KR100254034B1 - Public nuisanci gas process method by corona discharge plasma and apparatus thereof - Google Patents

Abstract

PURPOSE: Disclosed is a flue gas treatment equipment using a corona discharge plasma, which generates a cyclotron motion to lengthen the movement path of electron in electrodes and to increase the collision frequency of the electron and the molecule of pollutant gas. The equipment reduces the electron traveling degree of reverse direction of electric field. CONSTITUTION: The equipment using a corona discharge plasma is composed of a plasma reactor(21) which applies magnetic field at a right angle to electric field, an electricity power supplier(24) to supply electricity into the plasma reactor(21), a gas feed system(23) to deliver the pollutant gas (nitric oxide) into the reactor(21), and a gas analyser(22) to measure the concentration of the pollutant gas. To generate the electric discharge, a rotate spark gap switch is used in the electric power supplier(24). In addition, a pair of transparent acrylic resin in the reactor(21) contains a high voltage electrode in opposition to a grounding electrode, and also has a permanent magnet in a different polarity.

Description

Pollution Gas Treatment System by Corona Discharge Plasma

The present invention relates to an apparatus for treating pollution gas by corona discharge plasma, and in particular, by applying a magnetic field perpendicular to the direction of the electric field in a space to which an electric field is applied for discharging, thereby lengthening the entire motion path of electrons between electrodes by a cyclone motion. The present invention relates to an apparatus for treating pollution gas by corona discharge plasma which increases the number of collisions with molecules and increases the number of collisions, thereby increasing the efficiency of removing the molecules, and reducing power consumption by reducing electron mobility in the opposite direction to the electric field.

In general, when a sufficiently high voltage is applied to two electrodes in a gas medium, the atoms and molecules of the medium are electrically decomposed by an electrical discharge phenomenon to form electron-ion pairs and become electrically conductive.

The breakdown of the gas by discharge is the ionization of a conductor with resistance as low as 103 ohms.m from a low electrical conductor with a resistance of 1014 ohms.m (resistance x area / separation). It turns into a gas state. The potential difference between the two electrodes where this conversion occurs is called the breakdown potential (Vb) and depends on the type of gas, electrode material, distance between electrodes, gas density and degree of ionization. The decomposition of the gas produces positively and negatively charged electrons, which cause the electric field generated between the electrodes to accelerate positive and negatively charged ions and electrons to the cathode and anode, respectively. At this time, the charged particles are further generated through the collision process with the discharge gases in the discharge tube, the density of electrons and ions increases in the reaction tube, and the same amount of negative and positive charges exist. This is called plasma.

In the contaminated gas treatment by the electric discharge plasma, direct current, alternating current, pulse, and high frequency power are applied to the discharge electrode in the reaction apparatus. In this case, the electrons emitted from the negative electrode and the electrons and ions emitted during the discharge process are respectively directed in the direction of the electrode. As a result, the process proceeds at an equivalent acceleration straight line to decompose and collide with nitrogen oxides (NOx), sulfur oxides (SOx) and other polluting molecules to treat polluted gases.

In general, NOx and SOx generate acid rain, and CO ₂ and CH ₄ form a temperature reversal layer due to the greenhouse effect, which is a major cause of global warming. Recently, as air pollution becomes more serious, treatment of these emissions becomes more important. It is becoming.

Conventionally, the method of converting these gases into harmless gases (H ₂ O, H ₂ , O _2, etc.) and the conversion of acidic gases and greenhouse gases into renewable materials (agricultural fertilizer, Dry ice, calcium chloride, calcium fluoride, ammonium sulfate aerosol and the like).

In addition, various conventional corona discharge reactors such as coaxial cylindrical reactors, multi-bed flat reactors, flow stabilization reactors, bed reactors and creepage corona reactors have been developed and used as conventional pollution gas treatment devices. It is true.

By the way, the conventional gas multi-bed flatbed reactor mentioned above has the effect of simultaneously reducing SO ₂ and NO x in the exhaust gas discharged from the factory and the vehicle by plasma by electric discharge, but there is a non-discharge area between the needle electrodes. As the untreated polluted gas passes to the place, there was a problem of reducing the efficiency of pollution gas removal.

In addition, compared with other reaction treatments, the electrical discharge method has another problem of high power consumption.

Accordingly, the present invention has been made to solve the above problems, the object of which is to apply a magnetic field perpendicular to the direction of the electric field in the space to which the electric field is applied for discharging to increase the pre-movement path of electrons between the electrodes by the cyclotron motion The present invention provides an apparatus for treating pollution gas by corona discharge plasma which increases the efficiency of removing pollutants by increasing the number of polluting molecules and collisions, and also reduces power consumption by reducing electron mobility in the opposite direction to an electric field.

1 is an experimental configuration of a corona discharge plasma reaction apparatus used in the present invention

2 is a block diagram of the plasma reactor of the present invention shown in FIG.

3 is a waveform diagram of current, voltage, and power in a pulse voltage rising portion

4 is a characteristic diagram of discharge power with respect to the increase of the voltage when the magnetic field is applied (a) and the non-application (b).

5A and 5B show NO initial concentrations [NO] O = 1350ppm for the NOx removal rate of unapplied (a) and unapplied (b) of an external magnetic field having a magnetic flux density (Mf) of 0.27wb / m2, and a pulse frequency Pr = Graph showing the effect of flow rate (Qg) at 400pps as a function of discharge power

FIG. 6 is a graph showing the effect of magnetic flux density on the NOx removal efficiency at [NO] O = 1350ppm, Qg = 1ℓ / min, Pr = 400pps

7 is a graph showing the effect of the initial concentration of NOx on the NOx removal at Qg = 1ℓ / min, Mf = 0.27wb / ㎡, Pr = 400pps

8 is a graph showing the effect of pulse frequency on the NOx removal efficiency at [NO] O = 1350ppm, Qg = 1ℓ / min, Mf = 0.27wb / m2

FIG. 9 is a graph of NO, NO ₂ and NOx concentrations as the function of discharge power at [NO] O = 1350ppm, Qg = 1l / min, Mf = 0.27wb / m2 and Pr = 400pps

10 shows the energy of NOx removal as a function of discharge power for various flow rates when a magnetic field is applied (a) and when no magnetic field is applied (b) at [NO] O = 1350 ppm, Mf = 0.27wb / m2. Graph showing yield

* Explanation of symbols for main parts of the drawings

11 plasma reactor 12 nitrogen oxide analyzer

13 gas supply unit 14 voltage supply unit

21 permanent magnet 22 high voltage electrode

23 plate type ground electrode 24 acrylic resin

Features of the present invention for achieving the above object,

A plasma reactor in which a magnetic field is applied to a space to which an electric field is applied for discharge, at a right angle to the electric field, a voltage supply unit for supplying a voltage to apply an electric field to the plasma reactor, and a pollution gas into the plasma reactor Pollution gas by corona discharge plasma including a gas supply unit for inserting (NO + N ₂ , N ₂ ) and a nitrogen oxide (NOx) analyzer for analyzing the pollution gas (NOx) discharged through the plasma reactor In the processing apparatus,

The voltage supply unit generates a pulse voltage through the rotary spark gap switch to generate an electric field in the plasma reactor,

The plasma reactor includes a pair of transparent acrylic resins facing each other at a predetermined distance, and a high voltage electrode and a ground electrode having a plurality of precipitation electrodes between the pair of acrylic resins are connected to both ends of the pair of acrylic resins. Are formed to face each other, the pair of acrylic resin is characterized in that the permanent magnet is attached to the polarity of the opposing portion different from each other.

Here, the high voltage electrode and the ground electrode are formed of aluminum so as not to affect the magnetic field of the permanent magnet.

Hereinafter, an embodiment of the pollution gas treatment apparatus using a corona discharge plasma according to the present invention will be described in detail with reference to FIGS. 1 to 10.

1 is a configuration diagram for experimenting with a corona discharge plasma reaction apparatus used in the present invention, a plasma reaction apparatus 11 in which a magnetic field is applied to a space to which an electric field is applied for discharge in a direction perpendicular to the electric field direction, and the plasma reaction. Voltage supply unit 14 for supplying a voltage for applying an electric field to the device 11, and gas supply unit 13 for introducing the pollution gas (NO + N ₂ , N ₂ ) into the plasma reactor (11). ) And a nitrogen oxide (NOx) analyzer 12 for analyzing the pollutant gas NOx discharged through the plasma reactor 11.

The pulse voltage applied to generate the electric field to the plasma reactor 11 is generated by a rotating spark gap switch (R.S.G) of the voltage supply unit 14 as shown. The pulse frequency was adjusted to 150, 300, 400pps by changing the rotational speed of the direct current (DC) motor connected to the rotating electrode of the rotary spark gap switch (R.S.G).

Here, the concentration of NOx means the sum of the concentrations of NO and NO ₂ .

FIG. 2 is a configuration diagram of the plasma reactor shown in FIG. 1, wherein the plasma reactor includes a pair of transparent acrylic resins 24 facing each other at a predetermined distance, and the pair of acrylic resins 24 is disposed between the pairs of acrylic resins 24. The high voltage electrode 22 and the ground electrode 23 having a plurality of precipitation electrodes are formed to face each other at both ends of the pair of acrylic resins 24, and the pair of acrylic resins 24 have opposite polarities. The permanent magnet 21 is configured to be different from each other.

Here, the permanent magnet 21 is a samarium-cobalt magnet having a magnetic flux density of 1.08 wb / m 2. The space between the needle electrode and the plate electrode is 18 mm, the height of the reactor is 25 mm, the length is 300 mm, and the number of needle electrodes is 66. In addition, the magnetic flux density in the reactor is 0.27wb / m 2 and increases to 0.36wb / m 2 when the magnetic field circuit is formed.

The initial concentration of NOx was changed to 400, 750, 1000 and 1350 ppm by adding N ₂ to the simulated gas (NO: 0.17%, N ₂ : 99.83%), and the flow rates were 1, 3, 5 L / min. Discharge power, discharge voltage, and discharge current were measured with a THIAT's 2404 power meter and NICOLE PowerPro 610 image processor. In order to measure the NOx concentration, an automatic NOx analyzer (Analyzer) 440 was used.

The present invention uses the principle of the electromagnetism, the operation by the above configuration will be described through a mathematical principle.

First, when the electric field E is applied in the X direction in the plasma discharge region and the magnetic field B is applied in the Z direction, the charged particles (electrons) are subjected to Lorentz force.

[Equation 1]

The x, y, z direction component of this force

[Equation 2]

Fx = q (E-Vy B / c)

Fy = q Vx B / c

Fz = 0

Therefore, when the charged particles (electrons) move while colliding with other heavy elements, the average speed is

[Equation 3]

<Vx> = Fx / mv c

= λ Fx / m <V>

= lambda q (E-<Vy> B / c) / m <V>

= μ (E-<Vy> B / C)

[Equation 4]

<Vy> = lambda q <Vx> B / m <V> c

= μ <Vx> B / c

Where <V> is the thermal average speed, μ is the mobility, v c is the collision frequency, and c is the luminous flux.

Substituting Equation 4 into Equation 3,

[Equation 5]

<Vx> = μ E / [1+ (μ 2 / c 2) B 2]

= μ HE

Where the field mobility is

[Equation 6]

μ H = μ / [1+ (μ 2 / c 2) B 2]

= μ / [1+ (ω b2 / vc)]

Angular Velocity ω b = | q | B / mc

As shown in Equation 6, the mobility of electrons in the opposite direction to the electric field is inversely proportional to B2. Therefore, as the magnetic flux density increases, the mobility in the opposite direction to the electric field decreases, the discharge current decreases, and the power consumption decreases. In addition, electrons in a vacuum move in a circular motion due to cyclotron motion, but move at a certain angle with the electric field direction as the pressure in the reactor increases. Therefore, the distance to reach the counter electrode increases, so that the number of collisions between electrons and neutral pollutants increases, thereby improving the decomposition rate of the polluted gas.

3 shows waveforms of current, voltage, and power in the rising portion of the pulse voltage.

As shown, a large overshoot was observed at the rising part of the pulse voltage, where the discharge current and the discharge power showed peak values. A peak current of 38 amperes (A) was observed at an 11 kilovolt (KV) peak voltage.

Figure 4 shows the discharge power characteristics with respect to the increase in the voltage when applying the magnetic field (a) and (b).

Corona discharge power increases with increasing pulse frequency. This is because corona generation increases due to the overshoot voltage as the pulse frequency increases.

When the magnetic field is applied to the discharge region, the discharge power decreases. Under the electric field, electrons are emitted from the cathode and travel linearly to the anode. However, when a magnetic field perpendicular to the electric field is applied, a full cyclone circular motion is performed under vacuum.

That is, the electric field accelerates the charged particles (electrons) in the opposite direction of the electric field, and the magnetic field exerts a force on the charged particles (electrons) in a direction perpendicular to the electric field and the magnetic field. At high pressures, however, the electrons collide with the neutrons, which prevents the complete circular motion. Especially under atmospheric pressure, the electron's orbit is linear at an angle to the electric field due to the high collision frequency. The energy and average free stroke of the electrons do not depend on the magnetic field, but the movement distance in the electric field direction per unit time decreases, thereby reducing the mobility of the electrons. Therefore, the conduction current of the electron is reduced, thereby reducing the power consumption.

5A and 5B show N0 initial concentrations [NO] O = 1350ppm and pulse frequency Pr = for the NOx removal rate of unapplied (a) and unapplied (b) of an external magnetic field having a magnetic flux density (Mf) of 0.27wb / m 2. The effect of flow rate Qg at 400pps is shown as a function of discharge power.

NOx removal efficiency decreases with increasing flow rate. This is believed to be due to the decrease in residence time in Reacta with increasing gas flow rate.

As shown in figure (b), it is higher than NOx removal efficiency when external magnetic field is applied. The NOx removal efficiency is 76% when an external magnetic field is applied at Qg = 1 / min and 63% when no external magnetic field is applied.

6 shows the effect of magnetic flux density on the NOx removal efficiency at [NO] O = 1350ppm, Qg = 1l / min, Pr = 400pps.

At the same discharge power, NOx removal efficiency increases with magnetic flux density. The highest NOx removal efficiency of 85% was obtained at a magnetic flux density of 0.36wb / ㎡ discharge power of 10W.

As described above, when the magnetic field is applied in a direction perpendicular to the electric field direction, the path of movement of electrons emitted from the cathode to the counter electrode is longer than the entire path when the magnetic field is not applied. Therefore, the electrons are more likely to collide with the ions and neutral gas molecules of the gas molecules, and the NOx removal efficiency may be increased when applied to an external magnetic field.

FIG. 7 shows the influence of the initial concentration of NOx on NOx removal at Qg = 1 L / min, Mf = 0.27wb / m2 and Pr = 400pps, indicating that the NOx removal efficiency is slightly affected by the initial concentration.

8 shows the effect of pulse frequency on the NOx removal efficiency at [NO] O = 1350ppm, Qg = 1l / min, Mf = 0.27wb / m2.

As the pulse frequency increases, the NO removal rate increases. This is because the number of pulse voltages applied to the discharge area increases when the pulse frequency is increased, and the electrical energy converted into corona discharge increases.

FIG. 9 shows NO, NO ₂ and NOx concentrations as a function of discharge power at [NO] O = 1250ppm, Qg = 1l / min, Mf = 0.27wb / m2 and Pr = 400pps, NO generated at the beginning of corona generation ₂ is nearly constant in all voltage ranges tested.

10 shows the energy yield of NOx removal as a function of discharge power for various flow rates when a magnetic field is applied (a) and when no magnetic field is applied (b) at [NO] O = 1350ppm, Mf = 0.27wb / m2. It is shown.

When the magnetic field is applied at the discharge power of 8 (W), the energy yield is better by 23 g / kWh than when the magnetic field is not applied (about 2 times). As the flow rate increases, the energy yield increases but almost depends on the discharge power. Did not do it.

In this experiment, the removal characteristics of NOx in pollutant gases emitted from factories and automobiles using pulse corona discharge were tested for the case of the application of external magnetic field and the case of non-application.

(1) Since the discharge current is generated in the rising part of the pulse voltage, the increase in the pulse frequency increases the discharge power and the NOx removal efficiency.

(2) When the external magnetic field is applied, the NOx removal efficiency is increased by about 10% more than when the magnetic field is not applied even though the discharge power is decreased.

(3) With the increase of the flow rate, the NOx removal efficiency decreased but did not depend on the initial NOx concentration.

(4) When a magnetic field is applied, the energy yield for NOx removal is twice as high as the energy yield when no magnetic field is applied. And when a magnetic field is applied, the maximum of energy yield shifts towards lower discharge power.

As described above, according to the pollution gas treatment apparatus using the corona discharge plasma of the present invention, the electric movement path of electrons by the cyclotron motion by applying a magnetic field to the space to which the electric field is applied for discharge is perpendicular to the electric field direction. By increasing the effect of increasing the number of polluting molecules and collisions can increase the efficiency of removing pollutants, and also has a very excellent effect of reducing the power consumption by reducing the electron mobility in the opposite direction to the electric field.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to various modifications, changes, additions, etc. within the spirit and scope of the present invention, these modifications and changes should be seen as belonging to the following claims. something to do.

Claims (2)

A plasma reactor in which a magnetic field is applied to a space to which an electric field is applied for discharge, at a right angle to the electric field, a voltage supply unit for supplying a voltage to apply an electric field to the plasma reactor, and a pollution gas into the plasma reactor Pollution gas by corona discharge plasma including a gas supply unit for inserting (NO + N ₂ , N ₂ ) and a nitrogen oxide (NOx) analyzer for analyzing the pollution gas (NOx) discharged through the plasma reactor In the processing apparatus, The voltage supply unit generates a pulse voltage through the rotary spark gap switch to generate an electric field in the plasma reactor, The plasma reactor includes a pair of transparent acrylic resins facing each other at a predetermined distance, and a high voltage electrode and a ground electrode having a plurality of precipitation electrodes between the pair of acrylic resins are connected to both ends of the pair of acrylic resins. Formed to face each other, and the pair of acrylic resin, the pollutant gas treatment apparatus according to the corona discharge plasma, characterized in that the permanent magnet is attached to the polarity of the opposing portion different from each other. The method of claim 1, The high voltage electrode and the ground electrode, Pollution gas treatment apparatus according to the corona discharge plasma, characterized in that formed of aluminum so as not to affect the magnetic field of the permanent magnet.

Images