Patent Application
20090173485
The present invention relates generally to the field of air-cooled heat exchangers, and specifically to fin tube assemblies for air-cooled heat exchangers and methods of manufacturing the same.
Air-cooled heat exchangers are of use in a variety of industrial applications, particularly in applications where there is a scarcity of water for use as a cooling medium. Air-cooled steam condensers are a particular type of heat exchanger employed to condense steam. Condensers are widely used in the industrial, chemical, petrochemical and energy industries.
Air-cooled steam condensers typically include a number of fin tube assemblies connected in parallel. The fin tube assemblies typically comprise elongated core tubes of circular or non-circular cross-section and sets of fins attached to the outer surface of the core tubes to increase heat transfer from the fluid within the core tube to the surrounding air atmosphere by increasing the surface area The fins are typically crated of highly thermal conductive materials. In operation, steam (or other fluid) flows through the inside of the tubes while cooling air flows outside of the tube along the fins.
Typically, a finned tube assembly for air cooled condenser application in present day technology is formed by taking a rounded tube made of carbon steel, stainless steel and flattening the tube so that the vertical cross-section is noncircular. The tube is coated with aluminum and aluminum fins are then brazed to the tube. Brazing fins to core tubes is well known and the standard in the art.
Existing fin tube assemblies for air-cooled heat exchanger, and methods of manufacturing the same are disclosed in the following: (1) U.S. Pat. No. 7,293,602, to Nadig et al., issued Nov. 13, 2007; (2) U.S. Pat. No. 7,243,712, to Fay, issued Jul. 17, 2007; (3) U.S. Pat. No. 7,165,606, to Take, issued Jan. 23, 2007; (4) U.S. Pat. No. 6,332,494, to Bodas et al, issued Dec. 25, 2001; (5) U.S. Pat. No. 6,142,223, to Bodas et al, issued Nov. 7, 2000; and (6) U.S. Pat. No. 6,000,461, to Ross et al., issued Dec. 14, 1999, the entireties of which are incorporated by reference.
While the aforementioned fin tube assemblies, and methods of manufacture, are suitable in many way, all of these suffer from one or more drawbacks, including complexity of manufacture, less than optimal heat transfer, use of expensive materials, and expensive manufacturing, which results in high end costs.
It is an object of the present invention to provide a fin tube assembly for use in air cooled heat exchangers, and a method of manufacturing the same.
Another object of the present invention is to provide a fin tube assembly for use in air cooled heat exchangers, and method of manufacture, that is free of brazing.
Yet another object of the present invention is to provide a fin tube assembly for use in air cooled heat exchangers, and method of manufacture, that is easy, quick and cost effective to manufacture.
Still another object of the present invention is to provide a fin tube assembly for use in air cooled heat exchangers, and method of manufacture, having fins welded directly to the core tube without the use of a filler material.
A further object of the present invention is to provide a robust fin tube assembly for use in air cooled heat exchangers, and method of manufacture.
A yet further object of the present invention is to provide a fin tube assembly for use in air cooled heat exchangers, and method of manufacture, that utilizes a multi-part core tube.
A still further object of the present invention is to provide a fin tube assembly for use in air cooled heat exchangers, and method of manufacture, that is corrosion resistant.
These and other objects are met by the present invention which in one aspect can be a fin tube assembly for an air-cooled heat exchanger comprising: a core tube having an internal passageway for carrying a fluid to be cooled, the core tube having a non-circular transverse cross-section; and at least one set of fins welded to an outside surface of the core tube. It is preferred, in some embodiments, that the at least one set of fins be welded directly to the outside surface of the core tube using a fusion welding technique that does not use a filler material.
Preferably, the at least one set of fins can be a corrugated sheet having peaks terminating in ridges and valleys terminating in floors. More preferably, the floors of the valleys of the corrugated sheet can be contiguously laser welded to the outside surface of the core tube. Most preferably, the floors of the valleys comprise a substantially flat section that can be contiguously laser welded to the outside surface of the core tube.
In another aspect, the invention can be a fin tube assembly for an air-cooled heat exchanger comprising: a core tube having an inner surface forming a passageway for carrying a fluid to be cooled and an outsider surface having a first substantially flat face and a second substantially flat face opposite the first substantially flat face; the core tube constructed from a single flat plate structure bent into the shape of the core tube so that a longitudinal interface exists, the longitudinal interface being contiguously welded to form the core tube; and a set of fins connected to each of the first and second substantially flat faces.
In yet another aspect, the invention can be a fin tube assembly for an air-cooled heat exchanger comprising: a core tube having an inner surface forming a passageway for carrying a fluid to be cooled and an outsider surface having a first substantially flat face and a second substantially flat face opposite the first substantially flat face; the core tube constructed from a first flat plate structure bent into a first transverse section of the core tube and a second flat plate structure bent into a second transverse section of the core tube, the first and second transverse sections arranged in an adjacent manner so that first and second longitudinal interfaces exist, the first and second longitudinal interfaces being contiguously welded to form the core tube; at least one of the first or second longitudinal interfaces formed by either (1) contact between lateral edges of the first and second transverse sections, the lateral edges being butt welded together, or (2) contact between bottom surfaces of lateral flanges formed into the first transverse section and top surfaces of lateral flanges formed into the second transverse section, the lateral flanges being fusion welded together; and a set of fins connected to each of the first and second substantially flat faces.
In still another aspect, the invention can be a fin tube assembly for an air-cooled heat exchanger comprising: a core tube having an inner surface that forms an internal passageway for carrying a fluid to be cooled, the core tube having a non-circular transverse cross-section; at least one set of fins connected to an outside surface of the core tube; and a baked phenolic or zinc-based coating covering the at least one set of fins and the core tube.
In a further aspect, the invention can be a method of manufacturing a fin tube assembly for an air-cooled heat exchanger comprising: a) providing a core tube having an inner surface that forms an internal passageway for carrying a fluid to be cooled, the core tube having a non-circular transverse cross-section; b) providing at least one set of fins; and c) welding the at least one set of fins to the outside surface of the core tube using a fusion welding technique that does not use a filler material.
In a yet further aspect, the invention can be a method of manufacturing a fin tube assembly for an air-cooled heat exchanger comprising: a) providing a substantially flat plat structure having a first lateral edge, a second lateral edge, a first end edge, a second end edge, a first major surface, and a second major surface, the first and second end edges defining a longitudinal length of the substantially flat plat structure; b) providing a first set of fins and a second set of fins; c) welding the first set of fins to a first portion of the first major surface of the substantially flat plat structure using a fusion welding technique that does not use a filler material, the first set of fins spaced from the first lateral edge so that the first major surface has a first perimeter portion extending longitudinally between the first set of fins and the first lateral edge that is free of fins; d) welding the second set of fins to a second portion of the first major surface of the substantially flat plat structure using the fusion welding technique, the second set of fins spaced from the first set of fins and the second lateral edge so that the first major surface has an elongated portion extending longitudinally between the first and second set of fins that is free of fins and a second perimeter portion extending longitudinally between the second set of fins and the second lateral edge that is free of fins; e) bending the first and second perimeter portions of the substantially flat plat structure to extend from a plane formed by the second major surface of the substantially flat plat structure; f) bending the substantially flat plat structure being bent along the elongated portion so that the first and second portions of the first major surface are on opposite surfaces and the bent first and second perimeter portions contact one another forming a longitudinal interface; and g) contiguously welding the longitudinal interface to form a core tube wherein the second major surface forms an internal passageway of the core tube and the first major surface forms an outside surface of the core tube.
In a still further aspect, the invention can be a method of manufacturing a fin tube assembly for an air-cooled heat exchanger comprising: a) providing a core tube having an inner surface that forms an internal passageway for carrying a fluid to be cooled, the core tube having a non-circular transverse cross-section; b) providing at least one set of fins; c) connecting at least one set of fins to the outside surface of the core tube. and d) coating the at least one set of fins and the core tube with a baked phenolic coating or a zinc-based coating.
In an even further aspect, the invention can be a method of manufacturing a fin tube assembly for an air-cooled heat exchanger comprising: a) providing a substantially flat plat structure having a first lateral edge, a second lateral edge, a first end edge, a second end edge, a first major surface, and a second major surface, the first and second end edges defining a longitudinal length of the substantially flat plat structure; b) providing a first set of fins and a second set of fins; c) connecting the first set of fins to a first area of the first major surface of the substantially flat plat structure, the first set of fins spaced from the first lateral edge so that the substantially flat plat structure has a first portion extending longitudinally between the first set of fins and the first lateral edge that is free of fins; d) connecting the second set of fins to a second area of the first major surface of the substantially flat plat structure, the second set of fins spaced from the first set of fins and the second lateral edge so that the substantially flat plat structure has a second portion extending longitudinally between the first and second set of fins that is free of fins and a third portion extending longitudinally between the second set of fins and the second lateral edge that is free of fins; e) bending the first and third portions of the substantially flat plat structure to extend from a plane formed by the second major surface of the substantially flat plat structure; f) bending the substantially flat plat structure along the second portion so that the first and second areas of the first major surface are on opposite surfaces and the bent first and third portions contact one another forming a longitudinal interface; and g) contiguously welding the longitudinal interface to form a core tube wherein the second major surface forms an internal passageway of the core tube and the first major surface forms an outside surface of the core tube.
In another aspect, the invention can be a method of manufacturing a fin tube assembly for an air-cooled heat exchanger comprising: a) providing a first substantially flat plate structure having a first lateral edge, a second later edge, a first major surface and a second major surface; b) providing a second substantially flat plate structure having a first lateral edge, a second later edge, a first major surface and a second major surface; c) connecting a first set of fins to the first major surface of the first substantially flat plate structure; d) connecting a second set of fins to the first major surface of the second substantially flat plate structure; e) bending the first substantially flat plate structure into a first transverse section of a core tube; f) bending the second substantially flat plate structure into a second transverse section of a core tube; g) arranging the first and second transverse sections in an adjacent manner so as to form first and second longitudinal interfaces; and h) contiguously welding the first and second longitudinal interfaces to form the core tube having a internal passageway formed by the second major surface of the first and second transverse sections.
In even another aspect, the invention can be a method of manufacturing a fin tube assembly for an air-cooled heat exchanger comprising: a) providing a plurality of first substantially flat plate structures; b) connecting at least one set of fins to one of the plurality of substantially flat plate structures; c) bending the plurality of flat plate structures into transverse sections of a core tube; d) arranging the transverse sections in an adjacent manner so as to form a plurality of longitudinal interfaces; and e) contiguously welding the plurality of longitudinal interfaces to form the core tube having a internal passageway and an outer surface comprising the at least one set of fins.
In another aspect, the invention can be a fin tube assembly for an air-cooled heat exchanger comprising: a core tube having an inner surface that forms an internal passageway for carrying a fluid to be cooled; at least one set of fins connected to an outside surface of the core tube; and wherein the outside surface of the core tube and the at least one set of fins is subjected to a ferretic nitrocarburization process.
In yet another aspect, the invention can be a method of manufacturing a fin tube assembly for an air-cooled heat exchanger comprising: a) providing a core tube having an inner surface that forms an internal passageway for carrying a fluid to be cooled, at least one set of fins connected to an outside surface of the core tube; and b) performing a surface conversion process to the at least one set of fins and the outside surface of the core tube that increases corrosion resistance. In one embodiment, it is preferred that the surface conversion process be a ferritic nitrocarburization process.
Referring first to
Generally, the fin tube assembly 100 comprises an elongated core tube 10 and two sets of cooling fins 20A-B. The core tube 10 has an inner surface 11 that forms a longitudinal internal passageway 40 and an outer surface 12 to which the two sets of fins 20A-B are connected. The internal passageway 40 is a extends from an opening at a proximal end 13 of the fin tube assembly 100 to an opening at a distal end 14 of the fin tube assembly 100. The internal passageway 40 is a hermetically sealed fluid conduit for transporting fluids, such as steam and other vapors, therethrough to facilitate the removal of heat from the fluid while keeping the fluid isolated from the surrounding atmosphere.
The core tube 10 (and the resulting internal passageway 40) has a transverse cross-section that is non-circular. In the illustrated embodiment, the core tube 10 generally comprises two opposing substantially flat sections 15, 16 that are connected by lateral sections (which, in this embodiment, are formed by lateral flanges 114-115 and 122-123). Of course, the invention is not so limited and the core tube can take on a wide variety of transverse cross-sectional shapes that are non-circular.
The core tube 10 extends a longitudinal length LL. In some embodiments, the longitudinal length LL may be between 20 to 60 feet. The width (not marked in the figures) of the core tube 10 is preferably in a range between 4 to 18 inches. The thickness of the core tube 10 can be, in some embodiments, 0.035 to 0.12 inches. Of course, the invention is not so limited and the longitudinal length LL, width and thickness can be any desired measurement. Moreover, while the core tube 10 is exemplified as extending along a linear longitudinal axis, the core tube 10, in other embodiments, can include curves, bends and/or angles.
The core tube 10 is preferably constructed of a metal or other material that effectively conducts heat. For example, and without limitation, the core tube 10 can be constructed of copper, aluminum, carbon, stainless steel, or combination thereof. Of course, other materials can be used.
The sets of fins 20A-B are preferably connected to the outside surface 12 of the substantially flat portions 15, 16 on opposite sides of the fin tube assembly 100. Preferably, in some embodiments of the invention, the sets of fins 20A-B will be connected directly to the core tube via a fusion welding technique that does not use a filler materials, such as a laser welding technique. The details of the connection of the sets of fins 20A-B to the core tube 10 will be described in greater detail below with respect to
Referring now to
The top plate structure 10A comprises a first lateral edge 110, a second lateral edge 111, a proximal end edge 112 and a distal end edge 113. The top plate structure 10A comprises the flat portion 15 and first and second lateral flanges 114, 115 that extend downward and laterally outward from the flat portion 15. The lateral flanges 114, 115 have bottom surfaces 116, 117 respectively, and terminate in the lateral edges 110, 111.
Similarly, the bottom plate structure 10B comprises a first lateral edge 118, a second lateral edge 119, a proximal end edge 120 and a distal end edge 121. The bottom plate structure 10B comprises the flat portion 16 and first and second lateral flanges 122, 123 that extend upward and laterally outward from the flat portion 16. The lateral flanges 122, 123 have top surfaces 124, 125 respectively, and terminate in the lateral edges 118, 119.
The first set of fins 20A is connected to the substantially flat top surface of the flat portion 15 of the top plate structure 10A while the second set of fins 20B is connected to the substantially flat bottom surface of the flat portion 16 of the bottom plate structure 10B.
Each set of the fins 20A, 20B is preferably a corrugated sheet of material having a high coefficient of thermal conductivity, such as aluminum, carbon steel, stainless steel, copper or combinations thereof. The corrugated sheets 20A, 20B can be of any length. Either a single or a plurality of the corrugated sheets can be used to cover the entire longitudinal length LL of a single face of the fin tube assembly 100. The dimensional and structural details of the corrugated sheets will be described below in greater detail with respect to
Referring now to
The combination of the first lateral flanges 114, 122 form a first longitudinal ridge 30 that protrudes from the outside surface 12 of a first side of the core tube 10 along the length LL of the fin tube assembly 100. Similarly, the combination of the second lateral flanges 115, 123 form a second longitudinal ridge 31 that protrudes from the outside surface 12 of a second side of the core tube 10 along the length LL of the fin tube assembly 100. The first and second longitudinal ridges 30, 31 (and the interfaces 126, 127) are opposite one another and 180 degrees apart about a central longitudinal axis X-X (visible only as point X in
In the illustrated embodiment of
In order to make the internal passageway 40 a fluid-tight conduit for carrying a fluid to be cooled, the first flanges 114, 122 of the top and bottom plate structures 10A, 10B are contiguously welded together, thereby connecting the top and bottom plate structures 10A, 10B together on one side and hermetically sealing the first longitudinal interface 126. Similarly, the second flanges 115, 123 of the top and bottom plate structures 10A, 10B are also contiguously welded together, thereby connecting the top and bottom plate structures 10A, 10B together on the other side and hermetically sealing the second longitudinal interface 127. The contiguous welding of the first flanges 114, 122 and/or the second flanges 115, 123 can be accomplished using any suitable welding technique that uses or does not use a filler material, including without limitation resistance seam welding, manual metal arc welding, metal inert gas welding, tungsten inert gas welding, submerged arc welding, plasma arc welding, gas welding, electroslag welding, electron beam welding, laser welding, thermit welding, resistance spot welding and/or combinations thereof. Most preferably, a resistance seam welding process is used.
Referring now to
The first set of fins 20A is connected to the substantially flat upper/outer surface of the flat portion 15 of the top plate structure 10A by welding. More specifically, all of the floors 24A of the first set of fins 20A are directly welded to the top plate structure 10A by using a fusion welding technique that does not utilize a filler material so as to ensure adequate thermal conduction between the first set of fins 20A and the core tube 10. One such suitable fusion welding technique is laser welding.
In one embodiment, all of the floors 24A of the first set of fins 20A are fusion welded in a stitched manner to the top plate structure 10A along the entire fin width WF. In another embodiment, all of the floors 24A of the first set of fins 20A are contiguously fusion welded to the top plate structure 10A along the entire fin width WF. Of course, a combination of both contiguous fusion welding and stitch fusion welding techniques can be used for different floors 24A of fins 20A for the same fin tube assembly 100 if desired. In
In embodiments where a stitch fusion welding is used to connect the sets of fins 20A, 20B to the core tube 10, it may be preferable to coat the entire fin tube assembly 100 with a metal-based coating after the welding to achieve intimate contact between the entireties of the floors 24A, 24B so as to facilitate thermal conduction between the core tube 10 and the fins 20A, 20B. In one such specific application, the fin tube assembly 100 (i.e., the assembly of the fins 20A, 20B stitch fusion welded to the assembled core tube lo) is dipped into a zinc or aluminum based liquid bath. As a result, the metal-based liquid enters and fills any gaps that may exists between the floors 24A, 24B of the fins 20A, 20B and the core tube 10. The fin-tube assembly is 100 then is allowed to cool. Of course, other metal-based coating can be used.
Finally, irrespective of whether a stitch or contiguous welding technique is used, the assembled fin tube assembly 100 can be coated with a corrosive resistant material so as to withstand operating and environmental conditions without substantial degradation. Suitable coatings include, without limitation, a metal-based coating or a baked phenol coating. Suitable metal-based coatings include without limitation zinc-based coatings and aluminum-based coatings. In order to minimize impedance of thermal transfer, the coating is less than 100 microns in some embodiments. As discussed, below, in other embodiments the fin tube assembly 100 can be made corrosion resistant by subjecting the assembly to a surface conversion process, such as ferritic nitrocarburization.
In one embodiment, the sets of fins will have a thickness between 0.005 to 0.015 inches and a height between 0.25 and 1.0 inches. The invention how ever is not limited to any specific dimensions. It is to be understood that the sets of fins 20A, 20B can take on a wide variety of shapes, sizes, thicknesses, structural arrangements and orientations on the core tube 10. None of which are limiting of the present invention unless specifically stated in the claims.
In
Referring now to
The first set of fins 20A′ is a orthogonally corrugated sheet of material, such as a metal or other thermally conductive material. The first set of fins 20A′ comprises a plurality of orthogonally undulating and alternating peaks 21A′ and valleys 22A′ (only some of which are numerically indicated to avoid clutter in the drawings). The peaks 21A′ respectively terminate in apex surfaces 23A′ while the valleys 22A′ terminate in flat floor surfaces 24A′.
For mass production of the fin tube assembly 100, the orthogonally corrugated shape of the fin set 20A′ may be preferable in some regards to the fin set 20A because of the flat floor surfaces 24A′. Creating the fin set 20A′ so that its floor surfaces 24A′ have a substantially flat portion increases the surface area which is in direct contact with the outside surface of the core tube during the direct fusion welding connection process (discussed above). As a result, adequate laser welding of the fin set 20A′ to the core tube 10 can be more easily and more reliably achieved without the need for extreme tolerances and precision in moving the laser torch across the fin width WF (same as that shown in
It should be noted that in some embodiments of the invention, the benefits of the flat floor surface 24A′ can be achieved without having the fin set 20A′ being of a purely orthogonal shape. In such embodiments, the walls and peaks may be angled and/or curved.
Referring now to
The first set of fins 20A″ comprise a plurality of separate L-shaped fins 28A″ that are individually laser welded to the core tube 10. While the individual fins 28A″ are orthogonal shaped, they can be curved or bent in other shapes if desired. Stated simply, it is to be understood that the sets of fins in the present invention do not have to formed out of a single piece of material but can be individually formed and welded to the core tube.
In
Referring now to
The main difference between the core tube 10′ and the core tube 10 is the shape of the lateral flanges 114′-115′, 122′-123′ of the top and bottom plate structures 10A′, 10B′. In this embodiment, the lateral flanges 114′, 115′ of the top plate structure 10A′ extend downward and inward from the flat portion 15′ of the top plate structure 10A′. Conversely, the lateral flanges 122′, 123′ of the bottom plate structure 10B′ extend upward and inward from the flat portion 16′ of the bottom plate structure 10B′.
As a result, when arranging the top and bottom plate structures 10A′, 10B′ in an adjacent and aligned orientation the bottom surfaces 116′, 117′ of the lateral flanges 114′, 115′ of the top plate structure 10A′ (which are now formed by the outer surface 12′ of the core tube) come into surface contact with the top surfaces 124′, 125′ of the lateral flanges 122′, 123′ of the bottom plate structure 10B′ (which are also formed by the outer surface 12′), thereby forming the two longitudinal interfaces 126′, 127′.
The combination of the first lateral flanges 114′, 122′ form a first longitudinal ridge 30′ that protrudes into the internal passageway 40′ from a first side of the core tube 10′ along the length LL of the fin tube assembly 100′. Similarly, the combination of the second lateral flanges 115′, 123′ form a second longitudinal ridge 31′ that also protrudes into the internal passageway 40′ from a second side of the core tube 10′ along the length LL of the fin tube assembly 100′.
As above, in order to make the internal passageway 40′ a fluid-tight conduit for carrying a fluid to be cooled, the first flanges 114′, 122′ of the top and bottom plate structures 10A′, 10B′ are contiguously welded together along the first and second longitudinal interfaces 126′, 127′, thereby connecting the top and bottom plate structures 10A′, 10B′. The contiguous welding of the first flanges 114′, 122′ and/or the second flanges 115′, 123′ can be accomplished using any suitable welding technique that uses or does not use a filler material, including without limitation resistance seam welding, manual metal arc welding, metal inert gas welding, tungsten inert gas welding, submerged arc welding, plasma arc welding, gas welding, electroslag welding, electron beam welding, laser welding, thermit welding, resistance spot welding and/or combinations thereof. Most preferably, a resistance seam welding process is used.
Referring now to
The main difference between the core tube 10″ and the core tube 10 is the shape of the lateral flanges 114″-115″, 122″-123″ of the top and bottom plate structures 10A″, 10B″. In this embodiment, the lateral flanges 114″, 115″ of the top plate structure 10A″ extend only downward from the flat portion 15″ of the top plate structure 10A″. Conversely, the lateral flanges 122″, 123″ of the bottom plate structure 10B″ extend only upward from the flat portion 16″ of the bottom plate structure 10B″. More specifically, the lateral flanges 114″-115″, 122″-123″ are bent into generally 90 degree curved sections. Of course, in alternative embodiments the lateral flanges 114″-115″, 122″-123″ can merely extend at a right angle to the flat portions 15″, 16″.
When the top and bottom plate structures 10A″, 10B″ are arranged in the adjacent and aligned orientation illustrated, the lateral edges 110″, 111″ of the top plate structure 10A″ come into contact and abut the lateral edges 118″, 119″ of the bottom plate structure 10B″, thereby forming the two longitudinal interfaces 126″, 127″.
As above, in order to make the internal passageway 40″ a fluid-tight conduit for carrying a fluid to be cooled, the top and bottom plate structures 10A″, 10B″ are contiguously welded together along the first and second longitudinal interfaces 126″, 127″, thereby connecting the top and bottom plate structures 10A″, 10B″. A butt welding technique is preferably used in this embodiment that does or does not use a filler material. Suitable welding techniques include without limitation resistance seam welding, manual metal arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, gas welding, electron beam welding, laser welding, induction welding, high frequency welding and/or combinations thereof.
Referring now to
The main difference between the core tube 10′″ and the core tube 10 is the shape of the lateral flanges 114′″-115′″, 122′″-123′″ of the top and bottom plate structures 10A′″, 10B′″. In this embodiment, the lateral flanges 114′″, 115′″ of the top plate structure 10A′ extend only downward from the flat portion 15′″ of the top plate structure 10A′″. Conversely, the lateral flanges 122′″, 123′″ of the bottom plate structure 10B′″ extend only upward from the flat portion 16′″ of the bottom plate structure 10B′″. More specifically, the lateral flanges 114′″-115′″, 122′″-123′″ are bent into generally 90 degree curved sections. Of course, in alternative embodiments the lateral flanges 114′″-115′″, 122′″-123′″ can merely extend at a right angle to the flat portions 15′″, 16′″.
The top plate structure 10B′″ is wider than the top plate structure 10A′″. When the top and bottom plate structures 10A′″, 10B′″ are in the adjacent and aligned orientation, a portion of the top plate structure 10A′″ nests within the bottom plate structure 10B′″. As a result, the bottom surfaces 116′″, 117′″ of the lateral flanges 114′″, 115′″ of the top plate structure 10A′″ (which are now formed by the outer surface 12′″) come into surface contact with the top surfaces 124′″, 125′″ of the lateral flanges 122′″, 123′″ of the bottom plate structure 10B′″ (which are now formed by the inner surface 11′″), thereby forming the two longitudinal interfaces 126′″, 127′″.
As above, in order to make the internal passageway 40′″ a fluid-tight conduit for carrying a fluid to be cooled, the first and second longitudinal interfaces 126′″, 127′″ are contiguously welded shut, thereby connecting the top and bottom plate structures 10A′″, 10B′″. This contiguous welding can be accomplished using any suitable welding technique that uses or does not use a filler material. Suitable welding techniques include without limitation resistance seam welding, manual metal arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, gas welding, electron beam welding, laser welding, induction welding, high frequency welding and/or combinations thereof.
In
Referring first to
The main difference between the fin tube assembly 1100 and fin tube assembly 100 is the construction of the core tube 1010 out of a single plate structure 1010 rather than a multi-part assembly of transverse sections. In this embodiment, a single plate structure 1010A forms the entirety of the transverse cross-section of the core tube 1010. As will be discussed in greater detail below, the single plate structure 1010A begins the manufacturing process as a substantially flat plate structure and is bent, rolled and otherwise formed into the transverse shape shown in
The plate structure 1010A comprises an outer surface 1012, an inner surface 1011, a first lateral edge 1110, and a second lateral edge 1111. A first lateral flange 1114 is formed into the plate structure 1010A near the first lateral edge 1110 while a second lateral flange 1115 is formed into the plate structure 1010A near the second lateral edge 1111. The plate structure 1010A is bent in an approximately 180 degree curved bend between the top flat portion 1015 and the bottom flat portion 1016 until the bottom surface 1116 of the first lateral flange 1114 comes into surface contact with the top surface 1117 of the second lateral flange 1115, thereby forming the first (and only) longitudinal interface 1126. As a result, the one lateral side 1070 of the core tube 1010 is unitary and free of a longitudinal interface, thus eliminating the need for a weld. The sole longitudinal interface 1126 is located on the opposite lateral side 1071 of the core tube 1010.
The first lateral flange 1114 and the second lateral flange 1115 form a single longitudinal ridge 1030 extending and protruding outward from the outside surface 1012 of the core tube 1010. As with the other embodiments of this kind, in order to make the internal passageways 1040 a fluid-tight conduit for carrying a fluid to be cooled, the longitudinal interface 1126 is contiguously welded shut, thereby connecting the first lateral flange 1114 and the second lateral flange 1115. This contiguous welding can be accomplished using any suitable welding technique that uses or does not use a filler material. Suitable welding techniques include without limitation resistance seam welding, manual metal arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, gas welding, electron beam welding, laser welding, induction welding, high frequency welding and/or combinations thereof. Most preferably, a resistance seam welding process is used.
Referring now to
The main difference between the fin tube assembly 2100 and fin tube assembly 100 is the construction of the core tube 2010 out of a single plate structure 2010 rather than a multi-part assembly of transverse sections. In this embodiment, a single plate structure 2010A forms the entirety of the transverse cross-section of the core tube 2010. As will be discussed in greater detail below, the single plate structure 2010A begins the manufacturing process as a substantially flat plate structure and is bent, rolled and otherwise formed into the transverse shape shown in
The plate structure 2010A comprises an outer surface 2012, an inner surface 2011, a first lateral edge 2110, and a second lateral edge 2111. A first lateral flange 2114 is formed into the plate structure 2010A near the first lateral edge 2110 while a second lateral flange 2115 is formed into the plate structure 2010A near the second lateral edge 2111. The plate structure 2010A is bent in an approximately 180 degree curved bend between the top flat portion 2015 and the bottom flat portion 2016 until the bottom surface 2116 of the first lateral flange 2114 comes into surface contact with the top surface 2117 of the second lateral flange 2115, thereby forming the first (and only) longitudinal interface 2126. As a result, the one lateral side 2070 of the core tube 2010 is unitary and free of a longitudinal interface, thus eliminating the need for a weld. The sole longitudinal interface 2126 is located on the opposite lateral side 2071 of the core tube 1010.
The first lateral flange 2114 and the second lateral flange 2115 form a single longitudinal ridge 2030 extending inward into the internal passageway 2040 of the core tube 2010. As with the other embodiments of this kind, in order to make the internal passageway 2040 a fluid-tight conduit for carrying a fluid to be cooled, the longitudinal interface 2126 is contiguously welded shut, thereby hermetically connecting the first lateral flange 2114 and the second lateral flange 2115. This contiguous welding can be accomplished using any suitable welding technique that uses or does not use a filler material. Suitable welding techniques include without limitation resistance seam welding, manual metal arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, gas welding, electron beam welding, laser welding, induction welding, high frequency welding and/or combinations thereof. Most preferably, a resistance seam welding process is used.
Referring now to
The main difference between the fin tube assembly 3100 and fin tube assembly 100 is the construction of the core tube 3010 out of a single plate structure 3010 rather than a multi-part assembly of transverse sections. In this embodiment, a single plate structure 3010A forms the entirety of the transverse cross-section of the core tube 3010. As will be discussed in greater detail below, the single plate structure 3010A begins the manufacturing process as a substantially flat plate structure and is bent, rolled and otherwise formed into the transverse shape shown in
The plate structure 3010A comprises an outer surface 3012, an inner surface 3011, a first lateral edge 3110, and a second lateral edge 3111. A first lateral flange 3114 is formed into the plate structure 3010A near the first lateral edge 3110 while a second lateral flange 3115 is formed into the plate structure 3010A near the second lateral edge 3111. The first and second lateral flanges 3114, 3115 are formed as 90 degree bends. The plate structure 3010A is bent in an approximately 180 degree curved bend between the top flat portion 3015 and the bottom flat portion 3016 until the first lateral edge 3110 comes into contact with the second lateral edge 3111, thereby forming the first (and only) longitudinal interface 3126. As a result, the one lateral side 3070 of the core tube 3010 is unitary and free of a longitudinal interface, thus eliminating the need for a weld. The sole longitudinal interface 3126 is located on the opposite lateral side 3071 of the core tube 3010.
As with the other embodiments of this kind, in order to make the internal passageway 3040 a fluid-tight conduit for carrying a fluid to be cooled, the longitudinal interface 3126 is contiguously welded shut, thereby hermetically connecting the first lateral edge 3110 and the second lateral edge 3111. A butt welding technique is preferably used in this embodiment that does or does not use a filler material. Suitable welding techniques include without limitation resistance seam welding, manual metal arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, gas welding, electron beam welding, laser welding, induction welding, high frequency welding and/or combinations thereof.
Referring now to
The main difference between the fin tube assembly 4100 and fin tube assembly 100 is the construction of the core tube 4010 out of a single plate structure 4010 rather than a multi-part assembly of transverse sections. In this embodiment, a single plate structure 4010A forms the entirety of the transverse cross-section of the core tube 4010. As will be discussed in greater detail below, the single plate structure 4010A begins the manufacturing process as a substantially flat plate structure and is bent, rolled and otherwise formed into the transverse shape shown in
The plate structure 4010A comprises an outer surface 4012, an inner surface 4011, a first lateral edge 4110, and a second lateral edge 4111. A first lateral flange 4114 is formed into the plate structure 4010A near the first lateral edge 4110 while a second lateral flange 4115 is formed into the plate structure 4010A near the second lateral edge 4111. The first and second lateral flanges 4114, 4115 are formed as 90 degree bends. The plate structure 4010A is bent in an approximately 180 degree curved bend between the top flat portion 4015 and the bottom flat portion 4016 until the bottom surface 4116 (formed in this embodiment by the outside surface 4012) of the first lateral flange 4114 comes into surface contact with the top surface 4117 (formed in this embodiment by the inner surface 4011) of the second lateral flange 4115, thereby forming the first (and only) longitudinal interface 4126. The bottom flat portion 4016 is wider than the top flat portion 4015 so as to create the offset during the bending.
The one lateral side 4070 of the core tube 4010 is unitary and free of a longitudinal interface, thus eliminating the need for a weld. The sole longitudinal interface 4126 is located on the opposite lateral side 4071 of the core tube 4010. As with the other embodiments of this kind, in order to make the internal passageway 4040 a fluid-tight conduit for carrying a fluid to be cooled, the longitudinal interface 4126 is contiguously welded shut, thereby hermetically connecting the first lateral flange 4114 and the second lateral flange 4115. This contiguous welding can be accomplished using any suitable welding technique that uses or does not use a filler material. Suitable welding techniques include without limitation resistance seam welding, manual metal arc welding, gas metal arc welding, gas tungsten arc welding, plasma arc welding, gas welding, electron beam welding, laser welding, induction welding, high frequency welding and/or combinations thereof. Most preferably, a resistance seam welding process is used.
In all of the embodiments illustrated in
Referring now to
The outside surface 5081 of the first material layer 5080 is in substantially intimate surface contact with the inner surface 5091 of the second material layer 5090 so as to not negatively impact thermal conduction between the two layers 5080, 5090 in a significant manner. The connection of the layers 5080, 5090 can be accomplished via a cladding or compression rolling process.
The first and second layers 5080, 5090 can be constructed of the same or different materials. Suitable materials include without limitation copper, aluminum, carbon steel and stainless steel. It may be preferred that the first/inner layer 5080 be constructed of a material having a higher coefficient of thermal expansion than the second/outer layer 5090 so as to ensure intimate surface contact under elevated thermal conditions.
While two-layers of material are exemplified in the multi-layer core tube 5010, any number of layers can be used as desired. Moreover, While the core tube 5010 is of the single-plate structure type, it is to be understood that the multi-layer concept can be applied, without limitation, to any of the multi-part core-tube configurations disclosed above in
Referring now to
The first and second layers 5025, 5026 can be constructed of the same or different materials. Suitable materials include without limitation copper, aluminum, carbon steel, and stainless steel. When connected to a core tube, the bottom surface 5029 of the second layer 5026 contacts the outer surface of the core tube. In an embodiment where a multi-layer fin set 5020 is to be welded directly to the core tube using a fusion welding technique that does not use a filler material, the first material layer 5025 should be constructed of a material that metallurgically compatible with the material of the core tube for welding purposes.
While two-layers of material are exemplified in the multi-layer fin set 5020, any number of layers can be used as desired. Moreover, the multi-layer fin concept can be applied to any of the fin types discussed above in
It should finally be noted that any of the structural alterative discussed above with respect to
Two examples of method of manufacturing fin tube assemblies in accordance with the present invention are described in greater detail below. It is to be understood that the general principles of manufacture discussed below can be utilized to create any of the fin tube assembly embodiments discussed above in
Beginning with
Referring now to
Once the first and second set of fins 3020A, 3020B are created (or otherwise obtained), the first set of fins 3020A are positioned atop the top surface 3012 of the flat plate structure 3010A extending longitudinally between the end edges. Similarly, the second set of fins 3020B are also positioned atop the top major surface 3012 of the flat plate structure 3010A extending longitudinally between the end edges. Of course, the first and second sets of fins 3020A, 3020B do not have to extend the entire longitudinal length of the plate 3010A.
The first set of fins 3020A are positioned atop the top major surface 3012 of the flat plate structure 3010A spaced from and near the right lateral edge 3110. The second set of fins 3020B are also positioned atop the top major surface 3012 of the flat plate structure 3010A but are spaced from and near the left lateral edge 3111 of the flat plate structure 3010A. The first and second set of fins 3020A, 3020B are also spaced from one another.
As a result of the above positioning of the fin sets 3020A, 3020B, a first longitudinal strip area 3012A exists between the first set of fins 3020A and the right lateral edge 3110 that is substantially free of fins. A second longitudinal strip area 3012B also exists between the second set of fins 3020B and the left lateral edge 3110 that is substantially free of fins. Finally, a third longitudinal strip area 3012C also exists between the first set of fins 3020A and the second set of fins 3020B that is substantially free of fins.
The first and second set of fins 3020A, 3020B are then welded directly to the flat plate structure 3010A via a fusion welding process that does not use a filler material, such as a laser weld. Most preferably, the floors 3024A, 3024B of the first and second set of fins 3020A, 3020B are contiguously laser welded to the flat plate structure 3010A. The laser welding process is achieved by creating relative motion between the laser torch and the assembly 3900 (i.e., the flat plate structure 3010A and the first and second set of fins 3020A, 3020B). In the illustration the relative movement would be left to right or vice-versa along the floors 3024A, 3024B. In one embodiment, it may be preferred to move the assembly 3900 in an assembly line style arrangement and keep the laser torch stationary so as to avoid undesired directional movements of the laser torch.
In order to keep the floors 3024A, 3024B of the first and second set of fins 3020A, 3020B in contact with the upper surface 3012 of the plate structure 3010A during laser welding, a wheel or other member that compresses the floors 3024A, 3024B against the flat plate structure 3010A may be adjacent to and/or lead the laser torch. Of course, other compression techniques can be used if desired, such as clamping, vacuum force, etc.
Once the first and second set of fins 3020A, 3020B are welded to the flat plate structure 3010A, the first and second strip areas 3012A, 3012B are bent along arrows B to form the lateral flanges 3114, 3115 respectively (shown in
Referring now to
While the bending/formation of the lateral flanges 3114, 3115 may be accomplished before or after the fin sets 3020A, 3020B are welded to the plate structure 3010A, it may be preferred to perform the fin connection first as the fins sets 3020A, 3020B will provided rigidity to the plate structure 3010A during flange formation, thereby eliminating unwanted curvature in certain portions of the plate 3010A. Additionally, bending the lateral flanges 3114, 3115 prior to connecting the fin sets 3020A, 3020B may result in the flat portions to which the fin sets 3020A, 3020B are to be welded to become bent due to residual stresses. This is undesirable because laser welding can be performed with a higher integrity when the surfaces are flat.
Referring now to
Referring now to
As is apparent, the fin tube assembly 3100 (along with any of the other embodiments described above) can be completely manufactured without brazing.
Beginning with
The flat plate structures 10A, 10B are rectangular in shape and can be cut to the desired size from a roll of sheet metal on the site of manufacture if desired or formed in any other suitable manner. Preferably, the flat plate structures 10A, 10B are constructed of carbon steel. However, as discussed above, the invention is not so limited.
Referring now to
Once the first and second set of fins 20A, 20B are created (or otherwise obtained), the first set of fins 20A are positioned atop the top surface 12A of the first flat plate structure 10A extending longitudinally between its end edges. Similarly, the second set of fins 20B are positioned atop the top major surface 12B of the second flat plate structure 10B extending longitudinally between its end edges. Of course, the first and second sets of fins 20A, 20B do not have to extend the entire longitudinal lengths of the plates 10A, 10B.
Specifically, the first set of fins 20A are positioned atop the top major surface 12A of the first flat plate structure 10A spaced from both the right lateral edge 110 and the left lateral edge 111. As a result of this positioning of the fin set 20A, a first longitudinal strip area 12C exists between the first set of fins 20A and the right lateral edge 110 that is substantially free of fins while a second longitudinal strip area 12D also exists between the set of fins 20A and the left lateral edge 110 that is substantially free of fins.
Similarly, the second set of fins 20B are positioned atop the top major surface 12B of the second flat plate structure 10B spaced from both the right lateral edge 119 and the left lateral edge 118. As a result of this positioning of the fin set 20B, a first longitudinal strip area 12E exists between the second set of fins 20B and the right lateral edge 119 that is substantially free of fins while a second longitudinal strip area 12F also exists between the set of fins 20B and the left lateral edge 118 that is substantially free of fins
The first and second set of fins 20A, 20B are then welded directly to the flat plate structure 10A, 10B respectively via a fusion welding process that does not use a filler material, such as a laser weld. Most preferably, the floors 24A, 24B of the first and second set of fins 20A, 20B are contiguously laser welded to the flat plate structures 10A, 10B. The laser welding process is achieved by creating relative motion between the laser torch and the assemblies 900A, 900B. In the illustration the relative movement would be left to right or vice-versa along the floors 24A, 24B. In one embodiment, it may be preferred to move the assemblies 900A, 900B in an assembly line style arrangement and keep the laser torch stationary so as to avoid undesired directional movements of the laser torch.
In order to keep the floors 24A, 24B of the first and second set of fins 20A, 20B in contact with the upper surfaces 12A, 12B of the plate structures 10A, 10B respectively during laser welding, a wheel or other member that compresses the floors 24A, 24B against the flat plate structures 10A, 10B may be adjacent to and/or lead the laser torch. Of course, other compression techniques can be used if desired, such as clamping, vacuum force, etc.
While it is illustrated that the fin sets 20, 20B are welded to separate plate structures 10A, 10B, in some embodiments one or more fin sets may be welded to a single plate structure that is then cut into multiple plate structures.
Once the first set of fins 20A are welded to the flat plate structure 10A the first and second strip areas 12C, 12D are bent along arrows D to form the lateral flanges 114, 115 respectively (shown in
Referring now to
While the bending/formation of the lateral flanges 114-115, 122-123 may be accomplished before or after the fin sets 20A, 20B are welded to the plate structures 10A, 10B, it may be preferred to perform the fin connection first as the fins sets 20A, 20B will provided rigidity to the plate structures 10A, 10B during flange formation, thereby eliminating unwanted curvature in certain portions of the plates 10A, 10B. Additionally, bending the lateral flanges 114-115, 122-123 prior to connecting the fin sets 20A, 20B may result in the flat portions to which the fin sets 20A, 20B are to be welded to become bent due to residual stresses. This is undesirable because laser welding can be performed with a higher integrity when the surfaces are flat.
Referring now to
Referring to
As is apparent, the fin tube assembly 100 (along with any of the other embodiments described above) can be completely manufactured without brazing.
Referring now to
In another embodiment, the invention can be an air-cooled condenser incorporating one or more of the fin tube assemblies described above.
In one specific embodiment, the inventive air cooled condenser utilizes a carbon steel (A1008/1010) fin and tube assembly having a surface conversion process in lieu of a coating for external corrosion protection. In one embodiment, the process is a ferritic nitrocarburization process
In this embodiment, the internal surface of the tube will be exposed to steam under a vacuum in an oxygen deficient environment. As the internal surface of the carbon steel tube corrodes, a layer of magnetite is formed which protects the carbon steel surface from further corrosion. Therefore, no supplemental treatment for the prevention of corrosion is required for the internal surface of the finned tube. However, the external surface of the carbon steel finned tube does require corrosion protection.
As mentioned above, a surface conversion process can be used in lieu of a coating for external corrosion protection. The process is a ferritic nitrocarburization process as outlined below.
First the finned tube is pre-heated to ˜750° F. in an air environment. The finned tube bundle is then immersed in a molten salt bath which is between 900 and 1165° F. The primary constituents of the molten salt are alkali cyanate and alkali carbonate which are actively aerated. The nitrocarburizing process occurs within the molten salt bath. The active constituent of the bath is the alkali cyanate. At elevated temperatures, the alkali cyanate causes a reaction to occur with the carbon steel surface. A nitrocarburized layer is formed which consists of an outer compound layer (iron-nitride) and a diffusion layer beneath. This reaction also causes the formation of alkali carbonate which is regenerated. The duration of this process is 60 to 120 minutes.
The bundle is removed from the molten salt bath and then placed in an oxidation cooling bath having a temperature maintained between 750 and 850 ° F. The oxidation bath causes an iron oxide layer (magnetite) to be formed on the surface. The bundle is then removed from the oxidation bath and cooled down to ambient temperature and cleaned by quenching the bundle in a water bath.
The last stage of the FNC process is to dip the bundle in a sealant bath. This bath contains emulsified oil. The bundle is dipped into the bath long enough to allow the emulsified oil to penetrate the pores of the compound layer. The bundle is then removed from the sealant bath and cleaned.
It should be noted that the FNC process described above can be used in combination with any of the structures discussed above for the core tube and the fins, including without limitation single or multi-layer core tubes and any shape of fins.
While the invention has been described and illustrated in sufficient detail that those skilled in this art can readily make and use it, various alternatives, modifications, and improvements should become readily apparent without departing from the spirit and scope of the invention.
The present application claims the benefit of U.S. Provisional Application 60/991,322, filed Nov. 30, 2007; U.S. Provisional Application 61/028,689, filed Feb. 14, 2008; and U.S. Provisional Application 61/108,511, filed Oct. 25, 2008, the entireties of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60991322 | Nov 2007 | US | |
| 61028689 | Feb 2008 | US | |
| 61108511 | Oct 2008 | US |
