Feedwater protection system and feedwater protection method for thermal power generation

Abstract

The application discloses a feed water protection system for thermal power generation, which comprises a condenser and a high-pressure heater drain pump, the condenser is connected with a condensate pump through a first pipe, the condensate pump is connected with a low-pressure heater through a second pipe, the low-pressure heater is connected with a steam-driven feed water pump through a third pipe, the steam-driven feed water pump is connected with a high-pressure heater and a boiler in sequence through a fifth pipe; the high-pressure heater drain pump is connected with the steam-driven feed water pump through a fourth pipe, a condensate pump outlet pressure gauge is arranged on the second pipe, a feed water pump inlet pressure gauge is arranged on the third pipe, and the condensate pump outlet pressure gauge and the feed water pump inlet pressure gauge are signal-connected with a controller; the application further discloses a feed water protection method for thermal power generation, and solves the problem of unstable pressure in the feed water process when a deaerator is excluded in the feed water system in the prior art.

Description

Technical Field

[0001] This invention belongs to the technical field of water supply protection systems, specifically relating to water supply protection systems for thermal power generation, and also to the aforementioned water supply protection methods for thermal power generation. Background Technology

[0002] The feedwater system is the core component of the thermal cycle in a thermal power plant, and its reliability directly affects the safety, stability, and economy of the entire unit. This system typically consists of feedwater pump sets (feedwater pumps and booster pumps), deaerators, high-pressure heaters, feedwater pipelines, and valves, among other auxiliary equipment. Its main function is to pressurize deaerated water, heat it through the high-pressure heaters, and supply it to the boiler to improve the unit's cycle thermal efficiency. It also provides high-pressure bypass, superheater, and reheater desuperheating water. During normal operation, a failure in the feedwater system can lead to anything from limited load operation to complete unit shutdown. Therefore, the reliability of the feedwater system is unique and critical.

[0003] Traditional thermal power units typically include deaerators in their thermal systems. However, when boiler parameters are increased to supercritical and above, the boiler feedwater treatment method undergoes a qualitative change, and deaerators are no longer considered essential equipment. In recent years, with the continuous increase in the single-unit capacity of thermal power units in my country, some supercritical and above thermal power units have gradually adopted deaerator-free thermal systems to reduce engineering costs and system complexity. However, this technology is currently rarely used in large-scale thermal power projects in China, and it is unknown whether the system's reliability and economy are the same as those of conventional thermal power unit feedwater systems. Summary of the Invention

[0004] The purpose of this invention is to provide a water supply protection system for thermal power generation, which solves the problem of unstable pressure during the water supply process when there is no deaerator in the existing water supply system.

[0005] Another objective of this invention is to provide a water supply protection method for thermal power generation, which solves the problem in the prior art that the transformer protection value cannot be dynamically adjusted according to the actual situation, thus affecting the stable operation of the equipment.

[0006] The technical solution adopted in this invention is a feedwater protection system for thermal power generation, including a condenser and a high-pressure heater drain pump. The condenser is connected to a condensate pump through a first pipe, the condensate pump is connected to a low-pressure heater through a second pipe, the low-pressure heater is connected to a steam-driven feedwater pump through a third pipe, and the steam-driven feedwater pump is connected to a high-pressure heater and a boiler in sequence through a fifth pipe. The high-pressure heater drain pump is connected to the steam-driven feedwater pump through a fourth pipe. A condensate pump outlet pressure gauge is installed on the second pipe, and a feedwater pump inlet pressure gauge is installed on the third pipe. The condensate pump outlet pressure gauge and the feedwater pump inlet pressure gauge are connected to a controller.

[0007] The invention is further characterized by: There are three condensate pumps connected in parallel. Three first electric valves are installed near the condensate pumps on the first pipe. Each of the three first electric valves is set to correspond to one of the three condensate pumps. All three condensate pumps are variable frequency adjustable with a % capacity. Under normal use, two condensate pumps are in operation and one is on standby.

[0008] There are two high-pressure heater drain pumps, which are connected in parallel. Two second electric valves are installed near the high-pressure heater drain pumps on the fourth pipe, and each of the two second electric valves is set to correspond to one of the two high-pressure heater drain pumps. The two high-pressure heater drain pumps have a capacity of % and are normally used with one in operation and one on standby.

[0009] There are two steam-driven feedwater pumps connected in parallel. Each pump is equipped with a pre-selection trip button to control the pump to trip. Two third electric valves are installed on the fifth pipe between the feedwater pumps and the high-pressure heater, each corresponding to one of the two pumps. Both pumps are frequency-adjustable with a 100% capacity. Normal operation of both pumps is two-way.

[0010] The first, second, and third electric valves are all connected to the controller signal.

[0011] Another technical solution adopted in this invention is a water supply protection method for thermal power generation, which uses a water supply protection system for thermal power generation, and the specific steps are as follows: Step 1: Set the pressure protection value, operating value, and RB protection logic within the controller; Step 2: After powering on, collect the pressure information from the outlet pressure gauge of the condensate pump and the inlet pressure gauge of the feed water pump, and update the pressure protection value and the working value. Step 3: Based on the pressure information, the controller adjusts the opening and closing of the first electric valve, the second electric valve, and the third electric valve to complete the continuous water supply to the boiler.

[0012] Another feature of the technical solution of the present invention is that: Step 1: Determining the pressure protection value and operating value. Calculate the low inlet pressure protection value of the steam-driven feedwater pump based on its output. Use the low inlet pressure protection value as a benchmark to calculate the pressure protection value and operating value. Specifically: the operating value of the condensate pump is the low pressure protection value + 0.8 MPa; the allowable starting pressure protection value for the steam-driven feedwater pump inlet is the low pressure protection value + 0.3 MPa; and the starting value for the standby condensate pump when the steam-driven feedwater pump inlet pressure is low is the low pressure protection value + 0.4 MPa.

[0013] There are three pressure gauges at the inlet of the water pump. The effective pressure information of the water pump inlet pressure gauge is obtained by averaging the three collected pressure values.

[0014] The RB protection logic in step 1 includes the RB protection logic of the condensate pump, the RB protection logic of the steam-driven feedwater pump, and the RB protection logic of the high-pressure heater drain pump. Specifically, the RB protection logic of the condensate pump is as follows: when any condensate pump trips and the unit load is not less than 335MW, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump to trip. At this time, the third electric valve at the output end of the steam-driven feedwater pump controlled by the first trip button is closed. The RB protection logic of the steam-driven feedwater pump is as follows: when the feedwater pump inlet pressure gauge reaches the pressure protection value, after a delay of 10-15 seconds, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump to trip. At this time, the third electric valve at the output end of the steam-driven feedwater pump is closed. If the feedwater pump inlet pressure gauge is at the pressure protection value after a delay of 5 seconds, the other steam-driven feedwater pump is tripped. At this time, both third electric valves are closed. The RB protection logic of the high-pressure heater condensate pump is as follows: when both high-pressure heater condensate pumps trip and the unit meets the requirement of not less than 495MW, the standby condensate pump is started after a 2s delay. At this time, the first electric valve corresponding to the standby condensate pump is opened. After a 3s delay, the steam-driven feedwater pump controlled by one of the first trip buttons is triggered to trip. At this time, the third electric valve corresponding to the steam-driven feedwater pump is closed.

[0015] The beneficial effects of this invention are: By installing pressure gauges at the condensate pump outlet and feedwater pump inlet and connecting them to the controller signal, real-time and accurate monitoring of pressure at key nodes in the feedwater system is achieved. This enables timely detection of pressure anomalies and effectively prevents equipment damage or system failures caused by pressure fluctuations. The controller incorporates built-in pressure protection values, operating values, and RB protection logic. Based on the collected pressure information, it automatically adjusts the switching of each electric valve, significantly improving the system's automation level and response speed, ensuring a continuous and stable feedwater supply to the boiler even under changing operating conditions. The high-pressure heater drain pump is connected to the steam-driven feedwater pump via a fourth pipe, complementing the main feedwater circuit. This design enhances the system's redundancy and backup capabilities, allowing for rapid switching or replenishment when the main circuit experiences insufficient pressure, greatly improving the reliability and safety of the entire feedwater system. Overall, this system organically integrates monitoring, control, and protection, with a close correlation between technical solutions and effects, effectively improving the stability and economy of thermal power generating unit operation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the water supply protection system for thermal power generation according to the present invention; In the diagram, 1. Condenser, 2. High-pressure heater drain pump, 3. First pipe, 4. Condensate pump, 5. Second pipe, 6. Low-pressure heater, 7. Third pipe, 8. Steam-driven feedwater pump, 9. Boiler, 10. Condensate pump outlet pressure gauge, 11. Feedwater pump inlet pressure gauge, 12. Controller, 13. First electric valve, 14. Fourth pipe, 15. Second electric valve, 16. Third electric valve, 17. High-pressure heater, 18. Fifth pipe. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0019] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0020] There are two high-pressure heater drain pumps 2, which are connected in parallel. Two second electric valves 15 are installed near the high-pressure heater drain pumps 2 on the fourth pipe 14. The two second electric valves 15 are respectively set with the two high-pressure heater drain pumps 2. The two high-pressure heater drain pumps 2 are at 100% capacity. The two high-pressure heater drain pumps 2 are normally used with one in use and one on standby.

[0021] There are two steam-driven feedwater pumps 8, which are connected in parallel. Each of the two steam-driven feedwater pumps 8 is equipped with a pre-selection first trip button, which is used to control the steam-driven feedwater pump 8 to trip. Two third electric valves 16 are installed on the fifth pipe 18 located between the steam-driven feedwater pump 8 and the high-pressure heater 17. Each of the two third electric valves 16 is set with a corresponding function to the two steam-driven feedwater pumps 8. Both steam-driven feedwater pumps 8 are frequency-adjustable with a capacity of 50%. The two steam-driven feedwater pumps 8 are normally operated in dual-operation mode.

[0022] The first electric valve 13, the second electric valve 15, and the third electric valve 16 are all connected to the controller 12 via signal transmission. Figure 1 As shown.

[0023] The water supply protection method for thermal power generation adopts the water supply protection system for thermal power generation, and the specific steps are as follows: Step 1: Set the pressure protection value, operating value, and RB protection logic within controller 12; Step 2: After powering on, collect the pressure information from the condensate pump outlet pressure gauge 10 and the feed water pump inlet pressure gauge 11, and update the pressure protection value and working value. Step 3: Based on the pressure information, the controller 12 adjusts the opening and closing of the first electric valve 13, the second electric valve 15 and the third electric valve 16 to complete the continuous water supply to the boiler.

[0024] Step 1, the process of determining the pressure protection value and the working value, is as follows: Calculate the low inlet pressure protection value of the steam-driven feedwater pump 8 based on its output; use the low inlet pressure protection value as a benchmark to calculate the pressure protection value and the working value; specifically: the working value of the condensate pump 4 is the low pressure protection value + 0.8 MPa, the allowable starting pressure protection value of the steam-driven feedwater pump 8 inlet is the low pressure protection value + 0.3 MPa, and the starting value of the standby condensate pump when the inlet pressure of the steam-driven feedwater pump 8 is low is the low pressure protection value + 0.4 MPa.

[0025] There are three pressure gauges 11 at the inlet of the water pump. The effective pressure information of the pressure gauges 11 is obtained by averaging the three collected pressure values.

[0026] In step 1, the RB protection logic includes the RB protection logic of condensate pump 4, the RB protection logic of steam-driven feedwater pump 8, and the RB protection logic of high-pressure heater drain pump 2. Specifically, the RB protection logic of condensate pump 4 is as follows: when any condensate pump 4 trips and the unit load is not less than 335MW, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 controlled by the first trip button is closed. The RB protection logic of the steam-driven feedwater pump 8 is as follows: When the feedwater pump inlet pressure gauge 11 reaches the pressure protection value, after a delay of 10-15 seconds, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 is closed. If the feedwater pump inlet pressure gauge 11 is at the pressure protection value after a delay of 5 seconds, the other steam-driven feedwater pump 8 is tripped. At this time, both third electric valves 16 are closed. The RB protection logic of the high-pressure heater condensate pump 2 is as follows: when both high-pressure heater condensate pumps 2 trip and the unit meets the requirement of not less than 495MW, the standby condensate pump 4 is started after a 2s delay. At this time, the first electric valve 13 corresponding to the standby condensate pump 4 is opened. After a 3s delay, the steam-driven feedwater pump 8 controlled by one of the first trip buttons is triggered to trip. At this time, the third electric valve 16 corresponding to the steam-driven feedwater pump 8 is closed.

[0027] Key equipment such as condensate pump 4, high-pressure heater drain pump 2, and steam-driven feedwater pump 8 all employ parallel backup designs. The three 50% capacity condensate pumps 4 operate in a "two-in-one-out" mode, the two 100% capacity high-pressure heater drain pumps 2 operate in a "one-in-one-out" mode, and the two 50% capacity steam-driven feedwater pumps 8 operate in a "two-in-one" mode. This ensures that in the event of an unexpected trip by any operating pump, the standby pump can be immediately and seamlessly activated to maintain stable feedwater flow and prevent boiler water outages due to single-point failures. This multi-layered equipment redundancy not only provides the system with extremely high availability but also allows for flexible scheduling during equipment maintenance, laying a solid physical foundation for the long-term stable operation of the unit.

[0028] The controller 12 collects pressure information from the outlet of condensate pump 4 and the inlet of steam-driven feedwater pump 8, and dynamically updates the pressure protection and operating values ​​accordingly. The start-up allowable value for the steam-driven feedwater pump 8 inlet is "low pressure protection value +0.3MPa", while the value for starting the standby condensate pump is "+0.4MPa". It is evident that the protection settings are not fixed but adaptively adjusted according to the actual operating conditions of the unit, avoiding false trips or failures due to unreasonable settings. This greatly improves the accuracy of the protection system, ensuring that the control system always triggers the corresponding action at the most appropriate time, guaranteeing safety while reducing unnecessary disturbances to the unit.

[0029] The system employs three independent protection logics for condensate pump 4, steam-driven feedwater pump 8, and high-pressure heater drain pump 2, each incorporating rigorous delay judgments. In the steam-driven feedwater pump 8 RB logic, after the pressure drops to the protection threshold, the first pump will trip after a 10-15 second delay. If the pressure does not recover, the second pump will trip after a 5-second delay. Many instantaneous fluctuations in the power system are self-recoverable; this brief delay provides the system with valuable self-stabilization time, effectively distinguishing between transient disturbances and genuine faults. This prevents overly rapid protection actions during transient processes from exacerbating faults or even causing unit outages. It achieves a soft landing in fault handling, smoothly guiding the system from fault conditions to safe and stable conditions through orderly and step-by-step load and auxiliary equipment disconnection, maximizing the maintenance of continuous unit operation.

[0030] The three pressure gauges at the inlet of the steam-driven feedwater pump 8 provide effective pressure information to the controller 12 using a "three-average" method. This effectively shields against interference from occasional malfunctions or signal fluctuations at a single measuring point, greatly improving the reliability of critical monitoring signals and preventing misjudgments in the entire protection system due to a single instrument failure. Simultaneously, all pump outlets are equipped with electric valves directly interlocked with the controller 12. The key advantage is that when the controller 12 issues a command based on reliable judgment logic, the electric valves can quickly and accurately execute switching actions, achieving perfect linkage with pump trip signals. This rapidly isolates faulty equipment, guides the working fluid to the backup path, and ultimately ensures continuous boiler feedwater supply under any abnormal operating conditions, thus guaranteeing the response speed and operational reliability of the entire system.

[0031] Example 1 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0032] Example 2 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0033] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0034] Example 3 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0035] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0036] There are two high-pressure heater drain pumps 2, which are connected in parallel. Two second electric valves 15 are installed near the high-pressure heater drain pumps 2 on the fourth pipe 14. The two second electric valves 15 are respectively set with the two high-pressure heater drain pumps 2. The two high-pressure heater drain pumps 2 are at 100% capacity. The two high-pressure heater drain pumps 2 are normally used with one in use and one on standby.

[0037] Example 4 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0038] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0039] There are two high-pressure heater drain pumps 2, which are connected in parallel. Two second electric valves 15 are installed near the high-pressure heater drain pumps 2 on the fourth pipe 14. The two second electric valves 15 are respectively set with the two high-pressure heater drain pumps 2. The two high-pressure heater drain pumps 2 are at 100% capacity. The two high-pressure heater drain pumps 2 are normally used with one in use and one on standby.

[0040] There are two steam-driven feedwater pumps 8, which are connected in parallel. Each of the two steam-driven feedwater pumps 8 is equipped with a pre-selection first trip button, which is used to control the steam-driven feedwater pump 8 to trip. Two third electric valves 16 are installed on the fifth pipe 18 located between the steam-driven feedwater pump 8 and the high-pressure heater 17. Each of the two third electric valves 16 is set with a corresponding function to the two steam-driven feedwater pumps 8. Both steam-driven feedwater pumps 8 are frequency-adjustable with a capacity of 50%. The two steam-driven feedwater pumps 8 are normally operated in dual-operation mode.

[0041] Example 5 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0042] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0043] There are two high-pressure heater drain pumps 2, which are connected in parallel. Two second electric valves 15 are installed near the high-pressure heater drain pumps 2 on the fourth pipe 14. The two second electric valves 15 are respectively set with the two high-pressure heater drain pumps 2. The two high-pressure heater drain pumps 2 are at 100% capacity. The two high-pressure heater drain pumps 2 are normally used with one in use and one on standby.

[0044] There are two steam-driven feedwater pumps 8, which are connected in parallel. Each of the two steam-driven feedwater pumps 8 is equipped with a pre-selection first trip button, which is used to control the steam-driven feedwater pump 8 to trip. Two third electric valves 16 are installed on the fifth pipe 18 located between the steam-driven feedwater pump 8 and the high-pressure heater 17. Each of the two third electric valves 16 is set with a corresponding function to the two steam-driven feedwater pumps 8. Both steam-driven feedwater pumps 8 are frequency-adjustable with a capacity of 50%. The two steam-driven feedwater pumps 8 are normally operated in dual-operation mode.

[0045] The first electric valve 13, the second electric valve 15, and the third electric valve 16 are all connected to the controller 12 via signal.

[0046] Example 6 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0047] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0048] There are two high-pressure heater drain pumps 2, which are connected in parallel. Two second electric valves 15 are installed near the high-pressure heater drain pumps 2 on the fourth pipe 14. The two second electric valves 15 are respectively set with the two high-pressure heater drain pumps 2. The two high-pressure heater drain pumps 2 are at 100% capacity. The two high-pressure heater drain pumps 2 are normally used with one in use and one on standby.

[0049] There are two steam-driven feedwater pumps 8, which are connected in parallel. Each of the two steam-driven feedwater pumps 8 is equipped with a pre-selection first trip button, which is used to control the steam-driven feedwater pump 8 to trip. Two third electric valves 16 are installed on the fifth pipe 18 located between the steam-driven feedwater pump 8 and the high-pressure heater 17. Each of the two third electric valves 16 is set with a corresponding function to the two steam-driven feedwater pumps 8. Both steam-driven feedwater pumps 8 are frequency-adjustable with a capacity of 50%. The two steam-driven feedwater pumps 8 are normally operated in dual-operation mode.

[0050] The first electric valve 13, the second electric valve 15, and the third electric valve 16 are all connected to the controller 12 via signal.

[0051] The water supply protection method for thermal power generation adopts the water supply protection system for thermal power generation, and the specific steps are as follows: Step 1: Set the pressure protection value, operating value, and RB protection logic within controller 12; Step 2: After powering on, collect the pressure information from the condensate pump outlet pressure gauge 10 and the feed water pump inlet pressure gauge 11, and update the pressure protection value and working value. Step 3: Based on the pressure information, the controller 12 adjusts the opening and closing of the first electric valve 13, the second electric valve 15 and the third electric valve 16 to complete the continuous water supply to the boiler.

[0052] Step 1, the process of determining the pressure protection value and the working value, is as follows: Calculate the low inlet pressure protection value of the steam-driven feedwater pump 8 based on its output; use the low inlet pressure protection value as a benchmark to calculate the pressure protection value and the working value; specifically: the working value of the condensate pump 4 is the low pressure protection value + 0.8 MPa, the allowable starting pressure protection value of the steam-driven feedwater pump 8 inlet is the low pressure protection value + 0.3 MPa, and the starting value of the standby condensate pump when the inlet pressure of the steam-driven feedwater pump 8 is low is the low pressure protection value + 0.4 MPa.

[0053] There are three pressure gauges 11 at the inlet of the water pump. The effective pressure information of the pressure gauges 11 is obtained by averaging the three collected pressure values.

[0054] In step 1, the RB protection logic includes the RB protection logic of condensate pump 4, the RB protection logic of steam-driven feedwater pump 8, and the RB protection logic of high-pressure heater drain pump 2. Specifically, the RB protection logic of condensate pump 4 is as follows: when any condensate pump 4 trips and the unit load is 376MW, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 controlled by the first trip button is closed. The RB protection logic of the steam-driven feedwater pump 8 is as follows: When the feedwater pump inlet pressure gauge 11 reaches the pressure protection value, after a delay of 13 seconds, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 is closed. If the feedwater pump inlet pressure gauge 11 is at the pressure protection value after a delay of 5 seconds, the other steam-driven feedwater pump 8 is tripped. At this time, both third electric valves 16 are closed. The RB protection logic of the high-pressure heater condensate pump 2 is as follows: when both high-pressure heater condensate pumps 2 trip and the unit meets the 547MW requirement, the standby condensate pump 4 is started after a 2s delay. At this time, the first electric valve 13 corresponding to the standby condensate pump 4 is opened. After a 3s delay, the steam-driven feedwater pump 8 controlled by one of the first trip buttons is triggered to trip. At this time, the third electric valve 16 corresponding to the steam-driven feedwater pump 8 is closed.

[0055] Example 7 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0056] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0057] There are two high-pressure heater drain pumps 2, which are connected in parallel. Two second electric valves 15 are installed near the high-pressure heater drain pumps 2 on the fourth pipe 14. The two second electric valves 15 are respectively set with the two high-pressure heater drain pumps 2. The two high-pressure heater drain pumps 2 are at 100% capacity. The two high-pressure heater drain pumps 2 are normally used with one in use and one on standby.

[0058] There are two steam-driven feedwater pumps 8, which are connected in parallel. Each of the two steam-driven feedwater pumps 8 is equipped with a pre-selection first trip button, which is used to control the steam-driven feedwater pump 8 to trip. Two third electric valves 16 are installed on the fifth pipe 18 located between the steam-driven feedwater pump 8 and the high-pressure heater 17. Each of the two third electric valves 16 is set with a corresponding function to the two steam-driven feedwater pumps 8. Both steam-driven feedwater pumps 8 are frequency-adjustable with a capacity of 50%. The two steam-driven feedwater pumps 8 are normally operated in dual-operation mode.

[0059] The first electric valve 13, the second electric valve 15, and the third electric valve 16 are all connected to the controller 12 via signal.

[0060] The water supply protection method for thermal power generation adopts the water supply protection system for thermal power generation, and the specific steps are as follows: Step 1: Set the pressure protection value, operating value, and RB protection logic within controller 12; Step 2: After powering on, collect the pressure information from the condensate pump outlet pressure gauge 10 and the feed water pump inlet pressure gauge 11, and update the pressure protection value and working value. Step 3: Based on the pressure information, the controller 12 adjusts the opening and closing of the first electric valve 13, the second electric valve 15 and the third electric valve 16 to complete the continuous water supply to the boiler.

[0061] Step 1, the process of determining the pressure protection value and the working value, is as follows: Calculate the low inlet pressure protection value of the steam-driven feedwater pump 8 based on its output; use the low inlet pressure protection value as a benchmark to calculate the pressure protection value and the working value; specifically: the working value of the condensate pump 4 is the low pressure protection value + 0.8 MPa, the allowable starting pressure protection value of the steam-driven feedwater pump 8 inlet is the low pressure protection value + 0.3 MPa, and the starting value of the standby condensate pump when the inlet pressure of the steam-driven feedwater pump 8 is low is the low pressure protection value + 0.4 MPa.

[0062] There are three pressure gauges 11 at the inlet of the water pump. The effective pressure information of the pressure gauges 11 is obtained by averaging the three collected pressure values.

[0063] In step 1, the RB protection logic includes the RB protection logic of condensate pump 4, the RB protection logic of steam-driven feedwater pump 8, and the RB protection logic of high-pressure heater drain pump 2. Specifically, the RB protection logic of condensate pump 4 is as follows: when any condensate pump 4 trips and the unit load is 440MW, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 controlled by the first trip button is closed. The RB protection logic of the steam-driven feedwater pump 8 is as follows: When the feedwater pump inlet pressure gauge 11 reaches the pressure protection value, after a delay of 10 seconds, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 is closed. If the feedwater pump inlet pressure gauge 11 is at the pressure protection value after a delay of 5 seconds, the other steam-driven feedwater pump 8 is tripped. At this time, both third electric valves 16 are closed. The RB protection logic of the high-pressure heater condensate pump 2 is as follows: when both high-pressure heater condensate pumps 2 trip and the unit meets the 500MW requirement, the standby condensate pump 4 is started after a 2s delay. At this time, the first electric valve 13 corresponding to the standby condensate pump 4 is opened. After a 3s delay, the steam-driven feedwater pump 8 controlled by one of the first trip buttons is triggered to trip. At this time, the third electric valve 16 corresponding to the steam-driven feedwater pump 8 is closed.

[0064] Example 8 The feedwater protection system for thermal power generation includes a condenser 1 and a high-pressure heater drain pump 2. The condenser 1 is connected to a condensate pump 4 via a first pipe 3. The condensate pump 4 is connected to a low-pressure heater 6 via a second pipe 5. The low-pressure heater 6 is connected to a steam-driven feedwater pump 8 via a third pipe 7. The steam-driven feedwater pump 8 is connected to a high-pressure heater 17 and a boiler 9 via a fifth pipe 18. The high-pressure heater drain pump 2 is connected to the steam-driven feedwater pump 8 via a fourth pipe 14. A condensate pump outlet pressure gauge 10 is installed on the second pipe 5, and a feedwater pump inlet pressure gauge 11 is installed on the third pipe 7. The condensate pump outlet pressure gauge 10 and the feedwater pump inlet pressure gauge 11 are connected to a controller 12.

[0065] There are three condensate pumps 4 connected in parallel. Three first electric valves 13 are installed near the condensate pumps 4 on the first pipe 3. Each of the three first electric valves 13 is set to correspond to one of the three condensate pumps 4. Each of the three condensate pumps 4 is frequency-adjustable with a capacity of 50%. During normal use, two of the three condensate pumps 4 are in operation and one is on standby.

[0066] There are two high-pressure heater drain pumps 2, which are connected in parallel. Two second electric valves 15 are installed near the high-pressure heater drain pumps 2 on the fourth pipe 14. The two second electric valves 15 are respectively set with the two high-pressure heater drain pumps 2. The two high-pressure heater drain pumps 2 are at 100% capacity. The two high-pressure heater drain pumps 2 are normally used with one in use and one on standby.

[0067] There are two steam-driven feedwater pumps 8, which are connected in parallel. Each of the two steam-driven feedwater pumps 8 is equipped with a pre-selection first trip button, which is used to control the steam-driven feedwater pump 8 to trip. Two third electric valves 16 are installed on the fifth pipe 18 located between the steam-driven feedwater pump 8 and the high-pressure heater 17. Each of the two third electric valves 16 is set with a corresponding function to the two steam-driven feedwater pumps 8. Both steam-driven feedwater pumps 8 are frequency-adjustable with a capacity of 50%. The two steam-driven feedwater pumps 8 are normally operated in dual-operation mode.

[0068] The first electric valve 13, the second electric valve 15, and the third electric valve 16 are all connected to the controller 12 via signal.

[0069] The water supply protection method for thermal power generation adopts the water supply protection system for thermal power generation, and the specific steps are as follows: Step 1: Set the pressure protection value, operating value, and RB protection logic within controller 12; Step 2: After powering on, collect the pressure information from the condensate pump outlet pressure gauge 10 and the feed water pump inlet pressure gauge 11, and update the pressure protection value and working value. Step 3: Based on the pressure information, the controller 12 adjusts the opening and closing of the first electric valve 13, the second electric valve 15 and the third electric valve 16 to complete the continuous water supply to the boiler.

[0070] Step 1, the process of determining the pressure protection value and the working value, is as follows: Calculate the low inlet pressure protection value of the steam-driven feedwater pump 8 based on its output; use the low inlet pressure protection value as a benchmark to calculate the pressure protection value and the working value; specifically: the working value of the condensate pump 4 is the low pressure protection value + 0.8 MPa, the allowable starting pressure protection value of the steam-driven feedwater pump 8 inlet is the low pressure protection value + 0.3 MPa, and the starting value of the standby condensate pump when the inlet pressure of the steam-driven feedwater pump 8 is low is the low pressure protection value + 0.4 MPa.

[0071] There are three pressure gauges 11 at the inlet of the water pump. The effective pressure information of the pressure gauges 11 is obtained by averaging the three collected pressure values.

[0072] In step 1, the RB protection logic includes the RB protection logic of condensate pump 4, the RB protection logic of steam-driven feedwater pump 8, and the RB protection logic of high-pressure heater drain pump 2. Specifically, the RB protection logic of condensate pump 4 is as follows: when any condensate pump 4 trips and the unit load is 335MW, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 controlled by the first trip button is closed. The RB protection logic of the steam-driven feedwater pump 8 is as follows: When the feedwater pump inlet pressure gauge 11 reaches the pressure protection value, after a delay of 15 seconds, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump 8 to trip. At this time, the third electric valve 16 at the output end of the steam-driven feedwater pump 8 is closed. If the feedwater pump inlet pressure gauge 11 is at the pressure protection value after a delay of 5 seconds, the other steam-driven feedwater pump 8 is tripped. At this time, both third electric valves 16 are closed. The RB protection logic of the high-pressure heater condensate pump 2 is as follows: when both high-pressure heater condensate pumps 2 trip and the unit meets the 495MW requirement, the standby condensate pump 4 is started after a 2s delay. At this time, the first electric valve 13 corresponding to the standby condensate pump 4 is opened. After a 3s delay, the steam-driven feedwater pump 8 controlled by one of the first trip buttons is triggered to trip. At this time, the third electric valve 16 corresponding to the steam-driven feedwater pump 8 is closed.

Claims

1. A method for protecting the water supply of thermal power plants, characterized in that, The feedwater protection system for thermal power generation includes a condenser (1) and a high-pressure heater drain pump (2). The condenser (1) is connected to a condensate pump (4) through a first pipe (3). The condensate pump (4) is connected to a low-pressure heater (6) through a second pipe (5). The low-pressure heater (6) is connected to a steam-driven feedwater pump (8) through a third pipe (7). The steam-driven feedwater pump (8) is connected to a high-pressure heater (17) and a boiler (9) in sequence through a fifth pipe (18). The high-pressure heater drain pump (2) is connected to the steam-driven feedwater pump (8) through a fourth pipe (14). A condensate pump outlet pressure gauge (10) is provided on the second pipe (5). A feedwater pump inlet pressure gauge (11) is provided on the third pipe (7). The condensate pump outlet pressure gauge (10) and the feedwater pump inlet pressure gauge (11) are connected to a controller (12). There are three condensate pumps (4), which are connected in parallel. The second pipe (5) is equipped with three first electric valves (13) near the condensate pumps (4). The three first electric valves (13) are all set in correspondence with the three condensate pumps (4). The three condensate pumps (4) are all frequency-adjustable with 50% capacity. When the three condensate pumps (4) are in normal use, two are in use and one is on standby. There are two high-pressure heater drain pumps (2), which are connected in parallel. The fourth pipe (14) is equipped with two second electric valves (15) near the high-pressure heater drain pumps (2). The two second electric valves (15) are respectively set with the two high-pressure heater drain pumps (2). The two high-pressure heater drain pumps (2) are at 100% capacity. The two high-pressure heater drain pumps (2) are normally used with one in use and one on standby. There are two steam-driven water pumps (8), which are connected in parallel. Each of the two steam-driven water pumps (8) is equipped with a pre-selection first trip button, which is used to control the steam-driven water pump (8) to trip. Two third electric valves (16) are provided on the fifth pipe (18) between the steam-driven water pump (8) and the high-pressure heater (17). Each of the two third electric valves (16) is corresponding to the two steam-driven water pumps (8). Both steam-driven water pumps (8) are 50% capacity variable frequency adjustable. The two steam-driven water pumps (8) are normally used in two-way operation. The specific steps are as follows: Step 1: Set the pressure protection value, operating value, and RB protection logic in the controller (12); Step 2: After powering on, collect the pressure information from the outlet pressure gauge (10) of the condensate pump and the inlet pressure gauge (11) of the feed water pump, and update the pressure protection value and working value. Step 3: Based on the pressure information, the controller (12) adjusts the opening and closing of the first electric valve (13), the second electric valve (15) and the third electric valve (16) to complete the continuous water supply to the boiler; The RB protection logic mentioned in step 1 includes the RB protection logic of the condensate pump (4), the RB protection logic of the steam-driven feedwater pump (8), and the RB protection logic of the high-pressure heater drain pump (2). The RB protection logic of the condensate pump (4) is as follows: when any condensate pump (4) trips and the unit load is not less than 335MW, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump (8) to trip. At this time, the third electric valve (16) at the output end of the steam-driven feedwater pump (8) controlled by the first trip button is closed. The RB protection logic of the steam-driven feedwater pump (8) is as follows: when the feedwater pump inlet pressure gauge (11) reaches the pressure protection value, after a delay of 10-15s, one of the first trip buttons is triggered to control the corresponding steam-driven feedwater pump (8) to trip. At this time, the third electric valve (16) at the output end of the steam-driven feedwater pump (8) is closed. If the feedwater pump inlet pressure gauge (11) is at the pressure protection value after a delay of 5s, the other steam-driven feedwater pump (8) is tripped. At this time, both of the third electric valves (16) are closed. The RB protection logic of the high-pressure heater condensate pump (2) is as follows: when both high-pressure heater condensate pumps (2) trip and the unit load is not less than 495MW, the standby condensate pump (4) is started after a delay of 2s. At this time, the first electric valve (13) corresponding to the standby condensate pump (4) is opened. After a delay of 3s, the steam-driven feedwater pump (8) controlled by one of the first trip buttons is triggered to trip. At this time, the third electric valve (16) corresponding to the steam-driven feedwater pump (8) is closed.

2. The water supply protection method for thermal power generation according to claim 1, characterized in that, The first electric valve (13), the second electric valve (15) and the third electric valve (16) are all signal connected to the controller (12).

3. The water supply protection method for thermal power generation according to claim 2, characterized in that, The process of determining the pressure protection value and working value in step 1 is as follows: calculate the low pressure protection value of the steam-driven feedwater pump (8) based on the output of the steam-driven feedwater pump (8); use the low pressure protection value as a benchmark to calculate the pressure protection value and working value; specifically: the working value of the condensate pump (4) is the low pressure protection value + 0.8MPa, the allowable pressure protection value for starting the steam-driven feedwater pump (8) is the low pressure protection value + 0.3MPa, and the starting value of the standby condensate pump for starting the steam-driven feedwater pump (8) with low inlet pressure is the low pressure protection value + 0.4MPa.

4. The water supply protection method for thermal power generation according to claim 3, characterized in that, There are three pressure gauges (11) at the inlet of the water pump. The effective pressure information of the pressure gauges (11) at the inlet of the water pump is obtained by averaging the three collected pressure values.

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