JPH01270982A - Air separator - Google Patents

Abstract

PURPOSE:To markedly reduce the mixing amount of coarse particles on a fine powder side by setting the inner diameter of a fine powder discharge port to a length having a specific ratio with respect to the max. diameter of a rotary blade wheel and providing an annular member having a specific length from the fine powder discharge port toward a vertical lower part. CONSTITUTION:A vertical drive shaft 7 supported in a rotatable manner and a rotary blade wheel 8' having a large number of integrally rotating classifying blades 8 provided to the periphery thereof are provided at the center of a classifying chamber 1. The fine powder discharge port 9 communicating with the interior of the rotary blade wheel are arranged above said blade wheel 8' and guide members 6 provided with a large number of slit like perforations for imparting revolution to classifying air are fixed to the outer periphery of the blade wheels on a concentric circle at a proper interval. A cone-shape member 10 reduced in its diameter downwardly is provided so as to be connected to the guide members 6. The inner diameter of the fine powder discharge port 9 is set to 30-70 of the max. diameter of the rotary blade wheel 8' and an annular member 12 having a length 5-20% of the height of the vent part of the classifying blades 8 is arranged from the fine powder discharge port 9 toward the vertical lower part.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to materials to be classified (hereinafter referred to as classified raw materials) such as cement raw materials, talin powder, blast furnace slag, limestone, and chemicals that are crushed in a crusher and a crushing section. This relates to an air separator that separates powder (described below) into fine powder and coarse powder using an air flow.

[Prior Art] An air separator is a classification device whose purpose is to extract powder of a desired particle size from the powder crushed in a crusher and a crushing section using an air flow to produce a product.The classification principle is as follows. Broadly speaking, gravitational classification uses the difference between fluid drag acting on the powder and gravity acting on the powder, and inertia classification uses the difference between the fluid drag and inertia force acting on the powder by suddenly changing the direction of airflow. It can be classified into three types: force classification and centrifugal force classification that utilizes the difference between fluid drag and centrifugal force acting on the powder by swirling airflow.

Among these, when processing a large amount of classified raw materials in a shell, a classification device that utilizes the principle of centrifugal force classification is used, and the shape of the classification chamber is spiral-shaped to swirl the airflow. There are free vortex types, forced vortex types in which the airflow is forcibly swirled by rotating blades installed in the classification chamber, and types that combine these to utilize both free vortices and forced vortices. be.

FIG. 7 shows an example of a conventional air separator.

This is a type of % formula that combines free vortex and forced vortex % The classified raw material is fed from the raw material supply port 3a, passes through the dispersion plate 4a rotating at high speed and the collision plate 20, and is used for classification in a dispersed state. thrown into the air. Classifying air flows tangentially from the classifying air intake 5a along the spiral inner wall of the casing, passes through the guide member 6a, forms a primary swirling airflow, and is then rotated by the rotating rotary impeller 8a. Next, a swirling airflow is formed.

Classification is performed in the first and second swirling airflows, and then in the secondary swirling airflow, by balancing the centrifugal force and the drag force due to the inwardly flowing air. It is taken out of the system as a fine powder.

On the other hand, aggregates of coarse particles larger than the required particle size and fine particles smaller than the required particle size are bounced off toward the outer circumference of the rotary impeller 8a by the centrifugal force caused by the secondary swirling airflow, and then flowed along the inside of the guide member 6a. While descending, the aggregates of fine particles are exposed to the classification air that enters through the guide member 6a and are subjected to a dispersion effect, but the coarse particles are roughly dispersed through the coarse powder outlet 11.
Continue falling towards. Then, the dispersed fine particles are
It is transported again to the secondary swirling airflow together with the classification air and classified.

[Problem to be solved by the invention] However, in centrifugal force classification, although there is a solid theory that classification is performed by the balance between fluid drag and centrifugal force, conventional technology It is difficult to extract only the particles as fine powder, and there have been many cases where coarse particles are mixed into the fine powder side.

Regarding the difference between theory and reality, the theory deals with single particles, whereas the powder to be actually classified is not a single particle, but particles collide with each other or collide with the classification blade. It is thought that the cause is that particles collide.

As a result, in order to prevent coarse particles from entering the fine powder side, the actual rotation speed of the classification blade is set higher than the theoretical rotation speed required to obtain fine powder of the required particle size. Measures have also been taken, such as installing a member on the outer periphery of the rotary impeller that rotates together with the impeller to prevent coarse particles from entering.

Therefore, as the rotational speed of the rotary impeller increases and the weight of the outer peripheral portion of the impeller increases, there is a problem in that the electric power required to drive the rotary impeller becomes excessive.

The present invention provides an air flow system that can suppress an increase in power consumption and reduce coarse particles mixed into the fine powder side with respect to extracting fine powder of a required particle size from the powder crushed in a crusher and a crushing section using an air flow. The purpose is to provide a separator.

[Means for Solving the Problems] A rotary impeller is provided in the center of the classification chamber and has a rotatably supported vertical drive shaft and a number of classification blades that integrally rotate around the drive shaft. A fine powder discharge port communicating with the inside of the rotary impeller is arranged above the vehicle, and a guide member having a large number of slit-shaped holes for giving swirl to the airflow for classification is placed on the outer circumference of the rotary impeller, spaced apart at an appropriate distance on a concentric circle. In the air separator, the inner diameter φd of the fine powder discharge port is 30% to 70% of the maximum diameter φD of the rotary impeller. Further, an annular member having a length h of 5% to 50% of the height H of the ventilation portion of the classification blade is provided vertically downward from the fine powder discharge port.

If the inner diameter φd of the fine powder outlet is made smaller than 30% of the outer diameter φD of the rotary impeller, the velocity of the classification air passing through the outlet will increase too much, and the separator differential pressure will increase, causing the exhaust fan to In addition, if the size exceeds 70%, the width of the classification blade is restricted and effective classification cannot be performed.

In addition, if the length h of the annular member is shorter than 5% of the height H of the ventilation part of the classification blade, the classification effect according to the present invention will be reduced, and if the length h exceeds 50%. If it is made too long, the classification air will concentrate under the classification blade and pass through, making it impossible to perform efficient classification.

[Operation] A primary swirling airflow is formed by the guide member, and a secondary swirling airflow is formed by the rotary impeller. Furthermore, the classified raw material is classified in the secondary swirling airflow and the secondary swirling airflow with the balance between centrifugal force and drag force due to inwardly flowing air, which is the same as in the conventional method.

Now, considering the space in which classification is performed, in conventional air separators, -order classification is performed in a space surrounded by a guide member and classification blades, and secondary classification is performed in a space corresponding to the width of the classification blades or It was said that the event would take place in the vicinity.

However, the present invention was made based on the inventor's discovery that secondary classification can be performed even in a space roughly in the center of the classification blade, and the inner diameter of the fine powder outlet is set to an appropriate size. In addition, by providing the annular member vertically downward around the fine powder discharge port, it is possible to form an effective swirling airflow even in the space from the inside of the classification blade to the position where the annular member is extended downward. The residence time of the classified raw material in the swirling air current becomes longer, and sharp classification is performed.

Therefore, the amount of coarse particles mixed into the fine powder side can be significantly reduced.

[Example] The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows one embodiment of the invention. The separator is constructed inside a cylindrical classification chamber 1 and a downward diameter-reduced classification chamber 2, and includes a vertical drive shaft 7 that is rotatably supported in the center of the classification chamber 1, and a vertical drive shaft 7 that is integrally mounted around the shaft. The impeller 8- has a rotary impeller 8- to which a large number of classification blades 8 are attached.
Above is a fine powder discharge port 9 that communicates with the inside of the rotating blade 8-.
are arranged. On the outer periphery of the rotary impeller 8', a guide member 6 having a large number of slit-like openings for giving swirl to the classified air is fixed concentrically at appropriate intervals and connected to the guide member 6. It is provided with a cone-shaped member 10 whose diameter is reduced downward.

Inside the dispersion 'g, 2, a dispersion disk 4 is provided on the drive shaft 7 in the lower part of the rotary impeller 8-, and the classified raw material supplied from the classified raw material supply port 3 is classified in the classification chamber 1 and is passed through the guide member. 6 and the aggregates of fine particles falling along the inner wall of the cone-shaped member 10 are thrown into the classification air that enters from the classification air intake port 5 via the slit 5' and dispersed. It has a structure that allows

Here, the inner diameter of the fine powder discharge port 9 is set to 30% to 70% φd with respect to the maximum diameter φD of the rotary impeller 8', and the ventilation of the classification blade 8 is directed vertically downward from the fine powder discharge port 9. A feature of the present invention is that the annular member 12 is provided with a length h corresponding to 5% to 50% of the height H of the portion.

FIG. 2 shows another embodiment of the present invention, in which a portion corresponding to the classification chamber of the air separator shown in FIG. 1 is applied to a vertical roller mill. ``The structure of each member of the separator is the same as that of the separator described above.

FIGS. 5 and 6 show partial classification efficiency determined from samples obtained by classification using the air separator of the present invention.

The classification experiment shown in Figure 5 was conducted under two conditions: with and without an annular member provided at the fine powder discharge port using the same air separator, and by determining the inner diameter of the fine powder discharge port and the rotation speed of the rotary impeller. The operating conditions of the separator, such as the amount of air for classification, and the amount of supplied raw material for classification, were kept constant. Ordinary Portland cement was used as the raw material for classification.

Looking at this figure, even if the operating conditions of the separator are constant, by providing an annular member at the fine powder outlet, the proportion of coarse particles collected on the coarse powder side increases.In other words, the proportion of coarse particles collected on the fine powder side increases. It is clearly seen that the area of coarse particles has decreased and the classification point has become smaller.

The classification experiment shown in Figure 6 was conducted using the same air separator under two conditions: with and without an annular member provided at the fine powder outlet. is constant, and the amount of supplied raw material for classification and the amount of air for classification are 10 when no annular member is provided.
If it is 0%, it increases to 150% when an annular member is provided.

Looking at this figure, it can be seen that by providing an annular member, even if the amount of classification air is increased, classification is performed equivalent to that without the annular member, and roughly speaking, the throughput of raw materials can be increased. It turns out that this is also possible.

[Effects of the Invention] As is clear from the above description, the present invention provides the following excellent effects.

(1) It is now possible to form an effective swirling airflow even in the space from the inside of the rotating blade to the position where the annular member is extended downward, and the time that the classified raw material stays in the swirling airflow can be extended. As a result, sharp classification is performed.

Therefore, it is possible to significantly reduce the amount of coarse particles mixed into the fine powder side.

(2) Furthermore, it becomes possible to make the classification point smaller, and it becomes possible to take out fine particles as fine powder from the classified raw material.

(3) Even if the amount of classification air is increased, the same classification as before can be performed, so the amount of classified raw materials that can be processed per hour can be increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an air separator according to the present invention;
FIG. 2 is a diagram representing another air separator according to the invention;
FIG. 3 is a cross-sectional view from ■ to ■ of FIG. 1 or 2;
FIG. 4 is a diagram with the dispersion chamber casing of the air separator shown in FIG. 1 removed. 5 and 6 are diagrams showing partial classification efficiency determined from the results of classification experiments using the air separator according to the present invention, and FIG. 7 is a diagram showing a conventional air separator. 1...minute @to, 1'...dispersion chamber casing, 2...
・Dispersion chamber, 2-... Dispersion chamber casing, 3, 3a...
・Classified raw material supply port, 3-...Crushed raw material supply port, 4,4
a... Dispersion plate, 5, 5a... Air intake for classification, 5
'-Slit, 6, 6a...Guide member, 6-...
Slit-shaped opening, 7, 7a... Drive shaft, 8... Classifying blade, 8", 8a... Rotating impeller, 9, 9a... Fine powder discharge port, 10... Cone-shaped member, DESCRIPTION OF SYMBOLS 11... Coarse powder discharge port, 12... Annular member, 20... Collision plate, 30...
... Reduction gear, 31... Grinding table, 32... Pressure cylinder, 33... Roller support member, 34... Grinding roller, 50... Airflow patent applicant Ube Industries Co., Ltd. No. 1 Cg Figure 2 Figure 3 Figure 4 Figure 5 Figure 6r5r1 Particle diameter <μm) Figure 7

Claims (1)

[Claims] At the center of the classification chamber, there is a rotary impeller with a rotatably supported vertical drive shaft and a number of classification blades that rotate integrally around the shaft. A guide member having a communicating fine powder discharge port and a large number of slit-like openings for giving swirl to the classification air around the outer periphery of the rotary impeller is fixedly installed on a concentric circle with an appropriate distance between the guide members. In the air separator, the inner diameter of the fine powder discharge port is set to 30 to 70% of the maximum diameter of the rotary impeller, and the inner diameter of the fine powder discharge port is set to be 30 to 70% of the maximum diameter of the rotary impeller. An air separator characterized in that an annular member is provided with a length of 5% to 50% of the height of the ventilation portion of the classification blade.