Patent Application
20090110833
1. Field of the Invention
The present invention relates generally to surface treatments and methods thereof, and more specially to the surface treatment of components of a pelletizing system. As used herein, the terms “pelletizing system” and “pelletization sequence” include the processes and equipment for extrusion, pelletization, transportation, drying, crystallization, and post-processing manipulations of pellets. In the general pelletizing system/pelletization sequence, the pelletizing apparatus is but a single component in a sequence of additional upstream and downstream equipment.
2. Description of the Prior Art
The generally independent processes and equipment of the conventional pelletizing system are known, some for many years, and used in many applications. Similarly, numerous processes and chemistries for surface treatment and coatings are known as well, some for many years. Yet, the prior art is silent to the application of these processes to the equipment components of the pelletizing system to achieve a synergistic effect such that corrosion, erosion, abrasion, and wear of those components can be limited, if not prevented, while simultaneously avoiding accumulation, adherence, occlusion, agglomeration, and stricture of the pellets produced to those components and areas surrounding those components.
Pelletization equipment and its use following extrusion processing have been implemented for many years by the assignee as demonstrated in prior art disclosures including, for example, U.S. Pat. Nos. 4,123,207; 4,251,198; 4,500,271; 4,621,996; 4,728,176; 4,888,990; 5,059,103; 5,403,176; 5,624,688; 6,332,765; 6,551,087; 6,793,473; 6,824,371; 6,925,741; 7,033,152; 7,172,397; US Patent Application Publication Nos. 20050220920, 20060165834; German Patents and Applications including DE 32 43 332, DE 37 02 841, DE 87 01 490, DE 196 42 389, DE 196 51 354, DE 296 24 638; World Patent Application Publications WO2006/087179, WO2006/081140, WO2006/087179, and WO2007/064580; and European Patents including EP 1 218 156 and EP 1 582 327. These patents and applications are all owned by the assignee and are included herein by way of reference in their entirety.
Similarly, dryer equipment has been used by the assignee of the present invention for many years as demonstrated in the prior art disclosures including, for example, U.S. Pat. Nos. 3,458,045; 4,218,323; 4,447,325; 4,565,015; 4,896,435; 5,265,347; 5,638,606; 6,138,375; 6,237,244; 6,739,457; 6,807,748; 7,024,794; 7,172,397; US Patent Application Publication No. 20060130353; World Patent Application Publication No. WO2006/069022; German Patents and Applications including DE 19 53 741, DE 28 19 443, DE 43 30 078, DE 93 20 744, DE 197 08 988; and European Patents including EP 1 033 545, EP 1 602 888, EP 1 647 788, EP 1 650 516. These patents and applications are all owned by the assignee and are included herein by way of reference in their entirety.
Additionally crystallization processes and equipment are also disclosed by the assignee exemplarily including U.S. Pat. No. 7,157,032; US Patent Application Publication Nos. 20050110182, 20070132134; European Patent Application No. EP 1 684 961; World Patent Application Publication Nos. WO2005/051623 and WO2006/127698. These patents and applications are all owned by the assignee and are included herein by way of reference in their entirety.
Post-processing manipulations as used herein can include thermal manipulation, pellet coating, particle sizing, storage, and packaging of the pellets thusly formed, and are well-known to those skilled in the art.
Surface treatment processes typically can begin with preparatory steps exemplary of which can be thorough substrate cleaning by degreasing as with solvents, mild to moderately rigorous abrasion as by peening or grit-blasting or sand-blasting, etching commonly with acids or bases, pickling, corona treatment, and plasma etching and activation. Onto these cleaned surfaces additional processing can include, for example, at least one of the steps of passivation, nitriding, carbonitriding, priming, phosphatizing, metallizing, galvanizing, electrolytic deposition, electroless plating, flame spraying including high velocity application, thermal spraying, sintering, plasma spraying, chemical and physical vapor deposition, vacuum deposition, electrolytic plasma treatment and sputtering techniques. Mechanical application techniques can be used as well exemplarily including dip coating, powder coating, roll coating, rod coating, extrusion, slush molding, and rotational molding. Reactive coatings can be applied as well and multiple treatments and coatings utilizing multiple methods or application are well-represented in the prior art.
The automotive industry has utilized coating technology to enable the use of lighter weight parts. The coatings can provide additional abrasion resistance to reduce wear and provide friction-reducing surfaces as exemplified in U.S. Pat. Nos. 5,080,056; 5,358,753; 6,095,126; and 6,280,796.
The aerospace industry has utilized coatings as well, for example, as a hard coat surface in U.S. Pat. No. 3,642,519. U.S. Pat. No. 4,987,105 discloses a coating comprised of carbon, boron nitride, water and similar organic carrier fluids and optionally binders such that at least a portion of the carbon can be selected from a carbon fiber, graphite, amorphous carbon and mixtures thereof.
EP 0 285 722 teaches the use of a composite coating, wherein a surface is prepared by flame spraying and/or thermal spraying a metal powder including stainless steel, nickel, nickel chromium, and molybdenum, for example, onto a substrate followed by impregnation of the porous surface with an ambiently air-cured silicone to form a film that fills the depressions and covers the raised areas that result from that thermal spray technique. An abrasion resistant composite is formed onto that substrate and can provide a release surface.
U.S. Pat. Nos. 5,066,367; 5,605,565; and 5,891,523 teach electroless coatings and metallization of surfaces. U.S. Pat. Nos. 6,309,583 and 6,506,509 disclose articles that can be comprised of composites formed with the electroless coatings including encapsulation of the composite material therein and formation of density gradients of that composite material in the electrolessly plated matrix material, respectively.
U.S. Pat. Nos. 5,508,092 and 5,527,596 respectively disclose substantially optically transparent coatings and improved interlayer adhesion of those coatings and articles made therefrom.
Formation of diamond and diamond-like coatings is disclosed in U.S. Pat. Nos. 5,308,661; 6,066,399; and 6,713,178. Control of the molecular structure of the carbon deposition can produce a range of geometry from a more planar graphite-like layer to a more three-dimensional diamond-like structure and can be achieved by modification of the source gas and the energetics of the deposition as disclosed therein. Improvement of adhesion to the substrate and enhancement of surface properties of the coated layer are disclosed. German Patent DE 20 2007 004 495 U1 discloses the use of a diamond coating on the surface of the die face that has a surface roughness at least twice that of the roughness of the edge of the cutting blade.
U.S. Pat. No. 7,166,202 teaches plasma electroplating wherein an object is coated in an electrolyte preparation through which plasma is generated in a bubble mass between the electrodes, one of which is the article being coated. The method discloses, for example, the use of electroplating metals and non-electroplating metals, non-metals, diamond-like carbon, and semiconductors including compound and ternary compositions.
U.S. Pat. No. RE 33,767 discloses an electroless plating technique onto a substrate that exemplarily may include polymers, glass, ceramics, and metal, and articles made therefrom. This process deposits a metal alloy into which can be dispersed polycrystalline diamond particles in a range from 0.1 micron to 75 microns.
U.S. Pat. Nos. 6,846,570 and 7,026,036 teach the use of multiple and single non-stick coatings, respectively and U.S. Pat. Nos. 6,287,702 and 6,312,814 disclose the concept of thermally melt-processable fluoropolymers. U.S. Pat. Nos. 5,989,698 and 6,486,291 teach curable and cross-linkable fluoropolymer urethanes, respectively that can be used to coat porous materials forming air-permeable repellent surfaces.
U.S. Pat. No. 6,576,056 discloses the use of insert members preferably constructed of synthetic diamond or other suitable non-metallic material and teaches a method whereby the insert is fixedly attached when welding and/or brazing are not suitable techniques.
U.S. Pat. No. 7,094,047 teaches the use of surface treatments on the face of a die for extrusion molding of a honeycomb. These surface treatments include a soft film over-coated onto a hard film in which the hard film is applied by chemical or physical vapor deposition of tungsten carbide, titanium carbide, titanium nitride, or titanium carbonitride. Alternatively, the hard film may be composed of silicon carbide, diamond, or carbon boronitride powders that can be applied as a dispersion in an electroless nickel plating process.
Inherent in most if not all of these coating technologies can be difficulties in application to the multiple components needing these treatments in the pelletization system including transport, drying, crystallization, and post-processing manipulations. Parts in this type of process can range from extremely small, for example, a cutter blade, to extremely large as exemplified by a centrifugal dryer housing. The parts can be subjected to high heat and pressure as in the extrusion process through a die. Similarly high impact zones occur in piping elbows, lifter blades in the drying process, and on impingement of pellets against a screen for dewatering and drying processes. Additional complications arise in that materials being processed can be tacky in at least one stage of the process and thusly are prone to accumulation potentially blocking passageways and screens. Materials being processed can contain corrosive materials and processing may generate similarly aggressive materials that can potentially damage components throughout the process stages.
Conventional technology can be limited in its use of vacuum by size constraints of the equipment. Processes involving high temperatures can be prone to deformation of the article being treated. Polymeric coatings and layers can suffer from poor adhesion and thus can be eroded and abraded from the surface with relative ease. Differing compositions of metals can lead to galvanic corrosion and different thermal expansion properties can induce stress potentially leading to cracks. Metal plating, metallizing, nitriding, carbonitriding, and similar processes typically involve very thin coatings that can be abraded and eroded away leaving the exposed substrate prone to accelerated wear. Particles bound to the surface can suffer from highly three-dimensional surfaces facilitating development of undesirable porosity and potential entrapment of chemicals that can exacerbate corrosive attack. The particles can be of such irregular surface that they can contribute undesirably to wear and abrasion of the pellets being produced. Adhesion between layerage of the surface treatments and coatings can be problematic and potentially leads to flaking, peeling, and ultimate failure of the coating.
The prior art remains silent as to appropriate surface treatments for protecting equipment involved in the pelletizing system, which can be a sequence that includes pelletization, transport, drying, and post-processing manipulations against the aggressive and damaging actions of abrasion, corrosion, erosion, and wear. It is also silent as to surface treatments that can prevent adhesion, accumulation, obstruction, and blockage of the passageways into and through that equipment.
What is needed, therefore, are surface treatment methods such that at least one surface treatment as well as many combinations of surface treatments can be applied to multiple component parts of an assemblage of equipment included in and that follow immediately from a pelletizing apparatus, thusly facilitating transport to and through a drying apparatus and through further crystallization and post-processing manipulations and/or storage of the pelletized product thusly formed without detrimental abrasion, corrosion, erosion, and wear of those components and to the surfaces of which the pellets thus formed will not adhere leading to undesirable stricture, accumulation, agglomeration, clumping, blockage, and otherwise obstructing the passageways into and through that assemblage of equipment. It is to such a method that the present invention is primarily directed.
The present invention is a method for abrasion-resistant non-stick surface treatments for pelletization and drying process equipment components. The present invention includes methods by which a sequence of surface treatments can be applied to various component parts of the pelletizing system. The surface treatments of the present invention protect the equipment of the pelletizing system from detrimental abrasion, corrosion, erosion, and wear. Further, the pellets formed by the pelletizing system will not adhere to the equipment, thus limiting if not eliminating agglomeration, clumping and/or obstruction of the passageways or devices.
Such surface treatments can involve one, two, and potentially multiple processes inclusive and exemplary of which are cleaning, degreasing, etching, primer coating, roughening, grit-blasting, sand-blasting, peening, pickling, acid-wash, base-wash, nitriding, carbonitriding, electroplating, electroless plating, flame spraying including high velocity applications, thermal spraying, plasma spraying, sintering, dip coating, powder coating, vacuum deposition, chemical vapor deposition, physical vapor deposition, sputtering techniques, spray coating, roll coating, rod coating, extrusion, rotational molding, slush molding, and reactive coatings utilizing thermal, radiational, and/or photoinitiation cure techniques, nitriding, carbonitriding, phosphating, and forming one or more layers thereon.
Materials applied utilizing these processes include metals, inorganic salts, inorganic oxides, inorganic carbides, inorganic nitrides, inorganic carbonitrides, corrosion inhibitors, sacrificial electrodes, primers, conductors, optical reflectors, pigments, passivating agents, radiation modifiers, primers, topcoats, adhesives, and polymers including urethanes and fluorourethanes, polyolefins and substituted polyolefins, polyesters, polyamides, fluoropolymers, polycarbonates, polyacetals, polysulfides, polysulfones, polyamideimides, polyethers, polyetherketones, silicones, and the like.
Surface treatments are applied with the intent to provide modifications to that surface such that it is more resistant to wear, or it has reduced damage from erosion or corrosion, or it is less prone to scratching and abrasion, or it discourages adhesion to that surface, or it reduces friction along that surface. Contemporary pelletization, by virtue of its heating, transport and cooling processes of polymers or polymer-like materials problematically include transiently or ultimately tacky materials, which by their nature can be erosive, corrosive, and/or abrasive or contain fillers or additives that are tacky, erosive, corrosive, and/or abrasive, and for which a particular surface treatment or assemblage of such surface treatments has not collectively proven effective across the range of pelletizing system components, over the temperature ranges involved in the various stages of processing, and/or over the processing conditions necessary for that process.
In a preferred embodiment, the present invention is a method for the surface treatment of components of equipment for a pelletization sequence comprising providing equipment of the pelletization sequence, and surface treating at least a portion of at least one component of the pelletization sequence with at least one component layer, wherein the surface treatment protects the at least a portion of at least one component of the pelletization sequence from action of pellets formed and from by-products of the pelletization sequence. The surface treatment can comprise at least two component layers.
The present method can further comprise pretreating the at least a portion of at least one component of the pelletization sequence prior to surface treatment, and/or over-layering a polymeric coating on the surface treatment.
The surface treatment can be metallization, and can fixedly attach metal oxides, metal nitrides, metal carbonitrides, diamond-like carbon to the at least a portion of at least one component of the pelletization sequence
The polymeric coating can be non-adhesive, have uniform surface wetting, be silicone, a fluoropolymer, and/or a combination of silicone and fluoropolymers.
The polymeric coating can be self-drying and/or curing, and be applied by reactive polymerization.
In a preferred embodiment, the present invention is a method for surface treatment of components of equipment for a pelletization sequence wherein said pelletization sequence includes pelletization, transport, drying, cooling, and optional crystallization of pellets formed and wherein the surface treatment is at least one component layer that protects said components from abrasion, erosion, corrosion, and wear from action of the pellets formed and from by-products of the pelletization sequence and wherein the surface treatment prevents obstruction and blockage of process pathways and of the process itself by preventing adhesion, accumulation, agglomeration, and clumping, of the pellets formed by the process.
Thus, an object of the present invention is to provide a method for and sequence of surface treatment of at least one layer to protect the surfaces of the many components throughout the processing equipment of a pelletizing sequence from the effects of abrasion, erosion, corrosion, and wear. The present invention can alleviate and prevent undue adhesion of the pellets produced leading to the prior art problems of accumulation, agglomeration, clumping, and potential obstruction and blockage of the passageways in the process and ultimately the process itself.
Another object of the present invention is to provide a surface coating or assemblage of such coatings for various components of an apparatus or combination of apparatuses used in a pelletization sequence, that pelletizes, transports, dries, and sufficiently cools and optionally crystallizes a polymeric or polymer-like product that can be corrosive, erosive, and/or abrasive, or emits corrosive and/or erosive by-products, and that is initially or ultimately possesses a high degree of tack and/or can contain abrasive, corrosive and/or erosive fillers and/or subsequently forms, by that apparatus or assemblage of such, an abrasive, corrosive, and/or erosive pellet. The present surface treatment also limits/prevents obstruction and blockage of the process pathways and of the process itself by limiting/preventing adhesion, accumulation, agglomeration, and clumping of the pellets formed by the process.
Another object of the present invention is to provide a surface treatment composed of at least two component layers for components of a pelletization sequence.
A further object of the present invention is to provide surface treatments for components of a pelletization sequence wherein the components can be prepared for such treatments by at least one preparation process including, but not limited to, cleaning, degreasing, etching, primer coating, roughening, grit-blasting, peening, pickling, acid-wash, base-wash, corona treatment, plasma treatment, and many combinations of these.
Yet another object of the present invention is to provide at least one surface treatment of components of a pelletization sequence wherein the surface treatment is composed of at least one material including metals, inorganic salts, inorganic oxides, inorganic carbides, inorganic nitrides, inorganic carbonitrides, corrosion inhibitors, sacrificial electrodes, conductors, optical reflectors, pigments, passivating agents, radiation modifiers, primers, topcoats, adhesives, synthetic diamond, and polymers. These polymers can include urethanes and fluorourethanes, polyolefins and substituted polyolefins, polyesters, polyamides, fluoropolymers, polycarbonates, polyacetals, polysulfides, polysulfones, polyamideimides, polyethers, polyetherketones, silicones, and many combinations of these.
Still another object of the present invention is to apply surface treatment to specific pelletizing system components, including to the inner surface of the diverter valve, the outer surface of the nose cone of the die, the inlet surface of the die body, the inlet surface of the removable insert of a die, and/or the inlet surface of the heated removable insert of a die. Additionally, the surface treatments can be applied to the area surrounding the die hole as well as into and through the die holes in the die body, the removable insert, and/or the heated removable insert. The surface treatment can include at least one of sintering, flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatment, high velocity air and fuel modified thermal treatment, vacuum treatment, chemical vapor deposition, physical vapor deposition, sputtering techniques, electrolytic plasma treatment and many combinations of these treatments. The surface treatment can include metallization, attachment of metal oxides, metal nitrides, metal carbonitrides, and diamond-like carbon, and combinations of these preferentially including attachment of diamond-like carbon in a metal matrix and attachment of diamond-like carbon in a metal carbide matrix.
Yet another object of the present invention is to apply surface treatment to other specific components of the pelletizing system, including to the inner surface of the flange, the lumens of the inlet and outlet pipe, the exterior surface of the die body, the outer surface of the exposed portion of the rotor shaft, the outlet and inlet flow surfaces of the flow guide, the flow guide faces distal and proximal from the aforementioned flange, the lumen and circumferential surfaces of the flow guide, the cutter hub and arm surfaces, the inner surfaces of the upper and lower feed chutes, the inner surface of the dryer base plate assembly, the exterior surface of the pipe shaft protector, the surface of the feed screen, the surface of the dewatering screen, the surface of the screen assemblies, the surface of the lifter assemblies, the exterior surface of the support ring assemblies, the inner surface of the upper portion of the dryer housing, the inner surface of the pellet chutes, the exterior surface of the pellet diverter plate, the inner surface of the optional pellet chute extension, the inner surfaces of the vibratory unit housings, the surface of the vibratory unit screen, the surface of the coating pan, the surfaces of the deflector and retainer weirs, the outer surface of the cylindrical core, the upper surface of the baseplate, and/or the inner surface of the vibratory unit cover assemblies. The surface treatment can include at least one of flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatment, electrolytic plasma treatment and many combinations of these treatments. The surface treatment can include metallization, attachment of metal oxides, metal nitrides, metal carbonitrides, and diamond-like carbon and combinations of these preferentially including attachment of diamond-like carbon in a metal matrix and attachment of diamond-like carbon in a metal carbide matrix. These surface treatments can be over-coated with a polymeric layer that preferentially is non-adhesive and has uniform surface wetting including silicones, fluoropolymers, and combinations of these. This polymeric overcoat preferentially does not require input of energy and/or heat to effect drying and/or curing, or alternatively, as used herein, self drying and/or curing. The polymeric overcoat can be applied by at least one of dip coating, roll coating, spray coating, reactive polymerization, sintering, thermal spray, flame spray, plasma treatment, and powder coating. The reactive polymerization can include at least one of thermal cure, moisture cure, photoinitiated polymerization, free-radical polymerization, vulcanization, room temperature vulcanization, and cross-linking.
Still another object of the present invention is to apply surface treatment to the tip, edge, and circumferential surfaces of the cutting blade by at least one of flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatment, electrolytic plasma treatment and many combinations of these. The surface treatment can include metallization, attachment of metal oxides, metal nitrides, metal carbonitrides, and diamond-like carbon, and combinations of these preferentially including attachment of diamond-like carbon in a metal matrix and attachment of diamond-like carbon in a metal carbide matrix.
Additionally, an object of the present invention is to apply surface treatment to the angle elbow to which is attached the air-injection inlet valve. The surface treatment can include at least one of flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatment, high velocity air and fuel modified thermal treatment, vacuum treatment, chemical vapor deposition, physical vapor deposition, sputtering techniques, electrolytic plasma treatment and many combinations of these treatments. The surface treatment can include metallization, attachment of metal oxides, metal nitrides, metal carbonitrides, and diamond-like carbon and combinations of these preferentially including attachment of diamond-like carbon in a metal matrix and attachment of diamond-like carbon in a metal carbide matrix. These surface treatments can be over-coated with a polymeric layer that preferentially is non-adhesive and has uniform surface wetting including silicones, fluoropolymers, and combinations of these. This polymeric overcoat preferentially does not require input of energy and/or heat to effect drying and/or curing. The polymeric overcoat can be applied by at least one of dip coating, roll coating, spray coating, reactive polymerization, sintering, thermal spray, flame spray, plasma treatment, and powder coating. The reactive polymerization can include at least one of thermal cure, moisture cure, photoinitiated polymerization, free-radical polymerization, vulcanization, room temperature vulcanization, and cross-linking.
Another object of the present invention is to apply surface treatment to the inner surface of the dryer housing and/or the inner surface of the dewater unit housing by rotational molding processes. These processes can include application of at least one of reactive polymers, polyolefins, polyethylene, polypropylene, cross-linkable polyethylene, vinyl polymers, polyester, polyamide, polycarbonate, and fluoropolymers. Preferentially, polyethylene, cross-linkable polyethylene and/or fluoropolymers are applied.
Those components to which the present surface treatments are applied are not operationally compromised as to their function.
These and other objects, features and advantages of the present invention will become more apparent upon reading the following specification in conjunction with the accompanying drawings.
a is a schematic illustration of a mixing vessel, medium pressure pump, and coarse screen changer.
b is a schematic illustration of a feeder, gear pump, and static mixer assembly.
a illustrates the three configurations of the heating element extracted from the die plate.
b illustrates the three configurations of the heating element positionally placed individually in side view.
a is a schematic illustration of a complete assembly of a comparative two-piece waterbox or transport fluid box.
b is a cross-sectional illustration of an alternative waterbox or transport fluid box inlet and outlet design.
c is a schematic face-view illustration of the alternative waterbox or transport fluid box inlet and outlet design of
a is a schematic illustration of a comparative flow guide.
b is a schematic illustration of a second configuration of a comparative flow guide.
a is a schematic view of a portion of a streamline cutter hub.
b is a schematic view of the streamline cutter hub rotated in perspective relative to
c is a cross-sectional view of the streamline cutter hub in
a is a schematic illustration of a comparative cutter hub with attached normal angle blade.
b is a schematic illustration of a steep angle cutter hub with attached blade.
c is a schematic illustration of a comparative perpendicular angle cutter hub with attached non-tapered or square-cut blunted tip blade.
d is a schematic illustration of a cutter hub with attached reduced thickness blade at normal angle.
a is a vertical schematic view of a vibratory unit with deflector weir and pan for powder treatment of pellets.
b is a side view illustration of a vibratory unit with deflector weir and pan for powder treatment of pellets.
a is a vertical schematic view of a vibratory unit with deflector weir and retainer weirs for enhanced crystallization of pellets.
b is a side view illustration of a vibratory unit with deflector weir and retainer weirs for enhanced crystallization of pellets.
Although preferred embodiments of the invention are explained in detail, it is to be understood that other embodiments are possible. Accordingly, it is not intended that the invention is to be limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. Also, in describing the preferred embodiments, specific terminology will be resorted to for the sake of clarity. Reference numbers for parts and coated parts can be different and coated regions ascribed to that part can be different, larger or smaller for example, than are areas specific to that part.
The pelletization sequence of which multiple components can be surface treated, including coatings, in accordance with the extant invention preferably includes extrusion of a polymer melt formulation through an underwater pelletizer with subsequent drying as shown in
In feeding section 1 material or component materials are fed into the mixing section 2 manually as a solid or liquid, preferably liquids can be pumped or metered, not shown, into the mixing apparatus and solids can be added via a feed screw 10 as indicated in
The mixing section 2 of the present invention includes dynamic 2a, extrusional 2b, and/or static 2c mixing components that can be used individually or as a plurality of two or more of these component types interconnectedly attached in series, in tandem, and/or in parallel.
The feed screw outlet 12 of feeding section 1,
On reaching the appropriate pour point valve 24 is opened and the fluid or molten material passes into and through pipe 26 and is drawn into booster pump 30. The booster pump 30 can be, for example, a centrifugal pump or a positive displacement reciprocating or rotary pump. Preferably, the booster pump 30 is rotary and can be a peristaltic, vane, screw, lobe, progressive cavity, or more preferably, a gear pump. The gear pump can be high precision or preferably is open clearance and generates an intermediate pressure, typically up to approximately 33 bar and preferably less than approximately 10 bar. The pump pressure is sufficient to force the melt through coarse filter 35 that can be a candle filter, basket filter, or screen changer, and is more preferably a basket filter of 20 mesh or coarser. The coarse filter 35 removes larger particles, agglomerates, or granular material from the melt as it flows to and through pipe 32. The dotted line 40a indicates the connection to melt pump 80.
Alternatively the feeding section 1 in
Analogously feeding section 1 can be connected via feed screw outlet 12 to inlet 14c in the static mixing section 2c in
Mixing sections can be used alone or in combination where dynamic, extrusional, and/or static mixing as described herein are connected in series and/or in parallel. Exemplary of this is dynamic mixing section 2a attached directly to static mixing section 2d at inlet 14d or extrusional mixing section 2b attached directly to static mixing section 2d at inlet 14d or alternatively to static mixing section 2c at inlet 14c of bypass static mixer 100 as detailed below. Extrusional mixing section 2b alternatively can be attached to another extrusional mixing section in series and/or in parallel of similar or different design type or configuration. Temperatures and process parameters can be the same or different in the various mixing sections and mixing units can be attached in combinations greater than two serially or otherwise.
Ingredients, liquid or solid, can be added utilizing the feeding section (or sections) 1 herein described connected at one or more locations including, but not limited to, inlets 14a, 14b, 14c, or 14d. For dynamic mixing, components are added at inlet 14a or preferably for volatiles at inlet position 75 proximal to inlet 14c. Where dynamic mixing is attached serially to static mixing (not shown in
Various levels of mixing and shear are achieved by the differing styles of mixing processes. Static mixing typically has the least shear and relies more on thermal energy. Dynamic mixing depends to a large degree on blade design and mixer design. Extrusional mixing varies with type of screw, number of screws, and the screw profile and is quite capable of significant generation of shear energy. Therefore, energy is introduced into the mixing process in terms of both shear or mechanical energy and thermal energy. Heating and/or cooling of the units can be achieved electrically, by steam, or by circulation of thermally controlled liquids such as oil or water. Mixing continues until a formulation reaches an appropriate temperature or other criterion of consistency or viscosity as determined or known specifically for the process by those appropriately skilled in the art.
On exit from the mixing stage 2a, 2b, 2c, or 2d, or any combination thereof, the molten or fluidized material optionally passes to and through a melt pump 80 that generates additional pressure on the melt, preferably at least 10 bar and more preferably 30 bar to 250 bar or more. Pressures required are dependent on the material being processed and are significantly affected by the pelletization process 3 that follows mixing as well as on the throughput rate or flow rate of the process. Melt pump 80 can be a centrifugal or positive displacement reciprocating or rotary pump, and preferably is a rotary pump that can be a peristaltic, vane, screw, lobe, progressive cavity, or gear pump, and more preferably is a gear pump. Seals should be compatible with the material being processed, chemically and mechanically, the details of which are well understood by those skilled in the art.
The pressurized melt passes through a filter 90 that is preferably a basket filter or screen changer, and is more preferably a screen changer of 200 mesh or coarser, and even more preferably a multilayer screen changer of two or more screens of differing mesh, most preferably a series of filters exemplary of which is 20 mesh, 40 mesh, and 80 mesh. The screen changer can be manual, plate, slide plate, rotary plate, single or dual bolt, and can be continuous or discontinuous.
The use of melt pump 80 and/or filter 90 is included herein and their use strongly and optionally dependent on the containment of volatile ingredients, if any, in the formulation. Pressures can be sufficient from extrusional mixing 2b to forego use of melt pump 80 whereas use of static and/or dynamic mixing, 2a or 2d, can require facilitation of pressurization to insure progress through and egress of the formulation from the apparatus. The filter 90 provides a safety mechanism, where employed, to insure oversize particles, lumps, amorphous masses, or agglomerates are not propagated to the bypass static mixer 100 or pelletization process 3. Alternatively, introduction of any volatile components can be performed at inlet position 75 proximal to inlet 14c in
Static mixer 60 in
The optional bypass static mixer 100 in
The outlet of optional filter 90 is attachedly connected to the bypass static mixer 100 in
The valve components 162 and 164 are preferably in the form of movable bolts, valve component 162 being upstream of the static mixing component 150 and valve component 164 is similarly downstream. The bolts contain, but are not limited to, two (2) bores exemplary of which is valve component 164, or three (3) bores of which valve component 162 is an example, or more bores. The respective bores can be straight-through, form a 90° turn or in the shape of a “tee or T”, and are specifically placed along the length of the bolt. Each of these bores is positionally placed by means of a fluid-controlled cylinder or equivalent device, and will adjustably maintain good alignment with the proper inlets and/or outlets of the bypass diverter valve 120, based on the desired position required by the operator running the process, as will be understood by those skilled in the art. The positioning of the fluid powered cylinders, and thus each bolt's position, can be controlled by manually operating a fluid flow valve or by automatic control such as by PLC, or both.
The component or components of the mixing section 2 are attachedly connected to the diverter valve 200, as indicated in
Use of surface treatments and coatings for components in sections 1 and 2 of
Referring again to
The die 320 in
Heating elements 330 can be a cartridge or more preferably a coil type element and can be of sufficient length inside the die body 324 to remain outside the circumference of the die holes as illustrated in
A preferred design of die 320 is illustrated in
The die 320 in all configurations (
The bolting mechanism for the nose cone 322 is illustrated in
Diverter valve outlet 206 is comprised of an inner bore that is tapered diametrically and conically in increasing diameter to create a chamber continuously and proportionately larger than nose cone 322 that inserts therein. The volume of the chamber thusly generated allows unobstructed flow of the polymeric material or other molten or liquid material to flow from the diverter valve 200 into the die hole 340. Alternatively, an adapter (not shown) can be attached to diverter valve outlet 206 which is accordingly tapered as described herein to accommodate the nose cone 322.
The diverter valve outlet 206 and alternative adapter (not shown), nose cone 322, and die body 324 in
To provide a smooth surface for die holes 340 in
In an embodiment of the present invention, sintering, flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatments, high velocity air and fuel modified thermal treatments, and electrolytic plasma treatments, singly and in combinations thereof, can be applied to the inner surface 1802 of the diverter valve outlet or alternative adapter, the outer surface 1804 of nose cone 322, and inlet surface 1806 of die body 324 in
Referring once again to
Similarly,
An exploded view of the two-piece configuration of transport fluid box or waterbox 400 is illustrated in
b and 12c illustrate an alternative design for the transport fluid box or waterbox inlet and outlet in that inlet 480 is fixedly attached to a rectangular or square inlet tube 482 that taperingly increases along its length as it approaches the housing 481 to which it is attachedly connected and within which is cutting chamber 484. Similarly attached to housing 481 and diametrically opposed to inlet tube 482 is rectangular or square outlet tube 486 that taperingly decreases along its length to outlet 488 to which it is fixedly attached. Flange 483 and flange 485 in
a, b, and c illustrate the preferred diametrically opposed inlets and outlets. Alternatively, the inlets, 454 and 480, and outlets, 456 and 488, can be located at an angle from 20° to the preferred 180° relative to and defined by the position of outlet to inlet and can be opposingly or staggeringly attached to housing 481 by way of example. Dimensions of the inlet and outlet can be the same or different, and the inlet and outlet can be similar or different in design. Preferably the inlet and outlet so identified are of similar dimension and design, and are diametrically opposed.
Returning to
Additionally, in an embodiment of the present invention, flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatments, and electrolytic plasma treatments, singly and in combinations thereof, can be applied to the inner surface 1812 of flange 466 and the lumens 1818 of inlet pipe 454 and outlet pipe 456 (lumen not shown) and exterior surface 1814 and exposed surface 1816 of die body 320. Exposed surface 1816 is subject to significant erosive effects of potential cavitation within the open cutting chamber 458. These treatments metallize the surface, preferably fixedly attach metal nitrides to the surface, more preferably fixedly attach metal carbides and metal carbonitrides to the surface, even more preferably fixedly attach diamond-like carbon to the surface, still more preferably attach diamond-like carbon in an abrasion-resistant metal matrix to the surface, and most preferably attach diamond-like carbon in a metal carbide matrix to the surface. Other ceramic materials can be used and are included herein by way of reference without intending to be limited.
These preferred surface treatments of this embodiment of the present invention can be further modified by application of a polymeric coating on the surface distal from the component substrate to reduce pellet adhesion, stricture, accumulation, and agglomeration to limit or prevent obstruction and blockage of the passageways. Preferably, the polymeric coatings are themselves non-adhesive and of low coefficient of friction. More preferably, the polymeric coatings are silicones, fluoropolymers, and combinations thereof. Most preferably, the application of the polymeric coatings requires minimal to no heating to effect drying and/or curing. Application of the coatings can be accomplished by dip coating, roll coating, spray coating, reactive polymerization, sintering, thermal spray, flame spray, plasma treatment, and powder coating techniques. Reactive polymerization can include thermal cure, moisture cure, photoinitiated polymerization, free-radical polymerization, vulcanization, room temperature vulcanization, and cross-linking. The benefits of polymeric coating can include the reduction of porosity of the metallization and ceramic processes, to provide additional surface leveling and modification, reduction of friction at the surface, to reduce the potential for abrasion of the treated surface on the pellets, and many combinations thereof.
Once again returning to the principle disclosure illustration in
The pelletizer 900 of the instant invention is shown diagrammatically in
To increase fluid velocity through the cutting chamber 458, improve pellet quality, reduce freeze off, avoid wrapping of melt around die face 410, generate or increase head pressure, and improve pellet geometry,
Continuing with
The cutter arms 610 and body of cutter hub 612 can be square or preferably rectangular in cross-section as shown in
Alternatively,
The cutter blade 750 and half-thickness blade 770 compositionally include, but are not limited to, tool steel, stainless steel, nickel and nickel alloys, metal-ceramic composites, ceramics, metal or metal carbide composites, carbides, vanadium hardened steel, suitably hardened plastic, or other comparably durable material and can be further annealed and hardened as is well known to those skilled in the art. Wear-resistance, corrosion resistance, durability, wear lifetime, chemical resistance, and abrasion resistance are some of the important concepts influencing the utility of a particular blade relative to the formulation being pelletized. Blade dimensions of length, width, and thickness as well as number of blades used relationally with cutter hub design are not limited within the scope of the present invention.
Returning to
Similarly, conventional nitriding, carbonitriding, sintering, high velocity air and fuel modified thermal treatments, and electrolytic plating can also be applied to the surfaces of flow guide 800 (
Additionally, in an embodiment of the present invention, flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatments, and electrolytic plasma treatments, singly and in combinations thereof, can be applied to the outer surface 1820 of the exposed portion of the rotor shaft 930 that extends out from the transport fluid box or waterbox flange 466 into cutting chamber 458 (
These preferred surface treatments of this embodiment of the present invention, preferentially excepting tip surfaces 1836 and 1838, edge surface 1840, and circumferential blade surface 1842 as illustrated in
Additionally processing aids, flow modifiers, surface modifiers, coatings, surface treatments including antistats and various additives known to those skilled in the art can be accommodated in the transport fluid. Piping, valving, and bypass components should be of suitable construction to withstand the temperature, chemical composition, abrasivity, corrosivity, and/or any pressure requisite to the proper transport of the pellet-transport fluid mixture. Any pressure required by the system is determined by the transport distance, vertical and horizontal, pressure level needed to suppress unwanted volatilization of components or premature expansion, pellet-transport fluid slurry flow through valving, coarse screening, and ancillary process and/or monitoring equipment. Pellet-to-transport fluid ratios should similarly be of varying proportions to be satisfactorily effective in eliminating or alleviating the above-mention complicating circumstances exemplary of which are pellet accumulation, flow blockage or obstruction, and agglomeration. Piping diameter and distances required are determined by the material throughput, thus the flow rate and pellet-to-transport fluid ratio, and time required to achieve an appropriate level of cooling and/or solidification of the pellets to avoid undesirable volatilization and/or premature expansion. Valving, gauges, or other processing and monitoring equipment should be of sufficient flow and pressure rating as well as of sufficient throughpass diameter to avoid undue blockage, obstruction or otherwise alter the process leading to additional and undesirable pressure generation or process occlusion. Transport fluid and additive composition should be compatible with the components of the pellet formulation and should not be readily absorbed into or adsorbed onto any of the components in that formulation. Excess transport fluid and/or additives should be readily removable from the pellets by such methods as rinsing, aspiration, evaporation, dewatering, solvent removal, filtration, or a similar technique understood by those skilled in the art.
Pump 500 and heat exchanger 520 in
The standard bypass loop 550, as illustrated in
Once the pellet is sufficiently solidified for processing, it is transported via pipe 1270 to and through an agglomerate catcher/dewatering unit 1300 and into the drying unit 1400, and downstream processes 2000, as illustrated in
Wherein crystallization of the pellets is a part of the process, the standard bypass loop 550 is optionally replaced with a direct pathway between the transport fluid box or waterbox 400 and the dryer 1400 such that pressurized air can be injected into that pathway as illustrated in
To those skilled in the art, flow rates and pipe diameters can vary according to the throughput volume, level of crystallinity desired, and the size of the pellets and granules. The high velocity air or inert gas effectively contacts the pellet water slurry generating water vapor by aspiration, and disperses the pellets throughout the slurry line propagating those pellets at increased velocity into the dryer 1400, preferably at a rate of less than one second from the transport fluid box or waterbox 400 to the dryer exit 1950 (
Abrasion, erosion, corrosion, wear, and undesirable adhesion and stricture can be problematic in transport piping as illustrated
In a preferred embodiment of the present invention, angle elbow 1908 in
The drying unit or dryer 1400, illustrated in
Turning now to
As illustrated in
A vertical rotor 1425 is mounted for rotation within the screen 1500 and is rotatably driven by a motor 1430 that can be mounted at and/or connected to the base of the dryer (
The housing 1410 is of sectional construction connected at a flanged coupling, not shown, at a lower end portion of the dryer and a flanged coupling, not illustrated, at the upper end portion of the dryer. The uppermost flange coupling is connected to a top plate 1480 that supports bearing structure 1440 and drive connection 1435 that are enclosed by a housing or guard 1437. A coupling 1432 atop the housing 1437 supports the motor 1430 and maintains all of the components in assembled relation.
The lower end of the housing 1410 is connected to a bottom plate 1412 on top of a water tank or reservoir 1600 by a flange connection 1610 as illustrated in
The self-cleaning structure of the disclosed dryer includes a plurality of spray nozzles or spray head assemblies 1702 supported between the interior of the housing 1410 and the exterior of the screen 1500 as illustrated in
There are preferably at least three spray head assemblies 1702 and related spray pipes 1700 and lines 1706. The spray head assembly 1702 and pipes 1700 are oriented in circumferentially spaced relation peripherally of the screen 1500 and oriented in staggered vertical relation so that pressurized fluid discharged from the spray head assembly 1702 will contact and clean the screen 1500, inside and out, as well as the interior of the housing 1410. Thus, collected pellets that can have accumulated or lodged in hang-up points or areas between the outside surface of the screen 1500 and inside wall of the housing 1410 are flushed through apertures 1612 into the reservoir 1600,
The region between the screen support section 1450 at the lower end of the dryer and the inner wall of the housing 1410 includes flat areas at the port openings and seams that connect the components of the dryer housing together. The high pressure water from the spray head assembly 1702 effectively rinses this region as well. The base screen support section 1450 is attached to the bottom plate 1412 of the housing 1410 and reservoir 1600 by screws or other fasteners to stationarily secure the housing and screen to the reservoir 1600. The base screen support section 1450 is in the form of a tub or basin as shown in
The rotor 1425 includes a substantially tubular member 1427 provided with inclined rotor blades 1485 thereon for lifting and elevating the pellets and subsequently impacting them against the screen 1500. In other dryers, the rotor 1410 can be square, round, hexagon, octagon or other shape in cross-section. A hollow shaft 1432 extends through the rotor 1425 in concentric spaced relation to the tubular member 1427 forming the rotor. The hollow shaft guides the lower end of the rotor as it extends through an opening 1482 in a guide bushing 1488 at the lower end of the rotor 1425, as well as aligned openings in bottom plate 1412 and the top wall of the reservoir 1600, respectively. A rotary coupling 1490 is connected to the hollow shaft 1432 and to a source of fluid pressure, preferably air (not shown) through hose or line 1492 to pressurize the interior of the hollow shaft 1432.
The hollow shaft 1432 includes apertures to communicate the shaft 1432 with the interior of the hollow rotor member 1427. These holes introduce the pressurized fluid, preferably air, into the interior of the rotor 1425. The rotor 1425 in turn has apertures in the bottom wall that communicate the bottom end of the rotor 1425 with the interior of the base or tub section 1450 to enable the lower end of the rotor 1425 and the tub section 1450 to be cleaned. Pellets flushed from the rotor and inside screen 1500 are discharged preferentially through the dried pellet outlet chute 1460.
The top of the rotor 1425 inside top section 1455 is also a hang-up point and subjected to high pressure fluid, preferably air, to dislodge accumulated pellets. As shown in
In addition to hang-up points or areas occurring in the dryer structure, the agglomerate catcher 1300 can also be cleaned by a separate pipe or hose 1720 controlled by a solenoid valve that directs high pressure fluid onto the pellet contact side of the angled agglomerate grate or catcher plate and bar rod grid 1310 to clean off agglomerates that are then discharged through the discharge tube or chute 1305.
A hose and nozzle supply bursts of air to discharge chute or pipe 1460 in a direction such that it cleans the top of the rotor 1425 and the pellet discharge outlet 1460. The air discharge blows pellets past pipe connections and the diverter plate 1465 in outlet 1467 for discharge of dried pellets out of the dryer.
The rotor 1425 is preferably continuously turning during the full cleaning cycle. Solenoid valves are provided to supply air preferably at about between 60 psi to 80 psi, or more, to additional hang-up points not shown that include the water box bypass air port, rotor air ports, top section air port, pellet outlet air port and diverter valve air port. The solenoid valves include timers to provide short air bursts, preferably about three seconds, which cleans well and does not require a lot of time. A clean cycle button (not shown) activates the cleaning cycle with the water box bypass air port being energized first to allow air to purge the bypass with a multiplicity of air bursts, preferably five or more. The top section air port is then activated. This is followed sequentially with activation of the diverter plate 1465. This valve closes prior to activation of the spray nozzle assembly 1702 that washes the screen for one to ten seconds, preferably about six seconds. The blower 1760 should be deactivated during the water spray cycles and is then reactivated when the spray nozzle pump is de-energized thus completing one cleaning cycle. The cycle as herein described is not limited in scope and each component of the cycle can be varied in frequency and/or duration as necessitated to achieve appropriate removal of the residual pellets.
Blower 1760 in
The screens for the process include none, one or more horizontal or vertical dewatering screens 1325, inclined dewatering screen 1335, port screens 1595, and/or one or more cylindrically attachable screens 1500 as illustrated in
The screens 1500 are preferably of suitably flexible construction as to be circumferentially placed around the dryer 1400 and rotor 1425 and can contain deflector bars 1550 as illustrated in
The outer support screen 1510 can be composed of molded plastic or wire-reinforced plastic and compositionally can be polyethylene, polypropylene, polyester, polyamide or nylon, polyvinyl chloride, polyurethane, or similarly inert material that capably maintains its structural integrity under chemical and physical conditions anticipated in the operation of the centrifugal pellet dryers. Preferably the outer support screen 1510 is a metal plate of suitable thickness to maintain the structural integrity of the overall screen assembly and flexible enough to be contoured, exemplarily cylindrically, to fit tightly and positionally in the appropriate centrifugal pellet dryer. The metal plate is preferably 18 gauge to 24 gauge and most preferably is 20 to 24 gauge in thickness. The metal can compositionally be aluminum, copper, steel, stainless steel, nickel steel alloy, or similarly non-reactive material inert to the components of the drying process. Preferably the metal is stainless steel, and most preferably is Grade 304 or Grade 316 stainless steel as necessitated environmentally by the chemical processes undergoing the drying operation.
The metal plate can be pierced, punched, perforated, or slotted to form openings that can be round, oval, square, rectangular, triangular, polygonal, or other dimensionally equivalent structures to provide open areas for separation and subsequent drying. Preferably the openings are round perforations and geometrically staggered to provide the maximum open area while retaining the structural integrity of the outer support screen. The round perforations are preferably at least approximately 0.075 inches (approximately 1.9 mm) in diameter and are positionally staggered to provide an open area of at least 30%. More preferred is an open area geometric orientation such that the effective open area is 40% or more. Most preferred are round perforations having a diameter of at least approximately 0.1875 inches (approximately 4.7 mm) that are positionally staggered to achieve an open area of 50% or more.
Alternatively, the outer support screen can be an assembled structure or screen composed of wires, rods, or bars, stacked angularly or orthogonally, or interwoven, and welded, brazed, resistance welded or otherwise permanently adhered in position. The wires, rods, or bars can be plastic or wire-reinforced plastic compositionally similar to the molded plastic described above or can be metal, similarly and compositionally delineated as above and can be geometrically round, oval, square, rectangular, triangular or wedge-shaped, polygonal or structurally similar. The wires, rods, or bars across the width or warp of the screen can be the same as or different dimensionally as the wires, rods, or bars longitudinally contained as the weft, shute, or otherwise known to those skilled in the art.
Preferably the wires, rods, or bars are a minimum of approximately 0.020 inches (approximately 0.5 mm) in the narrowest dimension, more preferably are at least approximately 0.030 inches (approximately 0.76 mm) in the narrowest dimension, and most preferably are approximately 0.047 inches (approximately 1.2 mm) in the narrowest dimension. Open areas are dimensionally dependent on the proximal placement of adjacent structural elements and are positionally placed so as to maintain a percent open area of at least approximately 30%, more preferably above approximately 40%, and most preferably approximately 50% or greater.
The optional middle screen 1520 or screens and the inner screen 1530 are structurally similar to that described herein for the outer support screen. Dimensionally and compositionally the screens in the respective layers can be similar or different. The percent open area of the respective screens can be similar or different wherein lesser percent open area will reduce the effective open area of the screen and the least percent open area will be the most restrictive and therefore the delimiting percent open area for the screen assembly. The orientation of any screen relative to other layers of the assembly as well as the dimension and structural composition of the screens can be similar or different.
The inner screen 1530 is preferably a woven wire screen that can be in a square, rectangular, plain, Dutch or similar weave wherein the warp and weft wire diameters can be the same or different dimensionally or compositionally. More preferably the inner screen is a plain square or rectangular weave wire screen wherein the warp and weft wires are similar compositionally and dimensionally and the open area is approximately 30% or greater. Even more preferably, the inner layer screen is plain square or rectangular 30 mesh or larger mesh grade 304 or grade 316 stainless steel, wherein the warp and weft wires are of a size to allow at least approximately 30% open area and most preferably are approximately 50% open area. Still more preferred is an inner screen of a plain square or rectangular weave of 50 mesh or greater mesh, with a percent open area of approximately 50% or greater. If incorporated, the middle screen 1520 would be of a mesh intermediate between the support screen 1510 and the inner screen 1530, and can be similar or different structurally, geometrically, compositionally, and orientationally. The two-layer screen is the preferred composition as delineated in the disclosure.
Returning to
Additionally, in an embodiment of the present invention, flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatments, and electrolytic plasma treatments, singly and in combinations thereof, can be applied to the inner surface of the upper feed chute 1844, the inner surface of the lower feed chute 1846, the inner surface of the base plate assembly 1848, the exterior surface of the pipe shaft protector 1850, the surface of the feed screen 1852 and the surface of the dewatering screen 1854 (
These preferred surface treatments of this embodiment of the present invention can be further modified by application of a polymeric coating on the surface distal from the component substrate to reduce pellet adhesion, stricture, accumulation, and agglomeration to limit or prevent obstruction and blockage of the passageways. Preferably, the polymeric coatings are themselves non-adhesive and of low coefficient of friction. More preferably, the polymeric coatings are silicones, fluoropolymers, and combinations thereof. Most preferably, the application of the polymeric coatings requires minimal to no heating to effect drying and/or curing. The methods or application and benefits provided by these treatments for these components follow from those previously described herein.
Additionally, the inner surface of dryer housing 1870 in
Pellets discharged from the pellet discharge chute 1460 can be sized, sieved, packaged, additionally dried or subjected to further processing such as fluidization or transported for storage or immediate manipulation in accordance with the process requirements. Many of these post-drying processes exemplary of which are sizing, pellet coating, and enhancement of crystallization, can involve use of vibratory units.
Coatings can be applied to the substantially dried pellets by directing the flow of pellets from the pellet outlet chute 1460 in
The coated pellet ultimately is vibratably shaken from the coating pan 2102 onto sizing screen 2104 and circumnavigates the screen effectively removing excipient coating material that passes through the screen and is expelled from the apparatus through an outlet 2114,
Coatings can be applied to pellets to reduce or eliminate tack, to provide supplementary structural integrity to the pellet, to introduce additional chemical and/or physical properties, and to provide color and other esthetic enhancement. Exemplary of coating materials can be, but are not limited to, talc, carbon, graphite, fly ash, wax including microcrystalline, detackifying agents, calcium carbonate, pigments, clay, wollastonite, minerals, inorganic salts, silica, polymeric powders, and organic powders. Preferably, the coating materials are powders.
a and 36b illustrate an alternative eccentric vibratory unit 2150 that can increase residence time allowing additional drying, cooling, and/or preferably crystallization and any combination thereof. The unit 2150 comprises a solid plate 2152 circumferentially enclosed by and fixedly attached to the unit housing 2154. Centrally attached onto the solid plate 2152 is a cylindrical core 2156 to which are attachedly and perpendicularly connected at least one and, preferably, a plurality of weirs. Deflector weir 2162 is fixedly attached to the unit housing 2154 distally from the cylindrical core 2156 and adjacent to outlet 2158. Preferably at least one (1) retainer weir 2160 and more preferably at least two (2) retainer weirs 2160 are similarly attached to the cylindrical core 2156 and the unit housing 2154. Retainer weir or a plurality thereof are lower in height than is the deflector weir 2162, and preferably are one-half the height of the deflector weir 2156. Retainer weirs 2160 are circumferentially placed around the unit 2150 and can be positioned symmetrically, asymmetrically, or both. The unit is fittedly attached with cover 2170.
Pellets are fed into unit 2150 on the side of the deflector weir 2162 remote from outlet 2158. Movement of pellets occurs circumferentially about the unit 2150 until a retainer weir 2160 is encountered, if any, against which pellet volume accumulates until such volume exceeds the height of retainer weir 2160 and pellets fall over to migrate vibrationally therearound to the next retainer weir 2160 or deflector weir 2162 as determined by design of unit 2150. Upon encounter of the pellet and the deflector weir 2156, movement of the pellet is redirected to and through outlet 2158. The design and mechanism of operation of that eccentric vibratory unit 2150 are well known to those skilled in the art. Increasing the number of retainer weirs 2160 increases the volume of pellets allowed to accumulate; thusly, increasing the residence time the pellets are retained by the eccentric vibratory unit 2150. Variance of the number and/or height of the retainer weirs 2160 can enhance the effective drying, cooling, and crystallization times for the pellets. On deflection to and through outlet 2158, the pellets can be transported to additional post-processing and/or storage as required.
The present invention anticipates that other designs of eccentric vibratory units, oscillatory units, and their equivalent known to those skilled in the art can be used effectively to achieve comparable results as disclosed herein. Components of the assemblies for the eccentric vibratory units described herein can be metal, plastic or other durable composition and are preferably made of stainless steel, and most preferably are made of 304 stainless steel. The shape of the vibratory units in
Referring again to
Additionally, in an embodiment of the present invention, flame spray, thermal spray, plasma treatment, electroless nickel dispersion treatments, and electrolytic plasma treatments, singly and in combinations thereof, can be applied to the inner surface of housings 1874 and 1876, the surface of screen 1878, the surface of coating pan 1880, the surface of deflector weir 1882, the surfaces of deflector weir 1884 and the surfaces of retainer weirs 1886, the outer surface of the cylindrical core 1888, the upper surface of baseplate 1890, and the inner surface of cover assemblies 1892 and 1894. These treatments metallize the surface, preferably fixedly attach metal nitrides to the surface, more preferably fixedly attach metal carbides and metal carbonitrides to the surface, even more preferably fixedly attach diamond-like carbon to the surface, still more preferably attach diamond-like carbon in an abrasion-resistant metal matrix to the surface, and most preferably attach diamond-like carbon in a metal carbide matrix to the surface. Other ceramic materials can be used and are included herein by way of reference without intending to be limited.
The preferred surface treatments of this embodiment of the present invention can be further modified by application of a polymeric coating on the surface distal from the component substrate to reduce pellet adhesion, stricture, accumulation, and agglomeration to limit or prevent obstruction and blockage of the passageways. Preferably, the polymeric coatings are themselves non-adhesive and of low coefficient of friction. More preferably, the polymeric coatings are silicones, fluoropolymers, and combinations thereof. Most preferably, the application of the polymeric coatings requires minimal to no heating to effect drying and/or curing. The methods or application and benefits provided by these treatments for these components follow from those previously described herein.
Surface treatments as described herein can involve at least one, preferably two, and optionally multiple processes inclusive and exemplary of which are cleaning, degreasing, etching, primer coating, roughening, grit-blasting, sand-blasting, peening, pickling, acid-wash, base-wash, nitriding, carbonitriding, electroplating, electroless plating, flame spraying including high velocity applications, thermal spraying, plasma spraying, sintering, dip coating, powder coating, vacuum deposition, chemical vapor deposition, physical vapor deposition, sputtering techniques, spray coating, roll coating, rod coating, extrusion, rotational molding, slush molding, and reactive coatings utilizing thermal, radiational, and/or photoinitiation cure techniques, nitriding, carbonitriding, phosphating, and forming one or more layers thereon. The layers can be similar in composition, different in composition, and many combinations thereof in multiple layer configurations.
Materials applied utilizing these processes can include at least one of metals, inorganic salts, inorganic oxides, inorganic carbides, inorganic nitrides, inorganic carbonitrides, corrosion inhibitors, sacrificial electrodes, primers, conductors, optical reflectors, pigments, passivating agents, radiation modifiers, primers, topcoats, adhesives, and polymers including urethanes and fluorourethanes, polyolefins and substituted polyolefins, polyesters, polyamides, fluoropolymers, polycarbonates, polyacetals, polysulfides, polysulfones, polyamideimides, polyethers, polyetherketones, silicones, and the like without intending to be limited. The inorganic salts, inorganic oxides, inorganic carbides, inorganic nitrides, and inorganic carbonitrides are preferably metal salts, metal oxides, metal carbides, metal nitrides, and metal carbonitrides respectively.
While the invention has been disclosed in its preferred forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents as set forth in the following claims.
