US3908897A - Off-line integration of bridge and boiler controls - Google Patents
Off-line integration of bridge and boiler controls Download PDFInfo
- Publication number
- US3908897A US3908897A US428286A US42828673A US3908897A US 3908897 A US3908897 A US 3908897A US 428286 A US428286 A US 428286A US 42828673 A US42828673 A US 42828673A US 3908897 A US3908897 A US 3908897A
- Authority
- US
- United States
- Prior art keywords
- signal
- steam
- generator
- flow
- control
- 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
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B35/00—Control systems for steam boilers
Definitions
- SIGNAL GENERATOR B FIG 2 1 1 SIGNAL l I GENERATOR '6 1 "w 1 T 22 AOOER ADDER Q l l 5 i PI A P 73 l i cOMPuTER CON- T" CON l TROLLER TROLLER l l 20 1 FLOW FLOW FIG. 4
- the invention relates to a process for the automatic control of a steam generator with varying load and an apparatus for carrying out the process,
- a steam generator with varying load requires special measures to be taken in order to rapidly adapt the steam production to the varying demand. Under varying load there is a chance that the heat production and, hence, the steam production, may lag very much behind variations in the demand for steam. Lagging will result in large variations in steam pressure and when the pressure rises excessively, losses may occur. When the pressure is too low, it may be impossible to supply the quantity of steam required. Problems of this kind are encountered particularly with a steam generator installed on board a ship during maneuvering the load changes. During maneuvering variations from no load to full load and vice versa occur in rapid succession.
- a known process is to control the combustion process in the steam generator by using as the desired value the sum of the output signal of the steam pressure controller and a signal that is proportional to the rate of steam offtake. It has been found, however, that this control configuration leads to the above-mentioned disadvantages, and the invention provides the means for an improved control configuration.
- the invention therefore relates to a process for the automatic control of a steam generator with varying load, in particular of a steam generator installed on board a ship.
- the combustion process in the steam generator is controlled by adjusting the supply of fuel and air, the desired value consisting of the sum of the output signal P of the steam pressure controller and a signal A that is proportional to the rate of steam offtake.
- a signal B proportional to the rate of change of the steam offtake is added to the sum of signal A.
- This control process uses a combination of proportional and derivative action, derived from the load of the steam generator, and of steam pressure control. These signals together adjust the heat production, This results in a considerable improvement of the speed of response of the steam generator.
- this control configuration is complemented by standard control systems belonging to a steam generator, such as a level control system, a system for the control of the fuel/air .ratio, a system for the control of. the boiler feedwater supply, a steam temperature control system, etc,
- the signal B is proportional to the expected rate of change of the steam offtake, the signal B being derived from an independent signal generator.
- the signal B is added.
- the magnitude of the signal B can be adapted to the expected rate of change of the steam offtake by manually adjusting the independent signal generator or by coupling this signal generator with the signal generator for the steam demand.
- the signal B now is not therefore obtained by deriving it from the measured steam offtake. This has the advantage that the signal B now is free from noise and, consequently, the fire in the combustion chamber becomes more quiet.
- Configurations for the control of the steam generator are known in which the rate of change of the steam offtake is confined to extreme limits.
- the rate of change of the valve position in the steam line to the turbine can be confined to a maximum positive or a maximum negative value.
- the absolute values of these limits may be equal, but need not be. For example, the rate of decrease of the load may be higher.
- the signal B in a control configuration of this type can have a fixed positive, respectively a fixed negative value, which sign is adapted to the sign of the change of the quantity of steam, which fixed value is automatically derived from an independent signal generator and added to the signal A as soon as the steam demand is changed.
- a fixed value of the signal B may suffice, because for instance during maneuveringof a ship changes in the steam demand occur of such an extent that changing the position of the steam valve takes place in accordance with the permitted extreme limits.
- An apparatus for the automatic control of a steam generator with varying load in particular of a steam generator belonging to a steam turbine plant on board a ship, is characterized by an adder of which one input is connected to the output of a steam pressure controller, another input to the signal output of a flowmeter measuring the quantity of steam supplied and still another input to a signal generator supplyinga signal that is proportional to the rate of change of the quantity of steam supplied.
- the adder output is connected to the input(s) for the set value of the system for the control of the supply of fuel and air to the combustion of the steam generator.
- the signal generator may consist of a computing element of which the input is connected to the signal output of the flowmeter measuring the quantity of steam supplied.
- the computing element output is connected to that input of the adder which receives the signal proportional to therate of change of the quantity of steam supplied, which signal can be made by the computing element.
- the signal generator may be an independent signal generator which is capable of supplying a signal that is proportional to the expected rate of change of the quantity of steam supplied.
- the signal generator output is connected to the appropriate input of the adder.
- the apparatus may be equipped with a controller by which the rate of change of the steam offtake can be confined to extreme limits.
- the said signal generator is an independent signal generator capable of supplying a signal of a fixed positive or negative value, which sign correspond to the sign of the change in the quantity of steam supplied.
- the signal generator is connected, by a switch element for effecting the connection to the signal of the desired sign, to the appropriate input of the adder.
- the switch element may be coupled to a correcting unit for the quantity of steam supplied.
- the apparatus may be further equipped with an adder of which one input is connected to the input of a controller for the air supply and another input is connected to the output of the first adder.
- the second adder is capable of supplying the sum of the signals P, A and B.
- the output of the first adder being connected to the correcting unit for the air supply, while the output of the second adder capable of supplying the sum of the signals P, A and B also receives the desired value of. the fuel supply controller and the air supply controller.
- FIG. 1 is a block diagram of one form of the invention
- FIG. 2 is a block diagram of one circuit for obtaining a control signed
- FIG. 3 is a block diagram of a modified form of the circuit shown in FIG. 2;
- FIG. 4 is a block diagram of the control system of FIG. 1 applied to a boiler.
- FIGS. 5 and 6 are response curves of the prior art control systems and the system of this invention.
- a boiler 1 for the production of steam is heated by a flame 2.
- the fuel supply is adjusted by a valve 3, the air flow by a device 4.
- the steam leaves the boiler via a line 5 and subsequently passes a superheater 6.
- This may be heated by, for instance, flue gases from the boiler.
- a superheater 7 after which the superheated steam can be passed via discharge line 8 to its destination, for instance a marine turbine.
- a heat exchanger 9 Through this heat exchanger superheated steam from 6 can be passed to the discharge line 8.
- the quantity of steam passing through the heat exchanger 9 can be adjusted by valves 10 and 11.
- a pressure gauge 12 measures the pressure in the line 8. The signal from this pressure gauge goes to the controller 13 and is there compared with a set value of the pressure. The output signal P of controller 13 goes to an adder 14. A flowmeter 15 measures the rate at which steam is supplied via line 8 and the signal from this meter also goes to the adder 14. This signal is the signal A. The adder 14 also received the signal B.
- the sum signal thus obtained goes as desired value to a controller 16 for the fuel supply and to a controller 17 for the air supply.
- controllers receive, respectively, signals from the flowmeter l8 measuring the fuel flow and the flowmeter l9 measuring the air flow.
- the valves or correcting units 3 and 4 are adjusted by the corresponding output signals.
- the output signals of the pressure controller 13 can also be used for adjusting valve 10.
- Valve 1 1 can be adjusted with a steam temperature controller.
- the signal B can be passed to the adder 14 by the action of the signal generator supplying the signal representing the steam demand, but it also is possible to use other methods.
- the signal B is obtained by passing the signal from flowmeter 15 to a computing element 20, from which is obtained a signal corresponding to the derivative of the steam flow through line 8 with respect to time.
- the signal B is obtained by connecting a switch element 21 to one of the signal generators 22 or 23, which are capable of supplying signals of opposite sign, possibly of the same value.
- Switch element 21 is operated simultaneously with the required change in the quantity of steam from line 8, which is symbolized by the dotted line 24.
- a vane pump 25 which can be driven by a motor 26.
- This motor 26 can be a steam turbine. It is also possible for an electric motor to be applied.
- the supply of air to the pump 25 can be controlled not only by controlling the power of the motor 26 but also by an air register 27.
- the pump 25 being a steam turbine, the supply of steam is adjusted by a valve 28.
- the number of revolutions per minute of the turbine is measured by meter 29 and controlled by controller 30, which adjusts the valve 28.
- the quantity of air supplied is measured with flowmeter 19.
- the signal from this meter goes to controller 17, which as desired value receives the output signal of the adder 14.
- the output signal of controller 17 goes to an adder 31 as also does the output signal of 14.
- the sum of these signals adjusts the air register 27. In this way it is ensured that the air register acts immediately in response to the signal B, which, as outlined hereinbefore, corresponds to the rate of change or the expected rate of change of the quantity of steam supplied.
- the controller 17 rather has the function of a trim controller.
- the output signal of the adder 31 also goes to the input of controller 30 receiving the set value for that contorller, so that the motor 26 also acts rapidly in response to the signal B.
- the output signal of the adder 14 also passes to a low signal value selector 32, as also does the signal of the flowmeter 19. In this way it is ensured that when the load of the steam generator increases, first the supply of air to the combustion chamber is increased and after that the supply of fuel, whichis desirable from the point of view of safety and atmospheric pollution.
- FIGS. 5 and 6 results are shown.
- the horizontal axes represent the same time scale.
- the series of curves in FIG. 5 have been obtained with a conventional control configuration, the series in FIG. 6 with a control configuration according to the invention.
- the curves with indication BL show how the steam demand varies with time. Large changes in the upward and in the downward direction are represented, in FIG. 5 at a rate of l.3%/s and in FIG. 6 even at a rate of 4%/s.
- the other curves relate to the responses to these changes, SDP representing the pressure in the steam drum, SOP the steam pressure at the superheater outlet, SOT the steam temperature at the same location (line 8 in FIG. 1), DL the water level in the steam drum and RF the heat generated under the drum.
- a process for the automatic control of a steam generator operating under varying load conditions comprising: measuring the exit steam pressure from the generator; comparing the measured steam pressure with the desired steam pressure and generating a correcting signal P; measuring the steam flow from the generator and generating a signal A related thereto; measuring the change in steam flow and generating a signal B related to the rate of chang in the steam flow; algebraically adding the signals P, A and B to obtain a control signal; and using the control signal to control the fuel and air flow to the combustion process of said generator.
- a flow meter disposed to measure steam flow from the generator and provide a flow signal related to the measured flow
- a pressure measuring means disposed to measure the pressure of the steam flow from the generator and supply a pressure signal related to the measured pressure
- a controller having a set point, said pressure measuring means being coupled to said controller said controller supplying a control signal in response to the difference between the pressure signal and said set point;
- a signal generator responsive to the flow signal to supply a rate of change signal related to the rate of change in said flow
- control means disposed to separately control the fuel and air supplied to the combustion chamber of said generator, said adder being coupled to said control means whereby said control means controls the air and fuel supplied to the combustion chamber.
- apparatus the signal generator consists of a computing element having an input connected to the signal output of the flow meter measuring the quantity of steam supplied and an output connected to that input of the adding circuit.
- said signal generator comprises an independent circuit capable of supplying a signal of a fixed positive and fixed negative value the sign of the signal being adapted to the sign of the change in the quantity of steam supplied, said signal generator being connected to a switch element for connecting the signal of the desired sign to the appropriate input of the adding circuit.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Steam Boilers And Waste-Gas Boilers (AREA)
- Devices For Medical Bathing And Washing (AREA)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL7217434A NL7217434A (en18) | 1972-12-21 | 1972-12-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3908897A true US3908897A (en) | 1975-09-30 |
Family
ID=19817601
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US428286A Expired - Lifetime US3908897A (en) | 1972-12-21 | 1973-12-26 | Off-line integration of bridge and boiler controls |
Country Status (7)
Country | Link |
---|---|
US (1) | US3908897A (en18) |
JP (1) | JPS4989001A (en18) |
DE (1) | DE2363270A1 (en18) |
GB (1) | GB1454416A (en18) |
NL (1) | NL7217434A (en18) |
NO (1) | NO137518C (en18) |
SE (1) | SE384403B (en18) |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4069675A (en) * | 1976-03-16 | 1978-01-24 | Measurex Corporation | Method of optimizing the performance of a multi-unit power |
US4175382A (en) * | 1975-08-22 | 1979-11-27 | Bbc Brown Boveri & Company Limited | Steam power plant with pressure-fired boiler |
US4497283A (en) * | 1983-11-18 | 1985-02-05 | Phillips Petroleum Company | Boiler control |
US4556018A (en) * | 1983-11-28 | 1985-12-03 | Shin-Ei Kabushiki Kaisha | Steam boiler |
US4583497A (en) * | 1984-03-14 | 1986-04-22 | Phillips Petroleum Company | Boiler control |
US4637348A (en) * | 1984-07-16 | 1987-01-20 | Babcock-Hitachi Kabushiki Kaisha | Apparatus for controlling starting operation of boiler |
US4768469A (en) * | 1985-07-31 | 1988-09-06 | Kabushiki Kaisha Toshiba | Operation control apparatus for recovery boilers |
KR100406472B1 (ko) * | 2001-10-31 | 2003-11-19 | 주식회사 경동보일러 | 풍압센서를 이용한 공기비례제어 보일러 |
US20090142717A1 (en) * | 2007-12-04 | 2009-06-04 | Preferred Utilities Manufacturing Corporation | Metering combustion control |
US20110244407A1 (en) * | 2010-03-30 | 2011-10-06 | Yamatake Corporation | Combustion controlling device |
US20140224344A1 (en) * | 2011-09-29 | 2014-08-14 | Azbil Corporation | Gas/liquid two-phase flow state controlling device and gas/liquid two-phase flow state controlling method |
US9328633B2 (en) | 2012-06-04 | 2016-05-03 | General Electric Company | Control of steam temperature in combined cycle power plant |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3103321A1 (de) * | 1981-01-31 | 1982-08-12 | Friedrich Wilh. Schwing Gmbh, 4690 Herne | "zweizylinder-dickstoffpumpe, vorzugsweise betonpumpe mit einem von einer zylinderseitigen brillenplatte abwechselnd schwenkenden schaltorgan" |
JP4526558B2 (ja) * | 2007-10-22 | 2010-08-18 | カワサキプラントシステムズ株式会社 | 舶用ボイラの蒸気温度制御方法及び制御装置 |
CN115016576B (zh) * | 2022-05-27 | 2024-02-09 | 国能河北沧东发电有限责任公司 | 再热汽温控制方法、装置、可读介质及电子设备 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3042007A (en) * | 1958-07-28 | 1962-07-03 | Beckman Instruments Inc | Boiler controller |
US3284615A (en) * | 1956-09-24 | 1966-11-08 | Burroughs Corp | Digital control process and system |
US3415232A (en) * | 1966-08-01 | 1968-12-10 | Combustion Eng | Safety system for steam generator |
US3616997A (en) * | 1968-05-20 | 1971-11-02 | Kockums Mekaniska Verkstads Ab | Combustion regulator |
-
1972
- 1972-12-21 NL NL7217434A patent/NL7217434A/xx not_active Application Discontinuation
-
1973
- 1973-12-19 GB GB5872873A patent/GB1454416A/en not_active Expired
- 1973-12-19 JP JP48141438A patent/JPS4989001A/ja active Pending
- 1973-12-19 DE DE19732363270 patent/DE2363270A1/de not_active Withdrawn
- 1973-12-19 SE SE7317131A patent/SE384403B/xx unknown
- 1973-12-19 NO NO4866/73A patent/NO137518C/no unknown
- 1973-12-26 US US428286A patent/US3908897A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3284615A (en) * | 1956-09-24 | 1966-11-08 | Burroughs Corp | Digital control process and system |
US3042007A (en) * | 1958-07-28 | 1962-07-03 | Beckman Instruments Inc | Boiler controller |
US3415232A (en) * | 1966-08-01 | 1968-12-10 | Combustion Eng | Safety system for steam generator |
US3616997A (en) * | 1968-05-20 | 1971-11-02 | Kockums Mekaniska Verkstads Ab | Combustion regulator |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4175382A (en) * | 1975-08-22 | 1979-11-27 | Bbc Brown Boveri & Company Limited | Steam power plant with pressure-fired boiler |
US4069675A (en) * | 1976-03-16 | 1978-01-24 | Measurex Corporation | Method of optimizing the performance of a multi-unit power |
US4497283A (en) * | 1983-11-18 | 1985-02-05 | Phillips Petroleum Company | Boiler control |
US4556018A (en) * | 1983-11-28 | 1985-12-03 | Shin-Ei Kabushiki Kaisha | Steam boiler |
US4583497A (en) * | 1984-03-14 | 1986-04-22 | Phillips Petroleum Company | Boiler control |
US4637348A (en) * | 1984-07-16 | 1987-01-20 | Babcock-Hitachi Kabushiki Kaisha | Apparatus for controlling starting operation of boiler |
US4768469A (en) * | 1985-07-31 | 1988-09-06 | Kabushiki Kaisha Toshiba | Operation control apparatus for recovery boilers |
KR100406472B1 (ko) * | 2001-10-31 | 2003-11-19 | 주식회사 경동보일러 | 풍압센서를 이용한 공기비례제어 보일러 |
US20090142717A1 (en) * | 2007-12-04 | 2009-06-04 | Preferred Utilities Manufacturing Corporation | Metering combustion control |
US20110244407A1 (en) * | 2010-03-30 | 2011-10-06 | Yamatake Corporation | Combustion controlling device |
US20140224344A1 (en) * | 2011-09-29 | 2014-08-14 | Azbil Corporation | Gas/liquid two-phase flow state controlling device and gas/liquid two-phase flow state controlling method |
US9367068B2 (en) * | 2011-09-29 | 2016-06-14 | Azbil Corporation | Gas/liquid two-phase flow state controlling device and gas/liquid two-phase flow state controlling method |
US9328633B2 (en) | 2012-06-04 | 2016-05-03 | General Electric Company | Control of steam temperature in combined cycle power plant |
Also Published As
Publication number | Publication date |
---|---|
SE384403B (sv) | 1976-05-03 |
NL7217434A (en18) | 1974-06-25 |
GB1454416A (en) | 1976-11-03 |
DE2363270A1 (de) | 1974-06-27 |
NO137518B (no) | 1977-11-28 |
JPS4989001A (en18) | 1974-08-26 |
NO137518C (no) | 1978-03-08 |
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