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WO1995026483A1 - Procede et dispositif de reajustement de la surface de transfert thermique d'un lit fluidise - Google Patents

Procede et dispositif de reajustement de la surface de transfert thermique d'un lit fluidise Download PDF

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Publication number
WO1995026483A1
WO1995026483A1 PCT/SE1995/000322 SE9500322W WO9526483A1 WO 1995026483 A1 WO1995026483 A1 WO 1995026483A1 SE 9500322 W SE9500322 W SE 9500322W WO 9526483 A1 WO9526483 A1 WO 9526483A1
Authority
WO
WIPO (PCT)
Prior art keywords
bed
fluidized
tube
heat
tube system
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.)
Ceased
Application number
PCT/SE1995/000322
Other languages
English (en)
Inventor
Mats Andersson
Rolf Hellbeck
Martin Olsson
Sven-Olof ÖSTMAN
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.)
Alstom Power Carbon AB
Original Assignee
ABB Carbon AB
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 ABB Carbon AB filed Critical ABB Carbon AB
Priority to EP95914650A priority Critical patent/EP0795108B1/fr
Priority to DE69513039T priority patent/DE69513039T2/de
Publication of WO1995026483A1 publication Critical patent/WO1995026483A1/fr
Anticipated expiration legal-status Critical
Priority to FI970559A priority patent/FI970559A7/fi
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D13/00—Heat-exchange apparatus using a fluidised bed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements or dispositions of combustion apparatus
    • F22B31/0007—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements or dispositions of combustion apparatus with combustion in a fluidized bed
    • F22B31/0015—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements or dispositions of combustion apparatus with combustion in a fluidized bed for boilers of the water tube type
    • F22B31/0023—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements or dispositions of combustion apparatus with combustion in a fluidized bed for boilers of the water tube type with tubes in the bed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F23C10/18—Details; Accessories
    • F23C10/28—Control devices specially adapted for fluidised bed, combustion apparatus

Definitions

  • a PFBC power plant Pressure Fluidized Bed Combustion
  • a steam turbine for utilizing steam energy generated in a tube system immersed into a fluidized bed.
  • a gas turbine is employed at the same time for utilizing the energy contents in flue gases formed during combustion in the bed.
  • the invention relates to the problem of dimensioning the heat-transferring tube area of the tube system.
  • particulate fuel usually coal
  • the bed is supplied with combustion air in the form of compressed air from the pressure vessel which surrounds a bed vessel, wherein the fluidized bed is stored, via fluidization nozzles below the bed.
  • the combustion gases which are formed during the combustion process are passed through a freeboard above the bed surface, whereupon they are cleaned and passed to a gas turbine.
  • the combustion gases drive the gas turbine, which in turn drive a generator as well as a compressor which provides the pressure vessel with compressed air.
  • a steam generator in the form of a tube bundle which constitutes a component in a steam system, is placed in the bed.
  • steam is generated, energy thus being obtained from the bed via the steam turbines to which the steam is led in the steam system.
  • the entire tube bundle is situated within the bed.
  • the cooling capacity of the tube bundle must be dimensioned to the power output from the bed to be able to maintain the correct bed tempera- ture.
  • both the steam turbine and the gas turbine are supplied with nominal power values for the respective turbine type, dimen ⁇ sioned for the plant.
  • the steam turbine it is a difficult technical problem to dimension the steam turbine to the exactly nominally correct power value when designing a PFBC plant, that is, the design of the steam turbine.
  • the dimen ⁇ sioning of the steam turbine is dependent on the fuel fine ⁇ ness, the moisture content of the fuel, the type of fuel, etc. , whereby the dimensioning of the steam turbine entails an adaptation to each individual plant taking into consideration, inter alia, the properties of the fuel.
  • a fundamental and difficult question to answer is how large a heat-transfer area is required in the tube bundle to achieve a certain desired steam production.
  • the heat transfer to the tube bundle shall be designed such that the calculated desired nominal temperature of the combustion gases, which are to drive the gas turbine, at full bed height at the same time provides a nominal steam production in the tube bundle such that a 100 per cent power output from the gas turbine is obtained while at the same time a 100 per cent power output is obtained at the steam turbine.
  • the heat absorption " .in the bed is performed by the generation of steam in the steam generator shaped as a tube bundle.
  • the steam production is controlled by the relationship
  • ⁇ T is the locally driving temperature difference
  • A is the installed area of the steam generator k is the heat-transfer coefficient
  • A constitutes the installed area of the steam generator in the PFBC plant and cannot be influenced without interfering in the plant.
  • the third parameter k can be influenced to a certain extent.
  • the parameter k or that part of the parameter k which is related to the external heat- transfer coefficient is - from the engineering point of view - a difficult parameter to calculate with satisfactory accuracy and thus to take into account when dimensioning the steam generator.
  • the dimensioning of the steam generator requires that variation in the steam produc ⁇ tion due to, for example, the quality of the fuel is taken into consideration.
  • Another problem which should be observed is the uncertainty which arises because of the properties of the bed, over which technicians have moderate control. This includes, for example, variation of particle fineness or particle properties when the quality or composition of the fuel fluctuates, or when changing to firing of a somewhat different type of coal than what was originally intended when firing, for example, parti- culate coal, all of these examples resulting in a changed k- value with an ensuing incorrectly dimensioned heat transfer.
  • the surplus steam is discharged from the steam system downstream of the bed and is supplied to a preheater in the form of a heat exchanger, which the combustion air flows through upstream of the bed, a higher temperature thus being imparted to the combustion air inclu ⁇ ded, which results in the power output from the gas turbine increasing.
  • a preheater in the form of a heat exchanger, which the combustion air flows through upstream of the bed, a higher temperature thus being imparted to the combustion air inclu ⁇ ded, which results in the power output from the gas turbine increasing.
  • an incorrectly dimensioned tube system may be corrected by transferring a variable quantity of energy to a gas system in which the gas turbine is included.
  • a disadvantage of such a solution is that it entails installation of additional components and associated control equipment and thus makes the plant more complicated.
  • the present invention is characterized in that the heat- transfer area of the steam generator is designed somewhat oversized in the bed in a PFBC power plant. By then creating one or more non-fluidized zones in the bed during operation, the active heat-transfer tube area may be adjusted. A certain part of the tube area is rendered passive as regards heat transfer.
  • Defluidization is achieved in a very simple manner by shutting off the fluidizing air to the bed below a vertical channel where a defluidized zone is to be created.
  • a barrier in the form of a shelf or a stop plate is installed near the lower ⁇ most level of the tube bundle, thus preventing fluidizing air from reaching the bed above the barrier. This results in the creation of an almost vertically standing defluidized zone above the barrier.
  • the cross-section area of the zone in the horizontal direction is determined by the horizontal area of the barrier.
  • these defluidized zones are created • nearest the walls of the combustor by shutting off the flui ⁇ dizing air as mentioned above and installing stop plates at the boiler walls in the vicinity of the lower level of a tube bundle.
  • An additional advantage of the invention is that the risks of erosion on tube surfaces and boiler walls are reduced.
  • Experience has shown a tendency to erosion in vertical channels in a fluidized wall, where no obstacles to a bed material flow in the vertical direction occur, as is the case precisely at a gap between tubes in a tube bundle and an adjacent boiler wall.
  • the upwardly-rising flows of fluidizing gas and the flows of bed material may in these gaps reach high velocities, which results in a higher erosion effect on the wall and tube material close to the path of the flow.
  • Still another advantage of the method according to the inven- tion can be understood when considering the construction of the walls in the room which surrounds the bed.
  • These walls consist of tube panels, which at the same time constitute a part of the walls of the combustor.
  • These tube panels are traversed by water, included in the steam system of the plant.
  • the water is usually heated in an economizer and is thereafter preheated further in the tube panels around the bed before the water is supplied to a steam generator in the bed. From the point of view of manufacturing, it is an advantage to be able to heat the water in the economizer to a high degree. If the heating is driven too far in the economizer, on the other hand, a risk of boiling of the water in the panel walls of the combustor arises.
  • Figure 1 schematically illustrates a view of a pressurized fluidized bed where the positions of the defluidizing devices according to the invention are shown.
  • Figure 2 shows the same view as Figure 1 with regions where non-fluidized zones are created between the tube bundle and the boiler wall by means of devices according to the invention marked as regions in the figure with heavier shading.
  • Figure 3 schematically shows a view of a pressurized fluidized bed where the positions of the defluidizing devices according to the invention are shown in a bed where two tube bundles create an intermediate gap and where a non-fluidized zone is created between two tube bundles by means of devices according to the invention, the non-fluidized region being marked in the figure as a region with heavier shading in the gap created between the tube bundles.
  • FIG. 1 the central units of a PFBC power plant are represented, wherein a combustor 1 is housed in a pressure vessel 2. Air from a compressor (not shown) is supplied to the pressure vessel 2 via the air inlet 3 for pressurization of the pressure vessel 2 and hence also the combustor 1. The compressed air 4 is supplied to the combustor 1 via fluidization nozzles 5 at the bottom of the combustor for fluidization of a bed 6 accommodated in the combustor.
  • the bed consists of bed material and of particulate fuel which is burnt in the fluidizing air 4 supplied to the bed 6.
  • Combus ⁇ tion gases from the bed 6 pass through a freeboard above the surface of the bed and are forwarded via the outlet 8 for cleaning in dust separators, whereafter the combustion gases are expanded in a gas turbine (not shown) , where the energy contents in the gases are transformed into useful energy.
  • a tube bundle 10 which is completely immersed into the bed at full-load operation, is also shown. Water is supplied to the tube bundle 10 at 11 for cooling the bed 10 and further for generating steam in the tubes in the tube bundle. The steam is forwarded at 12 to a steam turbine (not shown) in a steam cycle in the plant.
  • the heat-transfer area of the tubes in the tube bundle 10 is made somewhat larger than what is justified to achieve a cooling of the bed which is suffi ⁇ cient to maintain the bed at an optimum working temperature.
  • the heat-transfer area of the tubes of the tube bundle 10 can then be reduced by installing a barrier or shield in the form of - in the simplest case - a shelf 15 near the lowermost level 14 of the tube bundle.
  • the shelf is suitably located horizontally or almost horizontally and is connected to the boiler wall 16, that is, in this case to the wall of the combustor 1 and will thus block the inlet for a flow of fluidized bed material to a gap 17 shown between the tube bundle 10 and the boiler wall 16.
  • an almost vertical channel 18 of non-fluidized bed material thus arises along the boiler wall 16.
  • the shelf 15 consists of a plate which is attached to the boiler wall 16, for example by welding thereto.
  • Other materials and other forms than a plate shelf plane may, of course, be used.
  • other geometries of the barrier may be desirable. For example, shapes with triangular cross sections may be preferable.
  • a defluidizing member 15 instead of a shelf 15 there may be arranged a low, prefe ⁇ rably vertical, fixedly mounted partition which is applied near the lowermost tubes of the tube system (10), between the gap 17 and the tube system 10, while at the same time fluidi ⁇ zing air is not supplied below the gap 17 in the bed.
  • a low, prefe ⁇ rably vertical, fixedly mounted partition which is applied near the lowermost tubes of the tube system (10), between the gap 17 and the tube system 10, while at the same time fluidi ⁇ zing air is not supplied below the gap 17 in the bed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

L'invention est caractérisée par le fait que la zone de transfert thermique d'un générateur de vapeur (10) est légèrement surdimensionnée dans un lit fluidisé (6) d'une centrale PFBC (combustion à lit fluidisé sous pression). On peut ajuster la zone active de transfert thermique de tubes dans le générateur de vapeur (10) par création d'une zone ou d'une pluralité de zones non fluidisées (18) dans le lit (6) au cours du fonctionnement. Une certaine proportion de la zone de tubes montée est rendue passive en ce qui concerne le transfert thermique. La défluidisation s'effectue par coupure de l'alimentation en air de fluidisation (4) vers le lit (6) au-dessus d'un canal vertical où doit se créer une zone non fluidisée (18). On monte une barrière (15) sous forme d'étagère ou de plaque de butée à proximité du niveau le plus bas (10) du faisceau de tubes (10), ce qui empêche l'air de fluidisation (4) d'accéder au lit (6) au-dessus de la barrière (15). Ceci permet d'obtenir une zone non fluidisée (18) pratiquement verticale au-dessus de la barrière (15). La section transversale de la zone (18) dans le sens horizontal est déterminée par la zone horizontale de la barrière (15).
PCT/SE1995/000322 1994-03-28 1995-03-27 Procede et dispositif de reajustement de la surface de transfert thermique d'un lit fluidise Ceased WO1995026483A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP95914650A EP0795108B1 (fr) 1994-03-28 1995-03-27 Procede et dispositif de reajustement de la surface de transfert thermique d'un lit fluidise
DE69513039T DE69513039T2 (de) 1994-03-28 1995-03-27 Verfahren und vorrichtung zum ändern der wärmeübertragungsfläche eines wirbelbettes
FI970559A FI970559A7 (fi) 1994-03-28 1997-02-10 Menetelmä ja laite leijukerroksen lämmönsiirtoalan uudelleensäätämiseksi

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9401032A SE9401032L (sv) 1994-03-28 1994-03-28 Förfarande och anordning för att efterjustera tubyta i en fluidiserad bädd
SE9401032-9 1994-03-28

Publications (1)

Publication Number Publication Date
WO1995026483A1 true WO1995026483A1 (fr) 1995-10-05

Family

ID=20393443

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1995/000322 Ceased WO1995026483A1 (fr) 1994-03-28 1995-03-27 Procede et dispositif de reajustement de la surface de transfert thermique d'un lit fluidise

Country Status (6)

Country Link
EP (1) EP0795108B1 (fr)
DE (1) DE69513039T2 (fr)
ES (1) ES2141345T3 (fr)
FI (1) FI970559A7 (fr)
SE (1) SE9401032L (fr)
WO (1) WO1995026483A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000043713A1 (fr) 1999-01-21 2000-07-27 Kvaerner Pulping Oy Procede concernant une grille de tuyau pour chaudiere a lit fluidise et grille de tuyau
DE102016225338A1 (de) * 2016-12-16 2018-06-21 Deutsches Zentrum für Luft- und Raumfahrt e.V. Wärmeübertrager zur Wärmeübertragung zwischen einem partikelförmigen Wärmeträgermedium und einem zweiten Medium

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2842102A (en) * 1954-11-18 1958-07-08 Combustion Eng Steam generation
US3387590A (en) * 1967-03-16 1968-06-11 Interior Usa System for regulating the total heat output in a burning fluidized bed heat exchanger or boiler
US3542523A (en) * 1967-09-08 1970-11-24 Dorr Oliver Inc Reactor design
GB1525222A (en) * 1973-05-05 1978-09-20 Pearce A Fluidised beds
US4177765A (en) * 1978-08-14 1979-12-11 The Babcock & Wilcox Co. Output control for fluidized bed boilers
DE3030215A1 (de) * 1980-08-09 1982-03-18 Bergwerksverband Gmbh, 4300 Essen Wirbelbett-feuerung
US4396056A (en) * 1980-11-19 1983-08-02 Hodges James L Apparatus and method for controlling heat transfer between a fluidized bed and tubes immersed therein
US4436507A (en) * 1981-07-16 1984-03-13 Foster Wheeler Energy Corporation Fluidized bed reactor utilizing zonal fluidization and anti-mounding air distributors
US4453494A (en) * 1982-03-22 1984-06-12 Combustion Engineering, Inc. Fluidized bed boiler having a segmented grate
SE457661B (sv) * 1986-06-12 1989-01-16 Lars Axel Chambert Saett och reaktor foer foerbraenning i fluidiserad baedd

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2842102A (en) * 1954-11-18 1958-07-08 Combustion Eng Steam generation
US3387590A (en) * 1967-03-16 1968-06-11 Interior Usa System for regulating the total heat output in a burning fluidized bed heat exchanger or boiler
US3542523A (en) * 1967-09-08 1970-11-24 Dorr Oliver Inc Reactor design
GB1525222A (en) * 1973-05-05 1978-09-20 Pearce A Fluidised beds
US4177765A (en) * 1978-08-14 1979-12-11 The Babcock & Wilcox Co. Output control for fluidized bed boilers
DE3030215A1 (de) * 1980-08-09 1982-03-18 Bergwerksverband Gmbh, 4300 Essen Wirbelbett-feuerung
US4396056A (en) * 1980-11-19 1983-08-02 Hodges James L Apparatus and method for controlling heat transfer between a fluidized bed and tubes immersed therein
US4436507A (en) * 1981-07-16 1984-03-13 Foster Wheeler Energy Corporation Fluidized bed reactor utilizing zonal fluidization and anti-mounding air distributors
US4453494A (en) * 1982-03-22 1984-06-12 Combustion Engineering, Inc. Fluidized bed boiler having a segmented grate
SE457661B (sv) * 1986-06-12 1989-01-16 Lars Axel Chambert Saett och reaktor foer foerbraenning i fluidiserad baedd

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 7, No. 291, M-265; & JP,A,58 164 914 (KAWASAKI JUKOGYO KK), 29 Sept 1983. *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000043713A1 (fr) 1999-01-21 2000-07-27 Kvaerner Pulping Oy Procede concernant une grille de tuyau pour chaudiere a lit fluidise et grille de tuyau
US6571746B1 (en) 1999-01-21 2003-06-03 Kvaerner Pulping Oy Method in connection with a pipe grate for fluidized bed boiler and a pipe grate
US6782848B2 (en) 1999-01-21 2004-08-31 Kvaerner Power Oy Method in connection with a pipe grate for fluidized bed boiler and a pipe grate
DE102016225338A1 (de) * 2016-12-16 2018-06-21 Deutsches Zentrum für Luft- und Raumfahrt e.V. Wärmeübertrager zur Wärmeübertragung zwischen einem partikelförmigen Wärmeträgermedium und einem zweiten Medium

Also Published As

Publication number Publication date
EP0795108A1 (fr) 1997-09-17
FI970559A0 (fi) 1997-02-10
ES2141345T3 (es) 2000-03-16
EP0795108B1 (fr) 1999-10-27
SE9401032L (sv) 1995-09-29
DE69513039D1 (de) 1999-12-02
DE69513039T2 (de) 2000-06-29
FI970559A7 (fi) 1997-02-10
SE9401032D0 (sv) 1994-03-28

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