A method and system for treating dust and low concentration vocs containing exhaust gas

Abstract

The present application relates to volatile organic compounds treatment technical field, disclose a kind of method and system for treating dust and low concentration VOCs exhaust, wherein, the method comprises the following steps: (1) under the irradiation of ultraviolet, the exhaust to be treated is contacted with first oxidizing agent solution reversely, obtain first gas phase and waste liquid;(2) first gas phase is mixed with ozone, then the obtained mixed gas is irradiated using ultraviolet, obtain second gas phase;(3) under the irradiation of ultraviolet, second gas phase is contacted with second oxidizing agent solution reversely, the third gas phase obtained is carried out ozone decomposition reaction;First oxidizing agent solution and second oxidizing agent solution are same or different, and both contain peroxide.The method of the present application is based on the mechanism of photo-oxidation reaction, realizes the efficient treatment of dust and low concentration VOCs exhaust, simultaneously, in the process of removing VOCs, without using adsorption material and VOCs degradation catalyst, and the operation and maintenance cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of volatile organic compounds treatment, in particular to a method and system for treating dust-containing and low-concentration VOCs waste gas. BACKGROUND

[0002] With the development of economy, environmental pollution has affected the development and health of human beings. Among them, VOCs emission is one of the causes of air pollution. The current commonly used VOCs emission treatment technology mainly includes two methods: recovery method and destruction method. The recovery method is suitable for VOCs emission treatment with high concentration, and the purpose is to recover high-value substances and reduce environmental pollution. Common recovery methods include condensation method, absorption method, adsorption method and membrane separation method. For industrial waste gas with low VOCs concentration, the destruction method is used. Common VOCs destruction methods include regenerative thermal oxidation (RTO), catalytic combustion (RCO), biological degradation, low-temperature plasma method, photocatalytic oxidation method, advanced gas phase oxidation method, etc. Among them, RTO and RCO are commonly used VOCs treatment methods in industry.

[0003] However, for dust-containing and low-concentration VOCs industrial waste gas (<100ppm), it is difficult to use conventional methods for treatment. If regenerative thermal oxidation (RTO) is used, due to the low concentration of VOCs, a large amount of fuel gas is needed to maintain combustion, which consumes a large amount of energy and increases carbon emissions, which does not meet the future environmental management strategy of China. If catalytic oxidation combustion (RCO) is used, particles will adhere to the surface of the catalyst, causing the catalyst to be deactivated, and the overall device treatment efficiency will decrease. In addition, catalytic oxidation also needs to provide additional fuel gas to maintain the temperature of the catalytic bed.

[0004] From the above, it can be seen that dust-containing and low-concentration VOCs waste gas is a big problem in the field of VOCs treatment. Using conventional treatment methods will result in waste of a large amount of fuel gas, increase of carbon emissions, high-temperature treatment, and catalyst carbon deposition and deactivation, resulting in high operation and maintenance costs. Therefore, it is urgent to provide a new method for treating dust-containing and low-concentration VOCs waste gas. SUMMARY

[0005] The purpose of the present application is to overcome the problems of high energy consumption, easy production of other pollution, and high operation and maintenance costs in the treatment of dust-containing and low-concentration VOCs waste gas in the prior art, and to provide a method and system for treating dust-containing and low-concentration VOCs waste gas.

[0006] In order to achieve the above-mentioned purpose, one aspect of the present application provides a method for treating dust-containing and low-concentration VOCs waste gas, which comprises the following steps:

[0007] (1) under the irradiation of ultraviolet light, the waste gas to be treated is reversely contacted with a first oxidizing agent solution to obtain a first gas phase and a waste liquid;

[0008] (2) mixing the first gas phase with ozone, and then irradiating the resultant mixed gas with ultraviolet rays to obtain a second gas phase;

[0009] (3) contacting the second gas phase with a second oxidizing agent solution in a reverse direction under irradiation of ultraviolet rays, and performing an ozone decomposition reaction on the resultant third gas phase;

[0010] wherein the first oxidizing agent solution and the second oxidizing agent solution are the same or different, and both contain a peroxide.

[0011] Preferably, in the waste gas to be treated, the concentration of VOCs is 10 to 500 mg / m 3 , and the concentration of dust is 30 to 100 mg / m 3 .

[0012] Preferably, in step (1), the peroxide in the first oxidizing agent solution is selected from one or two or more of hydrogen peroxide, sodium persulfate, and potassium persulfate.

[0013] Preferably, in step (1), the concentration of the peroxide in the first oxidizing agent solution is 1 x 10 -3 to 20 x 10 -3 mol / L.

[0014] Preferably, in step (1), the wavelength of the ultraviolet rays is 160 to 320 nm.

[0015] Preferably, in step (2), the concentration of ozone in the mixed gas is 0.01 to 0.2 mol / m 3 .

[0016] Preferably, in step (2), the wavelength of the ultraviolet rays is 160 to 320 nm.

[0017] Preferably, in step (3), the peroxide in the second oxidizing agent solution is selected from one or two or more of hydrogen peroxide, sodium persulfate, and potassium persulfate.

[0018] Preferably, in step (3), the concentration of the peroxide in the second oxidizing agent solution is 1 x 10 -3 to 20 x 10 -3 mol / L.

[0019] Preferably, in step (3), the wavelength of the ultraviolet rays is 160 to 320 nm.

[0020] Preferably, in step (3), the ozone decomposition reaction is performed in the presence of a catalyst.

[0021] Preferably, the catalyst is manganese dioxide.

[0022] Preferably, in step (3), the temperature of the ozone decomposition reaction is 60-120℃.

[0023] Preferably, the method further comprises: subjecting the waste liquid obtained in step (1) to solid-liquid separation, and then using the obtained liquid phase to prepare the first oxidant solution and / or the second oxidant solution.

[0024] The second aspect of the present application provides a system for treating dust-containing and low-concentration VOCs waste gas, comprising: a liquid storage tank, a first spray tower, an ozone generator, a photo-oxidation device, a second spray tower, and an ozone removal device, wherein the first spray tower, the photo-oxidation device, and the second spray tower are each provided with an ultraviolet light generating device;

[0025] In the first spray tower, the waste gas to be treated and the oxidant solution from the liquid storage tank are subjected to reverse contact under ultraviolet irradiation to obtain a first gas phase and a waste liquid;

[0026] In the photo-oxidation device, the first gas phase from the first spray tower is mixed with ozone generated by the ozone generator to obtain a second gas phase;

[0027] In the second spray tower, the second gas phase from the photo-oxidation device and the oxidant solution from the liquid storage tank are subjected to reverse contact under ultraviolet irradiation to obtain a third gas phase;

[0028] The third gas phase from the second spray tower is subjected to an ozone removal reaction in the ozone removal device.

[0029] Preferably, the system further comprises a solid-liquid separator for removing solid phases in the waste liquid of the first spray tower and / or the second spray tower.

[0030] Preferably, the ultraviolet light generating device is an ultraviolet lamp.

[0031] Preferably, the first spray tower and the second spray tower are each provided with a gas distributor and a liquid distributor.

[0032] In the method of the present application, the waste gas to be treated is first subjected to reverse contact with a first oxidant solution to remove dust in the waste gas and to pre-treat VOCs under ultraviolet irradiation; then the obtained first gas phase is mixed with ozone to deeply remove VOCs under ultraviolet irradiation; followed by reverse contact with a second oxidant solution to deeply remove dust particles, and the obtained gas phase can be discharged after ozone decomposition reaction.

[0033] The method provided by the application is based on the mechanism of photo-oxidation reaction, combines liquid phase photo-oxidation reaction with gas phase photo-oxidation reaction, realizes efficient treatment of dust-containing and low-concentration VOCs waste gas, and simultaneously, in the process of removing VOCs, does not need to use adsorption materials, and due to the fact that no VOCs degradation catalyst is used, catalyst carbon deposition inactivation is avoided, so that the operation and maintenance cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a structural schematic diagram of one embodiment of the system for treating dust-containing and low-concentration VOCs waste gas provided by the application;

[0035] Figure 2 is a structural schematic diagram of another embodiment of the system for treating dust-containing and low-concentration VOCs waste gas provided by the application.

[0036] REFERENCE SIGNS

[0037] 1 first spray tower; 2 ozone generator; 3 photo-oxidation device; 4 second spray tower;

[0038] 5 liquid storage tank; 6 ozone remover; 7 solid-liquid separator; C1, C2, C3 and C4 are centrifugal pumps;

[0039] 51 first liquid storage tank; 52 second liquid storage tank; 71 first solid-liquid separator; 72 second solid-liquid separator. DETAILED DESCRIPTION

[0040] The specific embodiments of the application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the application, and are not intended to limit the application.

[0041] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be approximations that allow for significant variation. Various ranges of values that are provided are only meant to serve as examples. Other ranges of values can be easily determined without departing from the scope of the application.

[0042] The application provides a method for treating dust-containing and low-concentration VOCs waste gas, in one embodiment, the method comprises the following steps:

[0043] (1) under the irradiation of ultraviolet light, the waste gas to be treated is reversely contacted with a first oxidant solution, to obtain a first gas phase and a waste liquid;

[0044] (2) the first gas phase is mixed with ozone, and then the obtained mixed gas is irradiated with ultraviolet light, to obtain a second gas phase;

[0045] (3) under irradiation of ultraviolet light, the second gas phase is reversely contacted with a second oxidant solution, and a third gas phase obtained is subjected to an ozone decomposition reaction;

[0046] The method of the present application is suitable for industrial dust-containing, low-concentration organic gas treatment scenarios, such as silo tail gas, electronic special material production tail gas, electronic device production tail gas, etc.

[0047] In step (1) of the present application, a liquid phase photo-oxidation reaction is carried out. By reversely contacting the waste gas to be treated with a liquid phase (i.e. a first oxidant solution), dust in the waste gas can be removed; at the same time, by adding a peroxide to the liquid phase, under irradiation of ultraviolet light (UV) when the liquid phase is contacted with the waste gas, active molecules such as hydroxyl radicals can be generated in the liquid phase, and the active molecules react with VOCs, thereby removing the VOCs, so that pre-removal of VOCs is achieved.

[0048] It can be understood that the first gas phase contains water molecules. In step (1) of the present application, not only is removal of most of the dust and pre-removal of VOCs achieved, but also saturated water vapor is provided for the gas phase photo-oxidation reaction in step (2), thereby improving the treatment efficiency of VOCs.

[0049] In a specific embodiment, the concentration of VOCs in the waste gas to be treated is 10-500 mg / m 3 , and the concentration of dust is 30-100 mg / m 3 . It should be noted that VOCs include benzene series, organic chlorides, organic ketones, amines, alcohols, ethers, esters, acids and petroleum hydrocarbon compounds, etc. The waste gas generally contains multiple types of VOCs, but the content of most types is extremely low, making it difficult to measure or already meeting the emission requirements, so in this document, the concentration of VOCs is calculated based on the concentration of the main component.

[0050] In a preferred embodiment, in step (1), the peroxide in the first oxidant solution is selected from one or more of hydrogen peroxide, sodium persulfate and potassium persulfate.

[0051] In order to achieve better pre-removal of VOCs in the waste gas, in a preferred embodiment, in step (1), the concentration of the peroxide in the first oxidant solution is 1×10 -3 -20×10 -3 mol / L, preferably 2×10 -3 -10×10 -3 mol / L, specifically, for example, it can be 2×10 -3 mol / L, 3×10 -3 mol / L, 4×10-3 5x10 -3 6x10 -3 8x10 -3 10x10 -3 10x10

[0052] In a preferred embodiment, in step (1), the process of contacting the waste gas to be treated with the first oxidant solution in reverse comprises: in a first spray tower, the first oxidant solution (liquid phase) is sprayed from the top of the spray tower, the waste gas to be treated enters from the bottom of the spray tower, and a first gas phase and a waste liquid are obtained.

[0053] In order to enable the waste gas to be fully treated, in step (1), preferably, the volume ratio of the waste gas to be treated to the first oxidant solution is 50-200: 15-40, and specifically, for example, it can be 50:40, 50:30, 50:25, 50:15, 100:35, 100:25, 100:15, 200:25, 200:30 or 200:40.

[0054] In a preferred embodiment, in step (1), the wavelength of the ultraviolet light is 160-320 nm. It can be understood that the present application does not limit the specific wavelength of the ultraviolet light, as long as it is between 160-320 nm. The wavelength of the commercially available ultraviolet light lamp that meets this requirement is generally 185 nm or 254 nm, and in order to facilitate implementation, the wavelength of the ultraviolet light is preferably 185 nm or 254 nm.

[0055] In the method of the present application, step (2) is a gas phase photo-oxidation reaction. Specifically, in step (2), under UV irradiation, water molecules in the first gas phase produce active molecules such as hydroxyl radicals, and the active molecules oxidize VOCs, thereby deeply removing residual VOCs in the waste gas.

[0056] In the method of the present application, VOCs are removed based on the photo-oxidation reaction mechanism, without the use of adsorption materials and VOCs catalysts, and the operation and maintenance cost is low. Specifically, VOCs are degraded by active molecules such as hydroxyl radicals produced by peroxides under ultraviolet irradiation.

[0057] In specific implementation, step (2) comprises: mixing the first gas phase with ozone, passing the obtained mixed gas into a photo-oxidation device, and then irradiating the mixed gas with an ultraviolet lamp arranged in the photo-oxidation device to obtain a second gas phase.

[0058] In a preferred embodiment, the concentration of ozone in the mixed gas is 0.01-0.2 mol / m 3, preferably 0.01-0.1 mol / m 3 . That is, in the photo-oxidation device, the concentration of ozone is 0.01-0.2 mol / m 3 , preferably 0.01-0.1 mol / m 3 .

[0059] In a preferred embodiment, in step (2), the wavelength of the ultraviolet light is 160-320 nm. It can be understood that the present application does not limit the specific wavelength of the ultraviolet light, as long as it is between 160-320 nm. The wavelength of the commercially available ultraviolet light lamp that meets this requirement is generally 185 nm or 254 nm, and in order to facilitate implementation, the wavelength of the ultraviolet light is preferably 185 nm or 254 nm.

[0060] In the method of the present application, due to the incomplete degradation of VOCs in the photo-oxidation reactor, some polymers with hydrophilic properties are formed, and under the action of water vapor, micro-nano particles are formed, so the second gas phase obtained in step (2) also contains dust particles and VOCs. Through the operation of step (3) of reverse contacting the second gas phase with the second oxidizing agent solution under the irradiation of ultraviolet light, the dust particles and VOCs in the gas phase can be further removed, so that the content of dust and VOCs in the obtained gas phase meets the standard.

[0061] In a preferred embodiment, in step (3), the peroxide in the second oxidizing agent solution is selected from one or more of hydrogen peroxide, sodium persulfate and potassium persulfate.

[0062] In order to make the effect of pre-removal of VOCs in waste gas better, in a preferred embodiment, in step (3), the concentration of peroxide in the first oxidizing agent solution is 1×10 -3 -20×10 -3 mol / L, preferably 2×10 -3 -10×10 -3 mol / L, specifically, for example, it can be 2×10 -3 mol / L, 3×10 -3 mol / L, 4×10 -3 mol / L, 5×10 -3 mol / L, 6×10 -3 mol / L, 8×10 -3 mol / L or 10×10 -3 mol / L.

[0063] In a preferred embodiment, in step (3), the wavelength of the ultraviolet light is 160-320 nm. It can be understood that the present application does not limit the specific wavelength of the ultraviolet light, as long as it is between 160-320 nm. The wavelength of the commercially available ultraviolet light lamp that meets this requirement is generally 185 nm or 254 nm, and in order to facilitate implementation, the wavelength of the ultraviolet light is preferably 185 nm or 254 nm.

[0064] In a preferred embodiment, in step (3), the ozone decomposition reaction is carried out in the presence of a catalyst. Further preferably, the catalyst is manganese dioxide, and more preferably, it is a manganese dioxide honeycomb catalyst. It should be noted that although a catalyst is used here, it is used to treat the third gas phase after the dust particles and VOCs have been removed, so the catalyst is not easily deactivated by particles adhering to its surface during use. Therefore, the method of the present application can reduce the operation and maintenance costs.

[0065] In a preferred embodiment, in step (3), the temperature of the ozone decomposition reaction is 60-120℃, preferably 80-120℃, and specifically, for example, it can be 80℃, 90℃, 95℃, 100℃, 105℃, 110℃ or 120℃.

[0066] In order to reduce costs and reduce wastewater emissions, in a preferred embodiment, the method further comprises: subjecting the waste liquid obtained in step (1) to solid-liquid separation, and then using the obtained liquid phase to prepare the first oxidizing agent solution and / or the second oxidizing agent solution.

[0067] In a specific embodiment, the first oxidizing agent solution and the second oxidizing agent solution are the same. Further preferably, the first oxidizing agent solution and the second oxidizing agent solution are both aqueous solutions containing peroxides. In order to facilitate description, in this document, when the first oxidizing agent solution and the second oxidizing agent solution are the same, they are both referred to as oxidizing agent solution. Please refer to Figure 1When the first oxidant solution and the second oxidant solution are the same, in one embodiment, a system for implementing the method (i.e. a system for treating dust-containing and low-concentration VOCs waste gas) comprises: a first spray tower 1, an ozone generator 2, a photo-oxidation device 3, a second spray tower 4, a liquid storage tank 5, an ozone removal device 6, and ultraviolet light generating devices are arranged in the first spray tower 1, the photo-oxidation device 3 and the second spray tower 4; in the first spray tower 1, the waste gas to be treated and the oxidant solution from the liquid storage tank 5 are reversely contacted under ultraviolet irradiation to obtain a first gas phase and waste liquid; in the photo-oxidation device 3, the first gas phase from the first spray tower 1 is mixed with ozone generated by the ozone generator 2 to obtain a second gas phase; in the second spray tower 4, the second gas phase from the photo-oxidation device 3 and the oxidant solution from the liquid storage tank 5 are reversely contacted under ultraviolet irradiation to obtain a third gas phase; and the third gas phase from the second spray tower 4 is subjected to an ozone removal reaction in the ozone removal device 6.

[0068] In another specific embodiment, the first oxidant solution and the second oxidant solution are different. Please refer to Figure 2 When the first oxidant solution and the second oxidant solution are different, in another embodiment, a system for implementing the method (i.e. a system for treating dust-containing and low-concentration VOCs waste gas) comprises: a first spray tower 1, an ozone generator 2, a photo-oxidation device 3, a second spray tower 4, a liquid storage tank, and an ozone removal device 6, wherein the liquid storage tank is provided as two, i.e. a first liquid storage tank 51 and a second liquid storage tank 52; in the first spray tower 1, the waste gas to be treated and the first oxidant solution from the first liquid storage tank 51 are reversely contacted under ultraviolet irradiation to obtain a first gas phase and waste liquid; in the photo-oxidation device 3, the first gas phase from the first spray tower 1 is mixed with ozone generated by the ozone generator 2 to obtain a second gas phase; in the second spray tower 4, the second gas phase from the photo-oxidation device 3 and the second oxidant solution from the second liquid storage tank 52 are reversely contacted under ultraviolet irradiation to obtain a third gas phase; and the third gas phase from the second spray tower 4 is subjected to an ozone removal reaction in the ozone removal device 6.

[0069] In order to facilitate operation and recycling, the first oxidant solution and the second oxidant solution are preferably the same.

[0070] The application also provides a system for treating dust-containing and low-concentration VOCs waste gas, please refer to Figure 1In the embodiment, the system comprises a first spray tower 1, an ozone generator 2, a photo-oxidation device 3, a second spray tower 4, a liquid storage tank 5 and an ozone remover 6, and the first spray tower 1, the photo-oxidation device 3 and the second spray tower 4 are each provided with an ultraviolet light generating device (not shown in the figure);

[0071] In the first spray tower 1, the waste gas to be treated and the oxidant solution from the liquid storage tank 5 are subjected to reverse contact under ultraviolet irradiation to obtain a first gas phase and a waste liquid;

[0072] In the photo-oxidation device 3, the first gas phase from the first spray tower 1 is mixed with ozone generated by the ozone generator 2 to obtain a second gas phase;

[0073] In the second spray tower 4, the second gas phase from the photo-oxidation device 3 and the oxidant solution from the liquid storage tank 5 are subjected to reverse contact under ultraviolet irradiation to obtain a third gas phase;

[0074] The third gas phase from the second spray tower 4 is subjected to an ozone removal reaction in the ozone remover 6.

[0075] The system of the present application is suitable for industrial dust-containing and low-concentration organic gas treatment scenarios, such as silo tail gas, electronic special material production tail gas, electronic device production tail gas, etc.

[0076] In the system of the present application, the reverse contact is carried out in a spray tower, and the reverse contact is essentially spraying.

[0077] In a specific embodiment, the concentration of VOCs in the waste gas to be treated is 10-500 mg / m 3 , and the concentration of dust is 30-100 mg / m 3 .

[0078] In a preferred embodiment, the system further comprises a solid-liquid separator 7 for removing the solid phase in the waste liquid of the first spray tower 1 and / or the second spray tower 4, and then returning the obtained liquid phase to the liquid storage tank 5 for continuous use.

[0079] Further preferably, the solid-liquid separator 7 is a centrifugal solid-liquid separator 7, and the solid removal efficiency is 95-99%.

[0080] Further preferably, two solid-liquid separators are provided, which are a first solid-liquid separator 71 and a second solid-liquid separator 72, the inlet of the first solid-liquid separator 71 is connected with the waste liquid outlet of the first spray tower 1, the liquid phase outlet is connected with the inlet of the liquid storage tank 5, the inlet of the second solid-liquid separator 72 is connected with the waste liquid outlet of the second spray tower 4, and the liquid phase outlet is connected with the liquid storage tank 5.

[0081] In a preferred embodiment, the ultraviolet light generating device is an ultraviolet lamp.

[0082] In a preferred embodiment, both the first spray tower 1 and the second spray tower 4 are provided with a gas distributor (not shown in the figure) and a liquid distributor (not shown in the figure).

[0083] In a specific embodiment, the oxidizing agent solution contains peroxide, which can generate active molecules, such as hydroxyl radicals, in the liquid phase under the irradiation of UV, and the active molecules can react with VOCs to remove VOCs. Preferably, the oxidizing agent solution is an aqueous solution containing peroxide.

[0084] Further preferably, the peroxide is selected from one or more of hydrogen peroxide, sodium persulfate and potassium persulfate.

[0085] More preferably, the concentration of peroxide in the oxidizing agent solution is 1 x 10 -3 mol / L, preferably 2 x 10 -3 mol / L, more preferably 3 x 10 -3 mol / L, even more preferably 4 x 10 -3 mol / L, 5 x 10 -3 mol / L, 6 x 10 -3 mol / L, 8 x 10 -3 mol / L or 10 x 10 -3 mol / L. -3 -3 -3

[0086] In the system described in the present application, the first spray tower 1 and the second spray tower 4 can have the same or different structures. In a preferred embodiment, the first spray tower 1 and the second spray tower 4 have the same structural design. In a specific implementation, the exhaust gas enters the spray tower (including the first spray tower 1 and the second spray tower 4) from the bottom of the spray tower through the gas distributor, and the liquid phase is sprayed from the top of the spray tower through the liquid distributor. The gas phase (exhaust gas or second gas phase) and the liquid phase (oxidizing agent solution) are more fully contacted through the arrangement of the gas distributor and the liquid distributor.

[0087] In the system described in the present application, in the second spray tower 4, a third gas phase and a liquid phase are obtained, the liquid phase is transported from the bottom of the second spray tower 4 to the first spray tower 1 through the centrifugal pump C1, and the third gas phase is transported to the ozone remover 6.

[0088] ​​​In a preferred embodiment, the UV lamps in the first spray tower 1 and the second spray tower 4 are perpendicular to the gas phase direction, which facilitates replacement and can enhance the disturbance of the gas phase and the liquid phase (oxidant solution), thereby better removing dust.

[0089] In the photo-oxidation device 3, the lamp tube is arranged perpendicular to the gas phase direction, and under UV irradiation, water molecules in the gas phase generate active molecules such as hydroxyl radicals under the action of ozone, and the active molecules oxidize VOCs, thereby deeply removing VOCs in the gas phase. In a preferred embodiment, the concentration of ozone in the photo-oxidation device is 0.01-0.2 mol / m 3 , preferably 0.01-0.1 mol / m 3 .

[0090] In the system, the third gas phase is subjected to ozone removal treatment by the catalytic bed layer in the ozone removal device 6, wherein the temperature of the catalytic bed layer is set to 60-120°C, preferably 80-120°C. The catalyst is manganese dioxide, preferably manganese dioxide honeycomb catalyst.

[0091] In order to facilitate the delivery of the liquid phase, in a preferred embodiment, a centrifugal pump C1 is arranged between the liquid storage tank 5 and the first spray tower 1, a centrifugal pump C2 is arranged between the liquid storage tank 5 and the second spray tower 4, a centrifugal pump C3 is arranged between the first spray tower 1 and the first solid-liquid separator 71, and a centrifugal pump C4 is arranged between the second spray tower 4 and the solid-liquid separator 72.

[0092] When the first oxidant solution and the second oxidant solution are the same, in order to realize the recycling of the oxidant solution, in the system, the bottom outlet of the second spray tower 4 is connected to the top inlet of the first spray tower 1.

[0093] In the system, based on the photo-oxidation reaction mechanism, catalysts and adsorbent materials are not used, and the operation and maintenance cost is reduced; the liquid phase spray tower not only has a dust removal function, but also is provided with a UV generating device, which can simultaneously remove dust particles and VOCs; by combining the first spray tower 1, the photo-oxidation device 3, and the second spray tower 4, efficient treatment of dust-containing low-concentration VOCs waste gas is realized, and after the ozone removal device removes ozone, the gas that can meet the emission standard is obtained.

[0094] The application will be described in detail below through examples, but the protection scope of the application is not limited thereto.

[0095] As shown in Figure 1The system for treating dust-containing and low-concentration VOCs waste gas shown in the figure operates as follows: the system comprises a first spray tower 1, an ozone generator 2, a photo-oxidation device 3, a second spray tower 4, a liquid storage tank 5, an ozone remover 6, and a solid-liquid separator 7, and the first spray tower 1, the photo-oxidation device 3, and the second spray tower 4 are each provided with an ultraviolet light generating device; wherein the oxidant solution in the liquid storage tank 5 is delivered to the top of the first spray tower 1 by a centrifugal pump C1 and to the top of the second spray tower 4 by a centrifugal pump C2.

[0096] Example 1

[0097] The main components of the waste gas: the concentration of dust in the waste gas is 50 mg / m 3 , and the VOCs contain 10 mg / m 3 of benzene;

[0098] The oxidant solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 10×10 -3 mol / L;

[0099] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through a gas distributor, and the oxidant solution is sprayed downward from the top of the first spray tower 1 through a liquid distributor, to obtain waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 40 m 3 / h;

[0100] (2) After the first gas phase is combined with the ozone generated by the ozone generator 2, the obtained mixed gas is delivered to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm to obtain a second gas phase, and the power of the ozone generator 2 is adjusted so that the concentration of ozone in the photo-oxidation reactor reaches 0.06 mol / m 3 ;

[0101] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through a gas distributor, and the oxidant solution is sprayed downward from the top of the second spray tower 4 through a liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 40 m 3 / h;

[0102] (4) The third gas phase is delivered to the ozone remover 6 for treatment, and the temperature of the catalytic bed is set to 120℃, and the catalyst is manganese dioxide honeycomb catalyst.

[0103] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.01 mg / m 3, the concentration of benzene is less than or equal to 0.9 mg / m 3 , no ozone is detected.

[0104] Example 2

[0105] Main components of the waste gas: the concentration of dust in the waste gas is 50 mg / m 3 , VOCs mainly contain formaldehyde 100 mg / m 3 ;

[0106] The oxidizing agent solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 4x10 -3 mol / L;

[0107] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the first spray tower 1 through the liquid distributor, to obtain waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidizing agent solution is 40 m 3 / h;

[0108] (2) After the first gas phase is combined with the ozone generated by the ozone generator 2, the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm, to obtain a second gas phase. Adjust the power of the ozone generator 2 so that the concentration of ozone in the photo-oxidation reactor reaches 0.05 mol / m 3 ;

[0109] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the second spray tower 4 through the liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidizing agent solution is 40 m 3 / h;

[0110] (4) The third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed layer is set to 100°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0111] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.01 mg / m 3 , no formaldehyde and ozone are detected.

[0112] Example 3

[0113] Main components of the waste gas: the concentration of dust in the waste gas is 50 mg / m 3 , VOCs contain benzene 10 mg / m 3 ;

[0114] wherein the oxidant solution is an aqueous hydrogen peroxide solution, and the concentration of hydrogen peroxide is 8 x 10 -3 mol / L;

[0115] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through a gas distributor, and the oxidant solution is sprayed downward from the top of the first spray tower 1 through a liquid distributor, to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 15 m 3 / h;

[0116] (2) The first gas phase is combined with the ozone generated by the ozone generator 2, and the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm to obtain a second gas phase. The power of the ozone generator 2 is adjusted so that the concentration of ozone in the photo-oxidation reactor reaches 0.06 mol / m 3 ;

[0117] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through a gas distributor, and the oxidant solution is sprayed downward from the top of the second spray tower 4 through a liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 15 m 3 / h;

[0118] (4) The third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed layer is set to 100°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0119] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.4 mg / m 3 , the concentration of benzene is less than or equal to 1.3 mg / m 3 , and no ozone is detected.

[0120] Example 4

[0121] The main components of the waste gas are: the concentration of dust in the waste gas is 50 mg / m 3 , and the VOCs contain 10 mg / m 3 of benzene;

[0122] wherein the oxidant solution is an aqueous hydrogen peroxide solution, and the concentration of hydrogen peroxide is 2 x 10 -3 mol / L;

[0123] (1) under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through a gas distributor, and the oxidant solution sprays downward from the top of the first spray tower 1 through a liquid distributor, to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 25 m 3 / h;

[0124] (2) the first gas phase is combined with the ozone generated by the ozone generator 2, and the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated by ultraviolet light with a wavelength of 185 nm, to obtain a second gas phase, and the power of the ozone generator 2 is adjusted to make the concentration of ozone in the photo-oxidation reactor reach 0.02 mol / m 3 ;

[0125] (3) under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through a gas distributor, and the oxidant solution sprays downward from the top of the second spray tower 4 through a liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 25 m 3 / h;

[0126] (4) the third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed layer is 100℃, and the catalyst is manganese dioxide honeycomb catalyst.

[0127] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.1 mg / m 3 , the concentration of benzene is less than or equal to 3.8 mg / m 3 , and no ozone is detected.

[0128] Example 5

[0129] The main components of the waste gas are: the concentration of dust in the waste gas is 50 mg / m 3 , and the VOCs contain 10 mg / m 3 of benzene;

[0130] The oxidant solution is an aqueous solution of sodium persulfate, and the concentration of sodium persulfate is 3×10 -3 mol / L;

[0131] (1) under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through a gas distributor, and the oxidant solution sprays downward from the top of the first spray tower 1 through a liquid distributor, to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 30 m 3 / h;

[0132] (2) The first gas phase is combined with ozone generated by the ozone generator 2, and the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm to obtain a second gas phase. The power of the ozone generator 2 is adjusted so that the concentration of ozone in the photo-oxidation reactor reaches 0.05 mol / m 3 ;

[0133] (3) The second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 under the irradiation of ultraviolet light with a wavelength of 185 nm, and the oxidant solution is sprayed downward from the top of the second spray tower 4 through the liquid distributor to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 30 m 3 / h;

[0134] (4) The third gas phase is transported to the ozone removal device 6 for treatment, and the temperature of the catalytic bed is set to 60°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0135] The gas at the outlet of the ozone removal device 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.08 mg / m 3 , the concentration of benzene is less than or equal to 2.4 mg / m 3 , and no ozone is detected.

[0136] Example 6

[0137] The main components of the waste gas are: the concentration of dust in the waste gas is 50 mg / m 3 , and VOCs mainly contain formaldehyde 100 mg / m 3 ;

[0138] The oxidant solution is an aqueous solution of sodium persulfate, and the concentration of sodium persulfate is 6×10 -3 mol / L;

[0139] (1) The waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 under the irradiation of ultraviolet light with a wavelength of 185 nm, and the oxidant solution is sprayed downward from the top of the first spray tower 1 through the liquid distributor to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 25 m 3 / h;

[0140] (2) The first gas phase is combined with ozone generated by the ozone generator 2, and the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm to obtain a second gas phase. The power of the ozone generator 2 is adjusted so that the concentration of ozone in the photo-oxidation reactor reaches 0.01 mol / m3 ;

[0141] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through a gas distributor, and the oxidant solution sprays downward from the top of the second spray tower 4 through a liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 25 m 3 / h;

[0142] (4) The third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed is set to 100℃, and the catalyst is manganese dioxide honeycomb catalyst.

[0143] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.1 mg / m 3 , and no formaldehyde and ozone are detected.

[0144] Example 7

[0145] The main components of the waste gas are that the dust concentration in the waste gas is 50 mg / m 3 , and the VOCs mainly contain cyclohexane 50 mg / m 3 ;

[0146] The oxidant solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 5×10 -3 mol / L;

[0147] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through a gas distributor, and the oxidant solution sprays downward from the top of the first spray tower 1 through a liquid distributor, to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 30 m 3 / h;

[0148] (2) After the first gas phase is combined with the ozone generated by the ozone generator 2, the mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated by ultraviolet light with a wavelength of 185 nm to obtain a second gas phase, and the power of the ozone generator 2 is adjusted so that the concentration of ozone in the photo-oxidation reactor reaches 0.05 mol / m 3 ;

[0149] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through a gas distributor, and the oxidant solution sprays downward from the top of the second spray tower 4 through a liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 30 m 3 / h;

[0150] (4) The third gas phase is transported to the ozone remover 6 for treatment, the temperature of the catalytic bed is set to 100°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0151] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.08 mg / m 3 , the concentration of cyclohexane is less than or equal to 5.1 mg / m 3 , and no ozone is detected.

[0152] Example 8

[0153] The main components of the waste gas are: the concentration of dust in the waste gas is 50 mg / m 3 , the VOCs contain 10 mg / m 3 of benzene;

[0154] The oxidizing agent solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 4×10 -3 mol / L;

[0155] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the first spray tower 1 through the liquid distributor, to obtain waste liquid and a first gas phase, wherein the flow rate of the waste gas is 200 m 3 / h, and the flow rate of the oxidizing agent solution is 25 m 3 / h;

[0156] (2) The first gas phase is combined with the ozone generated by the ozone generator 2, and the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm, to obtain a second gas phase. Adjust the power of the ozone generator 2 so that the concentration of ozone in the photo-oxidation reactor reaches 0.05 mol / m 3 ;

[0157] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the second spray tower 4 through the liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidizing agent solution is 25 m 3 / h;

[0158] (4) The third gas phase is transported to the ozone remover 6 for treatment, the temperature of the catalytic bed is set to 100°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0159] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.23 mg / m3 , the concentration of benzene is less than or equal to 3.2 mg / m 3 , the concentration of ozone is less than or equal to 0.015 mol / m 3 .

[0160] Example 9

[0161] The main components of the exhaust gas: the concentration of dust in the exhaust gas is 50 mg / m 3 , VOCs mainly contain formaldehyde 100 mg / m 3 ;

[0162] The oxidizing agent solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 10 x 10 -3 mol / L;

[0163] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the exhaust gas enters the first spray tower 1 from the bottom of the first spray tower 1 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the first spray tower 1 through the liquid distributor, to obtain the exhaust liquid and the first gas phase, wherein the flow rate of the exhaust gas is 200 m 3 / h, and the flow rate of the oxidizing agent solution is 30 m 3 / h;

[0164] (2) After the first gas phase is combined with the ozone generated by the ozone generator 2, the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated using ultraviolet light with a wavelength of 185 nm, to obtain the second gas phase. Adjust the power of the ozone generator 2 so that the concentration of ozone in the photo-oxidation reactor reaches 0.05 mol / m 3 ;

[0165] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the second spray tower 4 through the liquid distributor, to obtain the third gas phase and the liquid phase, wherein the flow rate of the oxidizing agent solution is 30 m 3 / h;

[0166] (4) The third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed layer is set to 120°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0167] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.1 mg / m 3 , formaldehyde is not detected in the exhaust gas, and the concentration of ozone is less than or equal to 0.01 mol / m 3 .

[0168] Example 10

[0169] The main components of the waste gas: the concentration of dust in the waste gas is 50 mg / m 3 , and VOCs mainly contain formaldehyde 100 mg / m 3 ;

[0170] The oxidizing agent solution is an aqueous hydrogen peroxide solution, and the concentration of hydrogen peroxide is 6×10 -3 mol / L;

[0171] (1) Under the irradiation of ultraviolet light with a wavelength of 254 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the first spray tower 1 through the liquid distributor, to obtain waste liquid and a first gas phase, wherein the flow rate of the waste gas is 200 m 3 / h, and the flow rate of the oxidizing agent solution is 25 m 3 / h;

[0172] (2) After the first gas phase is combined with the ozone generated by the ozone generator 2, the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 254 nm to obtain a second gas phase. Adjust the power of the ozone generator 2 so that the concentration of ozone in the photo-oxidation reactor reaches 0.02 mol / m 3 ;

[0173] (3) Under the irradiation of ultraviolet light with a wavelength of 254 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through the gas distributor, and the oxidizing agent solution is sprayed downward from the top of the second spray tower 4 through the liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidizing agent solution is 40 m 3 / h;

[0174] (4) The third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed layer is set to 120°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0175] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.16 mg / m 3 , the concentration of benzene is less than or equal to 3.2 mg / m 3 , and no ozone is detected.

[0176] Comparative Example 1

[0177] According to the method described in Example 1, except that the oxidizing agent solution (aqueous potassium persulfate solution) is replaced with water.

[0178] Specifically, the main components of the waste gas: the concentration of dust in the waste gas is 50 mg / m 3 , and VOCs contain benzene 10 mg / m 3 ;

[0179] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas from the bottom of the first spray tower 1 enters the first spray tower 1 through a gas distributor, and water from above the first spray tower 1 is sprayed downward through a liquid distributor, to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the water is 40 m 3 / h;

[0180] (2) The first gas phase is combined with ozone generated by the ozone generator 2, and the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm to obtain a second gas phase. The power of the ozone generator 2 is adjusted so that the concentration of ozone in the photo-oxidation reactor reaches 0.06 mol / m 3 ;

[0181] (3) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase from the bottom of the second spray tower 4 enters the second spray tower 4 through a gas distributor, and water from above the second spray tower 4 is sprayed downward through a liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the water is 40 m 3 / h;

[0182] (4) The third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed layer is set to 120°C, and the catalyst is manganese dioxide honeycomb catalyst.

[0183] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.05 mg / m 3 , the concentration of benzene is less than or equal to 5.5 mg / m 3 , and no ozone is detected.

[0184] Comparative Example 2

[0185] According to the method described in Example 1, except that no ozone is introduced.

[0186] Specifically, the main components of the waste gas are: the concentration of dust in the waste gas is 50 mg / m 3 , and the VOCs contain 10 mg / m 3 of benzene;

[0187] The oxidizing agent solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 10×10 -3 mol / L;

[0188] (1) under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas enters the first spray tower 1 from the bottom of the first spray tower 1 through a gas distributor, and the oxidant solution is sprayed downward from the top of the first spray tower 1 through a liquid distributor, to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 40 m 3 / h;

[0189] (2) the first gas phase is transported to the photo-oxidation device 3, and is irradiated with ultraviolet light with a wavelength of 185 nm, to obtain a second gas phase;

[0190] (3) under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase enters the second spray tower 4 from the bottom of the second spray tower 4 through a gas distributor, and the oxidant solution is sprayed downward from the top of the second spray tower 4 through a liquid distributor, to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 40 m 3 / h;

[0191] (4) the third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed layer is set to 120℃, and the catalyst is a manganese dioxide honeycomb catalyst.

[0192] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 0.05 mg / m 3 , the concentration of benzene is less than or equal to 6.4 mg / m 3 , and no ozone is detected.

[0193] Comparative Example 3

[0194] The method described in Example 1 is implemented, except that no treatment is performed in the first spray tower 1, that is, step (1) is not performed.

[0195] The main components of the waste gas are: the concentration of dust in the waste gas is 50 mg / m 3 , and the VOCs contain 10 mg / m 3 of benzene;

[0196] The oxidant solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 10×10 -3 mol / L;

[0197] (1) the waste gas to be treated is combined with the ozone generated by the ozone generator 2, and the obtained mixed gas is transported to the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm, to obtain a second gas phase, and the power of the ozone generator 2 is adjusted, so that the concentration of ozone in the photo-oxidation reactor reaches 0.06 mol / m 3 , and the flow rate of the waste gas is 50 m 3 / h;

[0198] (2) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the second gas phase passes through a gas distributor from the bottom of the second spray tower 4 into the second spray tower 4, and the oxidant solution is sprayed downward from the top of the second spray tower 4 through a liquid distributor to obtain a third gas phase and a liquid phase, wherein the flow rate of the oxidant solution is 40 m 3 / h;

[0199] (3) The third gas phase is transported to the ozone remover 6 for treatment, and the temperature of the catalytic bed is set to 120℃, and the catalyst is manganese dioxide honeycomb catalyst.

[0200] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 8.3 mg / m 3 , the concentration of benzene is less than or equal to 7.8 mg / m 3 , and no ozone is detected.

[0201] Comparative Example 4

[0202] The method described in Example 1 is implemented, except that no treatment is performed in the second spray tower 4, i.e., step (3) is not performed.

[0203] The main components of the waste gas are: the concentration of dust in the waste gas is 50 mg / m 3 , and the VOCs contain 10 mg / m 3 of benzene;

[0204] The oxidant solution is an aqueous solution of potassium persulfate, and the concentration of potassium persulfate is 10 x 10 -3 mol / L

[0205] (1) Under the irradiation of ultraviolet light with a wavelength of 185 nm, the waste gas passes through a gas distributor from the bottom of the first spray tower 1 into the first spray tower 1, and the oxidant solution is sprayed downward from the top of the first spray tower 1 through a liquid distributor to obtain a waste liquid and a first gas phase, wherein the flow rate of the waste gas is 50 m 3 / h, and the flow rate of the oxidant solution is 40 m 3 / h;

[0206] (2) The first gas phase is combined with the ozone generated by the ozone generator 2, and the obtained mixed gas is transported into the photo-oxidation device 3, and the mixed gas is irradiated with ultraviolet light with a wavelength of 185 nm to obtain a second gas phase, and the power of the ozone generator 2 is adjusted so that the concentration of ozone in the photo-oxidation reactor reaches 0.06 mol / m 3 ;

[0207] (3) The second gas phase is transported to the ozone remover 6 for treatment, the temperature of the catalytic bed is set to 120℃, and the catalyst is manganese dioxide honeycomb catalyst.

[0208] The gas at the outlet of the ozone remover 6 is detected, and the results show that the dust concentration of the treated gas is less than or equal to 11.2 mg / m 3 , the benzene concentration is less than or equal to 6.7 mg / m 3 , and no ozone is detected.

[0209] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application, and all fall within the protection scope of the present application.

Claims

1. A method of treating dust-laden and low concentration VOCs off-gas, characterized by, The method comprises the following steps: (1) under the irradiation of ultraviolet rays, the waste gas to be treated is contacted with a first oxidant solution in a reverse direction to obtain a first gas phase and a waste liquid; (2) the first gas phase is mixed with ozone, and then the obtained mixed gas is irradiated with ultraviolet rays to obtain a second gas phase; (3) under the irradiation of ultraviolet rays, the second gas phase is contacted with a second oxidant solution in a reverse direction, and a third gas phase obtained is subjected to an ozone decomposition reaction; The first oxidizing agent solution and the second oxidizing agent solution are the same or different, and both contain peroxide; the concentration of VOCs in the waste gas to be treated is 10-500 mg / m 3 , and the concentration of dust is 30-100 mg / m 3 . In step (2), the concentration of ozone in the mixed gas is 0.01 to 0.2 mol / m 3 ; The system for implementing the method comprises a first spray tower (1), an ozone generator (2), a photo-oxidation device (3), a second spray tower (4), a liquid storage tank (5) and an ozone remover (6), and ultraviolet ray generating devices are arranged in the first spray tower (1), the photo-oxidation device (3) and the second spray tower (4); In the first spray tower (1), the waste gas to be treated and the oxidant solution from the liquid storage tank (5) are contacted in a reverse direction under the irradiation of ultraviolet rays to obtain a first gas phase and a waste liquid; In the photo-oxidation device (3), the first gas phase from the first spray tower (1) is mixed with ozone generated by the ozone generator (2) to obtain a second gas phase; In the second spray tower (4), the second gas phase from the photo-oxidation device (3) and the oxidant solution from the liquid storage tank (5) are contacted in a reverse direction under the irradiation of ultraviolet rays to obtain a third gas phase; The third gas phase from the second spray tower (4) is subjected to an ozone removal reaction in the ozone remover (6).

2. The method of claim 1, wherein, In step (1), the peroxide in the first oxidant solution is selected from one or more than two of hydrogen peroxide, sodium persulfate and potassium persulfate.

3. The method of claim 1, wherein, In step (1), the concentration of peroxide in the first oxidizing agent solution is 1 x 10 -3 -20 x 10 -3 mol / L.

4. The method of claim 1, wherein, In step (1), the wavelength of the ultraviolet rays is 160-320 nm.

5. The method according to any one of claims 1 to 3, characterized in that, In step (2), the wavelength of the ultraviolet rays is 160-320 nm.

6. The method of claim 1, wherein, In step (3), the peroxide in the second oxidant solution is selected from one or more than two of hydrogen peroxide, sodium persulfate and potassium persulfate.

7. The method of claim 1, wherein, In step (3), the concentration of peroxide in the second oxidizing agent solution is 1 x 10 -3 -20 x 10 -3 mol / L.

8. The method of claim 1, wherein, In step (3), the wavelength of the ultraviolet rays is 160-320 nm.

9. The method of claim 1, wherein, In step (3), the ozone decomposition reaction is carried out in the presence of a catalyst.

10. The method of claim 9, wherein, The catalyst is manganese dioxide.

11. The method of claim 1 or 9, wherein, In step (3), the temperature of the ozone decomposition reaction is 60-120 ℃.

12. The method of claim 1, wherein, The method further comprises subjecting the waste liquid obtained in step (1) to solid-liquid separation, and then using the obtained liquid phase to prepare the first oxidant solution and / or the second oxidant solution.

13. The method of claim 1, wherein, The system further comprises a solid-liquid separator (7) for removing the solid phase in the waste liquid of the first spray tower (1) and / or the second spray tower (4).

14. The method of claim 1, wherein, The ultraviolet ray generating device is an ultraviolet lamp.

15. The method of claim 1, wherein, The first spray tower (1) and the second spray tower (4) are each provided with a gas distributor and a liquid distributor.

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