US3195517A - Stable forced circulation boilers - Google Patents

Stable forced circulation boilers Download PDF

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Publication number
US3195517A
US3195517A US276048A US27604863A US3195517A US 3195517 A US3195517 A US 3195517A US 276048 A US276048 A US 276048A US 27604863 A US27604863 A US 27604863A US 3195517 A US3195517 A US 3195517A
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United States
Prior art keywords
downcomer
section
tubes
riser tubes
vapor
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Expired - Lifetime
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US276048A
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English (en)
Inventor
Bell Alan
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Foster Wheeler Inc
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Foster Wheeler Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B29/00—Steam boilers of forced-flow type
    • F22B29/02—Steam boilers of forced-flow type of forced-circulation type
    • 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
    • F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
    • F22B1/1823—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines for gas-cooled nuclear reactors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/02—Feed-water heaters, i.e. economisers or like preheaters with water tubes arranged in the boiler furnace, fire tubes, or flue ways

Definitions

  • This invention relates to forced circulation boilers.
  • water and steam are used herein to include any suitable liquid and its vapour unless the context otherwise requires.
  • the forced circulation boiler has the advantage over the natural circulation boiler of being of substantially lower weight and, consequently, cost. This arises largely out of the necessity, in a natural circulation boiler, of maintaining the pressure drop due to fiow through the tubes of the system as low as possible which involves the use of tubes of relatively large diameter defining fluid paths devoid of substantial or abrupt changes of direction.
  • a high pressure drop can be tolerated because although it leads to the provision of relatively high pumping power, there is the compensating advantage that the tubes can be of small diameter and follow almost any path. This can lead to a substanrtial saving in weight and cost and to valuable flexibility in design and consequent saving of space.
  • the forced circulation system has the further advantage over the natural circulation system that it involves a smaller number of piercings of that vessel.
  • the invention is concerned with eradicating or minimising the above mentioned disadvantages of the forced circulation boiler and, in general terms, consists in introducing at the evaporating stage of a forced circulation boiler a natural circulation akin to that which occurs in the tubes of a natural circulation boiler.
  • the forced circulation boiler in accordance with the invention has a tubular evaporating section leading to a tubular superheating section and there is provided between the two sections a collecting chamber for the steam and water mixture produced in the evaporating section and in which water is allowed or caused to separate and to be recirculated by natural circulation to and through the evaporating section while the steam passes to the superheating section.
  • At least one downcomer needs to be provided which connects the collecting chamber to the inlet of the evaporating section, and the heat transfer to which is substantially lower than that to the risers or evaporating tubes.
  • This can be achieved by arranging one or more downcomers outside the casing of the generator but in the preferred form of the invention, a single downcomer is used which is disposed along the axis of a bundle of steam generating tubes and insulated from the heating fluid.
  • the insulation is preferably ensured by providing the downcomer with a jacket filled with a fluid of low heat conductivity such as CO which, in the case in which such a gas is used as the heating fluid, may be a quantity of that gas which is trapped in an open-ended jacket.
  • the evaporating and superheating sections are formed of tubes terminating in tube plates, the outlet tube-plate of the evaporating section and the inlet tube-plate of the superheating section being joined by a cylindrical casing which defines the said chamber.
  • the effectiveness of the separation in the collecting chamber can be enhanced by the provision therein of a battle against which a major part of the steam and water mixture must impinge on entering the chamber.
  • a baflic can usefully be shaped so that it also serves to collect separated Water and deliver it to the downcomer.
  • FIGURE 1 is a sectional elevation of the tube system of the boiler.
  • FIGURE 2 is an enlarged view of the middle portion of the system shown in FIGURE 1 and illustrating in a greater detail the arrangement of the downcomer;
  • FIGURES 3 and 4 are sections taken on the lines lli-lll and lV-IV respectively on FTGURE l.
  • the tube system shown in the drawings can be assumed to have a length of about 25 feet and be arranged vertically within a shell or casing (not shown) side-by-side with a large number of identical tube systems.
  • the system provides a water preheating or economiser section B, an evaporating or steam generating section EV and a superheating section S connected together in series.
  • Each of the three sections comprises a bundle of straight tubes 10, i2, 14 connected respectively to inlet and outlet tube plates 16, 17; 18, 19; 20, 21.
  • the outlet tube plates of the economiser and evaporating sections are joined by short cylinders 2-2, 24 respectively to the inlet tube plates of the evaporating and superheating sections, the tube plates and cylinders defining collecting spaces or chambers 26, 28.
  • the inlet tube plate 16 of the economiser section has welded to it an adapter 30 through which the water to be evaporated is supplied at say the moderate pressure of 400800 p.s.i. g.
  • the outlet tube plate 21 of the superheater section has welded to it a similar adapter 32 forming the superheated steam outlet.
  • the heating fluid which can be assumed to be the CO coolant of a gas cooled nuclear reactor flows through the casing (not shown) countercurrent to the water flowing through the tubes and heats the water or the steam produced therefrom in the tube bundles l0, l2, 14 by indirect heat exchange.
  • the economiser bundle is made up of nineteen tubesa number which is very favourable to optimum utilisation of available space.
  • the evaporator bundle 12 (shown in greater detailin' FIG. 2) is similarly formed except that the central tube "4
  • the complete steam generator . will comprise a number of tube systems such as that illustrated in. the drawings arranged side by sidein a shell 34 is.not a riser as are the othereighteen tubes but a downcomer aswill be explained in greater detail further on. p
  • the superheater bundle 14 is substantially the same as the economiser bundle.
  • the water is heated in the economiser section 10 to or. near its saturation temperature and 'is passed thence upwards through the risers of the evaporating section 12 to emerge therefrom into thecollecting chamber 28 as a. mixture of steam and water, In the normal forcedcirculation boiler, this mixture would be passed directly to the superheater section. 14, and it is this, I believe, which leads'to the unsatisfactory performance referred to above as being characteristic of such boilers.
  • the chamber 28 is made sulficiently large to ensure that there will be a substantial sep-' aration of water from steam in it. For this purpose, it does not have to be particularly large.
  • V chamber 28 is in noway comparable for size with the steam and water drum of the conventional natural cir-"' culation boiler.
  • bafiie 36 is provided against which a major part of the mixture emerging from the evaporator tubes is caused to impinge.
  • this baffle is in the form of a The collecting dish in which separated water can collect and be guided:
  • the downcomer In order that the downcomer may act assuch, it must be designed disposed or arranged so that the heat transfer to it is substantially lower than is that to the remaining riser tubes of the evaporator.
  • the drawingsgitis provided over the greaterfpart of its In the Case illustrated'fin' length by a jacket 38 which if filled With a fluid of low conductivity, will form a: veryeifective barrier to the passage of heat to the downcomer even if the annular space defined by the jacket is very restricted indeed-say a small fraction of an inch;
  • the drawingsgitis provided over the greaterfpart of its In the Case illustrated'fin' length by a jacket 38 which if filled With a fluid of low conductivity, will form a: veryeifective barrier to the passage of heat to the downcomer even if the annular space defined by the jacket is very restricted indeed-say a small fraction of an inch;
  • the drawingsgitis provided over the greaterfpart of its In the Case illustrated'fin' length by a jacket 38 which
  • jacket is open at one end with the consequence that it will become filled with the carbon dioxide assumed here to be the heating fluid and which has indeed a low thermal conductivity and, when trapped in the jacket, functions or casing. It is. advantageous to utilise the space within .the casing to the utmost and to distribute the various tubes uniformly over the'crosssection of the casing.
  • the 19-tube bundles of hexagonal cross-section shown in FIGS. 3and 4 are very suitable for achieving these objects.
  • the invention is not restricted to any particular formation of tube bundles.
  • the superheater tubes may be arranged so as to provide within the superheater. section a sub-section.
  • said superheating section including a cir-
  • a forced circulation boiler including 'an 'economizer section, an inlet header for very efficiently as an insulator:
  • the risers may be given an'extended heat transfer surface as by the provision ofv fins.
  • the steam which is received by the superheater will have a substantially lowered water con'- tent and the quality of thesteam which emerges from the superheater outlet 32 will not only be high but will be very uniform as in the case of'the conventional natural circulation boiler.
  • the economizer section including a plurality of tubes extending to said avapor generating section inlet header wherebyt'ne ec'on'omizer section is in series flowwith'said vapor generating section.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
US276048A 1962-04-30 1963-04-26 Stable forced circulation boilers Expired - Lifetime US3195517A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB16516/62A GB1037415A (en) 1962-04-30 1962-04-30 Forced flow once-through boilers

Publications (1)

Publication Number Publication Date
US3195517A true US3195517A (en) 1965-07-20

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US276048A Expired - Lifetime US3195517A (en) 1962-04-30 1963-04-26 Stable forced circulation boilers

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US (1) US3195517A (US20100012521A1-20100121-C00001.png)
BE (1) BE631749A (US20100012521A1-20100121-C00001.png)
CH (1) CH395141A (US20100012521A1-20100121-C00001.png)
GB (1) GB1037415A (US20100012521A1-20100121-C00001.png)
NL (1) NL292094A (US20100012521A1-20100121-C00001.png)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3357409A (en) * 1964-10-07 1967-12-12 Atomic Energy Authority Uk Vertical tube module once-through steam generator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1281453B (de) * 1964-10-07 1968-10-31 Atomic Energy Authority Uk Dampferzeuger

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2240100A (en) * 1935-07-17 1941-04-29 Schmidt Martin Water tube steam generator and parts thereof
US2265481A (en) * 1938-01-17 1941-12-09 Hartmann Otto Heavy duty high pressure drumless boiler
FR1243428A (fr) * 1959-08-12 1960-10-14 Procédé d'aménagement d'installation ou de cellule d'échangeur pour la production de vapeur, cellules, installations et pièces de jonction pour faisceaux tubulaires en comportant application
US2983260A (en) * 1956-12-17 1961-05-09 Huet Andre Thermal heat exchange installation
US3116721A (en) * 1961-02-17 1964-01-07 Huet Andre Water and steam separators for evaporators

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2240100A (en) * 1935-07-17 1941-04-29 Schmidt Martin Water tube steam generator and parts thereof
US2265481A (en) * 1938-01-17 1941-12-09 Hartmann Otto Heavy duty high pressure drumless boiler
US2983260A (en) * 1956-12-17 1961-05-09 Huet Andre Thermal heat exchange installation
FR1243428A (fr) * 1959-08-12 1960-10-14 Procédé d'aménagement d'installation ou de cellule d'échangeur pour la production de vapeur, cellules, installations et pièces de jonction pour faisceaux tubulaires en comportant application
US3116721A (en) * 1961-02-17 1964-01-07 Huet Andre Water and steam separators for evaporators

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3357409A (en) * 1964-10-07 1967-12-12 Atomic Energy Authority Uk Vertical tube module once-through steam generator

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NL292094A (US20100012521A1-20100121-C00001.png)
CH395141A (fr) 1965-07-15
GB1037415A (en) 1966-07-27
BE631749A (US20100012521A1-20100121-C00001.png)

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