A thermal system suitable for low-load operation

Abstract

This disclosure proposes a thermal system suitable for low-load operation, comprising: a boiler; a high-pressure cylinder, the steam inlet of which is connected to the main steam outlet of the boiler, and the steam outlet of which is connected to the reheat steam inlet of the boiler; an intermediate-pressure cylinder, the steam inlet of which is connected to the reheat steam outlet of the boiler; a pressure-reducing device, the steam inlet of which is connected to the main steam outlet of the boiler; a first low-pressure cylinder, the steam inlet of which is connected to the steam outlet of the intermediate-pressure cylinder and the steam outlet of the pressure-reducing device; a switching device, the steam inlet of which is connected to the steam outlet of the intermediate-pressure cylinder and the steam outlet of the pressure-reducing device; and a second low-pressure cylinder, the steam inlet of which is connected to the steam outlet of the switching device. In this thermal system suitable for low-load operation, the losses in the last few stages of the thermal system are reduced, the overall energy consumption is lowered, and the thermal system can operate stably under low-load conditions, meeting the requirements for deep peak shaving.

Description

Technical Field

[0001] This disclosure relates to the field of thermal system technology, and more particularly to a thermal system suitable for low-load operation. Background Technology

[0002] The thermal power plant's thermal system is an integrated system consisting of boilers, steam turbines, and other thermal equipment connected in a specific sequence through steam and water pipelines. The thermal system typically includes subsystems such as intermediate steam reheat system, feedwater reheat system, external heating system, and bypass system. These subsystems have different functions and interact and coordinate with each other to ensure the safe, economical, and flexible operation of the thermal system.

[0003] With the application of clean energy power generation such as wind and solar power, the amount of clean energy generated is also increasing. Therefore, it is necessary to improve the deep peak-shaving capacity of the thermal system to match the high power generation of clean energy. However, during deep peak shaving of the thermal system, the steam flow of the low-pressure cylinder is small due to the low load, resulting in large losses in the last few stages of the thermal system and high overall energy consumption. This leads to insufficient deep peak shaving capacity of the thermal system, making it difficult to adapt to the large power generation of clean energy. Summary of the Invention

[0004] This disclosure aims to at least partially address one of the technical problems in the related art.

[0005] Therefore, the purpose of this disclosure is to provide a thermal system suitable for low-load operation.

[0006] To achieve the above objectives, this disclosure provides a thermal system suitable for low-load operation, comprising: a boiler; a high-pressure cylinder, the steam inlet of which is connected to the main steam outlet of the boiler, and the steam outlet of which is connected to the reheat steam inlet of the boiler; an intermediate-pressure cylinder, the steam inlet of which is connected to the reheat steam outlet of the boiler; a pressure-reducing device, the steam inlet of which is connected to the main steam outlet of the boiler; a first low-pressure cylinder, the steam inlet of which is connected to the steam outlet of the intermediate-pressure cylinder and the steam outlet of the pressure-reducing device; a switching device, the steam inlet of which is connected to the steam outlet of the intermediate-pressure cylinder and the steam outlet of the pressure-reducing device; a second low-pressure cylinder, the steam inlet of which is connected to the steam outlet of the switching device; and a generator, the power input of which is connected to the power output of the high-pressure cylinder, the intermediate-pressure cylinder, the first low-pressure cylinder, and the second low-pressure cylinder.

[0007] Optionally, the pressure reducing device includes: a pressure reducer, the steam inlet of which is connected to the main steam outlet of the boiler; and a first regulating valve, the steam inlet of which is connected to the steam outlet of the pressure reducer, and the steam outlet of which is connected to the steam inlet of the first low-pressure cylinder and the steam inlet of the switching device.

[0008] Optionally, the switching device includes: a second regulating valve, the steam inlet of which is connected to the steam outlet of the pressure reducing device, and the steam outlet of which is connected to the steam inlet of the second low-pressure cylinder; and a third regulating valve, the steam inlet of which is connected to the steam outlet of the pressure reducing device, and the steam outlet of which is connected to the steam inlet of the second low-pressure cylinder; wherein the second regulating valve and the third regulating valve are connected in parallel.

[0009] Optionally, the thermal system further includes: a condenser, wherein the steam inlet of the condenser's hot-side passage is connected to the steam outlet of the first low-pressure cylinder and the steam outlet of the second low-pressure cylinder, and cooling water is introduced into the cold-side passage of the condenser; and a low-pressure heating assembly, wherein the steam inlet of the low-pressure heating assembly's hot-side passage is connected to the steam outlet of the intermediate-pressure cylinder, the steam outlet of the first low-pressure cylinder, and the steam outlet of the second low-pressure cylinder, and the water outlet of the low-pressure heating assembly's hot-side passage is connected to the water inlet of the condenser's hot-side passage, and the water inlet of the low-pressure heating assembly's cold-side passage is connected to the water outlet of the condenser's hot-side passage. The system includes: a water inlet and a deaerator; a deaerator whose steam inlet is connected to the steam outlet of the intermediate-pressure cylinder, and whose water inlet is connected to the cold-side passage water outlet of the low-pressure heating assembly; and a high-pressure heating assembly whose hot-side passage steam inlet is connected to the steam outlet of the high-pressure cylinder and the intermediate-pressure cylinder, whose hot-side passage water outlet is connected to the water inlet of the deaerator, whose cold-side passage water inlet is connected to the water outlet of the deaerator, and whose cold-side passage water outlet is connected to the main steam inlet of the boiler.

[0010] Optionally, the low-pressure heating assembly includes: a first low-pressure heater, wherein the steam inlet of the hot side passage of the first low-pressure heater is connected to the steam outlet of the intermediate-pressure cylinder, and the water outlet of the cold side passage of the first low-pressure heater is connected to the water inlet of the deaerator; a second low-pressure heater, wherein the steam inlet of the hot side passage of the second low-pressure heater is connected to the steam outlet of the first low-pressure cylinder, the steam outlet of the second low-pressure cylinder, and the water outlet of the hot side passage of the first low-pressure heater, and the water outlet of the cold side passage of the second low-pressure heater is connected to the water inlet of the cold side passage of the first low-pressure heater; and a third low-pressure heater, wherein the steam inlet of the hot side passage of the third low-pressure heater is connected to the steam outlet of the first low-pressure cylinder, the steam outlet of the second low-pressure cylinder, and the water outlet of the hot side passage of the first low-pressure heater. The steam end of the third low-pressure heater is connected to the hot-side passage outlet of the second low-pressure heater, and the cold-side passage outlet of the third low-pressure heater is connected to the cold-side passage inlet of the second low-pressure heater; the steam inlet of the hot-side passage of the fourth low-pressure heater is connected to the steam outlet of the first low-pressure cylinder, the steam outlet of the second low-pressure cylinder, and the hot-side passage outlet of the third low-pressure heater; the hot-side passage outlet of the fourth low-pressure heater is connected to the hot-side passage inlet of the condenser; the cold-side passage inlet of the fourth low-pressure heater is connected to the hot-side passage outlet of the condenser; and the cold-side passage outlet of the fourth low-pressure heater is connected to the cold-side passage inlet of the third low-pressure heater.

[0011] Optionally, the low-pressure heating assembly further includes: a buffer tank, the inlet of which is connected to the hot-side passage outlet of the first low-pressure heater and the hot-side passage outlet of the second low-pressure heater; and a first pump body, the inlet of which is connected to the outlet of the buffer tank and the outlet of which is connected to the cold-side passage inlet of the first low-pressure heater.

[0012] Optionally, the high-pressure heating assembly includes: a fifth high-pressure heater, wherein the steam inlet of the hot-side passage of the fifth high-pressure heater is connected to the steam outlet of the high-pressure cylinder, and the water outlet of the cold-side passage of the fifth high-pressure heater is connected to the main steam inlet of the boiler; a sixth high-pressure heater, wherein the steam inlet of the hot-side passage of the sixth high-pressure heater is connected to the steam outlet of the high-pressure cylinder and the water outlet of the hot-side passage of the fifth high-pressure heater, and the water outlet of the cold-side passage of the sixth high-pressure heater is connected to the water inlet of the cold-side passage of the fifth high-pressure heater; and a seventh high-pressure heater, wherein the steam inlet of the hot-side passage of the seventh high-pressure heater is connected to the steam outlet of the intermediate-pressure cylinder and the water outlet of the hot-side passage of the sixth high-pressure heater, the water outlet of the hot-side passage of the seventh high-pressure heater is connected to the water inlet of the deaerator, the water outlet of the cold-side passage of the seventh high-pressure heater is connected to the water inlet of the cold-side passage of the sixth high-pressure heater, and the water inlet of the cold-side passage of the seventh high-pressure heater is connected to the water outlet of the deaerator.

[0013] Optionally, the hot-side passage outlet of the seventh high-pressure heater is connected to the hot-side passage inlet of the first low-pressure heater.

[0014] Optionally, the thermal system further includes: a cryogenic tank; an electric heater, the electric power input terminal of which is connected to the electric power output terminal of the generator, and the liquid inlet terminal of the electric heater is connected to the liquid outlet terminal of the cryogenic tank; and a high-temperature tank, the liquid inlet terminal of which is connected to the liquid outlet terminal of the electric heater, and the liquid outlet terminal of the high-temperature tank is connected to the liquid inlet terminal of the cryogenic tank.

[0015] Optionally, the thermal system further includes: a heat exchanger, wherein the inlet end of the heat exchanger's hot side passage is connected to the outlet end of the high-temperature tank, the outlet end of the heat exchanger's hot side passage is connected to the inlet end of the low-temperature tank, the inlet end of the heat exchanger's cold side passage is connected to the main steam inlet end of the boiler, and the outlet end of the heat exchanger's cold side passage is connected to the reheat steam inlet end of the boiler.

[0016] The technical solution provided in this disclosure may include the following beneficial effects:

[0017] Steam released from the pressure reducing device is used to supply steam to the first and second low-pressure cylinders, increasing the steam flow rate in both cylinders and significantly improving their flow efficiency. Furthermore, when the thermal system is under low load, the switching device closes, stopping the second low-pressure cylinder and concentrating the steam output from the intermediate-pressure cylinder and pressure reducing device into the first low-pressure cylinder, thereby greatly improving its flow efficiency. This reduces losses in the final stages of the thermal system, lowers overall energy consumption, and enables the thermal system to operate stably under low load conditions, meeting the requirements for deep peak shaving.

[0018] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this disclosure will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 This is a schematic diagram of the structure of a thermal system suitable for low-load operation according to an embodiment of this disclosure;

[0021] As shown in the figure: 1. Boiler, 2. High-pressure cylinder, 3. Medium-pressure cylinder, 4. First low-pressure cylinder, 5. Second low-pressure cylinder, 6. Generator, 7. Pressure reducer, 8. First regulating valve, 9. Second regulating valve, 10. Third regulating valve, 11. Condenser, 12. Deaerator, 13. First low-pressure heater, 14. Second low-pressure heater, 15. Third low-pressure heater, 16. Fourth low-pressure heater, 17. Buffer tank, 18. First pump body, 19. Fifth high-pressure heater, 20. Sixth high-pressure heater, 21. Seventh high-pressure heater, 22. Cryogenic tank, 23. Electric heater, 24. High-temperature tank, 25. Heat exchanger. Detailed Implementation

[0022] Embodiments of this disclosure are described in detail below, with examples of embodiments illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are used only to explain this disclosure, and should not be construed as limiting this disclosure. Rather, embodiments of this disclosure include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0023] like Figure 1 As shown in the figure, this disclosure proposes a thermal system suitable for low-load operation, including a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a pressure reducing device, a first low-pressure cylinder 4, a switching device, a second low-pressure cylinder 5, and a generator 6. The steam inlet of the high-pressure cylinder 2 is connected to the main steam outlet of the boiler 1, and the steam outlet of the high-pressure cylinder 2 is connected to the reheat steam inlet of the boiler 1. The steam inlet of the intermediate-pressure cylinder 3 is connected to the reheat steam outlet of the boiler 1. The steam inlet of the pressure reducing device is connected to the main steam outlet of the boiler 1. The steam inlet of the first low-pressure cylinder 4 is connected to the steam outlet of the intermediate-pressure cylinder 3 and the steam outlet of the pressure reducing device. The steam inlet of the switching device is connected to the steam outlet of the intermediate-pressure cylinder 3 and the steam outlet of the pressure reducing device. The steam inlet of the second low-pressure cylinder 5 is connected to the steam outlet of the switching device. The power input of the generator 6 is connected to the power output of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, the first low-pressure cylinder 4, and the second low-pressure cylinder 5.

[0024] Understandably, boiler 1 heats water into main steam through fuel combustion. The main steam enters high-pressure cylinder 2 to do work. The steam after doing work in high-pressure cylinder 2 enters boiler 1 to be heated into reheat steam. The reheat steam enters intermediate-pressure cylinder 3 to do work. The steam after doing work in intermediate-pressure cylinder 3 enters first low-pressure cylinder 4 and second low-pressure cylinder 5 to do work. Thus, the steam does work in high-pressure cylinder 2, intermediate-pressure cylinder 3 and low-pressure cylinder in sequence, driving generator 6 to generate electricity to transmit electrical energy to the outside.

[0025] The pressure reducing device is used to de-heat and depressurize the main steam of boiler 1 and release it to coordinate the balance between the steam output of boiler 1 and the steam consumption of high-pressure cylinder 2, thereby ensuring the stable operation of the overall thermal system. At the same time, the steam released by the pressure reducing device is used to supply steam to the first low-pressure cylinder 4 and the second low-pressure cylinder 5 to increase the steam flow in the first low-pressure cylinder 4 and the second low-pressure cylinder 5, thereby greatly improving the flow efficiency of the first low-pressure cylinder 4 and the second low-pressure cylinder 5, thereby reducing the losses in the last few stages of the thermal system, reducing the overall energy consumption, and enabling the thermal system to operate stably under low load conditions to meet the needs of deep peak shaving.

[0026] The switching device is used to control the connection and disconnection between the second low-pressure cylinder 5, the intermediate-pressure cylinder 3, and the pressure reducing device. When the thermal system is operating normally, the switching device is open, allowing the pressure reducing device and the intermediate-pressure cylinder 3 to simultaneously supply steam to the first low-pressure cylinder 4 and the second low-pressure cylinder 5 to meet the needs of power generation, etc. When the thermal system is under low load, the switching device is closed, causing the second low-pressure cylinder 5 to stop operating, and concentrating the steam output from the intermediate-pressure cylinder 3 and the pressure reducing device in the first low-pressure cylinder 4, thereby significantly improving the flow efficiency of the first low-pressure cylinder 4, reducing the losses in the last few stages of the thermal system, reducing overall energy consumption, and enabling the thermal system to operate stably under low load conditions to meet the needs of deep peak shaving.

[0027] It should be noted that the power generation of the thermal system can be used in conjunction with the power generation of clean energy. When the power generation of clean energy is large, the power generation demand of the thermal system is small, and the thermal system is limited by the low-load stable combustion of boiler 1. Therefore, the whole system needs to enter a low-load state, that is, deep peak shaving. At this time, due to the problem of bypass heat loss and low-pressure cylinder flow reduction, losses will occur in the last few stages of the thermal system. By using the steam discharged from the pressure reducing device into the first low-pressure cylinder 4 and the second low-pressure cylinder 5, the bypass heat loss is reduced on the one hand, and the flow of the low-pressure cylinder is increased on the other hand, thereby effectively reducing the overall energy consumption and meeting the deep peak shaving requirements of the thermal system.

[0028] Low load refers to a thermal system operating at a load of less than 20%.

[0029] like Figure 1 As shown, in some embodiments, the pressure reducing device includes a pressure reducer 7 and a first regulating valve 8. The steam inlet of the pressure reducer 7 is connected to the main steam outlet of the boiler 1, the steam inlet of the first regulating valve 8 is connected to the steam outlet of the pressure reducer 7, and the steam outlet of the first regulating valve 8 is connected to the steam inlet of the first low-pressure cylinder 4 and the steam inlet of the switching device.

[0030] Understandably, when the main steam output of boiler 1 is not coordinated with the main steam required by high-pressure cylinder 2, pressure reducer 7 will de-heat and depressurize the excess main steam and discharge it into the first low-pressure cylinder 4 and the second low-pressure cylinder 5. This not only ensures the stable operation of high-pressure cylinder 2, but also increases the steam flow in the first low-pressure cylinder 4 and the second low-pressure cylinder 5, thereby reducing the losses in the last few stages of the thermal system, reducing the overall energy consumption, and enabling the thermal system to operate stably under low load conditions, thus meeting the needs of deep peak shaving.

[0031] The steam flow from the pressure reducer 7 to the first low-pressure cylinder 4 and the second low-pressure cylinder 5 can be controlled by the first regulating valve 8, so that the steam flow in the first low-pressure cylinder 4 and the second low-pressure cylinder 5 can meet the deep peak shaving requirements of the thermal system, thereby ensuring the stable operation of the thermal system while making the thermal system more flexible.

[0032] It should be noted that the pressure reducer 7 includes two steam outlets. One steam outlet is connected to the steam inlet of the first regulating valve 8, and the other steam outlet is connected to the steam-using equipment or external space. The specific type of pressure reducer 7 can be set according to actual needs and there are no restrictions on it.

[0033] The specific type of the first regulating valve 8 can be set according to actual needs. For example, the first regulating valve 8 can be an electric regulating valve or a manual regulating valve.

[0034] like Figure 1 As shown, in some embodiments, the switching device includes a second regulating valve 9 and a third regulating valve 10. The steam inlet of the second regulating valve 9 is connected to the steam outlet of the pressure reducing device, and the steam outlet of the second regulating valve 9 is connected to the steam inlet of the second low-pressure cylinder 5. The steam inlet of the third regulating valve 10 is connected to the steam outlet of the pressure reducing device, and the steam outlet of the second regulating valve 9 is connected to the steam inlet of the second low-pressure cylinder 5. The second regulating valve 9 and the third regulating valve 10 are connected in parallel.

[0035] Understandably, the cooperation of the second regulating valve 9 and the third regulating valve 10 can not only control the on / off connection between the pressure reducing device and the second low-pressure cylinder 5, causing the second low-pressure cylinder 5 to stop operating, but also concentrate the steam output from the intermediate-pressure cylinder 3 and the pressure reducing device into the first low-pressure cylinder 4, thereby reducing the losses in the last few stages of the thermal system, reducing overall energy consumption, and enabling the thermal system to operate stably under low load conditions to meet the needs of deep peak shaving, but also regulate the steam flow between the pressure reducing device and the second low-pressure cylinder 5, ensuring the stable operation of the thermal system while making the thermal system more flexible.

[0036] It should be noted that the specific types of the second regulating valve 9 and the third regulating valve 10 can be set according to actual needs. For example, the second regulating valve 9 and the third regulating valve 10 can be electric regulating valves; the second regulating valve 9 and the third regulating valve 10 can be manual regulating valves.

[0037] The second regulating valve 9 can be used for fine adjustment of the steam flow between the pressure reducing device and the second low-pressure cylinder 5, and the third regulating valve 10 can be used for coarse adjustment of the steam flow between the pressure reducing device and the second low-pressure cylinder 5.

[0038] like Figure 1 As shown, in some embodiments, the thermal system further includes a condenser 11, a low-pressure heating assembly, a deaerator 12, and a high-pressure heating assembly. The steam inlet of the hot side passage of the condenser 11 is connected to the steam outlet of the first low-pressure cylinder 4 and the second low-pressure cylinder 5. Cooling water is introduced into the cold side passage of the condenser 11. The steam inlet of the hot side passage of the low-pressure heating assembly is connected to the steam outlet of the intermediate-pressure cylinder 3, the steam outlet of the first low-pressure cylinder 4, and the steam outlet of the second low-pressure cylinder 5. The water outlet of the hot side passage of the low-pressure heating assembly is connected to the water inlet of the hot side passage of the condenser 11. The cold side of the low-pressure heating assembly... The inlet of the passage is connected to the outlet of the hot side passage of the condenser 11. The inlet of the deaerator 12 is connected to the outlet of the intermediate pressure cylinder 3. The inlet of the deaerator 12 is connected to the outlet of the cold side passage of the low-pressure heating component. The inlet of the hot side passage of the high-pressure heating component is connected to the outlet of the high-pressure cylinder 2 and the outlet of the intermediate pressure cylinder 3. The outlet of the hot side passage of the high-pressure heating component is connected to the inlet of the deaerator 12. The inlet of the cold side passage of the high-pressure heating component is connected to the outlet of the deaerator 12. The outlet of the cold side passage of the high-pressure heating component is connected to the main steam inlet of the boiler 1.

[0039] Understandably, the steam after work is done in the first low-pressure cylinder 4 and the second low-pressure cylinder 5 enters the hot side passage of the condenser 11. Since cooling water is introduced into the cold side passage of the condenser 11, the steam in the hot side passage of the condenser 11 is condensed into condensate. The condensate passes through the cold side passage of the low-pressure heating component, the deaerator 12 and the cold side passage of the high-pressure heating component in sequence before entering the boiler 1 for reuse. This effectively reduces the operating cost of the thermal system and avoids the waste of water resources.

[0040] Among them, the deaerator 12 is used to remove dissolved oxygen and other gases from the steam outlet of the intermediate pressure cylinder 3 and the condensate, thereby reducing the corrosion of various equipment and pipelines in the thermal system and effectively extending the service life of the thermal system.

[0041] When condensate passes through the cold side passage of the low-pressure heating assembly, it is preheated because the hot side passage of the low-pressure heating assembly introduces steam from the intermediate-pressure cylinder 3, the first low-pressure cylinder 4, and the second low-pressure cylinder 5. When the deoxygenated condensate passes through the cold side passage of the high-pressure heating assembly, it is reheated because the hot side passage of the high-pressure heating assembly introduces steam from the high-pressure cylinder 2 and the intermediate-pressure cylinder 3. Thus, through the heating by the low-pressure and high-pressure heating assemblies, the water temperature at the main steam inlet of boiler 1 is effectively increased, thereby reducing the energy consumption of boiler 1 and lowering the operating cost of the thermal system.

[0042] It should be noted that the condenser 11 includes a hot side passage and a cold side passage, and the hot side passage and the cold side passage exchange heat. The heat exchange method can be set according to actual needs. For example, the hot side passage and the cold side passage can exchange heat indirectly through a medium; or the hot side passage and the cold side passage can exchange heat directly through contact.

[0043] The specific type of condenser 11 can be set according to actual needs, and there are no restrictions on it.

[0044] Deaerator 12 is also called swirl film deaerator 12 or thermal deaerator 12. The specific type of deaerator 12 can be set according to actual needs and there are no restrictions on it.

[0045] like Figure 1 As shown, in some embodiments, the low-pressure heating assembly includes a first low-pressure heater 13, a second low-pressure heater 14, a third low-pressure heater 15, and a fourth low-pressure heater 16. The steam inlet of the hot side passage of the first low-pressure heater 13 is connected to the steam outlet of the intermediate-pressure cylinder 3, and the water outlet of the cold side passage of the first low-pressure heater 13 is connected to the water inlet of the deaerator 12. The steam inlet of the hot side passage of the second low-pressure heater 14 is connected to the steam outlet of the first low-pressure cylinder 4, the steam outlet of the second low-pressure cylinder 5, and the water outlet of the hot side passage of the first low-pressure heater 13. The water outlet of the cold side passage of the second low-pressure heater 14 is connected to the water inlet of the cold side passage of the first low-pressure heater 13. The steam inlet of the hot side passage of the third low-pressure heater 15 is connected to the first low-pressure cylinder 4. The steam outlet of the first low-pressure cylinder 4, the steam outlet of the second low-pressure cylinder 5, and the hot-side passage water outlet of the second low-pressure heater 14 are connected. The cold-side passage water outlet of the third low-pressure heater 15 is connected to the cold-side passage water inlet of the second low-pressure heater 14. The hot-side passage steam inlet of the fourth low-pressure heater 16 is connected to the steam outlet of the first low-pressure cylinder 4, the steam outlet of the second low-pressure cylinder 5, and the hot-side passage water outlet of the third low-pressure heater 15. The hot-side passage water outlet of the fourth low-pressure heater 16 is connected to the hot-side passage water inlet of the condenser 11. The cold-side passage water inlet of the fourth low-pressure heater 16 is connected to the hot-side passage water outlet of the condenser 11. The cold-side passage water outlet of the fourth low-pressure heater 16 is connected to the cold-side passage water inlet of the third low-pressure heater 15.

[0046] It is understandable that the condensate discharged from the hot side passage of the condenser 11 passes sequentially through the cold side passage of the fourth low-pressure heater 16, the cold side passage of the third low-pressure heater 15, the cold side passage of the second low-pressure heater 14, and the cold side passage of the first low-pressure heater 13. The first low-pressure heater 13 uses the steam from the intermediate-pressure cylinder 3 to heat the condensate, and the second low-pressure heater 14, the third low-pressure heater 15, and the fourth low-pressure heater 16 use the steam from the first low-pressure cylinder 4 and the second low-pressure cylinder 5 to heat the condensate, so as to ensure that the temperature of the condensate can meet the requirements and reduce the energy consumption of the boiler 1.

[0047] By connecting the hot-side passages of the first low-pressure heater 13, the second low-pressure heater 14, the third low-pressure heater 15, and the fourth low-pressure heater 16 in series, the steam outlets of the intermediate-pressure cylinder 3, the first low-pressure cylinder 4, and the second low-pressure cylinder 5 can fully heat the condensate, effectively reducing heat loss and improving the heating efficiency of the condensate. At the same time, the steam outlets of the intermediate-pressure cylinder 3, the first low-pressure cylinder 4, and the second low-pressure cylinder 5, after releasing heat and condensing, enter the hot-side passage of the condenser 11 and are reused in the boiler 1 along with the condensate, further reducing the operating cost of the thermal system.

[0048] It should be noted that the first low-pressure heater 13, the second low-pressure heater 14, the third low-pressure heater 15, and the fourth low-pressure heater 16 all include a hot-side passage and a cold-side passage, which exchange heat. The hot-side passage includes a steam inlet, a water inlet, and a water outlet. The heat exchange method can be set according to actual needs. For example, the hot-side passage and the cold-side passage can exchange heat indirectly through a medium; or they can exchange heat directly through contact.

[0049] The specific types of the first low-pressure heater 13, the second low-pressure heater 14, the third low-pressure heater 15, and the fourth low-pressure heater 16 can be set according to actual needs, and there are no restrictions on this.

[0050] like Figure 1 As shown, in some embodiments, the low-pressure heating assembly further includes a buffer tank 17 and a first pump body 18. The inlet end of the buffer tank 17 is connected to the hot-side passage outlet end of the first low-pressure heater 13 and the hot-side passage outlet end of the second low-pressure heater 14. The inlet end of the first pump body 18 is connected to the outlet end of the buffer tank 17, and the outlet end of the first pump body 18 is connected to the cold-side passage inlet end of the first low-pressure heater 13.

[0051] It is understandable that by setting up the first pump body 18, the steam-water mixture after the first low-pressure heater 13 releases heat in the hot side passage and the second low-pressure heater 14 release heat in the hot side passage are pressurized and transported to the cold side passage of the first low-pressure heater 13. This effectively utilizes the heat from the steam output of the intermediate-pressure cylinder 3, the first low-pressure cylinder 4 and the second low-pressure cylinder 5, reduces the high energy consumption caused by the weakening of the interstage pressure difference under low load, ensures the stable operation of the thermal system under low load conditions, and meets the requirements for deep peak shaving.

[0052] The buffer tank 17 ensures that the steam-water mixture after the first low-pressure heater 13 releases heat in the hot side passage and the second low-pressure heater 14 release heat in the hot side passage, thus guaranteeing stable delivery by the first pump body 18.

[0053] It should be noted that the specific type of buffer tank 17 can be set according to actual needs, and there are no restrictions on it.

[0054] The specific type of the first pump body 18 can be set according to actual needs, and there are no restrictions on it.

[0055] A second pump body can also be installed between the hot side outlet of the condenser 11 and the cold side inlet of the fourth low-pressure heater 16 to ensure stable circulation of condensate.

[0056] like Figure 1 As shown, in some embodiments, the high-pressure heating assembly includes a fifth high-pressure heater 19, a sixth high-pressure heater 20, and a seventh high-pressure heater 21. The steam inlet of the hot side passage of the fifth high-pressure heater 19 is connected to the steam outlet of the high-pressure cylinder 2, and the water outlet of the cold side passage of the fifth high-pressure heater 19 is connected to the main steam inlet of the boiler 1. The steam inlet of the hot side passage of the sixth high-pressure heater 20 is connected to the steam outlet of the high-pressure cylinder 2 and the water outlet of the hot side passage of the fifth high-pressure heater 19, and the water outlet of the cold side passage of the sixth high-pressure heater 20 is connected to the water inlet of the cold side passage of the fifth high-pressure heater 19. The steam inlet of the hot side passage of the seventh high-pressure heater 21 is connected to the steam outlet of the intermediate-pressure cylinder 3 and the water outlet of the hot side passage of the sixth high-pressure heater 20, the water outlet of the hot side passage of the seventh high-pressure heater 21 is connected to the water inlet of the deaerator 12, the water outlet of the cold side passage of the seventh high-pressure heater 21 is connected to the water inlet of the cold side passage of the sixth high-pressure heater 20, and the water inlet of the cold side passage of the seventh high-pressure heater 21 is connected to the water outlet of the deaerator 12.

[0057] It is understandable that the condensate discharged from the deaerator 12 passes sequentially through the cold side passage of the seventh high-pressure heater 21, the cold side passage of the sixth high-pressure heater 20, and the cold side passage of the fifth high-pressure heater 19. The fifth high-pressure heater 19 and the sixth high-pressure heater 20 use the steam from the high-pressure cylinder 2 to heat the deaerated condensate, and the seventh high-pressure heater 21 uses the steam from the intermediate-pressure cylinder 3 to heat the deaerated condensate, so as to ensure that the temperature of the condensate can meet the requirements and reduce the energy consumption of the boiler 1.

[0058] By connecting the hot-side passages of the fifth, sixth, and seventh low-pressure heaters in series, the steam outlets of the high-pressure cylinder 2 and the intermediate-pressure cylinder 3 can fully heat the deoxygenated condensate, effectively reducing heat loss and improving the heating efficiency of the condensate. At the same time, the steam outlets of the high-pressure cylinder 2 and the intermediate-pressure cylinder 3, after exothermic condensation, enter the deaerator 12 for deoxygenation and are then reused in the boiler 1, further reducing the operating cost of the thermal system.

[0059] It should be noted that the fifth high-pressure heater 19, the sixth high-pressure heater 20 and the seventh high-pressure heater 21 all include a hot-side passage and a cold-side passage, and the hot-side passage and the cold-side passage exchange heat. The hot-side passage includes a steam inlet end, a water inlet end and a water outlet end. The heat exchange method can be set according to actual needs. For example, the hot-side passage and the cold-side passage can exchange heat indirectly through a medium; the hot-side passage and the cold-side passage can exchange heat directly through contact.

[0060] The specific types of the fifth high-pressure heater 19, the sixth high-pressure heater 20, and the seventh high-pressure heater 21 can be set according to actual needs, and there are no restrictions on this.

[0061] like Figure 1 As shown, in some embodiments, the hot-side passage outlet of the seventh high-pressure heater 21 is connected to the hot-side passage inlet of the first low-pressure heater 13.

[0062] It is understandable that the effluent from the hot side passage of the seventh high-pressure heater 21 enters the hot side passage of the first low-pressure heater 13 so that it can enter the deaerator 12 for deoxygenation along with the condensate. This avoids the drainage from the hot side passage of the high-pressure heating component from failing to flow into the deaerator 12 under low load, ensuring the stable operation of the thermal system under low load conditions and meeting the requirements for deep peak shaving.

[0063] It should be noted that a third pump body can be installed between the outlet of the deaerator 12 and the inlet of the cold side passage of the seventh high-pressure heater 21 to ensure stable circulation of condensate.

[0064] like Figure 1As shown, in some embodiments, the thermal system further includes a low-temperature tank 22, an electric heater 23, and a high-temperature tank 24. The power input terminal of the electric heater 23 is connected to the power output terminal of the generator 6. The liquid inlet terminal of the electric heater 23 is connected to the liquid outlet terminal of the low-temperature tank 22. The liquid inlet terminal of the high-temperature tank 24 is connected to the liquid outlet terminal of the electric heater 23. The liquid outlet terminal of the high-temperature tank 24 is connected to the liquid inlet terminal of the low-temperature tank 22.

[0065] Understandably, the low-temperature molten salt in the low-temperature tank 22 is heated into high-temperature molten salt when it passes through the electric heater 23 and stored in the high-temperature tank 24. The electric heater 23 is powered by the generator 6. Thus, when the thermal system can no longer reduce the power generation under low load conditions, the excess electrical energy can be converted into heat energy and stored in the molten salt, effectively improving the deep peak-shaving capability of the thermal system.

[0066] It should be noted that the electric heater 23 includes a heating tube and a heating tank. The heating tube is installed inside the heating tank. The inlet end of the heating tank is connected to the outlet end of the low-temperature tank 22, and the outlet end of the heating tank is connected to the inlet end of the high-temperature tank 24. The power input end of the heating tube is connected to the power output end of the generator 6. The specific type of the electric heater 23 can be set according to actual needs and is not limited thereto.

[0067] A fourth pump can be installed between the liquid inlet of the electric heater 23 and the liquid outlet of the cryogenic tank 22, and a fifth pump can be installed between the liquid outlet of the high-temperature tank 24 and the liquid inlet of the cryogenic tank 22, to ensure stable circulation of molten salt.

[0068] like Figure 1 As shown, in some embodiments, the thermal system further includes a heat exchanger 25. The inlet end of the hot side passage of the heat exchanger 25 is connected to the outlet end of the high-temperature tank 24, the outlet end of the hot side passage of the heat exchanger 25 is connected to the inlet end of the low-temperature tank 22, the inlet end of the cold side passage of the heat exchanger 25 is connected to the main steam inlet end of the boiler 1, and the outlet end of the cold side passage of the heat exchanger 25 is connected to the reheat steam inlet end of the boiler 1.

[0069] Understandably, when the high-temperature molten salt in the high-temperature tank 24 passes through the hot side passage of the heat exchanger 25 and the deoxygenated condensate passes through the cold side passage of the heat exchanger 25, the high-temperature molten salt heats the condensate into steam. The heated steam then enters the boiler 1 for reheating to supply the intermediate-pressure cylinder 3. Thus, when the thermal system is under low load, the excess electrical energy of the thermal system is converted into heat energy and stored in the molten salt. When the thermal system leaves the low-load state, the heat in the molten salt is released into the condensate to increase the steam flow rate in the intermediate-pressure cylinder 3, thereby effectively solving the problem of low load increase rate of the thermal system under low load conditions.

[0070] It should be noted that the heat exchanger 25 includes a hot side passage and a cold side passage, and the hot side passage and the cold side passage exchange heat. The heat exchange method can be set according to actual needs. For example, the hot side passage and the cold side passage can exchange heat indirectly through a medium; or the hot side passage and the cold side passage can exchange heat directly through contact.

[0071] The calculation of the ramp rate of the thermal system is as follows:

[0072] Under low load conditions, the ramp rate of the thermal system is close to 0. Therefore, the ramp rate S of the thermal system is determined by the power change P when the thermal system reaches its maximum peak load depth. tf The work P done by the steam output from heat exchanger 25 after entering the thermal system q The climbing time t of the thermal system p The decision is:

[0073]

[0074] Among them, the power change value P when the thermal system reaches the maximum depth of peak shaving tf for:

[0075] P tf =P;

[0076] Where P is the power of electric heater 23.

[0077] The work P done by the steam output from heat exchanger 25 after entering the thermal system q for:

[0078] P q =a×Q q ;

[0079] Among them, Q q 'a' represents the amount of steam output from heat exchanger 25, and 'a' represents the amount of work done per ton of steam entering the thermal system.

[0080] It should be noted that in the description of this disclosure, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0081] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of preferred embodiments of this disclosure includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this disclosure pertain.

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A thermal system suitable for low-load operation, characterized in that, include: boiler; A high-pressure cylinder, wherein the steam inlet of the high-pressure cylinder is connected to the main steam outlet of the boiler, and the steam outlet of the high-pressure cylinder is connected to the reheat steam inlet of the boiler. The intermediate pressure cylinder has its steam inlet end connected to the reheat steam outlet end of the boiler. A pressure reducing device, wherein the steam inlet of the pressure reducing device is connected to the main steam outlet of the boiler; The first low-pressure cylinder has its inlet end connected to the outlet end of the intermediate-pressure cylinder and the outlet end of the pressure reducing device. A switching device, wherein the steam inlet of the switching device is connected to the steam outlet of the intermediate pressure cylinder and the steam outlet of the pressure reducing device; The second low-pressure cylinder has its inlet end connected to the outlet end of the switching device. A generator, wherein the power input terminal of the generator is connected to the power output terminals of the high-pressure cylinder, the intermediate-pressure cylinder, the first low-pressure cylinder, and the second low-pressure cylinder; The pressure reducing device includes a pressure reducer and a first regulating valve. The steam inlet of the pressure reducer is connected to the main steam outlet of the boiler. The steam inlet of the first regulating valve is connected to the steam outlet of the pressure reducer. The steam outlet of the first regulating valve is connected to the steam inlet of the first low-pressure cylinder and the steam inlet of the switching device. The switching device includes a second regulating valve and a third regulating valve. The steam inlet of the second regulating valve is connected to the steam outlet of the pressure reducing device, the steam outlet of the second regulating valve is connected to the steam inlet of the second low-pressure cylinder, the steam inlet of the third regulating valve is connected to the steam outlet of the pressure reducing device, and the steam outlet of the second regulating valve is connected to the steam inlet of the second low-pressure cylinder. The second regulating valve and the third regulating valve are connected in parallel. The thermal system further includes: a low-temperature tank, an electric heater, and a high-temperature tank. The power input terminal of the electric heater is connected to the power output terminal of the generator. The liquid inlet terminal of the electric heater is connected to the liquid outlet terminal of the low-temperature tank. The liquid inlet terminal of the high-temperature tank is connected to the liquid outlet terminal of the electric heater. The liquid outlet terminal of the high-temperature tank is connected to the liquid inlet terminal of the low-temperature tank. The thermal system further includes: a heat exchanger, wherein the inlet end of the hot side passage of the heat exchanger is connected to the outlet end of the high-temperature tank, the outlet end of the hot side passage of the heat exchanger is connected to the inlet end of the low-temperature tank, the inlet end of the cold side passage of the heat exchanger is connected to the main steam inlet end of the boiler, and the outlet end of the cold side passage of the heat exchanger is connected to the reheat steam inlet end of the boiler. The ramp rate S of the thermal system is: Wherein, P tf The P value represents the power change when the thermal system reaches its maximum deep peak shaving. q The work done by the steam output from the heat exchanger after it enters the thermal system, t p The ramp-up time of the thermal system; P tf For: P tf =P, where P is the power of the electric heater; P q For: P q =a×Q q , wherein, the Q q is the amount of steam output from the heat exchanger, and 'a' is the amount of work done per ton of steam entering the thermal system.

2. The thermal system suitable for low-load operation according to claim 1, characterized in that, The thermal system also includes: The condenser has its hot-side passage inlet connected to the steam outlet of the first low-pressure cylinder and the steam outlet of the second low-pressure cylinder, and its cold-side passage leads to cooling water. The low-pressure heating component has its hot-side passage steam inlet end connected to the steam outlet end of the intermediate-pressure cylinder, the steam outlet end of the first low-pressure cylinder, and the steam outlet end of the second low-pressure cylinder; its hot-side passage water outlet end is connected to the hot-side passage water inlet end of the condenser; and its cold-side passage water inlet end is connected to the hot-side passage water outlet end of the condenser. The deaerator has its steam inlet connected to the steam outlet of the intermediate-pressure cylinder, and its water inlet connected to the water outlet of the cold side passage of the low-pressure heating assembly. The high-pressure heating assembly has its hot-side passage steam inlet connected to the steam outlet of the high-pressure cylinder and the steam outlet of the intermediate-pressure cylinder, its hot-side passage water outlet connected to the water inlet of the deaerator, its cold-side passage water inlet connected to the water outlet of the deaerator, and its cold-side passage water outlet connected to the main steam inlet of the boiler.

3. The thermal system suitable for low-load operation according to claim 2, characterized in that, The low-pressure heating component includes: The first low-pressure heater has its hot-side passage steam inlet connected to the steam outlet of the intermediate-pressure cylinder, and its cold-side passage water outlet connected to the water inlet of the deaerator. The second low-pressure heater has a hot-side passage steam inlet end connected to the steam outlet end of the first low-pressure cylinder, the steam outlet end of the second low-pressure cylinder and the hot-side passage water outlet end of the first low-pressure heater, and a cold-side passage water outlet end connected to the cold-side passage water inlet end of the first low-pressure heater. The third low-pressure heater has its hot-side passage steam inlet end connected to the steam outlet end of the first low-pressure cylinder, the steam outlet end of the second low-pressure cylinder, and the hot-side passage water outlet end of the second low-pressure heater. The cold-side passage water outlet end of the third low-pressure heater is connected to the cold-side passage water inlet end of the second low-pressure heater. The fourth low-pressure heater has its hot-side passage steam inlet connected to the steam outlet of the first low-pressure cylinder, the steam outlet of the second low-pressure cylinder, and the hot-side passage water outlet of the third low-pressure heater. The hot-side passage water outlet of the fourth low-pressure heater is connected to the hot-side passage water inlet of the condenser. The cold-side passage water inlet of the fourth low-pressure heater is connected to the hot-side passage water outlet of the condenser. The cold-side passage water outlet of the fourth low-pressure heater is connected to the cold-side passage water inlet of the third low-pressure heater.

4. The thermal system suitable for low-load operation according to claim 3, characterized in that, The low-pressure heating component also includes: A buffer tank, wherein the inlet end of the buffer tank is connected to the outlet end of the hot side passage of the first low-pressure heater and the outlet end of the hot side passage of the second low-pressure heater; The first pump body has its inlet end connected to the outlet end of the buffer tank, and its outlet end is connected to the inlet end of the cold side passage of the first low-pressure heater.

5. The thermal system suitable for low-load operation according to claim 3, characterized in that, The high-pressure heating assembly includes: The fifth high-pressure heater has its hot-side passage steam inlet end connected to the steam outlet end of the high-pressure cylinder, and its cold-side passage water outlet end connected to the main steam inlet end of the boiler. The sixth high-pressure heater has its hot-side passage steam inlet end connected to the steam outlet end of the high-pressure cylinder and the hot-side passage water outlet end of the fifth high-pressure heater, and its cold-side passage water outlet end connected to the cold-side passage water inlet end of the fifth high-pressure heater. The seventh high-pressure heater has its hot-side passage steam inlet connected to the steam outlet of the intermediate-pressure cylinder and the hot-side passage water outlet of the sixth high-pressure heater. The hot-side passage water outlet of the seventh high-pressure heater is connected to the water inlet of the deaerator. The cold-side passage water outlet of the seventh high-pressure heater is connected to the cold-side passage water inlet of the sixth high-pressure heater. The cold-side passage water inlet of the seventh high-pressure heater is connected to the water outlet of the deaerator.

6. The thermal system suitable for low-load operation according to claim 5, characterized in that, The hot-side passage outlet of the seventh high-pressure heater is connected to the hot-side passage inlet of the first low-pressure heater.

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