Device for applying bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined Venturi tube to landfill leachate treatment

Abstract

The invention relates to a device for applying bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a Venturi tube to landfill leachate treatment, and relates to the technical field of landfill leachate treatment. The device comprises a two-way high-speed shearing wheel set and a Venturi tube array, wastewater sequentially flows through a reverse rotation series wheel set, a connecting section and a forward rotation series wheel set, cavitation is generated at an outlet of the wheel set to generate free radicals, and the mass transfer effect is improved through a shearing structure. And a high-speed multiphase flow formed at the outlet of the wheel set forms a vortex after passing through the winding fluid at the connecting section, and collides with the fluid jetted by the Venturi tube array, so that the uniformity of free radicals in the wastewater is enhanced, the dissolved amount of a gas treatment agent is increased, and the cavitation effect of the subsequent wheel set is improved. The total amount of free radicals at the outlet of the forward rotation series wheel set is large, the free radicals are uniformly distributed, the density of free radicals at the outlet of the reverse rotation series wheel set is large, the energy is high, and high-concentration organic pollutants such as ammonia nitrogen and chemical oxygen demand and non-degradable trace new pollutants such as perfluorinated / polyfluorinated compounds and microplastics in the leachate can be synergistically removed.

Description

Technical Field

[0001] The present application relates to the technical field of landfill leachate treatment, and in particular to a device for treating landfill leachate using a bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube. Background Art

[0002] Landfill leachate is a highly polluted and complex wastewater, and its treatment is very challenging. There are many types of organic pollutants in landfill leachate, and the content of organic pollutants is usually high. The values ​​of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) are large. In addition, it contains low-concentration pollutants that are difficult to degrade, such as perfluorinated polyfluorinated compounds (PFAS), microplastics and other new pollutants. The composition and concentration of organic pollutants will change significantly with factors such as the age of the landfill, climatic conditions, and garbage composition. As the landfill time increases, the organic pollutants in the leachate gradually become difficult to be biodegraded, resulting in increased difficulty in treatment. Some organic pollutants are highly toxic and may cause serious harm to the ecological environment and human health.

[0003] The treatment methods of leachate from landfills at home and abroad mainly include physical and chemical treatment, biological treatment, land treatment, etc. The treatment method of leachate from domestic landfills in my country is mainly membrane-based. The leachate after membrane treatment can achieve standard discharge and produce high-concentration concentrate, which is further treated by reinjection, biochemical, evaporation, and furnace incineration. For example, the external membrane biochemical reactor-nanofiltration / reverse osmosis (MBR+NF / RO) technology is one of the most common leachate treatment technologies. However, the biodegradability of the concentrate is poor, and the difficult organic pollutants and heavy metals are highly toxic to microorganisms. Functional microorganisms are difficult to adapt to the environment where multiple heavy metals and organic pollutants coexist in the leachate. Expansion and propagation cannot be guaranteed, and there is no mature technology yet. In addition, the functions of microorganisms are usually single and cannot synergistically remove multiple organic pollutants. Advanced oxidation process and thermal treatment process are two other commonly used technologies for concentrate treatment, but they usually require a large amount of reagents or energy consumption, which does not meet the requirements of pollution reduction and carbon reduction policies. The hydrodynamic cavitation oxidation technology uses the high temperature, high pressure and strong shock waves generated by the hydrodynamic cavitation phenomenon to decompose water molecules to produce highly oxidizing hydroxyl free radicals and other active oxygen species, thereby oxidizing and decomposing organic pollutants in the water. The hydrodynamic cavitation technology has strong oxidation ability and rapid reaction. It can oxidize and decompose organic pollutants in a short time without secondary pollution. It does not require the addition of additional chemicals, so it does not generate additional energy consumption. It is an energy-saving water treatment technology.

[0004] The hydraulic cavitation device directly affects the cavitation effect and water treatment effect. The hydraulic cavitation device can be divided into a venturi tube cavitation generator, a perforated plate cavitation generator, a rotary cavitation generator and a vortex cavitation generator. The cavitation effects of cavitation generators with different structures vary greatly. The invention patent with patent number ZL201210040830.8 proposes a combined hydraulic cavitation device for degrading organic matter in wastewater, which achieves a COD removal rate of 21.2% by connecting the venturi tube assembly and the sieve plate in series. The invention patent with application number 202410474247.0 proposes a wastewater treatment method combining oxidation and hydraulic cavitation. The cavitation generator is connected in series with a wet oxidation reactor to improve the overall treatment effect of the wastewater. The COD conversion rate is increased from 85% in hydraulic cavitation treatment alone to 96% in series treatment. The hydraulic cavitation oxidation technology and its combination technology reported so far mostly report the removal effects of conventional organic matter such as COD and ammonia nitrogen, but have limited removal effects on trace and difficult-to-degrade new pollutants. It is now necessary to develop hydraulic cavitation devices for the coordinated treatment of new pollutants such as perfluorinated and polyfluorinated compounds, microplastics, and various organic matter such as ammonia nitrogen, COD, and BOD in landfill leachate. Summary of the invention

[0005] The purpose of the present application is to provide a device for treating landfill leachate by using a bidirectional multi-stage rotary shear high-speed multiphase flow hydraulic cavitation combined with a venturi tube. The device targets various organic pollutants in landfill leachate and leachate concentrate, removes trace pollutants by using the high-density hydroxyl groups generated by the reverse series wheel group, and removes high-concentration organic pollutants by using the large amount of evenly distributed hydroxyl groups generated by the forward series wheel group, thereby achieving the removal of various organic pollutants in landfill leachate.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a device for treating landfill leachate by using bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube, the device comprising a motor, a shaft assembly, a housing, a reverse series wheel set, a forward series wheel set, a venturi tube, a fluid body and a coupling, the reverse series wheel set and the forward series wheel set are installed at opposite ends of the housing and connected by the shaft assembly, the motor is installed at an end of the housing and connected to the shaft assembly, a water inlet is provided at one end of the housing close to the reverse series wheel set, and a water outlet is provided at one end of the housing close to the forward series wheel set;

[0007] The leachate of the garbage to be treated enters the reverse series wheel group radially from the water inlet, and then enters the forward series wheel group through the connecting section of the shell. A Venturi tube and a fluid flow are arranged on the connecting section. The fluid flow is placed upstream of the Venturi tube. The Venturi tube is used to add gas or liquid to the leachate.

[0008] In an optional embodiment, the installation directions of the reverse tandem wheel group and the forward tandem wheel group on the shaft assembly are opposite, the reverse tandem wheel group and the forward tandem wheel group include 1 to 5 levels of shear wheel groups, and the shear wheel groups included in the reverse tandem wheel group and the forward tandem wheel group may be inconsistent.

[0009] In an optional embodiment, the shaft assembly includes a transmission shaft, a bearing and a protective sleeve, the bearing is sleeved on the transmission shaft, the protective sleeve is sleeved on the bearing, the ratio of the diameter d of the transmission shaft to the diameter D of the connecting section is 0.1 to 0.4, and the value of the diameter d of the transmission shaft is positively correlated with the rotational speed.

[0010] In an optional embodiment, the reversing tandem wheel group includes a plurality of reversing shearing wheel groups arranged in sequence and at intervals, and the reversing shearing wheel group includes a fixed shearing wheel, a rotating wheel and a movable shearing wheel arranged in sequence and stacked, wherein the fixed shearing wheel is provided with bolt holes and guide grooves, the fixed shearing wheel is connected to the shell through the bolt holes, the movable shearing wheel is provided with shear blocks, and the movable shearing wheel and the rotating wheel are driven by the shaft assembly.

[0011] In an optional embodiment, the dynamic shear wheel is closer to the water inlet than the fixed shear wheel, the diameter of the dynamic shear wheel is smaller than the inner diameter of the shell, and a channel for leachate to pass through is formed between the edge of the dynamic shear wheel and the inner surface of the shell.

[0012] In an optional embodiment, the center hole of the fixed shear wheel is connected to the center hole of the rotating wheel to form a water flow channel. When the reverse series wheel group rotates, the guide groove on the edge of the fixed shear wheel and the shear block on the edge of the rotating dynamic shear wheel form a shearing effect, which intensifies the cavitation phenomenon of the leachate and forms asymmetric cavitation bubbles.

[0013] In an optional embodiment, a plurality of guide grooves are evenly arranged on the edge of the fixed shear wheel, a plurality of shear blocks are evenly arranged on the edge of the movable shear wheel, and the number of guide grooves and shear blocks is the same, and the number is 6 to 12.

[0014] In an optional embodiment, the number of guide grooves in the reverse tandem wheel set is less than the number of guide grooves in the forward tandem wheel set.

[0015] In an optional embodiment, the inlet flow rate of the reverse series wheel group is 20kg / min-200kg / min, the inlet pressure is 0.5-5MPa, the rotation speed is 1000 rpm-8000 rpm, and the rotation speed is inversely proportional to the inlet flow rate and pressure values.

[0016] In an optional embodiment, the venturi tube and the flow body are arranged in a group, and the incoming flow forms a vortex downstream after flowing through the flow body, thereby enhancing the collision effect with the fluid at the outlet of the venturi tube.

[0017] In an optional embodiment, the number of Venturi tubes and vortex bodies is 4 to 10 groups, the installation angle α of the Venturi tube relative to the flow direction in the connecting section is 0 to 30°, the ratio of the diameter dw of the Venturi tube to the diameter D of the connecting section is 0.1 to 0.3, the value of dw is inversely proportional to the value of the diameter d of the drive shaft, and the installation height of the Venturi tube is 0.1 to 0.2D from the tube wall of the connecting section, ensuring that the fluid injection cross-section at the Venturi tube outlet fully covers the cross-section of the connecting section.

[0018] In an optional embodiment, the gas or liquid sprayed by the venturi tube includes at least one of air, oxygen, ozone, and recycled treated water.

[0019] In an optional embodiment, Venturi tubes and vortex bodies are arranged at the outlet of the reverse tandem wheel set and the inlet of the forward tandem wheel set. When the device is running, the Venturi tube whose outlet is consistent with the water flow direction in the connecting section will work, and the Venturi tube in the opposite direction will be closed.

[0020] Through the above technical scheme, the leachate of the garbage to be treated enters the reverse series wheel group radially from the water inlet, and then enters the forward series wheel group through the connecting section. Venturi tubes are arranged at both ends of the connecting section to add gas or liquid to the leachate. The gas or liquid is ejected after being accelerated by the Venturi tube, and mixed with the leachate flow to form a high-speed multiphase flow, thereby improving the cavitation effect in the wheel group. The hydroxyl radical density and energy at the outlet of the shear wheel group of the reverse series wheel group are large, and can be used for the removal of difficult-to-degrade and trace organic pollutants. The total amount of hydroxyl radicals at the outlet of the shear wheel group of the forward series wheel group is large and evenly distributed, which can be used for the removal of high-concentration organic pollutants such as ammonia nitrogen and chemical oxygen demand (COD). The leachate that does not meet the standards at the water outlet is introduced into the device through the water inlet for further treatment, or discharged after meeting the standards, thereby achieving the removal of various organic pollutants in the garbage leachate. The device provided in this embodiment has the advantages of strong applicability, good cavitation effect, and reliable structure.

[0021] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the structure of a device for treating landfill leachate using a bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube provided in an embodiment of the present application;

[0024] Figure 2 for Figure 1 Structural schematic diagram of a center-reversed tandem wheel set;

[0025] Figure 3 A schematic diagram of the exploded structure of the inverted tandem wheel set from one perspective;

[0026] Figure 4 A schematic diagram of the exploded structure of the inverted tandem wheelset from another perspective;

[0027] Figure 5 It is a structural schematic diagram of the shaft assembly in the connecting section;

[0028] Figure 6 A schematic diagram of the array installation of the venturi tube and the fluid flow around it;

[0029] Figure 7 Two schematic diagrams showing the relationship between the diameter of the transmission shaft and the diameter and number of the Venturi tubes;

[0030] Figure 8 It is the histogram of cavitation rate;

[0031] Fig. 9 is the distribution diagram of hydroxyl radicals;

[0032] Fig.10 is the volume distribution streamline diagram of hydroxyl radicals.

[0033] Icons: 1-motor; 2-shaft assembly; 21-drive shaft; 22-bearing; 23-protective sleeve; 3-housing; 31-water inlet; 32-water outlet; 4-reverse tandem wheel group; 41-first-stage reverse shear wheel group; 42-second-stage reverse shear wheel group; 43-third-stage reverse shear wheel group; 411-fixed shear wheel; 412-rotating wheel; 413-moving shear wheel; 4111-bolt hole; 4112-guide groove; 4131-shear block; 5-forward tandem wheel group; 51-first-stage forward shear wheel group; 52-second-stage forward shear wheel group; 53-third-stage forward shear wheel group; 6-Venturi tube; 7-fluid body; 8-coupling. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0035] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0036] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] Please refer to Figure 1 This embodiment provides a device (hereinafter referred to as the device) for treating landfill leachate using a bidirectional multi-stage rotary shear high-speed multiphase flow hydraulic cavitation combined with a venturi tube, both of which have three stages of reverse series wheel groups and forward series wheel groups, and uses a high-speed multiphase flow coupled with a venturi effect. Specifically, the device includes a bidirectional high-speed shear wheel group and a venturi tube array, wherein the bidirectional high-speed shear wheel group includes a motor 1, a shaft assembly 2, a housing 3, a reverse series wheel group 4, a forward series wheel group 5, a vortex body 7, and a coupling 8, and the venturi tube array includes a plurality of venturi tubes 6.

[0038] The reverse tandem wheel set 4 and the forward tandem wheel set 5 are installed at opposite ends of the housing 3 and connected by the shaft assembly 2. The reverse tandem wheel set 4 and the forward tandem wheel set 5 are installed in opposite directions on the shaft assembly 2. The motor 1 is installed at one end of the housing 3 and connected to one end of the shaft assembly 2. The two ends of the housing 3 are provided with couplings 8, which are respectively connected to the two ends of the shaft assembly 2. In this embodiment, the reverse tandem wheel set 4 is arranged closer to the motor 1 than the forward tandem wheel set 5.

[0039] Please refer to Figures 5 to 7 The shaft assembly 2 includes a transmission shaft 21, a bearing 22 and a protective sleeve 23. The bearing 22 is sleeved on the transmission shaft 21, and the protective sleeve 23 is sleeved on the bearing 22. The ratio of the diameter d of the transmission shaft 21 to the diameter D of the connecting section is 0.1 to 0.4. The value of the diameter d of the transmission shaft 21 is positively correlated with the rotation speed. The number of the venturi tube 6 and the vortex body 7 is 4 to 10 groups (please refer to Figure 7 , Figure 7, a structure in which the number of Venturi tubes 6 and circumferential bodies 7 is 4 groups, and a structure in which the number of Venturi tubes 6 and circumferential bodies 7 is 10 groups is shown). The installation angle α of the Venturi tube 6 relative to the flow direction in the connecting section is 0-30°, and the angle between two adjacent Venturi tubes 6 can also be α. The ratio of the diameter dw of the Venturi tube 6 to the diameter D of the connecting section is 0.1-0.3, and the value of dw is inversely proportional to the value of the diameter d of the transmission shaft 21. The installation height of the Venturi tube 6 is 0.1-0.2D from the pipe wall of the connecting section, ensuring that the fluid injection cross-section at the outlet of the Venturi tube 6 fully covers the cross-section of the connecting section.

[0040] A water inlet 31 is provided on one end of the shell 3 near the reverse series wheel set 4, and a water outlet 32 ​​is provided on one end of the shell 3 near the forward series wheel set 5; the leachate of the garbage to be treated enters the reverse series wheel set 4 radially from the water inlet 31, and then enters the forward series wheel set 5 through the connecting section of the shell 3, on which a venturi tube 6 and a vortex body 7 are arranged, and the vortex body 7 is placed upstream of the venturi tube 6. The venturi tube 6 and the vortex body 7 are arranged in a group array, and the incoming flow forms a vortex downstream after passing through the vortex body 7, thereby enhancing the collision effect with the fluid at the outlet of the venturi tube 6.

[0041] The venturi tube 6 is used to add gas or liquid to the leachate, and the gas or liquid is ejected after being accelerated by the venturi tube 6, and mixed with the leachate flow to form a high-speed multiphase flow. The hydroxyl radical density and energy at the outlet of the shear wheel group of the reverse series wheel group 4 are large, and can be used to remove difficult-to-degrade and trace organic pollutants (such as new pollutants such as perfluorinated / polyfluorinated compounds). The total amount of hydroxyl radicals at the outlet of the shear wheel group of the forward series wheel group 5 is large and evenly distributed, and can be used to remove high-concentration organic pollutants such as ammonia nitrogen and chemical oxygen demand (COD). The leachate that does not meet the standards at the water outlet 32 ​​is introduced into the device through the water inlet 31 for further treatment, or discharged after meeting the standards, thereby achieving the removal of multiple organic pollutants in the garbage leachate.

[0042] The reverse series wheel set 4 and the forward series wheel set 5 are respectively composed of multiple stages of shear wheel sets connected in series. The number of shear wheel sets contained in the reverse series wheel set 4 and the forward series wheel set 5 may be inconsistent, and the number of wheel set stages may be increased or decreased according to the processing effect.

[0043] In this embodiment, the reverse series wheel group 4 includes three reverse shear wheel groups arranged in sequence at intervals. The water flow in the reverse series wheel group 4 flows in radially from the edge of the first-stage reverse shear wheel group 41, flows out from the center hole of the first-stage reverse shear wheel group 41, and then flows through the second-stage reverse shear wheel group 42 and the third-stage reverse shear wheel group 43 in sequence. After that, the high-speed multiphase flow enters the forward series wheel group 5 through the connecting section. The water flow in the first-stage forward shear wheel group 51 flows in axially, flows out radially from the edge of the forward shear wheel group, and then flows through the second-stage forward shear wheel group 52 and the third-stage forward shear wheel group 53 in sequence. Downstream of the water flow flowing through the shear wheel group, due to the huge pressure difference between the inlet and outlet, the leachate to be treated will undergo cavitation near the center hole of the reverse shear wheel group and the edge area of ​​the forward shear wheel group. In addition, since the leachate to be treated is pressurized layer by layer through the shear wheel group, the liquid flow rate at the outlet of the shear wheel group increases step by step, the pressure difference between the inlet and outlet of the shear wheel group increases, and the cavitation phenomenon will be aggravated.

[0044] The number of shear wheel groups of the forward series wheel group 5 and the reverse series wheel group 4 can be increased or decreased according to the treatment effect. When the concentration of difficult-to-treat micro-pollutants is high, the number of reverse series wheel groups 4 can be appropriately increased. When the concentration of conventional pollutants such as ammonia nitrogen and COD is high, the number of forward series wheel groups 5 can be appropriately increased. In addition, the forward series wheel group 5 and the reverse series wheel group 4 can be switched by changing the direction of the motor 1. This operation can effectively solve the problem of shear wheel blockage.

[0045] The venturi tube 6 includes two groups, each group contains 4-10 pipes, and is evenly arranged around the connecting section. When the device is running, the venturi tube 6 that is consistent with the water flow direction will work, and the venturi tube 6 will be used to spray at least one of air, oxygen, ozone, and circulating treatment effluent. A high-speed airflow will be formed at the outlet of the venturi tube 6. At the same time, the leachate will form a vortex downstream after flowing through the vortex body 7. The fluid sprayed from the venturi tube 6 and the leachate vortex will be fully collided and mixed, thereby increasing the solubility of the gas in the leachate, and thereby increasing the cavitation effect in the subsequent wheel group. In addition, according to the leachate treatment effect, the outlet water of the device can also be introduced into the venturi tube 6 to complete the collision and mixing with the wastewater to be treated, thereby improving the circulation treatment effect of the wastewater to be treated.

[0046] Venturi tubes 6 and circumferential bodies 7 are arranged at the outlet of the reverse tandem wheel set 4 and the inlet of the forward tandem wheel set 5. When the device is running, the Venturi tube 6 whose outlet is consistent with the water flow direction in the connecting section will work, and the Venturi tube 6 in the opposite direction will be closed.

[0047] Please refer to Figures 2 to 4The reversing shear wheel group includes a fixed shear wheel 411, a rotating wheel 412 and a movable shear wheel 413 which are stacked in sequence, wherein the movable shear wheel 413 is closer to the water inlet 31 than the fixed shear wheel 411, a bolt hole 4111 and a guide groove 4112 are arranged on the fixed shear wheel 411, the fixed shear wheel 411 is connected to the shell 3 through the bolt hole 4111, a shear block 4131 is arranged on the movable shear wheel 413, and the movable shear wheel 413 and the rotating wheel 412 are driven by the shaft assembly 2.

[0048] The diameter of the dynamic shear wheel 413 is smaller than the inner diameter of the housing 3, and a channel for the leachate to pass through is formed between the edge of the dynamic shear wheel 413 and the inner surface of the housing 3. The central hole of the fixed shear wheel 411 is connected with the central hole of the rotating wheel 412 to form a water flow channel. When the reverse series wheel group 4 rotates, the guide groove 4112 driven by the edge of the fixed shear wheel 411 and the shear block 4131 on the edge of the rotating dynamic shear wheel 413 form a shearing effect, which intensifies the cavitation phenomenon of the leachate, forms asymmetric cavitation, and improves the mass transfer rate.

[0049] A plurality of guide grooves 4112 are evenly arranged on the edge of the fixed shear wheel 411, and a plurality of shear blocks 4131 are evenly arranged on the edge of the movable shear wheel 413. The number of guide grooves 4112 and shear blocks 4131 is the same, and the number is 6 to 12. The number of guide grooves 4112 in the reverse series wheel set 4 is less than the number of guide grooves 4112 in the forward series wheel set 5 to reduce the inlet resistance, and the number of guide grooves 4112 in the forward series wheel set 5 is large to improve the shearing effect.

[0050] The inlet flow rate of the reverse series wheel group 4 is 20kg / min-200kg / min, the inlet pressure is 0.5-5MPa, the speed is 1000 rpm-8000 rpm, and the speed and the inlet flow rate are inversely proportional. The inlet and outlet pressure difference of the shear wheel group required for cavitation is achieved by adjusting the speed, inlet pressure or flow rate. When the number of shear wheel groups increases, the inlet flow rate / pressure or speed can be appropriately reduced.

[0051] Example 1

[0052] The device provided in the specific embodiment was used to perform fluid dynamics calculations on the device using ANSYS software. The simulated component was a forward-rotating series wheel group 5, the number of guide grooves 4112 and shear blocks 4131 were both 10, the inlet flow rate was 180 kg / min, the rotation speed was forward 6000 rpm, and the cavitation rate, hydroxyl radical distribution and volume fraction streamlines in the single-stage shear wheel group were as follows: Figures 8 to 10The maximum cavitation rate in the forward shear wheel group reaches 86.33%, the average cavitation rate is 25.36%, the hydroxyl radicals are mainly distributed at the radial outlet of the shear wheel group, the local maximum free radical volume fraction is 16.1%, the hydroxyl radicals are evenly distributed around the shear wheel group, and the maximum streamline velocity through the outlet of the shear wheel group is about 0.83 / s.

[0053] Example 2

[0054] The other conditions are the same as those in Example 1. The shear wheel group is changed in direction, and the speed of the shear wheel group is reversed at 6000 rpm. The cavitation rate, hydroxyl radical distribution and volume fraction streamlines in the single-stage shear wheel group during reverse rotation are as follows: Figures 8 to 10 The maximum cavitation rate in the reverse shear wheel group is 54.86%, the average cavitation rate is 1.55%, the hydroxyl radicals are mainly concentrated at the central outlet, the maximum volume fraction of hydroxyl radicals is about 8.40%, and the hydroxyl radicals are concentrated in the outlet pipe during reversal, with a maximum streamline velocity of about 337 / s.

[0055] It can be seen that the volume fraction of hydroxyl radicals at the outlet of the shear wheel group is large during forward rotation, but the maximum streamline velocity is much smaller. The distribution of hydroxyl radicals at the outlet of the shear wheel group is relatively uniform, which can be used to remove a large number of conventional organic matter. During reverse rotation, although the maximum volume fraction of hydroxyl radicals is 8.4%, the maximum streamline velocity reaches 337 / s. The hydroxyl radicals are concentrated in the outlet pipe, with high energy density, which can be used to remove residual difficult-to-degrade and trace organic pollutants. The leachate is circulated through the forward series wheel group 5 and the reverse series wheel group 4 until it meets the discharge standards.

[0056] The beneficial effects of the device provided in this embodiment for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube include:

[0057] The leachate of the garbage to be treated enters the reverse series wheel group 4 radially from the water inlet 31, and then enters the forward series wheel group 5 through the connecting section. Venturi tubes 6 are arranged at both ends of the connecting section for adding gas or liquid to the leachate. The gas or liquid is accelerated by the Venturi tube 6 and ejected, mixed with the leachate flow to form a high-speed multiphase flow, thereby improving the cavitation effect in the shear wheel group.

[0058] At the outlet of the shear wheel group of the reverse series wheel group 4, the hydroxyl radical density is large and the energy is high, which can be used to remove difficult-to-degrade and trace organic pollutants. At the outlet of the shear wheel group of the forward series wheel group 5, the total amount of hydroxyl radicals is large and evenly distributed, which can be used to remove high-concentration organic pollutants such as ammonia nitrogen and chemical oxygen demand (COD). The leachate that does not meet the standards at the outlet 32 ​​is introduced into the device through the water inlet 31 for further treatment, or is discharged after meeting the standards, thereby realizing the removal of various organic pollutants in the landfill leachate.

[0059] The device provided in this embodiment has the advantages of strong applicability, good cavitation effect, and reliable structure.

[0060] It should be noted that, in the absence of conflict, the features in the embodiments of this application may be combined with each other.

[0061] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A device for treating landfill leachate by using bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube, characterized in that: The device comprises a motor (1), a shaft assembly (2), a housing (3), a reverse tandem wheel set (4), a forward tandem wheel set (5), a venturi tube (6), a fluid flow path (7) and a coupling (8); the reverse tandem wheel set (4) and the forward tandem wheel set (5) are mounted at opposite ends of the housing (3) and are connected via the shaft assembly (2); the motor (1) is mounted at an end of the housing (3) and is connected to the shaft assembly (2) via the coupling (8); a water inlet (31) is provided on one end of the housing (3) close to the reverse tandem wheel set (4); and a water outlet (32) is provided on one end of the housing (3) close to the forward tandem wheel set (5); The leachate of the garbage to be treated enters the reverse series wheel set (4) radially from the water inlet (31), and then enters the forward series wheel set (5) through the connecting section of the shell (3). The venturi tube (6) and the vortex body (7) are arranged on the connecting section. The vortex body (7) is placed upstream of the venturi tube (6). The venturi tube (6) is used to add gas or liquid to the leachate.

2. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 1 is characterized in that: The reverse tandem wheel set (4) and the forward tandem wheel set (5) are installed on the shaft assembly (2) in opposite directions.

3. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 1 is characterized in that: The shaft assembly (2) comprises a transmission shaft (21), a bearing (22) and a protective sleeve (23); the bearing (22) is sleeved on the transmission shaft (21); the protective sleeve (23) is sleeved on the bearing (22); the ratio of the diameter d of the transmission shaft (21) to the diameter D of the connecting section is 0.1 to 0.4; and the value of the diameter d of the transmission shaft (21) is positively correlated with the rotation speed.

4. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 1 is characterized in that: The reverse tandem wheel group (4) comprises a plurality of reverse shear wheel groups arranged in sequence and at intervals, and the reverse shear wheel group comprises a fixed shear wheel (411), a rotating wheel (412) and a movable shear wheel (413) arranged in sequence and stacked, wherein the fixed shear wheel (411) is provided with a bolt hole (4111) and a guide groove (4112), the fixed shear wheel (411) is connected to the housing (3) via the bolt hole (4111), the movable shear wheel (413) is provided with a shear block (4131), and the movable shear wheel (413) and the rotating wheel (412) are driven by the shaft assembly (2).

5. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 4 is characterized in that: The dynamic shear wheel (413) is closer to the water inlet (31) relative to the fixed shear wheel (411), the diameter of the dynamic shear wheel (413) is smaller than the inner diameter of the shell (3), and a channel for leachate to pass through is formed between the edge of the dynamic shear wheel (413) and the inner surface of the shell (3).

6. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 5 is characterized in that: The central hole of the fixed shear wheel (411) is connected to the central hole of the rotating wheel (412) to form a water flow channel. When the reverse series wheel group (4) rotates, the guide groove (4112) on the edge of the fixed shear wheel (411) and the shear block (4131) on the edge of the rotating movable shear wheel (413) form a shearing effect, thereby intensifying the cavitation phenomenon of the leachate and forming asymmetric cavitation bubbles.

7. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 6 is characterized in that: The plurality of guide grooves (4112) are evenly arranged on the edge of the fixed shear wheel (411), and the plurality of shear blocks (4131) are evenly arranged on the edge of the movable shear wheel (413). The number of the guide grooves (4112) and the number of the shear blocks (4131) are the same, and the number is 6 to 12.

8. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 7 is characterized in that: The number of the guide grooves (4112) in the reverse series wheel set (4) is smaller than the number of the guide grooves (4112) in the forward series wheel set (5), so as to reduce the inlet resistance of the reverse series wheel set (4).

9. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 1, characterized in that: The inlet flow rate of the reverse tandem wheel group (4) is 20kg / min-200kg / min, the inlet pressure is 0.5-5MPa, the rotation speed is 1000 rpm-8000 rpm, and the rotation speed is inversely proportional to the inlet flow rate and pressure values.

10. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 3, characterized in that: The venturi tube (6) and the body flow (7) are arranged in a group, and after the incoming flow passes through the body flow (7), a vortex is formed downstream, thereby enhancing the collision effect with the fluid at the outlet of the venturi tube (6).

11. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 10, characterized in that: The gas or liquid sprayed by the venturi tube (6) includes at least one of air, oxygen, ozone, and recycled treated water.

12. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 10, characterized in that: The number of the Venturi tube (6) and the vortex body (7) is 4 to 10 groups, the installation angle α of the Venturi tube (6) relative to the flow direction in the connecting section is 0 to 30 degrees, the ratio of the diameter dw of the Venturi tube (6) to the diameter D of the connecting section is 0.1 to 0.3, the value of dw is inversely proportional to the value of the diameter d of the transmission shaft (21), and the installation height of the Venturi tube (6) is 0.1 to 0.2D from the tube wall of the connecting section, so as to ensure that the fluid injection cross section of the Venturi tube (6) outlet fully covers the cross section of the connecting section.

13. The device for treating landfill leachate by bidirectional multi-stage rotary shearing high-speed multiphase flow hydraulic cavitation combined with a venturi tube according to claim 10, characterized in that: The Venturi tube (6) and the vortex body (7) are arranged at the outlet of the reverse series wheel group (4) and the inlet of the forward series wheel group (5). When the device is in operation, the Venturi tube (6) whose outlet is consistent with the water flow direction in the connecting section will work, while the Venturi tube (6) in the opposite direction will be closed.

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