Thermal power plant peak and frequency regulation steam supply system and operation method thereof

Abstract

The embodiment of the invention provides a thermal power plant peak and frequency modulation steam supply system and an operation method thereof. A superheated steam outlet of a coal-fired boiler of the system communicates with a steam inlet of a high-pressure cylinder, a steam outlet of the high-pressure cylinder communicates with a reheat steam inlet of the coal-fired boiler, and a reheat steam outlet of the coal-fired boiler communicates with a steam header; the reheat steam outlet of the coal-fired boiler is further communicated with a steam inlet of the medium-pressure cylinder, and a steam outlet of the medium-pressure cylinder is communicated with a steam inlet of the low-pressure cylinder; the low-pressure cylinder is further connected to a generator, and the generator is connected to a boosting transformer and an electrode steam boiler transformer. The boosting transformer is used for supplying power to a power grid, the electrode steam boiler transformer is further connected to an electrode steam boiler, the electrode steam boiler is communicated with a steam header, and the steam header supplies steam to heat consumers through a steam pipe network. According to the thermal power plant peak regulation and frequency modulation steam supply system, the problem that the thermal power plant cannot meet the heat supply requirement in the deep peak regulation period can be solved.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the field of thermal power technology, and specifically relate to a peak-shaving and frequency-regulating steam supply system for a thermal power plant and an operation method thereof. Background Art

[0002] In recent years, new energy power generation technology has developed rapidly, and the installed capacity of wind power and photovoltaic power generation has increased year by year. Today, the installed capacity of non-fossil energy has exceeded 50% of the total installed capacity, and the proportion is still increasing. The continuous increase in the proportion of new energy requires that traditional thermal power, especially cogeneration units, can be adjusted more flexibly. However, the existing cogeneration units are highly coupled in heating and power generation, and it is difficult to ensure that the corresponding heat load can meet user needs when adjusting the electrical load. This puts higher requirements on the cogeneration units and requires deeper improvements to the cogeneration units. Summary of the invention

[0003] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art, and provide a peak-shaving and frequency-regulating steam supply system for a thermal power plant and an operation method thereof.

[0004] On the one hand, an embodiment of the present disclosure provides a peak-shaving and frequency-regulating steam supply system for a thermal power plant, the system comprising a coal-fired boiler, a high-pressure cylinder, a medium-pressure cylinder, a steam header, a low-pressure cylinder, a generator, a step-up transformer, an electrode steam boiler transformer, an electrode steam boiler, and a steam pipe network;

[0005] The superheated steam outlet of the coal-fired boiler is communicated with the steam inlet of the high-pressure cylinder, the steam outlet of the high-pressure cylinder is communicated with the reheated steam inlet of the coal-fired boiler, and the reheated steam outlet of the coal-fired boiler is communicated with the steam header;

[0006] The reheat steam outlet of the coal-fired boiler is also connected to the steam inlet of the intermediate pressure cylinder, and the steam outlet of the intermediate pressure cylinder is connected to the steam inlet of the low pressure cylinder; the low pressure cylinder is also connected to the generator, and the generator is respectively connected to the step-up transformer and the electrode steam boiler transformer; wherein,

[0007] The step-up transformer is used to supply power to the power grid, the electrode steam boiler transformer is also connected to the electrode steam boiler, the electrode steam boiler is connected to the steam manifold, and the steam manifold supplies steam to heat users through the steam pipe network.

[0008] Optionally, the system further comprises a delivery pipeline and a first electric regulating valve;

[0009] The inlet of the delivery pipeline is communicated with the reheat steam outlet of the coal-fired boiler, and the outlet of the delivery pipeline is communicated with the inlet of the steam header; and the first electric regulating valve is arranged in series on the delivery pipeline.

[0010] Optionally, the steam outlet of the high-pressure cylinder is also connected to the inlet of the delivery pipeline.

[0011] Optionally, the system further comprises a second electric regulating valve;

[0012] The second electric regulating valve is disposed between the electrode steam boiler and the steam header.

[0013] Optionally, the system further comprises a steam storage tank; the steam storage tank and the steam pipe network are arranged in parallel with each other.

[0014] Optionally, actual operating parameter values ​​of the steam network are lower than their design parameter values.

[0015] Optionally, the electrode steam boiler includes an electric superheater, through which the outlet steam of the electrode steam boiler is matched with the steam parameters in the steam manifold.

[0016] On the other hand, an embodiment of the present disclosure provides an operation method of a peak-shaving and frequency-regulating steam supply system of a thermal power plant, using the system described above, the operation method comprising:

[0017] When the power generation load is high, the reheated steam provided by the coal-fired boiler enters the steam network to supply steam to heat users, and the electrode steam boiler does not operate;

[0018] When the power generation load is low, the reheat steam is extracted according to the maximum value to ensure the safety of the unit, and at the same time the electrode steam boiler is put into operation, and the two together supply steam to the heat users.

[0019] Optionally, when the system includes a first electric regulating valve and a second electric regulating valve, the operating method further includes:

[0020] When the power generation load is high, the first electric regulating valve performs frequency modulation according to the maximum value of its own action rate through valve switching and adjustment actions in coordination with the AGC instruction of the thermal power unit to increase the AGC frequency modulation capability of the thermal power unit;

[0021] When the power generation load is low, the first electric regulating valve and the second electric regulating valve both adjust the frequency according to the maximum value of their own action rate through the switching and adjustment actions of the valves in coordination with the AGC instructions of the thermal power unit to increase the AGC frequency regulation capability of the thermal power unit.

[0022] Optionally, when the system further includes a steam storage tank, the operating method further includes:

[0023] When the operation of the first electric regulating valve and the second electric regulating valve causes the steam supply pressure to fluctuate, the steam supply pressure fluctuation is reduced by the steam storage tank, thereby improving the stability of the steam supply pressure.

[0024] The peak-shaving and frequency-regulating steam supply system for a thermal power plant and its operating method of the embodiments of the present disclosure can solve the problem of poor economic benefits caused by the power plant supplying steam to the outside due to electricity price fluctuations or deep peak-shaving in the electricity spot trading market. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a schematic structural diagram of a peak-shaving and frequency-regulating steam supply system for a thermal power plant according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0027] like Figure 1 As shown, a peak-shaving and frequency-regulating steam supply system 100 for a thermal power plant, the system 100 comprises a coal-fired boiler 110, a high-pressure cylinder 111, a medium-pressure cylinder 112, a steam header 120, a low-pressure cylinder 113, a generator 130, a step-up transformer 140, an electrode steam boiler transformer 150, an electrode steam boiler 160 and a steam network 170. The superheated steam outlet of the coal-fired boiler 110 is connected to the steam inlet of the high-pressure cylinder 111, the steam outlet of the high-pressure cylinder 111 is connected to the reheated steam inlet of the coal-fired boiler 110, and the reheated steam outlet of the coal-fired boiler 110 is connected to the steam header 120.

[0028] The reheat steam outlet of the coal-fired boiler 110 is also connected to the steam inlet of the intermediate pressure cylinder 112, and the steam outlet of the intermediate pressure cylinder 112 is connected to the steam inlet of the low pressure cylinder 113. The low pressure cylinder 113 is also connected to the generator 130, and the generator 130 is respectively connected to the boost transformer 140 and the electrode steam boiler transformer 150. Among them, the boost transformer 140 is used to supply power to the power grid, and the electrode steam boiler transformer 150 is also connected to the electrode steam boiler 160, and the electrode steam boiler 160 is connected to the steam header 120, and the steam header 120 supplies steam to the heat user 200 through the steam pipe network 170.

[0029] Specifically, Figure 1As shown, the steam source of external industrial steam comes from two aspects. On the one hand, it is the reheated steam (extraction steam from the reheating hot section) of the coal-fired boiler 110. After the reheated steam enters the steam header 120, it is sent to the heat user 200 through the steam pipe network 170. On the other hand, it is the superheated steam generated by the electrode steam boiler 160. After the superheated steam enters the steam header 120, it is also sent to the heat user 200 through the steam pipe network 170. The outlet of the steam header 120 is connected to the steam pipe network 170. The steam pipe network 170 can be set as a long-distance industrial steam pipe network. The end of the long-distance industrial steam pipe network is a steam user, that is, a heat user.

[0030] When the power generation load is high, the steam extraction volume and pressure of the reheating hot section of the thermal power unit can meet the requirements. This part of the steam extraction enters the heating network to supply heat users. At this time, the electrode steam boiler does not work. When the power generation load is low, the steam extraction volume and pressure of the reheating hot section of the thermal power unit are not enough to meet the requirements due to peak load regulation. At this time, steam extraction is carried out according to the maximum value of the reheating hot section steam extraction to ensure the safety of the unit. At the same time, the electrode steam boiler is put into operation, and the two jointly supply steam to heat users. The investment of the electrode steam boiler can reduce the amount of power connected to the grid and further play a role in deep peak load regulation.

[0031] It is not difficult to understand that the superheated steam released by the coal-fired boiler 110 first enters the high-pressure cylinder 111 to do work, and the exhaust steam of the high-pressure cylinder 111 continues to enter the coal-fired boiler 110 to be reheated to form reheated steam. Part of the reheated steam is directly transported to the steam header 120, and the other part enters the medium-pressure cylinder 112 to do work, and the exhaust steam of the medium-pressure cylinder 112 enters the low-pressure cylinder 113 to do work. The total amount of work done by the high-pressure cylinder 111, the medium-pressure cylinder 112 and the low-pressure cylinder 113 is converted into electrical energy through the generator 130, and is sent to the power grid for power supply through the step-up transformer 140. The power supply of the electrode steam boiler 160 comes from the electrode steam boiler transformer 150, and the electrode steam boiler transformer 150 can be a special transformer newly added between the generator 130 and the step-up transformer 140. If the remaining capacity of the high-voltage plant transformer of the thermal power plant is sufficient, the high-voltage plant transformer can also be used as the electrode steam boiler transformer.

[0032] It should be noted that in order to achieve the flexibility of the cogeneration unit, the electrode steam boiler is used to transform the unit. The electrode steam boiler is very suitable for application scenarios where the thermal power plant has more deep peak regulation periods, fewer peak periods, and insufficient low-load steam extraction capacity to meet the heating demand.

[0033] The peak-shaving and frequency-regulating steam supply system for thermal power plants of the disclosed embodiments can solve the problem of poor economic benefits caused by the external supply of steam by existing units in the electricity spot market due to electricity price fluctuations or deep peak-shaving. The use of electrode steam boilers solves the problem of the inability to meet the steam parameters of heat users due to insufficient steam extraction capacity of thermal power units under low load. At the same time, when the thermal power units are supplied with steam at low load by electrode steam boilers, the online power consumption of the thermal power units can be further reduced, further deep peak-shaving can be achieved, and deep peak-shaving benefits or spot benefits can be obtained.

[0034] For example, Figure 1 As shown, the system 100 further includes a delivery pipeline 180 and a first electric regulating valve 181. The inlet of the delivery pipeline 180 is connected to the reheat steam outlet of the coal-fired boiler 110, and the outlet of the delivery pipeline 180 is connected to the inlet of the steam header 120. And, the first electric regulating valve 181 is arranged in series with the delivery pipeline 180.

[0035] Specifically, Figure 1 As shown, part of the reheated steam of the coal-fired boiler 110 enters the steam header 120 through the delivery pipeline 180 under the control of the first electric regulating valve 181 .

[0036] Furthermore, the steam outlet of the high-pressure cylinder 111 is also connected to the inlet of the delivery pipeline 180. In addition to entering the coal-fired boiler 110, part of the exhaust steam of the high-pressure cylinder 111 will enter the steam header 120 through the delivery pipeline 130. The exhaust steam from the steam outlet of the high-pressure cylinder 111 to the inlet of the delivery pipeline 130 is the reheat cold section extraction steam. The steam source of the part of the external industrial steam delivered by the delivery pipeline 130 can be either the reheat hot section extraction steam or the reheat cold section extraction steam.

[0037] Furthermore, the system 100 further includes a second electric regulating valve 190. The second electric regulating valve 190 is disposed between the electrode steam boiler 160 and the steam header 120. The superheated steam generated by the electrode steam boiler 160 enters the steam header 120 under the control of the second electric regulating valve 190.

[0038] When the power generation load is high, the first electric regulating valve 181 performs frequency modulation according to the maximum value of its own action rate through the valve switching and adjustment action in coordination with the AGC instruction of the thermal power unit to increase the AGC frequency modulation capability of the thermal power unit. When the power generation load is low, the first electric regulating valve 181 and the second electric regulating valve 190 perform frequency modulation according to the maximum value of their own action rate through the valve switching and adjustment action in coordination with the AGC instruction of the thermal power unit to increase the AGC frequency modulation capability of the thermal power unit. By utilizing the action of the electric regulating valve, the AGC instruction of the thermal power unit can be coordinated to improve the frequency modulation capability of the unit.

[0039] For example, Figure 1 As shown, the system 100 further includes a steam storage tank 171. The steam storage tank 171 and the steam pipe network 170 are arranged in parallel with each other.

[0040] Specifically, if Figure 1 As shown, the steam storage tank 171 is operated in parallel with the steam network 170. When the first electric regulating valve 181 and the second electric regulating valve 190 are in operation, the pressure of the heat user 200 will fluctuate according to the duration of the electric regulating valve valve operation. The steam storage tank 171 can reduce the pressure fluctuation of the terminal heat user 200 and improve the stability of steam supply. For example, when the pressure of the heat user is high, the steam released from the steam header is stored in the steam storage tank. When the pressure of the heat user is low, the steam storage tank releases steam to increase the pressure.

[0041] The peak-shaving and frequency-regulating steam supply system of a thermal power plant in the embodiment of the present disclosure can reduce the fluctuation of steam parameters of end heat users caused by the operation of the electric regulating valve on the power plant side by connecting steam storage tanks in parallel in the steam pipeline network, thereby maintaining a high heating quality.

[0042] Exemplarily, the actual operating parameter value of the steam network 170 is lower than its design parameter value. Such a setting enables it to have a certain regulation margin, and the steam storage tank 171 can be used as a storage device for system heat. It should be noted that the steam temperature and pressure required by the heat user 200 are much lower than the temperature and pressure of the steam manifold 120 on the power plant side. Furthermore, the electrode steam boiler 160 includes an electric superheater (not shown in the figure), through which the outlet steam of the electrode steam boiler 160 is matched with the steam parameters in the steam manifold 120.

[0043] On the other hand, an embodiment of the present disclosure provides an operation method of a peak-shaving and frequency-regulating steam supply system of a thermal power plant, using the system described above, and the operation method includes: when the power generation load is high, the reheated steam provided by the coal-fired boiler enters the steam pipe network to supply steam to the heat user, and the electrode steam boiler does not operate. When the power generation load is low, the reheated steam is extracted according to the maximum value to ensure the safety of the unit, and the electrode steam boiler is put into operation at the same time, and the two jointly supply steam to the heat user.

[0044] Specifically, in this step, when the power generation load is high, the steam extraction volume and pressure of the reheat hot section extraction steam of the thermal power unit can meet the requirements, and this part of the extraction steam is used to enter the steam pipeline network to supply steam to the terminal heat users. At this time, the electrode steam boiler does not work. It should be noted that if the steam extraction volume and pressure of the reheat cold section extraction steam of the thermal power unit can meet the requirements, the reheat cold section extraction steam of the thermal power unit can also be used to supply steam to the heat users. When the power generation load is low, the steam extraction volume and pressure of the reheat cold section extraction steam or the reheat hot section extraction steam of the thermal power unit are not enough to meet the requirements due to peak regulation. At this time, steam is extracted according to the maximum value of the reheat cold section or the hot section to ensure the safety of the unit, and the electrode steam boiler is put into operation at the same time, and the two jointly supply steam to the terminal heat users. The investment of the electrode steam boiler can reduce the amount of power connected to the grid and further play a role in deep peak regulation.

[0045] The operating method of the peak-shaving and frequency-regulating steam supply system of a thermal power plant in the embodiment of the present disclosure can use an electrode steam boiler to solve the problem of insufficient steam extraction capacity of the thermal power unit under low load and inability to meet the steam parameters of heat users. When the thermal power unit supplies steam to the outside at low load, the online power consumption of the thermal power unit can be further reduced, thereby achieving further deep peak-shaving and obtaining deep peak-shaving benefits or spot benefits.

[0046] Furthermore, when the system includes a first electric regulating valve and a second electric regulating valve, the operation method further includes: when the power generation load is high, the first electric regulating valve performs frequency modulation according to the maximum value of its own action rate, through the opening and closing and regulating actions of the valve in coordination with the AGC instruction of the thermal power unit, so as to increase the AGC frequency modulation capability of the thermal power unit. When the power generation load is low, both the first electric regulating valve and the second electric regulating valve perform frequency modulation according to the maximum value of their own action rate, through the opening and closing and regulating actions of the valve in coordination with the AGC instruction of the thermal power unit, so as to increase the AGC frequency modulation capability of the thermal power unit.

[0047] Specifically, in this step, when the power generation load is high, the steam extraction volume and pressure of the reheating cold section extraction steam or the reheating hot section extraction steam of the thermal power unit can meet the requirements, and this part of the extraction steam is used to enter the steam pipeline network to supply steam to the terminal heat user. At this time, the electrode steam boiler does not work. The first electric regulating valve adjusts the frequency according to the maximum value of its own action rate through the valve switching and adjustment action to cooperate with the AGC instruction of the thermal power unit to increase the AGC frequency regulation capability of the thermal power unit.

[0048] When the power generation load is low, the extraction volume and pressure of the reheat cold section or reheat hot section extraction steam are insufficient to meet the requirements due to peak load regulation. At this time, steam is extracted according to the maximum value of the reheat cold section or hot section to ensure the safety of the unit. At the same time, the electrode steam boiler is put into operation, and the two jointly supply steam to the terminal heat users. The commissioning of the electrode steam boiler can reduce the amount of electricity connected to the grid and further play a role in deep peak load regulation. The first electric control valve and the second electric control valve adjust the frequency according to the maximum value of their own action rate through the opening and closing and adjustment actions of the valves in coordination with the AGC instructions of the thermal power unit, thereby increasing the AGC frequency regulation capability of the thermal power unit.

[0049] The operating method of the peak-shaving and frequency-regulating steam supply system of a thermal power plant in the embodiment of the present disclosure utilizes the action of the electric regulating valve to cooperate with the instructions of the AGC of the thermal power unit to improve the frequency regulation capability of the unit.

[0050] Furthermore, when the system further includes a steam storage tank, the operation method further includes: when the first electric regulating valve and the second electric regulating valve cause a fluctuation in the steam supply pressure, the fluctuation in the steam supply pressure is reduced by the steam storage tank, thereby improving the stability of the steam supply pressure.

[0051] Specifically, in this step, when the first electric regulating valve and the second electric regulating valve are actuated, the pressure of the heat user will fluctuate according to the duration of the electric regulating valve action. The steam storage tank can reduce the pressure fluctuation of the terminal heat user and improve the steam supply stability.

[0052] The operating method of the peak-shaving and frequency-regulating steam supply system of a thermal power plant in the embodiment of the present disclosure connects a steam storage tank in parallel in the steam pipeline network, which can reduce the fluctuation of the steam parameters of the heat users caused by the operation of the electric regulating valve on the power plant side and maintain a high heating quality.

[0053] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A peak-shaving and frequency-regulating steam supply system for a thermal power plant. It is characterized in that The system includes a coal-fired boiler, a high-pressure cylinder, a medium-pressure cylinder, a steam header, a low-pressure cylinder, a generator, a step-up transformer, an electrode steam boiler transformer, an electrode steam boiler and a steam network; The superheated steam outlet of the coal-fired boiler is communicated with the steam inlet of the high-pressure cylinder, the steam outlet of the high-pressure cylinder is communicated with the reheated steam inlet of the coal-fired boiler, and the reheated steam outlet of the coal-fired boiler is communicated with the steam header; The reheat steam outlet of the coal-fired boiler is also connected to the steam inlet of the intermediate pressure cylinder, and the steam outlet of the intermediate pressure cylinder is connected to the steam inlet of the low pressure cylinder; the low pressure cylinder is also connected to the generator, and the generator is respectively connected to the step-up transformer and the electrode steam boiler transformer; wherein, The step-up transformer is used to supply power to the power grid, the electrode steam boiler transformer is also connected to the electrode steam boiler, the electrode steam boiler is connected to the steam manifold, and the steam manifold supplies steam to heat users through the steam pipe network.

2. The peak-shaving and frequency-regulating steam supply system for a thermal power plant according to claim 1, It is characterized in that The system also includes a delivery pipeline and a first electric regulating valve; The inlet of the delivery pipeline is communicated with the reheat steam outlet of the coal-fired boiler, and the outlet of the delivery pipeline is communicated with the inlet of the steam header; and the first electric regulating valve is arranged in series on the delivery pipeline.

3. The peak-shaving and frequency-regulating steam supply system for thermal power plants according to claim 2, It is characterized in that The steam outlet of the high-pressure cylinder is also communicated with the inlet of the delivery pipeline.

4. The peak-shaving and frequency-regulating steam supply system for a thermal power plant according to claim 2, It is characterized in that The system also includes a second electric regulating valve; The second electric regulating valve is disposed between the electrode steam boiler and the steam header.

5. The peak-shaving and frequency-regulating steam supply system for thermal power plants according to claim 4, It is characterized in that The system further comprises a steam storage tank; the steam storage tank and the steam pipe network are arranged in parallel with each other.

6. The peak-shaving and frequency-regulating steam supply system for a thermal power plant according to any one of claims 1 to 5, It is characterized in that The actual operating parameter values ​​of the steam network are lower than the design parameter values ​​thereof.

7. The peak-shaving and frequency-regulating steam supply system for a thermal power plant according to any one of claims 1 to 5, It is characterized in that The electrode steam boiler comprises an electric superheater, through which the outlet steam of the electrode steam boiler is matched with the steam parameters in the steam header.

8. An operating method for a peak-shaving and frequency-regulating steam supply system in a thermal power plant, It is characterized in that Using the system according to any one of claims 1 to 7, the operating method comprises: When the power generation load is high, the reheated steam provided by the coal-fired boiler enters the steam network to supply steam to heat users, and the electrode steam boiler does not operate; When the power generation load is low, the reheat steam is extracted according to the maximum value to ensure the safety of the unit, and at the same time the electrode steam boiler is put into operation, and the two together supply steam to the heat users.

9. The operating method according to claim 8, It is characterized in that When the system includes a first electric regulating valve and a second electric regulating valve, the operating method further includes: When the power generation load is high, the first electric regulating valve performs frequency modulation according to the maximum value of its own action rate through valve switching and adjustment actions in coordination with the AGC instruction of the thermal power unit to increase the AGC frequency modulation capability of the thermal power unit; When the power generation load is low, the first electric regulating valve and the second electric regulating valve both adjust the frequency according to the maximum value of their own action rate through the switching and adjustment actions of the valves in coordination with the AGC instructions of the thermal power unit to increase the AGC frequency regulation capability of the thermal power unit.

10. The operating method according to claim 9, It is characterized in that When the system further includes a steam storage tank, the operating method further includes: When the operation of the first electric regulating valve and the second electric regulating valve causes the steam supply pressure to fluctuate, the steam supply pressure fluctuation is reduced by the steam storage tank, thereby improving the stability of the steam supply pressure.

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