JPH0347900B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This invention raises the pulverized material between a table and rollers using a gas flow, and takes out the pulverized material in the particle size composition range sorted by an upper classification mechanism. The present invention relates to the vertical roller mill and, in detail, its classification mechanism.

(Prior art) Vertical roller mills are generally more economical than tube mills because they require less electricity per unit of grinding work, but they are also more economical than tube mills; The n-valent tanα of the R-R diagram (see Figure 9) that evaluates the particle size structure is narrow.
(The horizontal axis is the logarithm logX of the particle diameter There is a tendency for the n value (indicating narrowness) to increase (suddenly), but this n value is related to the quality of the pulverized product, and in the case of cement, if the n value is high, it may cause problems such as workability. arise.

Furthermore, even if the sorting area of the classification mechanism is changed by adjusting the air volume to the classification mechanism or the rotational speed of the rotary classification mechanism, the number of circulations of the crushed material in the roll mill will change, and the central particle size of the particle size composition area will simply shift. However, the particle size configuration region (in other words, the n value) was still narrow (high).

Here, the particle size composition region refers to the region of particle diameters constituting a certain powder or granule, and changing the sorting region means the representative particle size of the powder or granule having a certain particle size composition region (for example, R = 50% (particle size).

By the way, the classification mechanism of conventional vertical roller mills is classified into three types, as shown in a, b, and c in Fig. 1: a fixed blade type b rotary blade type c fixed blade and rotary blade combined type. Of these types of classification mechanisms, it is difficult to adjust the sorting area for a, and for b and c it is possible to widely adjust the sorting area by changing the rotational speed of the rotor. However, it was not possible to obtain the desired particle size structure (because the particle size structure range of the pulverized material before sorting was narrow, so even C was only classified in series).

(Object of the Invention) This invention has been made in view of the above points, and is a classification mechanism that can obtain a desired particle size structure (various n values) for pulverized products and can meet the needs of all kinds of products. The present invention aims to provide a vertical roller mill equipped with the following.

(Structure of the Invention) In order to achieve the above object, the present invention has a particle size structure in which the pulverized material is pulverized between a table and a roller and is raised by a gas flow and sorted by at least two upper classification mechanisms having different particle size structure regions. In a vertical roller mill configured to individually take out pulverized products from a region and mix them in an air stream, the at least two classification mechanisms are arranged on a common axis,
Moreover, the present invention is characterized in that an air volume adjusting means is provided before introducing the classification mechanism or after passing through the classification mechanism, so that the mixing ratio of the pulverized material can be changed.

(Embodiments, Effects) Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 2 shows a first embodiment of the present invention, in which 1 is a rotary table installed at the lower part of the mill casing A, 2 is a crushing roller, 3 is an air or gas outlet, 4 is a raw material supply device, and 4 is a raw material supply device. A duct 5 for taking out the pulverized material is provided at the center of the upper end of A, and below the duct 5, separators 6 and 7, which are two types of classification mechanisms, are arranged in parallel in two stages, upper and lower, on a common axis. A cone 9 having a flap-type damper 8 at its discharge port is disposed below. As shown in FIG. 3, the upper separator 6 has a structure in which a large number of blades 6a whose rotation angle can be adjusted are arranged at equal intervals in the circumferential direction, and the lower separator 7 is set at a predetermined rotation angle. It has a structure in which a large number of blades 7a (which may be variable, however) are arranged at equal intervals in the circumferential direction. When the fixed blade classification mechanism is introduced into a gas classifier structure containing powder and granular materials to be sorted, the fixed blades apply swirling force to the powder and granular materials together with the gas. At this time, the fine particles are discharged from the mill along with the gas, but the coarse particles are subject to a large centrifugal force, so they move toward the outside of the blades and at the same time fall downward due to gravity, and are returned to the crushing section. As a result, in the case of a classification mechanism using fixed blades, the performance changes by changing the blade angle, and the closer the blade angle is to the tangential direction of the circumference, the finer the powder and granules discharged together with the gas will be.

Reference numeral 10 denotes a gas inflow amount adjusting cylinder which is an air volume adjusting means arranged vertically freely around the connecting portion of the upper and lower separators 6, 7 before introduction thereof. By changing the vertical position of this adjusting cylinder 10, each separator 6, By changing the ratio of gas amounts flowing into the separators 7, the mixing ratio of the products sorted by the separators 6 and 7 can be adjusted over a wide range.

Therefore, according to the vertical roller mill having at least two classification mechanisms arranged in parallel on a common axis as described above, the raw material supplied from the raw material supply device 4 is pulverized between the rotary table 1 and the rollers 2. The pulverized material rises inside the mill casing A due to the gas flow, but the rotation angle of the blades 6a of the upper separator 6 is set to a predetermined rotation angle different from that of the blades 7a of the lower separator 7 (for example, the blades 7a of the lower separator 7 By setting the angle closer to the center direction and sorting the pulverized materials, the pulverized materials having two different particle size composition regions are taken out from the duct 5.
mixed within. In this way, a product consisting of ground material with different particle size composition ranges is produced. Also,
By arranging the two classification mechanisms on a common axis, the entire device including the mill casing A can be made more compact.

FIG. 4 shows a second embodiment of the present invention, in which the upper separator 6 of the first embodiment is replaced with a rotary blade type separator, and by changing the rotation speed, the particle size composition range of the pulverized material to be sorted can be freely adjusted. It is possible to set it to .

FIG. 5 shows a third embodiment of the present invention, in which the upper and lower separators 6 and 7 are rotary blade type separators, and the rotational speeds of the separators 6 and 7 are set to different arbitrary speeds.
The particle size range of the pulverized products to be separated by the separators 6 and 7 can be set freely, and the final product is taken out of the duct as a mixture of the pulverized products by the gas flow. In the first to third embodiments, two separators 6 and 7 are arranged in parallel to exhibit a parallel classification function.

Next, FIG. 6 shows a fourth embodiment of the present invention, in which a rotary wing type separator 7 is arranged on a common axis within a fixed wing type separator 6 (functionally, they are arranged in parallel and in series). In addition, a dedicated duct 5, 5' is provided for each separator 6, 7, and a damper 5, which is an air volume adjustment means, is installed in each duct 5, 5'.
a, 5a' are arranged to connect the rear ends of the ducts 5, 5' to a common duct 5''.

Therefore, in this embodiment, the outer separator 6
A part of the pulverized material having a particle size composition including relatively coarse particles that has been primarily sorted by is taken out from the duct 5, and the rest is further sorted secondarily by the inner separator 7, and only the pulverized material having a fine particle size composition is taken out from the duct 5'. The two separators 6 and 7 are designed to mix in a common duct 5''. Therefore, these two separators 6 and 7 have a serial classification function in addition to a parallel classification function. The ratio of the finely ground material to the finely pulverized material is determined by adjusting the dampers 5a, 5a', which are air volume regulating means, instead of the gas inflow regulating cylinder 10 in the first to third embodiments.

FIG. 7 shows a fifth embodiment of the present invention, which has a structure in which the cone 9 of the previous fourth embodiment is removed and the fixed-wing type outer separator 6 is moved below the rotary-wing type separator 7. ,
In this example as well, the two separators 6 and 7 are arranged in parallel on a common axis, and their operation is common to the fourth embodiment. Although not shown, in the structure of this fifth embodiment (FIG. 7),
It is also possible to remove the fixed wing type outer separator 6 and perform gravity classification of the pulverized material. In this case, the pulverized material in the coarser particle size region is transferred to the duct 5.
It can be taken out from.

FIG. 8 shows a sixth embodiment of the present invention. In the fourth embodiment, another duct 11 is provided near the outside of the upper end of the mill casing A.
It has a structure in which a damper 11a is disposed inside the duct, and the rear end of the duct 11 is connected to a common duct 5''. Therefore, in the case of this embodiment, the particle size is relatively coarse and has been primarily classified by gravity classification. A portion of the ground material having a region is removed from the duct 11 and mixed in a common duct 5'' with the ground material sorted by the classification mechanism.

(Effects of the Invention) As explained above, the vertical roller mill of the present invention takes out the pulverized materials individually through at least two classification mechanisms having different particle size configuration regions or sorting regions, and then mixes them in an air stream. Moreover, since the air volume adjustment means is attached before the introduction of the classification mechanism or the air volume adjustment means is provided in the duct after passing through the classification mechanism,
It is possible to change the mixing ratio of two or more pulverized products having different sorted particle size composition regions or sorted regions, and therefore, it is possible to greatly expand the ability to adjust the particle size composition of the product and to facilitate the adjustment.

Furthermore, if the particle size composition range of the pulverized product after classification by each classification mechanism is narrow, or in other words, if the n value (R-R diagram) of the pulverized product is high, the n value as a product will be as shown in Figure 10. As shown, the sum (a+b) of two or more different grain size configuration regions can be lowered.

Furthermore, since it is possible to obtain a pulverized product having a desired particle size structure, it is particularly suitable for pulverizing cement, etc., where the n value has a profound effect on quality. Furthermore, the field of application of the vertical roller mill, which requires less electric power per unit of grinding operation than the tube mill, can be expanded.

[Brief explanation of drawings]

1a, b, and c are schematic front sectional views of a vertical roller mill equipped with a conventional general classification mechanism; FIG. 2 is a schematic front sectional view showing a first embodiment of the present invention;
3 is a sectional view taken along the line X-X in FIG. 2, FIG. 4 is a schematic front sectional view of a main part showing a second embodiment of this invention, and FIG. 5 is a main part showing a third embodiment of this invention. 6 is a schematic front sectional view of main parts showing a fourth embodiment of the present invention, FIG. 7 is a schematic front sectional view of main parts showing a fifth embodiment of this invention, and FIG. A schematic front sectional view of main parts showing the sixth embodiment of the invention, and FIGS. 9 and 10 are R-R diagrams (particle size distribution curve diagrams)
It is. 1...Rotary table, 2...Crushing roller, 3...
...Gas outlet, 4...Raw material supply device, 5...
Duct, 5a, 5b'... damper (air volume adjustment means),
6, 7... Separator (classifying mechanism), 8... Damper, 9... Cone, 10... Gas inflow adjustment cylinder (air volume adjustment means), A... Mill casing.

Claims (1)

[Claims] 1. The pulverized material pulverized between the table and the rollers is raised by a gas flow, and the pulverized material in the particle size composition ranges sorted by at least two upper classification mechanisms having different sorted particle size composition regions is taken out individually. , in a vertical roller mill configured to mix them in an air stream, the at least two classification mechanisms are arranged on a common axis, and an air volume adjustment means is provided before introducing the classification mechanism or after passing through the classification mechanism, A vertical roller mill characterized by being able to change the mixing ratio of pulverized materials. 2. The vertical roller mill according to claim 1, wherein at least one of the former classification mechanisms is a rotary blade type separator. 3. The vertical roller mill according to claim 1, wherein one of the early classification mechanisms is natural classification using gravity of the pulverized material.