Patent Application
20200324226
Various industries, including the paper and pulp industries and food processing industries by way of non-limiting example, involve the generation of undesirable foam within and on the processing line. Left uncontrolled, this foam can accumulate uncontrollably and eventually shut down a processing line. A typical industry solution involves the addition of chemical de-foaming or anti-foaming agents to a liquid (e.g., water) associated with the industrial process in question. Although chemical additives have proven effective in controlling unwanted foam accumulation, effective non-chemical methods and solutions have been sought. Two reasons for avoiding chemical additives are cost and safety. Safety is a particular concern in industrial food processing settings because measures must be taken to ensure that levels of chemicals coming in contact with the food and remaining thereon after processing are acceptably low.
Typically, the composition of built-up foam transitions from a ‘wet foam’ at the bottom of the foam (small bubble structure with water-like flowability) to a ‘dry foam’ at the surface (large bubbles that adhere to all surfaces and resist flow). Once a significant foam build-up has accumulated, most of the foam volume consists of the drier foam. Several non-chemical approaches for foam control have been evaluated over the years. Some are currently utilized to a limited degree, but primarily to selectively augment chemical additives. There are primarily three basic non-chemical approaches for foam control: (1) water spray, (2) optical, and (3) centrifugal, each of which is briefly described in turn.
Downwardly-directed vertical water sprays are sometimes used to partially “knock down” the foam by spraying the top-surface dry foam to condense it from dry foam to wet foam and thereby reduce the total volume. Large foam-control spray systems are sometimes used in waste treatment and aquaculture farms. The use of water-spray foam control is confined primarily to localized trouble areas, where, due to a combination of physical layout and/or turbulent water flow, foam generation is rapid. These local sprays can be limitedly effective; however, in many cases, these sprays, while reducing the foam volume at the point of impact, can create holes in the foam while pushing foam into the periphery of the spray impact area where it continues to grow. Even the condensed ‘wet foam’ can continue to grow unacceptably within the spray impact area, thus minimizing any further reduction in foam volume. The use of a sprays in these localized ‘hot spots’ does not address the foam problem on the entire production line where, due to the continuous agitation throughout a facility, the foam builds within vessels, channels, and tanks, for example.
Optical solutions for controlling foam have been proposed and selectively tested. In one such system, a high power laser is used to destroy foam. These lasers emit light at or near a wavelength at which the liquid has a strong absorption line. It is believed that the optical absorption by the liquid locally heats the surface of a bubble and causes its destruction. One implementation of this approach includes a CO2 laser mounted directly over a tank into which foam flows, and where additional foam is also generated due to turbulence within the tank. The laser beam ‘writes’ a line across the foam in a continuously varying pattern. The line defines a region in which the foam is destroyed and the underlying surface water is exposed. Rapid writing of the laser beam reduces the foam volume in those regions and further inhibits foam growth because it provides a localized “non-foamed” region which the surrounding foam fills, thus reducing the rate of foam growth in surrounding regions of the tank. Cost is a primary factor restricting the commercial deployment of such systems. The combination of the systems' capital costs and their operating costs, especially for deployment on a distributed processing line, is widely considered prohibitive.
Centrifugal systems have been used successfully for many years in a variety of industries and applications for separating the constituent liquids and gases of mixtures consisting of liquids and gases. Centrifugal gas/liquid separators typically rotate the liquid itself creating a cyclone or vortex within the liquid. As the “mixed medium” is rotated, the higher-density liquid is driven to the outside leaving behind on the inside the less dense gas, which can be subsequently removed.
Since foam is a gas/liquid mixture of, for example, air and water, a centrifugal gas/liquid separator can be a reasonable approach for non-chemical de-foaming. Consequently, variations of this technology have been studied and have resulted in designs, patents, and products directed at de-foaming applications. For the most part, air/gas separators are complicated systems, all of which require some subset of not only the means for high speed water rotation, but also vacuum systems, pumps, multi-stage impellers, filtering systems, and even heat. These systems do not lend themselves to in-situ foam control, but are best operated as an off-line system where the foamy solution needs to be pulled from all the key areas of the product-flow line into the separator(s), filtered, de-foamed, and then carefully pumped back into the line so as not to generate additional foam. Thus, the current separators manifest themselves as additional stand-alone closed operating systems. The costs associated with these systems are high and include capital cost, installation, maintenance, and floor space.
Other de-foaming technologies exist, but for very specialized applications, such as the aeration/separation systems used in aqua/fish farming. Similar to the application mismatches described above, these are large systems utilizing aeration, pumping, and evacuation techniques. Ultrasonic solutions have also been proposed, and have found specialized applications, such as in canning operations, but have similarly proved not to be a good general fit for broad applications.
To address the aforementioned problems, the sole inventor named in the present application devised a chemical-free foam control system that is now the subject of U.S. Pat. No. 9,713,779, granted Jul. 25, 2017 (hereinafter, the “779 patent”). As successful as that solution has proven in practical implementations, it is also characterized by certain limitations under certain conditions. The limitations of certain “real-world” implementations of the system of the 779 patent lead to innovation of the present system and method.
Like the invention of the 779 patent, the present system builds upon the need for a cost effective, chemical-free foam control system and method that lends itself to broad implementation across various industries challenged by undesirable foam generation. Moreover, like the system of the 779 patent, fluid-spray sources (e.g., “nozzles” or “diffusers”) are implemented in accordance with the present invention. However, the chief principles upon with the two systems operate are mutually distinct. In order to facilitate an appreciation for how the solutions of the 779 patent and the present invention differ, a summary of key operative parameters and conditions of the 779 system are provided as part of the background of the present application.
As explained in the summary of the 779 patent, in each of various implementations of that invention, there is established a foam-displacement path along which foam resulting from a relevant industrial process is to be moved. Also established is a direction along the foam-displacement path in which resultant foam is to be displaced as the foam accumulates on the surface of the liquid associated with the industrial process. In various industrial processes, the “liquid associated with the industrial process” as defined above, and in the claims appended hereto, will comprise water. In still more particular implementations, the liquid associated with the industrial process lacks chemical defoaming additives such as those presently employed and described in the background section of the specification.
A set of fluid-spray sources is provided including at least first and second fluid-spray sources from each of which a foam-subsiding fluid can be selectively ejected under pressure. In a typical implementation, the set of fluid-spray sources will include many more than two fluid-spray sources, but the inventive concept covered by the 779 patent is sufficiently broad to include implementations employing only first and second fluid-spray sources. Moreover, in practice, each fluid-spray source will comprise at least one spray nozzle.
A key aspect of the inventive system described and claimed in the 779 patent is that the fluid-spray sources (e.g., spray nozzles) are serially arranged above the surface of the liquid associated with the industrial process. In the potato washing context, for example, this will mean the fluid-spray sources are arranged above the wash table, which includes a reservoir of water that serves as the “liquid associated with the industrial process.” Each fluid-spray source is configured such that foam-subsiding fluid ejected therefrom is sprayed in a spray pattern that is centered about a spray axis. Additionally, each spray pattern, regardless of its general configuration (e.g., planar or conical) is representable by a spray vector extending along the spray axis. Each fluid-spray source is oriented such that its associated spray vector has (i) a non-zero component of spatial extension directed perpendicularly to, and downwardly toward, the liquid associated with the industrial process and (ii) a non-zero component of spatial extension directed parallel to the surface of the liquid associated with the industrial process and in the foam-displacement direction. The serial arrangement of the fluid-spray sources defines the foam displacement path.
When a system of the 779 patent is in use, foam-subsiding fluid is ejected from the fluid-spray sources such that foam impacted by foam-subsiding fluid ejected from the first fluid-spray source is wetted, partially subsided, and displaced in the foam-displacement direction toward the spray being ejected from the second fluid-spray source by which the foam is further wetted, subsided and displaced in the foam-displacement direction. Where the system implements three or more fluid-spray sources, foam initially displaced by the first fluid-spray source is displaced toward, under, then through the spray pattern associated with each successive fluid-spray source along the foam-displacement path, each time being further wetted, subsided and displaced. The result is that the foam volume is reduced in increments as the foam is displaced long the foam-displacement path.
In the inventive method of the 779 patent, foam reduction is tied to movement of accumulated foam along a defined foam-displacement path over the surface of an is underlying industrial-process liquid on which the foam is floating. The foam-displacement path typically has discernable starting and ending points, even in implementations in which the foam-displacement path is cyclic. While foam reduction is successive as the foam is moved sequentially between and through fluid-spray sources serially arranged along—and defining—the foam-displacement path, there are cases in which not all of the foam that has been generated is completely subsided before the final set of fluid-spray sources along the foam-displacement path is reached. This may especially be the case in systems characterized by non-cyclic foam-displacement paths, as defined in the 779 patent. The result, especially in systems lacking one or more drains through which residual foam can exit, is that foam reaching the end of a non-cyclic path can eventually accumulate undesirably in “dead zones.”
Accordingly, a need exists for further subsiding residual foam left unabated by systems configured in accordance with the invention of the 779 patent. In various implementations, it is envisioned that a system configured for further subsiding residual foam be implemented in conjunction with a system configured to move foam in sequential increments along a foam-displacement path in the general manner described and claimed in the 779 patent.
Like the foam control system and method of U.S. Pat. No. 9,713,779, various alternative implementations of a foam control system (alternatively, “foam abatement system”) and method within the scope of the present invention have in common the objective of subsiding foam resulting from an industrial process. However, whereas the system of the 779 patent relies upon, and actively induces in its various implementations, movement of the undesired process-resultant foam along the surface of the underlying industrial-process liquid (e.g., water) on which the foam is floating, the present system and method is configured to “trap” the foam to be subsided within a foam-depletion zone and minimize the movement of the foam undergoing depletion with respect to the underlying industrial-process fluid.
By way of non-limiting example, implementations are suited for use in industrial processes involving the washing of starchy or pulpy materials (e.g., paper, agricultural produce, etc.) which, when washed and/or churned in a reservoir of liquid associated with the industrial process, yield foam that accumulates on the liquid. One example of a process for which implementations of the method and system is particularly well-suited involves the preparation of potatoes for the making of potato chips and, more particularly, the washing of potato slices in a wash table before the potato slices are conveyed out of the wash table for subsequent processing (e.g., cooking). While some implementations of the system and method are explained and described in the context of potato processing in both the summary and detailed description, it is to be understood that the invention as defined in the appended claims is not so limited, except to the extent that particular claims are expressly so limited by their own terminology. On the contrary, explicitly within the scope and contemplation of the overall inventive concept is its configuration for, and application within, nearly any process resulting in the production and accumulation of undesirable foam on the surface of an associated, underlying industrial-process liquid, which liquid will frequently include water.
By way of establishing an illustrative environment, each of various implementations is envisioned as a method of subsiding foam resulting from an industrial process and accumulating on the surface of an industrial-process liquid associated with that industrial process along a horizontal liquid-surface plane corresponding to the surface of the industrial-process liquid. Throughout the specification and claims, the term “horizontal,” as in “horizontal plane,” is used in the sense ordinarily understood, and with reference to the earth's gravitational field. That is, if the weight force of an object on earth is represented by a vector “downwardly directed” toward earth's center, then a horizontal plane is one that is orthogonal to this wright-force vector. Additionally, terms such as “vertical,” “above,” “below,” and “downwardly,” and derivatives and synonyms thereof, are used in a similar sense.
Importantly, implementations of the method include designating a foam-depletion zone within which residual foam resulting from the industrial process is situated. The foam-depletion zone has defined in association therewith a depletion-zone perimeter and, inwardly of the depletion-zone perimeter, a depletion-zone center region that, in various implementations, includes a geometric center of the foam-depletion zone.
A set of fluid ejectors is provided that, at least in their individual configurations, but not in their mutual arrangement and alignment, may generally correspond to the fluid-spray sources of the 779 patent. In any event, like the fluid-spray sources of the 779 patent, each fluid ejector is configured to selectively eject a foam-subsiding fluid under pressure in a spray pattern that is representable by a spray vector. Moreover, the spray pattern is typically centered about a spray axis along which the spray vector extends.
While some system configurations within the scope and contemplation of the invention employ as few as two fluid-ejectors working “in opposition” to one another, initial discussion of an implementation employing a plurality of at least three fluid ejectors facilitates conceptualization, and is also more representative of a “real world application.” The fluid ejectors are peripherally disposed above the liquid-surface plane and about the depletion-zone perimeter. In this way, the fluid ejectors are above residual foam that is situated within the bounds of the depletion-zone perimeter and on the surface of the liquid associated with the industrial process (a.k.a., the industrial-process liquid).
In addition to their peripheral disposition, the fluid ejectors are mutually arranged so that they are inwardly and downwardly directed toward the depletion-zone center region. Illustratively, each of the fluid ejectors is oriented such that the spray vector associated therewith has (i) a non-zero vertical component of spatial extension directed perpendicularly to, and downwardly toward, the liquid-surface plane and (ii) a non-zero horizontal component of spatial extension directed (a) parallel to the liquid-surface plane and (b) inwardly of the depletion-zone perimeter, and toward the depletion-zone center region, so as to constrain within the foam-depletion zone, by action of the spray patterns collectively emanating from the fluid ejectors, foam situated within the foam-depletion zone for sustained impingement by the spray patterns. In other words, in more layman-like parlance, the general idea is to circumscribe foam within the foam-depletion zone with fluid ejectors such that the spray patterns emanating therefrom mutually cooperate to bombard the foam from opposing sides thereof and “trap” it within the foam-depletion zone by the action of equal and opposite spray forces so that it is subjected to continuous subsidence by the spray patterns.
As previously indicated, various implementations of the method aspect involving the containment and depletion of foam within a foam-depletion zone may be employed in conjunction with the methods of U.S. Pat. No. 9,713,779 in which the foam is intentionally moved with a non-zero net velocity relative to the underlying industrial-process liquid. Accordingly, the entirety of the detailed description of the 779 patent is actually included in the detailed description below, as are all of the drawings (
Representative embodiments are more completely described and depicted in the following detailed description and the accompanying drawings.
The following description of variously configured and implemented foam control and foam abatement systems and methods is demonstrative in nature and is not intended to limit the invention or its application of uses. Accordingly, the various implementations, aspects, versions and embodiments described in the summary and detailed description are in the nature of non-limiting examples falling within the scope of the appended claims and do not serve to restrict the maximum scope of the claims.
Shown in
In order to provide an illustrative context and environment in association with which variations of the system 10 may be employed, alternative implementations are described with principal reference to
As illustrated in each of
The fluid-spray sources 40 are serially arranged above the surface 22 of the industrial-process liquid 20. Each fluid-spray source 40 as the capacity to selectively eject under pressure a foam-subsiding fluid FFS. Moreover, each fluid-spray source 40 is configured such that foam-subsiding fluid FFS ejected therefrom is sprayed in a spray pattern 44 that is centered about a spray axis AS. Illustrative spray patterns 44 are shown in
Regardless of its general configuration (e.g., planar or conical), each spray pattern 44 is representable by a spray vector VS extending along the spray axis AS about which that spray pattern 44 is centered. As depicted most clearly in the example represented by the schematic side view of
For ease of identification and further discussion, the horizontal component of a spray vector VS (i.e., the spatial-extent component of non-zero magnitude that is parallel to the surface 22 of the industrial-process liquid 20) is denoted by a dashed arrow labeled with the alphanumeric reference character VS-X. In keeping with this Cartesian notation convention, the vertical component of a spray vector VS (i.e., the spatial-extent component of non-zero magnitude that is perpendicular, or “orthogonal,” to the surface 22 of the industrial-process liquid 20) is denoted by a dashed arrow labeled with the is alphanumeric reference character VS-Y. Of course, it will be readily appreciated that the ratio VS-Y/VS-X is directly related (by the trigonometric function “tangent”) to the spray-source orientation angle θ at which the spray vector VS is pitched relative to horizontal. Nevertheless, the ratio VS-Y/VS-X itself is an important factor to conceptualize in relation to the functionality of various implementations and may vary among locations along the foam-displacement path PFD. Presently, relative to various implementations, it is sufficient to observe in very general terms that, of the two spatial-extent components, the vertical component VS-Y is principally responsible for subsiding foam 15, while the horizontal component VS-X is principally responsible for moving the foam 15 along the surface 22 of the industrial-process liquid 20 in the foam-displacement direction DFD. Accordingly, implementations of the foam control system 10 are most efficient when the ratio VS-Y/VS-X is optimized at each fluid-spray source 40 for both the foam-subsiding and foam-displacement factors simultaneously.
With broader reference once again to
As discussed in the summary, as well as above in the detailed description relative specifically to the spray-source orientation angle θ and the ratio VS-Y/VS-X, the reduction in the volume of foam 15 as the foam 15 is impacted and displaced by foam-subsiding fluid FFS is a function of one or more alternative factors. In addition to those factors already discussed, foaming conditions of the specific industrial processing setting within which the foam control system 10 and method is implemented determines parameters for each fluid-spray source 40. In addition to the spray-source orientation angle θ, other important parameters include (i) the height H of each fluid-spray source 40 above the upper surface 22 of the industrial-process fluid 20, (iii) the configuration of the spray pattern 44, (iv) the spray droplet size, and (v) the force with which the spray impacts the foam 15 and the surface 22 of the industrial-process liquid 20. Such parameters are selected with the objective of optimizing foam-condensation efficiency and movement (flow rate) of the condensed foam 15, while minimizing the creation of additional foam 15 due to the spray impact on the surface 22 of the industrial-process liquid 20.
In various settings, minimizing the spray-source orientation angle θ works favorably for all desired effects. Lower spray-source orientation angles θ tend to increase the effective cross-sectional area of the spray pattern 44, especially for “full” spray patterns (e.g., a filled or full conical spray pattern), thus increasing the area of foam 15 that is impacted for condensation. Moreover, as the spray-source orientation angle θ is decreased, the “forward thrust” component of the spray force (i.e., along the VS-X component of the spray vector VS) increases, thus facilitating the movement of the condensed foam 15 along the foam-displacement path PFD.
In one illustrative implementation, at least the first fluid-spray source 40A ejects a “full spray” spray pattern 44A. A non-limiting illustrative example of a “full spray” spray pattern 44 is shown in the left side portion of
Referring to the right side portion of
As described in the summary, alternative implementations of a chemical-free foam control system 10 employ “non-cyclic” and “cyclic” foam-displacement paths PFD. Included in
An aspect common to systems 10 implementing non-cyclic or cyclic foam-displacement paths PFD is that there is a path start PS corresponding to a first fluid-spray source 40A and a path end PE corresponding to a last or final fluid-spray source 40. In a non-cyclic implementation, such as those of
Referring again specifically to
Referring still to
As with the examples of the previous schematics, the foam control system 10 employs a plurality of fluid-spray sources 40 which, in the present example, are numbered 44A thru 44F using consecutive letters of the alphabet. The system 10 depicted in
In either a cyclic or non-noncyclic operative mode, foam 15 (omitted in this drawing for clarity) is moved along the foam-displacement path PFD from the path start PS near fluid-spray source 40A toward fluid-spray source 40D. In either case, the foam 15 is moved in a non-lineal way and, in this particular setting, its movement is enhanced by the rotation of the partially-immersed wash drum 110 which, when viewed from the wash-drum input end 112, rotates counter-clockwise, thereby conveying foam 15 sprayed by fluid-spray source 40B on one side of the drum-rotation axis ADR toward fluid-spray source 40C located on the opposite side of the drum-rotation axis ADR.
In order to operate the system 10 of
While illustrative implementations discussed above focused principally on scenarios in which the horizontal component VS-X of each spray vector VS is directed in the foam-displacement direction FFD, there are within the scope and contemplation of the invention alternative versions in which the VS-X component of each spray vector VS is directed in opposition to the foam-displacement direction DFD. For instance, shown in
To this point, the detailed description has addressed foam control systems 10 in which foam 15 is moved along a foam-displacement path PFD with an intentional non-zero net velocity relative to the underlying industrial-process liquid 20 on which the foam 15 is accumulating and floating. Attention is now turned to the alternative, and conceptually distinct, methods in which foam is trapped and subsided by continuous impingement by sprayed foam-subsiding fluid FFS within a foam-depletion zone configured to minimize the net velocity of foam 15 relative to the underlying industrial-process liquid 20. However, because it is envisioned that both system types will be used in conjunction with one another, the latter type of system is described with initial reference to a schematic in which both systems are illustrated.
The schematic top-down view representation of
A principal difference between
Regardless of any elevational disparity between the upper surface 22 of the industrial-process liquid 20 in the reservoirs 25 and 225, as residual foam 15 is delivered to the foam abatement system 210, it accumulates on the upper surface 22 of the industrial-process liquid 20 along a horizontal liquid-surface plane PLS corresponding to the upper surface 22. Implementations of the method include designating a foam-depletion zone 230 within which residual foam 15 resulting from the industrial process is situated. In various implementations, the foam-depletion zone 230 has defined in association therewith a depletion-zone perimeter 232 and, inwardly of the depletion-zone perimeter 232, a depletion-zone center region 234 that, in various implementations, includes a geometric center 235 of the foam-depletion zone 230. In this particular case, the depletion-zone perimeter 232 coincides with the single tank-side wall 226 of the illustrative reservoir 225 depicted.
A set of fluid ejectors 240 is provided that, at least in their individual configurations, but not in their mutual arrangement and alignment, may generally correspond to the fluid-spray sources 40 associated with the foam control system 10. In the non-limiting illustrative case of
As with the fluid-spray sources 40, each fluid ejector 240 is configured to selectively eject a foam-subsiding fluid FFS under pressure in a spray pattern 244 that is representable by a spray vector VS. Moreover, the spray pattern 244 is typically centered about a spray axis AS along which the spray vector VS extends. The full discussion of the spray vectors VS associated with the fluid-spray sources 40, and the spray patterns 44 emitted therefrom, applies with equal validity to the nature of the spray vectors VS associated with the fluid ejectors 240, and the spray patterns 244, emitted therefrom. Accordingly, further discussion of same is omitted for purposes of efficiency and brevity.
With reference to
In addition to their peripheral disposition, and as seen perhaps best in
In the example of
In one such arrangement, fluid ejectors 240 disposed in mutual opposition, and peripherally of the foam-displacement path PFD defined by fluid-spray sources 40, eject foam-subsiding fluid FFS perpendicularly to the foam-displacement path PFD toward the center of the foam-displacement path PFD. In such a case, the depletion-zone center region 234 would be toward the center of the foam-displacement path PFD. While
The foregoing is considered to be illustrative of the principles of the invention. Furthermore, since modifications and changes to various aspects and implementations will occur to those skilled in the art without departing from the scope and spirit of the invention, it is to be understood that the foregoing does not limit the invention as expressed in the appended claims to the exact constructions, implementations and versions shown and described.
The present application is a continuation application of International Application Serial No. PCT/US2018/051685 filed Sep. 19, 2018 pursuant to the Patent Cooperation Treaty, and under the title “CHEMICAL-FREE FOAM ABATEMENT SYSTEM AND METHOD EMPLOYING MUTUALLY OPPOSED FLUID DIFFUSERS.” Application PCT/US2018/051685 claimed priority benefits in U.S. Provisional Application No. 62/560,853 filed Sep. 20, 2017 under the title “CHEMICAL-FREE FOAM ABATEMENT SYSTEM AND METHOD EMPLOYING MUTUALLY OPPOSED FLUID DIFFUSERS.” The present application claims the benefit of the filing date of Provisional Application Ser. No. 62/560,853, as well as the filing date of PCT Application No. PCT/US2018/051685, based on the priority chain outlined above. Moreover, the entireties of the disclosures, including the drawings, of both previous applications in the aforesaid priority chain are incorporated herein by reference as if set forth fully in the present application.
| Number | Date | Country | |
|---|---|---|---|
| 62560853 | Sep 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2018/051685 | Sep 2018 | US |
| Child | 16822215 | US |
