AU2009205434B2

AU2009205434B2 - Heat exchanger

Info

Publication number: AU2009205434B2
Application number: AU2009205434A
Authority: AU
Inventors: Melvin J. Albrecht; Jason M. Marshall; Dennis R. Shiffer; William J. White
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 2008-01-14
Filing date: 2009-01-14
Publication date: 2013-06-20
Anticipated expiration: 2029-01-14
Also published as: RO128317A2; EP2245406A1; US20090178779A1; ES2376814A1; WO2009091816A1; EP2245406B1; CN101910776A; IL206741A; CA2712027A1; MX2010007654A; NZ586755A; EP2245406A4; MX336768B; ES2376814B2; MA32011B1; CN101910776B; PT2009091816Y; AU2009205434A1; BRPI0907256A2; ZA201004604B

Abstract

A heat exchanger having an arrangement of heat transfer surfaces and a pair of vertical steam/water separators structurally interconnected to one another to provide an integral support structure for the heat exchanger. The structural interconnection includes upper and lower structural members extending between the pair of vertical steam/water separators. The upper and lower structural members include headers, and an arrangement of heating surface which extends between and is fluidically connected to the headers. A structural support framework surrounds the heat exchanger for bottom support thereof, the framework providing structural support and rigidity for the heat exchanger and a means by which the heat exchanger can be picked up and lifted for placement at a desired location.

Description

WO 2009/091816 PCT/US2009/030978 HEAT EXCHANGER FIELD AND BACKGROUND OF THE INVENTION [0001] The present invention relates, in general, to the field of heat exchangers and, more particularly, to a heat exchanger having an integral support structure and a structural framework for the support thereof. [0002] The present invention employs the teachings of U.S. Patent No. 6,336,429 to Wiener et al., the text of which is hereby incorporated by reference as though fully set forth herein. [0003] To the extent that explanations of certain terminology or principles of the heat exchanger, boiler and/or steam generator arts may be necessary to understand the present invention, the reader is referred to Steam/ its generation and use, 40th Edition, Stultz and Kitto, Eds., Copyright @1992, The Babcock & Wilcox Company, and to Steam/ its generation and use, 41st Edition, Kitto and Stultz, Eds., Copyright @2005, The Babcock & Wilcox Company, the texts of which are hereby incorporated by reference as though fully set forth herein. SUMMARY OF THE INVENTION [0004] One aspect of the present invention is drawn to a heat exchanger for transferring heat energy into a working fluid, such as water. The heat exchanger is used to transform at least a portion of the water from the liquid phase into saturated or superheated steam. [0005] Vertical steam/water separating devices, disclosed in the aforementioned U.S. Patent No. 6,336,429 to Wiener et al., are used to separate the steam from the WO 2009/091816 PCT/US2009/030978 -2 steam-water mixture. A pair of such vertical steam/water separators, structurally interconnected and arranged as described herein, provides an integral support structure for the heat exchanger. [0006] The heat exchanger of the present invention is advantageously comprised of an arrangement of heat transfer surfaces and fluid conveying conduits arranged in a particular fashion to transfer a desired amount of heat energy into the water. The heat transfer surfaces are advantageously made of tubes arranged into panels, and are provided with inlet and outlet headers as required. As is known to those skilled in the art, heat transfer surfaces which convey steam-water mixtures are commonly referred to as evaporative or boiler surfaces; heat transfer surfaces which convey steam therethrough are commonly referred to as superheating (or reheating, depending upon the associated steam turbine configuration) surfaces. Regardless of the type of heating surface, the sizes of tubes, their material, diameter, wall thickness, number and arrangement are based upon temperature and pressure for service, according to applicable boiler design codes, such as the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section I, or equivalent other codes as required by law. Required heat transfer characteristics, pressure drop, circulation ratios, spot absorption rates, mass flow rates of the working fluid within the tubes, etc. are also important parameters which must be considered. Depending upon the geographic location where the heat exchanger is to be installed, applicable seismic loads and design codes are also considered. [0007] The heat exchanger is bottom supported from a base which is part of an arrangement of interconnected rigid members that surrounds the heat exchanger and forms a structural support framework which, together with the aforementioned integral support structure not only provides structural support and rigidity for the heat exchanger, but also a means by which the heat exchanger can be picked up and lifted for placement at a desired location. In the case of an application of the heat exchanger as a solar heat energy receiver, the structural support framework permits the entire assembly of the heat exchanger and the framework to be assembled on the ground and then lifted and set upon a tower during installation. The structural support framework remains with the heat exchanger, thereby facilitating (if -3 necessary) the removal of the heat exchanger from the tower should it become desirable to do so. [0008] In accordance with the present invention, there is provided a heat exchanger comprising an arrangement of heat transfer surfaces and a pair of vertical steam/water separators structurally interconnected to one another by upper and lower structural members extending therebetween, the pair of steam/water separators and structural members providing an integral support structure for at least a portion of the heat transfer surface of the heat exchanger, and wherein said portion of the heat transfer surface extends between and is fluidically connected to central portions of the upper and lower structural members. The structural interconnection includes upper and lower structural members formed of heavy wall pipe and extending between the vertical steam/water separators. Each of the heavy wall pipes includes a pair of spaced inner partition walls disposed in crosswise fashion to form a central portion therein defining a header. The integrally supported portion of the heat transfer surfaces extends between and is fluidically connected to the headers of the upper and lower structural members. [0009] Each of the vertical steam/water separators includes four coplanar pedestal feet positioned at the lower end of the steam/water separator, and arranged at equally spaced intervals about the outer periphery of the steam/water separator. [0010] The heat exchanger includes a structural support framework in the shape of a rectangular parallelepiped having a top, a bottom and opposing lengthwise sides surrounding the heat exchanger for bottom support thereof. [0011] The bottom of the structural support framework is comprised of four horizontally extending parallel spaced lateral and longitudinal beams intersecting one another to form a grid-like structure which includes a lattice of obliquely-disposed web members positioned between intersecting longitudinal and lateral beams. [0012] Two pairs of lateral braces intersect the inner two of the four longitudinal beams of the bottom of the structural support framework to form support bases for the vertical steam/water separators. The pedestal feet of the steam/water separator are fixedly secured to the respective support base. 4301048_1 (GHMatters) P84518 AU 30/04113 -4 [0013] Each of the opposing lengthwise sides of the structural support framework has two pairs of parallel spaced vertical beams located at opposite ends of the structural framework and one pair of parallel spaced longitudinal beams intersecting the vertical beams and located at the upper end of each of the opposing sides. A lattice of obliquely disposed web members is positioned between each pair of vertical beams and the pair of longitudinal beams. [0014] The top of the structural support framework is comprised of two lateral beams intersecting the upper one of the pair of parallel spaced beams extending along each lengthwise side. The two lateral beams are located above the heat exchanger and provide a means by which the heat exchanger and the structural support framework can be lifted for placement at a desired location. [0015] Another aspect of the present invention is drawn to the combination of a heat exchanger and the structural framework used for the support thereof. The combination comprises an arrangement of heat transfer surfaces and a pair of vertical steam/water separators structurally interconnected to one another by upper and lower structural members extending therebetween, the structural members and the pair of separators providing an integral support structure for at least a portion of the heat transfer surface and wherein said portion of the heat transfer surface extends between and is fluidically connected to central portions of the upper and lower structural members, the structural framework having a top, a bottom and opposing lengthwise sides surrounding the heat exchanger for bottom support thereof. The structural interconnection between the heat exchanger surfaces and the pair of vertical steam/water separators is comprised of upper and lower heavy wall pipes, each pipe having partitions therein defining a central header. The integrally supported portion of the heat transfer surfaces extends between and is fluidically connected to the headers of the upper and lower heavy wall pipes. Each of the steam/water separators includes a plurality of pedestal feet positioned at the lower end of the steam/water separator. [0016] The structural framework part of the combination has a top, a bottom, and opposing lengthwise sides surrounding the heat exchanger for bottom support thereof. The bottom of the structural framework is comprised of four horizontally extending parallel spaced lateral and longitudinal beams intersecting one another to form a grid-like structure and includes a lattice of obliquely-disposed web members positioned between intersecting 4301048_1 (GHMatters) P84518.AU 30/04113 -4a longitudinal and lateral beams. Two pairs of parallel spaced lateral braces intersect the inner two of the four longitudinal beams at the 4301048_ 1 (GHMatters) P84518.AU 30/04/13 WO 2009/091816 PCT/US2009/030978 -5 bottom of the structural framework to form support bases for the vertical steam/water separators whose pedestal feet are fixedly secured to their respective support bases. Each of the opposing lengthwise sides of the structural framework has two pairs of parallel spaced vertical beams located at opposite ends of the structural framework and one pair of parallel spaced longitudinal beams intersecting the vertical beams and located at the upper end of each of the opposing sides. A lattice of obliquely disposed web members positioned between each pair of vertical beams and the pair of longitudinal beams. The top of the structural framework is comprised of two lateral beams intersecting the upper one of said pair of parallel beams. The two lateral beams are located above the heat exchanger and provide a means by which the heat exchanger and the structural framework can be lifted for placement at a desired location. [0017] These and other features of the present invention will be better understood and its advantages will be more readily appreciated from the following description, especially when read with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 is a perspective view of the heat exchanger which is shown, for clarity, without the structural support framework of the present invention; [0019] FIG. 2 is an exploded perspective view of the heat exchanger illustrated in FIG. 1; [0020] FIG. 3 is a perspective view of the pair of vertical steam/water separators structurally interconnected to one another to provide an integral support structure in accordance with the present invention; and [0021] FIG. 4 is a perspective view of the integrally supported heat exchanger structure of FIG. 3, together with the structural framework used to support the heat exchanger structure in accordance with the present invention.

WO 2009/091816 PCT/US2009/030978 -6 DETAILED DESCRIPTION OF THE INVENTION [0022] Reference will hereinafter be made to the accompanying drawings wherein like numerals designate the same or functionally similar elements throughout the various drawings. [0023] Referring to FIGS. 1-3, there is shown a heat exchanger 10 according to the present invention. The heat exchanger 10 has left and right side walls 12, a roof portion 14, and a pair of vertical steam/water separators 16 of the type disclosed in the aforementioned U.S. Patent No. 6,336,429 to Wiener et al. The vertical steam/water separators 16 of this type are particularly suited to handle large transient swings in heat input to the heat exchanger 10 which may, in turn, cause large variations in water levels within the steam/water separators 16. The side walls 12 are comprised of panels of tubes having a welded membrane between adjacent tubes. Welded membrane tube wall panels are well known to those skilled in the art and will thus not be described in detail here; for additional details, the reader is referred to the aforementioned Steam texts. The roof portion 14 is also comprised of welded membrane tube wall panels. While membrane wall tube panels are typically employed in conventional industrial and utility furnace walls to achieve a gas-tight construction, the provision of the membrane between adjacent tubes in this application also provides for structural rigidity of the panels and it is for that purpose that the side wall panels 12 and roof portion 14 have a membrane wall construction. [0024] If the heat exchanger 10 is used to provide merely saturated steam, the side walls 12 and roof portion 14 comprise evaporative or boiler heating surface. If the heat exchanger 10 is used to provide superheated steam, and as will be appreciated by those skilled in the art, some of the heating surface will have to be evaporative surface and other portions will have to be superheater surface. In the embodiment shown in FIG. 1, the side walls 12 are evaporative or boiler surface, and may be provided with inlet headers 18 and outlet headers 20. The steam-water mixture generated in tubes forming the side walls 12 is collected in the outlet headers 20 which also serve as a mix point to even out temperature imbalances which may exist in the steam-water mixture. Stubs 22 on the outlet headers 20 are WO 2009/091816 PCT/US2009/030978 -7 interconnected via risers (not shown) to stubs 26 on upper portions of each of the vertical steam/water separators 16. The vertical steam/water separators 16 operate in known fashion (see U.S. Patent No. 6,336,429 to Wiener et al.), separating the steam from the steam-water mixture. If the heat exchanger 10 is designed for saturated steam production, steam outlet connections (not shown) from the top portions of each of the separators 16 convey the steam to its downstream location and use. If the heat exchanger 10 is designed to produce superheated steam, the steam is conveyed from the separators 16 to superheater surfaces for further heating and eventual collection and conveyance to its downstream location and use. Depending upon the initial steam temperature and pressure, and the desired outlet superheated steam temperature desired, the superheater may have to be designed as a multiple-pass superheater in order to provide adequate mass flux rates within the superheater surface tubes, and such concepts are within the scope of the present invention. Two-pass, four-pass or additional pass designs may be required, taking into account the temperatures of not only the tubes in the superheater, but also the temperature of the tubes in an adjacent structure, in order to address differential thermal expansion concerns. In either case, the water separated from the steam-water mixture is conveyed to a lower portion of each of the separators 16, mixed with make-up feedwater, and conveyed to the evaporative surface to start the process over again. In order to facilitate the circulation of the water and water-steam mixture throughout the heat exchanger 10, circulation pumps 28 may advantageously be provided at the lower portion of each of the separators 16 for pumping the water back to the evaporative surface via supplies (not shown). [0025] Referring to FIG. 2, there is shown an exploded perspective view of the heat exchanger illustrated in FIG. 1. This view better illustrates the relationship between the side walls 12 and the integral support structure, generally designated 30, comprised of the pair of vertical steam/water separators 16 structurally interconnected to one another by means of upper and lower structural members 32. [0026] Referring to FIG. 3, there is shown a perspective view of the pair of vertical steam/water separators 16 structurally interconnected to one another according to the present invention which provides the integral support structure 30 for the heat WO 2009/091816 PCT/US2009/030978 exchanger 10. The upper and lower structural members 32 are advantageously comprised of heavy wall pipe, rather than a structural I-beam or WF section, for reasons that will become apparent. One end of each member 32 is connected to one of the vertical steam/water separators, such as by welding. The structural members 32 do not, in and of themselves, provide any direct fluidic interconnection between the separators 16. The heavy wall pipe that makes up each of the structural members 32 is fitted with inner partition walls 34 forming a central portion that comprises a header 36 which performs a fluid collecting/conveying function. In addition to providing an integral support structure for the heat exchanger 10, the headers 36 which are part of the upper and lower structural members 32, are interconnected to one another by an arrangement of heating surface 38 which extends between and is fluidically connected to the upper and lower headers 36. Typically, the heating surface 38 is up-flowing evaporative surface, comprised of tubes. Tube stubs 40 provide connections for risers (not shown) which convey the steam-water mixture to the tube stubs 26 on the separators 16 as hereinbefore described. [0027] It will be noted that the heating surface 38 extends in between the headers 36 of the upper and lower structural members 32 while providing a gap or space 42 between distal edges of the heating surface 38 and the outer wall of the steam/water separators 16. The side walls 12 extend into this space 42, with the distal edges of the heating surface 38 extending adjacent to and in close proximity with the inside portions of the side walls 12. However, in order to accommodate differential thermal expansion the heating surface 38 is not connected to the side walls 12 in any rigid fashion. The side walls 12 would be bottom supported from a base, in a fashion similar to that described below with respect to the integral support structure 30. The sidewalls 12 may also be provided with buckstays, not shown, which are well known to those skilled in the art as providing rigidity and support for membrane tube wall construction. [0028] Referring to FIG. 4, there is shown a perspective view of a portion of the heat exchanger 10 according to the present invention, similar to that illustrated in FIG. 1, together with a structural framework 50 which supports the heat exchanger WO 2009/091816 PCT/US2009/030978 10. For clarity, there is shown only the integral support structure 30 comprised of the pair of vertical steam/water separators 16 structurally interconnected to one another by means of upper and lower structural members 32. [0029] The three dimensional structural framework 50 is generally in a shape of a rectangular parallelepiped and is defined by the top 51, the bottom 52, and the lengthwise sides 55, and includes three sets of flanged beams extending in the three mutually orthogonal directions, eight longitudinal beams 58, six lateral beams 56, and eight vertical beams 54. [0030] The bottom 52 of the structural framework 50 is comprised of four parallel spaced longitudinal beams 58 and four parallel spaced lateral beams 56 which connectedly intersect one another to form a grid-like structure. A lattice of obliquely disposed web members 60 is positioned between the intersecting longitudinal and lateral beams 58 and 56 to structurally reinforce the grid-like structure forming the bottom 52 and to stiffen or add rigidity to the structural framework 50. [0031] The bottom 52 of the structural framework 50 includes a pair of support bases 53, each being formed by respective pairs of parallel spaced lateral braces 57 connectedly intersecting the inner pair of longitudinal beams 58. Each of the steam/water separators 16 includes four pedestal feet 59 located at or near the bottom of the steam/water separator. The pedestal feet 59 extend outwardly from the steam/water separator wall at a substantially right angle, and are coplanar and arranged at equally spaced intervals about the outer periphery of the steam/water separator 16. The pedestal feet 59 are each provided with a reinforcing gusset 61 and are fixedly secured to the support base 53. [0032] Each of the lengthwise sides 55 of the structural framework 50 is comprised of two pairs of parallel spaced vertical beams 54 located at opposite ends of the structural framework 50, and one pair of parallel spaced longitudinal beams 58 located at the upper end of the sides 55 and connectedly intersecting the vertical beams 54. A lattice of obliquely-disposed web members 60 is positioned between -10 each pair of vertical beams 54 and the longitudinal beams 58 to structurally reinforce the sides 55 and to stiffen the structural framework 50. [0033] The top 51 of the structural framework 50 is comprised of two lateral beams 56 which intersect and are connected to the upper one of each of the pairs of longitudinal beams 58 located at the upper end of the lengthwise sides 55. In addition to reinforcing the top 51 and stiffening the structural framework 50, the top lateral beams 56 are generally located over the heat exchanger 10 and provide a means by which the heat exchanger 10 and the supporting structural framework 50 can be picked up and lifted for placement at a desired location. [0034] Although the present invention has been described above with reference to particular means, materials, and embodiments, it is to be understood that this invention may be varied in many ways without departing from the spirit and scope thereof, and therefore is not limited to these disclosed particulars but extends instead to all equivalents within the scope of the following claims. [0035] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. [0036] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

Claims

1. A heat exchanger comprising an arrangement of heat transfer surfaces and a pair of vertical steam/water separators structurally interconnected to one another by upper and lower structural members extending therebetween, the pair of steam/water separators and structural members providing an integral support structure for at least a portion of the heat transfer surfaces of the heat exchanger, and wherein the heat transfer surface extends between and is fluidically connected to central portions of the upper and lower structural members.

2. The heat exchanger of claim 1, wherein said central portions of the upper and lower structural members lack a direct fluidic interconnection to the pair of vertical steam/water separators.

3. The heat exchanger of claim 1, wherein the upper and lower structural members are formed of pipe.

4. The heat exchanger of claim 3, including a pair of spaced partition walls disposed in crosswise fashion within the pipe to form the central portions therein.

5. The heat exchanger of claim 4, wherein the central portion is a header.

6. The heat exchanger of claim 5, wherein said portion of the heat transfer surface extends between and is fluidically connected to the headers of the upper and lower structural members.

7. The heat exchanger of claim 1, including a support structural framework having a top, a bottom and opposing lengthwise sides surrounding the heat exchanger for bottom support thereof.

8. The heat exchanger of claim 7, wherein the structural framework is in a shape of a rectangular parallelepiped. -12

9. The heat exchanger of claim 7, wherein the bottom of the structural framework is comprised of horizontally extending lateral and longitudinal beams.

10. The heat exchanger of claim 9, wherein the lateral and longitudinal beams intersect one another to form a grid-like structure.

11. The heat exchanger of claim 10, including a lattice of obliquely-disposed web members positioned between intersecting longitudinal and lateral beams.

12. The heat exchanger of claim 9, wherein the bottom of the structural framework includes four parallel spaced longitudinal beams

13. The heat exchanger of claim 12, including two pairs of parallel spaced lateral braces intersecting the inner two of said four longitudinal beams to form support bases for the steam/water separators.

14. The heat exchanger of claim 13, wherein each of the vertical steam/water separators includes a plurality of pedestal feet positioned at the lower end of the separator and fixedly secured to a respective one of the support bases.

15. The heat exchanger of claim 7, wherein each of the opposing lengthwise sides of the structural framework has two pairs of parallel spaced vertical beams located at opposite ends of the structural framework and one pair of parallel spaced longitudinal beams intersecting the vertical beams, an upper one of the pair of parallel spaced longitudinal beams located at the upper end of each of the opposing sides.

16. The heat exchanger of claim 15, including a lattice of obliquely-disposed web members positioned between each pair of vertical beams and the pair of longitudinal beams.

17. The heat exchanger of claim 15, wherein the top of the structural framework is comprised of two lateral beams intersecting the upper one of said pair of parallel spaced longitudinal beams and an inner one of each of said pairs of parallel spaced vertical beams. -13

18. The heat exchanger of claim 17, wherein the two lateral beams are located above the heat exchanger and provide the means by which the heat exchanger and the structural framework can be lifted for placement at a desired location.

19. In combination, a heat exchanger and the structural framework for the support thereof, the combination comprising an arrangement of heat transfer surfaces and a pair of vertical steam/water separators structurally interconnected to one another by upper and lower structural members extending therebetween, the structural members and the pair of separators providing an integral support structure for at least a portion of the heat transfer surface and wherein said portion of the heat transfer surface extends between and is fluidially connected to central portions of the upper and lower structural members, the structural framework having a top, a bottom, and opposing lengthwise sides surrounding the heat exchanger for bottom support thereof.

20. The combination of claim 19, wherein the upper and lower structural members providing structural interconnection between the pair of vertical steam/water separators are comprised of upper and lower pipes, each pipe having partitions therein defining a respective central header portion.

21. The combination of claim 20, wherein said portion of the heat transfer surface extends between and is fluidically connected to the headers in the upper and lower pipes.

22. The combination of claim 19, wherein the bottom of the structural framework is comprised of horizontally extending lateral and longitudinal beams intersecting one another to form a grid-like structure.

23. The combination of claim 22, including a lattice of obliquely-disposed web members positioned between intersecting longitudinal and lateral beams.

24. The combination of claim 22, wherein the bottom of the structural framework includes four parallel spaced longitudinal beams.

25. The combination of claim 24, including two pairs of parallel spaced braces intersecting the inner two of said four longitudinal beams to form support bases for the steam/water separators. -14

26. The combination of claim 25, wherein each of the vertical steam/water separators includes a plurality of pedestal feet positioned at the lower end of the separator and fixedly secured to the respective one of the support bases.

27. The combination of claim 19, wherein each of the opposing lengthwise sides of the structural framework has two pairs of parallel spaced vertical beams located at opposite ends of the structural framework and one pair of parallel spaced longitudinal beams intersecting the vertical beams an upper one of the pair of parallel spaced longitudinal beams located at the upper end of each of the opposing sides.

28. The combination of claim 27, including a lattice of obliquely-disposed web members positioned between each pair of vertical beams and the pair of longitudinal beams.

29. The combination of claim 27, wherein the top of the structural framework is comprised of two lateral beams intersecting the upper one of said pair of parallel spaced longitudinal beams and intersecting an inner one of each of said pairs of parallel spaced vertical beams.

30. The combination of claim 29, wherein the two lateral beams are located above the heat exchanger and provide the means by which the heat exchanger and the structural framework can be lifted for placement at a desired location.

31. The combination of claim 19, wherein said central portions of the upper and lower structural members lack a direct fluidic interconnection to the pair of vertical steam/water separators.