WO2022038894A1

WO2022038894A1 - Electric dust collector

Info

Publication number: WO2022038894A1
Application number: PCT/JP2021/024036
Authority: WO
Inventors: 啓輔山城
Original assignee: 富士電機株式会社
Priority date: 2020-08-20
Filing date: 2021-06-24
Publication date: 2022-02-24
Also published as: CN115003416A; JP2022035345A; EP4082668A1; KR20220114086A; EP4082668A4

Abstract

Provided is a technology capable of collecting particulate matter more efficiently. An electric dust collector 200 according to an embodiment of the present disclosure comprises: a charging part 210 which includes charging electrodes 212, 214 facing each other and in which a voltage is applied between the charging electrodes 212, 214 and a corona discharge is generated so that particulate matter contained in exhaust gas of main engine 100 passing through the charging part 210 is charged; and a collecting part 220 which includes collecting electrodes 222, 224 and in which a voltage is applied between the collecting electrodes 222, 224 and the particulate matter charged by the charging part 210 is collected by Coulomb force. The collecting electrode 224 that is one of the collecting electrodes 222, 224 and attracts particulate matter by Coulomb force includes a main body 224A configured to surround a hollow space, and has through hole 224B which opens to the hollow space in a flat plate part 224A1 facing the other collecting electrode.

Description

Electrostatic precipitator

This disclosure relates to an electrostatic precipitator.

For example, a charged part that charges particulate matter (PM: Particulate Matter) contained in gas, and a dust collecting part that is arranged adjacent to the downstream side of the charged part and collects charged particulate matter by Coulomb force. An electric dust collector having a (collecting portion) is known (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2018-126714

However, in Patent Document 1, the electrode of the collecting portion for applying an electric field to the charged particulate matter is in the shape of a flat plate. Therefore, depending on the speed of the gas flow or the like, the particulate matter collected on the surface may re-scatter.

Therefore, in view of the above problems, it is an object of the present invention to provide a technique capable of collecting particulate matter more efficiently.

In order to achieve the above object, in one embodiment of the present disclosure,
A charged part that includes two opposing charged electrodes, a voltage is applied between the two charged electrodes, and a corona discharge is generated to charge the particulate matter in the passing gas.
It includes two collecting electrodes facing each other, and includes a collecting portion in which a voltage is applied between the two collecting electrodes and the particulate matter charged by the charged portion is collected by Coulomb force.
One of the two collection electrodes is configured to surround the hollow space, and an opening for opening the hollow space is provided in a portion facing the other collection electrode.
An electrostatic precipitator is provided.

According to the above-described embodiment, particulate matter can be collected more efficiently.

It is a figure which shows an example of the exhaust gas purification system including the electrostatic precipitator. It is a figure which shows an example of an electric dust collector. It is a figure which shows an example of the structure of a charged electrode. It is a figure which shows an example of the structure of a collection electrode. It is a figure which shows an example of the structure of a collection electrode. It is a figure explaining the control method of the applied voltage of a collecting part.

Hereinafter, embodiments will be described with reference to the drawings.

[Overview of exhaust gas purification system]
First, the exhaust gas purification system 1 including the electrostatic precipitator 200 according to the present embodiment will be described with reference to FIG.

FIG. 1 is a diagram showing an example of an exhaust gas purification system 1 including an electrostatic precipitator 200 according to the present embodiment.

The exhaust gas purification system 1 is mounted on a ship. Hereinafter, the term "ship" means a ship on which the electrostatic precipitator 200 is mounted, unless otherwise specified.

As shown in FIG. 1, the exhaust gas purification system 1 includes a main engine 100, an electrostatic precipitator 200, a scrubber 300, and a pump 400. The exhaust gas purification system 1 purifies the exhaust gas discharged from the main engine 100 and discharges it to the outside from the chimney of the ship.

The main engine 100 (an example of an engine) drives the propeller to rotate and propels the ship. The main engine is, for example, a diesel engine that can use heavy fuel oil C as fuel.

The electrostatic precipitator 200 collects particulate matter (PM) contained in the exhaust gas (an example of gas) of the main engine 100. The exhaust gas collected by the electrostatic precipitator 200 (from which particulate matter has been removed) is sent to the scrubber 300.

The scrubber 300 sprays seawater supplied through the pump 400 into the exhaust gas of the main engine 100 passing through the inside thereof, and causes the seawater to absorb sulfur oxides (SOx) contained in the main engine 100. The seawater supplied to the scrubber 300 may be seawater that is constantly pumped from the sea by the open loop method, or seawater that is circulated (reused) while being neutralized in the neutralization tank by the closed loop method. May be. The exhaust gas from the scrubber 300 from which the SOx component has been removed is released to the atmosphere outside the ship through the chimney of the ship. In the case of the open loop method, the seawater discharged from the scrubber 300 that has absorbed the SOx component of the exhaust gas is discharged into the sea outside the ship, and in the case of the closed loop method, it is returned to the neutralization tank for reuse. Therefore, a neutralization treatment is applied.

The pump 400 pumps seawater to the scrubber 300 in the sea or from a neutralization tank.

As described above, the exhaust gas purification system 1 can purify the exhaust gas of the main engine 100 by using the electrostatic precipitator 200 and the scrubber 300.

[Example of electrostatic precipitator]
Next, an example of the electrostatic precipitator 200 will be described with reference to FIGS. 2 to 6.

<Structure of electrostatic precipitator>
FIG. 2 is a diagram showing an example of the electrostatic precipitator 200 according to the present embodiment. FIG. 3 is a diagram showing an example of the structure of the charged unit 210 (charged electrodes 212, 214). Specifically, FIG. 3 is a front view of the

charged electrodes

212 and 214 as viewed along the direction of flow. 4 and 5 are views showing an example of the structure of the collection unit 220 (collection electrode 222,224). Specifically, FIG. 4 is a vertical cross-sectional view of the

collection electrodes

222 and 224 with respect to the direction of the flow of exhaust gas, and FIG. 4 is a view from the collection electrode 222 facing the collection electrode 224. It is a figure.

As shown in FIG. 2, the electrostatic precipitator 200 includes a charging unit 210, a collecting unit 220, and a control unit 230.

The charged unit 210 includes

charged electrodes

212 and 214 and a DC power supply 216.

The

charged electrodes

212 and 214 are arranged so as to face each other, and a corona discharge is generated between them by the voltage applied by the DC power supply 216. As a result, the particulate matter that passes through the charged portion 210 can be charged (charged). The

charged electrodes

212 and 214 may be configured by appropriately using a conductive material such as stainless steel, tungsten, titanium, or a carbon material. Hereinafter, the same may apply to the

collection electrodes

222 and 224 described later.

The DC power supply 216 (an example of the first power supply) applies a voltage for generating a corona discharge between the

charged electrodes

212 and 214. Specifically, the positive electrode of the DC power supply 216 is connected to the charged electrode 214 and grounded, and the negative electrode of the DC power supply 216 is connected to the charged electrode 212. As a result, a negative voltage is applied between the

charged electrodes

212 and 214 so that the charged electrode 214 has a reference potential (ground potential) and the charged electrode 212 has a negative high potential. Therefore, a corona discharge is generated from the charged electrode 212, and the particulate matter of the exhaust gas passing between the

charged electrodes

212 and 214 can be negatively charged.

On the contrary, the DC power supply 216 may have a negative electrode connected to the charged electrode 214 and grounded, and the positive electrode thereof may be connected to the charged electrode 212. In this case, a positive voltage is applied between the

charged electrodes

212 and 214 so that the charged electrode 214 becomes a reference potential and the charged electrode 212 has a positive high potential. Therefore, the corona discharge from the charged electrode 212 can positively charge the particulate matter of the exhaust gas passing between the

charged electrodes

212 and 214.

As shown in FIGS. 2 and 3, the

charged electrodes

212 and 214 may be configured as a pair of cylindrical coaxial electrode discharge electrodes and counter electrodes (hereinafter, “cylindrical coaxial electrode pair”). Specifically, the charged electrode 214 as the counter electrode has a substantially cylindrical inner peripheral surface extending in the direction along the direction of the exhaust gas flow, and the charged electrode 212 as the discharge electrode is inside the charged electrode 214. It may have an elongated shape extending on the central axis of the peripheral surface. The term "abbreviation" is intended to tolerate manufacturing errors, for example, and is used hereinafter with the same meaning. As a result, the distance (gap length) from the charged electrode 214 on the reference potential side can be made substantially uniform at any position of the charged electrode 212 on the high voltage side. Therefore, it is possible to avoid the transition to spark discharge and form a stable corona discharge. Further, since the charged electrode 212 and the charged electrode 214 (inner peripheral surface) are provided so as to extend in the direction of the flow of the exhaust gas, the pressure loss in the charged portion 210 can be reduced.

Further, as shown in FIG. 3, the charged electrode 214 has a plurality of substantially cylindrical inner peripheral surfaces arranged in parallel with respect to the direction of the exhaust gas flow, and each of them has a corresponding charged electrode 212. A plurality of cylindrical coaxial electrode pairs are configured by being inserted. As a result, stable corona discharge is realized, and while maintaining the dimensions of the exhaust gas flow direction of the charged portion 210, the exhaust gas flow area is secured, so that the pressure loss is further reduced and the exhaust gas is exhausted. The flow rate of gas can be relatively increased.

The collecting unit 220 is arranged adjacent to the downstream side of the exhaust gas flow of the charged unit 210. The collection unit 220 includes a collection electrode 222,224 and a DC power supply 226.

The

collection electrodes

222 and 224 are arranged so as to face each other, and a voltage is applied between them by the DC power supply 226 to apply a Coulomb force to the particulate matter in the exhaust gas charged by the charged unit 210 to collect the particles. Collect on the collecting electrode 224.

The DC power supply 226 (an example of the second power supply) applies a voltage for generating an electric field between the

collection electrodes

222 and 224. The DC power supply 226 is provided separately from the DC power supply 216 that applies a voltage to the charging unit 210 (charged electrodes 212, 214). As a result, the DC power supply 226 can change the voltage applied to the collection unit 220 (collection electrode 222, 224) independently of the voltage applied to the charge unit 210. Specifically, the positive electrode of the DC power supply 226 is connected to the collection electrode 224 and is grounded, and the negative electrode of the DC power supply 226 is connected to the collection electrode 222. As a result, a negative voltage is applied between the

collection electrodes

222 and 224 so that the collection electrode 224 becomes a reference potential (ground potential) and the collection electrode 222 has a negative high potential. Therefore, when the particulate matter negatively charged by the charged portion 210 flows between the

collection electrodes

222 and 224, the Coulomb force attracted to the collection electrode 224 at the reference potential acts on the particulate matter to collect the particles. Particulate matter is collected on the electrode 224.

The DC power supply 226 may be grounded while its positive electrode is connected to the collection electrode 224 and its negative electrode is connected to the collection electrode 222. As a result, a positive voltage is applied between the

collection electrodes

222 and 224 so that the collection electrode 222 becomes a reference potential (ground potential) and the collection electrode 224 has a positive high potential. Therefore, when the particulate matter negatively charged by the charged portion 210 flows between the

collection electrodes

222 and 224, the Coulomb force attracted to the positive high potential collection electrode 224 acts on the particulate matter. Particulate matter is collected on the collection electrode 224. That is, when the particulate matter is negatively charged by the charged portion 210, the DC power supply 226 applies a voltage to the

collection electrodes

222 and 224 so that an electric field directed from the collection electrode 224 to the collection electrode 222 is applied. It may be applied. Further, as described above, when the particulate matter is positively charged by the charging unit 210, the DC power supply 226 has a collection electrode 222 so that an electric field directed from the collection electrode 222 to the collection electrode 224 is applied. A voltage may be applied to the 224. As a result, when the particulate matter positively charged by the charged portion 210 flows between the

collection electrodes

222 and 224, a Coulomb force acts on the particulate matter in the direction of the electric field, and the particulate matter acts on the collection electrode 224. Is collected. Specifically, when the particulate matter is positively charged by the charging unit 210, the positive electrode of the DC power supply 226 is connected to the collection electrode 222, and the negative electrode of the DC power supply 226 is connected to the collection electrode 224. Either one should be grounded.

The collection electrode 222 may have a flat plate shape extending in a direction along the direction of the exhaust gas flow, as shown in FIGS. 2 and 4, for example.

The collection electrode 224 is configured to surround the hollow space (in other words, to have a hollow box shape), as shown in FIGS. 2, 4, and 5, for example, and the collection electrode 222 and the collection electrode 222. A through hole 224B that opens a hollow space is provided in the facing portion. Specifically, the collection electrode 224 includes a main body portion 224A, a through hole 224B, and a partition plate 224C. Further, both ends of the collection electrode 224 in the depth direction of FIG. 4 are closed by, for example, a flat plate or the like.

The main body portion 224A includes two flat plate portions 224A1 facing each of the collection electrodes 222 on both sides, and curved surface portions 224A2 at both ends connecting the two flat plate portions 224A1 to each other. As a result, a hollow space surrounded by two flat plate portions 224A1 and curved surface portions 224A2 at both ends thereof is formed.

The through hole 224B (an example of an opening) is provided in the flat plate portion 224A1 so as to penetrate the flat plate portion 224A1. Specifically, as shown in FIGS. 4 and 5, a large number of through holes 224B are provided so as to occupy a very small area with respect to the area of the flat plate portion 224A1. As a result, the through hole 224B opens the hollow space inside the main body portion 224A, and allows the space between the

collection electrodes

222 and 224 to communicate with the space inside the collection electrode 224 (main body portion 224A). Can be done. Therefore, the particulate matter in the exhaust gas sucked by the Coulomb force can be accommodated in the hollow space inside the collection electrode 224 (main body portion 224A). Therefore, it is possible to suppress the re-scattering of the particulate matter collected on the collection electrode 224. In particular, since the exhaust gas discharged from the main engine 100 of a ship has a relatively high flow velocity, for example, in a flat plate-shaped collection electrode, the possibility of re-scattering is relatively high. On the other hand, the collection electrode 224 can suppress the re-scattering of the collected particulate matter even when the flow velocity is relatively high as in the case of the exhaust gas from the main engine 100 of the ship. ..

The partition plate 224C is configured to partition the hollow space inside the main body portion 224A into a space on one flat plate portion 224A1 side and a space on the other flat plate portion 224A1 side. As a result, particulate matter flowing into the hollow space inside the main body portion 224A from the through holes 224B of both flat plate portions 224A1 can be collected in a form of adhering to both sides of the partition plate 224C. Therefore, by fixing the particulate matter in the hollow space where the flow velocity is relatively low as compared with the mainstream of the exhaust gas, the particulate matter can be stably collected.

As described above, in this example, the functional part (charged part 210) for charging the particulate matter of the exhaust gas and the functional part for collecting the particulate matter are separated in the direction of the flow of the exhaust gas, and electrodes are provided for each. Pairs (charged

electrodes

212, 214, and collection electrodes 222,224) are provided.

For example, a discharge electrode that generates a corona discharge and a collection electrode that collects particulate matter charged by the corona discharge are opposed to each other, and a voltage is applied between the discharge electrode and the collection electrode. It is also possible to integrate the function of the charging unit 210 and the function of the collecting unit 220. However, in this case, the particulate matter charged by the discharge moves in the flow of the exhaust gas, so that the actual collection may be concentrated on the downstream side of the flow of the exhaust gas in the collection electrode. high. Therefore, the upstream portion of the exhaust gas flow in the collection electrode does not perform the function of collecting particulate matter, and the discharge electrode needs to be adjusted to the length of the collection electrode, so that the exhaust gas flow. There is a possibility that it will be unnecessarily long to the downstream side of. In particular, since the flow velocity of the exhaust gas of the main engine 100 of the ship is relatively high (large), the length (size) of the collection electrode and the discharge electrode may become unnecessarily large. Therefore, the size of the electrostatic precipitator 200 may increase.

On the other hand, in this example, the function of charging the particulate matter of the exhaust gas and the function of collecting the charged particulate matter are separated in the direction of the flow of the exhaust gas, and the respective sizes are set. It can be optimized according to the function. Therefore, the size of the electrostatic precipitator 200 can be reduced. In particular, it is suitable when there is not enough space for arranging the electrostatic precipitator 200, such as a ship.

The control unit 230 controls the DC power supply 226. The function of the control unit 230 is realized by arbitrary hardware, an arbitrary combination of hardware and software, and the like. For example, the control unit 230 includes a memory device such as a CPU (Central Processing Unit) and a RAM (Random Access Memory), a non-volatile auxiliary storage device such as a ROM (Read Only Memory), and an interface device for external and input / output. It is mainly composed of computers including.

Further, various signals used for controlling the DC power supply 226 are input to the control unit 230. For example, a signal corresponding to a measured value of the temperature of the exhaust gas flowing into the electrostatic collector 200 (exhaust gas temperature) is input to the control unit 230 from a temperature sensor installed near the inlet of the exhaust gas of the electric dust collector 200. It's okay. Further, for example, a signal regarding the load factor (engine load factor) of the main engine 100 may be input to the control unit 230 from another control unit that controls the main engine 100. Further, for example, the control unit 230 receives a signal corresponding to the measured value of the temperature (engine temperature) of the predetermined portion of the main engine 100 from the temperature sensor installed in the predetermined portion of the main engine 100 (for example, the exhaust manifold). May be entered. Further, for example, in the control unit 230, a temperature sensor installed at a predetermined portion of the electrostatic precipitator 200 (for example, a housing of the electrostatic precipitator 200A) can be used to measure the temperature (dust collector temperature) of the predetermined portion of the electrostatic precipitator 200. The corresponding signal may be input. Further, for example, a signal corresponding to a measured value of the temperature of the exhaust pipe (exhaust pipe temperature) is input to the control unit 230 from a temperature sensor installed in the exhaust pipe between the main engine 100 and the electrostatic precipitator 200. It's okay.

<Control method of electrostatic precipitator>
FIG. 6 is a diagram illustrating a method of controlling the applied voltage of the collection unit 220 (collection electrode 222,224). Specifically, FIG. 6 shows a graph 610 showing the relationship between the temperature of the gas to be dust-collected (exhaust gas in this embodiment) and the resistance of the particulate matter (PM), and the gas to be dust-collected. A graph 620 showing the relationship between the temperature of (exhaust gas) and the applied voltage of the collection unit 220 is included.

As shown in Graph 610, the resistivity (that is, conductivity) of the particulate matter changes depending on the temperature state of the exhaust gas.

When the resistivity of the particulate matter increases and the insulating property becomes relatively high, the particulate matter acts as a dielectric, and the particulate matter collected and deposited on the collection electrode 224 may undergo dielectric polarization. Therefore, the particulate matter having a relatively high resistivity may have a potential difference opposite to the potential difference of the collecting portion 220 due to the dielectric polarization. In particular, when the deposited layer of the particulate matter becomes relatively thick, the potential difference also becomes relatively large, and as a result, back discharge occurs, and the particulate matter may be scattered most.

Specifically, it is known that when the resistivity of the particulate matter rises to about 10 ¹¹ [Ωcm], there is a high possibility that back discharge will occur. Therefore, as shown in Graph 610, the resistivity of the particulate matter is 10 ¹¹ [Ωcm] or more in the range of the temperature of the particulate matter, that is, the temperature of the exhaust gas in the range of about 100 ° C. to about 200 ° C., and the back discharge is performed. Is more likely to occur.

On the other hand, in this example, the control unit 230 controls the DC power supply 226, the resistivity of the particulate matter is relatively low (that is, the conductivity is relatively high), and back discharge may occur. When the property is relatively low, the applied voltage of the collecting unit 220 is relatively large (high). On the other hand, when the resistivity of the particulate matter is relatively high (that is, the conductivity is relatively low) and the possibility of back discharge is relatively high, the control unit 230 applies the collection unit 220. Make the voltage relatively small (low). As a result, the control unit 230 can suppress the re-scattering of the particulate matter due to back discharge under the premise that a relatively high electric field for collecting the particulate matter is applied.

For example, as shown in Graph 620, the control unit 230 may switch the voltage applied between the

collection electrodes

222 and 224 of the collection unit 220 according to the temperature state of the exhaust gas flowing into the electrostatic precipitator 200. .. Specifically, when the temperature of the exhaust gas flowing into the electrostatic precipitator 200 is lower than 100 ° C. or higher than 200 ° C., the control unit 230 relatives the applied voltage between the

collection electrodes

222 and 224. The DC power supply 226 may be controlled by setting the predetermined value Va_H to a high value. On the other hand, when the temperature of the exhaust gas flowing into the electrostatic precipitator 200 is in the range of 100 ° C. or higher and 200 ° C. or lower, the control unit 230 sets the applied voltage between the

collection electrodes

222 and 224 to a relatively low predetermined value Va_L. The DC power supply 226 may be controlled by setting to. As a result, the control unit 230 relatively lowers the applied voltage between the

collection electrodes

222 and 224 in the temperature region of the exhaust gas where back discharge is likely to occur, and collects particulate matter. It is possible to suppress the re-scattering of the gas.

As described above, the temperature state of the exhaust gas flowing into the electrostatic precipitator 200 is measured by a temperature sensor arranged near the inlet of the electrostatic precipitator 200, and a signal corresponding to the measured value is taken into the control unit 230. It's okay. Further, the control unit 230 determines the temperature of the exhaust gas flowing into the electrostatic precipitator 200, for example, based on the temperature (measured value) of the exhaust gas measured by the temperature sensor installed further upstream from the inlet of the electrostatic precipitator 200. You may estimate. Further, the control unit 230 may estimate the temperature of the exhaust gas flowing into the electrostatic precipitator 200 from other information as described later.

Further, for example, the control unit 230 applies a voltage between the

collection electrodes

222 and 224 of the collection unit 220 according to the state of the main engine 100 (an example of a gas supply source) related to the temperature of the exhaust gas. May be switched.

The control unit 230 may switch the voltage applied between the

collection electrodes

222 and 224 of the collection unit 220 according to, for example, the load state of the main engine 100 (for example, the engine load factor). As shown in FIG. 6, when the load of the main engine 100 is relatively small, the temperature of the exhaust gas is low, and when the load of the main engine 100 is relatively high, the temperature of the exhaust gas is relatively high. Is.

Specifically, when the load factor of the main engine 100 is lower than the predetermined value LF1 or higher than the predetermined value LF2 (> LF1), the control unit 230 applies the voltage between the

collection electrodes

222 and 224. May be set to a predetermined value Va_H. On the other hand, when the load factor of the main engine 100 is in the range of the predetermined value LF1 or more and the predetermined value LF2 or less, the control unit 230 may set the applied voltage between the

collection electrodes

222 and 224 to the predetermined value Va_L. The predetermined values LF1 and LF2 correspond to the load factors of the main engine 100 when the temperatures of the exhaust gas flowing into the electrostatic precipitator 200 are 100 ° C. and 200 ° C., respectively.

Information on the load factor of the main engine 100 may be acquired from another control unit that controls the main engine 100, as described above. Further, data regarding the operating status of the main engine 100 may be fetched from another control unit into the control unit 230, and the control unit 230 may calculate the load factor of the main engine 100 from the data regarding the captured operating status.

Further, the control unit 230 may switch the voltage applied between the

collection electrodes

222 and 224 of the collection unit 220 according to, for example, the temperature state of a predetermined portion of the main engine engine 100. When the temperature of the exhaust gas of the main engine 100 becomes relatively low, the temperature of the main engine 100 itself also becomes relatively low, and when the temperature of the exhaust gas of the main engine 100 becomes relatively high, the temperature of the main engine 100 itself also becomes relatively low. This is because it is relatively high.

Specifically, when the temperature of the predetermined portion of the main engine 100 is lower than the predetermined value ET1 or higher than the predetermined value ET2 (> ET1), the control unit 230 applies the voltage between the

collection electrodes

222 and 224. The voltage may be set to a predetermined value Va_H. On the other hand, when the temperature of the predetermined portion of the main engine 100 is in the range of the predetermined value ET1 or more and the predetermined value ET2 or less, the control unit 230 sets the applied voltage between the

collection electrodes

222 and 224 to the predetermined value Va_L. good. The predetermined values ET1 and ET2 correspond to the temperatures of the predetermined parts of the main engine 100 when the temperature of the exhaust gas flowing into the electrostatic precipitator 200 is 100 ° C. and 200 ° C., respectively.

As described above, the temperature of the predetermined portion of the main engine 100 is measured by the temperature sensor installed in the main engine 100, and the signal corresponding to the measured value may be taken into the control unit 230.

Further, the control unit 230 may estimate the temperature of the exhaust gas flowing into the electrostatic precipitator 200 from the load factor of the main engine 100, the temperature state of a predetermined portion, and the like. Then, the control unit 230 switches the voltage applied between the

collection electrodes

222 and 224 of the collection unit 220 by the same method as described above according to the estimated value of the temperature of the exhaust gas flowing into the electrostatic precipitator 200. You may.

Further, for example, the control unit 230 captures the collection unit 220 according to the temperature (exhaust pipe temperature) of a predetermined portion of the exhaust pipe (an example of the gas supply path) between the main engine 100 and the electrostatic precipitator 200. The voltage applied between the

collector electrodes

222 and 224 may be switched. Further, the control unit 230 may switch the voltage applied between the

collection electrodes

222 and 224 of the collection unit 220 according to the temperature of a predetermined portion of the electrostatic precipitator 200 (dust collector temperature). When the temperature of the exhaust gas of the main engine 100 becomes relatively low, the temperature of the exhaust pipe and the electric dust collector 200 also becomes relatively low, and when the temperature of the exhaust gas of the main engine 100 becomes relatively high, the exhaust pipe and the electric dust collector 200 also become relatively low. This is because the temperature of 200 is also relatively high.

Specifically, when the exhaust pipe temperature is lower than the predetermined value XT1 or higher than the predetermined value XT2 (> XT1), the control unit 230 sets the applied voltage between the

collection electrodes

222 and 224 to the predetermined value Va_H. May be set to. On the other hand, when the exhaust pipe temperature is in the range of the predetermined value XT1 or more and the predetermined value XT2 or less, the control unit 230 may set the applied voltage between the

collection electrodes

222 and 224 to the predetermined value Va_L. The predetermined values XT1 and XT2 correspond to the exhaust pipe temperature when the temperature of the exhaust gas flowing into the electrostatic precipitator 200 is 100 ° C. and 200 ° C., respectively. Further, the same method may be adopted in the case of being controlled according to the dust collector temperature.

Further, the control unit 230 may estimate the temperature of the exhaust gas flowing into the electric dust collector 200 based on the exhaust pipe temperature, the dust collector temperature, and the like. Then, the control unit 230 switches the voltage applied between the

collection electrodes

[Other examples of electrostatic precipitators]
Next, another example of the electrostatic precipitator will be described.

The electrostatic precipitator 200 of the above-mentioned example may be appropriately modified or modified.

For example, in the electrostatic precipitator 200 of the above-mentioned example, only one through hole 224B of the collection electrode 224 may be provided in the flat plate portion 224A1 facing the collection electrode 222.

Further, for example, in the electrostatic precipitator 200 of the above example, the lower limit of the temperature range of the exhaust gas that relatively lowers the applied voltage between the

collection electrodes

222 and 224 is around 100 ° C instead of 100 ° C. It may be set within the predetermined range of. This predetermined range may be, for example, a range of 10 ° C. around 100 ° C., that is, a range of 90 ° C. to 110 ° C. Similarly, in the electrostatic precipitator 200 of the above example, the upper limit of the temperature range of the exhaust gas that relatively lowers the applied voltage between the

collection electrodes

222 and 224 is around 200 ° C instead of 200 ° C. It may be set within a predetermined range. This predetermined range may be, for example, a range of 10 ° C. before and after, that is, a range of 190 ° C. to 210 ° C.

Further, for example, in the electrostatic precipitator 200 of the above-mentioned example, the applied voltage between the

collection electrodes

222 and 224 is switched between a case of switching from a relatively high state to a low state and a case of switching from a low state to a high state. The boundary value of the temperature of the exhaust gas may be different. For example, when the temperature of the exhaust gas changes from less than 100 ° C to 100 ° C or higher, the control unit 230 may switch the applied voltage between the

collection electrodes

222 and 224 from a relatively high state to a low state. .. On the other hand, the control unit 230 applies a voltage between the

collection electrodes

222 and 224 when the temperature of the exhaust gas is lower than the predetermined temperature (for example, 95 ° C.) lower than 100 ° C. and becomes lower than the predetermined temperature. You may switch from a relatively low state to a high state. Similarly, when the temperature of the exhaust gas changes from more than 200 ° C to 200 ° C or lower, the control unit 230 switches the applied voltage between the

collection electrodes

222 and 224 from a relatively high state to a low state. good. On the other hand, the control unit 230 relatively applies a voltage between the

collection electrodes

222 and 224 when the temperature of the exhaust gas exceeds a predetermined temperature (for example, 205 ° C.) higher than 200 ° C. and exceeds the predetermined temperature. You may switch from a low state to a relatively high state. As a result, it is possible to suppress a situation in which the applied voltage between the

collection electrodes

222 and 224 is switched at a relatively high frequency.

Further, for example, the electrostatic precipitator 200 of the above-mentioned example may collect particulate matter of exhaust gas emitted by an engine arranged at a place different from that of a ship.

Further, for example, the electrostatic precipitator 200 of the above-mentioned example may collect particulate matter contained in a gas different from the exhaust gas of the engine.

[Action]
Next, the operation of the electrostatic precipitator 200 according to the present embodiment will be summarized.

In the present embodiment, the electrostatic precipitator 200 includes a charging unit 210 and a collecting unit 220. Specifically, the charged unit 210 includes opposite charged

electrodes

212 and 214, and a gas (for example, exhaust gas) that is passed by a voltage applied between the charged

electrodes

212 and 214 to generate a corona discharge. Charges the particulate matter inside. Further, the collecting unit 220 includes the opposing collecting

electrodes

222 and 224, and a voltage is applied between the collecting

electrodes

222 and 224 to collect particulate matter charged by the charged unit 210 by Coulomb force. .. The collection electrode 224 of one of the

collection electrodes

222 and 224 is configured to surround the hollow space, and a through hole 224B for opening the hollow space is provided in a portion facing the other collection electrode 222. Be done.

Thereby, the electrostatic precipitator 200 can separate the function of charging the particulate matter in the passing gas and the function of collecting the charged particulate matter in the direction of the gas flow. Therefore, the size can be optimized according to each function, and as a result, the size of the electrostatic precipitator 200 can be reduced.

Further, by attracting the particulate matter charged by the Coulomb force to the collection electrode 224, the particulate matter is collected in the hollow space inside from the through hole 224B of the collection electrode 224. Therefore, even when the flow velocity of the gas is relatively high, it is not easily affected by the flow velocity and re-scattering can be suppressed. Therefore, particulate matter in the gas can be collected more efficiently.

Further, in the present embodiment, one collection electrode 224 is used as a reference potential, and the other collection electrode 222 has the same polarity as the high-potential charged electrode 212 of the charged

electrodes

212 and 214. A voltage may be applied between 222 and 224. Further, even if a voltage is applied between the

collection electrodes

222 and 224 so that the other collection electrode 222 has a reference potential and one collection electrode 224 has the opposite polarity to the high potential charged electrode 212. good.

Thereby, the electrostatic precipitator 200 can apply an electric field between the

collection electrodes

222 and 224 so that the particulate matter charged by the charging unit 210 is collected by the collection electrode 224.

Further, in the present embodiment, the other collection electrode 222 has a flat plate shape, one collection electrode 224 has a flat plate portion 224A1 facing the other collection electrode 222, and the flat plate portion 224A1 has a flat plate portion 224A1. , A plurality of through holes 224B may be provided to open the hollow space.

Thereby, the electrostatic precipitator 200 can collect the particulate matter charged by the charged portion 210 into the hollow space inside the collecting electrode 224 through the plurality of through holes 224B.

Further, in the present embodiment, the charging unit 210 may include a DC power supply 216 that applies a voltage to the charged

electrodes

212 and 214. The collection unit 220 may include a DC power supply 226 different from the DC power supply 216 that applies a voltage to the

collection electrodes

222 and 224.

Thereby, the electrostatic precipitator 200 can change the voltage applied to the collecting unit 220 independently of the voltage applied to the charging unit 210.

Further, in the present embodiment, the electrostatic precipitator 200 (control unit 230) may change the magnitude of the voltage applied between the

collection electrodes

222 and 224 according to the temperature state of the passing gas.

For example, the conductivity (resistivity) of particulate matter changes depending on the temperature state of the passing gas. Then, when the conductivity decreases (that is, the resistivity increases), the collected particulate matter has a high reverse potential with respect to the potential of the collection electrode 224 due to the dielectric polarization. As a result, back discharge may occur and the particulate matter may re-scatter.

On the other hand, the electrostatic precipitator 200 can change the magnitude of the applied voltage of the collecting unit 220 according to the temperature state of the gas, which affects the conductivity of the particulate matter. As a result, the electrostatic precipitator 200 reduces the applied voltage relatively and suppresses the electric field required for charge-up, for example, in a situation where the conductivity of the particulate matter decreases and back discharge is likely to occur. be able to. Therefore, the electrostatic precipitator 200 can suppress the maximum scattering of particulate matter due to back discharge.

Further, in the present embodiment, the electrostatic precipitator 200 (control unit 230) has a large voltage applied between the

collection electrodes

222 and 224 according to the state of the gas supply source related to the temperature state of the passing gas. You may change the gas. For example, the electrostatic precipitator 200 (control unit 230) determines the magnitude of the voltage applied between the

collection electrodes

222 and 224 according to the load state of the main engine 100 or the temperature state of a predetermined portion of the main engine 100. You may change it.

Thereby, the electrostatic precipitator 200 can adjust the applied voltage in consideration of the conductivity of the particulate matter based on the relationship between the state of the gas supply source and the temperature state of the passing gas. Therefore, the electrostatic precipitator 200 can specifically suppress the maximum scattering of particulate matter due to back discharge.

Further, in the present embodiment, the electrostatic precipitator 200 (control unit 230) has a collection electrode depending on the temperature state of at least one of the gas supply path (for example, the exhaust pipe) to pass through and the predetermined portion of the electrostatic precipitator 200. The magnitude of the voltage applied between 222 and 224 may be changed.

As a result, the electrostatic precipitator 200 adjusts the applied voltage in consideration of the conductivity of the particulate matter based on the relationship between the temperature state of the gas supply path and the predetermined portion of the electrostatic precipitator 200 and the temperature state of the passing gas. can do. Therefore, the electrostatic precipitator 200 can specifically suppress the maximum scattering of particulate matter due to back discharge.

Further, in the present embodiment, the electrostatic precipitator 200 (control unit 230) is located between the two collection electrodes when the temperature of the passing gas is within the predetermined temperature range, as compared with the case where the temperature is outside the predetermined temperature range. Reduce the magnitude of the applied voltage. The predetermined temperature range is, for example, a range between a lower limit value defined within a predetermined range around 100 ° C. and an upper limit value defined within a predetermined range around 200 ° C.

Thereby, the electrostatic precipitator 200 can specifically suppress the electric field applied between the

collection electrodes

222 and 224 to be small (low) in the region where back discharge is likely to occur.

Further, in the present embodiment, the charged electrode 214 having the reference potential among the charged

electrodes

212 and 214 may have a substantially cylindrical inner peripheral surface extending in the direction in which the gas flows. The high-potential charged electrode 212 of the charged

electrodes

212 and 214 may be provided so as to extend in the direction of gas flow on substantially coaxial with the inner peripheral surface of the charged electrode 214.

This makes it possible to suppress the pressure loss of the passing gas in the charged portion 210. In addition, since the distance (gap length) from the charged electrode 214 on the reference potential side is substantially uniform at any position of the charged electrode 212 on the high voltage side, the transition to spark discharge is avoided and stable corona discharge is achieved. Can be formed.

Although the embodiments have been described in detail above, the present disclosure is not limited to such a specific embodiment, and various modifications and changes can be made within the scope of the gist described in the claims.

Finally, the present application claims priority based on Japanese Patent Application No. 2020-139592 filed on August 20, 2020, and the entire contents of the Japanese patent application are incorporated herein by reference.

1 Exhaust gas purification system 100 Main engine (engine, gas supply source)
200 Dust collector 210 Charge part 212,214 Charge electrode 216 DC power supply (first power supply)
220 Collection part 222,224 Collection electrode 224A Main body part 224A1 Flat plate part 224A2 Curved surface part 224B Through hole (opening)
224C partition plate 226 DC power supply (second power supply)
230 Control unit 300 Scrubber 400 Pump

Claims

A charged part that includes two opposing charged electrodes, a voltage is applied between the two charged electrodes, and a corona discharge is generated to charge the particulate matter in the passing gas.
It includes two collecting electrodes facing each other, and includes a collecting portion in which a voltage is applied between the two collecting electrodes and the particulate matter charged by the charged portion is collected by Coulomb force.
One of the two collection electrodes is configured to surround the hollow space, and an opening for opening the hollow space is provided in a portion facing the other collection electrode.
Electrostatic precipitator.
With the one collecting electrode as the reference potential, the other collecting electrode has the same polarity as the high potential charged electrode of the two charged electrodes, or the other collecting electrode has the reference potential. As a result, a voltage is applied between the two collection electrodes so that one of the collection electrodes has a polarity opposite to that of the high potential charged electrode.
The electrostatic precipitator according to claim 1.
The other collection electrode has a flat plate shape and has a flat plate shape.
The one collecting electrode has a flat plate portion facing the other collecting electrode and has a flat plate portion.
The flat plate portion is provided with a plurality of the openings that open the hollow space.
The electrostatic precipitator according to claim 1 or 2.
The charged portion includes a first power source that applies a voltage to the two charged electrodes.
The collection unit includes a second power source different from the first power source, which applies a voltage to the two collection electrodes.
The electrostatic precipitator according to any one of claims 1 to 3.
The magnitude of the voltage applied between the two collection electrodes is changed according to the temperature state of the gas.
The electrostatic precipitator according to any one of claims 1 to 4.
The magnitude of the voltage applied between the two collection electrodes is changed according to the state of the source of the gas related to the temperature state of the gas.
The electrostatic precipitator according to claim 5.
The supplier is an engine.
The gas is the exhaust gas of the engine.
The magnitude of the voltage applied between the two collection electrodes is changed according to the load state of the engine or the temperature state of a predetermined portion of the engine.
The electrostatic precipitator according to claim 6.
The magnitude of the voltage applied between the two collection electrodes is changed according to the temperature state of at least one of the gas supply path and the predetermined portion of the electrostatic precipitator.
The electrostatic precipitator according to claim 5.
When the temperature of the passing gas is within a predetermined temperature range, the magnitude of the voltage applied between the two collection electrodes is smaller than when the temperature is outside the temperature range.
The electrostatic precipitator according to any one of claims 5 to 8.
The temperature range is a range between a lower limit value defined within a predetermined range around 100 ° C. and an upper limit value defined within a predetermined range around 200 ° C.
The electrostatic precipitator according to claim 9.
Of the two charged electrodes, the charged electrode having the reference potential has a substantially cylindrical inner peripheral surface extending in the direction in which the gas flows.
The high-potential charged electrode of the two charged electrodes is provided so as to extend in the direction of flow of the gas on substantially coaxial with the inner peripheral surface.
The electrostatic precipitator according to any one of claims 1 to 10.