Gypsum slurry mixer output canister

Abstract

A gypsum slurry mixer output canister (10) is provided that includes a canister housing (16) having an upper end (18) and an opposite lower end (20) and defining a canister interior (22), a cover (26) secured to the upper end (18), a slurry inlet (30) in operative relationship with the upper end (18), and a spiral block (46) associated with the upper end (18) and having a helical flow surface (52) dependent from the interior (22). A flow distributor (60) is secured to the lower end (20) and in fluid communication with the interior (22), and a slurry outlet (62) is defined by the lower canister housing end (20).

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of priority from U.S. Provisional Patent Application No. 62 / 926,734, filed on October 28, 2019, the entire disclosure of which is incorporated herein by reference.

Background Art

[0002] The present invention relates to improvements in gypsum slurry manufacturing apparatus, and more particularly to an improved apparatus for distributing slurry from a slurry mixer to a movable conveyor belt during the production of gypsum wallboard.

[0003] The basic technology of gypsum wallboard manufacturing is disclosed in U.S. Pat. Nos. 1,500,452, 2,207,339, and 4,009,062, all of which are incorporated herein by reference. Gypsum products are produced by dispersing calcined gypsum in water to form a slurry, then casting the slurry into a mold or surface of a desired shape, and reacting the calcined gypsum (calcium sulfate hemihydrate or anhydride) with water to form hydrated gypsum (calcium sulfate dihydrate), thereby coagulating the slurry to form hardened gypsum. It is also well known to produce lightweight gypsum products by mixing aqueous foam into the slurry to generate air bubbles. This results in a desired distribution of voids in the coagulated gypsum product if the air bubbles do not leak out of the slurry before the hardened gypsum is formed. The voids often reduce the density of the final product, often referred to as "foamed gypsum".

[0004] A gypsum wallboard slurry mixer typically includes a housing that defines a mixing chamber having an inlet for receiving calcined gypsum, water, and other additives well known in the art. The mixer includes an impeller or other type of agitator configured to agitate the contents to be mixed into the slurry. A discharge gate or extractor controls the flow of the slurry from the mixer to the distribution system. Foam and / or other additives are typically added to the slurry after the slurry is substantially mixed, through a foam injection port in the outer sidewall of the discharge gate through which an aqueous foam or other desired additive, such as a retarder, accelerator, dispersant, starch, binder, and polyphosphates, sodium trimetaphosphate, etc., an intensity enhancing product passes. Suitable gypsum mixers are described in U.S. Patent Nos. 5,643,510, 5,683,635, 6,494,609, and 6,874,930, all of which are incorporated by reference.

[0005] A common problem in the design of gypsum wallboard slurry mixers is that the slurry must be kept moving and obstacles to free flow, or places where the slurry can collect and tend to coagulate prematurely, must be avoided. Such premature coagulation creates lumps of gypsum, which form irregularities in the resulting wallboard panels. One such device designed to prevent premature coagulation of the slurry is disclosed in U.S. Patent No. 8,475,762, which is incorporated by reference. Such a device, called a boot, maintains the slurry flow rate within the mixer while providing a desired distribution pattern. It is known to provide a canister between the mixer and the boot to maintain the slurry flow rate and prevent a stagnant flow zone in the flow path from the mixer to the wallboard conveyor line.

[0006] In gypsum slurry mixers, conventionally, the canister has been attached to the front of the mixer and no adjustments have been made to be able to vary the amount within the mixer. Problems for system designers include the routing, diameter, and connection of various hose lines to the area between the mixer and the boot.

[0007] Accordingly, there is a need for an improved slurry distribution apparatus that maintains slurry flow rate and improves the flow characteristics from the mixer to the conveyor line. SUMMARY OF THE INVENTION

[0008] The above need is met, or exceeded, by this improved mixer output cannister that allows slurry to be discharged from the mixer, shortens the required length of the hose, and maintains a level that allows for a better blend of foam and slurry before transitioning to the boot. This cannister is essentially an alternative to the transition from the hose to the boot that facilitates the routing of the mixer output discharge hose and allows for an improved blend of foam with the slurry.

[0009] This mixer cannister simplifies slurry distribution. A higher slurry output rate is achieved to improve production results. The cannister includes a generally cylindrical housing with a cap, and a spiral block that is fixed to the cap and that, depending on the cap, defines a reverse spiral flow surface. The spiral block is configured and arranged to create a spiral slurry flow within the cannister, which has a velocity sufficient to prevent premature coagulation and undesirable agglomeration. A flow distributor that is vertically spaced from the spiral block converts the spiral slurry flow to a desired linear flow, which is more suitable for direction to the outlet boot and ultimately deposition onto a wallboard conveyor line on a single sheet of paper.

[0010] In a preferred embodiment, the cannister housing has a height of about 8.5 inches, the spiral block has a height of about 4.5 inches, and thus occupies more than 50% of the height of the housing. Further, the flow distributor has a preferred height of about 3 inches, such that the flow chamber defined between the spiral block and the flow distributor has a relatively short height of about 1.0 inch. For the purposes of this application, "about" refers to ±1 inch in the recited dimensions.

[0011] More specifically, there is provided a gypsum slurry mixer outlet canister including a canister housing having an upper end, an opposite lower end, and defining the interior of the canister, a cover fixed to the upper end, a slurry inlet in operative relation with the upper end, and a spiral block associated with the upper end and having a spiral flow surface depending on the interior. The flow distributor is fixed to the lower end and in fluid communication with the interior, and the slurry outlet is defined by the lower canister housing end.

[0012] In one embodiment, the upper housing end has a radially extending flange for accommodating attachment of the cover, and the spiral block is fastened to the lower surface of the cover. Also, the slurry inlet has a non-circular cross-section where the inlet merges with the housing, and in a preferred embodiment, the slurry inlet has a rectangular cross-section where the inlet merges with the housing.

[0013] In one embodiment, the spiral block has a vertical inlet wall in fluid communication with the slurry inlet and forming an end of the spiral flow surface. Preferably, the spiral flow surface defines a 360° arc. In one embodiment, the spiral block has a vertical height of about 4.5 inches, ±1 inch, and the housing has a vertical height of about 8.5 inches ±1 inch. Further, it is preferred that the housing has a vertical height of about 10.5 inches ±1 inch.

[0014] In one embodiment, the flow distributor defines an outlet opening having a plurality of lobes in fluid communication with a central opening. Also, the flow distributor includes a plurality of radially inwardly projecting teeth defining a plurality of lobe-shaped recesses in communication with the central opening. The teeth preferably define an internally tapered geometry where the tips of the teeth form the innermost circumference of the central opening. Also, the vertical height of the flow distributor is about 3.0 inches, ±1 inch. In a preferred embodiment, the spiral block occupies about 50% of the vertical height of the housing.

[0015] In another embodiment, a gypsum slurry mixer outlet canister is provided that includes a canister housing having an upper end, an opposite lower end, and defining an interior of the canister, a cover fixed to the upper end, a slurry inlet fixed to the upper end, and a spiral block associated with the upper end and having a spiral flow surface depending on the interior. The flow distributor is fixed to the lower end and in fluid communication with the interior. The slurry outlet is defined by the lower canister housing end, the spiral block has a vertical height that occupies about 50% of the height of the housing, and the flow distributor has a vertical height of about 3 inches.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0017] Referring now to FIGS. 1-5, a first embodiment of the present slurry mixer output canister is generally indicated at 10. Canister 10 is configured and arranged for connection between and fluid communication with mixer output hose 12 and mixer boot inlet 14. A suitable mixer outlet boot is disclosed in U.S. Patent No. 8,475,762, which is incorporated by reference. The flow direction of the gypsum slurry and mixing foam from the mixer is indicated by arrow "A".

[0018] Canister 10 preferably includes a canister housing 16 that is cylindrical and tubular, although other tubular shapes (including but not limited to polygonal) are contemplated. The upper end 18 of housing 16 is opposite the lower end 20, and the canister interior 22 is defined within the housing. A radially extending flange 24 is preferably provided at the upper end 18 to accommodate secure attachment of cover 26. Attachment of cover 26 to flange 24 is accomplished by fasteners 28, preferably threaded bolts, as is well known in the art.

[0019] Vertically positioned below the flange 24 is a slurry inlet 30 that is in operative relation with the upper end 18 of the canister housing 16. At the free end 32, the slurry inlet 30 has a circular cross-section 34 for connection to the mixer output hose 12. However, as the inlet 30 proceeds towards its connection to the canister housing 16, the inlet has a non-circular cross-section 36 where the inlet merges with the housing. The inlet 30 also has an arcuate edge 38 where the inlet preferably joins the cylindrical canister housing 16. Thus, the inlet 30 is in fluid communication with an opening 40 within the canister housing 16. In a preferred embodiment, the slurry inlet 30 is secured to the canister housing 16 by welding, fasteners, and / or chemical adhesives, as is well known in the art. Another feature of the canister housing 16 is at least one mounting bar 42 secured to the exterior 44 of the housing to facilitate attachment of the canister 10 to a corresponding mixer infrastructure (not shown).

[0020] Next, referring to FIGS. 1, 3, 6, and 7, an important feature of the present canister 10 is a spiral block 46 that creates a slurry flow path that follows the internal profile of the housing 16, depending on the canister interior 22. Also preferably, the spiral block 46, fastened to the lower surface 48 of the cover 26 by fasteners or the like, fills the canister interior 22 above the opening 40, or the region between the cover and the opening. Thus, the presence of the spiral block 46 prevents an undesirable collection of stray slurry that could prematurely coagulate and create a mass within the resulting wall panel.

[0021] More specifically, the spiral block 46 has a generally cylindrical mounting end 50 configured to attach to the lower surface 48 of the cover 26. Opposite the mounting end is a spiral flow surface 52 that preferably extends in a complete 360° arc, although a portion of the surface is displaced vertically from the other portion. As seen in FIG. 1, when the spiral block 46 is attached to the cover 26, the block depends on the canister interior 22.

[0022] As shown in FIG. 6, the spiral block 46 has a vertical inlet wall 54 that is in fluid communication with the slurry inlet 30 and the housing opening 40. Also, the inlet wall 54 forms the end of the spiral flow surface 52. The upper edge 56 of the wall 54 defines the upper vertical limit of the spiral flow surface 52, which, as seen in FIG. 6, is actually the lower limit of the surface when the spiral block 46 is inverted and inserted into the canister interior 22. Also, the vertical inlet wall 54 is aligned with one edge of the opening 40 (FIG. 3). The incoming slurry passes through the opening 40 and is directed by the vertical inlet wall 54 to initiate a circular or spiral flow within the interior 22 due to the configuration of the spiral flow surface 52 of the dependent spiral block 46.

[0023] Next, referring to FIGS. 2 and 8 - 10, another component of the mixer canister 10 is a flow distributor 60 configured and arranged to receive the generally circular or spiral flow created by the spiral block 46 and re - orient the flow to be more linear or laminar. The latter flow is more desirable as is well known in the art because the slurry is discharged from the boot and flows over the moving web on the wallboard production conveyor.

[0024] In a preferred embodiment, the flow distributor 60 is fixedly positioned at the lower end 20 of the canister housing 16 and defines a slurry outlet 62. An annular groove 64 on the flow distributor 60 is engaged by at least one fastener 66, such as a set screw (FIG. 2), to secure the flow distributor to the canister housing 16. Also, the flow distributor 60 is in fluid communication with the canister interior 22.

[0025] More specifically, the flow distributor 60 is an integrally formed part by machining, casting, etc., and defines an outlet opening 68 having a plurality of circumferentially arranged lobes 70 in fluid communication with the central opening 72. The lobes 70 are defined by a plurality of radially inwardly projecting teeth 74 (FIG. 9), and each lobe is located between two adjacent teeth. Further, the teeth 74 define an internally tapered geometry such that the tip 76 of the teeth forms the innermost circumference of the central opening 72. As seen in FIG. 10, the wall 78 of the flow distributor 60 defines a generally wedge-shaped cross-section, and the tip 76 of the teeth 74 forms the tip of the wedge. Also, the teeth 74 are formed from an upper plate portion 80 and a lower plate portion 82 that taper towards the tip 76. In a preferred embodiment, the flow distributor 60 has a vertical height defined by the wall 78, preferably 3.0 inches ± 1 inch in height.

[0026] Referring now to FIGS. 11-21, an alternative embodiment of the present slurry mixer output canister is generally designated 100. Components shared with the canister 10 are marked with the same reference numerals. One of the main differences between the two canisters 10, 100 is that the canister housing 16 within the canister 10 has a vertical height of approximately 10 inches ± 1 inch. However, in the canister 100, the canister housing 102 has a vertical height of approximately 8.5 inches ± 1 inch. Also, since the spiral block 104 has a vertical height of approximately 4.5 inches ± 1 inch, the spiral block has a vertical height that occupies approximately 50% of the height of the housing 102.

[0027] Another feature of the canister 100 is that since the flow distributor 60 has a vertical height of about 3.0 inches ± 1 inch, about 1.0 inch remains inside the canister 22. Thus, the flow chamber 106 (FIG. 13) is defined inside the canister 22 between the spiral block 104 and the flow distributor 60 and has a vertical height of about 1.0 inch. The arrangement of this component within the housing 102 results in an improvement in performance, including the slurry velocity through the canister 100, such that the flow of slurry through the canister is accelerated and the slurry volume is maintained, and it has been found that unwanted agglomeration or premature coagulation is significantly reduced compared to conventional slurry dispensers in wall panel production lines.

[0028] Although specific embodiments of this gypsum slurry mixer output canister are described herein, it will be understood by those skilled in the art that changes and modifications can be made without departing from the invention in a broader sense as described in the following claims. [Appendix 1] A gypsum slurry mixer outlet cannister, having an upper end, an opposite lower end, and a cannister housing defining an interior thereof, a cover fixed to the upper end, a slurry inlet in operative relation with the upper end, a spiral block associated with the upper end and having a spiral flow surface depending on the interior, a flow distributor fixed to the lower end and in fluid communication with the interior, and a slurry outlet defined by the lower cannister housing end. A gypsum slurry mixer outlet cannister comprising the above components. [Appendix 2] The cannister according to Appendix 1, wherein the upper end has a radially extending flange for accommodating attachment of the cover. [Appendix 3] The cannister according to Appendix 1, wherein the slurry inlet has one of a non-circular cross-section and a rectangular cross-section where the inlet merges with the housing. [Appendix 4] The cannister according to Appendix 1, wherein the spiral block is fixed to the lower surface of the cover. [Appendix 5] The cannister according to Appendix 1, wherein the spiral block has a vertical inlet wall in fluid communication with the slurry inlet and forming an end of the spiral flow surface, and preferably the spiral block occupies about 50% of the vertical height of the housing. [Appendix 6] The cannister according to Appendix 1, wherein the spiral flow surface defines a 360° arc. [Appendix 7] The cannister according to Appendix 1, wherein the spiral block has one of a vertical height of about 4.5 inches ± 1 inch, about 8.5 inches ± 1 inch, and about 10 inches ± 1 inch. [Appendix 8] The cannister according to Appendix 1, wherein the flow distributor defines an outlet opening having a plurality of lobes in fluid communication with a central opening. [Appendix 9] The cannister according to Appendix 1, wherein the flow distributor includes a plurality of radially inwardly projecting teeth defining a plurality of lobed recesses in communication with a central opening. [Appendix 10] The cannister according to Appendix 9, wherein the teeth define an internal geometry that tapers radially inwardly such that the tips of the teeth form the innermost circumference of the central opening.

Claims

1. A gypsum slurry mixer output canister, comprising: a canister housing having an upper end, an opposite lower end, and defining an interior of the canister; a cover fixed to the upper end; a slurry inlet in fluid communication with the upper end; a spiral block located at the upper end and having a spiral flow surface that descends within the canister; a flow distributor fixed to the lower end and in fluid communication with the interior of the canister; a slurry outlet defined by the lower end; wherein the flow distributor defines an outlet opening having a plurality of lobes in fluid communication with a central opening; A gypsum slurry mixer output canister.

2. A gypsum slurry mixer output canister, comprising: a canister housing having an upper end, an opposite lower end, and defining an interior of the canister; a cover fixed to the upper end; a slurry inlet in fluid communication with the upper end; a spiral block located at the upper end and having a spiral flow surface that descends within the canister; a flow distributor fixed to the lower end and in fluid communication with the interior of the canister; a slurry outlet defined by the lower end; wherein the flow distributor includes a plurality of teeth projecting radially inwardly and defining a plurality of lobe-shaped recesses in communication with a central opening; A gypsum slurry mixer output canister.

3. The canister according to claim 1 or 2, wherein the upper end has a radially extending flange for accommodating attachment of the cover.

4. The canister according to claim 1 or 2, wherein the slurry inlet has one of a non-circular cross-section and a rectangular cross-section where the inlet merges with the housing.

5. The canister according to claim 1 or 2, wherein the spiral block is fixed to the lower surface of the cover.

6. The canister according to claim 1 or 2, wherein the spiral block has a vertical inlet wall in fluid communication with the slurry inlet and forming an end of the spiral flow surface, and the spiral block occupies 50% of the vertical height of the housing.

7. The canister according to claim 1 or 2, wherein the spiral flow surface defines a 360° arc.

8. The canister according to claim 1 or 2, wherein the spiral block has one of a vertical height of 3.5 inches to 5.5 inches, 7.5 inches to 9.5 inches, and 9 inches to 11 inches.

9. The canister according to claim 1, wherein the flow distributor includes a plurality of teeth projecting radially inwardly and defining a plurality of lobular recesses communicating with the central opening.

10. The canister according to claim 2 or 9, wherein the teeth define an internal geometry that tapers radially inwardly such that the tips of the teeth form the innermost circumference of the central opening.

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