JPH0963747A - Gas treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the average gas treatment capacity per unit volume of a gas treatment device by pulse streamer corona discharge. SOLUTION: A discharge tube 35 to which high voltage formed in a high voltage power circuit 32 is applied as high voltage pulse by a high-speed switching device 34 and a charge control circuit 36 in which charge voltage on the high voltage power circuit 32 is controlled are provided. In accordance with an instruction from a trigger control circuit 41 in which pulse voltage applied to the discharge tube 35 is output for every preset pulse number from the beginning of being applied, a rated voltage value is compared with an output voltage value in a comparison circuit 43. If the output voltage value is lower than the rated voltage value, a preset voltage value is added in a charge voltage control circuit 42 to be instructed to the high voltage power circuit 32 and field intensity between electrodes in the discharge tube 35 is gradually improved. With the change of the field intensity between the electrodes in the discharge tube 35, a space between the electrodes is charged toward the flow direction of treatment gas.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the generation of ozone and N
The present invention relates to a gas treatment device that performs gas treatment such as removal of Ox and SOx by pulse streamer corona discharge.

[0002]

2. Description of the Related Art A pulse streamer corona is used for processing various gases such as conversion of dry air or oxygen to ozone, or conversion of ammonium sulfate and ammonium nitrate by coexistence of ammonia in flue gas containing NOx and SOx. Discharge may be used.

The gas treatment device in this case will be described with reference to FIG. 5. The gas treatment device 1 takes out a gas inlet 2 for feeding a gas to be treated, for example, dry air, and a gas containing the treated gas, for example, ozone. A box 4 having a gas outlet 3, and a plurality of pulse streamers (three in the illustrated example) arranged in the box 4 along the flow direction of the gas to be processed (direction of arrow A in the figure). A discharge tube 5 that forms a corona discharge and a pulse high voltage power source 6 that applies an extremely short pulse high voltage to the discharge tube 5 are provided.

Further, in the box body 4, 80% or more of the discharge power supplied to the discharge tube 5 is converted into heat in the gas, and is provided on the outer wall portion 7 in order to prevent a decrease in processing efficiency due to this heat. With the cooling medium inlet 8 and the cooling medium outlet 9 and the partition walls 10 and 11 arranged in the box 4, a cooling medium in which a cooling medium such as water for cooling the discharge tube 5 arranged in the box 4 flows. Passages 13 are formed so as to cool the gas flowing in the discharge tube 5. The arrow B in the figure indicates the flow of the cooling medium.

In the discharge tube 5, the wire electrode 15 stretched along the flow direction of the processing gas in the box 4 is used as a corona discharge electrode, and the cylindrical electrode 16 through which the wire electrode 15 is inserted is a non-corona discharge electrode. Is a parallel coaxial cylindrical pulse streamer corona discharge tube composed of a pair of electrodes 15 and 16.

The wire electrode 15 which is one of the pair of electrodes in the discharge tube 5 has a base end located on the gas inlet 2 side,
The end portion of the wire electrode 15 located on the gas outlet 3 side is electrically connected to one electrode 19 of the pulse high voltage power source 6 inserted through the outer wall portion 7 of the box 4 via the outer wall portion 7 of the box 4. It is fixed to a wire end support insulator 21 which is insulated and supported via an insulator 20.

The other cylindrical electrode 16 of the pair of electrodes in the discharge tube 5 is connected to the other electrode 23 of the pulse high voltage power source 6 via the partition walls 10 and 11 and the outer wall portion 7. The outer wall portion 7 and the partition walls 10 and 11 of the box body 4 are
All of these are made of metal having excellent conductivity.

In the gas treatment in the gas treatment apparatus 1 having the above structure, the average flow velocity in each discharge tube 5 is set to a predetermined value, for example, several cm / s to several tens cm / s in the case of ozone generation. The gas to be processed is sent from the gas inlet 2 into the box 4 while controlling the supply amount, and an extremely short pulse high voltage is applied to the discharge tube 5 by the pulse high voltage power supply 6. The gas to be processed sent into the box 4 flows between the pair of electrodes 15 and 16 in the discharge tube 5, and is exposed to the pulse streamer corona discharge during that time and gradually progresses from the gas inlet 2 to the gas outlet 3. It is processed by causing a change due to a chemical reaction.

[0009]

By the way, according to the research of the pulse streamer corona discharge by the inventors, when a large number of pulse streamer corona discharges are repeated, the discharge current of the entire discharge tube decreases even under the same applied voltage. , It turned out to settle for a certain value. The phenomenon that the discharge current of the entire discharge tube decreases is generally known to have an electric field relaxation effect due to the accumulation of ion space charges generated by the discharge for corona discharge current. Is also presumed to be due to the action of this electric field relaxation effect.

That is, in the conventional gas treatment apparatus 1 as shown in FIG. 5, the pulse voltage applied between the pair of electrodes 15 and 16 of the discharge tube 5 is constant, and the interval also produces a spark discharge. It is set to a constant value (parallel coaxial) that does not allow it. On the other hand, the gas to be processed in the discharge tube 5 is pulsed (discharged).
Since the number of times is accumulated, the accumulated ion space charge amount and the electric field relaxation effect are gradually increased, and since the gas to be processed is flowing, the size thereof is larger toward the outlet side of the discharge tube 5, which results in It is considered that the discharge current of the entire discharge tube 5 is reduced.

That is, in the conventional gas processing apparatus 1 as shown in FIG. 5, the discharge current of each part of the discharge tube 5 with respect to the gas flow direction gradually decreases from the time when the voltage is applied, and the gas flow direction. No measures have been taken against the fact that the discharge current of each part is large on the inlet side of the discharge tube 5 and decreases as it goes to the outlet side, and the power input to the gas to be treated is not particularly effective at the outlet side of the discharge tube 5. However, there is a drawback that the gas treatment capacity is inferior to the volume of the gas treatment device.

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to increase the average gas treatment capacity per unit volume in a gas treatment apparatus by pulse streamer corona discharge.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a gas treatment apparatus for conducting gas treatment by passing between a pair of electrodes forming a pulse streamer corona discharge, and by controlling the electric field strength between the pair of electrodes. This is achieved by providing a gas treatment device characterized by being changed.

It is another object of the present invention to provide a gas treatment device for performing gas treatment by passing between a pair of electrodes forming a pulse streamer corona discharge, in which a pulse voltage applied between the pair of electrodes is pulsed. This is achieved by providing a gas treatment device characterized in that the number of pulses from the starting point is gradually increased until it reaches a predetermined number.

Further, an object of the present invention is a gas treatment device for performing gas treatment by passing between a pair of electrodes forming a pulse streamer corona discharge, wherein the gas passing through a space between the pair of electrodes is treated. This is achieved by providing a gas processing device characterized in that the downstream side is narrower than the upstream side.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

[0017]

1 is a block diagram of a gas processing apparatus according to a first embodiment of the present invention, and FIG. 2 is an operation explanatory view of the gas processing apparatus of FIG. In FIG. 1, 31 is a power supply, 32 is a high-voltage power supply circuit that is composed of an inverter, a converter, a capacitor, etc., and generates a high voltage, 33 is a rectifier circuit, 34 is a high-speed switching device such as a thyratron, and 35 is a pulse streamer corona discharge. Is a discharge tube that forms a charge control circuit for controlling the charging voltage of the high-voltage power supply circuit 32.
Incidentally, 37 is a box of the gas treatment device, and 38 is an output voltage detection circuit.

The gas treatment device configured as described above is
Under the command from the charge control circuit 36, the high voltage power supply circuit 3
2, a high voltage is formed, and the voltage is applied to the discharge tube 35 as a high voltage pulse by the high-speed switching device 34 that opens and closes at an appropriate timing based on a trigger command from the charge control circuit 36 via the rectifier circuit 33. To be done. At this time, a gas such as air or smoke is flowing through the discharge tube 35, a pulse streamer corona discharge is generated by the applied high voltage pulse, and the gas flowing through the pulse streamer corona discharge is ozone. Or conversion to ammonium sulfate or ammonium nitrate.

The charge control circuit 36 is the trigger control circuit 4
1, comprising a charging voltage control circuit 42 and a comparison circuit 43,
The trigger control circuit 41 sets the opening / closing timing of the high-speed switching device 34 and the number of times (shot number), outputs a trigger command to the high-speed switching device 34, and appropriately sets the number of shots of the trigger command (10 in this embodiment).
A comparison execution command is output to the comparison circuit 43 for each shot.

In the charging voltage control circuit 42, an initial voltage (15 KV in this embodiment) and a voltage increase value (300 V in this embodiment) are set, and the voltage increase value is added for each charging voltage increase command from the comparison circuit 43. Then, the charging voltage command is output to the high voltage power supply circuit 32. In the comparison circuit 43, the final charging voltage of the rated value (30 KV in this embodiment) is set as the reference value, and it is compared with the output voltage of the output voltage detection circuit 38 for each comparison execution command from the trigger control circuit 41, and from the reference value. Is also small, the charging voltage increase command is issued to the charging voltage control circuit 42.
Output to

Since the charging control circuit 36 is constructed as described above, the pulse voltage applied to the discharge tube 35 is as shown in FIG.
As shown in, the voltage of 300 V is added every 10 shots from 15 KV at the start of pulse application, and gradually rises until the rated value reaches 30 KV after 500 shots when gas treatment stabilizes. That is, the electric field strength between the pair of electrodes of the discharge tube 35 is gradually increased.

When the electric field strength between the pair of electrodes of the discharge tube 35 is gradually changed in this manner, the electric field strength is small when the spark discharge is likely to occur at the start of discharge, and the electric field strength is small.
Since the electric field strength increases as the gas flowing therethrough increases the electric field relaxation effect due to the accumulation of pulse streamer corona discharge, the interval between the pair of electrodes of the discharge tube 35 can be set narrow.

That is, the discharge tube 35 can be made thin or the rated voltage can be set high, and the gas treatment capacity per unit volume in the gas treatment apparatus can be enhanced. It should be noted that the numerical values given in the examples are set appropriately and are not limited to these numerical values.

FIG. 3 is a block diagram of a gas processing apparatus according to the second embodiment of the present invention. In the above-described first embodiment, the voltage applied to the discharge tube is changed to change the electric field strength, but in the second embodiment, the gap between the pair of electrodes of the discharge tube is changed in the gas flow direction, that is, A change is made from the upstream side of the flowing gas to the downstream side, and the electric field strength between the pair of electrodes is changed in the gas flow direction.

In FIG. 3, parts that are the same as or common to those of the conventional gas treatment device described with reference to FIG. 5 are given the same reference numerals, and detailed description of those parts is omitted to avoid duplication of description. To do. The difference between the gas processing apparatus of the second embodiment shown in FIG. 3 and the conventional gas processing apparatus 1 shown in FIG. 5 is a discharge tube 54 that forms a pulse streamer corona discharge.

In the discharge tube 54, a wire electrode 55 stretched along the flow direction of the processing gas (arrow A in the figure) in the box 4 is used as a corona discharge electrode, and the wire electrode 55 is arranged at the center thereof. The cylindrical electrode 56 formed around the periphery is provided with a taper whose diameter is smaller than the diameter of the gas inlet side, that is, the upstream side of the flowing gas, on the outlet side, that is, the downstream side of the flowing gas. It is composed of a pair of electrodes 55 and 56 which are corona discharge electrodes.

In the gas treatment device having the discharge tube 54 constructed as described above, the gas to be treated sent into the box 4 is caused to flow between the pair of electrodes 55 and 56 in the discharge tube 54, and the pulse streamer corona is provided therebetween. When exposed to an electric discharge, a change due to a chemical reaction is caused gradually with the progress from the gas inlet 2 to the gas outlet 3 for processing.

The gas to be processed which advances in the discharge tube 54 is
Pulse streamer Flows while accumulating the number of corona discharges,
Although the electric field relaxation effect is gradually increased as the discharge progresses, the distance between the pair of electrodes 55 and 56 of the discharge tube 54 is narrower on the downstream side than on the upstream side and the electric field strength is gradually increased. The discharge current of each part with respect to the flow direction is the same, and effective power supply to the gas to be processed can be performed all the time.

FIG. 4 is a configuration diagram of another example of the discharge tube in the gas treatment apparatus of FIG. In the discharge tube 64, the wire electrode 65 stretched along the flow direction of the processing gas (arrow A shown in the figure) in the box not shown serves as a corona discharge electrode, and the wire electrode 55 is arranged at the central portion so that the gas inlet side ,
That is, it is composed of a pair of electrodes 65 and 66 in which the cylindrical electrode 56 whose diameter is gradually reduced from the upstream side of the flowing gas is a non-corona discharge electrode. Even if the discharge tube 64 is configured in this way, it is possible to enjoy the same effects as those of the second embodiment shown in FIG.

The diameter of the electrode on the outlet side of the second embodiment,
That is, the distance between the pair of electrodes located on the outlet side may be determined within a range that does not cause dielectric breakdown, and is experimentally determined according to gas conditions and applied voltage conditions. Further, although a cylindrical electrode is used in each embodiment, an electrode configuration such as a flat plate pair wire may be used. Further, the first embodiment and the second embodiment may be combined, that is, the pulse high voltage power supply of the first embodiment may be used as the pulse high voltage power supply in the second embodiment. In this case, the processing capacity may be further improved. it can.

[0031]

As described above in detail, according to the present invention, when the gas treatment is performed by passing between the pair of electrodes forming the pulse streamer corona discharge, the voltage or the voltage for applying the electric field strength between the pair of electrodes is applied. Since the distance between the electrodes is changed, electric power can be effectively applied to the gas to be processed, and the gas processing capacity per unit volume can be increased.

[Brief description of drawings]

FIG. 1 is a block diagram of a gas treatment device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the gas treatment device of FIG.

FIG. 3 is a configuration diagram of a gas treatment device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of another example of a discharge tube in the gas treatment device of FIG.

FIG. 5 is a configuration diagram of a conventional gas treatment device.

[Explanation of symbols]

 1 Gas Treatment Device 2 Gas Inlet 3 Gas Outlet 4, 37 Box 5, 35, 54, 64 Discharge Tube 6 Pulse High Voltage Power Supply 8 Cooling Medium Inlet 9 Cooling Medium Outlet 10, 11 Partition Walls 15, 55, 65 Wire Electrode 16, 56, 66 Cylindrical electrode 32 High-voltage power supply circuit 33 Rectifier circuit 34 High-speed switching device 36 Charge control circuit 38 Output voltage detection circuit 41 Trigger control circuit 42 Charge voltage control circuit 43 Comparison circuit

Claims (3)

[Claims] 1. A gas processing apparatus for performing gas processing by passing between a pair of electrodes forming a pulse streamer corona discharge, wherein the electric field strength between the pair of electrodes is changed. apparatus. 2. A gas processing device for performing gas processing by passing between a pair of electrodes forming a pulse streamer corona discharge, wherein the pulse voltage applied between the pair of electrodes is the number of pulses from the start of pulse application. Is gradually increased until a predetermined number is reached. 3. A gas treatment device for performing gas treatment by flowing between a pair of electrodes forming a pulse streamer corona discharge, wherein the gas treatment device is downstream of an upstream side of a gas flowing through an interval between the pair of electrodes. A gas treatment device characterized by narrowing.