Electrostatic precipitator purification

Abstract

Aspects and embodiments provide a wet electrostatic precipitator with an accessory component cleaning device, the cleaning device comprising a cleaning assembly movable and supportable within the electrostatic precipitator, the cleaning assembly comprising a scraper, the scraper being configurable to abut an accessory component of the electrostatic precipitator, such that movement of the cleaning assembly within the electrostatic precipitator causes movement of the scraper relative to the accessory component, the accessory component comprising a component of a separation assembly provided within the wet electrostatic precipitator to maintain electrical insulation between the discharge electrode and the collection electrode. Also provided is a method of cleaning an accessory component of a wet electrostatic precipitator. The configuration recognizes that removing grounded or electrically neutral accessory components (i.e. components other than the discharge electrode and the collection electrode) can help maintain the overall efficient operation of some electrostatic precipitator devices. Such accessory components typically cannot be lapped, air blasted or washed due to their close proximity to high voltage components or other essential main components of the electrostatic precipitator. The configuration can provide a mechanism that allows for the use of minimum separation distances between attached and energized components by maintaining those separation distances through efficient agglomerate removal. Efficient agglomerate removal can thus allow for a reduction in the overall footprint of the electrostatic precipitator device in practical operating conditions.

Description

[Technical Field]

[0001] The field of the invention relates to wet electrostatic precipitators with auxiliary component cleaning devices and methods for cleaning wet electrostatic precipitators. [Background technology]

[0002] Electrostatic precipitators collect dust and particulate pollutants from gases, such as air or exhaust gases formed as part of an industrial process. Electrostatic precipitators use electrostatic forces to collect pollutants. For example, electrostatic precipitators can be configured to generate electrons through a corona discharge. The generated electrons ionize surrounding air or other gas molecules. The ionized gas molecules within the electrostatic precipitator combine with particulate matter carried in the air or exhaust gases. As a result, the particles become electrically charged and can be attracted by electrostatic forces to a properly grounded collection electrode.

[0003] An electrostatic precipitator device may include one or more electrically grounded collection electrodes and one or more discharge electrodes to which a high voltage is applied. When a high voltage is applied to the discharge electrode, a corona discharge occurs between the discharge electrode and the collection electrode. Both the collection electrode and the discharge electrode are typically conductive.

[0004] The efficient operation of an electrostatic precipitator device may depend on the nature of the corona discharge between the discharge electrode and the collection electrode. For example, increasing the distance between the discharge electrode and the collection electrode may lead to a decrease in efficiency, requiring a higher voltage to be applied to the discharge electrode to restore adequate efficiency. Similarly, decreasing the distance between the discharge electrode and the collection electrode may increase efficiency, but a short distance may also increase the likelihood of electrical breakdown, rendering the electrostatic precipitator inoperable.

[0005] Particulate matter buildup within an electrostatic precipitator can adversely affect the efficient operation of the electrostatic precipitator device. The buildup of particulate matter can cause short circuits and / or the formation of corona discharges in a manner that does not support efficient overall operation of the electrostatic precipitator device. Wet electrostatic precipitator devices utilize a fluid, such as water, to clean one or more major components of the precipitator device.

[0006] Aspects and embodiments can provide a mechanism for improving particulate accumulation and improving the efficient operation of wet electrostatic precipitators. Summary of the Invention [Means for solving the problem]

[0007] One aspect provides a wet electrostatic precipitator comprising a cleaning device for an accessory component, the cleaning device comprising a cleaning assembly movable and supportable within the wet electrostatic precipitator, the cleaning assembly comprising a scraper, the scraper being configurable to abut an accessory component of the wet electrostatic precipitator, such that movement of the cleaning assembly within the wet electrostatic precipitator causes movement of the scraper relative to the accessory component, and the accessory component comprising a component of a separation assembly provided within the wet electrostatic precipitator to maintain electrical insulation between a discharge electrode and a collection electrode.

[0008] Thus, in parallel with the primary particulate removal and purification mechanism provided in the primary components of the wet electrostatic precipitator, a secondary or additional removal configuration can be provided to support removal of one or more ancillary components of the wet electrostatic precipitator. Thus, by removing components other than the primary electrodes, overall particulate or agglomerate accumulation can be reduced, and efficient operation of the primary components of the electrostatic precipitator can be maintained for a longer period than would be expected without the removal of the ancillary components. In some configurations, the ancillary components removed by the purification device include components located adjacent to the primary electrostatic precipitator components. Thus, particulate or agglomerates accumulated on such components, if not removed, could come into contact with the primary components and adversely affect the operation of the primary component(s). An embodiment can be provided as an additional removal device and is not configured to remove the primary electrostatic precipitator components, such as the discharge or collection electrodes of the precipitator.

[0009] According to some embodiments, the ancillary components may include components of a separation assembly provided on the electrostatic precipitator to maintain electrical insulation between the discharge electrode and the collection electrode. Thus, reducing the buildup of particulates or agglomerates on ancillary components provided and positioned to maintain separation between the discharge electrode and the collection electrode can help prevent undesired contact from occurring between those electrodes.

[0010] According to some embodiments, movement of the cleaning assembly within the electrostatic precipitator causes movement of a scraper along the surface or edge of the attached component. The movement of the scraper along the surface or edge can help to dislodge or remove particulates or agglomerates that have accumulated on the edge or surface.

[0011] According to some embodiments, the scraper comprises a narrow, elongated element. Providing a scraper with a small surface area helps prevent particulates or agglomerates from accumulating on the scraper itself. A scraper with a small contact area with the attached component can allow for more efficient removal due to higher pressure on the scraper edge or contact area with the attached component.

[0012] According to some embodiments, the scraper comprises a wire. According to some embodiments, the scraper is electrically groundable. According to some embodiments, contact between the scraper and an attached component causes the scraper to be electrically grounded. Thus, grounding the scraper can help prevent any particulates or agglomerates from accumulating on the scraper itself.

[0013] According to some embodiments, the device can be coupled to a motor configured to move the cleaning assembly relative to the ancillary component. According to some embodiments, the device can be positioned within an electrostatic precipitator such that the cleaning assembly is carried by a flow of cleaning fluid and the body moves relative to the ancillary component. According to some embodiments, the cleaning fluid comprises a flow of water configured to clean at least one collection electrode surface within the electrostatic precipitator device. According to some embodiments, the cleaning fluid comprises a continuous or pulsed flow of gas configured to clean at least one collection electrode surface within the electrostatic precipitator device. Thus, relative movement between the scraper of the cleaning device and the ancillary component can be achieved in a variety of active or passive ways. Implementing a device that utilizes a passive drive mechanism can enable the provision of an ancillary component removal device that can be retrofitted to existing electrostatic precipitators.

[0014] According to some embodiments, the electrostatic precipitator includes a removal mechanism for a main component. The main component may include a discharge electrode or a collection electrode. The removal mechanism may include one or more of a cleaning mechanism, a lapping mechanism, or an air blast mechanism.

[0015] A further aspect provides a method for cleaning an ancillary component of a wet electrostatic precipitator, the method comprising the steps of providing a cleaning device comprising a cleaning assembly including a scraper; positioning the cleaning assembly of the cleaning device movably supported within the wet electrostatic precipitator; and configuring the scraper to abut against the ancillary component of the wet electrostatic precipitator, wherein movement of the cleaning assembly within the wet electrostatic precipitator causes movement of the scraper relative to the ancillary component, the ancillary component comprising a component of a separation assembly provided within the wet electrostatic precipitator to maintain electrical insulation between the discharge electrode and the collection electrode.

[0016] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

[0017] It should be understood that when features of an apparatus are described as being operable to provide a certain function, this includes features of an apparatus that provide that function or that are adapted or configured to provide that function. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0018] [Figure 1] An example of an electrostatic precipitator is shown below. [Figure 2] 2 is an enlarged view of a portion of the example electrostatic precipitator of FIG. 1. [Figure 3] 1 and 2. A water supply plate 120 as shown in the electrostatic precipitator of FIG. 1 is shown in perspective view. [Figure 4] 3 is a photograph showing some of the main components of a dust collector such as that shown in FIGS. 1 and 2. [Figure 5] 3 is a photograph showing some of the main components of a dust collector such as that shown in FIGS. 1 and 2. [Figure 6]1 shows a removal device according to one example embodiment suitable for use in an electrostatic precipitator such as that shown in FIGS. 1 and 2. [Figure 7] 1 shows an alternative removal device according to one example embodiment suitable for use in an electrostatic precipitator such as that shown in FIGS. 1 and 2. [Figure 8] 7 is a photograph showing some of the main components of a WESP such as that shown in FIGS. 1 and 2 in which a device such as that shown in FIG. 6 can be used. DETAILED DESCRIPTION OF THE INVENTION

[0019] Before describing the embodiments in more detail, a brief overview will be provided. The embodiments provide an arrangement that operates to support efficient operation of an electrostatic precipitator device. The arrangement seeks to provide a mechanism and method for reducing particulate buildup, and thus supports reliable generation of a corona discharge within the electrostatic precipitator.

[0020] Electrostatic precipitators typically operate to remove particulate matter from a gas by utilizing electrostatic forces, enabling the ionization of the particulate matter. A corona discharge is formed by providing at least one discharge electrode maintained at a high voltage and at least one collection electrode maintained at electrical ground. The resulting corona discharge forms ionized particles in the gas between the electrodes.

[0021] The collection electrode or "grounded plate" in an electrostatic precipitator (ESP) collects particulates as a result of the charged particles being attracted to the grounded plate.

[0022] The particulates can then be removed from the collecting electrodes and other electrically neutral or grounded areas. Dry electrostatic precipitator devices can be such that the particulates are removed by lapping the collecting electrodes (a process of physically vibrating or striking the electrode plates to remove particulate buildup) or by air blasting the collecting electrodes. In wet electrostatic precipitators (WESPs), the collecting electrodes are typically washed with a fluid such as water to prevent particulate buildup. In some applications, the configuration recognizes that particulates may form solid agglomerates on components other than the primary collecting electrode, rendering typical particulate removal techniques ineffective.

[0023] It should be understood that if particulates accumulate excessively on the collection electrode (or discharge electrode), the accumulation can lead to problems such as: a reduction in the electrode plate separation distance can lead to intermittent electrical arcing, which can result in reduced particulate removal performance; a reduction in the electrode plate separation distance can lead to a complete lack of electricity, with subsequent loss of particulate charge rendering the ESP completely inoperable; a reduction in the electrode plate separation distance can result in intermittent arcing, which requires the use of a high-performance power supply; and further, particulates accumulated on the ground surface can lead to back corona, which can result in increased current usage from the power supply.

[0024] The described arrangements recognize that in some electrostatic precipitator devices, there may be grounded or electrically neutral accessory components (i.e., components other than the discharge and collection electrodes) that cannot be lapped, air-blasted, or cleaned due to their close proximity to the high-voltage components or other essential primary components of the electrostatic precipitator. For example, lapping or cleaning associated with closely spaced components may lead to unexpected connections and electrical shorts between the closely spaced components. Furthermore, the described arrangements recognize that the specific applications selected for some electrostatic precipitator devices may result in the accumulation of particulate matter that may be problematic to remove using standard lapping, air-blasting, and / or cleaning techniques. The arrangements recognize that mechanical scraping can be used as a mechanism to clean the surfaces of one or more accessory components within the ESP. Even in the context of the auxiliary components of the precipitator, maintaining cleaner surfaces, particularly those located in close proximity to the primary functional components, can increase the length of time the ESP can maintain efficient operation before failure due to particulate buildup occurs.

[0025] Mechanical scraping of ESP components can be accomplished in a variety of ways. A scraper can comprise an element having a scraping edge or surface configured to engage the surface of the component to be removed. The scraping edge can be movable across one or more surfaces or edges of the component to be removed. Scraper movement can occur based on the selection and application of an appropriate electromechanical configuration, for example, by appropriate coupling of the scraper to a motor. Scraper movement can occur as a result of one or more components or fluids associated with the normal operation of the ESP or WESP, for example, as a result of a flow of cleaning fluid already used to clean a grounded dust collection electrode or as a result of movement achieved by an air blast configuration already operating within the ESP.

[0026] Electrostatic Precipitator 1 shows an example of an electrostatic precipitator 10. The electrostatic precipitator 10 includes a housing 20 having an inlet (not shown) for receiving an exhaust stream and an outlet (not shown) for providing a treated exhaust stream. In this example electrostatic precipitator, the housing 20 is generally cylindrical in shape. However, it should be understood that the housing 20 can be of any suitable shape and the inlet and outlet can be located in any suitable location.

[0027] 1 is a wet electrostatic precipitator (WESP) that includes a cylindrical inner ground plate forming the collection electrode 30, a cylindrical outer ground plate forming the collection electrode 40, and a discharge electrode cage 50. The discharge electrode cage 50 is maintained at a high voltage, for example, 5-50 kV, and in the illustrated example, the cylindrical inner collection electrode 30 is cleaned.

[0028] To maintain the ESP structure and maintain the separation distance between the components of the electrostatic precipitator 10, in the illustrated example, the discharge electrode cage 50 is mechanically coupled to the inner collection electrode 30. Electrical insulation between the electrode cage 50 and the grounded inner collection electrode is maintained by ensuring a mechanical coupling or connection between the two components that includes an electrical insulating element.

[0029] It should be understood that efficient operation of an electrostatic precipitator device depends on maintaining a high-voltage potential surface that is completely electrically isolated from the grounded collecting plate. In the illustrated example, the grounded, cylindrical inner collecting electrode structure 30 is continuously cleaned. An additional physical barrier in the form of a separator or guard 66 is provided between the water flow acting to clean the collecting electrode 30 and the insulating element that forms part of the mechanical coupling. The barrier itself may form part of the mechanical coupling. In the absence of such a barrier or guard, the electrically insulating element that forms part of the mechanical coupling between the discharge electrode cage 50 and the cleaned collecting electrode 30 may become wet. The wetted surface is no longer electrically insulated. The wetted surface may provide a high-voltage leakage path, resulting in failure of the ESP device.

[0030] Accessory components such as mechanical coupling means, insulating elements, and barriers are examples of components within the ESP that may trap particulate matter and adversely affect the operation of the ESP, but that cannot be removed as part of the normal operation of the ESP.

[0031] The described configuration recognizes that, despite various existing mechanisms for mitigating the chance of ESP failure, the likelihood of ESP failure can be further mitigated if a mechanism for reducing particulate matter accumulation on ESP ancillary components is provided when other removal techniques may be inadequate. Illustratively, particulate matter can accumulate on the mechanical coupling means between the discharge electrode and the collection electrode. Particulate matter may also accumulate, for example, on the separator or barrier described above. Accumulation of particulate matter on components of the mechanical coupling means, such as the separator barrier, can still cause ESP operation problems. Such ancillary components cannot be easily lapped or washed with water due to the potential impact on the electrical insulation of the ESP's primary operating components. The distance between ESP ancillary components that cannot be washed or lapped may sometimes be increased to address particulate accumulation, but this comes at the expense of increasing the footprint of the overall arrangement. The configuration described in more detail below provides an alternative mechanism for removing accumulated particulate matter from ESP components. Specifically, the configuration recognizes that the configuration can support mechanical cleaning of such components.

[0032] Mechanical cleaning can take the form of mechanically loosening, displacing, or scraping particulate matter from the surfaces and / or edges of one or more ESP components. Mechanical cleaning can be performed in a variety of ways. Generally, a mechanical cleaning device can be provided that includes at least one component positioned to contact the surface or edge of the ESP component from which particulate matter accumulation is to be removed. The component configured to contact the surface or edge of the ESP component can include a scraper. The scraper can include a scraping edge or surface configured to engage at least a portion of the surface or edge of the component to be removed. The scraping edge can be movable across one or more surfaces or edges of the component to be removed. The scraping edge can include, for example, a scraping wire. The scraping edge or element can have a small surface area so that a significant amount of particulates or agglomerates cannot adhere to it. The scraping element itself can be maintained electrically grounded.

[0033] The mechanical cleaning device may be an actively operated or passive device that is actuated as a result of one or more factors already associated with the standard operation of the ESP or WESP, for example, as a result of a flow of cleaning fluid or gas already required to clean by washing or blowing off the grounded dust collecting electrode.

[0034] Illustratively, the operation of a WESP, components of a WESP, and a mechanical cleaning device according to one example embodiment are described in detail.

[0035] FIG. 2 is an enlarged view of a portion of the wet electrostatic precipitator of FIG. 1. FIG. 2 shows a mechanical coupling 60 between the discharge electrode cage 50 and the wet inner dust collection electrode 30. The mechanical coupling 60 is housed within the housing 20. In this embodiment, the mechanical coupling 60 is coaxially positioned within the housing 20. The mechanical coupling 60 is sized to be spaced apart from the surface of the hollow housing 20 and extends along the elongation axis of the housing 20. An electrical coupling (not shown) couples to the discharge electrode cage 50. The mechanical coupling 60 is electrically insulated from the housing 20. The discharge electrode cage 50 includes a plurality of shafts 70. In this example, the shafts 70 are elongated plates extending from an annular support 80 along the elongation axis of the housing 20. The shafts 70 are positioned circumferentially around the annular support 80. A plurality of axially spaced teeth 90 extend radially from each of the shafts 70. In the illustrated example, the teeth 90 are integrally formed with the shaft 70. Specifically, the shaft 70 and teeth 90 are formed from a metal plate that is stamped or cut to form the comb-tooth structure. Advantageously, the shaft 70 can be bent or folded to provide a surface for fastening to the annular support 80.

[0036] The discharge electrode cage 50 and the inner collection electrode 30 are connected by a mechanical coupling means 60. The mechanical coupling means 60 includes an elongated shaft 62 and an insulating element 64. The insulating element mechanically couples the discharge electrode cage 50 and the inner collection electrode 30 but ensures that they are not electrically connected. In the illustrated example, the insulator comprises a series of axially spaced annular plate-like elements 65 that function as electrical insulators and electrical guards at the end regions of the substantially cylindrical, coaxially arranged wetted inner collection electrode 30 and the discharge electrode cage 50. The plate-like elements 65 also form a physical barrier between these ESP components. The mechanical coupling means 60 includes a barrier or guard 66 in the form of an open cylinder positioned between the wetted inner collection electrode 30 and the insulating element 64. The guard 66 functions as a barrier between the insulating element 64 and a fluid used to clean the wet collection electrode 30. In the configuration of FIG. 2, the guard 66 extends axially beyond the end of the collection electrode 30 to protect the insulating element 64 from splashes of the liquid used to clean the collection electrode 30.

[0037] In the configuration of Figure 2, wet cleaning of the electrode 30 is performed. An inner water reservoir (not shown in Figure 2) collects in a cavity 100 formed between the inner surface 32 of the hollow cylindrical collecting electrode 30 and the outer surface 67 of the barrier 66. A water supply 110 supplies water to the cavity 100 via a water supply plate 120, which is shown in more detail in later figures. Water from the water supply 110 fills the cavity 100 until the water level in the cavity reaches the upper lip 34, in the form of a water weir lip, of the inner collecting electrode 30. The water pours over the water weir lip 34 and onto the outer surface 36 of the collecting electrode 30.

[0038] In operation, as described above, the discharge electrode cage 50 is maintained at a high potential to induce a corona discharge. The corona discharge causes ionization of particulate matter within the ESP, which is then attracted to the outer surfaces of the grounded collection electrodes 30, 40 within the ESP. In the example shown in FIG. 2, the outer surface 36 of the inner electrode is washed with water to remove its particulate collection. Substantially continuous removal of the outer surface 36 can be achieved by allowing water within the cavity 100 to pass over the weir lip 34 and then along the outer surface 36, washing away the collected particulate matter. The presence of water on the outer surface 36 does not affect the potential difference between the discharge electrode cage 50 and the collection electrode 30.

[0039] FIG. 3 shows a perspective view of a water feed plate 120 as shown in the electrostatic precipitator of FIGS. 1 and 2. The water feed plate 120 is in the form of a substantially annular plate and can be positioned directly below the barrier 66 of the mechanical coupling means 60, as shown in FIG. 2. The water feed plate 120 includes an opening 122 that allows water to enter from the water supply 110. A plurality of baffles 124 formed on the plate 120 combine to form one or more flow passages 126 through which water enters from the water supply. Water entering the plate 120 from the water supply exits the plate tangentially through an outlet 128 and into the cavity 100. The water in the cavity 100 has a "swirling" circulating motion as a result of the tangential discharge of the water feed from the outlet 128 of the feed plate.

[0040] 4 and 5 are photographs showing some of the major components of a WESP, such as those shown in FIGS. 1 and 2, in which particulate buildup is visible. Specifically, FIG. 4 is a photograph taken along the axis of the ESP, from the electrode cage 50 to the annular support 80. The axis 70 of the electrode cage 50 can be seen extending away from the camera. A cavity 100, which receives a water container during use, can be seen, and is formed between the collection electrode 30 and the barrier 66. Generally, despite being cleaned, the photographed WESP components include an area A of accumulated particulates on the upper edge of the barrier 66. As noted above, the barrier 66 is not cleaned and cannot be air-blasted or lapped to remove particulate matter. Particulate matter buildup in area A can adversely affect the overall operation of the ESP.

[0041] Figure 5 is a similar photograph of the internal components of a WESP as shown in Figures 1-3. In this example, all components show particulate buildup, including significant particulate buildup in area A at the edge of the barrier 66 (also known as the insulator perimeter).

[0042] It has been found that particulate matter accumulation in areas such as area A shown in Figures 4 and 5 can lead to an ESP exhibiting a back corona glow during operation. The back corona glow caused by particulate accumulation significantly increases the ESP's power consumption from the power supply. To maximize the overall performance of the ESP, the electrode current is matched to the power supply. If additional current is drawn due to the formation of a back corona glow, the ESP system will use more power than strictly necessary to remove only the particulate matter in the treated fluid.

[0043] It is recognized that configurations can provide a device that can support the removal of particulate matter from one or more grounded or neutral components within an electrostatic precipitator.

[0044] FIG. 6 illustrates an example embodiment of a removal device 200 suitable for use in an electrostatic precipitator such as that shown in FIGS. 1 and 2 . The device 200 comprises a scavenging assembly including a body 210 supporting a scraper 220. In the illustrated example, the device is sized to be positioned within a cavity 100 formed between the inner collection electrode 30 and the barrier 66. Specifically, the body is sized to be adjacent to but spaced from the inner surface 32 of the collection electrode 30 and the outer surface 67 of the barrier 66. The device body 210 has a curvature selected to fit the space between the inner collection electrode 30 and the barrier 66. This size and geometry selection allows the device 200 to circulate freely within the cavity and allows the body to carry the scraper 220 on a path around the barrier 66. The device body 210 extends downward into the cavity 100 and is at least partially submerged in a container of scavenging fluid within the cavity 100. The body 210 of the device can be formed from a material that prevents the device 200 from floating in the water or other purification liquid provided to the cavity 100. Also, the material selected for the body of the device is not so dense, or heavy, that it interferes with the movement of fluid within the container that acts to carry the device 200 along.

[0045] The materials and weight of the device are carefully selected so that the device 200 does not simply float on the surface of the vessel, but is prevented from sinking into the cavity 100 by the scraper 210 resting on the upper edge of the barrier 66. The body of the device is kept upright in use by the provision of a support 230 disposed on the body so as to rest on the weir lip 34 of the inner collection electrode 30. In other words, the body of the device is suspended from the scraper 220 and the support 230, such that the body is positioned within the cavity and does not contact either the inner surface 32 of the collection electrode 30 or the outer surface 67 of the barrier 66. Because the axial length of the barrier extends axially beyond the length of the collection electrode, the scraper 220 is held in a slot provided in the scraper support 225 that protrudes from the top surface of the device body 210, while the stabilizing support 230 is held in place within the slot, which extends downward into the device body itself.

[0046] In use, the circumferential movement of cleaning liquid within cavity 100, caused by the plate described in connection with FIG. 3, acts to carry device 200 around a substantially circular path. The circumferential movement of cleaning liquid is caused by the provision of a water plate, ensuring that cleaning liquid flows evenly over water weir lip 34 to clean all portions of the inner collecting electrode. In the illustrated embodiment, this existing circumferential movement of cleaning liquid is utilized to cause movement of the cleaning assembly relative to other components of the ESP. To reduce fluid frictional resistance to device movement within the vessel, body 210 includes a shaped nose region 215. Scraper 220 rests on the edge of the barrier and functions to remove any particulate matter that has accumulated and adhered to the upper edge of barrier 66. Any removed particulate matter falls toward insulating element 64, likely affecting the operation of the discharge and collecting electrodes, or may fall into the cleaning liquid and then pass through water weir lip 34. Improved removability of the barrier can help increase maintenance intervals for electrostatic precipitators.

[0047] The scraper 220 in the illustrated example takes the form of a metal rod or wire, as does the stabilizing support 230. The wire scraper has a small surface area to prevent significant amounts of particulates or agglomerates from adhering to it as it scrapes the edge of the barrier 66. Additionally, the scraper wire 220 is maintained electrically grounded by virtue of at least direct contact with the barrier 66.

[0048] FIG. 7 illustrates an alternative removal device according to one example embodiment suitable for use in an electrostatic precipitator such as that shown in FIGS. 1 and 2. In this alternative embodiment, device 300 includes a body 310 supporting a scraper 320. In the illustrated example, the device is positioned inside barrier 66 between the barrier's inner surface and insulating element 64. Body 310 takes the form of an extension that can be coupled at one end to scraper 320 and at the other end to gear teeth 330. Teeth 330 are substantially annular and include a toothed inner surface 334 and a smooth outer surface 336. Toothed inner surface 334 is configured to mesh with cooperating teeth of drive teeth 340 that can be coupled to a rotary drive shaft 350 that extends through water plate 120 along the precipitator axis. Rotation of drive teeth 340 causes device 300 to move around barrier 66. The scraper 320 supported by the device body 310 takes the form of a wire that spans and engages the upper edge of the barrier 66, thereby providing a similar scraping and removal of agglomerates or particulate matter that may have accumulated on the upper edge of the barrier during use of the electrostatic precipitator, as described in connection with the exemplary embodiment shown in FIG. 6.

[0049] Figure 8 is a photograph showing some of the major components of a WESP such as that shown in Figures 1 and 2 with a device such as that shown in Figure 6 in operation. The removal device 200 can be seen positioned within the cavity 100 between the inner collection electrode 30 and the barrier 66. For example, particulate buildup is evident on the discharge electrode shaft 70, the annular support 80, and the insulating element plate 65, but the barrier 66 does not have any significant buildup of the type that could cause failure or inefficient operation of the electrostatic precipitator.

[0050] It should be understood that the described configuration is such that the ESP is provided in the form of a WESP. The use of a WESP supports short electrode spacing because water or other fluids can be used to remove at least one major operating component of the WESP. The typical corona operating current of a WESP is low. This is set at a level sufficient to provide a charging mechanism for the particles as well as an electric field to move the particles.

[0051] For example, aspects recognize that providing a cleaning device in the form of a scraper facilitates the removal of particulate matter that may otherwise accumulate in the portion of the WESP between the water wash weir and the insulator surface. It has been observed that if such particulate buildup is not removed, back corona or arcing may occur at the operating voltage of the WESP. Aspects recognize that some components, including ancillary components of a WESP, cannot be lapped to remove or dislodge particulate matter buildup. This is particularly true for WESPs where particulates may be wet and, as a result, cannot be easily removed or dislodged in this manner. Providing a moving cleaning section that can move continuously or periodically within the WESP can help prevent particulate buildup. While it might seem intuitive that providing additional devices or components within the operating zone of a WESP might cause further debris accumulation, it has been found that providing a moving body with a thin, wire-like mechanical scraper can remove any particulate buildup and further prevent particulate matter from accumulating on itself or on the scraped ancillary components. In other words, the described purification devices can help to mitigate, to some extent, the occurrence of buildup that can result in undesirable electrical pathways within the WESP.

[0052] The described configuration eliminates the interface between the insulator and the water purification section of the WESP. In other words, the accessory components to be removed may be composed of components that are not themselves insulators, and may be grounded but not cleaned. Aspects provide a mechanism for removing buildup that may occur on accessory portions of the WESP that cannot be cleaned or wrapped.

[0053] It should be understood that in some described implementations, the purification device operates with the tangential water flow that already forms part of the WESP's primary operation, and any debris removed by the purification device can be washed away by the tangential water flow that already forms part of the WESP's primary operation. Therefore, an additional collection hopper for the removed or purified particulate matter is not required. Furthermore, appropriate components in the purification device can support the escape of water over the weir of the WESP. In the illustrated configuration, the stabilizing supports 230 operate to level the purification device, thereby reducing resistance to its movement and helping it move smoothly around the perimeter of the WESP, but also function to provide a path that helps water escape evenly over the weir.

[0054] Although exemplary embodiments of the present invention have been disclosed in detail herein with reference to the accompanying drawings, it is understood that the present invention is not limited to the precise embodiments, and that various changes and modifications can be made by those skilled in the art without departing from the scope of the present invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0055] 10. Electrostatic precipitator 20. Housing 30 Inner dust collection electrode 32 Inner surface of inner dust collecting electrode 34 Water Weir Lip 36 Outer surface of inner dust collecting electrode 40 Outer dust collection electrode 50 Discharge electrode cage 60 Mechanical coupling means 62 Connection axis 64 Insulating Elements 65 Annular plate of insulating element 66 Guard or Barrier 67 Outer surface of guard or barrier 70 Discharge electrode axis 80 Annular shaft support 90 axial teeth 100 cavities 110 Water supply section 120 Water supply plate 124 Water supply plate baffle 126 Water plate channel 128 Water plate outlet 200 Removal Device 210 Removal device body 215 Molded Nose 220 Scraper 225 Scraper support 230 Stabilizing support 300 Removal Device 310 Removal device body 320 Scraper 330 Gears 334 toothed inner ring 336 smooth outer ring of teeth 340 driving teeth 350 drive shaft

Claims

1. A wet electrostatic precipitator comprising an accessory component, a cleaning device, the cleaning device comprising: a cleaning assembly movable and supportable within the wet electrostatic precipitator, the cleaning assembly comprising a scraper; Equipped with the scraper may be configured to abut an ancillary component of the wet electrostatic precipitator, such that movement of the cleaning assembly within the wet electrostatic precipitator causes movement of the scraper relative to the ancillary component; the ancillary components include components of a separation assembly provided within the wet electrostatic precipitator to maintain electrical insulation between a discharge electrode and a collection electrode; the purification device is disposed within the wet electrostatic precipitator, and the purification assembly is carried by a flow of purification fluid such that the purification assembly moves relative to the ancillary components; 10. A wet electrostatic precipitator, wherein the cleaning fluid comprises a flow of water configured to clean at least one collection electrode surface of the wet electrostatic precipitator.

2. 10. The wet electrostatic precipitator of claim 1, wherein movement of the cleaning assembly within the wet electrostatic precipitator causes movement of the scraper along a surface or edge of the attachment component.

3. 3. The wet electrostatic precipitator of claim 1 or 2, wherein the scraper comprises a narrow, elongated element.

4. The wet electrostatic precipitator of claim 1 or 2, wherein the scraper includes a wire.

5. 3. The wet electrostatic precipitator according to claim 1, wherein the scraper is electrically groundable.

6. 6. The wet electrostatic precipitator of claim 5, wherein contact between the scraper and an accessory component causes the scraper to be electrically grounded.

7. 3. The wet electrostatic precipitator of claim 1 or 2, wherein the cleaning device is coupled to a motor configured to move the cleaning assembly relative to the ancillary component.

8. 10. The wet electrostatic precipitator of claim 1, wherein the cleaning fluid comprises a continuous or pulsed flow of gas configured to clean at least one collecting electrode surface within the wet electrostatic precipitator.

9. 1. A method for cleaning ancillary components of a wet electrostatic precipitator, comprising: providing a cleaning device comprising a cleaning assembly including a scraper; placing the purification assembly of the purification device movably supported within the wet electrostatic precipitator; configuring the scraper to abut an attached component of the wet electrostatic precipitator; Including, movement of the cleaning assembly within the wet electrostatic precipitator causes movement of the scraper relative to the attachment component; the ancillary components include components of a separation assembly provided within the wet electrostatic precipitator to maintain electrical insulation between a discharge electrode and a collection electrode; the purification device is disposed within the wet electrostatic precipitator, and the purification assembly is carried by a flow of purification fluid such that the purification assembly moves relative to the ancillary components; The method, wherein the cleaning fluid comprises a flow of water configured to clean at least one collection electrode surface of the wet electrostatic precipitator.

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