An air grinder nozzle

Abstract

The application provides a gas mill nozzle, comprising a body, the body having opposite gas inlet and outlet end faces, a flow passage being arranged in the body, the flow passage comprising a gas inlet section, a contraction section, an expansion section and a gas outlet section which are coaxial and connected in sequence, the gas inlet section forming a gas inlet at the gas inlet end face, and the gas outlet section forming a gas outlet at the gas outlet end face; the gas inlet section and the gas outlet section are both cylindrical in shape, the contraction section and the expansion section are both frustoconical in shape, the large circular end of the contraction section has a diameter equal to that of the gas inlet section and is connected to the gas inlet section via the large circular end, the small circular end of the expansion section has a diameter equal to that of the small circular end of the contraction section, and the small circular end of the expansion section is connected to the small circular end of the contraction section, and the diameter of the gas outlet section is equal to that of the large circular end of the expansion section and is connected to the large circular end of the expansion section. The gas mill nozzle can accelerate the gas and make the gas be sprayed out at a high flow rate, thereby ensuring the crushing effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of jet mill, in particular to a jet mill nozzle. BACKGROUND

[0002] The jet mill is a kind of crushing equipment for processing coarse particle materials into fine particle powders by high-speed airflow, which is widely used in the fields of medicine, biochemistry, ceramics and lithium battery. The working principle of the jet mill is that the compressed gas flows through the jet mill nozzle, and then is injected into the crushing zone of the jet mill to make the material in a fluidized state. The accelerated particles flow with the airflow, repeatedly collide, rub and shear at the intersection point of the nozzle airflow, and are crushed. The crushed material reaches the classification wheel under the action of negative pressure and is classified. The fine particles meeting the particle size requirement enter the cyclone separator with the airflow for gas-solid separation and are captured. The coarse particles not meeting the particle size requirement return to the crushing zone under the action of their own gravity to continue the crushing. The airflow channel of the existing jet mill nozzle is cylindrical. This structure cannot accelerate the gas entering the jet mill nozzle, and the gas flow rate ejected from the jet mill nozzle is low, which affects the crushing effect. SUMMARY

[0003] The purpose of the present application is to provide a jet mill nozzle which can accelerate the gas so that the gas can be ejected at a high flow rate, thereby ensuring the crushing effect.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0005] A jet mill nozzle comprises a body.

[0006] The body has opposite gas inlet and outlet end faces. A flow passage is arranged inside the body. The flow passage comprises a gas inlet section, a converging section, an expanding section and a gas outlet section which are coaxial and connected in sequence. The gas inlet section forms a gas inlet at the gas inlet end face. The gas outlet section forms a gas outlet at the gas outlet end face, so that the gas can enter the flow passage from the gas inlet and be discharged from the gas outlet.

[0007] The shapes of the gas inlet section and the gas outlet section are both cylindrical. The shapes of the converging section and the expanding section are both circular truncated cone. The major circular end diameter of the converging section is equal to the diameter of the gas inlet section, and the converging section is connected to the gas inlet section through the major circular end. The minor circular end diameter of the expanding section is equal to the minor circular end diameter of the converging section, and the minor circular end of the expanding section is connected to the minor circular end of the converging section. The diameter of the gas outlet section is equal to the major circular end diameter of the expanding section, and the gas outlet section is connected to the major circular end of the expanding section.

[0008] Preferably, the taper angle of the converging section is α, and 30°≤α≤70°.

[0009] and / or the taper angle of the expansion section is β, and 20°≤β≤60°.

[0010] Preferably, the number of the flow channels is more than one.

[0011] The minor end diameter of the contraction section is d cr , and

[0012] where P0 is the gas pressure entering the flow channel from the gas inlet, Q is the gas flow, n is the number of the flow channels, a is the atmospheric pressure, b is a correction coefficient, and 1.3≤b≤1.6.

[0013] Preferably, an external gas source can be connected to the gas inlet to input gas into the flow channel.

[0014] P1=P0+0.05, where P1 is the external gas source pressure.

[0015] Preferably, when P0<1.2MPa, 1.3≤b≤1.45, and when P0>1.2MPa, 1.45≤b≤1.6.

[0016] Preferably, the diameter of the gas outlet section is d out , and

[0017] where M is the Mach number corresponding to the gas flow velocity of the gas discharged from the gas outlet, k is the adiabatic index of the gas flowing through the flow channel, c is an index factor, and e is a correction value.

[0018] Preferably, P0=1.8788×M 2 -6.5972M+6.3364.

[0019] Preferably, a flow guide strip is arranged on the inner wall of the gas outlet section, the flow guide strip extends along a curve from a position close to the expansion section towards a position close to the gas outlet, the number of the flow guide strips is at least two, and the at least two flow guide strips are uniformly arranged along the circumference of the gas outlet section.

[0020] Two points A and B are selected on the extension curve of the flow guide strip, and the distance between A and B along the axial direction of the gas outlet section is 1mm, a straight line L1 passing through A and tangent to the extension curve of the flow guide strip, and a straight line L2 passing through B and tangent to the extension curve of the flow guide strip, L1 and L2 form an included angle θ, and 5°≤θ≤15°.

[0021] Preferably, in the radial direction of the gas inlet section, the height of the flow guide strip is 0.1mm to 0.5mm.

[0022] Preferably, the diameter of the inlet section is d in , and 1.5xd cr <d in <4xd cr .

[0023] The gas mill nozzle of the present application can accelerate the gas and make the gas spray out at a high flow rate, thereby ensuring the crushing effect, by adopting the technical scheme that the shapes of the inlet section and the outlet section are both cylindrical, the shapes of the converging section and the diverging section are both frustoconical, the large circular end of the converging section has a diameter equal to that of the inlet section and is connected to the inlet section through the large circular end, the small circular end of the diverging section has a diameter equal to that of the small circular end of the converging section, and the small circular end of the diverging section is connected to the small circular end of the converging section, and the diameter of the outlet section is equal to that of the large circular end of the diverging section and is connected to the large circular end of the diverging section. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Fig. 1 is a structural schematic view of an embodiment of the gas mill nozzle of the present application;

[0025] Figure 2 Fig. 2 is a schematic view of the flow passage in the middle part of the gas mill nozzle of the present application. Figure 1

[0026] In the figure: 1 - body; 2 - inlet end face; 3 - outlet end face; 4 - flow passage; 5 - inlet section; 6 - converging section; 7 - diverging section; 8 - outlet section; 9 - inlet; 10 - outlet; 11 - flow guide strip. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the gas mill nozzle of the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0028] Embodiment One

[0029] As Figure 1 , 2 ​As shown, a gas mill nozzle comprises: a body 1, the body 1 having an air inlet end face 2 and an air outlet end face 3 facing each other, a flow channel 4 being provided inside the body 1, the flow channel 4 comprising an air inlet section 5, a contraction section 6, an expansion section 7, and an air outlet section 8, the axes of which coincide and are connected in sequence, the air inlet section 5 forming an air inlet 9 at the air inlet end face 2, and the air outlet section 8 forming an air outlet 10 at the air outlet end face 3, so that gas can enter the flow channel 4 from the air inlet 9 and be discharged through the air outlet 10. The air inlet section 5 and the air outlet section 8 are both cylindrical in shape, the contraction section 6 and the expansion section 7 are both truncated cone in shape, the large circular end of the contraction section 6 having a diameter equal to that of the air inlet section 5 and being connected to the air inlet section 5 through the large circular end, the small circular end of the expansion section 7 having a diameter equal to that of the small circular end of the contraction section 6, and the small circular end of the expansion section 7 being connected to the small circular end of the contraction section 6, the diameter of the air outlet section 8 being equal to that of the large circular end of the expansion section 7 and being connected to the large circular end of the expansion section 7. With this technical solution, when the airflow passes through the contraction section 6, it will be accelerated by the contraction effect, thereby increasing the speed of the airflow ejected from the air outlet 10. The airflow velocity ejected from the air outlet 10 is greater than the airflow velocity entering from the air inlet 9, achieving the effect of accelerating the airflow. Thus, the crushing effect is guaranteed.

[0030] Specifically, if Figure 2 As shown, the cone angle of the contraction section 6 is α, and 30°≤α≤70°. The purpose of providing the contraction section 6 is to accelerate the gas entering the flow channel 4 so that when it reaches the junction of the contraction section 6 and the expansion section 7, it is accelerated to supersonic speed, providing conditions for achieving the transition from subsonic speed to supersonic speed. The technical solution of 30°≤α≤70° can avoid the contraction section 6 being too long due to a too small angle α, which increases manufacturing costs. At the same time, it can also avoid the cross-section of the contraction section 6 being too quickly reduced due to an excessively large angle α, which causes excessive pressure loss and affects the efficient operation of the gas mill nozzle.

[0031] And / or, the cone angle of the expansion section 7 is β, and 20°≤β≤60°. The purpose of setting the expansion section 7 is to further expand and accelerate the airflow that reaches supersonic speed, so that it reaches the optimal expansion state when it reaches the junction of the expansion section 7 and the air outlet section 8, and reaches the designed airflow speed. The technical solution of 20°≤β≤60° can avoid the expansion section 7 being too long due to the β angle being too small, thereby increasing the manufacturing cost of the nozzle, and at the same time avoid the expansion of the gas being too large due to the β angle being unfavorable. In this way, the gas reaches the optimal expansion state, and the efficiency is the highest under this condition. Regardless of under-expansion or over-expansion, shock waves will be generated, causing the nozzle to deviate from the optimal working state, reducing efficiency, and thus resulting in poor crushing effect on the material.

[0032] Example 2

[0033] Based on Example 1, Figure 1 、 2As shown, the number of flow passages 4 is more than one;

[0034] The small circle end diameter of the convergent section 6 is dcr, and The following explains each parameter in the formula:

[0035] I. P0 is the gas pressure entering the flow passage 4 from the inlet 9, wherein the gas pressure P0 entering the flow passage 4 from the inlet 9 is related to the pressure P1 of the external gas source connected to the inlet 9, which is a key factor to be considered in the design of the jet mill nozzle and has an important influence on the crushing effect of the material. The higher the speed of the supersonic gas flow at the outlet 10 and the higher the corresponding Mach number M, the higher the gas source pressure P1 required to provide momentum. If P1 is too low, the gas cannot reach supersonic speed at the joint of the convergent section 6 and the divergent section 7, and if P1 is too large, it means higher equipment investment and higher operating cost. Therefore, the selection of the external gas source pressure P1 needs to consider multiple factors such as the design of the jet mill nozzle, the material crushing performance, the operating and maintenance cost, etc. In order to realize the quantitative design of the external gas source pressure P1, the relationship between the nozzle inlet pressure P0 and the Mach number M is fitted according to experimental data and theoretical analysis, which is as follows: P0 = 1.8788 x M 2 -6.5972M + 6.3364. Wherein M is the Mach number corresponding to the gas flow speed at the outlet 10, M is 1-8, preferably M is 1.8-4. The pressure loss during the operation of the jet mill mainly comes from the jet mill itself, but the pressure loss from the gas source to the inlet 9 should not be ignored. The following relationship can be used to calculate the gas source pressure that the compressed gas should guarantee: P 1＝ P0 + 0.05.

[0036] II. a is the atmospheric pressure, which is actually the atmospheric pressure at the place of use, a = 0.08-0.11, usually 0.09-0.103, unit MPa, the pressure here is absolute pressure.

[0037] III. Q is the gas flow, i.e. the gas flow into the jet mill nozzle under standard conditions, unit m 3 / h. The specific value of the gas flow Q can be obtained by directly measuring with a flowmeter.

[0038] IV. n is the number of flow passages, from which the theoretical gas flow of a single jet flow passage 4 can be obtained; the advantage of such a setting is that only the total amount of compressed gas needs to be measured, and the amount of a single jet does not need to be measured, and it is also difficult to accurately measure in actual use.

[0039] V. b is the throat diameter correction coefficient, when P0 < 1.2 MPa, 1.3 ≤ b ≤ 1.45, when P0 > 1.2 MPa, 1.45 ≤ b ≤ 1.6.

[0040] Embodiment three

[0041] Based on Embodiment two, as shown in Figure 2 diameter of the outlet section 8 is dout, and wherein M is the Mach number corresponding to the gas flow velocity of the gas discharged from the outlet 10, k is the adiabatic index of the gas flowing through the flow passage 4, c is an index factor, and e is a correction value. The parameters in the formula are described in detail as follows:

[0042] I. k is the adiabatic index of the gas flowing through the flow passage 4. When the gas flowing through the flow passage 4 is a monatomic molecule such as helium, neon, argon, etc., k is 1.67. When the gas flowing through the flow passage 4 is a diatomic molecule such as hydrogen, nitrogen, oxygen, etc., k is 1.4. When the gas flowing through the flow passage 4 is air, k is also 1.4. When the gas flowing through the flow passage 4 is a triatomic molecule such as carbon dioxide, k is 1.3.

[0043] II. c is an index factor, which is related to the properties of the gas flowing through the flow passage 4. When the gas flowing through the flow passage 4 is a monatomic molecule such as helium, neon, argon, etc., c is 1.99. When the gas flowing through the flow passage 4 is a diatomic molecule such as hydrogen, nitrogen, oxygen, etc., c is 3.0. When the gas flowing through the flow passage 4 is air, c is also 3.0. When the gas flowing through the flow passage 4 is a triatomic molecule such as carbon dioxide, c is 3.83.

[0044] IV. M is the Mach number corresponding to the design value of the gas flow velocity of the gas discharged from the outlet 10. Specifically, P0 can be obtained by calculating M, and the formula is P0 = 1.8788 x M 2 - 6.5972M + 6.3364.

[0045] V. The calculation steps of dcr have been described in Embodiment two, which will not be repeated here.

[0046] VI. e is a correction value. In this embodiment, the inner wall of the outlet section 8 is smooth (i.e. there is any structure on the inner wall of the outlet section 8 that can affect the movement of the gas flow), and the value of e is 0 at this time.

[0047] Embodiment four

[0048] Based on Embodiment three, since the gas flow reaches the designed optimal expansion state when it reaches the joint position of the nozzle expansion section 7 and the outlet section 8, the gas flow velocity reaches the maximum value at this time, and the gas leaves the body 1 in a parallel jet state after being rectified by the outlet section 8. Since the effect of the parallel jet on the entrainment of the material in the gas flow is not ideal, the technical solution of this embodiment is as follows Figure 2As shown, a guide strip 11 is provided on the inner wall of the outlet section 8. The guide strip 11 extends along a curve from near the expansion section 7 toward the outlet 10. There are at least two guide strips 11, evenly spaced along the circumference of the outlet section 8. Two points, A and B, are selected on the extension curve of the guide strip 11. In the axial direction of the outlet section 8, the distance between A and B is 1 mm. A straight line passing through A and tangent to the extension curve of the guide strip 11 is L1, and a straight line passing through B and tangent to the extension curve of the guide strip 11 is L2. L1 and L2 form an angle θ, with 5°≤θ≤15°. Furthermore, in the radial direction of the outlet section 8, the height of the guide strip 11 ranges from 0.1 mm to 0.5 mm. In actual production, to reduce wear on the guide strip 11 caused by airflow, the surfaces of the outlet section 8 and the guide strip 11 may be coated with an anti-wear layer. The provision of the guide strips 11 can cause the supersonic airflow discharged from the air outlet 10 to exhibit a swirling state, promoting the supersonic airflow's entrainment and carrying of the material, thereby enhancing the material pulverization effect. It should be noted that in the formula for calculating the diameter of the air outlet section 8 as dout, the value of e is 0.4 / k.

[0049] Example 5

[0050] Based on the second and fourth embodiments, Figure 2 As shown, the diameter of the air inlet section 5 is d in , and 1.5×d cr <d in <4×d cr The calculation steps of dcr have been described in Example 2 and will not be repeated here.

[0051] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A gas mill nozzle, characterized in that: include: Ontology(1); The body (1) has an air inlet end face (2) and an air outlet end face (3) facing each other, and a circulation channel (4) is provided inside the body (1). The circulation channel (4) includes an air inlet section (5), a contraction section (6), an expansion section (7) and an air outlet section (8) whose axes coincide and are connected in sequence. The air inlet section (5) forms an air inlet (9) on the air inlet end face (2), and the air outlet section (8) forms an air outlet (10) on the air outlet end face (3), so that gas can enter the circulation channel (4) from the air inlet (9) and be discharged through the air outlet (10); The air inlet section (5) and the air outlet section (8) are both cylindrical in shape, the contraction section (6) and the expansion section (7) are both truncated cone in shape, the diameter of the large circular end of the contraction section (6) is equal to the diameter of the air inlet section (5) and is connected to the air inlet section (5) through the large circular end, the diameter of the small circular end of the expansion section (7) is equal to the diameter of the small circular end of the contraction section (6), and the small circular end of the expansion section (7) is connected to the small circular end of the contraction section (6), the diameter of the air outlet section (8) is equal to the diameter of the large circular end of the expansion section (7), and is connected to the large circular end of the expansion section (7); The cone angle of the contraction section (6) is α, and 30°≤α≤70°; The cone angle of the expansion section (7) is β, and 20°≤β≤60°; The number of the circulation channels (4) is more than one; The diameter of the small round end of the contraction section (6) is d cr , and d cr =b× ; Wherein P0 is the pressure of the gas entering the circulation channel (4) from the air inlet (9), Q is the gas flow rate, n is the number of circulation channels (4), a is the atmospheric pressure, b is the correction coefficient, and 1.3≤b≤1.6; An external gas source can be connected to the gas inlet (9) to input gas into the flow channel (4); P1=P0+0.05, where P1 is the external gas source pressure; When P0<1.2MPa, 1.3≤b≤1.45, when P0>1.2MPa, 1.45≤b≤1.6; The diameter of the air outlet section (8) is d out , and d out =d cr × +e; Wherein M is the Mach number corresponding to the airflow velocity of the gas discharged from the gas outlet (10), k is the adiabatic index of the gas flowing through the flow channel (4), c is the exponential factor, and e is the correction value; P0=1.8788×M 2 -6.5972M+6.3364。 2. The gas mill nozzle according to claim 1, characterized in that: A guide strip (11) is provided on the inner wall of the air outlet section (8), and the guide strip (11) extends along a curve from a position close to the expansion section (7) toward a position close to the air outlet (10), and the number of the guide strips (11) is at least two, and at least two of the guide strips (11) are evenly arranged along the circumference of the air outlet section (8); Two points A and B are selected on the extension curve of the guide strip (11), and the distance between A and B along the axial direction of the air outlet section (8) is 1 mm. The straight line passing through A and tangent to the extension curve of the guide strip (11) is L1, and the straight line passing through B and tangent to the extension curve of the guide strip (11) is L2. L1 and L2 form an angle θ, and 5º≤θ≤15º.

3. The gas mill nozzle according to claim 2, characterized in that: In the radial direction of the air outlet section (8), the height of the guide strip (11) is 0.1 mm to 0.5 mm.

4. The gas mill nozzle according to claim 1, characterized in that: The diameter of the air inlet section (5) is d in , and 1.5×d cr <d in <4×d cr .

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