US3802189A - Boiler-turbine control system - Google Patents

Boiler-turbine control system Download PDF

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Publication number
US3802189A
US3802189A US00217484A US21748472A US3802189A US 3802189 A US3802189 A US 3802189A US 00217484 A US00217484 A US 00217484A US 21748472 A US21748472 A US 21748472A US 3802189 A US3802189 A US 3802189A
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United States
Prior art keywords
signal
boiler
turbine
pressure
set point
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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
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US00217484A
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English (en)
Inventor
T Jenkins
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.)
Leeds and Northrup Co
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Leeds and Northrup Co
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Filing date
Publication date
Application filed by Leeds and Northrup Co filed Critical Leeds and Northrup Co
Priority to US00217484A priority Critical patent/US3802189A/en
Priority to IT33915/72A priority patent/IT1006563B/it
Priority to AU51021/73A priority patent/AU464493B2/en
Priority to JP48006086A priority patent/JPS605761B2/ja
Application granted granted Critical
Publication of US3802189A publication Critical patent/US3802189A/en
Anticipated expiration legal-status Critical
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
    • F01K7/10—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating characterised by the engine exhaust pressure
    • F01K7/12—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating characterised by the engine exhaust pressure of condensing type
    • F01K7/14—Control means specially adapted therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K13/00—General layout or general methods of operation of complete plants
    • F01K13/02—Controlling, e.g. stopping or starting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
    • F23N1/082—Regulating fuel supply conjointly with another medium, e.g. boiler water using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/12—Integration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/14—Differentiation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel

Definitions

  • This invention relates to a boiler-turbine control system and more particularly to a control system for controlling the boiler inputs to meet the boiler-turbine system demand while maintaining a predetermined state for the throttle valve.
  • the state of the throttle valve may, for example, be its opening or the pressure difference across it.
  • the boiler input demand signal can be obtained from the quotient of the first stage pressure in the turbine or any other indication of the steam flow through the turbine divided by the throttle pressure. Multiplying this quotient by the pressure controller set point provides the boiler demand signal for sliding pressure operation.
  • the boiler demand signal is computed as the ratio of a signal representing the steam flow in the turbine to a signal representing the throttle pressure, all multiplied by the throttle pressure set point, and the demand signal is modified by a control signal responsive to the deviation of the throttle pressure from its set point.
  • the improvement comprises means operable to modify both the throttle pressure set point and the boiler demand signal to reduce the deviation between a signal representing the desired value of a particular state of the turbine control valve and a signal representing the measured value of the particular state of the turbine control valve.
  • FIG. 1 is a block diagram of one form of a boiler control system for carrying out the present invention.
  • FIG. 2 is a block diagram showing the changes neces sary to provide one modified form of the system of FIG. 1.
  • the boiler 10 is a once through boiler provided with the usual inputs such as fuel flow through line 12 and air flow through line 16.
  • the fuel flow and air flow are combined at the burner 14 so as to provide a necessary heat input to the boiler.
  • the feedwater flow is provided through line 18.
  • the air flow input through line 16 is subject to control by the adjustment of valve 20 by controller 22 which is shown as a controller providing both proportional and integral action as noted by the block labeled PI.
  • the air flow through line 16 is measured by the flowmeter 24, which by means of the associated pressure taps responds to the pressure differential established across the flow restriction 26.
  • the fuel flow in line 12 is subject to control by the adjustment of valve 30 by controller 32 which is similar to controller 22. Also the fuel flow is measured by flowmeter 34 in accordance with the pressure drop across the orifice plate 36.
  • the feedwater flow through line 18 is subject to control by valve 40 in response to the action of a controller (not shown) which can operate to control the feedwater in any one of a number of ways known in the art.
  • Another measurement which is necessary for the control system shown in FIG. 1 is a measurement representative of the steam flow to the turbine. That measurement may be a direct measurement of steam flow or may be made by measurement of the pressure in the first stage of the turbine or another appropriate stage, which measurement is related to the flow of steam through the turbine.
  • the first stage pressure P, of the turbine is measured by the pressure measuring device which is connected by tap 72 to the first stage of turbine 68.
  • steam from the boiler 10 is supplied through a turbine control valve 90 to turbine 68.
  • the turbine 68 is mechanically coupled to the generator 74 to produce an electrical output on lines 76.
  • the power output on lines 76 is shown as being measured by a wattmeter 80 to provide on line 81 a signal representative of the actual output G of the generator G.
  • a signal G representing the desired generation for generator 74.
  • the governor mechanism represented by block 86 is mechanically coupled to the turbine-generator by coupling 84.
  • the mechanical outputs of the governor 86 through coupling 88 controls the position of the turbine control valve 90 which in turn controls the steam flow to the turbine 68.
  • Governor 86 is controlled by signals on lines 91 and 92 to cause the governor to increase or decrease the opening of valve 90 to change steam flow as required to maintain generation measured by signal G on line 81 at its desired value G through the controller 100.
  • controller 100 has both proportional and integral response. That particular controller may be of the type disclosed in US. Pat. No. 3,008,072 and may be designed so as to produce on its output lines 91 and 92 electrical pulse signals whose duration depends upon the extent of the incremental control action called for by the controller 100.
  • the signal P is subject to modification by a control system so as to maintain a particular predetermined state for the control valve 90. That state may involve the position of valve 90 or it may involve the pressure drop across valve 90 depending upon the condition which it is desirable to maintain for the type of operation required.
  • the signal provided on line 108 is representative of the power demand established for the turbine 68. That turbine power demand signal is established by dividing the measured first stage pressure P in the turbine 68 by the measured throttle pressure P, as in the dividing network shown as block 114. There is thus obtained at line 116 a signal representative of the quantity P /P,. That quantity is then multiplied in multiplier 121 by signal P, on llne 117, which signal is representative of the throttle pressure set point.
  • the signal on line 117 is established, as shown, by a control system.
  • the control system for establishing the signal on line 1 17 includes a source providing on line 120 a preset signal representing the desired opening for the valve 90 which signal may be considered as a preset value for the ratio P /P to which the actual ratio signal is compared in the comparator 115.
  • control system for producing the signal on line 117 to respond to a deviation between the signal P1/P, supplied from the divider 114 and the signal on line 120 so as to maintain those signals as nearly equal as possible by control action of controller 122 adjusting the signal P, on line 1 17, which through the boiler input control system produces a change in generation so that controller 100 will in turn adjust valve 90 thus changing the P IP, ratio.
  • the control system for adjusting the value of P may include the use of a signal for attenuating the deviation signal by the introduction of the signal G into multiplier 123 by way of line 124.
  • the deviation signal derived from the comparator 115 can be modified in accordance with the desired generation G so as to thereby determine the relative effect that the deviation signal is going to have on the control of the signal P,.
  • a signal from line 98 indicative of the deviation of the actual generation from the desired generation is added to the output of multiplier 123 by way of line 125.
  • the input to the controller 122 comprises an attenuated deviation signal indicative of the deviation of valve from the desired opening as modified by the deviation of G, from G Since the generator output deviation is controlled to zero by controller 100 the controller 122 operates to reduce to zero the deviation of the valve 90 from its desired position.
  • the output of the controller 122 is modified by the addition of a signal from line 124 into summer 126 so as to provide a control effect on the signal P, which causes the control of P, to anticipate changes in the desired generation G
  • the output of the summing junction 126 then provides an input to the limit circuits shown as block 130.
  • Those limit circuits will include means for limiting the output, namely, the signal P, representative of the pressure set point on line 117 to a maximum and a minimum value as well as limiting the rate at which that value changes.
  • the signal P thus tends to vary as a result of the operation of controller 122 within a limited range and at a limited rate so as to attempt to maintain an equality between the preset desired opening for valve 90 as established by the set point signal on line and the actual opening of the valve 90 as represented by the ratio 1 /P
  • the controller 122 serves to cause the valve 90 to return to its desired opening by modifying the signal P, which establishes a modified value of the demand signal on line 108 so that the boiler inputs will be adjusted to effect a change in generation which in turn causes valve 90 hence P /P, to change.
  • the boiler demand signal on line 108 is subject to modification in accordance with the deviation of the throttle pressure P, from its desired value, set point P
  • This modification is accomplished by utilizing the output signal of the pressure measuring device 62 which is supplied on line as an input to a comparator 141 which has as its other input the signal P, shown as being supplied on line 143.
  • the results of the comparison in the comparator 141 is a signal on line representative of the deviation of the throttle pressure P, from its set point P,.
  • the signal on line 145 is an input to the controller 142.
  • the controller 142 has proportional, integral and derivative action so as to provide an output on line 144 which is added to the signal on line 108 by the summing unit so as to provide an output on line 154 which is a modified demand signal representative of the required boiler inputs. As shown in FIG. 1, the signal on line 154 is used for controlling the energy input to the boiler 10.
  • the signal on line 154 is representative of the fuel flow to the boiler It) needed to maintain the desired pressure in the steam line 60.
  • the signal on line 154 is introduced by way of line 180 to the comparator 182 where it is compared with the actual fuel flow signal on line 184 as derived from flowmeter 34. The result of the comparison provides an error signal on line 186 which serves as an input to controller 32 so that the controller is effective to adjust the position of valve 30 to maintain the fuel flow in line 12 at a value corresponding with the fuel requirement established by the signal on line 180.
  • the desired relationship between the fuel flow and the air flow is normally controlled in response to the desired fuel-air ratio signal introduced on line 192 to a multiplier 190.
  • the output from 190 on line 204 is a signal representative of the required air flow through line 16 needed to maintain the desired air-fuel ratio when the fuel flow in line 12 is in accordance with the signal on line 180.
  • the signal on line 204 is compared with the signal on line 206 as derived from the flowmeter 24 representing the measure of the air flow in line 16.
  • the signal on line 206 is compared with the signal on line 204 by the comparator 208 and provides an output on line 210 which represents an error signal input to controller 22 so that the controller can adjust the valve 20 to modify the air flow in line 16 so as to maintain as closely as possible the air flow corresponding to the signal on line 204.
  • the opening of the valve 90 when the system is in a quiescent state will normally be set, in accordance with the signal on line 120, very near the wide open position. If, for example, a change in G; should then occur the controller 100 would cause a resetting of the governor 86 which would in turn change the opening in valve 90 in a direction to change the steam flow to the turbine 68 so as to change the output G,, of the generator so that it will equal the new value G
  • the change in the opening of valve 90 will cause a comparable change in the ratio P /P, and consequently a similar change in the demand signal P P /P, on line 108 resulting in immediate changes in boiler inputs.
  • the inputs to the boiler will then be further changed as required by controller 122 until P,/P, is at its preset value with G equal to G
  • P,/P is at its preset value with G equal to G
  • the signal on line 120 would represent the pressure drop desired across valve 90 and the signal supplied to comparator 115 on line 118 would be a measure of the actual drop AP across valve 90 instead of the ratio P,/P,.
  • AP is measured by the differential pressure instrument 97 which is connected to pipe 60 by the taps 93 and 95.
  • the function generator 127 is also added in line 129 from line 124 to characterize the set point signal on line to the comparator l 15 as a function of desired generation as may be desired.
  • a control system for a turbine-generator unit which adjusts a control valve controlling the steam flow to the turbine to tend to maintain a desired power level in the turbine-generator unit, and adjusts the inputs to the boiler in accordance with a demand signal computer as the ratio of a signal representing said steam flow to a signal representing boiler output steam pressure all multiplied by a set point for said pressure with means for modifying the demand signal until the throttle pressure returns to a predetermined set point, the combination therewith of:
  • control action is responsive to said deviation times a signal representative of the desired output of said generator.
  • control action is responsive to said deviation plus a signal representative of the difference between the desired output of said generator and its measured output.
  • control action is responsive to said deviation times a signal representative of the desired output of said generator with the addition to the resulting product of a signal representative of the difference between the desired and measured outputs of said generator.
  • control action is responsive to said deviation times a signal representative of the desired output of said generator with the addition to the resulting product of a signal representative of the difference between the desired and measured outputs of said generator and the control action is modified by the addition of said signal representative of the desired output.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Steam Boilers And Waste-Gas Boilers (AREA)
US00217484A 1972-01-13 1972-01-13 Boiler-turbine control system Expired - Lifetime US3802189A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US00217484A US3802189A (en) 1972-01-13 1972-01-13 Boiler-turbine control system
IT33915/72A IT1006563B (it) 1972-01-13 1972-12-29 Sistema di controllo per un com plesso caldaia turbina
AU51021/73A AU464493B2 (en) 1972-01-13 1973-01-11 Boiler-turbine control system
JP48006086A JPS605761B2 (ja) 1972-01-13 1973-01-12 ボイラ−タ−ビン制御システム

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00217484A US3802189A (en) 1972-01-13 1972-01-13 Boiler-turbine control system

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US3802189A true US3802189A (en) 1974-04-09

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US00217484A Expired - Lifetime US3802189A (en) 1972-01-13 1972-01-13 Boiler-turbine control system

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US (1) US3802189A (enrdf_load_stackoverflow)
JP (1) JPS605761B2 (enrdf_load_stackoverflow)
AU (1) AU464493B2 (enrdf_load_stackoverflow)
IT (1) IT1006563B (enrdf_load_stackoverflow)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3896623A (en) * 1974-03-06 1975-07-29 Leeds & Northrup Co Boiler-turbine control system
US3922859A (en) * 1974-04-30 1975-12-02 Babcock & Wilcox Co Control system for a power producing unit
US3942327A (en) * 1972-05-05 1976-03-09 Thermo Electron Corporation Control system for external combustion engine
US4146270A (en) * 1976-06-19 1979-03-27 Maschinenfabrik Augsburg-Nuremberg Aktiengesellschaft Control device for turbines with speed and load control
US4174618A (en) * 1978-04-03 1979-11-20 Leeds & Northrup Company Decoupled cascade control system
US4178763A (en) * 1978-03-24 1979-12-18 Westinghouse Electric Corp. System for minimizing valve throttling losses in a steam turbine power plant
US4213304A (en) * 1978-11-24 1980-07-22 Leeds & Northrup Company Boiler control system
US4412780A (en) * 1981-03-27 1983-11-01 General Electric Company Rate initial pressure limiter
US4461152A (en) * 1981-04-16 1984-07-24 Hitachi, Ltd. Control apparatus for steam turbine
US4482814A (en) * 1983-10-20 1984-11-13 General Signal Corporation Load-frequency control system
EP0108928A3 (en) * 1982-11-11 1985-09-25 Siemens Aktiengesellschaft Control method of a power plant
US4909037A (en) * 1989-08-31 1990-03-20 General Signal Corporation Control system for once-through boilers
US6951105B1 (en) 2004-04-20 2005-10-04 Smith Edward J Electro-water reactor steam powered electric generator system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4445180A (en) * 1973-11-06 1984-04-24 Westinghouse Electric Corp. Plant unit master control for fossil fired boiler implemented with a digital computer
JPH0653181U (ja) * 1992-05-06 1994-07-19 チャンドラー株式会社 アルバムシート

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3247671A (en) * 1963-08-22 1966-04-26 Leeds & Northrup Co Boiler-turbine control system
US3545207A (en) * 1969-07-23 1970-12-08 Leeds & Northrup Co Boiler control system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3247671A (en) * 1963-08-22 1966-04-26 Leeds & Northrup Co Boiler-turbine control system
US3545207A (en) * 1969-07-23 1970-12-08 Leeds & Northrup Co Boiler control system

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3942327A (en) * 1972-05-05 1976-03-09 Thermo Electron Corporation Control system for external combustion engine
US3896623A (en) * 1974-03-06 1975-07-29 Leeds & Northrup Co Boiler-turbine control system
US3922859A (en) * 1974-04-30 1975-12-02 Babcock & Wilcox Co Control system for a power producing unit
US4146270A (en) * 1976-06-19 1979-03-27 Maschinenfabrik Augsburg-Nuremberg Aktiengesellschaft Control device for turbines with speed and load control
US4178763A (en) * 1978-03-24 1979-12-18 Westinghouse Electric Corp. System for minimizing valve throttling losses in a steam turbine power plant
US4174618A (en) * 1978-04-03 1979-11-20 Leeds & Northrup Company Decoupled cascade control system
US4213304A (en) * 1978-11-24 1980-07-22 Leeds & Northrup Company Boiler control system
US4412780A (en) * 1981-03-27 1983-11-01 General Electric Company Rate initial pressure limiter
US4461152A (en) * 1981-04-16 1984-07-24 Hitachi, Ltd. Control apparatus for steam turbine
EP0108928A3 (en) * 1982-11-11 1985-09-25 Siemens Aktiengesellschaft Control method of a power plant
US4482814A (en) * 1983-10-20 1984-11-13 General Signal Corporation Load-frequency control system
US4909037A (en) * 1989-08-31 1990-03-20 General Signal Corporation Control system for once-through boilers
US6951105B1 (en) 2004-04-20 2005-10-04 Smith Edward J Electro-water reactor steam powered electric generator system
US20050229599A1 (en) * 2004-04-20 2005-10-20 Smith Edward J Electro-water reactor steam powered electric generator system

Also Published As

Publication number Publication date
AU5102173A (en) 1974-07-11
JPS605761B2 (ja) 1985-02-14
JPS4880928A (enrdf_load_stackoverflow) 1973-10-30
IT1006563B (it) 1976-10-20
AU464493B2 (en) 1975-08-28

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