JPH08196924A - Vertical roller mill - Google Patents

Abstract

PURPOSE: To crush securely rough powder, prevent the slip of a crushing roller and improve the crushing efficiency by crushing the rough powder repelled by a classifier separately from raw coal at an exclusive crushing section. CONSTITUTION: A slit opening section 17' for passing powder 12 crushed by a crushing roller 11 and blown up and guiding the powder to a classifier 19 is formed, and a reject chute 15' for guiding rough powder repelled down by the classifier 19 to above the outer peripheral position of a crushing table 9 is formed in a mill casing table 7. An auxiliary crushing ring seat 22 protruding to the central side with downward gradient and having a passing opening 21 for the rough powder guided above the outer peripheral position of the crusing table 9 by a reject chute 15' bored on is fitted on the inner peripheral face of a mill casing 7, and an auxiliary crushing ring 23 with its upper face pressed to the lower face of the auxiliary crushing ring seat 22 and grinding the rough powder passing through the passing opening 21 is set on the outer peripheral edge of the crushing table 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical roller mill.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a vertical roller mill 1 provided in a coal-fired boiler or the like.
As shown in the figure, a coal feeder 5 that allows the coal 3 of the coal bunker 2 to be adjusted by a coal feeder motor 4
Is to be charged into the mill casing 7 via the coal feeding pipe 6, and the coal 3 charged from the coal feeding pipe 6
Is rotatably driven through a speed reducer 8 connected to an electric motor, and the crushing device 10 is pressed against the upper surface of the crushing table 9 by a reduction device 10 and rolls following the rotation of the crushing table 9. The roller 11 is crushed.

The powder 12 produced by the pulverization is blown up in the mill casing 7 by the primary air 14 for conveyance from the blowout port 13 provided in an annular shape so as to surround the pulverization table 9, and the mill casing 7 is blown up. 7 is conveyed upward through a slit opening 17 formed by bulging an outer edge portion 16 of a cut formed in a plurality of circumferential positions of a funnel-shaped reject chute 15 that divides the inside into upper and lower portions, and is guided further upward. The powder 12 is guided to and classified by a rotary classifier 19 which is provided in an upper portion inside the mill casing 7 and is rotationally driven by a classifier motor 18, and only fine powder having a predetermined particle size or less is milled in the mill casing 7.
The powder is supplied to a burner such as a coal-fired boiler (not shown) through a fine powder delivery pipe 20 connected to the top.

The coarse powder repelled by the classifier 19 slides down the inclined surface between the slit openings 17 of the reject chute 15 and is returned from the lower end of the reject chute 15 to the center of the crushing table 9 to feed the coal. It is designed to be crushed together with the coal 3 (raw coal) charged from the pipe 6.

[0005]

However, the grain size of the raw coal fed from the coal feeding pipe 6 is about 50.
On the other hand, the particle size of the coarse powder repelled by the classifier 19 is about 0.5 mm at the maximum, and there is a large difference in particle size between the two. When the coarse powder returned to the crushing table 9 through the reject chute 15 is crushed together with the raw coal fed from the coal feeding pipe 6, the pressing force (crushing force) of the crushing roller 11 has a large particle size. It will be used for crushing raw coal,
Coarse powder having a relatively small particle size has a drawback in that it is difficult to pulverize the coarse powder further, and the coarse powder also causes a slip of the pulverizing roller 11, so that the pulverization efficiency is lowered.

In view of the above situation, the present invention can surely pulverize the coarse powder by pulverizing the coarse powder repelled by the classifier separately from the raw coal in a dedicated pulverizing section. An object of the present invention is to provide a vertical roller mill which can prevent slipping of a crushing roller and can improve crushing efficiency.

[0007]

According to the present invention, there is provided a crushing table rotatably disposed at the inner bottom of a mill casing, and a rolling device which follows the rotation of the crushing table while being pressed against the upper surface of the crushing table by a rolling down device. Between the crushing roller and the crushing roller, which is arranged in the upper part of the mill casing, and a coal feeding pipe for feeding the coal supplied from the coal feeder to the crushing table in the mill casing at a substantially central portion. In a vertical roller mill equipped with a classifier that guides only the fine powder having a predetermined particle size or less out of the powder crushed and blown up to And a crushing roller, and has a slit opening portion that passes the powder pulverized and blown up and leads to the classifier,
And a reverse funnel-shaped reject chute that guides the coarse powder blown off by the classifier to the upper side of the outer peripheral position of the pulverizing table, is provided between the pulverizing table and the pulverizing roller inside the mill casing, and the classifier, On the inner peripheral surface of the mill casing above the outer peripheral position of the crushing table, there is a passage through which coarse particles pass toward the center of the mill casing with a downward slope and which is guided upward by the reject chute to the outer peripheral position of the pulverizing table. A perforated auxiliary crushing annular seat is provided, and an auxiliary crushing ring whose upper surface is pressed against the lower surface of the auxiliary crushing annular seat and which grinds coarse powder passing through the passage hole is provided at the outer peripheral edge of the crushing table. It is characterized by that.

[0008]

Therefore, the coal charged into the mill casing by the coal feeder through the coal feeding pipe is rotated by the upper surface of the crushing table which is rotationally driven and the upper surface of the crushing table while being pressed against the upper surface of the crushing table by the reduction device. The powder generated by the crushing is crushed between the crushing roller and the crushing roller which rolls along with the crushing roller. The powder introduced to (1) is introduced into a classifier and classified, and only fine fine particles having a predetermined particle size or less are introduced into the fine powder delivery pipe.

On the other hand, the coarse powder repelled by the classifier is
The inclined surface between the slit openings of the reject chute slides down and is guided onto the auxiliary crushing annular seat, and falls from the passage hole of the auxiliary crushing annular seat between the auxiliary crushing ring upper surface and the auxiliary crushing annular seat lower surface. To be ground.

The fine powder crushed between the upper surface of the auxiliary crushing ring and the lower surface of the auxiliary crushing annular seat is blown in the mill casing together with the powder crushed between the upper surface of the crushing table and the crushing roller. Raised and conveyed upward through the slit opening of the inverted funnel-shaped reject chute,
The same operation as described above is repeated.

As a result, the coarse powder repelled by the classifier is
It is not crushed together with the raw coal fed from the coal feeding pipe, the coarse powder is crushed surely, and the crushing roller does not slip.

[0012]

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

1 to 3 show one embodiment of the present invention,
In the figure, the parts denoted by the same reference numerals as those in FIG. 4 represent the same parts, and pass the powder 12 crushed and blown up between the crushing table 9 and the crushing roller 11 to the classifier 19. A reverse funnel-shaped reject chute 15 ′ having a slit opening 17 ′ and guiding coarse powder blown off by the classifier 19 to above the outer peripheral position of the crushing table 9 is provided in the crushing table 9 inside the mill casing 7 and Crushing roller 1
It is arranged between 1 and the classifier 19. The slit opening 17 'is formed by bulging an outer edge portion 16' of a notch formed at a plurality of circumferential positions of the reject chute 15 '.

Further, on the inner peripheral surface of the mill casing 7 above the outer peripheral position of the crushing table 9, it projects toward the center of the mill casing 7 with a downward slope and is guided to above the outer peripheral position of the crushing table 9 by the reject chute 15 '. An auxiliary crushing annular seat 22 having a passage 21 for passing the coarse powder is provided at a required position, and the upper surface is pressed against the lower surface of the auxiliary crushing annular seat 22 and passes through the outer peripheral edge of the crushing table 9. An auxiliary crushing ring 23 for crushing the coarse powder passing through the hole 21 is provided.

In the present embodiment, an auxiliary crushing section 25 having an inclined surface 24 following the inclination of the lower surface of the auxiliary crushing annular seat 22 is integrally formed on the outer periphery of the crushing table 9, and the auxiliary crushing section 25 is provided with the auxiliary crushing section 25. An annular groove 26 for fitting the auxiliary crushing ring 23 is formed, and a blowout port 13 for the primary air 14 is bored. Inside the annular groove 26, an elastic body 27 such as a spring or rubber is interposed. The auxiliary grinding ring 2
3, the upper surface of the auxiliary crushing ring 23 is pressed against the lower surface of the auxiliary crushing annular seat 22.

On the upper surface of the auxiliary crushing ring 23,
The auxiliary crushing annular seat 22 is formed with an introducing inclined portion 28 slightly looser than the lower surface of the auxiliary crushing annular seat 22 and a crushing sliding portion 29 which is substantially equal to the inclination of the lower surface of the auxiliary crushing annular seat 22.
The coarse powder from the passage hole 21 is surely introduced between the crushing sliding portion 29 of the auxiliary crushing ring 23 and the lower surface of the auxiliary crushing annular seat 22 via the introducing inclined portion 28.

Furthermore, the annular groove 26 of the auxiliary crushing section 25
A small amount of primary air 14 is inserted into the annular groove 2 in the insertion block 30 that is detachably fitted to the lower side of the annular groove 26 and used to replace the elastic body 27 filled in the annular groove 26.
6 is formed with a communication hole 31 for leading to 6, and the pressure in the annular groove 26 filled with the elastic body 27 is slightly increased, whereby fine powder enters the gap between the auxiliary crushing ring 23 and the annular groove 26, and This prevents clogging and obstructs the pressing of the auxiliary crushing ring 23 against the auxiliary crushing annular seat 22.

Next, the operation of the above embodiment will be described.

The coal 3 charged into the mill casing 7 through the coal feeding pipe 6 by the coal feeder 5 is brought into pressure contact with the upper surface of the crushing table 9 which is rotationally driven and the upper surface of the crushing table 9 by the pressure reducing device 10. Meanwhile, the powder 12 crushed by the crushing roller 11 which rolls following the rotation of the crushing table 9 and generated by the crushing is blown up in the mill casing 7 by the primary air 14 from the blowout port 13, Reverse funnel-shaped reject chute 15 'slit opening 1
The powder 12 conveyed upward through 7'and guided further upward is guided to a classifier 19 which is rotationally driven and classified, and only fine powder having a predetermined particle size or less is connected to the top of the mill casing 7. It is supplied to a burner (not shown) such as a coal-fired boiler via the fine powder delivery pipe 20.

On the other hand, the coarse powder repelled by the classifier 19 is the slit opening 1 of the reject chute 15 '.
The slanted surface between 7'slides down and is guided onto the auxiliary crushing annular seat 22, and falls from the passage hole 21 of the auxiliary crushing annular seat 22 between the upper surface of the auxiliary crushing ring 23 and the lower surface of the auxiliary crushing annular seat 22. To be ground.

Here, on the upper surface of the auxiliary crushing ring 23, an introducing inclined portion 28 which is slightly looser than the inclination of the lower surface of the auxiliary crushing annular seat 22 and a crushing sliding portion which is substantially equal to the inclination of the lower surface of the auxiliary crushing annular seat 22. 29 is formed, the coarse powder from the passage hole 21 of the auxiliary crushing annular seat 22 is formed into the introduction inclined portion 2
8 is reliably introduced between the crushing sliding portion 29 of the auxiliary crushing ring 23 and the lower surface of the auxiliary crushing annular seat 22, and the fitting block 30 has a small amount of primary air 14
Since the communication hole 31 that guides the ring to the annular groove 26 is formed and the pressure in the annular groove 26 filled with the elastic body 27 is slightly increased, a gap is formed between the auxiliary crushing ring 23 and the annular groove 26. The fine powder does not enter and cause clogging, and the pressing of the auxiliary crushing ring 23 against the auxiliary crushing annular seat 22 is not hindered.

The fine powder crushed between the upper surface of the auxiliary crushing ring 23 and the lower surface of the auxiliary crushing annular seat 22 is moved between the upper surface of the crushing table 9 and the crushing roller 11 by the primary air 14 from the blowing port 13. Together with the pulverized powder 12, it is blown up in the mill casing 7 and conveyed upward through the slit opening 17 'of the reverse funnel-shaped reject chute 15', and thereafter, the same operation as described above is repeated.

As a result, the coarse powder repelled by the classifier 19 is not crushed together with the coal 3 (raw coal) fed from the coal feeding pipe 6, and the coarse powder is surely crushed. Also, the crushing roller 11 does not slip.

Thus, by crushing the coarse powder repelled by the classifier 19 in a dedicated crushing unit separately from the raw coal,
Coarse powder can be reliably crushed, and the crushing roller 1
The slip of No. 1 can be prevented, and the grinding efficiency can be improved.

The vertical roller mill of the present invention is not limited to the above-mentioned embodiment, but instead of urging the auxiliary crushing ring by the elastic body to press it against the auxiliary crushing annular seat, the auxiliary crusher is hydraulically assisted. It is also possible to urge the ring to press it against the auxiliary crushing annular seat, etc.,
Needless to say, various changes can be made without departing from the scope of the present invention.

[0026]

As described above, according to the vertical roller mill of the present invention, the coarse powder repelled by the classifier is crushed separately from the raw coal in the dedicated crushing unit to crush the coarse powder. This has an excellent effect that it can be surely performed, slip of the crushing roller can be prevented, and crushing efficiency can be improved.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is a detailed view of a portion II in FIG.

FIG. 3 is a plan view showing a part of the auxiliary crushing annular seat, which is a view corresponding to the arrow III-III in FIG.

FIG. 4 is an overall schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 1 Vertical roller mill 3 Coal 5 Coal feeder 6 Coal feeding pipe 7 Mill casing 9 Grinding table 10 Reduction device 11 Grinding roller 12 Powder 15 'Reject chute 17' Slit opening 19 Classifier 20 Fine powder delivery pipe 21 Passage hole 22 Auxiliary Grinding ring seat 23 Auxiliary grinding ring

Claims (1)

[Claims] 1. A crushing table rotatably disposed at the bottom of the mill casing, a crushing roller that rolls following the rotation of the crushing table while being pressed against the upper surface of the crushing table by a pressure reducing device, and a coal feeder. The coal feed pipe that feeds the coal supplied from the mill casing into the mill casing at approximately the center of the crushing table and the upper portion of the mill casing are crushed and blown up between the crushing table and the crushing rollers. In a vertical roller mill equipped with a classifier that guides only the fine powder of a predetermined particle size or less out of the powder to the fine powder delivery pipe and knocks down the coarse powder exceeding the predetermined particle size, it is crushed between the crushing table and the crushing roller. A reverse funnel-shaped rejector that has a slit opening for passing the powder blown up and blown to the classifier and guides the coarse powder blown off by the classifier to above the outer peripheral position of the crushing table. A chute is disposed between the crushing table and the crushing roller inside the mill casing and the classifier, and has a downward slope toward the center of the mill casing on the inner peripheral surface of the mill casing above the outer peripheral position of the crushing table. Then, an auxiliary crushing annular seat is provided in which a passage hole for the coarse powder, which is projected to the upper side of the outer peripheral position of the crushing table by the reject chute, is provided at a required location, and the outer peripheral edge of the crushing table has an upper surface with A vertical roller mill, characterized in that an auxiliary crushing ring that is pressed against the lower surface of the auxiliary crushing annular seat and grinds the coarse powder that has passed through the passage holes is provided.