pressure roller unit 4, The pressure roller unit 4 is prevented from being worn.

  However, in the case where the call shield 8 is provided below the pressure roller unit 4, the coal particles that have lost their place due to collision with the call shield 8 are caused by the inner wall surface of the vertical mill 1 and the outlet 7. The inner wall surface of the vertical mill 1 is worn. Further, it is inevitable that the call shield 8 itself wears due to the collision between the call shield 8 and the coal particles, and it is necessary to replace the call shield 8 according to the wear state.

JP-A-10-28890

  In view of such circumstances, the present invention provides a vertical mill that blocks primary air blown from below the pressure roller unit and prevents wear of the pressure roller unit and the inner wall surface.

  The present invention includes a housing forming a classification chamber, a pulverizing table housed in a lower part of the housing and driven to rotate by a table driving device, and a pressure roller unit having a pressure roller pressed against the pulverizing table, A plurality of roller pressurizing devices for crushing a lump on the crushing table, a primary air chamber formed below the crushing table and into which primary air is introduced, and the primary air from the periphery of the crushing table A blower outlet for blowing the primary air of the chamber; and a coal supply device for supplying a lump to the pulverization table. A shielding member is provided below the pressure roller unit, and the pressure roller is provided by the shielding member. The present invention relates to a vertical mill that blocks the blowout port below the unit and prevents the primary air from being blown out from the blowout port.

  Further, the present invention relates to a vertical mill provided in the classification chamber so as to cover the upper end of the outlet, and the shielding member closes the lower end of the outlet. This relates to a vertical mill provided in the secondary air chamber.

  According to the present invention, a pressure roller unit having a housing forming a classification chamber, a crushing table housed in a lower portion of the housing and driven to rotate by a table driving device, and a pressure roller pressed against the crushing table. A plurality of roller pressurizing devices for crushing the lump on the crushing table, a primary air chamber formed below the crushing table, into which primary air is introduced, and the first from the periphery of the crushing table. A blow-out port for blowing out primary air in the secondary air chamber; and a coal feeder for supplying a lump to the pulverization table. A shielding member is provided below the pressure roller unit, and the shielding member is used to Since the blowout port below the pressure roller unit is blocked to prevent the primary air from being blown from the blowout port, an upward flow of primary air is generated below the pressure roller unit. Without upflow be clot in the primary air collides with the pressure roller unit, is not to wear the pressure roller unit. In addition, the lump that collides with the pressure roller unit and loses its place does not damage the inner wall surface of the housing.

  According to the invention, since the shielding member is provided in the classification chamber so as to cover the upper end of the outlet, the primary air blocked by the shielding member is deflected toward the pulverization table. The lump that is blown up by the primary air collides with the shielding member and wears the shielding member without the lump being entered between the shielding member and the crushing table by the deflected primary air. There is no.

  Furthermore, according to the present invention, since the shielding member is provided in the primary air chamber so as to close the lower end of the outlet, the position of the shielding member is more than that of the pulverizing table on which the lump is pulverized. Also, the lump that is blown up by the primary air does not collide with the shielding member, and exhibits an excellent effect that the shielding member does not wear due to the collision.

1 is a schematic elevation view of a vertical mill in a first embodiment of the present invention. It is a principal part expanded sectional view of the vertical mill in the 1st example of the present invention. It is a principal part expanded sectional view of the vertical mill in the 2nd example of the present invention. It is a principal part expanded sectional view of the conventional vertical mill.

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

  First, referring to FIG. 1 and FIG. 2, a first embodiment of the present invention will be described. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted.

  A sealed space is formed by a housing 11 erected on the base 9, and a pulverization table 2 is erected at a lower part of the space via a table driving device 12, and the pulverization table 2 is connected to the table driving device 12. Is rotated at a constant speed. Further, a table segment 14 having a concave groove 13 having a circular cross section is provided on the upper surface of the grinding table 2.

  Three sets of pressure roller units 4 are provided above the crushing table 2, and the pressure roller unit 4 has the pressure roller 3 and is tiltable about a horizontal support shaft 15. In addition, three sets of roller pressing devices 16 that radiately penetrate the housing 11 are provided at the lower portion of the housing 11. The roller pressure device 16 is supported by a journal cover 17 provided under the housing 11 and includes an actuator, for example, a hydraulic cylinder 18. The hydraulic cylinder 18 presses the pressure roller 3 against the concave groove 13. It is supposed to do.

  A primary air chamber 5 is formed below the grinding table 2, and a classification chamber 6 is located above the grinding table 2 inside the housing 11. A primary air supply port 19 communicates with a lower portion of the housing 11, and an air port ring 21 is fixed to a position of the housing 11 facing the pulverization table 2 by welding or the like. Concave portions are engraved in the peripheral edge portion of the pulverizing table 2 over the entire circumference at predetermined intervals, and a blowout port 7 is formed by the concave portion and the air port ring 21.

  Further, below each pressure roller unit 4, a shielding plate 22, which is a shielding member, is fixed to the journal cover 17 so as to be perpendicular to the outlet 7, and the shielding plate 22 is attached to the outlet 7. Covering. A slight gap is formed between the shielding plate 22 and the crushing table 2 and the outlet 7, and the tip of the shielding plate 22 extends inward from the inner edge of the outlet 7, The front end of the shielding plate 22 is bent downward along the surface of the concave groove 13. Further, the shielding plate 22 blocks the primary air blown up from the outlet 7, and the blocked primary air is deflected by the tip of the shielding plate 22 and blown onto the concave groove 13. It has become.

  The shielding plate 22 may have a triangular cross section so that pulverized coal does not accumulate on the upper surface of the shielding plate 22. In this case, since the shielding plate 22 vibrates as it is pulverized, the angle of the inclined surface may be small, but is preferably greater than the repose angle of pulverized coal.

  A coal supply / discharge portion 23 is provided on the upper side of the housing 11, and a pipe-like chute 24 is provided so as to penetrate the central portion of the coal supply / discharge portion 23. It extends inside. The chute 24 is supplied with coal, and the supplied coal falls on the crushing table 2.

  A classifier 25 is rotatably provided in the middle of the chute 24. The classifier 25 has strip-shaped blades 26 arranged at a required pitch in the circumferential direction, and the classifier 25 is a rotation drive unit. 27 to be rotated.

  The coal supply / discharge section 23 is connected to a burner (not shown) of a boiler for supplying pulverized coal supply pipes 28 for supplying pulverized coal particles.

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

  The pulverizing table 2 is rotated by the table driving device 12, and lump coal is introduced from the chute 24 in a state where primary air is introduced into the primary air chamber 5 from the primary air supply port 19. The The massive coal flows from the lower end of the chute 24 to the center of the crushing table 2 and is supplied onto the crushing table 2.

  The coal on the crushing table 2 moves in the outer peripheral direction by centrifugal force, is pulverized by being pressed by the pressure roller 3, and further overflows from the table segment 14 to the outer periphery by the centrifugal force. Rides on the primary air blown up from the outlet 7 and rises along the wall surface of the housing 11 in the outer peripheral portion of the classification chamber 6.

  The coal particles rising on the wall surface of the housing 11 are classified by the classifier 25, and coal particles smaller than a predetermined size are sent out from the pulverized coal feed pipe 28 and supplied to a burner of a boiler (not shown). Coal particles that are larger than the size of the above are repelled by the blade 26 or fall on the crushing table 2 again by their own weight.

  During the processing, the primary air blown up from the outlet 7 below the shielding plate 22 is blocked by the shielding plate 22. The gap between the shielding plate 22 and the pulverizing table 2 should be as small as possible.

  Below the pressure roller unit 4, since the primary air is blocked by the shielding plate 22, there is no jet of primary air from the outlet 7, and the coal particles blown up to the primary air are There is no collision with the pressure roller unit 4. Further, coal particles that have lost their place by colliding with the pressure roller unit 4 or the call shield 8 (see FIG. 4) do not wear the inner wall surface of the housing 11.

  Further, since the gap between the shielding plate 22 and the crushing table 2 is small, and the primary air deflected in the horizontal direction is blown out from the front end portion of the shielding plate 22, the crushing table 2. Among the coals moved by the centrifugal force, those having a large particle size cannot enter between the shielding plate 22 and the crushing table 2, and those having a small particle size are also the tip of the shielding plate 22. It is blown off by the primary air blown out more and does not enter between the shielding plate 22 and the crushing table 2.

  Accordingly, the coal particles blown up by the primary air collide with the shielding plate 22 and the shielding plate 22 is not worn, so that it is not necessary to periodically replace the shielding plate 22.

  Next, a second embodiment of the present invention will be described with reference to FIG. 3 that are the same as those in FIGS. 1 and 2 are given the same reference numerals, and descriptions thereof are omitted.

  In this embodiment, instead of the shielding plate 22 of the first embodiment, a plate-like closing plate 29 which is a shielding member is provided.

  The closing plate 29 is positioned below the pressure roller unit 4 and is provided so as to be horizontal in the primary air chamber. The front end of the closing plate 29 extends inward from the inner edge of the outlet 7, and the closing plate 29 substantially closes the lower end of the outlet 7, and is introduced from the primary air supply port 19. Air is prevented from flowing into the outlet 7 below the pressure roller unit 4.

  In the vertical mill 1 having the above-described configuration, during the coal pulverization process, the primary air supplied from the primary air supply port 19 to the primary air chamber 5 is blocked by the blocking plate 29, Since it does not flow into the outlet 7 below the pressure roller unit 4, no upward flow of primary air occurs below the pressure roller unit 4, and coal particles are blown up to the primary air, Coal particles that prevent wear of the pressure roller unit 4 due to collision with the pressure roller unit 4 and that have lost their place by collision with the pressure roller unit 4 or the call shield 8 (see FIG. 4). The wear of the inner wall surface of the housing 11 can be prevented.

  Further, since the closing plate 29 is positioned below the crushing table 2, the coal particles crushed by the pressure roller 3 are blown up by primary air below the pressure roller unit 4. There is nothing. Therefore, coal particles do not collide with the blocking plate 29 and wear the blocking plate 29, and it is not necessary to replace the blocking plate 29 periodically.

  A plurality of small pulverized coals that have fallen to the outlet 7 are blown into the closing plate 29 so that the pulverized coal is blown up by primary air when the outlet 7 is removed from the closing plate 29 by the rotation of the crushing table 2. A hole may be drilled and a floating layer of pulverized coal may be formed by the primary air blown from the small hole.

  In addition, although the said Example demonstrated the vertical mill 1 which grind | pulverizes massive coal, it cannot be overemphasized that this invention can be implemented also with respect to grinding | pulverization of massive objects, such as limestone.

DESCRIPTION OF SYMBOLS 1 Vertical mill 2 Crushing table 3 Pressure roller 4 Pressure roller unit 5 Primary air chamber 6 Classification chamber 7 Outlet 11 Housing 22 Shielding plate 29 Closure plate

Claims (3)

A housing forming a classification chamber, a pulverizing table housed in the lower part of the housing and driven to rotate by a table driving device , a concave groove formed on the upper surface of the pulverizing table , and a pressure applied to the concave groove A pressure roller unit having a roller, a plurality of roller pressure devices for pulverizing a lump on the pulverization table, a primary air chamber formed below the pulverization table and into which primary air is introduced, and A blowout port for blowing out primary air from the primary air chamber from the periphery of the crushing table; and a coal feeder for supplying a lump to the crushing table; and the crushing table below the pressure roller unit ; A shielding member is provided so that a slight gap is formed between the tip and the shielding member. Concave Is bent downward along the surface, and wherein the shield member intercepts the air outlet of the pressure roller unit downward blowing primary air which is deflected by the distal end portion of the shield member on the groove A vertical mill.   The vertical mill according to claim 1, wherein the shielding member is provided in the classification chamber so as to cover an upper end of the outlet.   The saddle type mill according to claim 1 or 2, wherein the shielding member has a triangular cross-sectional shape, and the angle of the inclined surface of the shielding member is equal to or greater than the repose angle of the crushed lump.

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