US20090183660A1 - Method for controlling the combustion air supply in a steam generator that is fueled with fossil fuels - Google Patents

Method for controlling the combustion air supply in a steam generator that is fueled with fossil fuels Download PDF

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Publication number
US20090183660A1
US20090183660A1 US12/308,976 US30897607A US2009183660A1 US 20090183660 A1 US20090183660 A1 US 20090183660A1 US 30897607 A US30897607 A US 30897607A US 2009183660 A1 US2009183660 A1 US 2009183660A1
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United States
Prior art keywords
air
combustion
air supply
flue gas
combustion zone
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.)
Abandoned
Application number
US12/308,976
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English (en)
Inventor
Friedhelm Wessel
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General Electric Technology GmbH
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Individual
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Filing date
Publication date
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Assigned to ALSTOM TECHNOLOGY LTD. reassignment ALSTOM TECHNOLOGY LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: WESSEL, FRIEDHELM
Publication of US20090183660A1 publication Critical patent/US20090183660A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N3/00—Regulating air supply or draught
    • F23N3/002—Regulating air supply or draught using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B35/00—Control systems for steam boilers
    • F22B35/007—Control systems for waste heat boilers
    • 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 
    • F23C6/00—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion
    • F23C6/04—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection
    • F23C6/045—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure
    • F23C6/047—Combustion apparatus characterised by the combination of two or more combustion chambers or combustion zones, e.g. for staged combustion in series connection with staged combustion in a single enclosure with fuel supply in stages
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L9/00—Passages or apertures for delivering secondary air for completing combustion of fuel 
    • F23L9/04—Passages or apertures for delivering secondary air for completing combustion of fuel  by discharging the air beyond the fire, i.e. nearer the smoke outlet
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/003—Systems for controlling combustion using detectors sensitive to combustion gas properties
    • F23N5/006—Systems for controlling combustion using detectors sensitive to combustion gas properties the detector being sensitive to oxygen
    • 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 
    • F23C2201/00—Staged combustion
    • F23C2201/10—Furnace staging
    • F23C2201/101—Furnace staging in vertical direction, e.g. alternating lean and rich zones
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2237/00—Controlling
    • F23N2237/16—Controlling secondary air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2241/00—Applications
    • F23N2241/10—Generating vapour

Definitions

  • the invention relates to a method for controlling the combustion air supply on a steam generator fired with fossil fuels in which the combustion air is added in stages in a plurality of combustion zones arranged one after another in the direction of the flue gas flow and in which the combustion air supply is also measured out as a function of the amount of fuel.
  • An air supply in stages of this type is known for example in the firing system of steam generators operated with pulverized lignite.
  • limit values must in any event be kept for the emission of nitrogen oxides and carbon monoxide.
  • the firing system must be optimized in terms of efficiency; in other words, the fuel consumption and CO 2 emissions should be as low as possible.
  • the oxygen concentration in the flue gas is an indicator for the flue gas amount; the carbon monoxide content in the flue gas should not exceed certain limits.
  • each air feed into the boiler was controlled by means of an air curve stored in a controller for the corresponding air feed.
  • the air curve showed the amount of air required relative to the firing rate of the boiler.
  • the air curves were indeed related to each other in process engineering terms, however they generally were processed in isolation from each other. When the air curves were modified on the basis of changed burning conditions, all of the settings had to be recalculated and reinput. This is particularly complex with respect to control technology.
  • the object of the invention is to improve a method of the type referred to above with respect to control stability.
  • the method of the invention should permit the steam generator to be operated with a flue gas quantity that is as constant as possible.
  • the object of the invention is achieved by a method of the type referred to above, which is characterized by the fact that control of the combustion air supply as a function of the NOx and/or CO concentration in the flue gas is carried out in such a way that at first a variation in the air supply between the various combustion zones is achieved with an approximately constant amount of air.
  • the invention may be summarized as follows: In the invention an internal control and an external control of NOx and/or CO is provided and these controls interact with each other so that, when there are NOx/CO fluctuations/deviations, at first the air supply between the individual combustion zones is varied while the amount of air remains largely constant.
  • the total air demand of the steam generator is also determined on the basis of the required fuel amounts and the calorific value of the fuels.
  • the air supply is varied by means of at least three combustion zones that are disposed in a series in the direction of flue gas flow.
  • the air supply in a first combustion zone seen in the direction of flue gas flow is reduced, and the air supply in the last combustion zone seen in the direction of flue gas flow is increased correspondingly.
  • the air supply in the next upstream combustion zone can be increased. Conversely, the air supply in the next upstream combustion zone may be decreased as needed.
  • the amount of air that is supplied to each combustion zone is determined as a function of an air/fuel ratio (A number) that is specified for each combustion zone.
  • a number an air/fuel ratio
  • the air/fuel ratio of each combustion zone may be specified, for example, as a function of the firing rate/load.
  • a version of the method in which the total air demand of the firing system is determined for the last combustion zone by means of the air/fuel ratio of this combustion zone using a fuel-specific air demand and the fuel mass flow is preferred.
  • the oxygen concentration in the flue gas downstream from the firing system is calculated on the basis of the air/fuel ratio specified for the last combustion zone.
  • the oxygen concentration calculated in this manner may be used as a setpoint for an external control of the total amount of air.
  • the external control of the total amount of air is achieved by comparing a measured oxygen concentration downstream from the boiler with a calculated oxygen concentration that is obtained, as will be explained below, exclusively from the air/fuel ratio specified for the last combustion zone.
  • the fuel-specific air demand is advantageously determined by means of a continuous fuel analysis.
  • the invention also relates to a method for the control in a lignite-fired boiler of claim 1 , wherein the fuel and at least one first partial stream of the combustion air is fed into burner stage as a first combustion stage of a combustion chamber and at least one additional partial stream of the combustion air is fed in as overfire air downstream in the direction of flue gas flow in at least one downstream overfire stage.
  • Each of the combustion stages including the burner stage forms a combustion zone and a variation of the air supply takes place across at least three combustion stages including the burner stage.
  • the burner stage forms the first combustion stage of the boiler, and a plurality of pulverized fuel burners are disposed there mostly above one another.
  • this area of the boiler is referred to as a burner stage or a first combustion stage; however, in strict geometrical terms this is not a single stage, but rather the lower area of the combustion seam of the boiler.
  • control scheme in accordance with the invention may be applied to any firing system using fossil fuels with air supply in stages and that the type of fuel being burned basically does not constitute a limitation upon the method.
  • the control scheme in accordance with the invention may be applied to any firing system using fossil fuels with air supply in stages and that the type of fuel being burned basically does not constitute a limitation upon the method.
  • the use of air stages within the burner is known.
  • the object of such a air supply in stages is also to minimize NOx emissions as well as CO emissions; here the goal is to improve the control stability of the air supply in stages with respect to steam generator efficiency fluctuations.
  • FIG. 1 a graphical representation of the effects of the control scheme upon which the invention is based
  • FIG. 2 a graphical representation of the air mass flow fed into the steam generator
  • FIG. 3 a schematic diagram of an air control system on a steam generator in accordance with the invention.
  • burners are arranged in groups, mostly above one another, in the boiler of the steam generator. Combustion takes place in the immediate vicinity of the burner flames as well as above the burner flames that extend into the boiler.
  • the combustion chamber of the boiler is divided into three combustion stages, whereby a first combustion stage is formed by the burner stage, a second combustion stage is defined by overfire air feed 1 (OFA 1 ), and a third combustion stage is defined by overfire air feed 2 (OFA 2 ).
  • the amount of air required for combustion may be added in stages and a partial stream of the combustion air may be added with the primary and secondary air from the burners of the firing system, a further partial stream of the combustion air may be fed in as overfire air 1 in the overfire stage located above the burner stage, and an additional partial stream may be fed in downstream in the direction of flue gas flow as overfire air 2 in the third combustion stage.
  • the total amount of the air fed into the steam generator is determined as a function of the fuel mass flow and the quality of fuel used and also as a function of the NOx and CO emissions from the steam generator.
  • the air supply is at first varied within the various combustion stages as a function of the measured NOx/CO emissions.
  • the purpose of this control system is to keep the total amount of air supplied to the steam generator as constant as possible, within certain limits, at a particular firing rate.
  • an air/fuel ratio curve is stored for each combustion stage (see the upper diagram in FIG. 1 ), in other words the desired air/fuel ratio is specified as a function of firing rate.
  • the air demand of the individual combustion stage is determined from the air/fuel ratio relative to the firing rate at which the unit is running.
  • a total amount of air at the end of the combustion chamber is determined based on the air/fuel ratio in the last combustion stage (air/fuel ratio OFA 2 ) and a fuel-specific air amount as well as the fuel mass flow.
  • an NOx controller which reduces the secondary air at the burners when a specified NOx setpoint is exceeded and adds the reduced amount of secondary to the overfire air 2 , is provided downstream from the boiler.
  • a specified CO setpoint is exceeded, the overfire airflow rate in OFA 2 is reduced stepwise in the direction of the burner, if possible while maintaining the NOx setpoint, and the amount of air that is reduced with OFA 2 is added to the secondary air stream of the burner.
  • the required amount of air determined at any given combustion stage in each case is determined as the total amount of air subtracting the already added amount of air.
  • the setpoint for the overfire air 1 is then determined from the stored air/fuel ratio for overfire air 1 , and the amount of air that is already added up to this stage (essentially the burner air amount) is subtracted from the calculated value.
  • the calculation for overfire air 2 proceeds in a similar manner. Here the overfire air 1 and the burner air amount are subtracted from the calculated total airflow.
  • the calculated value is used as the setpoint for the external control of the total amount of air downstream from the boiler, and the oxygen content is used as an indicator of the total amount of flue gas emitted.
  • a setpoint for the oxygen concentration of the flue gas is determined from the calculated air/fuel ratio for the last combustion stage, the storage of setpoint curves for the oxygen concentration of the flue gas as a function of the firing rate of the boiler becomes unnecessary.
  • the respective value is represented as the function generator f(x) in the control scheme in FIG.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Regulation And Control Of Combustion (AREA)
US12/308,976 2006-07-07 2007-07-05 Method for controlling the combustion air supply in a steam generator that is fueled with fossil fuels Abandoned US20090183660A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102006031900.1 2006-07-07
DE102006031900A DE102006031900A1 (de) 2006-07-07 2006-07-07 Verfahren zur Regelung der Verbrennungsluftzufuhr an einem mit fossilen Brennstoffen befeuerten Dampferzeuger
PCT/DE2007/001184 WO2008003304A1 (de) 2006-07-07 2007-07-05 Verfahren zur regelung der verbrennungsluftzufuhr an einem mit fossilen brennstoffen befeuerten dampferzeuger

Publications (1)

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US20090183660A1 true US20090183660A1 (en) 2009-07-23

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US12/308,976 Abandoned US20090183660A1 (en) 2006-07-07 2007-07-05 Method for controlling the combustion air supply in a steam generator that is fueled with fossil fuels

Country Status (5)

Country Link
US (1) US20090183660A1 (de)
EP (1) EP2038583A1 (de)
CN (1) CN101490476B (de)
DE (1) DE102006031900A1 (de)
WO (1) WO2008003304A1 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110048295A1 (en) * 2008-03-06 2011-03-03 Ihi Corporation Method and facility for feeding carbon dioxide to oxyfuel combustion boiler
US20110126742A1 (en) * 2008-03-06 2011-06-02 Ihi Corporation Method and apparatus of controlling flow rate of primary recirculating exhaust gas in oxyfuel combustion boiler
US20110212404A1 (en) * 2008-11-25 2011-09-01 Utc Fire & Security Corporation Automated setup process for metered combustion control systems
US20160146463A1 (en) * 2013-07-09 2016-05-26 Mitsubishi Hitachi Power Systems, Ltd. Combustion device

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006022657B4 (de) * 2006-05-12 2011-03-03 Alstom Technology Ltd. Verfahren und Anordnung zur Luftmengen-Regelung eines mit fossilen, festen Brennstoffen betriebenen Verbrennungssystems
JP5451455B2 (ja) * 2010-03-01 2014-03-26 大陽日酸株式会社 バーナの燃焼方法
CN103574580B (zh) * 2013-11-15 2015-07-01 神华集团有限责任公司 一种火电机组NOx排放监控方法及***
CN103574581B (zh) * 2013-11-15 2015-07-01 神华集团有限责任公司 一种火电机组NOx燃烧优化方法及***
CN105509035B (zh) * 2016-02-02 2018-11-20 华北电力科学研究院有限责任公司 一种确定对冲燃烧进风量的方法、装置及自动控制***
CN105485714B (zh) * 2016-02-02 2017-12-15 华北电力科学研究院有限责任公司 一种确定锅炉运行氧量的方法、装置及自动控制***
AT523384B1 (de) 2020-02-20 2021-08-15 Maggale Ing Anton Verfahren zum Verbrennen von Brennstoff
CN114791102B (zh) * 2022-04-21 2023-09-22 中国矿业大学 一种基于动态运行数据分析的燃烧优化控制方法

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US4403941A (en) * 1979-08-06 1983-09-13 Babcock-Hitachi, Ltd. Combustion process for reducing nitrogen oxides
US4515094A (en) * 1982-12-27 1985-05-07 Hitachi, Ltd. Fuel jet method and apparatus for pulverized coal burner
US4622922A (en) * 1984-06-11 1986-11-18 Hitachi, Ltd. Combustion control method
US5020454A (en) * 1990-10-31 1991-06-04 Combustion Engineering, Inc. Clustered concentric tangential firing system
US5280756A (en) * 1992-02-04 1994-01-25 Stone & Webster Engineering Corp. NOx Emissions advisor and automation system
US5626085A (en) * 1995-12-26 1997-05-06 Combustion Engineering, Inc. Control of staged combustion, low NOx firing systems with single or multiple levels of overfire air
US6164221A (en) * 1998-06-18 2000-12-26 Electric Power Research Institute, Inc. Method for reducing unburned carbon in low NOx boilers
US7401577B2 (en) * 2003-03-19 2008-07-22 American Air Liquide, Inc. Real time optimization and control of oxygen enhanced boilers

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US6237513B1 (en) * 1998-12-21 2001-05-29 ABB ALSTROM POWER Inc. Fuel and air compartment arrangement NOx tangential firing system
DE60309301T2 (de) * 2002-04-03 2007-06-06 Keppel Seghers Holdings Pte.Ltd. Verfahren und vorrichtung zur regelung der primär- und sekundärlufteinspritzung einer müllverbrennungsanlage
CN1548805A (zh) * 2003-05-15 2004-11-24 株式会社庆东Boiler 空气比例控制锅炉

Patent Citations (9)

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Publication number Priority date Publication date Assignee Title
US4403941A (en) * 1979-08-06 1983-09-13 Babcock-Hitachi, Ltd. Combustion process for reducing nitrogen oxides
US4403941B1 (de) * 1979-08-06 1988-07-26
US4515094A (en) * 1982-12-27 1985-05-07 Hitachi, Ltd. Fuel jet method and apparatus for pulverized coal burner
US4622922A (en) * 1984-06-11 1986-11-18 Hitachi, Ltd. Combustion control method
US5020454A (en) * 1990-10-31 1991-06-04 Combustion Engineering, Inc. Clustered concentric tangential firing system
US5280756A (en) * 1992-02-04 1994-01-25 Stone & Webster Engineering Corp. NOx Emissions advisor and automation system
US5626085A (en) * 1995-12-26 1997-05-06 Combustion Engineering, Inc. Control of staged combustion, low NOx firing systems with single or multiple levels of overfire air
US6164221A (en) * 1998-06-18 2000-12-26 Electric Power Research Institute, Inc. Method for reducing unburned carbon in low NOx boilers
US7401577B2 (en) * 2003-03-19 2008-07-22 American Air Liquide, Inc. Real time optimization and control of oxygen enhanced boilers

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110048295A1 (en) * 2008-03-06 2011-03-03 Ihi Corporation Method and facility for feeding carbon dioxide to oxyfuel combustion boiler
US20110126742A1 (en) * 2008-03-06 2011-06-02 Ihi Corporation Method and apparatus of controlling flow rate of primary recirculating exhaust gas in oxyfuel combustion boiler
US8490556B2 (en) * 2008-03-06 2013-07-23 Ihi Corporation Method and facility for feeding carbon dioxide to oxyfuel combustion boiler
US8550016B2 (en) * 2008-03-06 2013-10-08 Ihi Corporation Method and apparatus of controlling flow rate of primary recirculating exhaust gas in oxyfuel combustion boiler
US20110212404A1 (en) * 2008-11-25 2011-09-01 Utc Fire & Security Corporation Automated setup process for metered combustion control systems
US9028245B2 (en) * 2008-11-25 2015-05-12 Utc Fire & Security Corporation Automated setup process for metered combustion control systems
US20160146463A1 (en) * 2013-07-09 2016-05-26 Mitsubishi Hitachi Power Systems, Ltd. Combustion device
US10359193B2 (en) * 2013-07-09 2019-07-23 Mitsubishi Hitachi Power Systems, Ltd. Combustion device

Also Published As

Publication number Publication date
DE102006031900A1 (de) 2008-01-10
CN101490476A (zh) 2009-07-22
WO2008003304A1 (de) 2008-01-10
EP2038583A1 (de) 2009-03-25
CN101490476B (zh) 2014-05-28

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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:WESSEL, FRIEDHELM;REEL/FRAME:022060/0140

Effective date: 20081214

STCB Information on status: application discontinuation

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