Indole degradation device based on strong ionization discharge plasma and indole degradation method thereof

Abstract

The invention discloses an indole degradation device based on strong ionization discharge plasma and an indole degradation method thereof, and relates to the field of environmental protection and air pollution abatement, the indole degradation device comprises a discharge electrode and a grounding electrode, the discharge electrode is connected with a pulse power supply, the grounding electrode is grounded, and the discharge electrode and the grounding electrode are arranged in parallel; dielectric layers are arranged between the discharge electrode and the grounding electrode, a discharge gap is formed between the dielectric layers, and organic waste gas enters the space between the discharge electrode and the grounding electrode at a certain temperature, relative humidity, flow rate and concentration to be ionized and then enters a product collecting device. By improving the discharge energy density and optimizing the reaction conditions, efficient indole degradation is achieved, meanwhile, generation of by-products is reduced, and the method is suitable for efficient treatment of high-concentration VOCs waste gas.

Description

Technical Field

[0001] The invention relates to the field of environmental protection and air pollution control, and in particular to an indole degradation device based on strong ionization discharge plasma and an indole degradation method thereof. Background Art

[0002] Volatile organic compounds (VOCs) are one of the air pollutants, mainly from industrial processes such as petrochemicals, medicine, printing, and spraying. The emission of VOCs not only pollutes the atmospheric environment, but also produces ozone under sunlight with nitrogen oxides (NOx), forming photochemical smog, which affects human health and the ecological environment. Indole, as one of the common VOCs, is widely used in the chemical, pharmaceutical, and coating industries, and is highly volatile and harmful.

[0003] Existing technologies such as adsorption, catalytic combustion and low-temperature plasma methods can treat VOCs, but they have the disadvantages of high energy consumption, complex equipment or incomplete treatment. For example, the adsorption method requires regular replacement of the adsorption material, which increases the complexity of the operation; although the catalytic combustion method has a good degradation effect, it has high energy consumption and strict requirements on the heat resistance of the equipment. Although low-temperature plasma technology can effectively treat VOCs at room temperature and pressure, traditional plasma devices often have low energy utilization, cannot effectively treat high-concentration exhaust gas, and may generate byproducts such as ozone and nitrogen oxides. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an indole degradation device and an indole degradation method based on strong ionization discharge plasma. The present invention improves the discharge energy density and optimizes the reaction conditions to achieve efficient degradation of indole while reducing the generation of by-products. The present invention is suitable for efficient treatment of high-concentration VOCs waste gas.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] An indole degradation device based on strong ionization discharge plasma comprises a discharge electrode and a ground electrode, wherein the discharge electrode is connected to a pulse power supply, the ground electrode is grounded, the discharge electrode and the ground electrode are arranged in parallel, a dielectric layer is arranged between the discharge electrode and the ground electrode, a discharge gap is formed between the dielectric layers, and organic waste gas enters between the discharge electrode and the ground electrode at a certain temperature, relative humidity, flow rate and concentration, is ionized and then enters a product collection device.

[0007] In the above scheme, the dielectric layer material is α-Al 2 O 3 , the thickness of the dielectric layer is 1 to 5 mm, and the discharge gap is 0.5 to 2 cm.

[0008] In the above scheme, the pulse power supply is 3-10 kV, and the pulse frequency is 1-10 kHz.

[0009] In the above solution, the discharge electrode material is metallic silver.

[0010] In the above scheme, the organic waste gas is placed in an organic waste gas cylinder, and a pressure reducing valve and a rotor flow meter are arranged on the pipeline outside the organic waste gas cylinder. The organic waste gas enters the heating belt at a certain speed and concentration to be heated.

[0011] In the above scheme, the temperature of the heating belt is controlled by a temperature controller.

[0012] In the above scheme, the temperature is 15-50°C, the relative humidity is 10-90% and the flow rate is 1.0-5.0m 3 / h.

[0013] In the above scheme, the product collecting device is connected to a tail gas absorption bottle through a pipeline, and the organic waste gas after electrolysis is purified in the tail gas absorption bottle.

[0014] The above scheme also includes a control system, which controls the operation of the pressure reducing valve, the rotor flow meter, the temperature controller and the pulse power supply.

[0015] The indole degradation method based on the indole degradation device of strong ionization discharge plasma comprises the following steps:

[0016] Step 1: Gas pretreatment: Generate indole waste gas through a gas generator and adjust the temperature, relative humidity, concentration and flow rate;

[0017] Step 2: The pretreated indole waste gas is introduced between the discharge electrode and the ground electrode, and the pulse power supply and dielectric are used to generate high-energy electrons and active species to react with indole molecules to decompose indole into harmless small molecular products;

[0018] Step 3: Tail gas treatment: Remove byproducts such as ozone and nitrogen oxides through tail gas treatment;

[0019] Step 4: Exhaust emission: The purified exhaust gas is discharged into the atmosphere to ensure that the emission meets environmental protection standards.

[0020] Beneficial effects:

[0021] 1. The present invention significantly improves the degradation efficiency of indole through strong ionization discharge plasma technology, and the removal rate can reach more than 95%, which is particularly suitable for treating high-concentration indole waste gas.

[0022] 2. The device of the present invention has a simple structure, is easy to operate, is suitable for industrial promotion, and reduces the maintenance and operation costs of the processing equipment.

[0023] 3. The method of the present invention does not require the addition of a catalyst during the reaction process, thereby reducing the risk of secondary pollution. At the same time, the amount of by-products such as ozone and nitrogen oxides generated is relatively small, thus meeting environmental protection requirements.

[0024] 4. The method of the present invention can flexibly adjust the device operating parameters, so that the device is suitable for treating VOCs waste gas of different concentrations and types BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of an indole degradation device based on strong ionization discharge plasma;

[0026] Figure 2 for Figure 1 Schematic diagram of the working principle of the discharge electrode and grounding electrode involved in;

[0027] Figure 3 for Figure 1 Schematic diagram of organic waste gas cylinders, heating belts and temperature controllers involved;

[0028] Figure 4 for Figure 1 Schematic diagram of waste gas treatment after ionization involved in;

[0029] Figure 5 This is a graph showing the experimental results of the effects of different initial concentrations on indole degradation efficiency according to the present invention;

[0030] Figure 6 This is a graph showing the experimental results of the effects of different gas flow rates on indole degradation efficiency according to the present invention;

[0031] Figure 7 This is a graph showing the experimental results of the effect of different relative humidity on the indole degradation efficiency according to the present invention;

[0032] Figure 8 This is a graph showing the experimental results of the effects of different temperatures on indole degradation efficiency according to the present invention.

[0033] Reference numerals:

[0034] 1- organic waste gas cylinder; 2- pressure reducing valve; 3- rotor flowmeter; 4- heating belt; 5- temperature controller; 6- discharge electrode; 7- ground electrode; 8- pulse power supply; 9- dielectric layer; 10- product collection device; 11- tail gas absorption bottle; 12- discharge gap. DETAILED DESCRIPTION

[0035] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0036] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] An indole degradation device based on strong ionization discharge plasma generates high-energy electrons and active species in a reactor through high voltage, reacts with indole molecules, destroys their chemical bonds, and decomposes them into harmless small molecular products. The present invention can effectively treat high-concentration indole waste gas with a removal rate of more than 95%, and inhibits the generation of by-products such as ozone and nitrogen oxides by reasonably regulating parameters such as voltage and discharge frequency. The control system can adjust the operating parameters according to different waste gas concentrations to ensure the optimal performance of the device under different working conditions. The present invention has the advantages of simple structure, convenient operation, high treatment efficiency, and environmental friendliness, and is suitable for industrial waste gas treatment in petrochemical, printing, pharmaceutical and other industries.

[0038] Combined with Figure 1-4 As shown, an indole degradation device based on strong ionization discharge plasma includes a discharge electrode 6 and a ground electrode 7, the discharge electrode 6 is connected to a pulse power supply 8, the ground electrode 7 is grounded, the discharge electrode 6 and the ground electrode 7 are arranged in parallel, a dielectric layer 9 is arranged between the discharge electrode 6 and the ground electrode 7, and a discharge gap 12 is formed between the dielectric layers 9. The organic waste gas is heated at a temperature of 15-50°C, a relative humidity of 10-90%, and a flow rate of 1.0-5.0m 3 / h and a certain concentration enter between the discharge electrode 6 and the ground electrode 7, are ionized, and then enter the product collection device 10.

[0039] The material of the dielectric layer 9 is α-Al 2 O 3 , the thickness of the dielectric layer is 1 to 5 mm, and the discharge gap 12 is 0.5 to 2 cm.

[0040] The pulse power supply 8 is 3-10 kV, and the pulse frequency is 1-10 kHz. The pulse frequency and intensity can be automatically adjusted according to the initial concentration and flow rate of the gas to adapt to the treatment of indole waste gas with different concentrations.

[0041] The discharge electrode material is metallic silver, and a cooling channel is provided outside the discharge electrode to adjust the working temperature of the reactor to prevent overheating from affecting the degradation efficiency.

[0042] The organic waste gas is placed in an organic waste gas cylinder 1, and a pressure reducing valve 2 and a rotor flowmeter 3 are arranged on the pipeline outside the organic waste gas cylinder 1. The organic waste gas enters the heating belt at a certain speed and concentration to be heated.

[0043] The temperature of the heating belt 4 is controlled by a temperature controller 5 .

[0044] The product collecting device 10 is connected to the tail gas absorption bottle 11 through a pipeline. The organic waste gas after electrolysis is purified in the tail gas absorption bottle. The by-products such as ozone and nitrogen oxides are removed by the tail gas treatment system, which is used to monitor the tail gas composition after the reaction in real time and ensure that the by-products such as O 3 , NOx, etc. are within the safe range.

[0045] It also includes a control system, which controls the operation of the pressure reducing valve 1, the rotor flowmeter 2, the temperature controller 5 and the pulse power supply 8.

[0046] Combined with Figure 5 The figure shows the experimental results of the effect of different initial concentrations on the indole degradation efficiency of the present invention. The discharge frequency is kept at 5kHz, the relative humidity is 20%, and the gas temperature is 20°C. By changing the initial concentration, the initial concentrations (785, 1375, 1767 and 2357 mg / m 3 ) to study the effect of different initial indole concentrations on its degradation efficiency in a strong ionization reactor. For all concentrations studied in this experiment, as the applied voltage increased, the degradation efficiency of indole increased to varying degrees. As the voltage continued to increase, the rate of increase in the indole degradation rate gradually slowed down and eventually tended to a stable value. Therefore, increasing the voltage when the degradation efficiency tends to be stable will only lead to higher energy consumption and reduce energy utilization. Figure 4 It can be seen that when the voltage exceeds 2.4 kV, low concentrations of indole are easily removed. When the concentration is 785 mg / m 3 When the concentration increased to 2357 mg / m 3 When the removal efficiency is only 24.8%. 3 and 1767 mg / m 3 Similar phenomena were observed at concentrations of , and the degradation efficiency of indole was significantly improved at 2.6 kV. At the same time, when the applied voltage was constant, the removal efficiency decreased with increasing concentration.

[0047] Experiments show that the device has a high treatment efficiency at different indole concentrations, with the removal rate maintained above 90% and the amount of by-products generated being low.

[0048] Combined with Figure 6 The figure shows the experimental results of the effect of different gas flow rates on the indole degradation efficiency of the present invention. By controlling the initial concentration of indole at 2357 mg / m 3 The discharge frequency was kept constant at 5kHz and the relative humidity of the atmosphere was kept constant at 20%. The flow rate of the inlet gas was changed to change the space velocity, so that the strong ionization discharge reactor used different space velocities to further study the effect of space velocity on the indole degradation efficiency. Figure 5 As shown, the space speed is from 442h -1 Increased to 973h -1 , the removal efficiency of indole decreased at any applied voltage, indicating that space velocity is also an important factor affecting the indole degradation efficiency. -1 ,718h -1 and 442h -1 When the applied voltage was 3.4 kV, the degradation efficiency of indole was 85.2%, 89.3% and 95.1% respectively; when the applied voltage was 2.1 kV, the space velocity was 973 h -1 、718h -1 and 442h -1 When , the indole degradation rates were 11.2%, 19.5% and 41.7% respectively. Figure 5 We can also observe that the effect of gas flow rate on indole is more obvious at lower voltages.

[0049] Experiments show that when the gas flow rate is low, the indole waste gas stays in the reactor for a longer time, which is conducive to full reaction; while at a higher flow rate, the gas residence time is shortened, the reaction is incomplete, and the removal rate is reduced.

[0050] Combined with Figure 7 The experimental conditions used in this experiment to study the effect of humidity changes on the degradation effect are: temperature 20°C, initial indole concentration 1676 mg / m 3 , gas flow rate 12L / min, discharge frequency 5.23kHz. Using the water vapor regulating device, the relative humidity of the gas entering the reactor was changed, and several groups of graphs of indole degradation efficiency changing with humidity at different voltages were measured, such as Figure 6As shown in the figure, we can see that the degradation rate of indole reaches the maximum value when the relative humidity is 20%. In addition, the effect of humidity on indole is not obvious. In the relative humidity range of 0-80%, the fluctuation range of indole removal efficiency under all different voltages is less than 10%. Moreover, at low voltage (2.5kV), the effect of humidity is more significant.

[0051] Experiments show that the best humidity condition is about 20%, under which the degradation efficiency is the highest. Therefore, it is recommended to adjust the humidity to about 20% according to the on-site environment in actual application to obtain the best treatment effect.

[0052] Combined with Figure 8 The figure shows the experimental results of the effect of different temperatures on the indole degradation efficiency of the present invention. Experimental conditions: the initial concentration of indole is 1676 mg / m 3 , gas flow rate of 12L / min, relative humidity of 20%, the degradation efficiency of indole in the strong ionization discharge reactor was studied at different temperatures (20℃, 50℃, 70℃, 100℃, 120℃ and 150℃) when the specific input energy was 76J / L, 82J / L and 90J / L respectively. Figure 7 As shown in the figure, when the temperature rises from 20℃ to 150℃, the degradation efficiency of indole increases to varying degrees at each specific input energy. When the specific input energy is 90J / L, the degradation efficiency increases from 71% to 98.6%. When the specific input energy is lower at 76J / L, the degradation efficiency increases by 38%.

[0053] The experimental results show that as the temperature continues to rise, the kinetic energy of the gas molecules becomes higher. The high energy of the gas molecules themselves plus the energy transferred when the high-energy electrons collide with the gas molecules make the gas molecules easier to ionize. The ionized gas molecules ultimately increase the current. This phenomenon will also improve the degradation efficiency of indole from another perspective.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0055] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. An indole degradation device based on strong ionization discharge plasma, characterized in that: It includes a discharge electrode and a grounding electrode. The discharge electrode is connected to a pulse power supply, the grounding electrode is grounded, the discharge electrode and the grounding electrode are arranged in parallel, a dielectric layer is arranged between the discharge electrode and the grounding electrode, and a discharge gap is formed between the dielectric layers. Organic waste gas enters between the discharge electrode and the grounding electrode at a certain temperature, relative humidity, flow rate and concentration, is ionized, and then enters a product collection device.

2. The indole degradation device based on strong ionization discharge plasma according to claim 1, characterized in that: The dielectric layer material is α-Al2O3, the dielectric layer thickness is 1 to 5 mm, and the discharge gap is 0.5 to 2 cm.

3. The indole degradation device based on strong ionization discharge plasma according to claim 1, characterized in that: The pulse power supply is 3-10 kV, and the pulse frequency is 1-10 kHz.

4. The indole degradation device based on strong ionization discharge plasma according to claim 1, characterized in that: The discharge electrode material is metallic silver.

5. The indole degradation device based on strong ionization discharge plasma according to claim 1, characterized in that: The organic waste gas is placed in an organic waste gas cylinder, and a pressure reducing valve and a rotor flow meter are arranged on the pipeline outside the organic waste gas cylinder. The organic waste gas enters the heating belt at a certain speed and concentration and is heated.

6. The indole degradation device based on strong ionization discharge plasma according to claim 5, characterized in that: The temperature of the heating belt is controlled by a temperature controller.

7. The indole degradation device based on strong ionization discharge plasma according to claim 1, characterized in that: The temperature is 15-50℃, the relative humidity is 10-90% and the flow rate is 1.0~5.0m 3 / h.

8. The indole degradation device based on strong ionization discharge plasma according to claim 1, characterized in that: The product collecting device is connected to a tail gas absorption bottle through a pipeline, and the organic waste gas after electrolysis is purified in the tail gas absorption bottle.

9. The indole degradation device based on strong ionization discharge plasma according to claim 1, characterized in that: The utility model also comprises a control system, wherein the control system controls the operation of the pressure reducing valve, the rotor flow meter, the temperature controller and the pulse power supply.

10. The indole degradation method according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Gas pretreatment: Generate indole waste gas through a gas generator and adjust the temperature, relative humidity, concentration and flow rate; Step 2: The pretreated indole waste gas is introduced between the discharge electrode and the ground electrode, and the pulse power supply and dielectric are used to generate high-energy electrons and active species to react with indole molecules to decompose indole into harmless small molecular products; Step 3: Tail gas treatment: Remove byproducts such as ozone and nitrogen oxides through tail gas treatment; Step 4: Exhaust emission: The purified exhaust gas is discharged into the atmosphere to ensure that the emission meets environmental protection standards.

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