阅读说明：本技术 一种用于超细粉体的离心式空气分级机 (Centrifugal air classifier for superfine powder ) 是由 杨旭亮 于 2019-11-06 设计创作，主要内容包括：本发明公开了一种用于超细粉体的离心式空气分级机,包括进风管、分级室、顶盖、导风叶栅、分级叶轮、细粉中转室、锥形壳体、粗粉排料口、出风管,其中导风叶栅和分级叶轮均由分别绕其轴线环形排列的若干个弯扭叶片构成气流通道；所述弯扭叶片表现为径向弯曲和轴向扭曲的联合造型,弯曲角度范围为5°～90°,扭曲角度为5°～60°。通过采用弯扭联合造型的叶片设计,减小了导风叶栅和分级叶轮叶片间旋涡运动的尺寸和强度,削弱了该通道旋涡对粉体颗粒分离运动行为的扰动作用,提高了超细粉体的分级精度,降低了分级下限,为超细粉体干式高效分级提供了一种有效装置。(The invention discloses a centrifugal air classifier for superfine powder, which comprises an air inlet pipe, a classifying chamber, a top cover, an air guide blade grid, a classifying impeller, a fine powder transfer chamber, a conical shell, a coarse powder discharge port and an air outlet pipe, wherein the air guide blade grid and the classifying impeller form an air flow channel by a plurality of twisted blades which are annularly arranged around the axis of the air guide blade grid and the classifying impeller respectively; the bending and twisting blade is in a combined shape of radial bending and axial twisting, the bending angle range is 5-90 degrees, and the twisting angle range is 5-60 degrees. The design of the blades in the bending and twisting combined modeling is adopted, so that the size and the strength of the vortex motion between the air guide blade grid and the classification impeller blades are reduced, the disturbance effect of the vortex of the channel on the separation motion behavior of powder particles is weakened, the classification precision of the superfine powder is improved, the classification lower limit is reduced, and an effective device is provided for the dry-type efficient classification of the superfine powder.)

1. A centrifugal air classifier for superfine powder is characterized in that: comprises an air inlet pipe (1), a grading chamber (2), a top cover (3), an air guide blade grid (4), a grading impeller (5), a fine powder transfer chamber (6), a conical shell (8), a coarse powder discharge outlet (9) and an air outlet pipe (7);

the air inlet pipe (1) is connected with the grading chamber (2) in a tangential direction, the top cover (3) is located above the grading chamber (2), the top cover (3) comprises a feeding funnel, the air guide blade grids (4) are fixed in the grading chamber (2) through annular clamping grooves, the grading impeller (5) is located in the center of the grading chamber (2) and is cage-shaped, the air guide blade grids comprise an upper powder dispersion disc (11), a lower annular support disc (13) and bending blades (12) vertically fixed between the upper powder dispersion disc (11) and the lower annular support disc (13), the air guide blade grids (4) and the grading impeller (5) are concentrically arranged, an annular grading space is formed between the air guide blade grids and the grading impeller, and the air guide blade grids (4) and the grading impeller (5) form an air flow channel by a plurality of bending blades (12) which are annularly and equidistantly arranged around the geometric axis of the air guide blade grids and the; the twisted blade (12) is in a combined shape of radial bending and axial twisting, wherein the radial bending is non-equal curvature smooth bending, the bending angle range is 5-90 degrees, the twisting angle range is 5-60 degrees, the installation angle gamma of the twisted blade (12) ranges from 30-90 degrees,

the fine powder classifying device is characterized in that the conical shell (8) is arranged at the lower part of the classifying chamber (2), the fine powder chamber transfer chamber (6) is positioned in the conical shell (8) and is hermetically connected with the bottom of the classifying impeller (5), the air outlet pipe (7) is tangentially connected with the fine powder transfer chamber (6) and extends out of the conical shell (8), and the coarse powder discharge port (9) is communicated with the bottom of the conical shell (8);

the grading impeller (5) is fixed on a driving shaft (10), the driving shaft (10) is connected with the grading chamber (2) through a bearing, the driving shaft (10) penetrates through the fine powder transfer chamber (6) and the conical shell (8) through a sleeve and then is connected with a variable frequency motor through a belt driving device to drive the grading impeller (5) to rotate, and the grading impeller (5) is subjected to stepless speed regulation by adopting a variable frequency speed regulator, so that the cutting particle size of powder is regulated.

2. The centrifugal air classifier for ultrafine powders according to claim 1, characterized in that: the cross section of the twisted blade (12) is formed by sequentially connecting a blade front edge (14), a blade back (15), a blade rear edge (17) and a blade basin (16) end to end, wherein the blade front edge (14) and the blade rear edge (17) are formed by circular arcs, and the blade back (15) and the blade basin (16) are formed by curvature-variable smooth curves.

3. The centrifugal air classifier for ultrafine powders according to claim 1 or 2, characterized in that: the air inlet pipe (1) is provided with a plurality of air inlet pipes, and the air inlet pipes are arranged in an annular equidistant mode by taking a geometric central axis of the grading chamber (2) as an axis and are connected with the grading chamber (2) in a tangential mode.

4. The centrifugal air classifier for ultrafine powders according to claim 1 or 2, characterized in that: and a plurality of lattice bars are uniformly arranged on the upper surface of the upper powder dispersion disc (11) in the circumferential direction.

5. The centrifugal air classifier for ultrafine powders according to claim 1 or 2, characterized in that: the feeding hopper is communicated with the air-closed feeding device, the coarse powder discharge port (9) is communicated with the air-closed discharge device, and the air outlet pipe (7) is communicated with the dust removal recovery device.

Technical Field

The invention relates to a powder grading device, in particular to a centrifugal air classifier for superfine powder, which is suitable for dry-type grading of mineral powder and other powder materials and belongs to the field of powder preparation.

Background

The superfine powder is widely applied to various fields of fine chemical engineering, materials, building materials, mineral processing, medicines, foods and the like. With the development of national economy and science and technology, various industries put forward higher and higher requirements on ultrafine powder, the ultrafine powder is required to be extremely fine, and the particle size distribution is narrow, so that higher requirements are put forward on the powder classification technology. The centrifugal air classifier is provided with a classifying impeller rotating at a high speed to form a centrifugal flow field of a forced vortex, the centrifugal acceleration of particles in the flow field is hundreds times or even thousands times of the gravity acceleration, the particles are classified according to the particle size under the action of the centrifugal force and the fluid drag force generated by the rotating impeller, the classified particle size is smaller, the classification precision is higher, the centrifugal air classifier is most widely applied in industrial production, and the centrifugal air classifier is a main technical way for classifying superfine powder.

The blade geometrical characteristics of the wind guide blade cascade and the grading impeller in the centrifugal air classifier are key factors influencing the turbulent fluctuation characteristics of gas-solid two-phase flow, and directly influence the turbulent fluctuation strength of a grading space flow field and the strength of vortex motion between blade channels. The existing superfine powder centrifugal air classifier adopts straight blades or circular arc blades with equal curvature, for example, the Chinese patent application CN104703717A discloses a rotary classifier which adopts bent straight plate type rotating blades; the Chinese patent application CN106031901A discloses a cage-type rotor vortex superfine powder concentrator, wherein an annular fixed fluid director and a cage-type rotor both adopt a strip plate shape; the chinese patent application CN102225396A discloses a vortex air classification system, which adopts straight blades or equal curvature streamline blades. The classifier adopting the straight blades or the circular arc-shaped blades with equal curvature has the advantages that the turbulence intensity of a classification space flow field is high, the swirling motion in a flow channel between the blades is strong, the energy loss of secondary flow is high, meanwhile, the velocity gradient in the flow channel is too large, strong disturbance is generated on the motion behavior of particle separation, and the improvement of the classification precision of the superfine powder and the reduction of the classification lower limit are limited.

Disclosure of Invention

The invention aims to provide a centrifugal air classifier for ultrafine powder, which can reduce the turbulent fluctuation intensity of gas-solid two-phase flow in a classification space, improve the dry classification precision of the ultrafine powder and provide an effective device for fine classification of the ultrafine powder.

In order to achieve the purpose, the invention adopts the technical scheme that: a centrifugal air classifier for superfine powder comprises an air inlet pipe, a classifying chamber, a top cover, an air guide blade grid, a classifying impeller, a fine powder transfer chamber, a conical shell, a coarse powder discharge port and an air outlet pipe; the air intake pipe along the tangential with hierarchical room is connected, the top cap is located hierarchical room top, and the top cap includes feed funnel, the wind-guiding cascade is fixed in hierarchical room through ring groove, hierarchical impeller is located hierarchical room center, is the cage form, including upper portion powder dispersion impeller, the annular supporting disk in lower part and the vertical fixation blade between upper portion powder dispersion impeller and the annular supporting disk in lower part, the wind-guiding cascade with hierarchical impeller installs with one heart, forms annular hierarchical space between the two, the wind-guiding cascade with hierarchical impeller constitutes airflow channel by a plurality of turn-knob blade around its geometric axis annular equidistance is arranged respectively. The twisted blade is in a combined shape of radial bending and axial twisting, wherein the radial bending is non-equal curvature smooth bending, the bending angle range is 5-90 degrees, the twisting angle range is 5-60 degrees, the installation angle gamma of the twisted blade ranges from 30-90 degrees,

the fine powder chamber transfer chamber is positioned in the conical shell and is hermetically connected with the bottom of the grading impeller, the air outlet pipe is tangentially connected with the fine powder transfer chamber and extends out of the conical shell, the coarse powder discharge port is communicated with the bottom of the conical shell,

the grading impeller is fixed on a driving shaft, the driving shaft is connected with the grading chamber through a bearing, the driving shaft penetrates through the fine powder transfer chamber and the conical shell through a sleeve and then is connected with the variable frequency motor through a belt driving device to drive the grading impeller to rotate, and the grading impeller is subjected to stepless speed regulation by adopting a variable frequency speed regulator, so that the cutting particle size of the powder is regulated.

Preferably, the cross section of the twisted blade is formed by sequentially connecting the front edge, the back edge, the rear edge and the basin end to end, wherein the front edge and the rear edge are both formed by circular arcs, and the back edge and the basin are both formed by variable-curvature smooth curves.

Preferably, the air inlet pipe has a plurality of to hierarchical room geometry axis carries out annular equidistance and arranges as the axle, and all with hierarchical room tangential connection.

Furthermore, a plurality of lattice bars are uniformly arranged on the upper surface of the upper powder dispersion plate in the circumferential direction, and the function of impacting and dispersing materials is achieved.

Further, the feeding hopper is communicated with the air-closed feeding device, the coarse powder discharge port is communicated with the air-closed discharge device, and the air outlet pipe is communicated with the dust removal recovery device.

During operation, the dust removal recovery device sucks air in the classifier through the air outlet pipe, air required in the classification process is sucked and enters through the air inlet in a negative pressure mode, the air speed is controlled by adjusting the rotating speed of a draught fan in the dust removal recovery device, powder materials are fed onto a dispersion disc on the upper portion of a classification impeller through an air-closing feeding device, the dispersion disc rotates at a high speed, the powder is thrown out from the periphery, the powder uniformly falls into an annular classification space and is in vertical contact with rotating airflow, and the powder is subjected to the comprehensive effect of centrifugal force and airflow drag force generated by rotation of the classification impeller to realize separation according to the granularity. The particles of the finer powder body are subjected to larger air flow drag force and pass through a passage between blades of the grading impeller to enter the grading impeller along with the air flow, an annular supporting disk at the lower part of the grading impeller is hermetically connected with a transfer chamber of the fine powder chamber, and the air flow and the fine powder are sucked into a dedusting recovery device through an air outlet pipe tangentially connected with the fine powder transfer chamber; the coarse powder particles are subjected to a large centrifugal force, spirally fall along the periphery of the annular grading space, enter the conical shell and are discharged from the coarse powder discharge port through the air-closed discharge device.

Has the advantages that: the centrifugal air classifier for ultrafine powder provided by the invention adopts the blade design of bending and twisting combined modeling, reduces the size and strength of vortices between blades of the air guide blade grid and the classifying impeller, reduces the turbulent intensity of a classifying space, weakens the disturbance of channel vortices on the motion behavior of separating powder particles, improves the classifying precision of ultrafine powder, reduces the lower limit of classification, and provides an effective device for dry fine classification of ultrafine powder.

Drawings

FIG. 1 is a schematic three-dimensional structure of a centrifugal air classifier for ultrafine powders according to the present invention;

FIG. 2 is a schematic structural view of a classifying impeller;

FIG. 3 is a schematic structural view of a twisted blade;

FIG. 4 is a schematic cross-sectional profile of a cambered vane;

FIG. 5 is a schematic view of the stagger angle γ of a cambered vane;

in the figure, 1 an air inlet pipe, 2 a grading chamber, 3 a top cover, 4 air guide blade grids, 5 a grading impeller, 6a fine powder transfer chamber, 7 an air outlet pipe, 8 a conical shell, 9 a coarse powder discharge port, 10 a driving shaft, 11 an upper powder dispersion disc, 12 a cranked blade, 13 a lower annular supporting disc, 14 a blade front edge, 15 a blade back, 16 a blade basin and 17a blade rear edge.

Detailed Description

The present invention will be further described with reference to the accompanying drawings.

As shown in figure 1, the centrifugal air classifier for ultrafine powder comprises an air inlet pipe 1, a classifying chamber 2, a top cover 3, an air guide blade grid 4, a classifying impeller 5, a fine powder transfer chamber 6, a conical shell 8, a coarse powder discharge port 9 and an air outlet pipe 7. The air inlet pipes 1 are annularly and equidistantly arranged by taking a geometric central axis of the grading chamber 2 as an axis and are connected with the grading chamber 2 in a tangential direction; the top cover 3 is positioned above the grading chamber 2 and comprises a feeding funnel, and the feeding funnel is communicated with the air-closed feeding device; the air guide blade grid 4 is fixed in the grading chamber 2 through an annular clamping groove, and the grading impeller 5 is positioned in the center of the grading chamber 2; the conical shell 8 is arranged at the lower part of the grading chamber 2, the fine powder chamber transfer chamber 6 is positioned in the conical shell 8 and is hermetically connected with the bottom of the grading impeller 5, one end of the air outlet pipe 7 is tangentially connected with the fine powder transfer chamber 6 and extends out of the conical shell 8, and the other end of the air outlet pipe 7 is communicated with the dedusting recovery device; one end of the coarse powder discharge port 9 is communicated with the bottom of the conical shell 8, and the other end of the coarse powder discharge port 9 is communicated with the air-tight discharge device; the grading impeller 5 is fixed on a driving shaft 10, the driving shaft 10 is connected with the grading chamber 2 through a bearing, penetrates through the fine powder transfer chamber 6 and the conical shell 8 through a sleeve, and is connected with a variable frequency motor through a belt driving device so as to drive the grading impeller 5 to rotate, and stepless speed regulation is carried out on the grading impeller 5 through a variable frequency speed regulator.

As shown in fig. 1, the air guiding cascade 4 and the classifying impeller 5 are concentrically installed, an annular classifying space is formed between the air guiding cascade 4 and the classifying impeller 5, the air sucked from the air inlet pipe 1 flows through the air guiding cascade 4 and then forms a rotating airflow field in the annular classifying space, the feeding hopper is positioned right above the upper powder dispersion plate 11, the material falls into the annular classifying space from the upper part through the powder dispersion plate 11, the material is subjected to the comprehensive action of centrifugal force and airflow drag force generated by the rotation of the classifying impeller 5 to realize separation according to particle size, and finer powder particles pass through passages among the blades of the classifying impeller 5 along with the airflow and enter the classifying impeller 5, then enter the fine powder transfer chamber 6 and then are sucked into the dust removal and recovery device through the air outlet pipe 7; the coarse powder particles are subjected to a large centrifugal force, spirally fall along the periphery of the annular classification space, enter the conical shell 8, and are discharged from a coarse powder discharge port 9 through an air-closed discharge device.

As shown in fig. 2, the classifying impeller 5 is in a cage shape, and includes an upper powder dispersing plate 11, a lower annular supporting plate 13, and a twisted blade 12 vertically fixed between the upper powder dispersing plate 11 and the lower annular supporting plate 13; a plurality of grid bars are uniformly arranged on the upper surface of the upper powder dispersion disc 11 in the circumferential direction, three circles of division bars are arranged from inside to outside by taking the center of the disc body as a circle center, and the division bars of two adjacent circles are distributed in a staggered manner to play a role in impacting and dispersing materials; the lower annular supporting plate 13 is hollow, a threaded hole for connecting the driving shaft 10 is formed in the center of the plate body of the lower annular supporting plate 13, and the twisted blades 12 are uniformly arranged in an annular mode around the axis of the grading impeller 5.

As shown in fig. 2 and 3, the classifying impeller 5 has an airflow channel formed by a plurality of twisted blades 12 arranged annularly and equidistantly around the axis thereof, and the air guide blade cascade 4 also has an airflow channel formed by a plurality of twisted blades 12 arranged annularly and equidistantly around the axis thereof, and the introduction of the twisted blades 12 can reduce the turbulence intensity among the blade channels, reduce the energy loss and improve the classifying precision.

As shown in fig. 3, the twisted blade 12 exhibits a combined shape of radial bending and axial twisting, in which the radial bending is a non-equal curvature smooth bending, the bending angle ranges from 5 ° to 90 °, and the twisting angle ranges from 5 ° to 60 °. The bending angle and the twisting angle can be flexibly adjusted according to the requirements of working conditions.

As shown in fig. 4, the cross section of the twisted blade 12 is formed by sequentially connecting a blade leading edge 14, a blade back 15, a blade trailing edge 17 and a blade basin 16 end to end, wherein the blade leading edge 14 and the blade trailing edge 17 are both formed by circular arcs, and the blade back 15 and the blade basin 16 are both formed by a variable curvature smooth curve, which may be generated by a curve function or by spline curve fitting.

As shown in fig. 5, the installation angle γ (the included angle of the blade leading edge 14 with respect to the position of the blade trailing edge 17) of the twisted blade 12 ranges from 30 ° to 90 °.

In the classification process, a centrifugal air classifier for superfine powder is in a negative pressure air inlet state, the dust removal recovery device sucks air in the classifier through an air outlet pipe, air required in the classification process is sucked and enters from the air inlet 1 through negative pressure suction, and the air speed is controlled by adjusting the rotating speed of an induced draft fan in the dust removal recovery device through frequency conversion. The sucked wind is directionally rectified by the wind guide blade cascade 4 with the twisted blades, and a rotary airflow field is formed in an annular grading space formed by the wind guide blade cascade 4 and the grading impeller 5. The powder material is fed to the upper powder dispersion plate 11 of the grading impeller 5 through the feeding funnel by the air-closed feeding device, and the lattice strips distributed on the upper powder dispersion plate 11 play a role in impacting and dispersing the material. The upper powder dispersing disk 11 rotates at a high speed to throw out the powder from the periphery, the powder uniformly falls into the annular grading space and is vertically contacted with the rotating airflow, and the powder is subjected to the comprehensive action of airflow drag force and centrifugal force generated by the rotation of the grading impeller to realize the separation according to the granularity. The particles of the finer powder body are subjected to larger air flow drag force and pass through passages among bent blades of the classifying impeller 5 along with the air flow to enter the classifying impeller, an annular supporting disk at the lower part of the classifying impeller 5 is hermetically connected with a fine powder chamber transfer chamber 6, and the air flow and the fine powder entering the inner cavity of the classifying impeller 5 through the blades are sucked into a dust removal recovery device through an air outlet pipe 7 tangentially connected with the fine powder chamber 6; the coarse powder particles are subjected to a large centrifugal force, spirally fall along the periphery of the annular classification space, enter the conical shell 8, and are discharged from a coarse powder discharge port 9 through an air-closed discharge device. The divided particle size of the powder classification is adjusted by changing the air speed and the rotating speed of the classification impeller.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.