TUBE WITH CONDUCTIVE FINS
A tube includes a center tube comprising a steel material, a fluid flowing through the center tube; and at least one disk disposed around the center tube, the disk including a thermally conductive material and exposed to an external heat source. The disk conducts heat from the external heat source into the center tube. The center tube transfers the heat from the external heat source into the fluid. The thermal conductivity of the at least one disk is higher than the thermal conductivity of the center tube.
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The present subject matter relates generally to boiler and/or steam generator tubes, and more specifically to tubes with thermally conductive fins.
Heat recovery steam generators (HRSG), as well as boilers more generally, include several possible configurations including various arrangements of piping, tubes, orifices, baffles, flow conduits, and other components. Heat recovery steam generators installed at power plants use exhaust gases from gas turbine engines to produce steam at various pressures, temperatures, and flow rates for use in power-producing steam turbine generators, as well as for other processes and/or purposes (for example, at co-gen facilities).
Heat recovery steam generators may include high-pressure, intermediate-pressure, and low-pressure systems (referring to the pressure of the steam) which may include drums. Heat recovery steam generators (HRSG) may include tubes, the exterior portions of which are exposed to hot exhaust gas from the gas turbine, and the interior of which include fluids such as water and/or steam flowing therethrough. The effectiveness with which the tubes transfer heat from the exhaust gas to the fluid (i.e., water, steam, and/or other fluids such as ammonia) directly affects the effectiveness of the HRSG, and in turn the overall efficiency of the power plant and/or other facility in which the HRSG is installed.
HRSG and tube effectiveness depends on a number of factors including the surface area of the tubes, the internal flow area of the tubes, and the heat conductivity of the tube material. In addition, other design constraints factor into the design of HRSG including ensuring a minimal tube strength, accounting for pressure losses of the fluid within the tubes, initial construction costs, ongoing maintenance costs, as well as the general durability of the tubes, and their susceptibility to degradation.
BRIEF DESCRIPTION OF THE EMBODIMENTSAspects of the present embodiments are summarized below. These embodiments are not intended to limit the scope of the present claimed embodiments, but rather, these embodiments are intended only to provide a brief summary of possible forms of the embodiments. Furthermore, the embodiments may encompass a variety of forms that may be similar to or different from the embodiments set forth below, commensurate with the scope of the claims.
In one aspect, a tube includes a center tube comprising a steel material, a fluid flowing through the center tube; and at least one disk disposed around the center tube, the disk including a thermally conductive material and exposed to an external heat source. The disk conducts heat from the external heat source into the center tube. The center tube transfers the heat from the external heat source into the fluid. The thermal conductivity of the at least one disk is higher than the thermal conductivity of the center tube.
In another aspect, a method of forming a finned tube includes: disposing a conductive sheet material adjacent to a steel tube; winding the conductive sheet material around the steel tube; and welding the conductive sheet material to the steel tube using a high frequency welding process. The frequency of the high frequency welding process is between about 450 kHz and 1200 kHz.
In another aspect, an HRSG includes a tube with conductive fins according to the embodiments disclosed herein.
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of the disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of the disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein.
DETAILED DESCRIPTIONIn the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
As used herein, the term “axial” refers to a direction aligned with a central axis or shaft of a generator and/or turbine, and/or aligned with the central axis of an HRSG tube. As used herein, the term “longitudinal” may be used synonymously with the term “axial.”
As used herein, the term “circumferential” refers to a direction or directions around (and tangential to) the outer circumference of the generator, turbine, and/or HRSG tube, or for example the circle defined by the swept area of the rotor of the generator and/or turbine. As used herein, the terms “circumferential” and “tangential” may be synonymous.
As used herein, the term “radial” refers to a direction moving outwardly away from the central axis of the generator, turbine and/or HRSG tube. A “radially inward” direction is aligned toward the central axis moving toward decreasing radii. A “radially outward” direction is aligned away from the central axis moving toward increasing radii.
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In operation, heat from the gas stream from the gas turbine exhaust is transferred through the thermally conductive fin segments 58, into the center tube 52, and eventually into the fluid flowing through the center tube 52. HRSGs employing the finned tube 22 of the present embodiment may utilize finned tubes 22 for the lowest temperature 30-40% of the tubes. Stated otherwise, the 40% of HRSG tubes that are closest to the stack may employ the finned tube 22 configuration of the present embodiments, while tubes closer to the gas turbine exhaust may include a conventional design. In other embodiments, the 30% of HRSG tubes that are closest to the stack may employ the finned tube 22 configuration of the present embodiments. In other embodiments, the 20% of HRSG tubes that are closest to the stack may employ the finned tube 22 configuration of the present embodiments. In other embodiments, the 10% of HRSG tubes that are closest to the stack may employ the finned tube 22 configuration of the present embodiments. By including disks 50 composed of thermally conductive material around the center tube 22, an increase in the effectiveness of heat transfer into thermal energy (for use in a power generation facility or other application) may be realized. The embodiments disclosed herein may include disks 50 that are substantially circular and/or ring-shaped rather than segmented or serrated (i.e., continuous, un-segmented disks). In addition, by using a mix of materials (such as aluminum, beryllium, copper, gold, magnesium, iridium, molybdenum, rhodium, silver, tungsten, and also carbon steel, stainless steel, ferritic stainless, and/or austenitic stainless) with a mix of material properties (including thermal conductivity, temperature resistance, and stress tolerance) HRSG tubes that are both robust and effective at transferring heat may be realized. As such, the disk 50 may be composed of a material with a higher thermal conductivity than that of the center tube 52.
The present embodiments have been described primarily in terms of applications within heat recovery steam generators (HRSG). However, several other applications are possible. Exemplary applications of the present embodiments may include tubes within steam turbine boilers, once-through HRSGs, steam production boilers, conventional boilers, HVAC systems, heat exchangers, radiators, automobiles, condensers, chillers, refrigeration equipment and/or other types of equipment where enhanced heat transfer is desired. The embodiments disclosed herein enable highly thermally conductive materials such as aluminum and/or copper to be welded to high strength and temperature resistance materials such as various types of steels via high frequency spiral fin welding, which in turn enables an increased heat transfer effectiveness and higher overall efficiency in heat recovery steam generator (HRSG) and/or power generator applications.
Although specific features of various embodiments of the present disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the present disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose the embodiments of the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the embodiments described herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Claims
1. A tube comprising:
- a center tube comprising a steel material, a fluid flowing through the center tube; and
- at least one disk disposed around the center tube, the at least one disk comprising a thermally conductive material, the at least one disk exposed to an external heat source,
- wherein the at least one disk conducts heat from the external heat source into the center tube;
- wherein the center tube transfers the heat from the external heat source into the fluid, and
- wherein a thermal conductivity of the at least one disk is higher than a thermal conductivity of the center tube.
2. The tube of claim 1, further comprising at least one fin segment disposed in the at least one disk.
3. The tube of claim 1, wherein the at least one disk is bonded to the center tube via a high-frequency welding process.
4. The tube of claim 1, wherein the at least one disk further comprises a continuous ring-shaped disk.
5. The tube of claim 1, wherein the at least one disk is at least partially composed of at least one of aluminum, beryllium, copper, gold, magnesium, iridium, molybdenum, rhodium, silver, and tungsten.
6. The tube of claim 1, wherein the center tube is at least partially composed of at least one of carbon steel, alloy steel, stainless steel, ferritic stainless, and austenitic stainless.
7. The tube of claim 1, further comprising multiple disks, wherein the tube comprises between about 80 and about 450 disks per meter of tube length.
8. The tube of claim 7, wherein at least one disk of the multiple disks is longitudinally aligned with at least one adjacent disk.
9. The tube of claim 7, wherein the at least one disk wraps around the center tube in a spiral configuration.
10. The tube of claim 1, wherein the at least one disk comprises a thickness between about 0.5 mm and about 1.5 mm.
11. The tube of claim 2, wherein the at least one disk comprises a fin height of between about 4 mm and about 25 mm.
12. The tube of claim 2, wherein the at least one disk comprises between about 12 fin segments and about 100 fin segments.
13. The tube of claim 1, wherein a tube outer diameter is between about 1 inch and about 2.5 inches.
14. A heat recovery steam generator (HRSG) comprising at least one tube according to claim 1.
15. The HRSG of claim 14, wherein at least about 10% of the tubes of the HRSG comprise the tube according to claim 1.
16. The HRSG of claim 15, further comprising:
- at least one fin segment disposed in the at least one disk;
- wherein the at least one disk wraps around the center tube in a spiral configuration,
- wherein the at least one disk is bonded to the center tube via a high-frequency welding process,
- wherein the at least one disk is at least partially composed of at least one of aluminum and copper,
- wherein the center tube is at least partially composed of at least one of carbon steel, alloy steel, stainless steel, ferritic stainless, and austenitic stainless,
- wherein the at least one disk comprises a thickness between about 0.5 mm and about 1.5 mm,
- wherein the at least one disk comprises a fin height between about 4 mm and about 25 mm,
- wherein the at least one disk comprises between about 12 fin segments and about 100 fin segments, and
- wherein a tube outer diameter is between about 1 inch and about 2.5 inches.
17. A method of forming a finned tube comprising:
- disposing a conductive sheet material adjacent to a steel tube;
- winding the conductive sheet material around the steel tube; and
- welding the conductive sheet material to the steel tube using a high frequency welding process;
- wherein the frequency of the high frequency welding process is between about 450 kHz and 1200 kHz.
18. The method of claim 17, further comprising serrating the conductive sheet material prior to disposing the conductive sheet material adjacent to the steel tube.
19. The method of claim 17, wherein the conductive sheet material at least partially comprises at least one of aluminum and copper.
20. The method of claim 18, further comprising:
- coating the steel tube with a rust inhibitor after welding the conductive sheet material to the steel tube using a high frequency welding process; and
- heat treating the steel tube and conductive sheet material.
Type: Application
Filed: Dec 14, 2018
Publication Date: Jun 18, 2020
Applicant: General Electric Company (Schenectady, NY)
Inventors: Scott William Herman (Enfield, CT), Donald William Bairley (Southington, CT), Robert William Moore (Spartanburg, SC)
Application Number: 16/220,736