Multi-stage dynamic oxygenation control system and method for water supply system of nuclear power unit

Abstract

The invention discloses a multistage dynamic oxygenation control system and method for a water supply system of a nuclear power unit. An outlet of the low-pressure cylinder is communicated with an inlet of the high-pressure cylinder through a condensed water oxygenation point, a condensed water flow meter, a deaerator inlet dissolved oxygen meter, a deaerator, a main water supply oxygenation point, a water supply flow meter, a steam generator inlet dissolved oxygen meter and a steam generator outlet dissolved oxygen meter in sequence; an outlet of a high-pressure cylinder is communicated with an inlet of a low-pressure cylinder through a steam-water separator, the shell side of a first-stage reheater and a second-stage reheater, and a reheater steam extraction pipeline is communicated with the shell side of a fourth low-pressure heater through an oxygenation point of the first-stage reheater, the pipe side of the first-stage reheater, the pipe side of a third low-pressure heater and a low-pressure heater drainage pump in sequence. And the fifth low-pressure heater steam extraction pipeline is communicated with the pipe side of the third low-pressure heater through the low-pressure heater steam extraction oxygenation point, the pipe side of the fifth low-pressure heater and the pipe side of the fourth low-pressure heater in sequence. According to the system and method, the problem that the oxidation film structure is damaged due to the fact that the local oxygen concentration is too high or corrosion is aggravated due to the fact that the local oxygen concentration is too low can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of water chemistry control of nuclear power units, and relates to a multi-stage dynamic oxygenation control system and method for a water supply system of a nuclear power unit. Background Art

[0002] The traditional feedwater system of PWR nuclear power units adopts AVT(R) water chemistry with hydrazine added for deoxygenation to reduce the oxidation corrosion of the metal materials of the unit. However, for high-parameter fourth-generation nuclear reactor nuclear power units such as high-temperature gas-cooled reactors and sodium-cooled fast reactors, the flow-accelerated corrosion (FAC) of the feedwater can easily lead to blockage of the steam generator throttling components and deposition of heat transfer tubes. The use of feedwater oxygenation treatment can not only form a dense oxide film on the inner wall of the feedwater pipeline and evaporator, slow down the flow-accelerated corrosion rate of the feedwater system and condensate system, and effectively reduce the corrosion and scaling rate of the evaporator, but also eliminate the deposition problem of Fe3O4 at the throttle valve of the evaporator heat transfer tube, reduce the pressure difference increase rate of the evaporator on the DC side of the nuclear power unit, and eliminate the temperature deviation between tubes caused by throttle valve scaling. At the same time, feedwater oxygenation treatment can also extend the fine treatment operation cycle and has good economic efficiency.

[0003] The most commonly used oxygenation methods for feed water oxygenation are pure oxygen, compressed air and oxygen-enriched water. The oxygenation point generally adopts one-point oxygenation of condensate, or two-point oxygenation of main feed water, or three-point oxygenation of high-pressure hydrophobic oxygenation. However, the above oxygenation methods have problems such as lack of protection of steam-water separators, insufficient protection of low-pressure heaters, and poor uniformity of oxygenation. Under normal circumstances, flow accelerated corrosion (FAC) is more likely to occur in the temperature range of 120-180°C. Generally, the low-pressure heater of a nuclear power unit is about 5 levels, and the water temperature varies in the range of 20-150°C. Especially in the last two low-pressure heaters, the condensate temperature in the gate is 100-150°C, and the shell side cycle temperature is in the range of 120-180°C, which is highly overlapped with the temperature range where flow accelerated corrosion (FAC) is prone to occur. Two-point or three-point oxygenation can only protect the inner wall of the low-pressure heat exchange tube, and has no protective effect on the outer wall of the low-pressure heat exchange tube. However, the low-pressure heater has a huge heat exchange area, which undoubtedly further aggravates the flow accelerated corrosion (FAC) effect.

[0004] The current oxygenation method has a long pipeline distance between the dissolved oxygen measuring point and the oxygen addition point, which may cause the local oxygen concentration to be too high, resulting in damage to the oxide film structure, or too low, resulting in increased corrosion. The control relies on manual adjustment, or just a simple feedforward and feedback adjustment, which cannot adapt to unit load fluctuations and changes in water quality parameters, and has insufficient dynamic response capabilities. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a multi-stage dynamic oxygenation control system and method for a nuclear power unit water supply system, which can avoid the problem of excessively high local oxygen concentration leading to damage to the oxide film structure, or excessively low local oxygen concentration leading to increased corrosion.

[0006] To achieve the above object, the present invention discloses a multi-stage dynamic oxygenation control system for a water supply system of a nuclear power unit, comprising a low-pressure cylinder, a high-pressure cylinder, a reheater steam extraction pipeline and a No. 5 low-pressure heater steam extraction pipeline;

[0007] The outlet of the low-pressure cylinder is connected to the inlet of the high-pressure cylinder via the condenser, the condensate oxygenation point, the condensate flowmeter, the shell side of the No. 3 low-pressure heater, the shell side of the No. 4 low-pressure heater, the shell side of the No. 5 low-pressure heater, the dissolved oxygen meter at the deaerator inlet, the deaerator, the main feed water oxygenation point, the main feed water pump, the feed water flowmeter, the high-pressure heater, the steam generator inlet dissolved oxygen meter, the steam generator, and the steam generator outlet dissolved oxygen meter. The outlet of the high-pressure cylinder is connected to the inlet of the low-pressure cylinder via the steam-water separator, the shell side of the first-stage reheater and the second-stage reheater. The reheater steam extraction pipeline is connected to the shell side of the No. 4 low-pressure heater via the first-stage reheater oxygenation point, the tube side of the first-stage reheater, the tube side of the No. 3 low-pressure heater and the low-pressure heater drain pump in sequence. The No. 5 low-pressure heater steam extraction pipeline is connected to the tube side of the No. 3 low-pressure heater via the low-pressure heater steam extraction oxygenation point, the tube side of the No. 5 low-pressure heater and the tube side of the No. 4 low-pressure heater in sequence.

[0008] Furthermore, the outlet of the low-pressure cylinder is connected to the inlet of the high-pressure cylinder via the condenser, the condensate oxygenation point, the condensate pump, the fine treatment device, the condensate flowmeter, the combined low-pressure heaters No. 1 and 2, the shell side of the low-pressure heater No. 3, the shell side of the low-pressure heater No. 4, the shell side of the low-pressure heater No. 5, the dissolved oxygen meter at the deaerator inlet, the deaerator, the main feed water oxygenation point, the main feed water pump, the feed water flowmeter, the high-pressure heater, the dissolved oxygen meter at the steam generator inlet, the steam generator, and the dissolved oxygen meter at the steam generator outlet.

[0009] Furthermore, it also includes a control module, which is connected to the condensate pump, the condensate flowmeter, the low-pressure heater drain pump, the main feed water pump, the feed water flowmeter, the condensate oxygenation point, the low-pressure heater extraction steam oxygenation point, the first-stage reheater oxygenation point, the main feed water oxygenation point, the deaerator inlet dissolved oxygen meter, the steam generator inlet dissolved oxygen meter and the steam generator outlet dissolved oxygen meter.

[0010] Furthermore, there are two dissolved oxygen meters at the steam generator outlet, and the two dissolved oxygen meters at the steam generator outlet are operated in a one-for-standby and one-for-use mode.

[0011] Furthermore, the oxygenation medium at the condensate oxygenation point, the low-pressure steam extraction oxygenation point, the first-stage reheater oxygenation point and the main feed water oxygenation point is desalted water, compressed air, oxygen cylinders or oxygen-enriched water in the power plant.

[0012] The present invention discloses a multi-stage dynamic oxygenation control method for a water supply system of a nuclear power unit, comprising:

[0013] The amount of oxygen added at the condensate oxygenation point is 40% of the amount of oxygen required for the system OT operation;

[0014] The amount of oxygen added at the low-pressure extraction steam oxygenation point is less than or equal to 20% of the amount of oxygen required for the system OT operation;

[0015] The amount of oxygen added at the oxygen addition point of the first stage reheater is less than or equal to 20% of the amount of oxygen required for the system OT operation;

[0016] The amount of oxygen added at the main feed water oxygenation point is less than or equal to 20% of the amount of oxygen required for the system OT operation.

[0017] Furthermore, the amount of oxygen added at the condensate oxygenation point is controlled according to the condensate flow rate information measured by the condensate flowmeter.

[0018] Furthermore, the extraction steam flow of No. 4 LP heater and No. 5 LP heater controls the amount of oxygen added at the LP heater extraction steam oxygenation point.

[0019] Furthermore, the amount of oxygen added at the oxygen addition point of the first-stage reheater is controlled according to the reheater extraction steam flow rate of the first-stage reheater.

[0020] Furthermore, when the dissolved oxygen content measured by the dissolved oxygen meter at the steam generator inlet or the dissolved oxygen meter at the steam generator outlet reaches a preset protection value, the control module issues a specified stop to oxygen addition and triggers an alarm at the same time.

[0021] Furthermore, the control module adopts PID method for control.

[0022] The present invention has the following beneficial effects:

[0023] In the specific operation, the multi-stage dynamic oxygenation control system and method of the nuclear power unit feed water system described in the present invention are provided with 4 oxygenation points at the inlet of the condensate pump, the extraction side inlet of the No. 5 low-pressure heater, the extraction side inlet of the first-stage reheater and the outlet of the deaerator, wherein the oxygenation point at the inlet of the condensate pump is used as the basic oxygenation point of the system, providing 40% of the oxygen required for the OT operation of the system, and the other 3 oxygenation points are used as the subsequent oxygenation points of the system, and each level bears 20% of the oxygenation amount, thereby realizing the protection of the low-pressure heater tube side, shell side and steam-water separation reheater which are prone to flow accelerated corrosion. In terms of control mode, the comprehensive control logic of multi-signal collaborative feedback + feedforward compensation + adaptive algorithm is adopted, which can realize accurate and balanced control of the system oxygenation amount, and improve the response speed and stability of the oxygenation system when the system operating conditions fluctuate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 It is a structural diagram of the present invention.

[0026] Among them, 1 is the low-pressure cylinder, 2 is the condenser, 3 is the condensate pump, 4 is the fine treatment device, 5 is the condensate flowmeter, 6 is the No. 1 and 2 combined low-pressure heaters, 7 is the No. 3 low-pressure heater, 8 is the low-pressure heater drain pump, 9 is the No. 4 low-pressure heater, 10 is the No. 5 low-pressure heater, 11 is the deaerator, 12 is the main feed water pump, 13 is the feed water flowmeter, 14 is the high-pressure heater, 15 is the steam generator, 16 is the high-pressure cylinder, 17 is the steam-water separator, 18 is the first stage reheater, 19 is the second stage reheater, 20 is the reheater extraction steam pipeline, 21 is the No. 5 low-pressure heater extraction steam pipeline, 31 is the condensate oxygenation point, 32 is the low-pressure heater extraction steam oxygenation point, 33 is the first stage reheater oxygenation point, 34 is the main feed water oxygenation point, 41 is the deaerator inlet dissolved oxygen meter, 42 is the steam generator inlet dissolved oxygen meter, 43 is the steam generator outlet dissolved oxygen meter, and 50 is the control module. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0029] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0030] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0031] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0032] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0035] Embodiment 1

[0036] refer to Figure 1The multi-stage dynamic oxygenation control system of the feed water system of the nuclear power unit of the present invention comprises a low-pressure cylinder 1, a condenser 2, a condensate pump 3, a fine treatment device 4, a condensate flowmeter 5, a No. 1 and No. 2 combined low-pressure heater 6, a No. 3 low-pressure heater 7, a low-pressure heater drain pump 8, a No. 4 low-pressure heater 9, a No. 5 low-pressure heater 10, a deaerator 11, a main feed water pump 12, a feed water flowmeter 13, a high-pressure heater 14, a steam generator 15, a high-pressure cylinder 16, a steam-water separator 17, a first-stage reheater 18, a second-stage reheater 19, a reheater steam extraction pipeline 20, a No. 5 low-pressure heater steam extraction pipeline 21, a condensate oxygenation point 31, a low-pressure heater steam extraction oxygenation point 32, a first-stage reheater oxygenation point 33, a main feed water oxygenation point 34, a deaerator inlet dissolved oxygen meter 41, a steam generator inlet dissolved oxygen meter 42, a steam generator outlet dissolved oxygen meter 43 and a control module 50;

[0037] The outlet of the low-pressure cylinder 1 passes through the condenser 2, the condensate oxygenation point 31, the condensate pump 3, the polishing device 4, the condensate flowmeter 5, the No. 1 and No. 2 combined low-pressure heaters 6, the shell side of the No. 3 low-pressure heater 7, the shell side of the No. 4 low-pressure heater 9, the shell side of the No. 5 low-pressure heater 10, the deaerator inlet dissolved oxygen meter 41, the deaerator 11, the main feed water oxygenation point 34, the main feed water oxygenation point 34, the main feed water pump 12, the feed water flowmeter 13, the high-pressure heater 14, the steam generator inlet dissolved oxygen meter 42, the steam generator 15, the steam generator outlet dissolved oxygen meter 43 and the high-pressure cylinder 1. 6, the outlet of the high-pressure cylinder 16 is connected to the inlet of the low-pressure cylinder 1 via the steam-water separator 17, the shell side of the first-stage reheater 18 and the second-stage reheater 19, the reheater extraction steam pipeline 20 is connected to the shell side of the No. 4 low-pressure heater 9 via the first-stage reheater oxygenation point 33, the tube side of the first-stage reheater 18, the tube side of the No. 3 low-pressure heater 7 and the low-pressure heater drain pump 8 in sequence, the No. 5 low-pressure heater extraction steam pipeline 21 is connected to the tube side of the No. 3 low-pressure heater 7 via the low-pressure heater extraction steam oxygenation point 32, the tube side of the No. 5 low-pressure heater 10 and the tube side of the No. 4 low-pressure heater 9 in sequence.

[0038] The oxygenation medium for the four oxygenation points is preferably desalted water from a power plant, followed by compressed air, oxygen cylinders or oxygen-enriched water.

[0039] There are two dissolved oxygen meters 43 at the steam generator outlet. The dissolved oxygen signal is divided into two channels and sent to the control module 50. When the logic is normal, the higher value between the two is taken. When a steam generator outlet dissolved oxygen meter 43 or a channel signal fails, it automatically switches to another channel signal value.

[0040] Embodiment 2

[0041] The specific working process of the present invention is:

[0042] 1) Main control signal selection (feedback quantity)

[0043] Signal 1: Real-time dissolved oxygen concentration, using a high-precision oxygen sensor with an accuracy of ±0.1ppb, located at least 5 meters downstream of the oxygenation point.

[0044] Signal 2: Target oxygen concentration setting value. Dynamically adjusted according to unit load (10%-100%) and water flow rate, when the unit power is lower than 10%, the control module 50 automatically stops oxygenation.

[0045] 2) Auxiliary control signal selection (feedforward quantity)

[0046] Signal 1: water flow rate. The amount of oxygen added at the condensate oxygenation point 31 is 40% of the amount of oxygen required for the system OT operation, and the amount of oxygen added is provided by the condensate flowmeter 5 with a flow input signal.

[0047] Signal 2: Extraction steam flow. The oxygen addition amount at the low-pressure steam extraction oxygenation point 32 shall not exceed 20% of the oxygen required for the system OT operation. The oxygen addition amount is provided by the extraction steam flow of No. 4 low-pressure heater 9 and No. 5 low-pressure heater 10 to provide flow input signals.

[0048] Signal 3: The oxygen addition amount at the oxygen addition point 33 of the first stage reheater does not exceed 20% of the oxygen amount required for the system OT operation. The oxygen addition amount is provided by the reheater extraction steam flow of the first stage reheater 18 as a flow input signal.

[0049] Signal 4: Unit load signal. Changes in unit load (0%-100%) will affect changes in dissolved oxygen in the feed water and serve as an auxiliary control signal.

[0050] Signal 5: oxygenation device valve opening signal. The oxygenation device valve opening (0%-100%) and its linearity, valve speed and other inherent hysteresis are used as auxiliary control signals to correct the control logic.

[0051] 3) Control logic

[0052] PID controller optimization: Split-range PID control is adopted to divide the deviation of dissolved oxygen concentration in water into three intervals: when the deviation between the actual value and the set value of dissolved oxygen concentration is >5ppb, the fast response mode is enabled (the proportional gain is increased by 50%); when the deviation is 2-5ppb, conventional PID adjustment is adopted; when the deviation is <2ppb, the control system is mainly based on integral action to prevent over-adjustment.

[0053] Fuzzy adaptive logic: Dynamically adjust PID parameters according to the unit flow and load change rate. When the load or flow increases suddenly, the integral time constant is increased in advance; when the load or flow drops suddenly, the integral time constant is reduced in advance.

[0054] 4) Grading system control

[0055] Dynamic allocation of three-level oxygenation points:

[0056] Condensate oxygenation point 31: bears the basic oxygen content (40% of the total demand) and is used for rough adjustment of the system oxygen content;

[0057] Low-pressure steam extraction oxygenation point 32: used for the dissolved oxygen consumption of the low-pressure steam side protection, and at the same time compensates for the loss of dissolved oxygen consumption of condensate at the upstream primary oxygenation point (not exceeding 20% ​​of the total demand);

[0058] First stage reheater oxygenation point 33: used for the dissolved oxygen consumption of the first stage reheater 18 extraction side protection, and to compensate for the loss of dissolved oxygen consumption of condensate at the upstream first stage oxygenation point (not exceeding 20% ​​of the total demand);

[0059] Main feed water oxygenation point 34: precise fine-tuning (not exceeding 20% ​​of total demand) provides oxygen consumption for high-pressure water heater 14 and upstream and downstream pipelines, while suppressing fluctuations in dissolved oxygen at the terminal.

[0060] Priority logic: When a certain oxygenation point reaches the valve position limit, the redundant amount is automatically allocated to the upper level oxygenation point.

[0061] Protection logic: When the dissolved oxygen content measured by the steam generator inlet dissolved oxygen meter 42 or the steam generator outlet dissolved oxygen meter 43 reaches a preset protection value, the control module 50 issues a designated stop for oxygen addition and triggers an alarm at the same time.

[0062] Embodiment 3

[0063] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the multi-stage dynamic oxygenation control method for the water supply system of a nuclear power unit are implemented. The memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk memory, etc. The processor, the network interface, and the memory are interconnected through an internal bus. The internal bus may be an industrial standard architecture bus, a peripheral component interconnection standard bus, an extended industrial standard architecture bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs. Specifically, the program may include a program code, and the program code includes computer operation instructions. The memory may include a memory and a non-volatile memory, and provide instructions and data to the processor.

[0064] Embodiment 4

[0065] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the multi-stage dynamic oxygenation control method of the water supply system of the nuclear power unit are implemented. Specifically, the computer-readable storage medium includes, but is not limited to, for example, a volatile memory and / or a non-volatile memory. The volatile memory may include a random access memory (RAM) and / or a cache memory, etc. The non-volatile memory may include a read-only memory (ROM), a hard disk, a flash memory, an optical disk, a magnetic disk, etc.

[0066] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0067] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0068] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0069] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0070] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

[0071] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0072] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A multi-stage dynamic oxygenation control system for a water supply system of a nuclear power unit, characterized in that: It comprises a low-pressure cylinder (1), a high-pressure cylinder (16), a reheater steam extraction pipeline (20) and a No. 5 low-pressure heater steam extraction pipeline (21); The outlet of the low-pressure cylinder (1) is connected to the inlet of the high-pressure cylinder (16) through the condenser (2), the condensate oxygenation point (31), the condensate flowmeter (5), the shell side of the No. 3 low-pressure heater (7), the shell side of the No. 4 low-pressure heater (9), the shell side of the No. 5 low-pressure heater (10), the dissolved oxygen meter (41) at the inlet of the deaerator, the deaerator (11), the main feed water oxygenation point (34), the main feed water pump (12), the feed water flowmeter (13), the high-pressure heater (14), the steam generator inlet dissolved oxygen meter (42), the steam generator (15), and the steam generator outlet dissolved oxygen meter (43). The high-pressure cylinder (16) ) is connected to the inlet of the low-pressure cylinder (1) via the steam-water separator (17), the shell side of the first-stage reheater (18) and the second-stage reheater (19); the reheater steam extraction pipeline (20) is connected to the shell side of the No. 4 low-pressure heater (9) via the first-stage reheater oxygenation point (33), the tube side of the first-stage reheater (18), the tube side of the No. 3 low-pressure heater (7) and the low-pressure heater drain pump (8); the No. 5 low-pressure heater steam extraction pipeline (21) is connected to the tube side of the No. 3 low-pressure heater (7) via the low-pressure heater steam extraction oxygenation point (32), the tube side of the No. 5 low-pressure heater (10) and the tube side of the No. 4 low-pressure heater (9) in sequence.

2. The multi-stage dynamic oxygenation control system for the water supply system of a nuclear power unit according to claim 1, characterized in that: The outlet of the low-pressure cylinder (1) is connected to the inlet of the high-pressure cylinder (16) in sequence through the condenser (2), the condensate oxygenation point (31), the condensate pump (3), the polishing device (4), the condensate flowmeter (5), the No. 1 and No. 2 combined low-pressure heaters (6), the shell side of the No. 3 low-pressure heater (7), the shell side of the No. 4 low-pressure heater (9), the shell side of the No. 5 low-pressure heater (10), the deaerator inlet dissolved oxygen meter (41), the deaerator (11), the main feed water oxygenation point (34), the main feed water pump (12), the feed water flowmeter (13), the high-pressure heater (14), the steam generator inlet dissolved oxygen meter (42), the steam generator (15), and the steam generator outlet dissolved oxygen meter (43); The invention also comprises a control module (50), wherein the control module (50) is connected to a condensate pump (3), a condensate flowmeter (5), a low-pressure steam heater drain pump (8), a main feed water pump (12), a feed water flowmeter (13), a condensate oxygenation point (31), a low-pressure steam heater extraction oxygenation point (32), a first-stage reheater oxygenation point (33), a main feed water oxygenation point (34), a deaerator inlet dissolved oxygen meter (41), a steam generator inlet dissolved oxygen meter (42) and a steam generator outlet dissolved oxygen meter (43).

3. The multi-stage dynamic oxygenation control system for the water supply system of a nuclear power unit according to claim 1, characterized in that: The number of the steam generator outlet dissolved oxygen meters (43) is two, and the two steam generator outlet dissolved oxygen meters (43) adopt an operation mode of one standby and one in use.

4. The multi-stage dynamic oxygenation control system for a water supply system of a nuclear power unit according to claim 1, characterized in that: The oxygenation medium at the condensate oxygenation point (31), the low-pressure steam extraction oxygenation point (32), the first-stage reheater oxygenation point (33) and the main feed water oxygenation point (34) is desalted water from the power plant, compressed air, oxygen cylinders or oxygen-enriched water.

5. A multi-stage dynamic oxygenation control method for a water supply system of a nuclear power unit, characterized in that: The multi-stage dynamic oxygenation control system for the water supply system of a nuclear power unit according to claim 2 comprises: The amount of oxygen added at the condensate oxygenation point (31) is 40% of the amount of oxygen required for the system OT operation; The amount of oxygen added at the low-pressure extraction steam oxygenation point (32) is less than or equal to 20% of the amount of oxygen required for the system OT operation; The amount of oxygen added at the oxygen addition point (33) of the first stage reheater is less than or equal to 20% of the amount of oxygen required for the OT operation of the system; The amount of oxygen added at the main feedwater oxygenation point (34) is less than or equal to 20% of the amount of oxygen required for the system OT operation.

6. The multi-stage dynamic oxygenation control method for a water supply system of a nuclear power unit according to claim 4, characterized in that: The amount of oxygen added at the condensate oxygenation point (31) is controlled according to the condensate flow rate information measured by the condensate flowmeter (5).

7. The multi-stage dynamic oxygenation control method for a water supply system of a nuclear power unit according to claim 4, characterized in that: The steam extraction flow rate of the No. 4 low-pressure heater (9) and the No. 5 low-pressure heater (10) controls the amount of oxygen added at the low-pressure heater extraction steam oxygen addition point (32).

8. The multi-stage dynamic oxygenation control method for a water supply system of a nuclear power unit according to claim 4, characterized in that: The amount of oxygen added at the first-stage reheater oxygen addition point (33) is controlled according to the reheater extraction steam flow rate of the first-stage reheater (18).

9. The multi-stage dynamic oxygenation control method for a water supply system of a nuclear power unit according to claim 4, characterized in that: When the dissolved oxygen content measured by the dissolved oxygen meter (42) at the steam generator inlet or the dissolved oxygen meter (43) at the steam generator outlet reaches a preset protection value, the control module (50) issues a designated signal to stop oxygen addition and triggers an alarm at the same time.

10. The multi-stage dynamic oxygenation control method for a water supply system of a nuclear power unit according to claim 4, characterized in that: The control module (50) uses a PID method for control.

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