CN201168700Y - A centrifugal air classifier - Google Patents

Abstract

A centrifugal airflow classifier, the classifier comprises: a cylinder (3), a cone (4) connected sequentially to the lower part of the cylinder, a primary air chamber (5), a secondary air chamber (7), a coarse powder outlet ( 19) and the coarse powder discharge valve (9); the feeding hopper (1) and the feeding valve (2) are arranged on the side of the cylinder body, the top of the cylinder body (3) is provided with a fine powder outlet (16), and the vertical classification wheel ( 13) Installed inside the cylinder body (3), the rotating shaft (17) is fixed on the bearing seat of the upper cover of the cylinder body through bearings, and the speed regulating motor (18) transmits power to the rotating shaft (17) through a belt, driving the classifying wheel (13 ) rotation; the inside of the cylinder (3) and the outside of the classifying wheel (13) are provided with an isolation cone (10). The centrifugal air classifier provided by the utility model has high classification efficiency and is easy to operate. By adjusting the total air intake, the speed of the classifying wheel, the speed of primary air and secondary air, the particle size and classification accuracy of coarse powder and fine powder can be controlled.

Description

A centrifugal air classifier

technical field

The utility model relates to the technical field of particle size separation of solid powder in airflow, more specifically, relates to an airflow classifier with vertically installed classification wheels.

Background technique

With the development of modern technology, some high-tech and cutting-edge industries related to powder technology (such as fine ceramics, biology, chemical industry, dyes, metallurgy, building materials, food, microelectronics, etc.) have increasingly strict requirements on the particle size of raw materials. requirements. On the one hand, the powder is required to be ultra-fine (that is, several microns or less); on the other hand, the distribution of the powder is required to be very narrow, that is, it is required to be concentrated in a certain particle size range. For example, the particle size distribution range of zircon powder for fine ceramics used in a special resin in the microelectronics industry is required to be between 4 and 10 microns, and the mixing amount of less than 4 microns should not exceed 20%. Such a demanding requirement, neither pulverization (such as ball mill, jet mill) nor granulation can directly meet this requirement, and generally needs to be classified. Classification is an indispensable and important process in the powder preparation industry. How to improve the cutting accuracy of the classifier and reduce the entrainment between coarse and fine powders is an important topic in the powder preparation industry at home and abroad.

CN2774653Y discloses a powder classifier with classifying wheels installed horizontally, including a feed hopper, a classifying chamber and a classifying impeller installed in the classifying chamber, and the two ends of the classifying impeller are respectively provided with a discharge pipe and a rotating shaft , the discharge pipe and the rotating shaft are supported on the side wall of the classifying chamber through sealed bearings, and an air inlet is installed at the junction of the barrel and the cone of the classifier, and multiple classifying wheels are placed horizontally. Due to the horizontal placement of the grading wheel, the flow field in the grading space is caused to interfere with each other, making the flow field in the classifier unstable and affecting the grading effect.

CN2429273Y discloses a large-scale turbine-type airflow classifier, which adopts a vertical classification wheel. One side of the classification cylinder is provided with a raw ash inlet and a primary air inlet, and the other side of the classification cylinder is provided with a fine ash outlet and a secondary air inlet. There is a coarse ash outlet at the lower end of the grading cylinder.

US4292172 discloses a vertical classifying wheel classifier, which is provided with a primary air inlet and a secondary air inlet. It can be seen from the figure that the secondary air does not have any guiding structure, and the space is large, which may easily cause the secondary air to be directly short-circuited. It does not have the effect of elutriating fine powder.

CN2642413Y discloses a dry airflow classifier, the classification wheel is vertically installed, the bottom is straight into the air, the material to be classified is carried into the classifier from the bottom together with the gas, without any other auxiliary wind, this structure is easy to cause large particles Fine particles are entrained, and coarse particles are also likely to enter the classification wheel due to collision and be carried away by the airflow.

CN2263554Y discloses a turbine type powder particle classifier, the classification wheel is installed vertically, and consists of a powder outlet cover, a turbine, a cyclone, a blanking pipe, a powder retaining sheet, a main air chamber, a secondary air chamber, It is composed of a feeder and other components. After four times of elevating and grading, the fine powder is discharged from the powder outlet cover, and the coarse powder is discharged from the lower feeding pipe. This structure also has the problem that the coarse powder intercepted by the classifying wheel and the original powder are mixed with each other. At the same time, the secondary air adopts axial flow fluidization air, so the gas and the powder cannot fully contact, and the fine powder cannot be elutriated.

CN2329457Y discloses a powder classifier, the powder of the classifier is carried by the gas from the bottom into the classifier, the upper part of the feed port is equipped with a side-intake primary air, and the structure of the cylinder is equipped with a launch cone, mainly It is used to launch the feed through the screw feeder.

Contents of the invention

The purpose of the utility model is to provide a fine powder classifier with high classification efficiency and high definition of coarse and fine powder.

The centrifugal air classifier provided by the utility model includes: a cylinder 3, a cone 4 connected in sequence to the lower part of the cylinder, a primary air structure 5, a secondary air structure 7, a coarse powder outlet 19 and a coarse powder discharge valve 9, plus The hopper 1 and the feeding valve 2 are arranged on the side of the cylinder, the top of the cylinder 3 is provided with a fine powder outlet 16, the vertical classifying wheel 13 is installed inside the cylinder 3, and the rotating shaft 17 is fixed on the bearing seat of the upper cover of the cylinder through bearings , the speed regulating motor 18 transmits power to the rotating shaft through the belt, and drives the classifying wheel 13 to rotate; the inside of the cylinder 3 and the outside of the classifying wheel 13 are provided with an isolation cone 10 .

The centrifugal air classifier provided by the utility model preferably has a compressed air sealing structure 15 installed on the top of the classifying wheel 13 .

The beneficial effects of the centrifugal airflow classifier provided by the utility model are: the raw powder is washed and classified by four stages, and the classification efficiency is high; the operation is simple, and the total air intake, the speed of the classifying wheel, the speed of the primary air and the secondary air can be adjusted. Control the particle size and classification accuracy of coarse powder and fine powder. The preferred structure is provided with a compressed air sealing structure, which prevents particles and gases from short-circuiting at the top of the classifying wheel and directly enters the classifying wheel, further improving the separation accuracy.

Description of drawings

Fig. 1 is the main sectional view of classifier structure;

Figure 2 is a cross-sectional view of the primary air chamber;

Figure 3 is a cross-sectional view of the secondary air chamber;

Fig. 4 is a cross-sectional view of the isolation cone guide blade and the classifying wheel;

Fig. 5 is a vertical sectional view of the isolation cone guide blade and the classifying wheel.

Detailed ways

The centrifugal air classifier provided by the utility model includes: a cylinder body 3, an isolation cone 10 inside the cylinder body 3, a classification wheel 13 inside the isolation cone, a fine powder outlet 16, a cone body 4, a primary air chamber 5, a secondary air Chamber 7, coarse powder discharge valve 9 and coarse powder outlet 19, the feeding hopper 1 and the feeding valve 2 are arranged on the side of the cylinder, the top of the cylinder 3 is provided with a fine powder outlet 16, and the rotating shaft 17 is fixed on the upper cover of the cylinder through bearings On the inner bearing seat of the fine powder outlet 16, the speed regulating motor 18 transmits the power to the rotating shaft through the belt, and drives the classifying wheel 13 to rotate. A preferred structure is that a compressed air sealing structure 15 is installed on the top of the classifying wheel 13 .

In the classifier provided by the utility model, the isolation cone 10 is composed of an isolation cone guide vane 11, an upper straight pipe, a cone body and a lower straight pipe. The top of the isolation cone 10 is fixed on the top cover of the cylinder body 3 . The sum of the heights of the isolation cone guide vane and the upper straight pipe is less than the height of the barrel. The height ratio of the isolation cone guide blade 11, the upper straight pipe and the classifying wheel 13 is (0.8-1.2): (0-0.3): 1, preferably (0.9-1.1): (0-0.2): 1.

As can be seen from the sectional view of the isolation cone guide vane in accompanying drawing 4, the isolation cone guide vane 11 is composed of a plurality of slits milled out on the cylinder, and a guide plate that is close to the direction of the slit. The isolation cone guide vane 11 The number of blades is mainly determined by the speed of the gas passing through the slit and the gap between the slots, and is also related to the size of the cylinder. Generally, the gap is 3-20mm, preferably 5-10mm. There are 20 blades in the figure, but not limited this number. The normal included angle α between the blade and the cylinder circle is 20-50°.

As shown in Figure 1: the cone part of the isolation cone 10 extends to the vicinity of the top of the primary air chamber 5, below which is the lower straight pipe of the isolation cone, the length of the lower straight pipe is slightly longer than the height of the primary air chamber, but it cannot be inserted into the secondary air chamber 1/3 of the height.

In the classifier provided by the utility model, the main function of the classifying wheel 13 is to classify coarse and fine particles in the dust-laden gas. The classifying wheel 13 is in the shape of a platform with a large upper part and a small lower part, and the cone angle β is 0 to 15°. The classifying wheel guide cone 12 is installed at the bottom of the classifying wheel 13, and the apex angle of the classifying wheel guide cone 12 is 120 to 15°. 150°. The classifying wheel 13 is composed of a certain number of blades or cylindrical rods 14, wherein the distance between two adjacent blades or cylindrical rods 14 is 3-15 mm, preferably 4-8 mm. When the blade-type grading wheel is used, the cross-section of the blade and the normal direction of the circle are staggered by a certain angle γ, generally 10-20°; for materials with different properties, different intercepting structures such as blades or cylindrical sticks can be used , gap, etc., adjust different operating parameters (speed of classifying wheel, primary air volume, secondary air volume and the matching relationship between the three) to control the particle size of the coarse and fine powder of the classified material, and the classification accuracy.

In the classifier provided by the utility model, the outer wall of the primary air chamber 5 is provided with a primary air inlet 20 along the circumferential tangential direction, and the primary air chamber 5 is provided with a guide structure. It can be seen from the cross-sectional view of the primary air chamber in accompanying drawing 2 that the flow guide structure is composed of a plurality of tangential guide vanes 6, and these guide vanes are evenly distributed along a circumferential tangent, so as to guide the primary air evenly into the classifier. To provide a stable and uniform centrifugal force field for the classifier, the number of blades in the figure is 10, the utility model is not limited by this, and the arrangement is reasonable according to actual needs.

In the classifier provided by the utility model, the outer wall of the secondary air chamber 7 is provided with a secondary air inlet 21 along the circumferential tangential direction, and the secondary air chamber 7 is provided with a diversion structure. It can be seen from the cross-sectional view of the secondary air chamber in Fig. 3 that the flow guide structure is composed of a plurality of tangential guide blades 8 evenly distributed along the tangent of the circumference. The main function of the secondary air chamber 7 is to elutriate the coarse powder under separation and interception again. The number of blades in the figure is 6, but not limited to 6. The air intake in this part only accounts for a small part of the entire air volume, about 1 /4 or less.

In the classifier provided by the utility model, the feeding hopper 1 and the feeding valve 2 can be any uniform powder feeding mechanism, the figure is a rotary valve, but it is not limited to this structure, it can be a screw, or is another structure.

In the classifier provided by the utility model, the gas sealing structure 15 is composed of an air inlet 22, an annular space 23 and an annular air outlet 24. 24 blows air to the periphery of the top of the classifying wheel 13 to prevent the dust-laden gas from directly entering the classifying wheel 13.

Further illustrate the working process of the centrifugal air classifier provided by the utility model below in conjunction with accompanying drawing:

The main air is evenly introduced into the classifier by the guide vanes 6 of the primary air chamber 5, and a stable and uniform centrifugal force field is formed between the classifier cylinder 3 and the isolation cone 10; the powder to be classified is put into the hopper 1, and the The material valve 2 evenly feeds the powder into the classifier barrel 3. In the annular space of the barrel 3, the cone 4 and the isolation cone 10, the rotating updraft entering from the primary air inlet 20 is encountered. The bottom is dispersed in the entire annular space, and the centrifugal force entrained by the airflow is greater than the drag force of the gas, and the large particles are thrown onto the inner wall of the cylinder 3 and slide down along the annular space from top to bottom.

Smaller particles are carried by the airflow to the annular space between the isolation cone guide vane 11 and the cylinder 3, and the gas carries the particles through the gap between the isolation cone guide vanes 11 and enters the space between the isolation cone 10 and the classification wheel 13 In the annular space between, during this process, the airflow needs to change direction rapidly and enter in a turn, in which the large particles entrained by the airflow are separated due to inertia running in the straight direction of their operation during the turning process (see Figure 3) ; The separated coarse particles slide down along the wall of the device, and enter the secondary air chamber 7 miles after being washed by the primary wind.

The powder that enters the annular space between the isolation cone 10 and the classifying wheel 13 is carried by the airflow to move in the classifying wheel 13, and the rotating classifying wheel 13 collides and catches with the blades 14, and intercepts the coarse powder entrained in it, and the coarse powder along the The inner wall of the isolation cone 10 slides down and is discharged from the outlet of the isolation cone 10. It is mixed with the coarse powder washed by the primary wind, and after being washed again in the secondary air chamber 7, it is discharged from the coarse powder discharge port 19. . The gas enters the classification wheel 13 together with the fine powder, and is discharged from the fine powder outlet 16, and the fine powder is collected by the subsequent cyclone separator or bag filter.

When the dust-laden gas penetrates the classifying wheel 13, in order to prevent the gas from short-circuiting from the top of the classifying wheel 13 and directly enter the classifying wheel 13, a gas sealing structure 15 is installed on the top of the classifying wheel 13, and the compressed gas is evenly blown to the classifying wheel 13 The surrounding edge of the top prevents the dust-laden gas from directly entering the classifying wheel 13.

During this process, the speed-regulating motor 18 transmits power to the rotating shaft 17 through the belt, driving the classification wheel 13 to rotate. The particle size and classification accuracy of coarse powder and fine powder can be controlled by adjusting the total air intake, grading wheel speed, primary air intake speed, secondary air speed, etc.

The following examples will further illustrate the classifier provided by the utility model, but the utility model is not limited thereby.

Example 1

The structure of the classifier used is shown in Figure 1. The diameter of the classifier cylinder is 400mm, the diameter of the isolation cone is 240mm, the diameter of the classifying wheel is 180mm, the height of the classifying wheel is 220mm, and the cone angle β of the classifying wheel is 15°. The apex angle of the wheel guide cone is 120°. The height of the isolation cone guide vane is 180mm, the height of the straight pipe on the isolation cone guide vane is 30mm, and the total height of the classifier is 1800mm. Motor power 2.2KV.

Use this classifier to carry out the following classification test: classify a certain FCC catalyst fine powder, its particle size distribution is 0-80 microns, wherein the weight ratio of fine powders smaller than 40 microns is 45%. Use the above-mentioned classifier to classify the catalyst fine powder, use 40 microns as the classification point, and classify to obtain coarse powder and fine powder, wherein the coarse powder is less than 40 microns in less than 5%, and the fine powder is less than 40 microns in 90%. According to the sorting results, coarse powder and fine powder are clearly separated, and Newtonian classification efficiency η _N =86%.

Definition of Newtonian fractional efficiency:

η _N = recovery rate of useful components - residue of useless components

If coarse powder is used as the final product, the Newtonian classification efficiency calculation formula is:

Example 2

Adopt the classifier of the structure described in Example 1 to classify a certain kaolin powder, its particle size distribution is 10-100 microns, requiring 30 microns as the classification point, and the fine powder less than 30 microns in the raw material is 20%, after the utility model classification Get coarse powder, fine powder, wherein less than 30 microns in the powder are less than 1%, and in the fine powder, less than 30 microns are in 87%; From sorting result, coarse powder, fine powder are clearly separated, and Newton's classification efficiency η _N = 92.5%.

Claims (8)

1, a kind of centrifugal air classifier, this clasfficiator comprises: the cone (4) that cylindrical shell (3), cylindrical shell bottom connect successively, an air compartment (5), secondary air chamber (7), meal outlet (19) and meal bleeder valve (9); Loading hopper (1) is arranged on the cylindrical shell side with baiting valve (2), cylindrical shell (3) top is provided with fine powder outlet (16), vertical grading wheel (13) is installed in cylindrical shell (3) inside, rotating shaft (17) by bearing fixing on the bearing block of cylinder top cover, buncher (18) is given rotating shaft (17) by belt with transmission of power, drives grading wheel (13) rotation; It is characterized in that described cylindrical shell (3) is inner, grading wheel (13) outside is provided with and isolates awl (10).

2,, it is characterized in that described grading wheel (13) top is equipped with compressed air sealing structure (15) according to the clasfficiator of claim 1.

3, according to the clasfficiator of claim 1 or 2, it is characterized in that described isolation awl (10) is bored guide vane (11) by isolating, upward straight tube, cone and lower straighttube are formed, isolate awl (10) top and be fixed on the cylindrical shell (3) and cover, isolate awl guide vane (11), go up straight tube and grading wheel (13) aspect ratio be (0.8～1.2): (0～0.3): 1.

4,, it is characterized in that the aspect ratio of described isolation awl guide vane (11), last straight tube and grading wheel (13) is (0.9～1.1): (0～0.2): 1 according to the clasfficiator of claim 3.

5, according to the clasfficiator of claim 1 or 2, it is characterized in that described grading wheel (13) is the little garden platform shape in big bottom, top, cone angle beta is 0～15 °, in the bottom of grading wheel (13) deflection cone (12) is housed, and the cone-apex angle of deflection cone (12) is 120～150 °.

6,, it is characterized in that a described air compartment (5) outer wall is provided with a wind inlet (20) along the tangent to periphery direction, is provided with flow-guiding structure in the air compartment (5) according to the clasfficiator of claim 1 or 2.

7, according to the clasfficiator of claim 1 or 2, it is characterized in that described secondary air chamber (7) outer wall is provided with secondary wind inlet (21) along the tangent to periphery direction, secondary air chamber is provided with flow-guiding structure in (7).

8, according to the clasfficiator of claim 2, it is characterized in that described compressed air sealing structure (15) is made up of air inlet (22), annular space (23), air outlet (24), insert in the ring edge of air outlet (24) at the top of grading wheel (13).

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