CN1513753A - Method of producing sulfuric acid using hydroxg oxidation of sulfur dioxide - Google Patents

Abstract

A process for preparing sulfuric acid by using hydroxy radical to oxidize SO2 includes using discharge electrode, ground electrode, dielectric layer and partition to form a discharge gap, applying an AC voltage to create a discharging electric field and generate spark and arc discharge, flowing fume through the ionizing region to generate hydroxy radicals, oxidizing the SO2 in fume to become sulfuric acid microdrips, and collecting them to obtain sulfuric acid.

Description

Method for generating sulfuric acid by oxidizing sulfur dioxide with hydroxyl

Technical Field

The invention belongs to the technical field of gas ionization discharge and plasma chemistry application, and relates to a method for generating sulfuric acid by oxidizing sulfur dioxide with hydroxyl.

Technical Field

In the 80 s, physicists began to focus on some problems to be solved urgently in acid rain management methods, and attempted to solve dry-type SO recovery by extreme physical means₂The problem of difficulty in the method. In the middle of the 80 s, people who increased field and were treated with Qingmu Ding and the like began to study on the generation of OH by using a gas ionization discharge method^*、HO₂Etc. in place of the catalyst. In 1990, dry desulfurization method for recovering ionized flue gas by electron beam method was proposed by Nippon atomic force research institute, Tong gun, Qingmu Ding et al. Applying high voltage to accelerate electrons in vacuum cavity to obtain energy of 100-800 eV, passing through 20-40 μm thick titanium window with vacuum sealing function, exciting gas in flue at normal pressure to remove O in flue gas₂、H₂O, etc. to OH^*、HO₂、O(^ID) Adding NH at 65-80 deg.C with equal free radicals₃After generation of (NH)₄)₂SO₄And then recovered by an electric dust collector. 30X 10 times of the power plant of China institute of atomic force and Perilla Frutescens origin manufacturing³Nm³The electron beam desulfurization device of the flue gas is tested. Recently, it is planned to build 620 × 10 in Japan⁴Electron beam desulphurization unit of kW generating set. The electron beam method solves the problem of high-temperature catalyst poisoning, but the electron accelerator and the vacuum system have huge equipment and high primary cost; the titanium target window is too thin, and the internal and external pressure difference is too large, and SO₂The corrosion effect is easy to damage; in case of damage of X-ray radiation, an anti-radiation cement layer with the thickness of 1m-2m needs to be arranged outside the reflection system; treating an SO₂The molecule needs about 40eV energy and consumes energyLarge, due to the need of adding an absorbent NH₃In the presence of NH₃Supply, transportation, leakage prevention, explosion prevention and the like. The generated ammonium salt is not a high-efficiency fertilizer and has the problem of market sale.

In order to solve some defects of the electron beam method, the chemical desulfurization technique by high voltage narrow pulse corona discharge plasma generation was proposed by Zeta Kangshang et al in 1990, the desulfurization by discharge method was also studied by Entakov et al, the institute of electronic technology integration, Japan, and the desulfurization by pulse discharge was also studied by Young Sun Mok et al, 2001. They are intended to use high voltage pulsed corona (streamer) discharge electricfields instead of electron accelerators and vacuum sealing systems in order to overcome some of the disadvantages of electron beam desulfurization. Since the electric field intensity of the pulse discharge is only about 20kV/cm, the average energy obtained by electrons is only 2 eV. The electron energy in the discharge electric field is distributed according to Maxwell rule and can reach ionization O₂The electrons having a molecular energy of 12.6eV occupy only a few percent. That is to say only a few percent SO₂Is covered with OH^*Isoradical oxidation to H₂SO₄And then with NH₃Function to generate (NH)₄)₂SO₄The rest products are gaseous ammonium sulfite (at the temperature of more than or equal to 54 ℃), and sulfite can not be recovered under the high-temperature condition. Notice from Tokyo university, Cissus and Liu Shuhai et al, 1995, indicated that the pulsed corona discharge plasma chemical desulfurization process was a thermochemical reaction, with the product being ammonium sulfite (NH)₄)₂SO₃Ammonium sulfite is a gas at flue gas temperatures greater than 54 c, and is not recoverable at these temperatures. In the atmosphere (NH)₄)₂SO₃Will be decomposed into SO₂、NH₃When harmful gases are produced, on the contrary, aggravateAnd (4) flue gas pollution. In 2000, the research report by Zhang Tao et al indicates that the smoke temperature is 64 ℃ and the narrow pulse high voltage SO₂The removal rate reaches 90%, the recovery rate of ammonium salt is only 8.2%, and more than ninety percent of gaseous ammonium sulfite salt is exhausted. In 2000, Mao Ben et al also indicated the pilot plant of pulsed corona discharge desulfurization (12000 m)³A number of similar problems were also found in the/h) process.

Recently, many scholars propose a dielectric barrier discharge method to obtain a Dielectric Barrier Discharge (DBD) solution satisfying SO in flue gas₂Oxidation to H₂SO₄Required OH^*、HO₂、O(^ID) And the like. Moo bee Chang et al conducted dielectric barrier discharge desulfurization studies simulating flue gas in 1991. The flue gas stays for 2S in the plasma reaction chamber, and the consumed energy is 28Wh/m³The removal rate is only 20%, and the method does not use a catalyst or an absorbent in a dry manner, but also has the problems of too long retention time, large energy consumption and the like. In order to solve the problems, the method provides a method for strengthening the flue gas ionization process by additionally applying ultraviolet radiation on the basis, and has the problem that the engineering cannot be implemented although the desulfurization rate is improved. Similar research work was done in 1992 by Manabu Higashi et al, and the above problems were likewise not solved. In 2000, EAFilimonova et al conducted basic research on chemical models of pulsed discharge and dielectric barrier discharge SO2 removal, and they pointed out that the average discharge electric field intensity and streamer duty cycle (streamer volume/discharge space volume) of dielectric barrier discharge are 10 times and more than 100 times higher than those of pulsed corona discharge. While the dielectric blocks the discharged SO₂The removal rate only reaches 28 percent, and the requirement of coal-fired flue gas desulfurization efficiency cannot be met. In 2002, Hongbin Ma et al used a dielectric barrier discharge method to research desulfurization, and they wanted to solve the problems of pulsed corona discharge desulfurization by using the dielectric barrier discharge method, so as to replace the electron beam method to perform flue gas desulfurization. In the absence of NH₃When, SO₂The removal rate is only 10 percent, and NH is added₃When, SO₂The removal reaches 90 percent, the desulfurization efficiency is basically similar to that of the pulsed corona discharge desulfurization, and the problems in the pulsed corona discharge desulfurization and electron beam desulfurization methods are not solved.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for oxidizing sulfur dioxide to generate sulfuric acid by hydroxyl, which has the advantages of short process flow, high efficiency and no environmental pollution. Accelerating electron ionization and decomposing gas molecules by studying strong electric fieldBased on the basic theory and method, a non-equilibrium plasma reaction chamber with high temperature (more than or equal to 200 ℃) is established. By using an extreme physical method and a special processing technique, the average electric field intensity of a discharge electric field formed in plasma is more than 160kV/cm, the intrinsic electric field intensity of a streamer head is more than 400kV/cm, and the medium with the average energy of electrons being more than 13eV blocks strong ionization discharge, so that most of O in the smoke can be discharged₂、H₂O、N₂Ionization, ionization decomposition, decomposition adhesion, charge exchange, etc., and processing into high concentration OH on molecular level^*、e_aq ^-Free radicals (hydrated electrons) and the like can react SO at the temperature of 70-200 ℃ in the presence of catalyst and absorbent₂Direct oxidation to H₂SO₄The liquid particles are collected by a pre-charged, wide-pole-distance electric acid collector. Provides a new method for flue gas desulfurization resource with dry resource, no secondary pollution and low energy consumption for treating acid rain disaster.

The technical scheme adopted by the invention for solving the technical problem is as follows: a discharge gap is formed by a discharge electrode, a grounding electrode, a dielectric layer and a spacer, then an alternating voltage is applied to the discharge electrode, and a discharge electric field with the electric field intensity of 300Td-600Td is established in the discharge gap. The dielectric layer is used for blocking the alternating electric field to generate spark and arc discharge, so that streamer discharge is formed in the discharge gap to generate plasma, and water and oxygen containing gas are generated when passing through the ionization regionHydroxyl, hydroxyl being O of the gas (flue gas)₂、H₂After O ionization, decomposition ionization and charge exchange reaction, the resultant is processed into hydroxyl radical, which oxidizes the sulfur dioxide in gas into sulfuric acid particles, which are recovered by an electric acid mist collector and finally coalesced into sulfuric acid in the electric acid mist collector. The electric acid mist collector consists of corona electrode, mist collecting electrode, insulator, DC high voltage power supply, casing, sulfuric acid storing tank and valve. An electrostatic field is formed between the corona electrode and the mist collecting electrode, corona discharge is generated on the corona electrode, acid mist is aggregated into large fog drops under the action of the electric field, and the acid mist is collected on the mist collecting electrode under the action of the electric field, is aggregated into large acid drops and is finally collected in the sulfuric acid storage tank to form sulfuric acid. WhereinThe power frequency of the alternating voltage is 400Hz-10000 Hz; a dielectric layer is arranged on the surface of the discharge electrode, the surface of the grounding electrode or in the middle of the discharge gap and is made of ceramic, glass or enamel; the discharge electrode, the grounding electrode andthe dielectric layer are tubular and flat. The method comprises the following specific steps:

1. adopting cold plasma spraying technology to spray α type Al with high insulating strength (greater than or equal to 400kV/cm), high dielectric constant (greater than 10) and water absorption of 0 value₂O₃The superfine powder is sprayed and smelted on the surface of electrode to form a compact dielectric layer without air gap on the surface, which can prevent spark discharge and arc discharge so as to obtain strong ionization discharge of coal-fired flue gas. The electric field intensity of the high-voltage gas ionization discharge electric field is 4 times higher than that of the existing high-voltage gas ionization discharge electric field (10kV/cm-45kV/cm), and reaches more than 160 kV/cm. The strong ionization discharge intensity is far greater than other discharge modes.

2. High-energy electrons are obtained.

The average energy taken by the electrons in the plasma from the applied electric field depends on the discharge electric field strength and gas concentration. When the reduced average electric field intensity E/n of strong ionization discharge is greater than or equal to 600Td (characteristic parameter of gas discharge, 1Td is 10)^-17V·cm²) The majority of electrons can obtain energy from the electric field more than 13eV, and the energy of the electrons in the plasma is distributed according to Maxwell law, wherein most of the electrons have energy higher than O₂、N₂、H₂Ionization and decomposition energy of O is sufficient to make H₂O、O₂The active particles are ionized and decomposed into electrons, ions, atoms, excited state atoms (molecules), fragments and the like, and abundant basic active particles are provided for processing hydroxyl groups.

3. Plasma reaction process to obtain hydroxyl radical.

Electrons and H with low energy (2eV-10eV)₂O in inelastic Collision, OH^*Can be produced only by the following decomposition adhesion, decomposition reaction and the like. The reaction formula is as follows:

at O (^ID) Under the action of H₂Decomposition reaction of O:

low energy (weak ionization discharge) electrons and H₂The O molecules undergo inelastic collisions. The number of decomposition ionization reaction is 0.3 and 0.4 respectively when 100eV excitation energy is input. OH in the discharge of ionized gases in a strong electric field^*Mainly composed of positive ions and H₂Generated by O reaction, electrons have average energy more than 13eV and more than O in the process of ionizing gas discharge by a strong electric field₂The ionization energy of the molecule is 12.5eV, and oxygen molecules undergo a large number of ionization, decomposition and charge exchange reactions:

n can likewise be obtained₂ ⁺、H₂O⁺And N⁺、H⁺And (3) plasma. They undergo charge exchange reactions with gas molecules as follows:

formation of the hydrated ion is represented by the formula:

the main route for generating hydroxyl is generated by the decomposition of hydrated ions, and the reaction formula is as follows:

in strong ionization discharge, the average energy of electrons obtained from electric field is more than 13eV, and the oxygen molecule is electrically charged per 100eV input

The ionization and decomposition ionization numbers are respectively 2.07 and 1.23, which are 12 times and 769 times of weak ionization discharge reaction numbers. Can be used for

See OH^*Mainly composed of positive ions and H₂Produced by the reaction of O to produce OH^*How much depends mainly on the average momentum of electrons.

To obtain high concentration of OH^*Only the strong ionization discharge method is possible. We now know that high concentrations of hydroxyl radicals are obtained

Method of radical formation, OH^*The concentration reaches more than 10mg/L, and the OH meeting the requirement of flue gas desulfurization^*Concentration values.

Electrons with high energy excite water molecules, and the following reactions occur:

from the reaction formula, OH is generated simultaneously^*、H^*And e_aq ^-(hydrated electrons) and the like. Every input 100eV, can

2.70 OH groups were generated^*And 2.75 e_aq ^-

4. Generation of H₂SO₄Plasma chemical reaction.

Secondary generation of H₂SO₄Plasma chemical reaction of (2):

5. and (5) recovering sulfuric acid mist.

In a strong high-voltage electrostatic field, ultrafine acid mist particles collide with negative ions for charging in 1/100 s. In a strong electrostatic field

Under the action of field, the coagulation of charged acid fog particles is strengthened, the particle size is increased by more than 20 times, and the charged acid is greatly improved

The driving speed of the fog particles promotes the acid fog to be completely driven to a fog collecting electrode of an electric fog collecting device, so that the ultra-fine acid fog can be returned

And (7) collecting.

6. The technological process of the strong ionization discharge flue gas desulfurization resource test.

The coal-fired flue gas volume is 400m³The experimental process flow of the strong electric field ionization discharge desulfurization resource method is shown in figure 1, the flue gas for the experiment is prepared into the flue gas component and the concentration value thereof required by the experiment in a gas distribution chamber 1, the flue gas generates high-concentration hydroxyl in a plasma reaction chamber 4, and then the hydroxyl and SO in the flue gas generate₂Act to form ultrafine particles H₂SO₄And (4) atomizing. The sulfuric acid is recovered into liquid sulfuric acid in a wide-polar-distance electric acid collector 5 with a pre-charging component.

The invention has the beneficial effects that:

1. the flue gas is treated by adopting an extreme physical means of high-frequency dielectric medium for blocking strong electric field discharge to accelerate electrons and exciting gas molecules

Middle O₂、H₂O is ionized and decomposed into OH^*And HO₂、O(^ID) Etc. active particles of OH^*The specific concentration reaches 10mg/L

Above, satisfy SO₂Direct oxidation to H₂SO₄Desired hydroxyl group concentration value.

2. The first realization is that the SO can be directly extracted within 1 mu s₂By oxidation to H₂SO₄The whole chemical process flow is completed within a distance of only 2 m. Is producing H worldwide₂SO₄The chemical reaction process flow is the shortest and the chemical reaction time is the fastest.

3. The method has the advantages of no need of catalyst, no absorbent and no additional additionUnder other external conditions, SO can be converted only by hydroxyl generated by strong ionization discharge₂Oxidation to produce chemical important raw material H₂SO₄. No by-product and new pollutant are produced, and no negative effect is produced to the environment. Provides an innovative resource method for coal-fired flue gas desulfurization.

Drawings

The invention is further illustrated by the following figures and examples.

FIG. 1 is a process flow of the strong ionization discharge flue gas desulfurization resource process of the present invention.

Fig. 2 is a schematic view of the configuration of the electric acid mist collector.

FIG. 3 is a schematic diagram of a plasma reaction chamber configuration.

FIG. 4 is a graph of plasma reaction time versus SO₂The removal rate is plotted.

FIG. 5 is SO₂Concentration versus removal rate.

FIG. 6 is H₂Concentration of O to SO₂The removal rate is plotted.

In fig. 1: 1. humidifying tower, 2 flow meter, 3 temperature and humidity regulator, 4 plasma reaction chamber, 5 electric acid collector

Fog machine, 6. induced draft fan, 7. high frequency high voltage power supply controller, 8. inverter, 9. transformer, 10. DC high voltage power supply controller

And a generator 11, a direct current high voltage generator.

In fig. 2: 12. insulator, 13 corona electrode, 14 mist collecting electrode, 15 acid drop, 16 sulfuric acid storage tank, 17 sulfuric acid,

18. valve, 19 casing, 20 DC high voltage power supply.

In fig. 3: 21. ground 22 discharge plate (discharge + dielectric), 23 spacer, 24 dielectric.

Detailed Description

The strong ionization discharge flue gas desulfurization resource process flow is as followsShown in FIG. 1, SO₂、H₂O and flue gas are added into a humidifying tower 1 to be prepared into experimental gas, the flow of the gas is detected by a flow meter 2, the experimental gas is subjected to temperature and humidity control in a temperature and humidity adjusting device 3 and then enters a plasma reaction chamber 4, plasma chemical reaction is carried out in a plasma reactor to generate hydroxyl radicals, and SO is directly added into the experimental gas₂Direct oxidation to form mist H₂SO₄The particles are recovered by an electric acid collecting mist device 5, and the treated flue gas is discharged by a draught fan 6. The high-frequency high-voltage power supply controller 7, the inverter 8 and the transformer 9 form a high-voltage high-frequency power supply for supplying power to the plasma reaction chamber. The dc high voltage power controller 10 and the dc high voltage generator 11 are used to supply power to the electric acid collector 5.

The electric acid mist collector 5 in fig. 2 is composed of a corona electrode 13, a mist collecting electrode 14, an insulator 12, a direct-current high-voltage power supply 20, a shell 19, a sulfuric acid storage tank 16 and a valve 18. An electrostatic field is formed between the corona electrode and the mist collecting electrode, corona discharge is generated on the corona electrode, acid mist is electrically coagulated into large mist drops under the action of the electric field, and the large mist drops are collected on the mist collecting electrode under the action ofthe electric field, condensed into large acid drops 15 and finally collected in a sulfuric acid storage tank 16 to form sulfuric acid 17.

FIG. 3 is a structural view of a plasma reaction chamber in the present invention, which is mainly composed of a discharge electrode plate 22, a ground electrode 21, a dielectric layer 24 and a spacer 23.

Plasma reaction time and SO₂The relationship between the removal rates is shown in fig. 4. O is₂Concentration 21.5% (v/v), H₂O concentration of 4.0% (v/v), SO₂The concentrations are respectively 8.00X 10^-4(v/v)、4.00×10^-4(v/v) with increasing plasma reaction time, SO₂The higher the removal rate: at a reaction time of 0.25s, with SO₂The concentration is from 4.00X 10^-4(v/v) increased to 8.00X 10^-4(v/v), the removal rate is reduced by 14.0%; with SO, the plasma reaction time is 0.73s₂The concentration is from 4.00X 10^-4(v/v) increased to 8.00X 10^-4(v/v), the removal rate was reduced by 30.0%. It can be seen that, in SO₂At high concentrations, if desired with SO₂At the same removal rate at a low concentration, the reaction time should be appropriately prolonged. In SO₂Is 4.00X 10^-4(v/v) condition SO₂The removal rate reaches 84.0 percent at most. This is due to the increased SO content of the flue gas as a result of the prolonged plasma reaction time in the reactor₂Molecule and OH^*The collision probability of the active particles is equal, resulting in more O₂The molecules are ionized to produce more water ions and more SO₂The molecule is oxidized to H₂SO₄And (4) microdroplets.

SO₂The results of the experiments on the removal rate as a function of its concentration are shown in FIG. 5, where SO₂Theexperimental conditions for the effect of concentration on the removal rate are shown in table 1. As can be seen from the graph, with SO₂The removal rate gradually decreased with increasing concentration, as shown in curve 1, at a flow rate of 0.1m³/h，H₂O concentration of 1.2% (v/v), O₂At a concentration of 21.0% (v/v) in terms of SO₂The concentration is from 2.98X 10^-4(v/v) increased to 10.5X 10^-4(v/v), the removal rate is reduced from 76.4% to 18.3%, and the removal rate is reduced by 58.1%; as can be seen from the curve 3, the flow rate was 0.2m³/h，H₂O concentration of 0.3% (v/v), O₂At a concentration of 49.5% (v/v) in terms of SO₂The concentration is from 2.35X 10^-4(v/v) increased to 9.83X 10^-4(v/v), the removal rate decreased from 68.5% to 28.0%, which was 40.5% lower. Visible, SO₂The influence of the initial concentration on the removal rate is large.

SO₂Same concentration of H₂The larger the O concentration, the higher the removal rate, and SO can be seen from the curves 1 and 2₂The concentration is 2.90×10^-4(v/v) is, H₂The O concentration is increased from 0.3% (v/v) to 1.2% (v/v), and the removal rate is increased by 57.4%; SO (SO)₂The concentration is 9.60 × 10^-4(v/v) with H₂Increase in O concentration, SO₂The removal rate is only increased by 10%. It can be seen that, in SO₂At low concentration, H₂The influence of the O concentration on the removal rate is also considerable. At H₂O concentration of 1.2% (v/v), SO₂The concentration is 2.89X 10^-4(v/v) ConditionThe maximum removal rate reaches 76.4 percent.

In SO₂At the same concentration, O₂The higher the concentration, the greater theremoval rate, as can be seen from curves 3 and 4, when SO is present₂The concentration is 4.00X 10^-4(v/v) with O₂The concentration is increased from 21.0% (v/v) to 49.5% (v/v), and the removal rate is increased by 48.0%; when SO₂The concentration is 10.00X 10^-4(v/v) with O₂The removal rate is only increased by 23.0 percent due to the increase of the concentration. Can be seen in SO₂At low concentration, O₂Concentration to SO₂The removal rate is greatly influenced. O is₂Concentration of 49.5%, SO₂The concentration is 2.35X 10^-4(v/v), the removal rate reaches 74 percent at the maximum.

From the above results, it can be seen that: SO in flue gas₂Concentration decrease at the same H₂In the case of O concentration or oxygen content, more SO is produced₂The molecule is oxidized to form H₂SO₄(ii) a H in flue gas₂The increase of the O concentration greatly increases the generation probability of hydrated ions and increases OH^*In such a concentration that more SO is present₂Molecule is oxidized by H₂SO₄Mist particles; increase of oxygen content in flue gas, more O₂The molecule can be decomposed and ionized into O₂ ⁺And O (^ID) Isoactive particles of H and₂the O molecules and the like generate a large amount of hydrated ion clusters O by collision₂ ⁺(H₂O), thereby increasing OH^*Amount of production of, SO₂Molecule and OH^*SO that more SO is generated₂The molecule is oxidized to H₂SO₄Liquid fine particles.

TABLE 1 Experimental conditions

Gas composition [% (v/v)]

Curved flow

H₂O O₂N₂

Marker [ m]³/h]

[％(v/v)][％(v/v)][％(v/v)]

1： 0.1 1.2 21.0 77.8

2： 0.1 0.3 21.0 78.7

3： 0.2 0.3 49.5 50.2

4： 0.2 0.3 21.0 78.7

SO₂Removal rate and H₂The results of the O concentration experiments are shown in fig. 6. O is₂The concentration was 21.0% (v/v), the flow rate was 0.1m³/h，SO₂The concentration is 8.20X 10^-4(v/v). From the graph, it can be seen that in H₂O concentration of 0% (v/v) to 4.0% (v/v), rapid increase in desorption, in H₂The removal rate reached 48.4% at an O concentration of 4.0% (v/v), thus showing that H₂Concentration of O to SO₂The inflection point of the influence of the removal rate is 4.0% (v/v), and the SO larger than the inflection point₂The removal rate is a constant. In the case of strong ionization discharge, H₂The O concentration should be selected to be 4.0% (v/v).

The high-concentration OH meeting the requirement of flue gas desulfurization can be obtained by adopting an extreme physical means of a strong ionization medium for blocking strong electric field discharge to accelerate electrons and exciting gas molecules^*The active particles effectively solve the problem of directly adding SO under the conditions of high temperature, no catalyst, no absorbent and any other substances₂The oxidation is carried out to H, which is a dry type resource method without secondary pollution and with low energy consumption.

Claims (7)

1. A process for preparing sulfuric acid by oxidizing sulfur dioxide with hydroxy radical includes such steps as generating discharge gap by discharge electrode, grounding electrode, dielectric layer and isolating plate, applying AC voltage to the discharge electrode, creating discharge electric field with electric field intensity of 300-600 Td, using dielectric layer to block the AC electric field to generate spark and arc discharge, generating streamer discharge in the discharge gap, generating plasma, generating hydroxy and hydrated electron radicals, oxidizing sulfur dioxide in gas to become sulfuric acid particles, recovering acid mist by acid mist collector, and finally collecting sulfuric acid in acid mist collector.

2. The process of claim 1, wherein the acid mist collector comprises a corona electrode, a mist collector, an insulator, a dc high voltage power supply, a housing, a sulfuric acid storage tank, and a valve, wherein an electrostatic field is formed between the corona electrode and the mist collector, corona discharge occurs at the corona electrode, and the acid mist is electrically coagulated into large mist droplets under the action of the electric field, and the large mist droplets are collected on the mist collector under the action of the electric field, condensed into large acid droplets, and finally collected in the sulfuric acid storage tank to form sulfuric acid.

3. A method of oxidizing sulfur dioxide to sulfuric acid as claimed in claim 1 wherein said alternating voltage has a power frequency of 400Hz to 10000 Hz.

4. A process for the oxyhydroxide formation of sulfur dioxide into sulfuric acid as claimed in claim 1, wherein the hydroxyl group is O in a gas (flue gas)₂、H₂And after O ionization, decomposition ionization and charge exchange reaction, processing the product into hydroxyl and hydrated electron free radicals according to the structures of hydroxyl and hydrated electrons.

5. A process for the oxidation of sulfur dioxide by hydroxyl radicals to sulfuric acid as claimed in claim 1, wherein the surface of the discharge electrode, the surface of the ground electrode, or the middle of the discharge gap is provided with a dielectric layer.

6. A method of oxidising sulphur dioxide with hydroxyl groups to sulphuric acid according to claims 1 and 5, characterised in that the dielectric layer is made of a ceramic, glass or enamel.

7. A method of oxidizing sulfur dioxide to sulfuric acid as claimed in claims 1 and 5, wherein said discharge electrode, ground electrode and dielectric layer are in the form of tubes or plates.

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