A smoke exhaust and air supply system for nuclear power plants

Abstract

The present application relates to the technical field of nuclear power plant, disclose a kind of nuclear power plant exhaust and air supplement system, including air supplement subsystem, exhaust subsystem and safety protection module, air supplement subsystem includes gas source filling module, total pipe pressure relief module and branch pipe distribution module, gas source filling module stores high-pressure gas, after the pressure of low-pressure air is distributed to smoke prevention subarea by total pipe and branch pipe grading reduction;Exhaust subsystem includes suction isolation module and power execution module, connect smoke prevention subarea to provide negative pressure suction power;Safety protection module includes relief protection module and thermal protection module, for overpressure relief and boundary isolation.The present application adopts high-pressure gas storage combined with grading reduction, solves the problem of limited plant space and prevents pipeline icing;Through the feedback electric signal of exhaust valve triggering linkage, the synchronous execution of exhaust and air supplement in specific area is realized;Both ensure the smoke exhaust capacity to prevent smoke diffusion, and avoid negative pressure lock door, guarantee evacuation safety.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant technology, specifically to a smoke exhaust and make-up air system for nuclear power plants. Background Technology

[0002] In the fire protection and ventilation engineering of the nuclear island building of a nuclear power plant, the smoke exhaust system and the make-up air system are key facilities to ensure personnel evacuation and prevent the spread of fire. When a fire occurs in the area, the smoke exhaust network is responsible for extracting toxic and high-temperature smoke to the outside, while the make-up air network simultaneously delivers fresh air to the smoke control zone, thereby maintaining a slightly negative pressure state in the room on fire (smoke control zone). This timely make-up air mechanism can not only prevent the smoke exhaust fan from being blocked due to excessive negative pressure in the closed building, thus preventing the actual smoke exhaust volume from failing to meet the standard, but also prevent the negative pressure from locking the door and hindering personnel evacuation and fire rescue. At the same time, it ensures that the internal smoke will not spread backward to the evacuation passages such as stairwells that maintain positive pressure.

[0003] Due to the dense layout of equipment inside the nuclear island, the reserved installation space in the plant is extremely limited. Conventional make-up air systems using atmospheric or low-pressure containers occupy too much space and cannot meet the on-site engineering layout requirements. In order to reduce the size of the equipment, some designs have switched to high-pressure gas storage schemes. However, when high-pressure gas is directly released to supply gas to the room, the large pressure difference expansion of the gas at the valve port will produce a significant throttling effect, causing a sharp drop in local temperature, which can lead to pipeline ice blockage and transonic flow obstruction. At the same time, the high-pressure gas source will generate pressure infiltration downstream of the pipeline network when it is in standby mode for a long time, causing pipeline creep and pressure rise, which will compromise the standby safety of the equipment.

[0004] In terms of system control and electrical linkage, the existing smoke exhaust duct network and make-up air duct network adopt independent control logic. In actual fire conditions, this separate architecture will cause signal deadlock or action conflict in the control loop due to the multiple triggering and transmission timing differences of the fire alarm signals on site. It is difficult to ensure the synchronous start-up of smoke exhaust equipment and make-up air equipment. In addition, the existing linkage logic lacks a mechanism to identify equipment fault status. Once the main smoke exhaust fan stops without command due to abnormal conditions such as motor overload tripping, the conventional control system will treat the contact signal generated by the passive shutdown as a manual reset signal.

[0005] Furthermore, the existing smoke control and exhaust linkage system lacks robust protection mechanisms under abnormal operating conditions. For smoke control zones equipped with smoke exhaust measures, fire safety logic requires that make-up air must be strictly interlocked with smoke exhaust. That is, when smoke exhaust is interrupted, make-up air must also be stopped simultaneously. Once the main exhaust fan trips due to motor overload or other abnormal conditions, some conventional control systems lack accurate capture and forced interlocking mechanisms for fault shutdown signals, and cannot promptly shut down the make-up air pipeline that is supplying air. This control defect, which blindly and continuously supplies air to the fire area even when smoke exhaust power is lost, can cause the smoke control zone to be instantly blown from a slightly negative pressure to a positive pressure, thereby forcibly pushing high-temperature toxic smoke into adjacent evacuation routes and safe areas, posing a significant fire safety hazard. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a flue gas and make-up air system for nuclear power plants, which solves the problems of high-pressure gas storage throttling and ice blockage under space constraints in nuclear power plants, as well as the problems of low reliability of the linkage between the flue gas and make-up air systems and gas supply interruption caused by abnormal shutdown of the flue gas fan.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a smoke extraction and make-up air system for nuclear power plants, including a make-up air subsystem, a smoke extraction subsystem, and a safety protection module. The make-up air subsystem is used to establish a high-pressure air storage and distribution channel, including a gas source filling module, a main pipe pressure reducing module, and a branch pipe distribution module. The gas source filling module is connected to an external gas source to store high-pressure gas. The air inlet side of the main pipe pressure reducing module is connected to the output end of the gas source filling module for first-stage pressure reduction. The branch pipe distribution module is connected to the main pipe pressure reducing module and distributes the reduced-pressure air to the smoke control zone. The smoke extraction subsystem is used to establish an exhaust channel for the smoke control zone, including a suction isolation module and a power execution module. The suction isolation module is connected to the smoke control zone, and the power execution module is connected to the suction isolation module to provide negative pressure suction power. The safety protection module defines the physical safety boundary between the system pipelines and the end points, including a venting protection module and a thermal protection module. The venting protection module is connected to the gas source filling module for overpressure venting, and the thermal protection module is located at the airflow end of the make-up air branch within the smoke control zone.

[0008] The above system adopts a combination of high-pressure gas storage and staged depressurization, which solves the problem of the layout of the make-up air system caused by insufficient space in the nuclear island plant. At the same time, it streamlines the connection relationship between high-pressure gas storage, negative pressure suction and boundary isolation from the perspective of pipeline hardware, providing underlying structural support for the coordinated execution of smoke exhaust and make-up air operations.

[0009] Furthermore, the gas supply module is equipped with a gas supply pipeline and a compressed air storage tower; the input end of the gas supply pipeline is equipped with a gas source interface, and a gas supply isolation valve and a check valve are sequentially arranged on the gas supply pipeline along the gas filling direction; the output end of the gas supply pipeline is connected to the compressed air storage tower; the main pipe pressure reducing module is equipped with a main gas supply pipe, the inlet side of the main gas supply pipe is connected to the output end of the compressed air storage tower, and a main pipe isolation valve and a main pipe pressure reducing valve are sequentially connected in series on the main gas supply pipe along the gas transmission flow direction.

[0010] Using a compressed air storage tower can reduce the footprint of the make-up air equipment. The main pipe pressure reducing valve performs primary throttling and pressure reduction on the released high-pressure gas, avoiding pipeline icing and airflow blockage caused by a large pressure difference release at one time.

[0011] Furthermore, the branch pipe distribution module is equipped with multiple make-up air branch pipes corresponding to the number of smoke control zones; the air inlet side of each make-up air branch pipe is connected to the downstream side of the main gas supply pipe, and a pressure reducing valve and an electric isolation valve with zero leakage shut-off characteristics are sequentially connected in series along the gas transmission flow direction on each make-up air branch pipe; the end of each make-up air branch pipe is connected to the corresponding make-up air duct, and a fire damper from the thermal protection module is connected in series on each make-up air duct.

[0012] The pressure reducing valve on the branch line is used for secondary pressure regulation to convert the medium-pressure gas after initial pressure reduction into low-pressure air that meets the room's air supply impedance requirements. The pressure reducing valve with zero leakage shut-off characteristics can prevent high-pressure fluid from leaking to the front end of the isolation valve during standby, ensuring the stability of the system in standby mode.

[0013] Furthermore, the suction isolation module is provided with multiple smoke exhaust branch pipes corresponding to the number of smoke prevention zones, and each of the smoke exhaust branch pipes is equipped with a smoke exhaust valve; The power execution module is equipped with a smoke exhaust fan inlet pipe, a smoke exhaust fan, and a smoke exhaust fan outlet pipe; The outlet of each of the aforementioned smoke exhaust branch pipes is connected in parallel to the main inlet pipe of the smoke exhaust fan. A smoke exhaust fire damper is installed on the main inlet pipe of the smoke exhaust fan. The outlet of the main inlet pipe of the smoke exhaust fan is connected to the inlet of the smoke exhaust fan. The outlet of the smoke exhaust fan is connected to the outlet pipe of the smoke exhaust fan.

[0014] The smoke exhaust subsystem adopts a multi-branch parallel layout, and a single smoke exhaust fan can be used to handle the exhaust tasks of multiple smoke control zones. By independently opening and closing the smoke exhaust valves of each branch, local smoke extraction can be performed on the specific area where a fire occurs.

[0015] Furthermore, the system also includes a system controller, which is configured with a multi-parallel exhaust fan trigger control model; After receiving the action command, the smoke exhaust valve corresponding to a specific smoke control zone is energized and drives the valve blade to rotate to the fully open position, sending a feedback electrical signal to the smoke exhaust control circuit indicating that the smoke exhaust valve is in the open working state; The system controller collects the feedback electrical signals of the smoke exhaust valves of all smoke control zones in the system in real time. When any one of the smoke exhaust valves is in the open state, the system controller outputs a start action command to drive the smoke exhaust fan to operate, so as to establish a negative pressure suction channel in the pipeline network.

[0016] By receiving position feedback electrical signals from the smoke exhaust valves in each area through a multi-channel parallel control model, the smoke exhaust fan can be started immediately as soon as any smoke exhaust valve is opened, preventing omissions in the system control logic when multiple signals are input.

[0017] Furthermore, the system is also configured with a positive interlocking trigger architecture, and the supplementary air subsystem is equipped with a programmable logic controller; The feedback electrical signal generated when the smoke exhaust valve in the corresponding area is in the open working state is synchronously transmitted to the input terminal of the programmable logic controller of the air supply subsystem, triggering its output relay contact closing command to the motor drive circuit of the electric isolation valve on the air supply branch pipe of the corresponding smoke prevention zone, driving the electric isolation valve of the corresponding area to open in a positive linkage. The high-pressure gas in the compressed air storage tower is converted into medium-pressure air after the first-stage constant enthalpy depressurization operation is performed by the main pipe pressure reducing valve. The medium-pressure air is then diverted into the corresponding make-up air branch pipe and converted into low-pressure air by the second-stage constant enthalpy depressurization operation performed by the pressure reducing valve configured on the branch pipe. This low-pressure air is then sent into the corresponding smoke control zone.

[0018] The contact signal generated by opening the smoke exhaust valve is directly used to trigger the corresponding branch's make-up air isolation valve, so that the smoke exhaust operation and make-up air operation of a specific smoke control zone are executed simultaneously. The gas discharged from the gas storage tower undergoes two stages of isenthalpic pressure reduction and expansion, and finally outputs low-pressure air to the fire alarm room in a stable manner.

[0019] Furthermore, the electrical control cabinet of the smoke exhaust fan is equipped with normally closed auxiliary contacts of a contactor. When the smoke exhaust fan is stopped by a system reset command, the normally closed auxiliary contacts of the contactor mechanically close when the main contacts open, generating a stop status feedback signal indicating that the smoke exhaust equipment has left the operating condition, and transmitting it to the programmable logic controller of the air supply subsystem. After the programmable logic controller of the air supply subsystem recognizes the stop status feedback signal, it outputs a reverse drive closing command to all the electric isolation valves in the system to perform a forced closing action. When the smoke exhaust fan is stopped without instruction due to abnormal conditions such as motor overload tripping, the system controller also recognizes the stop status feedback signal generated by the opening of the main contacts, and synchronously outputs a drive closing command to all the electric isolation valves in the open state to perform a forced closing action, so as to stop the air supply to the smoke control zone.

[0020] When the system receives a normal reset command to shut down the fan, it will interlock and close all make-up air branch pipes to stop the gas supply. In case of fan overload tripping or other fault shutdowns, the system will also use the captured shutdown signal as the interlock trigger source to forcibly close the electric isolation valve that is in the open state. The interlock protection mechanism strictly implements the safety logic that if the smoke exhaust stops, the make-up air must also stop, to prevent the fire area from changing from a slightly negative pressure to a positive pressure due to continuous gas supply when the smoke exhaust power is lost, thereby eliminating the hidden danger of toxic smoke spreading backward to the safe evacuation passage and other areas.

[0021] Furthermore, the fire damper is internally equipped with a heat-sensitive element and a pre-tensioned torsion spring; When the ambient temperature at the end reaches the set phase change threshold, the heat-sensitive element changes state, and the fusible ring body undergoes thermodynamic melting and fracture, releasing the mechanical constraint force that the fusible ring body originally exerted on the valve actuator. After the pre-tightened torsion spring is unrestrained, it releases the elastic potential energy of the torsion spring and drives the valve blade to rotate to the fully closed position. Under the action of the one-way ratchet mechanism, it performs mechanical locking and cuts off the airflow connection path inside the corresponding air supply duct.

[0022] Fire dampers utilize the phase change melting characteristic of fusible rings at high temperatures to mechanically cut off ventilation branch pipes. This action does not rely on on-site electricity and can automatically lock the pipeline when the ambient temperature exceeds the limit, preventing the back spread of fire.

[0023] Furthermore, the relief protection module is equipped with a safety relief pipeline, which is connected to the compressed air storage tower. The safety relief pipeline is branched with two sets of identical and parallel safety valves, forming two independent relief branches. Isolation valves, one and two, which are kept normally open, are connected in series on the two branches respectively. When the fluid pressure inside the compressed air storage tower exceeds the pressure limit, safety valve one or safety valve two senses the pressure increase variable in the pipe, and the valve disc is pushed up to open the pressure relief channel to discharge the internal high-pressure gas to the outside.

[0024] The dual-parallel safety relief pipeline can automatically release pressure when the gas storage pressure exceeds the limit. The dual-redundancy design ensures that even if one branch is closed for maintenance, the other branch can still work normally, ensuring the safety of the gas storage equipment.

[0025] Furthermore, in the design process of the compressed air storage tower's storage volume, the lower limit constraint of the internal volume is set using the actual gas state equation. The lower limit constraint is related to the volumetric flow rate requirement of the room with the largest smoke exhaust volume in the smoke control zone under standard conditions, the air density under standard conditions, the continuous gas supply time required by the system, the specific gas constant of air, the absolute temperature of the storage environment, the initial filling design pressure of the compressed air storage tower, and the minimum allowable working pressure of the system. The corresponding actual compressibility factor is also introduced for calculation to relate the specific physical relationship between volume, pressure, and temperature.

[0026] To address the issue of air deviating from the ideal gas model under high pressure, the actual gas state equation is used and a compressibility factor is introduced for correction when calculating the gas storage volume. This calculation method can accurately match the gas replenishment flow rate and time requirements of the smoke prevention zone, preventing insufficient actual gas storage capacity of the system due to theoretical calculation errors.

[0027] This invention provides a flue gas exhaust and make-up air system for nuclear power plants. It has the following beneficial effects: 1. This invention uses a compressed air storage tower to store high-pressure gas, and installs a main gas supply pipe pressure reducing valve and a branch pipe pressure reducing valve on the main gas supply pipe and the make-up air branch pipe respectively. This arrangement of high-pressure gas storage combined with two-stage constant enthalpy pressure reduction not only reduces the footprint of the make-up air equipment in the nuclear island plant, but also avoids the pipeline throttling and icing phenomenon caused by the single-stage large pressure difference release of high-pressure gas. At the same time, the branch pipe uses a pressure reducing valve with zero leakage shut-off characteristics to cut off the leakage path of fluid to the end in the standby state and maintain the stability of the pipeline standby pressure.

[0028] 2. This invention establishes an electrical linkage architecture for smoke exhaust and air supply based on hard-wired contact signals. The feedback electrical signal generated when the smoke exhaust valve is opened is synchronously transmitted to the programmable logic controller of the system controller and the air supply subsystem. This control logic uses a single valve action signal to simultaneously trigger the operation of the main smoke exhaust fan and the opening of the electric isolation valve of the corresponding smoke prevention zone, so that the smoke exhaust operation and air supply operation in a specific area are executed synchronously, eliminating the hidden danger of control dead zone when multiple independent signals are transmitted across systems.

[0029] 3. This invention configures reset interlocking and abnormal shutdown interlocking protection logic in the control process. When the smoke exhaust fan stops normally according to the command, the electrical signal generated by the normally closed auxiliary contact of the contactor will be used to close all the make-up air isolation valves to block the ineffective gas supply. When the smoke exhaust fan stops due to non-command faults such as motor overload tripping, the system can also accurately capture the shutdown electrical signal and immediately interlock to forcibly close the electric isolation valves that are in the open state. The mechanism implements the fire safety logic that the make-up air must stop when the smoke exhaust stops. It effectively prevents the room from changing from a slightly negative pressure to a positive pressure due to continuous gas supply when the smoke exhaust power is lost. This eliminates the major hidden danger of toxic smoke spreading backward to stairwells and other safe evacuation routes, and effectively protects the fire isolation safety of the entire plant. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the system plan of the present invention; Figure 2 This is a schematic diagram of the method flow of the present invention; Figure 3 This is a surface diagram for calculating the volume of a compressed air storage tower based on the actual gas state equation of the present invention. Figure 4 This is a graph showing the absolute pressure gradient variation along the pipeline of the two-stage isenthalpic pressure drop in the make-up air subsystem of the present invention. Figure 5 This is a static pressure evolution curve at the end of the standby operating condition according to the present invention; Figure 6 This is a graph showing the oxygen content maintenance curve after the fan trips according to the present invention.

[0031] Among them, 11. Compressed air storage tower; 12. Air supply pipeline; 120. Air source interface; 121. Air supply isolation valve; 122. Check valve; 13. Air supply main pipe; 131. Main pipe isolation valve; 132. Main pipe pressure reducing valve; 14. Air supply branch pipe one; 141. Pressure reducing valve one; 142. Electric isolation valve one; 143. Air supply duct one; 1431. Fire damper one; 15. Air supply branch pipe two; 151. Pressure reducing valve two; 152. Electric isolation valve two; 153. Air supply duct two; 1531. Fire damper two; 16. Air supply branch pipe three; 161. Pressure reducing valve three; 162. Electric isolation valve three; 163. Air supply duct three; 16 31. Fire damper 3; 17. Makeup air branch pipe n; 171. Pressure reducing valve n; 172. Electric isolation valve n; 173. Makeup air duct n; 1731. Fire damper n; 18. Safety relief pipeline; 181. Isolation valve 1; 182. Safety valve 1; 183. Isolation valve 2; 184. Safety valve 2; 21. Smoke exhaust branch pipe 1; 211. Smoke exhaust valve 1; 22. Smoke exhaust branch pipe 2; 221. Smoke exhaust valve 2; 23. Smoke exhaust branch pipe 3; 231. Smoke exhaust valve 3; 24. Smoke exhaust branch pipe n; 241. Smoke exhaust valve n; 25. Smoke exhaust fan inlet main pipe; 251. Smoke exhaust fire damper; 26. Smoke exhaust fan; 27. Smoke exhaust fan outlet pipe. Detailed Implementation

[0032] The technical solutions in 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.

[0033] See attached document Figure 1 The present invention provides a smoke exhaust and make-up air system for nuclear power plants, which may include a make-up air subsystem, a smoke exhaust subsystem, and a safety protection module.

[0034] The air supply subsystem establishes a high-pressure air storage and distribution channel. The air supply subsystem includes an air source filling module, a main pipe pressure reducing module, and a branch pipe distribution module.

[0035] The gas supply module is equipped with a gas supply pipeline 12 and a compressed air storage tower 11. The input end of the gas supply pipeline 12 is equipped with a gas source interface 120. A gas supply isolation valve 121 and a check valve 122 are sequentially arranged on the gas supply pipeline 12 along the gas filling direction. The output end of the gas supply pipeline 12 is connected to the compressed air storage tower 11. An external gas source is connected through the gas source interface 120, injected through the gas supply pipeline 12 and stored inside the compressed air storage tower 11.

[0036] The main pipe pressure reducing module is equipped with a main gas supply pipe 13. The inlet side of the main gas supply pipe 13 is connected to the output end of the compressed air storage tower 11. A main pipe isolation valve 131 and a main pipe pressure reducing valve 132 are connected in series along the gas transmission flow direction on the main gas supply pipe 13.

[0037] The branch pipe distribution module has multiple make-up air branches corresponding to the number of smoke control zones in the system. Taking the first smoke exhaust room as an example, it has a corresponding make-up air branch pipe 14. The air inlet side of the make-up air branch pipe 14 is connected to the downstream side of the main gas supply pipe 13. A pressure reducing valve 141 and an electric isolation valve 142 are connected in series along the gas transmission direction on the make-up air branch pipe 14. The pressure reducing valve 141 has a zero-leakage shut-off characteristic to prevent pressure creep of the fluid to the front end of the electric isolation valve 142 in the standby state. The end of the make-up air branch pipe 14 is connected to the make-up air duct. For connection 143, when the system covers multiple smoke exhaust rooms, make-up air branch pipes 215, 316 to 17 are set in parallel respectively. The pipe connection relationship of each make-up air branch pipe is the same. Pressure reducing valves 2151, 3161 to 171, 2152, 3162 to 172 with zero leakage shut-off characteristics are set in series respectively. The ends are connected to make-up air ducts 2153, 3163 to 173 respectively.

[0038] The smoke exhaust subsystem establishes exhaust channels for each smoke control zone. The smoke exhaust subsystem includes a suction isolation module and a power execution module.

[0039] The suction isolation module is equipped with several smoke exhaust branch pipes corresponding to the number of smoke exhaust rooms. Taking the first smoke exhaust room as an example, it is equipped with a smoke exhaust branch pipe 1 21. A smoke exhaust valve 1 211 is installed on the smoke exhaust branch pipe 1 21. Multiple smoke exhaust rooms are equipped with smoke exhaust branch pipes 22, 33 to 24 respectively. Corresponding smoke exhaust valves 221, 331 to 241 are connected in series on each smoke exhaust branch pipe.

[0040] The power execution module is equipped with a smoke exhaust fan inlet main pipe 25, a smoke exhaust fan 26, and a smoke exhaust fan outlet pipe 27. The outlet ends of smoke exhaust branch pipes 21 to 24 are all connected in parallel to the smoke exhaust fan inlet main pipe 25. A smoke exhaust fire damper 251 is installed on the smoke exhaust fan inlet main pipe 25. The outlet end of the smoke exhaust fan inlet main pipe 25 is connected to the inlet of the smoke exhaust fan 26. The outlet of the smoke exhaust fan 26 is connected to the smoke exhaust fan outlet pipe 27.

[0041] The safety protection module defines the physical safety boundary between the system piping and the terminals. The safety protection module includes a discharge protection module and a thermal protection module.

[0042] The venting protection module is equipped with a safety venting pipeline 18, which is connected to the compressed air storage tower 11. Two sets of venting branches are connected in parallel on the safety venting pipeline 18. Isolation valve 181 and safety valve 182 are connected in series on the first set of venting branches, and isolation valve 283 and safety valve 284 are connected in series on the second set of venting branches.

[0043] The thermal protection modules are distributed at the end of the make-up airflow in each smoke exhaust room. Taking the first smoke exhaust room as an example, fire damper 1431 is installed on the make-up air duct 143. Independent fire dampers 1531, 1631 and n173 are also connected in series on the other make-up air ducts 153, 1631 and n173 respectively.

[0044] See attached document Figure 2 This invention provides a method for operating a flue gas exhaust and makeup air system for nuclear power plants, comprising the following steps: S10, an external air source is connected to the system through the air source interface 120. The gas flows sequentially through the air supply isolation valve 121 and check valve 122 on the air supply pipeline 12 and is injected into the compressed air storage tower 11 for pressure building. After the compressed air storage tower 11 reaches the set charging pressure, it maintains the pressure. In the system standby condition, the main pipe isolation valve 131 on the main air supply pipeline 13 remains open, the isolation valve 181 and the isolation valve 183 on the safety relief pipeline 18 remain open, all electric isolation valves 142 to n172 and smoke exhaust valves 211 to n241 remain closed, the smoke exhaust fan 26 is in the off state, and the fire dampers 1431 to n1731 in each room remain open. S20, when a fire alarm occurs in a specific smoke control zone, the smoke exhaust valve in the corresponding area receives the opening command and performs the opening operation. Taking the first smoke exhaust room as an example, smoke exhaust valve 211 is opened. The smoke exhaust system collects the status signal of the smoke exhaust valve. When any valve from smoke exhaust valve 211 to smoke exhaust valve n241 is in the open state, the system control logic outputs a start signal to control the smoke exhaust fan 26 to start running. The smoke exhaust fan 26 draws gas from the first smoke exhaust room through the smoke exhaust fan inlet main pipe 25 and the smoke exhaust branch pipe 21 to establish a smoke exhaust airflow channel. S30, the status signal of the smoke exhaust valve is synchronously transmitted to the air supply subsystem. The opening signal of the smoke exhaust valve 211 directly triggers the electric isolation valve 142 to open in conjunction, opening the air supply passage. The high-pressure air in the compressed air storage tower 11 continuously enters the main air supply pipe 13 under the pressure difference drive, and flows through the main pipe pressure reducing valve 132 to undergo the first stage of pressure reduction. The medium-pressure air that has completed the first stage of pressure reduction enters the air supply branch pipe 14 and flows through the pressure reducing valve 141 to undergo the second stage of pressure reduction. After the gas undergoes two stages of constant enthalpy pressure reduction, it is converted into low-pressure air that meets the air supply requirements. The low-pressure air passes through the electric isolation valve 142, the air supply pipe 143 and the fire damper 1431 which is in the normally open state in sequence, and enters the first smoke exhaust room to complete the air compensation. When a fire alarm occurs in other smoke exhaust rooms in the system, the smoke exhaust and air supply actions are performed according to the same logic. S40, after completing the smoke exhaust task or receiving a reset command, the smoke exhaust fan 26 performs a shutdown operation. The system collects the shutdown status signal of the smoke exhaust fan 26. All electric isolation valves 142 to 172 receive the shutdown signal and automatically close, blocking the path of the compressed air storage tower 11 to deliver gas to each room. S50 When the ambient temperature in the smoke exhaust room rises and is conducted to the end of the make-up airflow, the temperature sensing structure inside the fire damper performs physical monitoring. Taking the first smoke exhaust room as an example, when the ambient temperature reaches 70℃, the mechanical structure of fire damper-1431 automatically releases and closes, cutting off the airflow connection path inside the make-up air duct-143 and blocking the physical channel for the fire to spread backward along the ventilation duct.

[0045] See attached document Figure 3 In specific implementations, step S10 provided by the present invention may include the following steps: S101, connect to an external air source and fill the system with gas to establish initial working pressure. The external mobile air source or fixed high-pressure compressor unit is connected to the air source interface 120 through a hose or rigid flange. After the air supply isolation valve 121 is opened manually or electrically, high-pressure air enters the system along the flow direction of the air supply pipeline 12. The gas enters the compressed air storage tower 11 through the check valve 122. The check valve 122 only allows the gas to flow unidirectionally in the filling direction, limiting the high-pressure gas in the compressed air storage tower 11 from pipeline backflow leakage when the filling is completed or the external air source is disconnected. Real-time monitoring of the gas pressure inside the compressed air storage tower 11 is carried out based on existing pressure transmitter and control system signal acquisition methods. When the internal pressure reaches the set rated working pressure, and the rated working pressure in this embodiment is 35MPa, the air supply isolation valve 121 is closed to complete the independent pressure building operation of the system.

[0046] S102. Based on the spatial dimensions of the smoke control zone and the fire exhaust requirements, the physical parameters of the gas storage system are calculated and set. Due to the limited space layout of the nuclear island building in a nuclear power plant, conventional atmospheric pressure gas storage tanks cannot meet the land requirements. In this embodiment, the initial filling design pressure of the compressed air storage tower 11 is set to 35MPa. The high-pressure gas storage mode helps to compress a large volume of air under normal conditions into a limited container space. The gas storage capacity of the compressed air storage tower 11 is calculated based on the most unfavorable working condition in the nuclear power fire protection code, that is, it needs to meet the mass consumption requirement of continuous air supply for 30 minutes in the room with the largest smoke exhaust volume in the smoke control zone. Since the volume of air molecules and the intermolecular forces cannot be ignored under the high pressure environment of 35MPa, the state characteristics of air deviate from the ideal gas model. Therefore, in the design process of the gas storage volume, the actual gas state equation is used for calculation. By introducing parameters that reflect the gas compression characteristics into the conventional state equation, the specific physical relationship between volume, pressure and temperature is associated.

[0047] To meet the quality requirements of continuous air supply, the lower limit constraint of the internal volume of the compressed air storage tower 11 in engineering design satisfies the following relationship: ; In the formula, The internal design volume of the compressed air storage tower 11; The volumetric flow rate requirement of the room with the largest smoke exhaust volume in the system's smoke control zone under standard conditions; This refers to the air density under standard conditions. Set the required continuous gas supply time for the system; is the specific gas constant of air; The absolute temperature of the gas storage environment; The initial filling design pressure for compressed air storage tower 11; The actual compressibility factor of air under the conditions corresponding to the initial inflation design pressure and the absolute temperature of the storage environment; This is the minimum operating pressure allowed by the system. It is the actual compressibility factor of air under the conditions corresponding to the minimum working pressure and the absolute temperature of the gas storage environment.

[0048] In practical engineering applications, the above compressibility factor can be obtained by consulting a high-pressure air thermodynamic property handbook or by using general fluid state equation calculation software.

[0049] S103 configures the initial standby state of each pipeline node in the entire system. After the inflation is completed and the standby monitoring cycle is entered, the main pipe isolation valve 131 on the main gas supply pipe 13 remains open, so that the medium-pressure air after the initial pressure reduction by the main pipe pressure reducing valve 132 fills the main gas supply pipe 13 and stops at the beginning of each make-up air branch pipe. The isolation valve 181 and isolation valve 283 on the safety relief pipeline 18 remain open, so that the safety valve 182 and safety valve 284 are directly exposed to the gas source pressure and are always in the mechanical start-up preparation state.

[0050] As boundary elements at the air intake of each smoke control zone, all electrically operated isolation valves 142 to 172 are disconnected from power and kept normally closed, and all smoke exhaust valves 211 to 241 are kept normally closed to ensure the airtightness requirements of each smoke control zone. The motor disconnect contactor of the smoke exhaust fan 26 is in a stopped state, and the fire dampers 1431 to 1731 at the end of each room are kept normally open by the tension of the internal mechanical spring and temperature sensing element to ensure that the make-up air terminal channel remains unobstructed. The combination of the opening and closing states of the various valves and fans in the above system provides the initial action conditions for the system to respond to the fire alarm trigger command.

[0051] In specific implementations, step S20 provided by the present invention may include the following steps: S201, receiving a fire alarm signal and executing the mechanical opening operation of the smoke exhaust valve in the corresponding area. When the detection equipment in a specific smoke control zone senses abnormal fire environmental parameters, the nuclear power plant fire protection system control center outputs electrical alarm and action commands to the corresponding area. After receiving the action command, the internal actuator of the smoke exhaust valve in the corresponding area is energized and drives the valve blade to rotate to the fully open position. Taking the fire alarm in the first smoke exhaust room as an example, the smoke exhaust valve 211 opens to conduct the airflow channel between the first smoke exhaust room and the smoke exhaust branch pipe 21. The physical position confirmation of the smoke exhaust valve's open state is based on the existing valve limit switch or position sensor feedback method. When the blade of the smoke exhaust valve 211 reaches the fully open limit position, the internal mechanical contact of the smoke exhaust valve 211 closes and sends an electrical signal indicating that the smoke exhaust valve 211 is in the open working state to the smoke exhaust control circuit.

[0052] S202: Collects the status feedback signals of the smoke exhaust valves of the entire system and performs multi-channel parallel logic operations. The system controller collects the status feedback electrical signals of the smoke exhaust valves of all smoke prevention zones in the system in real time. The system configures a hardware relay parallel topology or software configuration logic based on logic OR between the smoke exhaust valve status signal node and the start / stop control loop of the smoke exhaust fan 26. When any one or more of the smoke exhaust valves 211 to 241 are in the open state, the output of the control logic is determined to be true and a start action command is issued. At the same time, the software configuration logic of the system controller superimposes and counts the feedback signals of the smoke exhaust valves currently in the open state to generate a characteristic variable of the number of effectively opened valves. The multi-channel parallel smoke exhaust fan 26 trigger control model provides a definite technical structure support for the functional feature that any smoke exhaust valve opening can trigger the start. The configuration of the multi-channel parallel smoke exhaust fan 26 trigger control model eliminates the risk of control dead zone deadlock between multiple source signal inputs and single main equipment power output.

[0053] S203, execute the logic start command and drive the smoke exhaust fan 26 to operate to establish a negative pressure suction channel in the pipeline. After the control circuit outputs the start command, the main contactor of the electrical control cabinet of the smoke exhaust fan 26 is engaged to connect the three-phase power supply of the main motor of the smoke exhaust fan 26. The smoke exhaust fan 26 starts and accelerates its operation, and calls the preset operating frequency parameter according to the number of smoke exhaust valves that are currently open. In this embodiment, the value range of the operating frequency parameter is 30Hz to 50Hz to maintain the constant negative pressure suction force required by the pipeline. The constant negative pressure suction force is transmitted to the interior of the first smoke exhaust room along the smoke exhaust branch pipe 21 that is in the connected state. The high temperature flue gas accumulated in the room is continuously drawn into the smoke exhaust branch pipe 21 under the action of the environmental pressure difference. The airflow merges into the main inlet pipe of the smoke exhaust fan 26 and passes through the normally open smoke exhaust fire damper 251. Finally, it is discharged to the external space of the nuclear island plant through the smoke exhaust fan 26 and the smoke exhaust fan outlet pipe 27 to complete the physical response cycle of the area negative pressure smoke exhaust.

[0054] See attached document Figure 4 In specific implementations, step S30 provided by the present invention may include the following steps: S301 transmits the status feedback signal of the smoke exhaust valve and triggers the positive linkage opening of the electric isolation valve of the corresponding make-up air branch. After the smoke exhaust valve 211 in the smoke exhaust subsystem completes mechanical opening, the hard-wired electrical signal generated by the closure of the internal contacts of the smoke exhaust valve 211 is synchronously transmitted to the input terminal of the programmable logic controller of the make-up air subsystem. The status feedback signal is identified as the direct action source of make-up air supply and triggers the controller to output a relay contact closing command. The relay contact closing command is transmitted to the motor drive circuit of the electric isolation valve 142 on the corresponding make-up air branch through the control cable. The actuator of the electric isolation valve 142 is energized and drives the valve core to disengage from the valve seat and move to the fully open position. The positive interlocking trigger architecture forms the synchronous execution logic of the smoke exhaust action and the make-up air action in the area smoke prevention zone in the electrical control dimension.

[0055] S302, the high-pressure gas in the compressed air storage tower 11 is released and the first-stage constant enthalpy pressure reduction operation is performed through the main pipe pressure reducing module. After the electric isolation valve 142 is opened to conduct the physical passage of the make-up air delivery of the corresponding smoke prevention zone, a fluid pressure difference is formed at both ends of the gas supply main pipe 13. The compressed air stored in the compressed air storage tower 11 is continuously replenished into the internal flow channel of the main pipe pressure reducing valve 132 under the drive of the fluid pressure difference. When the high-pressure fluid flows through the throttling orifice or valve disc gap set inside the main pipe pressure reducing valve 132, the flow cross-sectional area shrinks and then expands in the downstream chamber. The gas completes the isenthalpic thermodynamic conversion process of fluid pressure drop and volume expansion under an adiabatic boundary without external heat exchange. The main pipe pressure reducing valve 132 reduces the absolute pressure of the gas from the initial high pressure state to the set medium-pressure pipeline reference pressure range. In this embodiment, the value range of the medium-pressure pipeline reference pressure range is 1.5MPa to 3.0MPa, which is output to the downstream pipe section. The value of the medium-pressure pipeline reference pressure range is set according to the principle of equal pressure drop ratio between the initial set pressure of the system and the atmospheric pressure at the end to avoid the phenomenon of ice blockage of the throttling valve or transonic flow obstruction caused by excessive single-stage pressure drop.

[0056] S303, the medium-pressure gas after the first-stage pressure reduction is introduced and delivered to the smoke exhaust room via the branch pipe distribution module through the second-stage isenthalpic pressure reduction operation. The medium-pressure fluid that has completed the primary pressure reduction is diverted along the main gas supply pipe 13 into the corresponding activated make-up air branch pipe and passes through the flow section of the pressure reducing valve 141 under the pressure of the pipeline static pressure. The pressure reducing valve 141 uses a throttling and pressure reduction physical mechanism that is isomorphic to the main pipe pressure reducing valve 132 to perform terminal secondary pressure regulation and expansion on the introduced medium-pressure fluid. After the gas undergoes the second-stage isenthalpic pressure reduction operation, the static pressure of the medium-pressure fluid is reduced. The design impedance threshold required to reach the room air outlet is matched to the make-up air duct network. In this embodiment, the design impedance threshold ranges from 200Pa to 500Pa. After two stages of constant enthalpy pressure reduction conversion, the low-pressure air passes through the fully open electric isolation valve 142 and the normally open fire damper 1431 located at the end of the make-up air duct 143. The low-pressure air is sent into the first smoke exhaust room to replenish the gas mass lost due to the smoke exhaust fan 26 and to perform the fixed-point make-up air circulation action of the area smoke control zone.

[0057] In specific implementations, step S40 provided by the present invention may include the following steps: S401, the system receives a reset command and cuts off the main power supply circuit of the exhaust fan 26 to perform a shutdown operation and collects a physical shutdown feedback signal. After the nuclear power plant's main control room confirms that the fire is over or the fire control panel issues a system reset command, the main contactor coil in the exhaust control circuit is de-energized and disconnects the three-phase power supply circuit of the main motor of the exhaust fan 26. After losing electromagnetic driving force, the exhaust fan 26 decelerates and stops rotating due to rotor inertia and stops applying negative pressure suction to the pipeline network.

[0058] The normally closed auxiliary contact of the contactor installed inside the control cabinet of the smoke exhaust fan 26 mechanically closes when the main contact opens, generating a shutdown status feedback signal indicating that the smoke exhaust equipment has been removed from the operating condition. This shutdown status feedback signal serves as the system reset trigger source and only takes effect when the main contact opens due to a manual or normal system reset command from the fire control center. It is transmitted in real time to the input port of the programmable logic controller of the air supply subsystem via the control cable. When the smoke exhaust fan 26 shuts down without instruction due to abnormal conditions such as motor overload tripping, the system controller does not use this shutdown status feedback signal as a reset signal. All electric isolation valves that are in the open state remain open and continue to supply air to the smoke exhaust room to maintain the positive pressure environment of the smoke control zone and meet the evacuation needs of personnel.

[0059] S402, transmits the feedback signal of the smoke exhaust equipment shutdown and triggers the reverse linkage of all electric isolation valves on the make-up air branch pipes to perform a forced closure action. After the programmable logic controller of the make-up air subsystem recognizes the shutdown status electrical signal of the smoke exhaust fan 26, including normal reset shutdown and abnormal trip shutdown, it executes the global reset logic in the internal control configuration of the programmable logic controller and outputs the reverse drive closing command to all electric isolation valves 142 to 172 in the system. After receiving the command, the motor drive actuator of each electric isolation valve reverses the rotation and drives the valve core to fall back to the valve seat sealing surface to establish a physical isolation of the pipeline. All make-up air passages are physically cut off and the continued delivery path of the remaining high pressure gas in the compressed air storage tower 11 to each smoke prevention zone is blocked. The fluid valve elements of the entire system return to the initial standby normally closed state and rebuild the ventilation airtightness boundary of each smoke prevention zone building structure inside the nuclear island plant to complete the electrical interlocking action of a single fire smoke exhaust make-up air task.

[0060] In specific implementations, step S50 provided by the present invention may include the following steps: S501, sensing the terminal ambient temperature and triggering the internal heat-sensitive element of the fire damper to perform a passive mechanical locking action. When the flue gas in the nuclear power plant area spreads to the end of the make-up air duct or the indoor temperature continues to rise to the set phase change threshold, and in this embodiment the phase change threshold is 70°C, the heat-sensitive element configured inside the fire damper at the end of the make-up air branch of each smoke control zone changes state. The specific implementation of the heat-sensitive element adopts the existing fusible alloy ring mechanism with a calibrated melting temperature of 70°C. When the ambient temperature of the fluid flowing through the fire damper reaches the 70°C phase change point, the fusible ring body undergoes thermodynamic melting and fracture, releasing the mechanical constraint force of the fusible ring body on the valve actuator. After losing the constraint of the fusible ring, the pre-tightened torsion spring inside the fire damper releases the elastic potential energy of the torsion spring and drives the valve blade to rotate to the fully closed position and performs mechanical locking under the action of the one-way ratchet mechanism. The fully closed state forms a physical cutoff boundary for the make-up air duct network to extend upstream of the system or other smoke control zones, and the fully closed state does not depend on the continuous power supply of the system electrical control circuit.

[0061] S502, monitor the static pressure inside the compressed air storage tower 11 and trigger the parallel safety valve to perform dual-path relief operation based on the state inside the pipe. When the system is in the working cycle, the fluid pressure inside the compressed air storage tower 11 exceeds the pressure limit. In this embodiment, the pressure limit ranges from 36.75MPa to 38.5MPa. The safety valve configured on the safety relief pipeline 18 senses the pressure increase variable inside the pipe. The safety relief pipeline 18 is connected to two sets of safety valves 182 and 184 with the same structure and connected in parallel to form two independent relief branches. Isolation valves 181 and 183, which are kept in the normally open state, are connected in series on the two branches respectively. The safety valve's tripping pressure threshold is set based on a fixed overpressure multiple of the design pressure of the compressed air storage tower 11. The fixed overpressure multiple is calibrated to be between 1.05 and 1.10 times in engineering applications. When the gas pressure inside the pipe overcomes the preload of the spring inside the safety valve, the valve disc is pushed up to open the pressure relief channel and discharge the internal high-pressure gas to the outside. When isolation valve 181 or isolation valve 2183 is in a partially closed state, the parallel passage of the unisolated side where safety valve 182 or safety valve 2184 is located continues to maintain fluid communication with the internal space of the compressed air storage tower 11.

[0062] To aid in understanding the technical solution of this invention, the following provides an application example and test case of a conventional cable auxiliary plant smoke exhaust and air supply system for a nuclear island.

[0063] In this application example, four smoke control zones are set up. The first smoke exhaust room, with the largest spatial dimensions and smoke exhaust load, is selected as the benchmark. The ambient absolute temperature is set at 293.15K, or 20℃, and the standard air density is taken as 1.2kg / m³. 3 The gas constant for air is taken as 287 J / (kg·K). According to the specifications, the continuous make-up air time is determined to be 1800 s, and the maximum room standard condition volumetric flow rate requirement is 4.0 m³ / s. 3 / s, the initial gas charging pressure of the gas storage tower is set to 35MPa, corresponding to a compressibility factor of 1.05; the minimum operating pressure of the system is set to 3.0MPa, corresponding to a compressibility factor of 0.98.

[0064] Substituting the actual gas state equation into the calculation of the volumetric lower limit constraint, the calculation logic is as follows: the product of the five parameters—the standard condition volumetric flow rate requirement of the largest room in the system, the standard condition air density, the continuous air supply time, the air-to-gas ratio constant, and the ambient absolute temperature—is used as the gas demand baseline parameter; the ratio of the initial charging pressure to the compressibility factor corresponding to the initial state, minus the ratio of the system's minimum operating pressure to the compressibility factor corresponding to the minimum operating pressure, is used as the effective differential pressure release parameter; the quotient obtained by dividing the gas demand baseline parameter by the effective differential pressure release parameter is the boundary value of the volumetric lower limit of the compressed air storage tower 11.

[0065] The calculated lower limit of the volume is approximately 24.01 m³. 3 In this embodiment, the actual total volume is 25m³. 3 There are 11 sets of compressed air storage towers.

[0066] After the system pressure is built up, it enters standby mode. The pressure in the main gas supply pipe 13 is adjusted to a medium pressure of 2.0 MPa by the main pipe pressure reducing valve 132. The pressure reducing valve on the make-up air branch pipe uses zero leakage characteristics to block the fluid. The pressure in the pipe section before the isolation valve is maintained at a low level. When the fire alarm is triggered in the first smoke exhaust room, the smoke exhaust valve opens. The system controller receives the status signal and performs multi-channel parallel logic operation. The controller generates a valid opening quantity variable and calls the initial frequency of 35.2 Hz to start the smoke exhaust fan 26. The static pressure sensor of the fan inlet main pipe feeds back the real-time negative pressure of the pipeline. The controller performs proportional-integral-derivative control and dynamically fine-tunes the fan frequency to 38.4 Hz, so that the negative pressure of the main pipe tends to the set value of -200 Pa. At the same time, the electric isolation valve of the make-up air branch pipe opens. The medium pressure fluid of 2.0 MPa undergoes a secondary isenthalpic pressure reduction through the branch pipe pressure reducing valve. The pipeline static pressure drops to about 342 Pa, providing compensation air volume to the smoke exhaust room.

[0067] In the test case section, the system applying the present invention was selected as the implementation group and the traditional system using conventional mechanical pressure reducing valves without distinguishing the shutdown reset source as the control group. The system was tested on a hardware-in-the-loop simulation platform for comparison.

[0068] Monitoring Table of Operating Status Parameters of Implementation Group and Control Group under Variable Operating Conditions

[0069] According to the table above and Figure 5 and Figure 6 It can be seen that the system of the present invention has shown a definite engineering control effect in many core operating indicators, verifying the integrity of the scheme logic and the effectiveness of implementation. For the standby condition, the static pressure of the terminal pipe section of the implementation group remained at 0.03MPa after running for 168 hours, while the data of the control group climbed to 1.96MPa. This test result shows that the pressure reducing valve arranged in series along the branch pipe and having zero leakage shut-off characteristics blocked the fluid pressure creep phenomenon in the standby state.

[0070] In the table above, the "-" indicates that the test item is a process time indicator for evaluating the dynamic response speed of the system, and is not applicable or has no definite static setting benchmark and environmental initial value.

[0071] The physical isolation between valves remained stable, fundamentally eliminating the structural risk of damage to low-pressure ventilation ducts caused by high-pressure transient release during subsequent startup. Under the variable operating condition of parallel access to dual-zone smoke exhaust, the physical impedance of the pipeline network underwent a step change. In the comparison group, the negative pressure of the main pipe instantly decreased to -78.3Pa, and the system self-recovery time reached 16.7s, resulting in a serious deficiency in smoke exhaust suction. In the implementation group, the negative pressure extreme value of the system during this transient process only fluctuated to -181.6Pa, and quickly converged to the reference threshold within 2.4s. The data proved that the dynamic control architecture combining multi-signal parallel superposition counting and static pressure closed-loop feedback can perform real-time aerodynamic dynamic compensation for the variable branch pipeline network, ensuring the stability of the system's smoke exhaust negative pressure.

[0072] The smoke exhaust power equipment failure test simulated an extreme fire scene. The control group was set to the erroneous operating logic of blindly supplying air to the air supply system after the smoke exhaust fan tripped. This caused the smoke exhaust room to suddenly become severely positive pressure within 30 seconds after the abnormal fan tripped due to continuous air filling. A large amount of high-temperature toxic smoke was back-pressed into the adjacent evacuation corridor. After 300 seconds, the visibility in the corridor suddenly dropped to 1.5m, and the conditions for personnel evacuation were completely lost.

[0073] Under the same operating conditions, the implementation team executed the interlocking protection logic that if the smoke exhaust stops, the make-up air must also stop. The smoke exhaust fan accurately captured the shutdown signal the instant it tripped and simultaneously cut off the isolation make-up air valve, blocking the high-pressure air source compensation. The test results showed that the static pressure in the smoke exhaust room of the implementation team transitioned smoothly within 30 seconds and remained at a slightly negative pressure state of about -5.2Pa. After 300 seconds, the visibility of the adjacent evacuation corridor still remained at the safe standard line of 15.0m. This comparative result directly verified the scientific nature of the abnormal shutdown interlocking logic, eliminating the major hidden danger of toxic smoke spreading backward to the safe evacuation channel due to blind make-up air, and effectively ensuring the safety of the fire isolation boundary of the entire plant. Relying on the static pressure of high-pressure compressed air to continuously provide low-pressure compensation air volume to the smoke control zone, this control strategy slowed down the smoke settling speed, maintained the oxygen content of the internal environment, and met the physical needs of on-site operation and evacuation under fault conditions.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A smoke exhaust and make-up air system for nuclear power plants, characterized in that, This includes a makeup air subsystem, a smoke exhaust subsystem, and a safety protection module; The air supply subsystem is used to establish a high-pressure air storage and distribution channel, including an air source filling module, a main pipe pressure reducing module, and a branch pipe distribution module. The air source filling module is connected to an external air source to store high-pressure gas. The air inlet side of the main pipe pressure reducing module is connected to the output end of the air source filling module for first-stage pressure reduction. The branch pipe distribution module is connected to the main pipe pressure reducing module and distributes the reduced-pressure air to the smoke control zone. The smoke exhaust subsystem is used to establish the exhaust channel of the smoke prevention zone, and includes a suction isolation module and a power execution module. The suction isolation module is connected to the smoke prevention zone, and the power execution module is connected to the suction isolation module to provide negative pressure suction power. The safety protection module defines the physical safety boundary between the system pipeline and the terminal, including a venting protection module and a thermal protection module. The venting protection module is connected to the gas source filling module for overpressure venting, and the thermal protection module is installed at the airflow end of the make-up air branch in the smoke prevention zone.

2. The exhaust and make-up air system for nuclear power plants according to claim 1, characterized in that, The gas supply module is equipped with a gas replenishment pipeline and a compressed air storage tower. The gas supply pipeline has a gas source interface at its input end. A gas supply isolation valve and a check valve are sequentially installed on the gas supply pipeline along the gas filling direction. The output end of the gas supply pipeline is connected to the compressed air storage tower. The main pipe pressure reducing module is equipped with a main gas supply pipe. The inlet side of the main gas supply pipe is connected to the output end of the compressed air storage tower. A main pipe isolation valve and a main pipe pressure reducing valve are connected in series along the gas transmission flow direction on the main gas supply pipe.

3. The exhaust and make-up air system for nuclear power plants according to claim 2, characterized in that, The branch pipe distribution module is equipped with multiple make-up air branch pipes corresponding to the number of smoke control zones; The air inlet side of each of the aforementioned make-up air branch pipes is connected to the downstream side of the main gas supply pipe, and a pressure reducing valve and an electric isolation valve with zero leakage shut-off characteristics are sequentially connected in series along the gas transmission flow direction on each of the aforementioned make-up air branch pipes. The end of each of the aforementioned make-up air branch pipes is connected to the corresponding make-up air duct, and each make-up air duct is equipped with a fire damper from the thermal protection module connected in series.

4. The exhaust and make-up air system for nuclear power plants according to claim 3, characterized in that, The suction isolation module is equipped with multiple smoke exhaust branch pipes corresponding to the number of smoke prevention zones, and each of the smoke exhaust branch pipes is equipped with a smoke exhaust valve. The power execution module is equipped with a smoke exhaust fan inlet pipe, a smoke exhaust fan, and a smoke exhaust fan outlet pipe; The outlet of each of the aforementioned smoke exhaust branch pipes is connected in parallel to the main inlet pipe of the smoke exhaust fan. A smoke exhaust fire damper is installed on the main inlet pipe of the smoke exhaust fan. The outlet of the main inlet pipe of the smoke exhaust fan is connected to the inlet of the smoke exhaust fan. The outlet of the smoke exhaust fan is connected to the outlet pipe of the smoke exhaust fan.

5. The exhaust and make-up air system for nuclear power plants according to claim 4, characterized in that, The system also includes a system controller, which is configured with a multi-parallel smoke exhaust fan trigger control model; After receiving the action command, the smoke exhaust valve corresponding to a specific smoke control zone is energized and drives the valve blade to rotate to the fully open position, sending a feedback electrical signal to the smoke exhaust control circuit indicating that the smoke exhaust valve is in the open working state; The system controller collects the feedback electrical signals of the smoke exhaust valves of all smoke control zones in the system in real time. When any one of the smoke exhaust valves is in the open state, the system controller outputs a start action command to drive the smoke exhaust fan to operate, so as to establish a negative pressure suction channel in the pipeline network.

6. The exhaust and make-up air system for nuclear power plants according to claim 5, characterized in that, The system is also configured with a positive interlocking trigger architecture, and the supplementary air subsystem is equipped with a programmable logic controller; The feedback electrical signal generated when the smoke exhaust valve in the corresponding area is in the open working state is synchronously transmitted to the input terminal of the programmable logic controller of the air supply subsystem, triggering the output relay contact closing command to the motor drive circuit of the electric isolation valve on the air supply branch pipe of the corresponding smoke prevention zone, driving the electric isolation valve of the corresponding area to open in a positive linkage. The high-pressure gas in the compressed air storage tower is converted into medium-pressure air after the first-stage constant enthalpy depressurization operation is performed by the main pipe pressure reducing valve. The medium-pressure air is then diverted into the corresponding make-up air branch pipe and converted into low-pressure air by the second-stage constant enthalpy depressurization operation performed by the pressure reducing valve configured on the branch pipe. This low-pressure air is then sent into the corresponding smoke control zone.

7. The exhaust and make-up air system for nuclear power plants according to claim 6, characterized in that, The electrical control cabinet of the exhaust fan is equipped with normally closed auxiliary contacts of a contactor. When the system reset command causes the exhaust fan to perform a shutdown operation, the normally closed auxiliary contact of the contactor mechanically closes when the main contact opens, generating a shutdown status feedback electrical signal indicating that the exhaust equipment has left the operating condition, and transmitting it to the programmable logic controller of the air supply subsystem. After the programmable logic controller of the air supply subsystem recognizes the shutdown status feedback electrical signal, it outputs a reverse drive closing command to all the electric isolation valves in the system to execute a forced closing action. When the exhaust fan stops without instruction due to abnormal conditions such as motor overload tripping, the system controller also recognizes the shutdown status feedback signal generated by the main contact disconnection, and synchronously outputs a drive closing command to all the electric isolation valves in the open state to execute a forced closing action to stop the supply of air to the smoke control zone.

8. The exhaust and make-up air system for nuclear power plants according to claim 3, characterized in that, The fire damper is internally equipped with a heat-sensitive element and a pre-tightened torsion spring; When the ambient temperature at the end reaches the set phase change threshold, the heat-sensitive element changes state, and the fusible ring body undergoes thermodynamic melting and fracture, releasing the mechanical constraint force that the fusible ring body originally exerted on the valve actuator. After the pre-tightened torsion spring is unrestrained, it releases the elastic potential energy of the torsion spring and drives the valve blade to rotate to the fully closed position. Under the action of the one-way ratchet mechanism, it performs mechanical locking and cuts off the airflow connection path inside the corresponding air supply duct.

9. The exhaust and make-up air system for nuclear power plants according to claim 2, characterized in that, The discharge protection module is equipped with a safety discharge pipeline, which is connected to the compressed air storage tower; The safety relief pipeline is connected to two sets of safety valves 1 and 2 with the same structure and connected in parallel to form two independent relief branches, and isolation valves 1 and 2, which are kept in a normally open state, are connected in series on the two branch pipes respectively. When the internal fluid pressure of the compressed air storage tower exceeds the pressure limit, the first safety valve or the second safety valve senses the pressure increase in the pipe, and the valve disc is pushed up to open the pressure relief channel to release the internal high-pressure gas to the outside.

10. The exhaust and make-up air system for nuclear power plants according to claim 2, characterized in that, In the design process of the compressed air storage tower, the lower limit constraint of the internal volume is set by the actual gas state equation. The lower limit constraint of the engineering design is related to the volumetric flow rate requirement of the room with the largest smoke exhaust volume in the smoke control zone under standard conditions, the air density under standard conditions, the continuous gas supply time required by the system, the specific gas constant of air, the absolute temperature of the gas storage environment, the initial filling design pressure of the compressed air storage tower, and the minimum allowable working pressure of the system. The corresponding actual compression factor is introduced for calculation to relate the specific physical relationship between volume, pressure and temperature.

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