A VOCs gas treatment device based on electrochemical technology

Abstract

The application discloses a VOCs gas treatment device based on an electrochemical technology, which comprises a tower type reaction cavity, and an electric Fenton reaction zone and an electric catalysis reaction zone are sequentially arranged in the tower type reaction cavity from top to bottom along the longitudinal direction; the electric Fenton reaction zone is provided with a plurality of groups of electric Fenton units which are arranged in a staggered mode, each group of electric Fenton units sequentially comprises an anode, an activated carbon layer, a carbon felt layer and a cathode from top to bottom; the electric catalysis reaction zone is provided with a plurality of groups of electric catalysis units which are arranged in a staggered mode, each group of electric catalysis units sequentially comprises an anode, a cathode and an anode from top to bottom; and overflow weirs and downcomers are arranged at the top and bottom of the ports of each electric Fenton unit and each electric catalysis unit. By changing the tower tray aperture and the overflow weir height, the electrolyte and the VOCs gas residence time in the electric Fenton reaction zone is prolonged, the electrochemical reaction efficiency is enhanced, and the VOCs removal efficiency is improved.

Description

Technical Field

[0001] This invention relates to a VOCs gas treatment device based on electrochemical technology. Background Technology

[0002] Volatile organic compounds (VOCs) are a class of volatile substances that can participate in photochemical reactions in the atmosphere to form organic compounds, such as common hydrocarbons, oxygenated organic compounds, and carbonaceous organic compounds. The generation of VOCs leads to environmental problems such as photochemical smog and haze; in addition, because VOCs are toxic, they can also harm human health.

[0003] Existing VOCs waste gas treatment technologies include adsorption, absorption, condensation, photocatalysis, low-temperature plasma, combustion, and biological methods. Compared with other VOCs treatment technologies, adsorption has advantages such as high removal rate, simple equipment, and reusable adsorbents. However, adsorption requires a large area and cannot be used if the concentration of organic waste gas is high and the conditions are high humidity and temperature. Absorption processes are complex, require large amounts of absorbent and secondary treatment, and the absorbent is easily miscible with other organic solvents. Combustion requires high temperatures and can only treat small volumes of waste gas, which is inconsistent with current low-carbon trends. Photocatalytic oxidation has strict requirements for materials and reaction conditions and is prone to catalyst deactivation. Low-temperature plasma treatment has limitations in decomposing benzene compounds and requires a high electric field strength. Currently, most VOCs treatment technologies suffer from high equipment requirements, high investment costs, and strict operating conditions. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a VOCs gas treatment device based on electrochemical technology. This device treats VOCs gas by combining electro-Fenton and electrocatalysis, which effectively improves the treatment effect of VOCs gas.

[0005] Technical Solution: The VOCs gas treatment device based on electrochemical technology of the present invention includes a tower-type reaction chamber. Along its longitudinal direction, the tower-type reaction chamber contains, from top to bottom, an electro-Fenton reaction zone and an electrocatalytic reaction zone. The electro-Fenton reaction zone contains multiple sets of staggered electro-Fenton units, each set consisting of, from top to bottom, an anode, an activated carbon layer, a carbon felt layer, and a cathode. The electrocatalytic reaction zone contains multiple sets of staggered electrocatalytic units, each set consisting of, from top to bottom, an anode, a cathode, and an anode. Each electro-Fenton unit and each electrocatalytic unit is arc-shaped, with the arc-shaped side fitting and fixedly connected to the inner wall of the reaction chamber. An upward-extending overflow weir and a downcomer extending in the opposite direction to the overflow weir are located at the port away from the inner wall of the reaction chamber.

[0006] The overflow weir maintains a certain height of liquid layer on the tray and makes the liquid flow uniformly on the tray, ensuring that the gas and liquid phases form sufficient interphase mass transfer surface on the tray; the overflow method in the processing device of this invention adopts single overflow, and the liquid flow path is relatively long, which is conducive to the residence of electrolyte.

[0007] The tower-type reaction chamber further includes a liquid outlet and a gas inlet at the bottom of the reaction chamber, and a liquid inlet and a gas outlet at the top of the reaction chamber. The electrolyte flows out from the liquid outlet at the bottom of the reaction chamber and is circulated to the liquid inlet at the top of the reaction chamber by a circulating pump. The gas enters from the gas inlet at the bottom of the reaction chamber, and from bottom to top, it first passes through the electrocatalytic reaction zone for reaction, then passes through the electro-Fenton reaction zone for oxidation-reduction reaction, and finally exits from the gas outlet at the top of the reaction chamber.

[0008] The liquid inlet is equipped with a spray head, through which the electrolyte is sprayed onto the uppermost electro-Fenton unit. (The spray head ensures that the electrolyte flows down the tray evenly.)

[0009] In the electric Fenton unit, the anode is an iron perforated plate (iron tower plate), the cathode is a stainless steel perforated plate or a TiO2 perforated plate, and the distance between the anode and cathode is 65-100mm.

[0010] The activated carbon layer has a filling thickness of 55–85 mm, and the activated carbon is in the form of spherical or cylindrical particles with a particle size of 1–5 mm; the carbon felt layer has a filling thickness of 10–15 mm; and the spacing between each electric Fenton unit is 90–110 mm. Each electric Fenton unit forms a baffle channel.

[0011] In the electrocatalytic unit, the upper and lower anodes are Sb-SnO2 perforated plates, synthetic boron-doped diamond thin-layer BDD perforated plates, or Ti / SnO2 perforated plates; the cathode is a stainless steel perforated plate; the distance between the upper and lower anodes and the cathode is 2–5 mm; the distance between each electrocatalytic unit is 90–110 mm. Each electrocatalytic unit forms a baffle channel.

[0012] The inner diameter of the tower-type reaction chamber is 80-100cm, and the height of the reaction chamber is 2-3m.

[0013] In the electro-Fenton unit and the electro-catalytic unit, the orifice plates (plates) selected for the cathode and anode are actually electrode plates, and the outer diameter of the plate (circular) is 70-90% of the inner diameter of the reaction chamber.

[0014] The electro-Fenton reaction zone consists of 6-8 electro-Fenton units, with an opening ratio of 25-30% and a pore size of 2-4 mm on each tray. The overflow weir at the end of each electro-Fenton unit has a height of 60-80 mm. In the electro-Fenton reaction zone, multiple sets of electro-Fenton units are first set up to achieve multiple series reactions, thus extending the residence time of electrolytes and gases in the electro-Fenton units. Then, the height of the overflow weir in the electro-Fenton units is increased to maintain a certain liquid layer height on the tray, further increasing the residence time of the electrolyte in the electro-Fenton units. Secondly, through... Increasing the packing thickness of porous materials (carbon fiber felt and activated carbon particles) in the electric Fenton unit, reducing the pore size of the electric Fenton unit trays, and decreasing the size of the activated carbon particles in the electric Fenton unit all increase the residence time of VOCs gas in the electric Fenton unit. At the same time, the electrolyte liquid layer maintained by the overflow weir hinders gas flow, further increasing the residence time of VOCs gas in the electric Fenton unit. The residence time of VOCs gas in the electric Fenton reaction zone can reach 2-3 minutes, and the residence time of electrolyte in the electric Fenton reaction zone is 6-10 minutes.

[0015] In the electrocatalytic reaction zone, there are 2 to 4 electrocatalytic units, with an opening rate of 45 to 60% on each tray, a pore size of 8 to 10 mm, and an overflow weir height of 10 to 20 mm at the end of each electrocatalytic unit.

[0016] The electrolyte is a mixture of sodium sulfate and sodium chloride solutions, and its composition is: n(SO4) 2- ): n(Cl - The ratio of electrolyte to electrolyte is 5-10:1. A small amount of chloride ions in the electrolyte will generate active chlorine, which can oxidize organic matter and promote the formation of redox reactions. The pH of the electrolyte entering the tower is adjusted to 1-3. The electro-Fenton reaction requires acidic conditions to facilitate the formation of hydroxyl groups.

[0017] After passing through the electro-Fenton reaction zone, the electrolyte pH value is 5-6 (hydrogen ions are consumed to generate hydrogen peroxide during the electro-Fenton reaction, and the consumption of hydrogen ions leads to an increase in pH value). At this time, the electrolyte enters the electrocatalytic reaction zone. After passing through the electrocatalytic reaction zone, the electrolyte exiting the tower has a pH value of 6-7.

[0018] A longer gas-liquid residence time is achieved by adjusting the number of electro-Fenton units in the upper part of the tower, the porosity and pore size of the trays, the overflow weir, the size of the activated carbon particles, and the thickness of the carbon felt layer. This maximizes the generation of hydroxyl radicals and thus the electro-Fenton reaction. Specifically, the smaller pore size of the trays and the height of the overflow weir increase the residence time of the electrolyte and VOCs on the trays, facilitating the full generation of the electro-Fenton reaction in the electro-Fenton section. This produces more hydroxyl radicals that mix with VOCs, oxidizing and degrading the organic matter in the VOCs gas, achieving efficient removal of pollutants. A shorter gas-liquid residence time is achieved by adjusting the number of electrocatalytic units in the lower part of the tower, the porosity and pore size of the trays, and the size of the overflow weir and downcomer. Therefore, the electrocatalytic reaction is rapid, requiring a shorter residence time. Electrolytes are sprayed down from the top of the tower via spray heads, first passing through the electro-Fenton reaction zone, then entering the electro-catalytic reaction zone, and then flowing out from the bottom outlet of the tower. After passing through the circulation pump, the electrolyte pH value is adjusted to 1-3 at the inlet, realizing electrolyte recycling. VOCs gas enters from the bottom and exits from the top. The gas first passes through the electro-catalytic reaction zone in the lower half of the tower, then through the electro-Fenton reaction zone in the upper half of the tower, and is discharged from the gas outlet at the top of the tower after the reaction.

[0019] The electrolyte flows from top to bottom. VOCs are directly oxidized and degraded into small-molecule organic compounds at the anode of the electrocatalytic section. Simultaneously, water is decomposed to form hydroxyl radicals and reactive oxygen species. VOCs react with these radicals and reactive oxygen species to be mineralized into small-molecule H2O and CO2 (a small portion of VOCs undergoes mineralization at this stage; the vast majority are degraded into small-molecule organic compounds in the first reaction). After flowing to the bottom of the column, the electrolyte is circulated back to the top via a circulation pump. At the top, the pH is adjusted to 1–3. The upper part of the column contains the electro-Fenton reaction zone: the electrolyte at pH 1–3 contains a large amount of H+. + During the electro-Fenton reaction, H + At the cathode, oxygen (mostly from VOCs gases, with a small portion from the electrolyte solution) undergoes a two-electron reduction reaction to generate H₂O₂. The carbon felt layer, with its large specific surface area and numerous mesopores, is particularly conducive to H₂O₂ production, resulting in a higher concentration of H₂O₂. Fe₂ is generated from the oxidation of the iron surface at the anode. 2+ H2O2 rapidly reacts with Fe 2+ The reaction generates hydroxyl radicals, which further react with the gas that has passed through the electrocatalytic stage to oxidize the organic matter therein. In the electro-Fenton section, the higher the efficiency of the electro-Fenton reaction from bottom to top, the higher the efficiency of hydroxyl radical generation. The treated gas is discharged through the gas outlet at the top of the tower.

[0020] This invention treats VOCs gases by combining electro-Fenton and electrocatalytic reactions. The electrolyte passes through two reaction zones within the tower from top to bottom. The reaction rate is optimized by controlling the residence time (gas-liquid contact reaction time) of the gas and liquid in the two reaction zones, thereby promoting the VOCs treatment effect. Simultaneously, controlling the residence time allows for the concentration of H+ in the electrolyte to increase. + The decreasing concentration reaches the optimal pH range of each reaction unit, further synergistically promoting the VOCs treatment effect of the device.

[0021] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: The present invention uses a combination of electro-Fenton reaction and electrocatalytic reaction to treat VOCs gas, effectively improving the treatment effect of VOCs by combining the two electrochemical treatment methods; in particular, by changing the tray aperture and the overflow weir height, the residence time of electrolyte and VOCs gas in different reaction zones is adjusted, which on the one hand enhances the reaction efficiency of electrochemical reaction, and on the other hand, allows the H in the electrolyte to be concentrated. + The decreasing concentration precisely reaches the optimal pH range of each reaction zone, thereby improving the removal efficiency of VOCs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the gas processing device of the present invention.

[0023] Figure 2 This is a pipeline diagram of the gas processing device of the present invention;

[0024] Figure 3 This is a top view of the electrode tray. Detailed Implementation

[0025] like Figures 1-3 As shown, the VOCs gas treatment device based on electrochemical technology of the present invention includes a tower-type reaction chamber 14. Along the longitudinal direction, the tower-type reaction chamber 14 is provided with an electro-Fenton reaction zone 15 and an electrocatalytic reaction zone 16 arranged sequentially from top to bottom. The electro-Fenton reaction zone 15 is provided with multiple sets of staggered electro-Fenton units, each set consisting of an anode 2, an activated carbon layer 8, a carbon felt layer 9, and a cathode 3 from top to bottom. The electrocatalytic reaction zone 16 is provided with multiple sets of staggered electrocatalytic units, each set consisting of an upper anode 10, a cathode 4, and a lower anode 11 from top to bottom. Each electro-Fenton unit and each electrocatalytic unit is arc-shaped, with the arc-shaped side fitting and fixedly connected to the inner wall of the reaction chamber (fixed to the inner wall of the reaction chamber). An upward-extending overflow weir 5 and a downcomer 6 extending in the opposite direction to the overflow weir 5 are provided at the port away from the inner wall of the reaction chamber. Electrolytes falling onto the previous stage reaction unit overflow the overflow weir 5 and then descend along the downcomer 6 to the next stage reaction unit.

[0026] In the electro-Fenton unit, activated carbon is used to adsorb organic gases, and the carbon felt has adsorption, conductivity, and catalytic properties, promoting the generation of hydrogen peroxide. Since the gas rises from bottom to top, the entire electro-Fenton reaction requires the oxygen carried in the gas to react with the cathode with two electrons to generate hydrogen peroxide, so cathode 3 is located at the bottom.

[0027] In the electrocatalytic unit, the electrocatalytic part mainly involves oxidation reaction at the anode. The sandwich electrode arrangement, with two anodes sandwiching the cathode, can improve the efficiency of the electrocatalytic unit in treating waste gas, degrading as much organic matter in the gas as possible into smaller organic molecules, which is beneficial for the subsequent electro-Fenton reaction.

[0028] The tower-type reaction chamber 14 includes a liquid outlet 13 and an air inlet 12 located at the bottom of the reaction chamber, and a liquid inlet 7 and an air outlet 1 located at the top of the reaction chamber. Electrolytes flow out from the liquid outlet 13 at the bottom of the reaction chamber and are circulated by a circulation pump to the liquid inlet 7 at the top of the reaction chamber. Gas enters from the air inlet 12 at the bottom of the reaction chamber, reacts in the electrocatalytic reaction zone 16 from bottom to top, undergoes an oxidation-reduction reaction in the electro-Fenton reaction zone 15, and is then discharged from the air outlet 1 at the top of the reaction chamber. A spray head 18 is provided at the liquid inlet 7, through which the electrolyte is sprayed onto the uppermost electro-Fenton unit.

[0029] In the electro-Fenton unit and the electro-catalytic unit, the orifice plates (plates) selected for the cathode and anode are actually electrode plates, and the outer diameter of the plate (circular) is 70-90% of the inner diameter of the reaction chamber.

[0030] In the electro-Fenton reaction zone, multiple sets of electro-Fenton units are first set up to achieve multiple series reactions, thus extending the residence time of electrolytes and gases in the electro-Fenton units. Then, by increasing the height of the overflow weir of the electro-Fenton unit, a certain liquid layer is maintained on the tray, further increasing the residence time of electrolytes in the electro-Fenton unit. Secondly, by reducing the pore size of the electro-Fenton unit tray and reducing the porosity of the porous material (carbon fiber felt) in the electro-Fenton unit, the residence time of VOCs gas in the electro-Fenton unit is increased. At the same time, the electrolyte liquid layer maintained by the overflow weir hinders gas flow, further increasing the residence time of VOCs gas in the electro-Fenton unit. As a result, the residence time of VOCs gas in the electro-Fenton reaction zone reaches 2-3 minutes, and the residence time of electrolytes in the electro-Fenton reaction zone reaches 6-10 minutes.

[0031] Example 1

[0032] The gas treatment device of this invention is used to treat waste gas containing toluene and n-hexane, with the initial concentrations of both toluene and n-hexane being 100 mg / m³. 3 The gas processing capacity is 20,000 m³. 3 / h;

[0033] The electrolyte composition is n(SO4)2- ): n(Cl - The ratio of electrolyte to electrolyte is 10:1. The pH of the electrolyte is adjusted to 2.5 at the top of the column, and the conductivity is 10000 μS / cm.

[0034] The distance between each Fenton unit and each electrocatalytic unit is 90 mm. With the power supply on, the current density is adjusted to 20 mA / cm². 2 (1) Electro-Fenton reaction stage: A total of 8 electro-Fenton units are set up, in which the anode of the electro-Fenton unit adopts iron electrode and the cathode adopts stainless steel electrode. The anode and cathode are filled with AC activated carbon and ACF carbon felt. The filling thickness of AC activated carbon is 85mm, and the radius of spherical activated carbon is 1mm. The thickness of ACF carbon felt is 15mm. The porosity of each plate is 30%, the pore size is 4mm, and the height of the overflow weir at the end of each electro-Fenton unit is 60mm. The outer diameter of the plate is 70% of the inner diameter of the reaction chamber. (2) Electrocatalysis stage: A total of 4 electrocatalysis units are set up, in which the anode of the electrocatalysis unit adopts Sb-SnO2 electrode and the cathode adopts stainless steel electrode. The distance between the anode and cathode is 2mm. The porosity of each plate is 45%, the pore size is 8mm, and the height of the overflow weir at the end of each electro-Fenton unit is 20mm. The outer diameter of the plate is 85% of the inner diameter of the reaction chamber. The diameter of the tower is 2m and the inner diameter of the tower is 80cm. The electrolyte is circulated from the outlet at the bottom of the column to the inlet at the top of the column via a circulating pump, thus realizing the recycling of the electrolyte; the residence time of the gas in the electro-Fenton reaction zone is about 2.2 minutes.

[0035] The concentrations of different treated gases were detected at the inlet and outlet of the gas using the corresponding detectors, and the removal rate was calculated as follows: Removal rate (%) = (Inlet concentration - Outlet concentration) / Inlet concentration × 100.

[0036] The results of the gas treatment are shown in Table 1:

[0037]

[0038]

[0039] As can be seen from Example 1 and Comparative Examples 1-4, the smaller the spacing between each processing unit, the better the mass transfer effect between adjacent units, the higher the organic matter removal rate, and the better the gas treatment effect.

[0040] Example 2

[0041] The gas treatment device of this invention is used to treat waste gas containing toluene and n-hexane, with the initial concentrations of both toluene and n-hexane being 100 mg / m³. 3 The gas processing capacity is 20,000 m³. 3 / h;

[0042] The electrolyte composition is n(SO4) 2- ): n(Cl - The ratio of electrolyte to electrolyte is 10:1. The pH of the electrolyte is adjusted to 2.5 at the top of the column, and the conductivity is 10000 μS / cm.

[0043] The distance between each Fenton unit and each electrocatalytic unit is 90 mm. With the power supply on, the current density is adjusted to 20 mA / cm². 2 (1) Electro-Fenton reaction stage: A total of 8 electro-Fenton units are set up, in which the anode of the electro-Fenton unit adopts iron electrode and the cathode adopts stainless steel electrode. The anode and cathode are filled with AC activated carbon and ACF carbon felt. The filling thickness of AC activated carbon is 85mm, and the radius of spherical activated carbon is 1mm. The thickness of ACF carbon felt is 15mm. The porosity of each plate is 30%, the pore size is 2mm, and the height of the overflow weir at the end of each electro-Fenton unit is 80mm. The outer diameter of the plate is 70% of the inner diameter of the reaction chamber. (2) Electrocatalysis stage: A total of 4 electrocatalysis units are set up, in which the anode of the electrocatalysis unit adopts Sb-SnO2 electrode and the cathode adopts stainless steel electrode. The distance between the anode and cathode is 2mm. The porosity of each plate is 45%, the pore size is 8mm, and the height of the overflow weir at the end of each electro-Fenton unit is 20mm. The outer diameter of the plate is 70% of the inner diameter of the reaction chamber. The diameter of the tower is 2m and the inner diameter of the tower is 80cm. The electrolyte is circulated from the outlet at the bottom of the column to the inlet at the top of the column via a circulating pump, thus realizing the recycling of the electrolyte; the residence time of the gas in the electro-Fenton reaction zone is 2.3 min.

[0044] The concentrations of different treated gases were detected at the inlet and outlet of the gas using the corresponding detectors, and the removal rate was calculated as follows: Removal rate (%) = (Inlet concentration - Outlet concentration) / Inlet concentration × 100.

[0045]

[0046]

[0047] Example 3

[0048] The gas treatment device of this invention is used to treat waste gas containing toluene and n-hexane, with the initial concentrations of both toluene and n-hexane being 100 mg / m³. 3 The gas processing capacity is 20,000 m³. 3 / h;

[0049] The electrolyte composition is n(SO4) 2- ): n(Cl - The ratio of electrolyte to electrolyte is 10:1. The pH of the electrolyte is adjusted to 2.5 at the top of the column, and the conductivity is 10000 μS / cm.

[0050] The distance between each Fenton unit and each electrocatalytic unit is 90 mm. With the power supply on, the current density is adjusted to 20 mA / cm². 2 (1) Electro-Fenton reaction stage: A total of 8 electro-Fenton units are set up, in which the anode of the electro-Fenton unit adopts iron electrode and the cathode adopts stainless steel electrode. The anode and cathode are filled with AC activated carbon and ACF carbon felt. The filling thickness of AC activated carbon is 55mm, and the radius of spherical activated carbon is 5mm. The thickness of ACF carbon felt is 10mm. The porosity of each plate is 30%, the pore size is 4mm, and the height of the overflow weir at the end of each electro-Fenton unit is 60mm. The outer diameter of the plate is 70% of the inner diameter of the reaction chamber. (2) Electrocatalysis stage: A total of 4 electrocatalysis units are set up, in which the anode of the electrocatalysis unit adopts Sb-SnO2 electrode and the cathode adopts stainless steel electrode. The distance between the anode and cathode is 2mm. The porosity of each plate is 45%, the pore size is 8mm, and the height of the overflow weir at the end of each electro-Fenton unit is 20mm. The outer diameter of the plate is 70% of the inner diameter of the reaction chamber. The diameter of the tower is 2m and the inner diameter of the tower is 80cm. The electrolyte is circulated from the outlet at the bottom of the column to the inlet at the top of the column via a circulating pump, thus realizing the recycling of the electrolyte; the residence time of the gas in the electro-Fenton reaction zone is 1.9 min.

[0051] The concentrations of different treated gases were detected at the inlet and outlet of the gas using the corresponding detectors, and the removal rate was calculated as follows: Removal rate (%) = (Inlet concentration - Outlet concentration) / Inlet concentration × 100.

[0052]

[0053] Example 4

[0054] The gas treatment device of this invention is used to treat waste gas containing toluene and n-hexane, with the initial concentrations of both toluene and n-hexane being 100 mg / m³. 3 The gas processing capacity is 20,000 m³. 3 / h;

[0055] The electrolyte composition is n(SO4) 2- ): n(Cl - The ratio of electrolyte to electrolyte is 10:1. The pH of the electrolyte is adjusted to 2.5 at the top of the column, and the conductivity is 10000 μS / cm.

[0056] The distance between each Fenton unit and each electrocatalytic unit is 90 mm. With the power supply on, the current density is adjusted to 20 mA / cm². 2(1) Electro-Fenton reaction stage: A total of 8 electro-Fenton units are set up, in which the anode of the electro-Fenton unit adopts iron electrode, the cathode adopts stainless steel electrode, and the space between the anode and cathode is filled with AC activated carbon and ACF carbon felt; the filling thickness of AC activated carbon is 85mm, the radius of spherical activated carbon is 1mm; the thickness of ACF carbon felt is 15mm; the opening ratio of each plate is 25%, the pore size is 2mm, the height of the overflow weir at the end of each electro-Fenton unit is 80mm; the outer diameter of the plate is 85% of the inner diameter of the reaction chamber; (2) Electrocatalysis stage: A total of 4 electrocatalysis units are set up, in which the anode of the electrocatalysis unit adopts Sb-SnO2 electrode, the cathode adopts stainless steel electrode, the distance between the anode and cathode is 2mm; the opening ratio of each plate is 60%, the pore size is 10mm, the height of the overflow weir at the end of each electro-Fenton unit is 10mm; the outer diameter of the plate is 85% of the inner diameter of the reaction chamber; the diameter of the device tower is 2m, and the inner diameter of the tower is 80cm. The electrolyte is circulated from the outlet at the bottom of the column to the inlet at the top of the column via a circulating pump, thus realizing the recycling of the electrolyte; the residence time of the gas in the electro-Fenton reaction zone is 2.35 min.

[0057]

[0058] Example 5

[0059] The gas treatment device of this invention is used to treat waste gas containing toluene and acetone, both of which have a concentration of 300 mg / m³. 3 The gas processing capacity is 5000m³. 3 / h;

[0060] The electrolyte composition is n(SO4) 2- ): n(Cl - The electrolyte ratio was 5:1, and the pH of the electrolyte was adjusted to 2.7 at the top of the column, with a conductivity of 5000 μS / cm.

[0061] The distance between each Fenton unit and each electrocatalytic unit is 90 mm. With the power supply on, the current density is adjusted to 15 mA / cm². 2(1) Electro-Fenton reaction stage: A total of 8 electro-Fenton units are set up, in which the anode of the electro-Fenton unit is an iron electrode and the cathode is a stainless steel electrode. The anode and cathode are filled with AC activated carbon and ACF carbon felt; the filling thickness of AC activated carbon is 85mm, and the radius of spherical activated carbon is 1mm; the thickness of ACF carbon felt is 15mm; the opening ratio of each tray is 25%, the pore size is 2mm, and the height of the overflow weir at the end of each electro-Fenton unit is 80mm; the outer diameter of the tray is 85% of the inner diameter of the reaction chamber; (2) Electrocatalytic stage: A total of Four electrocatalytic units were installed, with BDD electrodes as the anodes and stainless steel electrodes as the cathodes, and a 2mm gap between the anodes and cathodes. The opening ratio of each tray was 60%, with a pore size of 8mm. The height of the overflow weir at the end of each electro-Fenton unit was 20mm. The outer diameter of the tray was 85% of the inner diameter of the reaction chamber. The diameter of the tower was 2m, and the inner diameter was 80cm. The electrolyte was recycled from the outlet at the bottom of the tower to the inlet at the top via a circulating pump. The residence time of the gas in the electro-Fenton reaction zone was 2.34min.

[0062] The results of the gas treatment are shown in Table 2:

[0063]

[0064] As can be seen from Example 5 and Comparative Examples 5-8, as the current density in the device increases, the production of hydroxyl radicals per unit time is higher, the removal rate is higher, and the gas treatment effect is better.

[0065] Example 6

[0066] The gas treatment device of this invention is used to treat waste gas containing ethylene oxide and methanol, both with a concentration of 400 mg / m³. 3 The gas processing capacity is 500m³. 3 / h;

[0067] The electrolyte composition is n(SO4) 2- ): n(Cl - The ratio of electrolyte to electrolyte is 8:1. At the top of the column, the pH of the electrolyte is adjusted to 3, and the conductivity is 2500 μS / cm.

[0068] The distance between each Fenton unit and the electrocatalytic unit is 90 mm. With the power supply on, the current density is adjusted to 15 mA / cm². 2(1) Electro-Fenton reaction stage: A total of 8 electro-Fenton units are set up, in which the anode of the electro-Fenton unit is an iron electrode and the cathode is a stainless steel electrode. The anode and cathode are filled with AC activated carbon and ACF carbon felt; the filling thickness of AC activated carbon is 85mm, and the radius of spherical activated carbon is 1mm; the thickness of ACF carbon felt is 15mm; the opening ratio of each tray is 25%, the pore size is 2mm, and the height of the overflow weir at the end of each electro-Fenton unit is 80mm; the outer diameter of the tray is 90% of the inner diameter of the reaction chamber; (2) Electrocatalytic stage: A total of 4 The electrocatalytic unit uses a Ti / SnO2 electrode as the anode and a stainless steel electrode as the cathode, with a 2mm gap between the anode and cathode. Each tray has a 60% opening rate and a 10mm pore size. The overflow weir at the end of each electro-Fenton unit has a height of 15mm. The outer diameter of the tray is 90% of the inner diameter of the reaction chamber. The tower diameter is 2m, and the inner diameter is 80cm. The electrolyte is recycled from the outlet at the bottom of the tower to the inlet at the top via a circulating pump. The residence time of the gas in the electro-Fenton reaction zone is 2.38min.

[0069] The results of the gas treatment are shown in Table 3:

[0070]

[0071] As can be seen from Example 6 and Comparative Examples 9-12, in the electrocatalytic unit, the smaller the distance between the electrodes, the greater the electric field strength, the higher the organic matter removal rate, and the better the gas treatment effect.

Claims

1. A VOCs gas treatment device based on electrochemical technology, characterized by: The tower type reaction cavity comprises a tower type reaction cavity in the longitudinal direction, and an electro-Fenton reaction zone and an electro-catalysis reaction zone are sequentially arranged in the tower type reaction cavity from top to bottom.

2. The electrochemical technology based VOCs gas treatment device according to claim 1, characterized in that: The tower type reaction cavity further comprises a liquid outlet and a gas inlet arranged at the bottom of the reaction cavity, and a liquid inlet and a gas outlet arranged at the top of the reaction cavity; electrolyte flows out of the liquid outlet at the bottom of the reaction cavity, is circulated to the liquid inlet at the top of the reaction cavity by a circulating pump, and gas enters the gas inlet at the bottom of the reaction cavity, first passes through the electro-catalysis reaction zone from bottom to top to react, then passes through the electro-Fenton reaction zone to perform a redox reaction, and is discharged from the gas outlet at the top of the reaction cavity.

3. The electrochemical technology-based VOCs gas treatment device according to claim 2, characterized in that: A spray head is arranged at the liquid inlet, and electrolyte is sprayed onto the uppermost electro-Fenton unit by the spray head.

4. The electrochemical technology based VOCs gas treatment device as claimed in claim 1, wherein: In the electro-Fenton unit, the anode is an iron hole plate, the cathode is a stainless steel hole plate or a TiO2 hole plate, and the distance between the anode and the cathode is 65-100 mm.

5. The electrochemical technology based VOCs gas treatment device as claimed in claim 1, wherein: The filling thickness of the activated carbon layer is 55-85 mm, the activated carbon is spherical or cylindrical particles, and the particle size of the activated carbon is 1-5 mm; the filling thickness of the carbon felt layer is 10-15 mm; and the distance between the electro-Fenton units is 90-110 mm.

6. The electrochemical technology based VOCs gas treatment device as claimed in claim 1, wherein: In the electro-catalysis unit, the upper anode and the lower anode are Sb-SnO2 hole plates, synthetic boron-doped diamond thin layer BDD hole plates or Ti / SnO2 hole plates; the cathode is a stainless steel hole plate; the distance between the upper anode, the lower anode and the cathode is 2-5 mm; and the distance between the electro-catalysis units is 90-110 mm.

7. The electrochemical technology based VOCs gas treatment device as claimed in claim 1, wherein: In the electro-Fenton reaction zone, the number of electro-Fenton units is 6-8, the opening rate of each tray is 25-30%, the hole diameter is 2-4 mm, and the height of the overflow weir at the end of each electro-Fenton unit is 60-80 mm; and the outer diameter of the tray is 70-90% of the inner diameter of the reaction cavity.

8. The electrochemical technology based VOCs gas treatment device as claimed in claim 1, wherein: In the electro-catalysis reaction zone, the number of electro-catalysis units is 2-4, the opening rate of each tray is 45-60%, the hole diameter is 8-10 mm, the height of the overflow weir at the end of each electro-catalysis unit is 10-20 mm, and the outer diameter of the tray is 70-90% of the inner diameter of the reaction cavity.

9. The electrochemical technology based VOCs gas treatment device as claimed in claim 2, wherein: The electrolyte is a mixed solution of sodium sulfate solution and sodium chloride solution, wherein the electrolyte has a composition of n(SO4 2- ) : n(Cl - ) = 5 to 10:

1.

10. The electrochemical technology based VOCs gas treatment device as claimed in claim 2, wherein: The pH of the electrolyte entering the electro-Fenton reaction zone is 1-3, and the pH of the electrolyte entering the electro-catalysis reaction zone is 5-6.

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