An inner circulation precision control classifier and an inner circulation control method thereof

Abstract

The application discloses an inner circulation precision control classifier and an inner circulation control method thereof, which comprises a fine classifier and an inner circulation control device arranged at the lower part of the whole equipment. The inner circulation control device comprises an inner circulation transmission mechanism, a control device shaft system, an inner circulation control disc, a wind control volute, a central feeding device and a material return control device. The inner circulation transmission mechanism drives the control device shaft system to drive the inner circulation control disc to rotate. A wind control ring concentric with the inner circulation control disc is arranged close to the inner circulation control disc. The wind control ring is fixed on the inner wall of the wind control volute. An inner circulation control area is formed between the inner circulation control disc and the wind control ring. The feeding port of the central feeding device is arranged above the inner circulation control disc in an eccentric manner to realize central feeding. The material return control device is arranged at the lower part of a medium-coarse powder return hopper of the fine classifier to guide the medium-coarse powder out of the equipment. The application can realize inner circulation precision control, reduce the power consumption of the matched circulating fan and the classifier body and improve the separation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mineral processing classification, in particular to an internal circulation precise control classifier and an internal circulation control method thereof. BACKGROUND

[0002] In the process of grinding classification in the field of mineral processing, the circulating load refers to the ratio of the amount of material returned to the classifier to the amount of finished product, and the internal circulating load refers to the ratio of the amount of material that cannot be brought into the classification zone by the classification equipment itself to the amount of finished product without considering the grinding equipment.

[0003] In a combined \ semi-final grinding system composed of an extrusion grinding device, the classifier matched with the fine grinding part is used. The material is fed into the classifier from the upper feeding channel by the lifting device, and then is thrown and scattered by the scattering disc installed on the cage rotor for pre-dispersion, and then falls into the classification zone between the static blade and the cage rotor to complete the classification. Under the requirement of a specific finished product fineness, the speed of the cage rotor is constant, and since the scattering disc and the cage rotor are fixed together and driven by the same drive, the speed of the scattering disc cannot be adjusted independently. The above two reasons lead to the following problems:

[0004] (1) All the material enters the classification zone, i.e. the internal circulating load is 100%, which is uncontrollable;

[0005] (2) The speed of the scattering disc is uncontrollable, the pre-dispersion state of the material is poor, and the subsequent separation efficiency is affected.

[0006] The above problems result in the following consequences: the internal circulating load is 100%, which is uncontrollable, the concentration of the material in the classification zone is high, the high concentration of the material causes high system resistance, the power consumption of the matched circulating fan increases, and the unreasonable scattering mode and the concentration of the material cause the power consumption of the classifier body to be also high. Through the power consumption statistics of multiple classifiers and matched circulating fans, when grinding PO42.5 cement (medium grindability), the unit power consumption of the classifier drive motor is about 0.3-0.6 kWh / t, and the unit power consumption of the matched circulating fan is usually > 2 kWh / t. At the same time, the separation efficiency is low, and under the normal working condition of the external circulating load, it is usually ≤ 65%. SUMMARY

[0007] In order to solve the problems of high power consumption of the circulating fan and the classifier body and low separation efficiency caused by the uncontrollable internal circulation of the classifier in the prior art, the present application provides an internal circulation precise control classifier and an internal circulation control method thereof, which can realize internal circulation precise control, improve the pre-dispersion state, thereby reducing the power consumption of the matched circulating fan and the classifier body, and improving the separation efficiency.

[0008] The present invention is implemented as follows: an internal circulation precision control classifier includes a fine classifier located at the upper part of the entire equipment and used to produce finished products; it also includes an internal circulation control device located at the lower part of the entire equipment and used to realize precise control of internal circulation and pre-dispersion of materials.

[0009] The internal circulation control device includes an internal circulation transmission mechanism, a control device shaft system, an internal circulation control disc, an air control volute, a central feeding device, and a return material control device. The internal circulation transmission mechanism drives the control device shaft system to rotate, and the top of the control device shaft system is connected to the internal circulation control disc. The air control volute surrounds the internal circulation control device, with air inlets distributed on its sides and a coarse powder outlet at its bottom. An air control ring, concentric with the internal circulation control disc, is located near the internal circulation control disc and is fixed to the inner wall of the air control volute. The air control ring has a frustum-shaped thin-walled structure, forming an internal circulation control zone between the internal circulation control disc and the air control ring. The feeding port of the central feeding device is located above the internal circulation control disc and is eccentrically arranged, so that the material drop point of the central feeding device is located at the center of the internal circulation control disc, realizing central feeding. The return material control device is located at the lower part of the medium and coarse powder return cone of the fine classifier and is used to discharge the medium and coarse powder after being sorted by the fine classifier from the equipment.

[0010] Preferably, the eccentricity of the central feeding device is E, the distance from the feeding point of the central feeding device to the inner circulation control disk in the height direction is L, the installation angle of the central feeding device with respect to the vertical direction is α, and the radius of the inner circulation control disk is R; the acceleration caused by the gravity of the material is negligible, and central feeding is achieved when the material moves equal distances in the horizontal and vertical directions, E=L×tanα, and according to the material's angle of repose, L=(0.05~0.6)×R;

[0011] Therefore, E = (0.05~0.6) × R × tanα.

[0012] Preferably, the internal circulation control disk has a ring-shaped stacked structure, consisting of a material spreading impeller, a deceleration ring, and a dispersion sorting control impeller from top to bottom. The material spreading impeller is composed of multiple arrayed rotating blades, with the rotating blades forming an angle β with the horizontal plane, and the direction of β being consistent with the direction of rotation. The lower part of the material spreading impeller is a receiving plate, with the edge of the receiving plate surrounding the deceleration ring, forming a weir between the deceleration ring and the receiving plate. The dispersion sorting control impeller is located below the outer circumference of the deceleration ring, and is composed of multiple arrayed rotating blades, with the rotating blades forming an angle γ with the horizontal plane, and the direction of γ being consistent with the direction of rotation. The rotating blades are fixed to the deceleration ring by bolts and circumferentially welded connecting plates.

[0013] Further preferably, each of the rotating vanes is composed of a sector plate, a material lifting boss and a material blocking plate, the material lifting boss is a plurality of pieces, welded at the high end side of the sector plate, the material blocking plate is located between two adjacent sector plates, and the upper and lower ends of the material blocking plate are connected with the two adjacent sector plates respectively to block the gap between the two sector plates.

[0014] Preferably, a dustproof cap is arranged at the top of the inner circulation control disc.

[0015] Preferably, the material returning control device comprises a material guiding cone one, a material guiding cone two, a material distributing cone, a material returning pipe joint and a material returning chute, the material guiding cone one is installed inside the medium-coarse powder returning cone hopper, the material guiding cone two is concentrically connected above the material guiding cone one, the top angle of the material guiding cone two is larger than that of the material guiding cone one, and the two together form a central material guiding cone; an annular material area for collecting medium-coarse powder is formed between the central material guiding cone and the medium-coarse powder returning cone hopper, a plurality of material distributing cones are uniformly arranged in the circumferential direction in the annular material area, the material distributing cone is formed by two plates stacked together in a ridge shape, the annular material area is divided into a plurality of hopper-shaped material areas by the material distributing cone, each hopper-shaped material area is provided with a material returning pipe joint at the bottom, the material returning pipe joint is in the shape of a funnel with the upper part larger and the lower part smaller, and the lower end of the material returning pipe joint is connected with the material returning chute.

[0016] Further preferably, the lower end of the material returning chute is connected with a medium-coarse powder returning box located outside the air control volute, the medium-coarse powder returning box is arranged at the staggered empty space of the air inlet, and an observation door is arranged on the medium-coarse powder returning box.

[0017] Preferably, the inner circulation control device is a reverse rotary device, and the inner circulation transmission mechanism is a lower transmission, which is located at the bottom of the inner circulation control device and connected with the bottom end of the control device shaft system.

[0018] Further preferably, the lower transmission is installed on the control device fixed beam by bolts, and the control device fixed beam is a steel frame, so that the force of the inner circulation control device is transmitted to the foundation and does not superimpose vibration with the air control volute.

[0019] Still further preferably, the lower transmission comprises a transmission motor, a lower transmission support and a shaft coupling, the transmission motor is located at the bottom and fixed with the lower transmission support by bolts, the lower transmission support is fixed with the control device fixed beam, and the transmission motor is connected with the main shaft of the control device shaft system through the shaft coupling.

[0020] Preferably, the control device shafting comprises a main shaft, a reverse bearing seat, a shaft sleeve, an upper bearing seat and a pull rod support, the main shaft is located in the shaft sleeve, the lower part of the main shaft is supported by bearing assembly one installed in the reverse bearing seat, and the upper part of the main shaft is centered by bearing assembly two installed in the upper bearing seat, the two ends of the shaft sleeve are connected with the reverse bearing seat and the upper bearing seat respectively to form an integral whole, the pull rod support is provided with a plurality of pull rod supports arranged in the radial direction around the upper bearing seat, one end of the pull rod support is connected with the upper bearing seat, and the other end of the pull rod support is connected with the control air volute, and the reverse bearing seat is fixed with the control device fixed beam.

[0021] Further preferably, an anti-abrasion sleeve is sleeved on each pull rod support.

[0022] Preferably, the control device shafting is coincided with the center of the whole device, the lower part of the control device shafting is provided with a diagonal brace, and the other end of the diagonal brace is connected with the control device fixed beam.

[0023] Preferably, the air inlet is in the form of tangential air inlet or vertical air inlet, an air inlet adjusting valve is arranged on the air inlet, a plurality of anti-abrasion lining plates made of flat steel are welded on the inner wall of the control air volute in the axial direction, and each anti-abrasion lining plate is perpendicular to the control air volute.

[0024] Preferably, the coarse powder outlet is arranged in the form of two, four, six or other forms of uniform distribution or non-uniform distribution, and the slope is arranged between the coarse powder outlets to avoid material accumulation.

[0025] Preferably, the fine classifier comprises a fine classifier transmission mechanism, a fine classifier rotating mechanism, a static blade, a fine classifier shell and a medium-coarse powder return cone, the fine classifier transmission mechanism is located at the top of the fine classifier shell and connected with the fine classifier rotating mechanism, the top end of the fine classifier rotating mechanism is fixed on the top platform of the fine classifier shell through a flange plate, the static blade is distributed around the fine classifier rotating mechanism at the same height and concentrically, the static blade and the fine classifier rotating mechanism are located in the middle section of the fine classifier shell, the top end of the medium-coarse powder return cone is connected with the bottom end of the static blade, and the bottom end of the fine classifier shell is connected with the control air volute to form a dust-containing air flow channel.

[0026] The internal circulation control method of the internal circulation precision control classifier is that the material to be sorted is fed into the upper part of the internal circulation control disc by the central feeding device, the internal circulation transmission mechanism drives the control device shafting to drive the internal circulation control disc to rotate, so that the material falling thereon is uniformly entered into the internal circulation control area, and the sorting air flow enters the control air volute through the air inlet and moves upward into the internal circulation control area; the control particles with a particle size of d, the coarse particles with a particle size greater than d and the fine particles with a particle size less than d in the material to be sorted are under the joint action of the internal circulation control disc and the control air ring, different particles are subjected to their own gravity F g, centrifugal force F generated by the inner circulation control device c , air drag force F generated by the circulating fan d different residence times, when the vertical direction residence time t v of the particle is greater than the horizontal direction residence time t h , the particle of this size is settled, and the inner circulation load is increased; when the vertical direction residence time t v of the particle is less than the horizontal direction residence time t h , the particle of this size passes through the inner circulation control area, and the inner circulation load is decreased; by controlling the rotating speed of the inner circulation control disc or the structure of the air control ring, the value of the control particle size d is changed, so that the amounts of coarse particles and fine particles are changed, to realize the precise control of the inner circulation load.

[0027] Preferably, the calculation formula of the control particle size d is as follows:

[0028]

[0029] In the formula, d is the control particle diameter, m; γ m is the material density, kg / m 3 ; γ e is the gas density, kg / m 3 ; v is the gas dynamic viscosity, m 2 / s; Q is the working air volume of the circulating fan, m 3 / s; R is the radius of the inner circulation control disc, m; n is the rotating speed of the inner circulation control disc, r / s; H is the height of the inner circulation control area, m; D is the width of the inner circulation control area, m; and δ is the inclination angle of the air control ring.

[0030] The present application has the advantages and positive effects that:

[0031] The present application realizes the precise and controllable inner circulation through the adjustment of the inner circulation control device, and the inner circulation adjustment device is a variable frequency stepless speed regulation, so that the inner circulation load required in various working conditions can be realized according to the requirements of the grinding and sorting process. Under the reasonable inner circulation load, the settlement of coarse particles at the inner circulation control device is accelerated, the material concentration in the sorting area is reduced, the system resistance is reduced, and the power consumption of the circulating fan is reduced; in combination with the center material scattering mode of the inner circulation control device, the power consumption of the fine classifier is also reduced; through the statistics of the power consumption of the classifier and the matching circulating fan of the present application, when grinding PO42.5 cement (medium easy grindability), the unit power consumption of the classifier is about 0.1-0.3 kWh / t, and the unit power consumption of the matching circulating fan is less than 1.5 kWh / t, and at the same time, under the normal working condition of the outer circulation load, the sorting efficiency is greater than 70%, which is greatly improved compared with the traditional classifier with uncontrollable inner circulation. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application, the drawings needed to be used in the specific embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are some specific embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0033] Figure 1 is the internal structure schematic diagram of the internal circulation precision control classifier of the present application;

[0034] Figure 2 is the structure schematic diagram of the internal circulation transmission mechanism, control device shaft system and internal circulation control disc cooperation of the present application;

[0035] Figure 3 is the structure schematic diagram of the return material control device of the present application;

[0036] Figure 4 is Figure 1 A-A view in the figure;

[0037] Figure 5 is the gas and material flow direction diagram of the internal circulation control zone of the present application;

[0038] Figure 6 is the realization principle diagram of the internal circulation control method of the present application;

[0039] Figure 7 is the particle distribution diagram in the equipment of the CFD transient analysis of the present application.

[0040] 1, fine classifier transmission mechanism; 2, fine classifier shell; 3, fine classifier rotating mechanism; 4, stationary blade; 5, return material control device; 6, center feeding device; 7, air control ring; 8, air control volute; 9, control device shaft system; 10, control device fixed beam; 11, under transmission; 12, internal circulation control disc; 13, inclined support; 14, medium-coarse powder return material box; 15, coarse powder outlet; 16, dustproof cap; 17, material scattering impeller; 18, speed reduction ring; 19, dispersion and separation control impeller; 191, material lifting boss; 192, fan-shaped plate; 193, material blocking plate; 20, shaft sleeve; 21, reversed bearing seat; 22, shaft coupling; 23, under transmission support; 24, transmission motor; 25, upper bearing seat; 26, main shaft; 27, pull rod support; 28, wear-resistant sleeve; 29, medium-coarse powder return material conical hopper; 30, material guiding cone one; 31, material guiding cone two; 32, material distributing cone; 33, return material pipe interface; 34, return material upper sliding pipe; 35, return material lower sliding pipe; 36, primary air adjusting valve; 37, primary air inlet; 38, wear-resistant lining plate; 39, secondary air adjusting valve; 40, secondary air inlet; 41, internal circulation control zone. Specific embodiment

[0041] The technical solutions of the present application will be described clearly and completely in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0043] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] Embodiments

[0045] Please refer to Figures 1-5 The embodiment of the present application provides an internal circulation precise control classifier, which comprises a fine classifier. The fine classifier is located at the upper part of the whole device, and is used to produce finished products. It also comprises an internal circulation control device, which is located at the lower part of the whole device, and is used to realize internal circulation precise control and material pre-dispersion.

[0046] The inner loop control device comprises an inner loop transmission mechanism, a control device shaft system 9, an inner loop control disc 12, an air control volute 8, a central feeding device 6 and a material return control device 5. The inner loop transmission mechanism drives the control device shaft system 9 to rotate. The top end of the control device shaft system 9 is connected with the inner loop control disc 12, and the inner loop control disc 12 rotates at variable frequency under the driving of the control device shaft system 9. The air control volute 8 surrounds the periphery of the inner loop control device. The side surface of the air control volute 8 is provided with an air inlet, and the bottom end is provided with a coarse powder outlet 15 for discharging the coarse powder generated after the inner loop control. The coarse powder outlet 15 avoids the lower transmission and avoids internal material accumulation through reasonable arrangement. A concentric air control ring 7 is arranged near the inner loop control disc 12. The air control ring 7 is fixed on the inner wall of the air control volute 8. The air control ring 7 is in the form of a circular truncated cone thin wall structure. The height and length of the air control ring 7 can be adjusted. The inner loop control area 41 is formed between the inner loop control disc 12 and the air control ring 7. The inner loop control area 41 is controlled by the cooperation of the inner loop control disc 12 and the air control ring 7. The feeding port of the central feeding device 6 is located above the inner loop control disc 12 and is arranged eccentrically, so that the dropping point of the central feeding device 6 is located at the center of the inner loop control disc 12, thereby realizing the central feeding. The material return control device 5 is located below the medium-coarse powder return cone hopper 29 of the fine classifier, and is used for uniformly guiding the medium-coarse powder selected by the fine classifier into the plurality of medium-coarse powder return boxes 14 arranged on the air control volute 8.

[0047] The inner loop control device is a reverse rotary device. The inner loop transmission mechanism is a lower transmission 11. The lower transmission 11 is located at the bottom of the inner loop control device. The lower transmission 11 is connected with the bottom end of the control device shaft system 9. The lower transmission 11 is bolted on the control device fixed beam 10. The control device fixed beam 10 is a type steel frame, which transmits the stress of the inner loop control device to the foundation and prevents the vibration superposition with the air control volute 8.

[0048] Referring to Figure 1 and Figure 2 , the lower transmission 11 comprises a transmission motor 24, a lower transmission support 23 and a shaft coupling 22. The transmission motor 24 is located at the bottom and is fixed with the lower transmission support 23 by bolts. The lower transmission support 23 is fixed with the control device fixed beam 10. The transmission motor 24 is connected with the main shaft 26 of the control device shaft system 9 through the shaft coupling 22, drives the main shaft 26 to rotate at the required speed and realizes the variable frequency speed regulation. The power source of the lower transmission 11, i.e. the transmission motor 24, can be a combination of a variable frequency speed reduction motor, a permanent magnet direct drive motor, a variable frequency motor and a speed reducer.

[0049] The control device shaft 9 coincides with the center of the whole device, and in order to prevent the verticality from deviating during operation, inclined braces 13 are arranged around the lower part of the control device shaft 9, and the other ends of the inclined braces 13 are connected with the control device fixed beam 10.

[0050] The control device shaft 9 comprises a main shaft 26, a reversed bearing seat 21, a shaft sleeve 20, an upper bearing seat 25 and a pull rod support 27. The main shaft 26 is located in the shaft sleeve 20, the lower part of the main shaft 26 is supported by bearing assembly one installed in the reversed bearing seat 21, and the upper part of the main shaft 26 is centered by bearing assembly two installed in the upper bearing seat 25. The shaft sleeve 20 is connected with the reversed bearing seat 21 and the upper bearing seat 25 at both ends to form a whole. The pull rod supports 27 are arranged in multiple numbers and are arranged in the radial direction around the upper bearing seat 25. One end of the pull rod support 27 is connected with the upper bearing seat 25, and the other end is connected with the control air volute 8 through bolt fixing to ensure the stable operation of the inner circulation control disc 12. An anti-wear sleeve 28 is sleeved on each pull rod support 27 to slow down the wear of the pull rod support 27 caused by the dust-containing airflow. The reversed bearing seat 21 is fixed with the control device fixed beam 10, so that the control device fixed beam 10 bears the weight of the whole inner circulation control device and additional force during operation.

[0051] The inner circulation control disc 12 is a ring-shaped laminated structure, and from top to bottom, it comprises a material scattering impeller 17, a speed reduction ring 18 and a dispersion and separation control impeller 19. The material scattering impeller 17 is located at the uppermost part and is composed of a plurality of arrayed rotating blades one. The rotating blades one form an angle β with the horizontal plane, and the direction β is consistent with the rotating direction. The lower part of the material scattering impeller 17 is a material receiving flat plate, and the edge of the material receiving flat plate surrounds the speed reduction ring 18, so that a weir is formed between the speed reduction ring 18 and the material receiving flat plate, which can slow down the material flow rate and improve the material dispersion uniformity. The dispersion and separation control impeller 19 is located at the lower part of the outer circumferential surface of the speed reduction ring 18. The dispersion and separation control impeller 19 is composed of a plurality of arrayed larger rotating blades two. The rotating blades two form an angle γ with the horizontal plane, and the direction γ is consistent with the rotating direction. The bottom of the rotating blades two is fixed through bolt and circumferentially distributed welding of the connecting plate of the speed reduction ring 18. Each rotating blade two is composed of a sector plate 192, a material lifting boss 191 and a material blocking plate 193. The material lifting boss 191 is radially welded on the high end side of the sector plate 192 to improve the material dispersion. The material blocking plate 193 is located between the adjacent two sector plates 192, and the upper and lower ends of the material blocking plate 193 are connected with the adjacent two sector plates 192 respectively to block the gap between the two sector plates 192 to prevent material leakage and assist the sector plate 192 to generate radial driving airflow.

[0052] A dustproof cap 16 is arranged at the top of the inner circulation control disc 12 to reduce the wear of the shaft end caused by the feeding material.

[0053] The inner circulation control disc 12 has three layers of the material scattering impeller 17, the speed reduction ring 18 and the dispersion and separation control impeller 19, but for high-moisture and high-viscosity materials, the dispersion effect should be improved by increasing the number of layers or changing the arrangement form to ensure the inner circulation control ability.

[0054] Referring to Figure 1 In order to ensure that the material falling point is located at the center of the inner circulation control disc 12 and realize the center feeding, an eccentricity E should be designed, the eccentricity of the center feeding device 6 is E, the distance between the material falling point of the center feeding device 6 and the height direction of the inner circulation control disc 12 is L, the installation inclination angle of the center feeding device 6 with the vertical direction is α, and the radius of the inner circulation control disc 12 is R.

[0055] The acceleration caused by the gravity of the material is negligible, the center feeding is realized when the material moves in the horizontal direction and the height direction by equal distance, E = L × tan α, and according to the material pile angle, L = (0.05-0.6) × R; therefore, E = (0.05-0.6) × R × tan α.

[0056] The center feeding device 6 is a chute, a slide or a scraper feeder and the like. The center feeding device 6 is fixed through the fixed sleeve on the control air volute 8.

[0057] Referring to Figure 1 and Figure 4 , the air inlet is located at the lower part of the control air volute 8, the air inlet is two or multiple, the air inlet form is tangential air inlet or vertical air inlet and the like, and the air inlet is provided with an air inlet adjusting valve. Two air inlets are arranged in the embodiment, which are a primary air inlet 37 and a secondary air inlet 40, the primary air inlet 37 is connected with the control air volute 8 in the tangential direction, the secondary air inlet 40 is located in the 180° rotation direction of the primary air inlet 37 and is also connected with the control air volute 8 in the tangential direction, the primary air inlet 37 is provided with a primary air inlet adjusting valve 36, the secondary air inlet 40 is provided with a secondary air inlet adjusting valve 39, and the dust-containing airflow in the control air volute 8 is uniformly controlled through the control of the two adjusting valves. A plurality of wear-resistant lining plates 38 made of flat steel are welded on the inner wall of the control air volute 8 in the axial direction, each wear-resistant lining plate 38 is perpendicular to the control air volute 8, and a low wind speed area is generated on the inner wall to realize wear resistance.

[0058] The coarse powder outlet 15 is located at the bottom end of the control air volute 8, and the arrangement form can be two, four, six or non-uniform distribution and the like, and the slope is arranged between the coarse powder outlets 15 to avoid material accumulation.

[0059] Referring to Figure 1 , Figure 3 and Figure 4The return material control device 5 comprises a guide cone 1, a guide cone 2, a distribution cone 3, a return pipe interface 4, and a return chute. The guide cone 1 is installed inside the medium-coarse powder return cone hopper 29. The guide cone 2 is concentrically connected above the guide cone 1. The top angle of the guide cone 2 is larger than that of the guide cone 1. The two guide cones together form a central guide cone. An annular material area for collecting medium-coarse powder is formed between the central guide cone and the medium-coarse powder return cone hopper 29. A plurality of distribution cones 3 are uniformly arranged in the circumferential direction of the annular material area. The distribution cone 3 is formed by two plates stacked together and has a ridge shape. The distribution cone 3 divides the annular material area into a plurality of hopper-shaped material areas. Each hopper-shaped material area is provided with a return pipe interface 4 at the bottom. The return pipe interface 4 has a funnel shape with a large upper end and a small lower end, which can completely avoid material accumulation. The lower end of the return pipe interface 4 is connected to the return chute. In this embodiment, the return chute is divided into a return upper chute 34 and a return lower chute 35. The lower end of the return pipe interface 4 is connected to the return upper chute 34. The lower end of the return upper chute 34 is connected to the return lower chute 35. The return upper chute 34 and the return lower chute 35 are connected by bolts. The return angle can be adjusted according to the process requirements of the material flow direction. The lower end of the return lower chute 35 is connected to the medium-coarse powder return box 14 located outside the air control volute 8. The medium-coarse powder return box 14 is arranged in the staggered empty space of the air inlet. An observation door is arranged on the medium-coarse powder return box 14 to observe the material condition in the equipment.

[0060] Referring to Figure 1 , the fine classifier comprises a fine classifier transmission mechanism 1, a fine classifier rotating mechanism 3, a stationary blade 4, a fine classifier housing 2, and a medium-coarse powder return cone hopper 29. The fine classifier transmission mechanism 1 is located at the top of the fine classifier housing 2 and is connected to the fine classifier rotating mechanism 3. The top end of the fine classifier rotating mechanism 3 is fixed to the top platform of the fine classifier housing 2 by a flange. The stationary blade 4 is distributed around the fine classifier rotating mechanism 3 at the same height and concentrically. The stationary blade 4 and the fine classifier rotating mechanism 3 are both located inside the middle section of the fine classifier housing 2. The top end of the medium-coarse powder return cone hopper 29 is connected to the bottom end of the stationary blade 4. The bottom end of the fine classifier housing 2 is connected to the air control volute 8 to form a dust-containing air flow passage.

[0061] The sorted material is subjected to the combined action of its own gravity F g , the centrifugal force F c generated by the inner circulation control device, and the air drag F d generated by the circulating fan.

[0062] The sorted material is subjected to the combined action of its own gravity F g : F g = πd 3 (γ m -γ e )g / 6 = 3πdνVv γ e ;

[0063] wherein: d is the diameter of the material particles, m; γ m is the density of the material, kg / m 3 ; γ e is the density of the gas, kg / m 3 ; v is the dynamic viscosity of the gas, m 2 / s; V v is the vertical settling velocity, m / s;

[0064] From the above equation, the vertical settling velocity V v : V v = d 2 g( γ m - γ e ) / (18 v γ e ) is obtained.

[0065] The centrifugal force F c generated by the inner loop control device is: F c = 2 π 3 d 3 ( γ m - γ e ) n 2 R / 3 = 3 π d v V h γ e ;

[0066] wherein: R is the radius of the inner loop control disc 12, m; n is the rotating speed of the inner loop control disc 12, r / s; V h is the horizontal settling velocity, m / s;

[0067] From the above equation, the horizontal settling velocity V h : V h = 2 π 2 d 2 n 2 ( γ m - γ e ) R / (9 v γ e ) is obtained.

[0068] Due to the air drag force F d generated by the circulating fan, the corresponding component velocities W v and W h in the vertical and horizontal directions are generated, and thus the vertical residence time t v and the horizontal residence time t h are obtained;

[0069] The vertical residence time t v : t v = H / (W V -VV ); where H is the height of the inner circulation control zone 41, m;

[0070] Horizontal direction residence time t h : t h = D / (V h -W h ); where D is the width of the inner circulation control zone 41, m;

[0071] For the material controlling the particle size d, t v = t h , then:

[0072]

[0073] When the vertical direction residence time t v is greater than the horizontal direction residence time t h , the particle size d particles settle, and the inner circulation load increases; when the vertical direction residence time t v is less than the horizontal direction residence time t h , the particle size d particles pass through the inner circulation control zone 41, and the inner circulation load decreases; thus, the inner circulation is precisely controlled, and here the particle size d is referred to as the control particle size.

[0074] Referring to Figure 5 , the gas and material flow directions of the inner circulation control zone 41 are shown, the hollow arrows represent the gas flow, the solid arrows represent the material flow, and the particle-filled arrows represent the dust-containing gas flow. The material to be sorted fed by the central feeding device 6 has control particles with a particle size of d2, coarse powder (coarse particles) with a particle size greater than d2, and fine powder (fine particles) with a particle size less than d2. Under the joint action of the inner circulation control disc 12 and the air control ring 7, the coarse powder settles, the fine powder passes through, and the control particles with a particle size of d2 theoretically make circular motion in the inner circulation control zone 41, but the particles collide and wrap each other, part of which enters the fine powder, and part of which enters the coarse powder. When the rotation speed of the inner circulation control disc 12 or the structure of the air control ring 7 changes, the value of the control particle size d2 changes, thereby changing the amounts of the coarse powder and the fine powder, and the inner circulation load is controllable.

[0075] Referring to Figure 6 , the particle state of the inner circulation control zone 41 is shown. It is assumed that the material to be sorted contains three particle sizes d1, d2, and d3, where d1>d2>d3, and δ is the inclination angle of the air control ring 7. When the circulation fan works at the working air volume Q, the ventilation area S (the lateral area of the inverted circular truncated cone) passing through the inner circulation control zone 41 formed between the inner circulation control disc 12 and the air control ring 7 is calculated as follows:

[0076] where S is the ventilation area of the inner circulation control zone 41, m 2 ;

[0077] Wherein: W is the wind speed of the inner circulation control area 41, m / s; Q is the working air volume of the circulation fan, m 3 / s;

[0078]

[0079]

[0080] Combined with the formula for calculating the control particle size d, we have:

[0081]

[0082] In operation, because the structural parameters of the control air ring 7 are fixed, and the speed n of the inner circulation control disc 12 is adjustable, when n is the speed n2, the corresponding control particle size d2 is:

[0083]

[0084] Wherein: n2 is the speed of the inner circulation control disc 12, r / s; d2 is the control particle size when the speed of the inner circulation control disc 12 is n2, m;

[0085] In theory, at this time, the coarse particles with a particle size greater than d2, including d1, cannot pass through the inner circulation control area 41, and the fine particles with a particle size less than d2, including d3, can pass through the inner circulation control area 41.

[0086] When n is the speed n1, the corresponding control particle size d1 is:

[0087]

[0088] Wherein: n1 is the speed of the inner circulation control disc 12, r / s; d1 is the control particle size when the speed of the inner circulation control disc 12 is n1, m;

[0089] In theory, at this time, the coarse particles with a particle size greater than d1 cannot pass through the inner circulation control area 41, and the fine particles with a particle size less than d1, including d2 and d3, can pass through the inner circulation control area 41, and the inner circulation load is reduced.

[0090] When n is the speed n3, the corresponding control particle size d3 is:

[0091]

[0092] Wherein: n3 is the speed of the inner circulation control disc 12, r / s; d3 is the control particle size when the speed of the inner circulation control disc 12 is n3, m;

[0093] Theoretically, the coarse particles with a particle size greater than d3 including d1 and d2 cannot pass through the inner circulation control area 41, and the fine particles with a particle size less than d3 can pass through the inner circulation control area 41, and the inner circulation load is increased.

[0094] When the rotation speed n of the inner circulation control disc 12 cannot meet the inner circulation control requirement, the inner circulation control requirement can also be met by adjusting the parameters such as the inclination angle δ formed by the air control ring 7, the height H of the inner circulation control area 41, and the width D of the inner circulation control area 41.

[0095] During operation, the ground material to be sorted is fed onto the inner circulation control disc 12 by the central feeding device 6. Under the drive of the lower transmission 11, the inner circulation control disc 12 is rotated by the control device shaft system 9. The material falling thereon is uniformly distributed into the outer inner circulation control area 41 under the action of the material scattering impeller 17, the speed reduction ring 18, and the dispersion and separation control impeller 19 in sequence. The separation airflow enters the air control volute 8 through the primary air inlet 37 and the secondary air inlet 40. Under the joint action of the primary air inlet adjusting valve 36 and the secondary air inlet adjusting valve 39, the flow field inside the air control volute 8 is uniformly and stably realized. The entering airflow moves upward and is guided by the air control ring 7 to generate a speed inclination angle, and enters the inner circulation control area 41. Under the joint action of the inner circulation control disc 12 and the air control ring 7, different particle sizes are subjected to centrifugal force, air drag, gravity, and other actions to produce different residence times. When the vertical direction residence time t v is greater than the horizontal direction residence time t h , the particle size of the particle is settled, the inner circulation load is increased; when the vertical direction residence time t v is less than the horizontal direction residence time t h , the particle size of the particle passes through the inner circulation control area 41, and the inner circulation load is reduced, thereby realizing accurate inner circulation control. The settled particles fall along the side wall of the air control volute 8 into the coarse powder outlet 15, and the particles passing through the inner circulation control area 41 enter the upper fine classifier. The fine classifier transmission mechanism 1 drives the fine classifier rotating mechanism 3 to work, and the annular area formed between the stationary blade 4 and the fine classifier rotating mechanism 3 completes fine classification. The fine powder passes through the fine classifier rotating mechanism 3 and is collected by the subsequent dust collection equipment, and the medium coarse powder falls into the medium coarse powder return hopper 29, and then is introduced into the medium coarse powder return box 14 at the lower part of the air control volute 8 by the return control device 5, and is discharged from the coarse powder outlet 15.

[0096] Referring to Figure 7By CFD transient analysis of the distribution of particles in the device, it can be seen that, under the action of the inner circulation control device, the inner circulation control area 41 has obvious particle separation, retention and aggregation, part of the coarse particles cannot pass through the inner circulation control area 41 and fall into the lower part of the control air spiral case 8, and part of the fine particles pass through the inner circulation control area 41 and enter the fine classifier, which realizes the purpose of accurate control of inner circulation.

[0097] The application effect of the inner circulation accurate control classifier designed in the application and the fine classifier without using the inner circulation control device is shown in the following table 1.

[0098] Table 1 Application effect comparison

[0099]

[0100] As shown in table 1, after the inner circulation accurate control classifier designed in the application is used, the rated power of the motor matched with the fine classifier is reduced by 130kW, the rated power of the motor matched with the circulating fan is reduced by 220kW, the actual unit power consumption of the fine classifier is reduced by 0.14kWh / t, the actual unit power consumption of the circulating fan is reduced by 0.91kWh / t, and the unit power consumption of the system is reduced by 1.54kWh / t. Therefore, the application of the inner circulation accurate control classifier of the application effectively reduces the unit power consumption of the fine classifier, the circulating fan and the system.

[0101] The application can realize accurate control of the inner circulation load through the inner circulation control device, can meet the requirement of any inner circulation load of the grinding and separation process, reduces the probability of coarse particles entering the fine classifier, improves the efficiency of the fine classifier, reduces the power of the motor of the transmission part, reduces the load of the separation airflow, reduces the pressure head of the circulating fan, and reduces the power consumption.

[0102] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the above embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A precision-controlled grading machine with internal circulation, comprising a fine grading machine located on the upper part of the entire machine, the fine grading machine being used to produce finished products; characterized in that: It also includes an internal circulation control device, which is located at the bottom of the entire equipment. The internal circulation control device is used to achieve precise control of internal circulation and pre-dispersion of materials, so as to achieve internal circulation load requirements under various working conditions. The internal circulation control device includes an internal circulation transmission mechanism, a control device shaft system, an internal circulation control disc, an air control volute, a central feeding device, and a return material control device. The internal circulation transmission mechanism drives the control device shaft system to rotate, and the top of the control device shaft system is connected to the internal circulation control disc. The air control volute surrounds the internal circulation control device, with air inlets distributed on its sides and a coarse powder outlet at its bottom. An air control ring, concentric with the internal circulation control disc, is located near the internal circulation control disc and is fixed to the inner wall of the air control volute. The air control ring has a frustum-shaped thin-walled structure, and an internal circulation control area is formed between the internal circulation control disc and the air control ring. The feeding port of the central feeding device is located above the internal circulation control disc and is eccentrically arranged, so that the material drop point of the central feeding device is located at the center of the internal circulation control disc, realizing central feeding. The return material control device is located at the lower part of the medium and coarse powder return cone of the fine classifier and is used to discharge the medium and coarse powder after being sorted by the fine classifier from the equipment. The internal circulation control disc has a ring-shaped stacked structure, consisting of a material spreading impeller, a deceleration ring, and a dispersion sorting control impeller from top to bottom. The material spreading impeller is composed of multiple arrayed rotating blades, each forming an angle β with the horizontal plane, with the β direction aligned with the rotation direction. The lower part of the material spreading impeller is a receiving plate, with the deceleration ring encircling its edge, forming a weir between the deceleration ring and the receiving plate. The dispersion sorting control impeller is located below the outer circumference of the deceleration ring, and is composed of multiple arrayed rotating blades, each forming an angle γ with the horizontal plane, with the γ direction aligned with the rotation direction. The rotating blades are fixed to connecting plates circumferentially welded to the deceleration ring by bolts.

2. The internal circulation precision control grading machine according to claim 1, characterized in that, The eccentricity of the central feeding device is E, the distance from the feeding point of the central feeding device to the inner circulation control disk in the vertical direction is L, the installation angle of the central feeding device with respect to the vertical direction is α, and the radius of the inner circulation control disk is R; the acceleration caused by the gravity of the material is negligible, and central feeding is achieved when the material moves equal distances in the horizontal and vertical directions. According to the angle of repose of the material, ;therefore, .

3. The internal circulation precision control grading machine according to claim 1, characterized in that, Each of the rotating blades consists of a fan-shaped plate, a lifting boss, and a baffle plate. The lifting boss consists of multiple pieces, which are welded to the high end of the fan-shaped plate. The baffle plate is located between two adjacent fan-shaped plates, and its upper and lower ends are connected to the two adjacent fan-shaped plates respectively, sealing the drop gap between the two fan-shaped plates.

4. The internal circulation precision control grading machine according to claim 1, characterized in that, A dust cap is provided at the top of the internal circulation control panel where it mates with the spindle.

5. The internal circulation precision control grading machine according to claim 1, characterized in that, The return material control device includes a first guide cone, a second guide cone, a dividing cone, a return pipe interface, and a return chute. The first guide cone is installed inside the medium-coarse powder return cone hopper. The second guide cone is concentrically connected above the first guide cone, and the apex angle of the second guide cone is larger than that of the first guide cone. Together, they form a central guide cone. An annular material zone for collecting medium-coarse powder is formed between the central guide cone and the medium-coarse powder return cone hopper. Several dividing cones are evenly distributed along the circumference of the annular material zone. Each dividing cone consists of two plates stacked together in a ridge shape. The dividing cones divide the annular material zone into several bucket-shaped material zones. Each bucket-shaped material zone has a return pipe interface at its bottom. The return pipe interface is funnel-shaped with a larger top and a smaller bottom. The lower end of the return pipe interface is connected to the return chute.

6. The internal circulation precision control grading machine according to claim 5, characterized in that, The lower end of the return chute is connected to the medium-coarse powder return box located outside the air control volute. The medium-coarse powder return box is located in the space where the air inlets intersect, and an observation door is provided on the medium-coarse powder return box.

7. The internal circulation precision control grading machine according to claim 1, characterized in that, The internal circulation control device is a reverse-rotating device, and the internal circulation transmission mechanism is a bottom-mounted transmission. The bottom-mounted transmission is located at the bottom of the internal circulation control device and is connected to the bottom end of the control device shaft system.

8. The internal circulation precision control grading machine according to claim 7, characterized in that, The lower transmission is bolted to the control device fixing beam, which is a steel frame, so that the force of the internal circulation control device is transmitted to the foundation and does not cause vibration superposition with the wind control volute.

9. The internal circulation precision control grading machine according to claim 8, characterized in that, The lower transmission includes a transmission motor, a lower transmission support, and a coupling. The transmission motor is located at the bottom and is fixed to the lower transmission support by bolts. The lower transmission support is fixed to the control device fixing beam. The transmission motor is connected to the main shaft of the control device shaft system through the coupling.

10. The internal circulation precision control grading machine according to claim 1, characterized in that, The control device shaft system includes a main shaft, a reverse bearing housing, a bushing, an upper bearing housing, and tie rod supports. The main shaft is located inside the bushing. The lower part of the main shaft is supported by a bearing assembly one installed in the reverse bearing housing, and the upper part is aligned by a bearing assembly two installed in the upper bearing housing. The two ends of the bushing are respectively connected to the reverse bearing housing and the upper bearing housing to form a whole. Multiple tie rod supports are provided and arranged radially around the upper bearing housing. One end of the tie rod support is connected to the upper bearing housing, and the other end is connected to the air control volute. The reverse bearing housing is fixed to the control device fixing beam.

11. The internal circulation precision control grading machine according to claim 10, characterized in that, Each of the aforementioned tie rod supports is fitted with an anti-wear sleeve.

12. The internal circulation precision control grading machine according to claim 1, characterized in that, The control device shaft system coincides with the center of the entire equipment. Diagonal braces are provided around the lower part of the control device shaft system, and the other end of the diagonal braces is connected to the control device fixed beam.

13. The internal circulation precision control grading machine according to claim 1, characterized in that, The air inlet is either tangential or vertical. An air inlet regulating valve is provided on the air inlet. Several wear-resistant liners made of flat steel are welded axially around the inner wall of the air control volute located at the air inlet. Each wear-resistant liner is perpendicular to the air control volute.

14. The internal circulation precision control grading machine according to claim 1, characterized in that, The fine classifier includes a fine classifier transmission mechanism, a fine classifier rotary mechanism, stationary blades, a fine classifier housing, and a medium-coarse powder return cone. The fine classifier transmission mechanism is located at the top of the fine classifier housing and is connected to the fine classifier rotary mechanism. The top of the fine classifier rotary mechanism is fixed to the top platform of the fine classifier housing via a flange. The stationary blades are at the same height as the fine classifier rotary mechanism and are concentrically distributed around the fine classifier rotary mechanism. Both the stationary blades and the fine classifier rotary mechanism are located inside the middle section of the fine classifier housing. The top of the medium-coarse powder return cone is connected to the bottom of the stationary blades. The bottom of the fine classifier housing is connected to the air control volute to form a dust-laden airflow channel.

15. The internal circulation control method for a precise internal circulation control grading machine according to any one of claims 1 to 14, characterized in that, The material to be sorted is fed into the inner circulation control disc by the central feeding device. The inner circulation transmission mechanism drives the control device shaft system to rotate the inner circulation control disc, so that the material sprinkled on it enters the inner circulation control zone evenly. The sorting airflow enters the air control volute through the air inlet and moves upward into the inner circulation control zone. The material to be sorted contains control particles with a particle size of d, coarse particles with a particle size greater than d, and fine particles with a particle size less than d. Under the combined action of the inner circulation control disc and the air control ring, different particles have different residence times due to their own gravity, the centrifugal force generated by the inner circulation control device, and the air drag force generated by the circulating fan. When the vertical residence time of the particles is t... v Greater than the horizontal dwell time t h When particles of this size settle, the internal circulation load increases; when the vertical residence time t of the particles... v Less than the horizontal dwell time t h When particles of this size pass through the internal circulation control zone, the internal circulation load decreases. By controlling the rotation speed of the internal circulation control disc or the structure of the air control ring, the value of the controlled particle size d is changed, thereby changing the amount of material as coarse and fine particles, so as to achieve precise control of the internal circulation load.

16. The internal circulation control method for a precise internal circulation control classifier according to claim 15, characterized in that, The formula for calculating the particle size d is as follows: In the formula: To control particle diameter, m; The density of the material is kg / m³. 3 ; The density of the gas is kg / m³. 3 ; For gas dynamic viscosity, m 2 / s; Q is the operating air volume of the circulating fan, in meters. 3 / s; The radius of the internal circulation control panel is in meters (m). δ is the rotational speed of the internal circulation control disc, r / s; H is the height of the internal circulation control zone, m; D is the width of the internal circulation control zone, m; δ is the tilt angle of the air control ring.

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