CN209968113U

CN209968113U - Heterogeneous discharge system for removing VOCs with different solubilities through catalysis and synergy

Info

Publication number: CN209968113U
Application number: CN201920519328.2U
Authority: CN
Inventors: 徐苹; 王蕾; 陈航宇; 王嘉倩; 杨晔; 赖安兴; 袁俊发
Original assignee: Xiamen University of Technology
Current assignee: Xiamen University of Technology
Priority date: 2019-04-17
Filing date: 2019-04-17
Publication date: 2020-01-21
Anticipated expiration: 2029-04-17

Abstract

The utility model relates to a VOCs field of handling, specifically relate to a catalysis is in coordination with heterogeneous discharge system who gets rid of different solubility VOCs, including inclosed reaction chamber, reaction tank and dielectric barrier discharge device, reaction chamber has air inlet and gas outlet, the pool mouth of reaction tank is located the reaction chamber, alkaline solution has in the reaction tank, dielectric barrier discharge device has included the high voltage electrode that is located directly over the reaction tank and is located the reaction chamber and the barrier medium that is located between high voltage electrode and the reaction tank pool mouth, the reaction tank direct ground connection is as the low voltage electrode of this dielectric barrier discharge device; the liquid surface of the reaction tank is covered with a catalyst net which comprises a reticular carrier, the upper surface of the carrier is provided with a VOCs gas-phase reaction catalyst, and the lower surface of the carrier is provided with a VOCs liquid-phase reaction catalyst, so that soluble and indissolvable VOCs can be removed simultaneously.

Description

Heterogeneous discharge system for removing VOCs with different solubilities through catalysis and synergy

Technical Field

The utility model relates to a VOCs handles the field, specifically relates to a heterogeneous discharge system that different solubility VOCs was got rid of in coordination in catalysis.

Background

Volatile Organic Compounds (VOCs) are an important component of atmospheric pollution, and are a complex source of emissions and a wide variety of pollutants. The industrial source VOCs is discharged most, and the terminal treatment technology is an important link in VOCs pollution control.

However, the VOCs have complex components and wide concentration and flow ranges, and the traditional VOCs treatment technology has low efficiency, high cost, complex process and limited industrial application. The conventional technologies include absorption, thermal decomposition, catalytic oxidation, membrane separation, etc., but these conventional treatment technologies have limitations in treating complex VOCs. Activated carbon such as adsorption is easily saturated and generates micro waste; the thermal decomposition method and the catalytic oxidation method are both carried out in a high-temperature environment, and the requirement on equipment is high; the membrane separation method has more intermediate products and is not easy to process; the life of the photocatalytic mercury lamp is short, aerosol is generated in the reaction process, the light transmittance of the mercury lamp can be reduced, the photocatalytic reaction is influenced, and in addition, the mercury lamp belongs to micro waste and is difficult to treat.

The low-temperature plasma (NTP) technology utilizes inelastic collision between high-energy electrons and gas molecules, and generates a large amount of active particles through excitation, dissociation, ionization and other processes, so that organic pollutants can be thoroughly decomposed.

The applicant finds that the concerted catalysis can improve the removal rate of the composite VOCs, inhibit the generation of byproducts and reduce the energy consumption in research. The problem of the treatment effect of the different VOCs of solubility that often generates is not good in the industrial production is directed against, heterogeneous plasma concerted catalysis processing system has been designed, effectively gets rid of compound organic pollution, avoids producing by-products such as aerosol simultaneously, and this application is from this.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a heterogeneous discharge system of different solubility VOCs is got rid of in coordination in catalysis, this heterogeneous discharge system handles VOCs simultaneously on gaseous phase and liquid phase, can get rid of the VOCs of different solubilities simultaneously.

The specific scheme is as follows:

a multi-phase discharge system for removing VOCs with different solubilities in a catalytic and synergistic manner comprises a closed reaction chamber, a reaction tank and a dielectric barrier discharge device, wherein the reaction chamber is provided with an air inlet and an air outlet, a tank opening of the reaction tank is positioned in the reaction chamber, an alkaline solution is arranged in the reaction tank, the dielectric barrier discharge device comprises a high-voltage electrode positioned right above the reaction tank and positioned in the reaction chamber and a barrier medium positioned between the high-voltage electrode and the tank opening of the reaction tank, and the reaction tank is directly grounded to serve as a low-voltage electrode of the dielectric barrier discharge device; the liquid level of the reaction tank is also covered with a catalyst net which comprises a reticular carrier, the upper surface of the carrier is provided with a VOCs gas-phase reaction catalyst, and the lower surface of the carrier is provided with a VOCs liquid-phase reaction catalyst.

Further, the catalyst net floats on the liquid surface of the alkaline solution in the reaction tank.

Further, the gas phase reaction catalyst for VOCs comprises at least one transition metal ion.

Further, the VOCs liquid phase reaction catalyst is a Fenton reaction catalyst.

Further, the carrier of the catalyst net is made of Al₂O₃And (4) preparing.

Further, the alkaline solution is NaHCO₃The pH value of the aqueous solution is 8-9.

Further, the reaction tank is also connected with a pH value detector and a circulating device, the pH value detector can detect the pH value of the alkaline solution in the reaction tank, and the circulating device can circularly supplement the alkaline solution in the reaction tank.

The utility model provides a heterogeneous discharge system that different solubility VOCs were got rid of in coordination in catalysis has following advantage compared with prior art:

1. the utility model provides a heterogeneous discharge system adopts non-uniform plasma catalysis processing system in coordination, when to gas discharge, also discharges to the solution pond surface of water, can handle the VOCs of different solubilities simultaneously to improve compound VOCs's clearance, restrain the formation of accessory substance and reduce the energy consumption.

2. The in-process production intermediate products such as organic acid of conventional DBD (dielectric barrier discharge) processing VOCs, the further degradation of organic acid also need consume the energy, the utility model discloses carry out follow-up degradation with simple cheap chemical method after degrading into organic acid with it earlier, reduce the energy consumption on the whole.

3. Conventional compound VOCs handles and often adopts the washing gas as the main step, but the unable processing of washing gas waste water, the utility model discloses a discharge the solution tank surface of water, also solved the processing problem of waste water when getting rid of VOCs.

4. Because the main active substance produced by the conventional gas-phase dielectric barrier discharge is ozone, the active substance produced by the gas-liquid discharge of the utility model comprises a large amount of hydroxyl free radicals, OH and hydrogen peroxide besides ozone, and the hydroxyl free radicals have stronger oxidability compared with the ozone and have faster reaction rate with organic pollutants.

5. In the method and device of conventional DBD (dielectric barrier discharge) processing VOCs, often use the mode of adding water vapor outward in order to increase the production of hydroxyl radical, the utility model discloses utilize the gas-liquid to discharge simultaneously, need not to add water vapor generating device.

Drawings

Fig. 1 shows a schematic diagram of a multi-phase discharge system.

Figure 2 shows a schematic diagram of a catalyst mesh.

Detailed Description

To further illustrate the embodiments, the present invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. With these references, one of ordinary skill in the art will appreciate other possible embodiments and advantages of the present invention. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

The present invention will now be further described with reference to the accompanying drawings and detailed description.

As shown in fig. 1, the utility model provides a heterogeneous discharge system of different solubility VOCs is got rid of in coordination in catalysis, this heterogeneous discharge system include inclosed reaction chamber 10, reaction tank 20 and dielectric barrier discharge device 30, reaction chamber 10 has air inlet 100 and gas outlet 110, the pool mouth of reaction tank 20 is located reaction chamber 10, alkaline solution has in the reaction tank 20, and alkaline solution can absorb some soluble VOCs in the waste gas. The dielectric barrier discharge device 30 includes a high voltage electrode 300 located right above the cell opening of the reaction cell 20 and located in the reaction chamber 10, and a barrier dielectric 310 located between the high voltage electrode 300 and the cell opening, and the reaction cell 20 is directly grounded to serve as a low voltage electrode of the dielectric barrier discharge device.

Wherein the reaction chamber 10 and the blocking medium are made of an insulating material, such as polymethyl methacrylate. The alternating voltage applied between the high-voltage electrode and the low-voltage electrode is provided by an alternating-current high-voltage power supply, the discharge gap between the two electrodes (namely the distance between the high-voltage electrode and the liquid level of the alkaline solution in the reaction tank 20) is 3-10 mm, and the discharge voltage is about 10 kV-40 kV at the moment.

In addition, referring to fig. 1 and 2, the liquid surface of the reaction tank 20 is covered by a catalyst net 40, the catalyst net 40 includes a net-shaped carrier 400, the upper surface of the carrier is coated with a gas-phase reaction catalyst 410 of VOCs, and the lower surface of the carrier is coated with a liquid-phase reaction catalyst 420 of VOCs. The carrier 400 is made of a material having good chemical stability, such as ceramic, quartz, etc., the VOCs gas phase reaction catalyst 410 may be a catalyst including transition metal ions, such as Ti, Pt, Pd, Mn, Co, Ce, etc., and the VOCs liquid phase reaction catalyst 420 may be a transition metal ion catalyst, such as Fe²⁺、Cu²⁺. The catalyst mesh 40 not only can accelerate the decomposition of VOCs, but also can solve the problem of unstable discharge caused by air flow blowing the water surface. Preferably, the catalyst net 40 floats on the surface of the alkaline solution in the reaction tank 20, i.e. the lower part of the catalyst net 40 is directly contacted with the alkaline solution, and the upper part is located on the surface of the alkaline solution.

When the dielectric barrier discharge device 30 discharges, not only the gas between the two electrodes but also the water surface of the reaction tank 20 is discharged. In the gas phase, VOCs are directly degraded by strong oxidizing particles generated by discharging in the discharging air gap, wherein ozone generated by the reaction is adsorbed on the catalyst mesh 40 and reacts with the VOCs gas-phase reaction catalyst 410 on the catalyst mesh 40 to generate oxygen free radicals to initiate chain reaction, so that the reaction process is accelerated, the gas-phase catalytic reaction rate is improved, and the decomposition of VOCs is accelerated; in the liquid phase, the dielectric barrier discharge device 30 discharges to the water surface of the reaction tank 20 to generate hydrogen peroxide, and particles such as copper, iron and the like in the fenton reaction catalyst and the hydrogen peroxide in the solution generate a fenton reaction to generate a large amount of hydroxyl radicals, thereby promoting the degradation of soluble organic matters.

The mechanism of the multiphase discharge system for removing VOCs is as follows: under the combined action of the medium barrier discharge device, the catalyst net and the alkaline solution, the medium barrier discharge device discharges to generate a large amount of energy-carrying electrons to bombard pollutants so as to ionize, dissociate and excite the pollutants, and simultaneously discharges to the water surface of the alkaline solution to generate O₃And H₂O₂During initiation ofA series of complex physical and chemical reactions are carried out, so that macromolecular pollutants in the VOCs are converted into micromolecular organic matters, and CO is finally generated₂And H₂O。

The brief mechanism of VOCs is illustrated by using insoluble gas toluene and soluble gas ethyl acetate which are common in VOCs as examples:

e+O₂→2O+e

O+O₂→O₃

H₂O+e→OH^·+H^·+e

H₂O+e→2e+H₂O⁺

H₂O⁺+H₂O→OH^·+H₃O⁺

H₂O+e^-→OH^·+H^·+e^-

OH^·+OH^·→H₂O₂

H₂O₂+hv→2OH^·

wherein R is H, CH3, etc.

I.e. O₂And H₂Production of O by dielectric discharge₃And H₂O₂Toluene and ethyl acetate in dielectric discharge, O₃、H₂O₂And the reaction and decomposition are carried out under the action of a catalyst, wherein the reaction intermediate product is a plurality of organic acids, such as formic acid, acetic acid and the like, part of the organic acids produced by the reaction is absorbed by an alkaline solution, and the rest part of the organic acids are further decomposed into CO under the action of discharge and the catalyst₂And H₂O。

In this embodiment, preferably, the alkaline solution is NaHCO₃The pH value of the aqueous solution is 8-9.

In this embodiment, it is further preferable that the reaction tank 20 is further connected to a pH detector 50 and a circulation device (not shown in the figure), the pH detector 50 can detect the pH of the alkaline solution in the reaction tank 20, and the circulation device can circulate and replenish the alkaline solution in the reaction tank 20, for example, when the pH of the alkaline solution in the reaction tank 20 is lower than 8, the circulation device (typically, a circulation pump) pumps an externally stored alkaline solution into the reaction tank 20 to circulate and replenish the alkaline solution in the reaction tank 20.

The utility model provides a VOCs processing system is when handling VOCs, the gaseous direct alkaline solution absorption by the alkaline solution of VOCs of partly water-soluble, partly by the direct decomposition of the plasma that dielectric barrier discharge produced, and the ozone that the reaction produced is adsorbed on catalyst net 40, with VOCs gaseous phase reaction catalyst 410 reaction generation oxygen free radical initiation chain reaction on catalyst net 40, VOCs's decomposition has been accelerated, copper in the fenton reaction catalyst, iron particle takes place the fenton reaction with the hydrogen peroxide in the solution, produce a large amount of hydroxyl free radicals, also promote VOCs's degradation, thereby make this VOCs processing system can get rid of soluble and indissolvable VOCs simultaneously, good VOCs treatment effeciency has.

Example 1

The experimental conditions for this example are as follows:

toluene which is slightly soluble in water is used as insoluble VOCs, ethyl acetate is used as soluble VOCs, and nitrogen and air are used as carrier gases;

the discharge gap is 5mm, and the discharge voltage is 24 KV;

the alkaline solution is NaHCO₃Aqueous solution of NaHCO₃The pH of the aqueous solution was 9.

The test procedure was as follows:

(1) respectively passing nitrogen gas through a sealed bottle filled with toluene and ethyl acetate to form high-concentration toluene and ethyl acetate gas, and mixing the toluene and ethyl acetate gas with air in a mixing bottle to form VOCs gas;

(2) introducing VOCs gas into the VOCs treatment system at the flow rate of 1.2L/min for treatment, carrying out medium discharge after the gas flow rate is stable, respectively sampling from the gas inlet and the gas outlet of the VOCs treatment system after the medium discharge lasts for 30min, and then analyzing the concentrations of toluene and ethyl acetate in the VOCs by using gas chromatography.

Wherein the concentration of toluene at the gas inlet is 51.43ppm and the concentration of ethyl acetate is 26.74ppm according to gas chromatographic analysis; after the medium is discharged for 30min, the concentration of toluene at the air outlet is 4.19ppm, the concentration of ethyl acetate is 1.32ppm, and according to the solubility of toluene and ethyl acetate in the air inlet and the air outlet, the removal rate of toluene and the removal rate of ethyl acetate of the VOCs treatment system can be calculated to be 91.85% and 95.06%.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A catalysis is in coordination with heterogeneous discharge system who gets rid of different solubility VOCs which characterized in that: the device comprises a closed reaction chamber, a reaction tank and a dielectric barrier discharge device, wherein the reaction chamber is provided with an air inlet and an air outlet, a tank opening of the reaction tank is positioned in the reaction chamber, an alkaline solution is arranged in the reaction tank, the dielectric barrier discharge device comprises a high-voltage electrode which is positioned right above the reaction tank and is positioned in the reaction chamber and a barrier dielectric which is positioned between the high-voltage electrode and the tank opening of the reaction tank, and the reaction tank is directly grounded to be used as a low-voltage electrode of the dielectric barrier discharge device; the liquid level of the reaction tank is covered with a catalyst net which comprises a reticular carrier, the upper surface of the carrier is provided with a VOCs gas-phase reaction catalyst, and the lower surface of the carrier is provided with a VOCs liquid-phase reaction catalyst.

2. The multi-phase discharge system of claim 1, wherein: the catalyst net floats on the liquid level of the alkaline solution in the reaction tank.

3. The multi-phase discharge system of claim 1, wherein: the VOCs gas phase reaction catalyst comprises at least one transition metal ion.

4. The multi-phase discharge system of claim 1, wherein: the VOCs liquid phase reaction catalyst is a Fenton reaction catalyst.

5. The multi-phase discharge system of claim 1, wherein: the carrier of the catalyst net is made of Al₂O₃And (4) preparing.

6. The multi-phase discharge system of claim 1, wherein: the alkaline solution is NaHCO₃The pH value of the aqueous solution is 8-9.

7. The multi-phase discharge system of claim 1, wherein: the reaction tank is also connected with a pH value detector and a circulating device, the pH value detector can detect the pH value of the alkaline solution in the reaction tank, and the circulating device can circularly supplement the alkaline solution in the reaction tank.