JPS6122674Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a roller mill that can be applied to a vertical dry mill for pulverizing, drying, and classifying coal, cement raw materials, etc. In general, in a vertical dry mill that crushes, dries, and classifies coal, limestone, etc., hot air is sent from the bottom of the mill into the inside of the mill through multiple hot air passages for conveying and drying the pulverized material. There is usually variation in air volume between aisles. The structure of a conventional vertical mill will be explained with reference to FIGS. 1 to 3. Materials to be crushed 11 such as coal or cement raw materials are transported from a supply pipe 1 to a rotating table 2.
and is caught between the table 2 and the roller 3. At this time, the object to be crushed 11 is crushed by the crushing load applied to the roller 3 by the loading device 4. The crushed material 12 is blown out of the rotary table 2 by the centrifugal force of the rotary table 2. On the other hand, hot air 13 for the purpose of transporting and drying the pulverized material 12 enters the mill bottom 6 through one or two hot air ducts 5 attached to the side wall of the mill, and enters the hot air inlet 7.
Enter the inside of the mill 8. This hot air inlet section 7 is partitioned into a plurality of hot air passages 19 by an inclined plate 17. Crushed material 12 thrown out of the aforementioned table 2
rises while being dried on the hot air currents,
Enter separator 9. The pulverized material 12 is separated into fine particles 14 and coarse particles 15 in the separator 9, and the former exits as a product from the outlet pipe 10.
The latter returns to table 2 and is re-ground. As for the shape of the hot air inlet section 7, there are two types: one in which there are inlet sections all around the circumference (FIG. 2), and one in which there are inlet sections at several locations (three locations in FIG. 4). Hot air inlet section 7
is further subdivided by an inclined plate 17 to form a plurality of hot air passages 19 (FIG. 3). The hot air duct 5 can be installed at one side (Figs. 2 and 4) or at the center (in the 5th position).
(Fig. 6) and both-side type (Fig. 6), and the number of rollers may be three, two, or four (not shown). On the other hand, the hot air supplied from the hot air duct 5 enters the mill interior 8 through the hot air passage 19 between the inclined plates 17 of the hot air inlet 7 while swirling inside the mill bottom 6. Conventionally, the inclined plate 17 in the hot air inlet section 7 has been installed with exactly the same shape as shown in Fig. 3.
This resulted in the following drawbacks. First, as shown in the measurement example of FIG. 8, considerable variation occurred in the amount of hot air in each hot air passage 19, which adversely affected the grinding performance, drying performance, and classification performance of the mill. In addition, as a countermeasure against the above-mentioned variations, conventional measures have been taken to increase the mill bottom height 18 (FIG. 1) to increase the mill bottom volume, so to speak, to give the mill bottom a tank effect. However, if the above measures are taken, the height of the mill will increase. Cost increases. The rotating main shaft 16 becomes longer, and as a result, the bending moment acting on the main shaft increases. Therefore, extra measures for strength, such as increasing the diameter of the rotating main shaft 16, are required, which increases costs. There were drawbacks such as: The present invention was proposed to solve the above-mentioned conventional drawbacks, and includes a table that rotates around a vertical drive shaft, a table that rotates while being pressed against the top surface of the table,
a plurality of rollers for pulverizing the material to be pulverized supplied onto the table; a generally cylindrical main body housing the table and the rollers; and a main body constituting a mill bottom below the table within the main body. at least one or more hot air ducts communicating with the side,
In a roller mill having an inclined plate disposed in a gap between the outer periphery of the table and the main body and forming a plurality of hot air passages, the inclined plate forming the hot air passages has a smaller opening ratio of the passages as they are closer to the hot air duct. By installing a resistor that reduces the height of the mill bottom, it is possible to reduce the variation in the amount of hot air in each hot air passage, and to reduce the cost of the mill and improve the performance of the roller mill. This is what we intend to provide. Below, an embodiment of the present invention will be explained with reference to the drawings. Fig. 9 shows an embodiment of the present invention corresponding to the sectional view from X to X in Fig. 1, and if the symbols in Fig. 1 are used as they are, In a vertical dry mill, the mill is equipped with a table 2 that rotates, and a plurality of rollers 3 that rotate while being pressed against the upper surface of the table 2 and crush the material to be crushed 11 together with the table 2. Bottom part 6 and said table 2
A plurality of hot air passages 19 connecting the upper mill interior 8
In addition, a resistor 20 is provided to alleviate the imbalance in the hot air flow rate. Now, as the structure is shown in FIGS. 9 to 12, a circular tube is used as the resistor 20, and a guide plate 21 is attached to the circular tube to smooth the flow.
The diameter of the circular pipe was set to be larger at the hot air inlet where the air volume was larger, according to the actual measurements shown in Figure 8. Specifically, in Fig. 9, from the upstream side of the hot air, a 23 mm circular tube is installed at the hot air inlet section 7, A, and a 13 mm circular tube is installed at the 10th hot air inlet section 7, B.
It was installed as shown in Fig. 11. Note that nothing was attached to the hot air inlet section 7,C. By inserting circular tubes of different sizes into the respective hot air inlets in this way, a throttling effect is produced in the hot air passage, making it possible to reduce variations in the air volume at the hot air inlets. Next, the first example of experimental results when this invention is applied is shown.
It is shown in Figure 3 and Table 1. Experimental example 1 is the hot air inlet section 7.
Both the mill bottom height 18 were the same as before, and the maximum deviation (dispersion) in air volume was 25% at this time. In Experimental Example 2, the hot air inlet section 7 had the same shape as before.
This is the case when the mill bottom height 18 is reduced to 2/3,
At this time, the maximum deviation in air volume was 32%. The reason why the variation in Experimental Example 2 was larger than that in Experimental Example 1 was because the mill bottom height 18 was reduced.
This is because the volume of the tank has decreased, and the so-called tank effect has decreased. Experimental example 3 reduces the mill bottom height 18 to 2/3,
This is a case where the embodiment of the present invention shown in FIGS. 9 to 12 is applied, and the attached resistor 20 has the pipe diameter as described above. At this time, the mill bottom height is 18.
Despite the tilt being as low as 2/3, the maximum deviation in air volume was reduced to 7%, demonstrating the great effect of the present invention. Examples of the above experiments include side-type hot air ducts,
Although a mill having three hot air inlets has been described, the same effect was obtained when the present invention was applied to a center type hot air duct or other types having hot air inlets around the entire circumference. In addition to the circular tube, tests were also conducted using a triangular prism and an orifice as the shape of the resistor 20, but the same effect was obtained with both. can be selected. 【table】

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional rigid dry mill;
The figure is a sectional view from X to X in Figure 1, and Figure 3 is a cross-sectional view from Y in Figure 2.
~Y cross-sectional view, Figures 4, 5, and 6 are X-X cross-sectional views of Figure 1 showing structures different from Figure 2, and Figure 7.
The figure is an explanatory diagram showing the measurement positions of A, B, and C in Figure 8. Figure 8 is a diagram showing an example of actual measurement of variation in air volume.
FIG. 9 is a cross-sectional view of a roller mill showing an embodiment of the present invention in a portion corresponding to the section X to X in FIG.
The figure is a sectional view from Z to Z in Fig. 9, Fig. 11 is a sectional view from W to W in Fig. 9, Fig. 12 is a sectional view from V to V in Fig. 9, and Fig. 13 is a sectional view of hot air in the conventional and present invention FIG. 3 is a diagram showing the relationship between the position of the inlet and the air volume ratio. Explanation of the main parts of the diagram, 2...Table, 3...
Roller, 6... Mill bottom, 7... Hot air inlet, 8
... Inside the mill, 11 ... Material to be crushed, 19 ... Hot air passage, 20 ... Resistor.

Claims (1)

[Scope of utility model registration request] A table that rotates around a vertical drive shaft, a plurality of rollers that rotate while being pressed against the top surface of the table and crush materials to be crushed that are supplied onto the table, and a generally cylindrical shape that accommodates these tables and rollers. a main body, at least one hot air duct communicating with the side surface of the main body constituting the mill bottom below the table in the main body, and a plurality of hot air ducts arranged in a gap between the outer periphery of the table and the main body. A roller mill having an inclined plate constituting a passage, characterized in that a resistor is attached to the inclined plate constituting the hot air passage to reduce the opening ratio of the passage as it is closer to the hot air duct.