A system and method for degrading organic wastewater by hydrodynamic cavitation and plasma

Abstract

The present invention discloses a system and method for degrading organic wastewater using hydrodynamic cavitation and plasma. The system includes a liquid storage tank, an aeration device, and a plasma rotary cavitation reactor. The plasma rotary cavitation reactor includes a reactor shell, the reactor shell being provided with an organic wastewater inlet and an organic wastewater outlet. The aeration device is connected to the organic wastewater inlet. The liquid storage tank is connected to the aeration device. The present invention integrates plasma discharge technology with hydrodynamic cavitation technology, utilizing dielectric barrier plasma discharge to generate active substances such as ozone and hydroxyl radicals, and in conjunction with hydrodynamic cavitation technology, enhances the degradation of organic wastewater, thereby improving the wastewater degradation effect. Upper and lower rows of teeth with opposite tooth inclination angles are provided on the rotor, inducing a circulation flow of fluid between the cavitation area and the discharge area, further improving the gas-liquid mass transfer efficiency. By providing upper and lower jet cavitation channels with varying inner diameters and opposite directions, the pressure drop value when the fluid flows through the channels is changed, thereby enhancing the cavitation effect.

Description

Technical Field

[0001] The invention relates to a system and method for degrading organic wastewater by using hydrodynamic cavitation and plasma, and belongs to the technical field of organic wastewater degradation. Background Art

[0002] Since organic wastewater contains a large amount of difficult-to-degrade organic matter, the degradation process of organic wastewater has become a research hotspot in the environmental field. The combination of ozone oxidation and hydrodynamic cavitation is a new organic wastewater degradation technology. During the plasma discharge process, when the voltage applied between the electrodes is high enough, the gas medium between the electrodes is broken down, thereby generating a low-temperature plasma rich in active substances such as ozone, free radicals, electrons, and excited molecules, which can be used for the efficient degradation of organic wastewater. However, ozone molecules are difficult to dissolve in water, and hydrodynamic cavitation technology is required to increase the gas-liquid mass transfer intensity and promote the hydrolysis of ozone; except for ozone, the lifespan of other active substances is only milliseconds or microseconds. The chemical thermal effect generated when the cavitation bubble collapses can promote the generation of strongly oxidizing hydroxyl radicals (·OH) and other active substances, effectively enhancing the degradation of organic wastewater. Therefore, hydrodynamic cavitation synergistic plasma degradation technology is a very promising method for organic wastewater degradation.

[0003] The invention patent "System and method for degrading oily wastewater by miniaturized plasma combined with hydrodynamic cavitation" (Announcement No. CN117247083B) discloses a system and method for degrading oily wastewater by miniaturized plasma combined with hydrodynamic cavitation. Its working principle is to use the vortex effect to cause cavitation of the oily wastewater in the local negative pressure area within the reaction chamber, and then pass the high-energy active particles generated by the plasma discharge device into the reaction device to achieve the degradation of the oily wastewater. Although the device combines plasma discharge technology with hydrodynamic cavitation technology, the active substances such as hydroxyl radicals, high-energy electrons, and excited state molecules generated during plasma discharge have a life cycle of only microseconds or milliseconds. They are inactivated in the process of being transported into the cavitation chamber. Only ozone molecules can participate in the degradation reaction inside the cavitation chamber. The large amount of waste of active substances directly leads to low energy utilization of the degradation system and a relatively limited degradation effect.

[0004] The invention patent "A three-stage hydrodynamic cavitation treatment system for organic wastewater" (publication number CN 109824173 B) discloses a three-stage hydrodynamic cavitation treatment system for organic wastewater. The wastewater is first subjected to coagulation and sedimentation, and then the wastewater and Fenton reagent are simultaneously pumped into a rotary hydrodynamic cavitator, and finally passed into an ultrasonic cavitator for multi-stage degradation treatment. However, in this device, the Fenton reagent and the hydroxyl radicals generated by its decomposition are pumped separately from the stator sidewall of the rotary hydrodynamic cavitator. After entering the cavitation cavity, they are concentrated near the bottom and inner wall of the cavitation cavity due to the shear force and centrifugal force applied by the rotor, and convection cannot be generated inside the cavitator. This will cause uneven distribution of hydroxyl radical concentration in the cavitation cavity, affecting the degradation effect. If a sufficient concentration of hydroxyl radicals is to be ensured everywhere in the cavitation cavity to achieve efficient degradation, the amount of Fenton reagent added must be increased, which will introduce a large amount of iron ions into the wastewater, resulting in secondary pollution. Therefore, the practicality of this device is poor.

[0005] The invention patent "A Sewage Treatment Device" (publication number CN 112320882 B) discloses a wastewater treatment device. After passing through a perforated plate cavitation generator, the wastewater enters a discharge chamber, where plasma discharge is applied to the gas-liquid two-phase flow containing cavitation bubbles, thereby achieving wastewater degradation. However, this device does not take into account the heat dissipation problem of the plasma discharge device, and the electrodes are directly installed in a closed space. During the plasma discharge process, most of the energy is consumed in the form of heat, so heat energy easily accumulates at the electrodes and causes overheating. Due to the inherent instability of ozone molecules, they slowly and spontaneously decompose to produce oxygen at room temperature, and the rate of ozone self-decomposition doubles or even increases several times for every ten degrees Celsius increase in ambient temperature. If heat dissipation from the electrodes cannot be guaranteed, the ozone molecules will be inactivated before reacting with pollutant molecules, significantly reducing the degradation rate. In addition, at high temperatures, the rate of oxidation and corrosion of the electrodes themselves will increase, affecting the electrode's conductivity and even creating safety hazards.

[0006] In summary, the existing wastewater treatment device combining plasma discharge with hydrodynamic cavitation still has the following shortcomings:

[0007] 1. The integration level of the plasma discharge device and the hydrodynamic cavitation device is low. A separate plasma discharge device is required to generate ozone, and then the ozone gas is input into the hydrodynamic cavitation device, resulting in a low integration level of the degradation device.

[0008] 2. Low mass transfer intensity between ozone and wastewater. Ozone generated solely needs to be introduced into wastewater through aeration or bubbling. The diameter of the ozone bubbles cannot be controlled, and the surface area of ​​the bubbles is small. Furthermore, because ozone molecules are insoluble in water, the gas-liquid mass transfer coefficient is low. The low mass transfer intensity of ozone in water results in a low yield of hydroxyl radicals generated by hydrolysis, and the degradation effect needs to be further improved. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a system and method for hydrodynamic cavitation-coordinated plasma degradation of organic wastewater, providing a new technical solution for achieving efficient degradation of organic wastewater. The present invention integrates plasma discharge technology and hydrodynamic cavitation technology, designs a plasma rotary cavitation reactor, sets an aeration device to generate micron-sized bubbles in the organic wastewater, pumps the organic wastewater rich in microbubbles into the inlet at the bottom of the plasma rotary cavitation reactor through a water pump, and uses a medium to block plasma discharge to generate active substances such as ozone and hydroxyl radicals, which are combined with hydrodynamic cavitation technology to enhance the degradation of organic wastewater and improve the degradation effect of wastewater; a rotor with opposite tooth inclination angles is set to increase the area of ​​the negative pressure area, induce the internal fluid to circulate between the cavitation area and the discharge area, and improve the gas-liquid mass transfer efficiency; by setting a variable-diameter jet cavitation channel, the pressure drop value when the fluid flows through the channel is changed, thereby enhancing the cavitation effect.

[0010] The technical solution adopted in the present invention is as follows:

[0011] The present invention provides a hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater, comprising a liquid storage tank, an aeration device, and a plasma rotary cavitation reactor; the plasma rotary cavitation reactor comprises a reactor shell, the bottom of the reactor shell is provided with an organic wastewater inlet, and the top is provided with an organic wastewater outlet; the aeration device is connected to the organic wastewater inlet via a water pump; the liquid storage tank is connected to the aeration device via a water pump;

[0012] A plasma discharge chamber and a cavitation reaction chamber are provided inside the reactor shell, and the plasma discharge chamber and the cavitation reaction chamber are connected through a plurality of upper jet cavitation channels and a plurality of lower jet cavitation channels. A sector-shaped electrode is provided on the outer wall of the plasma discharge chamber, and the sector-shaped electrode is fixed in a slot on the outer wall of the plasma discharge chamber and is located in the electrode cooling channel. A rotor is provided in the cavitation reaction chamber, and the outer wall of the rotor is provided with an upper row of teeth and a lower row of teeth, with grooves provided between adjacent teeth. The plurality of upper jet cavitation channels are circumferentially distributed around the upper row of teeth, and the inner diameter of the upper jet cavitation channels gradually decreases from the inner wall of the plasma discharge chamber to the inner wall of the cavitation reaction chamber. The plurality of lower jet cavitation channels are circumferentially distributed around the lower row of teeth, and the inner diameter of the lower jet cavitation channels gradually increases from the inner wall of the plasma discharge chamber to the inner wall of the cavitation reaction chamber.

[0013] In one embodiment of the present invention, the plasma rotary cavitation reactor further comprises a rotor motor, which is fixed on a motor bracket, which is fixed on a reactor housing, and the output end of the rotor motor is connected to the rotor main shaft via a coupling; the rotor is provided with a through hole along the axial centerline, the rotor main shaft is passed through the through hole and is fixedly connected to the rotor; the wastewater stored in the liquid storage tank is passed through an aeration device to generate a gas-liquid two-phase solution with microbubbles, and the water pump transports the gas-liquid two-phase solution in the aeration device from the organic wastewater inlet to the cavitation reaction chamber, and the rotor motor drives the rotor to rotate via the coupling and the rotor main shaft; during the rotation of the rotor, a narrow flow channel is formed between the upper and lower rows of teeth and the inner wall of the cavitation reaction chamber, and the increase in fluid flow rate causes the pressure to decrease, and a wide flow channel is formed between the grooves between adjacent teeth and the inner wall of the cavitation reaction chamber, and the decrease in fluid flow rate causes the pressure to increase. The periodic alternation of the pressure of the above-mentioned fluid induces a cavitation effect between the rotor and the inner wall of the cavitation reaction chamber.

[0014] In one embodiment of the present invention, the rotor rotates counterclockwise from top to bottom, the upper row of teeth has a left-handed rotation direction, and the lower row of teeth has a right-handed rotation direction. When the upper row of teeth rotates, the tooth inclination angle thereof is the same as the rotation direction, thereby reducing the centrifugal force applied to the surrounding liquid. Moreover, the size of the upper row of teeth is smaller than that of the lower row of teeth, so that a low-pressure area is formed near the upper row of teeth of the rotor, causing liquid to be sucked from the plasma discharge chamber into the cavitation reaction chamber through the upper jet cavitation channel. When the lower row of teeth rotates, the tooth inclination angle thereof is opposite to the rotation direction, thereby flinging the liquid out in all directions, causing the liquid to be squeezed from the cavitation reaction chamber into the plasma discharge chamber through the lower jet cavitation channel. This induces a continuous circulation flow of the fluid between the cavitation region of the cavitation reaction chamber and the discharge region of the plasma discharge chamber, causing the organic wastewater to cavitate in the cavitation reaction chamber and fully contact with the active substances generated by the medium in the plasma discharge chamber that blocks the plasma discharge. Simultaneously, a strong cavitation effect is formed at the inner diameter contraction of the upper jet cavitation channel and the lower jet cavitation channel, thereby enhancing the cavitation process.

[0015] In one embodiment of the present invention, the electrode cooling channel forms two coaxial cylindrical hollow cavities as dielectric barriers, a sector-shaped electrode is disposed in each of the hollow cavities, and a plasma discharge cavity is disposed between the two hollow cavities.

[0016] In one embodiment of the present invention, the plasma discharge chamber is made of quartz glass or a material with a relative dielectric constant greater than .

[0017] In one embodiment of the present invention, the sector-shaped electrodes are distributed in a surrounding manner on the outer wall of the plasma discharge chamber. A layer of sector-shaped electrodes is installed on the side of the outer wall of the plasma discharge chamber close to the rotor as a positive electrode, and a layer of sector-shaped electrodes is installed on the side of the outer wall of the plasma discharge chamber away from the rotor as a negative electrode; the sector-shaped electrodes are connected to a high-voltage power supply through wires, and a dielectric barrier plasma discharge phenomenon is formed by applying a voltage between the two electrodes to generate active substances such as ozone and hydroxyl free radicals in water.

[0018] In one embodiment of the present invention, the reactor shell includes an upper shell and a lower shell connected to each other, the electrode cooling channel includes an electrode cooling channel inlet and an electrode cooling channel outlet, the electrode cooling channel inlet is arranged in the lower shell, and the electrode cooling channel outlet consists of a plurality of holes uniformly distributed in a circle on the top of the upper shell; the electrode cooling channel inlet is connected to the air pump, and the air pump cools the sector-shaped electrode from bottom to top through the electrode cooling channel.

[0019] In one embodiment of the present invention, the upper jet cavitation channel and the lower jet cavitation channel are configured as hyperbolic holes, and the edges are connected by arc transition to form smooth channels; the opening end of the upper jet cavitation channel with a larger inner diameter is opened on the inner wall of the plasma discharge chamber, and the opening end with a smaller inner diameter is opened on the inner wall of the cavitation reaction chamber; the opening end of the lower jet cavitation channel with a larger inner diameter is opened on the inner wall of the cavitation reaction chamber, and the opening end with a smaller inner diameter is opened on the inner wall of the ion discharge chamber; the axes of the upper jet cavitation channel and the lower jet cavitation channel are perpendicular to the inner wall of the cavitation reaction chamber.

[0020] In one embodiment of the present invention, when a gas-liquid two-phase flow is passed between the positive and negative electrodes, a plasma discharge phenomenon is generated after the voltage of the applied alternating current exceeds the breakdown voltage of the gas. The system adopts coaxial twin-cylinder dielectric barrier plasma discharge technology. The voltage U unit V is applied between the two electrodes. The voltage value is calculated according to formula (1):

[0021]

[0022] Among them, E g is the voltage intensity of the gas in the discharge gap, unit is V / mm, t is the total thickness of the two dielectric layers, unit is mm; l gl is the equivalent discharge gap when gas-liquid two-phase flow is passed between the two electrodes, unit: mm; ε g is the dielectric constant of the gas, ε d is the dielectric constant of the barrier medium; the equivalent discharge gap l when gas-liquid two-phase flow is passed between the two electrodes gl It is related to the volume fraction of bubbles in the liquid and is the cumulative diameter of the bubbles in the normal direction of the electrode. gl Calculate according to formula (2):

[0023] l gl =c·l d (2)

[0024] Where c is the volume fraction of the gas phase between the two electrodes, and the value of c is between 0 and 1. d is the distance between the two dielectric layers.

[0025] On the other hand, the present invention provides a method for degrading organic wastewater by using hydrodynamic cavitation and plasma, which uses the hydrodynamic cavitation and plasma system for degrading organic wastewater. The method comprises:

[0026] Step 1: Open the organic wastewater inlet and the organic wastewater outlet, start the water pump to pump the organic wastewater into the liquid storage tank at a certain flow rate to the aeration device. The organic wastewater generates microbubbles in the aeration device, and the gas-liquid mixed organic wastewater enters the organic wastewater inlet at a certain flow rate through the water pump;

[0027] Step 2: After the organic wastewater enters the plasma rotary cavitation reactor, the rotor motor is turned on. The rotor rotates to generate strong shear force and cavitation effect around the upper and lower rows of teeth, generating a large number of cavitation bubbles in the cavitation reaction chamber and releasing hydroxyl free radicals.

[0028] Step 3: The organic wastewater is squeezed from the cavitation reaction chamber into the plasma discharge chamber through the lower jet cavitation channel. The high-voltage power supply is adjusted to discharge the sector electrode, forming a dielectric barrier plasma discharge, generating ozone and hydroxyl free radicals in the water. During the discharge, the air pump is turned on to dissipate heat from the sector electrode.

[0029] Step 4: While discharging, the rotor rotates at high speed, and the organic wastewater is sucked from the plasma discharge chamber into the cavitation reaction chamber through the upper jet cavitation channel, inducing a continuous circulation flow between the cavitation area of ​​the cavitation reaction chamber and the discharge area of ​​the plasma discharge chamber. The degraded wastewater is discharged from the organic wastewater outlet by water pressure;

[0030] Step 5: Detect the pollutant removal rate of the liquid flowing out of the organic wastewater outlet and adjust the flow rate of the water pump in real time to achieve efficient degradation of the organic wastewater.

[0031] The beneficial effects of the present invention are:

[0032] (1) It integrates plasma discharge technology and hydrodynamic cavitation technology. The system uses dielectric barrier plasma discharge technology to generate low-temperature plasma rich in active substances such as ozone, free radicals, electrons, and excited molecules in organic wastewater. Combined with the local high temperature, high pressure and mechanical shock waves generated when the cavitation bubbles collapse, the ozone molecules and active substances with long life and poor solubility in water fully react with the organic wastewater, rapidly improving the utilization rate of active substances. This synergistic effect not only makes the organic matter decompose more thoroughly, but also effectively reduces the degradation time and energy consumption.

[0033] (2) The rotor tooth inclination angle was optimized and the upper and lower teeth were set with opposite inclination angles. The upper and lower rows of teeth with opposite inclination angles were designed on the rotor to enhance the shear force of the wastewater in the cavitation area and intensify the formation and bursting of bubbles. The opposite tooth inclination angles improved the flow pattern of the wastewater, accelerated the circulation of the wastewater between the cavitation area and the discharge area, strengthened the cavitation process and ionization effect of the organic wastewater, and further improved the gas-liquid mass transfer efficiency and degradation effect.

[0034] (3) An upper jet cavitation channel and a lower jet cavitation channel were designed. An upper jet cavitation channel with an inner radial contraction of the inner wall of the cavitation reaction chamber was set up, and a lower jet cavitation channel with an inner radial contraction of the inner wall of the plasma discharge chamber was set up. The pressure difference on both sides of the upper jet cavitation channel caused the liquid in the discharge area to be sucked into the cavitation area, and the pressure difference on both sides of the lower jet cavitation channel squeezed the liquid in the cavitation area into the discharge area. The organic wastewater cavitated in the cavitation reaction chamber and was able to fully contact with the active substances generated by the plasma discharge in the medium blocking the plasma discharge in the plasma discharge chamber, thereby improving the degradation effect. When the fluid passes through the jet cavitation channel, the cross-sectional area gradually decreases, the flow velocity of the fluid increases significantly, the cavitation phenomenon is significantly enhanced, the flow field structure is optimized, and the degradation of the organic wastewater is more thorough.

[0035] (4) Constructed an electrode heat dissipation path. An electrode cooling channel was set up to achieve continuous heat dissipation of the electrode, ensuring efficient system operation while avoiding performance degradation or oxidation corrosion caused by electrode overheating. This design extends the service life of the equipment and improves the stability and reliability of the system.

[0036] (5) Adjustable dielectric barrier plasma discharge voltage. The minimum voltage required for coaxial twin-cylinder dielectric barrier plasma discharge is calculated, and the applied voltage is adjusted according to the actual situation, avoiding unstable or discontinuous discharge caused by too low voltage and increased system energy consumption caused by too high voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 A schematic diagram of the structure of a hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater provided by an embodiment of the present invention.

[0039] Figure 2 A cross-sectional view of a plasma rotary cavitation reactor provided in an embodiment of the present invention.

[0040] Figure 3 This is a schematic structural diagram of the upper shell provided by an embodiment of the present invention.

[0041] Figure 4 This is a schematic structural diagram of the lower shell provided by an embodiment of the present invention.

[0042] Figure 5 A schematic structural diagram of a rotor provided in an embodiment of the present invention.

[0043] Figure 6 A diagram of convection within a plasma rotary cavitation reactor provided by an embodiment of the present invention.

[0044] Figure 7 A flow chart of a method for degrading organic wastewater by hydrodynamic cavitation and plasma provided in an embodiment of the present invention.

[0045] The parts in the figure are marked as follows: 1. Liquid storage tank; 2. Water pump; 3. Aeration device; 4. Plasma rotary cavitation reactor; 41. Rotor motor; 411. Rotor main shaft; 42. Motor bracket; 43. Reactor shell; 431. Plasma discharge chamber; 432. Fan-shaped electrode; 433. Cavitation reaction chamber; 434. Upper shell; 435. Lower shell; 436. Slot; 44. Rotor; 441. Upper row of teeth; 442. Lower row of teeth; 443. Through hole; 444. Groove; 45. Upper jet cavitation channel; 46. Lower jet cavitation channel; 47. Electrode cooling channel; 48. Organic wastewater inlet; 49. Organic wastewater outlet; 5. Air pump; 6. High-voltage power supply. DETAILED DESCRIPTION

[0046] The present invention is described in detail below. In the following paragraphs, various aspects of the embodiments are defined in more detail. Each aspect defined in this manner may be combined with any other aspect or aspects unless expressly stated not to be combinable. In particular, any feature considered to be preferred or advantageous may be combined with one or more other features considered to be preferred or advantageous.

[0047] The terms "first" and "second" appearing in the present invention are only for the convenience of description to distinguish different components with the same name, and do not indicate a priority or primary and secondary relationship.

[0048] In addition, when an element is referred to as being “on” another element, the element may be directly on the other element or may be indirectly on the other element with one or more intervening elements interposed therebetween. In addition, when an element is referred to as being “connected to” another element, the element may be directly connected to the other element or may be indirectly connected to the other element with one or more intervening elements interposed therebetween. Hereinafter, the same reference numerals denote the same elements.

[0049] The present invention uses the terms “upper”, “lower”, “top”, “bottom”, “front”, “back”, “inside” and “outside” to indicate directions or positional relationships. This is only for the convenience of describing the present invention, and does not indicate or imply that the device referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, it should not be understood as limiting the scope of protection of the present invention.

[0050] like Figure 1 As shown, the present invention provides a hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater. In some embodiments, the system includes a liquid storage tank 1, a water pump 2, an aeration device 3, a plasma rotary cavitation reactor 4, an air pump 5, and a high-voltage power supply 6. The air pump 5 and the high-voltage power supply 6 are connected to the plasma rotary cavitation reactor 4. The liquid storage tank 1 is connected to the aeration device 3 via the water pump 2; the other end of the aeration device 3 is connected to the plasma rotary cavitation reactor 4 via the water pump 2; the wastewater in the liquid storage tank 1 is generated into a gas-liquid two-phase solution with microbubbles by the aeration device 3, and the water pump 2 pumps the gas-liquid two-phase solution in the aeration device 3 into the plasma rotary cavitation reactor 4; the plasma rotary cavitation reactor 4 ionizes and cavitates the gas-liquid two-phase solution.

[0051] like Figure 2 As shown, in some embodiments, the plasma rotary cavitation reactor 4 includes a rotor motor 41, a motor bracket 42, a reactor housing 43, a rotor 44, an upper jet cavitation channel 45, a lower jet cavitation channel 46, an electrode cooling channel 47, an organic wastewater inlet 48, and an organic wastewater outlet 49. The organic wastewater inlet 48 is located at the bottom of the reactor housing 43, and the organic wastewater outlet 49 is located at the top of the reactor housing 43. After the plasma rotary cavitation reactor 4 is filled with solution, the degraded organic wastewater overflows from the organic wastewater outlet 49 at the top of the reactor housing 43 due to water pressure. The rotor motor 41 is fixed to the motor bracket 42 by bolts, and the motor bracket 42 is also fixed to the reactor housing 43 by bolts. The output end of the rotor motor 41 is connected to the rotor main shaft 411 through a coupling. The reactor housing 43 provides support and fixation for the internal components of the entire plasma rotary cavitation reactor 4. The reactor housing 43 is provided with a plasma discharge chamber 431, a sector electrode 432, and a cavitation reaction chamber 433.

[0052] like Figure 2 and Figure 5As shown, in some embodiments, a rotor 44 is provided in the cavitation reaction chamber 433, and a through hole 443 is provided in the center of the rotor 44, and an upper row of teeth 441 and a lower row of teeth 442 are provided on the outer wall, and a groove 444 is provided between adjacent teeth. The rotation direction of the upper row of teeth 441 is left-handed, and the rotation direction of the lower row of teeth 442 is right-handed; the rotor main shaft 411 is passed through the through hole 443, and the end of the rotor main shaft 411 is fixedly connected to the rotor 44 by a bolt, and the rotor motor 41 drives the rotor 44 to rotate through the coupling and the rotor main shaft 411.

[0053] Preferably, the rotation speed of the rotor 44 is set to 2000r / min, the tooth inclination angle of the upper row of teeth 441 and the lower row of teeth 442 is 45°, the diameter of the main body of the upper row of teeth 441 is 64mm, the depth of the groove 444 is 8mm, the diameter of the main body of the lower row of teeth 442 is 80mm, the depth of the groove 444 is 10mm, and the width of the groove 444 is 3.1mm.

[0054] like Figure 2 and Figure 3 As shown, in some embodiments, there are a plurality of upper jet cavitation channels 45 and a plurality of lower jet cavitation channels 46 on the inner wall of the cavitation reaction chamber 433, and the plurality of upper jet cavitation channels 45 are circumferentially distributed around the upper row of teeth 441, and the inner diameter of the upper jet cavitation channel 45 gradually decreases from the inner wall of the plasma discharge chamber 431 to the inner wall of the cavitation reaction chamber 433; the plurality of lower jet cavitation channels 46 are circumferentially distributed around the lower row of teeth 441, and the inner diameter of the lower jet cavitation channel 46 gradually increases from the inner wall of the plasma discharge chamber 431 to the inner wall of the cavitation reaction chamber 433; the upper jet cavitation channels 45 and the lower jet cavitation channels 46 are set as hyperbolic holes, and the edges are connected by arc transition to form smooth channels.

[0055] The pressure differential created by the velocity difference between the upper and lower jet cavitation channels 45 and 46 induces a continuous circulation of fluid between the cavitation region of the cavitation reaction chamber 433 and the discharge region of the plasma discharge chamber 431. This allows the organic wastewater to cavitate in the cavitation reaction chamber 433 and fully contact the active substances generated by the dielectric barrier plasma discharge in the plasma discharge chamber 431, thereby enhancing the degradation effect. As the fluid passes through the jet cavitation channel, the cross-sectional area gradually decreases, significantly increasing the flow velocity and intensifying the cavitation phenomenon. This optimizes the flow field structure and enables more thorough degradation of the organic wastewater.

[0056] Preferably, in this embodiment, the number of the upper jet cavitation channels 45 and the lower jet cavitation channels 46 can be four, which is not specifically limited.

[0057] Furthermore, the opening end of the upper jet cavitation channel 45 with a larger inner diameter is opened on the inner wall of the plasma discharge chamber 431, and the opening end with a smaller inner diameter is opened on the inner wall of the cavitation reaction chamber 433; the opening end of the lower jet cavitation channel 46 with a larger inner diameter is opened on the inner wall of the cavitation reaction chamber 433, and the opening end with a smaller inner diameter is opened on the inner wall of the ion discharge chamber 431; the axes of the upper jet cavitation channel 45 and the lower jet cavitation channel 46 are perpendicular to the inner wall of the cavitation reaction chamber 433.

[0058] like Figure 2 、 Figure 3 and Figure 4 As shown, in some embodiments, the reactor shell 43 is composed of an upper shell 434 and a lower shell 435 connected by bolts; a plasma discharge chamber 431, a sector electrode 432 and a cavitation reaction chamber 433 are provided inside the upper shell 434; a machine waste water inlet 48 connected to the cavitation reaction chamber 433 is provided inside the lower shell 435; an electrode cooling channel 47 is provided inside the reactor shell 43, and the electrode cooling channel 47 includes an electrode cooling channel inlet 471 and an electrode cooling channel outlet 472, the electrode cooling channel inlet 471 is provided in the lower shell 435, and the electrode cooling channel outlet 472 has several holes uniformly distributed in a circle on the top of the upper shell 434; the air pump 5 is connected to the electrode cooling channel inlet 471 to continuously cool the sector electrode 432 from bottom to top. Figure 1 、 Figure 2 and Figure 5 As shown, organic wastewater with microbubbles enters from the organic wastewater inlet 48 and passes through the cavitation reaction chamber 433. During the rotation of the rotor 44, a narrow flow channel is formed between the upper row of teeth 441 and the lower row of teeth 442 and the inner wall of the cavitation reaction chamber 433. The increase in fluid flow rate causes the pressure to decrease, and a wide flow channel is formed between the grooves 444 between adjacent teeth and the inner wall of the cavitation reaction chamber 433. The decrease in fluid flow rate causes the pressure to increase. The periodic alternation of the pressure of the above-mentioned fluid can induce a cavitation effect between the rotor 44 and the inner wall of the cavitation reaction chamber 433.

[0059] Furthermore, the sector-shaped electrode 432 is provided with two rows of holes with different inner diameters. The upper row of holes provides support for the upper jet cavitation channel 45 , and the lower row of holes provides support for the lower jet cavitation channel 46 , and the sector-shaped electrode 432 is sealedly connected to the upper jet cavitation channel 45 and the lower jet cavitation channel 46 .

[0060] like Figure 6As shown, when the upper row of teeth 441 rotates, its tooth inclination angle is the same as the rotation direction, reducing the centrifugal force applied to the surrounding liquid, and the size of the upper row of teeth 441 is smaller than that of the lower row of teeth 442, so that the rotor 44 forms a low-pressure area near the upper row of teeth 441, causing the liquid to be sucked from the plasma discharge chamber 431 through the upper jet cavitation channel 45 to the cavitation reaction chamber 433; when the lower row of teeth 442 rotates, its tooth inclination angle is opposite to the rotation direction, throwing the liquid to the surroundings, causing the liquid to be discharged from the cavitation reaction chamber 433. The wastewater is squeezed into the plasma discharge chamber 431 through the lower jet cavitation channel 46; this triggers a continuous circulation flow of the fluid between the cavitation area of ​​the cavitation reaction chamber 433 and the discharge area of ​​the plasma discharge chamber 431, so that the organic wastewater is cavitated in the cavitation reaction chamber 433 and can fully contact with the active substances generated by the dielectric barrier plasma discharge in the plasma discharge chamber 431; at the same time, the fluid forms a strong cavitation effect at the inner diameter contraction of the upper jet cavitation channel 45 and the lower jet cavitation channel 46, thereby strengthening the cavitation process.

[0061] In the cavitation reaction chamber 433, the high-speed flow and cavitation bubbles generated by the rotation of the rotor 44 cause extremely high temperature and pressure to be generated in the liquid. The cavitation bubbles enter the plasma discharge chamber 431, and the dielectric barrier discharge produces active substances with strong oxidizing ability. Combined with the shock wave generated by the collapse of the cavitation bubbles, the organic matter is decomposed more thoroughly, greatly improving the degradation efficiency.

[0062] Furthermore, the electrode cooling channel 47 forms two coaxial cylindrical hollow cavities as a dielectric barrier layer, each cylindrical hollow cavity is provided with a fan-shaped electrode 432, and the middle layer between the two cylindrical hollow cavities forms a plasma discharge chamber 431 with a width, inner diameter and length of 5 mm, 16 mm and 80 mm respectively.

[0063] The sector-shaped electrodes 432 are fixed to the outer wall of the plasma discharge chamber 431 and arranged in a surrounding pattern. A layer of sector-shaped electrodes 432 is mounted on the side of the outer wall of the plasma discharge chamber 431 close to the rotor 44, serving as the positive electrode, and a layer of sector-shaped electrodes 432 is mounted on the side of the outer wall of the plasma discharge chamber 431 away from the rotor 44, serving as the negative electrode. Specifically, the sector-shaped electrodes 432 are fixed in slots 436 on the outer wall of the plasma discharge chamber 431. The sector-shaped electrodes 432 are connected to the high-voltage power supply 6 via wires. By applying a sufficiently high voltage between the two electrodes, a dielectric barrier plasma discharge phenomenon is generated, thereby generating active substances such as ozone and hydroxyl radicals in the water. Preferably, the material of the plasma discharge chamber 431 is quartz glass or a material with a relative dielectric constant greater than 3.8, and the wall thickness of the plasma discharge chamber 431 is 2 mm.

[0064] When a gas-liquid two-phase flow is passed between the positive and negative electrodes, a plasma discharge phenomenon occurs when the voltage of the applied alternating current exceeds the breakdown voltage of the gas. The system adopts coaxial double-cylinder dielectric barrier plasma discharge technology. The voltage U applied between the two electrodes, in V, is calculated according to formula (1):

[0065]

[0066] Among them, E g is the voltage intensity of the gas in the discharge gap, unit is V / mm, t is the total thickness of the two dielectric layers, unit is mm; l gl is the equivalent discharge gap when gas-liquid two-phase flow is passed between the two electrodes, unit: mm; ε g is the dielectric constant of the gas, ε d is the dielectric constant of the barrier medium; the equivalent discharge gap l when gas-liquid two-phase flow is passed between the two electrodes gl It is related to the volume fraction of bubbles in the liquid and is the cumulative diameter of the bubbles in the normal direction of the electrode. gl Calculate according to formula (2):

[0067] l gl =c·l d (2)

[0068] Where c is the volume fraction of the gas phase between the two electrodes. The value of c is between 0 and 1 and needs to be determined experimentally. d is the distance between the two dielectric layers. At this point, the total thickness of the two dielectric layers is 4mm. When gas-liquid two-phase flow is passed between the two electrodes, the equivalent discharge gap is 4mm. The dielectric constant of the gas is 1, and the dielectric constant of quartz glass is 3.7. According to Paschen's law, the breakdown voltage of the gas under normal circumstances is 3000V / mm. The calculated minimum voltage required at this time is 15200V. Therefore, a design with a power supply output of 15200V can achieve the minimum voltage for plasma discharge. When degrading organic wastewater, too low a voltage may lead to unstable or discontinuous discharge, while too high a voltage may lead to excessive discharge, increasing the system's energy consumption and electrode wear.

[0069] In addition, if Figure 7 As shown, the present invention also provides a method for degrading organic wastewater by hydrodynamic cavitation and plasma, which uses the above-mentioned hydrodynamic cavitation and plasma system for degrading organic wastewater, including the following steps:

[0070] Step 1: Open the organic wastewater inlet 48 and the organic wastewater outlet 49, start the water pump 2 to pump the organic wastewater into the liquid storage tank 1 at a certain flow rate to the aeration device 3. The organic wastewater generates microbubbles in the aeration device 3, and the organic wastewater in a gas-liquid mixed state enters the organic wastewater inlet 48 at a certain flow rate through the water pump 2;

[0071] Step 2: After the organic wastewater enters the plasma rotary cavitation reactor 4, the rotor motor 41 is turned on, and the rotor 44 rotates to generate strong shear force and cavitation effect around the upper row of teeth 441 and the lower row of teeth 442, generating a large number of cavitation bubbles in the cavitation reaction chamber 433 and releasing hydroxyl radicals;

[0072] Step 3: The organic wastewater is squeezed from the cavitation reaction chamber 433 into the plasma discharge chamber 431 through the lower jet cavitation channel 46. The high-voltage power supply 6 is adjusted to discharge the sector electrode 432, forming a dielectric barrier plasma discharge, generating ozone and hydroxyl radicals in the water. During the discharge, the air pump 5 is turned on to dissipate heat from the sector electrode 432.

[0073] Step 4: While discharging, the rotor 44 rotates at high speed, and the organic wastewater is sucked from the plasma discharge chamber 431 into the cavitation reaction chamber 433 through the upper jet cavitation channel 45, inducing a continuous circulation flow between the cavitation area of ​​the cavitation reaction chamber 433 and the discharge area of ​​the plasma discharge chamber 431. The degraded wastewater is discharged from the organic wastewater outlet 49 by water pressure.

[0074] Step 5: Detect the pollutant removal rate of the liquid flowing out of the organic wastewater outlet 49 and adjust the flow rate of the water pump 2 in real time to achieve efficient degradation of the organic wastewater.

[0075] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A hydrodynamic cavitation synergistic plasma degradation system for organic wastewater, characterized in that: The invention comprises a liquid storage tank (1), an aeration device (3) and a plasma rotary cavitation reactor (4); the plasma rotary cavitation reactor (4) comprises a reactor shell (43); the bottom of the reactor shell (43) is provided with an organic wastewater inlet (48), and the top is provided with an organic wastewater outlet (49); the aeration device (3) is connected to the organic wastewater inlet (48) through a water pump (2); the liquid storage tank (1) is connected to the aeration device (3) through the water pump (2); A plasma discharge chamber (431) and a cavitation reaction chamber (433) are provided inside the reactor shell (43), and the plasma discharge chamber (431) and the cavitation reaction chamber (433) are communicated with each other through a plurality of upper jet cavitation channels (45) and a plurality of lower jet cavitation channels (46); a sector-shaped electrode (432) is provided on the outer wall of the plasma discharge chamber (431), and the sector-shaped electrode (432) is fixed in a slot (436) on the outer wall of the plasma discharge chamber (431) and is located in the electrode cooling channel (47); a rotor (44 ), the outer wall of the rotor (44) is provided with an upper row of teeth (441) and a lower row of teeth (442), and a groove (444) is provided between adjacent teeth; a plurality of the upper jet cavitation channels (45) are circumferentially distributed around the upper row of teeth (441), and the inner diameter of the upper jet cavitation channel (45) gradually decreases from the inner wall of the plasma discharge chamber (431) to the inner wall of the cavitation reaction chamber (433); a plurality of the lower jet cavitation channels (46) are circumferentially distributed around the lower row of teeth (442), and the inner diameter of the lower jet cavitation channel (46) gradually increases from the inner wall of the plasma discharge chamber (431) to the inner wall of the cavitation reaction chamber (433); The rotation direction of the rotor (44) is counterclockwise from top to bottom, the rotation direction of the upper row of teeth (441) is left-handed, and the rotation direction of the lower row of teeth (442) is right-handed; when the upper row of teeth (441) rotates, its tooth inclination angle is the same as the rotation direction, reducing the centrifugal force applied to the surrounding liquid, and the size of the upper row of teeth (441) is smaller than that of the lower row of teeth (442), so that the rotor (44) forms a low-pressure area near the upper row of teeth (441), causing the liquid to be sucked from the plasma discharge chamber (431) to the cavitation reaction chamber (433) through the upper jet cavitation channel (45); when the lower row of teeth (442 .... The direction is opposite, and the liquid is thrown out to the surroundings, causing the liquid to be squeezed from the cavitation reaction chamber (433) through the lower jet cavitation channel (46) to the plasma discharge chamber (431); the fluid is triggered to form a continuous circulation flow between the cavitation area of ​​the cavitation reaction chamber (433) and the discharge area of ​​the plasma discharge chamber (431), so that the organic wastewater is cavitated in the cavitation reaction chamber (433) and can fully contact with the active substances generated by the medium blocking plasma discharge in the plasma discharge chamber (431); at the same time, the fluid forms a strong cavitation effect at the inner diameter contraction of the upper jet cavitation channel (45) and the lower jet cavitation channel (46), thereby strengthening the cavitation process; The electrode cooling channel (47) forms two coaxial cylindrical hollow cavities as a dielectric barrier layer, a sector-shaped electrode (432) is provided in each of the hollow cavities, and a plasma discharge cavity (431) is provided between the two hollow cavities; The fan-shaped electrodes (432) are distributed in a surrounding manner on the outer wall of the plasma discharge chamber (431); a layer of fan-shaped electrodes (432) is installed on the side of the outer wall of the plasma discharge chamber (431) close to the rotor (44) as a positive electrode, and a layer of fan-shaped electrodes (432) is installed on the side of the outer wall of the plasma discharge chamber (431) away from the rotor (44) as a negative electrode; the fan-shaped electrodes (432) are connected to a high-voltage power supply (6) through a wire, and a dielectric barrier plasma discharge phenomenon is formed by applying a voltage between the two electrodes to generate active substances such as ozone and hydroxyl free radicals in water.

2. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 1, characterized in that: The plasma rotary cavitation reactor (4) further comprises a rotor motor (41), wherein the rotor motor (41) is fixed on a motor bracket (42), wherein the motor bracket (42) is fixed on a reactor housing (43), and an output end of the rotor motor (41) is connected to a rotor main shaft (411) via a coupling; the rotor (44) is provided with a through hole (443) along an axial center line, and the rotor main shaft (411) is passed through the through hole (443) and is fixedly connected to the rotor (44); the wastewater stored in the liquid storage tank (1) is generated into a gas-liquid two-phase solution with microbubbles through the aeration device (3), and the water pump (2) pumps the gas in the aeration device (3) into the gas-liquid two-phase solution. The liquid two-phase solution is transported from the organic wastewater inlet (48) to the cavitation reaction chamber (433), and the rotor motor (41) drives the rotor (44) to rotate through the coupling and the rotor main shaft (411); during the rotation of the rotor (44), a narrow flow channel is formed between the upper row of teeth (441) and the lower row of teeth (442) and the inner wall of the cavitation reaction chamber (433), and the pressure decreases as the fluid flow rate increases. A wide flow channel is formed between the grooves (444) between adjacent teeth and the inner wall of the cavitation reaction chamber (433), and the pressure increases as the fluid flow rate decreases. The periodic alternation of the pressure of the above-mentioned fluid induces a cavitation effect between the rotor (44) and the inner wall of the cavitation reaction chamber (433).

3. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 1, characterized in that: The material of the plasma discharge chamber (431) is quartz glass or a material with a relative dielectric constant greater than 3.

8.

4. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 1, characterized in that: The reactor shell (43) includes an upper shell (434) and a lower shell (435) connected to each other. The electrode cooling channel (47) includes an electrode cooling channel inlet (471) and an electrode cooling channel outlet (472). The electrode cooling channel inlet (471) is arranged on the lower shell (435), and the electrode cooling channel outlet (472) consists of a plurality of holes uniformly distributed in a circumferential manner on the top of the upper shell (434). The electrode cooling channel inlet (471) is connected to an air pump (5), and the air pump (5) cools the sector-shaped electrode (432) from bottom to top through the electrode cooling channel (47).

5. The hydrodynamic cavitation synergistic plasma degradation organic wastewater system according to claim 1, characterized in that: The upper jet cavitation channel (45) and the lower jet cavitation channel (46) are configured as hyperbolic holes, with their edges connected by arc transitions to form smooth channels; the opening end of the upper jet cavitation channel (45) with a larger inner diameter is opened on the inner wall of the plasma discharge chamber (431), and the opening end of the lower jet cavitation channel (46) with a smaller inner diameter is opened on the inner wall of the cavitation reaction chamber (433); the opening end of the lower jet cavitation channel (46) with a larger inner diameter is opened on the inner wall of the cavitation reaction chamber (433), and the opening end of the lower jet cavitation channel (46) with a smaller inner diameter is opened on the inner wall of the ion discharge chamber (431); the axes of the upper jet cavitation channel (45) and the lower jet cavitation channel (46) are perpendicular to the inner wall of the cavitation reaction chamber (433).

6. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 1, characterized in that: When gas-liquid two-phase flow is passed between the positive and negative electrodes, the voltage of the applied alternating current exceeds the breakdown voltage of the gas, generating plasma discharge. The system uses coaxial twin-cylinder dielectric barrier plasma discharge technology, and the voltage applied between the two electrodes is , unit V, the voltage value is calculated according to formula (1): （1） in, is the voltage intensity of the gas in the discharge gap, unit is V / mm, is the total thickness of the two dielectric layers, in mm; The equivalent discharge gap when gas-liquid two-phase flow is passed between the two electrodes, unit: mm; is the dielectric constant of the gas, is the dielectric constant of the barrier medium; the equivalent discharge gap when gas-liquid two-phase flow is passed between the two electrodes , is the cumulative diameter of the bubble in the normal direction of the electrode, Calculate according to formula (2): （2） in, c is the volume fraction of the gas phase between the two electrodes, c The value of is between 0 and 1, is the distance between the two dielectric layers.

7. A method for degrading organic wastewater by hydrodynamic cavitation and plasma, characterized in that: The hydrodynamic cavitation synergistic plasma degradation system for organic wastewater according to any one of claims 1 to 6 is used, and the method comprises: Step 1: Open the organic wastewater inlet (48) and the organic wastewater outlet (49), start the water pump (2) to pump the organic wastewater into the liquid storage tank (1) at a certain flow rate to the aeration device (3), the organic wastewater generates microbubbles in the aeration device (3), and the organic wastewater in a gas-liquid mixed state enters the organic wastewater inlet (48) at a certain flow rate through the water pump (2); Step 2: After the organic wastewater enters the plasma rotary cavitation reactor (4), the rotor motor (41) is turned on, and the rotor (44) rotates to induce strong shear force and cavitation effect around the upper row of teeth (441) and the lower row of teeth (442), generating a large number of cavitation bubbles in the cavitation reaction chamber (433) and releasing hydroxyl radicals; Step 3: The organic wastewater is squeezed from the cavitation reaction chamber (433) into the plasma discharge chamber (431) through the lower jet cavitation channel (46), and the high-voltage power supply (6) is adjusted to discharge the sector electrode (432), forming a dielectric barrier plasma discharge, generating ozone and hydroxyl radicals in the water; while discharging, the air pump (5) is turned on to dissipate heat from the sector electrode (432); Step 4: while discharging, the rotor (44) rotates at a high speed, and the organic wastewater is sucked from the plasma discharge chamber (431) into the cavitation reaction chamber (433) through the upper jet cavitation channel (45), causing the fluid to form a continuous circulation flow between the cavitation area of ​​the cavitation reaction chamber (433) and the discharge area of ​​the plasma discharge chamber (431), and the degraded wastewater is discharged from the organic wastewater outlet (49) by water pressure; Step 5: Detect the pollutant removal rate of the liquid flowing out of the organic wastewater outlet (49) and adjust the flow rate of the water pump (2) in real time to achieve efficient degradation of the organic wastewater.

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