Flexible peak and frequency regulation system and method utilizing steam to drive gravity energy storage

Abstract

The invention discloses a flexible peak and frequency regulation system and method for utilizing steam to drive gravity energy storage. The system comprises a generator set, a back pressure turbine heat supply system and a gravity energy storage system. The generator set comprises a boiler, a main steam pipeline of the boiler communicates with a turbine high-pressure cylinder, an outlet of the turbine high-pressure cylinder communicates with the boiler through a pipeline and communicates with a turbine intermediate-pressure cylinder through a reheat steam pipeline, and an outlet of the turbine intermediate-pressure cylinder communicates with a turbine low-pressure cylinder. The back pressure machine heat supply system comprises a back pressure machine, the back pressure machine is communicated with a reheat steam pipeline through a reheat steam extraction pipeline, and the back pressure machine is communicated with the gravity energy storage system through a speed change device. The gravity energy storage system is driven by steam generated by the unit, when the load of the unit needs to be reduced, heat energy is converted into gravitational potential energy to be stored through the steam-driven gravity energy storage system, the amount of steam entering a steam turbine to do work is reduced, the power generation load is reduced, and the extracted steam is supplied with heat after being subjected to energy storage through the back pressure turbine; and gradient utilization of energy is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of peak load regulation in coal-fired power plants, and in particular to a flexible peak load regulation and frequency regulation system and method utilizing steam-driven gravity energy storage. Background Art

[0002] In order to achieve the "dual carbon" goal, the power industry has stepped up efforts to build new energy power stations such as solar and wind power. With the continuous growth of new energy installed capacity, its share in the energy structure has also increased rapidly. The intermittent and unstable shortcomings of new energy power generation such as solar and wind power have also become increasingly prominent, which has had a significant impact on the stability and security of the power grid.

[0003] In order to cope with the impact of new energy sources such as solar energy and wind energy on the stability of the power grid after grid connection and to ensure the stability and safety of the power system, the grid dispatching agency usually requires coal-fired units to undertake peak load and frequency regulation tasks. However, due to the aging of the unit equipment or the task of heating and livelihood protection, the peak load regulation capacity of some units is limited. Therefore, it is urgent to improve the peak load and frequency regulation capabilities of some existing units. Coupling coal-fired units with energy storage devices is an effective way to improve the peak load and frequency regulation capabilities of coal-fired units.

[0004] The patent with application number CN202310069483 discloses a peak-shaving system for flexible transformation of thermal power plants coupled with gravity energy storage and a method thereof. The patent sets a gravity energy storage device between a large generator and a power grid, uses electric energy to drive a lifting machine to move a gravity block, and stores electric energy in the gravity energy storage device. However, in the process of power generation, the conversion of steam heat energy into electric energy results in cold source loss, and about 50-60% of the energy will be wasted, which is well known in the power industry. Therefore, using electric energy to drive a gravity energy storage device is uneconomical and environmentally unfriendly.

[0005] Therefore, researching and developing a flexible peak-shaving and frequency-regulating system and method using steam-driven gravity energy storage is of great significance for peak-shaving and frequency-regulating coal-fired power plants, maintaining grid stability, and energy conservation and environmental protection. Summary of the invention

[0006] In order to solve the above technical problems, the present invention designs a flexible peak-shaving and frequency-modulating system and method using steam-driven gravity energy storage. The present invention uses the steam generated by the unit to drive the gravity energy storage system. When the load of the unit needs to be reduced, the steam in the unit is extracted to drive the gravity energy storage system to convert the thermal energy into gravitational potential energy for storage, thereby reducing the amount of steam entering the steam turbine to do work and reducing the power generation load. The extracted steam is stored in the back pressure machine and then used for heat supply, thereby realizing the cascade utilization of energy.

[0007] The present invention adopts the following technical solution: A flexible peak-shaving and frequency-regulating system using steam-driven gravity energy storage, comprising a generator set, a back pressure machine heating system and a gravity energy storage system; The generator set comprises a boiler, the main steam pipe of the boiler is connected to the high-pressure cylinder of the steam turbine, the outlet of the high-pressure cylinder of the steam turbine is connected back to the boiler through a pipeline, and is connected to the medium-pressure cylinder of the steam turbine through the reheat steam pipe of the boiler, and the outlet of the medium-pressure cylinder of the steam turbine is connected to the low-pressure cylinder of the steam turbine; The back pressure machine heating system includes a back pressure machine, which is connected to the reheat steam pipeline through a reheat steam extraction pipeline. The back pressure machine is connected to the gravity energy storage system through a speed change device, and the speed change device transfers the kinetic energy of the back pressure machine to the gravity energy storage system.

[0008] Preferably, the gravity energy storage system includes a gravity energy storage device, which includes a gravity energy storage unit and a lifting device. The speed change device is connected to the lifting device and drives the lifting device to work. The lifting device transports the gravity energy storage unit to a high place to complete energy storage and realize peak load and frequency regulation of the unit.

[0009] Preferably, the high-pressure cylinder, medium-pressure cylinder and low-pressure cylinder of the steam turbine are connected to a large generator. The steam expands in the high, medium and low cylinders of the steam turbine to drive the large generator to rotate and generate electricity. Preferably, the outlet of the back pressure machine is connected to a heat exchange station through a heating pipeline. The heat exchange station transfers the exhaust steam heat to heating water, which is then supplied to heating users.

[0010] Preferably, the back pressure machine outlet is connected to regulating valve 1 through an industrial steam supply pipeline, and the steam pressure and temperature are adjusted by regulating valve 1 before being directly supplied to industrial steam users.

[0011] Preferably, the back pressure machine outlet is connected back to the low-pressure cylinder of the steam turbine through a return pipe.

[0012] Preferably, the exhaust port of the low-pressure cylinder of the steam turbine is connected to the condenser, the condenser is connected to the low-pressure heater through the condensate pump, the low-pressure heater is connected to the deaerator, the deaerator is connected to the high-pressure heater through the feedwater pump, the high-pressure heater is connected back to the boiler through a pipeline, and the steam extraction port of the intermediate-pressure cylinder of the steam turbine is connected to the deaerator, completing a steam-water cycle.

[0013] Preferably, a regulating valve 2 is installed on the return pipeline to adjust the steam pressure and temperature.

[0014] Preferably, the gravity energy storage system is connected to a small generator. The lifting equipment moves the gravity energy storage unit to a lower place and drives the small generator to rotate and generate electricity, thereby releasing energy and achieving peak power and frequency modulation of the unit.

[0015] A flexible peak-shaving and frequency-regulating method using steam-driven gravity energy storage, the method steps are as follows: when a generator set receives a deep peak-shaving instruction from a power grid, reheat steam is extracted through a reheat steam extraction pipeline or the reheat steam extraction amount is increased, at which time the steam flow entering the intermediate pressure cylinder and the low pressure cylinder of the steam turbine is reduced, the work capacity of the steam is reduced, the power generation of the large generator is reduced, and the load of the generator set is reduced; The reheated steam enters the back compressor to expand and do work. The back compressor rotates, and the speed change device transfers the kinetic energy of the back compressor to the gravity energy storage system. The lifting equipment moves the gravity energy storage unit to a high place to complete the energy storage. The exhaust steam at the outlet of the back pressure machine is utilized through lines Ⅰ, Ⅱ, and Ⅲ to meet the needs of different users; when the exhaust steam is utilized according to line Ⅰ, the exhaust steam enters the heat exchange station through the heating pipeline, completes the transfer of heat to the heating water, and realizes heating for users; when the exhaust steam is utilized according to line Ⅱ, the exhaust steam passes through the heating pipeline, and after the steam pressure and temperature are adjusted by the regulating valve 1, it is directly supplied to industrial steam users; when the exhaust steam is utilized according to line Ⅲ, the exhaust steam passes through the return pipeline, and after the steam pressure and temperature are adjusted by the regulating valve 2, it returns to the low-pressure cylinder of the steam turbine to continue to expand and do work; When the generator set receives the peak power command from the power grid, the lifting equipment moves the gravity energy storage unit to a lower place, and at the same time drives the small generator to rotate and generate electricity. The gravity energy storage device completes the energy release and achieves the peak power. When the generator set receives a frequency regulation instruction from the power grid, the frequency regulation of the set can be achieved by controlling the extraction amount of reheat steam and the number of gravity energy storage units transported. At the same time, the frequency regulation of the set can also be achieved by controlling the speed of the lifting equipment transporting the gravity energy storage units through the speed change device.

[0016] The beneficial effects of the present invention are as follows: (1) The present invention directly utilizes steam thermal energy as a power source without converting it into electrical energy, thereby reducing cold source loss and being more energy-efficient; (2) The present invention utilizes a back pressure machine for heating and energy storage, thereby realizing a cascade utilization of energy and making energy utilization more efficient; (3) The present invention controls the transport speed and transport quantity of the gravity energy storage unit through a speed change device for frequency modulation, which is convenient, fast and responsive; (4) The present invention designs three energy storage lines, which can be flexibly switched according to the operating requirements of the unit, and is suitable for heating units for heating and industrial steam supply, and is also suitable for pure condensing units, with a wide range of applications; (5) The present invention can take into account deep peak regulation, peak load and frequency modulation, and realize the transfer of energy in time and space. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention; In the figure: 1. Boiler; 1a. Main steam pipeline; 1b. Reheat steam pipeline; 1c. Reheat steam extraction pipeline; 2. Steam turbine high-pressure cylinder; 3. Steam turbine medium-pressure cylinder; 4. Steam turbine low-pressure cylinder; 5. Large generator; 6. Condenser; 7. Condensate pump; 8. Low-pressure heater; 9. Deaerator; 10. Feedwater pump; 11. High-pressure heater; 12. Back pressure machine; 12a. Heating pipeline; 12b. Industrial steam supply pipeline; 12c. Return pipeline; 13. Speed ​​change device; 14. Gravity energy storage device; 14a. Gravity energy storage unit; 14b. Lifting equipment; 15. Small generator; 16. Heat exchange station; 17. Control valve one; 18. Control valve two. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings: Example: Figure 1 As shown, a flexible peak-shaving and frequency-regulating system using steam-driven gravity energy storage comprises a generator set, a back pressure machine heating system and a gravity energy storage system; The generator set includes a boiler 1, the main steam pipe 1a of the boiler is connected to the high-pressure cylinder 2 of the steam turbine, the outlet of the high-pressure cylinder of the steam turbine is connected back to the boiler through a pipeline, and is connected to the medium-pressure cylinder 3 of the steam turbine through the reheat steam pipe 1b of the boiler, and the outlet of the medium-pressure cylinder of the steam turbine is connected to the low-pressure cylinder 4 of the steam turbine; The back pressure machine heating system includes a back pressure machine 12, which is connected to the reheat steam pipeline through the reheat steam extraction pipeline 1c. The back pressure machine is connected to the gravity energy storage system through the speed change device 13, and the speed change device transfers the kinetic energy of the back pressure machine to the gravity energy storage system.

[0019] The gravity energy storage system includes a gravity energy storage device 14, which includes a gravity energy storage unit 14a and a lifting device 14b. The speed change device is connected to the lifting device and drives the lifting device to work. The lifting device transports the gravity energy storage unit to a high place to complete energy storage and realize peak load and frequency regulation of the unit.

[0020] The steam turbine high pressure cylinder, the steam turbine intermediate pressure cylinder and the steam turbine low pressure cylinder are connected to a large generator 5 .

[0021] The back pressure machine outlet is connected to the heat exchange station 16 through the heating pipe 12a.

[0022] The outlet of the back pressure machine is connected to the regulating valve 17 through the industrial steam supply pipeline 12b, and the steam pressure and temperature are adjusted by the regulating valve 1 before being directly supplied to industrial steam users.

[0023] The back pressure machine outlet is connected to the low pressure cylinder of the steam turbine through the return pipe 12c.

[0024] The exhaust port of the low-pressure cylinder of the steam turbine is connected to the condenser 6, the condenser is connected to the low-pressure heater 8 through the condensate pump 7, the low-pressure heater is connected to the deaerator 9, the deaerator is connected to the high-pressure heater 11 through the feed water pump 10, the high-pressure heater is connected back to the boiler through a pipeline, and the steam extraction port of the intermediate-pressure cylinder of the steam turbine is connected to the deaerator.

[0025] A regulating valve 18 is installed on the return pipeline.

[0026] The gravity energy storage system is connected to a small generator 15 .

[0027] A flexible peak-shaving and frequency-regulating method using steam-driven gravity energy storage, the method steps are as follows: when a generator set receives a deep peak-shaving instruction from a power grid, reheat steam is extracted through a reheat steam extraction pipeline or the reheat steam extraction amount is increased, at which time the steam flow entering the intermediate pressure cylinder and the low pressure cylinder of the steam turbine is reduced, the work capacity of the steam is reduced, the power generation of the large generator is reduced, and the load of the generator set is reduced; The reheated steam enters the back compressor to expand and do work. The back compressor rotates, and the speed change device transfers the kinetic energy of the back compressor to the gravity energy storage system. The lifting equipment moves the gravity energy storage unit to a high place to complete the energy storage. The exhaust steam at the outlet of the back pressure machine is utilized through lines Ⅰ, Ⅱ, and Ⅲ to meet the needs of different users; when the exhaust steam is utilized according to line Ⅰ, the exhaust steam enters the heat exchange station through the heating pipeline, completes the transfer of heat to the heating water, and realizes heating for users; when the exhaust steam is utilized according to line Ⅱ, the exhaust steam passes through the heating pipeline, and after the steam pressure and temperature are adjusted by the regulating valve 1, it is directly supplied to industrial steam users; when the exhaust steam is utilized according to line Ⅲ, the exhaust steam passes through the return pipeline, and after the steam pressure and temperature are adjusted by the regulating valve 2, it returns to the low-pressure cylinder of the steam turbine to continue to expand and do work; When the generator set receives the peak power command from the power grid, the lifting equipment moves the gravity energy storage unit to a lower place, and at the same time drives the small generator to rotate and generate electricity. The gravity energy storage device completes the energy release and achieves the peak power. When the generator set receives a frequency regulation instruction from the power grid, the frequency regulation of the set can be achieved by controlling the extraction amount of reheat steam and the number of gravity energy storage units transported. At the same time, the frequency regulation of the set can also be achieved by controlling the speed of the lifting equipment transporting the gravity energy storage units through the speed change device.

[0028] The working principle of the flexible peak-shaving and frequency-regulating system using steam-driven gravity energy storage is as follows: the main steam generated by boiler 1 enters the high-pressure cylinder 2 of the steam turbine through the main steam pipe 1a, the main steam exhaust steam at the outlet of the high-pressure cylinder 2 of the steam turbine returns to boiler 1 to be heated again to generate reheated steam, the reheated steam enters the medium-pressure cylinder 3 of the steam turbine through the reheat steam pipe 1b, the reheated steam exhaust steam enters the low-pressure cylinder 4 of the steam turbine, the exhaust steam of the low-pressure cylinder 4 of the steam turbine enters the condenser 6 to condense into condensate, the condensate is transported to the low-pressure heater 8 for heating through the condensate pump 7, and then to the deaerator 9 for deoxygenation, the deoxygenated water at the outlet of the deaerator 9 is transported to the high-pressure heater 11 for heating through the feed water pump 10, and the feed water finally returns to boiler 1, and the feed water is heated in boiler 1 to generate main steam and enter the next steam-water cycle. The steam turbine high-pressure cylinder 2, the steam turbine medium-pressure cylinder 3, and the steam turbine low-pressure cylinder 4 are connected to a large generator 5. The main steam and the reheated steam expand in the high-pressure, medium-pressure, and low-pressure cylinders of the steam turbine to drive the large generator 5 to rotate and generate electrical energy, thereby realizing power generation of the unit.

[0029] The unit heat supply peak regulation, gravity energy storage system energy storage: When receiving the deep peak load regulation instruction from the power grid dispatch, part of the reheated steam is extracted through the reheated steam extraction pipeline 1c and enters the back pressure machine 12. The steam expands and works in the back pressure machine 12, and the exhaust pressure and temperature of the back pressure machine decrease. When the exhaust steam is used according to the first utilization line, the exhaust steam enters the heat exchange station 16 through the heating pipeline 12a, heats the heating water, and supplies it to the heating users. When the exhaust steam is used according to the second utilization line, the exhaust steam is transported through the industrial steam supply pipeline 12b, and after the pressure and temperature are adjusted by the regulating valve 17, it is directly supplied to the industrial steam users. The exhaust steam is used according to the first and second utilization lines to meet different heating needs.

[0030] After extracting part of the reheated steam, the amount of steam entering the turbine intermediate pressure cylinder 3 and the turbine low pressure cylinder 4 is reduced, the working capacity of the unit itself decreases, the power generation is reduced, and deep peak regulation is completed.

[0031] The reheated steam expands and performs work in the back pressure machine 12, and the back pressure machine 12 drives the speed change device 13 to rotate. The speed change device 13 drives the lifting equipment 14b to move the gravity energy storage unit 14a to a high place, completing the energy storage process.

[0032] The unit is not used for peak load regulation, and the gravity energy storage system stores energy: When receiving the deep peak load regulation instruction from the power grid dispatch, part of the reheated steam is extracted through the reheated steam extraction pipeline 1c and enters the back pressure machine 12, where the steam expands and performs work, and the exhaust pressure and temperature of the back pressure machine decrease. When the exhaust steam is used according to the third utilization line, the exhaust steam returns to the low-pressure cylinder 4 of the steam turbine to perform work and generate electricity after adjusting the steam pressure and temperature through the return pipeline 12c and the regulating valve 2 18.

[0033] After extracting part of the reheated steam, the amount of steam entering the intermediate pressure cylinder 3 of the steam turbine is reduced, the working capacity of the unit itself is reduced, the power generation is reduced, and deep peak regulation is completed.

[0034] The reheated steam expands and performs work in the back pressure machine 12, and the back pressure machine 12 drives the speed change device 13 to rotate. The speed change device 13 drives the lifting equipment 14b to move the gravity energy storage unit 14a to a high place, completing the energy storage process.

[0035] At the peak of the unit, the gravity energy storage system releases energy: When receiving the peak command from the grid dispatch, the lifting equipment 14b moves the gravity energy storage unit 14a to a lower place, and at the same time drives the small generator 15 to rotate and generate electricity. The gravity energy storage device 14 completes energy release and achieves the peak.

[0036] Unit frequency regulation: When the generator set receives the grid frequency regulation instruction, it adjusts the reheat steam extraction amount along the reheat steam extraction pipe 1c, reduces or increases the amount of steam entering the turbine intermediate pressure cylinder 3 and the turbine low pressure cylinder 4, and completes the unit frequency regulation.

[0037] Gravity energy storage system frequency modulation: When the generator set receives the grid frequency modulation instruction, the speed change device 13 controls the number or speed of the lifting equipment 14b to move the gravity energy storage unit 14a, thereby controlling the power generation of the small generator 15 and completing the frequency modulation of the gravity energy storage system.

[0038] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A flexible peak-shaving and frequency-regulating system using steam-driven gravity energy storage, characterized in that: It includes a generator set, a back pressure machine heating system and a gravity energy storage system; The generator set comprises a boiler, the main steam pipe of the boiler is connected to the high-pressure cylinder of the steam turbine, the outlet of the high-pressure cylinder of the steam turbine is connected back to the boiler through a pipeline, and is connected to the medium-pressure cylinder of the steam turbine through the reheat steam pipe of the boiler, and the outlet of the medium-pressure cylinder of the steam turbine is connected to the low-pressure cylinder of the steam turbine; The back pressure machine heating system includes a back pressure machine, which is connected to the reheat steam pipeline through a reheat steam extraction pipeline. The back pressure machine is connected to the gravity energy storage system through a speed change device, and the speed change device transfers the kinetic energy of the back pressure machine to the gravity energy storage system.

2. According to claim 1, a flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage is characterized in that: The gravity energy storage system includes a gravity energy storage device, which includes a gravity energy storage unit and a lifting device. The speed change device is connected to the lifting device and drives the lifting device to work. The lifting device transports the gravity energy storage unit to a high place to complete energy storage and realize peak load and frequency regulation of the unit.

3. According to claim 1, a flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage is characterized in that: The steam turbine high-pressure cylinder, the steam turbine intermediate-pressure cylinder and the steam turbine low-pressure cylinder are connected to a large generator.

4. The flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage according to claim 1 is characterized in that: The back pressure machine outlet is connected to the heat exchange station through a heating pipeline.

5. The flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage according to claim 1 is characterized in that: The outlet of the back pressure machine is connected to the regulating valve 1 through the industrial steam supply pipeline, and the steam pressure and temperature are adjusted by the regulating valve 1 and then directly supplied to the industrial steam users.

6. The flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage according to claim 1 is characterized in that: The back pressure machine outlet is connected back to the low pressure cylinder of the steam turbine through a return pipeline.

7. The flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage according to claim 1 is characterized in that: The exhaust port of the low-pressure cylinder of the steam turbine is connected to the condenser, the condenser is connected to the low-pressure heater through a condensate pump, the low-pressure heater is connected to the deaerator, the deaerator is connected to the high-pressure heater through a feedwater pump, the high-pressure heater is connected back to the boiler through a pipeline, and the steam extraction port of the intermediate-pressure cylinder of the steam turbine is connected to the deaerator.

8. The flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage according to claim 1 is characterized in that: A second regulating valve is installed on the return pipeline.

9. The flexible peak-shaving and frequency-modulating system using steam-driven gravity energy storage according to claim 1 is characterized in that: The gravity energy storage system is connected to a small generator.

10. A method for flexible peak-shaving and frequency-modulation using steam-driven gravity energy storage, using the flexible peak-shaving and frequency-modulation system for steam-driven gravity energy storage as claimed in any one of claims 1 to 9, characterized in that: The method comprises the following steps: when the generator set receives a deep peak load regulation instruction from the power grid, reheat steam is extracted through the reheat steam extraction pipeline or the reheat steam extraction amount is increased. At this time, the steam flow entering the intermediate pressure cylinder and the low pressure cylinder of the steam turbine is reduced, the steam work capacity is reduced, the power generation of the large generator is reduced, and the load of the generator set is reduced; The reheated steam enters the back compressor to expand and do work. The back compressor rotates, and the speed change device transfers the kinetic energy of the back compressor to the gravity energy storage system. The lifting equipment moves the gravity energy storage unit to a high place to complete the energy storage. The exhaust steam at the outlet of the back pressure machine is utilized through lines Ⅰ, Ⅱ, and Ⅲ to meet the needs of different users; when the exhaust steam is utilized according to line Ⅰ, the exhaust steam enters the heat exchange station through the heating pipeline, completes the transfer of heat to the heating water, and realizes heating for users; when the exhaust steam is utilized according to line Ⅱ, the exhaust steam passes through the heating pipeline, and after the steam pressure and temperature are adjusted by the regulating valve 1, it is directly supplied to industrial steam users; when the exhaust steam is utilized according to line Ⅲ, the exhaust steam passes through the return pipeline, and after the steam pressure and temperature are adjusted by the regulating valve 2, it returns to the low-pressure cylinder of the steam turbine to continue to expand and do work; When the generator set receives the peak power command from the power grid, the lifting equipment moves the gravity energy storage unit to a lower place, and at the same time drives the small generator to rotate and generate electricity. The gravity energy storage device completes the energy release and achieves the peak power. When the generator set receives a frequency regulation instruction from the power grid, the frequency regulation of the set can be achieved by controlling the extraction amount of reheat steam and the number of gravity energy storage units transported. At the same time, the frequency regulation of the set can also be achieved by controlling the speed of the lifting equipment transporting the gravity energy storage units through the speed change device.

Images