A particulate feeder for foam forming

Abstract

A process and system for adding particulate material to a flow of foam to a headbox. A particulate material feeder includes a supply chamber fillable with particulate material, a supply hopper, and an airlock valve disposed between the supply chamber and the supply hopper. The particulate material in the supply chamber is flowable into the supply hopper when the airlock valve is open. A pressure supply line coupled to the supply chamber and configured for flowing air into and / or from the supply chamber.

Description

[0001] A PARTICULATE FEEDER FOR FOAM FORMING

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application is related and claims right of priority to U.S. Provisional Application No. 63 / 601 ,350, which was filed in the United States Patent & Trademark Office on November 21 , 2023 and is incorporated by reference in its entirety.

[0004] BACKGROUND

[0005] Many tissue products, such as facial tissue, bath tissue, paper towels, industrial wipers, and the like, are produced according to a wet laid process. Wet laid webs are made by depositing an aqueous suspension of pulp fibers onto a forming fabric and then removing water from the newly- formed web.

[0006] In order to improve various characteristics of tissue webs, webs have also been formed according to a foam forming process. During a foam forming process, a foamed suspension of fibers is created and spread onto a moving porous conveyor for producing an embryonic web. Foam formed webs can demonstrate improvements in bulk, stretch, caliper, and / or absorbency. In addition to tissue webs, foam forming can be used to make all different types of webs and products. For example, relatively long fibers and synthetic fibers can be incorporated into webs using a foam forming process. Thus, foam forming processes can be more versatile than many wet laid processes.

[0007] In certain conventional foam forming systems, superabsorbent material is added to the foam prior to the headbox. Adding superabsorbent material to the foam can be challenging. For instance, air can be entrained into the foam in addition to the superabsorbent material, which can negatively affect performance of the foam in the headbox.

[0008] A system for improved introduction of superabsorbent material into foam would be useful.

[0009] SUMMARY

[0010] In general, the present disclosure is directed to an improved process and system for adding particulate material to a flow of foam to a headbox. A pump, such as an eductor, may draw the particulate material, such as superabsorbent material, into the flow of foam to the headbox. To limit the air entrained into the foam by the vacuum generated by the pump, a particulate material feeder assembly positioned upstream of the headbox on a flow path for the foam to the headbox includes an airlock valve between a supply chamber and a supply hopper. Particulate material within the supply chamber may flow from the supply chamber into the supply hopper when the airlock valve is open, and the airlock valve may block airflow between the supply chamber and the supply hopper when the airlock valve is closed. Thus, the airlock valve may selectively seal the supply hopper to limit available air in the supply hopper for entrainment into the foam. A pressure supply line, separate from the pump, may also be coupled to the supply chamber. The pressure supply line may draw air from and / or supply air to the supply chamber. Thus, e.g., when the supply chamber is filled with particulate material and the airlock valve is closed, the pressure supply line may evacuate air from the supply chamber in order to limit the air that flows from the supply chamber into the supply hopper when the airlock valve opens to transfer the particulate material from the supply chamber to the supply hopper. The above-described particulate material feeder assembly may advantageously allow for continuous operation of the foam forming process at the headbox by refilling the supply hopper with particulate material, e.g., without introducing significant volumes of air into foam.

[0011] In one example embodiment, a foam forming system includes a headbox and a superabsorbent material feeder assembly positioned upstream of the headbox on a flow path for foam to the headbox. The superabsorbent material feeder assembly is configured for adding superabsorbent material to the foam. The superabsorbent material feeder assembly includes a supply chamber fillable with the superabsorbent material, a supply hopper, and an airlock valve disposed between the supply chamber and the supply hopper. The airlock valve is configured for opening and closing in order to selectively connect the supply chamber and the supply hopper. The superabsorbent material in the supply chamber is flowable into the supply hopper when the airlock valve is open. A pressure supply line coupled to the supply chamber and configured for flowing air into and / or from the supply chamber.

[0012] In another example embodiment, a particulate material feeder for a foam forming system includes a supply chamber fillable with particulate material, a supply hopper positioned below the supply chamber, and an airlock valve disposed between the supply chamber and the supply hopper. The airlock valve is configured for opening and closing in order to selectively connect the supply chamber and the supply hopper. The particulate material in the supply chamber is flowable into the supply hopper when the airlock valve is open. A pressure supply line coupled to the supply chamber and configured for flowing air into and / or from the supply chamber.

[0013] In another example embodiment, a method for feeding particulate material within a foam forming process includes flowing superabsorbent material to a supply chamber, removing air from the supply chamber, opening an airlock valve between the supply chamber and a supply hopper such that the superabsorbent material transfers from the supply chamber to the supply hopper, and metering the superabsorbent material into a flow of foam to a headbox.

[0014] Other features and aspects of the present disclosure are discussed in greater detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A full and enabling disclosure of the present disclosure is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

[0016] FIG. 1 is a schematic view of a system and process according to an example embodiment of the present disclosure for forming webs from a foamed suspension of materials;

[0017] FIG. 2 is a schematic view of a system and process according to an example embodiment of the present disclosure for depositing a foamed suspension of materials onto a forming surface in accordance with the present disclosure;

[0018] FIG. 3 is a schematic view of a system and process according to an example embodiment of the present disclosure for feeding superabsorbent material during foam forming of a non-woven web; and

[0019] FIG. 4 is a flow diagram of a process according to an example embodiment of the present disclosure for feeding superabsorbent material during foam forming of a non-woven web.

[0020] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

[0021] DEFINITIONS

[0022] When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a", “an”, “the” and “said” are intended to mean that there are one or more of the elements. As used herein, the terms “includes” and “including” are 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”). Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. For example, the approximating language may refer to being within a ten percent (10%) margin.

[0023] As used herein, the term “foam formed product” means a product formed from a suspension including a mixture of a solid, a liquid, and dispersed gas bubbles.

[0024] As used herein, the term “foam forming process” means a process for manufacturing a product involving a suspension including a mixture of a solid, a liquid, and dispersed gas bubbles. As used herein, the term “foaming fluid” means any one or more known fluids compatible with the other components in the foam forming process. Suitable foaming fluids include, but are not limited to, water.

[0025] As used herein, the term “foam half life” means the time elapsed until the half of the initial foam mass reverts to liquid water.

[0026] As used herein, the term “layer” refers to a structure that provides an area of a substrate in a height direction of the substrate that is comprised of similar components and structure.

[0027] As used herein, the term "nonwoven web" means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted web.

[0028] As used herein, unless expressly indicated otherwise, when used in relation to material compositions the terms "percent", “%”, "weight percent", or "percent by weight" each refer to the quantity by weight of a component as a percentage of the total except as whether expressly noted otherwise.

[0029] The term “personal care absorbent article” refers herein to an article intended and / or adapted to be placed against or in proximity to the body (i.e., contiguous with the body) of the wearer to absorb and contain various liquid, solid, and semi-solid exudates discharged from the body. Examples include, but are not limited to, diapers, diaper pants, training pants, youth pants, swim pants, feminine hygiene products, including, but not limited to, menstrual pads or pants, incontinence products, medical garments, surgical pads and bandages, and so forth.

[0030] The term "superabsorbent material" as used herein refers to water-swellable, water-insoluble organic or inorganic materials including superabsorbent polymers and superabsorbent polymer compositions capable, under the most favorable conditions, of absorbing at least about ten times (1 OX) their weight, or at least about fifteen times (15X) their weight, or at least about twenty-five times (25X) their weight in an aqueous solution containing nine-tenths (0.9) weight percent sodium chloride.

[0031] The term "machine direction" as used herein refers to the direction of travel of the forming surface onto which fibers are deposited during formation of a nonwoven web.

[0032] The term "cross-machine direction" as used herein refers to the direction which is perpendicular to the machine direction defined above.

[0033] The term "pulp" as used herein refers to fibers 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, esparto grass, milkweed, straw, jute, hemp, and bagasse. Pulp fibers may include hardwood fibers, softwood fibers, and mixtures thereof.

[0034] The term "average fiber length" as used herein refers to an average length of fibers, fiber bundles and / or fiber-like materials determined by measurement utilizing microscopic techniques. A sample of at least 20 randomly selected fibers is separated from a liquid suspension of fibers. The fibers are set up on a microscope slide prepared to suspend the fibers in water. A tinting dye is added to the suspended fibers to color cellulose-contain ing fibers so they may be distinguished or separated from synthetic fibers. The slide is placed under a Fisher Stereomaster II Microscope-S19642 / S19643 Series. Measurements of 20 fibers in the sample are made at 20X linear magnification utilizing a 0-20 mils scale and an average length, minimum and maximum length, and a deviation or coefficient of variation are calculated. In some cases, the average fiber length will be calculated as a weighted average length of fibers (e.g . , fibers, fiber bundles, fiber-like materials) determined by equipment such as, for example, a Kajaani fiber analyzer Model No. FS-200, available from Kajaani Oy Electronics, Kajaani, Finland. According to a standard test procedure, a sample is treated with a macerating liquid to ensure that no fiber bundles or shives are present. Each sample is disintegrated into hot water and diluted to an approximately 0.001% suspension. Individual test samples are drawn in approximately 50 to 100 ml portions from the dilute suspension when tested using the standard Kajaani fiber analysis test procedure. The weighted average fiber length may be an arithmetic average, a length weighted average or a weight weighted average and may be expressed by the following equation: where k=maximum fiber length xrfiber length n?=number of fibers having length xi n=total number of fibers measured.

[0035] One characteristic of the average fiber length data measured by the Kajaani fiber analyzer is that it does not discriminate between different types of fibers. Thus, the average length represents an average based on lengths of all different types, if any, of fibers in the sample.

[0036] As used herein the term "staple fibers” means discontinuous fibers made from synthetic polymers such as polypropylene, polyester, post consumer recycle (FOR) fibers, polyester, nylon, and the like, and those not hydrophilic may be treated to be hydrophilic. Staple fibers may be cut fibers or the like. Staple fibers can have cross-sections that are round, bicomponent, multicomponent, shaped, hollow, or the like. DETAILED DESCRIPTION

[0037] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0038] In general, the present disclosure is directed to a system and method for feeding superabsorbent material (or other particulate material) within a foam forming process. To feed the superabsorbent material into a flow of foam to a headbox, a supply hopper may feed superabsorbent material to a metering device that supplies the superabsorbent material into the flow of foam to the headbox. The metering device may be disposed within a sealed casing, e.g., such that an interior of the metering device containing the superabsorbent material is vacuum pressurized to less than atmospheric pressure by a pump, such as an eductor, that injects the superabsorbent material from the metering device into the flow of foam to the headbox. An interior of a supply chamber, which supplies the superabsorbent material to the supply hopper, may also be vacuum pressurized to less than atmospheric pressure. Thus, air may be evacuated from the superabsorbent material fed to the supply hopper in order to limit entrainment of air from the supply hopper into the flow of foam to the headbox. Moreover, an airlock valve may be positioned between the supply chamber and the supply hopper. The airlock valve can allow superabsorbent material to flow from the supply chamber to the supply hopper when the airlock valve is open, and the airlock valve can block airflow from the supply chamber into the supply hopper when the airlock valve is closed. The supply chamber may be connected to a pressure supply line, separate from the pump, that draws air out of the superabsorbent material in the supply chamber and / or supplies air into the superabsorbent material in the supply chamber prior for opening the airlock valve to flow the superabsorbent material from the supply chamber into the supply hopper.

[0039] In certain example embodiments, a first pressure sensor may measure an air pressure in the supply chamber, and a second pressure sensor may measure an air pressure within the supply hopper. A controller may be configured for adjusting the air pressure within the supply chamber based on measurements from the first and second sensors. For instance, the controller may adjust a valve to increase or decrease the flow rate of air into and / or out of the supply chamber through the pressure supply line. As another example, the controller may adjust a valve to increase or decrease a flow rate of motive fluid through a Venturi pump in order to change the air pressure within the supply chamber. The controller may also selectively open and close the airlock valve. For example, the controller may open the valve when a difference between the air pressures within the supply chamber and the supply hopper is less than a threshold value. Thus, e.g., both the supply chamber and the supply hopper may be vacuum pressurized to substantially the same magnitude prior for opening the airlock valve.

[0040] The system and process of the present disclosure can provide various advantages and benefits. For instance, removing air from the superabsorbent material in the supply chamber prior for opening the airlock valve may advantageously limit entrainment of air from the supply hopper into the flow of foam to the headbox. In addition, the headbox may be continuously fed with superabsorbent material without undesired entrainment of air into the flow of foam to the headbox. Thus, stability of the foam may be maintained while continuously feeding superabsorbent material into the flow of foam to the headbox.

[0041] Referring to FIGS. 1 and 2, an example embodiment of a system and process in accordance with aspects of the present disclosure is shown. In general, during the process, solid material, such as fibers and / or superabsorbent particles, water, and a foam forming agent are added to a tank and mixed until the desired air content, bubble size / foam stability, and solid dispersion are achieved, such as a fiber dispersion. The fiber-containing foam may then optionally be diluted during the process, especially when a recycle stream is present. In one example aspect, the air content of the foamed suspension is between about thirty percent (30%) and about sixty-five percent (65%). As will be described below, example aspects of the process and system of the present disclosure are directed to separating foam from free air and managing foam, e.g., during foam forming of a nonwoven web.

[0042] FIG. 1 illustrates a system and process for producing a foamed suspension of fibers and for forming webs from the foamed suspension of fibers. It will be understood that the example system shown in FIG. 1 is provided by way of example and that any suitable web forming system may be used in accordance with the present disclosure. As shown in FIG. 1 , the system may include a mixing tank 12 configured to form the foamed suspension of fibers. The foamed suspension of fibers may then be fed to a headbox or web forming system 10 that deposits the foamed suspension of fibers onto a porous forming surface 26 for forming a web 14. The mixing tank 12 may be in communication with a water supply 22 for feeding water to the tank and a foaming agent or surfactant supply 24 for feeding a surfactant to the tank 12. A fiber furnish may also be fed to the tank 12 and combined with the water and surfactant. The aqueous solution formed by combining the surfactant and water may be agitated and formed into a foam for forming a foamed suspension of fibers. As described above, in addition to fibers, various other materials may be combined in the tank 12. Such other materials, for instance, may include superabsorbent particles or the like.

[0043] The surfactant or foaming agent, for instance, may include any suitable surfactant. In one example embodiment, for instance, the foaming agent may include sodium lauryl sulfate, which is also known as sodium laureth sulfate or sodium lauryl ether sulfate. Other foaming agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other example embodiments, the foaming agent may include any suitable cationic and / or amphoteric surfactant. For instance, other foaming agents include fatty acid amines, amides, amine oxides, fatty acid quaternary compounds, and the like. In one example embodiment, a nonionic surfactant is used. The nonionic surfactant, for instance, may include an alkyl polyglycoside. In one aspect, for instance, the surfactant may be a C8 alkyl polyglycoside, a C10 alkyl polyglycoside, or a mixture of C8 and C10 alkyl polyglycosides.

[0044] The foaming agent may be combined with water generally in an amount greater than about one-tenth of a percent (0.1%) by weight, such as in an amount greater than about half of a percent (0.5%) by weight, such as in an amount greater than about seven-tenths of a percent (0.7%) by weight. One or more foaming agents may generally be present in an amount of from about one- hundredth of a percent (0.01 %) by weight to about five percent (5%) by weight, such as in an amount up to about two percent (2%) by weight.

[0045] When the foaming agent and water are combined, the mixture may be blended or otherwise subjected to forces capable of forming a foam. A foam generally refers is an aggregate of hollow cells or bubbles.

[0046] The foam density can vary depending upon the particular application and various factors including the fiber furnish used. In one example embodiment, for instance, the foam density of the foam may be greater than about two hundred grams per liter (200 g / L), such as greater than about two hundred and fifty grams per liter (250 g / L), such as greater than about three hundred grams per liter (300 g / L). The foam density is generally less than about six hundred grams per liter (600 g / L), such as less than about five hundred grams per liter (500 g / L), such as less than about four hundred grams per liter (400 g / L), such as less than about three hundred and fifty grams per liter (350 g / L). In one example embodiment, for instance, a lower density foam is used having a foam density of generally less than about three hundred and fifty grams per liter (350 g / L), such as less than about three hundred and forty grams per liter (340 g / L), such as less than about three hundred and thirty grams per liter (330 g / L). The foam may generally have an air content of greater than about forty percent (40%), such as greater than about fifty percent (50%), such as greater than about sixty percent (60%), e.g., at standard temperature and pressure (STP). The air content is generally less than about seventy-five percent (75%) by volume, such as less than about seventy percent (70%) by volume, such as less than about sixty-five percent (65%) by volume. The foam may be formed in the presence of a fiber furnish or, alternatively, the foam may first be formed and then combined with a fiber furnish. In general, any fibers capable of making a basesheet, such as a tissue web or other similar type of nonwoven, may be used.

[0047] Fibers suitable for making webs include any natural or synthetic cellulosic fibers including, but not limited to: nonwoody fibers, such as cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss fibers, and pineapple leaf fibers; and woody or pulp fibers, such as those obtained from deciduous and coniferous trees, including softwood fibers, such as northern and southern softwood kraft fibers; hardwood fibers, such as eucalyptus, maple, birch, and aspen. Pulp fibers may be prepared in high-yield or low-yield forms and may be pulped in any known method, including kraft, sulfite, high-yield pulping methods and other known pulping methods. Fibers prepared from organosolv pulping methods may also be used.

[0048] A portion of the fibers, such as up to one hundred percent (100%) or less by dry weight, or from about five percent (5%) to about thirty percent (30%) by dry weight, may be synthetic fibers, such as rayon, polyolefin fibers, polyester fibers, bicomponent sheath-core fibers, multi-component binder fibers, and the like. The fibers may be virgin fibers or recycled fibers. The fibers may be staple fibers and may have an average length of from 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 where the fibers intersect.

[0049] Synthetic cellulose fiber types include rayon in all its varieties and other fibers derived from viscose or chemically-modified cellulose. Chemically treated natural cellulosic fibers may be used, such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers. For good mechanical properties in using papermaking fibers, it may be desirable that the fibers be relatively undamaged and largely unrefined or only lightly refined. While recycled fibers may be used, virgin fibers are generally useful for their mechanical properties and lack of contaminants. Mercerized fibers, regenerated cellulosic fibers, cellulose produced by microbes, rayon, and other cellulosic material or cellulosic derivatives may be used. Suitable papermaking fibers may also include recycled fibers, virgin fibers, or mixes thereof. In certain example embodiments capable of high bulk and good compressive properties, the fibers may have a Canadian Standard Freeness of at least two hundred (200), more specifically at least three hundred (300), more specifically still at least four hundred (400), and most specifically at least five hundred (500).

[0050] Other papermaking fibers that may be used include broke or recycled fibers and high yield fibers. High yield pulp fibers are those papermaking fibers produced by pulping processes providing a yield of about sixty-five percent (65%) or greater, more specifically about seventy-five percent (75%) or greater, and still more specifically about seventy-five percent (75%) to about ninety-five percent (95%). Yield is the resulting amount of processed fibers expressed as a percentage of the initial wood mass. Such pulping processes include bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps, and high yield Kraft pulps, all of which leave the resulting fibers with high levels of lignin. High yield fibers are well known for their stiffness in both dry and wet states relative to typical chemically pulped fibers.

[0051] The web may also be formed without a substantial amount of inner fi ber-to-fi ber bond strength. In this regard, the fiber furnish used to form the base web may be treated with a chemical debonding agent. The debonding agent may be added to the foamed fiber slurry during the pulping process or may be added directly to the headbox. Suitable debonding agents that may be used include cationic debonding agents, such as fatty dialkyl quaternary amine salts, mono fatty alkyl tertiary amine salts, primary amine salts, imidazoline quaternary salts, silicone quaternary salt and unsaturated fatty alkyl amine salts. Other suitable debonding agents are disclosed in U.S. Pat. No. 5,529,665 to Kaun, the entirety of which is incorporated herein by reference. In particular, Kaun discloses the use of cationic silicone compositions as debonding agents.

[0052] In one example embodiment, the debonding agent used in the process of the present disclosure may be an organic quaternary ammonium chloride and, particularly, a silicone-based amine salt of a quaternary ammonium chloride. For example, the debonding agent may be PROSOFT.RTM. TQ1003, marketed by the Hercules Corporation. The debonding agent may be added to the fiber slurry in an amount of from about one kilogram per metric ton (1 kg / tonne) to about ten kilograms per metric ton (10 kg / tonne) of fibers present within the slurry.

[0053] In an alternative example embodiment, the debonding agent may be an imidazoline-based agent. The imidazoline-based debonding agent may be obtained, for instance, from the Witco Corporation. The imidazoline-based debonding agent may be added in an amount of between two kilograms per metric ton (2.0 kg / tonne) to about fifteen kilograms per metric ton (15 kg / tonne).

[0054] Other optional chemical additives may also be added to the aqueous papermaking furnish or to the formed embryonic web to impart additional benefits to the product and process. The following materials are included as examples of additional chemicals that may be applied to the web. The chemicals are included as examples and are not intended to limit the scope of the disclosure. Such chemicals may be added at any point in the papermaking process. Additional types of chemicals that may be added to the paper web include, but are not limited to, absorbency aids usually in the form of cationic, anionic, or non-ionic surfactants, humectants and plasticizers, such as low molecular weight polyethylene glycols, and polyhydroxy compounds, such as glycerin and propylene glycol. Materials that supply skin health benefits, such as mineral oil, aloe extract, vitamin E, silicone, lotions in general and the like, may also be incorporated into the finished products.

[0055] Other examples of such materials include but are not limited to odor control agents, such as odor absorbents, activated carbon fibers and particles, baby powder, baking soda, chelating agents, zeolites, perfumes or other odor-masking agents, cyclodextrin compounds, oxidizers, and the like. Superabsorbent particles may also be employed. Additional options include cationic dyes, optical brighteners, humectants, emollients, and the like.

[0056] Turning to FIG. 2, once the foamed suspension of fibers is formed in the tank 12 (FIG. 1), the foamed suspension of fibers may be fed to the web forming system 10. As illustrated in FIG. 2, the web forming system 10 may include includes one or more forming zones. In the example embodiment of FIG. 2, three forming zones are shown, including first forming zone 50, second forming zone 52, and third forming zone 54. The forming zones 50, 52, and 54 are positioned along the porous forming surface 26. In one example embodiment, as shown in FIG. 2, the porous forming surface 26 may be at an incline with respect to horizontal For instance, the porous forming surface 26 may be oriented at an angle with the horizontal of 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°). Each forming zone 50, 52, and 54 may be configured to receive a separate and independent flow of the foamed suspension of fibers for depositing the foamed suspension of fibers onto the forming surface 26. For instance, the first forming zone 50 may deposit a foamed suspension of fibers directly onto the forming surface 26. The second forming zone 52, however, may be configured to deposit a second flow rate of the foamed suspension of fibers on top of the fibers deposited by the first forming zone 50. Similarly, the third forming zone 54 may deposit a flow of the aqueous suspension of fibers on top of the fibers deposited by the first forming zone 50 and the second forming zone 52. In this manner, a multilayered web may be formed. It should be understood, however, that the system and process of the present disclosure may include only a single forming zone for forming single layered webs.

[0057] As shown in FIG. 2, each forming zone 50, 52, and 54 may be in fluid communication with a separate and independent foamed fibrous supply line. For instance, first forming zone 50 may be in communication with a first foamed fibrous supply line 56, the second forming zone 52 may be in fluid communication with a second foamed fibrous supply line 58, and the third forming zone 54 may be in fluid communication with a third foamed fibrous supply line 60. The first, second, and third supply lines 56, 58, and 60 may be configured to feed a foamed suspension of fibers to each of the respective forming zones 50, 52, and 54 at a determined and selected flow characteristic, which may be, for instance, flow rate, such as volumetric flow rate, pressure, air content, and / or density. In this regard, each of the supply lines 56, 58, and 60 may be in fluid communication with the mixing tank 12 as shown in FIG. 1 . For instance, the first supply line 56 may include a first injection line 62 that is connected to the mixing tank 12. Similarly, the second supply line 58 may include a second injection line 64, while the third supply line 60 may be in communication with a third injection line 66. The injections lines 62, 64, and 66 may all be in communication with the mixing tank 12 for feeding the foamed suspension of fibers to each of the forming zones 50, 52, and 54. Alternatively, the system 10 may include separate mixing tanks, and each of the first, second, and third injection lines 62, 64, and 66 may be connected to a different, respective mixing tank for feeding the foamed suspension of fibers to the web forming system 10.

[0058] As shown, each of the foamed fibrous 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 fibrous supply line 56, 58, and 60 may also be in communication with a density monitoring device. The density monitoring device, for instance, may be part of one of the other devices, such as part of the flow meter. Alternatively, the density of the foamed suspension of fibers may be calculated using information received from the other instruments.

[0059] For example: the first foamed fibrous 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 fibrous 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 fibrous 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 may be adjustable such that the foamed suspension of fibers may be independently fed 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 may monitor flow rates, pressures, and temperatures upstream from the forming surface for calculating at least one characteristic of the flow of the foamed suspension of fibers at the forming surface. In one example embodiment, the flow meters 74, 76, and 78, the pressure monitoring devices 80, 82, and 84, the temperature monitoring devices 81 , 83 and 85 may be placed in communication with one or more controllers. The controllers may include microprocessors or any suitable programmable device. The pumping devices 68, 70, and 72 may also be placed in communication with the one or more controllers. The controllers may be configured for adjusting the pumping devices 68, 70, and 72 based upon information received from the flow meters 74, 76, and 78, from the pressure monitoring devices 80, 82, and 84, and / or from the temperature monitoring devices 81 , 83 and 85. In this manner, the foamed suspension of fibers may be fed to each forming zone 50, 52, and 54 at a flow rate within desired set points and / or at a pressure within desired set points for optimizing formation of a web on the forming surface 26.

[0060] Information received from the flow meters 74, 76, and 78, from the pressure monitoring devices 80, 82, and 84, and / or from the temperature monitoring devices 81 , 83, and 85 may be used to determine the characteristics of the foamed suspension of fibers at the location of the measurements. In addition, the density of the foamed suspension of fibers may be measured or calculated from the information received from the various instruments. This information, in one embodiment, may be sent to the controllers for then calculating at least one characteristic of the foamed suspension of fibers at the forming surface. In particular, the controller may be programmed to correct the determined volumetric flow rate at the forming surface based upon changes in density, pressure, and temperature. For example, the foamed suspension can experience a pressure drop when being emitted from the supply line onto the forming surface that changes the density of the foamed suspension. One method for calculating downstream values of the foamed suspension, for instance, is disclosed in U.S. Patent No. 4,764,253, which is incorporated herein by reference.

[0061] As shown in FIG. 2, opposite the first forming zone 50 along the forming surface 26 may be a first drain device 86 in fluid communication with a first drain line 92. Opposite the second forming zone 52 may be a second drain device 88 in fluid communication with a second drain line 94. Similarly, opposite the third forming zone 54 may be a third drain device 90 in communication with a third drain line 96. The first, second, and third forming zones 50, 52, and 54 may be adjacent to one another along the forming surface 26 and may be positioned on one side of the forming surface 26. The drain devices 86, 88, and 90 may also be adjacent to one another and may be positioned on the opposite side of the forming surface 26 in alignment with the forming zones 50, 52, and 54. As the foamed suspension of fibers is deposited onto the forming surface from each forming zone 50, 52, and 54, a web 14 may be formed and excess fluids may enter the corresponding drain devices 86, 88, and 90. The drain devices may be any suitable static or dynamic drain device capable of draining fluids from the web or from the forming surfaces. The drain device may be a static suction or vacuum box. Alternatively, the drain device may be a drum, such as a rotating drum that applies suction.

[0062] As shown in FIG. 2, each drain 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 drain 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 drain 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 drain 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 flow through the line and may be, an adjustable valve or a pump. Pumps, for instance, may be used to apply suction to the forming surface. Alternatively, draining can occur through gravity. In still another example embodiment, each flow control device 98, 100, and 102 may be a combination of a pump and an adjustable valve.

[0063] In one example embodiment, the system 10 may further include one or more controllers 116. The controllers 116 may include microprocessors or any suitable programmable devices. As shown in FIG. 2, 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 may be in communication with the controller 116. The controller 116 may 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 making adjustments to the flow control devices 98, 100, and 102 for controlling the flow rate in which fluids are drained from each of the drain devices 86, 88, and 90. The combination of receiving information from the flow control devices 98, 100, and 102, which may be volumetric flow meters, from the pressure monitoring devices 110, 112, and 114, from the temperature monitoring devices 105, 107, and 109, and / or from optional density monitoring devices may be used to quantify the fluid discharge flows containing both gases and liquids. In one example embodiment, the controller 116 may use the above information to calculate a flow rate, such as a volumetric flow rate, at the forming surface and control the volumetric flow rate based upon at least one characteristic of the foamed suspension being fed to the forming surface. The controller 116 may then control the flow control devices 98, 100, and 102 to achieve a calculated discharge flow rate through each drain device and drain line. In example embodiments, the process and system of the present disclosure may further include a sealing zone 120 positioned along the forming fabric 26 and in fluid communication with a sealing fluid supply line 122. As shown in FIG. 2, 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 for feeding a fluid, particularly a liquid, to the sealing zone 120. Sealing fluid may be any suitable liquid. For instance, the sealing fluid may be water, a water and surfactant solution, or the like. In one example embodiment, the sealing fluid may be non-fibrous. A sealing fluid may be fed to the sealing fluid zone 120 at a flow rate and / or at a pressure such that sealing fluid deposited onto the forming surface 26 forms a fluid seal that prevents air flow in an upstream longitudinal direction. Information received from the flow meter 126, the pressure monitoring device 128, the temperature monitoring device 129, and optionally a density monitoring device may be used to calculate volumetric flow rates of the foam at the forming surface.

[0064] As shown in FIG. 2, the sealing zone 120 may be positioned upstream from and adjacent to the plurality of forming zones. The sealing zone 120 may also be placed opposite a sealing drain device 130 connected to a sealing drain line 132. The sealing drain line 132 may include a flow control device 134, a flow meter 136, a temperature monitoring device 137, and a pressure sensing device 138 that may all be in communication with the controller 116. In this manner, the flow rate of drainage of the sealing fluid may be controlled based upon the flow rate or pressure at which the sealing fluid enters or exits the sealing zone 120. By including the sealing zone 120, better formation of the web 14 occurs opposite the first forming zone 50.

[0065] The web forming system 10 as shown in FIG. 2 may also include a suction zone 140 adjacent to the plurality of formation zones and positioned downstream from the formation zones. The suction zone 140 may be in fluid communication with a drain line 142 which may include a pressure monitoring device 144. The suction zone 140 is for drawing fluids through the embryonic web 14 after the web has been formed. The suction zone 140 is for removing excess fluids, particularly liquids, from the web 14. In one aspect, the drainage flow rate of the foamed suspension of fibers being drained through the one or more drain devices may be controlled such that excess fluid from the one or more forming zones enters the suction zone 140. Ideally, the suction zone 140 facilitates draining fluids from the web 14 without causing any detrimental effects.

[0066] As shown in FIG. 2, all of the drain lines 92, 94, 96, 132, and 142 may be fed to a separator tank 150. The separator tank 150 may be configured to separate free gases from foam. As shown, the separator tank 150 may include a gas outlet 152 that may be connected to a vacuum source and a liquid outlet 154. The liquid collected in the separator tank 150 may include a water and surfactant mixture. As shown in FIG. 2, a pumping device 156 may be used to pump liquids from the separator tank 150 to a liquid tank 158 which may also be placed in communication with a water source 160. The liquid tank 158 may be used to recycle the water and surfactant mixture back into the process through the supply lines 56, 58, 60, and 122.

[0067] Referring back to FIG. 1 , after the embryonic web 14 is formed from the web forming system or headbox 10, the web 14 may be fed to various different downstream processes. FIG. 1 merely represents one example embodiment of a process for drying the web 14 after being formed. As shown, the web 14 is formed on the forming surface 26 and conveyed downstream. The endless traveling forming fabric 26, for instance, may be supported and driven by rolls 28.

[0068] Once formed on the forming fabric 26, the formed web 14 may have a consistency of 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 may be less than about two percent (2%), such as less than about one and eight-tenths percent (1 .8%), such as less than about one and a half percent (1 .5%). The forming consistency is generally greater than about a half percent (0.5%), such as greater than about eight-tenths percent (0.8%).

[0069] Once the wet web 14 is formed on the forming fabric 26, the web 14 is conveyed downstream and optionally further dewatered. For instance, the process may optionally include a plurality of vacuum devices 16, such as vacuum and vacuum rolls. The vacuum boxes assist in removing moisture from the newly formed web 14.

[0070] As shown in FIG. 1 , the forming fabric 26 may also be placed in communication with a steambox 18 positioned above a pair of vacuum rolls 20. The steambox 18, for instance, may increase dryness and reduce cross-directional moisture variance. The applied steam from the steambox 18 heats the moisture in the wet web 14 causing the water in the web to drain more readily, especially in conjunction with the vacuum rolls 20. From the forming fabric 26, the newly formed web 14 is conveyed downstream and dried. The web 14 may be dried using any suitable drying device. For instance, the web 14 may be through-air dried or placed on a heated drying drum and creped or left uncreped. In FIG. 1 , for instance, the formed web 14 is placed in contact with two heated drying drums 38 and 40. In one example embodiment, from the drying drums 38 and 40, the web 14 may be fed to a through-air dryer prior to being wound into a roll.

[0071] The embodiment in FIG. 2 is for forming multilayer webs. In another aspect, the process of the present disclosure may be used to create single layer webs from a foamed suspension of materials.

[0072] Turning now to FIG. 3, a system 200 for feeding superabsorbent material, or other solid particles, into a foam forming system according to an example embodiment of the present disclosure is shown. It will be understood that system 200 may be utilized in or with any foam forming system or process for forming webs from a foamed suspension of fibers. For example, system 200 may be used in or with the example systems and processes shown in FIGS. 1 and 2 and described above. However, it will be understood that system 200 may be used in or with other systems and processes for forming webs from a foamed suspension of fibers in alternative example embodiments.

[0073] As shown in FIG. 3, system 200 includes a headbox 210 and a superabsorbent material feeder assembly 220. The headbox 210 may be configured for forming a web from one or more foamed suspension of fibers. For instance, a foamed suspension of fibers 214 may be pumped from a tank 212 towards a headbox 210. At the headbox 210, the foamed suspension of fibers 214 may be deposited on a formation surface to for an embryonic web, e.g., as described above for the web forming system 10. The superabsorbent material feeder assembly 220 may add superabsorbent material 202 to the foamed suspension of fibers 214 upstream of the headbox 210. Thus, the foamed suspension of fibers 214 flowing into the headbox 210 may include superabsorbent material 202.

[0074] The superabsorbent material feeder assembly 220 may be positioned upstream of the headbox 210 along the flow of foamed suspension of fibers 214 to the headbox 210. The superabsorbent material feeder assembly 220 may be configured for adding superabsorbent material to foam, such as the flow of foamed suspension of fibers 214. The superabsorbent material feeder assembly 220 may include a supply chamber 230, a supply hopper 240, and an airlock valve 250. The supply chamber 230 may be fillable with superabsorbent material 202. For example, the superabsorbent material 202 may flow from a supply tank 234 to the supply chamber 230, and the superabsorbent material 202 may be contained within an interior 232 of the supply chamber 230. A control valve 236 may regulate the flow of superabsorbent material 202 from the supply tank 234 to the supply chamber 230.

[0075] A pressure supply line 260 may be coupled to the supply chamber 230. The pressure supply line 260 may be configured for drawing air from and / or supplying air to the supply chamber 230. For instance, the pressure supply line 260 may be connected to a vacuum source 262, and the vacuum source 262 may generate negative pressure for drawing air out of the interior 232 of the supply chamber 230. Thus, e.g., air may be removed from the supply chamber 230 via the pressure supply line 260. Moreover, the air may be removed from the supply chamber 230 while the superabsorbent material 202 remains within the interior 232 of the supply chamber 230. The vacuum source 262 may be any suitable device for generating negative pressure relative to ambient atmosphere. For instance, the vacuum source 262 may include one or more of a Venturi pump or a rotary vane pump. In other example embodiments, the pressure supply line 260 may be connected to a positive pressure source, such as a pump, compressor, etc., that may generate positive pressure for flowing air into the interior 232 of the supply chamber 230.

[0076] In example embodiments, the pressure level (e.g., the vacuum level) in the supply chamber 230 may be controlled by a backpressure regulator receiving a pressure signal from the supply hopper 240 or pump 280. As another example, the pressure level in the supply chamber 230 may be controlled by a control valve 264 coupled to the pressure supply line 260, and the control valve 264 may be configured for regulating the flow of air from and / or into the supply chamber 230, e.g., based on a pressure signal from the supply chamber 230. As another example, the pressure level in the supply chamber 230 may be controlled by a Venturi pump supplied by compressed air, and the flow rate / pressure of the compressed air may be controlled for adjusting the vacuum level, e.g., based on a pressure signal from the supply chamber 230.

[0077] The airlock valve 250 is disposed between the supply chamber 230 and the supply hopper 240. The airlock valve 250 is configured for regulating a flow of superabsorbent material 202 from the supply chamber 230 to the supply hopper 240. For example, when the airlock valve 250 is open, the superabsorbent material 202 in the interior 232 of the supply chamber 230 may flow through the airlock valve 250 into an interior 242 of the supply hopper 240. In example embodiments, the supply hopper 240 may be positioned below the supply chamber 230 such that the superabsorbent material 202 is gravity-fed from the interior 232 of the supply chamber 230 to the interior 242 of the supply hopper 240 when the airlock valve 250 is open. Conversely, when the airlock valve 250 is closed, the airlock valve 250 may block the superabsorbent material 202 in the interior 232 of the supply chamber 230 from flowing into the interior 242 of the supply hopper 240. In example embodiments, the airlock valve 250 may be a slide gate or other suitable valve.

[0078] The airlock valve 250 may also be configured for regulating airflow between the supply chamber 230 and the supply hopper 240. For example, when the airlock valve 250 is open, the interior 232 of the supply chamber 230 may be in fluid communication with the interior 242 of the supply hopper 240 through the airlock valve 250, e.g., such that air may flow between the supply chamber 230 and the supply hopper 240 via the airlock valve 250. Conversely, when the airlock valve 250 is closed, the airlock valve 250 may block airflow between the interior 232 of the supply chamber 230 and the interior 242 of the supply hopper 240 through the airlock valve 250.

[0079] In example embodiments, the superabsorbent material feeder assembly 220 may include an equilibration valve 252. The equilibration valve 252 may be disposed on an equilibration line between the interior 232 of the supply chamber 230 and the interior 242 of the supply hopper 240. Opening the equilibration valve 252 may advantageously equilibrate pressure differences between the supply chamber 230 and the supply hopper 240 at a controlled rate, e.g., prior for openinging the airlock valve 250. Thus, rapid pressure equilibration of the supply chamber 230 and the supply hopper 240 may be avoided when the airlock valve 250 is opened. Moreover, drawing of foam from the pump 280 into the superabsorbent material feeder assembly 220 or rapid injections of air to the pump 280 due to rapid pressure equilibration of the supply chamber 230 and the supply hopper 240 may be avoided or limited.

[0080] As may be seen from the above, the supply hopper 240 is configured for receiving the superabsorbent material 202 from the supply chamber 230. Thus, the interior 242 of the supply hopper 240 may be filled with the superabsorbent material 202 from the interior 232 of the supply chamber 230 when the airlock valve 250 is open. The supply hopper 240 may be configured for feeding the superabsorbent material 202 into the foamed suspension of fibers 214. For example, a metering device 270 may be positioned to receive superabsorbent material 202 from the interior 242 of the supply hopper 240. In example embodiments, the metering device 270 may be positioned at or proximate a bottom portion of the supply hopper 240 such that the superabsorbent material 202 is gravity-fed from the interior 242 of the supply hopper 240 to the metering device 270. The metering device 270 may be configured for feeding the superabsorbent material 202 into the foamed suspension of fibers 214 at a selected rate. For example, the metering device 270 may supply the superabsorbent material 202 to a pump 280, such as an eductor, and the pump 280 may draw the superabsorbent material 202 into the foamed suspension of fibers 214 due to a motive fluid (e.g., the foamed suspension of fibers 214) generating a pressure reduction via the Venturi effect. The metering device 270 may be any suitable device for feeding the superabsorbent material 202. For instance, the metering device 270 may include one or more of a Christy feeder, a vibrating hopper, a screw feeder, etc. In the example embodiment shown in FIG. 3, the metering device 270 includes a hopper 272 that directs the superabsorbent material 202 to the pump 280, and the metering device 270 is disposed within a vacuum box 274 to block or limit introduction of ambient air into the foamed suspension of fibers 214 via the pump 280.

[0081] In addition to the superabsorbent material 202, the pump 280 may also draw air into the foamed suspension of fibers 214. However, the superabsorbent material feeder assembly 220 may include features for limiting the volume of air entering the foamed suspension of fibers 214. Thus, e.g., the superabsorbent material feeder assembly 220 may advantageously add the superabsorbent material 202 to the foamed suspension of fibers 214 without negatively affecting the stability of the foamed suspension of fibers 214 by introducing excess air into the foamed suspension of fibers 214. With reference to FIG. 3, the pump 280 may draw air from the supply hopper 240 into the foamed suspension of fibers 214 in addition to the superabsorbent material 202. The airlock valve 250 may also block airflow between the supply chamber 230 and the supply hopper 240 when the airlock valve 250 is closed. Thus, the airlock valve 250 may limit or prevent air from the supply chamber 230 from flowing into the supply hopper 240 as the pump 280 draws superabsorbent material 202 into the foamed suspension of fibers 214. In addition, the pressure supply line 260 may draw air out of the supply chamber 230 while the airlock valve 250 is closed, e.g., in order to limit the volume of air transferred into the supply hopper 240 from the supply chamber 230 when the airlock valve 250 is open. As may be seen from the above, various components of the superabsorbent material feeder assembly 220 may cooperate to limit the volume of air entering the foamed suspension of fibers 214, e.g., via the pump 280, while the superabsorbent material feeder assembly 220 feds the superabsorbent material 202 into the foamed suspension of fibers 214.

[0082] In example embodiments, the metering device 270, the supply hopper 240, the supply chamber 230, and other components of superabsorbent material feeder assembly 220 may be sealed relative to ambient air in order to limit or prevent introduction of the ambient air into the foamed suspension of fibers 214 via the pump 280. However, it will be understood that superabsorbent material feeder assembly 220 may be configured to allow a limited bleed of air or other gases into the superabsorbent material feeder assembly 220 in order to facilitate the feeding of the superabsorbent material 202 into the foamed suspension of fibers 214. However, the bleed of air or other gases is limited in order to avoid negatively affecting the stability of the foamed suspension of fibers 214.

[0083] As shown in FIG. 3, system 200 may also include or be in operative communication with a processing device or a controller 290 that may be generally configured to facilitate operation of at least a portion of system 200. In this regard, control valve 236, airlock valve 250, control valve 264, metering device 270, various sensors, and other components of system 200 may be in communication with controller 290. Thus, e.g., the controller 290 may receive inputs from the sensors and may adjust operation of the components of system 200, such as airlock valve 250, based at least in part on the inputs from the sensors. The control valve 236, airlock valve 250, control valve 264, metering device 270, the various sensors, and other components of system 200 may be in communication with controller 290 via, for example, one or more signal lines or shared communication busses. In this manner, Input / Output ("I / O”) signals may be routed between controller 290 and various operational components of system 200.

[0084] As used herein, the terms "processing device,” "computing device,” “controller,” or the like may generally refer to any suitable processing device, such as a general or special purpose microprocessor, a microcontroller, an integrated circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field-programmable gate array (FPGA), a logic device, one or more central processing units (CPUs), a graphics processing units (GPUs), processing units performing other specialized calculations, semiconductor devices, etc. In addition, these “controllers” are not necessarily restricted to a single element but may include any suitable number, type, and configuration of processing devices integrated in any suitable manner to facilitate appliance operation. Alternatively, controller 290 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and / or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND / OR gates, and the like) to perform control functionality instead of relying upon software.

[0085] Controller 290 may include, or be associated with, one or more memory elements or non- transitory computer-readable storage mediums, such as RAM, ROM, EEPROM, EPROM, flash memory devices, magnetic disks, or other suitable memory devices (including combinations thereof). These memory devices may be a separate component from the processor or may be included onboard within the processor. In addition, these memory devices may store information and / or data accessible by the one or more processors, including instructions that may be executed by the one or more processors. It should be appreciated that the instructions may be software written in any suitable programming language or may be implemented in hardware. Additionally, or alternatively, the instructions may be executed logically and / or virtually using separate threads on one or more processors.

[0086] For example, controller 290 may be operable to execute programming instructions or microcontrol code associated with an operating cycle of system 200. In this regard, the instructions may be software or any set of instructions that when executed by the processing device, cause the processing device to perform operations, such as running one or more software applications, adjusting the operating parameters of airlock valve 250, etc. Moreover, it should be noted that controller 290 as disclosed herein is capable of and may be operable to perform any methods, method steps, or portions of methods as disclosed herein. For example, in some example embodiments, methods disclosed herein may be embodied in programming instructions stored in the memory and executed by controller 290.

[0087] The memory devices may also store data that may be retrieved, manipulated, created, or stored by the one or more processors or portions of controller 290. The data may include, for instance, data to facilitate performance of methods described herein. The data may be stored locally (e.g., on controller 290) in one or more databases and / or may be split up so that the data is stored in multiple locations. In addition, or alternatively, the one or more database(s) may be connected to controller 290 through any suitable network(s), such as through a high bandwidth local area network (LAN) or wide area network (WAN). In this regard, for example, controller 290 may further include a communication module or interface that may be used to communicate with one or more other component(s) of system 200, controller 290, or any other suitable device, e.g ., via any suitable communication lines or network(s) and using any suitable communication protocol. The communication interface may include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, or other suitable components.

[0088] As noted above, the controller 290 may be configured for controlling operation of the control valve 236, the airlock valve 250, the control valve 264, the metering device 270, and other components of system 200 based at least in part on inputs from various sensors, such as a supply chamber pressure sensor 292, a supply hopper pressure sensor 294, and level sensors 296, 298. The supply chamber pressure sensor 292 may be configured for measuring an air pressure within the supply chamber 230. Thus, e.g., the supply chamber pressure sensor 292 may be any suitable pressure sensor for measuring the pressure within the interior 232 of the supply chamber 230. The supply hopper pressure sensor 294 may be configured for measuring an air pressure within the supply hopper 240. Thus, e.g., the supply hopper pressure sensor 294 may be any suitable pressure sensor for measuring the pressure within the interior 242 of the supply hopper 240. The level sensors 296, 298 may be configured for measuring a level of the superabsorbent material 202 within the supply hopper 240. As an example, the level sensors 296, 298 may include one or more of an optical level sensor, an ultrasonic level sensor, a capacitance level sensor, a vibrating point level sensor, a rotating paddle level sensor, etc.

[0089] In example embodiments, the controller 290 may control components of system 200 in order to feed the superabsorbent material 202 into the foamed suspension of fibers 214. For example, the controller 290 may activate the metering device 270 such that the metering device 270 feds the superabsorbent material 202 from the supply hopper 240 to the pump 280, which draws the superabsorbent material 202 into the foamed suspension of fibers 214. The controller 290 may also detect the level of the superabsorbent material 202 in the supply hopper 240 via the level sensors 296, 298. When the supply hopper 240 needs more superabsorbent material 202, the controller 290 may operate various components of the superabsorbent material feeder assembly 220 to add superabsorbent material 202 to the supply hopper 240 without negatively affecting the stability of the foamed suspension of fibers 214 by introducing excess air into the foamed suspension of fibers 214. For example, the controller 290 may open the control valve 234 such that superabsorbent material 202 from the supply tank 234 flows to the supply chamber 230. When the interior 232 of the supply chamber 230 is filled with the superabsorbent material 202, the controller 290 may close the control valve 234 in order to stop the flow of superabsorbent material 202 into the supply chamber 230. The controller 290 may also open the control valve 264 to remove air from the supply chamber 230 via the pressure supply line 260. While the superabsorbent material 202 is added to the supply chamber 230 and the air is removed from the supply chamber 230, the controller 290 may keep the airlock valve 250 closed. Conversely, when the supply chamber 230 is filled with the superabsorbent material 202 and the air has been removed from the supply chamber 230 via the pressure supply line 260, the controller 290 may open the airlock valve 250 such that the superabsorbent material 202 in the supply chamber 230 flows through the airlock valve 250 into the supply hopper 240. In particular, the controller 290 may open the airlock valve 250 when the pressure measurements from the supply chamber pressure sensor 292 and the supply hopper pressure sensor 294 are (e.g., about) equal. By removing the air from the supply chamber 230 prior for openinging the airlock valve 250, the volume of air entering the supply hopper 240 from the supply chamber 230 may be reduced or limited to an extent that does not affect stability of the foamed suspension of fibers 214.

[0090] As may be seen from the above, superabsorbent material 202 may be added to the supply hopper 240 via an airlock approach, in which discrete volumes of superabsorbent material 202 and air are added to the separate supply chamber 230. When full, the air in the supply chamber 230 is evacuated by the pressure supply line 260, which is separate from the pump 280, e.g., until the pressure of the supply chamber 230 is about equal to the pressure of the supply hopper 240. The pressure supply line 260 may then be closed, and the airlock valve 250 opened to transfer the superabsorbent material 202 from the supply chamber 230 to the supply hopper 240. Once the superabsorbent material 202 is added to the supply hopper 240, the airlock valve 250 may be closed and the process repeated to allow for continuous feeding of superabsorbent material 202 into the foamed suspension of fibers 214 flowing to the headbox 210.

[0091] FIG. 4 illustrates a method 400 for foam forming according to an example embodiment of the present subject matter As an example, method 400 may be used in or with system 200 (FIG. 3) to assist with feeding superabsorbent material into a flow of foam to a headbox. The controller 290 of system 200 may be programmed or configured to implement method 400. While method 400 is described in greater detail below in the context of system 200, it will be understood that method 400 may be used in or within any suitable system or process in alternative example embodiments.

[0092] At 410, superabsorbent material flows to a supply chamber. For example, superabsorbent material 202 may flow from the supply tank 234 to the supply chamber 230 at 410. Moreover, the controller 290 may open the control valve 236 such that the superabsorbent material 202 flows from the supply tank 234 to the supply chamber 230. As another example, the superabsorbent material 202 may be manually added to the supply chamber 230.

[0093] At 420, air is removed from the supply chamber. For example, the pressure supply line 260 may remove air from the supply chamber 230 at 420. Moreover, the controller 290 may open the control valve 264 to evacuate air from the supply chamber 230 through the pressure supply line 260. In certain example embodiment, method 400 may include measuring an air pressure within the supply hopper at 420. For example, the supply chamber pressure sensor 292 may measure the air pressure within the supply chamber 230. In addition, method 400 may further include adjusting the vacuum pressure for removing air from the supply chamber based on the measured air pressure in the supply hopper. For instance, the controller 290 may adjust a backpressure regulator on the pressure supply line 260 based at least in part on the measured air pressure within the supply chamber 230 from the supply chamber pressure sensor 292. As another example, the controller 290 may adjust a flow of motive fluid through a Venturi pump configured as the vacuum source 262 based at least in part on the measured air pressure within the supply chamber 230 from the supply chamber pressure sensor 292. Thus, e.g., the vacuum applied to the supply chamber 230 at 420 may be controlled, e.g., to about match the pressure within the supply hopper 240. In other example embodiments, air may be added to the supply chamber. For example, the pressure supply line 260 may supply air into the supply chamber 230 at 420.

[0094] At 430, an airlock valve between the supply chamber and a supply hopper may be opened such that the superabsorbent material transfers from the supply chamber to the supply hopper. For example, the airlock valve 250 may be opened at 430 such that the superabsorbent material 202 in the interior 232 of the supply chamber 230 flows through the airlock valve 250 into the interior 242 of the supply hopper 240. Moreover, the controller 290 may open the airlock valve 250 at 430. In certain example embodiments, the airlock valve may be opened when a differential between an air pressure within the supply chamber and an air pressure within the supply hopper is less than a threshold value. For instance, the controller 290 may open the airlock valve 250 when the differential between the measurements of the supply chamber pressure sensor 292 and the supply hopper pressure sensor 294 are less than the threshold value. The threshold value may be selected such that the air pressures in the supply chamber 230 and the supply hopper 240 are about equal prior for openinging the airlock valve 250. For example, the threshold value may be no greater than a half bar (0.5 bar). Controller 290 may open the equilibration valve 252 to equilibrate pressure differences between the supply chamber 230 and the supply hopper 240 at a controlled rate at 430, e.g., prior for openinging the airlock valve 250. Thus, drawing of foam from the pump 280 into the superabsorbent material feeder assembly 220 or rapid injections of air to the pump 280 due to rapid pressure equilibration of the supply chamber 230 and the supply hopper 240 may be avoided or limited.

[0095] At 440, the superabsorbent material is metered into a flow of foam to a headbox. For example, the metering device 270 fed the superabsorbent material 202 from the supply hopper 240 into the foamed suspension of fibers 214 at a selected rate at 440. The controller 290 may activate the metering device 270. Method 400 may also include drawing the superabsorbent material into the flow of foam to the headbox via a pump, such as an eductor. For instance, the metering device 270 may supply the superabsorbent material 202 to the pump 280, and the pump 280 may draw the superabsorbent material 202 into the foamed suspension of fibers 214. The pump 280 may also draw air from the supply hopper into the foam. For example, the pump 280 may draw air from the supply hopper 240 into the foamed suspension of fibers 214 in addition to the superabsorbent material 202. The airlock valve 250 may also block airflow between the supply chamber 230 and the supply hopper 240 when the airlock valve 250 is closed. Thus, the airlock valve 250 may limit or prevent air from the supply chamber 230 from flowing into the supply hopper 240 as the pump 280 draws superabsorbent material 202 into the foamed suspension of fibers 214.

[0096] FIG. 4 depicts steps performed in a particular order for purposes of illustration and discussion. Those of ordinary skill in the art, using the disclosures provided herein, will understand that the steps of any of the methods discussed herein may be adapted, rearranged, expanded, omitted, or modified in various ways without deviating from the scope of the present disclosure.

[0097] These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.

[0098] EXAMPLE EMBODIMENTS

[0099] First example embodiment: A foam forming system, comprising: a headbox; a superabsorbent material feeder assembly positioned upstream of the headbox on a flow path for foam to the headbox, the superabsorbent material feeder assembly configured for adding superabsorbent material to the foam, the superabsorbent material feeder assembly comprising a supply chamber fillable with the superabsorbent material, a supply hopper, an airlock valve disposed between the supply chamber and the supply hopper, the airlock valve configured for opening and closing in order to selectively connect the supply chamber and the supply hopper, the superabsorbent material in the supply chamber flowable into the supply hopper when the airlock valve is open, and a pressure supply line coupled to the supply chamber and configured for flowing air into and / or from the supply chamber.

[0100] Second example embodiment: The foam forming system of the first example embodiment, wherein the superabsorbent material feeder assembly further comprises a pump positioned on the flow path for foam to the headbox, and the pump is configured for drawing the superabsorbent material into the foam.

[0101] Third example embodiment: The foam forming system of the second example embodiment, wherein the pump is configured for drawing air from the supply hopper into the foam, and the airlock valve blocks airflow between the supply chamber and the supply hopper when the airlock valve is closed.

[0102] Fourth example embodiment: The foam forming system of any one of first through third example embodiments, wherein the superabsorbent material feeder assembly further comprises an isolation valve coupled to the pressure supply line.

[0103] Fifth example embodiment: The foam forming system of any one of the first through the fourth example embodiments, wherein: the superabsorbent material feeder assembly further comprises a controller, a supply chamber pressure sensor, and a supply hopper pressure sensor; the supply chamber pressure sensor is configured for measuring an air pressure within the supply chamber; the supply hopper pressure sensor is configured for measuring an air pressure within the supply hopper; and the controller is in signal communication with the airlock valve, the supply chamber pressure sensor, and the supply hopper pressure sensor; and the controller is configured for opening the valve based at least in part on an air pressure differential between the supply chamber and the supply hopper being less than a threshold value. Sixth example embodiment: The foam forming system of any one of first through the fifth example embodiments, wherein: the superabsorbent material feeder assembly further comprises a backpressure regulator, a supply hopper pressure sensor, and a controller; the backpressure regulator is configured for adjusting a pressure in the pressure supply line; the supply hopper pressure sensor is configured for measuring an air pressure within the supply hopper; and the controller is in signal communication with the supply hopper pressure sensor and the backpressure regulator; and the controller is configured for adjusting the backpressure regulator based at least in part on the air pressure within the supply hopper.

[0104] Seventh example embodiment: The foam forming system of any one of the first through sixth example embodiments, wherein: the superabsorbent material feeder assembly further comprises a Venturi pump, a supply hopper pressure sensor, and a controller; the Venturi pump is connected to the pressure supply line; the supply hopper pressure sensor is configured for measuring an air pressure within the supply hopper; and the controller is in signal communication with the supply hopper pressure sensor; and the controller is configured for adjusting a flow of motive fluid through the Venturi pump based at least in part on the air pressure within the supply hopper.

[0105] Eighth example embodiment: The foam forming system of any one of the first through seventh example embodiments, wherein the supply chamber is disposed above the airlock valve, and the supply hopper is disposed below the airlock valve.

[0106] Nineth example embodiment: The foam forming system of any one of the first through eighth example embodiments, further comprising a metering device configured for regulating a flow of the superabsorbent material from the supply hopper into the flow path for foam to the headbox.

[0107] Tenth example embodiment: A particulate material feeder for a foam forming system, comprising: a supply chamber fillable with particulate material; a supply hopper positioned below the supply chamber; an airlock valve disposed between the supply chamber and the supply hopper, the airlock valve configured for opening and closing in order to selectively connect the supply chamber and the supply hopper, the particulate material in the supply chamber flowable into the supply hopper when the airlock valve is open; and pressure supply line coupled to the supply chamber and configured for flowing air into and / or from the supply chamber.

[0108] Eleventh example embodiment: A method for feeding particulate material within a foam forming process, comprising: flowing particulate material to a supply chamber; removing air from the supply chamber; opening an airlock valve between the supply chamber and a supply hopper such that the particulate material transfers from the supply chamber to the supply hopper; and metering the particulate material into a flow of foam to a headbox. Twelfth example embodiment: The method of the eleventh example embodiment, wherein opening the airlock valve comprises opening the airlock valve when a differential between an air pressure within the supply chamber and an air pressure within the supply hopper is less than a threshold value.

[0109] Thirteenth example embodiment: The method of either the eleventh or the twelfth example embodiments, further comprising drawing the particulate material into the flow of foam to the headbox via a pump.

[0110] Fourteenth example embodiment: The method of any one of the eleventh though thirteenth example embodiments, wherein the pump also draws air from the supply hopper into the foam, and the airlock valve blocks airflow between the supply chamber and the supply hopper when the airlock valve is closed.

[0111] Fifteenth example embodiment: The method of any one of the eleventh through fourteenth example embodiments, further comprising: measuring an air pressure within the supply chamber; and measuring an air pressure within the supply hopper, wherein opening the airlock valve comprises opening the airlock valve based at least in part on an air pressure differential between the supply chamber and the supply hopper being less than a threshold value.

[0112] Sixteenth example embodiment: The method of any one of the eleventh through fifteenth example embodiments, further comprising: measuring an air pressure within the supply hopper; and adjusting a pressure in a pressure supply line via, which flows the air to and / or from the supply chamber, a backpressure regulator based at least in part on the air pressure within the supply hopper. Seventeenth example embodiment: The method of any one of the eleventh through sixteenth example embodiments, further comprising: measuring an air pressure within the supply hopper; and adjusting a flow of motive fluid through a Venturi pump connected to a pressure supply line, which flows the air to and / or from the supply chamber, based at least in part on the air pressure within the supply hopper.

[0113] Eighteenth example embodiment: A system for feeding particulate material within a foam forming process, substantially as described herein Nineteenth example embodiment: A method for feeding particulate material within a foam forming process, substantially as described herein.

Claims

What Is Claimed:1 . A foam forming system, comprising: a headbox; and a superabsorbent material feeder assembly positioned upstream of the headbox on a flow path for foam to the headbox, the superabsorbent material feeder assembly configured for adding superabsorbent material to the foam, the superabsorbent material feeder assembly comprising a supply chamber tillable with the superabsorbent material, a supply hopper, an airlock valve disposed between the supply chamber and the supply hopper, the airlock valve configured for opening and closing in order to selectively connect the supply chamber and the supply hopper, the superabsorbent material in the supply chamber flowable into the supply hopper when the airlock valve is open, and a pressure supply line coupled to the supply chamber and configured for flowing air into and / or from the supply chamber.

2. The foam forming system of claim 1 , wherein the superabsorbent material feeder assembly further comprises a pump positioned on the flow path for foam to the headbox, and the pump is configured for drawing the superabsorbent material into the foam.

3. The foam forming system of claim 2, wherein the pump is configured for drawing air from the supply hopper into the foam, and the airlock valve blocks airflow between the supply chamber and the supply hopper when the airlock valve is closed.

4. The foam forming system of claim 1, wherein the superabsorbent material feeder assembly further comprises an isolation valve coupled to the pressure supply line.

5. The foam forming system of claim 1 , wherein: the superabsorbent material feeder assembly further comprises a controller, a supply chamber pressure sensor, and a supply hopper pressure sensor; the supply chamber pressure sensor is configured for measuring an air pressure within the supply chamber; the supply hopper pressure sensor is configured for measuring an air pressure within the supply hopper; andthe controller is in signal communication with the airlock valve, the supply chamber pressure sensor, and the supply hopper pressure sensor; and the controller is configured for opening the airlock valve based at least in part on an air pressure differential between the supply chamber and the supply hopper being less than a threshold value.

6. The foam forming system of claim 1 , wherein: the superabsorbent material feeder assembly further comprises a backpressure regulator, a supply hopper pressure sensor, and a controller; the backpressure regulator is configured for adjusting a pressure in the pressure supply line; the supply hopper pressure sensor is configured for measuring an air pressure within the supply hopper; and the controller is in signal communication with the supply hopper pressure sensor and the backpressure regulator; and the controller is configured for adjusting the backpressure regulator based at least in part on the air pressure within the supply hopper.

7. The foam forming system of claim 1 , wherein: the superabsorbent material feeder assembly further comprises a Venturi pump, a supply hopper pressure sensor, and a controller; the Venturi pump is connected to the pressure supply line; the supply hopper pressure sensor is configured for measuring an air pressure within the supply hopper; and the controller is in signal communication with the supply hopper pressure sensor; and the controller is configured for adjusting a flow of motive fluid through the Venturi pump based at least in part on the air pressure within the supply hopper.

8. The foam forming system of claim 1 , wherein the supply chamber is disposed above the airlock valve, and the supply hopper is disposed below the airlock valve.

9. The foam forming system of claim 1 , further comprising a metering device configured for regulating a flow of the superabsorbent material from the supply hopper into the flow path for foam to the headbox.

10. A particulate material feeder for a foam forming system, comprising: a supply chamber fillable with particulate material; a supply hopper positioned below the supply chamber; an airlock valve disposed between the supply chamber and the supply hopper, the airlock valve configured for opening and closing in order to selectively connect the supply chamber and the supply hopper, the particulate material in the supply chamber flowable into the supply hopper when the airlock valve is open; and a pressure supply line coupled to the supply chamber and configured for flowing air into and / or from the supply chamber.

11. A method for feeding particulate material within a foam forming process, comprising: flowing particulate material to a supply chamber; removing air from the supply chamber; opening an airlock valve between the supply chamber and a supply hopper such that the particulate material transfers from the supply chamber to the supply hopper; and metering the particulate material into a flow of foam to a headbox.

12. The method of claim 11 , wherein opening the airlock valve comprises opening the airlock valve when a differential between an air pressure within the supply chamber and an air pressure within the supply hopper is less than a threshold value.

13. The method of claim 11 , further comprising drawing the particulate material into the flow of foam to the headbox via a pump.

14. The method of claim 13, wherein the pump also draws air from the supply hopper into the foam, and the airlock valve blocks airflow between the supply chamber and the supply hopper when the airlock valve is closed.

15. The method of claim 11 , further comprising: measuring an air pressure within the supply chamber; and measuring an air pressure within the supply hopper, wherein opening the airlock valve comprises opening the airlock valve based at least in part on an air pressure differential between the supply chamber and the supply hopper being less than a threshold value.

16. The method of claim 11 , further comprising: measuring an air pressure within the supply hopper; and adjusting a pressure in a pressure supply line, which flows the air to and / or from the supply chamber, via a backpressure regulator based at least in part on the air pressure within the supply hopper.

17. The method of claim 11 , further comprising: measuring an air pressure within the supply hopper; and adjusting a flow of motive fluid through a Venturi pump connected to a pressure supply line, which flows the air to and / from the supply chamber, based at least in part on the air pressure within the supply hopper.

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