US3892205A - Steam generator - Google Patents

Steam generator Download PDF

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Publication number
US3892205A
US3892205A US439699A US43969974A US3892205A US 3892205 A US3892205 A US 3892205A US 439699 A US439699 A US 439699A US 43969974 A US43969974 A US 43969974A US 3892205 A US3892205 A US 3892205A
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United States
Prior art keywords
steam generator
sodium
tubes
heating medium
generator according
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Expired - Lifetime
Application number
US439699A
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English (en)
Inventor
Masanori Naitou
Hiraku Nakano
Shinichi Kashiwai
Chikara Satou
Motoaki Utamura
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Hitachi Ltd
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Hitachi Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B1/00—Methods of steam generation characterised by form of heating method
    • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
    • F22B1/06—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being molten; Use of molten metal, e.g. zinc, as heat transfer medium
    • F22B1/063—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being molten; Use of molten metal, e.g. zinc, as heat transfer medium for metal cooled nuclear reactors

Definitions

  • a vertical shell-and-tube heat exchanger of the type in D which water is flown inside the tubes from a lower sec- Appl'cauon Pnomy Dam tion while liquid sodium is flown outside the tubes Feb. I6, 1973 Japan 48 18265 from an upper section is provided.
  • a liquid metal stable to both water and liquid sodium and greater in 5/135; /163 density than said liquid sodium is placed in a lower [Sl] Int. Cl.
  • This invention relates to a steam generator adapted for use in a fast neutron reactor where liquid sodium is used as heating medium.
  • liquid sodium has been used as heating fluid in most of the steam generators for fast neutron reactors.
  • an alkali metal such as sodium has a disposition to become reacted vehemently with water, or the object to be heated, to develop tremendous reaction heat while producing at the same time a great quantity of hydrogen. lt is therefore required to keep strict watch over leakage of water or sodium in the steam generator to avoid sodium-water reaction that becomes a source of troubles.
  • the water supply header and the steam header at the top of the steam generator are positioned closely adjacent to each other and their temperature difference is excessively wide (about 270C), so that the upper spherical head is always exposed to danger of thermal stress. Also, sodium coheres to the tube plate on the water feed side in long-time use, causing tremendous temperature difference (about 300C) corrosion by sodium, so that difficulties are raised over designing and maintenance of the tube plate on the water feed side.
  • the object of the present invention is to provide an improved steam generator which is free of the described defects of the prior art and which is high in heat characteristic, simple and compact in structure, and easy of operation and maintenance.
  • the header construction used is same as in the conventional systems, there is a greater danger of causing sodium-water reaction, and resultant troubles, due to possible water leakage from the tube plate section of the water supply header particularly when the the operation is continued for a long time. This is the very reason why the disposition of the water supply header at the botton of the steam generator has been tabooed.
  • the present invention has succeeded in overcoming the problems that arise from such bottom-wise provision of the water supply header while allowing best use of the meritorious points of such arrangement.
  • the salient feature of the present invention resides in that liquid metal which is concordant with both sodium and water is disposed above the tube plate of the water supply header provided at the bottom of the steam generator, so as to prevent sodium from directly contacting with the tube plate section on the water supply side.
  • An no downcast pipe is provided, there is no need of providing a thermal shield and means for controlling flow rate and temperature of feed water in the relevant section, thus allowing smooth heat exchange between sodium and feed water. Also, the generating surface area can be reduced (by about 15 percent) and sensible heat of sodium can be utilized to the maximum degree.
  • FlG. l is a longitudinal sectional view of a conventional steam generator
  • FIG. 2 is a partial sectional view of another conventional steam generator
  • FIG. 3 is a longitudinal sectional view of a steam generator according to the present invention.
  • FIG. 4 is a temperature diagram of feed water and sodium in the conventional devices and the present invention.
  • a conventional steam generator comprising the shell l, a tube plate 3 on the water supply side, a water supply header 5, a gas side flange 6, an outlet steam header 7, an upper tube plate 8, a tube supporting structure 9, downcast pipes 10, tubes 11, a sodium inlet nozzle 12, a sodium outlet nozzle 13, a thermal shielding plate 19, a feed water layer 21, an inlet nozzle of feed water 21a, a steam layer 22, a steam discharge nozzle 220, a sodium layer 24, an inert gas layer 25, an inert gas feed nozzle 25a, and an inert gas dicharge nozzle 25b.
  • Letter A indicates the position of feed water in the downcast pipes 10 which stay in the interface between the inert gas layer 25 and the sodium layer 24, a the sodium of the same interface thereof, B the position of feed water at the bottommost end of the downcast pipes 10, b the position of sodium 24 at the same level as B, C the position of steam in the tubes 11 at said sodium interface, the interface thereof, and d the sodium in the sodium outlet nozzle 13.
  • a plurality of downcast pipes 10 extend downwardly along the outside of the thennal shielding plate 19 from the tube plate 3 of the water supply header and are turned back at the bottom of the shell 1 to extend now upwardly to serve as tubes while helically surrounding the thermal shielding plate 19 and the tube supporting structure 9 with the aid of a mounting seat (not shown) disposed at an outer peripheral part of said supporting structure 9 which is closed at its top and bottom, and said tubes are finally converged in the outlet steam header 7.
  • said plurality of downcast pipes and tubes 11 are formed from seamless low carbon steel pipes (for use in high temperatures) or seamless stainless steel pipes (for use in low temperatures) arranged with same length, and the tube supporting structure 9 and thermal shield plate 19 are retained in position along with said downcast pipes l0, tubes ll and sodium inlet nozzles 12 by the tube plates 3, 8 and gas side flange 6.
  • feed water is supplied to the header 5 under pressure of around 175 kg/cm g at 240C, and such feed water flows down in the downcast pipes 10 until it reaches the bottommost end B.
  • said feed water now rises up in the tubes 11, and in the course of this ascent, said water is heated by sodium and then collected in the steam header 7 in the form of superheated vapor with pressure of around kg/cm' g and temperature of about 513C.
  • sodium of approximately 540C is supplied from the inlet nozzle l2 and descends around the tubes 11 within the thermal shield 19 while heating water in said tubes. Through this heat exchange, said sodium is cooled to about 300C and then discharged out from the sodium outlet nozzle 13.
  • the space at the top of the shell 1 is provided an inert gas layer 25, and the sodium liquid levels a and c are always maintained constant.
  • FIG. 2 shows, in section, the water supply header and its vicinity in a steam generator using such double-pipe arrangement.
  • reference numeral 1 indicates the shell of the steam generator, 3 a tube plate on the water side, 5 a water supply header, ll tubes, 12 a sodium inlet nozzle, 13 a sodium outlet nozzle, 14 a mercury inlet nozzle, 21 a feed water layer, 21a a feed water inlet nozzle, 23 a mercury layer, and 31 outer pipes.
  • Mercury is supplied from the inlet nozzle 14 and charged into the outer pipes around the tubes 11 to form a mercury layer 23, while high-temperature sodium is supplied from the inlet nozzle 12 and discharged out, after cooled, from the outlet nozzle 13.
  • feed water enters the header 5 through the nozzle 21a and passes through the tubes 11, and during passage through said tubes, it is heated by a high-temperature sodium and is withdrawn in the form of high-temperature steam from a steam header (not shown) at the other end.
  • reference numeral 1 designates the shell of the steam generator, 2 a heating medium reservoir tank, 3 a lower tube plate, 4 a flange, 5 a water supply header, 6 a gas side flange, 7 an outlet steam header, 8 an upper tube plate, 9 a tube supporting structure, 11 tubes, 12 a sodium inlet nozzle, 13 a sodium outlet noule, 14 a heating medium inlet nozzle, 15 a heating medium outlet nozzle, 21 a feed water layer, 21a an inlet nozzle of feed water, 22 a steam layer, 220 a steam outlet nozzle, 23 a heating medium layer, 24 a sodium layer, 25 an inert gas layer, 25a an inert gas feed nozzle, and 25b an inert gas discharge nozzle.
  • the tube supporting structure 9 per se and its operational relation with the tube 11 are same as those in conventional apparatus shown in FIG. 1.
  • the salient structural differences of the present invention from the conventional apparatus shown in FIG. 1 are that the water supply header 5 is provided at the bottom of the generator body and the steam header 7 at the top thereof, with said both headers being connected respectively through a flange to a plurality of tubes arranged with equal length coiling around the tube sup porting structure 9, and that a layer of a heating medium 23 such as mercury is provided between the water feed side flange and feed sodium.
  • the heating medium used here is a substance which is not dissolved, diffused or emulfied in (that is, physically inert to) both water and sodium and is also not chemically reacted with (that is, chemically inert to) water and sodium and which has a melting point of lower than 300C and is greater in density than sodium.
  • mercury is used for such heating medium in the embodiment discussed hcre
  • the heating medium usable in the present invention is of course not limited to mercury; it is possible to use molten metal such as bismuth or indium or their alloys, or stabilized alloys thereof with sodium.
  • the tube supporting structure 9 is adapted to securely fix the tubes arranged helically therearound and is closed at its both upper and lower ends.
  • mercury is supplied into the mercury reservoir 2 in an amount of about 70 percent so that it will not be affected by the flow sodium, then sodium is charged into the steam generator and an inert gas is further supplied thereabove to thereby fill the steam generator.
  • high-temperature sodium is supplied from the inlet nozzle 12 and flown down passing between the tubes 11 and discharged out from the outlet nozzle 13 at the bottom of the shell 1.
  • sodium flows down as a one-way current and its central portion is also occupied by the tube supporting structure and the tubes, there is no reason for a chance of disturbing the flow of sodium in the vicinity of the mercury reservoir 2.
  • feed water supplied to the feed water header 5 flows upward through the mercury layer 23 and the sodium layer 24 into the tubes 11 where said water is further heated while swirling and boiled to produce steam which is once collected in the steam header 7 and then released out therefrom.
  • d refers to the bottom surface of the heating medium layer
  • d the interface of the heating medium and sodium
  • C the interface of sodium an inert gas.
  • D, D and C indicate the positions of feed water corresponding to said respective interfaces.
  • FIG. 4 shows a temperature diagram of the present invention in comparison with the prior art apparatus (FIG. 1).
  • temperature transition of feed water traces the course A B C and that of sodium follows the course a b c.
  • the segment A B indicates temperature transition in the downcast pipes, with the point B signifying the bottommost end of the downcast pipes.
  • Corresponding sodium temperature is also low as indicated by b.
  • feed water in the section A B serves as heat exchanger, it is rather required to provide a detection-control system for restraining rise of temperature of feed water under a certain level. Further, temperature difference between sodium and feed water in this section is reversed and also their flows are parallel, so that this section is not in a situation which permits performance of normal heat exchange.
  • the segment B C represents temperature transition of feed water in the tubes and corresponding temperature transition of sodium is indicated by segment b c. In this section, temperature difference between them is maintained substantially constant and also their flows are counter current, so that ideal heat exchange can be effected in this section.
  • the heating surface area expands wide from I to V (in FIG. 4) and a part thereof is actually little utilized, whereas in the present invention such area is limited to the section I-IV, allowing about 15 percent reduction.
  • the present invention has been described by way of an embodiment where the headers are provided at both top and bottom and the tubes are coiled helically around a support structure, with the entire unit being vertical, the present invention is not limited to such particular embodiment; it sufficis if the entire unit is arranged vertically such that heat exchange between sodium and water is accomplished in a counter current condition and sodium and water are sealed at the bottom through a liquid metal which can coexist stably with said sodium and water.
  • liquid sodium was nominated as the heating medium while water as the object to be heated, but such heating medium and object to be heated are not limited to sodium and water, respectively. It is possible to use any other suitable combination of liquids which are well reactive to each other.
  • a steam generator of a vertical multitubular (bushing) type having at least one tube plate at the lower end of the tubes and using two fluids flowing inside and outside said tubes respectively and reacted by contact with each other.
  • a reservoir located outside said tubes and on-said tube plate at the lower end of said tubes, and an intermediate heating medium disposed in said reservoir, said medium being physicochemically inert to said both fluids, and is greater in density than said both fluids, and has melting point of not higher than 300C.
  • heating medium is an alloy composed of a combination of two or more of sodium, mercury, bismuth, lead and indium.
  • a steam generator of a vertical multitubular type comprising a shell, a heating fluid inlet nozzle and inert gas feed and discharge nozzles provided at the top of said shell, an outlet nozzle for said heating fluid provided at the bottom of said shell, a vapor header and a feed liquid header provided at the top and bottom, respectively, of said shell, upper and lower tube plates mounted to said respective headers, a plurality of helically arranged tubes connected through said respective tube plates to said respective headers, a support structure including a cylindrical body for supporting said plurality of helical tubes, and a reservoir of an intermediate heating medium which is physico-chemically inert to said both feed liquid and heating fluid and which is greater in density than said heating fluid and has melting point of lower than 300C, said reservoir being disposed on said lower tube plate so as to enclose fixed portions of said tubes and said tube plate in a bundle.
  • heating medium is an alloy made of a combination of two or more of sodium, mercury, bismuth, lead and indium.
  • a shell comprising a heating fluid inlet nozzle and inert gas feed and discharge nozzles provided at the top of said shell, an outlet nozzle for said heating fluid provided at the bottom of said shell, a vapor header and a feed liquid header provided at the top and bottom, respectively, of said shell, upper and lower tube plates mounted to said respective headers, a plurality of helically arranged tubes connected through said respective tube plates to said respective headers, a support structure including a cylindrical body for supporting said plurality of helical pipes, and a cylindrical reservoir of an intermediate heating medium which is physicochemically inert to said both feed liquid and heating fluid and which is greater in density than said both feed liquid and heating fluid and has melting point of lower than 300C, said cylindrical reservoir disposed on said lower tube plate so as to enclose fixed portions of said tubes and said tube plate in a bundle.
  • heating medium is an alloy composed of a combination of two or more of sodium, mercury, bismuth, lead and indium.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
US439699A 1973-02-16 1974-02-05 Steam generator Expired - Lifetime US3892205A (en)

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Application Number Priority Date Filing Date Title
JP48018265A JPS49105001A (enrdf_load_stackoverflow) 1973-02-16 1973-02-16

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US3892205A true US3892205A (en) 1975-07-01

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US (1) US3892205A (enrdf_load_stackoverflow)
JP (1) JPS49105001A (enrdf_load_stackoverflow)
DE (1) DE2407366A1 (enrdf_load_stackoverflow)
FR (1) FR2228194B1 (enrdf_load_stackoverflow)
GB (1) GB1430493A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4249484A (en) * 1978-01-18 1981-02-10 Commissariat A L'energie Atomique Steam generator with an integrated reheater fed with a liquid metal
FR2792652A1 (fr) * 1999-04-23 2000-10-27 Centre Nat Rech Scient Procede de traitement de sodium pour le controle de sa reactivite
US6620969B1 (en) * 1999-03-11 2003-09-16 Nippon Shokubai Co. , Ltd. Shell-and-tube heat exchanger and method for inhibiting polymerization in the shell-and-tube heat exchanger
US20060065254A1 (en) * 2004-09-30 2006-03-30 Tsuneyuki Okabe Vaporizer

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2379881A1 (fr) * 1977-02-04 1978-09-01 Commissariat Energie Atomique Bloc-pompe echangeur de chaleur pour reacteurs nucleaires
FR2564229B1 (fr) * 1984-05-11 1986-09-05 Commissariat Energie Atomique Reacteur nucleaire a neutrons rapides a generateur de vapeur integre dans la cuve

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3395676A (en) * 1966-07-05 1968-08-06 Babcock & Wilcox Co Vapor generator
US3628507A (en) * 1968-12-14 1971-12-21 Progettazioni Meccaniche Nucle Liquid metal heated steam generators and superheaters
US3732922A (en) * 1970-03-06 1973-05-15 Stein Industrie Heat-exchanger module
US3768554A (en) * 1968-06-10 1973-10-30 Westinghouse Electric Corp Steam generator heated with liquid metal

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3395676A (en) * 1966-07-05 1968-08-06 Babcock & Wilcox Co Vapor generator
US3768554A (en) * 1968-06-10 1973-10-30 Westinghouse Electric Corp Steam generator heated with liquid metal
US3628507A (en) * 1968-12-14 1971-12-21 Progettazioni Meccaniche Nucle Liquid metal heated steam generators and superheaters
US3732922A (en) * 1970-03-06 1973-05-15 Stein Industrie Heat-exchanger module

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4249484A (en) * 1978-01-18 1981-02-10 Commissariat A L'energie Atomique Steam generator with an integrated reheater fed with a liquid metal
US6620969B1 (en) * 1999-03-11 2003-09-16 Nippon Shokubai Co. , Ltd. Shell-and-tube heat exchanger and method for inhibiting polymerization in the shell-and-tube heat exchanger
FR2792652A1 (fr) * 1999-04-23 2000-10-27 Centre Nat Rech Scient Procede de traitement de sodium pour le controle de sa reactivite
US20060065254A1 (en) * 2004-09-30 2006-03-30 Tsuneyuki Okabe Vaporizer
US7452424B2 (en) * 2004-09-30 2008-11-18 Tokyo Electron Limited Vaporizer

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Publication number Publication date
FR2228194B1 (enrdf_load_stackoverflow) 1977-09-09
DE2407366A1 (de) 1974-09-12
GB1430493A (en) 1976-03-31
JPS49105001A (enrdf_load_stackoverflow) 1974-10-04
FR2228194A1 (enrdf_load_stackoverflow) 1974-11-29

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