US3242911A - Apparatus and method for operating a vapor generator at subcritical and supercritical pressures - Google Patents

Apparatus and method for operating a vapor generator at subcritical and supercritical pressures Download PDF

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Publication number
US3242911A
US3242911A US332684A US33268463A US3242911A US 3242911 A US3242911 A US 3242911A US 332684 A US332684 A US 332684A US 33268463 A US33268463 A US 33268463A US 3242911 A US3242911 A US 3242911A
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United States
Prior art keywords
separating
conduit
flow
mixing vessel
operating
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Expired - Lifetime
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US332684A
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English (en)
Inventor
Willburt W Schroedter
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Combustion Engineering Inc
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Combustion Engineering Inc
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Application filed by Combustion Engineering Inc filed Critical Combustion Engineering Inc
Priority to US332684A priority Critical patent/US3242911A/en
Priority to GB50892/64A priority patent/GB1028509A/en
Priority to CH1636264A priority patent/CH458397A/de
Priority to BE657419D priority patent/BE657419A/xx
Priority to FR999419A priority patent/FR1417900A/fr
Priority to NL6414894A priority patent/NL6414894A/xx
Priority to ES0307429A priority patent/ES307429A1/es
Application granted granted Critical
Publication of US3242911A publication Critical patent/US3242911A/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
    • F22B29/00—Steam boilers of forced-flow type
    • F22B29/06—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes
    • F22B29/12—Steam boilers of forced-flow type of once-through type, i.e. built-up from tubes receiving water at one end and delivering superheated steam at the other end of the tubes operating with superimposed recirculation during starting and low-load periods, e.g. composite boilers
    • 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
    • F22B29/023—Steam boilers of forced-flow type of forced-circulation type without drums, i.e. without hot water storage in the boiler
    • F22B29/026—Steam boilers of forced-flow type of forced-circulation type without drums, i.e. without hot water storage in the boiler operating at critical or supercritical pressure

Definitions

  • the critical temperature of a gas is generally defined as the temperature at which the gas may just be liquified at its critical pressure. For water or water vapor this pressure is 3206.3 p.s.i.a. (pounds per square inch absolute) at the critical temperature of 705.34 P.
  • This pressure is 3206.3 p.s.i.a. (pounds per square inch absolute) at the critical temperature of 705.34 P.
  • saturation temperature When heating water at a pressure below the critical pressure it passes from the liquid state to the vapor state at a constant temperature the so-called saturation temperature. A certain amount of heat is required to change the water from the liquid state to the vapor state. This heat quantity is called heat of evaporation. It decreases with an increase in pressure and becomes zero at the critical pressure.
  • a further object of the invention is to accomplish the above with a minimum of capital investment for additional apparatus such as valves, piping, separators, etc.
  • FIG. 1 is a diagrammatic representation of a vapor generator organized for both supercritical and subcritical pressure operation
  • FIG. 2 depicts a vapor generating plant including a modified once-through vapor generator operating at supercritical pressure, which generator when at subcritical pressure will operate as a controlled circulation vapor generator;
  • FIG. 3 depicts a vapor generating plant including a once-through vapor generator operating at super-critical 3,242,911 Patented Mar. 29, 1966 pressure, which generator when at subcritical pressure will operate as a natural circulation vapor generator;
  • FIG. 4 is a diagrammatic representation of a threeway valve when in the position for supercritical operation.
  • FIG. 5 when in the position for subcritical operation.
  • FIG. 1 the illustrative embodiment of the invention depicted in FIG. 1 includes a vapor generator designated generally as 10, and comprising in the flow path of the working medium a preheating zone 12, a conduit 13, a separating and mixing zone 14, a conduit 15-, a recirculating pump 16, a radiant heating zone 18, a conduit 19, a three-way valve 20 and a superheating zone 21.
  • Fuel and air for burning is discharged into the vapor generator by way of burner 22 and air duct 24, respectively.
  • a through-flow quantity of the working fluid passes through the preheating zone 12 into the separating and mixing zone 14.
  • a relatively small recirculated portion of the working fluid having been returned from the outlet of the radiant heating zone 18 by way of conduit 26 is mixed with the through-flow quantity to form a total quantity.
  • This total quantity then passes through the radiant heating zone 18, with the through-flow quantity continuing through conduit 19 and three-way valve 20 into superheating zone 21, while the above-mentioned recirculated portion by means of pump 16 and conduit 26 is returned to the separating and mixing zone 14.
  • the three-way valve 20 occupies the position shown in FIG. 4 with the through-flow quantity passing therethrough in the direction indicated by the arrow.
  • valve 20 When operating the vapor generator at subcritical pres sure such as at low loads, and with a controlled circulation flow pattern the through-flow quantity of the working fluid passes through the preheating zone 12 into the separating and mixing zone 14, wherein it is mixed with a relatively large recirculated portion returned from the outlet of the radiant heating zone 18 by way of conduit 26. The total quantity then passes through the radiant heating zone 18 for the generation of steam at constant temperature. The resultant mixture of steam and water is then returned to the separating and mixing zone 14 wherein apparatus is provided for separating the steam from the water. The water again then passes through the radiant heating zone 18 and the steam flows to the superheater zone 21 via conduit 28, three-way valve 20 and the downstream portion of conduit 19.
  • valve 20 occupies the position shown in FIG. 5 with the through-flow quantity passing therethrough in the direction indicated by the arrow.
  • FIG. 1 shows the basic idea of the invention in a simplified and diagrammatic form
  • FIGS. 2 and 3 illustrate two applications thereof in a more detailed and specified manner.
  • feedwater is taken from the condenser 30 and is delivered under pressure into economizer 12a by way of conduit 32 and feed pump 33.
  • Economizer 12a corresponds to the preheating zone 12 of FIG. 1.
  • the preheated water is then delivered to drum 14a wherein the feedwater is mixed with a recirculated portion of the working fluid returned from the furnace tubes 18a.
  • Drum 14a and tubes 18a correspond to the separating and mixing zone 14 and radiant heating zone 18 of FIG. 1, respectively.
  • valve 34 When operating at supercritical .pressure the throughflow quantity of the working fluid is delivered directly from furnace tubes 18a to superheater 21a by way of conduit 19a and valve 34. Conduit 19a and superheater 21a correspond to conduit 19 and superheater 21 of FIG. 1, respectively. A second valve 35 provided in conduit 28a is closed during supercritical pressure operation.
  • valve 34 performs one of the two functions of the three-way valve 20 of FIG. 1, namely that of controlling the flow from radiant heating zone 18 to superheating zone 21, and valve 35 performs the other function, namely that of controlling the flow from vessel 14a to superheater 21a.
  • the steam at supercritical pressure is conducted to one or more steam turbine generators 36, with the steam subsequently being condensed in condenser 30, thereby returning to the beginning of the cycle.
  • the steam power plant illustrated by FIG. 2 and as hereinabove described as operating in the supercritical pressure range includes a steam generator of the modified once-through flow type also generally known as a combined circulation steam generator.
  • the feature which distinguishes the combined circulation steam generator from the throughflow steam generator is the provision for recycling of a small fraction of the working fluid from the outlet of the radiant zone 14 to the inlet thereof (see conduit 26 of FIG. 1 or 26a of FIG. 2).
  • This recycling of the working fluid serves the purpose of controllably maintaining a minimum velocity of the working medium passing through the furnace tubes for the purpose of satisfactorily protecting these tubes, with this velocity being independent of the through-flow quantity dictated by steam generator load.
  • the flow pattern of the working fluid is changed to the flow pattern of a controlled steam generator which requires a steam and water drum for separation of the steam from the water.
  • a steam and water drum for separation of the steam from the water.
  • the mixing vessel 1411 now also serves the purpose of the steam and water drum which is required when operating the steam generator at a subcritical pressure.
  • the flow path of the working fluid when operating in the subcritical pressure range is therefore as follows:
  • This combined water quantity then flows to the furnace tubes 18a by way of conduit 15a and recirculating pump 16a. While passing through furnace tubes 18a a portion of the water is evaporated to steam with the water and steam mixture being discharged into the steam and water drum 14a by way of conduit 26a, and with valve 34 in conduit 19a being closed.
  • Conventional equipment is provided in steam and water drum 14a for the separation of the steam from the Water.
  • An amount of steam equal to the through-flow quantity then flows from vessel 14a to the superheater 21a by way of conduit 28a and valve 35 which valve is now in the open position. Having been heated in superheater 21a to the desired steam temperature the steam is then conducted to steam turbine generator 36 and is subsequently condensed in condenser 30 thereby completing the steam cycle.
  • FIG. 3 the invention is applied to a straight throughflow steam generator when operating at top load in the supercritical pressure range. However when operating in the subcritical pressure range at low loads this steam generator is operating in the manner of a natural circulation boiler.
  • the steam and water When operating the steam generator illustrated in FIG. 3 at lower loads and in the subcritical pressure range, the steam and water circulates and flows in the manner of a natural circulation boiler. Accordingly, the feedwater passes from economizer 12b into drum 14b, where it is mixed with a relatively large quantity of recirculated water which is returned fromthe outlet of the furnace tubes 18b.
  • This mixture in conduit 15b possesses a greater density than the density of the mixture of steam and water rising in the furnace tubes 18b, and accordingly flows to the inlet of these tubes by way of duct 15b.
  • a portion of the water is evaporated to steam while passing through tubes 18b.
  • the water and steam mixture thus produced is returned to drum 14b by way of conduit 26b with valve 40 being open and valve 34 in conduit 1% being closed.
  • Conventional apparatus provided in drum 14b serves to separate the steam from the water.
  • the steam then passes through conduit 28b, valve 35, through superheater 21b and to turbine 36.
  • the water separated from the steam returns to the in
  • first conduit means for passing only a quantity of said Working fluid that is equal to said through flow quantity from said radiant heating means to said superheating means;
  • valve means in said first conduit means and in said second conduit means
  • valve means a first position of said valve means whereby when operating at supercritical pressure said valve means ing fluid through said preheating means, said fluid separating and mixing vessel and said radiant heating means in the order named;
  • valve means are means are closed for preventing flow through said opened for passage of said through-flow quantity first conduit means, and are opened for passage of through said first conduit, and said valve means are said through-flow quantity through said second con- Closed for Preventing flow through Said Second duit means and said separating and mixing vessel conduit and said separating and mix ng vessel funcfunctions as a separating device.
  • t ns as a miXing device
  • the combination comtrolled ir i W Said first valve means are prising: closed for preventing flow through said first cona working fluid preheating means; d-uit, and said valve means are opened for passage a fluid separating and mixing vessel; of said through-low quantity through said second a working fluid radiant heating means; conduit and said separating and mixing vessel funca working fluid superheating means; tions additionally as a separating device.
  • a feed pump for passing a through-flow quantity of the first conduit means for passing only a quantity of said Working fluid through Said economilfil, Said fluid working fluid th t i equal to id throu h fl separating and mixing vessel and said furnace heating quantity from said radiant heating means to said Surface/in the Order named;
  • recirculating means including a recirculating pump for second conduit means for passing only a quantity that Passing an additional q y of Said Working fluid is equal to said through-flow quantity from said through Said Separating mixing Vessel and Said separating and mixing vessel to said superheating fflmacil heating Surface and for returning Said addimeans; tional quantity to said separating and mixing vessel; first valve means in said first conduit means; a first Conduit for Passing only a q y of said Worksecond valve means in said second conduit means; ing fluid that is equal Said through-flow q y whereby when operating at supercritical pressure said from Said furnace heating surface to Said p first valve means are opened for passage of said mater;

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
US332684A 1963-12-23 1963-12-23 Apparatus and method for operating a vapor generator at subcritical and supercritical pressures Expired - Lifetime US3242911A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US332684A US3242911A (en) 1963-12-23 1963-12-23 Apparatus and method for operating a vapor generator at subcritical and supercritical pressures
GB50892/64A GB1028509A (en) 1963-12-23 1964-12-14 Apparatus and method for operating a vapor generator at subcritical and supercritical pressures
CH1636264A CH458397A (de) 1963-12-23 1964-12-18 Zwangsdurchlauf-Dampferzeuger zum Betrieb mit überkritischem oder unterkritischem Druck
BE657419D BE657419A (xx) 1963-12-23 1964-12-21
FR999419A FR1417900A (fr) 1963-12-23 1964-12-21 Générateur de vapeur à pression supercritique ou subcritique, à circulation ouverte, ou contrôlée, ou naturelle
NL6414894A NL6414894A (xx) 1963-12-23 1964-12-21
ES0307429A ES307429A1 (es) 1963-12-23 1964-12-22 Un aparato generador de vapor.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US332684A US3242911A (en) 1963-12-23 1963-12-23 Apparatus and method for operating a vapor generator at subcritical and supercritical pressures

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US3242911A true US3242911A (en) 1966-03-29

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US (1) US3242911A (xx)
BE (1) BE657419A (xx)
CH (1) CH458397A (xx)
ES (1) ES307429A1 (xx)
GB (1) GB1028509A (xx)
NL (1) NL6414894A (xx)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3467067A (en) * 1967-12-27 1969-09-16 Combustion Eng Recirculating type once-through steam generator
US3478726A (en) * 1967-05-23 1969-11-18 Sulzer Ag Apparatus for regulating the recirculation of working medium in a once-through force-flow steam generator
US3559626A (en) * 1969-01-03 1971-02-02 Douglas R Paxton Apparatus and process for accumulating and concentrating heat energy
US20070245731A1 (en) * 2005-10-05 2007-10-25 Tas Ltd. Advanced power recovery and energy conversion systems and methods of using same
US20120067551A1 (en) * 2010-09-20 2012-03-22 California Institute Of Technology Thermal energy storage using supercritical fluids

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2989038A (en) * 1956-04-26 1961-06-20 Duerrwerke Ag Device for starting-up once-through boilers
US3038453A (en) * 1957-02-07 1962-06-12 Combustion Eng Apparatus and method for controlling a forced flow once-through steam generator
US3046956A (en) * 1959-06-03 1962-07-31 Kuljian Corp Pumpless liquid heater and translator
US3135243A (en) * 1961-07-27 1964-06-02 Combustion Eng Furnace wall arrangement

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2989038A (en) * 1956-04-26 1961-06-20 Duerrwerke Ag Device for starting-up once-through boilers
US3038453A (en) * 1957-02-07 1962-06-12 Combustion Eng Apparatus and method for controlling a forced flow once-through steam generator
US3046956A (en) * 1959-06-03 1962-07-31 Kuljian Corp Pumpless liquid heater and translator
US3135243A (en) * 1961-07-27 1964-06-02 Combustion Eng Furnace wall arrangement

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3478726A (en) * 1967-05-23 1969-11-18 Sulzer Ag Apparatus for regulating the recirculation of working medium in a once-through force-flow steam generator
US3467067A (en) * 1967-12-27 1969-09-16 Combustion Eng Recirculating type once-through steam generator
US3559626A (en) * 1969-01-03 1971-02-02 Douglas R Paxton Apparatus and process for accumulating and concentrating heat energy
US20070245731A1 (en) * 2005-10-05 2007-10-25 Tas Ltd. Advanced power recovery and energy conversion systems and methods of using same
US7827791B2 (en) * 2005-10-05 2010-11-09 Tas, Ltd. Advanced power recovery and energy conversion systems and methods of using same
US20120067551A1 (en) * 2010-09-20 2012-03-22 California Institute Of Technology Thermal energy storage using supercritical fluids

Also Published As

Publication number Publication date
GB1028509A (en) 1966-05-04
BE657419A (xx) 1965-06-21
NL6414894A (xx) 1965-06-24
ES307429A1 (es) 1965-05-16
CH458397A (de) 1968-06-30

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