Energy storage peak shaving system and method coupling waste heat recovery with water body thermal storage

Abstract

The embodiment of the present disclosure provides a kind of energy storage peak shaving system and method for coupling waste heat recovery and water body heat storage, system includes: thermal power generation system, circulating water waste heat utilization subsystem, water body heat storage subsystem and heating subsystem;Through recycling circulating water waste heat, can improve unit thermal efficiency under the same cogeneration capacity, reduce coal consumption rate, help to realize energy-saving and carbon reduction reconstruction.Coupling water body heat storage technology, system can participate in peak shaving and peak service all year round, help to realize flexibility reconstruction;Steam extraction heating, circulating water waste heat recovery heating and diversified heating form of heat storage water heating, help to realize heating reconstruction.Through the deep coupling of circulating water waste heat utilization technology, water body heat storage technology and existing cogeneration unit, energy-saving and carbon reduction reconstruction, flexibility reconstruction and heating reconstruction of cogeneration unit can be realized simultaneously.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure belong to the technical field of thermal storage peak shaving, and particularly relate to a storage energy peak shaving system and method coupling waste heat recovery and water body thermal storage. BACKGROUND

[0002] In a new power system, the contradiction between electricity and heat faced by the traditional combined heat and power (CHP) unit in the operation mode of "heat determines electricity" is increasingly prominent. If the CHP unit generates maximum heat, the power output cannot be adjusted. If the power output is reduced to meet the demand for power peak shaving, the heat supply capacity will decrease. This operation mode in which heat and power output are coupled and restricted to each other makes it difficult for the CHP unit to fully adapt to the new power system, and the CHP unit faces the dilemma that the peak shaving benefit and the heat supply guarantee cannot be achieved at the same time. This is the significance of the state's vigorous promotion of "three changes linkage". Energy saving and carbon reduction, flexibility and heat supply cannot be compromised. In order to achieve the overall consideration of the three, it is urgent to develop a new transformation technology suitable for thermal power units.

[0003] At present, there are mainly two directions for thermal power units to carry out various technical transformations: the boiler and turbine body side and the external thermal storage technology. The transformation technologies on the boiler and turbine body side mainly include low-load stable combustion technology, high-back pressure operation technology, zero output of low-pressure cylinder technology, etc. The minimum output load of most units is reduced to 30-40% of the rated load, but it has gradually been unable to meet the demand of the power grid for peak shaving and frequency modulation power supply, and although it can alleviate the contradiction between adjustment flexibility and heat supply to a certain extent, it brings the problem of increased coal consumption rate, which cannot meet the demand of energy saving and carbon reduction at the same time. The external thermal storage technology mainly includes electrode boiler + thermal storage water tank, molten salt thermal storage and solid thermal storage technologies, which store electricity or steam in the form of heat during the peak shaving period to achieve the effect of peak clipping and valley filling. However, the electrode boiler converts high-grade electricity into low-grade heat, and the heat energy quality is greatly lost. The molten salt or solid thermal storage technology also converts high-grade electricity or higher-grade steam into heat, and the thermal storage interval is usually between 200-500°C, which does not match the temperature required for heat supply, and it is usually combined with industrial steam supply demand. These technologies are still in the promotion stage. The heat pump technology based on circulating water waste heat recovery can recover part of the low-grade waste heat of circulating water for heat supply and reduce the steam extraction for heat supply, which can achieve the effect of energy saving and carbon reduction. However, the current heat pump equipment can only be used in the heating season, and the annual use time is limited, and it has not been combined with the peak shaving and frequency modulation technology of thermal power units.

[0004] In summary, the above-mentioned technologies can only realize one or two of energy saving and carbon reduction transformation, flexibility transformation and heat supply transformation of thermal power units, and it is difficult to consider all three at the same time. Therefore, how to realize the "three changes linkage" of energy saving and carbon reduction, flexibility and heat supply for CHP units is a technical problem that needs to be solved. SUMMARY

[0005] The present disclosure aims to at least solve one of the technical problems existing in the prior art, and provides an energy storage peak shaving system and method coupling waste heat recovery and water body heat storage. In the non-heating season, heat storage peak shaving can be performed by recovering the waste heat of circulating water, and peak shaving can be performed by releasing heat by heating feed water. In the heating season, heat storage peak shaving can also be performed by recovering the waste heat of circulating water, and peak shaving can be performed by releasing heat by heating heat network return water. The energy storage peak shaving system and operation method provided by the present application can recover the waste heat of circulating water during peak shaving of a combined heat and power unit throughout the year, and can also improve the peak shaving depth, so that the heat storage amount can help the unit to peak, and the heat and power contradiction of the unit can be relieved.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] An energy storage peak shaving system coupling waste heat recovery and water body heat storage, comprising: a thermal power generation system, a circulating water waste heat utilization subsystem, a water body heat storage subsystem, and a heating subsystem.

[0008] The evaporator inlet of the circulating water waste heat utilization subsystem is in communication with the circulating water cooling outlet in the condenser of the thermal power generation system, and the circulating water is cooled again by the condenser through the pipeline after releasing waste heat in the evaporator, to complete the circulation.

[0009] The water body heat exchanger of the water body heat storage subsystem is in communication with the downstream pipeline of the condensate pump outlet of the thermal power generation system, and part of the condensate flows into the water body heater to complete heating, and then flows into the low-pressure heater inlet side downstream of the condensate pump of the thermal power generation system through the pipeline.

[0010] The lower temperature water in the lower layer of the heat storage water body in the water body heat storage subsystem flows into the absorber and the condenser of the circulating water waste heat utilization subsystem through the pipeline in sequence for heat exchange, and the high-temperature water formed by the heat exchange returns to the upper layer of the heat storage water body through the pipeline.

[0011] The heat network heater in the heating subsystem is in communication with the intermediate-pressure cylinder of the thermal power generation system, and the condensate formed after the extraction steam of the intermediate-pressure cylinder flows into the heat network heater to release heat, and then returns to the low-pressure heater inlet side through the pipeline.

[0012] The return water on the heat network return water side of the heating subsystem flows into the water body heat exchanger through the pipeline, and the return water after absorbing the heat storage amount of the heat storage water body in the water body heat exchanger flows into the heat network heater through the pipeline, and then flows into the heat network feed water side.

[0013] The return water on the heat network return water side of the heating subsystem flows into the absorber and the condenser of the circulating water waste heat utilization subsystem through the pipeline in sequence to absorb low-temperature heat, and the high-temperature water formed by the heat exchange flows into the heat network heater through the pipeline, and then flows into the heat network feed water side.

[0014] Optionally, the thermal power generating system comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feed water pump, a high-pressure heater, a circulating water pump and a cooling tower.

[0015] The boiler is in communication with the high-pressure cylinder; the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are in communication in sequence; the output end of the low-pressure cylinder is connected with the generator and the condenser respectively; the condenser, the condensate pump, the low-pressure heater, the deaerator, the feed water pump and the high-pressure heater are in communication in sequence; the output end of the high-pressure heater is in communication with the input end of the boiler; and the circulating water pump is used to communicate the condenser and the cooling tower.

[0016] Optionally, the circulating water waste heat utilization subsystem comprises a generator, a condenser, an absorber, an evaporator, a solution heat exchanger, a solution pump, a refrigerant pump and an expansion valve.

[0017] The evaporator, the absorber, the generator and the condenser are in communication in sequence; the solution heat exchanger is arranged between the absorber and the generator; the solution pump is arranged between the absorber and the solution heat exchanger; the refrigerant pump is arranged between external pipelines of the evaporator; and the expansion valve is arranged between pipelines between the evaporator and the condenser.

[0018] Optionally, the water body heat storage subsystem comprises a heat storage water body, a water body heat exchanger, a hot water user and a water supplement device.

[0019] The heat storage water body is connected with the water body heat exchanger, the hot water user and the water supplement device respectively.

[0020] Optionally, the heating subsystem comprises a heat network return water side, a heat network feed water side and a heat network heater; the heat network return water side, the heat network heater and the heat network feed water side are in communication in sequence.

[0021] Further, it further comprises:

[0022] The tenth valve and the twelfth valve are arranged on the pipeline between the condenser in the thermal power generating system and the evaporator in the circulating water waste heat utilization subsystem.

[0023] Part of the circulating water flowing through the condenser in the thermal power generating system flows into the evaporator through the pipeline and the tenth valve under the driving of the circulating water pump; and the circulating water after releasing waste heat reenters the condenser through the pipeline and the twelfth valve, to complete the circulation.

[0024] Optionally, the medium-pressure cylinder extraction steam enters the generator through the pipeline and the twenty-fourth valve, and the condensed water formed after releasing heat returns to the low-pressure heater inlet side through the pipeline and the twenty-fifth valve.

[0025] Optionally, the condensate from the outlet side of the condensate pump flows into the water heat exchanger via pipeline, valve No. 1, and valve No. 3; and the heated condensate flows into the inlet side of the low-pressure heater via pipeline, valve No. 4, and valve No. 2.

[0026] This invention provides a method for energy storage and peak shaving that couples waste heat recovery and water body heat storage. The method is implemented according to the system described above. S1, during the non-heating season, when the system needs to participate in peak shaving:

[0027] Steam is drawn from the intermediate-pressure cylinder of the thermal power generation system and enters the generator of the circulating water waste heat utilization subsystem via pipeline and valve No. 24. Low-temperature water from the lower layer of the water storage body in the water storage subsystem is then fed into the absorber and condenser of the circulating water waste heat utilization subsystem via pipeline and valves No. 21 and No. 23 for heating. The resulting high-temperature water is returned to the water storage body via pipeline and valves No. 16 and No. 15 for heat storage. A portion of the circulating water flowing through the condenser in the thermal power generation system is fed into the evaporator of the circulating water waste heat utilization subsystem via pipeline and valve No. 10, releasing heat and then returning to the condenser via pipeline and valve No. 12 for heat absorption.

[0028] S2, During the non-heating season, when the system needs peak operation:

[0029] The condensate from the thermal power generation system is heated by entering the water heat exchanger in the water storage subsystem via pipelines, valve 1, and valve 3. The heated condensate is then returned to the inlet side of the low-pressure heater via pipelines, valve 4, and valve 2. The high-temperature water from the upper layer of the stored hot water is released by entering the water heat exchanger via pipelines and valve 13. The released water is then returned to the lower low-temperature side of the stored hot water via pipelines and valve 20.

[0030] S3, during the heating season when the system needs peak shaving:

[0031] The process is the same as the peak-shaving procedure of the non-heating season system described in S1, except that the exhaust steam from the medium-pressure cylinder of the thermal power generation system enters the heating heater of the heating subsystem through the pipeline and valve No. 7, and the drain water after heat release enters the inlet side of the low-pressure heater through the pipeline, valve No. 6 and valve No. 2; the return water from the return water side of the heating network is heated by the heating network heater and then enters the feed water side of the heating network.

[0032] S4, During the heating season, when the system needs peak operation:

[0033] The high-temperature water from the upper layer of the hot water storage body in the circulating water waste heat utilization subsystem enters the water heat exchanger through pipelines and valve No. 13 to release heat, and then returns to the lower layer of the hot water storage body through pipelines and valve No. 20. Part of the return water from the heating network return water side of the heating subsystem enters the water heat exchanger through pipelines, valves No. 8 and No. 9 for heating, and then enters the heating network heater for secondary heating through pipelines and valve No. 5, and then enters the heating network supply water side. Part of the return water from the heating network return water side enters the absorber and condenser of the circulating water waste heat utilization subsystem through pipelines, valves No. 19 and No. 23 for heat absorption, and then enters the heating network heater for secondary heating through valve No. 17. The evaporator is the same as during peak shaving, recovering part of the heat in the circulating water.

[0034] The beneficial effects of the present invention include:

[0035] The novel energy storage and peak-shaving system proposed in this invention deeply couples circulating water waste heat utilization technology, water body thermal storage technology, and cogeneration units, simultaneously addressing energy-saving and carbon-reduction retrofits, flexibility upgrades, and heating system upgrades for cogeneration units. First, by recovering circulating water waste heat, the thermal efficiency of the unit can be improved and the coal consumption rate reduced under the same cogeneration capacity, contributing to energy-saving and carbon-reduction retrofits. Second, by coupling circulating water waste heat utilization technology with water body thermal storage technology, the system can participate in unit peak shaving and peak load operations year-round. The long-term and even cross-seasonal thermal storage advantages of large-volume water bodies can, to some extent, solve the source-load mismatch problem, contributing to flexibility upgrades. Third, this technology enables the synergy of water body heating, circulating water waste heat recovery heating, and heating from the original heating network heaters, reducing coal consumption while ensuring heating capacity and deeply participating in the peak-shaving market, thus contributing to heating system upgrades. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of an energy storage and peak-shaving system that couples waste heat recovery and water body heat storage according to an embodiment of the present disclosure.

[0037] Figure 2 This is a schematic diagram of the system operation structure in this embodiment when peak shaving is required during the off-peak electricity consumption period in the non-heating season;

[0038] Figure 3 This is a schematic diagram of the system operation structure in the peak electricity demand state during the non-heating season in this embodiment of the present disclosure;

[0039] Figure 4 This is a schematic diagram of the system operation structure in this embodiment when peak shaving is required during the off-peak electricity consumption period in the heating season;

[0040] Figure 5 This is a schematic diagram of the system operation structure in the peak electricity demand state during the heating season in this embodiment of the present disclosure.

[0041] In the diagram, 1. Boiler; 2. High-pressure cylinder; 3. Medium-pressure cylinder; 4. Low-pressure cylinder; 5. Generator; 6. Condenser; 7. Condensate pump; 8. Low-pressure heater; 9. Deaerator;

[0042] 10. Feed water pump; 11. High-pressure heater; 12. Circulating water pump; 13. Cooling tower; 14. Hot water storage body; 15. Water heat exchanger; 16. Generator; 17. Condenser; 18. Absorber; 19. Evaporator; 20. Solution heat exchanger; 21. Solution pump; 22. Refrigerant pump; 23. Expansion valve; 24. Heat network heater; 25. Hot water user; 26. Water supply device; 27. Heat network return water side; 28. Heat network feed water side; 29. ​​Valve No. 1; 30. Valve No. 2; 31. Valve No. 3; 32. Valve No. 4; 33. Valve No. 5; 34. Valve No. 6; 35. Valve No. 7; 36. Valve No. 8; 37. Valve No. 9; 38. Valve No. 10; 39. Valve No. 11; 40. Valve No. 12; 41. Valve No. 13;

[0043] 42. Valve No. 14; 43. Valve No. 15; 44. Valve No. 16; 45. Valve No. 17; 46. Valve No. 18; 47. Valve No. 19; 48. Valve No. 20;

[0044] 49. Valve No. 21; 50. Valve No. 22; 51. Valve No. 23; 52. Valve No. 24; 53. Valve No. 25. Detailed Implementation

[0045] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] The embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. The detailed descriptions and accompanying drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments. In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0047] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0048] like Figures 1-5 As shown, an energy storage and peak-shaving system that couples waste heat recovery and water body heat storage includes a thermal power generation system, a circulating water waste heat utilization subsystem, a water body heat storage subsystem, and a heating subsystem.

[0049] The inlet of the evaporator 19 of the circulating water waste heat utilization subsystem is connected to the circulating water cooling outlet of the condenser 6 in the thermal power generation system. After the circulating water releases waste heat in the evaporator 19, it cools the condenser 6 again through the pipeline to complete the circulation.

[0050] The water heat exchanger 15 of the water body heat storage subsystem is connected to the outlet side pipeline of the condensate pump 7 of the thermal power generation system. After some condensate flows into the water body heater to complete the heating, it flows into the inlet side of the low-pressure heater 8 downstream of the condensate pump 7 of the thermal power generation system through the pipeline.

[0051] In the water heat storage subsystem, the low-temperature water in the lower layer of the hot water body 14 flows into the absorber 18 and condenser 17 of the circulating water waste heat utilization subsystem through pipelines for heat exchange, and the high-temperature water formed by heat exchange returns to the upper high-temperature layer of the hot water body 14 through pipelines.

[0052] The heating network heater 24 in the heating subsystem is connected to the medium-pressure cylinder 3 of the thermal power generation system. After the steam is drawn from the medium-pressure cylinder 3 into the heating network heater 24 and released heat, the condensate formed returns to the inlet side of the low-pressure heater 8 through the pipeline.

[0053] The return water from the return water side 27 of the heating subsystem enters the water heat exchanger 15 through the pipeline; after absorbing the heat stored in the hot water body 14 by the water heat exchanger 15, the return water enters the heating network heater 24 through the pipeline and then flows into the heating network supply water side 28.

[0054] The return water from the heat network return water side 27 of the heating subsystem enters the absorber 18 and condenser 17 of the circulating water waste heat utilization subsystem in sequence through the pipeline to absorb low-temperature heat, and the high-temperature water formed by heat exchange flows into the heat network heater 24 through the pipeline and then into the heat network supply water side 28.

[0055] The beneficial effects of this disclosure include: 1. This disclosure couples circulating water waste heat recovery technology with water body heat storage technology, which can simultaneously achieve energy saving and carbon reduction, flexibility, and heating system renovation. 2. The heat source of this patent consists of two parts: one part is heating steam extraction, and the other part is the recovered waste heat from the circulating water. Compared with traditional electric heat storage or high-temperature heat storage, it has the advantage of reducing the unit's coal consumption rate. 3. This patent utilizes a large-capacity hot water storage body 14 (hot water storage tank) for long-term heat storage of low-grade heat, which is more thermally economical. Moreover, the larger the water volume, the greater the heat storage capacity, the higher the heat storage efficiency, the longer the heat storage time, and the lower the construction cost.

[0056] In some embodiments, the thermal power generation system includes a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a condenser 6, a condensate pump 7, a low-pressure heater 8, a deaerator 9, a feedwater pump 10, a high-pressure heater 11, a circulating water pump 12, and a cooling tower 13.

[0057] Boiler 1 is connected to high-pressure cylinder 2. High-pressure cylinder 2, intermediate-pressure cylinder 3, and low-pressure cylinder 4 are connected in sequence. The output end of low-pressure cylinder 4 is connected to generator 5 and condenser 6. Condenser 6, condensate pump 7, low-pressure heater 8, deaerator 9, feedwater pump 10, and high-pressure heater 11 are connected in sequence. The output end of high-pressure heater 11 is connected to the input end of boiler 1. Cooling tower 13 is installed in the pipeline between condenser 6 and circulating water pump 12.

[0058] In some embodiments, the circulating water waste heat recovery subsystem includes a generator 16, a condenser 17, an absorber 18, an evaporator 19, a solution heat exchanger 20, a solution pump 21, a refrigerant pump 22, and an expansion valve 23.

[0059] Evaporator 19, absorber 18, solution heat exchanger 20, generator 16, and condenser 17 are connected in sequence. Solution pump 21 is installed in the pipeline between absorber 18 and solution heat exchanger 20. Refrigerant pump 22 is installed in evaporator 19, and expansion valve 23 is installed in the pipeline between evaporator 19 and condenser 17.

[0060] In some embodiments, the water heat storage subsystem includes a water storage body 14, a water heat exchanger 15, a hot water user 25, and a water supply device 26. The water storage body 14 is connected to the water heat exchanger 15, the hot water user 25, and the water supply device 26, respectively.

[0061] In some embodiments, the heating subsystem includes a heat network return water side 27, a heat network supply water side 28, and a heat network heater 24. The heat network return water side 27 is connected to the inlet pipe of the absorber 18 in the circulating water waste heat utilization subsystem and the inlet pipe of the water heat exchanger 15 in the water heat storage subsystem, and is also connected to the heat network heater 24 and the heat network supply water side 28.

[0062] In some embodiments, the energy storage and peak-shaving system further includes a No. 10 valve 38 and a No. 12 valve 40 installed on the pipeline between the condenser 6 and the evaporator 19. Part of the circulating water from the thermal power generation system flowing through the condenser 6 is driven by the circulating water pump 12 and flows into the evaporator 19 via the pipeline and the No. 10 valve 38. The circulating water, after releasing waste heat, re-enters the condenser 6 via the pipeline and the No. 12 valve 40, completing the circulation.

[0063] In some embodiments, the intermediate pressure cylinder 3 is connected to the input end of the generator 16 via a pipeline, and the output end of the generator 16 is connected to the inlet side of the low pressure heater 8 via a pipeline.

[0064] The unit also includes: valve 52 of number 24 installed on the pipeline between the intermediate pressure cylinder 3 and the input end of the generator 16, and valve 53 of number 25 installed on the pipeline between the output end of the generator 16 and the inlet end of the low pressure heater 8.

[0065] Steam extracted from the intermediate pressure cylinder 3 enters the generator 16 via pipeline and valve 52 (number 24), and the condensate formed after releasing heat returns to the inlet side of the low-pressure heater 8 via pipeline and valve 53 (number 25).

[0066] In some embodiments, the outlet of the condensate pump 7 is connected to the input end of the water heat exchanger 15 via a pipeline, and the output end of the water heat exchanger 15 is connected to the inlet side of the low-pressure heater 8 via a pipeline.

[0067] The unit also includes: valve 29 and valve 31 are installed sequentially on the pipeline between the condensate pump 7 and the water heat exchanger 15; valve 32 and valve 30 are installed sequentially on the pipeline between the water heat exchanger 15 and the low-pressure heater 8.

[0068] Condensate from the outlet of condensate pump 7 flows into water heat exchanger 15 via pipeline, valve 29 and valve 31, and the heated condensate flows into the inlet of low-pressure heater 8 via pipeline, valve 32 and valve 30.

[0069] The beneficial effects of this disclosure include: 1) This disclosure can simultaneously realize the energy-saving and carbon-reduction transformation, flexibility transformation and heating transformation of cogeneration units.

[0070] 2) It can realize the recovery of waste heat from circulating water, reduce the temperature of circulating water, and improve the vacuum degree of condenser 6.

[0071] 3) Heat storage is achieved by using steam extraction to drive a water source heat pump, which helps the unit to regulate peak loads.

[0072] 4) After coupling the water body heat storage subsystem, the heat pump unit in the circulating water waste heat utilization subsystem can be put into operation all year round, and the recoverable circulating water waste heat is greatly improved. At the same time, it participates in the peak shaving of the unit throughout the year.

[0073] A specific example provided in this disclosure is an energy storage and peak-shaving system that simultaneously achieves energy saving and carbon reduction, flexibility, and heating system transformation. The unit includes a thermal power generation system, a circulating water waste heat utilization subsystem, a water body heat storage subsystem, and a heating subsystem.

[0074] The thermal power generation system includes a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a condenser 6, a condensate pump 7, a low-pressure heater 8, a deaerator 9, a feed water pump 10, a high-pressure heater 11, a circulating water pump 12, and a cooling tower 13.

[0075] The circulating water waste heat utilization subsystem includes a generator 16, a condenser 17, an absorber 18, an evaporator 19, a solution heat exchanger 20, a solution pump 21, a refrigerant pump 22, and an expansion valve 23.

[0076] The water body heat storage subsystem mainly includes a water storage body 14, a water heat exchanger 15, a hot water user 25, and a water replenishment device 26.

[0077] The heating subsystem mainly includes the return water side 27 of the heating network, the supply water side 28 of the heating network, and the heating network heater 24.

[0078] The connection between the thermal power generation system and the circulating water waste heat utilization subsystem is as follows: A portion of the circulating water flowing through the condenser 6 is driven by the circulating water pump 12 and flows into the evaporator 19 via pipeline and valve 38 (number 10). After releasing waste heat, it re-enters the condenser 6 via pipeline and valve 40 (number 12), completing the cycle. Furthermore, steam extracted from the intermediate-pressure cylinder 3 enters the generator 16 via pipeline and valve 52 (number 24). After releasing heat, it returns to the inlet side of the low-pressure heater 8 via pipeline and valve 53 (number 25).

[0079] The connection between the thermal power generation system and the water heat storage subsystem is as follows: condensate from the outlet side of condensate pump 7 flows into water heat exchanger 15 via pipeline, valve 29 and valve 31, and after heating, it flows into the inlet side of low-pressure heater 8 via pipeline, valve 32 and valve 30.

[0080] The connection between the thermal power generation system and the heating subsystem is as follows: steam is extracted from the intermediate pressure cylinder 3 and flows into the heating network heater 24 through the pipeline and valve 35 to release heat. Then, it returns to the inlet side of the low pressure heater 8 through the pipeline, valve 34 and valve 30.

[0081] The connection between the circulating water waste heat utilization subsystem and the water body heat storage subsystem is as follows: the low-temperature water in the lower layer of the hot water storage body 14 flows into the absorber 18 to absorb low-temperature heat after passing through the pipeline, valve 49 (No. 21), and valve 51 (No. 23). Further, it flows into the condenser 17 to absorb high-temperature heat, and then returns to the high-temperature layer above the hot water storage body 14 through the pipeline, valve 44 (No. 16), and valve 43 (No. 15).

[0082] The connection between the water heat storage subsystem and the heating subsystem is as follows: the return water from the return water side 27 of the heating network enters the water heat exchanger 15 through the pipeline, valve No. 8 36 and valve No. 9 37, absorbs the heat stored in the water storage body 14, and then enters the heating network heater 24 through the pipeline and valve No. 5 33, and then flows into the heating network supply water side 28.

[0083] The connection between the circulating water waste heat utilization subsystem and the heating subsystem is as follows: the return water from the heat network return water side 27 enters the absorber 18 through pipelines, valve 47 (No. 19), and valve 51 (No. 23) to absorb low-temperature heat. Further, it flows into the condenser 17 to absorb high-temperature heat, then through pipelines and valve 45 (No. 17) into the heat network heater 24, and then into the heat network supply water side 28.

[0084] In some embodiments, the hot water storage body 14 is an artificially constructed or natural hot water storage tank with a volume ranging from tens of thousands to millions of cubic meters. Combined with insulation materials, seepage prevention materials, and water distributors, it can achieve long-term and even cross-seasonal heat storage. Furthermore, the hot water storage body 14 has a pipeline directly connected to the hot water user 25 and a valve 42 of number fourteen, as well as a corresponding pipeline connected to the water supply device 26 and a valve 50 of number twenty-two.

[0085] In some embodiments, the circulating water waste heat utilization subsystem employs water source absorption heat pump technology. A dilute solution composed of refrigerant and absorbent is driven by solution pump 21 through solution heat exchanger 20 and enters generator 16, where it absorbs heat from the extracted steam of the thermal power generation system. The refrigerant evaporates and enters condenser 17. The higher-temperature concentrated solution heats the dilute solution in solution heat exchanger 20 before flowing into absorber 18. The high-temperature, high-pressure refrigerant heats the heat network return water or water storage in condenser 17, then flows through expansion valve 23 to reduce pressure, and enters evaporator 19 to absorb waste heat from the circulating water of the thermal power generation system to complete the evaporation process. Finally, it enters absorber 18 to mix with the concentrated solution to form a dilute solution. The released absorbed heat is used for preliminary heating of heat network return water or water storage.

[0086] The novel energy storage and peak-shaving system proposed in this invention deeply couples circulating water waste heat utilization technology, water body thermal storage technology, and cogeneration units, enabling simultaneous solutions for energy-saving and carbon-reduction retrofits, flexibility upgrades, and heating system improvements for cogeneration units. First, by recovering circulating water waste heat, the thermal efficiency of the unit can be improved and coal consumption reduced under the same cogeneration capacity, contributing to energy-saving and carbon-reduction retrofits. Second, by coupling circulating water waste heat recovery technology and water body thermal storage technology, the system can participate in peak-shaving throughout the year. The long-term and even cross-seasonal thermal storage of large-volume water bodies can, to some extent, solve the source-load mismatch problem, contributing to flexibility upgrades. Third, this technology enables the coordinated use of water body heating, circulating water waste heat recovery heating, and the original heating network heaters (24 hours a day), reducing coal consumption and deeply participating in the peak-shaving market while ensuring heating capacity, thus contributing to heating system improvements.

[0087] A second aspect of the embodiments of this disclosure provides a method for energy storage and peak shaving that couples waste heat recovery and water body thermal storage. The method is implemented based on the above-mentioned unit and specifically includes:

[0088] During the non-heating season, when the energy storage peak-shaving system needs to participate in peak-shaving:

[0089] S101. Extract exhaust steam from the intermediate-pressure cylinder 3 in the thermal power generation system. The exhaust steam enters the generator 16 in the circulating water waste heat utilization subsystem via pipeline and valve 52 (number 24). This configuration reduces the amount of steam entering the low-pressure cylinder 4, thereby reducing the power generation load.

[0090] S102. The low-temperature water from the lower layer of the water storage body 14 in the water storage subsystem is sequentially heated by entering the absorber 18 and condenser 17 in the circulating water waste heat utilization subsystem through pipelines, valve 49 (number 21), and valve 51 (number 23).

[0091] S103. The high-temperature water formed after heating is returned to the hot water storage body 14 through the pipeline and valve 44 of No. 16 for heat storage.

[0092] In some embodiments, when the energy storage peak-shaving system needs to participate in peak conditions during the non-heating season:

[0093] S201. Condensate from the thermal power generation system is piped through valves 29 and 31 into the water heat exchanger 15 of the water storage subsystem for heating. The heated condensate is then piped through valves 32 and 30 back to the inlet side of the low-pressure heater 8. This arrangement reduces the amount of regenerative steam extraction from the low-pressure cylinder 4, thereby increasing the unit's power generation load.

[0094] S202. The high-temperature water from the upper layer of the hot water storage body 14 is introduced into the water heat exchanger 15 through the pipeline and valve No. 13 41 to release heat.

[0095] S203. The high-temperature water from the upper layer after heat release is returned to the lower layer of the hot water storage body 14 through the pipeline and valve No. 20 48.

[0096] In some embodiments, reference is made to Figure 4 During the heating season, when thermal power units need to operate in peak-shaving mode:

[0097] S301, the steam extracted from the medium-pressure cylinder 3 in the thermal power generation system enters the heating network heater 24 in the heating subsystem through pipelines and valve 35 No. 7 to meet the heat load requirements.

[0098] S302, a small portion of the extracted steam from the intermediate pressure cylinder 3 enters the circulating water waste heat utilization subsystem through pipelines and valve 52 (number 24) to recover the waste heat of the circulating water and generate heat that is stored in the hot water storage body 14.

[0099] Specifically, the extracted steam in the intermediate-pressure cylinder 3 exchanges heat with the generator 16, and the resulting condensate flows through valves 25, 6, and 2 back to the inlet side of the low-pressure heater 8. The waste heat of the circulating water is used in the condenser 17 of the subsystem to heat the lower layer of low-temperature water in the hot water storage body 14, and then returns to the upper layer of the hot water storage body 14 to achieve heat storage.

[0100] S303, the return water from the return water side 27 of the heating network enters the heating network heater 24 through the pipeline and valve 46 (number 18) for heating, and finally flows into the heating network feed water side 28. In this scheme, the unit can simultaneously achieve peak shaving by steam extraction, waste heat recovery from circulating water, and heat storage during the non-heating season.

[0101] In some embodiments, reference is made to Figure 5 During the heating season, when thermal power units need to operate at peak capacity:

[0102] S401, the return water from the heating network return water side 27 of the heating subsystem is distributed through valves 8 (36), 19 (47), and 18 (46). Valve 8 (36) controls the flow of the return water from the heating network into the water heat exchanger 15 of the water storage subsystem, absorbing the heat stored in the water. Valve 19 (47) controls the flow of the return water from the heating network into the circulating water waste heat utilization subsystem, recovering the waste heat of the circulating water for heating under the drive of steam extraction.

[0103] S402, The return water of the residual flow of the return water on the return water side 27 of the heating network is combined with the return water of the heating network after being heated by the circulating water waste heat recovery subsystem and the water body heat storage subsystem through the pipeline and valve No. 18 46. It enters the heating network heater 24 of the heating subsystem and is heated to the specified temperature, and finally enters the heating network supply water side 28.

[0104] In this disclosure, the heat stored in the water body and the waste heat of the circulating water are used to heat the return water of the heating network, which can reduce the extraction of steam for heating and improve the peak capacity of the unit at this time.

[0105] In this disclosure, the peak shaving and peak operation modes during the non-heating season and the heating season are as follows: when the peak shaving and heat storage power of the water body 14 in the water body heat storage subsystem is greater than the peak heat release power during the non-heating season, the heat can be stored for the heating season and used to heat the heat network return water in the heating subsystem during the heating season, thereby improving the peak capacity during the heating season.

[0106] Furthermore, the year-round auxiliary frequency regulation operation mode, by extracting the exhaust steam from the high-pressure cylinder 3 of the thermal power generation system into the circulating water waste heat utilization subsystem, can quickly reduce the output of the low-pressure cylinder 4 and the unit's power generation load, thus assisting in the frequency regulation of the cogeneration unit.

[0107] Furthermore, the heat stored during the non-heating season heats the condensate, reducing the extraction of steam from condensate pump 7 and low-pressure heater 8, thereby increasing the unit's power generation.

[0108] Furthermore, the water body disclosed herein can store heat for extended periods, spanning seasons, storing heat in summer and releasing it in winter, thus resolving the mismatch between peak shaving and heating time.

[0109] Furthermore, during the heating season, the hot water storage body 14 and the water source heat pump will be given priority for heating, reducing the extraction of steam for heating by the unit and helping the unit reach its peak.

[0110] In this disclosure, during the non-heating season, heat storage and peak shaving can be achieved by recovering waste heat from circulating water, and peak shaving can be achieved by heating feedwater to release heat. During the heating season, similarly, heat storage and peak shaving can be achieved by recovering waste heat from circulating water, and peak shaving can be achieved by heating the return water of the heating network to release heat. The energy storage and peak shaving system and operation method provided by this invention enable combined heat and power (CHP) units to recover waste heat from circulating water for heat storage throughout the year during peak shaving, and also to increase the depth of peak shaving. The stored heat can help the unit achieve peak shaving and alleviate the heat and power imbalance of the CHP unit.

[0111] Specifically, S1, during the non-heating season, when the system needs to participate in peak shaving:

[0112] Steam is drawn from the intermediate-pressure cylinder of the thermal power generation system and enters the generator of the circulating water waste heat utilization subsystem via pipeline and valve No. 24. The low-temperature water from the lower layer of the water storage body in the water storage subsystem enters the absorber and condenser of the circulating water waste heat utilization subsystem via pipeline and valves No. 21 and No. 23 for heating. The high-temperature water formed after heating returns to the water storage body via pipeline and valves No. 16 and No. 15 for heat storage. A portion of the circulating water flowing through the condenser in the thermal power generation system enters the evaporator of the circulating water waste heat utilization subsystem via pipeline and valve No. 10. After releasing heat, it returns to the condenser via pipeline and valve No. 12 for heat absorption.

[0113] S2, During the non-heating season, when the system needs peak operation:

[0114] The condensate from the thermal power generation system is heated by entering the water heat exchanger in the water storage subsystem via pipelines, valve 1, and valve 3. The heated condensate is then returned to the inlet side of the low-pressure heater via pipelines, valve 4, and valve 2. The high-temperature water from the upper layer of the stored water body is released by entering the water heat exchanger via pipelines and valve 13. The released water is then returned to the lower low-temperature side of the stored water body via pipelines and valve 20.

[0115] S3, during the heating season when the system needs peak shaving:

[0116] The process is the same as the peak-shaving procedure of the non-heating season system described in S1, except that the exhaust steam from the medium-pressure cylinder of the thermal power generation system enters the heating heater of the heating subsystem through the pipeline and valve No. 7, and the drain water after heat release enters the inlet side of the low-pressure heater through the pipeline, valve No. 6 and valve No. 2; the return water from the return water side of the heating network is heated by the heating network heater and then enters the feed water side of the heating network.

[0117] S4, During the heating season, when the system needs peak operation:

[0118] The high-temperature water from the upper layer of the hot water storage body in the circulating water waste heat utilization subsystem enters the water heat exchanger through pipelines and valve No. 13 to release heat, and then returns to the lower layer of the hot water storage body through pipelines and valve No. 20. Part of the return water from the heating network return water side of the heating subsystem enters the water heat exchanger through pipelines, valves No. 8 and No. 9 for heating, and then enters the heating network heater for secondary heating through pipelines and valve No. 5, and then enters the heating network supply water side. Part of the return water from the heating network return water side enters the absorber and condenser of the circulating water waste heat utilization subsystem through pipelines, valves No. 19 and No. 23 for heat absorption, and then enters the heating network heater for secondary heating through valve No. 17. The evaporator is the same as during peak shaving, recovering part of the heat in the circulating water.

[0119] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A peak-shaving energy storage system coupling waste heat recovery and water body heat storage, characterized in that, include: Thermal power generation subsystem, circulating water waste heat utilization subsystem, water body heat storage subsystem and heating subsystem; The thermal power generation system includes a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feed water pump, a high-pressure heater, a circulating water pump, and a cooling tower. The boiler is connected to the high-pressure cylinder; the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder are connected in sequence; the output end of the low-pressure cylinder is connected to the generator and the condenser respectively; the condenser, the condensate pump, the low-pressure heater, the deaerator, the feedwater pump, and the high-pressure heater are connected in sequence; the output end of the high-pressure heater is connected to the input end of the boiler; the circulating water pump is used to connect the condenser and the cooling tower; The circulating water waste heat utilization subsystem includes a generator, condenser, absorber, evaporator, solution heat exchanger, solution pump, refrigerant pump, and expansion valve; The evaporator, the absorber, the generator, and the condenser are connected in sequence; the solution heat exchanger is located between the absorber and the generator; the solution pump is located between the absorber and the solution heat exchanger; the refrigerant pump is located between the external pipelines of the evaporator; and the expansion valve is located in the pipeline between the evaporator and the condenser. The water body thermal storage subsystem includes a water storage body, a water body heat exchanger, hot water users, and a water supply device; The hot water storage body is connected to the water heat exchanger, the hot water user, and the water supply device, respectively. The heating subsystem includes a return water side of the heating network, a supply water side of the heating network, and a heating network heater; the return water side of the heating network, the heating network heater, and the supply water side of the heating network are connected in sequence; The evaporator inlet of the circulating water waste heat utilization subsystem is connected to the circulating water cooling outlet in the condenser of the thermal power generation system. After the circulating water releases waste heat in the evaporator, it cools the condenser again through the pipeline to complete the circulation. The water heat exchanger of the water body heat storage subsystem is connected to the condensate pump outlet side pipeline of the thermal power generation system. Part of the condensate flows into the water body heater to complete the heating and then flows into the low-pressure heater inlet side downstream of the condensate pump of the thermal power generation system through the pipeline. In the water body heat storage subsystem, the lower layer of low-temperature water in the hot water body flows into the absorber and condenser of the circulating water waste heat utilization subsystem through pipelines for heat exchange, and the high-temperature water formed by heat exchange returns to the upper high-temperature layer of the hot water body through pipelines. The heating network heater in the heating subsystem is connected to the medium-pressure cylinder of the thermal power generation system. After the steam is drawn from the medium-pressure cylinder into the heating network heater and releases heat, the condensate formed returns to the inlet side of the low-pressure heater through the pipeline. The return water from the return water side of the heating network of the heating subsystem enters the water heat exchanger through the pipeline; after absorbing the heat stored in the hot water body by the water heat exchanger, the return water enters the heating network heater through the pipeline and then flows into the heating network supply side. The return water from the heat network return water side of the heating subsystem enters the absorber and condenser of the circulating water waste heat utilization subsystem in sequence through pipelines to absorb low-temperature heat, and the high-temperature water formed by heat exchange flows into the heat network heater through pipelines and then into the heat network supply water side.

2. The energy storage and peak-shaving system coupling waste heat recovery and water body heat storage according to claim 1, characterized in that, Also includes: Valve No. 10 and valve No. 12 are installed on the pipeline between the condenser in the thermal power generation system and the evaporator in the circulating water waste heat utilization subsystem. In the thermal power generation system, some of the circulating water flowing through the condenser is driven by the circulating water pump and flows into the evaporator through the pipeline and the No. 10 valve; and the circulating water after releasing waste heat re-enters the condenser through the pipeline and the No. 12 valve to complete the circulation.

3. The energy storage and peak-shaving system coupling waste heat recovery and water body heat storage according to claim 1, characterized in that, Steam extracted from the intermediate-pressure cylinder enters the generator via pipeline and valve number 24, and the condensate formed after releasing heat returns to the inlet side of the low-pressure heater via pipeline and valve number 25.

4. The energy storage and peak-shaving system coupling waste heat recovery and water body heat storage according to claim 1, characterized in that, The condensate from the outlet of the condensate pump flows into the water heat exchanger via pipeline, valve 1, and valve 3; and the heated condensate flows into the inlet of the low-pressure heater via pipeline, valve 4, and valve 2.

5. A method for energy storage and peak shaving that couples waste heat recovery and water body thermal storage, wherein the method is implemented using the system according to any one of claims 1-4, characterized in that, S1. During the non-heating season, when the system needs to participate in peak shaving: Steam is drawn from the intermediate-pressure cylinder of the thermal power generation system and enters the generator of the circulating water waste heat utilization subsystem via pipeline and valve No.

24. Low-temperature water from the lower layer of the water storage body in the water storage subsystem is then fed into the absorber and condenser of the circulating water waste heat utilization subsystem via pipeline and valves No. 21 and No. 23 for heating. The resulting high-temperature water is returned to the water storage body via pipeline and valves No. 16 and No. 15 for heat storage. A portion of the circulating water flowing through the condenser in the thermal power generation system is fed into the evaporator of the circulating water waste heat utilization subsystem via pipeline and valve No. 10, releasing heat and then returning to the condenser via pipeline and valve No. 12 for heat absorption. S2, During the non-heating season, when the system needs peak operation: The condensate from the thermal power generation system is heated by entering the water heat exchanger in the water storage subsystem via pipelines, valve 1, and valve 3. The heated condensate is then returned to the inlet side of the low-pressure heater via pipelines, valve 4, and valve 2. The high-temperature water from the upper layer of the stored hot water is released by entering the water heat exchanger via pipelines and valve 13. The released water is then returned to the lower low-temperature side of the stored hot water via pipelines and valve 20. S3, during the heating season when the system needs peak shaving: The process is the same as the peak-shaving procedure of the non-heating season system described in S1, except that the exhaust steam from the medium-pressure cylinder of the thermal power generation system enters the heating heater of the heating subsystem through the pipeline and valve No. 7, and the drain water after heat release enters the inlet side of the low-pressure heater through the pipeline, valve No. 6 and valve No. 2; the return water from the return water side of the heating network is heated by the heating network heater and then enters the feed water side of the heating network. S4, During the heating season, when the system needs peak operation: In the circulating water waste heat utilization subsystem, the high-temperature water from the upper layer of the hot water storage body enters the water heat exchanger through pipelines and valve No. 13 to release heat, and then returns to the lower layer of the hot water storage body through pipelines and valve No.

20. Part of the return water from the heating network return water side of the heating subsystem enters the water heat exchanger through pipelines, valves No. 8 and No. 9 for heating, and then enters the heating network heater for secondary heating through pipelines and valve No. 5, before entering the heating network supply water side. Part of the return water from the heating network return water side enters the absorber and condenser of the circulating water waste heat utilization subsystem through pipelines, valves No. 19 and No. 23 for heat absorption, and then enters the heating network heater for secondary heating through valve No.

17. The evaporator is the same as during peak shaving, recovering part of the heat in the circulating water.

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