EP3991850A1

EP3991850A1 - Dust collector

Info

Publication number: EP3991850A1
Application number: EP21760283.8A
Authority: EP
Inventors: Kouhei Murakami
Original assignee: Fuji Electric Co Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2020-02-25
Filing date: 2021-01-22
Publication date: 2022-05-04
Also published as: WO2021171856A1; JP7243915B2; KR20220020991A; CN114144260A; EP3991850A4; JPWO2021171856A1

Abstract

There is provided a dust collector including: a dust collection unit configured to trap particles; a microwave generation unit configured to generate a microwave to be introduced into the dust collection unit, and cause the particles, which are trapped in the dust collection unit, to combust by the microwave: and an intensity detection unit configured to detect an intensity of the microwave which is not absorbed by the particles, in which the microwave generation unit is configured to control the intensity of the microwave to be introduced into the dust collection unit, based on the intensity of the microwave detected by the intensity detection unit. The intensity detection unit may include a derivation unit configured to derive, from the dust collection unit, at least a part of the microwave which is not absorbed by the particles, a microwave absorbing body configured to absorb the microwave derived from the dust collection unit, and a temperature detection unit configured to detect a temperature of the microwave absorbing body.

Description

BACKGROUND

1. TECHNICAL FIELD

The present invention relates to a dust collector.

2. RELATED ART

In the related art, an electric dust collector, "in which electrically charged particles that are collected by a dust collection unit are burned by microwaves", is known (for example, refer to Patent Document 1). In addition, a device, which detects an energy quantity of microwaves from a temperature of an electric wave absorbing body for absorbing the microwaves, is known (for example, refer to Patent Documents 2, 3).

Patent Document 1: PCT/JP2019/ 35325
Patent Document 2: Japanese Patent Application Publication No. 05-172884
Patent Document 3: Japanese Patent Application Publication No. 05-52889

3. TECHNICAL PROBLEM

In a dust collector, it is preferable to reduce energy consumption.

GENERAL DISCLOSURE

In order to solve the above problem, an aspect of the present invention provides a dust collector. The dust collector may include a dust collection unit configured to trap particles. The dust collector may include a microwave generation unit configured to generate a microwave to be introduced into the dust collection unit, and cause the particles, which are trapped in the dust collection unit, to combust by the microwave. The dust collector may include an intensity detection unit configured to detect an intensity of the microwave which is not absorbed by the particles. The microwave generation unit may control the intensity of the microwave to be introduced into the dust collection unit, based on the intensity of the microwave detected by the intensity detection unit.
The intensity detection unit may include a derivation unit configured to derive, from the dust collection unit, at least a part of the microwave which is not absorbed by the particles. The intensity detection unit may include a microwave absorbing body configured to absorb the microwave derived from the dust collection unit. The intensity detection unit may include a temperature detection unit configured to detect a temperature of the microwave absorbing body.
The microwave generation unit may switch the intensity of the microwave to be introduced into the dust collection unit, to a second intensity which is lower than a first intensity, when the temperature of the microwave absorbing body becomes higher than or equal to a first reference temperature in a state in which the microwave of the first intensity is introduced into the dust collection unit.
The microwave generation unit may switch the intensity of the microwave to be introduced into the dust collection unit, to the first intensity, when the temperature of the microwave absorbing body becomes lower than or equal to a second reference temperature in a state in which the microwave of the second intensity is introduced into the dust collection unit.
The dust collector may include a flame detection unit configured to detect that a flame is generated in the dust collection unit. The microwave generation unit may reduce the intensity of the microwave to be introduced into the dust collection unit, or stop the introduction of the microwave into the dust collection unit, when the flame is generated.
The dust collector may include a calculation unit configured to calculate an amount of combustion components of the particles deposited in the dust collection unit, based on an integrated time in which the microwave generation unit introduces the microwave of the first intensity into the dust collection unit.
The dust collector may include a calculation unit configured to calculate an amount of the particles introduced into the dust collection unit, based on a slope of a rising waveform in a time waveform of the temperature detected by the temperature detection unit.
The intensity detection unit may store, in advance, a relationship between the temperature of the microwave absorbing body and the intensity of the microwave, when the microwave is introduced into the dust collection unit in a state in which the particles are not present in the dust collection unit. The intensity detection unit may detect the intensity of the microwave, which is not absorbed by the particles, from the temperature of the microwave absorbing body, when the microwave is introduced into the dust collection unit in a state in which the particles are present in the dust collection unit.
The dust collector may include a calculation unit configured to calculate the intensity of the microwave absorbed by the particles, from a difference between the intensity of the microwave detected by the intensity detection unit and the intensity of the microwave introduced into the dust collection unit by the microwave generation unit.
The calculation unit may calculate the amount of the combustion components of the particles remaining in the dust collection unit, based on an time integral value of the intensity of the microwave absorbed by the particles.
Derivation units may be provided at a plurality of derivation locations of the dust collection unit. The microwave absorbing body may absorb the microwave obtained by combining microwaves derived by the plurality of derivation units.
The microwave generation unit may introduce the microwave into the dust collection unit from a plurality of introduction locations of the dust collection unit. The microwave absorbing body may be provided for each of the derivation locations. The microwave generation unit may control, based on the temperature of the microwave absorbing body at each of the derivation locations, the intensity of the microwave to be introduced from the corresponding introduction location.
An exhaust gas, which is exhausted by an exhaust gas source, may be introduced into the dust collection unit. The microwave generation unit may control the intensity of the microwave to be introduced into the dust collection unit, based on an operation state of the exhaust gas source, when the flame is generated.
The summary clause does not necessarily describe all necessary features of the embodiments of the present invention. The present invention may also be a sub-combination of the features described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram showing one configuration example of a dust collector 100 according to an embodiment of the present invention.
Fig. 2 is a schematic diagram showing one example of a dust collection unit 120.
Fig. 3 is a view showing one example of a configuration of a partition wall 32.
Fig. 4 is a diagram showing one example of a YZ cross section of the dust collection unit 120 at a location X1 in an X axis direction in Fig. 3.
Fig. 5 is a diagram showing examples of a time waveform of a temperature of a microwave absorbing body 144, and a time waveform of an intensity of a microwave to be introduced into the dust collection unit 120 by a microwave generation unit 130.
Fig. 6 is a diagram showing another configuration example of the dust collector 100.
Fig. 7 is a diagram showing another configuration example of the dust collector 100.
Fig. 8 is a diagram showing an arrangement example of the microwave generation unit 130 and an intensity detection unit 140.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to claims. Further, not all the combinations of features described in the embodiments are essential for means to solve the problem in the invention.
Fig. 1 is a block diagram showing one configuration example of a dust collector 100 according to an embodiment of the present invention. The dust collector 100 traps particles contained in a target gas such as an exhaust gas. In the present specification, the target gas is described as the exhaust gas. The exhaust gas may be introduced into the dust collector 100 from an exhaust gas source 200. The exhaust gas source 200 is, for example, an engine of a ship or the like. In this case, the dust collector 100 may be provided in the ship.
The exhaust gas which is introduced into the dust collector 100 contains particles such as nitrogen oxides (NOx), sulfur oxides (SOx), and particle matters (PM: Particle Matter). The particle matter (PM) is also called black carbon, and is generated due to incomplete combustion of fossil fuel. The particle matter (PM) is a fine particle whose main component is carbon.
The dust collector 100 may trap charged particles obtained by charging target particles. That is, the dust collector 100 may be an electric dust collector. The dust collector 100 causes the trapped charged particles to combust by a microwave. This makes it possible to suppress excessive deposition of trapped charged particles, and to continuously treat the exhaust gas.
The dust collector 100 of the present example includes a charging unit 110, a dust collection unit 120, a microwave generation unit 130, an intensity detection unit 140, and a control unit 150. The exhaust gas is introduced into the charging unit 110. For example, the charging unit 110 causes ions to be generated by a corona discharge in a space through which the exhaust gas passes, thereby causing the target particles to be charged. The exhaust gas containing the charged particles is sent to the dust collection unit 120.
The dust collection unit 120 traps the charged particles. The dust collection unit 120 traps the charged particles by Coulomb force, for example, by arranging a member to which a ground potential or the like is applied in a path through which the exhaust gas passes. The dust collection unit 120 exhausts the exhaust gas after trapping the charged particles.
The microwave generation unit 130 generates the microwave to be introduced into the dust collection unit 120. The microwave is, for example, an electromagnetic wave having a frequency of 300 MHz to 300 GHz.
In the present example, the dust collector 100 causes the charged particles, which are trapped in the dust collection unit 120, to combust by the microwave generated by the microwave generation unit 130. The charged particles are heated, by the microwave introduced into the dust collection unit 120 being absorbed by the charged particles. It is possible to cause the charged particles to combust by introducing the microwave to the degree that temperatures of the charged particles become ignition points or higher. In general, a heating rate Q of an object to be heated by the microwave is expressed by the following Equation. $Q = (1 / 2) σ {|E|}^{2} + (1 / 2) ωε " {|E|}^{2} + (1 / 2) ωμ " {|B|}^{2}$
The first term (1/2)σ|E|² indicates a heating rate due to Joule heating by an electric field. Here, σ indicates conductivity of fine particles contained in the object to be heated. In addition, E is an electric field by the microwave. Applying the electric field to the object to be heated causes movements of charges in the object to be heated. The movements of the charges, that is, a current causes Joule loss. The first term represents a heat generation due to the Joule loss.
The second term (1/2)ωε"|E|² indicates a heating rate due to dielectric heating by an electric field. Here, ω indicates an angular frequency of the microwave, and ε" is an imaginary part of permittivity of the object to be heated. When the electric field is applied to the object to be heated, an electric dipole contained in the object to be heated follows a change in the electric field with a time delay. The following of the electric dipole with the time delay causes a loss. The second term represents the heat generation due to the loss.
The third term (1/2) ωµ"|B|² indicates the heating rate due to the Joule heating by an eddy current. Here, µ" is an imaginary part of magnetic permeability of the object to be heated. When a magnetic field is applied to the object to be heated, the eddy current is generated in a direction of hindering a change in the magnetic field. The eddy current causes the Joule loss. The third term represents the heat generation due to the Joule loss.
The dust collection unit 120 may have an antenna for radiating the microwave to an internal trapping space. By causing the charged particles to combust by using the microwave, it is possible to remove the target particles by a simple and space saving structure in comparison with methods such as hammering, air cleaning, and water cleaning.
For microwaves introduced into the dust collection unit 120, some component is absorbed by the charged particles, and the residual component remains without being absorbed by the charged particles. When the microwave, which has an intensity excessively high in comparison with an amount of the charged particles trapped in the dust collection unit 120, is introduced, the microwave, which is not completely absorbed by the charged particles, remains. The intensity detection unit 140 detects an intensity of the microwave which is not absorbed by the charged particles, for the microwaves introduced into the dust collection unit 120. This makes it possible to determine whether the intensity of the microwave is excessive.
The microwave generation unit 130 controls the intensity of the microwave to be introduced into the dust collection unit 120, based on the intensity of the microwave detected by the intensity detection unit 140. In the present example, the control unit 150 generates a control signal for controlling the intensity of the microwave in the microwave generation unit 130. As the intensity of the microwave, which is detected by the intensity detection unit 140, is high, the control unit 150 may reduce the intensity of the microwave to be introduced, by the microwave generation unit 130, into the dust collection unit 120. When the intensity of the microwave, which is detected by the intensity detection unit 140, exceeds a predetermined threshold value, the control unit 150 may reduce the intensity of the microwave to be introduced, by the microwave generation unit 130, into the dust collection unit 120. With the dust collector 100 of the present example, the intensity of the microwave to be introduced into the dust collection unit 120 can be appropriately controlled to suppress energy consumption.
The intensity detection unit 140 of the present example has a derivation unit 142, a microwave absorbing body 144, and a temperature detection unit 146. The derivation unit 142 derives, from the dust collection unit 120, at least a part of the microwave which is not absorbed by the charged particles inside the dust collection unit 120. The derivation unit 142 may have a circulator that causes the microwave in a direction of exiting the dust collection unit 120 to pass through, and blocks the microwave traveling in a direction toward the dust collection unit 120.
The higher the intensity of the microwave remaining inside the dust collection unit 120, the higher the intensity of the microwave derived by the derivation unit 142. This makes it possible to detect the intensity of the microwave which is not absorbed by the charged particles inside the dust collection unit 120, from the intensity of the microwave derived by the derivation unit 142.
The microwave absorbing body 144 absorbs the microwave derived from the dust collection unit 120. The microwave absorbing body 144 contains a substance that generates heat by absorbing the microwave. The microwave absorbing body 144 may contain water, or may contain ceramic such as silicon carbide or aluminum oxide.
The temperature detection unit 146 detects a temperature of the microwave absorbing body 144. The temperature detection unit 146 includes, for example, a sensor such as a thermocouple provided in contact with the microwave absorbing body 144. The temperature detection unit 146 of the present example notifies the control unit 150 of information indicating the temperature of the microwave absorbing body 144. As described above, the control unit 150 controls the microwave generation unit 130 based on the information. It can be understood that the higher the temperature of the microwave absorbing body 144, the higher the intensity of the microwave which is not absorbed by the charged particles.
Fig. 2 is a schematic diagram showing one example of a dust collection unit 120. Fig. 2 schematically shows a perspective diagram of the dust collection unit 120. A shape of the dust collection unit 120 in the present example is cylindrical, but may be another shape such as a box shape.
The dust collection unit 120 of the present example has an opening 42 to which the exhaust gas is supplied, a gas flow path 44 through which the exhaust gas flows, and an opening 46 from which the exhaust gas is exhausted. The exhaust gas which is supplied to the opening 42 contains the charged particles charged by the charging unit 110. The gas flow path 44 has a partition wall 32 that surrounds a space through which gas flows. The partition wall 32 may have a tubular shape. The charged particles are removed from the exhaust gas in the gas flow path 44. The exhaust gas from which the charged particles have been removed is exhausted from the opening 46.
The dust collection unit 120 has a charged particle accumulation unit 36 that accumulates the charged particles. The charged particle accumulation unit 36 of the present example has the partition wall 32, a space 41, and an outer wall 39 in a YZ plane. The space 41 is arranged outside the partition wall 32. The outer wall 39 is arranged outside the space 41 in the YZ plane. The outer wall 39 may have a tubular shape. In addition, the partition wall 32 is provided with an opening (described below) for passing the charged particles. The partition wall 32 and the outer wall 39 may be formed of a metal material.
A potential capable of electrically attracting the charged particles is applied to the outer wall 39. The potential that is applied to the outer wall 39 may be the ground potential. The charged particles contained in the exhaust gas, which passes through the gas flow path 44, pass through the opening (described below) of the partition wall 32, and adhere to the outer wall 39 or the like of the charged particle accumulation unit 36. By introducing the microwave into the space 41, it is possible to cause the charged particles, which adhere to the outer wall 39 or the like, to combust.
The outer wall 39 of the present example has an opening 48 for introducing the microwave generated by the microwave generation unit 130 or deriving the microwave from the dust collection unit 120. In the present example, a traveling direction of the exhaust gas in the dust collection unit 120 is defined as an X axis. The two orthogonal axes in a plane perpendicular to the X axis are defined as a Y axis and a Z axis. A plurality of openings 48 may be arranged along an X axis direction. In addition, the plurality of openings 48 may be arranged along an outer periphery of the outer wall 39 in the YZ plane. The opening 48 may be provided to penetrate the outer wall 39. In the example of Fig. 2, the two openings 48 are arranged with the gas flow path 44 being interposed therebetween in a Y axis direction.
The dust collection unit 120 has reflection units 34 that reflect the microwaves at both ends of the charged particle accumulation unit 36 in the X axis direction. The reflection units 34 provided at one end and the other end in the X axis direction may be provided to surround the space 41 in the YZ plane. The microwaves introduced from the openings 48 propagate through the charged particle accumulation unit 36, are reflected by the reflection units 34, and form traveling waves or standing waves in the charged particle accumulation unit 36. Note that the traveling direction of the microwave is not limited to a direction parallel to the X axis. The microwave can form the traveling wave or the standing wave in various directions, such as a circumferential direction of the space 41 in the YZ plane.
The dust collection unit 120 has a first electrode 30 and a second electrode. The first electrode 30 may be arranged along a central axis of the dust collection unit 120. The first electrode 30 may have a rod shape having a longer length in the X axis. The first electrode 30 may be continuously provided from the opening 42 to the opening 46 along the X axis direction. The second electrode may be arranged around the first electrode 30 in the YZ plane. In the present example, the partition wall 32 functions as the second electrode. The partition wall 32 may have a tubular shape in which the first electrode 30 is accommodated. The first electrode 30 may be arranged at the center of a region which is surrounded by the partition wall 32 in the YZ plane. In the YZ plane, the gas flow path 44 may be interposed between the first electrode 30 and the partition wall 32.
In the present example, the microwave generation unit 130 introduces the microwaves into the plurality of openings 48. The microwave generation unit 130 may introduce the microwaves with the same intensity into the plurality of openings 48. In another example, the microwave generation unit 130 may be able to control the intensity of the microwave for each opening 48.
The intensity detection unit 140 detects the intensities of the microwaves derived from the plurality of openings 48. The intensity detection unit 140 may collectively detect the intensities of the microwaves derived from the plurality of openings 48. The microwave derived from each opening 48 may be introduced into a common waveguide. The intensity detection unit 140 may detect the intensity of the microwave in the common waveguide.
In the example of Fig. 2, the microwave generation unit 130 and the intensity detection unit 140 are provided in different openings 48. In another example, the microwave generation unit 130 and the intensity detection unit 140 may be provided in the common opening 48. In this case, the intensity detection unit 140 detects the intensity of the microwave traveling from the opening 48 toward the microwave generation unit 130.
Fig. 3 is a view showing one example of a configuration of a partition wall 32. In
Fig. 3, the partition wall 32 is shown by hatching. In addition, in Fig. 3, the outer wall 39 is shown by a broken line. The partition wall 32 has an opening 38 through which the charged particles pass. The opening 38 is a through hole connecting the space 41 and the gas flow path 44. A plurality of openings 38 may be provided. The openings 38 may be periodically provided in the X axis direction and the YZ plane.
In the X axis direction, locations of the openings 38 and locations of the openings 48 may be different. When the dust collection unit 120 is viewed from a +Y axis direction to a -Y axis direction, the opening 48 and the partition wall 32 may overlap, or the opening 48 and the opening 38 may not overlap. When the dust collection unit 120 is viewed from the +Y axis direction to the -Y axis direction, some of the openings 48 may overlap some of the openings 38.
Fig. 4 is a diagram showing one example of a YZ cross section of the dust collection unit 120 at a location X1 in an X axis direction in Fig. 3. The cross section is a YZ plane passing through the opening 48, the first electrode 30, the gas flow path 44, the partition wall 32, the opening 38, the space 41 and the outer wall 39.
The partition wall 32 is provided to surround the gas flow path 44. The first electrode 30 is provided at the center location of the gas flow path 44 in the cross section. The partition wall 32 is provided with the opening 38. The space 41 is provided outside the partition wall 32. The space 41 is surrounded by the outer wall 39. The outer wall 39 and the partition wall 32 may be provided concentrically around the first electrode 30. The outer wall 39 is provided with the opening 48 for introducing or deriving the microwave.
The first electrode 30 may be set to a predetermined high DC potential with respect to the ground potential. The predetermined high potential may be, for example, 10 kV or higher. The partition wall 32 (the second electrode) and the outer wall 39 may be grounded. A predetermined high DC voltage (for example, 10 kV or higher) is applied between the first electrode 30 and the partition wall 32.
When the predetermined high DC voltage is applied between the first electrode 30 and the partition wall 32 (the second electrode), the corona discharge occurs in the gas flow path 44 between the first electrode 30 and the partition wall 32. Thereby, the particles contained in the gas flowing through the gas flow path 44 are charged. The charged particles 28 are attracted to the partition wall 32 and the outer wall 39, pass through the opening 38, and move into the space 41.
The microwave generation unit 130 introduces the microwave from the opening 48. The microwave generation unit 130 and the opening 48 may be connected by a waveguide 131. The microwave introduced from the opening 48 propagates mainly in the space 41, and is absorbed by the charged particles 28. When the amount of the charged particles 28 in the space 41 is small, the microwave absorbed by the charged particles 28 is small, and thus the microwave remaining in the space 41 is large.
The derivation unit 142 derives, from the opening 48, at least a part of the microwave remaining in the space 41. The opening 48 and the derivation unit 142 may be connected by the waveguide 131. The derivation unit 142 introduces the microwave, which is derived, into the microwave absorbing body 144. The derivation unit 142 and the microwave absorbing body 144 may be connected by the waveguide 131. The derivation unit 142 may have the circulator that blocks the microwave traveling from the waveguide 131 on a microwave absorbing body 144 side toward the opening 48. The microwave absorbing body 144 absorbs the introduced microwave and generates the heat. The higher the temperature of the microwave absorbing body 144, the higher the intensity of the microwave which is not absorbed by the charged particles. Such a configuration makes it possible to detect the intensity of the excessive microwave which is not absorbed by the charged particles 28.
In the example of Fig. 4, the microwave generation unit 130 and the derivation unit 142 are connected to the two openings 48 arranged opposite to each other in the YZ plane. The arrangement of the two openings 48 to which the microwave generation unit 130 and the derivation unit 142 are connected is not limited to the example of Fig. 4. The two openings 48 to which the microwave generation unit 130 and the derivation unit 142 are connected may be arranged at different locations in the X axis direction.
In addition, as shown in Fig. 2, the derivation unit 142 and the microwave absorbing body 144 may be commonly provided with respect to the plurality of openings 48. Thereby, even when the microwaves remain unevenly in the space 41, it is possible to average and detect the intensities of the microwaves in the space 41.
Fig. 5 is a diagram showing examples of a time waveform of a temperature of a microwave absorbing body 144, and a time waveform of an intensity of a microwave to be introduced into the dust collection unit 120 by a microwave generation unit 130. In the example of Fig. 5, a time when the microwave generation unit 130 is started is set as 0.
At the start, the microwave generation unit 130 generates the microwave of a first intensity P1. When the amount of the charged particles 28 in the space 41 is comparatively small, the microwave of the first intensity P1 is not completely absorbed by the charged particles 28, and the microwave is introduced into the microwave absorbing body 144. This makes the temperature of the microwave absorbing body 144 rise.
In a state in which the microwave of the first intensity P1 is introduced into the dust collection unit 120, when the temperature of the microwave absorbing body 144 becomes higher than or equal to a first reference temperature C1 (a time t1), the microwave generation unit 130 switches the intensity (watt) of the microwave to be introduced into the dust collection unit 120 to a second intensity P2 which is lower than the first intensity P1. The second intensity P2 may be 80% or less of the first intensity P1, may be 50% or less, or may be 0%. In addition, when the temperature of the microwave absorbing body 144 becomes higher than or equal to the first reference temperature C1, the microwave generation unit 130 may reduce, in a stepwise manner, the intensity of the microwave until the temperature of the microwave absorbing body 144 begins to decrease. As one example, the first intensity P1 is in a range of 450 W to 550 W, and the second intensity P2 is in a range of 350 W to 450 W.
When the intensity of the microwave is the second intensity P2 and the microwave introduced into the space 41 is almost absorbed by the charged particles 28, the microwave introduced into the microwave absorbing body 144 is small, or almost disappears. This makes the temperature of the microwave absorbing body 144 be reduced.
In a state in which the microwave of the second intensity P2 is introduced into the dust collection unit 120, when the temperature of the microwave absorbing body 144 becomes lower than or equal to a second reference temperature C2 (a time t2), the microwave generation unit 130 switches the intensity of the microwave to be introduced into the dust collection unit 120 to the first intensity P1. When the temperature of the microwave absorbing body 144 becomes lower than or equal to the second reference temperature C2, it can be determined that the intensity of the microwave to be introduced into the space 41 is much lower in comparison with the amount of the charged particles 28 in the space 41. Therefore, by switching the intensity of the microwave to the first intensity P1, it is easy to cause the charged particles 28 in the space 41 to combust. In addition, the microwave generation unit 130 may raise, in a stepwise manner, the intensity of the microwave until the temperature of the microwave absorbing body 144 begins to increase.
By repeating such processing, it is possible to adjust the intensity of the microwave to the intensity in accordance with the amount of charged particles 28 in the space 41. Therefore, it is possible to prevent the charged particles 28 from remaining without combusting, and to save microwave energy.
Fig. 6 is a diagram showing another configuration example of the dust collector 100. The dust collector 100 of the present example includes a calculation unit 152 in addition to the configuration of the dust collector 100 described with reference to Fig. 1 to Fig. 5. Other configurations are the same as the dust collector 100 described with reference to Fig. 1 to Fig. 5.
The calculation unit 152 may calculate an amount of combustion components of the charged particles 28 deposited in the dust collection unit 120, based on an integrated time in which the microwave generation unit 130 introduces the microwave of the first intensity P1 into the dust collection unit 120. That is, the calculation unit 152 calculates an amount of the deposition of the combustion components based on a cumulative time of a period T2 shown in Fig. 5. The charged particles 28 are caused to be combust mainly in the period T2 during which the intensity of the microwave is high, and thus it is possible to estimate an amount of the combustion of the charged particles 28 by accumulating the period T2. The calculation unit 152 may calculate the amount of the deposition of the combustion components based on a cumulative time of a period T1 shown in Fig. 5. The period T1 is a period from a time when the temperature of the microwave absorbing body 144 becomes lower than or equal to the second reference temperature C2 to a time when the temperature becomes the first reference temperature C1.
The intensity detection unit 140 may calculate the intensity of the microwave remaining without being absorbed by the charged particles 28 from the temperature of the microwave absorbing body 144. The temperature of the microwave absorbing body 144 varies depending on the intensity of the microwave. The intensity detection unit 140 may acquire, in advance, a relationship between the temperature of the microwave absorbing body 144 and the intensity of the microwave, when the microwave is introduced into the space 41 in a state in which the charged particles 28 are not present in the space 41. This makes it possible to acquire, from the temperature of the microwave absorbing body 144, the relationship between the temperature and the intensity of the remaining microwave in the space 41, and to store the relationship in advance in the intensity detection unit 140. The intensity detection unit 140 acquires the temperature of the microwave absorbing body 144 when the microwave is introduced into the space 41 in a state in which the charged particles 28 are present in the space 41. The intensity detection unit 140 may derive the intensity of the remaining microwave corresponding to the temperature from the above-described relationship between the temperature and the intensity.
The calculation unit 152 may calculate the intensity of the microwave absorbed by the charged particles 28 from a difference between the intensity of the remaining microwave and the intensity of the microwave introduced into the dust collection unit 120. In addition, the calculation unit 152 may calculate the amount of the combustion components remaining in the space 41, based on a time integral value of the intensity of the microwave absorbed by the charged particles 28. The relationship between the time integral value of the intensity of the absorbed microwave and the amount of combustion components may be experimentally acquired in advance.
When the amount of combustion components remaining in the space 41 exceeds a predetermined reference value, the calculation unit 152 may notify a user to that effect. This makes it easier to grasp a time to clean the dust collection unit 120.
The calculation unit 152 may calculate the amount of the particles introduced into the dust collection unit 120, based on a slope of the rising waveform in the time waveform of the temperature detected by the temperature detection unit 146. The calculation unit 152 detects a slope of a rising waveform 147 shown in Fig. 5. A difference between the first reference temperature C1 and the second reference temperature C2 is known, and thus the calculation unit 152 may detect the period T1 shown in Fig. 5 as the slope of the rising waveform 147. The smaller the amount of the charged particles 28 introduced into the dust collection unit 120, the smaller the microwave absorbed by the charged particles 28. In addition, when the amount of the charged particles 28 is small, a heat insulating and heat retaining effect of the charged particles 28 themselves becomes small. Therefore, heat dissipation from the charged particles 28 is dominant with respect to heat input to the charged particles 28 due to the microwave absorption. As a result, the slope of the rising waveform 147 becomes small. A relationship between the slope of the rising waveform 147 and the amount of charged particles 28 can be experimentally acquired in advance.
The microwave generation unit 130 may control the first intensity P1 based on the slope of the rising waveform 147. For example, when the slope of the rising waveform 147 is small, it is estimated that the amount of charged particles 28 is small. The microwave generation unit 130 may increase the first intensity P1 as the slope of the rising waveform 147 is small. This makes it possible to adjust the first intensity P1 of the microwave according to the amount of the charged particles 28.
Fig. 7 is a diagram showing another configuration example of the dust collector 100. The dust collector 100 of the present example includes a flame detection unit 160 in addition to the configuration of the dust collector 100 described with reference to Fig. 1 to Fig. 6. Other configurations are the same as the dust collector 100 of any aspect described with reference to Fig. 1 to Fig. 6. Fig. 7 illustrates a configuration in which the flame detection unit 160 is added to the configuration shown in Fig. 1.
The flame detection unit 160 detects that a flame is generated in the space 41 of the dust collection unit 120. The charged particles 28 combusts, by absorbing the microwave, without generating a flame unlike charcoal, but may generate the flame. For example, the flame may be generated in the space 41 due to causes such as the intensity of microwave being too high, the amount of charged particles 28 being too small, or the exhaust gas containing a large amount of oil contents. For example, when a gasoline engine is driven with a low load, the exhaust gas may contain a large amount of the oil contents. The flame detection unit 160 may detect the flame by detecting a wavelength component of light, which is generated when the flame is generated. The flame detection unit 160 may detect the flame based on other parameters such as an amount of the light and the temperature in the space 41.
The microwave generation unit 130 reduces the intensity of the microwave to be introduced into the dust collection unit 120, or stops the introduction of the microwave into the dust collection unit 120, when the flame is generated in the space 41. When the flame is generated, the microwave generation unit 130 may reduce, to the second intensity P2, the intensity of the microwave to be introduced into the dust collection unit 120, may reduce the intensity to an intensity lower than the second intensity P2, or may set the intensity to be zero. This makes it possible to protect the dust collection unit 120.
The microwave generation unit 130 may control the intensity of the microwave to be introduced into the dust collection unit 120, based on an operation state of the exhaust gas source 200, when the flame is generated. For example, a cause of the generation of the flame may differ depending on the operation state of the exhaust gas source 200. For example, when the exhaust gas source 200 is in a low load state, and the exhaust gas contains a large amount of the oil contents, the flame is likely to be generated due to the oil contents. In this case, the amount of charged particles 28 introduced into the space 41 is likely to be normal. On the other hand, when the exhaust gas source 200 is in a normal load state, the intensity of microwave is likely to be too high in comparison with the amount of charged particles 28 introduced into the space 41. In a case where the flame is generated when the exhaust gas source 200 is in the normal load state, the microwave generation unit 130 may set the intensity of microwave to be lower in comparison with the case where the flame is generated when the exhaust gas source 200 is in the low load state. This makes it easier to control the intensity of microwave in accordance with the amount of charged particles 28.
The microwave generation unit 130 may restart the introduction of the microwave into the dust collection unit 120 when the flame is extinguished. When the introduction is restarted, the microwave generation unit 130 may set the intensity of the microwave to be the first intensity P1, or to be an intensity lower than the first intensity P1.
In addition, the dust collector 100 may include a plurality of dust collection units 120. In this case, the dust collector 100 may stop the introduction of the exhaust gas and the introduction of the microwave into the dust collection unit 120 in which the flame is detected. The dust collector 100 may treat the exhaust gas by the dust collection unit 120 in which no flame is detected.
Fig. 8 is a diagram showing an arrangement example of the microwave generation unit 130 and an intensity detection unit 140. The microwave generation unit 130 of the present example is provided for each opening 48 with respect to the plurality of openings 48. Thereby. the microwave generation unit 130 introduces the microwave into the dust collection unit 120 from a plurality of introduction locations of the dust collection unit 120.
In addition, the intensity detection unit 140 is provided for each opening 48 with respect to the plurality of openings 48. Thereby, the intensity detection unit 140 derives the microwave from a plurality of derivation locations of the dust collection unit 120. Each intensity detection unit 140 has the structure shown in Fig. 1. That is, the derivation unit 142, the microwave absorbing body 144, and the temperature detection unit 146 are provided for each opening 48.
Each microwave generation unit 130 controls the intensity of the microwave to be introduced into the corresponding opening 48, based on the intensity of the microwave detected by any intensity detection unit 140. Each microwave generation unit 130 may control the intensity of the microwave, based on the detection result of the intensity detection unit 140 provided at a derivation location which is a location closest to the introduction location of the microwave generation unit 130 itself. In addition, each microwave generation unit 130 may control the intensity of the microwave, based on the detection result of the intensity detection unit 140 provided at a derivation location which is the same location, in the X axis direction, as the introduction location of the microwave generation unit 130 itself.
The charged particles 28 may be unevenly distributed in the space 41. In this case, the intensity of the microwave, which is derived from the derivation location near a region where the charged particles 28 are gathered, may become comparatively weak. By making the intensity of the microwave, which is to be introduced from the introduction location near the derivation location, be comparatively high, it is easy to radiate the microwave to the region where the charged particles 28 are gathered. Therefore, it is possible to cause the charged particles 28 to efficiently combust.
In the example of Fig. 8, the microwave generation unit 130 and the intensity detection unit 140 are connected to different openings 48. In another example, the microwave generation unit 130 and the intensity detection unit 140 may be connected to the common opening 48. In this case, the introduction location and the derivation location of the microwave are the same, and thus it is easy to control the intensity of the microwave to be introduced according to the distribution of the charged particles 28.
While the embodiments of the present invention have been described, the technical scope of the invention is not limited to the above-described embodiments. It is apparent to persons skilled in the art that various alterations and improvements can be added to the above-described embodiments. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the invention.

EXPLANATION OF REFERENCES

28: charged particles, 30: first electrode, 32: partition wall, 34: reflection unit, 36: charged particle accumulation unit, 38: opening, 39: outer wall, 41: space, 42: opening, 44: gas flow path, 46: opening, 48: opening, 100: dust collector, 110: charging unit, 120: dust collection unit, 130: microwave generation unit, 131: waveguide, 140: intensity detection unit, 142: derivation unit, 144: microwave absorbing body, 146: temperature detection unit, 147: rising waveform, 150: control unit, 152: calculation unit, 160: flame detection unit, 200: exhaust gas source

Claims

A dust collector comprising:
a dust collection unit configured to trap particles;

a microwave generation unit configured to generate a microwave to be introduced into the dust collection unit, and cause the particles, which are trapped in the dust collection unit, to combust by the microwave: and

an intensity detection unit configured to detect an intensity of the microwave which is not absorbed by the particles, wherein

the microwave generation unit is configured to control the intensity of the microwave to be introduced into the dust collection unit, based on the intensity of the microwave detected by the intensity detection unit.
The dust collector according to claim 1,
wherein
the intensity detection unit includes

a derivation unit configured to derive, from the dust collection unit, at least a part of the microwave which is not absorbed by the particles,

a microwave absorbing body configured to absorb the microwave derived from the dust collection unit, and

a temperature detection unit configured to detect a temperature of the microwave absorbing body.
The dust collector according to claim 2,
wherein
the microwave generation unit is configured to switch the intensity of the microwave to be introduced into the dust collection unit, to a second intensity which is lower than a first intensity, when the temperature of the microwave absorbing body becomes higher than or equal to a first reference temperature in a state in which the microwave of the first intensity is introduced into the dust collection unit.
The dust collector according to claim 3,
wherein
the microwave generation unit is configured to switch the intensity of the microwave to be introduced into the dust collection unit, to the first intensity, when the temperature of the microwave absorbing body becomes lower than or equal to a second reference temperature in a state in which the microwave of the second intensity is introduced into the dust collection unit.
The dust collector according to claim 3,
further comprising:
a calculation unit configured to calculate an amount of combustion components of the particles deposited in the dust collection unit, based on an integrated time in which the microwave generation unit introduces the microwave of the first intensity into the dust collection unit.
The dust collector according to any one of claims 2 to 4, further comprising:
a calculation unit configured to calculate an amount of the particles introduced into the dust collection unit, based on a slope of a rising waveform in a time waveform of the temperature detected by the temperature detection unit.
The dust collector according to any one of claims 2 to 6, wherein
derivation units are provided at a plurality of derivation locations of the dust collection unit, and

the microwave absorbing body is configured to absorb the microwave obtained by combining microwaves derived by the plurality of derivation units.
The dust collector according to any one of claims 2 to 6, wherein
derivation units are provided at a plurality of derivation locations of the dust collection unit,

the microwave generation unit is configured to introduce the microwave into the dust collection unit from a plurality of introduction locations of the dust collection unit,

the microwave absorbing body is provided for each of the derivation locations, and

the microwave generation unit is configured to control, based on the temperature of the microwave absorbing body at each of the derivation locations, the intensity of the microwave to be introduced from the corresponding introduction location.
The dust collector according to any one of claims 2 to 8, wherein
the intensity detection unit is configured to store, in advance, a relationship between the temperature of the microwave absorbing body and the intensity of the microwave, when the microwave is introduced into the dust collection unit in a state in which the particles are not present in the dust collection unit, and to detect the intensity of the microwave, which is not absorbed by the particles, from the temperature of the microwave absorbing body, when the microwave is introduced into the dust collection unit in a state in which the particles are present in the dust collection unit.
The dust collector according to any one of claims 2 to 8, further comprising:
a calculation unit configured to calculate the intensity of the microwave absorbed by the particles, from a difference between the intensity of the microwave detected by the intensity detection unit and the intensity of the microwave introduced into the dust collection unit by the microwave generation unit.
The dust collector according to claim 10,
wherein
the calculation unit is configured to calculate the amount of the combustion components of the particles remaining in the dust collection unit, based on an time integral value of the intensity of the microwave absorbed by the particles.
The dust collector according to any one of claims 1 to 11, further comprising:
a flame detection unit configured to detect that a flame is generated in the dust collection unit, wherein

the microwave generation unit is configured to reduce the intensity of the microwave to be introduced into the dust collection unit, or to stop introduction of the microwave into the dust collection unit, when the flame is generated.
The dust collector according to claim 12,
wherein
an exhaust gas, which is exhausted by an exhaust gas source, is introduced into the dust collection unit, and

the microwave generation unit is configured to control the intensity of the microwave to be introduced into the dust collection unit, based on an operation state of the exhaust gas source, when the flame is generated.