JPH0642738Y2 - Vertical roller mill - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a vertical roller mill, and more particularly to a vertical roller mill configured to reduce the retention of iron particles on the upper surface of a grinding table.

[Conventional technology]

Conventionally, blast furnace slag is crushed for reuse, but crushing is generally carried by an air flow injected from a nozzle provided inside the crushed powder to carry the powder after crushing, primary classification, and further separator. It is becoming more common for vertical roller mills to select powder products.

However, when the blast furnace slag is pulverized, the iron particles contained in this blast furnace slag become a problem.

In other words, the specific gravity of iron is larger than that of the blast furnace slag itself, which contains CaO as a main component, so it is difficult for iron particles to be removed from the upper surface of the crushing table, and the iron particles stay on the upper surface of this rotary table and are gradually concentrated. As a result, the crushing roller segment and the table segment are severely worn.

Therefore, a vertical roller mill has been developed which is designed to allow the crushing work to be continued while eliminating iron particles that tend to stay on the upper surface of the rotary table.

The vertical roller mill (Japanese Patent Laid-Open No. 60-14356) as described above is shown in FIGS.
The following is introduced with reference to FIG. 8 which is a sectional view taken along the line.

That is, reference numeral (1) shown in FIG. 7 is a vertical roller mill, and this roller mill (1) is composed of a lower casing (2) and an upper casing (2a).

A rotary table (3) which is rotated around the vertical axis at a predetermined rotational speed is arranged in the center of the lower casing (2), and the upper surface of the table (3) has an outer peripheral portion with a first table. As shown in FIG. 8, an annular dam ring (4) protruding upward is formed, and the dam ring (4) is formed.
A plurality of notches (4a) are engraved on the.

Further, a plurality of crushing rollers (5) rolling while being pressed against the upper surface of the rotary table (3) are arranged. An annular nozzle (7) having a plurality of air ejection ports (6) surrounding the outer periphery of the rotary table (3) is provided near the outer periphery of the rotary table (3). The lower part of the chute (12) for collecting coarse particles falling from the table (3) communicates with a transport machine (14) having an electromagnet (13) on the tip side.

Then, it falls from this chute (12) and is transported (14).
The coarse particles carried in the above are carried upward by the bucket elevator (15) and are fed to the hopper portion of the feeding chute (17) for feeding the raw material transported by the raw material feeding transport machine (16) to the table (3). It is configured to be turned on again.

Therefore, the raw material supplied to the upper surface of the rotary table (3) is pulverized by the pulverizing roller (5), and among the pulverized powder particles, fine powder particles are carried upward by the air flow ejected from the air ejection port (6). However, coarse powder particles with a large particle size, iron particles with a large specific gravity, etc. fall from the notch (4a) provided in the dam ring (4) or after being swirled by a vortex and then fall, The magnetic particles such as iron particles are removed by the electromagnet (13) while being transported by the transporting machine (14) via the (12). In this way, the coarse particles from which iron particles and the like have been removed are supplied again to the upper surface of the rotary table (3) together with the raw material transported by the supply transport machine (16) via the bucket elevator (15). . That is, the magnetic particles such as iron particles are sequentially removed from the upper surface of the rotary table (3), and the crushing operation of the raw material can be performed until the powder particles have a predetermined particle diameter.

[Problems to be solved by the device]

The above vertical roller mill removes iron particles from the rotary table by reducing the wind speed ejected from the annular nozzle or discharging the iron particles from the notch provided in the dam ring.

That is, when the wind speed is slowed down, a large amount of air is required in order to exert a predetermined capacity, resulting in enormous cost of incidental equipment such as a fan, a bag filter, and a duct, which is extremely economically disadvantageous. There is a problem that it ends up.

On the other hand, the notch of the dam ring makes it difficult to secure a stable layer thickness of the raw material necessary for stable operation of the roller mill, which causes a problem that it is not preferable for stable operation of the roller mill.

Therefore, an object of the present invention is to provide a vertical roller mill capable of reliably removing iron particles and the like without increasing the air volume and enabling stable crushing work.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention focuses on the blowback phenomenon of the air flow ejected from the air ejection port. Therefore, the feature of the vertical roller mill according to the first invention is A rotary table having an annular dam ring protruding upward at the outermost peripheral portion of the upper surface is rotatably supported around a vertical axis inside the lower casing, and a crushing roller that is pressed and rolls in the upper surface direction of the table is provided. In a vertical roller mill provided with an annular nozzle provided with a plurality of air jets between the outer peripheral portion of the table and the inner wall of the lower casing, at least one air of the plurality of jets is provided. Air jet speed that makes the flow velocity of the blown air slower than the flow velocity of the air blown from other air jets by freely narrowing the air flow area of the air jet to the jet outlet There is a means for collecting coarse particles and iron particles having a degree suppressing means.

A feature of the vertical roller mill according to the second invention is that a rotary table having an annular dam ring protruding upward at the outermost peripheral portion of the upper surface is rotatably supported around a vertical axis inside the lower casing. And provided with a crushing roller that rolls by being pressed in the direction of the upper surface of the table,
In a vertical roller mill having an annular nozzle provided with a plurality of air jets between an outer peripheral portion of the table and an inner wall of a lower casing, an air jet is provided at one of the plurality of jets. An air ejection velocity suppressing member is provided to reduce the air flow area of the ejection port to make the flow velocity of the blown air slower than the flow velocity of the air blown from another air ejection port.

[Action]

According to the vertical roller mill according to the present invention, among the crushed particles crushed by the upper surface of the rotary table and the rolling crushing rollers, the coarse particles and the iron particles having a large specific gravity, which are heavy by the vortex Etc. again returns to the upper surface of the rotary table, but at least one of the plurality of air outlets, in the first invention, one of the plurality of air outlets, the air outlet Is provided with a means for recovering coarse particles and iron particles having an air ejection velocity suppressing means for freely narrowing the air inflow area of the device, and in the second invention, one of the plurality of air ejection ports has an air ejection port, Since the air ejection speed suppressing member that narrows the air inflow area of the air ejection port is provided, the flow velocity of the air blown from this air ejection port becomes slow or does not flow, and as a result, the coarse particles and iron particles that have risen up One of There therefore continues to drop in the air spout, coarse and Tetsutsubu large specific gravity is reliably removed from the rotary table surface.

Further, since the dam ring of the rotary table is not provided with a notch, unevenness in the layer thickness of the supplied raw material is less likely to occur.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 to 6.

First Embodiment The first embodiment of the present invention is shown in FIG. 1 which is a side sectional view of an essential part thereof, FIG. 2 which is a sectional view taken along the line II-II of FIG. 1, and which is a sectional view taken along the line III-III of FIG. Based on Fig. 3, Fig. 4 of the relation diagram of iron particle concentration with respect to the crushing amount of blast furnace slag, and Fig. 5 of the relation diagram of crushing table and roller wear amount with respect to the crushing amount of blast furnace slag, The same parts as those of the conventional example will be described below using the same reference numerals.

In addition, in this embodiment, since the structure in the vicinity of the air ejection port of the vertical roller mill according to the prior art is partially modified, only the modified points will be mainly described.

That is, reference numeral (2) shown in the drawing is a lower casing of the vertical roller mill (1), and a rotary table (3) which is rotated around the vertical axis at a predetermined rotation speed is provided at the center of the lower casing (2). ) Is provided, and an annular dam ring (4) protruding upward is formed on the outer peripheral portion of the upper surface of the table (3). Further, a plurality of crushing rollers (5) rolling while being pressed against the upper surface of the table (3) are arranged. Further, near the outer periphery of the rotary table (3), an annular nozzle (7) having a plurality of air ejection ports (6) arranged so as to surround the outer periphery is provided.

Then, one of the plurality of air ejection ports (6) of the annular nozzle (7) communicates with a wind box (9) provided so as to surround the annular nozzle (7), and an opening / closing operation is performed. The recovery chute (8), which is a means for recovering coarse particles and iron particles, has a branch duct (10) in which a damper (11), which is an air ejection velocity suppressing means for freely narrowing the air circulation area, is interposed. did. Although not shown, similarly to the conventional vertical roll mill (1), a chute for collecting coarse particles falling from the table (3) and a lower part of the chute communicate with a transport machine, A bucket elevator that carries the coarse particles that have fallen from this chute and that has been carried by a transport machine upwards, and a coarse chute that has carried coarse particles that have been carried by this elevator that feed the raw materials transported by the raw material supply transport machine to the table. It is configured to be put into the hopper part of.

The reference numeral (12) arranged below the recovery chute (8) is an air lock damper.

Next, the usage of the vertical roller mill provided with the recovery chute (8) having the above-described configuration will be described below by crushing blast furnace slag as an example.

That is, the blast furnace slag supplied to the upper surface of the rotary table (3) is crushed by the nip rolling of the crushing roller (5), and among the crushed powder particles of the blast furnace slag, the fine powder particles are the air ejection port (6). Although it is carried upward by the air flow ejected from the blast furnace, coarse powder particles with a large particle diameter and iron particles with a large specific gravity contained in the blast furnace slag are soared by the vortex flow generated on the upper surface side of the rotary table (3). After that, it falls into the opening of the recovery chute (8). That is, the air that is about to be ejected from the wind box (9) through the branch duct (10) from this opening is
This is because the flow is suppressed by 1) and the ejection speed from this opening is low or zero.

Then, the mixed particles composed of coarse particles and iron particles that have dropped into the opening of the recovery chute (8) drop through the recovery chute (8) and are recovered.

Magnetic particles such as iron particles in the mixed particles thus collected are collected by an electromagnet or the like while being transported by a transport machine, and only the remaining coarse particles are newly supplied together with the newly supplied blast furnace slag.
It is again supplied to the upper surface of the rotary table (3) through the raw material supply duct.

Therefore, it is possible to prevent an increase in the amount of iron particles that tend to stay on the upper surface of the rotary table (3) and significantly reduce the amount of wear of the rotary table (3) and the crushing roller (5). It became.

Incidentally, the effect of this embodiment on the iron particle concentration and the abrasion amount of the pulverizing table and the roller will be described below with reference to FIGS. 4 and 5.

That is, FIG. 4 shows a modification of a vertical roller mill having a conventional structure, in which a steel chute (8) equipped with a damper is attached to one air ejection port (6) of an annular nozzle (7) before and after the iron is mounted. The change in grain concentration (average value by sampling at 9 locations of blast furnace slag on a rotary table) was examined. According to this figure, by attaching the recovery chute (8), the concentrated amount of iron particles becomes 1/4, and it is clearly understood that the effect of attaching the recovery chute (8) is great.

In addition, FIG. 5 shows changes in the amount of wear with respect to the amount of crushed blast furnace slag (the amount of wear in units of 1 ton of blast furnace slag is shown in units of g). Is indicated by a black ● mark, the third crushing roller is indicated by a white Δ mark, the fourth crushing roller is indicated by an X mark, and the rotary table is indicated by a black mark ■.

According to this figure, it can be clearly seen that the amount of wear of them has been reduced since the time of modification.

It should be noted that in the above-described embodiment, an example in which the recovery chute is arranged in one of the plurality of air ejection ports has been described, but a chute having such a configuration is provided in two or more air ejection ports. When two recovery chutes were provided, the concentration of iron particles could be reduced to about half that of one recovery chute.

Second Embodiment A second embodiment will be described below with reference to FIG.

That is, the wind box (9) is located on the inner side of the opening of one air ejection port (6) of the plurality of air ejection ports (6) of the annular nozzle.
A suppression plate (12) which is an air ejection speed suppression member is provided with the width dimension of the opening portion open to the side set to 1/2 of the width dimension of the opening portion of the air ejection port (6). It was configured.

That is, the recovery chute having the damper of the first embodiment is replaced with the suppressing plate (12).

Therefore, since the amount of air ejected from the air ejection port (6) is suppressed by the suppression plate (12), the iron particles pass through the openings of the air ejection port (6) and the suppression plate (12), and the iron particles are removed. It drops into a wind box (9) in which a scraper (not shown) for removal is arranged. And since iron particles in the wind box (9) can be removed by a scraper, its action,
The effect is almost the same as that of the first embodiment.

In the above, an example of crushing blast furnace slag as a raw material has been described, but since it is effective for crushed objects containing highly hard toxic substances such as iron particles, nothing is limited to blast furnace slag. Of course, further, modifications within the range not departing from the technical idea of the present invention are included.

[Advantages of the Invention] According to the vertical roller mill according to the present invention, at least one of the air outlets of the annular nozzle has at least one air outlet, so that the air flow area of the air outlet can be freely narrowed. Since the means for recovering coarse particles and iron particles having means or the air ejection speed suppressing member for narrowing the air flow area of the air ejection port is provided, the coarse particles and iron particles that are swirled by the vortex flow generated on the upper surface side of the rotary table And the like drop and are discharged to the portion where the ejected air amount adjusting means or the suppressing means is provided. Therefore, the iron particles are surely removed from the surface of the rotary table, and the amount of the iron particles does not increase, so that it becomes possible to reduce the wear amount of the crushing roller segment and the table segment.

Further, since the dam ring of the rotary table is not provided with a notch and unevenness in the layer thickness of the supplied raw material does not occur, in addition to enabling stable pulverization work of the raw material, Since it suffices to secure the flow velocity of the air flow ejected from the ejection port, as a result, the economical effect that the power cost of the auxiliary equipment for supplying the air can be reduced has been brought about.

Therefore, according to the present invention, it is possible to reliably remove iron particles and the like without increasing the air volume, and to realize an extremely excellent and useful vertical roller mill that enables stable crushing work. is there.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part of a vertical roller mill according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a sectional view taken along line III-III of FIG. Fig. 4 is a relational diagram of iron particle concentration with respect to crushing amount of blast furnace slag, Fig. 5 is a relational diagram of crushing table and roller wear amount with respect to crushing amount of blast furnace slag,
FIG. 6 is an explanatory view of the essential parts of the second embodiment of the present invention, and FIG. 7 is an explanatory view of the overall structure of a vertical roller mill according to the prior art.
FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. (1) …… Vertical roller mill, (3) …… Lower casing, (3) …… Rotary table, (4) …… Dam ring,
(5) ... crushing roller, (6) ... air jet, (7)
…… Annular nozzle, (8) …… Recovery chute, (9) ……
Wind box, (10) …… Branch duct, (11) …… Damper, (1
2) …… Suppression plate.

Claims (2)

[Scope of utility model registration request] 1. A rotary table having an annular dam ring projecting upward on the outermost peripheral portion of the upper surface is rotatably supported around a vertical axis inside the lower casing, and is pressed in the direction of the upper surface of the table to roll. In the vertical roller mill, which is provided with a crushing roller which is provided with an annular nozzle having a plurality of air jets between the outer peripheral portion of the table and the inner wall of the lower casing, At least one air outlet, by freely narrowing the air flow area of the air outlet, the flow velocity of the blown air is made slower than the flow velocity of the air blown from other air outlets. A vertical roller mill characterized in that it is provided with means for collecting coarse particles and iron particles having means. 2. A rotary table having an annular dam ring projecting upward at the outermost peripheral portion of the upper surface is rotatably supported around a vertical axis inside the lower casing, and is pressed in the upper surface direction of the table to roll. In the vertical roller mill, which is provided with a crushing roller which is provided with an annular nozzle having a plurality of air jets between the outer peripheral portion of the table and the inner wall of the lower casing, An air ejection velocity suppressing member that reduces the air flow area of the air ejection port to at least one air ejection port to make the flow velocity of the blown air slower than the flow velocity of the air blown from another air ejection port. A vertical roller mill characterized by being provided.