Bypass regenerative turbine system for low load feedwater heating of a thermal power unit

Abstract

The present application relates to the technical fields of deep peak regulation and energy saving and consumption reduction, and discloses a bypass heat recovery turbine system for feed water heating of a thermal power unit under low load, comprising the following modules: a boiler, a main steam valve, a low-load bypass regulating valve, a main regulating valve, a bypass heat recovery turbine and a feed water temperature regulator; the main steam outlet pipeline of the boiler is connected with the main steam valve, and the outlet flange of the main steam valve is connected with the inlet of the main regulating valve. The existing steam circulating power generation system of a steam turbine is improved, a bypass heat recovery turbine specially used for regulating the temperature of boiler feed water is arranged, the turbine exhaust pressure and exhaust steam flow are controlled by changing the opening degree of the bypass regulating valve and the turbine rotating speed, the temperature of the boiler feed water is always kept in the optimal temperature range, the steam work capacity is improved by using part of the throttle-free main steam under low load constant pressure operation, the coal consumption rate of the unit is reduced, and the overall energy saving level is improved.

Description

Technical Field

[0001] This invention relates to the field of deep peak shaving and energy saving technology, specifically a bypass regenerative turbine system for heating feedwater at low load in thermal power units. Background Technology

[0002] The stable operation of SCR flue gas denitrification systems in thermal power plants is a primary means of achieving nitrogen oxide emission reduction targets and has been widely adopted. In thermal power units, the regenerative extraction steam pressure is basically proportional to the unit load. As the unit load decreases, the boiler feedwater temperature inevitably decreases as well, causing a corresponding decrease in the flue gas temperature at the economizer outlet. When the flue gas temperature is too low, it leads to a reduction in catalyst activity. Simultaneously, ammonia and sulfur trioxide will generate ammonium bisulfate under low-temperature flue gas conditions, which adheres to the denitrification catalyst and air preheater, adsorbing dust and causing blockage of the denitrification catalyst and air preheater. The pressure differential in the denitrification reactor and air preheater slowly increases, thereby reducing the output of the induced draft fan and affecting the unit output. Therefore, controlling the inlet flue gas temperature of the denitrification reactor is crucial.

[0003] As the proportion of new energy in the power grid gradually increases, the demand for peak-shaving power sources also gradually increases. Compared with new energy power sources, coal power has better peak-shaving performance. In the next few years, thermal power units, especially coal power units, will continue to operate at low loads or perform deep peak shaving. Therefore, how to increase feedwater temperature and take into account energy conservation and consumption reduction under low load conditions has become the goal of thermal power units.

[0004] When the steam turbine is under low load, the amount of steam required decreases. Since the steam turbine's flow area is not adjustable, it is often necessary to reduce the steam pressure to decrease the steam density in order to ensure that the steam volume flow rate matches the steam turbine's flow area. It can be seen that the steam turbine inlet pressure is approximately proportional to the unit load. The lower the load, the lower the required inlet pressure. At this time, the boiler will still continue to provide steam at a higher pressure. There is a certain pressure difference between the main steam between the boiler and the steam turbine that can be utilized. Summary of the Invention

[0005] This invention provides a bypass regenerative turbine system for low-load feedwater heating in thermal power units to solve the problems mentioned in the background art.

[0006] This invention provides the following technical solution: a bypass regenerative turbine system for low-load feedwater heating in thermal power units, comprising the following modules: boiler, main steam valve, low-load bypass regulating valve, main regulating valve, bypass regenerative turbine, and feedwater temperature regulator;

[0007] The main steam outlet pipe of the boiler is connected to the main steam valve, the outlet flange of the main steam valve is connected to the inlet of the main regulating valve, part of the steam after the main steam valve enters the bypass regenerative turbine through the low load bypass regulating valve, and the feedwater temperature regulator detects the feedwater temperature entering the boiler in real time.

[0008] Boiler: Converts the chemical energy of fuel into thermal energy, thereby producing high-temperature and high-pressure steam or hot water, and supplies the steam to the main steam valve;

[0009] Main steam valve: controls the on / off of the main steam discharged from the boiler, regulates the flow rate, and cuts off the steam supply in emergencies to ensure system safety. It supplies the main steam to the main regulating valve and supplies a portion of the steam to the low-load bypass regulating valve.

[0010] Low-load bypass regulating valve: ensures stable operation of the steam power system under low-load, start-up, and shutdown conditions, and supplies steam to the bypass regenerating turbine;

[0011] Main regulating valve: By dynamically adjusting fluid parameters, it ensures that the equipment operates in a stable and efficient state, connects to the main steam valve to supply the main steam, and supplies the steam to the conventional steam turbine unit;

[0012] Bypass regenerative turbine: Optimizes the regenerative process, balances the steam distribution of the system and improves energy utilization efficiency. It uses the bypass steam supplied by the low-load bypass regulating valve to do work and realize energy recovery. The exhaust steam of the bypass regenerative turbine enters the feedwater temperature regulator to heat the boiler water.

[0013] Feedwater temperature regulator: precisely controls the boiler feedwater temperature to remain stable at the set value;

[0014] The low-load bypass regulating valve includes a three-way pipe with a main channel at its center. The two ports of the main channel are connected to the main steam valve and the main regulating valve respectively via pipelines. A bypass channel is opened at the end of the three-way pipe away from the main channel. An auxiliary pipe is fixedly sleeved on the side wall of the bypass channel. A piston is slidably sleeved on the inner wall of the auxiliary pipe. A baffle is rotatably sleeved on the inner wall of the bypass channel. A sealing ring is fixedly sleeved on the outer edge of the baffle, and the outer edge of the sealing ring is in close contact with the inner wall of the bypass channel. A spring is fixedly connected to the side of the piston, and the end of the spring away from the piston is fixedly connected to the inner wall of the auxiliary pipe.

[0015] A rotating frame is fixedly mounted on the bottom of the baffle. The outer edge of the rotating frame is rotatably sleeved with the inner wall of the auxiliary tube. A baffle is fixedly sleeved on the outer edge of the rotating frame. A positioning wheel is fixedly mounted on the bottom of the rotating frame. A tension spring is fixedly sleeved on the outer edge of the positioning wheel, and the end of the tension spring away from the positioning wheel is fixedly connected to the inner wall of the auxiliary tube. A limit groove is opened on the outer edge of the rotating frame. A rotating groove is opened on the inner wall of the auxiliary tube, and the inner wall of the rotating groove is rotatably sleeved with the outer edge of the baffle.

[0016] As a preferred embodiment of the present invention, a connecting pipe is fixedly sleeved on the inner wall of the auxiliary tube near both sides. A first magnet plate is fixedly mounted on the inner wall of the baffle, and the outer edge of the first magnet plate is rotatably connected to the inner wall of the rotating groove. A second magnet plate is fixedly mounted on the inner wall of the auxiliary tube. The adjacent sides of the first and second magnet plates are attracted to each other. A Hall sensor is fixedly mounted on the side of the second magnet plate, and the Hall sensor is electrically connected to the second magnet plate. A solenoid valve exhaust pipe is fixedly mounted on the inner wall of the auxiliary tube, and the solenoid valve exhaust pipe is electrically connected to the Hall sensor.

[0017] In a preferred embodiment of the present invention, a fixing ring is fixedly sleeved on the outer edge of the three-way pipe, an auxiliary ring is fixedly fitted on the side of the fixing ring, a connecting pipe is fixedly fitted on the inner wall of the auxiliary ring, a collar is fixedly sleeved on the outer edge of the connecting pipe, a venting pipe is fixedly sleeved on the inner wall of the collar, and the outer edge of the venting pipe is fixedly sleeved with the inner wall of the fixing ring, a bottom ring is fixedly sleeved on the inner wall of the connecting pipe, a pressure ring is fixedly fitted on the bottom of the bottom ring, a rubber pad is fixedly fitted on the bottom of the pressure ring, and the bottom of the rubber pad is fixedly sleeved with the outer edge of the three-way pipe.

[0018] As a preferred embodiment of the present invention, a circular plate is slidably sleeved on the inner wall of the connecting pipe, a connecting rod is fixedly sleeved on the inner wall of the circular plate, a magnet is fixedly mounted on the bottom of the connecting rod, a coil is fixedly sleeved on the inner wall of the bottom ring, and the inner wall of the coil is slidably sleeved with the outer edge of the magnet, a tension spring is fixedly connected to the bottom of the circular plate, and the bottom of the tension spring is fixedly connected to the top of the bottom ring.

[0019] As a preferred embodiment of the present invention, a tension spring three is fixedly connected to the inner wall of the fixing ring, and a positioning protrusion is fixedly connected to the end of the tension spring three away from the fixing ring. The shape and size of the convex surface of the positioning protrusion are adapted to the shape and size of the inner wall of the limiting groove. The limiting rod is slidably sleeved on the inner wall of the fixing ring near the top, and the bottom of the limiting rod passes through the inner wall of the tee pipe and is tightly attached to the outer edge of the sealing ring.

[0020] As a preferred embodiment of the present invention, the bypass regenerative turbine is used for boiler feedwater temperature regulation. The bypass regenerative turbine adopts an axial flow or centripetal structure. A speed controller for detecting the rotation speed is provided at the rotating shaft of the bypass regenerative turbine, and the signal output terminal of the speed controller is electrically connected to the drive mechanism of the steam regulating valve of the bypass regenerative turbine through a cable.

[0021] In a preferred embodiment of the present invention, when the boiler load is reduced to the start-stop point, the bypass regenerating turbine diverts a portion of the main steam from the main regulating valve. The low-load bypass regulating valve introduces the steam into the bypass regenerating turbine for expansion and work. The output shaft of the bypass regenerating turbine is coaxially connected to the input shaft of the variable frequency generator via a rigid coupling. The end of the variable frequency generator away from the bypass regenerating turbine is electrically connected to the input terminal of a high-power rectifier-inverter via a high-voltage cable. The high-power rectifier-inverter converts non-fixed-frequency electrical energy into electrical energy with the same frequency as the power grid. After being transformed by a transformer, the energy is connected to the plant power system. The exhaust steam from the bypass regenerating turbine enters the feedwater temperature regulator, thereby using the gas to increase the boiler feedwater temperature.

[0022] As a preferred embodiment of the present invention, the outlet end of the main regulating valve away from the main steam valve is connected to the steam inlet of the conventional steam turbine unit through a main steam pipeline. The conventional steam turbine unit achieves energy conversion by driving a conventional generator set to supply energy to the auxiliary system. The exhaust steam outlet of the conventional steam turbine unit is connected to the inlet of the condenser through an exhaust steam pipeline. The condensate outlet of the condenser and the inlet of the shaft seal heater are connected sequentially through a condensate pipeline, with a condensate pump as an intermediate power component. After the condensate absorbs the heat of the shaft seal leakage steam through the shaft seal heater, the outlet of the shaft seal heater is connected to the inlet of the low-pressure heater located downstream, and the condensate is further heated by the low-pressure heater.

[0023] The outlet of the low-pressure heater is connected to the inlet of the deaerator via a low-pressure heated water pipe. The outlet of the deaerator is pressurized by a feed water pump and connected to the inlet of the high-pressure heater via a pressurized water pipe. After the high-pressure heater heats the water to a predetermined temperature, its outlet pipe is connected to the feed water temperature regulator. A second bypass regenerative turbine is arranged in parallel on the side of the bypass regenerative turbine, and the two form parallel bypass regenerative paths.

[0024] The present invention has the following beneficial effects:

[0025] 1. This bypass regenerative turbine system for low-load feedwater heating in thermal power units is an improvement on the existing steam turbine steam cycle power generation system. It is equipped with a bypass regenerative turbine specifically for boiler feedwater temperature regulation. By changing the opening of the bypass regulating valve and the turbine speed, the turbine exhaust pressure and exhaust steam flow are controlled, so that the boiler feedwater temperature is always within the optimal temperature range. In addition, it can utilize some of the non-throttling main steam during low-load constant pressure operation to increase the steam work capacity, reduce the unit's coal consumption rate, and improve its overall energy saving level.

[0026] 2. This bypass regenerative turbine system for low-load feedwater heating in thermal power units utilizes a combination of a three-way pipe and an auxiliary pipe. It supplies main steam through the main channel and uses the main steam to drive a piston via the auxiliary pipe. When the piston moves to the point where the connecting pipe connects to the main channel via the auxiliary pipe, gas flows through the connecting pipe into the rotating slot, thereby driving the baffle to rotate. This, in turn, causes the auxiliary baffle to attract magnet plate one and magnet plate two, which in turn opens the solenoid valve exhaust pipe. The baffle then drives the baffle plate to rotate, allowing auxiliary gas to supply steam to the bypass regenerative turbine through the bypass channel. The auxiliary device then automatically starts and stops based on the steam pressure.

[0027] 3. This bypass regenerative turbine system for low-load feedwater heating in thermal power units supplies air to the auxiliary ring via a solenoid valve tube, thereby pushing the circular plate downwards. The circular plate, through a connecting rod, drives the magnet to slide on the inner wall of the coil. The electromagnetic damping generated by the coil and the magnet assists in reducing vibration in the three-way pipe, preventing valve vibration caused by flow fluctuations due to turbulent flow field, thus ensuring stable operation of the device. When the circular plate moves downwards, air is supplied to the inside of the fixed ring through the air guide pipe, thereby assisting the downward movement of the limiting rod. The limiting rod then compresses and limits the sealing ring, and the convex surface of the positioning protrusion aligns with the inner wall of the limiting groove, further ensuring the stable limiting of the baffle. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the bypass regenerative turbine system for low-load feedwater heating of thermal power units according to the present invention.

[0029] Figure 2 This is a schematic diagram of another implementation mode of the bypass regenerative turbine system for low-load feedwater heating of thermal power units according to the present invention.

[0030] Figure 3 This is a schematic diagram of the low-load bypass regulating valve structure of the present invention;

[0031] Figure 4 This is a schematic diagram of the cross-sectional structure of the tee pipe of the present invention;

[0032] Figure 5 This is a schematic diagram of the side cross-section of the tee pipe of the present invention;

[0033] Figure 6 This is a schematic diagram of the auxiliary ring cross-sectional structure of the present invention;

[0034] Figure 7 For the present invention Figure 6 Enlarged structural diagram at point A in the middle;

[0035] Figure 8 This is a schematic cross-sectional view of the blade structure of the present invention;

[0036] Figure 9 For the present invention Figure 8 Enlarged structural diagram at point B;

[0037] Figure 10 This is a schematic diagram of the piston structure of the present invention;

[0038] Figure 11 This is a schematic diagram of the baffle structure of the present invention;

[0039] Figure 12 This is a schematic diagram of the connecting pipe structure of the present invention;

[0040] Figure 13 This is a schematic diagram of the positioning protrusion structure of the present invention.

[0041] In the diagram: 1. Boiler; 2. Main steam valve; 3. Low-load bypass regulating valve; 4. Main regulating valve; 5. Bypass regenerative turbine; 6. Variable frequency generator; 7. High-power rectifier-inverter; 8. Transformer; 9. Plant auxiliary power system; 10. Speed ​​controller; 11. Feedwater temperature regulator; 12. Conventional steam turbine unit; 13. Conventional generator unit; 14. Condenser; 15. Condensate pump; 16. Shaft seal heater; 17. Low-pressure heater; 18. Deaerator; 19. Feedwater pump; 20. High-pressure heater; 21. Second bypass regenerative turbine;

[0042] 301. Tee pipe; 302. Main channel; 303. Bypass channel; 304. Auxiliary pipe; 305. Spring; 306. Piston; 307. Baffle; 308. Rotating groove; 309. Magnet plate one; 310. Connecting pipe; 311. Solenoid valve exhaust pipe; 312. Magnet plate two; 313. Rotating frame; 314. Limiting groove; 315. Baffle; 316. Sealing ring; 317. Solid 318. Fixed ring; 319. Auxiliary ring; 320. Connecting pipe; 321. Collar; 322. Bottom ring; 323. Coil; 324. Magnet piece; 325. Connecting rod; 326. Circular plate; 327. Air guide pipe; 328. Tension spring one; 329. Positioning wheel; 330. Tension spring two; 331. Pressure ring; 332. Rubber pad; 333. Positioning protrusion; 334. Tension spring three; 335. Limiting rod. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] Please see Figure 1 - Figure 13A bypass regenerative turbine system for low-load feedwater heating in thermal power units includes the following modules: boiler 1, main steam valve 2, low-load bypass regulating valve 3, main regulating valve 4, bypass regenerative turbine 5, and feedwater temperature regulator 11.

[0046] The main steam outlet pipe of boiler 1 is connected to the main steam valve 2. The outlet flange of the main steam valve 2 is connected to the inlet of the main regulating valve 4. Part of the steam after the main steam valve 2 enters the bypass regenerating turbine 5 through the low-load bypass regulating valve 3. The feedwater temperature regulator 11 detects the feedwater temperature entering boiler 1 in real time.

[0047] Boiler 1: Converts the chemical energy of fuel into thermal energy, thereby generating high-temperature and high-pressure steam or hot water, and supplies the steam to the main steam valve 2;

[0048] Main steam valve 2: controls the on / off of the main steam discharged from boiler 1, regulates the flow rate, and cuts off the steam supply in an emergency to ensure system safety. It supplies the main steam to the main regulating valve 4 and supplies part of the steam to the low-load bypass regulating valve 3.

[0049] Low-load bypass regulating valve 3: ensures stable operation of the steam power system under low-load, start-up, and shutdown conditions, and supplies steam to the bypass regenerating turbine 5;

[0050] Main regulating valve 4: By dynamically adjusting fluid parameters, it ensures that the equipment operates in a stable and efficient state, connects to the main steam supplied by the main steam valve 2, and supplies the steam to the conventional steam turbine unit 12;

[0051] Bypass regenerative turbine 5: Optimizes the regenerative process, balances the steam distribution of the system and improves energy utilization efficiency. It uses the bypass steam supplied by the low-load bypass regulating valve 3 to do work and realize energy recovery. The exhaust steam of the bypass regenerative turbine 5 enters the feedwater temperature regulator 11 to heat the water in boiler 1. The bypass regenerative turbine 5 is a steam turbine specially used for regulating the feedwater temperature of boiler 1. It can adopt an axial flow or centripetal structure and has adjustable speed and fast start-stop characteristics.

[0052] Feedwater temperature regulator 11: Precisely controls the feedwater temperature of boiler 1 to remain stable at the set value, optimizes the low coal consumption rate of the unit while maintaining the efficient operation of the flue gas denitrification device SCR of boiler 1, and determines the optimal feedwater temperature range of boiler 1 through thermal performance tests or system simulation calculations.

[0053] In a preferred embodiment, the low-load bypass regulating valve 3 includes a three-way pipe 301. A main channel 302 is located at the center of the three-way pipe 301, and the two ports of the main channel 302 are respectively connected to the main steam valve 2 and the main regulating valve 4 via pipelines. A bypass channel 303 is opened at the end of the three-way pipe 301 away from the main channel 302. An auxiliary pipe 304 is fixedly sleeved on the side wall of the bypass channel 303. A piston 306 is slidably sleeved on the inner wall of the auxiliary pipe 304. A baffle 315 is rotatably sleeved on the inner wall of the bypass channel 303. A sealing ring 316 is fixedly sleeved on the outer edge of the baffle 315. The outer edge of the piston 306 is in close contact with the inner wall of the bypass channel 303. A spring 305 is fixedly connected to the side of the piston 306, and the end of the spring 305 away from the piston 306 is fixedly connected to the inner wall of the auxiliary pipe 304. Through the cooperation of the spring 305 and the piston 306, the outer edge of the piston 306 is used to assist in intercepting the outer edge of the connecting pipe 310. When the piston 306 moves in the pipe, the resistance is mainly the elastic force of the spring 305. Through the cooperation of the baffle 315 and the sealing ring 316, the baffle 315 drives the sealing ring 316 to rotate, thereby assisting the connection between the main channel 302 and the bypass channel 303.

[0054] In a preferred embodiment, a rotating frame 313 is fixedly mounted on the bottom of the baffle 315. The outer edge of the rotating frame 313 is rotatably sleeved with the inner wall of the auxiliary pipe 304. A baffle 307 is fixedly sleeved on the outer edge of the rotating frame 313. A positioning wheel 328 is fixedly mounted on the bottom of the rotating frame 313. A tension spring 329 is fixedly sleeved on the outer edge of the positioning wheel 328. The end of the tension spring 329 away from the positioning wheel 328 is fixedly connected to the inner wall of the auxiliary pipe 304. A limit groove 314 is formed on the outer edge of the rotating frame 313. A rotating groove 308 is formed on the inner wall of the auxiliary pipe 304. The inner wall of the rotating groove 308 is rotatably sleeved with the outer edge of the baffle 307. The tension spring 329 is connected to the positioning wheel 328. Thus, when the steam is depressurized, the tension spring 329 drives the positioning wheel 328 to reset. Then, the positioning wheel 328 drives the baffle 315 to reset through the baffle 307.

[0055] In a preferred embodiment, a connecting pipe 310 is fixedly sleeved on the inner wall of the auxiliary pipe 304 near both sides. A first magnet plate 309 is fixedly mounted on the inner wall of the baffle 307, and the outer edge of the first magnet plate 309 is rotatably connected to the inner wall of the rotating groove 308. A second magnet plate 312 is fixedly mounted on the inner wall of the auxiliary pipe 304. The adjacent sides of the first magnet plate 309 and the second magnet plate 312 are attracted to each other. A Hall sensor is fixedly mounted on the side of the second magnet plate 312, and the Hall sensor is electrically connected to the second magnet plate 312. A solenoid valve exhaust pipe 311 is fixedly mounted on the inner wall of the auxiliary pipe 304, and the solenoid valve exhaust pipe 311 is electrically connected to the Hall sensor. Through the cooperation of the first magnet plate 309 and the second magnet plate 312, when the first magnet plate 309 and the second magnet plate 312 are attracted to each other, the Hall sensor controls the solenoid valve exhaust pipe 311 to open, and then the auxiliary gas is discharged to the outside through the solenoid valve exhaust pipe 311.

[0056] In a preferred embodiment, a fixing ring 317 is fixedly sleeved on the outer edge of the three-way pipe 301, an auxiliary ring 318 is fixedly fitted on the side of the fixing ring 317, a connecting pipe 319 is fixedly fitted on the inner wall of the auxiliary ring 318, a collar 320 is fixedly sleeved on the outer edge of the connecting pipe 319, an air guide pipe 326 is fixedly sleeved on the inner wall of the collar 320, and the outer edge of the air guide pipe 326 is fixedly sleeved with the inner wall of the fixing ring 317. A bottom ring 321 is fixedly sleeved on the inner wall of the connecting pipe 319, a pressure ring 330 is fixedly fitted on the bottom of the bottom ring 321, and a rubber pad 331 is fixedly fitted on the bottom of the pressure ring 330, and the bottom of the rubber pad 331 is fixedly sleeved with the outer edge of the three-way pipe 301. Through the cooperation of the pressure ring 330 and the rubber pad 331, the three-way pipe 301 is assisted in damping vibration when air is introduced into the bypass channel 303.

[0057] In a preferred embodiment, a circular plate 325 is slidably sleeved on the inner wall of the connecting pipe 319, and a connecting rod 324 is fixedly sleeved on the inner wall of the circular plate 325. A magnet 323 is fixedly mounted on the bottom of the connecting rod 324. A coil 322 is fixedly sleeved on the inner wall of the bottom ring 321, and the inner wall of the coil 322 is slidably sleeved with the outer edge of the magnet 323. A tension spring 327 is fixedly connected to the bottom of the circular plate 325, and the bottom of the tension spring 327 is fixedly connected to the top of the bottom ring 321. Through the cooperation of the coil 322 and the magnet 323, the magnet 323 is used to... When the wall slides, the coil 322 generates electromagnetic damping on the magnet 323, thereby assisting in shock absorption of the three-way pipe 301. As the magnet 323 and the connecting rod 324 move with the circular plate 325, the gas inside the auxiliary ring 318 pushes the circular plate 325 downward, thereby adapting and adjusting according to the amount of steam in the device to ensure stable operation. When the circular plate 325 moves downward to the point where the gas inside the auxiliary ring 318 is supplied to the fixed ring 317 through the connecting pipe 319, the collar 320, and the air guide pipe 326, the auxiliary positioning protrusion 332 and the limiting groove 314 engage, further ensuring the stability of the baffle 315.

[0058] In a preferred embodiment, a tension spring 333 is fixedly connected to the inner wall of the fixing ring 317, and a positioning protrusion 332 is fixedly connected to the end of the tension spring 333 away from the fixing ring 317. The shape and size of the convex surface of the positioning protrusion 332 are adapted to the shape and size of the inner wall of the limiting groove 314. A limiting rod 334 is slidably sleeved on the inner wall of the fixing ring 317 near the top, and the bottom of the limiting rod 334 passes through the inner wall of the three-way pipe 301 and is in close contact with the outer edge of the sealing ring 316. Through the cooperation of the positioning protrusion 332 and the limiting groove 314, the rotating frame 313 is assisted in limiting the position when the convex surface of the positioning protrusion 332 is aligned with the inner wall of the limiting groove 314.

[0059] In a preferred embodiment, the bypass regenerative turbine 5 is used for regulating the feedwater temperature of the boiler 1. The bypass regenerative turbine 5 adopts an axial flow or centripetal structure. A speed controller 10 for detecting the rotation speed is provided at the rotating shaft of the bypass regenerative turbine 5, and the signal output terminal of the speed controller 10 is electrically connected to the drive mechanism of the steam regulating valve of the bypass regenerative turbine 5 through a cable.

[0060] In a preferred embodiment, when the load of boiler 1 decreases to the start-stop point, the bypass regenerating turbine 5 diverts part of the main steam from the main regulating valve 4. The low-load bypass regulating valve 3 introduces steam into the bypass regenerating turbine 5 for expansion and work. The output shaft of the bypass regenerating turbine 5 is coaxially connected to the input shaft of the variable frequency generator 6 through a rigid coupling. The end of the variable frequency generator 6 away from the bypass regenerating turbine 5 is electrically connected to the input terminal of the high-power rectifier-inverter device 7 through a high-voltage cable. The high-power rectifier-inverter device 7 converts non-fixed-frequency electrical energy into electrical energy with the same frequency as the power grid. After being transformed by the transformer 8, it is connected to the plant power system 9. The exhaust steam of the bypass regenerating turbine 5 enters the feedwater temperature regulator 11, thereby using the gas to increase the feedwater temperature of boiler 1.

[0061] In a preferred embodiment, the outlet end of the main regulating valve 4, which is away from the main steam valve 2, is connected to the steam inlet of the conventional steam turbine unit 12 via a main steam pipeline. The conventional steam turbine unit 12 drives the conventional generator unit 13 to achieve energy conversion and supply energy to the auxiliary system. The exhaust steam outlet of the conventional steam turbine unit 12 is connected to the inlet of the condenser 14 via an exhaust steam pipeline. The condensate outlet of the condenser 14 is connected to the inlet of the shaft seal heater 16 via a condensate pump 15 as an intermediate power component. The condensate absorbs the heat of the shaft seal leakage steam after passing through the shaft seal heater 16. The outlet of the shaft seal heater 16 is connected to the inlet of the low-pressure heater 17 located downstream of it, and the condensate is further heated by the low-pressure heater 17.

[0062] The outlet of the low-pressure heater 17 is connected to the inlet of the deaerator 18 via a low-pressure heated water pipe. After the outlet of the deaerator 18 is pressurized by the feed water pump 19, it is connected to the inlet of the high-pressure heater 20 via a pressurized water pipe. After the high-pressure heater 20 heats the water to a predetermined temperature, its outlet pipe is connected to the feed water temperature regulator 11.

[0063] Working principle: When the load of boiler 1 is reduced to the start-stop point, the bypass reheat turbine 5 diverts part of the main steam from the main regulating valve 4.

[0064] The main steam is supplied through the main channel 302, and the main steam pushes the piston 306 to move through the auxiliary pipe 304 until the main channel 302 is connected to the rotating groove 308 through the auxiliary pipe 304 and the connecting pipe 310. Gas then flows through the connecting pipe 310 into the rotating groove 308, thereby driving the baffle 307 to rotate. The auxiliary baffle 307 then attracts the first magnet plate 309 and the second magnet plate 312, which in turn opens the solenoid valve exhaust pipe 311. This causes the baffle 307 to rotate the baffle plate 315, allowing auxiliary gas to supply steam to the bypass regenerating turbine 5 through the bypass channel 303. The auxiliary device then automatically starts and stops according to the steam pressure, supplying gas to the auxiliary ring 318 through the solenoid valve exhaust pipe 311, thereby pushing the circular plate 325 downwards. The circular plate 325 drives the magnet 323 to slide on the inner wall of the coil 322 via the connecting rod 324. The electromagnetic damping generated by the coil 322 and the magnet 323 assists the three-way pipe 301 in reducing vibration, avoiding valve vibration caused by flow fluctuations due to turbulent flow field, thus ensuring stable operation of the device. When the circular plate 325 moves down, air is supplied to the inside of the fixed ring 317 through the air guide pipe 326, thereby assisting the limit rod 334 to move down. The limit rod 334 then squeezes and limits the sealing ring 316. The convex surface of the positioning protrusion 332 connects with the inner wall of the limit groove 314, thereby further ensuring the stable limit of the baffle 315. This assists the low-load bypass regulating valve 3 to start and stop automatically, and avoids valve vibration caused by turbulent flow field, while further ensuring the stable limit of the baffle 315.

[0065] The bypass regenerative turbine 5 expands and performs work through the low-load bypass regulating valve 3. The bypass regenerative turbine 5 directly drives the variable frequency generator 6 to generate non-fixed-frequency electrical energy. Subsequently, the high-power rectifier-inverter device 7 converts the non-fixed-frequency electrical energy into electrical energy with the same frequency as the power grid. After being transformed by the transformer 8, it is connected to the plant power system 9. The exhaust steam from the bypass regenerative turbine 5 enters the feedwater temperature regulator 11 to increase the feedwater temperature of boiler 1, ensuring the normal operation of the flue gas denitrification device (SCR) of boiler 1 under low-load conditions and reducing the coal consumption of boiler 1. As the load will further decrease, the low-load bypass regulating valve 3 is gradually opened, and the speed of the bypass regenerative turbine 5 is gradually increased by the speed controller 10 to keep the feedwater temperature of boiler 1 within the set range.

[0066] When the load of boiler 1 increases and is not higher than the start-stop point, gradually close the low load bypass regulating valve 3 and gradually reduce the speed of bypass regenerating turbine 5 using speed controller 10 until the load of boiler 1 increases to the start-stop point. At this time, close the low load bypass regulating valve 3, and the bypass regenerating turbine 5 stops and is in heat preservation state, waiting for the next start-up.

[0067] An improvement is made to the existing steam turbine steam cycle power generation system by setting up a bypass regenerative turbine 5 specifically for regulating the feedwater temperature of boiler 1. By changing the opening of the bypass regulating valve and the turbine speed, the turbine exhaust pressure and exhaust steam flow are controlled, so that the feedwater temperature of boiler 1 is always within the optimal temperature range. Furthermore, some of the non-throttling main steam can be used during low-load constant pressure operation to increase the steam work capacity, reduce the unit's coal consumption rate, and improve its overall energy-saving level.

[0068] Example 2

[0069] A second bypass regenerative turbine 21 is installed on the side of the bypass regenerative turbine 5. The bypass regenerative turbine 5 and the second bypass regenerative turbine 21 are connected in series. After the bypass regenerative turbine 5 extracts steam, it is introduced into the feedwater temperature regulator 11. After the second bypass regenerative turbine 21 extracts steam, it is introduced into the high-pressure heater 20. After the bypass regenerative turbine 5 and the second bypass regenerative turbine 21 extract steam, they are mixed and exchanged with the condensate twice, which further increases the temperature of the boiler 1 inlet water, thereby improving the unit's circulation efficiency and reducing coal consumption.

[0070] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bypass regenerative turbine system for low-load feedwater heating in thermal power units, characterized in that, The following modules are included: boiler (1), main steam valve (2), low load bypass regulating valve (3), main regulating valve (4), bypass regenerating turbine (5), and feedwater temperature regulator (11). The main steam outlet pipe of the boiler (1) is connected to the main steam valve (2), the outlet flange of the main steam valve (2) is connected to the inlet of the main regulating valve (4), and part of the steam after the main steam valve (2) enters the bypass regenerating turbine (5) through the low load bypass regulating valve (3). The feedwater temperature regulator (11) detects the feedwater temperature entering the boiler (1) in real time. Boiler (1): converts the chemical energy of fuel into thermal energy, thereby generating high-temperature and high-pressure steam or hot water, and supplies the steam to the main steam valve (2). Main steam valve (2): controls the on / off of the main steam discharged from the boiler (1), regulates the flow rate, and cuts off the steam supply in an emergency to ensure system safety. It supplies the main steam to the main regulating valve (4) and supplies part of the steam to the low-load bypass regulating valve (3). Low-load bypass regulating valve (3): ensures stable operation of the steam power system under low-load, start-up and shutdown conditions, and supplies steam to the bypass regenerating turbine (5). Main regulating valve (4): By dynamically adjusting fluid parameters, it ensures that the equipment operates in a stable and efficient state, connects to the main steam supplied by the main steam valve (2), and supplies the steam to the conventional steam turbine unit (12). Bypass regenerating turbine (5): Optimizes the regenerating process, balances the steam distribution of the system and improves the energy utilization efficiency. It uses the bypass steam supplied by the low-load bypass regulating valve (3) to do work and realize energy recovery. The exhaust steam of the bypass regenerating turbine (5) enters the feedwater temperature regulator (11) to heat the water in the boiler (1). Feedwater temperature regulator (11): precisely controls the feedwater temperature of the boiler (1) to remain stable at the set value; The low-load bypass regulating valve (3) includes a three-way pipe (301), with a main channel (302) at its center. The two ports of the main channel (302) are connected to the main steam valve (2) and the main regulating valve (4) respectively via pipelines. A bypass channel (303) is provided at the end of the three-way pipe (301) away from the main channel (302). An auxiliary pipe (304) is fixedly sleeved on the side wall of the bypass channel (303). A piston (306) is slidably sleeved on the inner wall of the bypass channel (303), and a baffle (315) is rotatably sleeved on the inner wall of the bypass channel (303). A sealing ring (316) is fixedly sleeved on the outer edge of the baffle (315), and the outer edge of the sealing ring (316) is in close contact with the inner wall of the bypass channel (303). A spring (305) is fixedly connected to the side of the piston (306), and the end of the spring (305) away from the piston (306) is fixedly connected to the inner wall of the auxiliary tube (304). The bottom of the baffle (315) is fixedly equipped with a rotating frame (313). The outer edge of the rotating frame (313) is rotatably sleeved with the inner wall of the auxiliary tube (304). The outer edge of the rotating frame (313) is fixedly sleeved with a baffle (307). The bottom of the rotating frame (313) is fixedly equipped with a positioning wheel (328). The outer edge of the positioning wheel (328) is fixedly sleeved with a tension spring (329). The end of the tension spring (329) away from the positioning wheel (328) is fixedly connected to the inner wall of the auxiliary tube (304). The outer edge of the rotating frame (313) is provided with a limiting groove (314). The inner wall of the auxiliary tube (304) is provided with a rotating groove (308). The inner wall of the rotating groove (308) is rotatably sleeved with the outer edge of the baffle (307).

2. A bypass regenerative turbine system for low-load feedwater heating in thermal power units according to claim 1, characterized in that: A connecting pipe (310) is fixedly sleeved on the inner wall of the auxiliary tube (304) near both sides. A first magnet plate (309) is fixedly installed on the inner wall of the baffle (307), and the outer edge of the first magnet plate (309) is rotatably connected to the inner wall of the rotating groove (308). A second magnet plate (312) is fixedly installed on the inner wall of the auxiliary tube (304). The adjacent sides of the first magnet plate (309) and the second magnet plate (312) are attracted to each other. A Hall sensor is fixedly installed on the side of the second magnet plate (312), and the Hall sensor is electrically connected to the second magnet plate (312). A solenoid valve exhaust pipe (311) is fixedly installed on the inner wall of the auxiliary tube (304), and the solenoid valve exhaust pipe (311) is electrically connected to the Hall sensor.

3. A bypass regenerative turbine system for low-load feedwater heating in thermal power units according to claim 1, characterized in that: A fixing ring (317) is fixedly sleeved on the outer edge of the three-way pipe (301). An auxiliary ring (318) is fixedly fitted on the side of the fixing ring (317). A connecting pipe (319) is fixedly fitted on the inner wall of the auxiliary ring (318). A collar (320) is fixedly sleeved on the outer edge of the connecting pipe (319). A duct pipe (326) is fixedly sleeved on the inner wall of the collar (320). The outer edge of the duct pipe (326) is fixedly sleeved with the inner wall of the fixing ring (317). A bottom ring (321) is fixedly sleeved on the inner wall of the connecting pipe (319). A pressure ring (330) is fixedly fitted on the bottom of the bottom ring (321). A rubber pad (331) is fixedly fitted on the bottom of the pressure ring (330). The bottom of the rubber pad (331) is fixedly sleeved with the outer edge of the three-way pipe (301).

4. A bypass regenerative turbine system for low-load feedwater heating in thermal power units according to claim 3, characterized in that: A circular plate (325) is slidably sleeved on the inner wall of the connecting pipe (319). A connecting rod (324) is fixedly sleeved on the inner wall of the circular plate (325). A magnet (323) is fixedly mounted on the bottom of the connecting rod (324). A coil (322) is fixedly sleeved on the inner wall of the bottom ring (321). The inner wall of the coil (322) is slidably sleeved with the outer edge of the magnet (323). A tension spring (327) is fixedly connected to the bottom of the circular plate (325). The bottom of the tension spring (327) is fixedly connected to the top of the bottom ring (321).

5. A bypass regenerative turbine system for low-load feedwater heating in thermal power units according to claim 4, characterized in that: The inner wall of the fixing ring (317) is fixedly connected to a tension spring three (333), and the end of the tension spring three (333) away from the fixing ring (317) is fixedly connected to a positioning protrusion (332). The shape and size of the convex surface of the positioning protrusion (332) are adapted to the shape and size of the inner wall of the limiting groove (314). The inner wall of the fixing ring (317) near the top is slidably sleeved with a limiting rod (334), and the bottom of the limiting rod (334) passes through the inner wall of the three-way pipe (301) and is tightly attached to the outer edge of the sealing ring (316).

6. A bypass regenerative turbine system for low-load feedwater heating in thermal power units according to claim 1, characterized in that: The bypass regenerative turbine (5) is used for boiler (1) feedwater temperature regulation. The bypass regenerative turbine (5) adopts an axial flow or centripetal structure. A speed controller (10) for detecting the rotation speed is provided at the rotating shaft of the bypass regenerative turbine (5). The signal output terminal of the speed controller (10) is electrically connected to the drive mechanism of the steam regulating valve of the bypass regenerative turbine (5) through a cable.

7. A bypass regenerative turbine system for low-load feedwater heating in thermal power units according to claim 1, characterized in that: When the load of the boiler (1) is reduced to the start-stop point, the bypass regenerating turbine (5) diverts part of the main steam from the main regulating valve (4). The low-load bypass regulating valve (3) introduces the steam into the bypass regenerating turbine (5) to expand and do work. The output shaft of the bypass regenerating turbine (5) is coaxially connected to the input shaft of the variable frequency generator (6) through a rigid coupling. The end of the variable frequency generator (6) away from the bypass regenerating turbine (5) is electrically connected to the input end of the high-power rectifier-inverter device (7) through a high-voltage cable. The high-power rectifier-inverter device (7) converts non-fixed frequency electrical energy into electrical energy with the same frequency as the power grid. After being transformed by the transformer (8), it is connected to the plant power system (9). The exhaust steam of the bypass regenerating turbine (5) enters the feedwater temperature regulator (11), thereby using the gas to increase the feedwater temperature of the boiler (1).

8. A bypass regenerative turbine system for low-load feedwater heating in thermal power units according to claim 1, characterized in that: The outlet end of the main regulating valve (4) away from the main steam valve (2) is connected to the steam inlet of the conventional steam turbine unit (12) through the main steam pipeline. The conventional steam turbine unit (12) realizes energy conversion by driving the conventional generator set (13) to supply energy to the auxiliary system. The exhaust steam outlet of the conventional steam turbine unit (12) is connected to the inlet of the condenser (14) through the exhaust steam pipeline. The condensate outlet of the condenser (14) and the inlet of the shaft seal heater (16) are connected in sequence through the condensate pipeline with the condensate pump (15) as the intermediate power component. After the condensate absorbs the heat of the shaft seal leakage steam through the shaft seal heater (16), the outlet of the shaft seal heater (16) is connected to the inlet of the low-pressure heater (17) located downstream of it. The condensate is further heated by the low-pressure heater (17). The outlet of the low-pressure heater (17) is connected to the inlet of the deaerator (18) via a low-pressure heated water pipe. The outlet of the deaerator (18) is pressurized by the feed water pump (19) and connected to the inlet of the high-pressure heater (20) via a pressurized water pipe. After the high-pressure heater (20) heats the water to a predetermined temperature, its outlet pipe is connected to the feed water temperature regulator (11). A second bypass reheat turbine (21) is arranged in parallel on the side of the bypass reheat turbine (5), and the two form parallel bypass reheat paths.

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