Device and method for treating VOC (Volatile Organic Compound) waste gas by utilizing micro-nano bubble reinforced multiphase advanced oxidation technology

Abstract

The invention discloses a device and a method for treating VOC (volatile organic compound) waste gas by utilizing a micro-nano bubble enhanced multi-phase advanced oxidation technology. The device comprises a reaction tower, a mixed gas micro-nano bubble water generation unit and an ozone micro-nano bubble water generation unit. According to the device disclosed by the invention, by arranging the mixed gas micro-nano bubble water generation unit and the ozone micro-nano bubble water generation unit, VOC waste gas and ozone can be converted into micro-nano bubble water, so that the mass transfer effect and the treatment effect of the VOC waste gas are improved; the device has the advantages of simple structure, small investment, low operation cost, good treatment effect, high safety coefficient, easiness in engineering popularization and the like, can be widely used for treating the VOC waste gas, can realize efficient purification and stable up-to-standard emission of the VOC waste gas, and is high in use value, good in application prospect and suitable for popularization and application. The method is of great significance in effectively purifying VOC waste gas (such as light hydrocarbon waste gas) and meeting the requirements of enterprises.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic waste gas treatment, and relates to a VOC treatment device and method based on a multiphase advanced oxidation system of catalytic oxidation of ozone at room temperature, cavitation oxidation of micro-nano bubbles, and catalyst oxidation. Specifically, it relates to a device and method for treating VOC waste gas by using micro-nano bubbles to strengthen the multiphase advanced oxidation technology. Background Art

[0002] Volatile organic compounds (VOCs), as the main pollutants in typical air pollution incidents, are one of the most concerned pollutant gases in recent years, and the treatment of VOCs has attracted wide attention. The sources of VOCs are extensive. The oil refining and petrochemical industries, the coal chemical industry, chemical synthesis, and fuel combustion are all the main sources of VOC emissions. At the same time, due to its complex composition and high treatment difficulty, the degradation of VOCs is extremely challenging in various industrial waste gas treatments. Traditional treatment technologies, such as photocatalysis, adsorption, combustion, photooxidation, low-temperature plasma, and electrocatalysis, are difficult to meet the actual treatment requirements due to disadvantages such as low treatment efficiency, easy generation of secondary pollution or hazardous waste. Therefore, there is an urgent need to develop a green, efficient, economical, and energy-saving VOC treatment technology.

[0003] Due to their long residence time in water, high interfacial potential, high mass transfer efficiency, strong interfacial effect, and ability to release free radicals, micro-nano bubbles have become an emerging technology for treating organic pollutants at home and abroad. They exhibit excellent technical advantages and broad application prospects in environmental engineering fields such as organic wastewater treatment and black and odorous water body restoration. However, due to the complex composition, large flow rate, and low water solubility of industrial VOC waste gases, the treatment of VOCs by micro-nano bubbles mainly relies on absorption, with weak oxidation ability and low mineralization degree. Therefore, their application in waste gas treatment is still in its infancy. In addition, ozone has strong oxidizing properties, fast reaction rates, and less secondary pollution, making it an advantageous oxidant for treating VOCs. However, it has problems such as unstable properties and low mass transfer efficiency. Therefore, enhancing the utilization rate of ozone is an effective means to improve the treatment efficiency of VOCs. However, the vast majority of current catalytic ozonation processes for treating VOCs are limited to the gas-solid two-phase, with relatively strict requirements for temperature and humidity. Therefore, there is an urgent need to develop combined treatment technologies to improve the ozone mass transfer efficiency and oxidation ability. Existing research has shown that the use of the micro-nano bubble ozone coupling technology can effectively enhance the ozone oxidation ability and also improve the VOC mineralization degree. However, currently, this technology still faces the following deficiencies: 1) The energy consumption for generating micro-nano bubbles is high, the types of VOCs that can be treated are single, the treatment volume is low, and it is difficult to apply to industrial waste gases with complex compositions, high concentrations, and large flow rates, resulting in a disconnect between experimental research and practical engineering applications; 2) When hydrophobic VOC gases are directly introduced into the reaction tower, the mass transfer efficiency from the gas phase to the micro-nano bubble liquid phase is low, resulting in low utilization rate of pure ozone micro-nano bubbles and poor treatment effects; 3) The liquid distribution method of ozone micro-nano bubbles in the treatment methods involved is single. Especially in the oxidation system with solid catalysts, due to uneven water and gas distribution, it is difficult to promote the multi-phase mass transfer efficiency in the system to a greater extent. This makes the system unable to completely convert VOCs into carbon dioxide and water, and ultimately results in high VOC emission concentrations that cannot meet the emission standards.

[0004] Therefore, obtaining a method for treating VOCs with high efficiency and energy conservation, and a combined treatment technology device for treating VOCs with a simple structure, low operating cost, high mass transfer efficiency, good treatment effect, high safety factor, and easy to promote in engineering is of great significance for effectively treating VOC waste gases and meeting the needs of enterprises. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a device for treating VOC waste gases using micro-nano bubble enhanced multi-phase advanced oxidation technology with a simple structure, low operating cost, high mass transfer efficiency, good treatment effect, high safety factor, and easy to promote in engineering. The present invention also provides a method for treating VOC waste gases using micro-nano bubble enhanced multi-phase advanced oxidation technology with simple operation, low cost, high treatment efficiency, good purification effect, and no secondary air pollution.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] An apparatus for treating VOC waste gas by using a micro-nano bubble enhanced multi-phase advanced oxidation technology, comprising a mixed gas micro-nano bubble water generation unit, an ozone micro-nano bubble water generation unit, and a reaction tower;

[0008] The reaction tower includes a spray chamber and a bubbling chamber that are interconnected, and the spray chamber is located above the bubbling chamber;

[0009] The ozone micro-nano bubble water generation unit is respectively connected to the bubbling chamber and the spray chamber, and is used to provide ozone micro-nano bubble water to the spray chamber and the bubbling chamber;

[0010] The mixed gas micro-nano bubble water generation unit includes a first ozone generator and a first micro-nano bubble generator, and a VOC waste gas inlet is connected to the pipeline between the first ozone generator and the first micro-nano bubble generator; the first micro-nano bubble generator is connected to the bubbling chamber and is used to provide mixed gas micro-nano bubble water to the bubbling chamber.

[0011] As a further improvement of the above technical solution, a gas mixing tank is provided on the pipeline between the VOC waste gas inlet and the first micro-nano bubble generator, and a first gas-liquid mixing pump is provided on the pipeline between the gas mixing tank and the first micro-nano bubble generator; the first gas-liquid mixing pump is connected to the bubbling chamber.

[0012] As a further improvement of the above technical solution, a micro-nano bubble distribution plate is further provided at the bottom of the bubbling chamber, and the micro-nano bubble distribution plate is connected to the first micro-nano bubble generator; at least one bubbling chamber packing load layer is further provided above the micro-nano bubble distribution plate; the bubbling chamber packing load layer is a square grid structure composed of titanium mesh; the grid length of the titanium mesh is 1 mm to 3 mm.

[0013] As a further improvement of the above technical solution, the bubbling chamber packing load layer is loaded with a packing material and / or a solid catalyst for catalytic ozonation; the packing material is made of at least one of plastic, ceramic, or gravel; the shape of the packing material is a Pall ring, a Raschig ring, a conjugate ring, a saddle ring, or a combined ring composed of them; the solid catalyst for catalytic ozonation is a supported catalyst, and the supported catalyst includes a carrier material and a catalyst active component, and the catalyst active component is supported on the carrier material; the carrier material is zeolite, molecular sieve, Al 2 O 3 、SiO 2either one of them or SiC; the water absorption rate of the carrier material is 40% to 70%, and the particle size is 1 mm to 10 mm; the catalyst active components are one or more of Fe, Mn, Ni, Co, Cu, and Ce.

[0014] As a further improvement of the above technical solution, the ozone micro-nano bubble water generation unit includes a second ozone generator and a second micro-nano bubble generator, and a second gas-liquid mixing pump is provided on the pipeline between the second ozone generator and the second micro-nano bubble generator; the second gas-liquid mixing pump is communicated with the bubbling chamber; the second micro-nano bubble generator is communicated with the micro-nano bubble distribution plate.

[0015] As a further improvement of the above technical solution, at least one sprayer is further provided in the spray chamber, and the sprayer is communicated with the second micro-nano bubble generator through a pipeline; a spray chamber packing load layer is further provided below the sprayer; the spray chamber packing load layer is a square grid structure composed of titanium mesh; the grid length of the titanium mesh is 1 mm to 3 mm.

[0016] As a further improvement of the above technical solution, the spray chamber packing load layer is loaded with a packing material and / or a solid catalyst for catalytic ozonation; the material of the packing material is at least one of plastic, ceramic, or gravel; the shape of the packing material is Pall ring, Raschig ring, conjugate ring, saddle ring, or a combined ring composed of them; the solid catalyst for catalytic ozonation is a supported catalyst, and the supported catalyst includes a carrier material and a catalyst active component, and the catalyst active component is supported on the carrier material; the carrier material is zeolite, molecular sieve, Al 2 O 3 、SiO 2 or either one of them or SiC; the water absorption rate of the carrier material is 40% to 70%, and the particle size is 1 mm to 10 mm; the catalyst active components are one or more of Fe, Mn, Ni, Co, Cu, and Ce.

[0017] As a further improvement of the above technical solution, the supported catalyst uses Al 2 O 3 particles wrapped with a graphitized shell layer as the carrier skeleton, and metal particles of Fe and Mn are supported on the carrier skeleton to form a core-multi-shell structure; the water absorption rate of the Al 2 O 3 particles wrapped with a graphitized shell layer is 65% to 70%.

[0018] As a further improvement of the above technical solution, a demister is provided above the sprayer, and an ozone tail gas destructor is provided above the demister; the distance between the sprayer and the demister is 0.1 m to 0.5 m; the sprayer is a circular nozzle with atomizing small holes; the diameter of the atomizing small holes is 1 mm to 5 mm, and the atomizing small holes are arranged in concentric circles, and the number of arranged circles is 2 to 5; the demister is a curved panel with holes.

[0019] As a further improvement of the above technical solution, a tail gas discharge pipe is further provided at the top of the spray chamber; the spray tower chamber is a cylinder with a diameter of 12 cm to 36 cm and a height of 1 m to 3 m; the bubbling chamber is a cube with a side length of 0.5 m to 1.5 m.

[0020] As a general technical concept, the present invention also provides a method for treating VOC waste gas by using a micro-nano bubble enhanced multi-phase advanced oxidation technology, and the method is to treat VOC waste gas by using the above device.

[0021] As a further improvement of the above technical solution, it includes the following steps:

[0022] S1. Introduce the VOC waste gas and ozone into the first micro-nano bubble generator to generate a mixed gas micro-nano bubble water, and introduce it into the bubbling chamber;

[0023] S2. Introduce ozone into the second micro-nano bubble generator to generate ozone micro-nano bubble water, and introduce it into the spray chamber and the bubbling chamber respectively.

[0024] As a further improvement of the above technical solution, in step S1, the inlet concentration of the VOC waste gas is 100 mg / m 3 ~3000 mg / m 3 , the inlet pressure ≤ 0.4 MPa; the residence time of the VOC waste gas in the reaction tower is 2 s to 20 s; the VOC waste gas contains light hydrocarbons; the light hydrocarbons are one or more of benzene, toluene, and xylene; the concentration of ozone is 20 mg / L to 200 mg / L; the inlet flow rate of ozone is 1 L / min to 3 L / min; the outlet flow rate of the mixed gas micro-nano bubble water in the bubbling chamber is 10 L / min to 30 L / min.

[0025] As a further improvement of the above technical solution, in step S2, the concentration of ozone is 20 mg / L to 200 mg / L, the inlet flow rate of ozone is 1 L / min to 3 L / min, and the outlet flow rate of the ozone micro-nano bubble water in the bubbling chamber is 10 L / min to 30 L / min; the outflow rate of the ozone micro-nano bubble water in the spray chamber and the liquid-gas ratio of the VOC waste gas are 6 to 12; the solution in the bubbling chamber is updated every 20 to 30 days.

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] (1) Aiming at the deficiencies such as high energy consumption, high operating cost, poor mass transfer efficiency, poor treatment effect, and low safety factor existing in the existing VOC waste gas treatment devices, and the resulting defects such as the difficulty of meeting the emission standards of VOC waste gas, the present invention provides a device for treating VOC waste gas by using the micro-nano bubble enhanced multi-phase advanced oxidation technology. By setting up a mixed gas micro-nano bubble water generation unit and an ozone micro-nano bubble water generation unit, on the one hand, the mixed gas micro-nano bubble water generation unit can mix the VOC waste gas with ozone gas to form mixed gas micro-nano bubble water, thereby enabling the preliminary mixing of the VOC waste gas and ozone, and the VOC waste gas is preliminarily absorbed and oxidized in the mixed gas micro-nano bubble water. On the other hand, the ozone micro-nano bubble water generation unit can convert ozone gas into ozone micro-nano bubble water. On this basis, the mixed gas micro-nano bubble water and ozone micro-nano bubble water are introduced into the bubbling chamber of the reaction tower, and the VOC waste gas can be fully turbulently contacted with the ozone micro-nano bubble water in the bubbling chamber, and the VOC waste gas is further absorbed and oxidized. Therefore, under the synergistic action of the mixed gas micro-nano bubble water generation unit and the ozone micro-nano bubble water generation unit, most of the VOC waste gas, especially the hydrophilic VOC waste gas, is absorbed and oxidized in the bubbling chamber. On this basis, a small part of the untreated VOC waste gas enters the spraying chamber upward and contacts the ozone micro-nano bubble water reversely, and undergoes a convective reaction to enhance its gas-liquid mass transfer, so that the VOC waste gas is further absorbed and oxidized, thereby realizing the effective degradation of VOC waste gas under safe and environmental protection conditions. Compared with the conventional treatment device, the device of the present invention has the advantages of simple structure, small investment, low operating cost, good treatment effect, high safety factor, and easy engineering promotion, and can be widely used for treating VOC waste gas, which is of great significance for effectively purifying VOC waste gas (such as light hydrocarbon waste gas) and meeting the needs of enterprises.

[0028] (2) In the device of the present invention, by setting up a spraying chamber packing loading layer and a bubbling chamber packing loading layer, it is beneficial to increase the contact probability between the VOC waste gas and the ozone micro-nano bubble water, thereby enhancing the decomposition efficiency and utilization efficiency of ozone and maximizing the treatment efficiency and treatment effect of the VOC waste gas. At the same time, by setting up a demister, it can effectively avoid the accumulation of fog, improve the detection efficiency and accuracy, and improve the safety production coefficient. Moreover, by setting up an ozone tail gas destructor, it can remove the excess ozone and avoid secondary pollution.

[0029] (3) In the device of the present invention, packing materials and solid catalysts for catalytic ozonation are also loaded in the packing load layer of the spray chamber and the packing load layer of the bubbling chamber. The purification effect of VOC waste gas is enhanced by using highly efficient solid catalysts to catalyze ozonation. Specifically, the solid catalysts enhance ozone oxidation, which can further accelerate the decomposition of ozone, reduce the ozone escape rate, and improve its indirect oxidation ability using active oxygen for oxidation. Therefore, in the present invention, technologies such as catalytic ozone advanced oxidation, micro-nano bubble technology enhancement, and enhanced multi-phase mass transfer are effectively coupled, which greatly improves the absorption, mass transfer, and degradation of VOC waste gas in the gas-liquid-solid three-phase system, and is beneficial to improving the treatment efficiency and treatment effect of VOC waste gas. In addition, no additional energy input is required during the treatment process of the present invention, which has the advantages of economy and energy conservation. Moreover, since a large amount of VOC waste gas introduced into the reaction tower is promptly treated and consumed, the reaction tower can continuously and stably treat VOC waste gas, and the risk coefficient is significantly reduced.

[0030] (4) The present invention provides a method for treating VOC waste gas by using micro-nano bubble enhanced multi-phase advanced oxidation technology. When using the device of the present invention to treat VOC waste gas, by first converting VOC waste gas into micro-nano bubbles, it promotes the absorption and mass transfer of VOC, strengthens ozone catalysis, and is beneficial to improving the treatment efficiency and treatment effect of VOC waste gas. Moreover, due to the advantages of micro-nano bubbles such as a large specific surface area, high surface negative charge, excellent gas dissolution ability, slow rising speed in water, and high stability, more VOC waste gas can be dissolved into the micro-nano bubbles. At the same time, the gas dissolved in the micro-nano bubbles undergoes thermal decomposition as the bubbles burst, generating active oxygen such as ·OH at the gas-liquid interface, which enhances the absorption of hydrophobic VOC, accelerates the decomposition rate of ozone, enhances the indirect oxidation ability of ozone, improves the ozone utilization rate and mass transfer efficiency, and overcomes the limitations of ozone oxidation in multi-phase reaction treatment. In addition, during the treatment process, the ozone micro-nano bubbles are redispersed and recycled by bubbling and spraying, further prolonging the residence time of the ozone micro-nano bubbles in the circulating liquid. This not only improves the treatment time and treatment efficiency of VOC waste gas, but also strengthens the efficient oxidation and decomposition of the VOC waste gas absorbed in the water in the bubbling chamber and its preliminary oxidation products and other organic substances, improves the mineralization efficiency of the organic substances absorbed in the liquid phase, and realizes the deep purification of VOC waste gas. In addition, the purification effect of VOC waste gas is enhanced by using highly efficient solid catalysts to catalyze ozonation. Compared with the conventional treatment process of VOC waste gas, the method of the present invention has the advantages of simple operation, low cost, high treatment efficiency, good purification effect, no secondary air pollution, and low fire protection requirements. It is a new treatment method that is safe, green, economic, and energy-saving, can achieve the efficient purification of VOC waste gas, stable up-to-standard discharge, has high use value, and good application prospects. Description of the Drawings

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention.

[0032] Figure 1 It is a schematic structural diagram of the device for treating VOC waste gas by using the micro-nano bubble enhanced multi-phase advanced oxidation technology in Embodiment 1.

[0033] Figure 2 It is the degradation effect diagram of VOC waste gas under different treatment conditions in Embodiment 2 of the present invention.

[0034] Figure 3 It is the treatment effect curve graph of VOC waste gas by using the micro-nano bubble enhanced multi-phase advanced oxidation technology in Embodiment 3 of the present invention.

[0035] Legend description:

[0036] 101. First ozone generator; 102. Second ozone generator; 201. First micro-nano bubble generator; 202. Second micro-nano bubble generator; 3. VOC waste gas inlet; 4. Gas mixing tank; 5. Spray chamber; 6. Bubbling chamber; 7. Sprayer; 8. Spray chamber packing load layer; 9. Demister; 10. Ozone tail gas destroyer; 11. Tail gas discharge pipe; 12. Micro-nano bubble distribution plate; 13. Bubbling chamber packing load layer; 14. Mixed gas micro-nano bubble water inlet; 15. Water sample sampling port; 16. Water change port; 17. Water pump; 181. First gas-liquid mixing pump; 182. Second gas-liquid mixing pump; 19. Control valve; 20. Gas flow meter; 21. Liquid flow meter. Specific embodiments

[0037] The following further describes the present invention with reference to the accompanying drawings of the specification and specific preferred embodiments, but does not limit the protection scope of the present invention thereby.

[0038] The materials and instruments used in the following embodiments are all commercially available. In the embodiments of the present invention, unless otherwise specified, the processes used are conventional processes, the equipment used is conventional equipment, and the obtained data are all the averages of more than three tests.

[0039] Embodiment 1

[0040] As Figure 1As shown in the figure, the device for treating VOC waste gas by using the micro-nano bubble enhanced multi-phase advanced oxidation technology in this embodiment includes a mixed gas micro-nano bubble water generation unit, an ozone micro-nano bubble water generation unit, and a reaction tower; the reaction tower includes a spray chamber 5 and a bubbling chamber 6 that are interconnected, and the spray chamber 5 is located above the bubbling chamber 6; the ozone micro-nano bubble water generation unit is respectively connected to the bubbling chamber and the spray chamber 5 for providing ozone micro-nano bubble water into the spray chamber 5 and the bubbling chamber 6; the mixed gas micro-nano bubble water generation unit includes a first ozone generator 101 and a first micro-nano bubble generator 201, and a VOC waste gas inlet 3 is connected to the pipeline between the first ozone generator 101 and the first micro-nano bubble generator 201; the first micro-nano bubble generator 201 is connected to the bubbling chamber 6 for providing mixed gas micro-nano bubble water into the bubbling chamber 6.

[0041] In this embodiment, a gas mixing tank 4 is provided on the pipeline between the VOC waste gas inlet 3 and the first micro-nano bubble generator 201, and a first gas-liquid mixing pump 181 is provided on the pipeline between the gas mixing tank 4 and the first micro-nano bubble generator 201; the first gas-liquid mixing pump 181 is connected to the bubbling chamber 6.

[0042] In this embodiment, a micro-nano bubble distribution plate 12 is further provided at the bottom of the bubbling chamber 6, and the micro-nano bubble distribution plate 12 is connected to the first micro-nano bubble generator 201; a bubbling chamber packing loading layer 13 is further provided above the micro-nano bubble distribution plate 12; the bubbling chamber packing loading layer 13 is a square grid structure composed of titanium mesh; the grid length of the titanium mesh is 2 mm. In this embodiment, the bubbling chamber packing loading layer 13 is not loaded with packing materials and solid catalysts. According to needs, packing materials and solid catalysts for catalytic ozonation can be loaded in the bubbling chamber packing loading layer 13. For example, the material of the packing materials is at least one of plastic, ceramic, or gravel, and the shape of the packing materials is Pall ring, Raschig ring, conjugate ring, Intalox saddle ring, or a combined ring composed of them. The solid catalyst for catalytic ozonation is a supported catalyst, and the supported catalyst includes a carrier material and a catalyst active component. The catalyst active component is loaded on the carrier material, and the carrier material is zeolite, molecular sieve, Al 2 O 3 , SiO 2 or SiC, the water absorption rate of the carrier material is 40% - 70%, and the particle size is 1 mm - 10 mm; the catalyst active components are one or more of Fe, Mn, Ni, Co, Cu, Ce.

[0043] In this embodiment, the ozone micro-nano bubble water generating unit includes a second ozone generator 102 and a second micro-nano bubble generator 202. A second gas-liquid mixing pump 182 is provided on the pipeline between the second ozone generator 102 and the second micro-nano bubble generator 202; the second gas-liquid mixing pump 182 is connected to the bubbling chamber 6; the second micro-nano bubble generator 202 is connected to the micro-nano bubble distribution plate 12.

[0044] In this embodiment, at least one sprayer 7 is further provided in the spray chamber 5, such as two or three. Specifically, in this embodiment, the number of sprayers 7 is 2. The sprayer 7 is connected to the second micro-nano bubble generator 202 through a pipeline; a spray chamber packing load layer 8 is further provided below the sprayer 7; the spray chamber packing load layer 8 is a square grid structure composed of titanium mesh; the grid length of the titanium mesh is 2 mm. In this embodiment, the spray chamber packing load layer 8 is not loaded with packing materials and solid catalysts. According to needs, packing materials and solid catalysts for catalytic ozonation can be loaded in the spray chamber packing load layer 8. For example, the material of the packing materials is at least one of plastic, ceramic or gravel, and the shape of the packing materials is Pall ring, Raschig ring, conjugate ring, saddle ring or a combined ring composed of them. The solid catalyst for catalytic ozonation is a supported catalyst, and the supported catalyst includes a carrier material and a catalyst active component. The catalyst active component is loaded on the carrier material, and the carrier material is zeolite, molecular sieve, Al 2 O 3 、SiO 2 or SiC; the water absorption rate of the carrier material is 40% - 70%, and the particle size is 1 mm - 10 mm; the catalyst active components are one or more of Fe, Mn, Ni, Co, Cu, Ce.

[0045] In this embodiment, a demister 9 is provided above the sprayer 7, and an ozone tail gas destroyer 10 is provided above the demister 9; the distance between the sprayer 7 and the demister 9 is 0.1 m; the sprayer 7 is a circular nozzle with atomizing small holes; the diameter of the atomizing small holes is 2 mm, and the atomizing small holes are arranged in concentric circles, and the number of arranged circles is 5; the demister 9 is a curved panel with holes.

[0046] In this embodiment, a tail gas discharge pipe 11 is further provided at the top of the spray chamber 5; the spray tower chamber is a cylinder with a diameter of 12 cm and a height of 1.5 m; the bubbling chamber is a cube with a side length of 0.8 m.

[0047] In this embodiment, a water replacement port 16 is further provided at the bottom of the bubbling chamber 6. The water replacement port 16 is connected to a water pump 17 for replacing the washing liquid in the bubbling chamber 6. At the same time, a mixed gas micro-nano bubble water inlet 14 is also provided at the bottom of the bubbling chamber 6. The mixed gas micro-nano bubble water generated in the first micro-nano bubble generator 201 enters the micro-nano bubble distribution plate 12 through the mixed gas micro-nano bubble water inlet 14. A water sample sampling port 15 is further provided above the bubbling chamber 6, which is convenient for detecting the water quality of the solution in the bubbling chamber 6.

[0048] In this embodiment, a gas flow meter 20 is further provided on the intake pipeline of the VOC waste gas intake port 3 to monitor and adjust the intake volume of the VOC waste gas; a control valve 19 and a liquid flow meter 21 are successively provided on the pipeline between the second micro-nano bubble generator 202 and the sprayer 7 to control the dosage of the ozone micro-nano bubble water.

[0049] In this embodiment, the ozone generated in the first ozone generator 101, the VOC waste gas from the VOC waste gas intake port 3, and the solution in the bubbling chamber 6 are introduced into the first micro-nano bubble generator 201 through the first gas-liquid mixing pump 181. The first micro-nano bubble generator 201 generates mixed gas micro-nano bubble water. In this process, the VOC waste gas is initially absorbed and oxidized in the mixed gas micro-nano bubble water, and then is sprayed into the bubbling chamber through the micro-nano bubble distribution plate 12. In this process, the turbulence formed at the outlet of the micro-nano bubble distribution plate 12 is utilized to further improve the contact effect between the VOC waste gas and ozone, so that the VOC waste gas is further absorbed and oxidized. At this time, most of the VOC waste gas, especially the hydrophilic VOC waste gas, can achieve good treatment effects in the bubbling chamber. Further, a small part of the unprocessed VOC waste gas enters the spraying chamber 5 upward and contacts the ozone micro-nano bubble water sprayed into the spraying chamber 5 in a countercurrent manner for a convection reaction, enhancing its gas-liquid mass transfer, and the VOC waste gas is further absorbed and oxidized. Thus, the effective degradation of the VOC waste gas is realized under safe and environmental protection conditions.

[0050] In this embodiment, by providing the spray chamber packing loading layer 8 and the bubbling chamber packing loading layer 13, it is beneficial to increase the contact probability between the VOC waste gas and the ozone micro-nano bubble water, thereby enhancing the decomposition efficiency and utilization efficiency of ozone and maximizing the treatment efficiency and treatment effect of the VOC waste gas; at the same time, by providing the demister 9, the aggregation of fog can be effectively avoided, the detection efficiency and accuracy can be improved, the safety production coefficient can be improved, and by providing the ozone tail gas destroyer, the excess ozone can be removed to avoid secondary pollution.

[0051] Therefore, the device of the present invention has the advantages of simple structure, small investment, low operating cost, good treatment effect, high safety factor, easy engineering promotion, etc., and can be widely used for treating VOC waste gas, which is of great significance for effectively purifying VOC waste gas and meeting the needs of enterprises.

[0052] Example 2

[0053] A method for treating VOC waste gas by using a micro-nano bubble enhanced multi-phase advanced oxidation technology, specifically, the device of Example 1 is used to treat VOC waste gas, including the following steps:

[0054] Step 1): Turn on the first ozone generator connected to the VOC waste gas inlet to generate ozone, mix the VOC waste gas with ozone in the gas mixing tank, and then pump the obtained mixed gas and the circulating washing liquid from the bubbling chamber into the first micro-nano bubble generator through the first gas-liquid mixing pump to generate mixed gas micro-nano bubble water in the first micro-nano bubble generator. During this process, the VOC waste gas is preliminarily absorbed and oxidized in the mixed gas micro-nano bubble water, and then enters the reaction tower from the lower side of the bubbling chamber through the micro-nano bubble distribution plate. Among them, the inlet concentration of the VOC waste gas (containing benzene) is 500 mg / m 3 , the inlet pressure ≤ 0.4 MPa, the inlet flow rate is 1 m 3 / h, the concentration of ozone is 60 mg / L, the inlet flow rate of ozone is 1 L / min, and the flow rate of the mixed gas micro-nano bubble water entering the bubbling chamber is 10 L / min.

[0055] Step 2): Ozone generated by the second ozone generator and the circulating washing liquid from the bubbling chamber are pumped into the second micro-nano bubble generator by the second gas-liquid mixing pump to generate ozone micro-nano bubble water, where the concentration of ozone is 60 mg / L and the ozone inlet flow rate is 1 L / min. Further, the ozone micro-nano bubble water is sent into the bubbling chamber and the spraying chamber of the reaction tower through a sprayer and a micro-nano bubble distribution plate respectively. The ozone micro-nano bubble water is sprayed downward through the sprayer and circulates to the spraying chamber after reaching the bubbling chamber. The outlet flow rate of the ozone micro-nano bubble water in the bubbling chamber is 10 L / min, and the liquid-gas ratio of the ozone micro-nano bubble water flowing out (spraying liquid) in the spraying chamber to the VOC waste gas is 10. The solution in the bubbling chamber is updated every 30 days. In this step, the ozone micro-nano bubble water collapses and breaks to generate hydroxyl radical micro-bubbles, which fully contact and react with the VOC waste gas in the reaction tower. The mixed gas micro-nano bubble water and the ozone micro-nano bubble water enter the bubbling chamber through the micro-nano bubble distribution plate, and a turbulent flow will be formed at the outlet. At this time, the contact between ozone and the VOC waste gas is more sufficient and the reaction is more intense, so that the VOC waste gas is further absorbed and oxidized, and most of the VOC waste gas, especially the hydrophilic VOC waste gas, can be well treated in the bubbling chamber. Further, a small part of the unprocessed VOC waste gas enters the spraying chamber upward and contacts the ozone micro-nano bubble water reversely for convective reaction, enhancing its gas-liquid mass transfer, so that the VOC waste gas is further absorbed and oxidized, thereby effectively degrading the VOC waste gas under safe and environmental protection conditions.

[0056] Step 3): The treated VOC waste gas passes through a demister to remove the entrained droplets, and then is discharged from the tail gas outlet. The droplets intercepted in the demister flow downward into the reaction tower.

[0057] In this embodiment, the residence time of the VOC waste gas in the reaction tower is 6 s.

[0058] During the above degradation reaction process, the VOC waste gas at different reaction times is taken, and its concentration is detected by a gas chromatograph and its degradation rate is calculated.

[0059] Comparative Example 1: In Step 1) above, the first ozone generator and the first micro-nano bubble generator are not turned on, that is, the VOC waste gas directly enters the tower in a bubbling manner; in Step 2) above, the VOC waste gas is treated under the condition that air enters the second micro-nano bubble generator to generate air micro-nano bubble water, and other conditions are the same.

[0060] Comparative Example 2: In the above step 1), the first ozone generator is not turned on, and air and VOC waste gas enter the first micro-nano bubble generator to generate micro-nano bubble water of a mixed gas of VOC and air; in the above step 2), under the condition that air enters the second micro-nano bubble generator to generate air micro-nano bubble water, the VOC waste gas is treated, and other conditions are the same.

[0061] Comparative Example 3: In the above steps 1) and 2), the VOC waste gas is treated without turning on the micro-nano bubble generator, that is, the VOC waste gas is directly bubbled into the tower to react with ordinary ozone water, and other conditions are the same.

[0062] Comparative Example 4: In the above step 1), the ozone generator and the micro-nano bubble generator are not turned on, that is, the VOC waste gas is directly bubbled into the tower, and the VOC waste gas is treated with ozone micro-nano bubble water, and other conditions are the same.

[0063] Figure 2 This is the degradation effect diagram of VOC waste gas under different treatment conditions in Example 2 of the present invention. As Figure 2 shown, the degradation rate of treating VOC waste gas with air micro-nano bubble water alone is 21% (Comparative Example 1), the degradation rate of treating VOC waste gas with micro-nano bubble water of a mixed gas of air and VOC is 35% (Comparative Example 2), the degradation rate of treating VOC waste gas with ordinary ozone bubble water is 50% (Comparative Example 3), the degradation rate of treating VOC waste gas with ozone micro-nano bubbles reaches 72% (Comparative Example 4), and in the present invention, the degradation rate of treating VOC waste gas by synergistically treating the micro-nano bubble water of the mixed gas generated by mixing VOC waste gas and ozone and ozone micro-nano bubble water reaches 81%. By comparison, it can be seen that the rupture of air micro-nano bubbles and single ozone oxidation have a certain treatment effect on VOC waste gas, but it is not significant. The coupling of ozone and micro-nano bubble technology can enhance the ability of ozone decomposition to generate active oxygen, significantly improve the utilization rate and mass transfer efficiency of ozone, and is beneficial to the treatment of hydrophobic VOC waste gas; at the same time, compared with the traditional intake method of directly bubbling VOC waste gas into ozone micro-nano bubble water, in the present invention, the intake method of mixing VOC waste gas and ozone to generate mixed micro-nano bubbles is more conducive to realizing the absorption and oxidation of VOC, thereby promoting the improvement of the degradation effect of VOC waste gas.

[0064] Example 3

[0065] A method for treating VOC waste gas by using a micro-nano bubble enhanced multi-phase advanced oxidation technology is basically the same as Example 2, except that: solid catalysts for catalytic ozonation are loaded in both the spray chamber packing load layer and the bubbling chamber load layer in Example 3. Specifically, the solid catalyst for catalytic ozonation is a supported catalyst (Fe-Mn / NiCAF), with Al particles wrapped by a graphitized shell 2 O 3 particles as the carrier skeleton, on which metal particles of Fe and Mn are loaded to form a core-multi-shell structure. The water absorption rate of the Al particles wrapped by a graphitized shell 2 O 3 is 65.2%.

[0066] In this embodiment, the Al particles wrapped by a graphitized shell 2 O 3 particles are Ni-induced graphitized Al skeletons( 2 O 3 CAF) obtained by promoting the catalytic graphitization of carbon molecules with metal Ni. Ni CAF).

[0067] In this embodiment, the Al 2 O 3 particles are γ-Al 2 O 3 .

[0068] In this embodiment, the preparation method of the supported catalyst (Fe-Mn / Ni CAF) includes the following steps:

[0069] (1) Weigh 60.0 g of γ-Al 2 O 3 carrier particles with a diameter of 3 - 5 mm and place them in a beaker. Add 300 mL of a NaOH solution with a mass fraction of 0.1%. Place the beaker in a shaker and shake for 2 hours. After shaking, wash with ultrapure water until neutral, and dry at an ambient temperature of 105°C for 12 hours.

[0070] (2) Prepare 100 mL of a precursor solution containing iron salt, manganese salt, nickel salt, and carbon source. Specifically, dissolve Fe(NO 3 ) 3 ·9H 2 O, Mn(CH 3 COO) 2 ·4H 2 O, Ni(CH 3 COO) 2 ·4H 2 O, and sucrose in water so that the concentration of Fe(NO 3 ) 3 ·9H 2 O in the solution is 0.03 mol / L, the concentration of Mn(CH 3 COO) 2 ·4H 2 O is 0.01 mol / L, and the concentration of Ni(CH 3 COO)2 ·4H 2 The concentration of O is 0.03 mol / L and the concentration of sucrose is 0.03 mol / L. According to the volume ratio of 1:10, add the pretreated γ-Al 2 O 3 support particles (20 g), mix them by shaking at 25 °C and 150 rpm for 12 hours. After shaking, let them stand and age for 2 hours, then filter. Filter again and dry at 80 °C for 12 hours to obtain the Al 2 O 3 particles loaded with the precursor.

[0071] (3) Place the supported catalyst particles (Al 2 O 3 particles loaded with the precursor) obtained in step (2) in a quartz boat, transfer them to a tubular furnace, and calcine them at 600 °C for 2 hours under a nitrogen atmosphere at a heating rate of 5 °C / min. Before calcination, control the nitrogen gas flow rate at 40 mL / min for 20 minutes to keep the calcination system in an oxygen-free inert state. During calcination, control the nitrogen gas flow rate at 20 mL / min. After calcination, cool it naturally to room temperature, wash it twice with distilled water (total amount is 200 mL), filter, collect the filtered product and dry it in vacuum at 80 °C to obtain the Ni-induced carbon modified γ-Al 2 O 3 support loaded with Fe and Mn supported catalyst, which is the supported catalyst of the present invention, namely Fe-Mn / Ni CAF.

[0072] Figure 3 This is the degradation effect diagram of VOC waste gas by the micro-nano bubble enhanced multi-phase advanced oxidation technology in Example 3 of the present invention. As Figure 3 shown, after adding the catalyst, the degradation rate of VOC waste gas reaches 98%. Combining Figure 2 and Figure 3 results show that the coupling of ozone micro-nano bubbles and multi-phase catalytic oxidation can further improve the degradation effect of VOC waste gas, which indicates that micro-nano bubbles enhance the absorption and mass transfer of VOC, accelerate the decomposition of ozone to generate free radicals, and combine with a highly efficient catalyst to strengthen the multi-phase advanced oxidation coupling technology for VOC, which is an effective method to enhance the ability of ozone decomposition to generate reactive oxygen species, improve the utilization rate of ozone and the mass transfer efficiency.

[0073] As can be seen from the above results, the device of the present invention has the advantages of simple structure, small investment, low operating cost, good treatment effect, high safety factor, easy engineering promotion, etc. It can be widely used for treating VOC waste gas, realizing the efficient purification of VOC waste gas and stable up-to-standard discharge, which is of great significance for effectively purifying VOC waste gas (such as light hydrocarbon waste gas) and meeting the needs of enterprises.

[0074] The above embodiments are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, the improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. An apparatus for treating VOC waste gas by using micro-nano bubble enhanced multi-phase advanced oxidation technology, characterized in that, it includes a mixed gas micro-nano bubble water generation unit, an ozone micro-nano bubble water generation unit and a reaction tower; The reaction tower includes a spray chamber (5) and a bubbling chamber (6) which are connected to each other, and the spray chamber (5) is located above the bubbling chamber (6); The ozone micro-nano bubble water generation unit is respectively connected to the bubbling chamber and the spray chamber (5) for supplying ozone micro-nano bubble water into the spray chamber (5) and the bubbling chamber (6); The mixed gas micro-nano bubble water generation unit includes a first ozone generator (101) and a first micro-nano bubble generator (201). A VOC waste gas inlet (3) is connected to the pipeline between the first ozone generator (101) and the first micro-nano bubble generator (201); the first micro-nano bubble generator (201) is connected to the bubbling chamber (6) for supplying mixed gas micro-nano bubble water into the bubbling chamber (6).

2. The apparatus according to claim 1, characterized in that, a gas mixing tank (4) is provided on the pipeline between the VOC waste gas inlet (3) and the first micro-nano bubble generator (201), and a first gas-liquid mixing pump (181) is provided on the pipeline between the gas mixing tank (4) and the first micro-nano bubble generator (201); the first gas-liquid mixing pump (181) is connected to the bubbling chamber (6).

3. The apparatus according to claim 2, characterized in that, A micro-nano bubble distribution plate (12) is further provided at the bottom inside the bubbling chamber (6), and the micro-nano bubble distribution plate (12) is communicated with the first micro-nano bubble generator (201); at least one bubbling chamber packing loading layer (13) is further provided above the micro-nano bubble distribution plate (12); the bubbling chamber packing loading layer (13) is a square grid structure composed of titanium mesh; the grid length of the titanium mesh is 1 mm to 3 mm; the bubbling chamber packing loading layer (13) is loaded with a packing material and / or a solid catalyst for catalytic ozonation; the packing material is made of at least one of plastic, ceramic or gravel; the shape of the packing material is Pall ring, Raschig ring, conjugate ring, saddle ring or a combined ring composed of them; the solid catalyst for catalytic ozonation is a supported catalyst, and the supported catalyst includes a carrier material and a catalyst active component, and the catalyst active component is loaded on the carrier material; the carrier material is zeolite, molecular sieve, Al 2 O 3 、SiO 2 or any one of SiC; the water absorption rate of the carrier material is 40% to 70%, and the particle size is 1 mm to 10 mm; the catalyst active component is one or more of Fe, Mn, Ni, Co, Cu, Ce.

4. The apparatus according to claim 3, characterized in that, The ozone micro-nano bubble water generation unit includes a second ozone generator (102) and a second micro-nano bubble generator (202). A second gas-liquid mixing pump (182) is provided on the pipeline between the second ozone generator (102) and the second micro-nano bubble generator (202); the second gas-liquid mixing pump (182) is connected to the bubbling chamber (6); the second micro-nano bubble generator (202) is connected to the micro-nano bubble distribution plate (12).

5. The apparatus according to claim 4, characterized in that, At least one sprayer (7) is further provided in the spray chamber (5), and the sprayer (7) is communicated with the second micro-nano bubble generator (202) through a pipeline; a spray chamber packing load layer (8) is further provided below the sprayer (7); the spray chamber packing load layer (8) is a square grid structure composed of titanium mesh; the grid length of the titanium mesh is 1 mm to 3 mm; the spray chamber packing load layer (8) is loaded with a packing material and / or a solid catalyst for catalytic ozonation; the material of the packing material is at least one of plastic, ceramic or gravel; the shape of the packing material is Pall ring, Raschig ring, conjugate ring, Intalox saddle ring or a combined ring composed of them; the solid catalyst for catalytic ozonation is a supported catalyst, and the supported catalyst includes a carrier material and a catalyst active component, and the catalyst active component is supported on the carrier material; the carrier material is zeolite, molecular sieve, Al 2 O 3 , SiO 2 or any one of SiC; the water absorption rate of the carrier material is 40% to 70%, and the particle size is 1 mm to 10 mm; the catalyst active ingredient is one or more of Fe, Mn, Ni, Co, Cu, Ce; a demister (9) is provided above the sprayer (7), and an ozone tail gas destroyer (10) is provided above the demister (9); the distance between the sprayer (7) and the demister (9) is 0.1 m to 0.5 m; the sprayer (7) is a circular nozzle provided with atomizing small holes; the diameter of the atomizing small holes is 1 mm to 5 mm, and the atomizing small holes are arranged in concentric circles, and the number of arranged circles is 2 to 5 circles; the demister (9) is a curved panel with holes.

6. The apparatus according to any one of claims 1 to 5, characterized in that, a tail gas discharge pipe (11) is further provided at the top of the spray chamber (5); the spray tower chamber is a cylinder with a diameter of 12 cm to 36 cm and a height of 1 m to 3 m; the bubbling chamber is a cube with a side length of 0.5 m to 1.5 m.

7. A method for treating VOC waste gas by using micro-nano bubble enhanced multi-phase advanced oxidation technology, characterized in that, the method is to treat VOC waste gas by using the apparatus according to any one of claims 1 to 6.

8. The method according to claim 7, characterized in that, it includes the following steps: S1. Introduce VOC waste gas and ozone into the first micro-nano bubble generator (201) to generate mixed gas micro-nano bubble water, and introduce it into the bubbling chamber (6); S2. Introduce ozone into the second micro-nano bubble generator (202) to generate ozone micro-nano bubble water, and introduce it into the spray chamber (5) and the bubbling chamber (6) respectively.

9. The method according to claim 8, characterized in that, In step S1, the inlet concentration of the VOC waste gas is 100 mg / m 3 ~3000 mg / m 3 , the inlet pressure ≤ 0.4 MPa; the residence time of the VOC waste gas in the reaction tower is 2 s to 20 s; the VOC waste gas contains light hydrocarbons; the light hydrocarbons are one or more of benzene, toluene, and xylene; the concentration of ozone is 20 mg / L to 200 mg / L; the inlet flow rate of ozone is 1 L / min to 3 L / min; the outlet flow rate of the mixed gas micro-nano bubble water in the bubbling chamber (6) is 10 L / min to 30 L / min.

10. The method according to claim 8 or 9, characterized in that, In step S2, the concentration of the ozone is 20 mg / L to 200 mg / L, the inlet gas flow rate of the ozone is 1 L / min to 3 L / min, and the outlet water flow rate of the ozone micro-nano bubble water in the bubbling chamber (6) is 10 L / min to 30 L / min; the liquid-gas ratio of the ozone micro-nano bubble water flowing out in the spray chamber (5) to the VOC waste gas is 6 to 12; the solution in the bubbling chamber (6) is updated every 20 to 30 days.

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