EP0720714A1 - Chaudière à vapeur du type à circulation ouverte, et procédé de faire fonctionner une telle chaudière - Google Patents

Chaudière à vapeur du type à circulation ouverte, et procédé de faire fonctionner une telle chaudière

Info

Publication number
EP0720714A1
EP0720714A1 EP94926796A EP94926796A EP0720714A1 EP 0720714 A1 EP0720714 A1 EP 0720714A1 EP 94926796 A EP94926796 A EP 94926796A EP 94926796 A EP94926796 A EP 94926796A EP 0720714 A1 EP0720714 A1 EP 0720714A1
Authority
EP
European Patent Office
Prior art keywords
tubes
flow
steam generator
gas
tube
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.)
Granted
Application number
EP94926796A
Other languages
German (de)
English (en)
Other versions
EP0720714B1 (fr
Inventor
Wolfgang Köhler
Eberhard Wittchow
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP0720714A1 publication Critical patent/EP0720714A1/fr
Application granted granted Critical
Publication of EP0720714B1 publication Critical patent/EP0720714B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/10—Water tubes; Accessories therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/40—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only inside the tubular element
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/10—Water tubes; Accessories therefor
    • F22B37/101—Tubes having fins or ribs
    • F22B37/103—Internally ribbed tubes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/02—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by influencing fluid boundary

Definitions

  • the invention relates to a method for operating a once-through steam generator with a gas train consisting of gas-tightly welded, essentially vertically arranged tubes which are flowed through in parallel by a flow medium and through the surface structure of which is provided on the inside, a mixing of the flow medium is produced.
  • the invention is further directed to a once-through steam generator operating according to this method.
  • a steam generator the combustion chamber wall of which is constructed from vertically arranged pipes, is more economical to produce than a steam generator having a helical tube.
  • the unavoidable differences in the heat supply to the individual tubes can lead to temperature differences between adjacent tubes - in particular at the outlet of an evaporator. These temperature differences can cause damage due to impermissible thermal stresses.
  • the temperature differences can be avoided by drastically reducing the friction pressure loss.
  • the reduction in turn is achieved by a corresponding reduction in the flow rate, i.e. the mass flow density in the pipes.
  • it is e.g. known from European Patent Application 0 503 116 to use tubes which have ribs forming a multi-start thread on their inside.
  • cross-drawn tubes are known from German Offenlegungsschrift 20 32 891, on the inside of which a superimposed second ribbing is superimposed on a first ribbing to form a surface structure. If the combustion chamber wall of a steam generator is piped with internally finned evaporator tubes, a swirl is superimposed on the axial flow, which leads to a phase separation of the flow or heat absorption medium with a water film on the inner wall of the tube, ie on the heating surface. This allows the very good heat transfer from boiling to be maintained almost until the water has completely evaporated. In the pressure range between 200 bar and 221 bar, however, impermissibly high wall temperatures cannot always be avoided with strong heating with a swirl flow alone.
  • pages 352 to 360 range above a pressure of around 210 bar already slight wall overheating in order to get from the boiling state with a wetted heating surface to film boiling with an unwetted heating surface. Even in the case of slight overheating in the superheated boundary layer, vapor bubbles can form in the pressure range mentioned, which combine to form large bubbles and thus hinder heat transfer (homogeneous nucleation).
  • the invention is therefore based on the object of specifying a method for operating a once-through steam generator with which small temperature differences at the outlet of adjacent steam generator pipes are achieved. This is to be achieved in a continuous steam generator, in the case of which evaporator tubes, particularly near the critical pressure of about 210 bar, a particularly good heat transfer from the tube wall or heating surface to the heat absorption medium is ensured.
  • this object is achieved according to the invention in that the mass flow density m - based on full-load operation, ie 100% steam output - in the pipes is set as a function of the inner pipe diameter d, one determined by a pair of values of the mass flow density m and the inner pipe diameter d
  • the invention is based on the consideration that a flow swirl is not sufficient to ensure good heat transfer for operating points between curve B and the abscissa, especially in the vicinity of the critical pressure range above approximately 200 bar. Rather, it is also necessary to mix the flow well. In this way wall overheating can be avoided. A high level of turbulence in the flow can also prevent such large vapor bubbles from forming on the heating surface or in the superheated boundary layer that they can combine to form a vapor film and thus deteriorate the heat transfer.
  • the essentially vertically arranged tubes of the gas train to achieve high flow turbulence and / or
  • Formation of longitudinal vortices in the flow medium on their inside has a surface structure formed by two superimposed opposing ribs and are connected in parallel for the flow of the flow medium, and the opposing ribs including the same angle with the pipe axis, the object is achieved according to the invention, that the ridges delimited by the ribs are pyramid-shaped.
  • the pyramid-shaped structure leads to a particularly favorable longitudinal vortex formation when overflowing.
  • the first ribbing of the evaporator tube of such a continuous steam generator includes an acute angle with the tube axis, while the second ribbing runs parallel to the tube axis, a flank angle formed by the first or screw-shaped ribbing with the tube wall being flatter on the inflow side than on the downstream side.
  • the evaporator tube according to this second alternative then has a helical internal ribbing with longitudinal grooves interrupting the ribs in a production-technically simple manner.
  • the longitudinal grooves provide tear-off edges which favor the generation of vertebrae, the formation of longitudinal vertebrae being particularly advantageously promoted by the different flank angles.
  • the elevations of the inner wall limited by the ribbing are advantageously at least 0.7 mm.
  • FIG. 1 shows a simplified representation of a steam generator with a vertically tube-shaped combustion chamber wall
  • FIG. 2 shows a section of a horizontal section through a vertical throttle cable
  • FIG. 3 shows a longitudinal section through a small section of a counter-ribbed inner rib
  • FIG. 4 shows a section IV from FIG. 3 on a larger scale with an elevation
  • Figure 5 shows another embodiment of an opposing
  • FIG. 6 shows a detail VI from FIG. 5 on a larger scale with a pyramid-shaped elevation
  • FIG. 7 shows a further exemplary embodiment of an opposing one
  • FIG. 9 shows a coordinate system with curves A and B.
  • FIG. 1 shows schematically a once-through steam generator 2 with a rectangular cross section, the vertical gas duct of which is formed by a surrounding wall 4 which merges into a funnel-shaped bottom 6 at the bottom.
  • a lower region V of the gas flue there are a number of burners for a fossil fuel in each opening 8, of which only two are visible, in the enclosure composed of steam generator tubes 10 according to FIGS. 3, 5 or 7 - or combustion chamber wall 4 attached.
  • the steam generator tubes 10 are arranged in this region V, in which they are welded together gas-tight to form an evaporator heating surface 12 (FIG. 2), and run vertically.
  • the tubes 10 welded to one another in a gastight manner form, for example in a tube-web-tube construction or in a fin tube construction, the gas-tight combustion chamber wall 4.
  • Convection heating surfaces 14, 16 and 18 are located above this area V of the gas flue. Above this is a flue gas outlet channel 20, via which the flue gas RG generated by combustion of a fossil fuel leaves the vertical gas flue.
  • the flue gas RG serves as a heating medium for the water or water-steam mixture flowing in the damper tubes 10.
  • the steam generator tubes 10 have on their inside
  • the steam generator tube 10 according to FIG. 3 is provided on its inside with a first rib - in the direction of the arrow 22 - which is superimposed on an opposing second rib - in the direction of the arrow 24.
  • the superimposed fins 22 ', 24' include equally large, acute angles a 1 and b 1 with the tube axis M.
  • the depressions 28 ' are wedge-shaped, so that the elevations 26' - as can be seen in the enlarged section VI according to FIG. 6 - are pyramid-shaped. This results in inclined surfaces 33 and 34 both on the inflow side and on the outflow side. As indicated by the arrows 36 'and 38', surfaces 33, 34 overflowed at a certain angle tend to form longitudinal vortices in the wake in the overflow. This leads to thorough mixing of the boundary layer running directly on the inner wall with the core or main flow of the water / steam mixture flowing through the steam generator tube 10.
  • the steam generator tube 10 has, in addition to a helical inner rib 22, “longitudinal grooves as depressions 28”.
  • This first ribbing 22 "in turn encloses an acute angle a" with the tube axis M, while the second ribbing 24 "runs parallel to the tube axis M.
  • the longitudinal grooves or depressions 28" define tear-off edges 40 which generate a vortex favor.
  • the elevations 26 "of the helical ribbing 22" with the inner tube wall 42 include a flank angle c on the inflow side and a flank angle f on the outflow side.
  • the flank angle c on the inflow side is smaller than or equal to the flank angle f on the outflow side. This in turn favors the training of Longitudinal vortices on the outflow side, as indicated by the arrows 36 ", 38".
  • the heat generated by the combustion of a fossil fuel in the burners of the combustion chamber wall 4 is absorbed by the water or water-steam mixture (flow or heat absorption medium) which flows through the pipes 10 and thereby evaporates.
  • the pipe 10 transfers the heat it has absorbed from the flue gas RG particularly well to the flow medium and is safely cooled ..
  • a surface structure on the inside of the pipe 10 according to the exemplary embodiment according to FIG .
  • the mass flow density m is selected according to the invention as a function of the tube inner diameter d.
  • the mass flow density m is the mean throughput per area and time (kg / m 2 -s) of all pipes 10 at full load operation, ie 100% steam output.
  • the mass flow density m can be represented as a function of the inner pipe diameter d in the coordinate system according to FIG.
  • Curve B in FIG. 8 reflects the course of the mass flow density m, which is possible from this point of view.
  • the mass flow in multi-heated pipes 10 increases.
  • the mass flow in multi-heated pipes 10 does not decrease by more than 20% of the percentage of the multi-heating. For example, the additional heating of a tube 10%, the mass flow in this tube will decrease by less than 2% compared to the value of the average heated tubes 10.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Geometry (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
  • Gas Burners (AREA)
  • Combustion Of Fluid Fuel (AREA)

Abstract

Afin d'éviter les conséquences négatives d'un mauvais chauffage de tubes individuels (10) d'un générateur de vapeur (2) à tubulures verticales situées dans la chambre de combustion (4), la densité du courant massique m dans les tubulures (10) est ajustée au-dessous d'une valeur maximale prédéterminée (courbe B) qui dépend du diamètre intérieur d des tubulures utilisées. Afin d'éviter que la température de la paroi des tubulures ne s'élève de manière inadmissible même à proximité de la pression critique comprise entre 200 et 221 bars, la face intérieure de chaque tuyau (10) a une surface structurée de façon à provoquer une intense turbulence et/ou un tourbillonnement longitudinal dans le fluide en écoulement. On assure ainsi un mélange intime des composants du milieu en écoulement, donc une bonne transmission de chaleur.
EP94926796A 1993-09-30 1994-09-19 Chaudière à vapeur du type à circulation ouverte, et procédé de faire fonctionner une telle chaudière Expired - Lifetime EP0720714B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4333404 1993-09-30
DE4333404A DE4333404A1 (de) 1993-09-30 1993-09-30 Durchlaufdampferzeuger mit vertikal angeordneten Verdampferrohren
PCT/DE1994/001086 WO1995009325A1 (fr) 1993-09-30 1994-09-19 Procede permettant de faire fonctionner un generateur en continu de vapeur et generateur en continu de vapeur fonctionnant selon ce procede

Publications (2)

Publication Number Publication Date
EP0720714A1 true EP0720714A1 (fr) 1996-07-10
EP0720714B1 EP0720714B1 (fr) 1998-03-25

Family

ID=6499111

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94926796A Expired - Lifetime EP0720714B1 (fr) 1993-09-30 1994-09-19 Chaudière à vapeur du type à circulation ouverte, et procédé de faire fonctionner une telle chaudière

Country Status (8)

Country Link
US (1) US5706766A (fr)
EP (1) EP0720714B1 (fr)
JP (1) JPH09503284A (fr)
KR (1) KR960705177A (fr)
CN (1) CN1132548A (fr)
DE (2) DE4333404A1 (fr)
RU (1) RU2123634C1 (fr)
WO (1) WO1995009325A1 (fr)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5901669A (en) * 1995-04-05 1999-05-11 The Babcock & Wilcox Company Variable pressure once-through steam generator upper furnace having non-split flow circuitry
DE19600004C2 (de) * 1996-01-02 1998-11-19 Siemens Ag Durchlaufdampferzeuger mit spiralförmig angeordneten Verdampferrohren
DE19602680C2 (de) * 1996-01-25 1998-04-02 Siemens Ag Durchlaufdampferzeuger
DE19644763A1 (de) * 1996-10-28 1998-04-30 Siemens Ag Dampferzeugerrohr
DE19645748C1 (de) * 1996-11-06 1998-03-12 Siemens Ag Verfahren zum Betreiben eines Durchlaufdampferzeugers und Durchlaufdampferzeuger zur Durchführung des Verfahrens
AU2003275378A1 (en) * 2002-10-04 2004-05-04 Nooter/Eriksen, Inc. Once-through evaporator for a steam generator
WO2006032556A1 (fr) * 2004-09-23 2006-03-30 Siemens Aktiengesellschaft Generateur de vapeur en continu chauffe a l'aide d'un combustible fossile
CN1831426A (zh) * 2005-03-10 2006-09-13 三井巴布科克能源公司 超临界下射锅炉
US8607567B2 (en) * 2008-04-16 2013-12-17 Alstom Technology Ltd Solar steam generator
DE102009012322B4 (de) * 2009-03-09 2017-05-18 Siemens Aktiengesellschaft Durchlaufverdampfer
DE102009012321A1 (de) 2009-03-09 2010-09-16 Siemens Aktiengesellschaft Durchlaufverdampfer
DE102009024587A1 (de) * 2009-06-10 2010-12-16 Siemens Aktiengesellschaft Durchlaufverdampfer
DE102009040250B4 (de) * 2009-09-04 2015-05-21 Alstom Technology Ltd. Zwangdurchlaufdampferzeuger für den Einsatz von Dampftemperaturen von über 650 Grad C
DE102010038885B4 (de) * 2010-08-04 2017-01-19 Siemens Aktiengesellschaft Zwangdurchlaufdampferzeuger
CH703820A1 (de) * 2010-09-21 2012-03-30 Alstom Hydro France Luftgekühlter generator.
EP3098507B1 (fr) * 2013-12-27 2018-09-19 Mitsubishi Hitachi Power Systems, Ltd. Tube de transfert de chaleur, chaudière et installation de turbine à vapeur

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1288755A (fr) * 1960-12-27 1962-03-30 Babcock & Wilcox Co Tube de production de vapeur nervuré
US4864973A (en) * 1985-01-04 1989-09-12 The Babcock & Wilcox Company Spiral to vertical furnace tube transition
EP0349834B1 (fr) * 1988-07-04 1996-04-17 Siemens Aktiengesellschaft Chaudière à vapeur à passage unique
US5070937A (en) * 1991-02-21 1991-12-10 American Standard Inc. Internally enhanced heat transfer tube
EP0503116B2 (fr) * 1991-03-13 1997-11-19 Siemens Aktiengesellschaft Tube avec plusieurs nervures hélicoidales sur sa paroi interne et générateur de vapeur en faisant usage
EP0581760B2 (fr) * 1991-04-18 2001-10-31 Siemens Aktiengesellschaft Generateur de vapeur en continu avec cheminee a gaz constituee de conduits assembles pratiquement verticalement
JP2802184B2 (ja) * 1991-07-04 1998-09-24 住友軽金属工業株式会社 凝縮器用伝熱管

Non-Patent Citations (1)

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Title
See references of WO9509325A1 *

Also Published As

Publication number Publication date
EP0720714B1 (fr) 1998-03-25
DE59405540D1 (de) 1998-04-30
WO1995009325A1 (fr) 1995-04-06
CN1132548A (zh) 1996-10-02
KR960705177A (ko) 1996-10-09
DE4333404A1 (de) 1995-04-06
US5706766A (en) 1998-01-13
JPH09503284A (ja) 1997-03-31
RU2123634C1 (ru) 1998-12-20

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