Dust collection system and dust collection method

Abstract

To efficiently collect fine particles included in a gas.SOLUTION: A dust collection system includes: a flow path route through which a gas flows; a droplet supply section for supplying droplets to the flow path route; an electrostatic agglomeration unit that is arranged in the flow path route downstream from the position at which droplets are supplied, forms an electric field in the flow path of the gas, electrostatically charges the droplets and fine particles included in the gas, and causes the fine particles and the droplets to collide (agglomerate); and a dust collection section that is arranged in the flow path route downstream from the electrostatic agglomeration unit and collects the droplets and fine particles.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a dust collection system and a dust collection method.

Background Art

[0002] In a power generation plant that burns fossil fuels or a waste treatment plant that burns waste, a dust collection system that collects fine particles contained in exhaust gas is arranged as an exhaust gas treatment device. The dust collection system includes an electrostatic precipitator that forms an electric field in the passage of exhaust gas and attaches charged fine particles to an electrode for collection, a wet dust collector that injects droplets into the exhaust gas and collects fine particles with the droplets, a cyclone-type dust collector that rotates the exhaust gas and centrifugally separates fine particles, and the like. For example, Patent Documents 1 and 2 describe a system that injects droplets by spraying upstream of an electrostatic precipitator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As in Patent Documents 1 and 2, by injecting water into the exhaust gas, fine particles can be attached to the water, and the fine particles can be collected by a downstream electrostatic precipitator. However, more efficient collection is required.

[0005] The present disclosure has been made in view of such problems, and an object thereof is to provide a dust collection system and a dust collection method capable of efficiently collecting fine particles contained in a gas.

Means for Solving the Problems

[0006] A dust collection system of the present disclosure for solving the above problems includes a flow path through which a gas flows, a droplet supply unit for supplying droplets to the flow path, an electrostatic aggregation unit located downstream of the droplet supply position in the flow path, which forms an electric field in the gas flow path, charges the fine particles contained in the gas and the droplets, and causes them to collide (aggregate), and a dust collection unit located downstream of the electrostatic aggregation unit in the flow path for collecting the droplets and fine particles.

[0007] A dust collection method of the present disclosure for solving the above problems includes the steps of: supplying droplets to a flow path through which gas flows; forming an electric field in the flow path downstream of the droplet supply position to charge the fine particles contained in the gas and the droplets and cause them to collide (aggregate); and collecting the droplets and fine particles in the flow path downstream of the position where the fine particles and droplets are charged. [Effects of the Invention]

[0008] According to this disclosure, fine particles contained in gas can be efficiently collected. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of a combustion plant having a dust collection system according to this embodiment. [Figure 2] Figure 2 is a perspective view showing the schematic configuration of the dust collection system. [Figure 3] Figure 3 is a cross-sectional view showing the schematic configuration of the dust collection system shown in Figure 2. [Figure 4] Figure 4 is an explanatory diagram illustrating the processing of the dust collection system. [Figure 5] Figure 5 is an explanatory diagram illustrating the processing of the dust collection system. [Figure 6] Figure 6 is a perspective view showing a schematic configuration of a dust collection system in another embodiment. [Figure 7] Figure 7 is a cross-sectional view showing the schematic configuration of the dust collection system shown in Figure 6. [Figure 8]Figure 8 is a perspective view showing a schematic configuration of a dust collection system in another embodiment. [Figure 9] Figure 9 is a perspective view showing a schematic configuration of a dust collection system in another embodiment. [Figure 10] Figure 10 is a perspective view showing a schematic configuration of a dust collection system in another embodiment. [Modes for carrying out the invention]

[0010] The dust collection system and dust collection method according to this disclosure will be described below with reference to the drawings. Note that the description in this disclosure is one embodiment of the present invention and does not limit the invention thereto. This embodiment describes the dust collection system as being used to treat exhaust gas from a combustion device, but is not limited to this. The dust collection system can be used to collect various fine particles contained in gas. For example, it can be used as a system to collect fine particles contained in the air inside a manufacturing plant, or as a system to collect fine particles, such as dust, at work sites such as demolition sites. Furthermore, the fine particles are not limited to solids, but may also be liquids such as droplets or tar.

[0011] Figure 1 is a schematic diagram showing the general configuration of a combustion plant having a dust collection system according to this embodiment. The combustion plant 10 shown in Figure 1 includes a combustion device 12 and a dust collection system 14.

[0012] The combustion device 12 is a device that burns fossil fuels, incinerated materials, etc. The combustion device 12 discharges exhaust gas generated during combustion. The heat generated by burning the target material contained in the exhaust gas can be used for power generation or as a heat source. The combustion plant 10 may also have an exhaust heat recovery device that recovers heat from the exhaust gas and an exhaust gas treatment device that processes harmful components other than particulate matter in the exhaust gas path.

[0013] Next, the dust collection system 14 will be described with reference to FIGS. 1, 2, and 3. FIG. 2 is a perspective view showing a schematic configuration of the dust collection system. FIG. 3 is a cross-sectional view showing a schematic configuration of the dust collection system shown in FIG. 2. The dust collection system 14 collects fine particles contained in the exhaust gas discharged from the combustion device 12. The dust collection system 14 includes a flow path 20, a droplet supply unit 21, an electrostatic aggregation unit 22, an electrostatic precipitator 24, and a blower 26. The flow path 20 is a pipe that allows the exhaust gas generated by the combustion device 12 to flow in the flow direction 30. The flow path 20 is arranged in the order of the droplet supply unit 21, the electrostatic aggregation unit 22, the electrostatic precipitator 24, and the blower 26 from the upstream side in the flow direction 30.

[0014] The droplet supply unit 21 injects a liquid into the flow path 20 to form a large number of droplets. The droplet supply unit 21 includes a plurality of nozzles 40. The nozzles 40 spray the liquid and form droplets with a predetermined particle size range.

[0015] The electrostatic aggregation unit 22 is arranged downstream of the nozzles 40 of the droplet supply unit 21 in the flow path 20. The electrostatic aggregation unit 22 forms an electric field in the region through which the fine particles and droplets pass to charge the fine particles and droplets. The charged fine particles and droplets move in the electric field by diffusion and electrophoresis and collide (aggregate) with each other. When the fine particles collide with the droplets, they are incorporated into the droplets. The electrostatic aggregation unit 22 has a discharge electrode 50 and a ground electrode 52. A predetermined voltage is applied to the discharge electrode 50. The ground electrode 52 is a plate-shaped electrode arranged facing the discharge electrode 50. The ground electrode 52 is arranged in a direction such that the direction along the flow direction 30 is the surface. Thereby, the ground electrode 52 can be prevented from becoming a resistance to the flow of the exhaust gas. The ground electrode 52 is grounded. The electrostatic aggregation unit 22 forms an electric field between the discharge electrode 50 and the ground electrode 52 by applying a predetermined voltage to the discharge electrode 50. Note that the electrostatic aggregation unit 22 only needs to be able to form an electric field between the discharge electrode 50 and the ground electrode 52, and a predetermined voltage may be applied without grounding the ground electrode 52.

[0016] In this embodiment, the electrostatic agglomeration unit 22 is disposed downstream of the nozzle 40, but is not limited thereto. A part of the electrostatic agglomeration unit 22 may be disposed upstream of the nozzle 40. That is, the nozzle 40 may be disposed within the electrostatic agglomeration unit 22.

[0017] The electrostatic precipitator 24 is disposed downstream of the electrostatic agglomeration unit 22 in the flow passage 20. The electrostatic precipitator 24 forms an electric field in a region through which the fine particles and droplets pass, and collects the fine particles and droplets. The electrostatic precipitator 24 includes a discharge electrode 60 and a ground electrode (dust collecting electrode) 62. A predetermined voltage is applied to the discharge electrode 60. The ground electrode 62 is a plate-shaped electrode disposed facing the discharge electrode 60. The ground electrode 62 is disposed such that the direction along the flow direction 30 is the surface. Thereby, it is possible to suppress the ground electrode 62 from becoming a resistance to the flow of the exhaust gas. The ground electrode 62 is grounded. In the electrostatic precipitator 24 of this embodiment, the distance between the discharge electrode 60 and the ground electrode (dust collecting electrode) 62 is disposed at a shorter distance than the distance between the discharge electrode 50 and the ground electrode 52 of the electrostatic agglomeration unit 22. The electrostatic precipitator 24 forms an electric field between the discharge electrode 60 and the ground electrode 62 by applying a predetermined voltage to the discharge electrode 60. The electrostatic precipitator 24 forms an electric field to move the fine particles and droplets contained in the exhaust gas toward the ground electrode 62 and collects them by attaching them to the ground electrode 62.

[0018] Note that the electrostatic precipitator 24 only needs to be able to form an electric field between the discharge electrode 60 and the ground electrode 62, and a predetermined voltage may be applied without grounding the ground electrode 62. The electrostatic precipitator 24 may be provided with a cleaning device for removing the fine particles attached to the ground electrode 62 or a recovery device for dropping and recovering them vertically downward.

[0019] The blower 26 is disposed in the flow passage 20 downstream of the electrostatic precipitator 24. The blower 26 forms a flow from the combustion device 12 toward the electrostatic precipitator 24 and sends the exhaust gas in the flow direction 30. Note that when the exhaust gas from the combustion device 12 or the like is discharged at a predetermined flow rate during discharge, the blower 26 may not be provided. That is, the combustion device 12 may satisfy the blower function.

[0020] Next, the dust collection method of the dust collection system 14 will be explained using Figures 4 and 5, in addition to Figures 2 and 3. Figures 4 and 5 are explanatory diagrams illustrating the processing of the dust collection system, respectively. The dust collection system 14 is supplied with exhaust gas containing fine particles. The distribution of particles in the gas flowing into the dust collection system 14 is limited to the fine particle distribution 82, which corresponds to fine particles, as shown in the particle distribution 70 of Figure 4.

[0021] The exhaust gas flowing into the dust collection system 14 moves along the flow direction 30, and droplets are supplied in the area where the nozzle 40 is located. The particle distribution in the gas to which the droplets are supplied includes a particulate distribution 82 corresponding to fine particles and a droplet distribution 84 corresponding to droplets, as shown in the particle distribution 72 of Figure 4. In other words, a state in which droplets and fine particles coexist.

[0022] In the dust collection system 14, when a gas containing a mixture of droplets and fine particles passes through the electrostatic aggregation section 22, the fine particles 90 and droplets 92 pass through a first region 94 where an electric field is formed, as shown in Figure 5. The fine particles 90 and droplets 92 become charged when they pass through the first region 94 where the electrostatic aggregation section 22 is located. When the charged fine particles 90 approach the vicinity of the droplets 92, they either adhere to the droplets 92 or are absorbed into the droplets. As a result, as shown in Figure 4, the particle size distribution 74 of the gas that has passed through the electrostatic aggregation section 22 in the dust collection system 14 becomes a fine particle distribution 82a and a droplet distribution 84. Here, the fine particle distribution 82a decreases compared to the fine particle distribution 82 because the fine particles become integrated with the droplets.

[0023] In the dust collection system 14, the gas, which has a particle size distribution 74, passes through the second region 96 where the electrostatic precipitator 24 is located. The droplets 92 to which the fine particles 90 have adhered as they pass through the second region 96 are moved toward the earth electrode 62 by the electric field formed in the electrostatic precipitator 24, and adhere to the earth electrode 62.

[0024] As described above, the dust collection system 14 is equipped with a droplet supply unit 21 and an electrostatic aggregation unit 22 upstream of the electrostatic precipitator 24. The droplet supply unit 21 supplies droplets to the exhaust gas, and the electrostatic aggregation unit 22 charges the droplets and fine particles, making them more likely to collide, and allowing the droplets to capture the fine particles. By collecting the droplets that have captured the fine particles with the electrostatic precipitator 24, fine particles in the exhaust gas can be collected.

[0025] If droplets and fine particles are not charged, the flow of gas around the droplets, which occurs as they move along the exhaust gas flow, can prevent the fine particles from approaching the droplets, making it difficult for the fine particles to contact the droplets. When they reach the electrostatic precipitator 24 in this state, the droplets and fine particles are in separate states, and the electrostatic precipitator 24 collects the droplets that do not have any fine particles attached to them. In contrast, by charging the droplets and fine particles in the electrostatic aggregation unit 22, as described above, it becomes easier for the fine particles to collide with the droplets, and the droplets can be made to have fine particles attached to them before reaching the electrostatic precipitator 24. As a result, droplets with collected fine particles can be collected by the electrostatic precipitator 24.

[0026] The dust collection system 14 uses an electrostatic precipitator 24 to collect droplets to which fine particles are attached. This allows for the collection of droplets, which are more mobile than fine particles in the same electric field, and thus more efficient collection than collecting individual fine particles. Furthermore, because droplets can be collected over a shorter distance than fine particles, the electrostatic precipitator 24 can be made smaller.

[0027] Here, it is preferable that the electrostatic aggregation unit 22 forms an electric field with a lower electric field strength than the electrostatic precipitator 24. This allows the electrostatic precipitator 22 to suppress the collection of liquid droplets while bringing the fine particles and liquid droplets into contact, and the electrostatic precipitator 24 to collect the liquid droplets.

[0028] In the electrostatic aggregation section 22, it is preferable to have a greater distance between the ground electrode and the discharge electrode than in the electrostatic precipitator 24. In the electrostatic aggregation section 22, it is preferable to have a distance between the ground electrode and the discharge electrode that is 2 to 3 times greater than in the electrostatic precipitator 24.

[0029] It is preferable that the electrostatic aggregation unit 22 has a smaller potential difference between the ground electrode and the discharge electrode than the electrostatic precipitator 24. It is preferable that the electrostatic aggregation unit 22 has a potential difference between the ground electrode and the discharge electrode that is 1 / 3 or more and 1 or less than that of the electrostatic precipitator 24. By making the potential difference between the ground electrode and the discharge electrode smaller than that of the electrostatic precipitator 24, the electrostatic aggregation unit 22 can charge droplets and fine particles while suppressing the occurrence of discharge via droplets between the ground electrode and the discharge electrode.

[0030] In the electrostatic aggregation section 22, it is preferable that the electrode spacing (spacing in the gas flow direction or distance perpendicular thereto) between the discharge electrode and the ground electrode be 100 mm or more and 500 mm or less. In the electrostatic aggregation section 22, it is preferable that the potential difference between the discharge electrode and the ground electrode be 10 kV or more and 50 kV or less. By increasing the electrode spacing in the gas flow direction, sufficient collision time between fine particles and droplets can be ensured.

[0031] The droplet supply unit 21 controls the flow rate α (L / min) of the droplets to be supplied and the gas flow rate β (m³) of the flow path 30. 3 It is preferable to supply droplets to the flow channel 30 such that the relationship with ( / min) satisfies 0.1 ≤ (α / β) ≤ 1.0. This allows the droplets and fine particles to be charged while suppressing the occurrence of abnormal discharge (sparks) via the droplets between the ground electrode and the discharge electrode.

[0032] The electrostatic aggregation unit 22 and the electrostatic precipitator 24 may be arranged inside a single housing. For example, the electrostatic aggregation unit 22 and the electrostatic precipitator 24 may be arranged in a structure in which electrodes that form an electric field are placed in the flow channel 20. Alternatively, the dust collection system 14 may have a predetermined distance between the electrostatic aggregation unit 22 and the electrostatic precipitator 24. This allows the fine particles charged in the electrostatic aggregation unit 22 to enter the electrostatic precipitator 24 while attached to liquid droplets, thereby increasing the efficiency of fine particle collection.

[0033] The dust collection system 14 of this embodiment can efficiently move charged droplets and fine particles by performing dust collection with an electrostatic precipitator 24, and can efficiently collect fine particles. Here, the dust collection system 14 of this embodiment uses an electrostatic precipitator 24 to collect droplets and fine particles in order to obtain the above effect, but the dust collection unit is not limited to this. The dust collection unit of the dust collection system 14 may be a cyclone-type dust collector that rotates gas in a centrifugal direction and captures droplets by centrifugal force, a mist trap that captures droplets, or a wet-type dust collector that supplies droplets, combines them with droplets to which fine particles are attached, and drops them.

[0034] Figure 6 is a perspective view showing the schematic configuration of a dust collection system in another embodiment. Figure 7 is a cross-sectional view showing the schematic configuration of the dust collection system shown in Figure 6. The dust collection systems shown in Figures 6 and 7 are the same as the dust collection system 14, except for the structure of the electrostatic aggregation unit 22a and the electrostatic precipitator 24a.

[0035] The electrostatic aggregation unit 22a has a discharge electrode 50a and a ground electrode 52a. The discharge electrode 50a is a rod-shaped electrode. The ground electrode 52 is a rod-shaped electrode and is positioned around the discharge electrode 50a. The electrostatic precipitator 24a has a discharge electrode 60a and a ground electrode 62a. The discharge electrode 60a is a rod-shaped electrode. The ground electrode 62 is a rod-shaped electrode and is positioned around the discharge electrode 60a. When multiple discharge electrodes 60a are positioned around the ground electrode 62, it is positioned at an equidistant distance from each of the multiple discharge electrodes 60a.

[0036] Thus, the earth electrodes 52a and 62a may be in a rod shape. In this case as well, by making the electric field of the electrostatic aggregation unit 22a weaker than the electric field of the electrostatic precipitator 24a, the droplets and fine particles are charged in the electrostatic aggregation unit 22a, and the droplets and fine particles collide (aggregate), so that the droplets containing fine particles can be easily collected by the electrostatic precipitator 24a.

[0037] Figure 8 is a perspective view showing the schematic configuration of a dust collection system of another embodiment. The dust collection system shown in Figure 8 differs from the dust collection system 14 in that the droplet supply unit 21a is different. The following describes the points specific to the dust collection system shown in Figure 8. In the droplet supply unit 21a of the dust collection system shown in Figure 8, the spray direction of the nozzle 40a is on the opposite side from the flow direction 30. That is, the nozzle 40a sprays droplets toward the upstream side of the flow direction 30. As a result, the sprayed droplets move toward the upstream side of the flow direction 30, and then, due to the force of the exhaust gas flowing along the flow direction 30, their direction of travel is reversed and they move along the flow direction 30.

[0038] The dust collection system shown in Figure 8 positions the nozzle 40a's nozzle opening upstream of the flow direction 30, and by spraying droplets upstream of the flow direction 30, the distance the droplets sprayed from the nozzle 40a travel before entering the electrostatic aggregation section 22 can be increased. This allows the droplets supplied from the droplet supply section 21a to enter the electrostatic aggregation section 22 in a more dispersed state. As the dispersed droplets enter the electrostatic aggregation section 22, the droplets and fine particles can come into closer contact. Furthermore, even if the distance between the nozzle 40a and the electrostatic aggregation section 22 is shortened, the droplets can travel the distance necessary for dispersion, thus improving the performance of collecting fine particles while reducing the size of the flow direction 30 of the dust collection system.

[0039] Figure 9 is a perspective view showing the schematic configuration of a dust collection system in another embodiment. The dust collection system shown in Figure 9 differs from the dust collection system 14 in that the droplet supply unit 21b is different. The following describes the points specific to the dust collection system shown in Figure 9. The droplet supply unit 21b of the dust collection system shown in Figure 9 has a flow straightening mechanism 202 in addition to the parts of the droplet supply unit 21.

[0040] The rectifier mechanism 202 is positioned between the nozzle 40 and the electrostatic aggregation section 22. The rectifier mechanism 202 is a plate-shaped mesh, so-called plate-like arrangement, with regularly formed openings through which droplets and fine particles pass. For example, the rectifier mechanism 202 can use a mesh with an opening ratio of 0.5. Preferably, the opening ratio of the mesh in the rectifier mechanism 202 is between 0.2 and 0.6.

[0041] The droplet supply unit 21b arranges a flow straightening mechanism 202 with regularly spaced openings between the nozzle 40 and the electrostatic aggregation unit 22. This straightens the flow of droplets ejected from the nozzle 40 and fine particles contained in the exhaust gas, making it easier for the fine particles to collide with the droplets. Specifically, the flow straightening mechanism 202 restricts the area through which droplets and fine particles can pass to the openings of the straightening mechanism 202. This ensures that droplets are in close proximity to fine particles as they pass through the openings, making it easier for the fine particles to collide with the droplets. Furthermore, by spreading the droplets uniformly across the mesh surface, droplets can be dispersed over a wide area of ​​the 202 surface. As a result, droplets and fine particles can come into contact over a wider area.

[0042] The flow straightening mechanism 202 is not limited to a mesh-shaped plate, but can have various shapes that restrict the movement of droplets and fine particles ejected from the nozzle 40 and promote the adhesion of fine particles to the droplets. The flow straightening mechanism 202 may have a structure in which cylindrical flow channels are arranged in a two-dimensional view, that is, a structure in which a thick mesh is arranged. In addition, the flow straightening mechanism 202 may have multiple stages of flow straightening mechanisms.

[0043] Figure 10 is a perspective view showing the schematic configuration of a dust collection system of another embodiment. The dust collection system shown in Figure 10 differs from the dust collection system 14 in that the droplet supply unit 21c is different. The following describes the points specific to the dust collection system shown in Figure 10. In the droplet supply unit 21c of the dust collection system shown in Figure 10, the nozzles 40 are arranged in a grid pattern. The droplet supply unit 21c is, for example, 1m 2 Sixty nozzles 40 are placed per unit.

[0044] The droplet supply unit 21c, by arranging the nozzles 40 in a grid pattern, can reduce the area from which droplets are ejected by a single nozzle 40, thereby shortening the distance (distance in the flow direction 30) required for the ejected droplets to diffuse to a predetermined range. Furthermore, by ejecting droplets from multiple nozzles arranged in a grid pattern, the ejected droplets can be easily decelerated, allowing them to be reduced to a flow velocity similar to that of fine particles in a short distance. This makes it easier for fine particles and droplets to come into contact, enabling more reliable collection of fine particles by droplets.

[0045] In this embodiment, a matrix arrangement is used where the elements are arranged in rows in two dimensions, but a staggered grid arrangement may also be used. Furthermore, the droplet supply units 21c only need to be arranged in two dimensions when viewed from the flow direction 30, and the arrangement may be such that the positions in the flow direction 30 are offset.

[0046] This disclosure discloses the following inventions, but is not limited to those described below. (1) A dust collection system comprising: a flow path through which gas flows; a droplet supply unit that supplies droplets to the flow path; an electrostatic aggregation unit located downstream of the droplet supply unit in the flow path, which forms an electric field in the gas flow path, charges the fine particles contained in the gas and the droplets, and causes the fine particles and droplets to collide; and a dust collection unit located downstream of the electrostatic aggregation unit in the flow path, which collects the droplets and the fine particles. (2) The dust collection system according to (1), wherein the dust collection unit has a discharge electrode and an earth electrode, and an electric field is formed between the discharge electrode and the earth electrode, causing the droplets and fine particles to adhere to the earth electrode. (3) The dust collection system according to (2), wherein the electrostatic aggregation part forms an electric field with a lower electric field strength than the dust collection part. (4) The dust collection system according to (3), wherein the electrostatic aggregation unit is subjected to a lower voltage than the dust collection unit. (5) The dust collection system according to (3) or (4), wherein the electrostatic aggregation section has a discharge electrode and a ground electrode, and the distance between the discharge electrode and the ground electrode is greater than that between the dust collection section. (6) The dust collection system according to any one of (2) to (5), wherein the ground electrode is a plate-shaped electrode. (7) The dust collection system according to any one of (2) to (5), wherein the ground electrode is a rod-shaped electrode. (8) The droplet supply unit controls the flow rate α (L / min) of the droplets to be supplied and the gas flow rate β (m 3 A dust collection system according to any one of (1) to (7), wherein droplets satisfying the relationship with ( / min) 0.1(α / β) ≤ 1.0 are supplied to the flow channel. (9) The dust collection system according to any one of (1) to (8), wherein the droplet supply unit sprays the droplets upstream. (10) The dust collection system according to any one of (1) to (9), wherein the droplet supply unit has nozzles for spraying droplets arranged in a grid pattern on a plane perpendicular to the direction of gas flow. (11) The dust collection system according to any one of (1) to (10), wherein the droplet supply unit is provided with a mesh-shaped flow straightening mechanism downstream of the injection position for spraying the droplets. (12) A dust collection method comprising the steps of: supplying droplets to a flow path through which gas flows; forming an electric field in the flow path downstream of the droplet supply position to charge the fine particles contained in the gas and the droplets; causing the fine particles and the droplets to collide; and collecting the droplets and fine particles in the flow path downstream of the position where the fine particles and the droplets are charged. [Explanation of symbols]

[0047] 10 Combustion Plant 12 Combustion device 14 Dust collection system 20 Distribution Channels 21 Droplet supply section 22 Electrostatic aggregation part 24. Electrostatic precipitator (dust collection unit) 26 Blower 30 Distribution direction 40 nozzles 50, 60 discharge electrodes 52, 62 Grounding terminal 70, 72, 74 particle distribution 82, 82a Fine particle distribution 84 Droplet distribution 90 microparticles 92 droplets 94 First Domain 96. Second Field

Claims

1. The distribution channels through which gas is distributed, A droplet supply unit that supplies droplets to the aforementioned flow path, An electrostatic aggregation unit is located downstream of the droplet supply position in the flow path, which forms an electric field in the gas flow path, charges the fine particles contained in the gas and the droplets, and causes the fine particles and droplets to collide. It includes a dust collection unit located downstream of the electrostatic aggregation unit in the flow path, which collects the droplets and the fine particles, The dust collection unit has a discharge electrode and a ground electrode, and forms an electric field between the discharge electrode and the ground electrode, causing the droplets and fine particles to adhere to the ground electrode. The electrostatic aggregation portion has a discharge electrode and a ground electrode, The distance between the discharge electrode and the ground electrode of the electrostatic aggregation section is between two and three times the distance between the discharge electrode and the ground electrode of the dust collection section. A dust collection system in which the electrode spacing between the discharge electrode and the ground electrode of the electrostatic aggregation section is 100 mm or more and 500 mm or less.

2. The dust collection system according to claim 1, wherein the electrostatic aggregation portion forms an electric field with a lower electric field strength than the dust collection portion.

3. The dust collection system according to claim 2, wherein the electrostatic aggregation unit is subjected to a lower voltage than the dust collection unit.

4. The dust collection system according to claim 1, wherein the ground electrode is a plate-shaped electrode.

5. The dust collection system according to claim 1, wherein the ground electrode is a rod-shaped electrode.

6. The droplet supply unit controls the flow rate α (L / min) of the droplets to be supplied and the gas flow rate β (m) of the flow path. ３ The dust collection system according to claim 1, wherein droplets satisfying the relationship with ( / min) 0.1(α / β) ≤ 1.0 are supplied to the flow path.

7. The dust collection system according to claim 1, wherein the droplet supply unit sprays the droplets upstream.

8. The dust collection system according to claim 1, wherein the droplet supply unit has nozzles for ejecting the droplets arranged in a grid pattern on a plane perpendicular to the direction of gas flow.

9. The dust collection system according to any one of claims 1 to 8, wherein the droplet supply unit is provided with a mesh-shaped flow straightening mechanism downstream of the injection position for ejecting the droplets.

10. A method for collecting dust in a dust collection system according to any one of claims 1 to 8, The steps include supplying droplets to a gas flow path, The steps include forming an electric field in the flow path downstream of the liquid droplet supply position, thereby charging the fine particles contained in the gas and the liquid droplet, The steps involve colliding fine particles with liquid droplets, A dust collection method comprising the step of collecting the droplets and fine particles in a flow path downstream of the position where the fine particles and droplets are charged.

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