The present disclosure describes a system and method for separating solids from liquid-solid slurries.
There are a number of applications that involve separating solids from liquid-solid slurries. These applications include, but are not limited to, sewage sludge dewatering, storm water catch basin cleaning, paper pulp processing, sediment removal, separating cuttings from extracted minerals in mining, and dredging. In many applications, an objective is to separate clean liquid from suspended solids as quickly as possible for the lowest cost. The cleanliness of the liquid may be measured by the percentage of suspended solids, which is a factor often determined by environmental rules or other criteria.
In some applications, the separated solids may be classified as solid waste, requiring disposal in a landfill. In landfill applications, the cost of disposal may be related to the weight and volume of the solids. Because liquids add significantly to both the weight and volume of the solids, there is a strong economic motive to minimize the moisture content of the separated solids. Energy consumption may also be a significant factor in the cost of separation.
In addition to various mechanical liquid-solid separation processes, many of these applications may also employ chemical liquid-solid separation technologies such as flocculants, coagulants, and charge packs. These chemical processes may operate in conjunction with mechanical liquid-solid separation, and chemicals may be inserted into the flow of the liquid-solid slurry either before or during the mechanical liquid-solid separation process. These chemical processes may work in various ways to make it easier for the mechanical separation processes to function. For example, the addition of polymer flocculants to a liquid-solid slurry assists the solids in joining together in clumps—known as “flocs”—which may be filtered or screened.
In some applications, such as hydraulic dredging, a party separating solids from a liquid-solid slurry faces a continuous flow of incoming slurry. For example, in commercial hydraulic dredging applications, this flow rate is generally a minimum of 500 U.S. gallons per minute, which is dictated by the flow rate of commercially available pumps. Other applications may require different flow rates for different periods of time.
Thus, there is a need for a highly effective system/method for separating solids from liquid-solid slurries which is capable of handling continuous flows at significant flow rates while enabling the removal of solids to meet appropriate moisture content requirements. In addition, there is a need to be able to supplement such a process with chemical liquid-solid separation technologies.
An objective of the present invention may be to employ mechanical processes for separating solids from a liquid-solid slurry to meet appropriate objectives for moisture content of the separated solids without requiring further chemical processing.
Another objective of the present invention may be to supplement mechanical processes for separating solids from a liquid-solid slurry with traditional chemical liquid-solid separation processes without limiting the effectiveness of the chemical process.
Another objective of the present invention may be to rapidly produce dried solids separated from a liquid-solid slurry and to expel the solids for disposal during separation process.
Yet another objective of the present invention may be to operate within a limited footprint. The present subject matter described herein may provide a solution to this problem by rapidly separating solids from a liquid-solid slurry thereby eliminating the need to store large volumes of liquid-solid slurry on site.
These and other objects may be achieved with a liquid-solid slurry separation method and system that may collect incoming liquid-solid slurry in a collection vessel. Excess liquid or slurry may be decanted from the vessel and transferred to a storage basin, released to the environment, separated in other types of mechanical separation systems, or separated in similar filter units as described herein.
Within the collection vessel, gravity and hydrostatic pressure may feed collected liquid-solid slurry into a pump. There may be a regulating mechanism which controls the flow of the slurry into the pump and which may be operated to slow or stop slurry flow between the collection vessel and the pump. The pump may also perform this regulating function. Other types of regulating mechanisms may include doors, gates, valves, including one-way valves to prevent the flow of slurry from the pump into the collection vessel. From the pump, slurry may flow into a filter element.
The filter element may include openings configured in a size and shape appropriate to capture the solids within the slurry while allowing liquids to escape. In some configurations, the filter element may be configured in a substantially horizontal or slightly inclined position and may be open at a far end. In other configurations, the end of the filter element may include a valve. Appropriate materials for manufacturing the filter element may include stainless steel, titanium, other non-reactive metals, polymers, ceramics, or other substances.
As the slurry passes into the filter element from the pump, the element captures the solids, and liquid passes through the openings in the filter. The force of the pump may compact the solids into a compressed “cake.” The pump may also push the solid cake through the opening at the end of the filter element.
When a piston pump is used, a regulator may be necessary to stop the flow of slurry from the collection vessel, though the piston itself may be the regulator. Piston pumps may employ multiple cylinders, each connected to a separate filter element, to enable continuous operation without a separate regulator. Other types of pumps may allow continuous operation without a separate regulator; these include but are not limited to screw pumps, progressive cavity pumps, and lobe pumps.
When a piston pump is used, depending on the volume of compressed cake within the filter element, the piston may be retracted, the regulating mechanism opened, and additional slurry may flow into the filter element, with the filtration and compaction process repeated until the filter element is substantially filled with solids in the form of a compressed cake.
When a piston pump is used, once an operator has reached a desired volume of solids at a desired moisture content, the piston or ram may then operate as a clearing mechanism to push the compressed solid cake through an opening at the end of the filter element for collection and disposal.
Some embodiments may have a valve at the end of the filter element. The valve may be closed to compact the collected solids and to remove additional moisture from the collected solids. When an operator wishes to expel the collected solids, the valve may be opened either before the expelling action or as a result of the force of expelling action.
With the filter element substantially cleared of collected solids, the pump may be operated to accept incoming slurry. In various embodiments with screw, progressive cavity, diaphragm, or other pumps that may be operated continuously, the continued operation of the pump is all that is necessary to accept incoming slurry. In alternative embodiments, such as those employing piston pumps, the piston may be retracted. Once the piston or ram has been retracted and the filter element is clear of any materials, the regulating mechanism may be opened to accept slurry or liquids from the collection vessel.
In embodiments with a valve at the end of the filter element, the valve may be closed with an actuator or automatically upon removing force applied to the valve or to a linkage or mechanism.
These and other features and advantages of the present disclosure will be understood upon review of the following detailed description, the accompanying drawings and the appended claims.
The present disclosure may address one or more of the problems and deficiencies of other attempted solutions discussed above. However, it is contemplated that the present disclosure may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the present disclosure should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In one aspect the invention features a system for separating solids from a liquid-solid slurry including a collection vessel having a first opening and at least one second opening positioned below the first opening. The collection vessel is configured to receive the liquid-solid slurry through the first opening and to discharge the liquid-solid slurry through the at least one second opening. There is at least one filter unit having a chamber with a first end, a second end and a filter surface between the first end and the second end of the chamber. The filter surface has a plurality of apertures and the second end of the chamber has a discharge port. There is at least one pump unit interconnected to the first end of the chamber of the at least one filter unit. One of the at least one filter unit or the at least one pump unit is in fluid communication with the at least one second opening in the collection vessel and is configured to receive the liquid-solid slurry from the at least one second opening and direct a flow of the liquid-solid slurry through the filter unit chamber. This causes liquid from the liquid-solid slurry to flow through the apertures and out of the chamber of the filter unit and causes solids from the liquid-solid slurry to be retained in the chamber of the filter unit. The at least one pump unit includes a discharge device which is translatable from the first end to the second end of the chamber of the filter unit to force solids retained in the chamber toward the discharge port.
In other aspects of the invention one or more of the following features may be included. The collection vessel may include a top portion, a bottom portion, a first end portion and a second end portion and wherein the first opening is in the top portion and the at least one second opening is in the bottom portion. The collection vessel may include a plurality of collection sections distributed from the first end portion to the second end portion and wherein the collection sections are separated by dividers. Each of the dividers may comprise a baffle. Each collection section of the collection vessel may include a second opening through which the liquid-solid slurry is discharged. There may be included a plurality of filter units and a like plurality of pump units one connected to each of the plurality of filter units, wherein one of each of the plurality of filter units or its pump unit is connected to one of the second openings in the collection sections. There may be a flow regulator in fluid communication with each of the second openings in the collection sections to regulate flow of the liquid-slurry discharged from each of the second openings. Each of the plurality of filter units may include a valve at the discharge port of the filter unit and wherein the valve may be selectively opened and closed to allow or disallow solids retained in the chamber to be discharged out of the discharge port. In a compression mode, for each of the plurality of filter units the valve at the discharge port of the filter unit may be closed and the discharge device is activated to translate toward the second end of the chamber to compress the solids in the chamber against the closed valve and force out retained liquid from the solids. Each of the valves may include a door which is pivotably mounted to the chamber at the discharge port so that when the solids retained in the chamber are forced against the door by the discharge device as it is translates from the first end to the second end of the chamber the door is opened; and wherein each door may include a spring affixed to the door and to the filter unit proximate the discharge port which expands when the door is opened as the discharge device forces solids out of the discharge port and when the solids are discharged and when the discharge device retracts the spring retracts and causes the door to close.
In yet other aspects of the invention one or more of the following features may be included. Each pump may include a pump inlet connected to the second opening to receive the flow of the liquid-solid slurry from a respective collection section. Each pump may include a pump cavity interconnected to the pump inlet, and wherein the pump cavity may be interconnected to the filter chamber so as to allow the flow of liquid-solid slurry to pass through the pump cavity and into the filter chamber. The discharge device may include a piston and an actuator to extend and retract the piston; wherein when the piston is in a retracted position it is located in the pump cavity and when it is activated to extend it translates through the pump cavity and into the filter chamber to cause a surface of the piston to force solids retained in the chamber out of the discharge port. When the piston is activated to extend from the pump cavity to the filter chamber, the piston may block the pump inlet thereby preventing the flow of the liquid-slurry discharge until after the piston is retracted and is no longer blocking the pump inlet. Each filter unit may have a quadrilateral cross-section. The apertures in each filter unit may be disposed in each of four sides of the chamber and the apertures each have a length substantially greater than its width. The at least one filter unit may include a liquid collection vessel to collect the liquid from the liquid-solid slurry which flows through the apertures; and there is further included a conduit in communication with the liquid collection vessel and configured to direct liquid from the liquid collection to the first opening in the collection vessel for further filtration.
In another aspect the invention features a method for separating solids from a liquid-solid slurry including introducing a liquid-solid slurry into a collection vessel through a first opening and discharging the liquid-solid slurry through at least one second opening positioned below the first opening. The method includes providing at least one filter unit having a chamber with a first end, a second end, and a filter surface between the first end and the second end of the chamber, the filter surface having a plurality of apertures, the second end of the chamber having a discharge port. The method also includes providing at least one pump unit interconnected to the first end of the chamber of the at least one filter unit. The method additionally includes receiving the liquid-solid slurry from the at least one second opening by the at least one filter unit or the at least one pump unit and directing a flow of the liquid-solid slurry through the filter unit chamber to cause liquid from the liquid-solid slurry to flow through the apertures and out of the chamber of the filter unit and to cause solids from the liquid-solid slurry to be retained in the chamber of the filter unit. The method further includes forcing solids retained in the chamber toward the discharge port using a discharge device which is part of the at least one pump unit, wherein the discharge device is translatable from the first end to the second end of the chamber of the filter unit.
In other aspects of the invention one or more of the following features may be included. The collection vessel may include a top portion, a bottom portion, a first end portion and a second end portion and wherein the first opening is in the top portion and the at least one second opening is in the bottom portion. The method may include providing the collection vessel includes providing a plurality of collection sections distributed from the first end portion to the second end portion and wherein the collection sections are separated by dividers. Providing the plurality of collection sections may include providing each of the dividers with a baffle. Providing the plurality of collection sections may include providing each collection section with a second opening through which the liquid-solid slurry is discharged. The method may include providing a plurality of filter units and a like plurality of pump units one connected to each of the plurality of filter units, wherein one of each of the plurality of filter units or its pump unit is connected to one of the second openings in the collection sections. The method may include regulating a flow of the liquid-slurry discharged from each of the second openings using a regulator in fluid communication with each of the second openings in the collection sections. The method may include providing each of the plurality of filter units with a valve at the discharge port of the filter unit and selectively opening and closing the valve to allow or disallow solids retained in the chamber to be discharged out of the discharge port.
In yet other aspects of the invention one or more of the following features may be included. The method may include closing, in a compression mode, the valve at the discharge port of each of the filter units and translating the discharge device toward the second end of the chamber to compress the solids in the chamber against the closed valve and force out retained liquid from the solids. The method may include providing each of the valves with a door pivotably mounted to the chamber at the discharge port, translating the discharge device from the first end to the second end of the chamber to force the solids retained in the chamber against the door, causing the door to open and a spring affixed to the door and to the filter unit proximate the discharge port to expand and when the discharge device forces solids out of the discharge port retracting the discharge device causing the spring to retract and close the door. The method may include providing each pump with a pump inlet connected to the second opening to receive the flow of the liquid-solid slurry from a respective collection section. The method may include providing each pump with a pump cavity interconnected to the pump inlet, and connecting the pump cavity to the filter chamber so as to allow the flow of liquid-solid slurry to pass through the pump cavity and into the filter chamber. The method may include providing the discharge device with a piston and an actuator to extend and retract the piston; wherein when the piston is in a retracted position it is located in the pump cavity and when it is activated to extend it translates through the pump cavity and into the filter chamber to cause a surface of the piston to force solids retained in the chamber out of the discharge port. The method may include extending the piston from the pump cavity to the filter chamber, and causing the piston to block the pump inlet thereby preventing the flow of the liquid-slurry discharge until after the piston is retracted and is no longer blocking the pump inlet. The chamber of each filter unit may have a quadrilateral cross-section. The method may include disposing the apertures in each filter unit in each of four sides of the chamber and providing the apertures with a length substantially greater than its width. Providing the at least one filter unit may include providing a liquid collection vessel to collect the liquid from the liquid-solid slurry which flows through the apertures; and further providing a conduit in communication with the liquid collection vessel to direct liquid from the liquid collection to the first opening in the collection vessel for further filtration.
In various embodiments, the liquid-solid slurry may be treated with a combination, mixture, or compound of liquid-solid separation chemicals assembled into a separation chemistry. The presence of separation chemistry may assist in the operation of the system 10 for separating solids from a liquid-solid slurry as discussed herein, though the separation chemicals are not required at all stages of operation, and separation chemistry may be added to the slurry at various points in the operation of the system 10 for separating solids from a liquid-solid slurry as discussed herein. For example, in some embodiments, separation chemistry may be present in the slurry introduced into the collection vessel 20, and in other embodiments, the separation chemistry may be added to the slurry after the slurry has entered the collection vessel 20.
In various other embodiments, the liquid-solid slurry may pass through a shaker screen, a rock box, a sand screw, or similar structure to remove objects of specific sizes before the slurry enters the collection vessel 20.
Various embodiments of system 10 separate a liquid-solid slurry into liquid and solid components. The collected solids may be disposed of in the environment, in a landfill, or in another process. The liquids, which in various embodiments include water, may be drained, decanted, or collected and returned to the environment, stored, cleaned, filtered, or employed in another process. In some embodiments, decanted or filtered liquid may be reintroduced into the incoming slurry to recycle the separation chemistry, to optimize the liquid-solid ratios, or to otherwise facilitate the solid separation process. In some further embodiments, the decanted or filtered liquid may be introduced into the slurry flow before the slurry enters the system 10 for separating solids from a liquid-solid slurry as shown in
In various embodiments, solids separated from a liquid-solid slurry are compressed into “cake” form, which represents separated solids at a desired moisture content. In some embodiments, the appropriate moisture content of the solid cake may be measured with a “paint filter test,” in which solid cake is placed in a paint filter for a period of time—if water breaks away from the solids, then it indicates that the cake contains too much moisture and requires additional filtering or drying. Separated solids may be extracted from the filter element 50 and returned to the environment, stored, disposed of in a landfill, composted, or used in other processes.
An overview of the main components of system 10 for separating solids from a liquid-solid slurry is depicted in
Collection vessel 20 includes a first end portion 210 and a second end portion 212 between which are included a plurality of collection sections 20a-20e distributed from the first end portion 210 to the second end portion 212. The collection sections are separated by dividers 220a-220d which are lower in height than the top opening 22 of the collection vessel 20. Each divider includes a baffle 230a-230e which allows liquid solid slurry to flow over from one collection section to the next by passing through the respective baffle. The filtered liquid in the end collection section 20e when filled to the level of baffle 230e drains out from the collection vessel into a container (not shown).
At the bottom of collection vessel 20 there are openings 24a-24e in each collection section 20a-20e, respectively, through which the liquid-solid slurry may be discharged and provided to a pump/filter unit. The pump units 40a-40e are shown to receive the liquid-solid slurry from the collection vessel, however, the flow from the collection vessel could alternatively be received by the filter units 50a-50e which are interconnected to the pump units 40a-40e, respectively. To regulate flow from the collection section to a pump/filter unit a regulator, such as regulator 28a interconnected to collection section 20a, may be included. The regulator may be any kind of suitable valve which can be manually or automatically operated. In the case of automatic operation, the valve may be opened and closed via hydraulic, pneumatic, or electrical actuation under the control of a control system. Such a regulator may be interconnected between each of the other collection sections 20b-20e and their respective pump/filter units, but for clarity they are not shown in this figure. As described below, instead of providing a separate regulator, the pump units 40a-40e may be configured to operate as a flow regulator.
Each one of the filter units 50a-50e has a chamber with a first end connected to a pump unit and a second end with a discharge port through which filtered solids may be discharged after they have been collected. At the discharge port there may be included a valve or gate (not shown in this view) which may be operated manually or controlled to open and close automatically under the control of a control system. The filter units each have a filter surface with a plurality of apertures, through which liquid from the liquid-solid slurry flows leaving solids in the filter chamber. Each pump unit 40a-40e may be used to force solids retained in its respective filter chamber towards and out of the discharge port. This may be done by manually activating the pump or automatically using a control system. This process is described in more detail below.
The liquid exiting the filter units may then be collected in a collection tank (not shown) if the output (or effluent) for a particular application is sufficiently clean. The effluent would then be removed from the site and properly disposed. However, in certain applications, the effluent may need to be recirculated for further filtering before it may be collected and disposed. In this case, the liquid from the liquid-solid slurry which has flowed through the filter surfaces in the filter chambers may be collected by a liquid collector surrounding the filter unit.
For ease of description, only liquid collector 52a is shown, however, it will be understood that a liquid collector associated with each filter unit 50a-50e may be included. Liquid collector 52a is interconnected to a conduit 54 to receive the effluent which is then pumped by pump 56 up conduit 58 where the effluent is reintroduced into collection section 20a for further filtration. It should be noted that effluent from each other filter unit 50b-50e could be recirculated to its respective collection section or the filter units may be interconnected to a manifold connected to pump 56 for recirculation to collection section 20a.
As shown in
An alternative arrangement of the pump/filter units relative to the collection vessel is depicted in
In some embodiments, the collection vessel 20 of
In some embodiments, the divider 220 shared by adjacent collection sections of collection vessel 20 may comprise a single sheet of material, or it may comprise several elements to provide appropriate geometry for routing the slurry into one or more pumps 40 as necessary. In some embodiments, liquid-solid slurry may flow between collection sections 20a-20e via baffles 230 located at the top of a dividers 220. The baffles 230 shown in
In some embodiments, the dividers 220 between individual collection sections may be lower than the exterior sides of the collection vessel 20 assembled into a system. The lower dividers 220 may allow slurry to pass between collection sections when the flow of slurry between the collection sections exceeds the capacity of the given collection section. In some embodiments, the collections sections may be separated only by dividers 220 without baffles 230. In various embodiments, slurry may pass from a first collection section to a second collection section when flow to a filter element 50 in the first collection section is stopped, such as when an operator has closed a regulator 30 or has stopped operation of a pump 40 and may be clearing solids from a filter element 50.
In some embodiments, the collection vessel 20 may resemble and operate as a manifold, and this manifold may be either open to the environment or enclosed in some manner. In some alternative embodiments, there may be no dividers. In other embodiments, more than one pump 40 may be connected to the collection vessel 20 or to each collection section, or a single collection vessel 20 may ultimately feed through pumps 40 and into more than one filter element 50.
In some embodiments, optimal operation of the filter system 10 may involve decanting as much liquid as possible from the collection vessel while enabling slurry to flow into the pump 40. In some embodiments liquid may pass over either the baffles 230 or divider 220. Some embodiments may not include a baffle 230, and in these embodiments liquid may pass over the divider 220. This may be a part of normal operation as clean liquid decants from one collection section to the next in the system 10 for separating solids from a liquid-solid slurry. In order to facilitate this flow, a second collection section may be placed lower than a first collection section; however, other configurations of dividers 220, baffles 230, and collection sections may be possible. Decanted liquid may be returned to the environment or collected as with the liquid separated elsewhere from the liquid-solid slurry as described herein.
The filter element may include a plurality of filter openings or apertures 320 that may be of various sizes and shapes to address different types of solids within the slurry. For example, the filter opening 320 for filtering a fine, silt material may be smaller than a filter opening 320 intended to filter sand from a liquid-solid slurry. The embodiment of filter opening 320 depicted in
In some embodiments, the filter element 50 as shown may be constructed out of metal. While many metals may suffice, those skilled in the art will recognize that non-reactive metals, such as stainless steel, may be preferable in some applications. The filter element 50 may be formed out of sheet metal by rolling or bending and brazing, welding, bonding, or other manufacturing methods known to those skilled in the art. In sheet-metal construction, the filter openings 320 may be cut out of the sheet before forming. Cutting methods may involve blades, etching, water jets, lasers, plasma, and other types of manufacturing approaches known to those skilled in the art.
In other embodiments, the filter element 50 may be extruded, cast, forged, or manufactured in an appropriate manner as known to those skilled in the art. In yet other embodiments, the filter element 50 may be constructed out of nonmetallic materials such as polymers, ceramics, and composite materials. In various embodiments, the filter openings 320 may be cut from the formed filter element, formed as part of element construction, or cut from the filter element material before the filter element is formed. In some embodiments, the filter openings 320 may be cut, etched or formed during molding, casting or forging.
Filter element 50 may be connected to a pump 40 with a bolted flange. In other embodiments, the pump 40 and filter element 50 may be attached using a variety of fasteners and connecting methods. In yet other embodiments, the filter element 50 may be formed in a single, integral unit with the pump 40. Those skilled in the art will recognize the advantages of a replaceable filter element 50 that may be changed to accommodate slurry types and to address wear in the filter element 50.
In various embodiments, such as those including a piston-type pump 40 or any other pump 40 in which a pump inlet 300 as shown in
In addition to the size and shape of the filter openings 320, various other factors may contribute to the performance of the filter element, including but not limited to: cross-sectional area of the filter element 50, height of the collection vessel 20, length of the filter element 50, and the presence or absence of a valve 340 at the end of the filter element 50.
In various embodiments, reducing the cross-sectional area of the filter element 50 may increase the force applied by the hydrostatic pressure of the slurry in the collection vessel. This may assist in compacting the solids collected in the filter element 50. Alternatively, increasing the height of the collection vessel 20 may achieve a similar result, although as the height of the collection vessel 20 increases, the vessel may begin to operate as a clarifier, and solids may separate from the slurry in the collection vessel 20.
In various embodiments, an objective may be to prevent solids from separating from the slurry in the collection vessel, because the solid materials may form “dams” within the collection vessel, which presents several problems well known to those skilled in the art. First, the collected solids within the vessel must be removed from the collection vessel, often manually. Second, the presence of “dams” leads to “rat-holing” within the collection vessel, which make it difficult for an operator to manage slurry flow. Third, in order to clear the collection vessel 20, one may need to introduce additional liquids into the vessel, often with additional separation chemistry as well. While it is possible to decant liquids from a slurry above the line between liquid and slurry—often referred to as the “water break”—an objective of the system 10 for separating solids from a liquid-solid slurry as discussed herein may be to primarily separate the solids from the slurry, below the water break, within the filter element 50. Those skilled in the art will recognize that many embodiments may tolerate some degree of solid separation within the collection vessel 20 so long as the solid separation does not affect slurry flow into the pump 40 and filter element 50.
In various embodiments, another factor in the performance of the filter element 50 may be the length of that structure. In some embodiments, a longer filter may not include a valve 340, such as the door valve as shown in
In alternative embodiments, an operator may require a shorter filter element 50 in order to satisfy the constraints of space for transport. For example, in a system 10,
In yet another embodiment, the valve 340 may be a gate, butterfly, or ball valve, and the hinge 350 and spring 360 may be absent, and an electric motor, solenoid, hydraulic actuator, pneumatic actuator, or other device may operate the valve 340. In a further embodiment, the valve 340 may be a duckbill valve, and the hinge 350 and spring 360 may be absent. In a yet further embodiment, the valve 340 may include a bladder and the hinge 350 and spring 360 may be absent—the bladder may be filled with a gas or liquid to prevent solids from escaping from the end of the filter element 50. In various embodiments, electrical, magnetic, electromagnetic, hydraulic, pneumatic, or other actuators may replace the spring 360 in numerous possible configurations to achieve a similar result.
The operation of the embodiment of filter unit 50 shown in
Valve 340 includes a door which is pivotably mounted to the chamber of the filter unit by a hinge 350 at the discharge port so that when the solids retained in the chamber are forced against the door by the discharge device (pump 40) as it is translates from the first end to the second end of the chamber the door is opened. The door includes a spring 360 affixed to the door and to the filter unit proximate the discharge port which expands when the door is opened as the discharge device forces solids out of the discharge port and when the solids are discharged and the discharge device retracts the spring retracts and causes the door to close.
In order to compress and expel collected solids, as described above, the system 10 may include a pump 40 as shown in
The embodiment shown in
A purpose of the pump may be to compact the collected solids within the filter element 50 and to expel the collected solids from the filter element 50 when an operator desires or under the control of the controller,
Those skilled in the art will recognize that many types of pumps may not function with filter openings 320 as shown in
b) Regulating Flow into the Pump
One may regulate flow through the pump inlet 300 in a number of ways, including but not limited to doors, gates, and valves. For example, in some embodiments, the regulator 30 may be a door located within the collection vessel 20, or affixed to it as shown in
There are several types of embodiments of pump 40 and regulator 30 combinations. In a first embodiment of regulator 30 and pump 40 combination, slurry may flow when the pump 40 is operated, and no separate regulator 30 is necessary. In this embodiment, the pump 40 may perform the function of the regulator 30, and whatever flow control capability exists in the pump 40 may define the regulating ability of the system 10. Examples of this first embodiment include, but are not limited to, progressive cavity pumps, lobe pumps, and screw pumps—when these types of pumps are not operating, slurry may not flow from the pump inlet 300 to the pump outlet 315 as is possible with the piston pump 40 shown in
In a second embodiment of regulator 30 and pump 40 combination, a separate regulator 30 may be necessary to prevent the system 10 from operating in an undesired manner. For example, as is shown in
In another scenario where undesired pump 40 operation may require a regulator 30,
In other embodiments, such as those with an auger pump 40, a regulator 30 may be the only way to stop slurry flow, because slurry may flow past the auger, thereby connecting the pump inlet 300 with the pump outlet 315, and no operation of the auger pump 40 will prevent this flow. Otherwise, those skilled in the art will recognize that in various embodiments, a number of structures and approaches may address the regulating function, including: an external regulator 30, a regulator 30 contained within the pump 40, an alternate design of the pump 40, or operation rules for the pump 40.
In a third embodiment of regulator 30 and pump 40 combination, a regulator 30 may be necessary to prevent slurry from flowing from the pump 40, through the pump inlet 300, and into the collection vessel 20. For example, in embodiments employing a diaphragm pump, a regulator 30 may prevent slurry from flowing back through the pump inlet 300 and into the collection vessel 20. In various embodiments, the regulator 30 may include a one-way valve, such as a check valve. As described above, the regulator 30 may be internal to the pump 40 or contained within the pump housing 440. Other pump types may require similar regulation.
The pump 40 includes a pump cavity interconnected to the pump inlet 300 and to the filter chamber at pump outlet 315 so as to allow the flow of liquid-solid slurry to pass through the pump cavity and into the filter chamber. The piston 410 is driven by actuator 430 to extend and retract the piston; 410. When the piston is in a retracted position it is located in the pump cavity and when it is activated to extend it translates through the pump cavity and into the filter chamber to cause a surface of the piston to force solids retained in the chamber out of the discharge port
Those skilled in the art will recognize that numerous types of commercially available slurry pumps 40 operate in duplex, triplex, and other configurations with two, three, or more pump assemblies operating in concert to allow continuous operation and steady slurry flow. For example, piston pumps and diaphragm pumps are commonly assembled in these configurations, because these types of pumps may not accept slurry during the cycle time in which a piston 410 is either pumping or retracting or a diaphragm is pumping slurry into the filter element 50. Various embodiments may include multiple pump 40 assemblies that share a common pump inlet 300 manifold connected to a single collection vessel 20. In other embodiments, each pump 40 within a multiple pump assembly may have a pump inlet 300 collected to a collection vessel 20. In some embodiments with a multiple pump 40 assembly, each pump 40 may be connected to a filter element 50. In other multiple pump 40 embodiments, multiple pumps 40 may be connected to one or more filter elements 50.
As discussed above, operating a piston pump for these aforementioned purposes may requires an operator to stop flow to the filter element 50 when the piston pump is in operation. This may be accomplished with a regulator 30 that may be a distinct structural element such as a door, gate, or valve; however, in the embodiment as shown in
In
Referring again to
In various embodiments employing a piston pump 40, the piston 410 may extend past a pump flange 310 or pump outlet 315 and into the filter element 50. An operator may choose to vary the speed and distance of piston 410 motion in order to optimize the formation of a cake from collected solids within the filter element 50 and to subsequently expel these solids through the filter end 330 or through a valve 340.
A first step 602 in operating the filter system 10 may be to accept incoming slurry in the collection vessel 20. In various embodiments, the operation of the collection vessels 20, dividers 220, and baffles 230 may enable the incoming slurry to flow in a continuous operation while regulating slurry flow to individual filter elements 50.
In various embodiments, during operation, clean liquid above the “water break” may be decanted in step 605 and transferred to a storage basin, released to the environment, separated in other types of mechanical separation systems, separated in similar filter units as described herein, or disposed of in an appropriate manner. Or some or all of the decanted liquid may be added to the incoming slurry at step 601 in order to re-use the separation chemistry within the decanted liquid or to optimize the separation process, such as by adding liquid to a slurry with a particularly high solid content. Those skilled in the art will recognize that the decanting steps, while not required for liquid-solid separation, offers various operational and process efficiencies. Such efficiencies may include eliminating the onsite sources of clean liquids for mixing separation chemistry or for optimizing the solid content of the slurry.
In step 606 regulator 30 may be opened to allow slurry to flow into the pump 40/filter element 50. In various embodiments as described herein, the regulator 30 may be a piston 410 that serves other functions as described herein. While
In various embodiments, the solids collected within the filter element may be compacted in step 612. In order to compact the solids, the regulator 30 may be closed, as in step 610, in order to stop the flow of slurry to the filter element 50.
In some embodiments, the step of compaction 612 may be initiated before closing the regulator 30 in step 610. For example, as described above, in embodiments in which the piston 410 may also operate as a regulator. Operating the piston 410 may stop the flow of slurry to the filter element 50. In such an approach, when step 612 is initiated to compact the solids, and the operation of the piston 410 may thereby close the regulator 30, as in step 610, which may stop flow of slurry to the filter element.
In embodiments where the piston 410 may not be the regulator 30, those skilled in the art will recognize that operating the piston 410 to compact solids in step 612 may actuate step 610 through a variety of mechanical and electrical structures. For example, the operation of piston 410 in the compaction step 612 may trigger a switch or an electrical, optical, or magnetic sensor to close the regulator 30. Alternatively, the operation of piston 410 in step 612 may contact or actuate a mechanical linkage to close the regulator 30 in step 610.
In other embodiments, an operator may elect not to perform step 610 and may not close the regulator 30 to the filter element 50 during the compaction step 612.
At decision point 614 the properties of the collected solids may be evaluated to determine if they meet the desired requirements. Such properties may include volume of collected solids, moisture content, or other factors. This may be done manually by an operator via, e.g. a “paint filter test” may be used to evaluate whether solids have reached a target moisture content. The paint filter test is one in which collected solids are placed on a paint filter element and observed for a period of time to determine whether water breaks from the collected solids. Those skilled in the art will be familiar with the paint filter test as applied at decision point 614. In the alternative, sensors may be used to detect the condition of the solids. Or, the system may be set to detect a predetermined pressure level in the compaction process and when detected terminate the compaction process. The predetermined pressure level may be set based empirical data which achieves a certain desired condition based on the composition of the solids.
If, at decision point 614, it is determined that the collected solids are not as desired, the piston may be retracted and the system may revert to either step 615 to continue further filtering or to step 616 institute further compaction and subsequent steps.
If, at decision point 614 it is determined that the properties of the solids collected in the filter element 50 are as desired, then the system proceeds to step 617 and the pump 40 expels the solids in step 618. In such an operation, step 618 may be a continuation of the compaction stroke of piston 410 as shown in step 612.
In embodiments of filter element 50 with an open end 330, expelling the solids 618 may include operating piston 410, as actuated by actuator 430 through connecting rod 420, for a sufficient distance through the filter element 50 so as to expel the majority of the solids collected therein. For example, the expulsion step 618 may require moving piston 410 through the entire filter element 50 so that the piston 410 reaches the filter end 330.
In embodiments of filter element 50 with a valve 340 at the end, step 618 of expelling solids may include the added step of opening the valve 340 at the end of the filter element. In some embodiments, the valve 340 may be operated by force applied by the piston 410, the piston 410 potentially acting through the collected solids pressing on the valve. In other embodiments the opening and closing of the valve 340 may be automatic. For example, an operator may employ electrical, magnetic, optical, or mechanical position sensors and may open and close the valve 340 based upon the position of the piston 410 within the filter element 50. In various embodiments, the expulsion step 618 concludes with the operator retracting the piston 410.
In step 624, the separated solids and liquids may be disposed of. In
At decision point 620 if additional slurry needs to be processed, in step 622 the operator retracts the piston 410 and repeats steps 602 through 618 as discussed herein. However, if there is no additional slurry to process, the remaining solids 624 and end operation 625 of the filter system 10.
While the present disclosure has been described with particular reference to certain embodiments of the system and method for separating solids from a liquid-solid slurry, it is to be understood that it includes all reasonable equivalents thereof as defined by the following appended claims.
g) Pumps that May not Require Regulators
In various embodiments employing pumps 40 that may not require regulators 30 to control slurry flow into the pump 40, operation as shown in
In embodiments with a diaphragm pump 40, step 606 may be unnecessary, because the regulator 30 may include a one-way valve that may allow slurry to flow through the pump inlet 300 during the pump 40 intake cycle.
The systems and methods described above are set forth by way of example and not of limitation. Numerous variations, additions, omissions, and other modifications will be apparent to one of ordinary skill in the art. Furthermore, the order or presentation of method steps in the description and drawings above is not intended to require this order of performing the recited steps unless a particular order is expressly required or otherwise clear from the context. Thus, while particular embodiments have been shown and described, it will be apparent to those skilled in the art that various changes and modifications in form and details may be made without departing from the spirit and scope of this disclosure and all reasonable equivalents thereof as defined by the following appended claims.
This application is the U.S. National Stage Application of International Application No. PCT/US2017/016986, filed on Feb. 8, 2017, which claims benefit of priority of U.S. Provisional Patent Application 62/294,328 filed on Feb. 12, 2016, which are incorporated herein by reference in their entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/US17/16986 | 2/8/2017 | WO | 00 |
Number | Date | Country | |
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62294328 | Feb 2016 | US |