Degassing system and degassing method for nuclear reactor coolant

Abstract

The invention belongs to the technical field of nuclear power, and discloses a degassing system and a degassing method for a nuclear reactor coolant. The degassing system of the nuclear reactor coolant comprises a hollow fiber membrane degassing device, a coolant storage device connected with a coolant input end of the hollow fiber membrane degassing device, and a vacuum device connected with a nitrogen output end of the hollow fiber membrane degassing device, the hollow fiber membrane degassing device comprises at least one vertically arranged degasser; the degasser comprises a coolant channel and a membrane wire channel which are arranged in the vertical direction; coolant flows in the coolant channel from bottom to top, and nitrogen flows in the membrane filament channel from top to bottom. The hydrophobic characteristic of the hollow fiber membrane is utilized, and the membrane degassing technology is combined with vacuum suction and nitrogen purging to achieve the deep degassing target. According to the degassing system for the nuclear reactor coolant, the coolant flows from bottom to top in cooperation with nitrogen flowing from top to bottom, so that the whole system operates reliably for a long time, and energy consumption is optimized.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power technology, and specifically relates to a degassing system and method for nuclear reactor coolant. Background Technology

[0002] During the operation of pressurized water reactor nuclear power plants, the reactor coolant often contains dissolved oxygen, hydrogen, and some radioactive inert gases. High concentrations of these gases can exacerbate corrosion of pipes and equipment, and also increase the radioactivity level of the reactor coolant, impacting operational safety and maintenance costs. Traditional solutions often employ thermal degassing, requiring large degassing towers or spraying and steam-water separation under high temperature and pressure conditions. This results in large overall equipment size and high energy consumption. In special environments with limited space and energy, or in tilted or swaying conditions, traditional processes struggle to meet compactness and safety requirements. Summary of the Invention

[0003] In view of the technical problems existing in the prior art, the purpose of this invention is to provide a degassing system for nuclear reactor coolant.

[0004] Another objective of this invention is to provide a method for degassing a nuclear reactor coolant, utilizing the aforementioned nuclear reactor coolant degassing system.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A degassing system for a nuclear reactor coolant includes a hollow fiber membrane degassing device, a coolant storage device connected to the coolant input end of the hollow fiber membrane degassing device, and a vacuum device connected to the nitrogen output end of the hollow fiber membrane degassing device. The hollow fiber membrane degassing device includes at least one vertically arranged degasser. The degasser includes a coolant channel and a membrane fiber channel arranged in a vertical direction. The coolant flows from bottom to top in the coolant channel, and the nitrogen flows from top to bottom in the membrane fiber channel.

[0006] Furthermore, the hollow fiber membrane degassing device includes a multi-stage degassing unit connected by pipelines.

[0007] Furthermore, in the multi-stage degassing device, each stage of the degassing device is connected in parallel via a nitrogen flow line; in the multi-stage degassing device, each stage of the degassing device is connected in series via a coolant flow line.

[0008] Furthermore, each stage of the multi-stage degasser is equipped with independent inlet and outlet valves, allowing each stage of the degasser to operate independently. Specifically, valves are provided at the coolant inlet, coolant outlet, nitrogen inlet, and nitrogen outlet of the degasser. Pipelines connecting the coolant outlet and coolant inlet of the degasser are installed, and valves are installed on these pipelines.

[0009] Furthermore, the degasser includes a shell and a hollow fiber membrane column filled inside; the hollow fiber membrane column is composed of a plurality of hollow fiber membrane filaments.

[0010] Furthermore, the hollow fiber membrane column and the outer shell form three independent chambers, including a middle chamber formed by the side surface of the hollow fiber membrane column and the middle inner surface of the outer shell, an upper chamber formed by the upper end face of the hollow fiber membrane column and the upper inner surface of the outer shell, and a lower chamber formed by the lower end face of the hollow fiber membrane column and the lower inner surface of the outer shell; sealing components are respectively provided at the connection between the middle chamber, the upper chamber, and the lower chamber.

[0011] Furthermore, the hollow fiber membrane column is a hollow cylindrical structure; the upper and lower end faces of the hollow fiber membrane column are annular rings including coolant channel ports and several membrane fiber channel ports; the inner circle of the annular ring is the coolant channel port; the membrane fiber channel ports are distributed on the ring.

[0012] Furthermore, the degasser includes a nitrogen inlet and a coolant outlet located at the upper part of the outer shell, a nitrogen outlet and a coolant inlet located at the lower part of the outer shell; the coolant outlet and the coolant inlet are respectively tightly connected to the upper and lower ports of the coolant channel of the hollow fiber membrane column; the nitrogen inlet and the nitrogen outlet are respectively connected to the upper and lower chambers.

[0013] Furthermore, the membrane fiber channel includes a channel formed on the inner side of the hollow fiber membrane fiber; the coolant channel includes the hollow portion of the hollow fiber membrane column, the gap between the hollow fiber membrane fibers, and the central chamber.

[0014] Furthermore, the outer shell is an austenitic stainless steel shell; the pore size of the hollow fiber membrane is nanoscale.

[0015] Furthermore, the number of degassers in the multi-stage degassing system is greater than or equal to 2.

[0016] Furthermore, both the coolant output end and the coolant input end of the hollow fiber membrane degassing device are connected to a dissolved gas analysis device.

[0017] Furthermore, the coolant output end of the hollow fiber membrane degassing device is connected to a coolant collection device; the nitrogen output end of the hollow fiber membrane degassing device is connected to a waste gas collection / treatment device.

[0018] A method for degassing a nuclear reactor coolant, utilizing the aforementioned nuclear reactor coolant degassing system, includes the following steps: S1. The hollow fiber membrane degassing device is vertically arranged on the working platform, wherein the flow direction of nitrogen in the hollow fiber membrane degassing device is from top to bottom, and the flow direction of coolant is from bottom to top; S2. Coolant is introduced into the coolant channel; simultaneously, nitrogen gas is introduced into the membrane fiber channel; the gas in the coolant enters the membrane fiber channel through the nanopores of the hollow fiber membrane fiber; S3. The degassed coolant is obtained at the coolant output end of the hollow fiber membrane degassing device.

[0019] Furthermore, the degassing system operates at a temperature of 15-45℃ and an operating pressure of less than 0.4MPa.

[0020] Furthermore, in step S2, the feed pressure of the coolant introduced into the coolant is 0.15-0.4 MPa.

[0021] Furthermore, in step S2, the flow rate of the coolant introduced into the coolant is 0-8 m³ / h.

[0022] Furthermore, in step S2, the feed pressure of the nitrogen gas introduced into the nitrogen gas is 0.7-1 MPa; the feed flow rate is 15-30 Nm³ / h.

[0023] The implementation of this invention has the following beneficial effects: The degassing system for nuclear reactor coolant of the present invention is highly modular and can withstand tilting, swaying and shock environments. It is particularly suitable for the efficient removal of dissolved oxygen, hydrogen and radioactive inert gases from compact and miniaturized nuclear reactors, thereby improving the safety and economy of nuclear reactor operation.

[0024] This invention utilizes the hydrophobic properties of hollow fiber membranes to combine membrane degassing technology with vacuum suction and nitrogen purging to achieve deep degassing. It also has significant advantages in meeting the requirements of reactor radiation protection, shock protection, and resistance to tilting, swaying, and impact environments.

[0025] The degassing method for nuclear reactor coolant of the present invention enables efficient degassing of reactor coolant under relatively low temperature and low pressure conditions, which can significantly reduce the dependence on large degassing towers or high temperature and high pressure supporting equipment, reduce the overall footprint, and reduce the concentration of dissolved oxygen, hydrogen and radioactive inert gases to extremely low levels.

[0026] In the degassing system of the nuclear reactor coolant of the present invention, the coolant flows from bottom to top in combination with nitrogen flowing from top to bottom, which enables the system to operate reliably for a long time and optimizes energy consumption. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the degassing system for the nuclear reactor coolant of the present invention.

[0028] Figure 2 This is a schematic diagram of the degassing device of the present invention.

[0029] Figure 3 This is a cross-sectional view of the degassing device of the present invention.

[0030] Figure 4 A schematic diagram of the flow path of nitrogen and coolant in the degasser.

[0031] Among them, 11-coolant storage device; 12-pressurization device; 13-vacuum device; 21-first stage degasser; 22-second stage degasser; 23-third stage degasser; 24-fourth stage degasser; 31-first pressure monitoring device; 32-first dissolved gas analysis device; 33-flow monitoring device; 34-second pressure monitoring device; 35-second dissolved gas analysis device; 36-temperature monitoring device; 37-third pressure monitoring device; 201 - Outer shell; 202 - Hollow fiber membrane column; 203 - Nitrogen inlet; 204 - Nitrogen outlet; 205 - Coolant inlet; 206 - Coolant outlet; A - Coolant flow direction; B - Nitrogen flow direction. Detailed Implementation

[0032] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the invention will now be described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientations or positional relationships indicated by terms such as "front," "rear," "upper," "lower," "left," "right," "longitudinal," "horizontal," "vertical," "horizontal," "top," "bottom," "inner," "outer," "head," and "tail" are based on the orientations or positional relationships shown in the accompanying drawings, and are constructed and operated in a specific orientation. They are only for the convenience of describing the present invention and do not indicate that the device or element referred to must have a specific orientation; therefore, they should not be construed as limitations on the present invention.

[0033] It should also be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. When an component is referred to as being "on" or "below" another component, the component can be located "directly" or "indirectly" on the other component, or there may be one or more intermediary components. The terms "first," "second," "third," etc., are used only for the convenience of describing the present invention and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances.

[0034] like Figure 1 As shown, this embodiment provides a degassing system for nuclear reactor coolant, including a hollow fiber membrane degassing device, a coolant storage device 11 connected to the coolant input end of the hollow fiber membrane degassing device, and a vacuum device 13 connected to the nitrogen output end of the hollow fiber membrane degassing device; the hollow fiber membrane degassing device includes at least one vertically arranged degasser; the degasser includes a coolant channel and a membrane fiber channel arranged in a vertical direction; the coolant flows from bottom to top in the coolant channel, and the nitrogen flows from top to bottom in the membrane fiber channel.

[0035] Specifically, the hydrophobic properties of the hollow fiber membrane allow gases in the coolant to pass through while the liquid is blocked, thereby achieving the removal of gases (including oxygen, hydrogen, and radioactive inert gases) from the coolant. Vacuum device 13 is connected to the nitrogen output end of the hollow fiber membrane degassing device, thus maintaining a low partial pressure in the nitrogen flow channel of the hollow fiber membrane degassing device and achieving good degassing performance. Vacuum device 13 can be a vacuum pump. Nitrogen enters from the top and exits from the bottom of the hollow fiber membrane degassing device, working in the same direction as the suction of vacuum device 13 to continuously remove gases from the coolant that have permeated through the hollow fiber membrane into the nitrogen flow channel.

[0036] Furthermore, the coolant flows from bottom to top, while nitrogen flows from top to bottom, synergizing the flow direction with gravity: the coolant enters under higher static pressure at the bottom of the hollow fiber membrane degassing unit, suppressing local gas evolution and cavitation at the inlet. As the coolant gradually rises in the coolant flow pipe of the hollow fiber membrane degassing unit, any microbubbles generated or desorbed on the surface of the hollow fiber membrane are rapidly swept away by the mainstream in the direction of buoyancy and discharged from the top, significantly reducing the gas curtain and redissolution on the membrane surface. At the same time, nitrogen enters from the top of the hollow fiber membrane degassing unit. The liquid phase in the top section already has low gas content, corresponding to the freshest nitrogen with the lowest partial pressure, maintaining the maximum partial pressure difference in the end section to achieve ppb-level "last mile" degassing. The liquid phase in the bottom section has the highest gas content, corresponding to the enriched scavenging gas and higher static pressure zone, resulting in a more reasonable partial pressure matching and avoiding excessive driving at the front end and collapse of driving force at the end.

[0037] This flow channel combination also allows the gas phase in the inner cavity to converge axially from top to bottom, eliminating the stagnation of the upper gas mass and reducing the risk of pulsation and gas resistance on the suction side; the liquid phase is an upward flow, which has a fluidizing and carrying effect on entrained particles, thereby reducing bottom deposition and long-term pressure drop rise.

[0038] Compared to top-in / bottom-out liquid phase / bottom-in / top-out scavenging schemes, the top-in / bottom-out scavenging / bottom-in / top-out liquid phase scheme significantly improves the volumetric mass transfer coefficient per unit length and reduces pressure fluctuations on the vacuum side. This results in a significant reduction in short-term steady-state fluctuations and a significant decrease in the rate of pressure drop during long-term operation, which is beneficial for the overall long-term reliable operation and energy consumption optimization of the system. Specifically, bottom-in / top-out liquid phase ensures that the microbubble removal direction is aligned with gravity, reducing the outer boundary layer of the thin film and minimizing local "gas curtain" stagnation, thereby improving the volumetric mass transfer coefficient per unit length. Top-in / bottom-out gas phase creates countercurrent endpoint matching, keeping the terminal section in a state of higher effective partial pressure difference for a long time, avoiding terminal driving force collapse and reducing pulsations caused by gas cloud accumulation on the vacuum side. Segmented suction / branch pressure regulation on the vacuum side maintains a near-constant axial partial pressure gradient, reducing energy accumulation of pipeline-cavity coupled oscillations and reducing pressure fluctuations.

[0039] In some embodiments, the hollow fiber membrane degassing device includes a multi-stage degasser connected by pipelines. The number of degassers in the multi-stage degassing device is greater than or equal to two. Specifically, the number of degassers can be any integer within this range, wherein a larger number of degassers results in a better degassing effect, and an appropriate number of degassers can be selected according to the required degassing effect. The vacuum device 13 distributes pressure differences between stages, enabling the upstream stage to quickly remove most of the dissolved gas, and the downstream stage to achieve deep and fine degassing, ensuring stable degassing performance of the entire machine under different feed loads.

[0040] In some embodiments, such as Figure 1The connection method of the first-stage degasser 21, second-stage degasser 22, third-stage degasser 23, and fourth-stage degasser 24 shown is as follows: In a multi-stage degasser, each stage is connected in parallel via a nitrogen flow line; in another multi-stage degasser, each stage is connected in series via a coolant flow line. Each stage of the multi-stage degasser has independent inlet and outlet valves, allowing each stage to operate independently. Specifically, the parallel connection of each stage via nitrogen flow lines provides each stage with an independent vacuum branch, which better achieves the effect of rapid stripping in the preceding stage and deep, precise stripping in the subsequent stage. Understandably, valves are provided at the coolant inlet, coolant outlet, nitrogen inlet, and nitrogen outlet of the degasser; pipelines connecting the two ends are installed at the coolant outlet and coolant inlet of the degasser, and valves are installed on these pipelines, so that each stage of the degasser can operate independently, thereby realizing the modular configuration of multi-stage degasser, allowing each degasser to be isolated individually, and enabling maintenance or flexible adjustment of the number of degasser in operation without shutting down the system.

[0041] In some embodiments, the degasser includes a housing 201 and a hollow fiber membrane column 202 filled inside; the hollow fiber membrane column 202 is woven from a plurality of hollow fiber membrane filaments. Specifically, the housing 201 is an austenitic stainless steel housing; the membrane pore size of the hollow fiber membrane filaments is nanoscale. The degasser is designed for a service life of 60 years, and the hollow fiber membrane column 202 is designed for a service life of 3-5 years, serving as a replaceable component for periodic maintenance and performance recovery.

[0042] In some embodiments, such as Figure 2 and Figure 3As shown, the hollow fiber membrane column 202 and the outer shell 201 form three independent chambers, including a middle chamber formed by the side surface of the hollow fiber membrane column 202 and the middle inner surface of the outer shell 201, an upper chamber formed by the upper end face of the hollow fiber membrane column 202 and the upper inner surface of the outer shell 201, and a lower chamber formed by the lower end face of the hollow fiber membrane column 202 and the lower inner surface of the outer shell 201; sealing components are respectively provided at the connection between the middle chamber, the upper chamber, and the lower chamber. The hollow fiber membrane column 202 has a hollow cylindrical structure; the upper and lower end faces of the hollow fiber membrane column 202 are annular rings including coolant channel ports and several membrane fiber channel ports; the inner circle of the annular ring is the coolant channel port; the membrane fiber channel ports are distributed on the ring. The degasser includes a nitrogen inlet 203 and a coolant outlet 206 located at the upper part of the outer casing 201, a nitrogen outlet 204 and a coolant inlet 205 located at the lower part of the outer casing 201; the coolant outlet 206 and the coolant inlet 205 are respectively tightly connected to the upper and lower ports of the coolant channel of the hollow fiber membrane column 202; the nitrogen inlet 203 and the nitrogen outlet 204 are respectively connected to the upper and lower chambers. The membrane fiber channel includes a channel formed on the inner side of the hollow fiber membrane fiber; the coolant channel includes the hollow portion of the hollow fiber membrane column 202, the gaps between the hollow fiber membrane fibers, and the central chamber.

[0043] Understandably, such as Figure 4 As shown, nitrogen enters the upper chamber of the degasser through nitrogen inlet 203, then enters the hollow fiber membrane column 202 through the upper port of the hollow fiber membrane filament, exits the hollow fiber membrane column 202 through the lower port of the hollow fiber membrane filament and enters the lower chamber, and then exits the degasser through nitrogen outlet 204; coolant enters the degasser through coolant inlet 205, enters the hollow part of the hollow fiber membrane column 202 through the lower port of the coolant channel, then passes through the gaps between the hollow fiber membrane filaments and the middle chamber, and then concentrates in the hollow part of the hollow fiber membrane column 202, flows out of the hollow fiber membrane column 202 through the upper port of the coolant channel, and exits the degasser through coolant outlet 206.

[0044] Furthermore, the degasser end caps adopt remotely operable split clamps or ring bolt groups, and are equipped with interfaces for robotic arms / electric wrenches to enable rapid disassembly and assembly in radiation environments; positioning guide pins and brackets are set to automatically center the membrane column during replacement, shortening the time for reactor shutdown overhaul.

[0045] In some embodiments, the degassing system is equipped with reinforcing ribs, buffer pads and multi-point limiting, and is equipped with anti-vibration support frame, buffer pads and several fixing clamps to meet Class 1 impact requirements and can operate stably in inclined environments (inclination ≤15°) and swaying environments; the key pipelines of the degassing system adopt anti-vibration clamping and flexible compensation design to avoid fatigue failure under dynamic loads.

[0046] In some embodiments, the coolant input end of the hollow fiber membrane degassing device is connected to a first dissolved gas analyzer 32, and the coolant output end is connected to a second dissolved gas analyzer 35, so as to analyze the degassing effect of the hollow fiber membrane degassing device; in particular, the dissolved gas analyzer at the coolant output end is used to monitor the dissolved gas concentration in the effluent of the hollow fiber membrane degassing device and provide real-time feedback, thereby realizing the adjustment of nitrogen flow rate to avoid secondary dissolution and excessive energy consumption.

[0047] In some embodiments, the coolant output of the hollow fiber membrane degassing device is connected to a coolant collection device; the nitrogen output of the hollow fiber membrane degassing device is connected to a waste gas collection / treatment device. Specifically, the degassed coolant is reused in the main circuit after entering the coolant collection device.

[0048] In some embodiments, the output end of the coolant storage device 11 is sequentially connected to a pressurization device 12, a first pressure monitoring device 31, a first dissolved gas analysis device 32, and a hollow fiber membrane degassing device. The pressurization device 12 provides a certain positive pressure to the coolant, ensuring the speed at which the coolant flows through the multi-stage degassing unit. The pressurization device 12 can be selected as a booster pump. The output end of the nitrogen storage device is sequentially connected to a flow monitoring device 33, a second pressure monitoring device 34, and the hollow fiber membrane degassing device. The coolant output end of the hollow fiber membrane degassing device is sequentially connected to a temperature monitoring device 36, a second dissolved gas analysis device 35, and a coolant collection device. The nitrogen output end of the hollow fiber membrane degassing device is sequentially connected to a third pressure monitoring device 37, a vacuum device 13, and a waste gas collection / treatment device. This allows for monitoring of pressure, temperature, and dissolved gas concentration during the degassing process to better adjust relevant operating parameters and achieve a good degassing effect.

[0049] A method for degassing a nuclear reactor coolant, utilizing the aforementioned nuclear reactor coolant degassing system, includes the following steps: S1. The hollow fiber membrane degassing device is vertically arranged on the working platform. The flow direction of nitrogen in the hollow fiber membrane degassing device is from top to bottom, and the flow direction of coolant is from bottom to top.

[0050] Specifically, the hollow fiber membrane degassing device is placed vertically on the working platform, and then the various devices are connected according to the structure of the above system. This includes connecting the coolant inlet at the bottom of the hollow fiber membrane degassing device to the coolant storage device through a coolant flow pipeline, and connecting the vacuum device to the nitrogen outlet at the bottom of the hollow fiber membrane degassing device through a nitrogen flow pipeline, so that the flow direction of nitrogen in the hollow fiber membrane degassing device is from top to bottom, and the flow direction of coolant is from bottom to top.

[0051] S2. Coolant is introduced into the coolant channel; at the same time, nitrogen is introduced into the membrane fiber channel; the gas in the coolant enters the membrane fiber channel through the nanopores of the hollow fiber membrane fiber.

[0052] Step S2 specifically involves: starting the pressurization device to allow the coolant to enter the coolant channel, and simultaneously starting the vacuum device to allow nitrogen to enter the membrane fiber channel; oxygen, hydrogen, and inert gases in the coolant enter the membrane fiber channel through the nanopores of the hollow fiber membrane.

[0053] Specifically, the vacuum device provides a negative pressure of -0.095MPa to -0.1MPa, and any value within this range can be selected, including -0.095MPa, -0.098MPa, or -0.1MPa.

[0054] Specifically, the degassing system operates at a temperature of 15-45℃ and a pressure of less than 0.4MPa. Temperature and pressure can be selected at any value within the corresponding range.

[0055] Specifically, the feed pressure of the coolant introduced into the coolant is 0.15-0.4MPa; the flow rate of the coolant is 0-8 m³ / h, and the pressure and flow rate can be selected at any value within the corresponding range.

[0056] Specifically, the nitrogen feed pressure is 0.7-1 MPa; the feed flow rate is 15-30 Nm³ / h, and any value within the corresponding range can be selected for both pressure and flow rate. Furthermore, the nitrogen purging flow rate is adjusted based on the dissolved gas concentration at the coolant output of the hollow fiber membrane degassing device. Understandably, this adjustment involves gradually increasing the nitrogen purging flow rate until the dissolved gas concentration at the coolant output no longer decreases with increasing purging flow rate.

[0057] S3. The degassed coolant is obtained at the coolant output end of the hollow fiber membrane degassing device.

[0058] When degassing the coolant using the nuclear reactor coolant degassing system of the present invention, using dissolved oxygen as an indicator, when the feed dissolved oxygen is 7000-8000 ppb, the effluent dissolved oxygen is ≤10 ppb, and can be as low as below 1 ppb; when the feed dissolved oxygen is ≤7000 ppb, the effluent dissolved oxygen is ≤3 ppb, and can be as low as below 1 ppb; at the same time, it can significantly reduce the content of dissolved hydrogen and radioactive inert gases (krypton, xenon).

[0059] Example 1 S1. Place the hollow fiber membrane degassing device vertically on the working platform, and then connect the various devices according to the structure of the above system, including connecting the coolant inlet at the bottom of the hollow fiber membrane degassing device to the coolant storage device through a coolant flow pipeline, and connecting the vacuum device to the nitrogen outlet at the bottom of the hollow fiber membrane degassing device through a nitrogen flow pipeline, so that the flow direction of nitrogen in the hollow fiber membrane degassing device is from top to bottom, and the flow direction of coolant is from bottom to top; wherein, the hollow fiber membrane degassing device is a 4-stage degassing device; S2. Start the pressurization device to allow coolant to enter the coolant channel, and simultaneously start the vacuum device to allow nitrogen to enter the membrane fiber channel; oxygen, hydrogen, and inert gases in the coolant permeate through the nanopores of the hollow fiber membrane into the membrane fiber channel; the dissolved oxygen in the inlet coolant is 8000 ppb, the coolant feed pressure is 0.4 MPa, and the feed flow rate is 8 m³ / h; the nitrogen feed pressure is 0.8 MPa, and the feed flow rate is 20 Nm³ / h. During operation, the degassing system operates at a temperature of 15-45℃ and a pressure less than 0.4 MPa.

[0060] S3. The degassed coolant is obtained at the coolant output end of the hollow fiber membrane degassing device.

[0061] The dissolved oxygen content in the degassed coolant was measured to be less than 3 ppb.

[0062] Example 2 The difference from Example 1 is that the dissolved oxygen in the inlet coolant in step S2 is 6500 ppb; the dissolved oxygen in the coolant after degassing in step S3 is less than 1 ppb.

[0063] Example 3 The difference from Example 1 is that: in step S1, the hollow fiber membrane degassing device is a two-stage degassing device; the dissolved oxygen in the coolant after degassing in step S3 is less than 5 ppb.

[0064] Example 4 The difference from Example 2 is that: in step S1, the hollow fiber membrane degassing device is a two-stage degassing device; and the dissolved oxygen in the coolant after degassing in step S3 is less than 3 ppb.

[0065] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A system for deaerating a nuclear reactor coolant, the system comprising: The system comprises a hollow fiber membrane degassing device, a coolant storage device connected with a coolant input end of the hollow fiber membrane degassing device, and a vacuum device connected with a nitrogen output end of the hollow fiber membrane degassing device. The hollow fiber membrane degassing device comprises at least one vertically arranged degasser; the degasser comprises a coolant channel arranged in the vertical direction and a membrane filament channel; the coolant flows from bottom to top in the coolant channel, and the nitrogen flows from top to bottom in the membrane filament channel.

2. The nuclear reactor coolant degassing system according to claim 1, wherein: The hollow fiber membrane degassing device comprises multiple-stage degassers connected by pipelines; The multiple-stage degassers are connected in parallel through nitrogen flow pipelines, and are connected in series through coolant flow pipelines.

3. The system for removing gases from a nuclear reactor coolant according to claim 2, wherein: Independent inlet and outlet valves are arranged between the multiple-stage degassers to enable independent operation of the multiple-stage degassers.

4. The system for removing gases from a nuclear reactor coolant according to claim 1, wherein: The degasser comprises a shell and an internally filled hollow fiber membrane column; the hollow fiber membrane column is composed of a plurality of vertically arranged hollow fiber membrane filaments.

5. The system for removing gases from a nuclear reactor coolant according to claim 4, wherein: The hollow fiber membrane column and the shell form three independent chambers, including a middle chamber formed by a side surface of the hollow fiber membrane column and a middle inner surface of the shell, an upper chamber formed by an upper end surface of the hollow fiber membrane column and an upper inner surface of the shell, and a lower chamber formed by a lower end surface of the hollow fiber membrane column and a lower inner surface of the shell; sealing assemblies are arranged at the connections between the middle chamber and the upper chamber and the lower chamber, respectively.

6. The system for removing gases from a nuclear reactor coolant according to claim 5, wherein: The hollow fiber membrane column is a hollow cylindrical structure; the upper and lower end surfaces of the hollow fiber membrane column are annular rings comprising a coolant channel port and a plurality of membrane filament channel ports; the inner circle of the annular ring is the coolant channel port; the membrane filament channel ports are distributed on the ring of the annular ring.

7. The system for removing gases from a nuclear reactor coolant according to claim 6, wherein: The degasser comprises a nitrogen inlet and a coolant outlet arranged at the upper part of the shell, and a nitrogen outlet and a coolant inlet arranged at the lower part of the shell; the coolant outlet and the coolant inlet are in close connection with the upper and lower ports of the coolant channel of the hollow fiber membrane column, respectively; the nitrogen inlet and the nitrogen outlet are in connection with the upper and lower chambers, respectively.

8. The system for removing gases from a nuclear reactor coolant according to claim 7, wherein: The membrane filament channel comprises a channel formed by the inner side of the hollow fiber membrane filament; the coolant channel comprises a hollow part of the hollow fiber membrane column, a gap between the hollow fiber membrane filaments, and the middle chamber.

9. A method of deaerating a nuclear reactor coolant using the deaeration system of any one of claims 1-8, wherein, The method comprises the following steps: S1. vertically arranging the hollow fiber membrane degassing device on a working platform; the flow direction of the nitrogen in the hollow fiber membrane degassing device is from top to bottom, and the flow direction of the coolant is from bottom to top; S2. introducing the coolant into the coolant channel; at the same time, introducing the nitrogen into the membrane filament channel; the gas in the coolant passes through the nanopores of the hollow fiber membrane filaments into the membrane filament channel; S3. obtaining the degassed coolant at the coolant output end of the hollow fiber membrane degassing device.

10. The nuclear reactor coolant degassing method according to claim 9, wherein: The feeding pressure of the coolant in the cooling by the coolant in step S2 is 0.15-0.4 MPa; and / or, the flow rate of the coolant is 0-8 m³ / h; And / or, the feeding pressure of the nitrogen in the cooling by the nitrogen in step S2 is 0.7-1 MPa; the feeding flow rate is 15-30 Nm³ / h.

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