US3426734A - Vapor generator having gas recirculation system using gas ejector - Google Patents

Vapor generator having gas recirculation system using gas ejector Download PDF

Info

Publication number
US3426734A
US3426734A US604203A US3426734DA US3426734A US 3426734 A US3426734 A US 3426734A US 604203 A US604203 A US 604203A US 3426734D A US3426734D A US 3426734DA US 3426734 A US3426734 A US 3426734A
Authority
US
United States
Prior art keywords
gas
furnace
vapor
gases
recirculation
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
Application number
US604203A
Other languages
English (en)
Inventor
Earl K Rickard
Orlando Martinez Jr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Combustion Engineering Inc
Original Assignee
Combustion Engineering Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Combustion Engineering Inc filed Critical Combustion Engineering Inc
Application granted granted Critical
Publication of US3426734A publication Critical patent/US3426734A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G5/00—Controlling superheat temperature
    • F22G5/06—Controlling superheat temperature by recirculating flue gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G5/00—Controlling superheat temperature
    • F22G5/04—Controlling superheat temperature by regulating flue gas flow, e.g. by proportioning or diverting

Definitions

  • a gas recirculation system for a vapor generator having a combustion gas pump in the form of a gas ejector for inducing recirculating flow of combustion gases from the convection heating section of the vapor generator to the furnace.
  • the invention relates to a vapor generating unit, and particularly to means for effecting the recirculation of combustion gases thereinv
  • a vapor generating unit In the generation of vapor for producing electricity by means of a turbine, it is necessary to proportion the heat generated by combustion gases in the furnace between the evaporating surface and vapor heating surface since the distribution of heat determines the quantity of vapor generated and the superheat and reheat vapor temperatures.
  • One of the methods employed for distributing heat within a vapor generator involves the recirculation of combustion gases back into the furnace after it is passed in heat exchange relation with heating surface in the gas flow passage.
  • gas recirculation has been effected by means of a recirculating fan disposed to operate in a conduit connected between the point of withdrawal of the combustion gases from the gas passage and the point of readmission of the gases to the furnace.
  • a fan in a gas recirculation system has several manifest disadvantages. It is a large, cumbersome piece of equipment requiring a considerable amount of floor space for mounting. Oftentimes, sizing of the vapor generator and recirculating fan is such as to prevent the latters containment Within the vapor generator support columns thereby requiring additional building volume to house the apparatus.
  • the fan is a device that employs moving parts and, due to the relatively high gas temperature and volume, it must be capable of handling, it is an expensive apparatus that is subject to increased Wear and deterioration thereby requiring downtime for maintenance which adds to its expense.
  • a recirculating fan is also subject to fouling by excessive ash or sediment contained in the combustion gas on which it operates.
  • a dust collector as an ancillary piece of equipment to remove such ash and sediment from the gas stream prior to its admission to the fan.
  • Use of a dust collector adds both to the over-all expense of the unit and to the amount of draft loss experienced by the gases which concomitantly increases the pump power necessary to effect their circulation.
  • limits are imposed on the temperature of the gases to be handled by a recirculating fan since the use of high temperature metals in its construction to enable it to Withstand high gas temperatures would render its use economically unfeasible. It is therefore necessary, where gas recirculation is employed in units having extremely high combustion gas temperatures to insure that as much heat as possible is removed from the gases before they are admitted to the fan. This requires that the gases to be recirculated be withdrawn from the unit after they have been passed in heat exchange relation with all of the heating surface in the convection heating section.
  • the recirculated gas Since the recirculated gas must pass in heat exchange relation with all of the heating surface, its effectiveness as vapor temperature controlling means is reduced. Firstly, because the gases transfer heat to the economizer before being withdrawn from the convection heating section alteration of the recirculated gas flow, in addition to changing the vapor heating characteristics of the superheater and reheater, will also change the amount of vapor that is produced thereby disrupting the vapor temperature control function. Additional control apparatus rnust therefore be provided to rectify this situation.
  • the recirculation fan normally employed in gas recirculation systems is replaced by a combustion gas pump in the form of a gas ejector comprising a convergent-divergent nozzle, disposed in the recirculation gas conduit adjacent its connection with the convection heating section of the vapor generator and an air jet for passing air at high velocities through the nozzle.
  • a combustion gas pump in the form of a gas ejector comprising a convergent-divergent nozzle, disposed in the recirculation gas conduit adjacent its connection with the convection heating section of the vapor generator and an air jet for passing air at high velocities through the nozzle.
  • a gas ejector requires only simple ductwork that can easily be contained within the vapor generator support columns so that no additional building structure is required to contain the apparatus. It has no moving parts and is therefore subject to less wear and maintenance requirements.
  • FIGURE 1 is a somewhat schematic representation of a vapor generator adapted for use of the present invention.
  • FIGURE 2 is a partial side elevation of the vapor generator of FIGURE 1.
  • the numeral 10 indicates a vapor generator incorporating the present invention.
  • the vapor generator 10 comprises tubular walls defining a vertically elongated furnace 12 having a heating gas outlet 14 located at the upper end of the furnace and a rear gas pass 16 extending vertically downwardly and spaced from the furnace.
  • the rear gas pass 16 is connected to the gas out let 14 of the furnace by a horizontal gas pass 18.
  • Fuel burners 20 are disposed in a lower portion of the furnace 12 for generating combustion gases that flow upwardly, through the gas outlet 14 and thence through the horizontal and rear gas passes 16 and 18 to a stack (not shown). In flowing from the furnace 12 the combustion gases pass through a convection heating section that includes the horizontal and rear gas passes 16 and 18.
  • tubular heating surface that is heated largely by the convection heating characteristics of the combustion gases.
  • the horizontal gas pass 18 is located the high temperature superheater 22 and high temperature reheater 24.
  • Low temperature superheater 26, low temperature reheater 28, and economizer 30 are disposed in the rear gas pass 16.
  • An ash hopper 32 may be disposed at the end of the rear gas pass for discharging ash from the gas stream leaving the unit.
  • a gas recirculation system for withdrawing combustion gases from the convection heating section and for reintroducing them into the furnace 12 includes ductwork connected between the rear gas pass 16 and the furnace.
  • the ductwork comprises a vertical conduit 34 disposed in the space 36 between the furnace 12 and the rear gas pass 16. At its bottom end the conduit 34 connects with the bottom of the furnace 12 by means of a horizontal connector 38 that communicates with the furnace through openings 40 formed by spaces between adjacent furnace wall tubes.
  • An ash hopper 42 located at the bottom of conduit 34 is effective to remove some of the ash entrained in the recirculated gases before it is admitted to the furnace.
  • conduit 34 communicates by means of a manifold connector 45 with a plurality of conduit branches 44 that communicate with the convection heating section through connectors 46 connected to aligned openings 48 in the wall of the rear gas pass 16.
  • a combustion gas pump in the form of a gas ejector for withdrawing a portion of the combustion gases flowing through the rear gas pass and for passing them through the conduit 34.
  • the gas ejector comprises a convergent-divergent nozzle 50 contained within each branch 44 and an air jet nozzle 52 connected to a source of compressed air (not shown) for discharging a high volocity jet of air across the end of conduit 46 thereby rendering it a suction chamber into which the combustion gases flow from the rear gas pass 16.
  • gases drawn into the suction ohamber are entrained in the air and carried into the nozzle 50 where the velocity energy of the mixture is converted into pressure in a known manner.
  • gases can be effectively recirculated from the convection heating section to the furnace. Regulation of the recirculated gas flow can be effected by varying the flow of air through the jet nozzle 52.
  • the gas ejector is a significantly smaller piece of equipment as compared to a recirculating fan, it can be constructed of high temperature metals to enable it to withstand high gas temperatures at only a fraction of the cost of so constructing a recirculating fan. Moreover, because an ejector has no moving parts, its operation is much less subject to thermally induced stresses than is a recirculation fan. The result is that a gas ejector can accommodate much higher combustion gas temperatures enabling it to receive gas from the convection heating section from a point upstream of the economizer and, if desirable, upstream of other heating surface where the gas temperatures are normally higher.
  • the recirculation gas otftake defined by openings 48 isdisposed upstream of the economizer 30 and also upstream of another section of tubular heating surface here indicated as being the low temperature superheater 26. Because the oiftake is upstream of the economizer 30 the affect of gas recirculation on evaporation is significantly reduced so that changes in gas recirculation for the purpose of controling vapor temperatures in the superheater or reheater will not materially affect the amount of vapor being generated. Control of vapor temperature by gas recirculation is therefore more effective. Similarly, in the instant disclosed arrangement because the gas olftake is disposed upstream of the low temperature superheater 26 the effect of gas recirculation on reheat temperature control will have a reduced elfect on superheat temperatures.
  • a vapor generating unit adapted for operation on a reheat vapor cycle comprising:
  • a convection heating section including a rear gas pass communicating with said combustion gas outlet, said convection heating section containing tubular heating surface disposed in said rear gas pass, said tubular heating surface including reheat, superheat and economizer heat exchangers sequentially arranged in said rear gas pass for series flow of combustion gas thereover;
  • a vertically elongated gas recirculation conduit furnace of any tubular heating surface having its upper end communicating with said convection heating section intermediate said reheat and said superheat heat exchangers and its lower end communicating with said furnace at the lower end thereof;
  • a vapor generating unit comprising:
  • a convection heating section including a rear gas pass communicating with said combustion gas outlet, and containing tubular heating surface disposed in said rear gas pass;
  • gas ejector means disposed in said conduit 1,860,366 5/1932 Lucke 110-49 means for assuring withdrawal of combustion 1,915,397 6/1933 Barker 11049 XR gases from said rear gas pass during introduction 2,840,055 6/ 1958 Blaskowski 122-479 thereof to said furnace;
  • (v) means to supply motor fluid under pressure FOREIGN PATENTS to said conduit upstream of said gas ejector 71 9 1 6/1939 1 means.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
US604203A 1966-12-23 1966-12-23 Vapor generator having gas recirculation system using gas ejector Expired - Lifetime US3426734A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US60420366A 1966-12-23 1966-12-23

Publications (1)

Publication Number Publication Date
US3426734A true US3426734A (en) 1969-02-11

Family

ID=24418627

Family Applications (1)

Application Number Title Priority Date Filing Date
US604203A Expired - Lifetime US3426734A (en) 1966-12-23 1966-12-23 Vapor generator having gas recirculation system using gas ejector

Country Status (3)

Country Link
US (1) US3426734A (de)
DE (1) DE1551933A1 (de)
FR (1) FR1547979A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4098200A (en) * 1976-12-09 1978-07-04 Dauvergne Hector A Low pollution solid waste burner
US4286548A (en) * 1979-11-19 1981-09-01 Brash Leslie O Gas recirculation apparatus with integral ash hoppers
EP0224050A1 (de) * 1985-11-07 1987-06-03 L. & C. Steinmüller GmbH Kohlegefeuerter Dampferzeuger für Kohle-Kombiblock
US5795146A (en) * 1996-05-23 1998-08-18 Btu International, Inc. Furnace chamber having eductor to enhance thermal processing
US6314896B1 (en) * 1999-06-10 2001-11-13 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for operating a boiler using oxygen-enriched oxidants
US6532881B2 (en) * 1999-06-10 2003-03-18 L'air Liquide - Societe' Anonyme A' Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation De Procedes Georges Claude Method for operating a boiler using oxygen-enriched oxidants
US6619218B2 (en) * 2000-12-05 2003-09-16 San Iku Co., Ltd. Method and apparatus for making a pollutant harmless

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1766534A (en) * 1926-04-28 1930-06-24 Prat Daniel Corp Furnace
US1837713A (en) * 1926-03-09 1931-12-22 Fuller Lehigh Co Furnace and method of operating the same
US1860366A (en) * 1927-03-11 1932-05-31 Fuller Lehigh Co Furnace and method of operating the same
US1915397A (en) * 1927-12-05 1933-06-27 B P Lientz Mfg Company Furnace
US2840055A (en) * 1955-06-20 1958-06-24 Combustion Eng Method and apparatus for generating steam

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1837713A (en) * 1926-03-09 1931-12-22 Fuller Lehigh Co Furnace and method of operating the same
US1766534A (en) * 1926-04-28 1930-06-24 Prat Daniel Corp Furnace
US1860366A (en) * 1927-03-11 1932-05-31 Fuller Lehigh Co Furnace and method of operating the same
US1915397A (en) * 1927-12-05 1933-06-27 B P Lientz Mfg Company Furnace
US2840055A (en) * 1955-06-20 1958-06-24 Combustion Eng Method and apparatus for generating steam

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4098200A (en) * 1976-12-09 1978-07-04 Dauvergne Hector A Low pollution solid waste burner
US4286548A (en) * 1979-11-19 1981-09-01 Brash Leslie O Gas recirculation apparatus with integral ash hoppers
EP0224050A1 (de) * 1985-11-07 1987-06-03 L. & C. Steinmüller GmbH Kohlegefeuerter Dampferzeuger für Kohle-Kombiblock
US5795146A (en) * 1996-05-23 1998-08-18 Btu International, Inc. Furnace chamber having eductor to enhance thermal processing
US6314896B1 (en) * 1999-06-10 2001-11-13 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Method for operating a boiler using oxygen-enriched oxidants
US6418865B2 (en) * 1999-06-10 2002-07-16 American Air Liquide Method for operating a boiler using oxygen-enriched oxidants
US6532881B2 (en) * 1999-06-10 2003-03-18 L'air Liquide - Societe' Anonyme A' Directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation De Procedes Georges Claude Method for operating a boiler using oxygen-enriched oxidants
US6619218B2 (en) * 2000-12-05 2003-09-16 San Iku Co., Ltd. Method and apparatus for making a pollutant harmless

Also Published As

Publication number Publication date
DE1551933A1 (de) 1970-05-21
FR1547979A (fr) 1968-11-29

Similar Documents

Publication Publication Date Title
US4470255A (en) Power generation plant
US3048131A (en) Method for burning fuel
US3443550A (en) Two-section heat recovery steam generator
US3118429A (en) Power plant in which single cycle gas turbine operates in parallel with direct fired steam generator
US3314231A (en) Steaming feedwater system utilizing gas turbine exhaust
US3823693A (en) Fluidized bed heat exchanger
US3125995A (en) forced flow vapor generating unit
US2744733A (en) Heat exchange apparatus
US3155079A (en) Supercritical vapor generator power plant system
US2962005A (en) Forced flow vapor generating unit
US2287798A (en) Vapor generator
US2897797A (en) Steam generating, superheating, and reheating unit, and method effected thereby
US2918909A (en) Steam generating and resuperheating plant
US3020894A (en) Steam generating and superheating unit
US4421065A (en) Heating equipment for an installation using steam and heated gas
US2905155A (en) Gas recirculation method for controlling superheat in a slag tap vapor generating and superheating unit and apparatus therefor
US3245385A (en) Forced flow vapor generating unit
US2876748A (en) Vapor generating and superheating unit with vapor temperature controls
US3312198A (en) Steam generator having improved steam heating sections arranged for parallel flow
US2918910A (en) Radiant steam generating unit with tubular furnace division wall sections spaced apart to form a gap aligned with the hopper bottom throat
US2900174A (en) Vapor generator having a vapor heater with a novel outlet header
US1898079A (en) Steam generator
US1828814A (en) Single circuit water tube boiler
US2980084A (en) System for burning low volatile fuels
US2922406A (en) Method and apparatus for generating, superheating, and reheating steam with steam temperature control by selective gas recirculation