SYSTEMS, DEVICES, AND METHODS FOR COLLECTING SPECIES FROM A GAS STREAM
20210370318 · 2021-12-02
Inventors
- Maher Damak (Cambridge, MA, US)
- Karim Khalil (Boston, MA, US)
- Carl Frederik Brasz (Cambridge, MA, US)
- Kripa Varanasi (Lexington, MA, US)
Cpc classification
B03C3/12
PERFORMING OPERATIONS; TRANSPORTING
B03C2201/04
PERFORMING OPERATIONS; TRANSPORTING
B03C3/47
PERFORMING OPERATIONS; TRANSPORTING
B03C3/08
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
An example of a species collection system includes a plurality of spaced-apart electrically conductive collectors and a plurality of emitter electrodes. In some embodiments, at least one emitter electrode is disposed between adjacent ones of the collectors. In some embodiments, the at least one emitter electrode extends beyond the collectors (e.g., in at least one dimension). Collectors may be aligned to a direction of gas flow from an outlet (e.g., of a cooling tower) to facilitate collection while minimizing interference with the gas flow. Different emitter electrodes may be maintained at different voltages. In some embodiments, collectors are attached to a collector frame and emitter electrodes are attached to emitter frame(s) that are electrically insulated from the collector frame. Collectors may span a gas outlet (e.g., of a cooling tower) and emitter frame(s) may be positioned outside of the collectors (e.g., and outside of a periphery of the gas outlet).
Claims
1. A system for collecting a species from a gas stream, the system comprising: a plurality of electrically conductive collectors that are spaced apart; and a plurality of emitter electrodes, wherein at least one of the plurality of emitter electrodes is disposed between two of the plurality of electrically conductive collectors.
2. The system of claim 1, wherein, for each pair of adjacent collectors in the plurality of electrically conductive collectors, at least one of the plurality of emitter electrodes is disposed between the adjacent collectors.
3. The system of claim 2, wherein the at least one of the plurality of emitter electrodes comprises two emitter electrodes.
4. The system of claim 3, wherein the two emitter electrodes are spaced apart in a direction perpendicular to a direction in which the plurality of electrically conductive collectors are spaced apart.
5. The system of claim 4, wherein one of the two emitter electrodes is maintained at a first voltage and the other of the two emitter electrodes is maintained at a second voltage, wherein the first voltage is higher than the second voltage.
6. The system of claim 5, wherein the one of the two emitter electrodes is closer to a gas outlet than the other of the two emitter electrodes.
7. The system of claim 5, wherein the first voltage is sufficient to generate ions in a gas stream and the second voltage is insufficient to generate ions in the gas stream.
8. The system of claim 3, wherein, the at least one of the plurality of emitter electrodes is disposed between a pair of adjacent collectors in the plurality of electrically conductive collectors and an emitter separation between adjacent ones of the at least one of the plurality of emitter electrodes is from a fourth to five times a collector separation between the adjacent collectors.
9. The system of claim 3, wherein the two emitter electrodes are two non-identical emitter electrodes.
10. The system of claim 9, wherein the two non-identical emitter electrodes comprises a first wire and a second wire having a smaller radius of curvature than the first wire.
11-51. (canceled)
52. The system of claim 1, wherein the system is disposed on, in, or over a gas outlet.
53-57. (canceled)
58. The system of claim 52, wherein for at least one pair of adjacent collectors in the plurality of electrically conductive collectors, a first emitter electrode and a second emitter electrode of the plurality of emitter electrodes are disposed between the adjacent collectors, wherein the first emitter electrode is disposed further from the gas outlet than the second emitter electrode.
59. The system of claim 58, wherein the first emitter electrode is a wire and the second emitter electrode is a wire of smaller diameter.
60-76. (canceled)
77. A method for collecting a species from a gas stream, the method comprising: flowing a gas stream comprising a species dispersed within in a direction; charging the species; and collecting the charged species on surfaces of electrically conductive collectors using an electric field, wherein the electrically conductive collectors are aligned with the direction.
78-84. (canceled)
85. The method of 77, comprising: applying a first voltage to a first emitter electrode disposed relatively closer to a gas outlet that the gas stream flows from; and applying a second voltage to a second emitter electrode disposed relatively further from the gas outlet, wherein charging the species and collecting the charged species occur, at least in part, due to applying the first voltage and the second voltage.
86. The method of claim 85, wherein the first voltage is sufficient to cause the first emitter electrode to generate ions and charge the species and the second voltage is sufficient to deflect the species towards a collector but not generate any ions.
87. The method of claim 77, comprising directing ambient air toward a gas outlet thereby forming a plume with water in air near the gas outlet, wherein the species is dispersed within the plume.
88-91. (canceled)
92. The method of claim 86, wherein the first voltage wherein the first voltage is sufficient to cause the first emitter electrode to generate ions in the gas stream via corona discharge.
93. The method of claim 85, wherein the second emitter electrode generates less current than the first emitter electrode generates.
94. The method of claim 85, wherein the first emitter electrode and the second emitter electrode are disposed between adjacent ones of the collectors.
95. The system of claim 1, wherein the plurality of emitter electrodes comprises wires and ones of the wires having a smaller diameter are disposed closer to a gas outlet than ones of the wires having a larger diameter.
96. The system of claim 52, wherein the system is disposed after and over a cooling tower outlet.
97. The system of claim 96, wherein the plurality of electrically conductive collectors and the plurality of emitter electrodes are aligned in a direction of gas flow emanating from the cooling tower outlet.
98. The system of claim 58, wherein the first emitter electrode is maintained at a non-zero voltage and the second emitter electrode is maintained at a non-zero voltage such that less current is generated by the first emitter electrode than by the second emitter electrode.
99. The system of claim 58, wherein the first emitter electrode is maintained at a non-zero voltage such that no ions are generated by the first emitter electrode via corona discharge and the second emitter electrode is maintained at a non-zero voltage such that ions are generated by the second emitter electrode via corona discharge.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Drawings are presented herein for illustration purposes, not for limitation. Figures are not necessarily drawn to scale. The foregoing and other objects, aspects, features, and advantages of the disclosure will become more apparent and may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:
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DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
[0047] It is contemplated that systems, devices, methods, and processes of the disclosure encompass variations and adaptations developed using information from the embodiments described herein. Adaptation and/or modification of the systems, devices, methods, and processes described herein may be performed by those of ordinary skill in the relevant art.
[0048] Throughout the description, where articles, devices, and systems are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are articles, devices, and systems according to certain embodiments of the present disclosure that consist essentially of, or consist of, the recited components, and that there are processes and methods according to certain embodiments of the present disclosure that consist essentially of, or consist of, the recited processing steps.
[0049] In this application, unless otherwise clear from context or otherwise explicitly stated, (i) the term “a” may be understood to mean “at least one”; (ii) the term “or” may be understood to mean “and/or”; (iii) the terms “comprising” and “including” may be understood to encompass itemized components or steps whether presented by themselves or together with one or more additional components or steps; (iv) the terms “about” and “approximately” may be understood to permit standard variation as would be understood by those of ordinary skill in the relevant art; and (v) where ranges are provided, endpoints are included. In certain embodiments, the term “approximately” or “about” refers to a range of values that fall within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater than or less than) of the stated reference value unless otherwise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value).
[0050] It should be understood that the order of steps or order for performing certain action is immaterial so long as operability is not lost. Moreover, two or more steps or actions may be conducted simultaneously.
[0051] A system disclosed herein may include, inter alfa, a plurality of electrically conductive collectors and a plurality of emitter electrodes. The electrically conductive collectors may be spaced apart in at least a first dimension (e.g., horizontally spaced relative to a gas outlet). In some embodiments, at least one emitter electrode is disposed between two of the collectors (e.g., between adjacent ones of a plurality of collectors). In some embodiments, the at least one emitter electrode extends beyond the collectors (e.g., in at least one dimension). Emitter electrodes may be wires, needles, or other high curvature electrically conductive members. For any two (e.g., adjacent) collectors, more than one emitter electrode may be disposed therebetween. Collectors may be aligned to a direction of gas flow from an outlet (e.g., of a cooling tower) to facilitate collection while minimizing interference with the gas flow. Two emitter electrodes may be spaced apart in a direction perpendicular to a direction in which the plurality of electrically conductive collectors are spaced apart. Different emitter electrodes may be maintained at different voltages and/or have different curvatures. In some embodiments, collectors are attached to a collector frame and emitter electrodes are attached to emitter frame(s), where the emitter frame(s) are electrically insulated from the collector frame. Collectors may have a size that spans a gas outlet (e.g., of a cooling tower) and emitter frame(s) may be positioned outside of the collectors (e.g., outside of a periphery of the gas outlet).
[0052] Collectors are electrically conductive members. Collectors may be aligned with a direction of gas flow from a gas outlet (e.g., of a cooling tower). For example, collectors may be parallel (e.g., within 10 degrees) to a direction of gas flow. Examples of collectors are planar meshes, planar plates, cylindrical meshes, cylindrical plates, an array of wires, corrugated plates. Collectors may comprise metal. Materials that can be used include, but are not limited to, stainless steel, galvanized steel, mild steel, aluminum, copper, titanium and Inconel.
[0053] In some embodiments, species (e.g., droplets and/or particles) get charged as they travel between collectors (e.g., due to emitter electrode(s) disposed between the collectors) and are collected on the collectors. In some embodiments, collector(s) drain, at least in part due to gravity, into a gutter. Fluid collected into a gutter may be transported to elsewhere, for example through collection conduit attached to the gutter. In some embodiments, collectors have a width that spans the width of a gas outlet. Distance between collectors can be varied and is generally from one inch to three feet (e.g., from 2 inches to 2 feet). A height of collectors may be selected depending on multiple factors such as distance between them, size of droplets and/or particles and the speed of the air that is carrying them. A typical range for the height H in inches is [h.sub.0—20 h.sub.0] where
Spacing between adjacent ones of the plurality of electrically conductive collectors varies no more than 10% (e.g., no more than 5%, no more than 3%, or no more than 1%). Collectors may be attached to a frame (e.g., that emitter electrode(s) are also attached to) (e.g., a collector frame). In some embodiments, each of a plurality of electrically conductive collectors has a length to width aspect ratio of greater than one and the longer of the length and the width is aligned with a direction of gas flow from a gas outlet. In some embodiments, collectors may not be parallel. In some embodiments, collectors may not be planar but have other shapes including, but not limited to, cylinders, spirals and cones.
[0054] Emitter electrodes are electrically conductive members. An emitter electrode may comprise metal. One or more emitter electrodes may be placed between collectors. One or more emitter electrodes may extend beyond collectors in at least one dimension. In the space between each two adjacent collectors there can be zero, one, or multiple emitter electrodes. Emitter electrodes can be or comprise round wires (e.g., having a diameter from 50 μm to 10 mm (e.g., 50 μm to 2 mm or 50 μm to 250 μm or 100 μm to 200 μm), square wires (e.g., having a side length from 50 μm to 10 mm (e.g., 50 μm to 2 mm or 50 μm to 250 μm or 100 μm to 200 μm)), rods with sharp edges, an array of needles, or other shapes that have locations of high curvature. In some embodiments, an emitter electrode comprises one or more of titanium, tungsten, copper,
[0055] Inconel, and steel (e.g., stainless steel). Emitter electrodes may be placed in the middle of two electrodes (e.g., electrically conductive collectors). If there is more than one emitter electrode between adjacent collectors, the distance between them is typically between a fourth and five times the distance between the collectors, for example a vertical separation of emitter electrodes as compared to a horizontal separation between collectors. Emitter electrodes may include wires that run horizontally or vertically (relative to a direction of gas flow) but horizontally is more common. In some embodiments, emitter electrodes are connected to a power supply to be maintained at a certain voltage. In some embodiments, non-identical emitter electrodes are used. For example, a species collection system may include horizontal wires with a small radius at the bottom (e.g., nearer a gas outlet), followed by larger diameter wires on top (e.g., further from a gas outlet). Wire emitters can also be followed (e.g., in a direction of gas flow) by a plate or a low curvature electrode. The plate may function not to emit ions but just to maintain a strong electric field to enhance the attraction of species (e.g., droplets and/or particles) in the top region of collectors.
[0056]
[0057] In some embodiments, a shielding (e.g., shroud and/or casing) at least partially encloses a plurality of collectors (e.g., around a periphery of a gas outlet). A shielding may comprise one or more panels. A shielding may be open along a direction of gas flow from a gas outlet and, optionally, be otherwise enclosed. An example of species collection system 100 that includes shielding 160 is shown in
[0058] A shielding may shield a system from any negative effects of wind. Accordingly, a shielding could be made of a either metallic or plastic/composite material. The material may be either completely opaque, or is a partially transparent material. A shielding may have a lower percentage of open area than a collector mesh so that it catches the majority of the wind that is hitting it. A shielding could be attached to collectors in several ways. In some embodiments, collectors share a common structural support (for example two circular structural member that they are all tensioned against that holds them all from the top and bottom). A shielding could be attached to these structural rings holding the collectors in place. A shielding may catch and/or redirect wind in such a way that the wind is less of a dominant effect on a plume that is escaping a cooling tower. The plume would thus be able to rise vertically through a species collection system more easily without being caught by the wind, which would displace the plume horizontally as it rises through the system.
[0059] A shielding may also potentially provide overall rigidity to the system. A system of tensioned electrically conductive mesh collectors may benefit from additional rigidity so the entire system is capable of being picked up via crane and doesn't buckle when picked from its top portion. In some embodiments, a shielding would only encase emitter electrodes and collectors. In some embodiments, a shielding could also extend below collectors and emitter electrodes so that it partially overlaps with a shroud of a gas outlet (e.g., of a cooling tower) so that wind effects are even less pronounced between any gap between a system and the gas outlet.
[0060] In some embodiments, for example as shown in
[0061] In some embodiments, a system comprises one or more wind breaks that are disposed above a gas outlet and below and/or along the plurality of emitter electrodes and the plurality of collectors. In some embodiments, the one or more wind breaks includes one or more louvers (e.g., that are angled relative to ground level, for example as shown in
[0062] Collectors (and/or emitter electrodes) may be positioned in a plume emanating from a gas outlet (e.g., of a cooling tower). Often water plumes are in a transient state. They start as saturated air at the outlet (e.g., of the cooling tower), condense as supersaturated conditions are reached, and then evaporate again when more air gets mixed in. Thereby, there may be only a small spatial window (relative to a size of the cooling tower) where water droplets are in the air and collection desirably happens there. Collectors may be placed coincident (e.g., in) a surface of maximum water content in order to maximize collection.
[0063] In some embodiments, the system may be held at a certain height where there is a gap between the cooling tower outlet and the bottom of the collection system. That height can be adjusted as a function of parameters such as water and air flow rates, external winds if any, temperature and humidity of the air coming out of the exhaust and of the ambient air. In some embodiments, the height is between zero and five (e.g., zero and three) gas outlet diameters.
[0064] In some embodiments, one or more collection panels are disposed to maximize fluid collection. For example, a plume from a cooling tower being abated is in transient state. The plume starts as saturated air at the outlet of the cooling tower, condenses as supersaturated conditions are reached, and then evaporates again when more air gets mixed in. Thus, in some embodiments, there may be only a relatively small spatial window where water droplets are in the air and collection may preferably occur there. Models have been developed to predict the surface of maximum fluid content so that collection panel(s) can be placed at the location where it can collect the most. A location (or range of locations) of a surface of maximum water content can also be determined empirically from measurements (e.g., humidity measurements) at various times (e.g., under various ambient conditions). A surface of maximum fluid content can be a planar surface or a non-planar surface (e.g., three-dimensionally rounded surface). The physical location and shape of a surface may depend on, for example, the geometry of an air outlet or duct, the amount of fluid dispersed in the gas stream, and ambient conditions such as temperature and pressure. The physical location or shape of a surface may change based on a change in wind velocity (e.g., direction and/or speed). Arranging collection panel(s) relatively far away from a surface of maximum fluid content may reduce fluid collection. Thus, in some embodiments, a the frame is disposed near a gas outlet such that one or more collection panels are disposed within 8 m (e.g., within 5 m or within 3 m) of a surface of maximum fluid content of gas exiting the gas outlet. In some embodiments, fluid collection is mostly or totally agnostic to the particular location of collection panel(s), for example where the fluid distribution throughout a gas stream is relatively uniform, such as in the middle of a duct.
[0065] In some embodiments, collection panel(s) are mounted on a motion stage so their location can be adapted, for example due to changes in a location of surface of maximum fluid content (e.g., in the case of strong winds or other ambient conditions). Referring back to
[0066] In some embodiments, a species collection system includes one or more additional components. For example, species collection system 100 includes additional components 130a-b, shown in
[0067] A cooling mechanism may supply cooling, for example, through heat exchangers (e.g., external heat exchangers). In an example of a species collection system for a cooling tower, a cooling mechanism may be used when the ambient weather conditions are such as an additional cooling of the exiting air results in more fog production and thereby more water recovery during operation. Cooling can also be done directly on one or more collection electrodes of a collection panel, making the electrode(s) serve as both a collection site for already formed droplets and a condensation site for flowing vapor.
[0068] A humidifying mechanism may be used to promote fog production in order to improve fluid collection. In an example of a species collection system for a cooling tower, waste vapor from a plant cooled by the cooling tower (e.g., a power plant) can be used to humidify the tower outlet in order to encourage further fog production in order to increase fluid collection.
[0069] In some embodiments, a species collection system includes a particle injector. By injecting small particles that can act as condensation nuclei, a condensation rate is increased (e.g., by lowering the supersaturation needed for condensation is lowered). Using a particle injector may result in more fog formation. A particle injector may inject charged particles. A particle injector may inject particles of different sizes. For example, particles injected into a gas stream by a particle injector may have a multimodal size distribution. Particles injected by a particle injector may be pre-cooled (relative to an ambient temperature of a gas stream) before injection. Depending on the application and working conditions, these particles may or may not be filtered out after the fluid is collected at one or more collection panels, for example using an intermediate filter.
[0070] Collectors and emitter electrodes may be attached to (e.g., and electrically insulated from) each other in the form of collection panels. Multiple collection panels may be arranged in a spaced apart stack (e.g., aligned with a direction of gas flow from a gas outlet). Referring now to
[0071] One or more emitter electrodes may include one or more wires. Wires used as emitter electrodes may be metallic. For example, a wire may include one or more of stainless steel, copper, aluminum, silver, gold, titanium, and tungsten. In some embodiments, a wire has a diameter from 50 μm to 10 mm. For example, a wire may have a diameter from 50 μm to 250 um or from 100 μm to 200 μm. In some embodiments, a wire comprises 304 stainless steel. For example, a wire may be made from spring back (hardened) 304 stainless steel. In some embodiments, a wire has a tensile strength of at least 1GPa. Without wishing to be bound by any articular theory, a wire with higher tensile strength may partially or completely mitigate wire-snapping failures from any source of wire deflection or wire vibration during operation of a panel. One or more emitter electrodes may be attached to an emitter electrode frame (for example as shown in
[0072] One or more collection electrodes may include an electrically conductive collector. A collector may be, for example, an electrically conductive mesh or porous surface. A collector may comprise metal, such as stainless steel for example. A mesh may be made of large gauge metal wires for example. As another example, a collector may be a porous metal plate. A collector may be planar. One or more collection electrodes may be disposed in a planar arrangement. In some embodiments, a collector has a low contact angle hysteresis (e.g., of no more than 40 degrees difference between a receding contact angle and an advancing contact angle, e.g., when a panel is disposed at an angle of from 30 degrees to 60 degrees relative to level ground). Low contact angle hysteresis may help in shedding water during species collection.
[0073] Referring again to
[0074] An additional example of wire emitter electrodes disposed on an emitter electrode frame is shown in
[0075] In some embodiments, it is preferable to use wires as emitter electrodes and, particularly in some embodiments, wires that are kept at a constant tension. Deformations of wires may thus be low under regular loads (e.g., ambient wind or vibration from a cooling tower). Moreover, risk of breaking may be low due to elasticity of the wire. In some applications, upon impact with a rain droplet or other object, a wire can deform and come back to its original tension (e.g., in part due to constant force springs, if present). By using capstans (e.g., small plastic cylinders, for example with a low friction coefficient), a wire can wind (partially) around them, thereby achieving a desirable spacing, and only have a minor effect on tension. A preferred number of capstans per wire can be determined so that the tension in all parts of the wire is within an acceptable range.
[0076] Additional collection panels and components thereof, including emitter electrodes and collectors (e.g., collection electrodes), that may be used in systems and methods disclosed herein are described in U.S. Provisional Patent Application No. 62/881,814, filed on Aug. 1, 2019, and U.S. Provisional Patent Application No. 62/881,691, filed Aug. 1, 2019, the disclosures of each of which are hereby incorporated by reference herein in their entirety. Methods of using emitter electrodes and electrically conductive collectors to collect species from a gas stream that are applicable to systems and methods disclosed herein are described in U.S. patent application Ser. No. 15/763,229, filed on Mar. 26, 2018, the content of which is hereby incorporated by reference in its entirety.
[0077] For optimal performance of a species collection system, the distance between emitters and collectors should be kept as substantially constant (e.g., varying no more than 5%). Spacing can be well maintained in part by maintaining collectors as straight as possible. In some embodiments, a collector mesh is affixed to a more rigid metal edging or frame on the sides and is kept under tension. For example, one or more springs can apply tension to a metal edging attached to a collector. A tensioning system may apply tension force to a rigid edging in order to achieve a more uniform transfer of force to the collector. Tensioning can be done using springs or turnbuckles, for example. Pre-tensioning a mesh collector can reduce potential deflections of the mesh due to wind or vibrations while maintaining emitter to collector separation.
[0078] In some embodiments, rigidifying members (e.g., rods) are added along the length of a collector to increase rigidity of the collector. In some embodiments, one or more tensioning cables (e.g., metal cables) are run through a collector (e.g., through openings of a mesh collector). Tensioning cable(s) may be attached to a rigid frame or edging such that they tension a mesh collector thereby straightening it. Additionally an edging/frame for a collector may be specifically designed to house tensioning cable(s) so that the weaving it through the edge/frame could be done easily (e.g., by running the tensioning cable(s) over one or more capstans). The edge/frame would be fixed to the mesh collector uniformly so that when the cable is pulled in tension it applies the tension force to the entirety of the mesh as a well distributed force.
[0079] In some embodiments, emitter electrodes are maintained at a high voltage (e.g., between 1 kV and 500 kV) and are therefore preferably electrically insulated from collectors. Electrically conductive collectors may be grounded. For a species collection system that includes one or more emitter electrodes operable to be maintained at high voltage and one or more collectors that are grounded, the one or more emitters can be attached directly to the one or more collectors via high-voltage insulators (e.g., as in collection panel 200 in
[0080]
[0081] Emitter electrodes may be attached to an emitter frame and collectors may be attached to a collector frame. An emitter frame and/or collector frame may be metallic. Thus, a subset (e.g., all) of the emitter electrodes in a system may be commonly electrically connected. A subset (e.g., all) of the collectors in a system may be commonly electrically grounded. An emitter frame may include one or more electrically conductive elongated emitter connection members (e.g., metal rod(s)) to which emitter electrodes can be commonly attached (e.g., wrapped at least partially around), even when different ones are disposed between different pairs of collectors, thereby simplifying wiring to the emitter system. The space between emitter electrodes and collectors can therefore be set simply by how the emitter electrodes are attached to emitter connection members and how an emitter frame is fixed relative to collectors, rather than the length or dimensions of insulating members (e.g., as in the case of collection panel 200 shown in
[0082]
[0083] Soiling and degradation of insulating members (e.g., that connect an emitter frame to a collector frame) can occur over time if constantly exposed to a plume (e.g., owing to the water as well as possibly dissolved contaminants in the water that would deposit on the surface over time). Side mounting emitter electrodes outside of collectors (e.g., using emitter frames) may place insulating members also outside of collectors, for example if collectors span a gas outlet. Keeping insulating members outside of a plume can reduce degradation and/or increase time to reach a detrimental level of degradation. To further slow and/or reduce degradation of insulating members, they can be arranged in a housing (e.g., a respective housing).
[0084] A power supply may be used to apply a voltage to emitters, while the collectors are connected to electrical ground. This configuration creates an electric field between the emitters and the collectors. Voltage applied to one or more emitter electrodes can be optimized to enhance collection over small areas and to minimize power consumption. Typical (but non-limiting) values for the strength of the electric field generated between emitter electrodes and collectors are 2-20 kV/inch.
[0085] In some embodiments, voltage applied to different emitter electrodes (e.g., different emitter electrodes that are positioned between the same pair of adjacent collectors) can be different. Voltage of emitter electrodes may be set based on a distance the emitter electrode is from a gas outlet. For example, all emitter electrodes within a first distance may be maintained at a first voltage and all emitter electrodes further than a first distance, but within a second distance, may be maintained at a second voltage. The second voltage may be lower than the first voltage. A system may thus be effectively divided into sections or slices and each section has its emitters at a certain voltage. Such arrangements allow for more efficient power usage. Moreover, different emitter geometries may be used in different sections to further optimize performance. For example, lower curvature (larger diameter) wires may be used as emitter electrodes in sections further from a gas outlet and higher curvature (smaller diameter) wires may be used as emitter electrodes in sections closer to the gas outlet.
[0086] Keeping power consumption low is desirable for a system to be economically viable and attractive. As an example, corona discharge consumes power by establishing a flow of ions from emitter electrodes to collectors. Hence, operating an emitter electrode at an optimum production rate of ions to minimally fully charge all species (e.g., water droplets) in a gas stream (e.g., plume) allows minimal current to be used, thereby minimizing energy consumption. A multi-stage design can help in this effort by splitting the collection process into separate charging and deflection stages. Corona discharge is only useful for the charging stage, and once species are charged, ordinary electrostatic fields can be used to deflect charged species without adding additional current and thus power consumption. Therefore, while additional conductive members (e.g., emitter electrodes) are desirable to include between collectors in order to provide additional charged species deflection, thereby enhancing species collection, it is not necessary for all such conductive members to be operated at a sufficient voltage to generate ions. Thus, in some embodiments, a lower voltage in the second stage or section (and thus less current) is used. Additionally or alternatively, different conductive member(s) that are less prone to generating current (such as plates or larger diameter rods or wires) may be disposed further along a path of gas flow from a gas outlet than emitter electrode(s) that are maintained at a relative higher voltage.
[0087]
[0088] Referring to
[0089] In some embodiments, a gutter is disposed at a bottom of a collector (e.g., each of a plurality of collectors). A gutter may be attached to a collector. A gutter may include a channel placed around the bottom of the collector. Collected species (e.g., water) drain down a collector due to gravity and fall into the gutter. A gutter may be angled downward (e.g., relative to level ground) to more readily allow its contents to flow toward a periphery of a system. A gutter may be connected to collection conduit (e.g., a tube or pipe), for example at a periphery a system, to transfer the collected species. A gutter may be common to several collectors or each collector may have its own respective gutter. An edge of an electrically conductive collector may be disposed in a gutter. For example, the gutter may be attached to two opposing surfaces of the collector. A gutter may include one or more collection wings, for example to direct collected fluid down into the gutter. A gutter may include a tubular member into which fluid can drain. A gutter with collection wings may be shaped such that when droplets shed down a collector (e.g., a mesh), they are funneled into the gutter rather than hitting the collector-gutter interface and redirecting outwards and drip off of the system.
[0090]
[0091] A panel may include one or more electrically insulating members.
[0092] In some embodiments, insulator material, shed geometry and overall dimensions of an electrically insulating member are selected to optimize the electrically insulating member's resistance to shorting in wet conditions. An electrically insulating member may have a dielectric strength of at least 200 kV/cm (e.g., at least 400 kV/cm). An electrically insulating member may have a surface energy of no more than 25 mN/m. In some embodiments, sheds are utilized to breakup surface conduction pathways from end-to-end of an electrically insulating member and to prevent from surface arcing or surface electrical breakdown. An electrically insulating member may include polytetrafluoroethylene (PTFE). In some embodiments, an electrically insulating member comprises a polytetrafluoroethylene (PTFE) cylinder. PTFE has useful dielectric properties (a dielectric strength about 600 kV/cm) and is hydrophobic (having a surface energy of about 20 mN/m). The hydrophobicity of PTFE facilitates effective drainage of water during a wetting event and may prevent arcing due to stagnant water patches along a surface of an electrically insulating member. An electrically insulating member may be cylindrical (e.g., having a cylindrical volumetric extent).
[0093] In some embodiments, an electrically insulating member includes one or more sheds, for example three sheds. In some embodiments, shed(s) have a particular radius relative to a central core. The difference between these two values is known as the “shed overhang” dimension of an electrically insulating member. Sheds may have the same or different overhangs in a given electrically insulating member. In some embodiments, nearby sheds are spaced apart by a certain dimension that evenly spaces the sheds along a central core setting a pitch or shed separation between adjacent sheds. A ratio of shed overhang to shed pitch may be kept above a certain optimal ratio based on empirical data that correlates the optimal ratio as a function of the conductivity of a fluid (e.g., water) the electrically conductive member is being sprayed with or exposed to. This ratio increases as the fluid draining along the electrically conductive member increases in conductivity. An overall length of an electrically conductive member may be dictated by a pre-determined (e.g., optimal) spacing between emitter electrodes and fluid collection electrodes.
[0094] In some embodiments, each of one or more sheds of an electrically insulating member comprises a knife edge (e.g., an about 60° knife edge). A knife edge may facilitate droplets draining effectively from each shed and avoid any pooling on a bottom edge of the shed.
[0095] In some embodiments, the fluid collection member and the emitter electrode assembly member are physically connected using one or more electrically insulating members (e.g., at least four or at least six electrically insulating members). The one or more electrically insulating members may have a dielectric strength of at least 200 kV/cm (e.g., at least 400 kV/cm). The one or more electrically insulating members may have a surface energy of no more than 25 mN/m. Each of the one or more electrically insulating members may comprise polytetrafluoroethylene (PTFE). Each of the one or more electrically insulating members may comprise one or more sheds. Each of the one or more electrically insulating members may comprise three sheds. In some embodiments, the one or more sheds overhang a central core of the electrically insulating member by a distance from 10 mm to 20 mm. In some embodiments, each of the one or more sheds is separated from each adjacent shed by a distance of from 10 mm to 30 mm. The distance may be from 17.5 mm to 22.5 mm. Each of the one or more sheds may have a thickness of from 2 mm to 3 mm. In some embodiments, each of the one or more sheds comprises a knife edge (e.g., an about 60° knife edge). Each of the one or more electrically insulating members may be cylindrical. In some embodiments, each of the one or more electrically insulating members has a longitudinal length and the longitudinal length may be from 25 mm to 150 mm, for example from 25 mm to 75 mm.
[0096] In some embodiments, collected fluid can be fed into a cold-water return (e.g., of a cooling tower), a hot water line, a basin of a cooling tower, a location at a facility, or into a water distribution system (e.g., a municipal water system). This can be done by directly feeding collected amounts of fluid down toward the relevant line, or toward a separate tank, which then feeds into the desired return, line, basin, facility or system. In some embodiments, water can be used in other parts of a plant (e.g., power plant) or sold separately.
[0097] Depending on ambient conditions and quality of collected fluid, an intermediate filtering step can be used to purify collected fluid to a certain standard (e.g., a condenser coolant water quality standard), which may depend on location and facility a species collection system. Filtration may be preferred if a particle injector is used to enhance condensation rate of gas in a gas stream.
[0098] Fluid used for cooling may be, for example, water such as brackish water or seawater. Collecting fluid from a gas stream may have an added benefit of desalinizing water while also abating plume. That is, seawater may be used, for example for cooling, and pure, unsalinated water may be collected using a system described herein. In some embodiments, the system is combined with a cooling tower using seawater or other brackish water as feedwater, resulting in an ultra-low cost desalination system. A coastal power plant may use seawater in a cooling tower and an installed species collection system can then collect pure water coming out of the cooling tower, which can be used for domestic, industrial or agricultural needs.
[0099] Collected fluid may be much purer than source fluid that is then later dispersed in a gas stream. For example, collected water can be much purer than circulating water in a cooling tower. Contamination may enter collected fluid from the presence of drift that is also collected with the distilled water in the plume. In some embodiments, collected fluid has a purity (e.g., contaminants concentration) that is at least 5× and no more than 50× higher (e.g., at least 5× and no more than 50× lower contaminants concentration) than a purity of the fluid before the fluid entered the gas stream. Collected water may be used as a source of fresh water, as the water does not have to be used for cooling but can be used for other municipal uses. For example, collection conduit can carry collected fluid away from collection panel(s) and towards a storage tank, municipal water system, or other water circulating system.
[0100] In some embodiments, a system is installed at a cooling tower where an optimization algorithm for the tower is modified to optimize for both water and energy consumption. In previous systems, the temperature of the recirculating water is mostly selected to optimize for energy costs (e.g., from pumping, etc.). By adding a collection system as disclosed herein, a new optimization that takes water into account in the equation may be used and lead to even higher savings, since more water can be collected if the cooling tower was operated in another way (e.g., higher hot water temperature).
[0101]
[0102] Certain embodiments of the present disclosure were described above. It is, however, expressly noted that the present disclosure is not limited to those embodiments, but rather the intention is that additions and modifications to what was expressly described in the present disclosure are also included within the scope of the disclosure. Moreover, it is to be understood that the features of the various embodiments described in the present disclosure were not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations were not made express, without departing from the spirit and scope of the disclosure. Having described certain implementations of species capture systems, apparatus, and methods, it will now become apparent to one of skill in the art that other implementations incorporating the concepts of the disclosure may be used. Therefore, the disclosure should not be limited to certain implementations, but rather should be limited only by the spirit and scope of the following claims.