Nuclear power plant conventional island low pressure heater drain recovery system and sequential control method thereof

Abstract

The present application relates to the technical field of nuclear power plant conventional island, and discloses a nuclear power plant conventional island low-level waste heat recovery system and a sequential control method thereof.In the present application, when the low-level waste heat recovery system is started, a first inlet valve, a third inlet valve, a first regulating valve and a first outlet valve are sequentially opened, the opening of each valve is sequentially controlled, the manual intervention of a large number of operators is reduced, the operation steps of the operators are reduced, the risk of operation accidents of the operators in the starting process of the low-level waste heat recovery system is reduced, the opening or closing time of each valve is improved, the starting or closing process of the low-level waste heat recovery system is accelerated, and the labor intensity of the operators is reduced.

Description

Technical Field

[0001] This invention relates to the field of conventional island technology in nuclear power plants, and in particular to a low-pressure heater hydrophobic recovery system and its sequential control method for conventional island nuclear power plants. Background Technology

[0002] The low-pressure heater condensate drainage system is an important component of the conventional island regenerative system in a pressurized water reactor nuclear power plant. Its core function is to collect condensate from the shell side of each stage of the low-pressure heater, pressurize the condensate through a condensate pump, and send it into the low-pressure heater condensate outlet pipe to recover the working fluid and heat, thereby significantly improving the unit's cycle thermal efficiency.

[0003] Currently, the startup process of the low-pressure heater condensate system in nuclear power plants heavily relies on manual operation by operators. During unit startup, operators must sequentially complete dozens of operations according to the operating procedures, including filling the condensate tank, opening and closing valves, starting the pumps, and adjusting the liquid level. These numerous and logically complex steps not only prolong the overall startup cycle but also increase the risk of errors and omissions due to frequent manual operations. This can lead to serious accidents such as condensate pump cavitation damage, abnormal heater water levels, vacuum system leaks, and even water hammer in the turbine.

[0004] Furthermore, existing technologies lack dedicated sequential control logic for low-pressure hydrophobic recovery systems, making it impossible to automate the startup process, resulting in high labor intensity for operators and a high risk of human-caused accidents. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a low-pressure heater condensate recovery system and its sequential control method for the conventional island of a nuclear power plant. This helps to solve the technical problems of existing low-pressure heater condensate recovery systems in nuclear power plants, which rely on a lot of manual operation during startup, resulting in long startup times, high risk of human-caused accidents, and high labor intensity for operators.

[0006] In a first aspect, the present invention provides a low-pressure heater condensate recovery system for a conventional island of a nuclear power plant, comprising: a condensate tank, a first condensate pump, a second condensate pump, a condenser, and a condensate outlet; The condensate tank has a first outlet and a second outlet. The first outlet is connected to the inlet of the first condensate pump and the inlet of the second condensate pump, respectively. The second outlet is connected to the condenser. The outlets of the first condensate pump and the second condensate pump are both connected to the condensate outlet. A first inlet valve is provided on the pipeline between the first outlet and the first condensate pump, and a first outlet valve is provided on the pipeline between the first condensate pump and the condensate outlet; a second inlet valve is provided on the pipeline between the first outlet and the second condensate pump, and a second outlet valve is provided on the pipeline between the second condensate pump and the condensate outlet; a first regulating valve is provided on the pipeline between the condensate outlet and the first condensate pump, and a third inlet valve is provided on the pipeline between the first regulating valve and the condensate outlet; a first drain valve is provided on the pipeline between the second outlet and the condenser.

[0007] In one possible implementation, a first bypass pipeline is further included, located between the drain tank and the first regulating valve; the drain tank further includes a first inlet, which is connected to the outlet of the first bypass pipeline, and the inlet of the first bypass pipeline is connected to the outlets of the first drain pump and the second drain pump respectively; a second regulating valve is provided on the first bypass pipeline.

[0008] In one possible implementation, the first bypass pipeline is further provided with a first gate valve and a first vacuum valve, the first gate valve being located between the second regulating valve and the condensate outlet, and the first vacuum valve being located between the second regulating valve and the condensate tank.

[0009] In one possible implementation, a flow orifice plate is also included, located on the pipeline between the outlet of the first condensate pump and the condensate outlet.

[0010] In one possible implementation, a first heater is also included, the first heater having a third outlet and a second inlet; The condensate tank also includes a fourth outlet and a third inlet, the third outlet being connected to the third inlet and the fourth outlet being connected to the second inlet.

[0011] In one possible implementation, a second heater is further included, the second heater having a fifth outlet and a sixth outlet; the first heater also has a fourth inlet, the fifth outlet is connected to the fourth inlet, and the sixth outlet is connected to the condenser; a second gate valve and a pneumatic safety valve are provided on the pipeline between the fifth outlet and the first heater; a second drain valve is provided on the pipeline between the sixth outlet and the condenser.

[0012] On the other hand, the present invention also provides a sequential control method for a nuclear power plant conventional island low-pressure heater hydrophobic recovery system, applied to the nuclear power plant conventional island low-pressure heater hydrophobic recovery system as described above, the sequential control method comprising: When the liquid level in the condensate tank is at the normal level, the first outlet valve and the second outlet valve are controlled to be closed, and the first inlet valve and the second inlet valve are controlled to be open. The first regulating valve is kept closed, and the third inlet valve is adjusted to an automatic control state. When the set flow rate of the liquid in the low-pressure hydrophobic recovery system meets the target flow rate, the first hydrophobic pump or the second hydrophobic pump is started, and the first outlet valve or the second outlet valve is opened. The third inlet valve is controlled to open automatically, and the first regulating valve is adjusted so that the liquid level in the condensate tank meets the target liquid level. Control the first drain valve to be in the closed state, and then adjust the first regulating valve to the automatic control state; Control the first or second drainage pump to be in automatic control mode and interlock the first and second drainage pumps.

[0013] In one possible implementation, the low-pressure hydrophobic recovery system further includes a first bypass pipeline located between the hydrophobic tank and the first regulating valve; the hydrophobic tank further includes a first inlet, which is connected to the outlet of the first bypass pipeline, and the inlet of the first bypass pipeline is connected to the outlets of the first hydrophobic pump and the second hydrophobic pump respectively; a second regulating valve is provided on the first bypass pipeline. After the third inlet valve is automatically opened, the sequential control method further includes: Adjust the second regulating valve to automatic control mode and monitor the liquid flow rate in the low-pressure hydrophobic recovery system in real time; When the liquid flow rate in the low-pressure hydrophobic recovery system is lower than the target flow rate, the opening of the second regulating valve is increased to increase the liquid flow rate through the first hydrophobic pump or the second hydrophobic pump. When the liquid flow rate in the low-pressure hydrophobic recovery system is higher than the target flow rate, the opening of the second regulating valve is reduced to decrease the liquid flow rate through the first hydrophobic pump or the second hydrophobic pump.

[0014] In one possible implementation, after adjusting the first regulating valve to the automatic control state, the method further includes: Detect the liquid level in the hydrophobic tank and compare the liquid level with the target liquid level; When the liquid level is lower than the target liquid level, the opening of the first regulating valve is reduced to decrease the flow rate at the outlet of the first or second condensate pump. When the liquid level is higher than the target liquid level, the opening of the first regulating valve is increased to increase the flow rate at the outlet of the first or second condensate pump.

[0015] In one possible implementation, the low-pressure condensate recovery system further includes a first heater having a third outlet and a second inlet; the condensate tank further includes a fourth outlet and a third inlet, the third outlet being connected to the third inlet and the fourth outlet being connected to the second inlet; a second heater having a fifth outlet and a sixth outlet; the first heater also having a fourth inlet, the fifth outlet being connected to the fourth inlet, and the sixth outlet being connected to the condenser; a second gate valve and a pneumatic safety valve are provided on the pipeline between the fifth outlet and the first heater; a second condensate trap is provided on the pipeline between the sixth outlet and the condenser; The sequence control method further includes: The second steam trap is controlled to be closed, and the second gate valve and the pneumatic safety valve are controlled to be open. The condensate from the second heater is controlled to flow to the first heater, and then the condensate from the first heater is controlled to flow to the condensate tank.

[0016] In summary, the nuclear power plant conventional island low-pressure heater condensate recovery system and its sequential control method provided by this invention, during the startup of the low-pressure heater condensate recovery system, sequentially opens the first inlet valve, the third inlet valve, the first regulating valve, and the first outlet valve. By controlling the opening of each valve in sequence, the manual intervention of operators is reduced, the number of operating steps is decreased, and the risk of operational accidents during the startup of the low-pressure heater condensate recovery system is lowered. Furthermore, the opening or closing time of each valve is improved, thereby accelerating the startup or shutdown process of the low-pressure heater condensate recovery system and reducing the workload of operators. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a hydrophobic recovery system for the conventional island low-pressure heater of a nuclear power plant, according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating a sequential control method for a hydrophobic recovery system in the conventional island of a nuclear power plant, according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating a sequential control method for a hydrophobic recovery system in the conventional island of a nuclear power plant, according to another embodiment of the present invention. Figure 4 This is a flowchart illustrating a sequential control method for a hydrophobic recovery system in the conventional island of a nuclear power plant, according to another embodiment of the present invention. Figure 5 This is a flowchart illustrating a sequential control method for a hydrophobic recovery system in the conventional island of a nuclear power plant, according to another embodiment of the present invention.

[0019] Figure label: 100. Drainage tank; 110. First outlet; 120. Second outlet; 130. First inlet; 140. Fourth outlet; 150. Third inlet; 200. First drain pump; 300. Second drain pump; 400. Condenser; 500. Condensate outlet; 610. First bypass line; 620. Second bypass line; 700. First heater; 710. Third outlet; 720. Second inlet; 730. Fourth inlet; 800. Second heater; 810. Fifth outlet 820, Sixth Outlet; 1, First Inlet Valve; 2, First Outlet Valve; 3, Second Inlet Valve; 4, Second Outlet Valve; 5, First Regulating Valve; 6, Third Inlet Valve; 7, First Drain Valve; 8, Second Regulating Valve; 9, First Gate Valve; 10, First Vacuum Valve; 11, Flow Orifice Plate; 12, Second Gate Valve; 13, Pneumatic Safety Valve; 14, Second Drain Valve; 15, First Removable Filter Screen; 16, Second Removable Filter Screen; 17, First Check Valve; 18, Second Check Valve. Detailed Implementation

[0020] 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.

[0021] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] According to embodiments of the present invention, such as Figure 1As shown, a low-pressure heater condensate recovery system for a conventional island of a nuclear power plant is provided, comprising: a condensate tank 100, a first condensate pump 200, a second condensate pump 300, a condenser 400, and a condensate outlet 500; the condensate tank 100 has a first outlet 110 and a second outlet 120, the first outlet 110 being connected to the inlets of the first condensate pump 200 and the second condensate pump 300 respectively; the second outlet 120 being connected to the condenser 400, and the outlets of the first condensate pump 200 and the second condensate pump 300 being connected to the condensate outlet 500; a pipe connecting the first outlet 110 and the first condensate pump 200 is provided. The pipeline is equipped with a first inlet valve 1, a first outlet valve 2 between the first condensate pump 200 and the condensate outlet 500; a second inlet valve 3 between the first outlet 110 and the second condensate pump 300, a second outlet valve 4 between the second condensate pump 300 and the condensate outlet 500; a first regulating valve 5 between the condensate outlet 500 and the first condensate pump 200, a third inlet valve 6 between the first regulating valve 5 and the condensate outlet 500; and a first steam trap 7 between the second outlet 120 and the condenser 400.

[0023] In this embodiment, the condensate tank 100 is used to collect and buffer condensate from each stage of the low-pressure heater, perform steam-water separation, stabilize the inlet pressure of the condensate pump, and prevent cavitation in the condensate pump; it also serves as a condensate storage container to adapt to load fluctuations in the low-pressure heater condensate recovery system. The first condensate pump 200 and the second condensate pump 300 are both used to pressurize the low-pressure condensate in the condensate tank 100 to a pressure matching the condensate system and deliver it to the condensate outlet 500 to recover the working fluid and heat. The first condensate pump 200 can serve as the main condensate pump, and the second condensate pump 300 as a standby condensate pump. When the first condensate pump 200 is working, the second condensate pump 300 is in a stopped state. If the first condensate pump 200 fails to operate normally due to an accident, the second condensate pump 300 is controlled to start, ensuring the normal operation of the low-pressure heater condensate recovery system and improving its reliability. Condenser 400, as a cooling and condensing device for turbine exhaust steam, is a condensate receiving container under emergency conditions. It is used to receive emergency condensate from the low-pressure heater condensate recovery system to prevent water hammer from the turbine due to heater overfilling. Condensate outlet 500 is the output interface of the low-pressure heater condensate recovery system, which connects to downstream equipment of the condensate system to collect the recovered condensate into the main condensate flow.

[0024] The condensate drain tank 100 has a first outlet 110 and a second outlet 120. The first outlet 110 is connected to the inlet of the first condensate drain pump 200 and the second condensate drain pump 300, respectively, so that the first condensate drain pump 200 and the second condensate drain pump 300 are connected in parallel. A first inlet valve 1 is provided on the pipeline between the first outlet 110 and the first condensate drain pump 200, a second inlet valve 3 is provided on the pipeline between the first outlet 110 and the second condensate drain pump 300, a first outlet valve 2 is provided on the pipeline between the first condensate drain pump 200 and the condensate outlet 500, and a second outlet valve 4 is provided on the pipeline between the second condensate drain pump 300 and the condensate outlet 500. The first inlet valve 1, the second inlet valve 3, the first outlet valve 2, and the second outlet valve 4 are all electric valves. The first inlet valve 1 and the second inlet valve 3 control the opening and closing of the inlets of the first condensate drain pump 200 and the second condensate drain pump 300, respectively, and the first outlet valve 2 and the second outlet valve 4 control the opening and closing of the outlets of the first condensate drain pump 200 and the second condensate drain pump 300, respectively.

[0025] The second outlet 120 is connected to the condenser 400. A first drain valve 7 is installed on the pipeline between the second outlet 120 and the condenser 400. When the liquid level in the drain tank 100 exceeds the limit or all drain pumps fail, the valve will automatically open and drain the condensate directly to the condenser 400, effectively preventing accidents such as water ingress into the heater and water hammer in the turbine caused by the drain tank 100 being full.

[0026] A first regulating valve 5 is installed on the pipeline between the condensate outlet 500 and the first drain pump 200, and a third inlet valve 6 is installed on the pipeline between the first regulating valve 5 and the condensate outlet 500. By adjusting the opening of the first regulating valve 5, the flow rate of the drain pump to the condensate system is controlled, thereby maintaining the normal liquid level of the drain tank 100. The third inlet valve 6 is the main isolation valve of the low-pressure condensate recovery system. It is used in conjunction with the first regulating valve 5. During normal operation, the third inlet valve 6 remains open, and during maintenance, the third inlet valve 6 is closed to isolate the main pipeline.

[0027] During the condensate drainage process, the condensate in the condensate tank 100 flows out from the first outlet 110, passes through the first inlet valve 1 and enters the first condensate pump 200, then flows sequentially through the first outlet valve 2, the first regulating valve 5 and the third inlet valve 6, and finally flows out from the condensate outlet 500. If the liquid level in the condensate tank 100 is abnormal, the first condensate valve 7 is opened, allowing the water in the condensate tank 100 to flow out from the second outlet 120, and after passing through the first condensate valve 7, it is discharged to the condenser 400 until the liquid level in the condensate tank 100 drops to a safe value. During the operation of the first condensate pump 200, the second condensate pump 300 is in the off state, the second outlet valve 4 is in the off state, and the second inlet valve 3 is in the open state. When the first condensate pump 200 malfunctions and cannot operate normally, the second condensate pump 300 is started and the second inlet valve 3 is opened. Then, the first outlet valve 2 and the first inlet valve 1 are closed sequentially, allowing water in the condensate tank 100 to flow out from the first outlet 110 and enter the second condensate pump 300 through the second inlet valve 3. Then, it flows sequentially through the first outlet valve 2, the first regulating valve 5, and the third inlet valve 6, and finally flows out from the condensate outlet 500. The first condensate pump 200 and the second condensate pump 300 adopt a double-row parallel structure, so even if one row of condensate pumps fails, it will not affect the normal operation of the other row of condensate pumps. By setting multiple safety protection measures, the safe and stable operation of the low-pressure condensate recovery system under various operating conditions is ensured.

[0028] During startup of the low-pressure heater condensate recovery system, the first inlet valve 1, the third inlet valve 6, the first regulating valve 5, and the first outlet valve 2 are opened sequentially. By controlling the opening of each valve in sequence, significant manual intervention and operational steps by operators are reduced, thereby lowering the risk of operational accidents during startup. Furthermore, the opening and closing times of each valve are shortened, accelerating the startup and shutdown process of the low-pressure heater condensate recovery system and reducing the workload of operators.

[0029] In other possible implementations, a first removable filter screen 15 is provided between the first drain pump 200 and the first inlet valve 1, and a first check valve 17 is provided between the first drain pump 200 and the first outlet valve 2; a second removable filter screen 16 is provided between the second drain pump 300 and the second inlet valve 3, and a second check valve 18 is provided between the second drain pump 300 and the second outlet valve 4. By providing removable filters, impurities in the liquid transmitted through the drain tank 100 can be filtered, preventing impurities from affecting the normal operation of the drain pumps; making the filters removable facilitates subsequent cleaning or replacement. The check valves prevent water from flowing back into the drain pumps.

[0030] In one embodiment, a first bypass pipe 610 is also included, located between the drain tank 100 and the first regulating valve 5; the drain tank 100 also includes a first inlet 130, which is connected to the outlet of the first bypass pipe 610, and the inlet of the first bypass pipe 610 is connected to the outlet of the first drain pump 200 and the second drain pump 300 respectively; a second regulating valve 8 is provided on the first bypass pipe 610.

[0031] In this embodiment, the first bypass pipe 610 is installed between the condensate tank 100 and the first regulating valve 5, so that the first inlet 130 of the condensate tank 100 is connected to the outlet of the first bypass pipe 610, and the inlet of the first bypass pipe 610 is connected to the outlet of the first condensate pump 200 and the second condensate pump 300 respectively, so that the water discharged by the first condensate pump 200 or the second condensate pump 300 can enter the condensate tank 100 through the first bypass pipe 610, thereby regulating the water flow in the main circuit when the low-pressure condensate recovery system is operating normally, and also regulating the liquid level in the condensate tank 100. A second regulating valve 8 is provided on the first bypass pipe 610. When the liquid level in the condensate tank 100 rises, it indicates that the condensate flow of the heater increases. At this time, the second regulating valve 8 can be automatically closed. When the liquid level in the condensate tank 100 drops, it indicates that the condensate flow of the heater decreases. At this time, the second regulating valve can be automatically opened to increase the flow rate of water circulating to the condensate tank 100, thereby maintaining the stability of the liquid level in the condensate tank 100 and controlling the flow rate of water output to the condensate system.

[0032] In one embodiment, the first bypass pipeline 610 is further provided with a first gate valve 9 and a first vacuum valve 10. The first gate valve 9 is located between the second regulating valve 8 and the condensate outlet 500, and the first vacuum valve 10 is located between the second regulating valve 8 and the drain tank 100.

[0033] In this embodiment, the first bypass pipe 610 is also equipped with a first gate valve 9 and a first vacuum valve 10. By placing the first gate valve 9 between the second regulating valve 8 and the condensate outlet 500, high-pressure fluid from the outlet of the drain pump can be isolated during maintenance of the second regulating valve 8, creating safe conditions for maintenance of the second regulating valve 8. Moreover, the first gate valve 9 has good sealing performance, meeting the requirements of high-pressure conditions on the condensate outlet 500 side. By placing the first vacuum valve 10 between the second regulating valve 8 and the drain tank 100, the risk of air leaking into the drain tank 100 through the first bypass pipe 610 and then entering the condenser 400, thus disrupting the vacuum, can be reduced. During maintenance of the second regulating valve 8, low-pressure or vacuum fluid from the drain tank 100 side can also be isolated. Furthermore, placing the first vacuum valve 10 on the side away from the drain pump outlet avoids damage to its sealing surface due to high-pressure fluid impacting the first vacuum valve 10.

[0034] In one embodiment, a flow orifice plate 11 is also included, located on the pipeline between the outlet of the first condensate pump 200 and the condensate outlet 500.

[0035] In this embodiment, the flow orifice plate 11 is installed on the pipeline between the outlet of the first condensate pump 200 and the condensate outlet 500. When fluid flows through the flow orifice plate 11, a pressure difference is generated before and after the flow orifice plate 11, and the magnitude of the pressure difference is proportional to the square of the flow rate. Therefore, the flow rate supplied by the condensate pump in the main pipeline can be calculated by measuring the pressure difference. By measuring the total flow rate through the condensate pump in real time, an accurate feedback signal is provided for the automatic control of the second regulating valve 8, ensuring that the total flow rate through the condensate pump meets the target flow rate and is beneficial for controlling the liquid level in the condensate tank 100. The flow orifice plate 11 has a simple structure, no moving parts, high reliability, and long service life.

[0036] In one embodiment, the system also includes a first heater 700 having a third outlet 710 and a second inlet 720; the condensate tank 100 also includes a fourth outlet 140 and a third inlet 150, with the third outlet 710 connected to the third inlet 150 and the fourth outlet 140 connected to the second inlet 720.

[0037] In this embodiment, the first heater 700 has a third outlet 710 and a second inlet 720. The third outlet 710 is connected to the third inlet 150 of the condensate pump, allowing the condensate in the first heater 700 to flow into the condensate tank 100 by gravity and pressure difference. This facilitates the continuous discharge of condensate from the shell side of the first heater 700, preventing the heater from becoming full. The condensate is collected in the condensate tank 100, providing a stable water source for the condensate pump. The fourth outlet 140 of the condensate tank 100 is connected to the second inlet 720, forming a second bypass pipe 620 between the first heater 700 and the condensate tank 100. When the water level in the first heater 700 is too low, the condensate in the condensate tank 100 can flow back to the first heater 700 through the liquid level difference between the condensate tank 100 and the first heater 700. This helps maintain the minimum water level in the first heater 700, preventing the heat exchange tubes from being exposed to steam and burning dry. It also allows for control of the liquid level in the condensate tank 100.

[0038] In one embodiment, a second heater 800 is also included, having a fifth outlet 810 and a sixth outlet 820; the first heater 700 also has a fourth inlet 730, the fifth outlet 810 is connected to the fourth inlet 730, and the sixth outlet 820 is connected to the condenser 400; a second gate valve 12 and a pneumatic safety valve 13 are provided on the pipeline between the fifth outlet 810 and the first heater 700; a second drain valve 14 is provided on the pipeline between the sixth outlet 820 and the condenser 400.

[0039] In this embodiment, the second heater 800 has a fifth outlet 810 and a sixth outlet 820. The fifth outlet 810 is connected to the fourth inlet 730 of the first heater 700, and a second gate valve 12 and a pneumatic safety valve 13 are provided on the pipeline between the fifth outlet 810 and the fourth inlet 730. After the second heater 800 establishes a water level, the condensate can be discharged into the first heater 700 through the second gate valve 12. When the first heater 700 or the second heater 800 is under maintenance, the second gate valve 12 can cut off the normal condensate drainage path between the first heater 700 and the second heater 800. The second gate valve 12 can also withstand the working pressure of the second heater 800 and has good sealing performance. A pneumatic safety valve 13 is installed between the second gate valve 12 and the first heater 700 to prevent backflow of condensate into the second heater 800 when the pressure on the first heater 700 side rises abnormally. Under normal circumstances, when the pressure on the second heater 800 side is higher than that on the first heater 700 side, the pneumatic safety valve 13 automatically opens under the action of the pressure difference, allowing the condensate to flow normally by gravity. When the pressure on the first heater 700 side rises abnormally and the pressure difference is less than the set value, the pneumatic safety valve 13 automatically closes and automatically reopens after the pressure difference returns to normal. This reduces the risk of tube bundle rupture or turbine water hammer accidents caused by increased shell-side pressure of the second heater 800.

[0040] Furthermore, the sixth outlet 820 is connected to the condenser 400. A second drain valve 14 is installed on the pipeline between the sixth outlet 820 and the condenser 400. If the liquid level in the second heater 800 is abnormal, the second drain valve 14 is opened, so that the water in the second heater 800 flows out from the sixth outlet 820 of the second heater 800, and after passing through the second drain valve 14, it is discharged to the condenser 400 until the liquid level in the second heater 800 drops to a safe value.

[0041] Other possible implementations include a second condensate pump 300 system with the same structure as the low-pressure condensate recovery system, with the two low-pressure condensate recovery systems connected in parallel; during operation, even if one of the low-pressure condensate recovery systems fails, it will not affect the normal operation of the other low-pressure condensate recovery system, thereby improving the reliability of the system's condensate drainage.

[0042] On the other hand, such as Figure 2 As shown in the figure, this invention also provides a sequential control method for a hydrophobic recovery system in the conventional island of a nuclear power plant, comprising the following steps: Step S100: When the liquid level in the condensate tank 100 is at the normal level, control the first outlet valve 2 and the second outlet valve 4 to be closed, and control the first inlet valve 1 and the second inlet valve 3 to be open. Step S200: Control the first regulating valve 5 to be in the closed state, and adjust the third inlet valve 6 to the automatic control state; Step S300: When the set flow rate of the liquid in the low-pressure hydrophobic recovery system meets the target flow rate, control the first hydrophobic pump 200 or the second hydrophobic pump 300 to start, and control the first outlet valve 2 or the second outlet valve 4 to open. Step S400: Control the third inlet valve 6 to open automatically, and adjust the first regulating valve 5 to make the liquid level in the condensate tank 100 meet the target liquid level; Step S500: Control the first drain valve 7 to be in the closed state, and then adjust the first regulating valve 5 to the automatic control state; Step S600: Control the first drain pump 200 or the second drain pump 300 to be in automatic control mode, and interlock the first drain pump 200 and the second drain pump 300.

[0043] In this embodiment, before the condensate pumps are started, the condensate tank 100 is filled with water by the conventional island demineralized water distribution system. When it is determined that the liquid level in the condensate tank 100 is at the normal water level, such as 0 mm, the first outlet valve 2 on the pipeline where the first condensate pump 200 is located and the second outlet valve 4 on the pipeline where the second condensate pump 300 is located are controlled to be closed, and the first inlet valve 1 and the second inlet valve 3 are controlled to be open, so that the water in the condensate tank 100 naturally fills the pump chambers and inlet pipelines of the two condensate pumps under the action of gravity, and the air in the pumps is discharged.

[0044] Then, control the first regulating valve 5 to close to prevent a large amount of water from returning directly to the condensate tank 100 through the minimum flow loop when the condensate pump starts, which would prevent the pressure at the condensate outlet 500 from being established. Then, adjust the third inlet valve 6 to the automatic control state so that when the flow rate of the condensate pump is lower than the minimum safe flow rate after the condensate pump starts, the third inlet valve 6 can automatically adjust its opening so that the condensate pump meets the minimum flow requirement.

[0045] The set flow rate of the liquid in the low-pressure hydrophobic recovery system is obtained, and the minimum allowable continuous flow rate of the hydrophobic pump is met when the set flow rate meets the target flow rate. At this point, starting either the first hydrophobic pump 200 or the second hydrophobic pump 300 ensures the safety of the hydrophobic pumps. If the first hydrophobic pump 200 is started, the first outlet valve 2 will automatically open after the first hydrophobic pump 200 reaches its rated speed; if the second hydrophobic pump 300 is started, the second outlet valve 4 will automatically open after the second hydrophobic pump 300 reaches its rated speed, avoiding delays and misoperations caused by manual operation.

[0046] After the first condensate pump 200 starts, the third inlet valve 6 is automatically opened. The liquid level in the condensate tank 100 can be manually adjusted to meet the target level. To avoid frequent valve operation and drastic level fluctuations due to excessive deviation during the initial automatic adjustment phase, the water flow rate is unstable during the initial start-up of the condensate pump. After the third inlet valve 6 automatically opens, the opening of the first regulating valve 5 is manually adjusted based on the liquid level signal from the condensate tank 100. If the liquid level in the condensate tank 100 is too high, the opening of the first regulating valve 5 is increased to increase the flow rate to the condensate system; if the liquid level in the condensate tank 100 is too low, the opening of the first regulating valve 5 is decreased to reduce the flow rate to the condensate system.

[0047] After the liquid level in the condensate tank 100 meets the target level, the first condensate valve 7 is closed to confirm that the low-pressure condensate recovery system can deliver condensate normally, and the system enters normal operation. The first regulating valve 5 is then set to automatic control, ensuring that the set flow rate of the liquid in the low-pressure condensate recovery system always meets the target flow rate by adjusting the opening of the first regulating valve 5. Finally, the first condensate pump 200 or the second condensate pump 300 is set to automatic control and interlocked. By setting the first condensate pump 200 and the second condensate pump 300 to an interlocked state as the main pump and standby pump, the standby pump will quickly and automatically start when the operating pump fails, ensuring the normal operation of the low-pressure condensate recovery system and improving its reliability.

[0048] During the condensate drainage process, the condensate in the condensate tank 100 flows out from the first outlet 110, passes through the first inlet valve 1 and enters the first condensate pump 200, then flows sequentially through the first outlet valve 2, the first regulating valve 5 and the third inlet valve 6, and finally flows out from the condensate outlet 500. If the liquid level in the condensate tank 100 is abnormal, the first condensate valve 7 is opened, allowing the water in the condensate tank 100 to flow out from the second outlet 120, and after passing through the first condensate valve 7, it is discharged to the condenser 400 until the liquid level in the condensate tank 100 drops to a safe value. During the operation of the first condensate pump 200, the second condensate pump 300 is in the off state, the second outlet valve 4 is in the off state, and the second inlet valve 3 is in the open state. When the first condensate pump 200 malfunctions and cannot operate normally, the second condensate pump 300 is started and the second inlet valve 3 is opened. Then, the first outlet valve 2 and the first inlet valve 1 are closed sequentially, allowing water in the condensate tank 100 to flow out from the first outlet 110 and enter the second condensate pump 300 through the second inlet valve 3. Then, it flows sequentially through the first outlet valve 2, the first regulating valve 5, and the third inlet valve 6, and finally flows out from the condensate outlet 500. The first condensate pump 200 and the second condensate pump 300 adopt a double-row parallel structure, so even if one row of condensate pumps fails, it will not affect the normal operation of the other row of condensate pumps. By setting multiple safety protection measures, the safe and stable operation of the low-pressure condensate recovery system under various operating conditions is ensured.

[0049] When the low-pressure heater condensate recovery system is started, the first inlet valve 1, the third inlet valve 6, the first regulating valve 5, and the first outlet valve 2 are opened sequentially. The third inlet valve 6, the first regulating valve 5, and the condensate pump are then set to automatic control mode. This allows for the automatic control of the opening, closing, and adjustment of the opening degree of each valve and condensate pump in sequence, reducing manual intervention and operational steps by operators, thus lowering the risk of operational accidents during the startup process. Furthermore, it improves the opening and closing time of each valve, accelerating the startup and shutdown process of the low-pressure heater condensate recovery system and reducing the workload of operators.

[0050] In one embodiment, such as Figure 3 As shown, the following steps are included after step S400: Step S410: Adjust the second regulating valve 8 to the automatic control state and monitor the liquid flow rate in the low-pressure hydrophobic recovery system in real time; Step S420: When the liquid flow rate in the low-pressure hydrophobic recovery system is lower than the target flow rate, control the opening of the second regulating valve 8 to increase the liquid flow rate through the first hydrophobic pump 200 or the second hydrophobic pump 300. Step S430: When the liquid flow rate in the low-pressure hydrophobic recovery system is higher than the target flow rate, control the opening of the second regulating valve 8 to decrease, thereby reducing the liquid flow rate through the first hydrophobic pump 200 or the second hydrophobic pump 300.

[0051] In this embodiment, a first bypass pipe 610 is provided between the condensate tank 100 and the first regulating valve 5, and a second regulating valve 8 is provided on the first bypass pipe 610. The second regulating valve 8 is adjusted to an automatic control state, and the liquid flow rate in the low-pressure condensate recovery system is acquired in real time through the flow orifice plate 11. The current liquid flow rate in the low-pressure condensate recovery system is compared with the target flow rate. If the liquid flow rate in the low-pressure condensate recovery system is lower than the target flow rate, the opening of the second regulating valve 8 is increased to increase the liquid flow rate through the condensate pump to meet the minimum allowable continuous flow rate of the condensate pump. If the liquid flow rate in the low-pressure condensate recovery system is higher than the target flow rate, the opening of the second regulating valve 8 is closed to reduce the recirculation flow rate returning to the condensate tank 100, thereby reducing the total flow rate of the condensate pump; at the same time, the net flow rate output to the condensate system will increase accordingly to maintain a stable water level in the condensate tank 100.

[0052] In one embodiment, such as Figure 4 As shown, the following steps are included after step S500: Step S510: Detect the liquid level in the hydrophobic tank 100 and compare the liquid level with the target liquid level; Step S520: When the liquid level is lower than the target liquid level, control the opening of the first regulating valve 5 to reduce the flow rate at the outlet of the first condensate pump 200 or the second condensate pump 300. Step S530: When the liquid level is higher than the target liquid level, control the opening of the first regulating valve 5 to increase the flow rate at the outlet of the first condensate pump 200 or the second condensate pump 300.

[0053] In this embodiment, the liquid level in the condensate tank 100 is detected in real time and compared with a target liquid level, such as 0 mm. If the liquid level is lower than 0 mm, it indicates that the outflow rate of the condensate tank 100 is greater than the inflow rate, resulting in a low liquid level in the condensate tank 100. At this time, the opening of the first regulating valve 5 is reduced to decrease the flow rate at the first outlet 110, thereby reducing the flow rate at the outlet of the first condensate pump 200 or the second condensate pump 300, and further reducing the net flow rate into the condensate system, so that the liquid level in the condensate tank 100 gradually rises.

[0054] If the liquid level is higher than 0 mm, it indicates that the outflow velocity of the condensate tank 100 is lower than the inflow velocity, resulting in a higher liquid level in the condensate tank 100. At this time, the opening of the first regulating valve 5 is increased to increase the flow rate at the first outlet 110, thereby increasing the flow rate at the outlet of the first condensate pump 200 or the second condensate pump 300, and further increasing the net flow rate into the condensate system, causing the liquid level in the condensate tank 100 to gradually decrease. This ensures smooth drainage of the low-pressure condensate recovery system without causing the liquid level in the condensate tank 100 to become too low, which could lead to the condensate pumps running dry.

[0055] It is understandable that the liquid level in the condensate tank 100 is 0mm, which means that when the liquid level in the condensate tank 100 is 0mm, the water level in the condensate tank 100 is exactly level with the center line of the condensate pump inlet flange, and the condensate pump inlet is completely filled with water.

[0056] In one embodiment, such as Figure 5 As shown, it also includes the following steps: Step S700: Control the second drain valve 14 to be closed, and control the second gate valve 12 and the pneumatic safety valve 13 to be open; Step S800: Control the drainage of the second heater 800 to the first heater 700, and then control the drainage of the first heater 700 to the drainage tank 100.

[0057] In this embodiment, the second drain valve 14 must be closed before the normal drain passage can be opened; otherwise, the condensate from the second heater 800 will be directly discharged to the condenser 400, resulting in significant heat loss. With the second drain valve 14 closed, the second gate valve 12 between the first heater 700 and the second heater 800 is slowly opened to establish the flow capacity of the normal drain passage and to avoid water hammer caused by sudden flow. Finally, the pneumatic safety valve 13 is automatically opened based on the pressure difference. When the second gate valve 12 is opened, the pressure on the second heater 800 side is higher than that on the first heater 700 side, and the pneumatic safety valve 13 will automatically open.

[0058] Furthermore, as the second heater 800 is put into operation, condensate begins to form on the shell side of the second heater 800. When the water level in the second heater 800 reaches the target condition, the condensate begins to flow by gravity through the second gate valve 12 and the pneumatic safety valve 13 to the first heater 700. After receiving the condensate from the second heater 800, the water level in the first heater 700 begins to rise. When the water level in the first heater 700 reaches the target condition, the condensate from the first heater 700 is circulated to the condensate tank 100. The target condition can be set according to actual usage requirements; for example, the target condition can be 30% or 50% of the normal water level.

[0059] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0060] The specific embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A hydrophobic recovery system for the low-pressure heater in the conventional island of a nuclear power plant, characterized in that, include: Drainage tank (100), first drainage pump (200), second drainage pump (300), condenser (400) and condensate outlet (500); The condensate tank (100) has a first outlet (110) and a second outlet (120). The first outlet (110) is connected to the inlet of the first condensate pump (200) and the second condensate pump (300), respectively. The second outlet (120) is connected to the condenser (400). The outlets of the first condensate pump (200) and the second condensate pump (300) are both connected to the condensate outlet (500). A first inlet valve (1) is provided on the pipeline between the first outlet (110) and the first condensate pump (200), and a first outlet valve (2) is provided on the pipeline between the first condensate pump (200) and the condensate outlet (500); a second inlet valve (3) is provided on the pipeline between the first outlet (110) and the second condensate pump (300), and a second outlet valve (4) is provided on the pipeline between the second condensate pump (300) and the condensate outlet (500); a first regulating valve (5) is provided on the pipeline between the condensate outlet (500) and the first condensate pump (200), and a third inlet valve (6) is provided on the pipeline between the first regulating valve (5) and the condensate outlet (500); a first drain valve (7) is provided on the pipeline between the second outlet (120) and the condenser (400).

2. The hydrophobic recovery system for the conventional island low-pressure heater of a nuclear power plant according to claim 1, characterized in that, It also includes a first bypass pipe (610) located between the drain tank (100) and the first regulating valve (5); the drain tank (100) also includes a first inlet (130), the first inlet (130) is connected to the outlet of the first bypass pipe (610), the inlet of the first bypass pipe (610) is connected to the outlet of the first drain pump (200) and the second drain pump (300) respectively; a second regulating valve (8) is provided on the first bypass pipe (610).

3. The hydrophobic recovery system for the conventional island low-pressure heater of a nuclear power plant according to claim 2, characterized in that, The first bypass pipeline (610) is also provided with a first gate valve (9) and a first vacuum valve (10). The first gate valve (9) is located between the second regulating valve (8) and the condensate outlet (500), and the first vacuum valve (10) is located between the second regulating valve (8) and the drain tank (100).

4. The hydrophobic recovery system for the conventional island low-pressure heater of a nuclear power plant according to claim 1, characterized in that, It also includes a flow orifice plate (11) located on the pipeline between the outlet of the first condensate pump (200) and the condensate outlet (500).

5. The hydrophobic recovery system for the conventional island low-pressure heater of a nuclear power plant according to claim 1, characterized in that, It also includes a first heater (700) having a third outlet (710) and a second inlet (720); The condensate tank (100) also includes a fourth outlet (140) and a third inlet (150), the third outlet (710) being connected to the third inlet (150), and the fourth outlet (140) being connected to the second inlet (720).

6. The hydrophobic recovery system for the conventional island low-pressure heater of a nuclear power plant according to claim 5, characterized in that, It also includes a second heater (800) having a fifth outlet (810) and a sixth outlet (820); the first heater (700) also has a fourth inlet (730), the fifth outlet (810) being connected to the fourth inlet (730), and the sixth outlet (820) being connected to the condenser (400); a second gate valve (12) and a pneumatic safety valve (13) are provided on the pipeline between the fifth outlet (810) and the first heater (700); a second drain valve (14) is provided on the pipeline between the sixth outlet (820) and the condenser (400).

7. A sequential control method for a low-pressure reactor hydrophobic recovery system in the conventional island of a nuclear power plant, characterized in that, The sequential control method, applied to the hydrophobic recovery system of the conventional island low-pressure heater in a nuclear power plant as described in any one of claims 1-6, comprises: When the liquid level in the condensate tank (100) is at the normal water level, the first outlet valve (2) and the second outlet valve (4) are controlled to be closed, and the first inlet valve (1) and the second inlet valve (3) are controlled to be open. Control the first regulating valve (5) to be in the closed state, and adjust the third inlet valve (6) to the automatic control state; When the set flow rate of the liquid in the low-pressure hydrophobic recovery system meets the target flow rate, the first hydrophobic pump (200) or the second hydrophobic pump (300) is started, and the first outlet valve (2) or the second outlet valve (4) is opened. The third inlet valve (6) is controlled to open automatically, and the first regulating valve (5) is adjusted so that the liquid level in the condensate tank (100) meets the target liquid level. Control the first drain valve (7) to be in the closed state, and then adjust the first regulating valve (5) to the automatic control state; Control the first drainage pump (200) or the second drainage pump (300) to be in automatic control mode, and interlock the first drainage pump (200) and the second drainage pump (300).

8. The sequential control method for the hydrophobic recovery system of the conventional island low-pressure heater in a nuclear power plant according to claim 7, characterized in that, The low-pressure hydrophobic recovery system also includes a first bypass pipeline (610) located between the hydrophobic tank (100) and the first regulating valve (5); the hydrophobic tank (100) also includes a first inlet (130), which is connected to the outlet of the first bypass pipeline (610), and the inlet of the first bypass pipeline (610) is connected to the outlets of the first hydrophobic pump (200) and the second hydrophobic pump (300) respectively; a second regulating valve (8) is provided on the first bypass pipeline (610). After the third inlet valve (6) is automatically opened, the sequential control method further includes: Adjust the second regulating valve (8) to the automatic control state and monitor the liquid flow rate in the low-pressure hydrophobic recovery system in real time; When the liquid flow rate in the low-pressure hydrophobic recovery system is lower than the target flow rate, the opening of the second regulating valve (8) is increased to increase the liquid flow rate through the first hydrophobic pump (200) or the second hydrophobic pump (300); When the liquid flow rate in the low-pressure hydrophobic recovery system is higher than the target flow rate, the opening of the second regulating valve (8) is reduced to decrease the liquid flow rate through the first hydrophobic pump (200) or the second hydrophobic pump (300).

9. The sequential control method for the hydrophobic recovery system of the conventional island low-pressure heater in a nuclear power plant according to claim 7, characterized in that, After adjusting the first regulating valve (5) to the automatic control state, the method further includes: The liquid level in the hydrophobic tank (100) is detected, and the liquid level is compared with the target liquid level. When the liquid level is lower than the target liquid level, the opening of the first regulating valve (5) is reduced to decrease the flow rate at the outlet of the first condensate pump (200) or the second condensate pump (300). When the liquid level is higher than the target liquid level, the opening of the first regulating valve (5) is increased to increase the flow rate at the outlet of the first condensate pump (200) or the second condensate pump (300).

10. The sequential control method for the hydrophobic recovery system of the conventional island low-pressure heater in a nuclear power plant according to claim 7, characterized in that, The low-pressure hydrophobic recovery system further includes a first heater (700) having a third outlet (710) and a second inlet (720); the hydrophobic tank (100) further includes a fourth outlet (140) and a third inlet (150), the third outlet (710) being connected to the third inlet (150), and the fourth outlet (140) being connected to the second inlet (720); a second heater (800) having a fifth outlet (810) and a sixth outlet (820); the first heater (700) also has a fourth inlet (730), the fifth outlet (810) being connected to the fourth inlet (730). The sixth outlet (820) is connected to the condenser (400); a second gate valve (12) and a pneumatic safety valve (13) are provided on the pipeline between the fifth outlet (810) and the first heater (700); a second steam trap (14) is provided on the pipeline between the sixth outlet (820) and the condenser (400). The sequence control method further includes: Control the second drain valve (14) to be closed, and control the second gate valve (12) and the pneumatic safety valve (13) to be open; The condensate from the second heater (800) is controlled to flow to the first heater (700), and then the condensate from the first heater (700) is controlled to flow to the condensate tank (100).

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