JPH028777B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a vertical roller mill with a built-in classifier.

[Prior Art] A vertical roller mill has multiple rollers placed in contact with each other on a rotating rotary table, and the raw material supplied between the rollers is pulverized by creating an upward air current around the rotary table. This type of roller mill has rotating blades called a classifier above the casing.
As the pulverized raw material is sucked inside the casing by an exhaust fan and ascends, the coarse powder is knocked off by this classifier and returned to the table, and the coarse powder is re-displaced by taking out only the fine powder. It is configured to crush.

[Problems to be Solved by the Invention] Conventionally, in the above-mentioned roller mill, fine powder rides on the sucked air flow and is collected outside as a product, while coarse powder falls back toward the rotary table and some of it The particles rise again on the rising air current, and only the remaining portion falls onto the rotary table and is crushed again.

For this reason, a circulating flow containing fine powder and coarse powder always occurs within the casing, forming a powder fluidized bed and causing pressure loss. Because of this pressure loss, the output of the exhaust fan must be increased, resulting in an increase in power consumption.

On the other hand, the coarse powder that falls onto the rotary table falls indiscriminately on various parts of the rotary table, does not have a chance to be re-pulverized, and is resuspended on the air currents blown up from the outer periphery of the rotary table, causing it to be re-pulverized. There were drawbacks that hindered it.

[Means for Solving the Problems] The present invention involves pulverizing raw materials between a rotating rotary table and rollers rotating in contact with the rotary table, and pulverizing the raw material by riding the air flow sucked in by an exhaust fan. In a vertical roller mill in which the crushed raw material is classified by a classifier attached to the upper part, a curved plate with an inverted truncated conical side surface parallel to the inner surface is provided along the lower inner surface of the upper casing of the mill. forming a gap along the lower inner side;
A plurality of inverted triangular coarse powder pockets are provided in the gap,
The upper parts of each coarse powder pocket are connected to each other, and a coarse powder conduit is installed from the lower part of each coarse powder pocket toward the center, so that coarse powder is led out to the vicinity of the center of the rotary table by a plurality of coarse powder conduits. Do it like this.

[Function] The present invention forms a gap on the lower inner side of the upper casing by providing a curved plate with an inverted truncated conical side surface parallel to the inner surface along the lower inner surface of the upper casing in a vertical roller mill, and Since a plurality of continuous inverted triangular coarse powder pockets are provided in the gap, all of the coarse powder that swirls and falls along the upper casing can be returned to the rotary table.
Furthermore, since the powder is returned through the coarse powder conduit when returning to the rotary table, the coarse powder is not mixed into the upward air current generated around the rotary table.

[Embodiment] In an embodiment of the present invention, as shown in FIG. 1, a coarse powder pocket and a coarse powder conduit are attached to a conventional vertical roller mill 1.

That is, the main body of the vertical roller mill 1 includes a rotary table 3 at the bottom of a casing 2, and a plurality of rollers 4 are arranged in contact with the rotary table 3. This rotary table 3 is rotated via a reduction gear 5 by a lower electric motor not shown in the drawings. Incidentally, blades 6 are arranged at equal angular intervals on the outside of the rotary table 3.
Further, a classifier 7 is disposed in the upper part of the casing 2, and the classifier 7 uses an upper electric motor 9 to rotate a support member 10 by a shaft 8. Equipped with feathers 11.

On the inner surface of the upper casing 12 that partitions the periphery of the classifier 7, as shown in FIGS. A large number of upper casings 12 are provided inside the lower part of the upper casing 12.
By providing a curved plate 18 having an inverted truncated conical side surface parallel to the lower inner surface of the upper casing 12 along the lower part of the upper casing 12, a gap is created inside the upper casing 12 so that the lower part of the upper casing 12 has a double structure. Further, a plurality of inverted triangular coarse powder pockets 14 are formed in the gap between the curved plate 18 and the upper casing 12, and the upper part of the coarse powder pocket 14 is connected to the upper part of the adjacent coarse powder pocket 14. They are arranged in a continuous manner so as to touch each other, and from the bottom, through a coarse powder conduit 15, reach a collecting pipe 16, and a discharge port 17, which is the lower end of the collecting pipe 16, opens above the rotary table 3. do.

In the operation of the roller mill according to this embodiment, when the upper and lower electric motors are started, the rotary table 3 rotates and the rotary blades 11 also start rotating. Then, by operating an exhaust fan (not shown), an upward air current is generated as shown by the arrow in FIG.
2a leads to subsequent steps.

In this state, when raw materials to be crushed, such as limestone, are supplied onto the rotary table 3 by a feeder (not shown), the raw materials are sandwiched between the rotary table 3 and the rollers 4, and are crushed. The separated raw material rises on the rising air current and is guided to the classifier 7 through the gap in the coarse powder conduit 15. In the classifier 7, the rising raw material is classified by the rotating blades 11, and the fine powder rides the rising air flow and becomes a product at the opening 1.
The classified coarse powder is taken out of the main body of the mill from 2a and falls naturally while rotating along the inner wall of the casing 12. The coarse powder falling while rotating falls along the upper casing 12 while being caught by the coarse powder collection protrusion 13, falls into the coarse powder pocket 14 formed below the upper casing, and is collected at the bottom of the coarse powder pocket 14. Coarse powder conduit 1
5 and collecting pipe 16 to the center of the rotary table 3, allowing efficient pulverization.

Incidentally, the coarse powder collecting protrusion 13 provided on the inner surface of the casing 12 of the classifier 7 is not limited to a semi-cylindrical plate having a vertically straight shape as shown in FIG. Alternatively, instead of a large number of protrusions for collecting coarse powder, a large number of grooves for collecting coarse powder are provided, and the shape is substantially continuous in the vertical direction. Any shape may be used as long as it has concave and convex shapes spaced at appropriate intervals and efficiently guides the coarse powder that has fallen onto the inner surface of the upper casing 12 to the coarse powder pocket 14.

Furthermore, the shape of the discharge port 17 of the collecting pipe 16 is branched as shown in FIGS. It is also possible to have a structure in which the coarse powder is immediately pulverized by the rollers 4.

As described above, in this embodiment, the raw material is pulverized between the rotating rotary table 3 and the roller 4 rotating in contact with the rotary table 3, and the pulverized material rises on the airflow sucked by the exhaust fan. In a vertical roller mill 1 in which raw materials are classified by a classifier 7 attached to the upper part, a plurality of mutually continuous coarse powder pockets 14 are provided on the lower inner surface of the upper casing 12 of the mill, and a plurality of coarse powder pockets 14 are separated from the lower part of the coarse powder pockets. Since the coarse powder conduit 15 is arranged toward the center so that the collected coarse powder is led out to the center of the rotary table 3 or near the center such as in front of the biting part, the coarse powder is sorted by the rotary blades 11. The coarse raw material falling along the upper casing 12 is returned to the rotary table 3 without mixing with the flow path of the fine powder raw material that is pulverized and ascends on the air flow, and is further finely pulverized. Become.

[Effects of the Invention] The vertical roller mill according to the present invention can prevent the coarse powder raw material that hits the upper casing and falls along the inside of the upper casing due to the operation of the classifier from being carried by the air flow rising due to the coarse powder pocket. Since everything can be returned to the rotary table, coarse powder and fine powder can be efficiently distinguished, and coarse powder can be reliably guided to the center of the rotary table for re-grinding, reducing pressure loss. can be reduced to reduce power consumption and improve grinding efficiency.

Further, if the coarse powder is supplied to the biting portion of the roller, the coarse powder is immediately crushed and receives a more reliable crushing action, so that more efficient crushing can be achieved.

[Brief explanation of drawings]

Figure 1 is a longitudinal front view, Figure 2 is A-A of Figure 1.
3 is a sectional view, FIG. 3 is a plan view showing a state in which a distribution pipe is attached to a collecting pipe, and FIG. 4 is a side view thereof. 1...Roller mill, 2...Casing, 3...
Rotary table, 4...Roller, 5...Reducer, 6
...Blade, 7...Classifier, 8...Shaft, 9...
Upper electric motor, 10...Supporting member, 11...Rotating blade, 11...Upper casing, 13...Protrusion for collecting coarse powder, 14...Coarse powder pocket, 15...Coarse powder conduit, 16...Collecting pipe , 17... discharge port, 18...
curved plate.

Claims (1)

[Claims] 1. The raw material is pulverized between a rotating rotary table and a roller that rotates in contact with the rotary table, and the pulverized raw material rises on the airflow sucked by an exhaust fan. In a vertical roller mill that is classified using a classifier attached to the upper part, a curved plate with an inverted truncated conical side surface parallel to the inner surface of the upper casing of the mill is provided along the lower inner surface of the upper casing to reduce the gap along the lower inner surface of the upper casing. A plurality of inverted triangular coarse powder pockets are provided in the gap, and the upper part of each coarse powder pocket is continuous with each other, and a plurality of coarse powder conduits are installed from the bottom of each coarse powder pocket toward the center. A vertical roller mill characterized in that a coarse powder conduit is provided so that the coarse powder is led out near the center of a rotary table. 2. The vertical roller mill according to claim 1, characterized in that the collected coarse powder is led out to the front of the engagement portion between the roller and the rotary table by having a coarse powder conduit having a plurality of distribution pipes. 3. The vertical roller mill according to claim 1, wherein the upper casing has a groove for collecting coarse powder on the inner surface thereof.