US3576178A - Shell-and-tube steam generator with economizer - Google Patents

Shell-and-tube steam generator with economizer Download PDF

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Publication number
US3576178A
US3576178A US888020A US3576178DA US3576178A US 3576178 A US3576178 A US 3576178A US 888020 A US888020 A US 888020A US 3576178D A US3576178D A US 3576178DA US 3576178 A US3576178 A US 3576178A
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Prior art keywords
liquid
vapor
vapor generator
heating fluid
recited
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Expired - Lifetime
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US888020A
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English (en)
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Paul C Zmola
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Combustion Engineering Inc
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Combustion Engineering Inc
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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
    • F22B1/026—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 tubes between to horizontal tube sheets
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B35/00—Control systems for steam boilers
    • F22B35/004—Control systems for steam generators of nuclear power plants

Definitions

  • ABSTRACT A shell and tube vapor-generator is provided in which vaporizable liquid is transformed into vapor by passing Paul C. Zmola Bloomfield, Conn. [21] Appl. No. 888,020
  • the present invention relates in general to vapor generators of the shelland tube-type wherein vaporizable liquid is transformed into vapor by passing it in heat exchange relation with a heating fluid that is conducted through the tubes.
  • vapor generators of this type it is desirable to preheat feed liquid admitted to the unit to above saturation temperature v prior to passing it to the evaporator section. This is done for two principle reasons. First, it reduces thermal gradients within certain of the component parts of the unit with which the feed liquid comes in contact, thereby reducing the danger of ovcrstressing these elements. And secondly, it causes boiling heat transfer to occur along substantially the full length of the heat exchange surface in the evaporator section thereby resulting in the units operating at greater thermal efficiency.
  • the present invention is directed'toward the solution of the problem of achieving greater thermal efficiencies within vapor generators of the disclosed type without exposing the pressure shell to undue thermal stressing.
  • the invention comprises a novel method of operating a vapor generator of the shelland tube-type in which vaporirable liquid is passed in indirect heat transfer relation with the heating fluid.
  • feedwater Prior to admitting the vaporizable liquid, referred to as feedwater, to the evaporator section of the vapor generator it is heated to about saturation temperature such that evaporation of the liquid will occur substantially immediately upon entrance of the liquid into the evaporator section.
  • the feedwater whose inlet temperature is above that considered to be deleterious to the structural integrity of the pressure shell, is heated entirely by passing it in indirect heat transfer relation with heating fluid that is conducted through the tubes.
  • heating of the feedwater is accomplished entirely by passing it directly in contact with some of the vapor generated in the evaporator section.
  • the feedwater in preheated, in part by the condensation of vapor and in part by the evaporation of heat from the heating fluid.
  • Controls are provided to regulate operation of the vapor generator in order to effect feedwater preheating by the transfer of heat from the heating fluid in amounts proportional to the load on the vapor generator.
  • FIG. 1 is an elevational section' of a vapor generator embodying the present invention
  • FIG. 2 is a schematic representation of the feedwater delivery system for the vapor generator of FIG. 1 and including controls therefor;
  • FIG. 3 is a plot illustrating the relationship between the vapor generator load and the manner by which feedwater preheating is effected.
  • the unit comprises a vertically elongated cylindrical pressure shell 12 closed at its opposite ends by upper and lower domed closure members 14 and 16, respectively.
  • upper and lower transversely extending tube sheets, 18 and 20, respectively, are integrally attached to the shell wall and divide its interior into axially spaced chambers indicated as. heating fluid inlet chamber 22, heating fluid outlet chamber 24-, and vapor-generating chamber 26.
  • a plurality of straight, fluid-conducting heat exchange tubes 28 extend through the vapor-generating chamber 26 between the two tube sheets and communicating with the respective heating fluid inlet and outlet chambers 22 and 24.
  • Heating fluid inlet and outlet nozzles 30 and 32 communicate with the respective inlet and outlet chambers 22 and 24 in order to conduct heating fluid from a source (not shown) through the vapor-generating unit.
  • the wall of the pressure shell 12 is penetrated at three longitudinally spaced points by nozzles 34, 36, and 38.
  • the uppermost nozzle 34 is a vapor outlet nozzle and serves to conduct vapor generated within the shell to a point of use.
  • the other two noules are feedwater inlet nozzles with the lowermost nozzle 36 being the primary feed flownozzle and the nozzle indicated as 38, located between this nozzle and the vapor outlet nozzle, being the secondary feed flow nozzle.
  • the tubes 28 are arranged in a bundle and are surrounded by baffle means concentrically spaced from the wall of the shell to define annular fluid flow passages.
  • baffle means concentrically spaced from the wall of the shell to define annular fluid flow passages.
  • three separate baffles 40, 42, and 44 comprise the baffle means.
  • the first, indicated as 40 extends from a level spaced above the upper surface of the lower tube sheet 20 to a level just above the primary feed flow nozzle 36.
  • the annular passage 46 surrounding this baffle is termed the primary feedwater flow passage.
  • That region of the tube bundle enclosed by the baffle 40 is termed the preheat section and contains a plurality of axially spaced transverse baffle plates 48 that serve to conduct: liquid admitted to this section of the shell in crossflow relation to the tubes 28 that extend through this region of the tube bundle.
  • An annular transverse plate 50 closes the upper end of the passage 46 to prevent the admission of liquid thereto except that which passes through the flow nozzle 36.
  • the second baffle 42 extends from a level just above the transverse plate 50 to a level just above the secondary feed flow nozzle 38.
  • this baffle need extend only far 52 surrounding this bnfile is termed the secondary feed flow I pa ntings: and it surrounds the tube bundle in the evaporator section.
  • the passage 52 in unused to communicate at both its I upper and lower ends with the evaporator section.
  • the opening at the lower end of the passage is intended to conduct the upper tube sheet 18 and the flow passage 56 defined by the baffle communicates with the nozzle 34 and is termed the vapor outlet passage.
  • the passage 56 is closed by annular transverse plate 58.
  • a plurality of axially spaced transverse baffle plates 60 are disposed in the superheat section of the tube bundle and serve to direct vapor admitted to this region in crossflow relation to the tubes 28.
  • the lower areas of the pressure shell 12 and tube sheet 20 especially those areas that are subject to contact by the feedwater admitted through nozzles 36 and 38 may be covered by a thermal shield 61 that is slightly spaced from the surfaces of the respective members. in this way the affected shell parts will be enabled to tolerate contact by lower temperature feedwater than would otherwise be permitted.
  • FIG. 2 The system for delivering feedwater to the vapor generator 10, together with the controls therefor, is shown in FIG. 2.
  • the system comprises two separate supply lines connected between a vaporizable liquid source (not shown) and the respective feedwater inlet nozzles 36 and 38 on the vapor generator.
  • the first line indicated as primary feedline 62, contains a primary feed pump 64 and connects with the primary feedwater inlet noule 36.
  • the second line indicated as secondary feedline 66, contains a feed pump 63 and connects with the feedwater inletnozzle 38.
  • Appropriate flowregulating valve 76 and flowmeter 78 are interposed in the respective feedlines for controlling in conjunction with the controller 30 the rate of flow of feedwater to the respective inlet nozzles.
  • Additional control elements in the form of sensing elements 82 and 84 are employed for sensing load demand on the unit.
  • feedwater is admitted to the vapor generator in accordance with the plot illustrated in FIG. 3.
  • the feedwater controller 80 is effective to cause all of the feedwater admitted to the unit to be supplied by means of the primary feed pump 64 and line 62 to the inlet nozzle 36.
  • the feedwater is discharged into the passage 46 from whence it enters the preheat section of the tube bundle.
  • the liquid is directed by the transverse bafile plateswin crossflo'w'relation to the tubes 28 where the liquid is heated to about saturation temperature by the indirect transfer of heat from the heating fluid conducted through .the tubes.
  • the feedwater controller 80 is effective to cause all of the feedwater admitted to the unit to be supplied by means of the primary feed pump 64 and line 62 to the inlet nozzle 36.
  • the feedwater is discharged into the passage 46 from whence it enters the preheat section of the tube bundle.
  • the liquid is directed by the transverse bafile plateswin crossflo'w'relation to the tubes 28 where the liquid is heated to about saturation temperature by the indirect
  • the feedwater controller 30 is effective to pass all of the feedwater to the vapor generator through line 66 by way of the feed nozzle 38.
  • the liquid is separated by means of spray nozzles or the like into the annular passage 52 where it immediately comes in contact with a portion of the vapor generated in the evaporator section of the tube bundle.
  • This vapor will be drawn into the passage 52 through the space 53 existing between the baffles 42 and 44 by the aspirating effect caused by the condensation of vapor. in the passage. In giving up its heat of vaporization to cooler feed flow the vapor raises the temperature of the feedwater to about saturation temperature at which the establishment of thermal stresses in the shell parts will not occur.
  • the controller 80 operates regulating valve 76 in both of the supply lines 62 and 66 to admit feedwater to the unit through both of the feedwater inlet nozzles 36 and 38.
  • the regulator 76 are operated to pass-proportionately greater amounts of liquid through line 62 to the nozzle 36 and proportionately lesser amounts through line 66.
  • preheated feedwater is caused to enter the tube bundle after being preheated in part by flowing through the preheat section thereof and in part by condensing a portion of the vapor generated in the evaporator section.
  • vapor generators of the disclosed type are operated for the greatest portion of the time in the upper load ranges, or at full load, such that, by means of the herein-described apparatus and method of operation, the principal amount of feedwater preheating that occurs within the unit is done by bypassing the liquid through the preheater section of the tube bundle where its temperature is raised by the indirect transfer of heat from the heating fluid. Only at low loads, and to a minor extent at intermediate loads, must feedwaterpreheating be accomplished by the less efficient manner of condensing a portion of the vapor generated in the evaporator sectionof the tube bundle. The result gives rise to a vapor generator of the shelland tube-type that is considerably more efficient in operation as compared with similar units of the prior art.
  • the method of operating a vapor generator including a vessel containing a bundle ofheat exchange tubes having an evaporator portion comprising the steps of:
  • a vapor generator comprising: a. a vertically elongated pressure vessel; b. axially spaced tube sheets dividing the vessel into heating fluid inlet and outlet chamber and a vapor-generating chamber therebetween; c. a bundle of tubes extending through said vaporgenerating chamber and having their ends communicating with said heating; fluid inlet and outlet chambers for circulation of heating fluid through said tubes; d. means within said vapor-generating chamber defining an evaporator section and a preheat section;
  • baffle means surrounding said tube bundle concentrically spaced relation from the wall of said vessel to form an annular passage therebetween; said flow passage being in fluid communication with said evaporator section at the lower end thereof;
  • means for supplying vaporizable liquid to said vapor generator including:
  • a vapor generator as recited in claim 10 wherein said bafile means is in open fluid communication with said evaporator section at the top and bottom ends thereof and the opening at the top of the said baffle means is effective to admit vapor from said evaporator section to said flow passage while that at the bottom admits heated liquid to said evaporator section.
  • a vapor generator as recited in claim 10 including control means for regulating the supply of vaporizable liquid through said first and second supply means in response to changes in the temperature of the liquid being passed.
  • said control means includes means for passing all of the liquid supplied to said vapor generator through said first supply means during low load operation of said vapor generator, means for passing all of the liquid supplied to said vapor generator through said first supply means during high load operation of said vapor generator, and means for passing liquid through both of said supply means in controlled amounts during intermediate load operation of said vapor generator.
  • a vapor generator as recited in claim 16 including means defining a superheat section in said vapor-generating chamber disposed above said evaporator section and said means including means for directing the flowing fluid in crossflow relation to the tubes extending therethrough.

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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)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
US888020A 1969-12-24 1969-12-24 Shell-and-tube steam generator with economizer Expired - Lifetime US3576178A (en)

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US88802069A 1969-12-24 1969-12-24

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US (1) US3576178A (es)
CH (1) CH518489A (es)
DE (1) DE2054577A1 (es)
ES (1) ES386826A1 (es)
FR (1) FR2072053A1 (es)
GB (1) GB1315140A (es)
SE (1) SE360728B (es)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3724532A (en) * 1970-03-02 1973-04-03 Babcock & Wilcox Co Once-through vapor generator
US3797566A (en) * 1973-04-13 1974-03-19 Fives Lille Cail Heat exchanger
US3923007A (en) * 1972-12-19 1975-12-02 Siemens Ag Emergency water-cooling system for a steam generator for a pressurized-water coolant nuclear reactor
WO1981002112A1 (en) * 1980-01-24 1981-08-06 Rintekno Oy Method for the vaporization of liquid and apparatus for carrying out the method
US5588400A (en) * 1993-02-09 1996-12-31 L. & C. Steinmuller Gmbh Method of generating steam in a forced-through-flow boiler
US20110139094A1 (en) * 2008-06-12 2011-06-16 Brueckner Jan Method for operating a continuous flow steam generator
US10803997B2 (en) * 2010-09-27 2020-10-13 Bwxt Mpower, Inc. Compact nuclear reactor with integral steam generator

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3811498A (en) * 1972-04-27 1974-05-21 Babcock & Wilcox Co Industrial technique
DE2642800C2 (de) * 1976-09-23 1982-12-09 Deggendorfer Werft Und Eisenbau Gmbh, 8360 Deggendorf Rohrbodenanschluß für Rohrbündel-Reaktoren oder Rohrbündel-Wärmeaustauscher
DE2813614C2 (de) * 1978-03-30 1982-06-03 Helmut 7100 Heilbronn Bälz Indirekt beheizter Dampferzeuger

Citations (2)

* 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
US3385268A (en) * 1965-01-18 1968-05-28 Babcock & Wilcox Co Method of operating a once-through vapor generator

Patent Citations (2)

* 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
US3385268A (en) * 1965-01-18 1968-05-28 Babcock & Wilcox Co Method of operating a once-through vapor generator

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3724532A (en) * 1970-03-02 1973-04-03 Babcock & Wilcox Co Once-through vapor generator
US3923007A (en) * 1972-12-19 1975-12-02 Siemens Ag Emergency water-cooling system for a steam generator for a pressurized-water coolant nuclear reactor
US3797566A (en) * 1973-04-13 1974-03-19 Fives Lille Cail Heat exchanger
WO1981002112A1 (en) * 1980-01-24 1981-08-06 Rintekno Oy Method for the vaporization of liquid and apparatus for carrying out the method
US4422899A (en) * 1980-01-24 1983-12-27 Rintekno Oy Apparatus and method for the vaporization of liquid
US5588400A (en) * 1993-02-09 1996-12-31 L. & C. Steinmuller Gmbh Method of generating steam in a forced-through-flow boiler
US20110139094A1 (en) * 2008-06-12 2011-06-16 Brueckner Jan Method for operating a continuous flow steam generator
US9291345B2 (en) * 2008-06-12 2016-03-22 Siemens Aktiengesellschaft Method for operating a continuous flow steam generator
US10803997B2 (en) * 2010-09-27 2020-10-13 Bwxt Mpower, Inc. Compact nuclear reactor with integral steam generator

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Publication number Publication date
GB1315140A (en) 1973-04-26
DE2054577A1 (de) 1971-07-22
ES386826A1 (es) 1974-08-16
FR2072053A1 (es) 1971-09-24
CH518489A (de) 1972-01-31
SE360728B (es) 1973-10-01

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