CN109297074B - Control method and system for small steam turbine steam exhaust and heat supply system of back pressure type steam-driven induced draft fan - Google Patents
Control method and system for small steam turbine steam exhaust and heat supply system of back pressure type steam-driven induced draft fan Download PDFInfo
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- CN109297074B CN109297074B CN201811080212.XA CN201811080212A CN109297074B CN 109297074 B CN109297074 B CN 109297074B CN 201811080212 A CN201811080212 A CN 201811080212A CN 109297074 B CN109297074 B CN 109297074B
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- 238000010438 heat treatment Methods 0.000 claims abstract description 32
- 230000001105 regulatory effect Effects 0.000 claims abstract description 26
- 238000000605 extraction Methods 0.000 claims abstract description 18
- 239000013589 supplement Substances 0.000 claims description 14
- 230000001276 controlling effect Effects 0.000 claims description 11
- 230000008901 benefit Effects 0.000 abstract description 8
- 238000004134 energy conservation Methods 0.000 abstract description 5
- 238000010586 diagram Methods 0.000 description 6
- 239000002699 waste material Substances 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D1/00—Steam central heating systems
- F24D1/08—Feed-line arrangements, e.g. providing for heat-accumulator tanks, expansion tanks
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
- F22D1/50—Feed-water heaters, i.e. economisers or like preheaters incorporating thermal de-aeration of feed-water
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D19/00—Details
- F24D19/10—Arrangement or mounting of control or safety devices
- F24D19/1003—Arrangement or mounting of control or safety devices for steam heating systems
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P80/00—Climate change mitigation technologies for sector-wide applications
- Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
- Y02P80/15—On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply
Abstract
The invention discloses a control method and a system of a back-pressure steam-driven draught fan small steam turbine steam exhaust and heat supply system, wherein the method comprises the steps of switching a heat supply control mode to a normal heat supply working condition under the condition that whether a second regulating valve is installed on a unit four-section steam extraction pipeline connected with a deaerator and the unit four-section steam extraction pipeline is in a normal state or not, so that the steam exhaust of a back-pressure steam-driven draught fan small steam turbine unit mainly supplies heat to the outside through a heat supply branch cylinder and assists the steam supply and heating of the deaerator; otherwise, the heat supply control mode is switched to a temporary heat supply working condition, so that the steam discharged by the small steam turbine unit of the back pressure type steam-driven draught fan is mainly used for supplying steam to the deaerator and heating, and the heat is supplied to the outside through the heat supply branch cylinder; the system includes a computer device programmed to perform the foregoing method steps. The invention can effectively solve the problem of high-load air-to-air steam exhaust of the small steam turbine of the back-pressure steam-driven draught fan in a unit, improves the heat supply flexibility and economic benefit of thermal power enterprises adopting the back-pressure steam-driven draught fan, and achieves the purposes of energy conservation and emission reduction.
Description
Technical Field
The invention relates to a thermal generator set using a back-pressure steam-driven draught fan, in particular to a control method and a system of a small steam turbine steam exhaust and heat supply system of the back-pressure steam-driven draught fan.
Background
The back-pressure type steam-driven draught fan adopts a back-pressure type small steam turbine to replace a high-power motor to drive the draught fan, so that impact on service power when the large-scale electric draught fan is started can be avoided, the service power consumption rate is reduced, and steam exhausted by the small steam turbine can supply heat outwards, so that the economic benefit of a power plant is improved. After a power plant is put into operation, the steam exhausted by the small steam turbine of the back pressure type steam-driven draught fan is mainly supplied to a deaerator for heating, all the steam exhausted quantities of the small steam turbines of the two back pressure type steam-driven draught fans can not be absorbed by the deaerator under high load (the steam exhausted quantity of a single steam-driven draught fan is 50t/h and the steam exhausted quantities of the two back pressure type steam-driven draught fans are 100t/h under rated working conditions), the deaerator can absorb 80t/h at most, redundant steam exhausted by the deaerator can only open the air exhaust of a pressure control valve of the small steam turbine, certain resource waste and noise pollution are caused, otherwise, the high steam exhaust pressure can influence the output of the back pressure type steam-driven draught fan and the pressure control of a hearth, and. If the part of exhausted steam can be used as a heat source of peripheral enterprises, the waste of fuel resources can be avoided, the purposes of energy conservation and emission reduction are achieved, the economic benefit can be increased for a power plant, and the heat supply advantage of the back-pressure steam-driven draught fan is exerted. At present, domestic and foreign documents mainly report how to optimize a small steam turbine steam exhaust and heat supply process system of the back pressure type steam-driven draught fan, and reports aiming at a heat supply control method of the back pressure type steam-driven draught fan are few. Therefore, it is necessary to develop a steam exhaust and heat supply control method for the small steam turbine of the back-pressure steam-driven draught fan, which solves the problem that the small steam turbine of the existing back-pressure steam-driven draught fan has high load to exhaust steam in a unit and realizes flexible heat supply to the outside of the small steam turbine of the back-pressure steam-driven draught fan.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: aiming at the problems in the prior art, the invention provides a control method and a control system for a steam exhaust and heat supply system of a small steam turbine of a back-pressure steam-driven draught fan, which can effectively solve the problem of high-load air exhaust of the small steam turbine of the back-pressure steam-driven draught fan in a unit, improve the heat supply flexibility and the economic benefit of thermal power enterprises adopting the back-pressure steam-driven draught fan and achieve the purposes of energy conservation and emission reduction.
In order to solve the technical problems, the invention adopts the technical scheme that:
the invention provides a control method of a back-pressure steam-driven draught fan small steam turbine steam exhaust and heat supply system, the back-pressure steam-driven draught fan small steam turbine steam exhaust and heat supply system comprises a back-pressure steam-driven draught fan small steam turbine unit, a deaerator, a heat supply branch cylinder and an auxiliary steam header, the steam exhaust output end of the back-pressure steam-driven draught fan small steam turbine unit is respectively connected with the deaerator through a first regulating valve and a third regulating valve and the heat supply branch cylinder, the deaerator is connected with a unit four-section steam extraction pipeline through an electric door, the input end of the auxiliary steam header is connected with the unit four-section steam extraction pipeline, and the output end of the auxiliary steam header is connected with the steam exhaust input end of the heat supply branch cylinder through a fourth regulating valve, and the implementation steps of the control method comprise:
1) judging whether a second adjusting door is installed on a unit four-section steam extraction pipeline connected with the deaerator, and if the second adjusting door is installed, skipping to execute the step 2); otherwise, skipping to execute the step 4);
2) judging the working state of the second adjusting door, and if the second adjusting door is in a normal working state, skipping to execute the step 3); otherwise, skipping to execute the step 4);
3) switching the heat supply control mode to a normal heat supply working condition, so that the steam discharged by the small steam turbine unit of the back pressure type steam-driven draught fan mainly supplies heat to the outside through the heat supply branch cylinder and secondarily supplies steam to and heats the deaerator; withdrawing;
4) and switching the heat supply control mode to a temporary heat supply working condition, so that the steam discharged by the small steam turbine unit of the back pressure type steam-driven draught fan is mainly used for supplying steam to the deaerator and heating and is assisted for supplying heat to the outside through the heat supply branch cylinder.
Preferably, the detailed step of switching the heating control mode to the normal heating condition in the step 3) includes:
3.1) keeping the third adjusting door fully opened;
3.2) automatically controlling the pressure P3 of the heat supply cylinder by a first adjusting valve;
3.3) keeping the electric door fully opened, and automatically controlling the pressure P2 of the deaerator through a second adjusting door;
3.4) the auxiliary steam header is automatically controlled to supplement pressure to the heat supply branch cylinder through a fourth adjusting valve;
3.5) judge that the exhaust pressure P1 of the little steam turbine unit of backpressure formula steam-operated draught fan is greater than the first threshold K1 of opening of predetermineeing and whether hold, if hold then ally oneself with and open first governing valve, first threshold K1 of opening is less than the second threshold K2 of opening of the exhaust pressure control valve of the little steam turbine unit of backpressure formula steam-operated draught fan.
Preferably, when the pressure P3 of the heating cylinder is automatically controlled by the first adjusting door in step 3.2), a cascade PID cascade control system is adopted for the automatic control of the first adjusting door.
Preferably, the PID cascade control system is formed by connecting an outer ring PID controller and an inner ring PID controller in series, the controlled quantity of the outer ring PID controller is the pressure P3 of the heat supply steam-distributing cylinder and the pressure set value of the heat supply steam-distributing cylinder, the controlled quantity of the inner ring PID controller is the exhaust pressure P1 of the back pressure type pneumatic draught fan small steam turbine unit and the output value of the outer ring PID controller, and the output value of the inner ring PID controller is used as the opening instruction of the first regulating valve.
Preferably, the step 3.3) of automatically controlling the pressure P2 of the deaerator through the second regulating gate specifically includes: according to a preset second functionf 2(x) And calculating a second function value of the unit load, taking the second function value of the unit load as a pressure set value of the deaerator, inputting the pressure set value of the deaerator and the pressure P2 of the deaerator into the PID controller, and taking an output value of the PID controller as an opening instruction of the second adjusting door.
Preferably, the step 3.4) of automatically controlling the auxiliary steam header to supplement pressure to the heat supply branch cylinder through the fourth adjusting valve specifically includes: the pressure P3 of the heat supply cylinder and the pressure set value of the heat supply cylinder are input into the PID controller, and the output value of the PID controller is used as the opening command of the fourth adjusting valve.
Preferably, the detailed step of switching the heating control mode to the temporary heating condition in step 4) includes:
4.1) keeping the first adjusting door fully opened;
4.2) keeping the electric door closed;
4.3) the third regulating valve is automatically controlled to ensure that the small steam turbine of the back-pressure steam-driven induced draft fan does not exhaust steam in the opposite direction under the high-load condition of the unit;
4.4) the auxiliary steam header is automatically controlled to supplement pressure to the heat supply branch cylinder through a fourth adjusting valve;
4.5) judge that the exhaust pressure P1 of the little steam turbine unit of backpressure formula steam-operated draught fan is greater than the first threshold K1 of opening of predetermineeing and whether hold, if hold then ally oneself with and open the third regulating valve, first threshold K1 of opening is less than the second threshold K2 of opening of the exhaust pressure control valve of the little steam turbine unit of backpressure formula steam-operated draught fan.
Preferably, the step 4.3) automatically controls the third adjusting valve to enable the small steam turbine of the back-pressure steam-driven induced draft fan to not exhaust steam under the high-load condition of the unit specifically includes: according to a preset first functionf 1(x) And calculating a first function value of the unit load, and taking the first function value of the unit load as an opening instruction of the third adjusting door.
Preferably, the step 4.4) of automatically controlling the auxiliary steam header to supplement pressure to the heat supply branch cylinder through the fourth adjusting valve specifically includes: the pressure P3 of the heat supply cylinder and the pressure set value of the heat supply cylinder are input into the PID controller, and the output value of the PID controller is used as the opening command of the fourth adjusting valve.
The invention provides a control system of a back-pressure type steam-driven draught fan small steam turbine steam exhaust and heat supply system, which comprises computer equipment, wherein the computer equipment is programmed to execute the steps of the control method of the back-pressure type steam-driven draught fan small steam turbine steam exhaust and heat supply system.
According to the invention, under the condition that whether a second adjusting valve is installed on a unit four-section steam extraction pipeline connected with a deaerator and the second adjusting valve is in a normal state or not, a heat supply control mode is switched to a normal heat supply working condition, so that the steam exhaust of a small steam turbine unit of a backpressure type steam-driven draught fan is mainly used for supplying heat to the outside through a heat supply branch cylinder and is used for supplying steam to and heating the deaerator; otherwise will supply heat to control mode switch to interim heat supply operating mode for the little steam turbine unit of back pressure formula steam-operated draught fan is discharged vapour and is given first place to the oxygen-eliminating device steam supply heating, is assisted through the external heat supply of heat supply cylinder, compares with prior art, has following advantage: 1. the problem of air exhaust of the small steam turbine of the back-pressure steam-driven draught fan when the unit is in high load can be solved, and resource waste and noise pollution to the air exhaust are avoided; 2. the heat supply flexibility and the economic benefit of thermal power enterprises adopting the back-pressure type steam-driven draught fan can be improved, and the purposes of energy conservation and emission reduction are achieved.
Drawings
Fig. 1 is a schematic structural diagram of a back-pressure steam-driven draught fan small steam turbine steam exhaust and heat supply system in the embodiment of the invention.
FIG. 2 is a schematic diagram of a basic flow of a method according to an embodiment of the present invention.
FIG. 3 is a schematic flow chart of a normal heating operation according to an embodiment of the present invention.
FIG. 4 is a schematic flow chart of a temporary heating condition according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of an automatic control of the third adjustment gate in an embodiment of the invention.
Fig. 6 is a schematic diagram of an automatic control of the first adjustment gate in an embodiment of the present invention.
Fig. 7 is a schematic diagram of the automatic control of the second adjustment gate in the embodiment of the present invention.
Fig. 8 is an automatic control schematic diagram of a fourth adjustment door in an embodiment of the present invention.
Illustration of the drawings: 1. a small steam turbine unit of a back pressure type steam-driven draught fan; 11. a small steam turbine of a back pressure type steam-driven draught fan; 12. a steam discharge pressure control valve; 2. a deaerator; 21. a first adjustment gate; 22. a second adjustment gate; 23. an electrically operated door; 3. a heat supply steam distributing cylinder; 31. a third adjustment gate; 32. a fourth regulation gate; 4. and an auxiliary steam header.
Detailed Description
The method and system for controlling the steam exhaust and heat supply system of the small steam turbine of the back pressure steam-driven draught fan will be further described in detail by taking the steam exhaust and heat supply system of the small steam turbine of the back pressure steam-driven draught fan as an example shown in FIG. 1,
as shown in fig. 1, little steam turbine steam extraction heating system of back pressure formula steam-operated draught fan includes little steam turbine unit 1 of back pressure formula steam-operated draught fan, deaerator 2, heat supply steam-distributing cylinder 3 and auxiliary steam header 4, the steam extraction output of little steam turbine unit 1 of back pressure formula steam-operated draught fan links to each other and links to each other with heat supply steam-distributing cylinder 3 through first regulating gate 21 and deaerator 2 respectively and through third regulating gate 31, deaerator 2 is continuous with unit four sections steam extraction pipeline through electric gate 23, auxiliary steam header 4's input links to each other with unit four sections steam extraction pipeline, the output links to each other through the steam extraction input of fourth regulating gate 32 and heat supply steam-distributing cylinder 3.
As shown in fig. 1, in this embodiment, a second adjusting door 22 is installed on the four-section steam extraction pipeline of the unit connected to the deaerator 2.
As shown in fig. 1, the back-pressure steam-driven induced draft fan small steam turbine unit 1 includes two sets of back-pressure steam-driven induced draft fan small steam turbines 11, the two sets of back-pressure steam-driven induced draft fan small steam turbines 11 are arranged in parallel, the input ends of the two sets of back-pressure steam-driven induced draft fan small steam turbines 11 are header steam output by the low-temperature reheater outlet of the unit, the output ends of the two sets of back-pressure steam-driven draft fan small steam turbines are respectively provided with a steam exhaust pressure control.
As shown in fig. 2, this embodiment provides a control method for a back-pressure steam-driven induced draft fan small steam turbine steam exhaust and heat supply system, where the implementation steps of the control method include:
1) judging whether a second adjusting door 22 is installed on a unit four-section steam extraction pipeline connected with the deaerator 2, and if the second adjusting door 22 is installed, skipping to execute the step 2); otherwise, skipping to execute the step 4);
2) judging the working state of the second adjusting gate 22, and if the second adjusting gate 22 is in the normal working state, skipping to execute the step 3); otherwise, skipping to execute the step 4);
3) switching a heat supply control mode to a normal heat supply working condition, so that the back pressure type steam-driven draught fan small steam turbine unit 1 discharges steam mainly by supplying heat to the outside through a heat supply branch cylinder 3 and secondarily supplying steam and heating to a deaerator 2; withdrawing;
4) and switching the heat supply control mode to a temporary heat supply working condition, so that the steam discharged by the back pressure type steam-driven draught fan small steam turbine unit 1 is mainly used for supplying steam and heating the deaerator 2 and is assisted for supplying heat to the outside through the heat supply branch cylinder 3.
When the steam turbine four-section steam extraction (the steam turbine four-section steam extraction mainly supplies steam to the deaerator, the small steam turbine of the steam-driven feed pump and the auxiliary steam header of the unit) to the deaerator 2 is provided with the second regulating valve 22, and the second regulating valve 22 is normal, the heat supply control mode can be switched to the normal heat supply working condition, the steam exhaust of the small steam turbine unit 1 of the back pressure type steam-driven draught fan is mainly used for supplying heat to the outside, and the steam supply heating of the deaerator 2 is used for assisting.
As shown in fig. 3, the detailed step of switching the heating control mode to the normal heating condition in step 3) includes:
3.1) keeping the third adjustment gate 31 fully open, see fig. 5;
3.2) automatically controlling the pressure P3 of the heat supply cylinder 3 through the first adjusting valve 21;
3.3) the electric door 23 is kept fully opened, and the pressure P2 of the deaerator 2 is automatically controlled through the second adjusting door 22;
3.4) the auxiliary steam header 4 is automatically controlled to supplement pressure to the heat supply steam-distributing cylinder 3 through the fourth adjusting valve 32, so that when the steam exhaust of the small steam turbine unit 1 of the back pressure type steam-driven draught fan cannot ensure external heat supply, the auxiliary steam header 4 provides supplement;
3.5) judging whether the exhaust pressure P1 of the small steam turbine unit 1 of the back pressure type steam-driven draught fan is larger than a preset first opening threshold value K1, if so, opening the first adjusting valve 21 in a linked mode, wherein the first opening threshold value K1 is smaller than a second opening threshold value K2 of the exhaust pressure control valve 12 of the small steam turbine unit 1 of the back pressure type steam-driven draught fan, and therefore the small steam turbine of the back pressure type steam-driven draught fan is guaranteed not to exhaust steam in an opposite mode under any working condition. In this embodiment, the first opening threshold K1 specifically takes a value of 1.35MPa, and the exhaust pressure control valve 12 of the back-pressure steam-driven induced draft fan small steam turbine unit 1 specifically takes a value of 1.5 MPa.
In this embodiment, when the pressure P3 of the heating cylinder 3 is automatically controlled by the first adjusting valve 21 in step 3.2), a cascade PID cascade control system is adopted for the automatic control of the first adjusting valve 21. Referring to fig. 6, in the present embodiment, the PID cascade control system is formed by connecting an outer ring PID controller and an inner ring PID controller in series, the controlled variables of the outer ring PID controller are the pressure P3 of the heat supply branch cylinder 3 and the pressure set value of the heat supply branch cylinder 3, the controlled variables of the inner ring PID controller are the exhaust pressure P1 of the back pressure type pneumatic induced draft fan small steam turbine unit 1 and the output value of the outer ring PID controller, and the output value of the inner ring PID controller is used as the opening instruction of the first adjusting valve 21.
Referring to fig. 7, in this embodiment, the automatically controlling the pressure P2 of the deaerator 2 through the second regulating gate 22 in step 3.3) specifically means: according to a preset second functionf 2(x) And (3) calculating a second function value of the unit load, taking the second function value of the unit load as a pressure set value of the deaerator 2, inputting the pressure set value of the deaerator 2 and the pressure P2 of the deaerator 2 into the PID controller, and taking an output value of the PID controller as an opening instruction of the second adjusting door 22. Second functionf 2(x) Dividing the unit load into a plurality of intervals for a piecewise function, wherein the unit load point of each interval corresponds to a fixed pressure set value; in this embodiment, the second functionf 2(x) The method specifically comprises the following steps:
(0MW,0MPa),(330MW,0.7MPa),(500MW,0.9MPa),(600MW,1.0MPa),(660MW,1.1MPa)。
referring to fig. 8, in step 3.4) of this embodiment, the automatic control of the auxiliary steam header 4 through the fourth adjusting valve 32 to supplement pressure to the heat supply branch cylinder 3 specifically means: the pressure P3 of the heat supply cylinder 3 and the pressure set value of the heat supply cylinder 3 are input to the PID controller, and the output value of the PID controller is used as the opening command of the fourth adjustment valve 32.
When the steam turbine four-section steam extraction (the steam turbine four-section steam extraction mainly supplies steam to the deaerator, the small steam turbine of the steam feed pump and the auxiliary steam header of the unit) to the deaerator 2 is not provided with the second regulating valve 22 or the second regulating valve 22 fails, the heat supply control mode can be switched to the temporary heat supply working condition, the small steam turbine unit 1 of the back pressure type steam feed pump mainly supplies steam to the deaerator 2, and the external heat supply is auxiliary.
As shown in fig. 4, the detailed step of switching the heating control mode to the temporary heating condition in step 4) includes:
4.1) keeping the first adjusting door 21 fully opened;
4.2) keeping the electric door 23 closed;
4.3) the third adjusting door 31 is automatically controlled to ensure that the small steam turbine of the back-pressure steam-driven induced draft fan does not exhaust steam in the opposite direction under the high-load condition of the unit;
4.4) the auxiliary steam header 4 is automatically controlled to supplement pressure to the heat supply steam-distributing cylinder 3 through the fourth adjusting valve 32, so that when the steam exhaust of the small steam turbine unit 1 of the back pressure type steam-driven draught fan cannot ensure external heat supply, the auxiliary steam header 4 provides supplement to ensure stable and continuous external heat supply;
4.5) judging whether the exhaust pressure P1 of the small steam turbine unit 1 of the back pressure type steam-driven draught fan is larger than a preset first opening threshold value K1, if so, opening the third adjusting valve 31 in a linked mode, wherein the first opening threshold value K1 is smaller than a second opening threshold value K2 of the exhaust pressure control valve 12 of the small steam turbine unit 1 of the back pressure type steam-driven draught fan, and therefore the small steam turbine of the back pressure type steam-driven draught fan is guaranteed not to exhaust steam in an opposite mode under any working condition. In this embodiment, the first opening threshold K1 specifically takes a value of 1.35MPa, and the exhaust pressure control valve 12 of the back-pressure steam-driven induced draft fan small steam turbine unit 1 specifically takes a value of 1.5 MPa.
Referring to fig. 5, in step 4.3) of this embodiment, the third adjustment door 31 is automatically controlled so that the small steam turbine of the back-pressure steam-driven induced draft fan does not perform empty steam exhaust specifically: according to a preset first functionf 1(x) And a first function value of the unit load is obtained, the first function value of the unit load is used as an opening instruction of the third adjusting door 31, and the opening instruction of the third adjusting door 31 is a function of the unit load, so that the small steam turbine unit 1 of the back-pressure steam-driven induced draft fan can be ensured not to exhaust steam in the air under the high-load condition of the unit. First functionf 1(x) Is a piecewise function, i.e. the load of the unit is divided into a plurality of sections, and each sectionCorresponding a fixed opening instruction to the unit load point; in this embodiment, the first functionf 1(x) The method specifically comprises the following steps:
[(0MW,0%),(330MW,0%),(500MW,3%),(550MW,5%),(600MW,7%),(660MW,15%)]。
referring to fig. 8, in step 4.4) of this embodiment, the automatic control of the auxiliary steam header 4 through the fourth adjusting valve 32 to supplement pressure to the heat supply branch cylinder 3 specifically means: the pressure P3 of the heat supply cylinder 3 and the pressure set value of the heat supply cylinder 3 are input to the PID controller, and the output value of the PID controller is used as the opening command of the fourth adjustment valve 32.
As shown in fig. 5, in the normal heating condition, the adjustment door 3 is kept fully open, and the opening command is 100. Under the temporary heat supply working condition, the third adjusting door 31 is automatically switched on, and the opening instruction of the third adjusting door 31 is a first function of the unit loadf 1(x) And (4) determining. Under the temporary heat supply working condition, when the steam exhaust pressure P1 of the small steam turbine of the back pressure type steam-driven draught fan is larger than the opening threshold K1 (such as 1.35 MPa), the small steam turbine of the back pressure type steam-driven draught fan is opened in a linked mode to exhaust steam to the third adjusting valve 31 of the heat supply branch cylinder.
As shown in fig. 6, under the normal heat supply condition, the first adjusting valve 21 is automatically operated, and a cascade PID cascade control system is adopted, the PID cascade control system is formed by connecting an outer ring PID controller and an inner ring PID controller in series, the controlled quantity of the outer ring PID controller is the pressure P3 of the heat supply branch cylinder 3 and the pressure set value of the heat supply branch cylinder 3, the controlled quantity of the inner ring PID controller is the exhaust pressure P1 of the back-pressure steam-driven induced draft fan small steam turbine unit 1 and the output value of the outer ring PID controller, the output value of the inner ring PID controller is used as the opening instruction of the first adjusting valve 21, and the pressure set value of the heat supply branch cylinder 3 is manually set by an operator on duty according to the heat supply requirement; under the normal heat supply working condition, when the steam exhaust pressure P1 of the small steam turbine of the backpressure steam-driven draught fan is larger than the opening threshold K1 (such as 1.35 MPa), the steam exhaust of the small steam turbine of the backpressure steam-driven draught fan is linked to the first adjusting valve 21 of the deaerator. In the temporary heating condition, the first regulating valve 21 is kept fully opened, and the opening instruction is 100.
As shown in FIG. 7, the second regulating gate 22 is regulated by a PID controller, and the controlled amount is oxygen removalThe set point of the pressure P2 of the device is a second function of the load of the unitf 2(x) And (4) determining. According to a preset second functionf 2(x) And (3) calculating a second function value of the unit load, taking the second function value of the unit load as a pressure set value of the deaerator 2, inputting the pressure set value of the deaerator 2 and the pressure P2 of the deaerator 2 into the PID controller, and taking an output value of the PID controller as an opening instruction of the second adjusting door 22.
As shown in fig. 8, the fourth regulating valve 32 is regulated by a PID controller by a heating cylinder pressure P3. The pressure P3 of the heat supply cylinder 3 and the pressure set value of the heat supply cylinder 3 are input to the PID controller, and the output value of the PID controller is used as the opening command of the fourth adjustment valve 32.
The embodiment provides a control system of a back-pressure steam-driven draught fan small steam turbine steam exhaust and heat supply system, which comprises computer equipment, wherein the computer equipment is programmed to execute the steps of the control method of the back-pressure steam-driven draught fan small steam turbine steam exhaust and heat supply system, the problem of high-load air-to-air steam exhaust of the back-pressure steam-driven draught fan small steam turbine in a unit can be effectively solved, the heat supply flexibility and the economic benefit of a thermal power generation enterprise adopting the back-pressure steam-driven draught fan are improved, and the purposes of energy conservation and emission reduction are achieved.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (8)
1. A control method for a back pressure type steam-driven draught fan small steam turbine steam exhaust and heat supply system is characterized in that the implementation steps of the control method comprise:
1) judging whether a second adjusting door (22) is installed on a unit four-section steam extraction pipeline connected with the deaerator (2), and if the second adjusting door (22) is installed, skipping to execute the step 2); otherwise, skipping to execute the step 4);
2) judging the working state of the second adjusting gate (22), and if the second adjusting gate (22) is in a normal working state, skipping to execute the step 3); otherwise, skipping to execute the step 4);
3) switching a heat supply control mode to a normal heat supply working condition, so that the steam discharged by the back pressure type steam-driven draught fan small steam turbine unit (1) mainly supplies heat to the outside through the heat supply branch cylinder (3) and assists in supplying steam and heating the deaerator (2); withdrawing;
4) the heat supply control mode is switched to a temporary heat supply working condition, so that the steam discharged by the back pressure type steam-driven draught fan small steam turbine unit (1) is mainly used for supplying steam and heating the deaerator (2), and the heat is supplied to the outside through the heat supply branch cylinder (3) as an auxiliary;
the detailed step of switching the heating control mode to the normal heating operation in step 3) includes:
3.1) keeping the third adjusting door (31) fully opened;
3.2) the pressure P3 of the heat supply cylinder (3) is automatically controlled through a first adjusting valve (21);
3.3) the electric door (23) is kept fully opened, and the pressure P2 of the deaerator (2) is automatically controlled through the second adjusting door (22);
3.4) the auxiliary steam header (4) is automatically controlled to supplement pressure to the heat supply steam distributing cylinder (3) through a fourth adjusting valve (32);
3.5) judging whether the exhaust steam pressure P1 of the back-pressure type steam-driven induced draft fan small steam turbine unit (1) is greater than a preset first opening threshold value K1, if so, opening a first adjusting valve (21) in a linked mode, wherein the first opening threshold value K1 is smaller than a second opening threshold value K2 of an exhaust steam pressure control valve (12) of the back-pressure type steam-driven induced draft fan small steam turbine unit (1);
the detailed step of switching the heating control mode to the temporary heating condition in step 4) includes:
4.1) keeping the first adjusting door (21) fully open;
4.2) keeping the electric door (23) closed;
4.3) the third regulating valve (31) is automatically controlled to ensure that the small steam turbine of the back-pressure steam-driven induced draft fan does not exhaust steam in the opposite air under the condition of high load;
4.4) the auxiliary steam header (4) is automatically controlled to supplement pressure to the heat supply steam distributing cylinder (3) through a fourth adjusting valve (32);
4.5) judge that the exhaust pressure P1 of little steam turbine unit of backpressure formula steam-operated draught fan (1) is greater than first opening threshold K1 of preset and whether hold, if hold then ally oneself with and open third regulating valve (31), first opening threshold K1 opens threshold K2 littleer than the second of the exhaust pressure control valve (12) of little steam turbine unit of backpressure formula steam-operated draught fan (1).
2. The control method of the small steam turbine steam exhaust and heat supply system of the back-pressure steam-driven draught fan according to claim 1, wherein in the step 3.2), when the pressure P3 of the heat supply branch cylinder (3) is automatically controlled through the first adjusting door (21), a cascade PID cascade control system is adopted for the automatic control of the first adjusting door (21).
3. The control method of the back-pressure steam-driven induced draft fan small steam turbine steam exhaust and heat supply system according to claim 2, wherein the PID cascade control system is formed by serially connecting an outer ring PID controller and an inner ring PID controller, the controlled quantity of the outer ring PID controller is the pressure P3 of the heat supply branch cylinder (3) and the pressure set value of the heat supply branch cylinder (3), the controlled quantity of the inner ring PID controller is the steam exhaust pressure P1 of the back-pressure steam-driven induced draft fan small steam turbine unit (1) and the output value of the outer ring PID controller, and the output value of the inner ring PID controller is used as the opening instruction of the first regulating valve (21).
4. The control method of the back-pressure steam-driven draught fan small turbine steam exhaust and heat supply system according to claim 1, wherein the step 3.3) of automatically controlling the pressure P2 of the deaerator (2) through the second adjusting valve (22) specifically comprises the steps of: according to a preset second functionf 2(x) A second function value of the unit load is obtained, the second function value of the unit load is used as a pressure set value of the deaerator (2), and the pressure set value of the deaerator (2) is usedAnd the pressure P2 of the deaerator (2) is input into a PID controller, and the output value of the PID controller is used as the opening instruction of the second regulating valve (22).
5. The control method of the small steam turbine steam exhaust and heat supply system of the back-pressure steam-driven draught fan according to claim 1, wherein the step 3.4) of automatically controlling the auxiliary steam header (4) through the fourth adjusting valve (32) to supplement pressure to the heat supply branch cylinder (3) specifically comprises the following steps: the pressure P3 of the heat supply cylinder (3) and the pressure set value of the heat supply cylinder (3) are input into a PID controller, and the output value of the PID controller is used as the opening command of the fourth adjusting valve (32).
6. A control method of a back-pressure steam-driven draught fan small steam turbine steam exhaust and heat supply system according to any one of claims 1-5, characterized in that in step 4.3), the third regulating valve (31) is automatically controlled to enable the unit to perform non-null steam exhaust under the high load condition, specifically: according to a preset first functionf 1(x) And a first function value of the unit load is obtained, and the first function value of the unit load is used as an opening instruction of the third adjusting door (31).
7. The control method of the small steam turbine steam exhaust and heat supply system of the back-pressure steam-driven draught fan according to claim 6, wherein the step 4.4) of automatically controlling the auxiliary steam header (4) through the fourth adjusting valve (32) to supplement pressure to the heat supply branch cylinder (3) specifically comprises the following steps: the pressure P3 of the heat supply cylinder (3) and the pressure set value of the heat supply cylinder (3) are input into a PID controller, and the output value of the PID controller is used as the opening command of the fourth adjusting valve (32).
8. The utility model provides a back pressure type steam-driven draught fan small steam turbine steam exhaust heating system's control system, includes computer equipment, its characterized in that: the computer equipment is programmed to execute the steps of the control method of the back pressure type steam-driven induced draft fan small steam turbine steam exhaust and heat supply system according to any one of claims 1 to 7.
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| CN110410367A (en) * | 2019-08-06 | 2019-11-05 | 华能国际电力股份有限公司海门电厂 | A kind of steam-driven induced draft fan guide vane adaptive-optimum control method |
| CN114321878B (en) * | 2021-12-22 | 2023-08-15 | 江苏核电有限公司 | Transient pressure control method for deaerator during large-amplitude load shedding of nuclear power unit |
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