A system and method for measuring foam density

Abstract

A process and system for measuring foam density is provided. A weir is disposed within a casing such that the weir separates an interior of the casing into an inlet portion and an outlet portion. A pressure measurement conduit includes an inlet positioned for receipt the foam from the inlet portion of the interior. A pressure sensor is configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet of the pressure measurement conduit.

Description

[0001] A SYSTEM AND METHOD FOR MEASURING FOAM DENSITY

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application is related and claims right of priority to U.S. Provisional Application No. 63 / 601 ,386, 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, measuring density of the foam can be difficult. Moreover, foam is a two-phase fluid with both a liquid phase fluid and a gaseous phase fluid. Measuring the density of foam can depend not only on temperature for the liquid phase but also the pressure on the gaseous phase as well as a ratio of the liquid phase to the gaseous phase in the foam. The flow rate of foam in the system can also vary, which can make measuring density via fixed columns inaccurate.

[0008] A system for improved foam density measurement would be useful.

[0009] SUMMARY

[0010] In general, the present disclosure is directed to an improved process and system for measuring foam density. A density measurement assembly for a foam forming system includes a casing with an inlet for foam and an outlet for foam. The inlet of the casing is disposed on one side of a weir, and the outlet of the casing is disposed on the opposite side of the foam. Foam may enter the casing via the inlet of the casing by gravity or pressure. The weir may be configured such that the foam in the casing flows over the weir between the inlet and outlet of the casing. Thus, the weir may control the level of foam on the inlet side of the casing. A pressure measurement conduit may be coupled to the casing. Moreover, an inlet of the pressure measurement conduit may be positioned at the inlet side of the casing, e.g., such that foam on the inlet side of the casing (e.g., foam that has not flowed over the weir) may enter the pressure measurement conduit at the inlet of the pressure measurement conduit. The foam may flow through the pressure measurement conduit from the inlet of the pressure measurement conduit to an outlet of the pressure measurement conduit. A pressure sensor may be configured for measuring a pressure of the foam in the pressure measurement conduit. Moreover, the pressure sensor may measure the pressure of foam in the pressure measurement conduit at a measurement location, which may be located below the inlet and outlet of the pressure measurement conduit. For instance, the pressure measurement conduit may be U-shaped, and the pressure sensor may be configured for measuring the pressure of foam at the bottom of the U-shaped pressure measurement conduit. Based at least in part on pressure measurements from the pressure sensor, the density of the foam may be estimated. The density measurement assembly may advantageously provide a reliable, low-cost mechanism for measuring foam density in a foam forming system. Moreover, the density measurement assembly may advantageously provide accurate density measurements for various inlet flow rates for the foam and / or advantageously avoid foam decomposition during density measurements.

[0011] In one example embodiment, a density measurement assembly for a foam forming system, includes a casing with an inlet for foam into the casing and an outlet for the foam out of the casing. An interior of the casing is contiguous with ambient atmosphere. A weir is disposed within the casing such that the weir separates an interior of the casing into an inlet portion of the casing and an outlet portion of the casing. The inlet of the casing is positioned at the inlet portion of the interior such that the foam from the inlet flows into the inlet portion of the interior, and the outlet of the casing is positioned at the outlet portion of the interior such that the foam from the outlet portion of the interior flows into the outlet of the casing. The weir is configured such that the foam in the interior of the casing flows over the weir between the inlet portion and the outlet portion of the interior. A pressure measurement conduit includes an inlet positioned for receipt of the foam from the inlet portion of the interior and an outlet for the foam from the pressure measurement conduit. A pressure sensor is configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet and outlet of the pressure measurement conduit.

[0012] In another example embodiment, a foam forming system includes a headbox and a density measurement assembly configured for measuring a density of foam for the headbox. The density measurement assembly includes a casing with an inlet and outlet for the foam. An interior of the casing is contiguous with ambient atmosphere. A weir is disposed within the casing. The weir is configured such that the foam in the interior of the casing flows over the weir between an inlet and an outlet of the casing. A pressure measurement conduit includes an inlet for receiving the foam from the interior of the casing. The inlet of the pressure measurement conduit is positioned at an inlet-side of casing. A pressure sensor is configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet of the pressure measurement conduit.

[0013] Other features and aspects of the present disclosure are discussed in greater detail below.

[0014] 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 perspective view of a system and process according to an example embodiment of the present disclosure for measuring foam density during foam forming of a non-woven web;

[0019] FIG. 4 is a top, plan view of the example system and process of FIG. 3 for measuring foam density during foam forming of a non-woven web;

[0020] FIG. 5 is a front, elevation view of the example system and process of FIG. 3 for measuring foam density during foam forming of a non-woven web.

[0021] 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.

[0022] DEFINITIONS

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] As used herein, the term “foam half life” means the time elapsed until the half of the initial foam mass reverts to liquid water.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] The term "cross-machine direction" as used herein refers to the direction which is perpendicular to the machine direction defined above.

[0035] 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.

[0036] 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. 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.

[0037] As used herein the term "staple fibers" means discontinuous fibers made from synthetic polymers such as polypropylene, polyester, post consumer recycle (PCR) 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.

[0038] DETAILED DESCRIPTION

[0039] 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.

[0040] In general, the present disclosure is directed to a system and method for measuring density of foam in a foam forming system. For instance, a density measurement assembly may be installed in the foam forming system, and the density measurement assembly may receive a portion of a pressurized foam flow in the foam forming system. Moreover, foam from the foam forming system may be directed into a casing of the density measurement assembly. A weir within the casing may divide an interior of the casing into an inlet section and an outlet section. Foam may enter the casing at the inlet section of the interior. When the foam fills the inlet section of the interior, the foam may spill over the weir to the outlet section of the interior, where the foam can exit the casing. An interior of the casing may be contiguous with ambient atmosphere. Thus, the pressurized foam entering the casing may adjust to ambient pressure within the casing. The weir and open casing may thus assist with preventing or reducing flow-induced head pressure changes in a pressure measurement conduit. An inlet of the pressure measurement conduit is disposed at the inlet section of the interior, and an outlet of the pressure measurement conduit may be disposed below the inlet of the pressure measurement conduit. Thus, the pressure measurement conduit may have a head differential between the inlet and outlet of the pressure measurement conduit, which can cause a replenishing flow of foam from the inlet section of the interior through the pressure measurement conduit. A pressure sensor is configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet and outlet of the pressure measurement conduit. The pressure measurements from the pressure sensor may be used to calculate the density of the foam within the pressure measurement conduit. The system and process of the present disclosure can provide various advantages and benefits. For instance, the weir can advantageously convert variable foam flow from the foam forming system into nominally constant head pressure for the pressure measurement conduit. Thus, variations in the head pressure measured by the pressure sensor may be advantageously reduced. In addition, the flow of foam through the pressure measurement conduit may be controlled, e.g., by controlling a vertical distance between the inlet and outlet of the pressure measurement conduit, in order to further reduce variations in the head pressure measured by the pressure sensor. The density measurement assembly may also advantageously limit or prevent foam separation while measuring the density of foam, e.g., relative to conventional systems that measure fixed fluid columns.

[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 to adjust 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 FIGS. 3, 4, and 5, a system 200 for measuring foam density in 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 casing 210, a weir 220, a pressure measurement conduit 230, and a pressure sensor 250. The casing 210 include an inlet 211 for foam into the casing 210 and an outlet 213 for the foam out of the casing 210. For instance, foam from the web forming system 10 (FIGS. 1 and 2) may flow into an interior 212 of the casing 210 via the inlet 211 of the casing 210, and foam may flow out of the interior 212 of the casing 210 via the outlet 213 of the casing 210. As may be seen from the above, system 200 may take a portion of a pressurized flow of foam within the web forming system 10 for testing the density of the foam, as discussed in greater detail below.

[0074] In example embodiments, the casing 210 may include various walls for forming the casing 210 with the interior 212 for foam therein. In the example embodiment shown in FIGS. 3 through 5, the casing 210 may be generally cubic or rectangular prismatic. In other example embodiments, the casing 210 may be cylindrical or have other shapes depending upon the desired arrangement. The interior 212 of the casing 210 may be contiguous with ambient atmosphere. For instance, a top portion 218 of the casing 210 may be open such that the interior 212 of the casing 210 is contiguous with ambient atmosphere through the top portion 218 of the casing 210. As may be seen from the above, the foam within casing 210 may be allowed to reach atmospheric pressure.

[0075] The weir 220 is disposed within the casing 210. For instance, the weir 220 may be disposed within the interior 212 of the casing 210 such that the weir 220 separates the interior 212 of the casing

[0076] 210 into an inlet portion 214 of the casing 210 and an outlet portion 216 of the casing 210. The inlet

[0077] 211 of the casing 210 may be positioned at the inlet portion 214 of the interior 212. Foam may flow into the inlet portion 214 of the interior 212 via the inlet 211 of the casing 210. The inlet 211 of the casing 210 may be positioned at or adjacent a bottom of the inlet portion 214 of the interior 212 in certain example embodiments. The outlet 213 of the casing 210 may be positioned at the outlet portion 216 of the interior 212. Foam may flow out of the outlet portion 216 of the interior 212 via the outlet 213 of the casing 210. The outlet 213 of the casing 210 may be positioned at or adjacent a bottom of the outlet portion 216 of the interior 212 in certain example embodiments. As may be seen from the above, the inlet 211 and outlet 213 of the casing 210 may be positioned opposite each other about the weir 220. The weir 220 may be configured such that the foam in the interior 212 of the casing 210 flows over the weir 220 between the inlet portion 214 and the outlet portion 216 of the interior 212. For instance, the foam in the inlet portion 214 of the interior 212 may flow over a head 222 of the weir 220 into the outlet portion 216 of the interior 212. The head 222 of the weir 220 may correspond to the lowermost portion of the weir 220 at which foam is flowable from the inlet portion 214 of the interior 212 into the outlet portion 216 of the interior 212. In the illustrated example embodiment, the head 222 of the weir 220 may be linear. In other example embodiment, the head 222 of the weir 220 may have a curved shape, a piano-key or labyrinth shape, a triangular shape, or other shapes depending upon the desired arrangement. The weir 220 may include a wall facing the inlet portion 214 of the interior 212 and a wall facing the outlet portion 216 of the interior 212. The wall of the weir 220 facing the inlet portion 214 of the interior 212 may have a greater slope than the wall of the weir 220 facing the outlet portion 216 of the interior 212.

[0078] The weir 220 may advantageously control the level of foam at the inlet portion 214 of the interior 212, e.g., without requiring a large change in elevation to provide a substantial change in flow. Thus, e.g., the weir 220 may advantageously assist with converting variable inlet flow from the web forming system 10 into nominally constant head pressure for measuring the density of the foam. For example, foam from the inlet 211 of the casing 210 into the inlet portion 214 of the interior 212. When foam fills the inlet portion 214 of the interior 212, the foam may spill over the weir 220 into the outlet portion 216 of the interior 212, which funnels the foam to the outlet 213 of the casing 210. The foam filling the inlet portion 214 of the interior 212 may generate a constant head pressure in the pressure measurement conduit 230, which is measured to determine the density of the foam, as described in greater detail below. Thus, the weir 220 may advantageously assist with reducing or eliminating variability in a pressure-based, foam density measurement due to variable flow-induced head pressure change.

[0079] The pressure measurement conduit 230 includes an inlet 232 positioned for receipt of foam from the inlet portion 214 of the interior 212 and also includes an outlet 236 for the foam from the pressure measurement conduit 230. The inlet 232 of the pressure measurement conduit 230 may be positioned above the outlet 236 of the pressure measurement conduit 230. Such relative positioning between the inlet 232 and outlet 236 of the pressure measurement conduit 230 may generate a head differential, which can cause foam to flow from the inlet portion 214 of the interior 212 into the pressure measurement conduit 230 when the foam fills the inlet portion 214 of the interior 212. Thus, foam from the inlet portion 214 of the interior 212 may enter the pressure measurement conduit 230 at the inlet 232 of the pressure measurement conduit 230 and flow through the pressure measurement conduit 230 to the outlet 236 of the pressure measurement conduit 230. The pressure measurement conduit 230 may thus receive foam from the inlet portion 214 of the interior 212 for measurement by the pressure sensor 250, and the outlet 236 of the pressure measurement conduit 230 may direct excess foam out of the pressure measurement conduit 230. In example embodiments, the controlled flow of foam through the pressure measurement conduit 230 may advantageously assist with reducing or eliminating variability in the pressure-based, foam density measurement due to variable flow-induced head pressure change.

[0080] In example embodiments, the inlet 232 of the pressure measurement conduit 230 may be positioned above the inlet 211 of the casing 210 at the inlet portion 214 of the interior 212. As shown in FIGS. 4 and 5, the inlet 232 of the pressure measurement conduit 230 may be positioned on the weir 220 below the head 222 of the weir 220 in some example embodiments. As an example, the inlet 232 of the pressure measurement conduit 230 may be positioned no less than five centimeters (5 cm), such as no less ten centimeters (10 cm), such as no less than fifteen centimeters (15 cm), from the head 222 of the weir 220. As another example, the inlet 232 of the pressure measurement conduit 230 may be positioned no more than fifty centimeters (50 cm), such as no more forty centimeters (40 cm), such as no more than thirty centimeters (30 cm), from the head 222 of the weir 220.

[0081] An interior 242 of the pressure measurement conduit 230 may be contiguous with ambient atmosphere. For example, the pressure measurement conduit 230 may include a discharge opening 240. The discharge opening 240 may be positioned between the inlet 232 and outlet 236 of the pressure measurement conduit 230. For instance, the discharge opening 240 may be disposed on a branch line from the pressure measurement conduit 230 proximate the inlet 232 of the pressure measurement conduit 230. In example embodiments, the discharge opening 240 may be disposed below the inlet 232 of the pressure measurement conduit 230, and the discharge opening 240 may be disposed above the outlet 236 of the pressure measurement conduit 230. The discharge opening 240 may include an opening to ambient atmosphere. Thus, the discharge opening 240 may limit or prevent siphoning of foam from the inlet portion 214 of the interior 212.

[0082] In example embodiments, the outlet 236 of the pressure measurement conduit 230 may be configured for directing the foam from the pressure measurement conduit 230 into a tank, such as the separator tank 150 (FIG. 2). The outlet 213 of the casing 210 may also be configured for directing the foam from the outlet portion 216 of the casing 210 into the tank, such as the separator tank 150. Thus, e.g., both the outlet 236 of the pressure measurement conduit 230 and the outlet 213 of the casing 210 may be positioned and oriented for directing foam into the same tank. For instance, both the outlet 236 of the pressure measurement conduit 230 and the outlet 213 of the casing 210 may be positioned over the separator tank 150 such that foam falls into the separator tank 150 from the outlets 213, 236. Thus, the portion of the pressurized flow of foam within the web forming system 10 removed by the system 200 for testing the density of the foam may be recombined into the pressurized flow of foam downstream from the system 200.

[0083] As noted above, the outlet 236 of the pressure measurement conduit 230 may be positioned below the inlet 232 of the pressure measurement conduit 230. As an example, the outlet 236 of the pressure measurement conduit 230 may be positioned no less than two centimeters (2 cm), such as no less five centimeters (5 cm), such as no less than seven centimeters (7 cm), below the inlet 232 of the pressure measurement conduit 230. As another example, the outlet 236 of the pressure measurement conduit 230 may be positioned no more forty centimeters (40 cm), such as no more than twenty centimeters (20 cm), such as no more than fifteen centimeters (15 cm), such as no more than ten centimeters (10 cm), below the inlet 232 of the pressure measurement conduit 230.2

[0084] In example embodiments, the outlet 236 of the pressure measurement conduit 230 may be adjustable such that a vertical distance between the inlet 232 and outlet 236 of the pressure measurement conduit 230 is adjustable. For example, the pressure measurement conduit 230 may be rotatable in order to adjust the vertical distance between the inlet 232 and outlet 236 of the pressure measurement conduit 230. As another example, a sleeve may be mounted on the pressure measurement conduit 230 at the outlet 236 to adjust the vertical distance between the inlet 232 and outlet 236 of the pressure measurement conduit 230. Adjusting the vertical distance between the inlet 232 and outlet 236 of the pressure measurement conduit 230 may advantageously assist with changing a flow rate of the foam through the pressure measurement conduit 230. Thus, e.g., the flow rate of the foam through the pressure measurement conduit 230 may be controlled to a selected speed to reduce or eliminate variation in pressure-based, foam density measurements.

[0085] The pressure sensor 250 may be configured for measuring a pressure of the foam in the pressure measurement conduit 230. For example, the pressure sensor 250 may be configured for measuring the pressure of foam at a measurement location 234 in the pressure measurement conduit 230. Flowing foam through the pressure measurement conduit 230 while the pressure sensor 250 may measure the pressure of the foam in the pressure measurement conduit 230 can advantageously maintain stability of the foam during measurement.

[0086] The measurement location 234 may be disposed located below the inlet 232 and outlet 236 of the pressure measurement conduit 230. As an example, the measurement location 234 may be disposed at or adjacent a lowermost portion of the pressure measurement conduit 230. As shown in FIG. 3, at least a portion of the pressure measurement conduit 230 may be U-shaped between the inlet 232 and outlet 236 of the pressure measurement conduit 230. For example, the pressure measurement conduit 230 may include a U-shaped section 235 between the inlet 232 and outlet 236 of the pressure measurement conduit 230. The measurement location 234 may be disposed at or adjacent a lowermost portion of the U-shaped section 235.

[0087] The pressure measurement conduit 230 may also include a drain tap 238. Foam and other fluids may be removed from the pressure measurement conduit 230 through the drain tap 238. The drain tap 238 may be disposed at or adjacent the lowermost portion of the pressure measurement conduit 230. For example, the drain tap 238 may be disposed at or adjacent a lowermost portion of the U-shaped section 235.

[0088] As shown in FIG. 3, system 200 may also include or be in operative communication with a processing device or a controller 260 that may be generally configured to facilitate operation of at least a portion of system 200. In this regard, pressure sensor 250 and other components of system 200 may be in communication with controller 260. Thus, e.g., the controller 260 may receive inputs from the pressure sensor 250 and may determine the density of the foam in the pressure measurement conduit 230 based at least in part on the inputs from the pressure measurement conduit 230. The pressure sensor 250 and other components of system 200 may be in communication with controller 260 via, for example, one or more signal lines or shared communication buses. In this manner, Input / Output (“I / O”) signals may be routed between controller 260 and various operational components of system 200.

[0089] 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 260 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.

[0090] Controller 260 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.

[0091] For example, controller 260 may be operable to execute programming instructions or microcontrol code associated with operation of the 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, measuring foam density via signals from the pressure sensor 250, etc. Moreover, it should be noted that controller 260 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 260.

[0092] 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 260. The data may include, for instance, data to facilitate performance of methods described herein. The data may be stored locally (e.g., on controller 260) 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 260 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 260 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 260, 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.

[0093] As noted above, the controller 260 may be configured for receiving data from the pressure sensor 250. The data from the pressure sensor 250 may correspond to pressure measurements for the foam in the pressure measurement conduit 230 at the measurement location 234. Moreover, the pressure sensor 250 may measure the head pressure generated by the foam below the inlet 232 and outlet 236 of the pressure measurement conduit 230, and the pressure sensor 250 may output data to the controller 260 corresponding to the pressure measurements.

[0094] The controller 260 may also compute a density of the foam in the pressure measurement conduit 230 based at least in part on the pressure measurement from the pressure sensor 250. For example, the density of the foam in the pressure measurement conduit 230 may be directly proportional to the pressure of the foam in the pressure measurement conduit 230. To calibrate the density measurements via the pressure measurement from the pressure sensor 250, water may be flowed through the pressure measurement conduit 230, and the pressure measurement from the pressure sensor 250 may be taken. The pressure measurement taken by the pressure sensor 250 while water flows through the pressure measurement conduit 230 may thus correspond to a first calibration point due to the known density of water. Next, the foam (e.g., the lowest density foam that will run through system 200) may be flowed through the pressure measurement conduit 230, and the pressure measurement from the pressure sensor 250 may be taken. The density of the foam may be determined via manual density measurements, such as by weighing a fixed volume of foam to calculate the density of the foam, to provide a second calibration point. A linear interpolation of the first and second calibration points may be used to calculate the foam densities corresponding to other pressure measurements from the pressure sensor 250 during operation of the system 200.

[0095] As may be seen from the above, the system 200 may advantageously measure the pressure of a replenishing flow of foam. Thus, e.g., the system 200 may accurately measure the densities of foam flowing through the system 200 with high air contents, such as air contents approaching sixty- five percent (65%). Moreover, the system 200 may be vertically compact, e.g., such that a total height of the system 200 is less than one and a half meters (1 .5 m), such as less than one and two-tenths meters (1 .2 m). The system 200 may also have a high resolution. For instance, the system 200 may be accurate to less than two percent density with a feed flow turndown ratio in excess of 100:1 . In general, the system 200 may provide a low-cost, proven mechanism for density measurement within foam forming systems. The system 200 may include various features for reducing or preventing foam density measurement variation due to variable inlet flow and foam decomposition.

[0096] 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. EXAMPLE EMBODIMENTS

[0097] First example embodiment: A density measurement assembly for a foam forming system, comprising: a casing comprising an inlet for foam into the casing and an outlet for the foam out of the casing, an interior of the casing being contiguous with ambient atmosphere; a weir disposed within the casing such that the weir separates the interior of the casing into an inlet portion of the casing and an outlet portion of the casing, the inlet of the casing positioned at the inlet portion of the interior such that the foam from the inlet flows into the inlet portion of the interior, the outlet of the casing positioned at the outlet portion of the interior such that the foam from the outlet portion of the interior flows into the outlet of the casing, the weir configured such that the foam in the interior of the casing flows over the weir between the inlet portion and the outlet portion of the interior; a pressure measurement conduit comprising an inlet positioned for receipt of the foam from the inlet portion of the interior and an outlet for the foam from the pressure measurement conduit; and a pressure sensor configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet and outlet of the pressure measurement conduit.

[0098] Second example embodiment: The density measurement assembly of the first example embodiment, wherein the inlet of the pressure measurement conduit is positioned above the outlet of the pressure measurement conduit.

[0099] Third example embodiment: The density measurement assembly of the first example embodiment or the second example embodiment, wherein the outlet of the pressure measurement conduit is adjustable such that a vertical distance between the inlet and outlet of the pressure measurement conduit is adjustable.

[0100] Fourth example embodiment: The density measurement assembly of any one of first through third example embodiments, wherein an interior of the pressure measurement conduit is contiguous with ambient atmosphere.

[0101] Fifth example embodiment: The density measurement assembly of any one of the first through the fourth example embodiments, wherein the pressure measurement conduit further comprises a discharge opening positioned above the outlet of the pressure measurement conduit.

[0102] Sixth example embodiment: The density measurement assembly of any one of first through the fifth example embodiments, wherein the inlet of the pressure measurement conduit is positioned on the weir below a head of the weir. Seventh example embodiment: The density measurement assembly of any one of the first through sixth example embodiments, wherein at least a portion of the pressure measurement conduit is U-shaped between the inlet and outlet of the pressure measurement conduit.

[0103] Eighth example embodiment: The density measurement assembly of any one of the first through seventh example embodiments, wherein the measurement location is disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit.

[0104] Nineth example embodiment: The density measurement assembly of any one of the first through eighth example embodiments, wherein the pressure measurement conduit further comprises a drain tap disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit.

[0105] Tenth example embodiment: The density measurement assembly of any one of the first through nineth example embodiments, further comprising a controller in signal communication with the pressure sensor, the controller configured for: receiving data from the pressure sensor corresponding to a pressure measurement; and computing a density of the foam in the pressure measurement conduit based at least in part on the pressure measurement.

[0106] Eleventh example embodiment: The density measurement assembly of any one of the first through tenth example embodiments, wherein the outlet of the casing and the outlet of the pressure measurement conduit are configured for directing foam into a tank.

[0107] Twelfth example embodiment: A foam forming system, comprising: a headbox; and a density measurement assembly configured for measuring a density of foam for the headbox, the density measurement assembly comprising a casing comprising an inlet and outlet for the foam, an interior of the casing being contiguous with ambient atmosphere, a weir disposed within the casing, the weir configured such that the foam in the interior of the casing flows over the weir between an inlet and an outlet of the casing, a pressure measurement conduit comprising an inlet for receiving the foam from the interior of the casing, the inlet of the pressure measurement conduit positioned at an inlet-side of casing, and a pressure sensor configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet of the pressure measurement conduit.

[0108] Thirteenth example embodiment: The foam forming system of the twelfth example embodiment, wherein the inlet of the pressure measurement conduit is positioned above the outlet of the pressure measurement conduit.

[0109] Fourteenth example embodiment: The foam forming system of either the twelfth example embodiment or the thirteenth example embodiment, wherein the outlet of the pressure measurement conduit is adjustable such that a vertical distance between the inlet and outlet of the pressure measurement conduit is adjustable.

[0110] Fifteenth example embodiment: The foam forming system of any one of the twelfth through fourteenth example embodiments, wherein an interior of the pressure measurement conduit is contiguous with ambient atmosphere.

[0111] Sixteenth example embodiment: The foam forming system of any one of the twelfth through fifteenth example embodiments, wherein the pressure measurement conduit further comprises a discharge opening positioned above the outlet of the pressure measurement conduit.

[0112] Seventeenth example embodiment: The foam forming system of any one of the twelfth through sixteenth example embodiments, wherein the inlet of the pressure measurement conduit is positioned on the weir below a head of the weir.

[0113] Eighteenth example embodiment: The foam forming system of any one of the twelfth through seventeenth example embodiments, wherein at least a portion of the pressure measurement conduit is U-shaped between the inlet and outlet of the pressure measurement conduit.

[0114] Nineteenth example embodiment: The foam forming system of any one of the twelfth through eighteenth example embodiments, wherein the measurement location is disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit.

[0115] Twentieth example embodiment: The foam forming system of any one of the twelfth through nineteenth example embodiments, wherein the pressure measurement conduit further comprises a drain tap disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit. Twenty-first example embodiment: The foam forming system of any one of the twelfth through twentieth example embodiments, further comprising a controller in signal communication with the pressure sensor, the controller configured for: receiving data from the pressure sensor corresponding to a pressure measurement; and computing a density of the foam in the pressure measurement conduit based at least in part on the pressure measurement.

[0116] Twenty-second example embodiment: The foam forming system of any one of the twelfth through twenty-first example embodiments, further comprising a tank, the outlet of the casing and the outlet of the pressure measurement conduit are arranged for directing the foam into the tank. Twenty-third example embodiment: A method for measuring foam density within a foam forming process, substantially as described herein.

[0117] Twenty-fourth example embodiment: A system for measuring foam density within a foam forming process, substantially as described herein.

Claims

What Is Claimed:1 . A density measurement assembly for a foam forming system, comprising: a casing comprising an inlet for foam into the casing and an outlet for the foam out of the casing, an interior of the casing being contiguous with ambient atmosphere; a weir disposed within the casing such that the weir separates the interior of the casing into an inlet portion of the casing and an outlet portion of the casing, the inlet of the casing positioned at the inlet portion of the interior such that the foam from the inlet flows into the inlet portion of the interior, the outlet of the casing positioned at the outlet portion of the interior such that the foam from the outlet portion of the interior flows into the outlet of the casing, the weir configured such that the foam in the interior of the casing flows over the weir between the inlet portion and the outlet portion of the interior; a pressure measurement conduit comprising an inlet positioned for receipt of the foam from the inlet portion of the interior and an outlet for the foam from the pressure measurement conduit; and a pressure sensor configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet and outlet of the pressure measurement conduit.

2. The density measurement assembly of claim 1 , wherein the inlet of the pressure measurement conduit is positioned above the outlet of the pressure measurement conduit.

3. The density measurement assembly of claim 1 , wherein the outlet of the pressure measurement conduit is adjustable such that a vertical distance between the inlet and outlet of the pressure measurement conduit is adjustable.

4. The density measurement assembly of claim 1 , wherein an interior of the pressure measurement conduit is contiguous with ambient atmosphere.

5. The density measurement assembly of claim 1 , wherein the pressure measurement conduit further comprises a discharge opening positioned above the outlet of the pressure measurement conduit.

6. The density measurement assembly of claim 1 , wherein the inlet of the pressure measurement conduit is positioned on the weir below a head of the weir.

7. The density measurement assembly of claim 1 , wherein at least a portion of the pressure measurement conduit is U-shaped between the inlet and outlet of the pressure measurement conduit.

8. The density measurement assembly of claim 7, wherein the measurement location is disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit.

9. The density measurement assembly of claim 7, wherein the pressure measurement conduit further comprises a drain tap disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit.

10. The density measurement assembly of claim 1 , further comprising a controller in signal communication with the pressure sensor, the controller configured for: receiving data from the pressure sensor corresponding to a pressure measurement; and computing a density of the foam in the pressure measurement conduit based at least in part on the pressure measurement.11 . The density measurement assembly of claim 1 , wherein the outlet of the casing and the outlet of the pressure measurement conduit are configured for directing foam into a tank.

12. A foam forming system, comprising: a headbox; and a density measurement assembly configured for measuring a density of foam for the headbox, the density measurement assembly comprising a casing comprising an inlet and outlet for the foam, an interior of the casing being contiguous with ambient atmosphere, a weir disposed within the casing, the weir configured such that the foam in the interior of the casing flows over the weir between an inlet and an outlet of the casing, a pressure measurement conduit comprising an inlet for receiving the foam from the interior of the casing, the inlet of the pressure measurement conduit positioned at an inlet-side of casing, and a pressure sensor configured for measuring a pressure of the foam in the pressure measurement conduit at a measurement location located below the inlet of the pressure measurement conduit.

13. The foam forming system of claim 12, wherein the inlet of the pressure measurement conduit is positioned above the outlet of the pressure measurement conduit.

14. The foam forming system of claim 12, wherein the outlet of the pressure measurement conduit is adjustable such that a vertical distance between the inlet and outlet of the pressure measurement conduit is adjustable.

15. The foam forming system of claim 12, wherein an interior of the pressure measurement conduit is contiguous with ambient atmosphere.

16. The foam forming system of claim 12, wherein the pressure measurement conduit further comprises a discharge opening positioned above the outlet of the pressure measurement conduit.

17. The foam forming system of claim 12, wherein the inlet of the pressure measurement conduit is positioned on the weir below a head of the weir.

18. The foam forming system of claim 12, wherein at least a portion of the pressure measurement conduit is U-shaped between the inlet and outlet of the pressure measurement conduit.

19. The foam forming system of claim 18, wherein the measurement location is disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit.

20. The foam forming system of claim 18, wherein the pressure measurement conduit further comprises a drain tap disposed proximate a bottom of the U-shaped portion of the pressure measurement conduit.21 . The foam forming system of claim 12, further comprising a controller in signal communication with the pressure sensor, the controller configured for: receiving data from the pressure sensor corresponding to a pressure measurement; and computing a density of the foam in the pressure measurement conduit based at least in part on the pressure measurement.

22. The foam forming system of claim 12, further comprising a tank, the outlet of the casing and the outlet of the pressure measurement conduit are arranged for directing the foam into the tank.

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