US3889641A - Steam generator feed-water preheater improvement - Google Patents

Steam generator feed-water preheater improvement Download PDF

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Publication number
US3889641A
US3889641A US434360A US43436074A US3889641A US 3889641 A US3889641 A US 3889641A US 434360 A US434360 A US 434360A US 43436074 A US43436074 A US 43436074A US 3889641 A US3889641 A US 3889641A
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United States
Prior art keywords
feed
water
preheater
baffles
steam
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US434360A
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English (en)
Inventor
Hans Mayer
Heinz-Jurgen Schroeder
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Siemens AG
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Siemens AG
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Filing date
Publication date
Priority claimed from DE19732303681 external-priority patent/DE2303681C3/de
Application filed by Siemens AG filed Critical Siemens AG
Application granted granted Critical
Publication of US3889641A publication Critical patent/US3889641A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F22B1/023—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers with heating tubes, for nuclear reactors as far as they are not classified, according to a specified heating fluid, in another group
    • F22B1/025—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers with heating tubes, for nuclear reactors as far as they are not classified, according to a specified heating fluid, in another group with vertical U shaped tubes carried on a horizontal tube sheet

Definitions

  • a steam generator includes a feed-water casing having a steam output outlet and enclosing a horizontal tube sheet in which are mounted the ends of a plurality of heat-exchanger tubes extending upwardly therefrom and radially enclosed by a casing of a feed-water preheater having a series of vertically interspaced transverse feed-water flow baffles through which the heat exchanger tubes extend and which define alternately horizontal offset flow passages.
  • a feed-water inlet connects with the upper portion of this series of baffles for downward flow through the preheater of externally introduced feed-water.
  • the feed-water flowing through the preheater may convert to steam which collects beneath one or more of the preheaters flow baffles. reducing the feed-water flow rate and resulting in further and more rapid steam conversion while precipitating compounds inevitably included by the feed-water and which are corrosive with respect to the preheaters parts and the heat exchanger itself.
  • steam venting tubes are built into the preheater so as to extend from those areas beneath the flow baffle plates where such steam can collect, and which extend upwardly through the preheater and open above the latter into the feedwater casing where the steam can rise upwardly through ascending feed-water and escape.
  • This invention relates to a steam generator having a feed-water preheater and which is of the type used in a pressurized-water reactor power plant. That type includes a vertical, generally cylindrical feed-water casing having its top closed by a steam dome having a steam output outlet and its bottom closed by a horizontal tube sheet in which the inlet and outlet legs of an inverter U-shaped tube bundle are mounted and having appropriate inlet and outlet manifolds therebelow and through which the reactors water coolant is circulated through the tube bundle. The latter is enclosed by a cylindrical shroud having an open top and bottom and radially spaced from the inside of the feed-water casing to form a descent space.
  • Feed-water from an external source is fed to the easings inside to maintain a water level above the top of the heat exchanger, the feed-water ascending within the shroud and flowing over its top and descending through the descent space.
  • the water converts to steam while ascending and the top of the shroud is normally provided with a steam-water separator, the steam leaving via the steam output outlet and the separated water flowing into the feed-water for descent via the descent space.
  • a feed-water preheater is built around the outlet leg of the heat-exchanger tube bundle.
  • This preheater is formed by a casing radially enclosing the heat-exchangers outlet leg and containing a series of vertically interspaced transverse feed-water flow baffles through which the heat-exchanger tubes extend and which define alternately horizontally offset flow passages.
  • the feed-water is introduced to this preheater so as to flow sinuously back and forth between the heat-exchanger tubes in either an upward or downward direction, but in either case discharging into the inside of the shroud.
  • the baffles are horizontal plates alternately connected with opposite side walls of the preheater and, therefore, forming corner areas. If excessive preheating occurs, the feed-water may convert to steam which be comes entrapped in such corner areas, this reducing the feed-water flow rate so that more steam develops. When the feed-water converts to steam, it precipitates compounds inevitably carried by the feed-water and which are corrosive with respect to the preheater parts and the heat-exchanger tubes. With time the steam generator must be shut down to remove accumulations of such deposits.
  • the object of the present invention is to provide a preheater construction avoiding the above-indicated trouble.
  • baffles which join with the preheater casing to form the corner areas are provided with tubes having lower ends opening to these areas through the baffles involved, these tubes extending upwardly through the preheater to above its top which is open to the ascending feed-water within the shroud.
  • baffles are normally horizontal and each upper one of the flow passages is above the portion of the next lower baffle defining the steam-entrapping corner area, so the tube extending from the latter area can pass upwardly through that flow passage in each instance without being required to extend through the next upper one of the baffles.
  • Each corner area is necessarily of extended horizontal length, and therefore, for each of said areas a plurality of the tubes are used, the tubes extending vertically upwardly through the preheater in mutually parallel relationship and each forming a row of tubes as to each of the areas to be vented.
  • FIG. 1 schematically shows in vertical section a steam generator including a preheater embodying the principles of the invention
  • FIG. 2 schematically shows the top of that preheater.
  • the illustrated steam generator is of the type used in the case of a pressurizedwater reactor power plant. It includes a generally cylindrical feed-water casing 1 having an upper portion closed by a steam dome 2 provided with a steam output outlet 3, and a lower portion closed by a horizontal tube sheet 4 in which the input leg 5 and the output leg 6 of the heat exchanger are mounted.
  • This heat exchanger is illustrated only by broken lines, but it is to be understood as being of the inverted U- shaped tube bundle type.
  • An inlet manifold 7 having a pressurized-water connection 8 feeds the pressurizedwater coolant through the tube sheet 4 into the inlet leg 5, the outlet leg 6, normally called the cold leg, feeding through the tube sheet 4 to an outlet manifold 9 having an outlet connection 10.
  • the entire heat exchanger is radially enclosed by a shroud l1 radially spaced from the inside of the casing l to form a descent space 12, the top of the shroud mounting a steam-water separator 13 from which the steam goes to the output outlet 3 via a fine water separator 14, the separated water flowing downwardly into and through the descent space 12 for descent to the tube sheet 4 and radially inwardly via an opening 15 for ascent within the shroud around the heat-exchanger legs 5 and 6 while vaporizing to steam.
  • the desired water level within the casing l is obtained accurately by the addition of feed-water via an inlet 16 connecting with the perforated annular tube 17 surrounding the water separator 13, and for emergency purposes, another feed-water inlet 18 is provided. Although these feed-water elements are illustrated, they do not provide the main feed-water input.
  • Two main feed-water inlets l9 and 20 provide the main feed-water input to the casing 1. It is this main feed-water input that is desirably preheated to avoid thermal shock to the heat exchanger and the tube sheet 4.
  • the illustrated preheater is formed by a semicylindri cal preheater casing enclosing the lower end of the outlet leg 6 which is also of generally semicylindrical contour. This casing is in part formed by an adjacent lower portion Ha of the shroud, and in part by a vertical transverse wall 21 which extends through the space between the legs and 6.
  • a transverse horizontal wall 22 extends completely between the side walls 11a and 21 to divide the preheater into upper and lower sections, the feed-water input connection 19 connecting above this wall 22 with the upper section, and the feed-water input connection 20 connecting below this wall 22 to feed through the lower section.
  • This lower section beneath the wall 22, has a series of vertically interspaced horizontal baffle plates of which the plate 23 connect with the side wall 110 and extends therefrom partially to the wall 21 to define a flow passage 24.
  • a horizontal baffle 25 connects with the wall 21 and extends partially to the wall 110 to define a flow passage 26.
  • a horizontal baffle 27 which connects with the wall 11a and extends partially to the wall 21 to define a flow passage 28, while a bottom wall 29 connects with the wall 21 and extends to define the preheater discharge opening 30 which discharges the preheater feedwater to the top of the tube sheet 40 and, of course, inwardly around the tubes of the heat exchangers cold leg 6 at that location.
  • the upper preheater section above the wall 22, is correspondingly arranged but is not described in detail. That section discharges upwardly to the feed-water ascending within the shroud 11 and does not involve the steam accumulating or pocketing trouble to the same degree as does the lower section of the preheater where the feedwater flow is downward. In both sections the feed-water flow is as indicated by the arrows shown in FIG. 1.
  • corner area adjacent to the junction between the horizontal baffle 25 and the vertical casing wall 21, the previously described corner area is formed below the plate 25, and that adjacent to the junction between the baffle 27 and the preheater casings side wall 11a another of the corner areas is formed.
  • corner areas or pockets extend along horizontally for substantial distances and it is in these areas that the steam can collect. The trouble is most apt to occur in the lower most portion of the preheater because the feed-water is gradually increasing in temperature as it progresses through the preheater. incidentally, such a preheater may have more baffles than are shown.
  • the venting means of the present invention is shown as comprising a series of vertical tubes 31 arranged as a row of vertical tubes which are laterally or horizontally interspaced with this series extending along the entire length of the wall 21 and opening into the entire length of the corner area formed between the horizontal baffle 25 and this side wall 21.
  • These tubes do not need to extend through all of the baffles above the baffle 25, because each of the passages corresponding to the flow passages 24 are located above the vented corner area. Therefore, these tubes need extend only through alternate ones of the higher baffles.
  • the feed-water can exit upwardly through the tubes 31 and 32, discharging upwardly into the upward flowing feed-water within the shroud 11. This venting of the feed-water from the corner areas in and of itself tends to reduce the initial formation collection of steam in these areas. If steam does form, it can immediately vent upwardly through the tubes 31 and 32 so that solid water is maintained in the corner areas.
  • a steam generator comprises a feed-water casing having a steam output outlet, a horizontal tube sheet enclosed by said casing, a plurality of heat-exchanger tubes having ends mounted in said tube sheet and extending upwardly therefrom, a feed-water preheater casing radially enclosing said legs and having a series of vertically interspaced transverse feed-water flow baffles through which said tubes extend and which define alternately horizontally offset flow passages, and a feed-water inlet connecting with the upper portion of said series of baffles for downward flow of feed-water deflected transversely alternately in opposite directions between said tubes prior to discharge into said feedwater casing; wherein the improvement comprises means for venting steam from beneath at least one of said baffles, upwardly and to a location free from said series of baffles.
US434360A 1973-01-25 1974-01-17 Steam generator feed-water preheater improvement Expired - Lifetime US3889641A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19732303681 DE2303681C3 (de) 1973-01-25 Dampferzeuger mit einem Vorwärmer

Publications (1)

Publication Number Publication Date
US3889641A true US3889641A (en) 1975-06-17

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Application Number Title Priority Date Filing Date
US434360A Expired - Lifetime US3889641A (en) 1973-01-25 1974-01-17 Steam generator feed-water preheater improvement

Country Status (9)

Country Link
US (1) US3889641A (es)
JP (1) JPS49109702A (es)
AR (1) AR202467A1 (es)
BE (1) BE809698A (es)
CH (1) CH563552A5 (es)
ES (1) ES422584A1 (es)
FR (1) FR2226052A5 (es)
GB (1) GB1426403A (es)
IT (1) IT1007006B (es)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6199515B1 (en) * 1998-01-12 2001-03-13 Beatrae Sadia Heating Limited Baffles for water heaters
US6510819B1 (en) * 2000-09-26 2003-01-28 Premark Feg L.L.C. Inlet baffle for water heater
US20060056572A1 (en) * 2002-04-12 2006-03-16 Framatome Anp Method and device for the production of electricity from the heat produced in the core of at least one high temperature nuclear reactor
US20130125839A1 (en) * 2010-08-02 2013-05-23 L'air Liquide Societe Anonyme Pour L'etude Et L' Exploitation Des Procedes Georges Claude U-tube vaporizer

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3147743A (en) * 1962-05-08 1964-09-08 Combustion Eng Vertical recirculating type vapor generator
US3182719A (en) * 1962-01-10 1965-05-11 Escher Wyss Ag Multitubular heat exchanger
US3766892A (en) * 1972-04-21 1973-10-23 Combustion Eng Split feed economizer
US3811498A (en) * 1972-04-27 1974-05-21 Babcock & Wilcox Co Industrial technique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3182719A (en) * 1962-01-10 1965-05-11 Escher Wyss Ag Multitubular heat exchanger
US3147743A (en) * 1962-05-08 1964-09-08 Combustion Eng Vertical recirculating type vapor generator
US3766892A (en) * 1972-04-21 1973-10-23 Combustion Eng Split feed economizer
US3811498A (en) * 1972-04-27 1974-05-21 Babcock & Wilcox Co Industrial technique

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6199515B1 (en) * 1998-01-12 2001-03-13 Beatrae Sadia Heating Limited Baffles for water heaters
US6510819B1 (en) * 2000-09-26 2003-01-28 Premark Feg L.L.C. Inlet baffle for water heater
USRE40307E1 (en) 2000-09-26 2008-05-13 Premark Feg L.L.C. Inlet baffle for water heater
US20060056572A1 (en) * 2002-04-12 2006-03-16 Framatome Anp Method and device for the production of electricity from the heat produced in the core of at least one high temperature nuclear reactor
US20130125839A1 (en) * 2010-08-02 2013-05-23 L'air Liquide Societe Anonyme Pour L'etude Et L' Exploitation Des Procedes Georges Claude U-tube vaporizer
US9109795B2 (en) * 2010-08-02 2015-08-18 L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude U-tube vaporizer

Also Published As

Publication number Publication date
DE2303681B2 (de) 1976-02-12
DE2303681A1 (de) 1974-08-15
FR2226052A5 (es) 1974-11-08
IT1007006B (it) 1976-10-30
ES422584A1 (es) 1976-05-16
CH563552A5 (es) 1975-06-30
AR202467A1 (es) 1975-06-13
GB1426403A (en) 1976-02-25
JPS49109702A (es) 1974-10-18
BE809698A (fr) 1974-05-02

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