High-voltage power supply

Abstract

To apply effective explosion prevention treatment to the part of a high-voltage power supply device to be an ignition source.SOLUTION: A high-voltage power supply device 201 includes: low voltage terminals Ta, Tb, with a plurality of terminals separated from each other by a predetermined distance; a low voltage terminal box 224 that tightly seals the low voltage terminals Ta, Tb; encapsulation means (third inert gas encapsulation part 303) for encapsulating inert gas GN in the low voltage terminal box 224; and seal means including a coupling 225 connected to a cable lead-in port of the low voltage terminal box 224.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an explosion-proof high-voltage power supply device suitable for use in an electrostatic precipitator.

Background Art

[0002] Conventionally, a high-voltage power supply device for an electrostatic precipitator has been installed in a safe location and not in a location where flammable gas is present in the surroundings. This is because a paper-insulated cable could be used as the wiring from the high-voltage power supply device to the electrostatic precipitator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, at the time of filing of the present application, the production of paper-insulated cables has been discontinued and no alternatives have been developed. Therefore, in order to install the high-voltage power supply device without laying the paper-insulated cable, the high-voltage power supply device has to be installed in a location where flammable gas is present, such as above the electrostatic precipitator. Therefore, without taking some measures, there is a risk of explosion when the flammable gas comes into contact with the ignition source of the high-voltage power supply device. Therefore, it is required to take effective explosion-proof measures for the part that becomes the ignition source of the high-voltage power supply device.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to take effective explosion-proof measures for the part that becomes the ignition source of the high-voltage power supply device.

Means for Solving the Problems

[0006] The inventors of the present invention have found that the above-mentioned high-voltage power supply device can be solved by incorporating, as essential components, a sealing means that includes a sealing means for sealing an inert gas inside a low-voltage terminal box and a sealing means that includes a coupling connected to the cable entry port of the low-voltage terminal box, and have completed the present invention. Specifically, the present invention provides the following.

[0007] (1) A high-voltage power supply device comprising: a low-voltage terminal having a plurality of terminals arranged at a predetermined distance apart; a low-voltage terminal box for sealing the low-voltage terminal; a sealing means for sealing an inert gas inside the low-voltage terminal box; and a sealing means including a coupling connected to the cable entry port of the low-voltage terminal box.

[0008] (2) The high-voltage power supply device according to (1), wherein the inert gas is nitrogen gas and the internal pressure inside the low-voltage terminal box is maintained at 0.5 kPa or higher.

[0009] (3) The high-voltage power supply device according to (1) or (2), wherein the distance between the plurality of terminals is 200 mm or less.

[0010] (4) An electrostatic precipitator equipped with any of the high-voltage power supply devices described in (1) to (3).

[0011] (5) The electrostatic precipitator according to (4), wherein the high-voltage power supply is located in close proximity to the upper housing on which the exhaust port of the electrostatic precipitator is installed. [Effects of the Invention]

[0012] According to the present invention, effective explosion-proof measures can be applied to the part of a high-voltage power supply that is a potential ignition source. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing the schematic configuration of a wet electrostatic precipitator equipped with an explosion-proof high-voltage power supply according to one embodiment of the present invention. [Figure 2] Figure 1 is a perspective view showing the schematic configuration of the inside of the housing of the wet electrostatic precipitator. [Figure 3] Figure 1 is a cross-sectional view showing the configuration of an explosion-proof high-voltage power supply unit among the wet electrostatic precipitators. [Figure 4] Figure 3 is a cross-sectional view showing the configuration of a low-voltage terminal box and coupling installed in an explosion-proof high-voltage power supply unit. [Modes for carrying out the invention]

[0014] One embodiment of the present invention will be described below with reference to the drawings.

[0015] Figure 1 is a cross-sectional view showing the schematic configuration of a wet electrostatic precipitator 11 equipped with an explosion-proof high-voltage power supply unit 201 according to one embodiment of the present invention. Specifically, Figures 1(A) and 1(B) are cross-sectional views showing the schematic external configuration of the wet electrostatic precipitator 11, and are cross-sectional views taken from different directions that are substantially perpendicular to each other. The explosion-proof high-voltage power supply unit 201 is indicated by the dashed line in Figure 1(A).

[0016] The wet electrostatic precipitator 11 is equipped with an upper casing 111, a dust collection electrode 122, a lower casing 113, a frame 114, and an explosion-proof high-voltage power supply unit 201.

[0017] The housing of the wet electrostatic precipitator 11 is formed by assembling the upper casing 111, the dust collection electrode 122, and the lower casing 113 in that order from above. The housing of the wet electrostatic precipitator 11 is fixed by a frame 114 at a predetermined distance above the ground. In this embodiment, conductive FRP (fiber-reinforced plastics) is used as the material for the housing of the wet electrostatic precipitator 11.

[0018] The explosion-proof high-voltage power supply device device 201 is installed at a position close to the upper casing (upper casing 111) where the exhaust port of the wet electrostatic precipitator 11 (the exhaust port of G2 in Fig. 1(A)) is installed (for example, the part indicated by the broken line in Fig. 1(A)). This position is a place where flammable gas (G2) and the like exist. Also, the explosion-proof high-voltage power supply 201 potentially has an ignition source inside it as well. Therefore, the explosion-proof high-voltage power supply 201 of the present embodiment has effective explosion-proof measures compared to conventional high-voltage power supplies. The specific content of the explosion-proof measures will be described later using Figs. 3 and 4.

[0019] Fig. 2 is a perspective view showing the schematic configuration inside the casing of the wet electrostatic precipitator 11. As shown in the figure, inside the casing of the wet electrostatic precipitator 11, there are provided an upper grid 121, a dust collecting electrode 122, a lower grid 123, an electrode rod 124, a discharge wire 125, a weight 126, an upward spray nozzle 127, and a cleaning pipe 128.

[0020] As shown in Fig. 2, the upper grid 121, the dust collecting electrode 122, and the lower grid 123 are arranged at a predetermined distance from each other in that order from above and are substantially parallel to each other in the horizontal direction.

[0021] As shown in Fig. 2, the dust collecting electrode 122 is configured by repeatedly and continuously arranging a plurality of pole chambers with a square tube as a unit (hereinafter, such a unit is referred to as a "pole chamber"). Specifically, hereinafter, in the substantially horizontal direction, one direction is called the "vertical direction", and the direction perpendicular to the vertical direction is called the "horizontal direction". In this case, the dust collecting electrode 122 is configured by repeatedly and continuously arranging p units in the vertical direction and q units in the horizontal direction (hereinafter, expressed as "p×q"). Here, p and q are independent arbitrary integer values. In the present embodiment, as shown in Fig. 2, the number of pole chambers of the dust collecting electrode 122 is p×q = 3×3.

[0022] Furthermore, dust collection electrodes, such as the dust collection electrode 122, which are constructed as an assembly of rectangular tubes, are generally called "rectangular tube type dust collection electrodes." They have the advantage of a large dust collection electrode area per unit volume, which allows for a compact design. In this embodiment, conductive FRP is used as the material for the dust collection electrode 122.

[0023] In this embodiment, the discharge electrode for such a dust collection electrode 122 is composed of an electrode rod 124 and a discharge wire 125. As shown in Figure 2, the electrode rod 124 is arranged to penetrate substantially vertically through the center of a predetermined electrode chamber of the dust collection electrode 122, with its upper end fixed to the upper grid 121 and its lower end fixed to the lower grid 123.

[0024] As shown in Figure 2, the discharge wire 125 is suspended from the upper grid 121 and is positioned to penetrate approximately vertically through the center of a predetermined electrode chamber of the dust collection electrode 122. The discharge wire 125 is also connected to a weight 126 provided on the upper part of the lower grid 123 to maintain sufficient tension to prevent sagging.

[0025] A negative DC high voltage V is directly applied to the electrode rod 124 from an explosion-proof high-voltage power supply 201. On the other hand, a negative DC high voltage V is applied to the discharge wire 125 from the explosion-proof high-voltage power supply 201 via the electrode rod 124 and the upper grid 121.

[0026] The upward-facing spray nozzles 127 are positioned above the four corners of each electrode chamber of the dust collection electrode 122 and spray the cleaning water flowing through the cleaning pipe 128 as a fine mist in a nearly vertical upward direction. Here, "mist" refers to water droplets with a diameter on the order of microns, 1 cm 3 This refers to a state in which several to several hundred particles are contained in the space. In this embodiment, the cleaning water is ejected from the upward spray nozzle 127 in a nearly vertical upward direction as water droplets with a diameter of approximately 200 to 800 μm.

[0027] The mist ejected from each of the upward-facing spray nozzles 127, which are positioned above the four corners of each electrode chamber of the dust collection electrode 122, forms a water film that covers the entire side surface of each electrode chamber of the dust collection electrode 122. In other words, the cleaning water ejected as mist from the upward-facing spray nozzles 127 forms a wet wall on the side surface of each electrode chamber of the dust collection electrode 122. This prevents the growth of fine particles such as mist and dust adhering to the dust collection electrode 122 and makes it possible to clean and remove these fine particles more reliably than in conventional methods. As shown in Figure 1, a downward-facing spray nozzle 129 may also be provided at a predetermined position above the upper end of the dust collection electrode 122, at a predetermined distance from the upper end, similar to conventional wet electrostatic precipitators.

[0028] Next, we will describe the explosion-proof measures for the explosion-proof high-voltage power supply unit 201 installed in the wet electrostatic precipitator 11 described above.

[0029] Figure 3 is a cross-sectional view showing the configuration of the explosion-proof high-voltage power supply unit 201 of the wet electrostatic precipitator 11 shown in Figure 1. As shown in the figure, the explosion-proof high-voltage power supply unit 201 is equipped with an oil tank 221, a protective duct 222, a grounding switch 223, a low-voltage terminal box 224, a ventilation pressure box 227, a pressure gauge 228, and a safety valve 229.

[0030] The oil tank 221 is provided with a first inert gas sealing section 301, which is a sealing means for sealing in an inert gas. The protective duct 222 is similarly provided with a second inert gas sealing section 302. The low-pressure terminal box 224 is also similarly provided with a third inert gas sealing section 303, which is a sealing means for sealing in an inert gas. In addition, a blower 304 is provided in the ventilation pressure box 227.

[0031] The oil tank 221 is a metal tank into which insulating oil is poured. Insulating oil can become an ignition source if it comes into contact with flammable gas that enters from the outside. To prevent the insulating oil from igniting, inert gas GN is sealed inside the oil tank 221 by the first inert gas sealing section 301. That is, the insulating oil is sealed inside the oil tank 221, and then the inert gas GN is sealed on top of that. This prevents flammable gas from the outside from coming into contact with the insulating oil. Nitrogen can be used as the inert gas GN, for example.

[0032] Furthermore, by installing a pressure gauge 228 on the oil tank 221, the internal pressure inside the oil tank 221 can be managed. Specifically, for example, the internal pressure can be managed by conducting daily inspections based on the temperature and pressure characteristics inside the oil tank 221 and confirming whether or not the internal pressure is normal.

[0033] The protective duct 222 is a duct for protecting the electrode rod 124. As the wet electrostatic precipitator 11 operates, electric charge accumulates inside the protective duct 222, and during periodic maintenance, this charge is discharged from the grounding switch 223. The movable contact portion of this grounding switch 223 can become an ignition source if it comes into contact with flammable gas that enters from the outside. Therefore, in order to prevent ignition at the movable contact portion of the grounding switch 223, inert gas GN is sealed inside the protective duct 222 by the second inert gas sealing portion 302. This prevents flammable gas from entering the protective duct 222 from the outside, that is, it prevents flammable gas from coming into contact with the grounding switch 223.

[0034] The low-voltage terminals Ta and Tb (see Figure 4, described later) located inside the low-voltage terminal box 224 can also become ignition sources if they come into contact with flammable gases that enter from the outside. To prevent this, the low-voltage terminal box 224 is sealed with inert gas GN by the third inert gas sealing section 303.

[0035] Here, a power cable C surrounded by a conduit 226 is connected to the low-voltage terminal box 224, and a gap may be created around the entry point of this power cable through which flammable gas can enter. If inert gas GN leaks from this gap, the internal pressure of the inert gas GN inside the low-voltage terminal box 224 cannot be properly maintained, and as a result, there is a risk that flammable gas may enter through the gap. Therefore, in the low-voltage terminal box 224, sealing with inert gas GN and a coupling 225 are used in combination as sealing means.

[0036] As shown in Figure 4, the coupling 225 is configured to include three components: a screw portion 225a, a coupling portion 225b, and a short union portion 225c, and is used as a sealing means at the power cable entry point of the low-voltage terminal box 224. Specifically, first the screw portion 225a is screwed into the cable entry point of the low-voltage terminal box 224, then the power cable is passed through the screw portion 225a, the coupling portion 225b, and the short union portion 225c, and finally, with the screw portion 225a and the coupling portion 225b in close contact, the short union portion 225c is screwed into the screw portion 225a to complete the installation. This ensures that the airtightness of the power cable entry point is sufficiently improved.

[0037] By using couplings in this manner, the airtightness of the power cable entry point can be sufficiently enhanced. This allows the internal pressure of the inert gas GN inside the low-voltage terminal box 224 to be stably maintained at an appropriate pressure, preventing flammable gases from entering the low-voltage terminal box 224 from the outside, and thus preventing contact of flammable gases with the low-voltage terminals Ta and Tb with a higher degree of certainty.

[0038] Furthermore, by using an air seal with inert gas GN in combination with the above-mentioned coupling, the stability of the internal pressure is enhanced by the coupling, making the air seal function more stable. On the other hand, even if the sealing function by the coupling deteriorates due to aging of the materials, the air seal function can suppress the intrusion of gas from the outside to some extent, so using both together is effective in preventing the rapid intrusion of large amounts of flammable gas. intenseThis can contribute to improved safety by preventing accidents such as explosions caused by intrusion. Furthermore, for example, by setting a pressure gauge (not shown) in the low-voltage terminal box 224 and constantly monitoring the appropriate internal pressure that should be maintained by the inert gas GN, a decrease in sealing function due to coupling deterioration can be detected early.

[0039] Furthermore, the low-voltage terminals Ta and Tb inside the low-voltage terminal box 224, which could be ignition sources, are arranged at a predetermined distance apart to maintain insulation. That is, because the insulation effect of the low-voltage terminals Ta and Tb fluctuates depending on the environment inside the low-voltage terminal box 224 (humidity, dirt, etc.), the distance between the low-voltage terminals Ta and Tb is separated according to the voltage to maintain insulation and prevent short circuits. The specific details of the insulation maintenance method by separating the low-voltage terminals Ta and Tb, and the sealing method using the coupling 225, will be described later with reference to Figure 4.

[0040] The ventilated pressure box 227 houses the oil tank 221, grounding switch 223, and low-voltage terminal box 224, which can all be ignition sources as described above. The blower 304 seals air A inside the ventilated pressure box 227. As a result, the air pressure inside the ventilated pressure box 227 becomes higher than atmospheric pressure, preventing flammable gases from entering the ventilated pressure box 227, i.e., preventing flammable materials from coming into contact with parts that could be ignition sources. In this way, the ventilated pressure box 227 can achieve an even higher level of explosion protection. Thus, it becomes necessary to manage the air pressure inside the ventilated pressure box 227 to be higher than atmospheric pressure. For this reason, the ventilated pressure box 227 is equipped with a pressure gauge 228 to manage the internal pressure. In addition, a safety valve 229 can be installed to activate in the event of an abnormal internal pressure.

[0041] Figure 4 is a cross-sectional view showing the configuration of the low-voltage terminal box 224 and coupling 225 of the explosion-proof high-voltage power supply unit 201 shown in Figure 3. As shown in the figure, the low-voltage terminal box 224 has low-voltage terminals Ta and Tb inside. The power cable C is drawn into the low-voltage terminal box 224 from the power cable entry port. Inside the low-voltage terminal box 224, the end of power cable Ca is connected to low-voltage terminal Ta, and the end of power cable Cb is connected to low-voltage terminal Tb.

[0042] As described above, the low-voltage terminals Ta and Tb can be ignition sources. That is, if flammable gas flows into the low-voltage terminal box 224 and a short circuit occurs between the low-voltage terminals Ta and Tb, there is a risk of explosion. Therefore, the distance W between the low-voltage terminals Ta and Tb must be separated as much as possible to maintain insulation and prevent a short circuit, depending on the voltage. In this invention, as described above, by using an air seal with inert gas GN and a coupling in combination, the intrusion of flammable gas is prevented with extremely high stability, so the distance W between the low-voltage terminals Ta and Tb can be made smaller than in conventional designs. In addition, this makes it possible to miniaturize and save space in the low-voltage terminal box 224.

[0043] As an example of a preferred embodiment of the present invention, in a low-pressure terminal box 224 equipped with a coupling 225, if nitrogen gas is sealed inside as the inert gas NG while maintaining an internal pressure of 0.5 kPa, the distance between multiple terminals can be 200 mm or less while ensuring sufficient safety.

[0044] Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and any modifications, improvements, etc. that can achieve the objectives of the present invention are included in the present invention.

[0045] For example, in the embodiments described above, nitrogen is given as an example of an inert gas GN, but it is not limited to nitrogen. Other inert gases that can achieve the objective of explosion prevention may be used.

[0046] Furthermore, in the embodiment described above, a method of connecting a coupling 225 to the cable entry port is employed as a sealing means to prevent flammable gas from entering through the gap in the cable entry port of the low-voltage terminal box 224, but it is not limited to the coupling 225. Other methods may be used as long as the objective of preventing gaps from forming in the cable entry port is achieved. [Explanation of symbols]

[0047] 11. Wet electrostatic precipitator 111 Upper casing 113 Lower casing 114 Frame 121 Top Grid 122 Dust collection electrode 123 Lower Grid 124 Electrode Rods 125 Discharge wires 126 weights 127 Upward spray nozzle 128 Cleaning pipes 129 Downward spray nozzle 201 High-voltage power supply 221 Oil tank 222 Protective duct 223 Earthing switch 224 Low-voltage terminal box 225, 225a, 225b, 225c coupling 226 Conduit 227 Ventilated pressure box 228 Pressure Gauge 229 Safety valve 301 First inert gas filled section 302 Second inert gas filling section 303 Third inert gas filled section 304 Blower C, Ca, Cb power cable GN Inert Gas Ta, Tb Low-voltage terminals W is the distance between low-voltage terminals.

Claims

1. A high-voltage power supply device equipped with an electrostatic precipitator and a low-voltage terminal box for sealing low-voltage terminals, which are arranged at a predetermined distance apart, A sealing means including a coupling connected to the cable entry port of the low-voltage terminal box, A sealing means for sealing an inert gas inside the low-voltage terminal box, A pressure gauge that constantly monitors the internal pressure of the low-voltage terminal box, It has, The inert gas is nitrogen gas, and the inside of the low-pressure terminal box is maintained at a predetermined internal pressure. High-voltage power supply unit.

2. An electrostatic precipitator comprising the high-voltage power supply device described in claim 1.

3. The electrostatic precipitator according to claim 2, wherein the high-voltage power supply is located in close proximity to the upper housing on which the exhaust port of the electrostatic precipitator is installed.

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