Liquid level control separator for foam forming

Abstract

A method and system for foam forming a web is disclosed. Foamed suspensions of materials, such as fibers and other particles, are fed to one or more forming zones that are sequentially positioned along an inclined forming surface. A plurality of corresponding discharge devices are positioned below the forming surface for discharging excess fluid from the newly formed web. The flow rate of fluid discharged from the web is controlled relative to the flow rate or pressure of the foamed fiber suspension fed to the forming zones.

Description

Background Technology

[0001] Many tissue products, such as facial tissues, toilet paper, paper towels, and industrial wipes, are produced using a wet-laid web forming process. Wet-laid webs are made by depositing an aqueous suspension of pulp fibers onto a shaped fabric and then removing the water from the newly formed web.

[0002] To improve the various properties of tissue paper webs, webs have also been formed using a foaming process. During the foaming process, a foamed fiber suspension is formed and spread onto a moving porous conveyor belt for initial web production. Foam-formed webs can exhibit improvements in bulk, stretch, thickness, and / or absorbency. Besides tissue paper webs, foaming can be used to manufacture all different types of webs and products. For example, relatively long fibers and synthetic fibers can be incorporated into webs using the foaming process. Therefore, the foaming process is more versatile than many wet web forming processes.

[0003] In some conventional foam forming systems, one or more fan pumps flow foam from the separator silo to the return tank via short water channels. This arrangement can have disadvantages. For example, large fan pumps and / or vacuum assistance may be required to provide sufficient suction pressure for the low-density form in the separator silo. As another example, the compressibility of the foam in the separator silo may limit the degree of vacuum that can be applied at the separator silo.

[0004] A system for improving foam control between separation silos and return water tanks would be useful. Summary of the Invention

[0005] Overall, this disclosure relates to an improved method and system for flowing foam between a separator and a tank. A pump is operable to flow foam from the separator into the tank. The pump can be controlled based on signals from a sensor detecting the level of foam in the separator to maintain the foam level in the separator. The method and system of this disclosure can advantageously help reduce or prevent over-discharge or under-discharge of foam from the separator. Furthermore, over-discharge of foam from the separator may entrain large bubbles from the separator into the foam stream, which may reduce foam density and impede foam flow. In contrast, over-discharge of foam from the separator may cause a loss of vacuum in the separator, foam agitation in the separator, and introduction of foam into a vacuum source. By operating the pump to maintain the foam level in the separator, such negative effects of over-discharge and under-discharge can be limited or prevented. The method and system of this disclosure can also advantageously help provide a consistent residence time of foam in the separator, which can improve foam stability.

[0006] In one example embodiment, the foam forming system includes a headbox and a tank. A separator is disposed between the headbox and the tank along a flow path for foam. The separator includes an inlet for foam, a first outlet for foam, and a second outlet for free air from the foam. The foam forming system also includes a pump. A sensor is operable to determine the level of foam in the separator. A controller is configured to receive a signal from the sensor corresponding to the level of foam in the separator, and to operate the pump, at least in part, based on the level of foam in the separator, to maintain the level of foam within the separator within a determined range.

[0007] In another example embodiment, the foam forming system includes a tank. A vacuum separator includes an inlet for foam, a first outlet for foam, and a second outlet for free air from the foam. The vacuum separator is coupled to the tank via the first outlet, allowing foam to flow from the vacuum separator into the tank. A pump is operable to flow foam from the vacuum separator into the tank. A sensor is operable to determine the level of foam in the vacuum separator. A controller is configured to determine the level of foam in the vacuum separator based at least in part on signals from the sensor, and to operate the pump at least in part on the determined level of foam in the vacuum separator to maintain the level of foam within the vacuum separator within a determined range.

[0008] In another example embodiment, the method for foam forming includes: flowing foam from a headbox to a vacuum separator; allowing free air from the foam to exit the vacuum separator through a vacuum outlet; and operating the pump to allow the foam to exit the vacuum separator through a foam outlet. Operating the pump includes using a sensor to determine the level of foam in the vacuum separator, and adjusting the pump flow rate based at least in part on the determined level of foam in the vacuum separator to maintain the foam level within the vacuum separator within a determined range.

[0009] Other features and aspects of this disclosure are discussed in more detail below. Attached Figure Description

[0010] The disclosure, which is comprehensive and enables the implementation of this disclosure, is set forth in more detail in the remainder of the specification and with reference to the accompanying drawings, in which:

[0011] Figure 1 This is a schematic diagram of a system and method for forming a web from a foamed suspension of materials, according to an example embodiment of the present disclosure;

[0012] Figure 2 This is a schematic diagram of a system and method for depositing a foamed suspension of material onto a molded surface according to an exemplary embodiment of the present disclosure; and

[0013] Figure 3 This is a schematic diagram of a system and method for separating free air from a foam stream during foam forming of a nonwoven web, according to an example embodiment of the present disclosure.

[0014] Figure 4 This is a flowchart of a method for separating free air from a foam stream during foam forming of a nonwoven web, according to an example embodiment of the present disclosure.

[0015] The repeated use of reference numerals in this specification and the accompanying drawings is intended to indicate the same or similar features or elements of the invention.

[0016] definition

[0017] When describing elements of this disclosure or its preferred embodiments, the articles “a,” “an,” “the,” and “the” are intended to indicate the presence of one or more of the elements. As used herein, the term “includes / including” is intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). As used herein throughout the specification and claims, approximate language is used to modify any quantitative expression that allows for variation without causing a change in the essential function associated with it. Thus, values ​​modified by one or more terms such as “about,” “approximate,” and “substantially” are not limited to the specified precise values. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value. For example, approximate language may refer to a limit of ten percent (10%).

[0018] As used herein, the term "foam-formed product" means a product formed from a suspension of a mixture comprising solids, liquids and dispersed air bubbles.

[0019] As used herein, the term “foam forming process” refers to a process used to manufacture products involving suspensions of mixtures comprising solids, liquids and dispersed bubbles.

[0020] As used herein, the term "foaming fluid" means any one or more known fluids that are compatible with other components in the foam forming process. Suitable foaming fluids include, but are not limited to, water.

[0021] As used in this article, the term "foam half-life" refers to the time elapsed until half of the initial foam material has reverted to liquid water.

[0022] As used herein, the term "layer" refers to a structure that provides a substrate region in the height direction of a substrate composed of similar components and structures.

[0023] As used herein, the term “nonwoven web” refers to a web having a structure of individual fibers or threads that are layered but not in an identifiable manner (as in knitted webs).

[0024] As used herein, unless otherwise expressly indicated, when used in relation to the composition of materials, the terms “percentage,” “%,” “weight percentage” or “weight %” each refer to the amount of a component as a percentage of the total amount by weight, unless otherwise expressly indicated.

[0025] The term "personal care absorbent articles" as used herein refers to articles intended or adapted to be placed close to or near the wearer's body (i.e., adjacent to the body) to absorb and contain various liquid, solid, and semi-solid excretions from the body. Examples include, but are not limited to, diapers, diaper pants, training pants, youth pants, swim trunks, feminine hygiene products (including but not limited to menstrual pads or pants), incontinence products, medical clothing, surgical pads, and bandages, etc.

[0026] As used herein, the term “superabsorbent material” refers to a water-swellable, water-insoluble organic or inorganic material, including superabsorbent polymers and compositions thereof that, under most favorable conditions, are capable of absorbing at least about ten times (10X), at least about fifteen times (15X), or at least about twenty-five times (25X) of their weight in an aqueous solution containing nine-tenths (0.9) wt% sodium chloride.

[0027] As used herein, the term "longitudinal" refers to the direction of travel of the shaped surface on which fibers are deposited during the formation of the nonwoven web. As used herein, the term "transverse" refers to the direction perpendicular to the longitudinal as defined above. As used herein, the term "pulp" refers to fibers derived from natural sources such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, Spanish grass, milkweed, straw, jute, and bagasse. Pulp fibers may include hardwood fibers, softwood fibers, and mixtures thereof. As used herein, the term "average fiber length" refers to the average length of fibers, fiber bundles, and / or fibrous materials determined by measurement using microscopy. A sample of at least 20 randomly selected fibers is separated from a liquid suspension of fibers. The fibers are placed on a microscope slide prepared to suspend the fibers in water. A coloring dye is added to the suspended fibers to color the cellulose-containing fibers so that they can be distinguished or separated from synthetic fibers. The slide was placed under a Fisher Stereomaster II microscope—S19642 / S19643 series. Twenty fibers in the sample were measured using a 0-20 mil scale at 20X linear magnification, and the average length, minimum and maximum length, and deviation or coefficient of variation were calculated. In some cases, the average fiber length was calculated as a weighted average length of the fibers (e.g., fibers, fiber bundles, fibrous materials), determined using, for example, a Kajaani Fiber Analyzer model FS-200 from Kajaani Oy Electronics, Kajaani, Finland. The sample was treated with an impregnation solution according to standard testing procedures to ensure the absence of fiber bundles or debris. Each sample was decomposed in hot water and diluted to a suspension of approximately 0.001%. When testing using standard Kajaani fiber analysis testing procedures, approximately 50 ml to 100 ml of test sample was drawn from each diluted suspension. The weighted average fiber length can be an arithmetic mean, a length-weighted mean, or a weight-weighted mean, and can be expressed by the following equation:

[0028]

[0029] Where k = maximum fiber length x i =fiber length n i =Number of fibers of length xi, n =Total number of fibers measured. A characteristic of the average fiber length data measured by the Kajaani fiber analyzer is that it does not distinguish between different types of fibers. Therefore, the average length represents the average length based on all different types (if any) of fibers in the sample.

[0030] As used herein, the term "short fiber" refers to discontinuous fibers made from synthetic polymers such as polypropylene, polyester, post-consumer recycled (PCR) fibers, nylon, etc., and those that are non-hydrophilic can be treated to become hydrophilic. Short fibers can be cut fibers, etc. Short fibers can have cross-sections such as round, bicomponent, multicomponent, molded, hollow, etc. Detailed Implementation

[0031] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this disclosure.

[0032] Overall, this disclosure relates to a system and method for forming foam from nonwoven webs. In this system, a separator silo is separated from a return water tank, and a pump can be configured to flow foam from the separator silo to the return water tank. The pump can be controlled to maintain a consistent level range for the foam in the separator silo. Furthermore, the level of the foam in the separator silo can be measured by a sensor (such as a capacitive rod), and the pump can be controlled based on the sensor measurement. The separator silo can be configured to operate under vacuum, and the return water tank can be configured to operate at ambient pressure.

[0033] The systems and processes disclosed herein offer various advantages and benefits. For example, the system may include a fan pump, which is separate from the main pump and configured to push foam from the return tank into the headbox. By utilizing the pump to maintain a consistent level range for the foam in the separator silo, the fan pump can operate with increased efficiency and stability. Therefore, the suction head of the fan pump can be improved, and / or a centrifugal pump can be used at the fan pump instead of a vacuum-assisted centrifugal pump. As another example, the vacuum level throughout the system can be increased, and the desired vacuum level can be decoupled from the machine height. Therefore, by utilizing the pump to maintain a consistent level range for the foam in the separator silo, the height difference between the free surface of the foam in the separator silo and the free surface of the foam in the return tank can be significantly reduced. As another example, utilizing the pump to maintain a consistent level range for the foam in the separator silo can help reduce or prevent over- or under-discharge of foam from the separator silo. Therefore, it is possible to avoid entraining large air bubbles from the separator silo into the foam stream, and / or to avoid introducing foam into the vacuum source used for the separator silo. As another example, using a pump to maintain a consistent level range for the foam in the separator silo can help provide a consistent residence time for the foam in the separator, which can improve foam stability.

[0034] See Figure 1 and Figure 2Example embodiments of systems and processes according to aspects of this disclosure are shown. Generally, during this process, solid materials (such as fibers and / or superabsorbent particles), water, and foam-forming agents are added to a tank and mixed until desired air content, bubble size / foam stability, and solid dispersion (such as fiber dispersion) are achieved. The fiber-containing foam may then be optionally diluted during the process, particularly in the presence of a recirculation flow. In one example aspect, the air content of the foaming suspension is between about thirty percent (30%) and about sixty-five percent (65%). As will be described below, example aspects of the methods and systems of this disclosure relate to, for example, separating and managing foam from free air during foam formation of nonwoven webs.

[0035] Figure 1 Examples are given of systems and processes for producing foamed fiber suspensions and for forming webs from foamed fiber suspensions. It will be understood that... Figure 1 The example system shown is provided by way of example, and any suitable web forming system can be used according to this disclosure. Figure 1 As shown, the system may include a mixing tank 12 configured to form a foamed fiber suspension. The foamed fiber suspension may then be fed into a headbox or web forming system 10, which deposits the foamed fiber suspension onto a porous forming surface 26 for web forming 14. The mixing tank 12 may be connected to a water supply 22 for feeding water into the tank and a foaming agent or surfactant supply 24 for feeding surfactant into the tank 12. Fiber feedstock may also be fed into the tank 12 and combined with water and surfactant. The aqueous solution formed by mixing surfactant and water may be agitated and formed into foam to form the foamed fiber suspension. As described above, various other materials besides fibers may be combined in the tank 12. For example, such other materials may include superabsorbent particles, etc.

[0036] Surfactants or blowing agents may, for example, contain any suitable surfactant. In one example embodiment, the blowing agent may contain sodium lauryl sulfate, also known as sodium lauryl polyoxyethylene ether sulfate or sodium lauryl ether sulfate. Other blowing agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other example embodiments, the blowing agent may contain any suitable cationic and / or amphoteric surfactants. For example, other blowing agents include fatty acid amines, amides, amine oxides, fatty acid quaternary ammonium compounds, etc. In one example embodiment, a nonionic surfactant is used. For example, a nonionic surfactant may include alkyl polysaccharides. For example, in one aspect, the surfactant may be a C8 alkyl polysaccharide, a C10 alkyl polysaccharide, or a mixture of C8 and C10 alkyl polysaccharides.

[0037] The foaming agent can generally be combined with water in an amount greater than about one-tenth by weight (0.1%), such as in an amount greater than about half by weight (0.5%), such as in an amount greater than about seven-tenths by weight (0.7%). One or more foaming agents can generally be present in an amount from about one percent by weight (0.01%) to about five percent by weight (5%), such as in an amount as high as about two percent by weight (2%).

[0038] When foaming agents and water are combined, the mixture can be blended or otherwise subjected to forces capable of forming foam. Foam is generally referred to as an aggregate of hollow cells or air bubbles.

[0039] Foam density can vary depending on the specific application and various factors, including the fiber formulation used. In one example embodiment, the foam density can be greater than about 200 g / L, such as greater than about 250 g / L, such as greater than about 300 g / L. Foam densities are generally less than about 600 g / L, such as less than about 500 g / L, such as less than about 400 g / L, such as less than about 350 g / L. In one example embodiment, for example, a lower density foam is used, which is generally less than about 350 g / L, such as less than about 340 g / L, such as less than about 330 g / L. For example, at standard temperature and pressure (STP), foam can typically have an air content greater than about 40%, such as greater than about 50%, such as greater than about 60%. An air content by volume is typically less than about 75%, such as less than 70%, such as less than 65%.

[0040] Foam can be formed in the presence of fiber ingredients, or alternatively, foam can be formed first and then combined with fiber ingredients. Generally, any fiber capable of manufacturing a substrate (such as tissue paper webs or other similar types of nonwovens) can be used.

[0041] Fibers suitable for preparing webs include any natural or synthetic cellulose fibers, including but not limited to: non-wood fibers such as cotton, Manila hemp, kenaf, Indian grass, flax, thatch, straw, jute, bagasse, milkweed, and pineapple leaf fibers; and woody or pulp fibers, such as those obtained from broadleaf and coniferous trees, including softwood fibers such as northern and southern softwood kraft paper fibers; and hardwood fibers such as eucalyptus, maple, birch, and aspen. Pulp fibers can be prepared in high-yield or low-yield forms and can be pulped using any known method (including kraft paper, sulfite, high-yield pulping methods) and other known pulping methods. Fibers prepared by organic solvent pulping methods can also be used.

[0042] A portion of the fiber (such as up to 100% (100%) or less by dry weight, or about 5% (5%) to about 30% (30%) by dry weight) may be a synthetic fiber, such as rayon, polyolefin fiber, polyester fiber, bicomponent core-sheath fiber, multicomponent adhesive fiber, etc. The fiber may be virgin or recycled. The fiber may be short fiber and may have an average length of about three millimeters (3 mm) to about one hundred and fifty millimeters (150 mm). An exemplary polyethylene fiber is Fybrel®, available from Minifibers, Inc. (Jackson City, Tenn.). When containing synthetic polymer fibers, the web may be thermally bonded at the fiber intersections.

[0043] Synthetic cellulose fiber types include all varieties of rayon and other fibers derived from viscose or chemically modified cellulose. Chemically treated natural cellulose fibers, such as mercerized pulp, chemically hardened or cross-linked fibers, or sulfonated fibers, can be used. To achieve good mechanical properties when using papermaking fibers, it may be desirable for the fibers to be relatively undamaged and largely unrefined or only slightly refined. While regenerated fibers can be used, virgin fibers are generally available due to their mechanical properties and lack of contaminants. Mercerized fibers, regenerated cellulose fibers, cellulose produced by microorganisms, rayon, and other cellulose materials or cellulose derivatives can be used. Suitable papermaking fibers may also include regenerated fibers, virgin fibers, or mixtures thereof. In some example embodiments capable of achieving high bulk and good compressibility, the fibers may have a Canadian standard freeness of at least two hundred (200), more specifically at least three hundred (300), even more specifically at least four hundred (400), and most specifically at least five hundred (500).

[0044] Other papermaking fibers, including subgrade paper or recycled fibers, and high-yield fibers, can be used. High-yield pulp fibers are those papermaking fibers produced by pulping processes that provide a yield of about 65% (65%) or higher, more specifically about 75% (75%) or higher, and even more specifically about 75% (75%) to about 95% (95%). Yield is the amount of processed fiber obtained as a percentage of the initial wood mass. Such pulping processes include bleached chemothermal-mechanical pulp (BCTMP), chemothermal-mechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high-yield nitrite pulp, and high-yield kraft pulp, all of which result in fibers with high levels of lignin. High-yield fibers are known for their stiffness relative to typical chemothermal-pulped fibers in both dry and wet states.

[0045] Web fabric can also be formed without significant internal fiber-to-fiber bond strength. In this regard, the fiber formulation used to form the base web fabric can be treated with a chemical detacker. The detacker can be added to the foamed fiber slurry during the pulping process or directly to the headbox. Suitable detackers that can be used include cationic detackers, such as aliphatic dialkyl quaternary ammonium salts, monoaliphatic alkyl tertiary ammonium salts, primary amine salts, imidazoline quaternary salts, organosilicon quaternary salts, and unsaturated aliphatic alkyl ammonium salts. Other suitable detackers are disclosed in U.S. Patent No. 5,529,665 to Kaun, the entire contents of which are incorporated herein by reference. Specifically, Kaun discloses the use of cationic organosilicon compositions as detackers.

[0046] In one example embodiment, the detacking agent used in the process of this disclosure may be an organic quaternary ammonium chloride, and more specifically, an organosilicon amine salt of quaternary ammonium chloride. For example, the detacking agent may be PROSOFT.RTM. TQ1003 sold by Hercules Corporation. The stripping agent may be added to the fiber slurry in an amount of about one kilogram per metric ton (1 kg / ton) to about ten kilograms per metric ton (10 kg / ton) of fiber present in the slurry.

[0047] In an alternative example embodiment, the detackifier may be an imidazoline-based agent. Imidazolline-based detackifiers may be obtained, for example, from Witco Corporation. Imidazolline-based strippers may be added in amounts between two kilograms per metric ton (2.0 kg / ton) and up to fifteen kilograms per metric ton (15 kg / ton).

[0048] Other optional chemical additives may also be added to the aqueous papermaking ingredients or the initial web formed to impart additional benefits to the product and process. The following materials are examples of other chemicals that can be applied to the web. These chemicals are examples and are not intended to limit the scope of this disclosure. Such chemicals may be added at any time during the papermaking process.

[0049] Other types of chemicals that can be added to the paper web include, but are not limited to, absorbent additives such as low molecular weight polyethylene glycol and polyhydroxy compounds such as glycerin and propylene glycol, which are typically in the form of cationic, anionic, or nonionic surfactants, humectants, and plasticizers. Materials that provide skin health benefits, such as mineral oil, aloe vera extract, vitamin E, silicones, and general emulsions, can also be incorporated into the finished product.

[0050] Other examples of such materials include, but are not limited to, odor control agents such as odor absorbers, activated charcoal fibers and granules, baby powder, baking soda, chelating agents, zeolites, fragrances or other odor masking agents, cyclodextrin compounds, oxidants, etc. Superabsorbent granules may also be used. Additional options include cationic dyes, optical brighteners, humectants, emollients, etc.

[0051] Go to Figure 2 Once the foamed fiber suspension is in tank 12 ( Figure 1 The foamed fiber suspension, formed in the process, can then be fed into the web forming system 10. For example... Figure 2 As illustrated, the web forming system 10 may include one or more forming zones. Figure 2 In one example implementation, three forming regions are shown, including a first forming region 50, a second forming region 52, and a third forming region 54. Forming regions 50, 52, and 54 are positioned along the porous forming surface 26. In one example implementation, as... Figure 2As shown, the porous forming surface 26 can be inclined relative to a horizontal plane. For example, the porous forming surface 26 can be oriented at an angle greater than about ten degrees (10°), such as greater than about twenty degrees (20°), such as greater than about thirty degrees (30°), and generally less than about sixty degrees (60°), such as less than about fifty degrees (50°), relative to the horizontal plane. Each forming region 50, 52, and 54 can be configured to receive individual and independent streams of foamed fiber suspension for depositing the foamed fiber suspension onto the forming surface 26. For example, the first forming region 50 can deposit the foamed fiber suspension directly onto the forming surface 26. However, the second forming region 52 can be configured to deposit a second flow rate of foamed fiber suspension on top of the fibers deposited by the first forming region 50. Similarly, the third forming region 54 can deposit an aqueous suspension stream of fibers on top of the fibers deposited by the first forming region 50 and the second forming region 52. In this way, multilayer webs can be formed. However, it should be understood that the systems and processes disclosed herein may consist of only a single forming zone for forming a single-layer web.

[0052] like Figure 2 As shown, each forming zone 50, 52, and 54 can be in fluid communication with individual and independent foamed fiber supply lines. For example, the first forming zone 50 can be in fluid communication with the first foamed fiber supply line 56, the second forming zone 52 can be in fluid communication with the second foamed fiber supply line 58, and the third forming zone 54 can be in fluid communication with the third foamed fiber supply line 60. The first supply line 56, the second supply line 58, and the third supply line 60 can be configured to feed the foamed suspension of fibers into each of the respective forming zones 50, 52, and 54 with determined and selected flow characteristics, such as flow rate, volumetric flow rate, pressure, air content, and / or density. In this regard, each of the supply lines 56, 58, and 60 can be in fluid communication with the mixing tank 12, as... Figure 1 As shown. For example, the first supply line 56 may include a first injection line 62 connected to the mixing tank 12. Similarly, the second supply line 58 may include a second injection line 64, and the third supply line 60 may be in communication with the third injection line 66. Injection lines 62, 64, and 66 may all be in communication with the mixing tank 12 for feeding the foamed fiber suspension into each of the forming zones 50, 52, and 54. Alternatively, the system 10 may include separate mixing tanks, and each of the first injection line 62, the second injection line 64, and the third injection line 66 may be connected to a different corresponding mixing tank for feeding the foamed fiber suspension into the web forming system 10.

[0053] As shown in the figure, each of the foamed fiber supply lines 56, 58, and 60 may include a pumping device, a flow meter (such as a volumetric flow meter), a pressure monitoring device, and / or a temperature monitoring device. Each foamed fiber supply line 56, 58, and 60 may also be connected to a density monitoring device. For example, the density monitoring device may be part of other devices, such as a flow meter. Alternatively, information received from other instruments may be used to calculate the density of the foamed fiber suspension.

[0054] For example, the first foamed fiber supply line may include a first pumping device 68, a first flow meter 74, a first pressure monitoring device 80, and a first temperature monitoring device 81; the second foamed fiber supply line 58 may include a second pumping device 70, a second flow meter 76, a second pressure monitoring device 82, and a second temperature monitoring device 83; and the third foamed fiber supply line 60 may include a third pumping device 72, a third flow meter 78, a third pressure monitoring device 84, and a third temperature monitoring device 85. The pumping devices 68, 70, and 72 are adjustable, allowing the foamed fiber suspension to be fed independently to each forming zone 50, 52, and 54 at a desired, selected flow rate and / or pressure. The flow meters 74, 76, and 78, the pressure monitoring devices 80, 82, and 84 (e.g., volumetric flow rate), and the temperature monitoring devices 81, 83, and 85 can monitor the flow rate, pressure, and temperature upstream of the forming surface to calculate at least one characteristic of the flow of the foamed fiber suspension at the forming surface.

[0055] In one example implementation, flow meters 74, 76, and 78, pressure monitoring devices 80, 82, and 84, and temperature monitoring devices 81, 83, and 85 may be positioned in communication with one or more controllers. The controllers may include a microprocessor or any suitable programmable device. Pumping devices 68, 70, and 72 may also be positioned in communication with one or more controllers. The controllers may be configured to regulate pumping devices 68, 70, and 72 based on information received from flow meters 74, 76, and 78, pressure monitoring devices 80, 82, and 84, and / or temperature monitoring devices 81, 83, and 85. In this way, the foamed fiber suspension can be fed into each forming zone 50, 52, and 54 at a desired flow rate and / or pressure within a desired set point for optimizing the formation of the web on the forming surface 26.

[0056] Information received from flow meters 74, 76, and 78, from pressure monitoring devices 80, 82, and 84, and / or from temperature monitoring devices 81, 83, and 85 can be used to determine the characteristics of the foamed fiber suspension at the measurement location. Additionally, the density of the foamed fiber suspension can be measured or calculated based on information received from various instruments. In one embodiment, this information can be transmitted to a controller for calculating at least one characteristic of the foamed fiber suspension at the forming surface. Specifically, the controller can be programmed to correct for a determined volumetric flow rate at the forming surface based on changes in density, pressure, and temperature. For example, when the foamed suspension is ejected from a supply line onto the forming surface, the foamed suspension may experience a pressure drop that changes the density of the foamed suspension. For example, a method for calculating downstream values ​​of a foamed suspension is disclosed in U.S. Patent 4,764,253, which is incorporated herein by reference.

[0057] like Figure 2 As shown, a first discharge device 86, fluidly connected to a first discharge line 92, may be located opposite the first forming region 50 along the forming surface 26. A second discharge device 88, fluidly connected to a second discharge line 94, may be located opposite the second forming region 52. Similarly, a third discharge device 90, connected to a third discharge line 96, may be located opposite the third forming region 54. The first forming region 50, the second forming region 52, and the third forming region 54 may be adjacent to each other along the forming surface 26 and may be positioned on one side of the forming surface 26. The discharge devices 86, 88, and 90 may also be adjacent to each other and may be positioned on the opposite sides of the forming surface 26 aligned with the forming regions 50, 52, and 54. When the foamed fiber suspension is deposited from each forming region 50, 52, and 54 onto the forming surface, a web 14 may be formed, and excess fluid may enter the corresponding discharge devices 86, 88, and 90. The discharge device may be any suitable static or dynamic discharge device capable of discharging fluid from the web or from the forming surface. The discharge device may be a static suction box or a static vacuum box. Alternatively, the discharge device can be a roller, such as a rotating roller that applies suction.

[0058] like Figure 2As shown, each discharge line 92, 94, and 96 may include a corresponding flow control device, flow meter, temperature monitoring device, and pressure monitoring device. For example, the first discharge line 92 may include a first flow control device 98, a first flow meter 104, a first temperature monitoring device 105, and a first pressure monitoring device 110; the second discharge line 94 may include a second flow control device 100, a second flow meter 106, a second temperature monitoring device 107, and a second pressure monitoring device 112; and the third discharge line 96 may include a third flow control device 102, a third flow meter 108, a third temperature monitoring device 109, and a third pressure monitoring device 114. The flow control devices 98, 100, and 102 may be any suitable device for controlling the flow through the lines and may be adjustable valves or pumps. For example, a pump may be used to apply suction to a shaped surface. Alternatively, discharge may occur by gravity. In yet another example embodiment, each flow control device 98, 100, and 102 may be a combination of a pump and an adjustable valve.

[0059] In one example implementation, system 10 may also include one or more controllers 116. Controller 116 may include a microprocessor or any suitable programmable device. Figure 2 As shown, each flow control device 98, 100, and 102, each flow meter 104, 106, and 108, each temperature monitoring device 105, 107, and 109, each density monitoring device, and / or each pressure monitoring device 110, 112, and 114 can communicate with the controller 116. The controller 116 can receive information from the flow meters 104, 106, and 108, the temperature monitoring devices 105, 107, and 109, the optional density monitoring devices, and / or the pressure monitoring devices 110, 112, and 114 for regulating the flow control devices 98, 100, and 102 to control the flow rate of fluid discharged from each of the discharge devices 86, 88, and 90. A combination of information received from flow control devices 98, 100, and 102 (which may be volumetric flow meters), pressure monitoring devices 110, 112, and 114, temperature monitoring devices 105, 107, and 109, and / or optional density monitoring devices can be used to quantify fluid discharge flows containing both gas and liquid. In one example embodiment, controller 116 can use the aforementioned information to calculate the flow rate (e.g., volumetric flow rate) at the forming surface and control the volumetric flow rate based on at least one characteristic of the foamed suspension fed to the forming surface. Controller 116 can then control flow control devices 98, 100, and 102 to achieve the calculated discharge flow rate through each discharge device and discharge line.

[0060] In example embodiments, the process and system of this disclosure may further include a sealing region 120 positioned along the shaped fabric 26 and in fluid communication with a sealing fluid supply line 122. For example... Figure 2 As shown, the sealing fluid supply line 122 may include a pumping device 124, a flow meter 126, a pressure monitoring device 128, and a temperature monitoring device 129. The sealing fluid supply line 122 is used to feed fluid, particularly a liquid, into the sealing zone 120. The sealing fluid can be any suitable liquid. For example, the sealing fluid can be water, water, and surfactant solutions, etc. In one example embodiment, the sealing fluid may be non-fibrous. The sealing fluid may be fed into the sealing fluid zone 120 at a certain flow rate and / or pressure, such that the sealing fluid deposited on the forming surface 26 forms a fluid seal that prevents airflow in the upstream longitudinal direction. Information received from the flow meter 126, the pressure monitoring device 128, the temperature monitoring device 129, and the optional density monitoring device can be used to calculate the volumetric flow rate of the foam at the forming surface.

[0061] like Figure 2 As shown, the sealing region 120 can be positioned upstream of and adjacent to a plurality of forming regions. The sealing region 120 can also be positioned opposite a sealing discharge device 130 connected to a sealing discharge line 132. The sealing discharge line 132 may include a flow control device 134, a flow meter 136, a temperature monitoring device 137, and a pressure sensing device 138, all of which can communicate with the controller 116. In this way, the discharge rate of the sealing fluid can be controlled based on the flow rate or pressure of the sealing fluid entering or leaving the sealing region 120. By including the sealing region 120, the web 14 is better formed opposite to the first forming region 50.

[0062] like Figure 2 The illustrated web forming system 10 may further include a suction zone 140 adjacent to and positioned downstream of multiple forming zones. The suction zone 140 may be in fluid communication with a discharge line 142, which may include a pressure monitoring device 144. The suction zone 140 is used to suction fluid from the initial web 14 after web forming. The suction zone 140 is used to remove excess fluid, particularly liquids, from the web 14. In one aspect, the discharge flow rate of the foamed fiber suspension discharged through one or more discharge devices may be controlled so that excess fluid from one or more forming zones enters the suction zone 140. Ideally, the suction zone 140 facilitates the removal of fluid from the web 14 without causing any harmful effects.

[0063] like Figure 2As shown, all discharge lines 92, 94, 96, 132, and 142 can be fed into separator 150. Separator 150 can be configured to separate free gas from foam. As shown, separator 150 may include a gas outlet 152 and a liquid outlet 154 that can be connected to a vacuum source. The liquid collected in separator 150 may include a mixture of water and surfactant. Figure 2 As shown, pumping device 156 can be used to pump liquid from separator 150 to liquid tank 158, which can also be connected to water source 160. Liquid tank 158 can be used to recycle the water and surfactant mixture back into the process via supply lines 56, 58, 60 and 122.

[0064] See back Figure 1 After the initial web 14 is formed from the web forming system or headbox 10, the web 14 can be fed into various downstream processes. Figure 1 This illustration only shows one example embodiment of the process for drying the web 14 after formation. As shown, the web 14 is formed on the forming surface 26 and conveyed downstream. For example, the annularly traveling formed fabric 26 can be supported and driven by rollers 28.

[0065] Once formed on the shaped fabric 26, the consistency of the shaped web 14 can be less than about fifty percent (50%), such as less than about twenty percent (20%), such as less than about ten percent (10%), such as less than about five percent (5%). In fact, the forming consistency can be less than about two percent (2%), such as less than about one hundred and eight percent (1.8%), such as less than about one hundred and five percent (1.5%). The forming consistency is generally greater than about five percent (0.5%), such as greater than about eight percent (0.8%).

[0066] Once a wet web 14 is formed on the shaped fabric 26, the web 14 is conveyed downstream and optionally further dehydrated. For example, the method may optionally include multiple vacuum devices 16, such as vacuum chambers and vacuum rollers. Vacuum chambers help remove moisture from the newly formed web 14.

[0067] like Figure 1 As shown, the shaped fabric 26 can also be positioned in communication with a steam box 18 located above a pair of vacuum rollers 20. The steam box 18 can, for example, significantly increase dryness and reduce transverse moisture variation. The steam applied from the steam box 18 heats the moisture in the wet web 14, making it easier for water to drain from the web, especially when combined with the vacuum rollers 20. The newly formed web 14 is conveyed downstream from the shaped fabric 26 and dried. Any suitable drying device can be used to dry the web 14. For example, the web 14 can be air-dried or placed on heated drying rollers and wrinkled or unwrinkled. For example, in Figure 1In this process, the shaped web 14 comes into contact with two heated drying rollers 38 and 40. In one example embodiment, the web 14 can be fed from the drying rollers 38 and 40 into a ventilated dryer before being wound into a roll.

[0068] Figure 2 The embodiments described herein are used to form multilayer webs. In another aspect, the method disclosed herein can be used to form single-layer webs from a foamed suspension of materials.

[0069] Now go to Figure 3 This illustration shows a system 200 according to an example embodiment of the present disclosure for separating and managing foam from free air, for example, during foam forming of a nonwoven web. It will be understood that system 200 can be used in or in conjunction with any foam forming system or method for forming a web from a foamed suspension of fibers. For example, system 200 can be used in... Figure 1 and Figure 2 The examples shown and used in or with the example systems and methods described above are therefore used in the following text. Figure 1 and Figure 2 System 200 is described in more detail within the context of the example systems and methods shown. However, it will be understood that, in alternative example embodiments, system 200 may be used in or in conjunction with other systems and methods for forming webs from foamed suspensions of fibers.

[0070] like Figure 3 As shown, system 200 includes a separator 210 and a tank 230. The separator 210 may be located in a headbox (such as web forming system 10). Figure 1 The separator 210 is located between the headbox and tank 230. Furthermore, the separator 210 can be arranged along the flow path for foam between the headbox and tank 230. Therefore, the separator 210 can receive foam flowing from the headbox to tank 230. The separator 210 can be configured to separate free gas from the foam within the separator 210. The headbox and separator 210 can be connected via pipes, conduits, or conduits.

[0071] Separator 210 may include an inlet 220, a first outlet 222, and a second outlet 224. Inlet 220 may be in fluid communication with a headbox, and the foam flow FF may enter separator 210 through inlet 220. As shown, in an example embodiment, separator 210 may include multiple inlets 220. Each inlet of inlet 220 may be connected to discharge lines 92, 94, 96, 132, and 142 (…). Figure 2The corresponding discharge line in the web forming system 10 is connected and fluidly communicated. Therefore, foam from various parts of the web forming system 10 can enter the separator 210 via a corresponding inlet in inlet 220. In other example embodiments, two or more foam streams from the web forming system 10 can be combined upstream of the separator 210 and enter the separator 210 via a single inlet.

[0072] The first outlet 222 can be in fluid communication with the tank 230, and the foam flow FF can exit the separator 210 through the first outlet 222. Therefore, the foam flow FF can pass through the first outlet 222 on the flow path for foam between the headbox and the tank 230. The second outlet 224 can be in fluid communication with the vacuum source 270, and the free air flow FA can exit the separator 210 through the second outlet 224. Furthermore, the vacuum source 270 can be operated to generate a vacuum within the internal volume 216 of the separator 210. The vacuum within the internal volume 216 of the separator 210 can extract and remove large air bubbles from the foam in the separator 210. The free air from the large air bubbles can then exit the separator 210 through the second outlet 224. In contrast, the air entrained within the foam as dispersed bubbles can be retained within the foam flow FF and exit the separator 210 through the first outlet 222.

[0073] As noted above, separator 210 can be configured to remove free air from the foam flow FF passing through separator 210 between headbox and tank 230. Gravity can facilitate the separation of free air from foam within separator 210. Furthermore, relatively dense foam can settle toward the bottom portion 212 of separator 210, and relatively less dense free air can rise toward the top portion 214 of separator 210 with the aid of a vacuum within the internal volume 216 of separator 210. To aid in the separation of free air from the foam flow FF, a first outlet 222 and a second outlet 224 can be spaced apart on separator 210. For example, separator 210 can extend, for example, in a vertical direction V between the bottom portion 212 and the top portion 214. The first outlet 222 can be located at the bottom portion 212 of separator 210, and the second outlet 224 can be located at the top portion 214 of separator 210. Therefore, for example, the first outlet 222 and the second outlet 224 may be spaced apart in the vertical direction V on the separator 210 and / or positioned opposite each other in the vertical direction V on the separator 210. Furthermore, the first outlet 222 may be positioned to receive relatively dense foam settling toward the bottom portion 212 of the separator 210, and the second outlet 224 may be positioned to receive relatively less dense free air rising toward the top portion 214 of the separator 210. The inlet 220 may be positioned, for example, in the vertical direction V between the first outlet 222 and the second outlet 224. Thus, the foam flow FF may enter the internal volume 216 of the separator 210 between the first outlet 222 and the second outlet 224 and / or at the middle portion of the separator 210.

[0074] Tank 230 can be in fluid communication with separator 210. Furthermore, the foam flow FF can exit separator 210 through first outlet 222 and flow into tank 230. Separator 210 and tank 230 can be connected via pipes, conduits, or other conduits. Water, surfactants, or other fluids can be added to the foam within tank 230. Tank 230 can also be connected to a headbox (e.g., web forming system 10). Figure 2Fluid communication allows the foam in tank 230 to be reintroduced into the headbox for nonwoven web foam forming at the headbox. Therefore, tank 230 can be configured to recycle the foam stream FF back into the foam forming process. Tank 230 and the headbox can be connected via piping, conduit, or other means. In some example embodiments, the internal volume 232 of tank 230 may be adjacent to the ambient atmosphere. Therefore, for example, during operation of system 200, the pressure within the internal volume 232 of tank 230 may be greater than the vacuum within the internal volume 216 of separator 210. In example embodiments, the internal volume 232 of tank 230 may be adjacent to the ambient atmosphere via valve 234. In other example embodiments, the top portion of tank 230 may include an opening or other connection to the ambient atmosphere. The internal volume 232 of tank 230 may be larger than the internal volume 216 of separator 210. For example, the internal volume 232 of tank 230 can be no less than twice (2X), no less than five times (5X), or no less than ten times (10X) the internal volume 216 of separator 210.

[0075] System 200 also includes a feature for maintaining the liquid level LF of the foam in separator 210. For example... Figure 3 As shown, system 200 includes pump 240 and sensor 250. Pump 240 can be positioned along a flow path for foam between headbox and tank 230. For example, pump 240 can be positioned downstream of first outlet 222, for example, between separator 210 and tank 230. Pump 240 can be operated to allow foam to flow out of the internal volume 216 of separator 210 via first outlet 222. Furthermore, during operation of pump 240, foam stream FF can exit separator 210 at first outlet 222. In some example embodiments, pump 240 can be a positive displacement pump, such as a rotary, reciprocating, or linear positive displacement pump. For example, due to the ability of positive displacement pumps to handle viscous fluids more efficiently than centrifugal pumps, using a positive displacement pump can advantageously help pump foam from separator 210 via first outlet 222 during operation of pump 240. Because the foam in foam stream FF can be non-Newtonian, the density and viscosity of the foam in foam stream FF can vary based on location and process. Therefore, when pump 240 is a positive displacement pump, pump 240 may be particularly suitable for pumping foam. However, it will be understood that in alternative example embodiments, pump 240 may be a centrifugal pump.

[0076] Sensor 250 can be operated to determine the level LF of foam in separator 210. For example, sensor 250 can detect and / or measure the height of the level LF of foam within the internal volume 216 of separator 210, for example, along a vertical direction V. The level LF of foam can correspond to the boundary between the foam and free air within the internal volume 216 of separator 210. For example, as noted above, separator 210 can separate free air from the foam within separator 210. The free surface of the top portion 214 of the foam facing separator 210 can correspond to the level LF of foam in separator 210. Sensor 250 can be configured to detect the level LF of foam. As an example, sensor 250 can be a capacitor bar mounted to separator 210 and extending into the internal volume 216 of separator 210. For example, the capacitor bar can be mounted to separator 210 at the top portion 214 and can extend downward along a vertical direction V toward the bottom portion 212 of separator 210. The capacitor bar can detect capacitance changes that vary as a function of the foam level LF in separator 210, and can output a signal corresponding to the foam level LF in separator 210. Other sensors can also be used to detect the foam level LF in separator 210. For example, sensor 250 may include optical sensors, cameras, ultrasonic sensors, radar sensors, etc., configured to sense the foam level LF in separator 210 and output a signal corresponding to the foam level LF in separator 210.

[0077] System 200 may also include a processing device or controller 260 or be operatively in communication with such processing device or controller, which may be generally configured to facilitate the operation of at least a portion of system 200. In this regard, pump 240, sensor 250, and other components of system 200 may communicate with controller 260. Thus, for example, controller 260 may receive input from sensor 250 and may regulate the operation of pump 260 at least in part based on the input from sensor 250. Pump 240, sensor 250, and other components of system 200 may communicate with controller 260 via, for example, one or more signal lines or a shared communication bus. In this way, input / output (“I / O”) signals may be routed between controller 260 and various operating components of system 200.

[0078] As used herein, the terms “processing device,” “computing device,” “controller,” etc., can generally refer to any suitable processing device, such as a general-purpose or special-purpose microprocessor, microcontroller, integrated circuit, application-specific integrated circuit (ASIC), digital signal processor (DSP), field-programmable gate array (FPGA), logic device, one or more central processing units (CPU), graphics processing units (GPUs), processing units performing other specialized calculations, semiconductor devices, etc. Furthermore, these “controllers” are not necessarily limited to a single element, but can include any suitable number, type, and configuration of processing devices integrated in any suitable manner to facilitate device operation. Alternatively, controller 260 can be configured to perform control functions without using a microprocessor, for example, using a combination of discrete analog and / or digital logic circuits (such as switches, amplifiers, integrators, comparators, flip-flops, AND / OR gates, etc.), rather than relying on software.

[0079] Controller 260 may include or be associated with one or more memory elements or non-transitory computer-readable storage media, such as RAM, ROM, EEPROM, EPROM, flash memory devices, disks, or other suitable memory devices (including combinations thereof). These memory devices may be components separate from the processor or may be included on-board within the processor. Additionally, these memory devices may store information and / or data accessible by one or more processors, including instructions executable by one or more processors. It should be understood that the instructions may be software written in any suitable programming language or may be implemented in hardware. Alternatively or additionally, instructions may be executed logically and / or virtually using independent threads on one or more processors.

[0080] For example, controller 260 can be operated to execute programming instructions or microcontroller code associated with the operating cycle of system 200. In this regard, the instructions can be software or any set of instructions that, when executed by a processing device, cause the processing device to perform operations such as running one or more software applications, adjusting operating parameters of pump 240, etc. Furthermore, it should be noted that controller 260, as disclosed herein, is capable of and can be operated to perform any methods, method steps, or portions of methods disclosed herein. For example, in some example embodiments, the methods disclosed herein can be embodied in programming instructions stored in memory and executed by controller 260.

[0081] The memory device may also store data that can be retrieved, manipulated, created, or stored by one or more processors or portions of the controller 260. This data may include, for example, data that facilitates the execution of the methods described herein. The data may be stored locally (e.g., on the controller 260) in one or more databases and / or may be segmented such that the data is stored in multiple locations. Alternatively or additionally, one or more databases may be connected to the controller 260 via any suitable network, such as a high-bandwidth local area network (LAN) or wide area network (WAN). In this regard, for example, the controller 260 may also include a communication module or interface that can be used, for example, via any suitable communication line or network and using any suitable communication protocol, to communicate with one or more other components of the system 200, the controller 260, or any other suitable device. The communication interface may include any suitable component for interfacing with one or more networks, including, for example, a transmitter, receiver, port, controller, antenna, or other suitable component.

[0082] Controller 260 can be configured to control the operation of pump 240 to maintain the foam level LF within separator 210. For example, controller 260 can receive a signal from sensor 250 corresponding to the foam level LF in separator 210. Based at least in part on the foam level LF in separator 210, controller 260 can operate pump 240 to maintain the foam level LF within separator 210 within a defined range. As an example, controller 260 can adjust the operation of pump 240 to increase the flow rate of foam stream FF from separator 210 in response to a detected foam level LF from sensor 250 being greater than a defined range R. Conversely, controller 260 can adjust the operation of pump 240 to decrease the flow rate of foam stream FF from separator 210 in response to a detected foam level LF from sensor 250 being less than a defined range R. The defined range R can be selected to limit or prevent excessive and / or insufficient foam discharge from separator 210. For example, the lower limit of the determined range R can be positioned vertically above the first outlet 222, and the upper limit of the determined range R can be positioned vertically below the second outlet 224. As a specific example, the lower limit of the determined range R can be positioned vertically at least 25 cm above the first outlet 222, and the upper limit of the determined range R can be positioned vertically at least 25 cm below the second outlet 224. This spacing can advantageously help limit or prevent excessive and / or insufficient discharge of foam from the separator 210. In example embodiments, the determined range R can be less than 50 cm, less than 25 cm, less than 10 cm, etc., vertically. This setting of the determined range R can help provide a consistent residence time for the foam in the separator 210 during operation of the system 200.

[0083] like Figure 3 As shown, system 200 may also include an auxiliary pump 280. The auxiliary pump 280 may be located downstream of tank 230. The auxiliary pump 280 can be operated to flow foam from tank 230 to a headbox (e.g., web forming system 10). Figure 2 In the example embodiment, the auxiliary pump 280 may include a fan-type pump. By maintaining the foam level LF within the defined range R, the auxiliary pump 280 can operate with improved efficiency and stability. Furthermore, in the example embodiment, since the pump 240 maintains the foam level LF within the defined range R, the auxiliary pump 280 may not require vacuum assistance.

[0084] Figure 4A method 400 for foam forming according to an example embodiment of this subject is shown. As an example, method 400 can be used in system 200 ( Figure 3 This method can be used in or with the system to help maintain the foam level within the vacuum separator. The controller 260 of system 200 can be programmed or configured to implement method 400. Although method 400 is described in more detail below in the context of system 200, it will be understood that, in alternative example embodiments, method 400 can be used in or within any suitable system or process.

[0085] At 410, foam can be released from the headbox (such as web forming system 10). Figure 2 The fluid flows to a vacuum separator (such as separator 210). Figure 3 Therefore, the foam flow FF can enter the separator 210 at 410. At 420, the free air from the foam can exit the vacuum separator, for example, via the second outlet 224.

[0086] At 430, the foam level in the vacuum separator can be determined. For example, sensor 250 can detect and / or measure the foam level LF within the internal volume 216 of separator 210 at 430, and sensor 250 can output a signal corresponding to the foam level LF. At 440, the foam level LF can be compared with a determined range. For example, controller 260 can compare the determined foam level LF from sensor 250 with a determined range.

[0087] Method 400 may further include controlling pump operation based on a comparison of the foam level with a defined range. For example, at 450, when the detected foam level is outside the defined range, pump operating parameters may be adjusted to change the flow rate of foam from the vacuum separator. In some example embodiments, at 450, when the detected foam level LF from sensor 250 is greater than the defined range R, controller 260 may increase the operating speed of pump 240 to increase the flow rate of foam stream FF from separator 210. Conversely, in such example embodiments, when the detected foam level LF from sensor 250 is less than the defined range R, controller 260 may decrease the operating speed of pump 240 at 450 to decrease the flow rate of foam stream FF from separator 210. At 460, when the detected foam level is within the defined range, pump operating parameters may be maintained or kept constant to maintain the flow rate of foam from the vacuum separator. In some example implementations, at 460, when the detected level LF of foam from sensor 250 is within the defined range R, controller 260 can maintain the operating speed of pump 240 in order to keep the flow rate of foam stream FF from separator 210 constant.

[0088] In the example implementation, the average residence time of the foam in the vacuum separator can be substantially constant during method 400. Therefore, for example, during method 400, the average residence time of the foam in separator 210 can vary to less than one minute (1 min), less than thirty seconds (30 s), less than ten seconds (10 s), etc. This consistent residence time can advantageously improve the stability of the foam during method 400.

[0089] During method 400, the interior of the vacuum separator can be under vacuum. Therefore, for example, vacuum source 270 can operate during method 400 to create a vacuum within the internal volume 216 of separator 210, thereby extracting and removing large bubbles from the foam within separator 210. During method 400, the internal volume of the return tank receiving the foam stream from the vacuum separator can be adjacent to the ambient atmosphere. Therefore, for example, during method 400, when the foam stream FF leaves separator 210 and flows into tank 230, the internal volume 232 of tank 230 can be adjacent to the ambient atmosphere.

[0090] Figure 4 The steps performed in a specific order are described for illustrative and discussion purposes. Using the disclosure provided herein, those skilled in the art will understand that the steps of any method discussed herein can be adapted, rearranged, extended, omitted, or modified in various ways without departing from the scope of this disclosure.

[0091] These and other modifications and variations of the invention may be practiced by those skilled in the art without departing from the spirit and scope of the invention as more specifically described in the appended claims. Furthermore, it should be understood that aspects of the various embodiments may be interchanged, in whole or in part. Moreover, those skilled in the art will appreciate that the above description is merely illustrative and is not intended to limit the invention further described in the appended claims.

[0092] Example Implementation Plan

[0093] First example embodiment: A foam forming system, comprising: a headbox; a tank; a separator disposed between the headbox and the tank along a flow path for foam, the separator including an inlet for the foam, a first outlet for the foam, and a second outlet for free air from the foam; a pump; a sensor operable to determine a level of the foam in the separator; and a controller configured to receive from the sensor a signal corresponding to the level of the foam in the separator, and to operate the pump at least in part based on the level of the foam in the separator to maintain the level of the foam within the separator within a determined range.

[0094] Second example implementation: The foam forming system as described in the first example implementation further includes an additional pump disposed downstream of the tank in a flow path for foam between the tank and the headbox, the additional pump being operable to cause the foam to flow along the flow path between the headbox and the tank.

[0095] Third example implementation: A foam forming system as described in the second example implementation, wherein the additional pump includes a fan pump.

[0096] Fourth example implementation: A foam forming system as described in any one of the first to third example implementations, wherein the inlet is disposed vertically between the first outlet and the second outlet.

[0097] Fifth example implementation: A foam forming system as described in any one of the first to fourth example implementations, wherein the first outlet is located at the bottom portion of the separator and the second outlet is located at the top portion of the separator.

[0098] Sixth Example Implementation: The foam forming system as described in any one of the first to fifth example implementations further includes a vacuum source connected to the separator via a second outlet of the separator, the vacuum source being operable to generate a vacuum within the internal volume of the separator.

[0099] Seventh Example Implementation: A foam forming system as described in the sixth example implementation, wherein the internal volume of the tank is adjacent to the ambient atmosphere.

[0100] Eighth Example Implementation: A foam forming system as described in any one of the first to seventh example implementations, wherein the pump includes a positive displacement pump.

[0101] Ninth Example Implementation: A foam forming system as described in any one of the first to eighth example implementations, wherein the sensor includes a capacitive rod.

[0102] Tenth Example Implementation: A foam forming system as described in any one of the first to ninth example implementations, wherein the volume of the tank is greater than the volume of the separator.

[0103] Eleventh Example Implementation: A foam forming system comprising: a tank; a vacuum separator including an inlet for foam, a first outlet for the foam, and a second outlet for free air from the foam, the vacuum separator being coupled to the tank via the first outlet such that the foam can flow from the vacuum separator to the tank; a pump operable to cause the foam to flow from the vacuum separator to the tank; a sensor operable to determine a level of the foam in the vacuum separator; and a controller configured to determine the level of the foam in the vacuum separator based at least in part on a signal from the sensor, and to operate the pump based at least in part on the determined level of the foam in the vacuum separator to maintain the level of the foam within the vacuum separator within a determined range.

[0104] Twelfth Example Implementation: The foam forming system of the eleventh example implementation further includes an additional pump disposed downstream of the tank, the additional pump being operable to cause the foam to flow from the tank.

[0105] Thirteenth Example Implementation: A foam forming system as described in the eleventh or twelfth example implementation, wherein the inlet is disposed vertically between the first outlet and the second outlet.

[0106] Fourteenth Example Implementation: A foam forming system as described in any one of the eleventh to thirteenth example implementations, wherein the first outlet is located at the bottom portion of the vacuum separator, and the second outlet is located at the top portion of the vacuum separator.

[0107] Fifteenth Example Implementation: The foam forming system as described in any one of the eleventh to fourteenth example implementations further includes a vacuum source connected to the vacuum separator via a second outlet of the vacuum separator, the vacuum source being operable to generate a vacuum within the internal volume of the vacuum separator.

[0108] Sixteenth Example Implementation: A foam forming system as described in Fifteenth Example Implementation, wherein the internal volume of the tank is adjacent to the ambient atmosphere.

[0109] Seventeenth Example Implementation: A method for foam forming, comprising: flowing foam from a headbox to a vacuum separator; allowing free air from the foam to exit the vacuum separator through a vacuum outlet; and operating a pump to allow the foam to exit the vacuum separator through a foam outlet, wherein operating the pump includes using a sensor to determine the level of the foam in the vacuum separator, and adjusting the flow rate of the pump, at least in part, based on the determined level of the foam in the vacuum separator, to maintain the level of the foam within the vacuum separator within a determined range.

[0110] Eighteenth Example Implementation: The method described in the seventeenth example implementation, wherein the interior of the vacuum separator is under vacuum.

[0111] Nineteenth Example Implementation: The method described in the seventeenth or eighteenth example implementation, wherein the residence time of the foam in the vacuum separator is substantially constant.

Claims

1. A foam forming system, comprising: headbox; Can; A separator is disposed between the headbox and the tank along a flow path for foam, the separator including an inlet for the foam, a first outlet for the foam, and a second outlet for free air from the foam; Pump; A sensor, operable to determine the level of the foam in the separator; as well as Controller, the controller is configured to The sensor receives a signal corresponding to the liquid level of the foam in the separator, and The pump is operated at least in part based on the level of the foam in the separator to maintain the level of the foam within the separator within a defined range.

2. The foam forming system of claim 1, further comprising an additional pump disposed downstream of the tank in a flow path for foam between the tank and the headbox, the additional pump being operable to cause the foam to flow along the flow path between the headbox and the tank.

3. The foam forming system of claim 2, wherein the additional pump comprises a fan pump.

4. The foam forming system according to any one of claims 1 to 3, wherein the inlet is disposed vertically between the first outlet and the second outlet.

5. The foam forming system of any one of claims 1 to 4, wherein the first outlet is located at the bottom portion of the separator, and the second outlet is located at the top portion of the separator.

6. The foam forming system of any one of claims 1 to 5, further comprising a vacuum source connected to the separator via a second outlet of the separator, the vacuum source being operable to generate a vacuum within the internal volume of the separator.

7. The foam forming system of claim 6, wherein the internal volume of the tank is adjacent to the ambient atmosphere.

8. The foam forming system of any one of claims 1 to 7, wherein the pump comprises a positive displacement pump.

9. The foam forming system of any one of claims 1 to 8, wherein the sensor comprises a capacitor rod.

10. The foam forming system of any one of claims 1 to 9, wherein the volume of the tank is greater than the volume of the separator.

11. A foam forming system, comprising: Can; A vacuum separator, comprising an inlet for foam, a first outlet for the foam, and a second outlet for free air from the foam, the vacuum separator being coupled to the tank via the first outlet such that the foam can flow from the vacuum separator into the tank; A pump, operable to cause the foam to flow from the vacuum separator to the tank; A sensor, operable to determine the level of the foam in the vacuum separator; as well as Controller, the controller is configured to The level of the foam in the vacuum separator is determined at least in part based on signals from the sensor, and The pump is operated at least in part based on a determined level of the foam in the vacuum separator to maintain the level of the foam within the vacuum separator within a determined range.

12. The foam forming system of claim 11, further comprising an additional pump disposed downstream of the tank, the additional pump being operable to cause the foam to flow from the tank.

13. The foam forming system of claim 11 or claim 12, wherein the inlet is disposed vertically between the first outlet and the second outlet.

14. The foam forming system of any one of claims 11 to 13, wherein the first outlet is located at the bottom portion of the vacuum separator, and the second outlet is located at the top portion of the vacuum separator.

15. The foam forming system of any one of claims 11 to 14, further comprising a vacuum source connected to the vacuum separator via a second outlet of the vacuum separator, the vacuum source being operable to generate a vacuum within the internal volume of the vacuum separator.

16. The foam forming system of claim 15, wherein the internal volume of the tank is adjacent to the ambient atmosphere.

17. A method for foam molding, comprising: The foam is then directed from the headbox to the vacuum separator. Free air from the foam is allowed to flow out of the vacuum separator through the vacuum outlet. as well as Operate the pump to allow the foam to flow out of the vacuum separator through the foam outlet. Operating the pump includes using a sensor to determine the level of the foam in the vacuum separator, and adjusting the flow rate of the pump, at least in part, based on the determined level of the foam in the vacuum separator, to maintain the level of the foam within the vacuum separator within a determined range.

18. The method of claim 17, wherein the interior of the vacuum separator is in a vacuum state.

19. The method of claim 17 or 18, wherein the residence time of the foam in the vacuum separator is substantially constant.

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