CN214664331U - Load control system of supercritical heat supply unit - Google Patents
Load control system of supercritical heat supply unit Download PDFInfo
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- CN214664331U CN214664331U CN202120730989.7U CN202120730989U CN214664331U CN 214664331 U CN214664331 U CN 214664331U CN 202120730989 U CN202120730989 U CN 202120730989U CN 214664331 U CN214664331 U CN 214664331U
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Abstract
The utility model discloses a supercritical heat supply unit load control system, including high intermediate pressure jar, steam extraction pressure regulating valve, heat supply network heat exchanger, steam turbine low pressure jar, communicating pipe pressure regulating valve. Because the requirement on steam parameters of heating and steam extraction is not high, a steam source is usually extracted from a steam exhaust position of a steam turbine intermediate pressure cylinder, the extracted steam enters a heat supply heat exchanger, exchanges heat with a cold working medium of a heat supply network user, enters a condenser through a drain pipe, and reenters thermodynamic cycle through a condensate pump. In order to ensure the steam extraction pressure, a communicating pipe pressure regulating valve is arranged on a communicating pipe from the steam extraction of the intermediate pressure cylinder to the inlet of the low pressure cylinder to regulate the steam extraction pressure. And a pressure regulating valve is arranged on the side of the heating steam extraction pipeline and used for regulating the steam flow of the hot working medium of the heat supply network heat exchanger when the demand of a hot user changes.
Description
Technical Field
The utility model belongs to the technical field of the automatic control of thermal power plant, concretely relates to supercritical heat supply unit load control system.
Background
In recent years, the proportion of heat supply units in installed capacity is gradually increased, and the situation that large supercritical units are adopted as heating units is increasing. The supercritical (super) unit has large capacity, high parameters and high thermal efficiency of the whole plant, and can play the roles of energy conservation, environmental protection and emission reduction compared with the conventional cogeneration unit.
Compared with an industrial steam extraction system, the heating steam extraction heat supply system has the characteristics of the heating steam extraction heat supply system. The purpose is to warm for residents and urban utilities, so the requirement on steam extraction parameters is not high, and the steam exhausted from a steam turbine intermediate pressure cylinder is usually used as a steam source. Has obvious seasonality, great annual change and small daily change.
Because the requirement on steam parameters of heating and steam extraction is not high, a steam source is usually extracted from a steam exhaust position of a steam turbine intermediate pressure cylinder, the extracted steam enters a heat supply heat exchanger, exchanges heat with a cold working medium of a heat supply network user, enters a condenser through a drain pipe, and reenters thermodynamic cycle through a condensate pump. In order to ensure the steam extraction pressure, a communicating pipe pressure regulating valve is arranged on a communicating pipe from the steam extraction of the intermediate pressure cylinder to the inlet of the low pressure cylinder to regulate the steam extraction pressure.
When the steam extraction pressure needs to be reduced, the opening degree of the pressure regulating valve of the communicating pipe is increased, so that more steam exhausted by the intermediate pressure cylinder enters the low pressure cylinder to do work. When the steam extraction pressure needs to be improved, the opening degree of the pressure regulating valve of the communicating pipe is reduced, so that more middle pressure cylinder steam exhausts enter a steam extraction system to heat a heat supply network user. Meanwhile, in order to ensure the minimum steam flow of the low-pressure cylinder, when the inlet pressure of the low-pressure cylinder is low, the adjusting door is locked and the valve is closed to be small, so that the safety of the low-pressure cylinder blade is ensured. And a pressure regulating valve is arranged on the side of the heating steam extraction pipeline and used for regulating the steam flow of the hot working medium of the heat supply network heat exchanger when the demand of a hot user changes.
Because the heating heat supply type unit extracts partial steam from the exhaust steam of the intermediate pressure cylinder for heating, the partial steam can be influenced to enter the low pressure cylinder for acting, thereby causing mismatching between the electric load and the heat load of the unit; if the unit electrical load is still used as a reference for unit coordination control at this time, energy imbalance between boiler energy and steam turbine requirements is inevitably caused, so that imbalance of important parameters such as load, temperature and pressure is caused, the safe and stable operation of the unit is further influenced, and the quick response requirement of a power grid AGC on the unit load cannot be met.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to solve the problem among the prior art, provide a supercritical heat supply unit load control system, the utility model discloses can be accurate calculate heating extraction steam heat load to with it in the effectual unit coordinated control system that adds, improve supercritical heat supply unit load control's regulation quality.
In order to achieve the above purpose, the utility model adopts the following technical scheme to realize:
a load control system of a supercritical heat supply unit comprises:
the exhaust steam of the boiler enters a high-medium pressure cylinder to do work, and the exhaust steam after doing work enters a low-pressure cylinder to exhaust steam;
the exhaust steam of the low-pressure cylinder returns to the boiler after sequentially passing through a condenser, a condensate pump, a low-pressure heater, a deaerator, a feed pump and a high-pressure heater;
and a heat source of the heat supply network heat exchanger is from partial exhaust steam of the high and medium pressure cylinder, and is conveyed to an inlet of the condensate pump after heat exchange.
The utility model discloses further improvement lies in:
and one part of the exhaust steam of the high and medium pressure cylinders enters the low pressure cylinder through the communicating pipe pressure regulating valve, and the other part of the exhaust steam enters the heat supply network heat exchanger through the steam extraction pressure regulating valve in sequence.
And a heat supply steam extraction check valve is arranged at the inlet of the steam extraction pressure regulating valve.
Compared with the prior art, the utility model discloses following beneficial effect has:
the utility model discloses to supercritical heat supply unit, from aspects such as heating extraction steam heat calculation, heating power load calculation, unit load control optimization (boiler master control return circuit, main vapour pressure generation return circuit, fuel correction return circuit), consider, guarantee under the accurate prerequisite of heating load calculation, carry out corresponding modification to load control return circuit, satisfy the requirement of taking out the timely response of opportunity group coordination system when the vapour changes. And according to the actual operation condition, a calculation method of the heat supply steam extraction load is reasonably selected, so that the size of the heat supply load is accurately calculated, and the stable operation of the unit coordination control is ensured.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a diagram of a heating and heating steam extraction system.
FIG. 2 is a logic diagram of a thermoelectric load generation circuit.
Fig. 3 shows a heat supply unit load control optimization logic diagram.
Wherein: 1-boiler, 2-high and medium pressure cylinder, 3-low pressure cylinder, 4-condenser, 5-condensate pump, 6-low pressure heater, 7-deaerator, 8-water supply pump, 9-high pressure heater, 10-heat network heat exchanger, 11-communicating pipe pressure regulating valve, 12-heat supply steam extraction check valve, 13-steam extraction pressure regulating valve.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the embodiments of the present invention, it should be noted that, if the terms "upper", "lower", "horizontal", "inner", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, or the orientation or position relationship that the product of the present invention is usually placed when in use, the description is only for convenience of description and simplification, but the indication or suggestion that the device or element to be referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be interpreted as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the embodiments of the present invention, it should be further noted that unless explicitly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.
The present invention will be described in further detail with reference to the accompanying drawings:
referring to fig. 1, the embodiment of the utility model discloses a supercritical heat supply unit load control system, including high intermediate pressure jar 2, steam extraction pressure regulating valve 13, heat supply network heat exchanger 10, steam turbine low pressure jar 3, communicating pipe pressure regulating valve 11. Because the requirement on steam parameters of heating and steam extraction is not high, a steam source is usually extracted from a steam exhaust position of a steam turbine intermediate pressure cylinder, the extracted steam enters a heat supply heat exchanger, exchanges heat with a cold working medium of a heat supply network user, enters a condenser 4 through a drain pipeline, and enters thermodynamic cycle again through a condensate pump 5. In order to ensure the steam extraction pressure, a communicating pipe pressure regulating valve 11 is arranged on a communicating pipe for exhausting steam from the intermediate pressure cylinder to the inlet of the low pressure cylinder 3 to regulate the steam extraction pressure. And a pressure regulating valve is arranged on the side of the heating steam extraction pipeline and used for regulating the steam flow of the hot working medium of the heat supply network heat exchanger 10 when the demand of a heat user changes.
The utility model discloses a heating extraction steam parameter calculation unit is equipped with flow nozzle usually behind the extraction governing valve for measure flow, temperature and the pressure of heating extraction. Therefore, the extraction heat can be calculated through the heating extraction steam parameters. When the load of the unit changes or the demand of a user of a heat supply network changes, the flow, pressure and temperature of heating extraction steam all change rapidly, heating heat calculation is carried out by using the steam parameters, the change condition of the heat load of the extraction steam can be reflected timely and accurately, timely response of the water, coal, air and other sub-circuits of the boiler 1 is ensured, and stable operation of the unit is ensured. When the measurement of the steam extraction pressure is inaccurate or no measuring point exists, the drainage quantity of the heat supply network heater can be adopted for calculation.
After the heating steam extraction heat is calculated, the heating steam extraction heat needs to be converted into an electric load unit, and corresponding judgment switching logic is added to ensure the reality and effectiveness of the heat calculation.
And adding the calculated heat supply electric load into coordinated control to ensure that the heat of the boiler 1 is matched with the requirement of a steam turbine, and the electric load of the generator is consistent with the heat load of the steam turbine.
The supercritical coal-fired unit with the heat supply and steam extraction functions has the advantages that the heat supply load changes slowly, the load control loop is correspondingly modified on the premise of ensuring the heat supply load to be calculated accurately, and the requirement of timely response of a unit coordination system when steam extraction changes can be met. According to the actual operation condition, a calculation method of the heat supply steam extraction load is reasonably selected, so that the size of the heat supply load is accurately calculated, and the key for ensuring the stable operation of the unit coordination control is realized.
The utility model discloses a heating extraction steam parameter calculation unit is equipped with flow nozzle usually behind the extraction governing valve for measure flow, temperature and the pressure of heating extraction. Therefore, the extraction heat can be calculated through the heating extraction steam parameters. The heat formula for calculating the steam extraction parameters is as follows:
qr＝(Ts-T0)Cps+r+(T0-Tw)CpwQm
wherein q isrFor calculating the heat of extraction, TsIs the temperature of extraction, T0Is the saturation temperature at the extraction pressure, CpsIs the specific heat capacity of steam at constant pressure under the extraction pressure, r is the latent heat of vaporization of water vapor, TwIs the hydrophobic temperature, CpwIs the specific heat capacity of water, QmIs the extraction mass flow.
When the load of the unit changes or the demand of a user of a heat supply network changes, the flow, pressure and temperature of heating extraction steam all change rapidly, heating heat calculation is carried out by using the steam parameters, the change condition of the heat load of the extraction steam can be reflected timely and accurately, timely response of the water, coal, air and other sub-circuits of the boiler 1 is ensured, and stable operation of the unit is ensured. When the measurement of the steam extraction pressure is inaccurate or no measuring point exists, the drainage quantity of the heat supply network heater can be adopted for calculation. And when the heat supply network cold working medium parameter is adopted to calculate the stable state of the heat supply network system, the heat consumed by the heat supply network for steam extraction is equal to the heat absorption capacity of the user side cold working medium. Therefore, when the steam extraction flow or the drainage quantity is measured inaccurately, the temperature and the flow of the inlet water at the user side of the heat supply network can be used for heat calculation. The calculation formula is as follows:
qr＝(T1-T2)Cpw Qm
wherein q isrFor calculating the heat of extraction, T1For the side outlet temperature, T, of the heat supply network2Temperature of the side inlet water for the user of the heat supply network, CpwIs the specific heat capacity of water, QmThe water mass flow of the user side of the heat supply network.
The heat of extraction calculated by the above formula is an energy unit, and it needs to be converted into a power unit. The conversion formula is as follows:
Prl＝1000qr/3600＝0.278qr
wherein q isrFor calculating the heat of extraction, GJ/h; prlTo calculate thermal power, MW.
Since the heating extraction steam is extracted from the steam exhaust position of the middle pressure cylinder, the part of steam does not enter the low pressure cylinder 3 to do work, and therefore the heat power calculated in the above formula needs to be converted into electric power. The conversion formula is as follows:
Pr＝K×ηLP×Prl。
wherein, PrlFor calculating thermal power，MW；PrFor calculating the extraction thermoelectric power, MW; etaLPThe efficiency of the low-pressure cylinder 3 can be obtained by the specification of a steam turbine; k is a correction coefficient and can be obtained by comparison calculation according to two working conditions of non-heat supply and heat supply of the on-site unit.
The heat supply load is calculated by measuring points such as working medium flow, temperature and pressure, the influence factors are more, and the flow fluctuation of the water side is more frequent, so that corresponding logic judgment is needed, and the heat supply load calculation is real and effective. The specific logic is shown in figure 2.
When the heating steam extraction check valve 12 is closed or the command of the steam extraction pressure regulating valve 13 is less than 5%, delaying for 20s, and considering that the heating steam extraction loop is cut off at the moment, and the heating electric load is cut to 0 from the calculated value. When the heating and power supply load is calculated to have bad quality, the calculation load is locked, and load fluctuation caused by inaccurate measuring points is avoided.
Because the control scheme aims at heating heat load, the daily change amplitude is small, the large fluctuation of the calculated electric load caused by measuring point disturbance is avoided, and the load calculation locking function is added. When the calculated thermoelectric load change is small, the current value is kept, and the system is kept stable. When the load calculation value changes greatly, a tracking actual calculation value is output, and the accuracy of a calculation result is ensured. In order to avoid the fluctuation of the calculated measuring point and the large measuring error, the links of speed limit, inertia and high and low amplitude limiting are added, and finally the heating and power load required by the coordination control is obtained.
According to the calculated heat supply electric load, the heat supply electric load is added into the coordination control, the heat of the boiler 1 is ensured to be matched with the requirement of a steam turbine, the electric load of the generator is consistent with the heat load of the steam turbine, and the specific logic is shown in figure 3.
(1) Boiler 1 main control loop. When the heat supply steam extraction electric load changes, the energy change of the boiler 1 is directly required, so the calculated load is superposed into the main control instruction feedforward of the boiler 1, and the corresponding increase and decrease of sub-circuits such as wind, coal, water and the like are ensured, thereby ensuring the timely response of the boiler 1 when the heat supply load changes.
(2) A main steam pressure generating circuit. Due to the generation of heat supply extraction steam, the steam inlet quantity of the steam turbine is increased, and deviation is generated with actual electric load. If still according to original sliding pressure curve operation this moment, can lead to the main vapour pressure to hang down excessively, the accent door aperture is too big, has reduced unit economic nature to influence safety. Therefore, the sliding pressure curve of the steam turbine with the heating and power load superposition value needs to be generated into a loop, and the main steam pressure of the unit is ensured to be normal.
(3) A fuel correction circuit (BTU). The fuel correction loop adjusts the fuel correction coefficient according to the difference between the current load design coal quantity and the actual coal quantity, thereby realizing the coordination control self-adaption function when the coal type changes. Therefore, the heating power load needs to be superposed in the design coal amount calculation loop, and the adjustment accuracy of the fuel correction loop is ensured.
The supercritical coal-fired unit with the heat supply and steam extraction functions has the advantages that the heat supply load changes slowly, the load control loop is correspondingly modified on the premise of ensuring the heat supply load to be calculated accurately, and the requirement of timely response of a unit coordination system when steam extraction changes can be met. According to the actual operation condition, a calculation method of the heat supply steam extraction load is reasonably selected, so that the size of the heat supply load is accurately calculated, and the key for ensuring the stable operation of the unit coordination control is realized.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. A load control system of a supercritical heat supply unit is characterized by comprising:
the steam exhaust of the boiler (1) enters a high and medium pressure cylinder (2) to do work, and the steam exhaust after doing work enters a low pressure cylinder (3) to exhaust steam;
the low-pressure steam generator comprises a low-pressure cylinder (3), wherein exhaust steam of the low-pressure cylinder (3) returns to a boiler (1) after sequentially passing through a condenser (4), a condensate pump (5), a low-pressure heater (6), a deaerator (7), a water feed pump (8) and a high-pressure heater (9);
and a heat source of the heat supply network heat exchanger (10) is from partial exhaust steam of the high and medium pressure cylinder (2), and the heat is transferred to an inlet of the condensate pump (5).
2. The load control system of the supercritical heat supply unit according to claim 1, characterized in that a part of the exhaust steam of the high and medium pressure cylinder (2) enters the low pressure cylinder (3) through the communicating pipe pressure regulating valve (11), and the other part enters the heat network heat exchanger (10) through the steam extraction pressure regulating valve (13) in turn.
3. The load control system of a supercritical heat supply unit according to claim 2 characterized in that the inlet of the extraction pressure regulating valve (13) is provided with a heating extraction check valve (12).
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