Nuclear power plant seawater desalination control system and method

Abstract

The invention belongs to the technical field of nuclear energy seawater desalination, and aims to solve the problems of low automation degree, difficulty in maintenance, low response speed and low reliability in the existing nuclear power plant seawater desalination technology. The invention discloses a nuclear power plant seawater desalination control system and method. The system comprises a control layer, a communication layer and a monitoring layer, the method comprises an ultrafiltration step, a first-stage reverse osmosis step and a second-stage reverse osmosis step. According to the application, an operator can remotely monitor the operation condition of the seawater desalination and demineralized water production system, corresponding automatic operation control can be carried out according to the technological process requirement, and corresponding automatic operation control can be carried out according to the technological process requirement.

Description

Technical Field

[0001] The present application belongs to the technical field of nuclear energy seawater desalination, and in particular, relates to a seawater desalination control system and method for a nuclear power plant. Background Art

[0002] The seawater desalination system of Tianwan Nuclear Power Station uses seawater from the drainage tunnel gate shafts of Units 3 and 4 and the forebay of the plant to provide water that meets the water quality requirements of the corresponding systems to the desalination plant, desalination systems of Units 1 to 8, domestic water system of the plant, cooling water of Units 1 to 8, and cooling water system of the North BOP equipment after pretreatment, ultrafiltration and reverse osmosis in the chemical water plant.

[0003] The desalination control system mainly includes pretreatment, desalination, demineralized water, gate well water intake facilities, floating water intake facilities, etc. In daily operation, the control system architecture needs to achieve the control requirements of low load rate of the main and standby CPUs of each substation, power supply redundancy, controller module redundancy, controller network redundancy, fast response time, and small impact range of hot-swap I / O cards. The operating personnel use the operator station display, function keyboard and mouse in the water control room as the main monitoring and control means, and realize the start and stop operation, operation condition monitoring, adjustment and accident handling of demineralized water, seawater desalination, seawater pretreatment, floating water intake facilities, and valve well water intake pump stations with the cooperation of a small number of local operators and patrol inspection personnel. Summary of the invention

[0004] The purpose of the present application is to provide a nuclear power plant seawater desalination control system and method, which solves the problems of low automation, difficult maintenance, slow response speed and low reliability existing in the existing nuclear power plant seawater desalination technology.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides a nuclear power plant seawater desalination control system, comprising:

[0007] The control layer is equipped with multiple DCS cabinets and relay cabinets, which are used to control the desalination and demineralization part, floating water intake facilities, chemical water electrical valve well water intake facilities, pretreatment part and another desalination and demineralization part. Each DCS cabinet and relay cabinet is equipped with I / O cards, processor units and control networks to achieve measurement, monitoring, control and protection of process and equipment;

[0008] The communication layer uses a redundant network configuration to connect the control layer and the monitoring layer for system communication;

[0009] The monitoring layer is equipped with an operator station and an engineer station, which are used to collect and display operating information and monitor and control the operating conditions of the unit.

[0010] In some embodiments, the control layer includes 10 DCS cabinets and 4 relay cabinets, and the specific configuration is as follows:

[0011] DCS cabinets No. 1 to No. 5 and relay cabinets No. 1 to No. 2 are used to control the desalination and desalination parts and floating water intake facilities;

[0012] No. 6 DCS cabinet is used to control the chemical water, electrical and gas valve well water intake facilities;

[0013] DCS cabinets No. 7 to No. 8 and relay cabinet No. 3 are used to control the pre-processing part;

[0014] DCS cabinets No. 9 to No. 10 and relay cabinet No. 4 are used to control another seawater desalination and demineralized water section;

[0015] The monitoring and control signals of the floating water intake facility are connected to the No. 2 DCS cabinet by communication.

[0016] In some embodiments, I / O cards are deployed in each DCS cabinet to collect analog or digital signals from the field and convert these signals for processing by the main controller, or output the signals processed by the main controller to the field through each relay cabinet; for important signals with high availability and reliability requirements, redundant I / O configuration is adopted.

[0017] In some embodiments, the processor unit is deployed in some DCS cabinets, and communicates with I / O devices through the control network to realize the collection of field data and the transmission of control data; the processor unit communicates with the monitoring layer through the redundant system network to realize the uploading of process data and diagnostic data; the processor unit adopts the main-hot standby mode, and each pair of processors consists of two processor modules, one in working state and the other in hot standby state.

[0018] In some embodiments, the communication layer uses a 100M high-speed redundant network to form a system network, connects the operator station, monitoring layer and control layer, completes data monitoring of the entire system, and responds to various operation requests from the operator; the system network adopts a star structure, and each subsystem is connected to the switch on the system center node as a sub-node.

[0019] In some embodiments, the monitoring layer includes:

[0020] Operator station, used to collect and display operating information, so that operators can monitor and control the operating conditions of the unit;

[0021] Engineer station, used for program development, system diagnosis, control system configuration, and editing and modifying databases and screens.

[0022] In some embodiments, the system further comprises:

[0023] The ultrafiltration subsystem has an ultrafiltration water pump, a self-cleaning filter, an ultrafiltration device and an ultrafiltration water tank. The ultrafiltration device system is divided into 3 groups, each group contains at least 5 sets of ultrafiltration devices running in parallel, and a total of 15 sets of ultrafiltration devices are set. Two ultrafiltration water tanks are set behind the ultrafiltration devices;

[0024] The primary reverse osmosis subsystem has a primary reverse osmosis water feed pump, a primary reverse osmosis safety filter, a primary reverse osmosis high-pressure pump, a primary reverse osmosis device and a primary fresh water tank. The primary reverse osmosis device is a unit system and operates in parallel, with a total of 5 sets;

[0025] The secondary reverse osmosis subsystem has a secondary reverse osmosis water feed pump, a secondary reverse osmosis safety filter, a secondary reverse osmosis high-pressure pump, a secondary reverse osmosis device and a secondary fresh water tank. The secondary reverse osmosis device is a unit system and operates in parallel, with a total of 4 sets.

[0026] In some embodiments, the operation of the ultrafiltration device is automatically controlled by the front-rear pressure difference or the turbidity of the outlet water, and participates in the operation control of the first-stage reverse osmosis device; the operation of the first-stage reverse osmosis device is put into operation one by one according to the liquid level of the first-stage fresh water tank and the start and stop status of the second-stage reverse osmosis device; the operation of the second-stage reverse osmosis device is interlocked with the liquid level of the second-stage fresh water tank, and the number of reverse osmosis devices in operation is selectively arranged according to the actual water consumption or the equipment conditions of the reverse osmosis device.

[0027] In some embodiments, a high-pressure pump is provided before the ultrafiltration device, the first-stage reverse osmosis device and the second-stage reverse osmosis device. The high-pressure pump adopts frequency conversion control and alarms and stops the pump according to the low inlet pressure or excessive outlet pressure.

[0028] In a second aspect, the present application provides a nuclear power plant seawater desalination control method, which uses the nuclear power plant seawater desalination control system, including:

[0029] The impurities in the water are removed by the ultrafiltration subsystem, and the ultrafiltration product water is stored in the ultrafiltration water tank. The operation of the ultrafiltration device is adjusted by frequency conversion according to the ultrafiltration water tank liquid level and the output of the ultrafiltration water inlet pump;

[0030] The product in the ultrafiltration water tank is further desalinated by the first-stage reverse osmosis device. The first-stage reverse osmosis device is a unit system and is operated in parallel. A first-stage reverse osmosis water pump, a first-stage reverse osmosis safety filter and a first-stage reverse osmosis high-pressure pump are set. According to the liquid level of the first-stage fresh water tank and the start and stop status of the second-stage reverse osmosis device, the first-stage reverse osmosis device is put into operation or withdrawn one by one, and the output of the first-stage reverse osmosis high-pressure pump is adjusted by frequency conversion.

[0031] The product after the primary reverse osmosis is further desalinated by a secondary reverse osmosis device to obtain raw water for the desalted water treatment system. A secondary reverse osmosis water feed pump, a secondary reverse osmosis safety filter and a secondary reverse osmosis high-pressure pump are set. According to the liquid level of the secondary fresh water tank, the secondary reverse osmosis device is put into or out of operation one by one, and the output of the secondary reverse osmosis water feed pump and the secondary reverse osmosis high-pressure pump is adjusted by frequency conversion.

[0032] Compared with the prior art, the nuclear power plant seawater desalination control system and method provided by this application have the following advantages:

[0033] Beneficial effects:

[0034] The present application enables operators to remotely monitor the operating conditions of seawater desalination and desalination water production systems, and can perform corresponding automatic operation control according to the requirements of the technological process.

[0035] This application adopts a distributed control system (DCS) for centralized monitoring to realize functions such as data collection, control, alarm, interlock protection, diagnosis, start / stop, normal operation, accident handling and operation guidance of the chemical water system, which is convenient for operating personnel to monitor, control and handle accidents in the production process.

[0036] The availability of the seawater desalination control system of a nuclear power plant shall not be less than 99.9%.

[0037] The desalination control system of nuclear power plants is easy to configure and has defense functions to ensure the stability of the software. All hardware and software are easy to use and expand, and the functions are as decentralized as possible. Failure of any component in the system will not affect the function of the entire system.

[0038] The desalination control system of a nuclear power plant is easy to maintain, with the goal of reducing the risk of human error and improper disturbance under all system operating conditions, and the mean time to repair will not jeopardize the system control function. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the technical description.

[0040] Figure 1 The desalination control system diagram of the nuclear power plant provided for this application;

[0041] Figure 2 A schematic diagram of the working principle of processor unit redundancy provided for this application;

[0042] Figure 3 A schematic diagram of the control network (CNET) topology provided for this application;

[0043] Figure 4Implementation flow chart of the desalination control system of a nuclear power plant provided for this application;

[0044] Figure 5 A flow chart of the seawater desalination control method for a nuclear power plant provided in this application. DETAILED DESCRIPTION

[0045] The following is further explained in detail through specific implementation methods.

[0046] like Figure 1 As shown, the present application provides a desalination control system for a nuclear power plant. The design of the control system follows the principles of centralized management, decentralized control, and resource sharing, and realizes the functions of collecting process data, equipment operating status, automatically adjusting production data, and controlling the operation of process equipment. The system includes a control layer, a communication layer, and a monitoring layer.

[0047] (1) Control Layer

[0048] The control layer realizes the measurement, monitoring, control and protection of the process and equipment, and is mainly composed of three parts: I / O cards, processor units and control networks. Figure 1 As shown, the control layer of the seawater desalination control system of the nuclear power plant includes DCS cabinet No. 1 (1#DCS cabinet), DCS cabinet No. 2 (2#DCS cabinet), DCS cabinet No. 3 (3#DCS cabinet), DCS cabinet No. 4 (4#DCS cabinet), DCS cabinet No. 5 (5#DCS cabinet), DCS cabinet No. 6 (6#DCS cabinet), DCS cabinet No. 7 (7#DCS cabinet), DCS cabinet No. 8 (8#DCS cabinet), DCS cabinet No. 9 (9#DCS cabinet), DCS cabinet No. 10 (10#DCS cabinet), relay cabinet No. 1 (1#relay cabinet), relay cabinet No. 2 (2#relay cabinet), relay cabinet No. 3 (3#relay cabinet), and relay cabinet No. 4 (4#relay cabinet).

[0049] DCS cabinet No. 1, DCS cabinet No. 2, DCS cabinet No. 3, DCS cabinet No. 4, DCS cabinet No. 5, relay cabinet No. 1 and relay cabinet No. 2 are used to control the seawater desalination and desalination part (seawater desalination + desalination part 1) and floating water intake facilities; DCS cabinet No. 6 is used to control the chemical water electrical valve well water intake facilities; DCS cabinet No. 7, DCS cabinet No. 8 and relay cabinet No. 3 are used to control the pretreatment part; DCS cabinet No. 9, DCS cabinet No. 10 and relay cabinet No. 4 are used to control the seawater desalination and desalination part (seawater desalination + desalination part 2); the monitoring and control signals of the floating water intake facilities are connected to DCS cabinet No. 2 by communication.

[0050] I / O cards are deployed in each DCS cabinet to collect analog or digital signals from the field, convert these signals for processing by the main controller, or output the signals processed by the main controller to the field through each relay cabinet. For important signals with high availability and reliability requirements, such as regulation loop signals, redundant I / O configuration is adopted, and the input (or output) signals are collected (or output) by different modules. The failure of a single I / O card will not cause disturbances to other devices.

[0051] The K series modules have powerful redundancy functions, which are ensured by redundant configuration of the modules, so that the system can work normally even in the case of a single module failure. Installing two K-AI01 modules in the K-AT21 base can achieve module redundancy. At the same time, when the system loses power, the drive output of the final controlled device can "maintain the original state" or "safe" state.

[0052] The processor unit is deployed in 1#DCS cabinet, 3#DCS cabinet, 4#DCS cabinet, and 8#DCS cabinet. It communicates with I / O devices through the control network to collect field data and send control data. The processor unit communicates with the monitoring layer through the redundant system network (SNETA / B) to upload process data and diagnostic data. This system implements the main-hot standby mode by configuring the K-CU processor. Each pair of processors consists of two processor modules. Each processor module is an independent system, one of which is in working state and the other is in hot standby state. The standby processor module continuously updates the read information.

[0053] like Figure 2 As shown in the figure, when the working processor module exits operation due to a fault, the standby one automatically starts running without disturbance and manual intervention. The failure, removal, maintenance, etc. of one processor module does not affect the operation of the other one. At the same time, when the system has the power-off protection function turned on, if the main controller suddenly loses power, the project files and some key data that need to be maintained will be automatically saved. After powering on again, the main controller will automatically load the project stored in the controller, and restore the data items set to power-off protection to the state before the power-off.

[0054] The control network (CNET) topology diagram is as follows: Figure 3 As shown, the K-BUS module is used to realize redundant communication between process I / O cards and processor units, between the main cabinet and the expansion cabinet, and complete the transmission of real-time input and output data.

[0055] (2) Communication layer

[0056] The system network connects the control layer, monitoring layer and system peripherals to ensure reliable and efficient system communication. Figure 1As shown in the figure, the desalination control system adopts a redundant network configuration. The system network (SNET) is composed of a 100M high-speed redundant network, which connects operator station 1, operator station 2, operator station 3 and the monitoring layer with the control layer to complete the data monitoring of the entire system and respond to various operation requests of the operator. The system network (SNET) adopts a star structure. The desalination and desalination part, the desalination part, and the gate well water intake system are connected to the central node of the desalination control system as sub-nodes, that is, the 24-port switch redundantly arranged in the 0CPE61 cabinet. Among them, the desalination and desalination part (desalination + desalination part2) are arranged in a cabinet room farther away, and are connected to the 24-port switch through the 6 electrical and 2 optical switches in the 0CPE19 cabinet through optical fiber links.

[0057] The seawater desalination control system can also exchange data with the energy station DCS control system through the gateway.

[0058] (3) Monitoring layer

[0059] The monitoring layer collects and displays relevant operating information, and the operating personnel monitor and control the operating conditions of the unit based on it. All operations of the operating personnel on the operator station are performed through the keyboard and mouse, and the sequential control of each subsystem of the seawater desalination can be achieved through the DCS system.

[0060] like Figure 1 As shown in the figure, the entire production process and process can be monitored, managed and controlled through the three operator stations in the control room, and the automatic control and production management of the seawater desalination system can be completed. The three operator stations are backup for each other, ensuring that when one of them fails, the other can operate completely independently, thereby ensuring high reliability of control and data acquisition. The DCS can be configured, monitored, and programs read and downloaded through the control room engineer station.

[0061] The task of the operator station is to collect and display relevant operating information on the standard screen and user configuration screen, so that the operator can monitor and control the operating conditions of the unit. All operations of the operator on the operator station are performed through the keyboard and mouse. Each operator station is a station on the redundant communication bus, and each operator station has an independent redundant communication processing module, which is connected to the redundant communication bus SNET-A and SNET-B respectively.

[0062] The engineer station is mainly used for program development, system diagnosis, control system configuration, database and screen editing and modification. At the same time, through the communication bus, the system configuration information and related data of any distributed processing unit in the system can be called up, and the engineer can also download the configuration data from the engineer station to each distributed processing unit and operator station.

[0063] The history station can save all historical operation and fault record data for at least 1 year.

[0064] Through the design of the above three parts, the seawater desalination control system of the nuclear power plant mainly realizes the following functions:

[0065] 1) Process monitoring, control functions (including manual operation, automatic logic control and regulation control, etc.) and operation management;

[0066] 2) Provide computerized operation guidance and support to operators;

[0067] 3) Data communication;

[0068] 4) Alarm display and processing;

[0069] 5) Forms and checklists;

[0070] 6) Display and printing of variables: including variable monitoring, trend, data list, historical data display, alarm, log monitoring and display, and corresponding printing functions;

[0071] 7) Operation management;

[0072] 8) Data recording and archiving, etc.

[0073] Desalination projects involve thousands of process variables. The following measures are taken to ensure the availability, reliability and rapid response of the desalination control system in nuclear power plants:

[0074] Through fully redundant hot standby configuration of CPU modules, communication modules, power supplies, data communication networks, etc., the availability of the nuclear power plant's seawater desalination control system is guaranteed to be no less than 99.9%; when the system CPU is running at maximum load, the load rate does not exceed 60%, and the average load rate does not exceed 40%; the average load rate of the operator station and server unit does not exceed 40%.

[0075] By reducing the time of processor unit data call and optimizing the installation position of I / O cards, the data communication load of the communication network is ensured to be less than 40% on average for token ring and less than 20% on average for Ethernet under the busiest conditions.

[0076] The seawater desalination control system of a nuclear power plant also includes an ultrafiltration subsystem, a primary reverse osmosis subsystem, and a secondary reverse osmosis subsystem.

[0077] (1) Ultrafiltration subsystem

[0078] The ultrafiltration subsystem includes the connected ultrafiltration water pump, self-cleaning filter, ultrafiltration device, and ultrafiltration water tank. The ultrafiltration device system is divided into 3 groups. A self-cleaning filter is set before entering the ultrafiltration device. Its main function is to filter impurities in the water and protect the ultrafiltration membrane from damage. The ultrafiltration device system is equipped with 4 self-cleaning filters, 3 for use and 1 for backup, which can also be used at the same time.

[0079] The ultrafiltration device is used to remove suspended matter, colloids, etc. in water. Each group of 5 ultrafiltration devices operates in parallel, and the 3 groups of ultrafiltration device systems operate in parallel as units, with a total of 15 ultrafiltration devices.

[0080] Two ultrafiltration water tanks are set behind the ultrafiltration device to store ultrafiltration product water. The ultrafiltration product water supplies the reverse osmosis system with water.

[0081] Ultrafiltration device operation description: The operation of the ultrafiltration device is automatically controlled by the front and rear pressure difference or the turbidity of the water outlet, and participates in the operation control of the reverse osmosis device. The water output of the ultrafiltration device is slightly greater than the water intake of the first-stage reverse osmosis device. The two are regulated by the ultrafiltration water tank and the ultrafiltration water tank liquid level will not drop gradually.

[0082] The operation of the ultrafiltration device is directly related to the liquid level in the ultrafiltration water tank and the output of the ultrafiltration water inlet pump. When the operating conditions of the various components of the system drift due to temperature and other reasons, the ultrafiltration water production and the first-stage reverse osmosis water inlet may not match, and the liquid level in the ultrafiltration water tank may continue to decrease. At this time, the ultrafiltration water feed pump automatically increases its output through frequency conversion to increase the water production of the ultrafiltration device until the pump is stopped when the ultrafiltration water tank is at a high liquid level or frequency conversion is used to maintain the liquid level when the liquid level is high.

[0083] When the ultrafiltration tank has a low liquid level, 13 sets of ultrafiltration devices are put into operation; if the ultrafiltration tank liquid level continues to decrease, 15 sets of ultrafiltration devices are started in sequence until all are put into operation; if the liquid level does not rise at this time, the ultrafiltration water inlet pump is frequency-controlled to quickly increase the ultrafiltration tank liquid level, otherwise the subsequent equipment may be shut down. When the liquid level reaches the ultrafiltration tank high level, the ultrafiltration devices are shut down one by one according to the procedure.

[0084] (2) Primary reverse osmosis subsystem

[0085] The water produced by the primary reverse osmosis subsystem must meet the water quality and quantity requirements of the secondary reverse osmosis system source water, and mainly includes the connected primary reverse osmosis water pump, primary reverse osmosis safety filter, primary reverse osmosis high-pressure pump, primary reverse osmosis device, and primary fresh water tank.

[0086] There are 6 first-stage reverse osmosis water pumps in total, 5 in use and 1 as a spare.

[0087] The function of the primary reverse osmosis security filter is to intercept particles larger than 5μm in the effluent of the pretreatment system and prevent them from entering the primary reverse osmosis system. There are 5 primary reverse osmosis security filters, corresponding to 5 sets of primary reverse osmosis devices.

[0088] The function of the first-stage reverse osmosis high-pressure pump is to provide sufficient water inlet pressure for the first-stage reverse osmosis device. There are 5 first-stage reverse osmosis high-pressure pumps, corresponding to 5 sets of first-stage reverse osmosis devices respectively.

[0089] The primary reverse osmosis device is a unit system and operates in parallel, with a total of 5 sets. Two primary fresh water tanks are installed behind the primary reverse osmosis device to store the product water of the primary reverse osmosis device and provide water for the secondary reverse osmosis device.

[0090] Operation description of the primary reverse osmosis device: The primary reverse osmosis device is a unit system and is operated in parallel, with a total of 5 sets. During normal operation, the operation of the primary reverse osmosis device is put into operation one by one according to the liquid level of the primary fresh water tank (2 seats) and the start and stop of the secondary reverse osmosis device. When the liquid level of the primary fresh water tank is low, all the primary reverse osmosis devices are put into operation. When the liquid level of the primary fresh water tank is high, the primary reverse osmosis devices are shut down one by one. The number of primary reverse osmosis devices in operation is matched with the water consumption of the secondary reverse osmosis device through the primary fresh water tank.

[0091] When the liquid level of the primary fresh water tank drops to the set value, if the secondary reverse osmosis device is in operation, the primary reverse osmosis water feed pump and the primary reverse osmosis high-pressure pump are started one by one, and one set of the primary reverse osmosis device is put into operation. If the liquid level of the primary fresh water tank continues to drop, the primary reverse osmosis water feed pump, the primary reverse osmosis high-pressure pump, and the primary reverse osmosis device should be put into operation one by one. If the liquid level of the primary fresh water tank continues to drop, the primary reverse osmosis high-pressure pump should automatically increase the output through frequency conversion to increase the water output of the reverse osmosis device until the primary fresh water tank reaches a high liquid level and the pump is stopped or the high liquid level is maintained by frequency conversion.

[0092] When the first-stage reverse osmosis device is operating normally, it is not necessary to put all of them into operation. The first-stage reverse osmosis device automatically rotates and operates according to the set program, and the operating time of each first-stage reverse osmosis device is roughly equal.

[0093] The water produced by the primary reverse osmosis system must meet the water quality and quantity requirements of the secondary reverse osmosis system and the raw water of the plant users. The primary reverse osmosis devices are operated in parallel. The operator can selectively arrange the number of reverse osmosis devices in operation according to the actual water consumption or the equipment conditions of the reverse osmosis devices.

[0094] A high-pressure pump is installed in front of the first-stage reverse osmosis device. The high-pressure pump adopts frequency conversion control. Pressure switches are installed at the inlet and outlet of the high-pressure pump. When the pump inlet pressure is low or the outlet pressure is too high, an alarm will be issued and the pump will be stopped.

[0095] The first-stage reverse osmosis device is program-controlled and automatically monitored by DCS, and is equipped with automatic start, automatic flushing when starting and stopping.

[0096] The primary fresh water tank is part of the reverse osmosis system and participates in the overall automatic control and operation of the reverse osmosis system.

[0097] (3) Secondary reverse osmosis subsystem

[0098] The water produced by the secondary reverse osmosis subsystem is mainly used as the raw water of the desalted water treatment system, and mainly includes a secondary reverse osmosis feed water pump, a secondary reverse osmosis safety filter, a secondary reverse osmosis high-pressure pump, a secondary reverse osmosis device, and a secondary fresh water tank.

[0099] There are 4 secondary reverse osmosis water pumps in total, 3 in use and 1 as a backup, corresponding to 4 sets of secondary reverse osmosis devices respectively.

[0100] The function of the secondary reverse osmosis security filter is to intercept particles larger than 5μm in the effluent of the primary reverse osmosis system and prevent them from entering the secondary reverse osmosis system. There are 4 secondary reverse osmosis security filters, corresponding to 4 sets of secondary reverse osmosis devices.

[0101] The function of the secondary reverse osmosis high-pressure pump is to provide sufficient water inlet pressure for the secondary reverse osmosis device. There are 4 secondary reverse osmosis high-pressure pumps, corresponding to 4 sets of secondary reverse osmosis devices respectively.

[0102] The secondary reverse osmosis device is a unit system operating in parallel, with a total of 4 sets, 3 in use and 1 as a backup.

[0103] Operation description of secondary reverse osmosis device: The secondary reverse osmosis device is a unit system with parallel operation, with 4 sets in total, 3 in use and 1 as a standby. Under normal circumstances, 3 sets are in operation, and the number of operating sets can be reduced when the water consumption of the desalted water treatment system is reduced.

[0104] The operation of the secondary reverse osmosis device is also interlocked with the liquid level of the secondary fresh water tank (2 sets). When the liquid level is low, 3 sets are put into operation, and when the liquid level reaches the high level of the secondary fresh water tank, each set is shut down one by one.

[0105] When the liquid level in the secondary fresh water tank drops to the set value, three sets of secondary reverse osmosis feed water pump, secondary reverse osmosis high pressure pump and secondary reverse osmosis device are put into operation. If the liquid level in the secondary fresh water tank continues to drop, the secondary reverse osmosis feed water pump and secondary reverse osmosis high pressure pump will automatically increase the output through frequency conversion to increase the reverse osmosis water production and reach the set output until the secondary fresh water tank reaches a high liquid level and adjusts the frequency conversion or shuts down.

[0106] When the temperature drops and the water production of the secondary reverse osmosis device decreases, the secondary reverse osmosis water pump and the secondary reverse osmosis high-pressure pump use frequency conversion regulation to maintain a constant set water production of the secondary reverse osmosis membrane assembly.

[0107] This system is equipped with one set of standby trains, and the secondary reverse osmosis devices are automatically rotated according to the set program, so that the operating time of each set of secondary reverse osmosis devices is roughly equal.

[0108] The two-stage reverse osmosis devices are operated in parallel. The operator can selectively arrange the number of reverse osmosis devices to be operated according to the actual water consumption or the equipment conditions of the reverse osmosis devices. The state of the reverse osmosis devices can also be switched during the operation of the reverse osmosis devices.

[0109] A high-pressure pump is installed in front of the secondary reverse osmosis device. The high-pressure pump adopts frequency conversion control. Pressure switches are installed at the inlet and outlet of the high-pressure pump. When the pump inlet pressure is low or the outlet pressure is too high, an alarm will be issued and the pump will be stopped.

[0110] The secondary reverse osmosis device is program controlled and automatically monitored by DCS, and is equipped with automatic start, automatic flushing when starting and stopping.

[0111] In addition, if Figure 4 and Figure 5 As shown, based on the above nuclear power plant seawater desalination control system, the present application also provides a nuclear power plant seawater desalination control method, the main process flow includes ultrafiltration, primary reverse osmosis, and secondary reverse osmosis. The method specifically includes the following steps:

[0112] (1) Ultrafiltration step

[0113] The ultrafiltration subsystem with self-cleaning filter is used to remove suspended solids, colloids and other impurities in the water. The ultrafiltration device system is divided into 3 groups, each group contains 5 sets of ultrafiltration devices running in parallel, and is equipped with 4 self-cleaning filters, 3 in use and 1 in reserve or used simultaneously;

[0114] The ultrafiltration product water is stored in two ultrafiltration water tanks and supplied to the subsequent reverse osmosis system;

[0115] According to the ultrafiltration tank liquid level and the output of the ultrafiltration water inlet pump, the operation of the ultrafiltration device is adjusted by frequency conversion to ensure the stability of the ultrafiltration tank liquid level and increase or decrease the operating number of the ultrafiltration device when necessary.

[0116] (2) Primary reverse osmosis step

[0117] The product in the ultrafiltration water tank is further desalinated by the first-stage reverse osmosis device, which is a unit system and operates in parallel, with a total of 5 sets;

[0118] A first-stage reverse osmosis water supply pump, a first-stage reverse osmosis safety filter and a first-stage reverse osmosis high-pressure pump are installed to provide sufficient water inlet pressure and protect the first-stage reverse osmosis device;

[0119] According to the liquid level of the primary fresh water tank and the start and stop status of the secondary reverse osmosis device, the primary reverse osmosis device is put into or out of operation one by one, and the output of the primary reverse osmosis high-pressure pump is adjusted by frequency conversion to meet the needs of the secondary reverse osmosis system and plant users.

[0120] (3) Secondary reverse osmosis step

[0121] The product after the primary reverse osmosis is further desalinated by the secondary reverse osmosis device to obtain the raw water of the desalted water treatment system. The secondary reverse osmosis device is a unit system and operates in parallel, with a total of 4 sets, 3 in use and 1 in reserve;

[0122] A secondary reverse osmosis water feed pump, a secondary reverse osmosis safety filter and a secondary reverse osmosis high-pressure pump are installed to provide sufficient water inlet pressure and protect the secondary reverse osmosis device;

[0123] According to the liquid level of the secondary fresh water tank, the secondary reverse osmosis device is put into operation or withdrawn one by one, and the output of the secondary reverse osmosis feed water pump and the secondary reverse osmosis high-pressure pump is adjusted by frequency conversion to meet the water demand of the desalted water treatment system;

[0124] During the operation of the secondary reverse osmosis device, the status of the reverse osmosis devices is switched to ensure that the operation time of each set of secondary reverse osmosis device is roughly equal.

[0125] Furthermore, a high-pressure pump is arranged before the ultrafiltration, primary reverse osmosis and secondary reverse osmosis devices, the high-pressure pump adopts frequency conversion control, and alarms and stops the pump according to the situation of low inlet pressure or excessive outlet pressure;

[0126] Furthermore, the DCS system realizes automatic monitoring, program control and automatic flushing functions of the ultrafiltration, primary reverse osmosis and secondary reverse osmosis devices.

[0127] Furthermore, the method also includes the steps of regularly maintaining and servicing the ultrafiltration, primary reverse osmosis and secondary reverse osmosis devices to ensure the normal operation of each device and extend its service life.

[0128] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A seawater desalination control system for a nuclear power plant, characterized in that: include: The control layer is equipped with multiple DCS cabinets and relay cabinets, which are used to control the desalination and demineralization part, floating water intake facilities, chemical water electrical valve well water intake facilities, pretreatment part and another desalination and demineralization part. Each DCS cabinet and relay cabinet is equipped with I / O cards, processor units and control networks to achieve measurement, monitoring, control and protection of process and equipment; The communication layer uses a redundant network configuration to connect the control layer and the monitoring layer for system communication; The monitoring layer is equipped with an operator station and an engineer station, which are used to collect and display operating information and monitor and control the operating conditions of the unit.

2. The nuclear power plant seawater desalination control system according to claim 1, characterized in that: The control layer includes 10 DCS cabinets and 4 relay cabinets, and the specific configuration is as follows: DCS cabinets No. 1 to No. 5 and relay cabinets No. 1 to No. 2 are used to control the desalination and desalination parts and floating water intake facilities; No. 6 DCS cabinet is used to control the chemical water, electrical and gas valve well water intake facilities; DCS cabinets No. 7 to No. 8 and relay cabinet No. 3 are used to control the pre-processing part; DCS cabinets No. 9 to No. 10 and relay cabinet No. 4 are used to control another seawater desalination and demineralized water section; The monitoring and control signals of the floating water intake facility are connected to the No. 2 DCS cabinet by communication.

3. The nuclear power plant seawater desalination control system according to claim 1, characterized in that: I / O cards are deployed in each DCS cabinet to collect analog or digital signals from the field and convert these signals for processing by the main controller, or output the signals processed by the main controller to the field through each relay cabinet; for important signals with high availability and reliability requirements, redundant I / O configuration is adopted.

4. The nuclear power plant seawater desalination control system according to claim 1, characterized in that: The processor unit is deployed in some DCS cabinets and communicates with I / O devices through the control network to collect field data and send control data; The processor unit communicates with the monitoring layer through a redundant system network to upload process data and diagnostic data; The processor unit adopts the active-hot standby mode, and each pair of processors consists of two processor modules, one in working state and the other in hot standby state.

5. The nuclear power plant seawater desalination control system according to claim 1, characterized in that: The communication layer uses a 100M high-speed redundant network to form the system network, connecting the operator station, monitoring layer and control layer, completing data monitoring of the entire system, and responding to various operation requests from operators; the system network adopts a star structure, and each subsystem is connected to the switch on the system center node as a sub-node.

6. The nuclear power plant seawater desalination control system according to claim 1, characterized in that: The monitoring layer includes: Operator station, used to collect and display operating information, so that operators can monitor and control the operating conditions of the unit; Engineer station, used for program development, system diagnosis, control system configuration, and editing and modifying databases and screens.

7. The nuclear power plant seawater desalination control system according to claim 1, characterized in that: The system also includes: The ultrafiltration subsystem has an ultrafiltration water pump, a self-cleaning filter, an ultrafiltration device and an ultrafiltration water tank. The ultrafiltration device system is divided into 3 groups, each group contains at least 5 sets of ultrafiltration devices running in parallel, and a total of 15 sets of ultrafiltration devices are set. Two ultrafiltration water tanks are set behind the ultrafiltration devices; The primary reverse osmosis subsystem has a primary reverse osmosis water feed pump, a primary reverse osmosis safety filter, a primary reverse osmosis high-pressure pump, a primary reverse osmosis device and a primary fresh water tank. The primary reverse osmosis device is a unit system and operates in parallel, with a total of 5 sets; The secondary reverse osmosis subsystem has a secondary reverse osmosis water feed pump, a secondary reverse osmosis safety filter, a secondary reverse osmosis high-pressure pump, a secondary reverse osmosis device and a secondary fresh water tank. The secondary reverse osmosis device is a unit system and operates in parallel, with a total of 4 sets.

8. The seawater desalination control system for a nuclear power plant according to claim 7, characterized in that: The operation of the ultrafiltration device is automatically controlled by the front and rear pressure difference or the turbidity of the outlet water, and participates in the operation control of the first-stage reverse osmosis device; the operation of the first-stage reverse osmosis device is put into operation one by one according to the liquid level of the first-stage fresh water tank and the start and stop status of the second-stage reverse osmosis device; the operation of the second-stage reverse osmosis device is interlocked with the liquid level of the second-stage fresh water tank, and the number of reverse osmosis devices in operation is selectively arranged according to the actual water consumption or the equipment conditions of the reverse osmosis device.

9. The seawater desalination control system for a nuclear power plant according to claim 7, characterized in that: High-pressure pumps are installed in front of the ultrafiltration device, the first-stage reverse osmosis device and the second-stage reverse osmosis device. The high-pressure pumps are controlled by frequency conversion and alarm and stop the pump according to the low inlet pressure or excessive outlet pressure.

10. A method for controlling seawater desalination in a nuclear power plant, characterized in that: A nuclear power plant seawater desalination control system according to any one of claims 1 to 9, comprising: The impurities in the water are removed by the ultrafiltration subsystem, and the ultrafiltration product water is stored in the ultrafiltration water tank. The operation of the ultrafiltration device is adjusted by frequency conversion according to the ultrafiltration water tank liquid level and the output of the ultrafiltration water inlet pump; The product in the ultrafiltration water tank is further desalinated by the first-stage reverse osmosis device. The first-stage reverse osmosis device is a unit system and is operated in parallel. A first-stage reverse osmosis water pump, a first-stage reverse osmosis safety filter and a first-stage reverse osmosis high-pressure pump are set. According to the liquid level of the first-stage fresh water tank and the start and stop status of the second-stage reverse osmosis device, the first-stage reverse osmosis device is put into operation or withdrawn one by one, and the output of the first-stage reverse osmosis high-pressure pump is adjusted by frequency conversion. The product after the primary reverse osmosis is further desalinated by a secondary reverse osmosis device to obtain raw water for the desalted water treatment system. A secondary reverse osmosis water feed pump, a secondary reverse osmosis safety filter and a secondary reverse osmosis high-pressure pump are set. According to the liquid level of the secondary fresh water tank, the secondary reverse osmosis device is put into or out of operation one by one, and the output of the secondary reverse osmosis water feed pump and the secondary reverse osmosis high-pressure pump is adjusted by frequency conversion.

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