JP5512235B2 - Tube support system for nuclear steam generators. - Google Patents

Description

  The present invention relates generally to reactor steam generators, and more particularly to a new and useful tube support system for use with reactor steam generators that uses tube support plates to maintain tube row spacing within the steam generator and The present invention relates to a tube support method.

  A pressurized steam generator or heat exchanger associated with the nuclear power plant transfers heat from the primary coolant generated in the reactor to the secondary coolant, and the transferred heat drives the turbine of the power plant. These steam generators are approximately 22.5 m (75 ft) in length and approximately 3.6 m (12 ft) in outer diameter, and a straight pipe for circulating coolant therein has an outer diameter of approximately 1.6 cm (5 cm). / 8 inch). However, this straight pipe has an effective length of about 15.6 m (52 feet) between its respective attachment end and the opposing tubesheet face. A tube bundle of one heat exchanger typically includes 15000 or more tubes. It is clear that these tube support structures, such as tube support plates, need to be provided between each tube plate to ensure tube separation, proper rigidity, and the like.

  U.S. Pat. No. 4,503,903 describes an apparatus and method for radially supporting a tube support plate in a heat exchanger such as a U-tube steam generator having inner and outer shells. The device is rigidly attached to the inner shell, and the tube support plate is centrally located within the inner shell.

  U.S. Pat. No. 5,497,827 describes an apparatus and method for holding a tube support radially in a U-tube steam generator. The inner tube bundle enclosure or inner shell is radially spaced from the outer pressure enclosure by the abutment. Each abutment is welded and fixed to the inner tube bundle enclosure and is in contact with the inner face of the pressure enclosure. Each abutment maintains the steam generator coaxial enclosure and tube bundle assembly in a radial direction by means of a spacer plate, which may be caused by, for example, external stresses associated with earthquakes. It is intended to avoid relative deviations and impacts that occur between them. In one variation of the device, a helical spring is used to obtain an elastic pressure that contacts the spacer plate, and this spring is positioned inside the pressure enclosure.

  U.S. Pat. No. 4,204,305 describes a nuclear steam generator, generally referred to as Once Through Steam Generator (OTSG), which is hereby incorporated by reference. The OTSG houses a bundle of tubes including straight tubes, and each tube is supported laterally by a tube support plate (TSP) at several locations along its length. Each tube is inserted through a hole in the TSP having three flow paths and three tube contact surfaces that support each tube in the lateral direction. After heat exchanger assembly, each tube is in contact with one or two of the lands projecting inside the TSP, thus providing only lateral support to maintain the tube bundle against lateral forces such as loads associated with earthquakes. Rather, support for mitigating tube vibration during normal operation is provided.

US Pat. No. 6,914,955 B2 describes a tube support plate suitable for use with the OTSG.
For a general description of reactor steam generator characteristics, see The Babcock & Wilcox, Steam / Its Generation and Use 41st Edition, Chapter 48, 2005, Barberton, Ohio, USA.

US Pat. No. 4,503,903 US Pat. No. 5,497,827 US Pat. No. 4,204,305 US Pat. No. 6,914,955B2

The Babcock & Wilcox, Steam / Its Generation and Use, 41st edition, Chapter 48, Barberton, Ohio, USA, 2005

  It is an object to provide an improved method and apparatus for supporting a tube in a steam generator.

  According to the present invention, a tube bundle support system and a tube bundle support method are provided that can advantageously incorporate tube support plates into an aligned configuration that is compatible with normal fabrication processes. As the steam generator becomes hot, one or more tube support plates are misaligned under control. The tube support plate is made of a material that has a coefficient of thermal expansion that is less than that of the shroud surrounding the tube. As a result, as the steam generator is heated, there is a radial gap adjacent to the tube support plates, thus the associated tube support plate biasing system provides space for each tube support plate to shift or deflect laterally. Is provided.

The tube support plate biasing system has only one part located in the steam generator shell, thus minimizing the risk of component loss.
The apparatus and method of the present invention can be easily integrated into existing steam generators with little internal modification and, conversely, can be easily removed to return the steam generator to its original condition.
The normal load path for transferring the load caused by the earthquake between each pipe and the support, the shroud and the shell can be used as it is.

  Thus, according to one aspect of the present invention, there are a plurality of parallel spaced tubes for flowing fluid, each tube having a tube that conducts heat to the fluid flowing along these tubes, and traversing the tubes. A method and apparatus for assembling and operating a steam generator also having a plurality of laterally arranged tube support plates are provided. The steam generator assembly and operation method includes 1) aligning the tube support plate, 2) passing the tube through the aligned tube support plate, and 3) at least one tube while heating the steam generator. Biasing the support plate laterally across each tube, thus increasing the effectiveness of the tube support.

The method can include biasing adjacent tube support plates in the same lateral direction across the tube.
The method may include biasing every other tube support plate in the same lateral direction across the tube.
The method may include alternately biasing the tube support plates in a first lateral direction across each tube and biasing the remaining tube support plates in a lateral direction transverse to the first lateral direction.
The method includes biasing a first plurality of tube support plates in a first lateral direction across the tube and a remaining plurality of tube support plates across the first lateral direction and in the opposite lateral direction. Biasing can be included.
The method can include biasing one or more tube support plates in the same or variable amounts and directions to provide one or more biases for any given tube support plate.

  According to yet another aspect of the present invention, a heat exchanger having a plurality of parallel spaced tubes for flowing fluid, each tube indirectly transferring heat to the fluid flowing along these tubes. A tube support plate biasing system for use, wherein the heat exchanger includes a tube support plate disposed laterally across each tube, and a cylindrical shroud disposed within and surrounding each cylindrical pressure shell And a tube support plate biasing system. The tube support plate biasing system includes a tube support plate that is disposed laterally across the tube and made from a material that has a coefficient of thermal expansion smaller than that of the shroud, the tube support plate comprising: It further includes biasing means for laterally biasing across the tube. The biasing means has a restraining mechanism connected to the pressure shell at one end and a link bar connected to the tube support plate at the other end. The link bar can be incorporated loosely or slightly taut. As the radial gap between the tube support plate and the shroud surrounding each tube opens during heating, the link bar tension or increased tension pulls the tube support plate, thus biasing the tube support plate.

According to yet another aspect of the invention, there are a plurality of parallel spaced tubes for flowing fluid, each tube having a tube that indirectly transfers heat to the fluid flowing along these tubes, A tube for use in a steam generator having a plurality of transversely disposed tube support plates and a cylindrical shroud, the shroud being disposed within a cylindrical pressure shell and surrounding each tube A support plate biasing system is provided. The tube support plate biasing system may include a thread engagement mechanism or other adjustment mechanism within its link system that changes the length or amount of tension of the link mechanism during or after installation of the link system. Let
The tube support plate biasing system causes the one or more tube support plates to be unaligned under control in the same or variable amounts and orientations and with one or more devices on any individual tube support plate. Can be used for.

  An improved method and apparatus for supporting a tube in a steam generator is provided.

FIG. 1 is a cross-sectional view of a once-through steam generator that can implement the principles of the present invention. FIG. 2 is a side view of an embodiment of the link mechanism of the pipe support plate biasing system of the present invention. FIG. 3 is a partial cross-sectional view of the link mechanism shown in FIG. FIG. 4 is a side cross-sectional view illustrating a tube support plate configuration incorporating a plurality of tube support plate biasing systems according to the present invention.

Referring to FIG. 1, a conventional once-through steam generator 10 is shown and includes a vertical elongated cylindrical pressure vessel or shell 11 having ends closed by an upper head 12 and a lower head 13, respectively.
The upper head includes an upper tube sheet 14, a primary coolant inlet 15, a human passage 16, and a hand hole 17. The human road 16 and the hand hole 17 are used for inspection and repair when the steam generator 10 is stopped. The lower head 13 includes a drain 18, a coolant outlet 20, a hand hole 21, a human passage 22, and a lower tube sheet 23.
The steam generator 10 is supported on a frustoconical or cylindrical skirt 24 engaged with the outer surface of the lower head 13 for supporting the steam generator 10 above the structural floor 25.
The total length of the typical steam generator under consideration between the structural floor 25 and the upper end of the primary coolant inlet 15 is about 22.5 m (75 feet), and the overall diameter of the steam generator 10 is Is over 12 feet.

  The lower cylindrical shroud 26 or wrapper or baffle surrounding the shell 11, heat exchanger tube bundle 27 is illustrated in part in FIG. The number of tubes enclosed in the shroud 26 of the steam generator under consideration exceeds 15000, and the outer diameter of each tube is about 1.6 cm (5/8 inch). In the steam generator of the type described here, it has been found that 690 alloy is the preferred material for the tube. Each tube 27 in each tube bundle is locked to each hole formed in each of the upper and lower tube plates 14 and 23 by expanding it in a bell shape or welding the tube end portion inside the tube plate.

The lower shroud 26 is aligned inside the shell 11 by shroud alignment pins. The shroud 26 can be secured by bolting to the lower tube sheet 23 or by welding to a lug protruding from the lower end of the shell 11. The lower edge of the shroud 26 has a group of rectangular water ports 30 or a single opening (not shown) that opens in a circumferential direction that receives the feed water flow from the inlet toward the riser chamber 19. The upper end of the shroud 26 is a gap or vapor discharge hole between the riser chamber 19 in the shroud 26 and the annular downcomer annular space 31 formed between the outer surface of the shroud 26 and the inner surface of the cylindrical shell 11. Establish fluid communication via 32.
The support rod system 28 is fixed at the position of the uppermost support plate 45B, and this support rod system 28 is located between the lower tube plate 23 and the lowermost support plate 45A and then to the uppermost support plate 45B. It includes a threaded segment that spans between all support plates 45.

  A hollow, toroid-shaped secondary coolant feed inlet header (hereinafter header) 34 surrounds the outer surface of the shell 11. The header 34 is in fluid communication with the annular downcomer annular space 31 via an array of feed water inlet nozzles 35 (hereinafter referred to as an array) arranged in the radial direction. As indicated by the arrows in FIG. 1, the feed water stream flows from the header 34 through nozzles 35 and 36 into the steam generator 10. The water supplied from the nozzle flows downward, enters the riser chamber 19 through the water port 30 from the end of the annular downcomer annular space 31. The secondary coolant flow rises through the shroud 26 in the riser chamber in a direction that counter-flows with the primary coolant flowing down through each tube 27. An annular plate 37 welded between the inner surface of the shell 11 and the outer surface of the bottom edge of the upper cylindrical shroud, and a baffle or wrapper 33, the water supply entering the downcomer annular space 31 is indicated by arrows. Ensure that it flows down towards the water port 30 in the direction. The secondary coolant absorbs heat from the primary coolant that passes through each tube 27 in the tube bundle and thus rises into the riser chamber 19 defined by the shroud 26 and the baffle 33 into steam.

  The baffle 33 is aligned with the shell 11 by an alignment pin (not shown in FIG. 1), and is fixed to an appropriate position by being welded to the shell 11 at a position directly below the steam outlet nozzle 40 through the annular plate 37. The baffle 33 surrounds about one third of each tube 27 constituting the tube bundle.

  An auxiliary water supply header 41 is in fluid communication with the upper portion of the tube bundle through one or more nozzles 42 that penetrate the shell 11 and the baffle 33. The auxiliary water supply header is used, for example, to fill the steam generator 10 when the water supply flow from the header 34 stops. As described above, the water supply or secondary coolant rises in the direction of the arrow along the pipe 27 and becomes steam. In the illustrated embodiment, this steam is superheated before reaching the upper edge of the baffle 33 and flows in the direction of the arrow beyond the top of the baffle 33, between the outer surface of the baffle 33 and the inner surface of the shell 11. The formed annular outlet passage 43 flows down. Steam in the outlet passage 43 exits the steam generator 10 through a steam outlet nozzle 40 in communication with the outlet passage 43. Thus, the temperature of the secondary coolant rises from the feed water inlet temperature to the superheated steam temperature at the steam outlet nozzle 40 position. An annular plate 37 prevents mixing of steam and feed water flowing from the downcomer annular space 31. The primary coolant flows from the reactor (not shown) into the primary coolant inlet 15 in the upper head 12, passes through each tube 27 in the heat exchanger tube bundle and enters the lower head 13, where the secondary coolant The heat is transferred to and discharged from the outlet 20, thus completing the loopback to the reactor, which ultimately generates heat that draws useful work.

  In order to facilitate manufacturing and in particular to facilitate the insertion of the tubes 27 during the manufacturing process, the tube support plates 45 are generally aligned with each other and with the upper and lower tube plates. The tube support plate 45 is aligned with the tube support plate alignment block 104 shown in FIGS. 3-4 disposed along the peripheral portion of the tube support plate between the tube support plate and the inner surface of the shroud 26 or baffle 33. Maintained by The tube support plate alignment block 104 is attached to the shroud 26 or baffle 33 or the tube support plate 45, but not both of them, and the tube between the tube support plate 45 and the shroud 26 or baffle 33. Fill most or all of the gaps that may occur at specific locations along the periphery of the support plate. The shroud, which is typically a continuous large cylinder, is supported laterally within the OTSG shell 11 by shroud alignment pins 106 shown in FIGS. This support arrangement provides a lateral load path from the tube 27 through the tube support plate 45 to the shroud 26 or baffle 33 supported by the shell 11.

  Referring to FIGS. 2-4, the tube support plate 45 is accurately aligned under the condition of minimizing the gap between components during manufacturing, resulting in a controlled misalignment in accordance with the steam generator temperature rise. A tube bundle support system 100 and method is provided. The tube support plate 45 is advantageously incorporated in an alignment configuration that is compatible with normal manufacturing processes. Deviations that cause misalignment occur only when the heat exchanger is heated. By biasing the tube support plate 45 out of alignment under high temperature conditions, tube vibrations due to cross-flow or axial flow excitation mechanisms can be beneficially mitigated.

  The misalignment between the different heights of the tube support plates 45 is due to the fact that the tube support plates 45 are made of a material whose coefficient of thermal expansion is less than that of the shroud 26 or baffle 33 so that these tube support plates 45 are heated. Can be partially achieved. The radial gap 102 shown in FIG. 4 between the tube support plate 45 and the shroud 26 or baffle 33 occurs at each position of the tube support plate alignment block 104 as the temperature of the steam generator rises. However, it provides a space for facilitating lateral displacement or deviation of each tube support plate 45.

As explained in detail below, lateral misalignment or bias is caused by the tube support plate biasing system 100 having link bars 112 that pull each side of each tube support plate 45 under tension. The differential lateral expansion of the tube support plate 45, preferably between the carbon steel shroud 11 and preferably the 410S stainless steel tube support plate 45, allows an effective lateral deflection of the tube support plate 45, and thus the flow excitation of the tube 27. Sufficient operational clearance is provided to mitigate sexual vibrations. The radial gap 102 can be reduced to zero by the link bar force.
The tube support plate alignment block 104 may be incorporated under circumstances with an initial gap that facilitates operation of the tube support plate under high temperature conditions.
As shown in FIG. 4, the desired misalignment in the tube support plate and the tube support can be achieved by alternating the tensile direction of the tube support plate that is continuous at different height positions, eg 45C, 45D, 45E, 45F. The tube 27 can be loaded into the hole 116 of the plate. In general, since the tube support plate 45 is made of a material having a sufficiently smaller coefficient of thermal expansion than the shroud, the radial gap between the tube 27 and the hole 116 at the operating temperature is such that Much larger than the gap between them.

  It is unlikely that the tube support plate 45 at all height positions in an upright heat exchanger need to be laterally misaligned. For example, the tube support plates 45 are alternately biased in the same direction, and the remaining tube support plates 45 are constrained to their original positions, thereby obtaining a desired misalignment. One or more tube support plate biasing systems 100 may be provided per height position of a tube support plate. Thus, the tube support plate biasing system 100 can variably bias a plurality of tube support plates in one or more tube support plates in one or more different directions, in the same or variable amount and direction. It also provides for controlled misalignment of one or more tube support plates in situations where one or more devices are provided on any individual tube support plate.

  Referring to FIGS. 2 and 3, the link bar 112 is shown and has a connecting end 124 and a threaded end 126. The threaded end 126 of the link bar 112 extends through the constraining plate or constraining disk 113 and the threaded groove engages the constraining nut 115. As shown in FIG. 3, the restraining disk 113 is in contact with a lip in the hand hole 132 provided in the shell 11.

  As shown in FIGS. 3-4, the tube support plate biasing system 100 is used to laterally bias the tube support plate 45. The restraining nut 115 is engaged with the link bar 112 via the thread groove. The threaded end 126 of the link bar 112 and the restraining nut 115 adjust the tension of the link bar 112 or link between the restraining disk 113 and the connecting end 124 engaged with the tube support plate 45. Accessible to adjust the length of the bar. The shell 11 is provided with a hand hole 132 for accessing the restraining nut 115. The hand hole 132 is sealed by a hand hole cover 134 with a bolt and a gasket when not in use.

In a preferred embodiment, the connecting end contact end 124 of the link bar 112 may include a finger portion that extends into the tube hole space of the tube support plate 45, as shown in FIGS. Any one or combination of the structures described can be included at each height position of the tube support plate 45.
(A) A threaded end that engages a perforated and threaded hole provided in the edge or surface of the tube support plate 45 via a threaded groove.
(B) An end portion welded to the edge or surface of the tube support plate 45.
(C) Ends that are hooked or engaged with one or more tubes 27 that extend through the tube support plate 45 and through which the inner stabilizer core is inserted or not inserted into the one or more tubes 27.
(D) The end of the tube support plate 45 hooked or engaged in a new or existing hole other than the hole normally used to receive the tube 27.
(E) an end coupled to a lip, protrusion, recess, deformed portion or flange of the tube support plate 45 or to a support rod 28 extending through the tube support plate 45;
(F) Ends that are tightly clamped to the top and bottom surfaces of the tube support plate 45 and thus clamp the tube support plate 45 between the top and bottom surfaces.

  When the shell / shroud / tube support plate assembly is heated, the shroud 26 or baffle 33 supports the tube because the thermal expansion coefficient of the shell 11 and shroud 26 or baffle 33 is greater than that of the material of the tube support plate 45. Inflates with respect to plate 45. As shown in FIG. 4, under this high temperature condition, the link bar 112 laterally biases the tube support plate 45 within the shroud 26 or baffle 33 or provides an offset 136 with respect to its initial center position 138. The tensile force of the link bar 112 causes a reaction by the tube 27 in contact or by the tube support plate alignment block 104 on the opposite side of the tube 27 and the tube support plate 45, but in any case the tensile force is obtained, Thus, the desired high tube support effect is provided.

The contact force between the tube and the tube support plate under high temperature conditions is controlled by controlling the preload or the effective length of the link bar 112 under the initial cold condition. The effective length or preload is adjustable via a handhole cover 132 that provides access to the restraining nut 115 of the link bar 112. In a cold stop situation, the handhole cover 132 may be removed for access to the link bar 112 and adjusted to rotate the restraining nut 115 to obtain the desired length or tension.
As shown in FIG. 4, by alternating the pull direction of successive tube support plates at different height positions, eg 45C, 45D, 45E, the tube support plates are misaligned as desired and the tube support plate The load on the tube 27 in each hole can be adjusted. There is probably no need to laterally misalign all tube support plate heights. For example, the desired misalignment can be achieved by shifting every other tube support plate in the same direction while maintaining the remaining tube support plates in a neutral position. One or more tube support plate biasing systems 100 with respect to the height of the tube support plate may be used.

Further, the contact force between the tube 27 and the tube support plate 45 can be controlled by limiting the lateral displacement amount or stroke of the link bar 112. The maximum stroke distance is selected as the material of the tube support plate 45 having a desired coefficient of thermal expansion, and thus the maximum radial clearance between the tube support plate 45 and the tube support plate alignment block 104 under high temperature conditions. Can be controlled by limiting the stroke length or adjusting the effective length of the link bar 112.
The link bar 112 may include any desired cross-section bar or cable, or a chain or tubular structure of material selected to meet applicable pressure, temperature, and stress conditions.

Benefits of the present invention include the following.
The tube support plate 45 is incorporated in an aligned configuration that is compatible with normal manufacturing processes. The desired misalignment occurs only under the high temperature conditions of the heat exchanger.
Misalignment of the tube support plate 45 under high temperature conditions can mitigate tube vibration based on cross flow or axial flow excitability mechanisms.
The contact load between the tube and the tube support plate under high temperature conditions can be controlled by controlling the effective length or tension of the link bar, the amount of deflection of the tube support plate, or a combination thereof.
The normal load path used to transfer the seismic load between the tube 27, tube support plate 45, shroud 26 or baffle 33, and shell 11 is unchanged.
The tube support plate biasing system 110 is engaged with each other through a threaded groove and has three members as members to be placed inside the steam generator shell 11, namely a link bar 112 and a restraining plate or disk 113, and a screw. It has only a restraining nut 115 that engages through a groove, thus minimizing the risk of component loss.
Access to the hardware that adjusts the tension or length of the link bar 112 is easy.

The contact end 124 of the link bar is disposed in the shroud opening 130 and the threaded end 126 is disposed in the hand hole 132. The link bar 112 engages with the restraining plate or disk 113 and the restraining nut 115 via the threaded groove, thus preventing the possibility of losing parts with each other.
The link bar tension is counteracted by the shell 11, which is a rigid anchor point, rather than the relatively flexible shroud 26 or baffle 33.

The present invention can be incorporated into an existing apparatus because the required change amount inside the apparatus is small. Conversely, the tube support plate biasing system 150 can be easily removed to return the steam generator to its original condition.
The tube support plate alignment block 104 can be incorporated in an initial gap amount that facilitates deflection of the tube support plate during heating of the heat exchanger.
Although the present invention has been described with reference to the embodiments, it should be understood that various modifications can be made within the present invention.

DESCRIPTION OF SYMBOLS 10 Steam generator 11 Shell 12 Upper head 13 Lower head 14 Upper tube sheet 15 Primary coolant inlet 16 Human passage 17 Hand hole 18 Drain 19 Riser chamber 20 Cooling water outlet 21 Hand hole 22 Human passage 23 Tube plate 25 Structure floor 26 Shroud 27 Each Pipe 28 Support rod system 30 Water port 31 Precipitation pipe annular space 32 Steam discharge hole 33 Baffle 34 Header 35 Water supply inlet nozzle 37 Annular plate 40 Steam outlet nozzle 41 Auxiliary water supply header 42 Nozzle 43 Outlet passage 45, 45A, 45B Pipe support plate 48 Tube support plate alignment block 49 shroud alignment pin 100 tube support plate biasing system 102 radial gap 104 tube support plate alignment block 106 shroud alignment pin 110 tube support plate biasing system 112 link bar 114 Shuroddo 115 constrained nut 118 central portion 120 opening 122 tapered portions 124 contact end 126 pivot end 128 drives the head 130 opening 132 hand hole 134 hand hole cover 138 central position 150 tube support plate displacement system

Claims (27)

A plurality of parallelly spaced tubes for fluid flow, each having a tube that conducts heat to the fluid flowing along the tube, and a plurality of tubes arranged laterally across each tube A steam generator assembly and operation method further comprising a support plate, comprising:
Aligning the tube support plates;
Passing the tube through the aligned tube support plate,
During heating of the steam generator, at least one tube support plate is laterally offset and misaligned across the tube by a link bar having a coupling end coupled to the tube support plate , thus providing tube support effects. To increase,
Including methods.   During heating of the steam generator, at least one tube support plate can be laterally displaced across the tube and misaligned, thus increasing the tube support effect. The method of claim 1, further comprising biasing in the same transverse direction across.   While heating the steam generator, at least one tube support plate is laterally offset across the tube and misaligned, thus increasing the tube support effect is the same as crossing the tube support plate across the tube. The method of claim 1 further comprising biasing every other lateral direction.   During heating of the steam generator, the at least one tube support plate is laterally biased across the tube and misaligned, thus increasing the tube support effect, the tube support plate across the tube. 2. The method of claim 1, further comprising alternately biasing in the same first lateral direction and biasing the remaining tube support plates in a second lateral direction across the tube opposite to the first lateral direction.   During heating of the steam generator, the at least one tube support plate is laterally offset across the tubes and misaligned, thus increasing the tube support effect. Alternately biasing in the same first lateral direction across the tube and biasing the remaining plurality of tube support plates in a second lateral direction across the tube opposite to the first lateral direction. The method of claim 1 comprising:   While heating the steam generator, at least one tube support plate is laterally offset across the tubes and misaligned, thus increasing the tube support effect, biasing the plurality of tube support plates The method of claim 1 further comprising:   While heating the steam generator, the at least one tube support plate is laterally offset across the tubes and misaligned, thus increasing the tube support effect, allowing multiple tube support plates to be displaced by a variable amount. The method of claim 6 further comprising:   During heating of the steam generator, at least one tube support plate is laterally offset across the tube and misaligned, thus increasing the tube support effect, 7. The method of claim 6, further comprising biasing in one or more of the directions.   While heating the steam generator, it is possible to cause the at least one tube support plate to be laterally offset across the tubes and misaligned, thus increasing the tube support effect. The method of claim 1, further comprising biasing the variable amount in one or more of the directions. A plurality of parallel spaced tubes for fluid flow, each tube having a tube for transferring heat to fluid flowing along the tube, further comprising a cylindrical shroud, the shroud comprising: A tube support system for use in a steam generator disposed within a cylindrical pressure shell and surrounding a shroud, comprising:
A tube support plate made of a material having a coefficient of thermal expansion smaller than that of the shroud, with a tube support plate disposed across each tube;
Means for biasing the tube support plate in a transverse direction across each tube;
Only including,
Means, including the tube support system a link bar having a coupling end for coupling to a tube support plate for biasing the tube support plate in the horizontal direction transverse to the respective tubes.   11. The tube support system of claim 10, wherein the tube support plate is made from 410S stainless steel and the shroud is made from carbon steel. 11. The tube support system of claim 10 , wherein the means for biasing the tube support plate in a transverse direction across each tube includes a restraint plate, a restraint nut that engages the link bar and threaded groove. The tube support system of claim 12 , wherein the link bar is positioned within the shell. 13. The tube support system of claim 12 , wherein the link bar is adjustable in length or tension. The tube support system of claim 12 , wherein the restraining plate is coupled to the shell. 11. The tube support of claim 10 , wherein the coupling end includes a threaded end that is perforated and engages the tap hole and the threaded groove provided in an edge or surface of the tube support plate. system. 11. The tube support system of claim 10 , wherein the coupling end includes an end welded to an edge or surface of the tube support plate. The tube support system of claim 10 , wherein the coupling end includes an end hooked or engaged with one or more tubes extending through the tube support plate. 19. The tube support system of claim 18 , wherein the one or more tubes that hook or engage the coupling end are provided with an inner stabilizer core that is inserted through the one or more tubes. 11. The tube support system of claim 10 , wherein the coupling end includes an end hooked or engaged in a new or existing hole other than the hole normally used to receive the tube. 11. The tube support system of claim 10 , wherein the coupling end includes an end coupled to a lip, protrusion, recess, deformed portion or flange of the tube support plate or to a support rod extending through the tube support plate. 11. The tube support system of claim 10 , wherein the coupling end includes an end that is tightly clamped to the top and bottom surfaces of the tube support plate, thus sandwiching the tube support plate between the top and bottom surfaces.   The tube support plate is made of a material whose coefficient of thermal expansion is sufficiently lower than that of the shroud surrounding the tubes, thus the radial gap between the tubes and the support holes of the tubes at the operating temperature. 11. The tube support system of claim 10, wherein the tube support system is much larger than the gap between the two. A plurality of parallelly spaced tubes for fluid flow, each having a tube that conducts heat to the fluid flowing along the tube, and a plurality of tubes arranged laterally across each tube A tube support biasing system for use in a steam generator, further comprising a support plate and a cylindrical shroud, further comprising a shroud disposed within the cylindrical pressure shell and surrounding each tube,
In the link bar coupled to an end thereof to the tube support plate, the machine configuration of the link bar engages for adjusting the effective length to limit the maximum lateral deviation amount of the tube support plate during the operation of the steam generator,
Tube support biasing system including: 25. The tube support biasing system of claim 24 , including access means through the pressure shell for adjusting the effective length of the link bar or tension on the link bar. 25. The tube support biasing system of claim 24 , wherein the material of the tube support plate is preselected to limit the maximum lateral deflection of the link bar. 25. The tube support biasing system of claim 24 , wherein the link bar is the only component of the tube support biasing system positioned within the inner diameter portion of the shell.

Images