KR20080097365A - Apparatus for removal of nox, sox and dioxins by mediated electrochemical oxidation - Google Patents

Abstract

An apparatus for Removal of toxic gas by Mediated Electrochemical Oxidation is provided to process the toxic gas such as NOx, SOx and dioxin efficiently by increasing an oxidation efficiency of the toxic gas and to diminish an initial equipment investment cost by simplifying the apparatus. A gas-solid contact intermediation oxidation scrubber(10) is filled with filler. The filler is disassembled by an intermediation ion in which the flowed toxic gas is oxidized. An intermediation ion introduction tube(11) is connected on an upper part of the gas-solid contact intermediation oxidation scrubber. The intermediation ion introduction tube sprays the intermediation ion oxidized in the anode room(41) of an electrolytic cell(40). A toxic gas introduction tube(12) introduces the toxic gas mixture at a lower part of the gas-solid contact intermediation oxidation scrubber. The electrochemical intermediation oxidation hazardous gas control apparatus oxidizes and removes the toxic gas by contacting the toxic gas mixture introduced from the toxic gas introduction tube with the intermediation ion oxidized in the gas-solid intermediation oxidation scrubber.

Description

Apparatus for Removal of NOx, SOx and Dioxins by Mediated Electrochemical Oxidation}

The present invention relates to an apparatus for mediating oxidation of harmful gases such as NOx, SOx and dioxins by electrochemical mediation. That is, the sustainable hazardous gas clean treatment technology using the electrochemical mediated electrochemical oxidation (MEO) according to the present invention can be applied to the treatment of harmful gases such as NOx, SOx and dioxins generated throughout the industry. It is a clean process technology that can be applied to a wide range of hazardous gas treatment fields such as incineration flue gas, livestock and domestic wastes and odors generated from chemical processes or VOCs.

     Most of the technologies currently applied to the treatment of harmful gases rely on catalytic reduction technology. Recently, treatment processes using plasma, ion beam, biofilter, and photocatalyst have been studied, but such conventional treatment techniques include various components. It is difficult to treat the harmful gases at the same time, and the use of high cost and limited lifetime catalysts not only increases the operating cost, but also a major problem to be solved by the secondary pollutants due to used catalysts, absorbents and adsorbents.

In addition, gaseous harmful substances have recently been generated in various chemical processes, and environmental standards have been strengthened, and attention has been given to them. However, the treatment is very difficult, and it is mainly limited to removal by adsorption or thermal incineration. In addition, a lot of energy and costs are generated, and the removal efficiency is not satisfactory with the difficulty of securing the site of the incinerator.

In order to solve the above problems, the present invention develops an apparatus for performing gas-liquid contact using the oxidized mediated ions while performing a reaction for oxidizing the reduced mediated ions during the mediated oxidation process through an electrochemical mediated oxidation method. By doing so, the invention has been invented a device for removing gas-liquid contact harmful gas substances using a mediated oxidation method that has not been developed in the past.

The present invention can increase the oxidation efficiency of harmful gases by performing the gas-liquid contact in the integrated gas-liquid contact mediated oxidation scrubber to efficiently handle the non-degradable harmful gases, the device is simple, can be installed in a narrow place The present invention aims to provide an environmentally friendly treatment apparatus and method with excellent initial investment and ease of operation.

The present invention is fundamentally different from the existing applied technology and the researched technology, a technology capable of treating harmful gases by using a medium metal ion having a strong oxidizing power, the present technology is to oxidize harmful gases as shown in FIG. It is a revolutionary technology that completely oxidizes by direct oxidation by gas-liquid contact with the mediator metal ions (Ce ⁴⁺ , Ag ²⁺ ) in the state. The noxious gas to be treated in the present invention is preferably NOx, SOx, Dioxins, volatile organic compounds (VOCs) or mixtures thereof, and more preferably NOx, SOx, Dioxins, or mixtures thereof.

In addition, the medial metal ions used in the treatment of harmful gases can be repeatedly used in the electrolysis cell together with the electrolyte solution, so that the medial metal ions need not be replenished and exchanged. Therefore, this technology is a sustainable toxic gas clean treatment technology that can be operated only by supplying electric power without discharging secondary pollutants by sludge or waste oxidant during the treatment process.

That is, the present technology utilizes the strong oxidizing power of the mediated ions (M ^{n + 1} ) by oxidizing mediating metal ions such as Ce, Ag, Mn, Co, etc. dissolved in an acidic electrolyte solution by an electrochemical method. It is a technology that completely decomposes harmful gases into harmless substances.

Hazardous gases such as dioxins and VOCs are completely oxidized to CO ₂ and H ₂ O by mediated ions (M ^{n + 1} ), while NOx and SOx are oxidized to mediated ions (M ^{n + 1} ) It is absorbed into acidic electrolyte solution and processed. At this time, used in the harmful gas treatment reaction, the reduced mediated ion (M ⁿ ) is oxidized in the electrolytic cell and is continuously used as the mediated ion (M ^{n +1} ). Therefore, it is a sustainable next-generation clean processing technology that can clean the harmful gas while continuously oxidizing and reducing by power supply without supplying additional intermediate metal ions and electrolytes.

Unlike conventional catalyst reduction, absorption, and adsorption technologies, it is possible to process several gases simultaneously, obtain high treatment efficiency, replace the used catalyst, adsorbent, absorbent and discharge secondary pollutants. Low cost, high efficiency, continuous processing is possible.

NO, NO ₂ , SO ₂ and dioxin according to the present invention can be decomposed and treated, and the decomposition mechanism is not clearly known, but it is estimated to be decomposed by the following reaction. First, it is thought that metal ions are oxidized in the electrolysis cell to generate mediated ions, and the mediated ions are removed by oxidizing by gas-liquid contact with noxious gas or dioxin.

That is, M ^{n + 1} is generated by electrochemically oxidizing M ⁿ as in Formula (1) in the electrolytic cell. NO, NO ₂ and SO ₂ gases are oxidized as shown in equations (2), (3) and (4) and then scrubbed in an electrolyte solution with sulfuric acid and nitric acid. In the case of dioxins, the oxidized M ^{n +1} is completely oxidatively decomposed into harmless CO ₂ as shown in Formula (5), where M ⁿ is lost and reduced by reaction with NO, NO ₂ , SO ₂ and dioxins. is delivered to the continuous playback M ^{n +1} by again formula (1) in the cell can be a process of continuous toxic gas. As such, this technology is the key to clean the noxious gas in terms of zero emission, secondary pollution reduction, simultaneous treatment of multi-component noxious gas and development of sustainable processes.

Hereinafter, in order to examine the device of the present invention in detail, the device for the treatment of harmful gases in the mediated electrochemical oxidation (MEO) using Ce (IV) or Ag (II) as the mediation ion (Fig. 2) Will be described in detail.

The harmful gas used in the experiment is diluted to a constant concentration by controlling the flow rate by the MFC (Mass Flow Controller) 60 is supplied to the gas-liquid contact mediated oxidation scrubber 10 through the harmful gas introduction pipe (12).

Ce (III) or Ag (I) used as the mediation ion is, for example, the cathode chamber 42 by Nafion 324 as an electrolytic diaphragm 43 before being introduced into the scrubber 10 for the decomposition of harmful gases. And the anode chamber 41 is oxidized to Ce (IV) and Ag (II) by supplying a current to the separated electrolytic cell 40, the electrolytic cell 40 even while noxious gas is processed in the scrubber 10 Continued supply of current to the oxidative gas oxidative decomposition to continuously oxidize the intermediate metal ions reduced to Ce (III) and Ag (I), the decomposition of the organic gas by Ce (IV) and Ag (II) can proceed. Make sure

At this time, the size of the scrubber 10 is adjustable as necessary, for example, the inner diameter is 10cm, the height is 90cm, harmful gas by the anode (anolyte) containing Ag (II) and Ce (IV). The actual section is decomposed so that the gas and anode liquid (Anolyte) is sprayed from the upper side within 60cm of the height of the packing material (filling material) is filled in contact with the decomposition process. The fillers in the scrubber 10 are not easily decomposed by Ce (IV), Ag (II) and nitric acid electrolytes and are of any form and are not strongly related to any acid resistant and durable material, but are not related to, for example, teflon. By filling a series of fillers (Tri-Pack, PFA, Jaeger Products iNC.), The harmful gas mixture can be contacted with an electrolyte containing Ce (IV) and Ag (II) to treat the hazardous gas mixture. The material is more durable and recommended.

In addition, as harmful gases in the harmful gas mixture introduced from the upper portion of the scrubber 10, harmful substances such as nitrogen dioxide, nitrogen monoxide and dioxins are decomposed, but air and N ₂ , which occupy most of the gases introduced into the scrubber, It is discharged out of the scrubber as it is. At this time, in the gas discharged from the scrubber, water, medial metal ions or nitric acid may be discharged by the flow rate of the gas introduced into the scrubber, and moisture, medial metal ions or nitric acid may be discharged by the temperature of the anolyte in the scrubber. This can be evaporated and discharged out of the scrubber. If the water, medium metal ions or nitric acid are evaporated and discharged from the scrubber, the conditions of the initial anolyte for treating the noxious gas mixture will continue to change over time. Due to the lost intermediary metal ions and electrolytes, the treatment efficiency of NO can be reduced. Therefore, in order to prevent loss of moisture, medial ions or nitric acid due to the gas discharged from the scrubber 10, the heat exchanger or electrostatic precipitator 70 is connected to the scrubber to collect the vaporized moisture, medial metal ions or nitric acid. By returning back to the anolyte storage tank 20 to maintain the initial conditions of the anolyte (Anolyte), the harmful gas mixture is continuously treated with high processing efficiency.

In more detail, the device of the present invention will be described.

The device according to the invention receives electrons from the anode chamber 41 and the anode chamber 41 in which the reduced mediated ions flowing from the gas-liquid contact mediated oxidation scrubber 10 are oxidized by the current from the rectifier 30. An electrolytic cell 40 provided with a cathode chamber 42 for receiving a cathode liquid and an electrolytic separator 43 between the anode chamber 41 and the cathode chamber 42; The medium temperature inlet pipe 11 connected to the upper portion of the gas-liquid contact mediated oxidation scrubber 10 into which the oxidized medium ion is introduced in the anode chamber 41 and the harmful gas introduction pipe 12 connected to the lower portion of the scrubber and the upper portion of the scrubber Decomposition gas discharge pipe 13 connected to the outside; Is connected to the decomposition gas discharge pipe 13 is composed of a heat exchanger 70 or an electrostatic precipitator on the top of the scrubber to prevent the loss of water, medium metal ions or nitric acid due to the gas discharged from the scrubber 10, the harmful gas introduced It may be provided with an MFC (60) connected to the pipe (12) to regulate the harmful gas flow rate. It is also composed of an anode liquid storage tank (20) for storing the anolyte (anolyte) through the recovery pipe 14 is installed in the lower portion of the scrubber (10) to recover the mediated ions reduced by contact with the harmful gas, It consists of a catholyte storage tank (50) installed in order to balance the material and the node liquid storage tank (20).

Mediated ions is suitably a transition metal ion and, in particular, ^{Ce 3+, Ag +, Co 2+} , Ce 3+, Ag + in the operational surface of the first is preferable, and oxidizing power plane or step or more kinds selected from Mn ²⁺ More preferred is Ce (NO ₃ ) ₃ as the compound of Ce ³⁺ ions. The mediated ions are dissolved in nitric acid or sulfuric acid aqueous solution to oxidize the organic waste solution by mediated oxidation reaction, and then reduced. The mediated ions are oxidized by electrochemical method in the anode chamber 41 of the electrolytic cell 40 and circulated again. The concentration of the mediated ion is 0.5M to 1.6M, preferably 0.8M to 1.5M.

In the cathode chamber 42 of the electrolytic cell 40, the catholyte is reduced simultaneously with the oxidation of the intermediate ion in the anode chamber 41, and the catholyte solution is preferably HNO ₃ or H ₂ SO ₄ aqueous solution. .

At this time, the temperature of the intermediate oxidation reaction is performed at room temperature to 100 ° C, preferably 70 ° C to 100 ° C, and the operating temperature of the catholyte is preferably room temperature to 70 ° C.

The apparatus according to the present invention has the advantage of reducing the size of the mediated oxidation reaction tank by efficiently treating the harmful gas by gas-liquid contacting the harmful gas mixture using the electrochemical mediated oxidation method, and also has an integrated scrubber oxidation reactor. By applying the device, the device can be simplified, thus the initial device investment cost and ease of operation.

Hereinafter, the present invention will be described in more detail with reference to Examples, and the rights of the present invention are not limited to Examples.

<Example 1>

Anolyte was used to dissolve 1M Ce (III) and 3M HNO ₃ in distilled water to 2000ml, and catholyte was used as 1000M of 4M HNO ₃ . Each reactor and the scrubber were subjected to oxidation and NO treatment experiments of Ce (III) by maintaining a temperature of the anolyte at 80 ° C. using a heating jacket. At this time, the inner diameter of the scrubber is φ10cm, the height is 90cm, and the actual section in which NO is decomposed by the anolyte containing Ag (II) and Ce (IV) is the gas and the annolyte within 60cm of the filling material. Contact was allowed to decompose. Filler was filled with Teflon packing material (Tri-Pack, PFA, Jaeger Products iNC.) To better contact the NO mixed gas and the electrolyte containing Ce (IV) and Ag (II). As a carrier gas, air was controlled to adjust the flow rate of NO at a flow rate of 1.2 L / min such that the concentration of NO in the gas (Air + NO mixed gas) introduced into the scrubber was 500 and 450 ppm, respectively. At this time, the flow rate of the anolyte (Ce (III) + Ce (IV) + HNO ₃ + H ₂ O mixed solution) injected through the nozzle at the top of the scrubber was maintained at 2.25 l / min. After supplying 10A of current to the anolyte mixed with 1M Ce (III) and 3M HNO ₃ to oxidize Ce (III) by 92%, the flow rate of 1, 2L / min for the gas mixed with NO and air in the scrubber The decomposition rate of NO with time at 80 ° C. was measured while injecting. When the flow rate of the gas mixed with NO and air was 1L / min, the concentration of NO in the mixed gas was 500ppm, and in the case of 2L / min, the flow rate of NO was controlled by using MFC such that the concentration of NO was 450ppm.

As a result, as can be seen in Figure 3, it can be seen that NO is more than 85% decomposed by Ce (IV), the concentration of NO in the gas discharged from the scrubber can be treated below the NOx emission standard below 100ppm. And it was found. In addition, more than 95% of the water, the mediated metal ions, and nitric acid contained in the gas discharged from the scrubber were recovered through a heat exchanger. From the results, it can be seen that NO can be continuously processed by the MEO process using Ce.

<Example 2>

In the anolyte, 0.1M Ag (I) and 3M HNO ₃ were dissolved in distilled water to be 3000ml, and catholyte was used as 1000M of 4M HNO ₃ . In each reactor and scrubber, the temperature of the anolyte solution was maintained at 20 ° C to perform oxidation and NO treatment experiments of Ag (I).

The flow rate of NO was controlled at 1, 2 L / min of air, which is a carrier gas, so that the concentration of NO in the gas (Air + NO mixed gas) introduced into the scrubber was adjusted to be 520 and 490 ppm, respectively.

In this case, the same scrubber was used as in Example 1, and the flow rate of the anolyte solution (a solution mixed with Ag (I) + Ag (II) + HNO ₃ + H ₂ O) injected through the nozzle at the top of the scrubber was It was kept at 2.25 L / min. After supplying 10A of current to the anolyte mixed with 0.1M Ag (I) and 3M HNO ₃ to oxidize Ag (I) by 4% or more, the scrubber mixed gas of NO and air with 1, 2L / min It shows the decomposition rate of NO with time at 20 ℃ while injecting at the flow rate of. When the flow rate of the gas mixed with NO and air is 1L / min, the concentration of NO in the mixed gas was 520ppm, in the case of 2L / min was adjusted to the flow rate of NO using MFC so that the concentration of NO is 490ppm.

As a result, as shown in FIG. 4, NO could be decomposed more than 90% by Ag (II), and it can be seen that the concentration of NO in the gas discharged from the scrubber can be treated below the NOx emission standard at 50 ppm or less. there was. In addition, more than 95% of the water, the mediated metal ions, and nitric acid contained in the gas discharged from the scrubber were recovered through a heat exchanger. From the results, it can be seen that the NOO can be continuously treated by the MEO process using Ag.

1 is a schematic of the apparatus of the harmful gas medium oxidation process according to the present invention,

2 is a device configuration diagram of a harmful gas medium oxidation process according to the present invention,

3 is a graph showing the result of NO removal according to Example 1 of the present invention,

4 is a graph showing the result of NO removal according to Example 2 of the present invention.

-Explanation of symbols for the main parts of the drawings-

10: gas-liquid contact mediated oxidation scrubber 11: medium temperature entrance

12: harmful gas introduction pipe 13: decomposition gas discharge pipe

14: recovery tube 20: anolyte storage tank

30: rectifier 40: electrolytic cell

41: anode chamber 42: cathode chamber

43: electrolytic diaphragm 50: catholyte storage tank

60: MFC (Mass flow controller) 70: heat exchanger

Claims (4)

A gas-liquid contact mediated oxidation scrubber filled with a filler, wherein the introduced harmful gas is oxidized and decomposed by an oxidized intermediate ion; A medium metal oxide introduction pipe connected to an upper portion of the gas-liquid contact mediated oxidation scrubber and spraying a medium ion generated in an anode chamber of an electrolysis cell; Toxic gas introduction pipe for introducing harmful gas from the lower end of the gas-liquid contact mediated oxidation scrubber; An anode liquid storage tank for storing the anolyte solution and injecting the anolyte solution into the anode chamber of the electrolytic cell from a gas-liquid contact mediated scrubber through a recovery tube for recovering the mediated ions reduced by the harmful gas contact; A catholyte storage tank for matching material balance with the anolyte storage tank; And A heat exchanger connected to the decomposition gas discharge pipe provided on the upper portion of the gas-liquid contact mediated oxidation scrubber to collect water, mediated metal ions or nitric acid discharged from the gas-liquid contact mediated oxidation scrubber, and to recover the anode liquid reservoir; Electrostatic precipitator; Harmful gas treatment apparatus by electrochemical mediated oxidation having a. The method of claim 1, The electrolytic cell is composed of an anode chamber, a cathode chamber and an electrolytic diaphragm, and the current is supplied by a rectifier to oxidize the intermediate ions, characterized in that the electrochemical mediated oxidation treatment apparatus. The method of claim 1, The mediator ion is Ce ³⁺ , Ag ⁺ , Co ²⁺ or Mn ²⁺ , the anolyte and the catholyte is an electrochemical mediated oxidation treatment device, characterized in that the aqueous solution of nitric acid or sulfuric acid. The method according to any one of claims 1 to 3, The noxious gas is NOx, SOx, Dioxins (Dioxins), volatile organic compounds (VOC) or a mixture of the harmful gas, characterized in that the apparatus for treating harmful gases by electrochemical oxidation.

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