EP0795112B1 - Method of regulating the superheating temperature of steam in a circulating fluidized bed type gas cooler - Google Patents

Method of regulating the superheating temperature of steam in a circulating fluidized bed type gas cooler Download PDF

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Publication number
EP0795112B1
EP0795112B1 EP95937910A EP95937910A EP0795112B1 EP 0795112 B1 EP0795112 B1 EP 0795112B1 EP 95937910 A EP95937910 A EP 95937910A EP 95937910 A EP95937910 A EP 95937910A EP 0795112 B1 EP0795112 B1 EP 0795112B1
Authority
EP
European Patent Office
Prior art keywords
solids
temperature
gas
mixing chamber
chamber
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
EP95937910A
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German (de)
English (en)
French (fr)
Other versions
EP0795112A1 (en
Inventor
Olli Arpalahti
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.)
Amec Foster Wheeler Energia Oy
Original Assignee
Foster Wheeler Energia Oy
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Filing date
Publication date
Application filed by Foster Wheeler Energia Oy filed Critical Foster Wheeler Energia Oy
Publication of EP0795112A1 publication Critical patent/EP0795112A1/en
Application granted granted Critical
Publication of EP0795112B1 publication Critical patent/EP0795112B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • F22B31/0084—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 with recirculation of separated solids or with cooling of the bed particles outside the combustion bed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G5/00—Controlling superheat temperature
    • 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

Definitions

  • the present invention relates to a method of regulating the superheating temperature of steam in a circulating fluidized bed type gas cooler, which comprises in the lower section thereof a mixing chamber for the circulating material and the gas to be cooled; a riser in communication with the mixing chamber; a separator in communication with the riser, for separating solids from the gases; means for introducing the separated solids into the mixing chamber; and means for generating and superheating steam; in which method hot gas is introduced into the mixing chamber, where it is mixed with solids having a temperature lower than that of the gas, whereby the temperature of the mixing chamber settles to a mixing temperature, the mixture of the gas and solids is taken to the riser and further to the solids separator where solids are separated from the gas, separated solids are thereafter introduced into the mixing chamber and, in connection with the cooling of the gas, superheated steam is generated, steam being superheated in heat transfer surfaces disposed in the riser.
  • a method is known, for example, from US-A-4 453 495.
  • a Finnish patent application 813717 (FI patent 64997) teaches cooling of gas in a circulating fluidized bed reactor. It discloses a method of recovering heat from a gas containing vaporized, molten, and eutectic components by bringing the gas into contact with heat transfer surfaces of a heat exchanger, whereby heat recovery based on so-called controlled erosion is explained to happen by lowering the gas temperature before the heat exchanger to a value below the eutectic temperature range of the melt drops so that solid particles which have cooled in the heat exchanger, separated from the gas and circulated, and possibly also other particles, are mixed with the gas.
  • Finnish patent application 843606 discloses a method of cleaning gases containing condensable components, in which method the gases are cleaned by cooling them in a circulating fluidized bed reactor so that the components condense onto the surface of solids in the reactor.
  • a conventional way of regulating the temperature of superheated steam is to divide the superheating surfaces into at least two parts and to arrange controlled steam cooling between these parts. It is common to arrange the required cooling, e.g., by injecting condensate, or by leading steam, e.g, through a heat exchanger disposed in the water space of the steam drum. A way of regulating the temperature of the superheated steam is to pass by the superheater.
  • the method of the present invention of regulating the superheating temperature of steam in a circulating fluidized bed type gas cooler is characterized by the features as defined in claim 1.
  • a circulating fluidized bed type gas cooler comprises in the lower section thereof a mixing chamber for the circulating material and the gas to be cooled; a riser in communication with the mixing chamber; a solids separator in communication with the riser, for separating solids from the gases; means for introducing the separated solids into the mixing chamber; and means for generating steam and for superheating it; whereby the gas to be cooled is introduced into the mixing chamber via a gas inlet.
  • Gas preferably serves as a fluidizing gas in the cooler.
  • the gas is mixed with solids having a temperature lower than that of the gas, whereby the temperature of the gas/solids suspension formed settles to a so-called mixing temperature.
  • the mixture of gas and solids is taken to the riser and further to a solids separator where solids are separated from the gas. Separated solids are fed to the mixing chamber.
  • the temperature of the superheated steam generated in the riser is controlled by regulating the mixing temperature in the mixing chamber, which mixing temperature again is regulated by controlling the amount and/or temperature of the solids returned to the mixing chamber.
  • the superheating temperature of the steam may be influenced by carrying out any of the following functions:
  • the superheating temperature of steam may also be influenced by cooling solids in a solids chamber so that heat is transferred from the solids to a heat transfer medium. This cooling manner speeds up the regulation of the superheating temperature.
  • the solids chamber may be provided with a bubbling fluidized bed. Solids may also be cooled simply so that the walls of the solids chamber are of a cooled construction.
  • Solid material may be cooled prior to separating it from the gas, as a gas suspension, preferably by heat transfer surfaces disposed in the riser or in the mixing chamber.
  • Fig. 1 shows an exemplary gas cooler applying the circulating fluidized bed concept, which gas cooler comprises in the lower section thereof a mixing chamber 10 for the gas to be cooled and for the circulating material, and an inlet 11 to the mixing chamber, for the gases to be cooled. Above the mixing chamber and in connection therewith is disposed a riser 13, the upper section whereof is in communication with a solids separator 20 for separating solids from the gases. Furthermore, the equipment comprises means for introducing the separated solids into the mixing chamber, which means consist of a return duct 22 and a solids chamber 26 connected in parallel therewith, and solids discharge means 24.
  • the equipment is also provided with heat transfer surfaces 12, 14, disposed in the riser, for generating steam and for superheating it, respectively, a steam drum 16, and a steam generating circulation system, equipped with a circulating pump 18.
  • a steam drum 16 disposed in the riser, for generating steam and for superheating it, respectively, a steam drum 16, and a steam generating circulation system, equipped with a circulating pump 18.
  • the above is a description of an exemplary forced steam circulation.
  • Hot gas is introduced via inlet 11 into the mixing chamber 10, where it is efficiently mixed with the solids fed to the mixing chamber.
  • Gas preferably serves as a fluidizing gas in the cooler.
  • the mixing temperature is observed by a measuring element 29, which transmits a measuring signal to a controlling member 28.
  • the gas/solids suspension being cooled by heat exchangers 12 and 14, passes via riser 13 to the upper section thereof.
  • the heat exchangers have vaporizing surface 12 and superheating surface 14. It is also possible to use other cooling surfaces, such as a preheater of feed water or an air heater in the riser.
  • the gases are led from the upper section of the riser to the solids separator 20, where solids are separated from the gas. From the separator, the gases.are taken to a further treatment via conduit 21. Solids are recirculated to the mixing chamber via return duct 22.
  • the gas cooler is also provided with a solids chamber 26, whereinto material may be led from the mass circulation and wherefrom material may be taken along with the circulation if necessary.
  • a valve 25 for controlling the feed of the material into the chamber.
  • the controlling member 28 controls the function of the valve 25.
  • the outlet conduit from the solids chamber is also provided with a valve 27, for controlling the feed of the material back to the mass circulation, preferably by means of controlling member 28.
  • New material can be introduced into the process via conduit 19, which is disposed in connection with the return duct, on the inclined portion thereof, which is in communication with the mixing chamber. Most preferably, the conduit 19 is connected with the solids chamber 26.
  • valve 1 shows a conduit to both chambers, but it is naturally sufficient to have one of the conduits.
  • Introduction of new material is also controlled by controlling member 28.
  • the above-mentioned valves are controlled by the controlling member,whereby the regulation of the superheating temperature is implemented in a very advantageous manner.
  • the chamber 26 may be used for altering the amount of circulating material.
  • the regulation of the mixing temperature may be speeded up so that more circulating material from the chamber is taken to the mass circulation or so that part of the solids from the mass circulation is led to the chamber.
  • the amount of solids (dust) contained in the gas to be cooled is so plentiful that it adds to the solids amount in the mass circulation of the cooler; in other words, the circulating fluidized bed type gas cooler separates more inlet dust to its circulation than what remains unseparated in its exhaust gases.
  • valve 24 This valve is also controlled by controlling member 28.
  • feed water is introduced into the steam drum 16 via conduit 17.
  • the steam drum is in communication with a steam generating circulation system.
  • the steam generating circulation system comprises circulating pump 18 and vaporizing surfaces 12, which vaporizing surfaces are preferably disposed in the riser 13 of the cooler.
  • the generated steam is superheated on superheating surfaces 14, which are also disposed in the riser 13.
  • the temperature of the superheated steam is kept substantially constant; the allowable deviation from the set value is normally only about +/- 5°C.
  • the superheated steam is led to the turbine generator unit 31, wherefrom condensed steam may be returned to the feed water conduit 17.
  • the regulation of the superheating temperature is so effected that, when raising the superheating temperature, solids are taken into the chamber 26 or out via discharge means 24.
  • Use of the chamber is, however, more advantageous because it lessens the need for new solids.
  • the superheating temperature is desired to be decreased by increasing the amount of solids in the mass circulation, solids are taken from chamber 26.
  • the amount of solids in chamber 26 is maintained at a suitable level by feeding more solids to the chamber or by discharging them. In the cases in which the amount of circulating mass increases because of the new material entrained with the gas, solids have to be discharged from the circulation.
  • Fig. 2 shows an exemplary arrangement which is mainly similar to the arrangement shown in Fig. 1, but it illustrates vaporizing surfaces 12' as part of the structure of the equipment itself, and the steam circulation is arranged as a so-called natural circulation. It is appreciated from Fig. 2 that the wall of the riser 13 forms vaporizing surface 12'. Also other parts of the cooler may be of a cooled construction. In Fig. 2, superheating surface 14' is arranged in connection with the mixing chamber. This arrangement is exemplary and, e.g., the surfaces may naturally be disposed in different ways.
  • Fig. 2 additionally shows a heat transfer element 32 disposed in chamber 26, which heat transfer element is capable, e.g., of cooling solids in chamber 26 if this is necessary for the regulation of superheated steam.
  • the chamber is preferably provided with feeding means 33 for fluidizing gas.
  • the regulation of the steam superheating temperature may thus be speeded up by cooling solids in the solids chamber 26 so that heat is transferred from the solids to a heat transfer medium, which flows inside the element 32.
  • the solids chamber is preferably provided with a bubbling fluidized bed by bringing fluidizing gas thereinto by feeding means 33.
  • Feeding means 33 preferably comprise a gas distribution plate or a grate, below which is a gas distribution chamber, whereinto fluidizing gas is introduced in a controlled manner; if desired, fluidizing does not exist in this arrangement at all.
  • new material is introduced into the process via conduit 19 direct to the mixing chamber.
  • Controlling member 28 also controls the function of conduit 19.
  • Figs. 1 and 2 illustrate controlling members 24, 25 and 27 as valves, but it is, however, clear that these can also be arranged non-mechanically if so desired, whereby they utilize, e.g., the solids bed/column for bringing about a valve effect.
  • the superheating surfaces 14, 14' may be disposed in the most appropriate place in the equipment; they need not necessarily be integrated in the riser wall or in the mixing chamber of the gas cooler.
  • the vaporizing and superheating surfaces may also be disposed one after the other in the riser.
  • controlling member 28 which has connections with at least the following elements: conduit 19 for introducing new material into the mixing chamber, solids chamber or return duct; valve 25 disposed in the feeding conduit of the solids chamber; valve 27 disposed in the outlet conduit of the solids chamber and solids discharge means 24; sensing element 29 measuring the temperature of the mixing chamber; and sensing element 30 measuring the temperature of superheated steam.
  • controlling member 28 the temperature of superheated steam is regulated by controlling member 28, whereby control signals are transmitted from the controlling member to at least the following elements: conduit 19 for introducing new material into the mixing chamber or return duct; valve 25 disposed in the feeding conduit of the solids chamber; valve 27 disposed in the outlet conduit of the solids chamber and solids discharge means 24; and which controlling member 28 receives measuring signals from at least the sensing element 29 measuring the temperature of the mixing chamber and from the sensing element 30 measuring the temperature of superheated steam.
  • the method for regulating the temperature of superheated steam can advantageously by used when cooling high temperature process gases generated in e.g. combustion processes, metallurgical smelting processes or chemical processes.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)
  • Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
  • Control Of Temperature (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
EP95937910A 1994-12-05 1995-11-14 Method of regulating the superheating temperature of steam in a circulating fluidized bed type gas cooler Expired - Lifetime EP0795112B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI945737 1994-12-05
FI945737A FI945737A7 (fi) 1994-12-05 1994-12-05 Menetelmä höyryn tulistuslämpötilan säätämiseksi kiertopetityyppisessä kaasunjäähdyttimessä
PCT/FI1995/000627 WO1996018076A1 (en) 1994-12-05 1995-11-14 Method of regulating the superheating temperature of steam in a circulating fluidized bed type gas cooler

Publications (2)

Publication Number Publication Date
EP0795112A1 EP0795112A1 (en) 1997-09-17
EP0795112B1 true EP0795112B1 (en) 1999-01-13

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ID=8541931

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Application Number Title Priority Date Filing Date
EP95937910A Expired - Lifetime EP0795112B1 (en) 1994-12-05 1995-11-14 Method of regulating the superheating temperature of steam in a circulating fluidized bed type gas cooler

Country Status (9)

Country Link
EP (1) EP0795112B1 (enrdf_load_stackoverflow)
JP (1) JPH10500477A (enrdf_load_stackoverflow)
AT (1) ATE175772T1 (enrdf_load_stackoverflow)
AU (1) AU681547B2 (enrdf_load_stackoverflow)
CA (1) CA2205982A1 (enrdf_load_stackoverflow)
DE (1) DE69507337D1 (enrdf_load_stackoverflow)
FI (1) FI945737A7 (enrdf_load_stackoverflow)
TW (1) TW280858B (enrdf_load_stackoverflow)
WO (1) WO1996018076A1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6612250B2 (en) 2001-04-02 2003-09-02 Einco Oy Method of controlling the temperature of a reaction carried out in a fluidised bed reactor

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10260943B3 (de) * 2002-12-20 2004-08-19 Outokumpu Oyj Verfahren und Anlage zur Regelung von Temperatur und/oder Materialeintrag in Reaktoren
US8764350B2 (en) † 2008-06-05 2014-07-01 Alstom Technology Ltd Conveyor for transporting powder, and a method for conveying powder

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4312301A (en) * 1980-01-18 1982-01-26 Battelle Development Corporation Controlling steam temperature to turbines
DE3125849A1 (de) * 1981-07-01 1983-01-20 Deutsche Babcock Anlagen Ag, 4200 Oberhausen Dampferzeuger mit zirkulierender atmosphaerischer oder druckaufgeladener wirbelschichtfeuerung sowie verfahren zu seiner regelung
CA1225292A (en) * 1982-03-15 1987-08-11 Lars A. Stromberg Fast fluidized bed boiler and a method of controlling such a boiler
FR2526182B1 (fr) * 1982-04-28 1985-11-29 Creusot Loire Procede et dispositif de controle de la temperature d'un lit fluidise
US4453495A (en) * 1983-03-23 1984-06-12 Electrodyne Research Corporation Integrated control for a steam generator circulating fluidized bed firing system
US4672918A (en) * 1984-05-25 1987-06-16 A. Ahlstrom Corporation Circulating fluidized bed reactor temperature control

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6612250B2 (en) 2001-04-02 2003-09-02 Einco Oy Method of controlling the temperature of a reaction carried out in a fluidised bed reactor

Also Published As

Publication number Publication date
AU681547B2 (en) 1997-08-28
EP0795112A1 (en) 1997-09-17
WO1996018076A1 (en) 1996-06-13
CA2205982A1 (en) 1996-06-13
FI945737A0 (fi) 1994-12-05
TW280858B (enrdf_load_stackoverflow) 1996-07-11
DE69507337D1 (de) 1999-02-25
FI945737A7 (fi) 1996-06-06
JPH10500477A (ja) 1998-01-13
ATE175772T1 (de) 1999-01-15
AU3873695A (en) 1996-06-26

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