Thermal power multi-stage vapor compression heat supply peak shaving system with energy storage and peak shaving method

Abstract

The application relates to a thermal power multi-stage steam compression heat supply peak regulation system with energy storage and a peak regulation method, and relates to the technical field of steam waste heat utilization, and comprises a multi-stage water steam compressor unit, a condenser and a backwater pipe bundle. The multi-stage water steam compressor unit is used for multi-stage compression of exhaust steam discharged from a low-pressure cylinder of a steam turbine, and the water steam is multi-stage discharged through a plurality of discharge ports. The condenser comprises a shell, at least two steam side partitions are arranged in the shell along the width direction of the shell, so as to form a plurality of condensing chambers. The plurality of condensing chambers are arranged along the width direction of the shell and correspond to the discharge ports one by one. The condensing chambers sequentially comprise a lower water chamber, a heat supply chamber and an upper water chamber from bottom to top. The plurality of heat supply chambers are in communication with the corresponding discharge ports. The backwater pipe bundle is arranged in each heat supply chamber. The two ends of the backwater pipe bundle are respectively and sealingly penetrated through corresponding tube plates and are in communication with the corresponding upper water chamber and lower water chamber. The upper water chamber is connected with a heat network circulating water system through a heat supply pipeline.

Description

Technical Field

[0001] This application relates to the field of steam waste heat utilization technology, and in particular to a multi-stage steam compression heating and peak-shaving system and method for thermal power plants with energy storage. Background Technology

[0002] The use of waste heat from thermal power plants for heating retrofitting is a common solution adopted by power plants. The mainstream waste heat utilization solutions include high back pressure heating retrofitting, high back pressure plus ejector heating retrofitting, and heat pump heating retrofitting. On the other hand, with the increase in the grid connection of new energy sources, the demand for deep peak shaving of thermal power units has increased, and the demand for deep peak shaving of large-capacity thermal power units is urgent. To connect with heating units, many thermal power units are equipped with electric boilers for heating peak shaving.

[0003] Existing technologies involve a thermoelectric co-processing system and operation method integrating steam ejectors. This system includes a boiler, a high-, medium-, and low-pressure turbine cylinders, exhaust valve A, a condenser, a condensate pump, a low-pressure turbine heater group, a deaerator, a feedwater pump, and a high-pressure turbine heater group, all connected in sequence. It also includes various valves, high- and low-pressure steam ejectors, high- and low-temperature heat exchangers, electric heat pumps, and high- and low-temperature thermal storage tanks. During peak electricity demand periods, the high- and low-pressure steam ejectors, high- and low-temperature heat exchangers, and electric heat pumps are not in operation. The low-temperature thermal storage tank recovers waste heat from the turbine exhaust steam, while the high-temperature thermal storage tank is used for heating network supply. During off-peak electricity demand periods, the high- and low-pressure steam ejectors, high- and low-temperature heat exchangers, and electric heat pumps are all in operation. The operating steam of the steam ejectors is flexibly and orderly selected according to the heating network load, and the high-temperature thermal storage tank stores excess hot water for external heating during peak electricity demand periods.

[0004] In the aforementioned and existing high back pressure schemes, the condenser typically adopts a single-chamber structure, with steam pressure and condensation temperature determined solely by the turbine exhaust back pressure. The water-side flow is either fixed in parallel or in series, making it impossible to adjust the ratio of outlet water temperature and flow rate according to seasonal heating changes. When mechanical compression is used to improve the exhaust steam grade, the total pressure ratio required from low-pressure exhaust steam to heating temperature is relatively large. The excessively high pressure ratio of single-stage compression leads to reduced compression efficiency and increased power consumption. Furthermore, the exhaust steam from each stage of multi-stage compression makes it difficult to achieve zoned condensation in the condenser and the cascade recovery of condensate waste heat. Summary of the Invention

[0005] This application provides a multi-stage steam compression heating peak-shaving system and method for thermal power plants with energy storage, which can solve the problems that existing thermal power generating units cannot be adaptively adjusted according to complex and diverse actual operating conditions, are difficult to achieve zoned condensation in the condenser and cascade recovery of condensate waste heat, and are difficult to maintain the continuity of heating network after the operation of heating units is reduced or stopped during the power peak-shaving period.

[0006] The technical solution of this application is as follows: a multi-stage steam compression heating and peak-shaving system for thermal power plants with energy storage, comprising: A multi-stage steam compressor unit is used to compress the exhaust steam discharged from the low-pressure cylinder of the steam turbine in multiple stages and discharge the steam through multiple outlets in multiple stages. A condenser, comprising a shell, wherein at least two steam-side baffles are arranged inside the shell along its width to form multiple condensing chambers, the multiple condensing chambers being arranged along the width of the shell and corresponding one-to-one with the discharge port; The condenser chamber comprises, from bottom to top, a lower water chamber, a heating chamber, and an upper water chamber. The heating chamber and the upper water chamber, as well as the heating chamber and the lower water chamber, are sealed and isolated by tube sheets. Each of the multiple heating chambers is connected to a corresponding discharge port. The return water pipe bundle is provided in each of the heating chambers. The two ends of the return water pipe bundle are respectively sealed and penetrated through the corresponding tube sheet, and are respectively connected to the corresponding upper water chamber and lower water chamber. The upper water chamber is connected to the heating network circulating water system through the heating pipeline. A heat storage tank is connected to the heating pipeline at the top via a heat storage pipeline, and to the return water inlet of the drain chamber at the bottom via a cooling pipeline. A heat storage control component and a cooling control component are respectively provided on the heat storage pipeline and the cooling pipeline.

[0007] By adopting the above scheme, the multi-stage steam compressor unit compresses and pressurizes the low-pressure exhaust steam discharged from the steam turbine in stages, and then sends it into the corresponding condensing chambers in the condenser shell. The steam in each condensing chamber condenses and releases heat on the outer wall of the return water tube bundle, and the heat network circulating return water absorbs heat and rises in temperature in the tubes. The condensation and heat release on the steam side and the heat absorption on the water side are completed in the same shell, eliminating the need to set up an independent evaporator and reducing the number of heat exchange links and equipment. In addition, each condenser chamber is separated by a steam-side baffle, which can form a pressure gradient that increases along the compression stage, so that the exhaust pressure of each stage compressor is matched with the condensation temperature in the corresponding condenser chamber, thereby reducing the single-stage compression ratio and reducing compression power consumption. Meanwhile, the heat storage tank is connected to the heating pipeline at the top via a heat storage pipeline and to the return water inlet of the drain chamber at the bottom via a cooling pipeline. During the heat storage and cooling process, hot and cold water directly enter and exit the heat storage tank without passing through a secondary heat exchanger, reducing heat exchange temperature difference loss and enabling the system to maintain continuous heating to the heating network during peak power periods.

[0008] In one embodiment of this application, the tube sheet includes an upper tube sheet and a lower tube sheet; The upper tube sheet is provided above the condenser chamber, and the upper tube sheet, the steam-side baffle, and the shell enclose each other to form the upper water chamber; The lower tube sheet is located below the condenser chamber, and the lower tube sheet, steam-side baffle, and shell enclose each other to form the lower water chamber.

[0009] By adopting the above scheme, the upper tube sheet seals and isolates the heating chamber from the upper water chamber, and the lower tube sheet seals and isolates the heating chamber from the lower water chamber. The two ends of the return water tube bundle are sealed and pass through the upper and lower tube sheets respectively, so that a reliable pressure isolation is formed between the return water inside the tube and the steam outside the tube, preventing steam and water from mixing. The upper and lower water chambers are enclosed by the tube sheet, steam-side baffle and shell, which is compact in structure. The return water is collected and distributed by utilizing the space of the condenser shell itself, without the need for a separate water chamber structure outside the shell.

[0010] In one embodiment of this application, a flap valve is provided on the portion of the steam-side baffle located in the lower water chamber, and a connecting valve is provided on the portion of the steam-side baffle located in the upper water chamber. By controlling the opening and closing of the flap valve and the connecting valve, the series or parallel connection between the multiple return water pipe bundles can be switched.

[0011] By adopting the above scheme, and controlling the alternating opening and closing combination of the flap valve and the connecting valve installed on the same steam-side baffle, the series serpentine flow or parallel diversion flow can be switched between multiple return water pipe bundles. When the flap valve and the connecting valve on two adjacent steam-side baffles are in an alternating state, that is, the connecting valve is open and the flap valve is closed on one baffle, and the flap valve is open and the connecting valve is closed on the adjacent baffle, the return water is forced to pass through each stage of the return water pipe bundle in sequence to form a serpentine series flow. The water flow is fully heated by each stage of steam, achieving maximum efficiency. Water supply temperature rise; when all flap valves and connecting valves on the steam side diaphragms are open, adjacent lower and upper water chambers are directly connected. The return water is split and connected in parallel among all lower water chambers through each level of return water pipe bundle. The flow velocity in the pipe is reduced, and the water flow is only heated by a single stage of steam before converging and being output. The outlet water temperature rise is reduced accordingly, but the total flow rate increases. By different opening and closing combinations of flap valves and connecting valves, the matching relationship between the heating outlet water temperature and flow rate can be independently adjusted without changing the compressor operating parameters, so as to adapt to the heating demand of different seasons and different heat load conditions.

[0012] In one embodiment of this application, the flap valve includes: The flap has a window in the portion of the steam-side baffle located in the drain chamber, and the flap is rotatably connected to the inside of the window; A driving component, wherein the driving shaft of the driving component is connected and fixed to the flap to drive the flap to open or close the window.

[0013] By adopting the above scheme, the flap is rotatably connected and installed inside the window of the steam-side baffle. The drive unit drives the flap to rotate around the pivot, which can realize the opening or closing of the window. The structure is simple, the stroke is short, and the response speed is fast. When the flap is closed, it fits against the edge of the window and relies on its own area to withstand the pressure difference between adjacent water chambers, so the seal is reliable.

[0014] In one embodiment of this application, the multi-stage steam compressor unit includes multiple steam compressors connected sequentially along the steam inlet direction, and the outlets of the multiple steam compressors are all connected to discharge pipes to form multiple discharge ports. The discharge pipes pass through the shell and communicate with the heating chamber.

[0015] By adopting the above scheme, multiple steam compressors are connected in series along the steam inlet direction. The exhaust steam enters from the first-stage compressor and is pressurized step by step. The outlet of each stage compressor is connected to the corresponding heating chamber through the discharge pipeline, so that the exhaust pressure of each stage compressor corresponds to the working pressure of different condensing chambers. The discharge pipelines of each stage pass through the shell and are directly connected to the heating chamber, which shortens the exhaust steam delivery path, reduces pressure drop and heat loss along the way. In addition, the step-by-step discharge method means that each stage compressor only needs to bear the pressure difference between adjacent two stages, the single-stage pressure ratio is reduced, the compression process is closer to the isentropic process, and the compression efficiency is improved.

[0016] In one embodiment of this application, a drain pipe is also included, and the plurality of heating chambers are connected to the drain pipe through connecting pipes; a drain outlet is provided in the steam-side baffle at the bottom of the heating chamber to connect the hot wells of adjacent heating chambers and realize the step-by-step flash evaporation of condensate.

[0017] By adopting the above scheme, after the steam in each heating chamber condenses on the outer wall of the return water pipe bundle, the condensate collects at the bottom of the heating chamber. With the help of the drain outlet at the bottom of the steam-side baffle, the hot wells of adjacent heating chambers are connected. When the condensate in the high-pressure stage heating chamber flows into the adjacent low-pressure stage heating chamber through the drain outlet, due to the pressure reduction, some of the condensate undergoes flash evaporation. The generated secondary steam condenses again and releases heat in the low-pressure stage heating chamber, which is absorbed by the return water pipe bundle. This achieves the step-by-step recovery of waste heat from the condensate until the condensate from each stage finally flows into the drain pipe and is discharged uniformly. It can then be returned to the condensate system for recycling, reducing the waste heat loss carried away by the condensate during discharge.

[0018] In one embodiment of this application, the heating pipeline is provided with an outlet valve, a heating network circulating water pump, a circulating water pump outlet valve, a heating network heater inlet valve, and a heating network heater in sequence along the water outlet direction, and the outlet of the heating network heater is connected to the heating network circulating water system.

[0019] By adopting the above scheme, the outlet valve controls the on / off of the condenser's heating water supply, the heating network circulating water pump provides circulation power for the heating network return water, the circulating water pump outlet valve is used to regulate the pipeline flow, the heating network heater inlet valve controls the amount of water entering the heating network heater, and the heating network heater further heats the heating water supply to meet the required water supply temperature of the heating network; each valve is set sequentially along the water outlet direction, so that the heating pipeline has the functions of flow regulation, on / off control and temperature compensation, and the heating parameters can be adjusted step by step according to the actual load demand of the heating network.

[0020] In one embodiment of this application, the heat storage pipeline includes a heat storage bypass and a heat storage main line connected in parallel. The heat storage control component includes a heat storage inlet valve and a heat storage drain pump. The heat storage inlet valve is located on the heat storage bypass, and the heat storage drain pump is located on the heat storage main line. One end of the heat storage pipeline is connected to the heating pipeline through the heat storage valve, and the other end is connected to the top of the heat storage tank.

[0021] By adopting the above scheme, the heat storage inlet valve on the heat storage bypass uses the pressure difference between the heating pipeline and the heat storage tank to introduce some high-temperature hot water into the heat storage tank by gravity. At the same time, the heat storage drainage pump on the heat storage main pipeline provides forced delivery power when the pipeline pressure difference is insufficient, ensuring the reliability of the heat storage process. The heat storage bypass and the heat storage main pipeline are set in parallel, and gravity-flow heat storage or pumped heat storage can be selected according to the actual operating pressure conditions. The heat storage valve controls the opening and closing of the heat storage pipeline and the heating pipeline to avoid hot water leakage into the heat storage tank during non-heat storage periods.

[0022] In one embodiment of this application, the cooling pipeline includes a cooling bypass and a cooling main line connected in parallel. The cooling control component includes a cold water discharge valve and a cold water pump. The cold water discharge valve is located on the cooling bypass, and the cold water pump is located on the cooling main line. One end of the cooling pipeline is connected to the return water inlet of the drain chamber through a cold water valve, and the other end is connected to the bottom of the heat storage tank. On the heating pipeline, a heater outlet valve is provided between the access point of the heat storage valve and the outlet of the heating network heater.

[0023] By adopting the above scheme, the cold water discharge valve on the cooling bypass utilizes the pressure difference between the liquid level at the bottom of the heat storage tank and the lower water chamber to allow low-temperature cold water to flow by gravity into the return water inlet of the lower water chamber, replenishing the return water volume; the cold water pump on the cooling main line provides forced drainage power when the pressure difference is insufficient; the cold water valve controls the opening and closing of the cooling pipeline and the return water inlet of the lower water chamber; during the heat storage tank's heat release and heating period, closing the heater outlet valve allows the high-temperature hot water discharged from the heat storage tank to be directly sent to the heating network through the heating pipeline, while the low-temperature water at the bottom of the heat storage tank is replenished into the lower water chamber through the cooling pipeline, forming a displacement-type heat release process with the heat storage tank entering from the top and exiting from the bottom. The hot water and cold water inside the heat storage tank are stored in layers, reducing mixing losses inside the tank.

[0024] The second objective of this application is to provide a multi-stage steam compression heating and peak shaving method for thermal power generating units.

[0025] The technical solution is as follows: a multi-stage steam compression heating and peak shaving method for thermal power plants with energy storage, employing a multi-stage steam compression heating and peak shaving system, including the following steps: S1: Start the multi-stage steam compressor unit, compress the exhaust steam discharged from the steam turbine in multiple stages, and send it into the corresponding heating chamber through each discharge port, where it condenses and releases heat on the outer wall of the return water pipe bundle. Among them, the return water of the heating network absorbs heat and rises in temperature in the return water pipe bundle, and is then transported to the heating network circulating water system through the heating pipeline. The condensate in each heating chamber is flashed and released into the adjacent low-pressure heating chamber through the drain outlet, and finally discharged through the drain pipe. S2: Based on the heating load demand of the heating network, control the opening and closing combination of the flap valve and the connecting valve to switch the return water to either a series serpentine flow or a parallel diversion flow between multiple return water pipe bundles, so as to adjust the matching relationship between the heating outlet water temperature and flow rate. S3: During periods of low power load, increase the operating power of the multi-stage steam compressor unit, turn on the heat storage control component, and introduce some of the high-temperature hot water in the heating pipeline into the heat storage tank for storage via the heat storage pipeline. During peak electricity load periods, the operating power of the multi-stage steam compressor unit is reduced or it is shut down to release peak loads in the power grid. At the same time, the high-temperature hot water stored in the heat storage tank is replenished into the heating pipeline through the heat storage pipeline, and the low-temperature water below the heat storage tank is replenished into the return water inlet of the lower water chamber through the cooling pipeline to compensate for the heating network supply.

[0026] By adopting the above scheme, multi-stage compression and compartment condensation are carried out simultaneously. The waste heat of the exhaust steam is absorbed step by step by the return water pipe bundle in each heating chamber. The condensate releases heat through flash evaporation through the drain outlet, realizing the cascade utilization of the waste heat of the exhaust steam. At the same time, by switching the series or parallel connection of the return water pipe bundle through the combination of opening and closing flap valves and connecting valves, the ratio of outlet water temperature to flow rate is adjusted under the condition that the compressor operating conditions remain unchanged, so that the entire system can adapt to the seasonal changes in heating load. In addition, this device can also increase the compressor power during the off-peak period and store the excess heat in the heat storage tank. During the peak period, the compressor power is reduced or the machine is shut down to release electricity. At the same time, the high-temperature hot water stored in the heat storage tank is added to the heating pipeline to maintain heating. The low-temperature water at the bottom of the heat storage tank flows back to the lower water chamber through the cooling pipeline as return water supplement, decoupling the peak-shaving process from the heating process, ensuring the continuity of heating network while meeting the peak-shaving needs of the power grid.

[0027] In summary, this application includes at least one of the following beneficial technical effects: The low-pressure exhaust steam discharged from the turbine is compressed stage by stage using a multi-stage steam compressor unit. Each stage's exhaust steam is sent into a corresponding condensing chamber within the condenser shell, separated by steam-side baffles. This creates a pressure gradient along the stage direction within each condensing chamber. Each stage compressor only needs to bear the pressure difference between adjacent stages, reducing the single-stage pressure ratio and thus lowering compression power consumption. Simultaneously, the steam in each condensing chamber condenses and releases heat on the outer wall of the return water tube bundle. The condensate flows through the drain ports at the bottom of the steam-side baffles to the adjacent low-pressure stage heating chambers, where it undergoes a process of heat exchange. Flash evaporation generates secondary steam that is condensed and released heat again in the low-pressure stage heating chamber and absorbed by the return water pipe bundle. This enables the step-by-step recovery of condensate waste heat and can also work in conjunction with water-side heat absorption within the same shell, eliminating the need for a separate evaporator and reducing the number of heat exchange stages and the corresponding heat transfer temperature difference losses. The synergistic effect of the above-mentioned multi-stage low-pressure ratio compression, step-by-step flash evaporation waste heat recovery, and reduction of heat exchange stages within the same shell structure increases the heating output per unit input power of the compressor, improves the system's energy efficiency coefficient, and enhances the overall energy efficiency of the system.

[0028] 2. By installing flap valves in the lower water chamber and connecting valves in the upper water chamber of the steam-side diaphragm, under high-temperature heating conditions during severe cold periods, the flap valves and connecting valves on each steam-side diaphragm are alternately opened and closed, creating a serpentine series flow of return water between each level of return water pipe bundle. The water flows through each level of pipe bundle sequentially and is heated by the corresponding stage of steam, maximizing the outlet water temperature rise. Under high-flow-rate and low-temperature-difference heating conditions during transitional seasons, all flap valves and connecting valves are opened, connecting the lower and upper water chambers of each level. The return water flows in parallel and is distributed between each level of pipe bundle, reducing the flow velocity within each pipe bundle, decreasing the water-side flow resistance, and decreasing the outlet water temperature rise while increasing the total flow rate. Through the switching of the opening and closing combinations of the above valves, the matching relationship between the heating outlet water temperature and flow rate is adjusted without changing the operating power and exhaust steam pressure of each level of compressor, allowing the system to adapt to the heating needs of different seasons and different heat load conditions.

[0029] 3. During periods of low electricity demand, the multi-stage steam compressor unit operates at higher power. A portion of the high-temperature hot water in the heating pipeline directly enters the upper part of the heat storage tank via the heat storage pipeline for storage. The cold water at the bottom of the heat storage tank is discharged into the return water inlet of the lower water chamber via the cooling pipe to participate in circulation, forming a stratified storage state of hot water at the top and cold water at the bottom. During periods of high electricity demand, the compressor unit's operating power is reduced or it is shut down to release electricity for peak shaving. The high-temperature hot water at the top of the heat storage tank is directly replenished into the heating pipeline to supply heat to the heating network via the heat storage pipeline, while the low-temperature water at the bottom is simultaneously replenished into the lower water chamber via the cooling pipe as circulating return water, forming a displacement-type heat release process. This ensures that the heat release outlet temperature of the heat storage tank during peak shaving periods remains consistent with the heat supply outlet temperature during normal compressor operation. Therefore, although the system reduces or stops the operation of the compressor unit during peak electricity demand periods, the heating parameters and continuity of the heating network are not affected by the heat release compensation from the heat storage tank. This also allows the system to perform cascade heat extraction and series-parallel temperature regulation for a longer period, achieving a simultaneous balance between peak electricity demand and heating security. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a multi-stage steam compression heating and peak-shaving system with energy storage provided in the embodiments of this application; Figure 2 This is a cross-sectional view of the shell of the thermal power multi-stage steam compression heating and peak shaving system with energy storage provided in the embodiments of this application under full load three-stage compression conditions during severe cold periods; Figure 3 This is a cross-sectional view of the shell of the thermal power multi-stage steam compression heating and peak shaving system with energy storage provided in the embodiments of this application under the two-stage compression condition during the shallow cold period. Figure 4 This is a cross-sectional view of the shell of the thermal power multi-stage steam compression heating and peak shaving system with energy storage provided in the embodiments of this application, under the single-stage compression condition during the initial and final cold periods.

[0031] Explanation of reference numerals in the attached diagram: 1. Low-pressure cylinder of steam turbine; 2. Air-cooled island; 3. Drive motor; 4. First-stage steam compressor; 5. Second-stage steam compressor; 6. Third-stage steam compressor; 7. First-stage outlet valve; 8. First-stage steam inlet valve; 9. Second-stage steam inlet valve; 10. Second-stage outlet valve; 11. Return water inlet valve; 12. First-stage condensate chamber; 13. Second-stage condensate chamber; 14. Third-stage condensate chamber; 15. Water outlet valve; 16. First drain valve; 17. Second drain valve; 18. Third drain valve; 19. Heat network circulation. 20. Water pump; 21. Circulating water pump outlet valve; 22. Heat network heater inlet valve; 23. Heater outlet valve; 24. Thermal storage inlet valve; 25. Thermal storage drain pump; 26. Cold water drain valve; 27. Cold water pump; 28. Thermal storage tank; 29. ​​Thermal storage valve; 30. Cold water valve; 31. Tube sheet; 301. Upper tube sheet; 302. Lower tube sheet; 32. Shell; 33. Upper water chamber; 34. Heating chamber; 35. Lower water chamber; 36. Steam side baffle; 37. Return water pipe bundle; 38. Flip valve; 39. Connecting valve. Detailed Implementation

[0032] The following is in conjunction with the appendix Figures 1-4 This application provides a further detailed description of the multi-stage steam compression heating and peak-shaving system with energy storage provided in this application, as well as the peak-shaving method.

[0033] The thermal power multi-stage steam compression heating and peak-shaving system with energy storage provided in this application embodiment includes: A multi-stage steam compressor unit is used to compress the exhaust steam discharged from the low-pressure cylinder 1 of the steam turbine in multiple stages and discharge the steam through multiple discharge ports in multiple stages. A condenser, comprising a shell 32, wherein at least two steam-side baffles 36 are provided inside the shell 32 along its width direction to form a plurality of condensing chambers, wherein the plurality of condensing chambers are arranged along the width direction of the shell 32 and correspond one-to-one with the discharge port; The condenser chamber includes, from bottom to top, a lower water chamber 35, a heating chamber 34, and an upper water chamber 33. The heating chamber 34 and the upper water chamber 33, as well as the heating chamber 34 and the lower water chamber 35, are respectively sealed and isolated by tube sheets 31. The plurality of heating chambers 34 are respectively connected to the corresponding discharge ports. The return water pipe bundle 37 is provided in each of the heating chambers 34. The two ends of the return water pipe bundle 37 are respectively sealed and penetrated on the corresponding tube sheet 31, and are respectively connected to the corresponding upper water chamber 33 and lower water chamber 35. The upper water chamber 33 is connected to the heating network circulating water system through the heating pipeline. The heat storage tank 28 is connected to the heating pipeline via a heat storage pipeline at its top and to the return water inlet of the drain chamber 35 via a cooling pipeline at its bottom. The heat storage pipeline and the cooling pipeline are respectively equipped with a heat storage control component and a cooling control component.

[0034] In this embodiment, the inlet of the multi-stage steam compressor unit is connected to the low-pressure cylinder of the steam turbine, and the low-pressure cylinder of the steam turbine can also be connected to the air-cooled island 2.

[0035] The tube sheet 31 includes an upper tube sheet 301 and a lower tube sheet 302; The upper tube sheet 301 is provided above the condenser chamber, and the upper tube sheet 301, the steam-side baffle 36 and the shell 32 enclose each other to form the upper water chamber 33; The lower tube sheet 302 is provided below the condenser chamber. The lower tube sheet 302, the steam-side baffle 36 and the shell 32 enclose each other to form the lower water chamber 35.

[0036] In this embodiment, a return water pipe is provided that is connected to the inlet end of the drain chamber 35, and a return water inlet valve 11 is provided on the return water pipe.

[0037] The portion of the steam-side baffle 36 located within the lower water chamber 35 is provided with a flap valve 38, and the portion of the steam-side baffle 36 located within the upper water chamber 33 is provided with a connecting valve 39. By controlling the opening and closing of the flap valve 38 and the connecting valve 39, the series or parallel connection between the multiple return water pipe bundles 37 can be switched.

[0038] The flap valve 38 includes a flap (not shown) and a drive component (not shown). The portion of the steam-side baffle 36 located within the drain chamber 35 has a window. The flap is rotatably connected to the inside of the window. The drive shaft of the drive component is connected and fixed to the flap to drive the flap to open or close the window.

[0039] In this embodiment, the driving component is a servo motor, which is installed on the outer wall of the housing 32. Its drive shaft passes through the housing 32 through a sealing stuffing box and is fixedly connected to the rotating shaft of the flap. The edge of the flap is provided with an elastic sealing strip. When the flap is rotated to the closed position, the elastic sealing strip fits and seals against the frame of the window to block the water flow path between adjacent drain chambers 35.

[0040] The connecting valve 39 is a butterfly valve, which is installed in the through hole of the steam-side baffle 36 located in the water chamber 33. Its valve stem passes through the housing 32 through a sealing structure and is connected to an external actuator.

[0041] It should be noted that under the variable operating condition where some stages of the compressor are shut down, no steam enters the heating chamber 34 corresponding to the shut-down stage, and the return water pipe bundle 37 of that stage does not participate in heat exchange. At this time, the flap valve 38 and the connecting valve 39 on the steam-side baffle 36 of that stage are opened, and the return water pipe bundle 37 of the shut-down stage is connected in parallel with the return water pipe bundle 37 of the adjacent operating stage. The return water of the heating network flows through the pipe bundles of the operating stage and the shut-down stage at the same time. The return water in the pipe bundle of the operating stage is heated by steam, while the return water in the pipe bundle of the shut-down stage remains at its original temperature and is not heated. The two return waters merge and mix in the shared upper water chamber 33 or lower water chamber 35 before continuing to flow.

[0042] Although the shut-down tube bundle does not participate in heat exchange, it provides additional water-side flow cross-sectional area, increasing the total flow cross-sectional area to several times that of the operating tube bundle alone. The flow velocity inside the tube is correspondingly reduced to a fraction of the original velocity, and the water-side flow resistance decreases significantly according to the square of the flow velocity, thereby significantly reducing the operating power consumption of the heating network circulating water pump 19. At the same time, the high-temperature water at the outlet of the operating tube bundle and the low-temperature water at the outlet of the shut-down tube bundle naturally mix in the water chamber, playing a role in cooling the water inside the shell. The output temperature is between the two, and a medium-low temperature water supply that matches the low-load conditions can be obtained without the need to install an external mixing device on the heating network side.

[0043] In the series process, the return water flows through all the tube bundles in sequence, and the water-side heat exchange area is the sum of the areas of each tube bundle. The total heat transfer temperature difference decreases step by step along the flow direction but always remains positive, so the total temperature rise is the largest. In the parallel process, each tube bundle exchanges heat independently, the water flow rate is distributed among the tube bundles, the flow velocity in each tube bundle decreases, the heat transfer temperature difference between the return water and steam in a single tube bundle increases, and the heat exchange is more complete. However, the return water is only output after passing through a single tube bundle, so the temperature rise is limited.

[0044] The multi-stage steam compressor unit includes multiple steam compressors connected sequentially along the steam inlet direction. The outlets of the multiple steam compressors are all connected to discharge pipes to form multiple discharge ports. The discharge pipes pass through the housing 32 and communicate with the heating chamber 34.

[0045] In this embodiment, the multi-stage steam compressor unit may include a first-stage steam compressor 4, a second-stage steam compressor 5, and a third-stage steam compressor 6. The outlet of the first-stage steam compressor 4 is connected to the inlet of the second-stage steam compressor 5, and a first-stage outlet valve 7 is provided on the connecting pipe between the two. The outlet of the second-stage steam compressor 5 is connected to the inlet of the third-stage steam compressor 6, and a second-stage outlet valve 10 is provided on the connecting pipe between the two. The first-stage steam compressor 4 is equipped with a first-stage steam inlet valve 8 on its discharge pipeline; the second-stage steam compressor 5 is equipped with a second-stage steam inlet valve 9 on its discharge pipeline. A drive motor 3 can also be set to drive the first-stage steam compressor 4, the second-stage steam compressor 5 and the third-stage steam compressor 6 to compress steam. Correspondingly, two steam-side baffles 36 can be provided inside the shell 32 to form three condensing chambers, namely the first-stage condensing chamber 12, the second-stage condensing chamber 13 and the third-stage condensing chamber 14. The first-stage condensing chamber 12, the second-stage condensing chamber 13 and the third-stage condensing chamber 14 are respectively connected to the first-stage steam compressor 4, the second-stage steam compressor 5 and the third-stage steam compressor 6.

[0046] It also includes a drain pipe, and multiple heating chambers 34 are connected to the drain pipe through connecting pipes; the steam side baffle 36 is provided with a drain outlet at the bottom of the heating chamber 34 so that the hot wells of adjacent heating chambers 34 can be connected to realize the step-by-step flash evaporation of condensate.

[0047] In this embodiment, the drain pipes can also be respectively provided with a first drain pipe, a second drain pipe and a third drain pipe. The first drain pipe is provided with a first drain valve 16, the second drain pipe is provided with a second drain valve 17, and the third drain pipe is provided with a third drain valve 18.

[0048] The heating pipeline is provided with an outlet valve 15, a heating network circulating water pump 19, a circulating water pump outlet valve 20, a heating network heater inlet valve 21, and a heating network heater 22 in sequence along the water outlet direction. The outlet of the heating network heater 22 is connected to the heating network circulating water system.

[0049] The heat storage pipeline includes a heat storage bypass and a heat storage main line connected in parallel. The heat storage control component includes a heat storage inlet valve 24 and a heat storage drain pump 25. The heat storage inlet valve 24 is located on the heat storage bypass, and the heat storage drain pump 25 is located on the heat storage main line. One end of the heat storage pipeline is connected to the heating pipeline through a heat storage valve 29, and the other end is connected to the top of the heat storage tank 28.

[0050] In this embodiment, the heat storage bypass and the heat storage main line are connected in parallel between the heat storage valve 29 and the heat storage tank 28. During heat storage, the heat storage valve 29 and the heat storage inlet valve 24 are opened, and the high-temperature hot water in the heating pipeline flows into the area above the heat storage tank 28 through the heat storage bypass under the pressure of the system network, without the need for additional power equipment. During heat release, the heat storage inlet valve 24 is closed, and the heat storage drain pump 25 is started. The heat storage drain pump 25 pumps the high-temperature hot water stored above the heat storage tank 28 to the heating pipeline through the heat storage main line to overcome the pressure of the network system and replenish the hot water into the heating network. The heat storage valve 29 is located at the connection between the heat storage pipeline and the heating pipeline, and is used to control the overall on / off state between the heat storage pipeline and the heating pipeline. When the system is in a normal heating operation state without heat storage and release, the heat storage valve 29 is closed, the heat storage pipeline is isolated from the heating pipeline, and the heat storage tank 28 does not participate in the circulation.

[0051] The cooling pipeline includes a cooling bypass and a cooling main line connected in parallel. The cooling control component includes a cold water discharge valve 26 and a cold water pump 27. The cold water discharge valve 26 is located on the cooling bypass, and the cold water pump 27 is located on the cooling main line. One end of the cooling pipeline is connected to the return water inlet of the lower water chamber 35 through a cold water valve 30, and the other end is connected to the bottom of the heat storage tank 28. On the heating pipeline, a heater outlet valve 23 is provided between the access point of the heat storage valve 29 and the outlet of the heating network heater 22.

[0052] The second objective of this application is to provide a method for multi-stage steam compression heating and peak shaving in thermal power plants with energy storage.

[0053] The technical solution is as follows: a multi-stage steam compression heating and peak shaving method for thermal power plants with energy storage, employing a multi-stage steam compression heating and peak shaving system, including the following steps: S1: Start the multi-stage steam compressor unit, compress the exhaust steam discharged from the steam turbine in multiple stages, and send it into the corresponding heating chamber 34 through each discharge port, where it condenses and releases heat on the outer wall of the return water pipe bundle 37. Among them, the return water of the heating network absorbs heat and rises in temperature in the return water bundle 37, and is then transported to the heating network circulating water system through the heating pipeline. Condensate in each heating chamber 34 is flashed and released to the adjacent low-pressure heating chamber 34 through the drain outlet, and finally discharged through the drain pipe; S2: Based on the heating load demand of the heating network, control the opening and closing combination of the flap valve 38 and the connecting valve 39 to switch the return water to either a series serpentine flow or a parallel diversion flow among the multiple return water pipe bundles 37, so as to adjust the matching relationship between the heating outlet water temperature and flow rate. S3: During periods of low power load, increase the operating power of the multi-stage steam compressor unit, turn on the heat storage control component, and introduce some of the high-temperature hot water in the heating pipeline into the heat storage tank 28 for storage via the heat storage pipeline. During peak electricity load periods, the operating power of the multi-stage steam compressor unit is reduced or it is shut down to release peak loads in the power grid. At the same time, the high-temperature hot water stored in the heat storage tank 28 is replenished into the heating pipeline through the heat storage pipeline, and the low-temperature water below the heat storage tank 28 is replenished into the return water inlet of the lower water chamber 35 through the cooling pipeline to compensate for the heating network supply.

[0054] In this embodiment, in step S1, the steam compressors at each stage are started sequentially from the low-pressure stage to the high-pressure stage. After the exhaust pressure of each stage stabilizes to the corresponding condenser design pressure, the steam inlet valves on the corresponding exhaust pipelines are opened to introduce compressed steam into each stage of the heating chamber 34. The steam releases latent heat of condensation upon contact with the outer wall of the corresponding return water pipe bundle 37 in each stage of the heating chamber 34, and the condensate flows into the hot well at the bottom of each stage of the heating chamber 34. The condensate in the hot well of the high-pressure stage heating chamber 34 is then... Due to the pressure difference between adjacent stages, the condensate flows spontaneously into the adjacent low-pressure stage heating chamber 34 through the drain outlet at the bottom of the side partition 36. Since the pressure in the low-pressure stage heating chamber 34 is lower than the saturation pressure corresponding to the condensate, the condensate undergoes flash evaporation to generate secondary steam. The secondary steam condenses again on the outer wall of the return water tube bundle 37 in the low-pressure stage heating chamber 34, releasing heat and being absorbed by the return water in the tube, thus realizing the step-by-step recovery and utilization of the waste heat of the condensate. The final condensate after all flash evaporation is discharged from the system through the drain pipe at the bottom of the lowest pressure stage heating chamber 34.

[0055] In step S2, the opening and closing combination of the flap valve 38 and the connecting valve 39 is determined based on the outdoor ambient temperature and the return water temperature of the heating network: When the outdoor temperature is lower than the set low temperature threshold, the flap valves 38 and connecting valves 39 on each steam-side baffle 36 are set to an alternating state—the connecting valve 39 on the first steam-side baffle 36 is open and the flap valve 38 is closed, and the flap valve 38 on the second steam-side baffle 36 is open and the connecting valve 39 is closed—the return water enters the first-stage return water bundle 37 from the first-stage lower water chamber 35 and flows upward to the first-stage upper water chamber 33. It then flows into the second-stage upper water chamber 33 through the connecting valve 39 opened on the first steam-side baffle 36, flows downward in the second-stage return water bundle 37 to the second-stage lower water chamber 35, flows into the third-stage lower water chamber 35 through the flap valve 38 opened on the second steam-side baffle 36, and flows upward in the third-stage return water bundle 37 to the third-stage upper water chamber 33 before being discharged, forming a serpentine series flow. It is heated by steam at each stage to achieve the maximum water supply temperature rise. When the outdoor temperature is between the set low temperature threshold and the set high temperature threshold, the flap valve 38 and the connecting valve 39 on part of the steam side diaphragm 36 are opened simultaneously, so that the condensing chambers on both sides of the diaphragm are connected in parallel. The remaining diaphragms are kept in an alternating state to maintain the series relationship. The first-stage compressor in the parallel stage can be shut down accordingly to reduce the system power consumption. At this time, the shut-down stage tube bundle serves as a bypass flow channel to share the water volume and reduce the water-side resistance. When the outdoor temperature is higher than the set high temperature threshold, all flap valves 38 and connecting valves 39 are opened, all lower water chambers 35 are connected, all upper water chambers 33 are connected, all return water pipe bundles 37 are operated in parallel, only the first-stage compressor is kept running, the heat network return water is diverted to all pipe bundles, the operating stage pipe bundle heats the return water, and the shutdown stage pipe bundle serves as a cold water bypass channel. The water flows from all directions are mixed in the upper water chamber 33 and then output a low-temperature, high-flow water supply that matches the low-load operating conditions.

[0056] In summary, taking a direct air-cooled unit as an example, the unit's exhaust steam pressure is 10 kPa, exhaust steam temperature is 46℃, and exhaust steam enthalpy is 2584.3 kJ / kg. The first-stage steam compressor has a compression ratio of 2, resulting in a first-stage outlet steam pressure of 20 kPa. The first-stage steam compressor's adiabatic compression efficiency is 0.8, and its outlet steam enthalpy is 2722.9 kJ / kg. Assuming a first-stage exhaust steam utilization rate of 80 t / h, the first-stage adiabatic compression power consumption is 2464.1 kW, with an actual power consumption of 3080.1 kW. The first-stage steam compressor outlet is equipped with a first-stage heating network condenser with a terminal temperature difference of 2℃. The first-stage heating network condenser outlet water temperature is approximately 58.1℃, and the heating network circulating water flow rate is 1500 t / h. Therefore, the steam consumption at the first-stage steam compressor outlet is approximately 20.48 t / h, and the calculated heat exchange power of the first-stage heating network condenser is approximately 14.1 MW.

[0057] The second-stage steam compressor 5 has a pressure ratio of 2, resulting in an outlet pressure of 40 kPa, an adiabatic efficiency of 0.8, an outlet enthalpy of approximately 2893.2 kJ / kg, and an outlet steam temperature of approximately 207.7°C. Therefore, the calculated power consumption of the second-stage steam compressor is 2816.3 kW. The second-stage condenser is designed with a terminal temperature difference of 2°C, an outlet water temperature of 73.9°C, and a steam flow rate of approximately 38.5 t / h. The heating power of the second-stage condenser is 27556 ​​kW.

[0058] The compression ratio of the third-stage steam compressor 6 is 1.43, therefore the outlet pressure of the third-stage steam compressor 6 is 57.2 kPa, the adiabatic efficiency of the third-stage steam compressor 6 is 0.8, the outlet enthalpy of the third-stage steam compressor 6 is approximately 2996.3 kJ / kg, the outlet temperature of the third-stage steam compressor 6 is approximately 260℃, and the power consumption of the third-stage steam compressor 6 is 601.5 kW. The terminal temperature difference of the third-stage heating network condenser is 2℃, therefore the outlet temperature of the third-stage heating network condenser is approximately 82.7℃, the steam consumption of the third-stage heating network condenser is approximately 21 t / h, and the heat exchange power of the third-stage heating network condenser is 15403.5 kW.

[0059] Ignoring the power consumption of the auxiliary system, the total power consumption of the three-stage steam compressor is approximately 6497.9kW, while the actual heating power can reach 57021.7kW, and the heating COP can reach 8.7.

[0060] The thermal storage tank 28 is designed to store energy for 6 hours and release heat externally for 6 hours. The thermal storage drainage pump 25 and the chilled water pump 27 are each equipped with a capacity of 500 t / h. Therefore, the total thermal storage tank 28 is designed to be approximately 3200 m³. During peak-shaving periods, the thermal storage tank 28 releases heat externally, providing about one-third of the heat load for the heating network circulating water. The thermal storage tank 28 can perform two heat storage and heat release processes daily.

[0061] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A multi-stage steam compression heating and peak-shaving system for thermal power plants with energy storage, characterized in that, include: A multi-stage steam compressor unit is used to compress the exhaust steam discharged from the low-pressure cylinder (1) of the steam turbine in multiple stages and discharge the steam through multiple discharge ports in multiple stages. A condenser, the condenser including a shell (32), the shell (32) having at least two steam-side baffles (36) arranged inside it along its width direction to form a plurality of condensing chambers, the plurality of condensing chambers being arranged along the width direction of the shell (32) and corresponding one-to-one with the discharge port; The condenser chamber includes, from bottom to top, a lower water chamber (35), a heating chamber (34), and an upper water chamber (33). The heating chamber (34) and the upper water chamber (33), as well as the heating chamber (34) and the lower water chamber (35), are sealed and isolated by tube sheets (31). The plurality of heating chambers (34) are respectively connected to the corresponding discharge ports. The return water pipe bundle (37) is provided in each of the heating chambers (34). The two ends of the return water pipe bundle (37) are respectively sealed and penetrated on the corresponding tube sheet (31) and are respectively connected to the corresponding upper water chamber (33) and lower water chamber (35). The upper water chamber (33) is connected to the heating network circulating water system through the heating pipeline. A heat storage tank (28) is connected to the heating pipeline above the heat storage tank (28) via a heat storage pipeline, and connected to the return water inlet of the water chamber (35) below the heat storage tank (28) via a cooling pipeline. A heat storage control component and a cooling control component are respectively provided on the heat storage pipeline and the cooling pipeline.

2. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 1, characterized in that: The tube sheet (31) includes an upper tube sheet (301) and a lower tube sheet (302); The upper tube sheet (301) is provided above the condenser chamber. The upper tube sheet (301), the steam-side baffle (36), and the shell (32) enclose each other to form the upper water chamber (33). The lower tube sheet (302) is provided below the condenser chamber. The lower tube sheet (302), the steam-side baffle (36), and the shell (32) enclose each other to form the lower water chamber (35).

3. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 2, characterized in that: The portion of the steam-side baffle (36) located within the lower water chamber (35) is equipped with a flap valve (38), and the portion of the steam-side baffle (36) located within the upper water chamber (33) is equipped with a connecting valve (39). By controlling the opening and closing of the flap valve (38) and the connecting valve (39), the series or parallel connection between the multiple return water pipe bundles (37) can be switched.

4. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 3, characterized in that, The flap valve (38) includes: The flap is provided with a window in the part of the steam side baffle (36) located in the drain chamber (35), and the flap is rotatably connected to the inside of the window; A driving component, wherein the driving shaft of the driving component is connected and fixed to the flap to drive the flap to open or close the window.

5. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 1, characterized in that: The multi-stage steam compressor unit includes multiple steam compressors connected in sequence along the steam inlet direction. The outlets of the multiple steam compressors are all connected to discharge pipes to form multiple discharge ports. The discharge pipes pass through the housing (32) and communicate with the heating chamber (34).

6. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 3, characterized in that: It also includes a drain pipe, and multiple heating chambers (34) are connected to the drain pipe through connecting pipes; the steam side baffle (36) is provided with a drain outlet at the bottom of the heating chamber (34) so ​​that the hot wells of adjacent heating chambers (34) can be connected to realize the step-by-step flash evaporation of condensate.

7. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 1, characterized in that: The heating pipeline is provided with an outlet valve (15), a heating network circulating water pump (19), a circulating water pump outlet valve (20), a heating network heater inlet valve (21), and a heating network heater (22) in sequence along the water outlet direction. The outlet of the heating network heater (22) is connected to the heating network circulating water system.

8. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 7, characterized in that: The heat storage pipeline includes a heat storage bypass and a heat storage main line connected in parallel. The heat storage control component includes a heat storage inlet valve (24) and a heat storage drain pump (25). The heat storage inlet valve (24) is located on the heat storage bypass, and the heat storage drain pump (25) is located on the heat storage main line. One end of the heat storage pipeline is connected to the heating pipeline through a heat storage valve (29), and the other end is connected to the top of the heat storage tank (28).

9. The thermal power multi-stage steam compression heating and peak-shaving system with energy storage according to claim 8, characterized in that: The cooling pipeline includes a cooling bypass and a cooling main line connected in parallel. The cooling control component includes a cold water discharge valve (26) and a cold water pump (27). The cold water discharge valve (26) is located on the cooling bypass, and the cold water pump (27) is located on the cooling main line. One end of the cooling pipeline is connected to the return water inlet of the drain chamber (35) through a cold water valve (30), and the other end is connected to the bottom of the heat storage tank (28). On the heating pipeline, a heater outlet valve (23) is provided between the access point of the heat storage valve (29) and the outlet of the heating network heater (22).

10. A multi-stage steam compression heating and peak shaving method for thermal power plants with energy storage, employing the multi-stage steam compression heating and peak shaving system as described in claim 6, characterized in that... Includes the following steps: S1: Start the multi-stage steam compressor unit, compress the exhaust steam discharged from the turbine in multiple stages, and send it into the corresponding heating chamber (34) through each discharge port, where it condenses and releases heat on the outer wall of the return water pipe bundle (37); Among them, the heat network circulating return water absorbs heat and rises in temperature in the return water bundle (37) and is transported to the heat network circulating water system through the heating pipeline; The condensate in each heating chamber (34) is flashed and released into the adjacent low-pressure heating chamber (34) through the drain outlet, and finally discharged through the drain pipe; S2: According to the heating load demand of the heating network, control the opening and closing combination of the flap valve (38) and the connecting valve (39) to switch the return water to the series serpentine flow or parallel diversion flow between multiple return water pipe bundles (37) to adjust the matching relationship between the heating outlet water temperature and flow rate. S3: During periods of low power load, increase the operating power of the multi-stage steam compressor unit, turn on the heat storage control component, and introduce some of the high-temperature hot water in the heating pipeline into the heat storage tank (28) for storage. During peak electricity load periods, the operating power of the multi-stage steam compressor unit is reduced or it is shut down to release the peak load of the power grid. At the same time, the high-temperature hot water stored in the heat storage tank (28) is replenished into the heating pipeline through the heat storage pipeline, and the low-temperature water below the heat storage tank (28) is replenished into the return water inlet of the lower water chamber (35) through the cooling pipeline to compensate for the heating network.

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