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WO1997000721A1 - Centrale a combustible de type particulaire et son mode d'exploitation - Google Patents

Centrale a combustible de type particulaire et son mode d'exploitation Download PDF

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Publication number
WO1997000721A1
WO1997000721A1 PCT/SE1996/000803 SE9600803W WO9700721A1 WO 1997000721 A1 WO1997000721 A1 WO 1997000721A1 SE 9600803 W SE9600803 W SE 9600803W WO 9700721 A1 WO9700721 A1 WO 9700721A1
Authority
WO
WIPO (PCT)
Prior art keywords
fuel
bed
power plant
air
locations
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/SE1996/000803
Other languages
English (en)
Inventor
John Weatherby
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
Publication of WO1997000721A1 publication Critical patent/WO1997000721A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • F23C10/20—Inlets for fluidisation air, e.g. grids; Bottoms
    • 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
    • F23C10/16—Fluidised bed combustion apparatus specially adapted for operation at superatmospheric pressures, e.g. by the arrangement of the combustion chamber and its auxiliary systems inside a pressure vessel
    • 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

  • the present invention relates to a power plant having a combustor and a bed located therein, to the bottom region of which air is supplied for fluidizing the bed, particle ⁇ like fuel being fed into the bed at defined locations in the bottom region thereof for combustion of the fuel in the bed as well as a method in combustion of particle-like fuel according to the preamble of the appended claim 1.
  • Firing of particle-like fuel in a fiuidized bed requires a very good distribution of the fuel fed into the bed already in the very region of feeding it thereinto, i.e. in the bottom region of the bed, so as to avoid the problems discussed below.
  • Another possible solution consists in arranging any form of distributor of the fuel in the bed after feeding it there ⁇ into, which is known through for example the patent GB 1 326 651, in which a distributor in the form of a rotating wheel provided with blades is used.
  • movable details are strongly influenced by degradating powers, such as for example the high temperature, which in combination with the fact that the availability for maintenance of possible devices is strongly reduced or disturbs the operations of the power plant, means that this is a bad so- lution of the problem.
  • a spreading device in such a bed for distributing the gas and fuel in the bed between the nozzles for feeding in the fuel and tubes for steam generation.
  • Another disadvantage of the prior art plants is that they require the use of a particle-like fuel having a low content of volatile substances, which is strongly limiting for the plants. Volatile substances present in the fuel will namely in contact with air rapidly take care of a great part of the oxygen existing therein, so that there will be a shortage of oxygen at the locations where the fuel is fed in. Also if a fuel having a low content of volatile substances is used the problem with a tendency to a deficit of oxygen will still be there in the prior art devices with the problems this will bring about at the locations for feeding the fuel into the bed, should not un- acceptably much fluidizing air be supplied to the bed, which then will cause a tremendous production of NO x in other parts of the bed.
  • the object of the present invention is to provide a method as well as a power plant of the type defined in the intro ⁇ duction, which find a remedy to the inconveniences men ⁇ tioned above of such methods and plants already known.
  • This object is according to the invention obtained by pro ⁇ viding such a power plant with means for adjustably supply ⁇ ing additional air separated from the fluidizing air to the bed at said locations as well as a method according to the independent method patent claim.
  • the invention makes it possible to use fuels having different contents of volatile substances and when a fuel having a high content of volatile substances is used an ad ⁇ justment towards supply of a greater flow of additional air to the locations for feeding in fuel takes place, so that there will be a sufficient amount of oxygen left in the re ⁇ gions over these locations for being enough for the combus ⁇ tion of the fuel there after the volatile substances have taken care of that part of the oxygen they will demand.
  • fuels of different types such as of different carbon types, may have the same thermal value and be fed into the bed with the same feed rate, but they may be combusted differently fast with a factor 3. The faster the combustion takes place the more air is of course required locally so as to avoid the problem mentioned above.
  • said power plant comprises a control unit arranged to control said means, and said means comprise at least one conduit for conducting said additional air to said locations as well as at least one regulating member arranged to be controlled by the control unit and regulate the flow of said additional air in said conduit.
  • the device comprises members arranged to record data concerning the nature of the fuel fed to said locations and important for the combustion of the fuel, and the control unit is arranged to control said adjusting means on the basis of said data.
  • the supply of said additional air may in this way reliably be adapted to important nature data, such as the contents of volatile substances, of the fuel fed into the bed for obtaining an optimum combustion of the fuel without any oxygen deficit and exaggerated formation of SO x .
  • the definition of said members is here intended also to comprise members recording these nature data through a purely manual adjustment thereof through an operator.
  • the power plant comprises members adapted to record changes of the power tapped from the power plant, and the control unit is adapted to control said adjusting means on the basis of this recordal. It is in this way ensured that the supply of said additional air will be adapted to changes of the power tapped from the power plant, which will have a tendency to change the availabil ⁇ ity of oxygen in the bed.
  • the power plant comprises an additional conduit for supply of said additional air besides a conduit for feeding fuel into the bed at said locations.
  • This embodiment may be used for all types of fuel supply, but it is especially intended for the case in which the fuel is fed into the bed in the form of a liquid paste, since it will in such a case not be possible to supply said additional air directly together with the fuel.
  • said regulating means are arranged to regulate the supply of said additional air through changing the air/fuel-ratio in the fuel feeding air.
  • said regulation may accord ⁇ ingly be obtained in a very simple way by providing the ar ⁇ rangement for feeding in fuel already there with a means for regulating the air/fuel-ratio in the conduit for feeding in fuel.
  • Fig 1 schematically illustrates a PFBC-power plant having a combined gas and steam cycle (the latter is not shown), in which a device according to the invention may be applied,
  • Fig 2 is a schematic, partially sectioned view of the pressure vessel with the combustor arranged therein in the power plant according to Fig 1, which illustrates a first preferred embodiment of the method according to the inven- tion and the device according to the invention,
  • Fig 3 is a simplified, sectioned view from above of the pressure vessel and the combustor according to Fig 2, and
  • Fig 4 is a view corresponding to Fig 2, which illustrates a second preferred embodiment of the method according to the invention and the device according to the invention.
  • the invention is not in any way restricted to the use in a PFBC-power plant, i.e. a plant for combustion of particle ⁇ like fuel in a pressurized fiuidized bed, but it has special advantages when used in such a power plant, which is the reason for describing it applied to such a plant, and the overall construction and function of a possible type of such a power plant will now be explained with reference to Fig 1.
  • the plant comprises a combustor 1, which is received in a pressure vessel 2, which may have a volume in the order of 10 ⁇ m3 and which may be pressurized to for example about 16 bars.
  • Compressed air 3 for pressurizing the combustor and for fluidizing a bed 4 in the combustor is supplied to the pressure vessel.
  • the compressed air is supplied to the combustor through fluidizing nozzles 5 schematically indicated at the bottom of the combustor for fluidizing the bed enclosed in the combustor.
  • the bed is made of bed material, granule-shaped absorbent and a particle-like fuel, preferably crushed carbon, which is combusted in the fluidizing air supplied to the bed.
  • the combustion gases hereinafter called flue gases
  • flue gases in the bed are led to a pu ⁇ rification plant 7 illustrated through a box, which for ex ⁇ ample may be constituted by a set of cyclones arranged to separate particles from the flue gases.
  • the flue gases are then proceeding to a gas turbine 9 comprising a high pressure step 10 and a low pressure step 11.
  • the high pressure turbine 10 is arranged on the same axle as a high pressure compressor 12 and a generator 13, which in this way is driven by the high pressure turbine for output of useful energy.
  • the high pressure compressor 12 delivers compressed air to the combustor 1 through the conduit 14.
  • the gas expanded in the high pressure turbine 10 is led to a low pressure turbine 11.
  • the gases leaving the low pressure turbine still contains energy, which is utilized by an economizer 16.
  • the low pressure compressor is driven by the low pressure turbine and provides from the outlet thereof the high pressure compressor 12 with air compressed in a first step.
  • An intercooler 19 is arranged between the low pres ⁇ sure compressor and the high pressure compressor for lowering the air temperature of the air supplied to the in ⁇ let of the high pressure compressor 12.
  • the power plant has also a steam turbine side, which is not shown here, but it is indicated through a set of tubes 20 immersed in the fiuidized bed 4, in which water is circu ⁇ lated and evaporated and superheated through heat exchange between the tubes and the bed material for absorbing the heat generated through the combustion carried out in the bed.
  • the fuel is preferably, but not at all necessarily, consti- tuted by crushed carbon, which may be supplied as a liquid paste, i.e. preferably mixed up with water, or in a dry form through air transport.
  • the power plant has further a main conduit 24 for supply of air to the different locations 21 for feeding in of fuel through conduits 25 branched therefrom.
  • the conduit 24 takes preferably the air from the air present in the pressure vessel 2 by emerging thereinto at 26.
  • the conduit 24 is provided with a regulating member in the form of a valve 27, by which the flow of air, i.e.
  • the plant further comprises a control unit indicated by a box 28 adapted to control the valve 27. It is also indicated through lines 29 and 30 that members are arranged to co-operate with the control unit and these are arranged to record data concerning the nature of the fuel fed to said locations important for the combustion of the fuel and changes of the power tapped from the power plant, respectively, said control unit being adapted to control the valve 27 on the basis of this information from the members 29 and 30. Even if the fuel fed into the bed will be spread comparatively uniformly in the bed, it may not be neglected that a high concentration of fuel will be there exactly at the locations 21 for feeding it into the bed.
  • the air supplied to the bed through the fluidizing nozzles 5 will exactly there have a tendency to be rapidly depleted with respect to oxygen, which the locally increased combustion of the fuel requires. Quite an amount of oxygen will also at the locations for feeding in the fuel be used for the reaction with the volatile sub ⁇ stances contained in the fuel, and the size of this part depends on the contents of volatile substances in the fuel.
  • the fuel con ⁇ sists mainly of C, H, N, 0, S and ashes and in the case of a supply of the fuel in the form of a liquid paste of H2O, of which primarily H2O, H, N and 0, but also C and S, may be considered as volatile substances.
  • the contents of volatile substances may for example when different carbon types are used vary between for example 20 and 50 % by weight without changing the thermal value of the carbon for that sake.
  • Lime is preferably supplied to the bed together with the fuel for the desulphurization reaction, and the desulphuri- zation reaction may be written: CaC03 + SO2 + h® ⁇ CaS ⁇ 4 + CO2, and oxygen is accordingly consumed in said desulphu ⁇ rization, which accordingly may not take place to a desired extent when there is a deficit of oxygen and unacceptable amounts of SO2 will then come into the open air through the chimney of the power plant.
  • the fluidizing air is always sup ⁇ plied so that there will always be an average 02 ⁇ ontent in the flue gases in the free space 31 over the bed 4 within a certain interval, but it may without the supply according to the invention of additional air to the points for feeding in fuel well be so that the contents of O2 over the bed over the locations for feeding in fuel may be lower than this interval, while it is over this interval at another location.
  • this lower value may well mean a still lower value at the location for feeding in fuel, which may be so low that it is unacceptable.
  • a rapid increase of the load of such a power plant may in absence of the supply of the additional air according to the invention well result in an average 02-content in the free space 31 being lower than said interval, which indicates that the deficit of oxygen may prevail at the locations 21 for feeding in fuel.
  • FIG 4 A second embodiment of the invention is illustrated in Fig 4, in which the members for feeding in fuel are arranged to feed fuel into the bed through feeding air conveying the fuel, so called dry feeding in of fuel.
  • a dry feeding in is necessary for example when crushed carbon having a low thermal value is used, since the efficiency in the combustion thereof will be much too low if water is sup ⁇ plied and it is converted into a paste.
  • Parts of this embodiment having substantially the same function as in the embodiment according to Figs 2 and 3 are provided with the same reference numerals provided with a ' .
  • the conduits 22 and 25 for supply of fuel and additional air are here combined through conduits 32, which emerge into the bottom region of the bed at locations for feeding in fuel.
  • the conduit 24' with air from the pressure vessel to the conduits 32 for feeding in fuel comprises besides the valve 27' a fan member 33 for feeding the air, said control unit 28 being connected to the fan member 33 as well as the valve 27' for regulation thereof so as to regulate the air/fuel-ratio in the air provided with fuel fed into the bed at said locations 21. Additionally, in the conduit 23' for supply of fuel to the gas flow a valve 34 is arranged, through which the amount fuel supplied per time unit may be regulated in a conventional way, in which signals related to the position of this valve are intended to be transmit ⁇ ted to the control unit 28' .
  • the function of the part of the power plant illustrated in Fig 4 is evident in the light of the description thereof and the discussions above about the power plant part shown in Figs 2 and 3.
  • the number of locations for feeding in fuel may for example be totally different than what is shown in the Figures.
  • air in this disclosure, it has to be given a very broad sense and comprises not only the normal gas mixture existing in the free atmosphere, but all types of gas mixtures which at least have a portion of oxygen.
  • air having a constituent not existing in normal air and air from which a constituent ex- isting in the normal air has been removed are also com ⁇ prised.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)

Abstract

Centrale pourvue d'une chambre de combustion (1) avec un lit fluidisé (4) alimenté par de l'air provenant de la partie inférieure du brûleur et d'éléments (22, 23) conçus pour alimenter le lit fluidisé en combustible de type particulaire à des emplacements définis dans sa partie inférieure pour qu'il y soit brûlé. Ladite centrale comprend des éléments (24, 25, 27) permettant d'amener des quantités dosables d'air supplémentaire indépendamment du circuit d'air de fluidisation auxdits emplacements du lit.
PCT/SE1996/000803 1995-06-21 1996-06-19 Centrale a combustible de type particulaire et son mode d'exploitation Ceased WO1997000721A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9502247-1 1995-06-21
SE9502247A SE9502247L (sv) 1995-06-21 1995-06-21 Förfarande vid samt kraftanläggning med förbränning av partikulärt bränsle

Publications (1)

Publication Number Publication Date
WO1997000721A1 true WO1997000721A1 (fr) 1997-01-09

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PCT/SE1996/000803 Ceased WO1997000721A1 (fr) 1995-06-21 1996-06-19 Centrale a combustible de type particulaire et son mode d'exploitation

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WO (1) WO1997000721A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6797473B2 (en) 1998-01-29 2004-09-28 University Of Ottawa Methods and compounds for modulating male fertility

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3417978A (en) * 1965-09-17 1968-12-24 Ube Industries Method and apparatus for the gasification and combustion of liquid fuel in a fluidized bed
EP0073650A1 (fr) * 1981-08-25 1983-03-09 Foster Wheeler Energy Corporation Echangeur de chaleur à lit fluidifié
WO1992013237A1 (fr) * 1991-01-15 1992-08-06 Abb Carbon Ab Bruleur a deux etages de gazeification et lit fluidifie equipe de moyens servant a ameliorer la distribution du combustible et des gaz

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3417978A (en) * 1965-09-17 1968-12-24 Ube Industries Method and apparatus for the gasification and combustion of liquid fuel in a fluidized bed
EP0073650A1 (fr) * 1981-08-25 1983-03-09 Foster Wheeler Energy Corporation Echangeur de chaleur à lit fluidifié
WO1992013237A1 (fr) * 1991-01-15 1992-08-06 Abb Carbon Ab Bruleur a deux etages de gazeification et lit fluidifie equipe de moyens servant a ameliorer la distribution du combustible et des gaz

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 12, No. 212, M-710; & JP,A,63 014 006 (UBE IND. LTD), 21 January 1988. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6797473B2 (en) 1998-01-29 2004-09-28 University Of Ottawa Methods and compounds for modulating male fertility

Also Published As

Publication number Publication date
SE9502247D0 (sv) 1995-06-21
SE9502247L (sv) 1996-12-22

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