EP0108586B1 - Reducing losses in combustion operations - Google Patents

Reducing losses in combustion operations Download PDF

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Publication number
EP0108586B1
EP0108586B1 EP83306625A EP83306625A EP0108586B1 EP 0108586 B1 EP0108586 B1 EP 0108586B1 EP 83306625 A EP83306625 A EP 83306625A EP 83306625 A EP83306625 A EP 83306625A EP 0108586 B1 EP0108586 B1 EP 0108586B1
Authority
EP
European Patent Office
Prior art keywords
loss
unburned
combustion operation
opacity
air
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
Application number
EP83306625A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0108586A1 (en
Inventor
Marion A. Keyes, Iv
Michael P. Lukas
Robert E. Pocock
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.)
Babcock and Wilcox Co
Original Assignee
Babcock and Wilcox Co
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 Babcock and Wilcox Co filed Critical Babcock and Wilcox Co
Publication of EP0108586A1 publication Critical patent/EP0108586A1/en
Application granted granted Critical
Publication of EP0108586B1 publication Critical patent/EP0108586B1/en
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/02—Regulating fuel supply conjointly with air supply
    • F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/08—Measuring temperature
    • F23N2225/10—Measuring temperature stack temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/22—Measuring heat losses
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/22—Measuring heat losses
    • F23N2225/24—Measuring heat losses indicated in an amount of money
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2231/00—Fail safe
    • F23N2231/20—Warning devices

Definitions

  • This invention relates to methods of and apparatus for reducing losses in a combustion operation (e.g. in a boiler, heater, or other device) for burning fuel with air at a load level with the combustion operation producing flue gas having unburned by-product and oxygen and being at a stack temperature.
  • a combustion operation e.g. in a boiler, heater, or other device
  • the deviation of CO from its preselected set point is used to adjust the set point of an oxygen (0 2 ) controller in a cascade fashion.
  • excess air is adjusted to control, to a preselected combustibles set point, until the oxygen moves outside preselected limits.
  • the the control mode is switched to bring the oxygen back within limits at which point combustibles control is resumed.
  • UK Patent Application Publication No. GB-A-2 064 780 discloses apparatus for measuring the efficiency of combustion appliances.
  • the temperature of flue gas resulting from combustion of a fuel in the appliance is measured.
  • either the oxygen or carbon dioxide content of the flue gas is measured.
  • the efficiency of the appliance can be determined by computing the heat loss or stack loss of the flue gas.
  • the stack loss can be computed from a formula in which the temperature and oxygen measurements are variables or from a formula in which the temperature and carbon dioxide measurements are variables.
  • a preliminary boiler analysis is carried out to select a simplified equation or model approximately defining the boiler efficiency.
  • the equation may employ a heat loss method, according to which the equation contains variables including the stack temperature and the amount of oxygen in the flue gas.
  • an optimisation algorithm or program is selected to distribute the loads among individual boilers in such a way that a given steam demand is satisfied at a minimum cost.
  • the present invention provides a method of reducing losses in a combustion operation for burning fuel with air at a load level with the combustion operation producing flue gas having unburned by-product and oxygen and being at a stack temperature, the method comprising:
  • the invention also provides apparatus for reducing losses in a combustion operation for burning fuel with air at a load level with the combustion operation producing flue gas having unburned by-product and oxygen and being at a stack temperature, the apparatus comprising:
  • the preferred embodiment operates by effecting measurements of excess air and of each of the combustibles elements. These are multiplied by a boiler/heater load index to produce a "rate of loss" estimate for each element. These rates are multiplied by appropriate economic factors to convert them into the "dollars lost" per unit time of operation, and then added together to produce a combined loss index. The air/fuel ratio is then adjusted during on-line operation to search for the minimum value of this loss index.
  • the economic impact of violating regulations on smoke emissions e.g. those of the U.S. Government Environmental Protection Agency or "EPA" is taken into account by significantly increasing the rate of penalising the opacity component as it approaches the EPA limit.
  • the preferred apparatus described below is simple in design, rugged in construction, and economical to manufacture.
  • the cost of heating excess air is estimated by using measurements of stack temperature from a transmitter 30 and oxygen from a transmitter 32 in flue gas produced by a combustion operation in which fuel is burnt with air at a load level.
  • a function generator 34 and a multiplier 36 convert these measurements into an effective heat value of the excess air.
  • This value is multiplied in a multiplier 42 by a boiler/heater load index provided on a tine 38. tn this case this vatue is fuel demand as measured in a fuel demand transmitter 40. It could also be steam flow in a boiler or product flow in a process heater.
  • the multiplier 42 thus generates a heat loss rate, which is then multiplied by a K$ factor in a multiplier 44 to convert the loss rate into an air heating loss per unit time in dollars.
  • CO and HC measurements are multiplied by the load index and the K$ factors in multipliers 52, 54, 56 and 58, to generate a fuel loss rate per unit time.
  • the opacity measurement is handled in the same way, except that a function generator 60 is used instead of a simple K$ multiplication factor.
  • the function generator 60 sharply increases the effective K$ factor when the opacity approaches an allowed EPA limit L, then settles out at the magnitude of the fine when the limit is reached or exceeded.
  • All of the combustibles loss rates then are added together in a summing unit 62 and smoothed (filtered in time) in a smoothing filter to generate a total fuel loss rate in dollars per unit time.
  • the summing unit 62 thus generates a total of the unburned by-product loss and loss due to a characteristic of the flue gas (opacity) which may cause a fine.
  • the air and fuel loss rates are fed into a "Loss Index Minimisation Algorithm” block 64 shown in Figure 1.
  • a "high opacity alarm” is generated by a limit and alarm unit 66 when the opacity exceeds the EPA limit. This alarm and the load index are also fed into the minimisation algorithm block 64.
  • Air demand is set by an optimum air demand value provided on a line 70 from the block 64.
  • the operation of the "Loss Index Minimisation Algorithm" block 64 is illustrated in Figures 2 and 3.
  • the block 64 keeps track of the "best previous" values of air demand that have been found for each value of load index ( Figure 2). Also, the corresponding dollar values of air heating loss, fuel loss, and total loss (the sum of the other two losses) are stored for each load index value ( Figure 3).
  • the minimisation algorithm searches for the minimum value of the total loss parameter by adjusting the air demand output from the block. The algorithm increases or decreases the air demand, depending on the deviation ofthe current values of air and fuel losses from the corresponding "best previous" values stored.
  • the algorithm will reduce the air demand.
  • the algorithm will increase the air demand.
  • the algorithm measures the new value of the total loss parameter. If it is less than the stored "best previous" value for the current load index, the new air demand replaces the old one as the "best previous” value. Also, the corresponding new loss parameters then replace the old ones and the search continues incrementally in the same direction until a minimum is found as shown at M in Figure 3.
  • the optimisation algorithm operates as described only under "normal" operating conditions as defined above. If the load index is changing, the optimisation operation is suspended and the air demand output is adjusted to match the "best previous" value stored for the current load index. If the load index is stable but the "high opacity" alarm is active, the loss minimisation operation still continues, but the "best previous" air demand and lossvaluesfound under these alarm conditions are discarded after the alarm becomes inactive. This is done because the fuel loss parameter is made artificially high during these alarm conditions. Therefore, its value is not relevant under normal operating conditions.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)
  • Feedback Control In General (AREA)
EP83306625A 1982-11-01 1983-10-31 Reducing losses in combustion operations Expired EP0108586B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43821682A 1982-11-01 1982-11-01
US438216 1982-11-01

Publications (2)

Publication Number Publication Date
EP0108586A1 EP0108586A1 (en) 1984-05-16
EP0108586B1 true EP0108586B1 (en) 1988-06-01

Family

ID=23739730

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83306625A Expired EP0108586B1 (en) 1982-11-01 1983-10-31 Reducing losses in combustion operations

Country Status (10)

Country Link
EP (1) EP0108586B1 (enrdf_load_stackoverflow)
JP (2) JPS59131824A (enrdf_load_stackoverflow)
KR (1) KR880001507B1 (enrdf_load_stackoverflow)
BR (1) BR8306128A (enrdf_load_stackoverflow)
CA (1) CA1197011A (enrdf_load_stackoverflow)
DE (1) DE3376871D1 (enrdf_load_stackoverflow)
ES (1) ES526800A0 (enrdf_load_stackoverflow)
HK (1) HK98988A (enrdf_load_stackoverflow)
IN (1) IN160113B (enrdf_load_stackoverflow)
MX (1) MX168154B (enrdf_load_stackoverflow)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4308055A1 (de) * 1993-03-13 1994-09-15 Rwe Entsorgung Ag Verfahren zur Regelung thermischer Prozesse
KR20040019462A (ko) * 2002-08-28 2004-03-06 김은기 보일러 최적연소를 위한 미연탄소 및 공기댐퍼 제어 시스템
KR101021293B1 (ko) * 2008-10-02 2011-03-11 한국전력공사 순 산소 보일러 연소 가스 물성 자동계산 시스템 및 방법
KR101237995B1 (ko) * 2010-10-29 2013-02-27 한국전력공사 보일러 최적 효율 유지 장치 및 방법
CN103256623B (zh) * 2012-02-20 2015-06-17 宝山钢铁股份有限公司 一种灵活控制脉冲烧嘴空气过剩系数的方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2021815B (en) * 1978-05-24 1983-01-26 Land Pyrometers Ltd Automatic control of burnes
GB2064780B (en) * 1979-11-23 1984-04-18 Neotronics Ltd Apparatus for measuring the efficiency of combustion appliances
US4360336A (en) * 1980-11-03 1982-11-23 Econics Corporation Combustion control system
JPS57174620A (en) * 1981-04-20 1982-10-27 Sumitomo Metal Ind Ltd Combustion control system
JPS57174618A (en) * 1981-04-22 1982-10-27 Fuji Electric Co Ltd Control system for variable spped fan in combustion equipment
AU559412B2 (en) * 1981-12-10 1987-03-12 International Control Automation Finance Sa Steam generator on-line efficiency monitor

Also Published As

Publication number Publication date
ES8501511A1 (es) 1984-12-01
DE3376871D1 (en) 1988-07-07
BR8306128A (pt) 1984-06-12
IN160113B (enrdf_load_stackoverflow) 1987-06-27
CA1197011A (en) 1985-11-19
KR880001507B1 (ko) 1988-08-16
MX168154B (es) 1993-05-06
KR840007168A (ko) 1984-12-05
ES526800A0 (es) 1984-12-01
EP0108586A1 (en) 1984-05-16
JPS59131824A (ja) 1984-07-28
JPH0356040U (enrdf_load_stackoverflow) 1991-05-29
HK98988A (en) 1988-12-16

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