Multichannel Venturi-tube hydrodynamic cavitation generating device

Abstract

A multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation comprising an inlet tube 1 and venturi tube body 2 with expansion section and a throat section 12, wherein a

Description

The present disclosure relates to the field of hydrodynamic cavitation technologies, and in particular, to a multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation. BACKGROUND Tailings often contain many fine-particle minerals, and it is an important scientific technology to turn tailing resources into wealth and utilize this wealth on a large scale through an advanced process. In a tailing extraction process, a Venturi tube is matched with a flotation column to float fine-particle minerals using micro- and nano-sized vapor bubbles. A Venturitube-type hydrodynamic cavitation reactor is a key technology for separating and recovering valuable minerals in tailings, and the cavitation performance thereof directly influences the flotation efficiency of the tailings. Cavitation is the process of formation, development, and collapse of vapor or gas cavities (cavitation bubbles) within liquid or at a liquid-solid interface when the local pressure is lower than the saturated vapor pressure, and is usually performed using a Venturi tube in the mineral processing. Chinese patent publication No. CN110339696A discloses a Venturi hydrodynamic cavitation reactor, which includes an inlet convergent section, a throat, and an outlet divergent section, where the throat is provided with a gas inlet, a porous plate is arranged in the throat, the gas inlet is close to the inlet convergent section side, and the porous plate is close to the outlet divergent section side. According to the above-mentioned technical solution, the porous plate and the gas inlet are mounted in the throat of a Venturi tube in the patent, so as to strengthen a cavitation effect. However, the throat is a low pressure region with preliminary cavitation generation in the Venturi tube, and the introduction of external gas into this region may additionally introduce high pressure gas, such that the local pressure of the throat of Venturi tube is increased, cavitation inception conditions cannot be met, and the cavitation efficiency of the hydrodynamic cavitation reactor is greatly influenced. In addition, the hydrodynamic cavitation reactor has a single cavitation mode, as only one cavitation channel is present in the tube, resulting cavitation is not thorough, and a sufficient hydrodynamic cavitation intensity cannot be reached in the application of mineral processing with requirements for the cavitation performance. SUMMARY In view of the deficiencies in the prior art, the present disclosure provides a multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation, which has advantage of plural times of cavitation, solves the problems that the traditional Venturi tube has only one water channel, a single cavitation approach, and thus incomplete cavitation, and further improves the cavitation rate of a single Venturi tube using plural ways for strengthening the cavitation generation. The above technical object of the present disclosure is attained with the following technical means. A multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation is provided, including an inlet tube and a Venturi tube body, where the Venturi tube body includes an expansion section and a throat tube section; an input end of the throat tube section is in fluid communication with an output end of the inlet tube, and an output end of the throat tube section is connected to the expansion section; the expansion section is a divergent tube, and a flow-blocking body is arranged in the expansion section by means of fixed rods; the flow-blocking body is of a hollow structure; the output end of the inlet tube is in fluid communication with arc-shaped throat tubes, the arc-shaped throat tubes are in fluid communication with a ring tube, and flow-dividing throat tubes are arranged at an output end of the ring tube; and output ends of the flow-dividing throat tubes are arranged in the expansion section above the flow-blocking body; wherein the inlet tube is of a hollow cylindrical structure, and gas injection holes are formed in side walls of the water inlet tube; a plurality of holes are formed in a bottom surface of the hollow cylindrical structure, and the holes on the water inlet tube are in fluid communication with the arc-shaped throat tubes and the throat tube section. Further, a spiral impeller is arranged in the water inlet tube. Further, blades of the spiral impeller are supercavitation blades. Further, a diameter of the arc-shaped throat tubes and a diameter of the flow-dividing throat tubes are both less than a diameter of the ring tube. Further, a porous plate is arranged in each of the arc-shaped throat tubes. Further, permanent magnets are arranged in each of the flow-blocking body and the ring tube. Further, the ring tube is of a spherical structure. Further, the flow-blocking body is a hollow tube and is in a divergent shape in a fluid direction. Further, the gas injection holes are distributed on the water inlet tube at equal intervals in a circumferential direction. Compared with the prior art, the present disclosure has the following beneficial effects. 1. In the present disclosure, the spiral impeller is mounted in the inlet tube, and when water flow enters the inlet tube, the rotation of the impeller increases the disturbance degree of the water flow to increase the energy of the water flow, thus providing favorable conditions for generation of strong cavitation phenomena. 2. In the present disclosure, the spiral impeller is configured to have supercavitation blade airfoils, and a series of ribs of the same type are processed on a surface of the impeller to increase the contact areas between the blades and a water body, such that the disturbance of fluid is intensified to form more cavitation bubbles, so as to achieve the aim of strengthening cavitation generation. The blade airfoils are thin and sharp, a series of bubbles are directly induced on the back of each of the blades at the inlet tube, and the bubbles move with an eddy current flow, thus avoiding cavitation erosion damage to the blades caused by direct collapse on surfaces of the blades. After entering the Venturi tube body, the bubbles are gathered near the axis of the tube under the action of a centrifugal force provided by the spiral impeller, which ensures that the position of hydrodynamic cavitation generation is apart from an inner wall surface of a Venturi tube, thereby reducing cavitation erosion damage to the wall of the tube by collapse of the bubbles while cavitation generation is guaranteed. 3. In the present disclosure, the gas injection holes are evenly arranged at 90-degree intervals in the circumferential direction on a wall surface of the inlet tube, which does not increase the pressure value of a low pressure region of a throat, and can additionally increase the number of bubbles in the fluid to provide gas cores necessary for cavitation inception, so as to achieve the purpose of strengthening hydrodynamic cavitation generation. 4. In the present disclosure, the inlet tube is configured in a cylindrical shape, the inlet tube is directly and linearly connected to the throat tube section of the Venturi tube body, and when the water flow enters the throat through the inlet tube, an increase of a contraction angle increases an inflow speed to generate a relatively large pressure drop in the Venturi tube, and meanwhile reduces turbulence intensity, so as to finally achieve the aims of increasing the cavitation rate in a diffusion section and effectively guaranteeing hydrodynamic cavitation generation. 5. In the present disclosure, the ring tube is arranged in the Venturi tube body, the water flow is divided by the plurality of flow-dividing throat tubes when entering, and is cavitated in the ring tube to be discharged, and the water flow normally passing through the Venturi tube is divided and cavitated by the flow-blocking body again, thereby achieving an effect of plural times of cavitation, solving the problems of a single water channel and cavitation approach and resulting incomplete cavitation of the traditional Venturi tube, and realizing the advantage that plural times of cavitation are performed in a limited space to improve a cavitation efficiency. 6. In the present disclosure, the permanent magnets are arranged, and a magnetic field generated by the permanent magnets may prolong the service life of active free radicals, thereby greatly reducing the risk of accumulating pathogenic microorganisms in the mineral flotation column. 7. In the present disclosure, the hollow flow-blocking body is arranged, the water flow is divided by the flow-blocking body after entering the expansion section through the throat tube section, one part of the water flow passes through the hollow part of the flow-blocking body, the other part of the water flow slides over an outer wall of the flow-blocking body, and since the flow-blocking body has a small inlet and a large inner space and outlet to form a shape similar to a Venturi tube, the water flow passing through the inner part of the flow-blocking body can induce secondary cavitation phenomenon. 8. In the present disclosure, by providing the fixed rods for connection, the flow-blocking body may be suspended on the inner side of the ring tube, and may be thus matched with the ring tube to reduce a diameter through which the water flow passes, and the water flow sliding over the outer wall of the flow-blocking can generate cavitation bubbles. 9. In the present disclosure, the hole diameter of the arc-shaped throat tubes and the hole diameter of the flow-dividing throat tubes are set to be both less than the hole diameter of the ring tube, such that after cavitated by the matched arc-shaped throat tubes and ring tube, the water flow is guided by the flow-dividing throat tubes, and the water flow in the ring tube can be subjected to convection collision after discharged from the tube, thus promoting generation of the cavitation bubbles to enhance cavitation intensity. 10. In the present disclosure, the porous plates are arranged, the fluid enters the fluid inlet tube and passes through the porous plates, and due to a throttling effect of the porous plate, the flow rate is increased, and the hydrostatic pressure is reduced, and when the pressure reaches or is even lower than saturated vapor pressure of the fluid at the temperature, the cavitation appears in the form of vapor-filled bubbles, and the gas trapped within the crevices of particle surfaces are considered as additional cavitation nuclei, thus achieving a cavitation assisting effect. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic structural diagram of a multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to the present disclosure. REFERENCE NUMERALS 1-inlet tube; 2-Venturi tube body; 3-ring tube; 4-flow-dividing throat tube; 5-arc-shaped throat tube; 6-flow-blocking body; 7-permanent magnet, 8-fixed rod; 9-porous plate; 10-gas injection hole; 11-spiral impeller; 12-throat tube section. DETAILED DESCRIPTION OF THE EMBODIMENTS Reference will be made in detail to embodiments of the present disclosure, and the examples of the embodiments are illustrated in the drawings, where the same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions. The embodiments described below with reference to drawings are illustrative, and intended for explaining the present disclosure. The embodiments shall not be construed to limit the present disclosure. In descriptions of the present disclosure, it should be understood that, directions or positional relationships indicated by terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer", etc. are based on orientations or positional relationships shown in the accompanying drawings, and they are used only for describing the present disclosure and for description simplicity, but do not indicate or imply that an indicated device or element must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present disclosure. In addition, the terms such as "first" and "second" are merely used for purposes of description and are not intended to indicate or imply relative importance or to imply the number of indicated technical features. Thus, the feature defined with "first" and "second" may include one or more of this feature explicitly or implicitly. In the description of the present disclosure, "a plurality of means two or more unless otherwise specified. In the present disclosure, unless specified or limited otherwise, the terms "mounted", "connected", "coupled", "fixed" and the like are used broadly, and may be, for example, fixed connections, detachable connections, or integral connections; may also be mechanical or electrical connections; may also be direct connections or indirect connections via intervening structures; may also be inner communications of two elements. The above terms can be understood by those skilled in the art according to specific situations. With reference to FIG. 1, a multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation includes an inlet tube 1, where the inlet tube 1 is provided in a cylindrical shape, a spiral impeller 11 is mounted in the inlet tube 1 in the axis direction, a series of rib protrusions are processed on a surface of each blade of the spiral impeller 11, gas injection holes 10 are evenly arranged at 90-degree intervals in the circumferential direction of a wall surface of the inlet tube 1, a top of the inlet tube 1 is in fluid communication with a Venturi tube body 2, the Venturi tube body 2 includes a throat tube section 12 and an expansion section, the expansion section is fixedly connected to a top of the throat tube section 12 and is in a horn shape with a large upper part and a small lower part, an outer side wall of a ring tube 3 is fixedly connected to the expansion section of the Venturi tube body 2, the ring tube 3 is of a spherical structure and is a hollow tube with a circular cross section, a circular hollow part is arranged on an inner side of the ring tube 3, a top of the ring tube 3 is in fluid communication with flowdividing throat tubes 4, an outer wall of the ring tube 3 extends outside the Venturi tube body 2, an outer wall of the inlet tube 1 is in fluid communication with arc-shaped throat tubes 5, the two arc-shaped throat tubes are arranged on two sides of the Venturi tube body 2 in a suspended manner respectively, top ends of the arc-shaped throat tubes 5 are in fluid communication with the ring tube 3, a flow-blocking body 6 located on the inner side of the ring tube 3 is arranged in the expansion section of the Venturi tube body 2, the flow-blocking body 6 is located in the circular hollow part on the inner side of the ring tube 3, and a gap between the flow-blocking body 6 and an inner side wall of the ring tube 3 forms an annular flow-blocking region. With reference to FIG. 1, the inlet tube 1 is of a hollow cylindrical straight tube structure, and such a structure may increase an inflow velocity relative to a conical structure to generate a relatively large pressure drop in the tube, and meanwhile reduce disturbance intensity, and finally achieve the aims of increasing the cavitation intensity in a diffusion section and effectively guaranteeing hydrodynamic cavitation generation. Referring to FIG. 1, the gas injection holes are evenly arranged at 90-degree intervals in the circumferential direction on the wall surface of the inlet tube 1. As an optimized technical solution of the present disclosure, inert gas is additionally injected into the tube through the gas injection holes located in a high pressure region of the inlet tube, which does not increase the pressure value of a low pressure region of a throat, and can additionally increase the number of bubbles in fluid to provide gas cores necessary for cavitation generation, so as to achieve the purpose of strengthening hydrodynamic cavitation generation. Referring to FIG. 1, the spiral impeller 11 is mounted at the axial position in the Venturitube inlet tube 1. As an optimized technical solution of the present disclosure, the rotation of the spiral impeller adds additional disturbance to a water body, increases the kinetic energy of water flow, and provides beneficial conditions for strengthening of a cavitation phenomena. Protruding ribs on each of the blades of the impeller increase the contact area between the blade and the water body, such that the disturbance of the fluid is intensified to form more cavitation bubbles, so as to achieve the aim of strengthening cavitation generation. A series of bubbles are induced at the inlet tube 1 by the thin and sharp blades, and the bubbles move with an eddy current flow, thus avoiding cavitation erosion damage to the blades caused by direct collapse on the surfaces of the blades. After entering the Venturi tube body, the bubbles are gathered near the axis of the tube under the action of a centrifugal force provided by the spiral impeller, which ensures that the position of hydrodynamic cavitation generation is apart from an inner wall surface of a Venturi tube, thus achieving the aim of reducing cavitation erosion damage to the wall of the tube by collapse of the bubbles while cavitation generation conditions are met. Referring to FIG. 1, permanent magnets 7 are fixedly connected to each of inner walls of the expansion section of the Venturi tube body 2, the ring tube 3 and the flow-blocking body 6. As an optimized technical solution of the present disclosure, the permanent magnets 7 are arranged, and a magnetic field generated by the permanent magnets 7 may prolong the service life of active free radicals, thereby achieving the purpose of greatly reducing the risk of accumulating pathogenic microorganisms in the mineral flotation column. Referring to FIG. 1, the flow-blocking body 6 is hollow, an opening is arranged at each of a top and a bottom of the flow-blocking body 6, and the opening at the bottom is smaller than the opening at the top of the flow-blocking body 6. As an optimized technical solution of the present disclosure, the hollow flow-blocking body 6 is arranged, the water flow may be divided by the flow-blocking body 6 after entering the expansion section through the throat tube section, one part of the water flow passes through the hollow part of the flow-blocking body 6, the other part of the water flow slides over an outer wall of the flow-blocking body 6, and since the flow-blocking body 6 has a small inlet and a large inner space and outlet to form a shape similar to a Venturi tube, the water flow passing through the inner part of the flow-blocking body 6 can induce secondary cavitation phenomenon. Referring to FIG. 1, fixed rods 8 are fixedly connected to the outer wall of the flow-blocking body 6, an end of each of the fixed rods 8 apart from the flow-blocking body 6 is fixedly connected to a respective one of the inner wall of the Venturi tube body 2 and the ring tube 3, and a distance between the flow-blocking body 6 and the ring tube 3 is less than a hole diameter of the throat tube section of the Venturi tube body 2. As an optimized technical solution of the present disclosure, by providing the fixed rods 8 for connection, the flow-blocking body 6 may be suspended on the inner side of the ring tube 3, and may be thus matched with the ring tube 3 to reduce a diameter through which the water flow passes, and the water flow sliding over the outer wall of the flow-blocking body 6 can generate cavitation bubbles.. Referring to FIG. 1, a hole diameter of the arc-shaped throat tubes 5 and a hole diameter of the flow-dividing throat tubes 4 are both less than a hole diameter of the ring tube 3. As an optimized technical solution of the present disclosure, the hole diameter of the arcshaped throat tubes 5 and the hole diameter of the flow-dividing throat tubes 4 are set to be both less than the hole diameter of the ring tube 3, such that after cavitated by the matched arc-shaped throat tubes 5 and ring tube 3, the water flow is guided by the flow-dividing throat tubes 4, and the water flow in the ring tube 3 can be subjected to convection collision after discharged from the tube, thus promoting generation of the cavitation bubbles and enhancing cavitation intensity. Referring to FIG. 1, a porous plate 9 is fixedly connected to an interior of each of the arcshaped throat tubes 5. As an optimized technical solution of the present disclosure, the porous plates 9 are arranged, the fluid enters the fluid inlet tube 1 and passes through the porous plates 9, and due to a throttling effect of the porous plates 9, a flow rate is increased, and the hydrostatic pressure is reduced, and when the local pressure reaches or is even lower than saturated vapor pressure of the fluid at the temperature, the cavitation appears in the form of vapor-filled bubbles, and the gas trapped within the crevices of particle surfaces is considered as additional cavitation nuclei, thus achieving a cavitation assisting effect. After entering from the inlet tube 1, the water flow enters the arc-shaped throat tubes 5 and the throat tube section 12 of the Venturi tube body 2 and is divided into a plurality of streams of water flow for cavitation, the water flow passes through the porous plates 9 after entering the arcshaped throat tubes 5, and due to the throttling effect of the porous plates 9, the flow rate is increased, and the hydrostatic pressure is reduced, and when the pressure reaches or is even lower than the saturated vapor pressure of the fluid at the temperature, the cavitation appears in the form of vapor-filled bubbles, and the trapped gas within the crevices of particle surfaces are considered as additional cavitation nuclei, thus achieving the cavitation assisting effect; then, the fluid enters the ring tube 3 for cavitation and is then discharged from the flow-dividing throat tubes 4 for convection collision, the water flow passing through the throat tube section of the Venturi tube body 2 enters the expansion section for one-time cavitation and is then blocked and divided by the flow-blocking body 6, one stream of water flow enters the flow-blocking body 6 for cavitation, and other water flow flows against the outer wall of the flow-blocking body 6, and the water flow flows to the annular flow-blocking region formed by the gap between the flow-blocking body 6 and the inner side wall of the ring tube 3 for cavitation, thereby achieving the aim of plural times of cavitation. In the description of the present specification, reference throughout this specification to "an embodiment", "some embodiments", "example", "specific example" or "some examples" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In the specification, the schematic expressions to the above-mentioned terms are not necessarily referring to the same embodiment or example. Furthermore, the described particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. Although embodiments of the present disclosure have been shown and illustrated, it shall be understood that the above-mentioned embodiments are exemplary and not construed as limitations to the present disclosure. Various changes, modifications, alternatives and variants within the scope of the present disclosure may be made by those skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

What is claimed is:

1. A multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation, comprising an inlet tube (1) and a Venturi tube body (2), characterized in that the Venturi tube body (2) comprises an expansion section and a throat tube section (12); an input end of the throat tube section (12) is in fluid communication with an output end of the inlet tube (1), and an output end of the throat tube section (12) is connected to the expansion section; the expansion section is a divergent tube, and a flow-blocking body (6) is arranged in the expansion section by means of fixed rods (8); the flow-blocking body (6) is of a hollow structure; the output end of the inlet tube (1) is in fluid communication with arc-shaped throat tubes (5), the arc-shaped throat tubes (5) are in fluid communication with a ring tube (3), and flow-dividing throat tubes (4) are arranged at an output end of the ring tube (3); and output ends of the flow-dividing throat tubes (4) are arranged in the expansion section above the flow-blocking body (6);wherein the inlet tube (1) is of a hollow cylindrical structure, and gas injection holes (10) are formed in side walls of the inlet tube (1); a plurality of holes are formed in a bottom surface of the hollow cylindrical structure, and the holes on the inlet tube (1) are in fluid communication with the arc-shaped throat tubes (5) and the throat tube section (12).

2. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 1, characterized in that a spiral impeller (11) is arranged in the inlet tube (1).

3. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 2, characterized in that blades of the spiral impeller (11) are supercavitation blades.

4. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 1, characterized in that a diameter of the arc-shaped throat tubes (5) and a diameter of the flow-dividing throat tubes (4) are both less than a diameter of the ring tube (3).

5. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 1, characterized in that a porous plate (9) is arranged in each of the arc-shaped throat tubes (5).

6. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 1, characterized in that permanent magnets (7) are arranged in each of the flow-blocking body (6) and the ring tube (3).

7. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 1, characterized in that the ring tube (3) is of a spherical structure.

8. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 1, characterized in that the flow-blocking body (6) is a hollow tube and is in a divergent shape in a fluid direction.

9. The multichannel Venturi-tube hydrodynamic cavitation generating device for mineral flotation according to claim 1, characterized in that the gas injection holes (10) are distributed on the inlet tube (1) at equal intervals in a circumferential direction.

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