JPH05144594A - Discharge plasma generator - Google Patents

Abstract

PURPOSE:To provide a discharge plasma generator which can change discharge performance corresponding to a purpose by using an induction electric field where a comparatively high voltage is easily available without using a microwave, and by changing the forms of discharge electrodes or intervals thereof or the frequency of an applied voltage. CONSTITUTION:Two or more ring-like magnetic substances 7, 8 are arranged at the peripheral portions of pipings 2, 3, and coils 9, 10 are wound around the ring-like magnetic substances 7, 8, and also electrodes 13, 14 to promote discharge are arranged inside the pipings 2, 3. Atmospheric pressure or exhaust gas or specific gas whose pressure is lower than the atmospheric pressure is made to exist inside the pipings so that discharge plasma is generated inside the pipings 2, 3 by applying AC voltage to the coils 7, 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge plasma generator using an induction electric field.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a schematic structure of a conventional discharge plasma generator. In the figure, 43 is a discharge pipe, and a coil 42 is wound around the outer periphery of the discharge pipe 43. Exhaust gas is caused to flow in the discharge pipe 43, and a microwave plasma is supplied from the microwave power source 41 to the high frequency coil to generate discharge plasma in the discharge pipe 43.

[0003]

The above-mentioned conventional discharge plasma generator uses microwaves, but the pressure of the gas to be discharged (exhaust gas 44 in the figure) is at a certain level in order to start discharge. If it is not low, there is a drawback that it is difficult to turn it into plasma.

The present invention has been made in view of the above points, and uses an induction electric field in which a relatively high voltage can be easily obtained without using microwaves, and the shape and interval of the discharge electrode or the frequency of the applied voltage can be changed. It is an object of the present invention to provide a discharge plasma generator capable of changing the discharge performance according to the purpose by changing it.

[0005]

In order to solve the above-mentioned problems, the present invention has two or more ring-shaped magnetic bodies arranged on the outer peripheral portion,
A coil is wound around the ring-shaped magnetic body, an electrode that promotes discharge is arranged inside the pipe, and exhaust gas or a specific gas at atmospheric pressure or a pressure lower than that is present in the pipe, and an AC voltage is applied to the coil. Then, discharge plasma is generated in the pipe.

Further, it is characterized in that the generation of discharge initiation plasma is controlled by setting the frequency of the alternating voltage applied to the coil to an appropriate value.

[0007]

By configuring the discharge plasma device as described above, when a pulsed AC voltage is applied to the coil wound around the ring-shaped magnetic body, the magnetic body is magnetized and the time of the applied pulse waveform is increased. An induction electric field proportional to the differential coefficient is generated inside the pipe in a direction to cancel the magnetization. At this time, if the material has a property that the magnetic body follows the pulse waveform with a sharp rise and fall, it is possible to generate a large potential difference between the electrodes mounted in the pipe. The discharge performance can be changed by changing the shape and interval of the electrodes or the frequency of the AC voltage, and the discharge can be facilitated even at a high gas pressure.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a diagram for explaining the principle of the induction electric field generator of the present invention. In the figure, 34 is a discharge pipe with a discharge electrode, and a ring-shaped magnetic body 32 made of ferrite or the like is arranged on the outer periphery of the discharge pipe 34. A coil 33 is wound around the ring-shaped magnetic body 32, and when a pulsed AC voltage is applied to the coil 33 from the high frequency power supply 31, the magnetic body 32 is magnetized.

When the magnetic substance 32 is magnetized, an induction electric field proportional to the time differential coefficient of the applied pulse waveform is generated inside the discharge pipe 34 in the direction of canceling the magnetization.
At this time, a material having a property that the magnetic body 32 follows the pulse waveform with a sharp rise and fall makes it possible to generate a large potential difference between the electrodes attached to the discharge pipe 34. The discharge performance can be changed by changing the shape of the discharge pipe 34, the interval between the electrodes, or the pulse frequency from the AC high frequency power supply 31. Therefore, the discharge becomes easy even at a high gas pressure.

FIG. 1 is a diagram showing a schematic structure of a discharge plasma generator using an induction electric field according to the present invention. In FIG. 1, reference numerals 1 and 1 denote pipes for passing exhaust gas, and two discharge pipes 2 and 3 are provided between the pipes 1 and 1 for insulation.
It is inserted through 6. Ring-shaped magnetic bodies 7 and 8 made of ferrite or the like are arranged on the outer peripheral portions of the discharge pipes 2 and 3, and coils 8 and 9 are wound around the magnetic bodies 7 and 8, respectively. The coil 8 and the coil 9 are connected in series, and a pulsed voltage is applied from the high frequency power supply 11 {see (a) of FIG. 2}. In the figure, 12 is a phase shifter for converting the phase of the voltage applied to the coil 9. Further, discharge electrodes 13 and 14 are arranged inside the discharge pipes 2 and 3.

FIG. 2 shows the operation of the plasma generating apparatus having the above structure.
This will be described with reference to the waveform diagram of. When a rectangular wave voltage as shown in FIG. 2A is applied from the high frequency power source 11, inside the magnetic body 7 is proportional to the time differential coefficient of the applied voltage as shown in FIG. An internal electric field E1 that forms a large peak is generated at the rising and falling portions of the applied pulse voltage. If the phase shifter 12 is not provided, an internal electric field E2 as shown in FIG. 2C is generated inside the magnetic body 8. Without the phase shifter 12 as shown in FIGS. 2B and 2C, the peaks of the internal electric field E1 and the internal electric field E2 are deviated, which is inconvenient. So phase shifter 1
The phase of the voltage applied to the coil 9 is shifted by 2 so that the peaks of the internal electric field E1 and the internal electric field E2 coincide with each other, as shown in FIG.

Inside the discharge pipes 2 and 3, a discharge electrode 13,
14 is arranged, and a large potential difference is generated between the electrodes of the discharge electrodes, and discharge plasma is generated. By configuring the plasma generator as shown in FIG.
5 and 6 and magnetic bodies 7 and 8 are electrically independent of the discharge pipes 2 and 3, and there is an advantage that the discharge operation occurs only inside the discharge pipes 2 and 3.

In the plasma generator having the structure shown in FIG. 1, the discharge plasma is generated in the exhaust gas by flowing the exhaust gas into the discharge pipes 2 and 3 through the pipes 1 and 1, whereby N ₂ in the exhaust gas, O ₂ and HO ₂ are active species OH,
O and HO ₂ . The generated active species react with SO ₂ in the exhaust gas to form sulfuric acid. That is, SO ₂ + 2OH → H ₂ SO 4 SO ₂ + O → SO ₃ + H ₂ O → H ₂ SO ₄ NH ₃ to which the sulfuric acid thus generated is added and a reaction salt (by-product), and the exhaust gas is treated. To be done. That is, H ₂ SO ₄ + H ₂ O + NH ₃ → (NH ₄ ) ₂ SO ₄ (ammonium sulfate).

Further, the components CO, HC, N in the exhaust gas₂，
O₂, H₂O is OH, O, HO₂, N₂, H, HC, CO
And the active species N₂, HC and CO react with NO in exhaust gas
In response, NO + 2H → 1 / 2N₂+ H₂ONO + 2H + HC → 1 / 2N₂+ CO₂+ H₂ONO + 2H + CO → 1 / 2N₂+ CO₂  Becomes

As described above, the plasma generator can be used as an exhaust gas treatment device for treating SO _X and NO _X in exhaust gas.

[0016]

As described above, according to the present invention, the discharge performance can be changed by changing the conditions such as the shape interval of the electrodes inside the pipe or the voltage-voltage frequency applied to the coil. And an excellent effect that discharge plasma can be generated without selecting the gas pressure.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic structure of a discharge plasma generator using an induction electric field of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the discharge plasma generation device of FIG.

FIG. 3 is a diagram for explaining the principle of the induction electric field generator of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a conventional discharge plasma generator.

[Explanation of symbols]

 1 Piping 2,3 Discharge Piping 4,5,6 Insulation Piping 7,8 Magnetic Material 9,10 Coil 11 High Frequency Power Supply 12 Shifter 13,14 Discharge Electrode

Claims (2)

[Claims] 1. Inside the pipe, two or more ring-shaped magnetic bodies are arranged on the outer periphery of the pipe, a coil is wound around the ring-shaped magnetic body, and an electrode for promoting discharge is arranged inside the pipe. A discharge plasma generating apparatus, characterized in that an exhaust gas or a specific gas having an atmospheric pressure or a lower pressure than that is present in the coil, and an AC voltage is applied to the coil to generate a discharge plasma in the pipe. 2. A discharge plasma generating apparatus, wherein discharge initiation plasma generation is controlled by setting a frequency of an AC voltage applied to the coil to an appropriate value.