PRIORITY

This application claims the benefit of U.S. Provisional Application No. 63/015,168, filed April 24, 2020, and titled “Refractory Plastic Application Systems and Methods”.

FIELD

Embodiments of this disclosure relate generally to systems and methods for applying refractory materials, and more particularly, to systems and methods for applying refractory materials that are especially susceptible to clogging using a rotary feed mechanism.

BACKGROUND

The present invention pertains to application of refractory materials that are especially susceptible to clogging, such as refractory plastics, using a rotary feed mechanism. Rotary feed mechanisms (also referred to as “rotary gunite machines” or (“rotary guns”) are configured to receive continuous feed of dry-mix or wet-mix refractory materials (for example, concrete) and transport the materials through a hose to a location for application. Oftentimes, the rotary gunite machines are used to spray or “gun” refractory materials to form raised or vertical surfaces, for example, to create vertical walls for a swimming pools, tunnels, furnaces, or other applications where non-traditional concrete surfaces are required and where traditional concrete pouring methods would prove cumbersome.

Rotary gunite machines enable processes involving the application of gunite as well as the application of shotcrete. Gunite is a dry monolithic refractory designed for use with dry gun equipment and it usually includes additives to make it stickier. Rotary gunite machines use air to push the dry (or pre-dampened) gunite through a hose and to the target. Water (which may include additives) is added at the nozzle of the outlet port of the hose to moisten the dry mix so it sticks to the surface. Shotcrete is typically a low-cement, low-moisture refractory that is fully tempered and mixed with water (which may include additives), and then is applied through a machine that uses a piston pump and air to spray the wet material from a nozzle similar to gunite.

Seminal work in this field is memorialized in U.S. Pat. No. 3,161,442 (the “442 Patent”), entitled “Transmission of Granular Material,” issued December 15, 1964. The 442’ Patent discloses a rotary feed mechanism which includes a segmented rotating bowl operable to carry particulate material from a hopper to an outlet tube. The mechanism utilizes compressed-air expulsion of the material from U-shaped passageways, or "pockets," of the feed bowl into the outlet tube, and further into a flexible hose having a nozzle for ejecting the material at high velocities. Rotary gunite machines are most commonly configured to accept dry mix materials (for example, including crystalline silica) and combine the materials with pressurized fluids, such as water which may include binding chemicals, at or near the ejection outlet of the flexible hose.

However, it was realized by the inventors of the systems and methods described in this application that rotary gunite machines used for application of refractory materials that are especially susceptible to clogging, such as refractory plastics, require modifications and improvements. One or more of such modifications and improvements is described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the figures shown herein may include dimensions or may have been created from scaled drawings. However, such dimensions, or the relative scaling within a figure, are by way of example, and not to be construed as limiting. FIG. 1 depicts an exemplary rotary gunite machine used for conveying refractory materials;

FIG. 2 depicts a cross-sectional view of the hopper and feed rotor of the rotary gunite machine of FIG. 1 taken along line FIG. 2-FIG. 2;

FIG. 3 depicts an exemplary wear plate for use with a rotary gunite machine; FIG. 4 depicts a cross-sectional view of the wear plate of FIG. 3 taken along line FIG.

4-FIG. 4;

FIGS. 5A-B depict an exemplary rigid conduit for coupling with an output of the rotary gunite machine of FIG. 1, including a secondary fluid injector;

FIGS. 6A-B depict a first exemplary end nozzle used for spraying refractory plastic materials; and

FIG. 7 depicts a second exemplary end nozzle used for spraying refractory plastic materials.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to one or more embodiments, which may or may not be illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended; any alterations and further modifications of the described or illustrated embodiments, and any further applications of the principles of the disclosure as illustrated herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. At least one embodiment of the disclosure is shown in great detail, although it will be apparent to those skilled in the relevant art that some features or some combinations of features may not be shown for the sake of clarity.

Specific quantities (spatial dimensions, pressures, times, force, resistance, etc.) may be used explicitly or implicitly herein, such specific quantities are presented as examples only and are approximate values unless otherwise indicated. Discussions pertaining to specific compositions of matter, if present, are presented as examples only and do not limit the applicability of other compositions of matter, especially other compositions of matter with similar properties, unless otherwise indicated.

Embodiments of the present disclosure provide improvements to rotary gunite machines used for applying, or “gunning,” refractory materials. Particularly, one or more of the systems and methods described herein provides improvements to rotary gunite machines configured for conveying refractory materials that are especially susceptible to clogging, such as refractory plastics, to a target.

Occupational Safety and Health Administration (OSHA) Standard 1926.1153, which applies to all occupational exposures to respirable crystalline silica in construction work, has in some instances impacted the simplicity, and therefore the motivation and desire, of performing dry-mix refractory applications. Typical dry-mix refractory applications include the addition of water after the material has been removed from its storage sack, thereby exposing workers to crystalline silica dust. The addition of water to dry-mix materials thereafter initiates the bond formation process. As such, with increasing regulations on crystalline silica, the refractory installation industry has searched for means to mitigate dust exposure hazards. One method of mitigating such hazards includes the installation of monoaluminum phosphate (A1(H2P04)3 or “MAP”) bonded plastic refractory, which is pre-mixed during manufacturing and which forms chemical bonds upon exposure to heat during the material application.

Common methods for installing MAP-bonded refractory include hand placement by ramming and pneumatic placement utilizing a rotary feed wheel pneumatic conveying system known as a “BSM Gun”. One example of a BSM Gun is the Greengun-85P Plus, manufactured by HarbisonWalker International of Pittsburgh, PA. However, the two application techniques noted above suffer from multitude of setbacks. For example, hand ramming requires intense manual repetitive motion, and utilizing pneumatic-driven placement requires installing additional structures. In larger applications, the pneumatic-driven process requires a large number of employees to produce an installation rate suitable for the customers outage requirements. Though pneumatic placement systems are capable of applying material at a faster rate (for example, in some instances 3,000 pounds in 30 minutes with a crew size of six employees), these systems are rapidly becoming discontinued and also difficult to maintain and repair. Considering the respirable silica regulations are moving the focus toward dust- free refractory application processes, and the need to continue applying dust-free premixed refractory plastic (such as, phosphate-bonded refractory materials) in a labor efficient manor remains, systems and methods described herein provide various improvements to rotary gunite machines to sustain manufacturing of such systems and their replacement parts.

I. Exemplary Rotary Gunite Machines A. Overview

Depicted in FIGS. 1-2 is one exemplary rotary gunite machine (100) which is commonly used for applying refractory materials, particularly, dry-mix gunite materials. Shown is the REED LOVA gunite machine manufactured by J.F. Shea Co., Inc. of Walnut, CA. Although the REED LOVA gunite machine is referenced herein, it should be understood that other rotary gunite machines may exist or may be developed utilizing the systems and methods described.

The REED LOVA bowl -type rotary gunite machine was designed for applications of gunite and shotcrete-based materials. The materials conveyed through this system are primarily cement-based dry-mix refractory or concrete mixes configured such that water is mixed with the materials at or substantially near the outlet end of the hose line (such as, the nozzle) to initiate the hydration-cement bond formation. Particularly, the water is introduced to the dry-mix materials within the hose a location near the nozzle where the operator grasps the hose and nozzle, thereby providing the operator holding the nozzle access to the water controls. Alternatively, the use of a pre mixed small -aggregate concrete wet-mix has also been used in the construction process of swimming pools and other various non-traditional shaped walls and linings. Refractory applications utilizing bowl-type rotary gunite machines include dry-mix small -aggregate refractory materials configured in one of two configurations. In one configuration, the water is lightly pre-mixed prior to its introduction into the hopper of the machine and is introduced again at or near the outlet nozzle. In an alternative configuration, only dry-mix materials are introduced into the hopper of the machine, and all of the water is introduced and mixed with the materials at or near the outlet nozzle. The systems and methods described herein can permit a third configuration which supports a phosphorous acid refractory (such as, a plastic refractory), which is a fully pre-mixed wet-mix material, being introduced into the hopper of the machine, and without requiring any additional material or water mixing at or near the outlet nozzle. A plastic refractory is a moist, pliable mixture of aggregates and binders which when applied to a furnace wall or the like and fired in place forms a hard, monolithic, refractory lining for the substrate. Plastic refractory compositions are manufactured in granular form and in slab form. Both forms have been and still are placed by ramming the plastic masses onto the substrate to knead and knit them together and form a monolithic lining. Ramming is labor intensive and much care must be taken to avoid lamination of the plastic masses which would shorten the useful life of the refractory lining.

As shown, the rotary gunite machine (100) includes a hopper (102) having an upper opening (102a) and a lower opening (102b), the hopper (102) being operable to receive refractory materials (104). Refractory materials (104) may be introduced from a larger truck and/or funnel, or by hand through operators dumping or shoveling refractory materials into it. Optionally, an operator may lift and drop a bag, such as a 50-pound bag of dry-mix materials, onto a bag breaker (106) having sharp spikes intended to slice open the bag, thereby allowing the contents to spill down into the hopper (102). A screen (not shown) may be placed across the upper opening (102a), if desired, to keep out undesirably large rock and the like.

The hopper (102) is positioned above and secured to a feed rotor (108). As such, the material (104) is funnel ed down into the feed rotor (108). In some applications, the feed rotor (108) may optionally include one or more agitator blades (110) mounted on a rotary shaft (112) so as to mix the material, and to encourage it to pass downward through the hopper (102) to the feed rotor (108). A housing (114) extends around a portion of the bottom periphery of the feed rotor (108) to blank off and shroud certain portions of an expulsion station (116). As such, granular material (104) contained in the hopper is only able to come into contact with face (118) which is not covered by housing (114).

As will be described in greater detail below, the rotary gunite machine (100) further includes a plurality of pockets (120) formed on the bottom surface inside the feed rotor (108). Each pocket (120) is substantially an upright U-shaped member formed by a round bottom extending downwardly into the pocket, thereby providing a substantially smooth and continuous conduit between the respective upper ports relating to each individual ones of the pockets. In practice, each pocket (120) is substantially a cylindrical member interrupted by radially-extending walls, such as wall (122). Pockets (120) are defined by a coupling between a wear plate (124) and a feed bowl (126). Wear plate (124) is fitted between housing (114) and feed bowl (126), and both wear plate (124) and feed bowl (126) are secured to rotary shaft (112) and thereby rotate as rotary shaft (112) is rotated by a motor (not shown). As wear plate (124) and feed bowl (126) are rotated, material (104) drops into the U-shaped pockets (120) from hopper (102) and the pocket (120) of material is then rotated to expulsion station (116). Once U-shaped pockets (120) are rotated to a pre-defined position in expulsion station (116), a wear pad (136) provides an air-tight seal between the openings of the U-shaped pocket (120) and each conduit (130, 132).

Wear plate (124) and feed bowl (126) are generally formed with steel, a steel alloy, or other similar materials or combinations of materials including neoprene, cast iron, carbon fiber, glass, and/or composites. However, it should be understood that other suitable materials having similar properties may be used as well.

An air inlet hose (128) may be coupled with and provide compressed air from an air compressor (160) through a conduit (130), while one or more hoses having a nozzle at the distal end of the hose relative to the feed rotor (109) may be coupled with outlet conduit (132), or “goose neck,” to convey material (104). In typical configurations, connector (134) of outlet conduit (132) is coupled with a flexible hose having a spray nozzle at which water may be mixed in pneumatic concrete work, or the hose may simply deliver the material to some destination.

B. Exemplary Improvements to Reduce or Prevent Material Buildup and Plugging within the Feed Rotor

As noted above, gunning plastic refractory was previously unsustainable through the bowl typed gunite machine as the phosphorous acid wet-mix (fully pre-mixed) refractory is too susceptible to building up and plugging prior rotary gunite machine systems, both within the rotary feed wheel and within the hose used the convey the material. This is because gunnable plastic refractory must be drier than a granular ramming plastic to avoid clogging of the feed rotor (108), hose and nozzle. Dry-mix materials are less sticky and therefore do not adhere to the inner walls of the gunning equipment, but instead are fed through the feed rotor (108) with minimal plugging issues. However, the dry-mix materials also do not adhere well to the target walls, thereby necessitating solutions such as those described herein for passing wet-mix refractory plastics through the feed rotor, hose, and nozzle.

As best shown in FIG. 2, once materials (104) are introduced into the hopper (102), the materials (104) funnel downward into the U-shaped pockets (120) formed by the rotating wear plate (124) and feed bowl (126). Air inlet hose (128) provides air from air compressor (160) through conduit (130), into one opening of the U-shaped pocket (120) on face (118) as it passes by expulsion station (116) during rotation, therefore forcibly pushing material (104) out of pocket (120) and through outlet conduit (132). Thereafter, wear plate (124) and feed bowl (126), which together form a plurality of U- shaped pockets (see FIGS. 3-4), continue to rotate to collect material (104) and deliver it to expulsion station (116) to be forced out of the feed rotor (108).

Shown in FIGS. 3-4 are a top plan view (FIG. 3) and a cross-sectional view (FIG. 4) of one exemplary assembled wear plate (200) and feed bowl (300) which may be used within feed rotor (108) to provide the functionality of wear plate (124) as described above. To assemble wear plate (200) within a feed rotor, one or more pins coupled with a rotary shaft mechanism, such as rotary shaft (112), may insert through one or more sockets (212) defined through wear plate (200), and/or a fastener (not shown) may be affixed to a rotary mechanism through central socket (114). As noted above, wear plate (200) and corresponding feed bowl (300) may be rotatably secured using the same or similar fastening methods and are configured to rotate in unison. Once assembled, the top face (202) of wear plate (200) defines face (118) as described above with reference to FIG. 2. Wear plate (200) includes an inner ring wall (204), an outer ring wall (206), and a plurality of transverse walls (208) which form a plurality of openings (210) extending all the way through wear plate (200). Similarly, feed bowl (300) includes an inner ring wall (302), an outer ring wall (304), and a plurality of transverse walls (306) which form a plurality of openings (312) and which align with inner ring wall (204), outer ring wall (206), transverse walls (208), and openings (210) of wear plate (200). Feed bowl (300) further defines a curved interior wall surface (308) coupling adjacent openings (210a, 210b) of wear plate (200) with adjacent openings (312a, 312b) of feed bowl (300) thereby defining a U-shaped pocket (310). Wall (208) generally corresponds with wall (122) shown in FIG. 2, while adjacent openings (210a, 210b) provide as the two openings on face (118) corresponding with each U-shaped pocket (310) (or pocket (120) as shown in FIG. 2), although various configurations of wear plates known in the art and are used with rotary gunite machines. By varying the pocket sizes and the number of pockets, the amount of material collected within the pockets and thereafter ejected by expulsion station (116) may be varied depending on the requirements of the application as is understood by a person skilled in the art.

As traditional wear plates are generally constructed to feed dry-mix materials or only lightly pre-mixed materials, wear plate (200) and/or feed bowl (300) may be modified with additional features to ensure stickier wet-mix materials, such as phosphate-bonded refractory plastics, may be directly introduced into the hopper (102) and therefore into the U-shaped pockets (310) through openings (210, 312) of wear plate (200) and feed bowl (300).

In one example inner facing surfaces (216, 218, 220, 222) of openings (210a, 210b) of wear plate (200) may be coated with a material suitable for reducing surface friction as materials pass through openings (210a, 210b), whether during filling of the pocket (310) with material or ejecting material out of the pocket (310) using compressed air. Any material capable of coating to the inner opening surfaces (216, 218, 220, 222) may be used and may be selected depending on the material used to form the wear plate (200) and the ability to adhere a non-slip substance to it. In one exemplary configuration, inner opening surfaces (216, 218, 220, 222) may be coated with a friction-reducing material (350) such as an industrial grade epoxy, to create a smooth and slick surface allowing sticky materials to traverse without building up or plugging the openings (210a, 210b, 312a, 312b) or the pocket (310). Industrial grade epoxy may be packaged in two parts that are mixed prior to application. The two parts may consist of an epoxy resin which is cross linked with a co-reactant or hardener. When properly catalyzed and applied, epoxies produce a hard, chemical and solvent resistant finish which may be used on concrete and steel to provide a friction-reduced, slick finish that also protects the surface from damage caused by water, alkali, and/or acids. The specific selection and combination of epoxy component and hardener component may be varied to determine the final characteristics and suitability of the coating for a given environment. One example of an epoxy suitable for this configuration is PSX-700 manufactured by PPG Industries, Inc. of Pittsburgh, PA. The friction reducing material (350) may be painted onto inner opening surfaces (216, 218, 220, 222) and allowed to dry prior to introducing material, and it may further be refinished as needed once the coating exhibits wear from normal use. In addition or alternative to coating inner facing surfaces (216, 218, 220, 222) with a friction reducing coating, interior wall surface (308) of feed bowl (300) may also be coated with the same or similar friction reducing coating to promote wet-mix materials to pass through the pocket (310) from opening (312b) to opening (312a) without building up or plugging. Similarly, interior wall surface (308) may be painted with the coating and allowed to dry prior to introducing material, and it may further be refmished as needed once the coating exhibits wear from normal use.

In addition or alternative to coating inner facing surfaces (216, 218, 220, 222) of wear plate (200) and/or interior wall surface (308) of feed bowl (300), various other features may be included to prevent or reduce buildup and plugging of sticky material within feed rotor. For example, a blocking plate or chute (320) may be removably placed within the hopper to blank off some pockets (310) and therefore funnel material to a reduced number of pockets (310) at one time. This may prevent too much material from filling the pockets (310) which may in some instances result in bogging down the rotational drive mechanism. In some applications, it is advantageous that the chute is unaffixed to the machine and quickly removable to permit an operator quick access to the top face of the wear plate (200) to provide maintenance, move stuck material, or the like.

Alternatively, an unaffixed and removable blocking plate or chute (320) that is cone-shaped may be inserted into the hopper to blank off certain openings, such as the inner wear plate and feed bowl openings (210b, 312b). In this configuration, material is only permitted to fall into pocket (310) through outer wear plate and feed bowl openings (210a, 312a), resulting in a less buildup and plugging since less material is being introduced to the expulsion station (116). As such, the compressed air from air compressor (160) being pumped through the pocket (310) expels a lesser amount of material through the goose neck outlet (see FIG. 1) and toward the target.

In addition to or alternative to the systems and methods described above to reduce or prevent material buildup and plugging within the feed rotor, the compressed air introduced through conduit (130) (see FIG. 2) and through the pocket (310) to expel material from the pocket (310) out of the outlet conduit (132) (see FIG. 2) may be increased above recommended dry-mix material pressure levels as needed to force wet- mix material out of the pocket (310) and outlet conduit (132) (see FIG. 2). For example, the REED LOVA Series 4 rotary gunite machine recommends instrument quality air pressure of around 210 cubic feet per minute (CFM) for 1” hose sizes and 375 CFM for 1-1/2” hose sizes. However, for wet-mix refractory plastic applications as described herein, the instrument quality compressed air is advantageously increased to approximately between 375-400 CFM to force wet-mix material out more adequately of the pocket (310) and outlet conduit (132) (see FIG. 2).

In some embodiments, an air amplifier (162) (see FIG. 1) may optionally be coupled between the air compressor (160) and inlet conduit (130). Air amplifier (162) may operate as, for example, a booster compressor (or “air intensifier”), used to increase or amplify the air pressure coming from the air compressor (160) by passing it through additional compression stages. One example of air amplifier (162) is a Super Air Amplifier manufactured by the EXAIR Corporation of Cincinnati, OH. Booster air compressors can magnify existing air flows between. As such, air compressor (160) size may be decreased accordingly, thus saving on the costs associated with the purchase, operation, and transport of air compressor (160). Additionally, including an air amplifier (162) and decreasing the size of the air compressor (160) may also decrease the resulting compressed air injected into inlet conduit (130). For example, without including the optional air amplifier (162), a 600-750 CFM instrument quality air compressor may be required in larger rotary feed wheel pocket arrangements. Alternatively, by including the optional air amplifier (162), a 375-425 CFM air compressor may be only required to inject compressed air in such larger rotary feed wheel pocket arrangements.

In addition to or alternative to the systems and methods described above to reduce or prevent material buildup and plugging within the feed rotor, the compressed air introduced through conduit (130) (see FIG. 2) and through the pocket (310) to expel material from the pocket (310) out of the outlet conduit (132) (see FIG. 2) may be cooled prior to introduction into the feed rotor, and further the moisture content of the air may be reduced below the recommended levels. In typical dry-mix applications using rotary gunite machines, air pressure includes a high moisture content of approximately 80-90% humidity which also results in higher temperatures of approximately 190-200 degrees Fahrenheit. However, monoaluminum phosphate present within refractory plastics is activated by heat, and high moisture content also increases sticking. As such, by cooling and decreasing the moisture content from the material down to approximately 5-10% humidity, sticking of the material within the system is greatly reduced. Additionally, since the monoaluminum phosphate bonds of refractory plastics are not activated by hot air, material rebound off of a target wall is also greatly reduced (such as, the material provides improved sticking properties to the target surface).

C. Exemplary Improvements to Prevent Material Buildup and Plugging within the Transfer Tubing

As noted above, gunning plastic refractory was previously unsustainable through the bowl typed gunite machine as the phosphorous acid wet-mix (fully pre-mixed) refractory is too susceptible to building up and plugging prior rotary gunite machine systems, both within the rotary feed wheel and within the hoses and piping used the transfer the materiel to the target and to convey it. In conventional dry-mix gunite and shotcrete applications, hose diameters of between 1” and 1-1/2” are utilized to move dry materials from the feed rotor to the end nozzle for spraying on the target surface. Further, typical hoses (501) (see FIG. 5A) coupled with outlet ports of rotary gunite machines (for example, outlet port (134) of FIGS. 1-2) are comprised of flexible hose materials, including deformable materials such as rubber or other known materials commonly used in flexible hoses. As noted above, typical rotary gunite machine configurations commonly include water or air propulsion included at or immediately adjacent the exit nozzle and within reach of the operator to make real-time adjustments to the propulsion as needed to improve the material application.

As depicted in FIGS. 5A-5B, a rigid conduit assembly (400), such as a conduit unable to bend or be forced out of shape (for example, an aluminum or stainless-steel schedule 40 pipe), may be directly coupled with outlet port (134) (see FIGS. 1-2) to facilitate transferring wet-mix refractory plastics from the feed rotor to a conduit system. For example, in one exemplary configuration for applying wet-mix refractory materials, a rigid conduit (402) may define a 1.5” or 2” rigid aluminum or stainless-steel conduit. At each end is a female coupling (416) with one end further comprising a connector (414), such as a 3” coupling, for securing to the outlet port (134) (see FIGS. 1-2).

In some versions, female couplings (416) may be advantageously configured to maintain the same inner diameter and provide a seamless, flush-surfaced transition between outlet port (134) and the rigid conduit (402), and also between rigid conduit (402) and the flexible hose (501). Shown in FIG. 5B is a perspective view of female coupling (416). Connector (414) of female coupling (416) may be configured as a bell- type heavy duty (HD) connector defining an inner diameter which increases near the distal end (420) relative to the proximal end (422). As such, the conduit being coupled with connector (414) of rigid conduit (402) may be configured as having the same inner diameter of rigid conduit (402), and upon connecting the inner diameter will remain consistent therethrough the connection.

The rigid conduit (402) and female couplings (416) collectively provide an advantageous material transfer from the rotary gunite machine to the hose which decreases material buildup and plugging when compared to traditional flexible hose transfer conduits. This is due to the reduced surface friction applied to the passing material by stainless steel, aluminum, or the like over rubber or other flexible/deformable materials, and/or the reduced impact angle of the material and the conduit wall in a straightened conduit versus that of a more curved conduit. As such, rigid conduit assembly (400) thereby reduces the resistance to material flow versus traditional flexible hoses, and in some instances reduces the thickness of the boundary layer of slower or non-moving material adjacent the conduit wall which may lead to clogging.

In addition to or alternative to the rigid conduit assembly (400), a secondary fluid injector (401) may be included anywhere along the length of the rigid conduit assembly (400) to impel or otherwise increase the propulsion of the material through the conduit system down the line toward the flexible hose (501) and exit nozzle (for example, nozzles 500 or 600). In the exemplary improved configuration for application of wet-mix refractory plastics, a secondary fluid injector (401) may be configured to introduce compressed air and can be included in place of any injection ports adjacent the nozzle. Secondary fluid injector (401) thereby supplements the initial fluid injection of inlet conduit (130) (see FIG. 2) to assist propelling the material toward the end nozzle. In this exemplary configuration, the secondary fluid injector (401) is positioned sufficiently close to the coupling with the upward-oriented outlet port (134) (see FIGS. 1-2) such that any material building up adjacent the outlet port is relieved prior to transferring the material to any additional conduits, such a flexible hoses. In some configurations, secondary fluid injector (401) may include a ball valve (418) at one end for coupling the internal lumen with the air compressor (160), optionally utilizing an air amplifier (162) as described above, a nipple (404), and coupling (406) at the opposing end to introduce the compressed air via secondary conduit (403) in line with the flow of the material through conduit (402). Secondary conduit (403) may include a 1.5” or 2” (inner diameter) pipe formed with aluminum and galvanized steel, although it should be understood that various alternative conduits having different sizes and materials may be utilized. In other configurations, secondary fluid injector (401) may be outfitted with HD flange-type (bell) connectors for coupling the internal lumen with the air compressor (160) and the secondary conduit (403). Optionally, secondary fluid injector (401) may include a tee (408) and reducer (410) for coupling an air pressure gauge (412) allowing an operator to monitor the air pressure being applied into conduit (402). While the illustrated embodiment shows secondary fluid injector (401) introducing air along an axis that is substantially parallel to a longitudinal axis defined by a straightened portion (405) of conduit (402), or substantially axially aligned with the longitudinal axis defined by a straightened portion (405) of conduit (402) as shown, it should be understood that conduit (402) may comprise any shape and second air injector (401) positioning may be varied to introduce air at any point along conduit (402), including introducing air along an axis that is transverse to the longitudinal axis defined by a straightened portion (405) of conduit (402). Because secondary conduit (403) may be arranged obliquely relative to the rigid conduit assembly (400) at the point of entry.

In some embodiments, an air compressor may introduce compressed air to ball valve (418) of secondary fluid injector (401) at approximately 185 CFM for propelling material distally through the aluminum or stainless steel conduit transfer pipe, although the air flow rate may be modified to better suit different applications. In some embodiments, the compressed air introduced to secondary fluid injector (401) may be chilled and moisture-reduced similar to the primary fluid injector described above.

As noted above, conduit (402) includes a coupling (416) for securing the proximal end of an additional conduit, such as a flexible hose (501). The flexible hose (501) provides for an operator to move around the job site as required to convey refractory materials. In some configurations, a standard 1.5” inner diameter flexible hose (501) may be used. However, in modified configurations, a 2” inner diameter hose may be preferable to reduce or prevent building or plugging. In any arrangement, the inner diameter of flexible hose (501) may be equal to the inner diameter of rigid conduit assembly (400). In exemplary embodiments, a 10 to 15-foot long discharge hose may be utilized to transfer material from rigid conduit assembly (400) to the end nozzle. However, in other embodiments, a 40 to 45-foot long discharge hose may be utilized.

Depicted in FIGS. 6A-B is an improved spray nozzle (500) adapted for coupling with the flexible hose (501) for use with one or more of the rotary gunite machines described above. Particularly, spray nozzle (500) may be formed using any rigid material known in the art which is suitable for spraying refractory materials. While conventional nozzles include one or more ports for introduction of water or air at the nozzle, exemplary spray nozzle (500) is adapted for use with wet-mix refractory plastics and therefore nozzle (500) does not include a port to mix additional water prior to ejection. Further, secondary fluid injector (401) (see FIG. 5A) ensures material is transferred to nozzle (500) with sufficient velocity for spraying. In one embodiment, nozzle (500) may include various assembled parts such as an exit tube (502), a reducer (504), a transfer conduit (506), and a hose coupling (508) to secure nozzle (500) to the hose (501). In some embodiments, the various parts of nozzle (500) may be welded or otherwise affixed together. Tube (502) may be, for example, a 1” x 1” square tube, reducer (504) may be a 2-1/2” to 1” HD flange (bell) reducer, and transfer conduit (506) may be a 2” rigid pipe. While tube (502) is illustrated as a square tube, it should be understood that various other shapes and configurations may be utilized without decreasing the functionality of nozzle (500). Additionally, hose coupling (508) may alternatively be configured as an HD flange-fitting (bell) similar to female coupling (414) for providing a seamless transition between components to prevent material build ups.

Depicted in FIG. 7 is another improved spray nozzle (600) adapted for coupling with a flexible hose (501) for use with one or more of the rotary gunite machines described above. Particularly, spray nozzle (500) may be formed using any rigid material known in the art which is suitable for spraying refractory materials. While conventional nozzles include one or more ports for introduction of water or air at the nozzle, exemplary spray nozzle (600) is adapted for use with wet-mix refractory plastics and therefore nozzle (600) does not include a port to mix additional water prior to ejection. Further, secondary fluid injector (401) (see FIG. 5A) ensures material is transferred to nozzle (600) with sufficient velocity for spraying. In one embodiment, nozzle (600) may include various assembled parts such as an exit tube (602), a transfer conduit (604), and a hose coupling (606) to secure nozzle (600) to the hose (501). Tube (602) may be, for example, a 1.5” diameter cylindrical tube. Exit tube (602) may also be shaped to function as a reducer to decrease the inner diameter carrying material to about 1”. Additionally, hose coupling (606) may be configured as a bell-fitting similar to female coupling (414) for providing a seamless transition between components to prevent material build-ups.

Various systems and methods described herein provide improved application of high-density phosphate bonded refractory through the bowl typed rotary gunite machines. In practice, the embodiments described are capable of providing an applied material density equal to or greater than the applied material density of a BSM refractory gun. By utilizing these improved systems and methods, application rates of up to 3,000 pounds of conveyed refractory plastic material per 30 minutes can be achieved.

Reference systems that may be used herein can refer generally to various directions (for example, upper, lower, forward and rearward), which are merely offered to assist the reader in understanding the various embodiments of the disclosure and are not to be interpreted as limiting. Other reference systems may be used to describe various embodiments, such as referring to the direction of projectile movement as it exits the firearm as being up, down, rearward or any other direction.

While examples, one or more representative embodiments and specific forms of the disclosure have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive or limiting. The description of particular features in one embodiment does not imply that those particular features are necessarily limited to that one embodiment. Some or all of the features of one embodiment can be used or applied in combination with some or all of the features of other embodiments unless otherwise indicated. One or more exemplary embodiments have been shown and described, and all changes and modifications that come within the spirit of the disclosure are desired to be protected. What is claimed is: