System and method for degrading organic wastewater through cooperation of hydrodynamic cavitation and plasma

Abstract

The invention discloses a system and a method for degrading organic wastewater through cooperation of hydrodynamic cavitation and plasma. The system comprises a liquid storage tank, an aeration device and a plasma rotary cavitation reactor, the plasma rotary cavitation reactor comprises a reactor shell, and the reactor shell is provided with an organic wastewater inlet and an organic wastewater outlet; the aeration device is communicated with the organic wastewater inlet; and the liquid storage tank is communicated with the aeration device. The plasma discharge technology and the hydrodynamic cavitation technology are fused, active substances such as ozone and hydroxyl radicals are generated through dielectric barrier plasma discharge, degradation of organic wastewater is enhanced in cooperation with the hydrodynamic cavitation technology, and the degradation effect of the wastewater is improved; an upper row of teeth and a lower row of teeth with opposite tooth inclination angles are arranged on the rotor, so that fluid is triggered to circularly flow between a cavitation area and a discharge area, and the gas-liquid mass transfer efficiency is further improved; by arranging the upper jet flow cavitation channel and the lower jet flow cavitation channel which are variable in inner diameter and opposite in direction, the pressure drop value when fluid flows through the channels is changed, and the cavitation effect is enhanced.

Description

Technical Field

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

[0002] Since organic wastewater contains a large amount of organic matter that is difficult to degrade, 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 type of 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 intensity of gas-liquid mass transfer 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 hydraulic cavitation" (Announcement No. CN117247083B) discloses a system and method for degrading oily wastewater by miniaturized plasma combined with hydraulic cavitation. Its working principle is to use the vortex effect to cause cavitation of the oily wastewater in the local negative pressure area in 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 hydraulic cavitation technology, the active substances such as hydroxyl radicals, high-energy electrons, and excited state molecules generated during plasma discharge have only a life cycle of microseconds or milliseconds, and 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 limited degradation effect.

[0004] The invention patent "A three-stage hydraulic cavitation treatment system for organic wastewater" (Announcement No. CN 109824173 B) discloses a three-stage hydraulic cavitation treatment system for organic wastewater, which firstly performs coagulation and sedimentation on the wastewater, then simultaneously pumps the wastewater and Fenton's reagent into a rotary hydraulic cavitator, and finally passes into an ultrasonic cavitator for multi-stage degradation treatment. However, in the device, the Fenton's reagent and the hydroxyl radicals generated by its decomposition are pumped separately from the stator side wall of the rotary hydraulic cavitator. After entering the cavitation cavity, they will be 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, which will cause uneven distribution of hydroxyl radical concentration in the cavitation cavity, affecting the degradation effect. If it is to be ensured that there is a sufficient concentration of hydroxyl radicals everywhere in the cavitation cavity to achieve efficient degradation, the amount of Fenton's reagent added must be increased, which will introduce a large amount of iron ions into the wastewater, thereby causing secondary pollution. Therefore, the practicability of the device is poor.

[0005] The invention patent "A Sewage Treatment Device" (Announcement No. CN 112320882 B) discloses a wastewater treatment device. After the wastewater flows through the orifice plate cavitation generator, it enters the discharge chamber and performs plasma discharge on the gas-liquid two-phase flow containing cavitation bubbles to achieve wastewater degradation. However, the 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 energy, so it is easy to generate heat energy accumulation at the electrode and cause overheating. Since the ozone molecules themselves are not stable in nature, they will slowly decompose and generate oxygen at room temperature, and the ozone self-decomposition rate will double or several times for every ten degrees Celsius increase in ambient temperature. If the heat dissipation of the electrode cannot be guaranteed, the ozone molecules will be inactivated before reacting with the pollutant molecules, which significantly reduces the degradation rate. In addition, the rate at which the electrode itself is oxidized and corroded will also increase at high temperatures, affecting the conductivity of the electrode and even causing 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 degree of plasma discharge device and 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 degree of the degradation device.

[0008] 2. The mass transfer intensity between ozone and wastewater is low. Ozone generated alone needs to enter the wastewater through aeration or bubbling. The diameter of the ozone bubbles cannot be controlled and the specific surface area of ​​the bubbles is small. In addition, because the ozone molecules themselves are difficult to dissolve in water, the gas-liquid mass transfer coefficient is low. The mass transfer intensity of ozone in water is low, resulting in a low yield of hydroxyl radicals generated by hydrolysis, and the degradation effect needs to be further improved. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a system and method for hydrodynamic cavitation-coordinated plasma degradation of organic wastewater, which provides 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-level bubbles in organic wastewater, pumps 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, cooperates with hydrodynamic cavitation technology to strengthen the degradation of organic wastewater, and improves the degradation effect of wastewater; a rotor with opposite tooth inclination angles is set to increase the area of ​​the negative pressure area, causing the internal fluid to circulate between the cavitation area and the discharge area, and improves 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, and the cavitation effect is strengthened.

[0010] The technical solution adopted by 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 through a water pump; the liquid storage tank is connected to the aeration device through a water pump;

[0012] A plasma discharge chamber and a cavitation reaction chamber are arranged 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 electrode is arranged on the outer wall of the plasma discharge chamber, and the sector electrode is fixed in a slot on the outer wall of the plasma discharge chamber and is located in an electrode cooling channel; a rotor is arranged in the cavitation reaction chamber, and an upper row of teeth and a lower row of teeth are arranged on the outer wall of the rotor, and a groove is arranged between adjacent teeth; a plurality of the 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; a plurality of the 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, the rotor motor is fixed on a motor bracket, the motor bracket is fixed on a reactor shell, the output end of the rotor motor is connected to the rotor main shaft through a coupling; the rotor is provided with a through hole along the axial center line, the rotor main shaft is penetrated in 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, 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 through the coupling and the rotor main shaft; during the rotation of the rotor, a narrow flow channel is formed between the upper row of teeth and the lower row of teeth and the inner wall of the cavitation reaction chamber, the increase in fluid flow rate leads to a decrease in pressure, a wide flow channel is formed between the grooves between adjacent teeth and the inner wall of the cavitation reaction chamber, the decrease in fluid flow rate leads to an increase in pressure, and 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 rotation direction of the rotor is counterclockwise from top to bottom, the rotation direction of the upper row of teeth is left-handed, and the rotation direction of the lower row of teeth is right-handed; when the upper row of teeth rotates, the tooth inclination angle thereof 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 is smaller than that of the lower row of teeth, so that the rotor forms a low-pressure area near the upper row of teeth, causing the liquid to be sucked from the plasma discharge chamber to 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, throwing the liquid to the surroundings, causing the liquid to be squeezed from the cavitation reaction chamber to the plasma discharge chamber through the lower jet cavitation channel; inducing the fluid to form a continuous circulation flow between the cavitation area of ​​the cavitation reaction chamber and the discharge area of ​​the plasma discharge chamber, so that the organic wastewater is cavitated in the cavitation reaction chamber and can fully contact with the active substances generated by the medium blocking plasma discharge in the plasma discharge chamber; at the same time, the fluid forms a strong cavitation effect at the inner diameter contraction of the upper jet cavitation channel and the lower jet cavitation channel to strengthen the cavitation process.

[0015] In one embodiment of the present invention, the electrode cooling channel forms two coaxial cylindrical hollow cavities as a dielectric barrier layer, 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 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 is composed 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 a smooth channel; 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 a coaxial double-cylinder dielectric barrier plasma discharge technology, and the voltage U unit V is applied between the two electrodes, and 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, in V / mm, t is the total thickness of the two dielectric layers, in 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 blocking 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, using the hydrodynamic cavitation and plasma system for degrading organic wastewater, the method comprising:

[0026] Step 1: Open the organic wastewater inlet and the organic wastewater outlet, start the water pump to pump the organic wastewater to the liquid storage tank to the aeration device at a certain flow rate, 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, and the rotor rotates to induce strong shear force and cavitation effect around the upper and lower teeth, and a large number of cavitation bubbles are generated in the cavitation reaction chamber and hydroxyl free radicals are released;

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

[0029] Step 4: The rotor rotates at high speed while discharging, and the organic wastewater is sucked from the plasma discharge chamber into the cavitation reaction chamber through the upper jet cavitation channel, inducing the fluid to form a continuous circulation flow between the cavitation area of ​​the cavitation reaction chamber and the discharge area of ​​the plasma discharge chamber, and 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 a 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 is optimized and the upper and lower teeth with opposite inclination angles are set. The upper and lower teeth with opposite inclination angles are designed on the rotor to enhance the shear force of the wastewater in the cavitation area and intensify the formation and rupture of bubbles. The opposite tooth inclination angles improve the flow pattern of the wastewater, accelerate the circulation of the wastewater between the cavitation area and the discharge area, strengthen the cavitation process and ionization effect of the organic wastewater, and further improve the gas-liquid mass transfer efficiency and degradation effect.

[0034] (3) An upper jet cavitation channel and a lower jet cavitation channel are designed. An upper jet cavitation channel with an inner radial contraction of the inner wall of the cavitation reaction chamber is set, and a lower jet cavitation channel with an inner radial contraction of the inner wall of the plasma discharge chamber is set. The pressure difference on both sides of the upper jet cavitation channel causes 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 squeezes the liquid in the cavitation area into the discharge area. The organic wastewater cavitates in the cavitation reaction chamber and can fully contact with the active substances generated by the medium blocking 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. A cooling channel for the electrode is set up to achieve continuous heat dissipation of the electrode, ensuring that the system operates efficiently 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 double-cylinder dielectric barrier plasma discharge is calculated, and the applied voltage is adjusted according to the actual situation to avoid 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 a hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater provided in 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 A schematic structural diagram of an upper shell provided in an embodiment of the present invention.

[0041] Figure 4 A schematic structural diagram of a lower shell provided in 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 convection diagram in a plasma rotary cavitation reactor provided in 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, different aspects of the embodiments are defined in more detail. Each aspect so defined can be combined with any other aspect or aspects, unless explicitly stated not to be combined. In particular, any feature that is considered to be preferred or advantageous can be combined with one or more other features that are considered to be preferred or advantageous.

[0047] The terms "first", "second" and the like 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 intermediate 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 intermediate elements interposed therebetween. Hereinafter, the same reference numerals represent the same elements.

[0049] In the present invention, descriptions of directions or positional relationships indicated by “upper”, “lower”, “top”, “bottom”, “front”, “back”, “inside” and “outside” are used only to facilitate the description of the present invention, and do not indicate or imply that the device referred to must have a specific direction, be constructed and operated 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, which in some embodiments 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, wherein 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 through the water pump 2; the other end of the aeration device 3 is connected to the plasma rotary cavitation reactor 4 through the water pump 2; the wastewater in the liquid storage tank 1 is passed through the aeration device 3 to generate a gas-liquid two-phase solution with microbubbles, and the water pump 2 pumps the gas-liquid two-phase solution in the aeration device 3 to 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 shell 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, wherein the organic wastewater inlet 48 is arranged at the bottom of the reactor shell 43, and the organic wastewater outlet 49 is arranged at the top of the reactor shell 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 shell 43 by water pressure. The rotor motor 41 is fixed to the motor bracket 42 by bolts, and the motor bracket 42 is fixed to the reactor shell 43 by bolts. The output end of the rotor motor 41 is connected to the rotor main shaft 411 through a coupling; the reactor shell 43 provides support and fixation for the internal components of the entire plasma rotary cavitation reactor 4, and the reactor shell 43 is provided with a plasma discharge chamber 431, a fan-shaped electrode 432 and a cavitation reaction chamber 433.

[0052] like Figure 2 and Figure 5As shown, in some embodiments, a rotor 44 is arranged in the cavitation reaction chamber 433, a through hole 443 is arranged in the center of the rotor 44, an upper row of teeth 441 and a lower row of teeth 442 are arranged on the outer wall, and a groove 444 is arranged 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 penetrated in the through hole 443, and the end of the rotor main shaft 411 is fixedly connected to the rotor 44 by bolts, 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 angles of the upper row of teeth 441 and the lower row of teeth 442 are 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 channel 45 and the lower jet cavitation channel 46 are set as hyperbolic holes, and the edges are connected by arc transition to form a smooth channel.

[0055] The pressure difference formed by the flow velocity difference on both sides of the upper jet cavitation channel 45 and the lower jet cavitation channel 46 causes 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, 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, 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.

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

[0057] Furthermore, an 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 an opening end with a smaller inner diameter is opened on the inner wall of the cavitation reaction chamber 433; an 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 an 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 arranged inside the upper shell 434; a machine waste water inlet 48 connected to the cavitation reaction chamber 433 is arranged inside the lower shell 435; an electrode cooling channel 47 is arranged 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, wherein the electrode cooling channel inlet 471 is arranged in the lower shell 435, and a plurality of holes of the electrode cooling channel outlet 472 are evenly 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 leads to a decrease in pressure. 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 leads to an increase in pressure. 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 , 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 to the cavitation reaction chamber 433 through the upper jet cavitation channel 45; 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 sucked 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 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, 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.

[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 of the two cylindrical hollow cavities forms a plasma discharge cavity 431 with a width, inner diameter and length of 5 mm, 16 mm and 80 mm respectively.

[0063] The fan-shaped electrode 432 is fixed on the outer wall of the plasma discharge chamber 431 and is distributed in a surrounding manner. A layer of fan-shaped electrode 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 electrode 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. Specifically, the fan-shaped electrode 432 is fixed in the slot 436 on the outer wall of the plasma discharge chamber 431, and the fan-shaped electrode 432 is connected to the high-voltage power supply 6 through a wire. By applying a sufficiently high voltage between the two electrodes, a dielectric barrier plasma discharge phenomenon is formed to generate active substances such as ozone and hydroxyl radicals in 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, the voltage of the applied alternating current exceeds the breakdown voltage of the gas, and a plasma discharge phenomenon occurs. 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, in V / mm, t is the total thickness of the two dielectric layers, in 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 blocking 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 time, the total thickness of the two dielectric layers is 4mm, the equivalent discharge gap when the gas-liquid two-phase flow is passed between the two electrodes is 4mm, the dielectric constant of the gas is 1, and the dielectric constant of the quartz glass is 3.7. According to Paschen's law, the breakdown voltage of the gas is 3000V / mm under normal circumstances. The minimum voltage that needs to be applied at this time is calculated to be 15200V, so the design with a power output of 15200V can achieve the minimum voltage of 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 energy consumption of the system and the wear of the electrodes.

[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, and includes 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 to the liquid storage tank 1 to the aeration device 3 at a certain flow rate, 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 induce strong shear force and cavitation effect around the upper row of teeth 441 and the lower row of teeth 442, and a large number of cavitation bubbles are generated in the cavitation reaction chamber 433 and hydroxyl free radicals are released;

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

[0073] 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, inducing 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;

[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 make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrodynamic cavitation-coordinated 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 a water pump (2); A plasma discharge chamber (431) and a cavitation reaction chamber (433) are arranged inside the reactor shell (43); the plasma discharge chamber (431) and the cavitation reaction chamber (433) are connected via a plurality of upper jet cavitation channels (45) and a plurality of lower jet cavitation channels (46); a sector-shaped electrode (432) is arranged on the outer wall of the plasma discharge chamber (431); 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 an 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 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 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).

2. The hydrodynamic cavitation synergistic plasma degradation organic wastewater system according to claim 1 is 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, wherein 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 passed through an aeration device (3) to generate a gas-liquid two-phase solution containing microbubbles, and a water pump (2) pumps the gas in the aeration device (3) into the wastewater. 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, and 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 synergistic plasma degradation organic wastewater system according to claim 2 is characterized in that: 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, thereby 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) rotates, its tooth inclination angle is the same as the rotation direction. The liquid is thrown out in the opposite direction to the surroundings, so that the liquid is squeezed from the cavitation reaction chamber (433) to the plasma discharge chamber (431) through the lower jet cavitation channel (46); the fluid is induced 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), so as to strengthen the cavitation process.

4. The hydrodynamic cavitation synergistic plasma degradation organic wastewater system according to claim 1, characterized in that: The electrode cooling channel (47) forms two coaxial cylindrical hollow cavities as a dielectric barrier layer, a sector-shaped electrode (432) is arranged in each of the hollow cavities, and a plasma discharge cavity (431) is arranged between the two hollow cavities.

5. The hydrodynamic cavitation synergistic plasma degradation organic wastewater system 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.

6. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 4, characterized in that: 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.

7. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 6, characterized in that: The reactor shell (43) comprises an upper shell (434) and a lower shell (435) which are connected to each other; the electrode cooling channel (47) comprises 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); the electrode cooling channel outlet (472) comprises 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 the air pump (5); the air pump (5) cools the fan-shaped electrode (432) from bottom to top through the electrode cooling channel (47).

8. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 1, characterized in that: The upper jet cavitation channel (45) and the lower jet cavitation channel (46) are arranged as hyperbolic holes, and the edges are connected by arc transition to form a smooth channel; 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).

9. The hydrodynamic cavitation-coordinated plasma degradation system for organic wastewater according to claim 6, characterized in that: When a 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, and a plasma discharge phenomenon occurs. The system adopts coaxial double-cylinder dielectric barrier plasma discharge technology. The voltage U applied between the two electrodes is in V, and the voltage value is calculated according to formula (1): Among them, E g is the voltage intensity of the gas in the discharge gap, in V / mm, t is the total thickness of the two dielectric layers, in 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 blocking 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): l gl ＝c·l d (2) 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.

10. A method for degrading organic wastewater by hydrodynamic cavitation and plasma, characterized in that: The method of using the hydrodynamic cavitation synergistic plasma degradation system for organic wastewater according to any one of claims 1 to 9 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 from the liquid storage tank (1) to the aeration device (3) at a certain flow rate, 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), and a large number of cavitation bubbles are generated in the cavitation reaction chamber (433) and hydroxyl free radicals are released; 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), thereby forming a dielectric barrier plasma discharge, and generating ozone and hydroxyl radicals in the water; while discharging, the air pump (5) is turned on to dissipate the heat of 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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