Lead-based coolant vacuum-driven solid phase oxygen control device and method

Abstract

The application discloses a kind of lead-based coolant vacuum-driven solid-phase oxygen control device and method, the application uses vacuum negative pressure condition as the power of liquid level promotion and circulation operation of liquid coolant to realize the supplement and control of oxygen concentration.Oxygen supplement pipe inside is placed by PbO particle wrapped by filter screen, whole is above the liquid level of lead-based coolant, and the top two liquid level meters are used for monitoring working liquid level and alarm liquid level respectively.When measured oxygen concentration signal is lower than target value, vacuum pump works and opens vacuum air valve, arc metal sheet is compressed under the phase transition compression state of Ni-Ti based high temperature double-way shape memory alloy spring and negative pressure suction force, and forms airtight vacuum environment, coolant flows into solid-phase oxygen control oxygen supplement pipe by inlet under the action of pressure difference, oxygen concentration is increased after PbO particle, and coolant flows back to liquid level through outlet to realize oxygen supplement, and vacuum air valve is closed until oxygen concentration reaches target value.The application has the characteristics of small occupied volume, simple structure and safe and easy operation.

Description

Technical Field

[0001] This invention belongs to the field of nuclear engineering technology, specifically relating to a vacuum-driven solid-phase oxygen control device and method using lead-based coolant. Background Technology

[0002] Liquid lead-based alloys have been selected as one of the main candidate coolants for Generation IV nuclear energy systems due to their excellent heat transfer properties, chemical inertness, and economic advantages. Oxygen concentration control technology, as one of the key technologies in its application, has been extensively studied worldwide. The main purpose of oxygen concentration control is to maintain the dissolved oxygen concentration of the coolant within a specific range to prevent the formation of coolant impurities (mainly PbO) and simultaneously to form a dense oxide film on the surface of structural materials to mitigate corrosion. Currently, among the solid-phase oxygen control technologies developed internationally, various types of PbO solid-phase oxygen control (mass exchangers) designs for lead-based reactors have been developed. Most designs require liquid coolant pumps as the driving force, leading to complexity in system structure and space. Furthermore, the impeller corrosion resistance, operating temperature, and service life of liquid metal pumps all impose limitations on solid-phase oxygen control design. In the solid oxygen control design of lead-based reactors, PbO solid oxygen control (mass exchangers) are basically immersed below the coolant surface. Even when not in operation, PbO particles are still immersed in the coolant, which places higher demands on the dissolution and corrosion performance of PbO particles. At the same time, if the PbO content in the coolant is too high due to long-term immersion of PbO, there is also a risk of excessive oxygen supplementation during the oxygen control process. Summary of the Invention

[0003] To address the shortcomings of existing solid-phase oxygen control systems, this invention proposes a lead-based coolant vacuum-driven solid-phase oxygen control device and method. The solid-phase oxygen control device is placed above the coolant liquid surface, and the vacuum negative pressure condition is used as the driving force for the liquid coolant level rise and circulation to achieve oxygen concentration replenishment and control. The driving device is a non-contact vacuum pump, which has the characteristics of small internal volume, simple structure, good economy, safety and easy operation.

[0004] To achieve the above objectives, the technical solution adopted by this invention is as follows: A lead-based coolant vacuum-driven solid-phase oxygen control device includes a coolant tank and an oxygen supply pipe. The coolant tank stores coolant, and the oxygen supply pipe is disposed inside the coolant tank with its lower end below the coolant liquid level. The oxygen supply tube includes a top cover, a vacuum tube, a main body, a liquid outlet tube, a shape memory alloy spring, and an arc-shaped metal plate. PbO particles fixed inside the main body are arranged by a metal wire mesh. The upper end of the main body is sealed to the top cover. The vacuum tube is located on the upper part of the top cover and communicates with the main body. A liquid outlet tube is located on the side of the main body. An arc-shaped metal plate matching the outlet tube is provided at its opening for opening and closing. The arc-shaped metal plate is connected to the shape memory alloy spring via a metal connecting wire. One end of the shape memory alloy spring is fixedly installed on the inner wall of the vacuum tube.

[0005] In the above technical solution, an oxygen sensor is installed in the coolant tank.

[0006] In the above technical solution, the upper end of the vacuum tube is connected to the vacuum pump.

[0007] In the above technical solution, a level gauge is installed in the oxygen supply pipe.

[0008] In the above technical solution, the level gauge includes a first level gauge and a second level gauge. The lower end of the first level gauge is flush with the upper end of the outlet pipe, and the lower end of the second level gauge is higher than the upper end of the outlet pipe.

[0009] In the above technical solution, the liquid inlet at the lower end of the oxygen supplementation tube is trapezoidal in shape.

[0010] In the above technical solution, the liquid outlet pipe and the main body of the oxygen supply pipe are set at an inclined angle.

[0011] In the above technical solution, the shape memory alloy spring is a Ni-Ti based high-temperature two-way shape memory alloy spring.

[0012] The present invention also provides a method for using a lead-based coolant vacuum-driven solid-phase oxygen control device, the steps of which include: Step 1: When the oxygen concentration signal measured by the oxygen sensor is lower than the target value, the vacuum pump starts and opens the vacuum air valve. Since the working coolant temperature is generally above 300℃, and the covering gas also has a high temperature, the Ni-Ti based high-temperature two-way shape memory alloy spring at the upper end of the metal connecting line reaches the phase transition temperature (100℃) when the high-temperature covering gas passes through. At temperatures above 200℃, the liquid changes from a stretched state under cold conditions to a compressed state. The arc-shaped metal sheet connected to it blocks the outlet pipe under tension. The arc-shaped metal sheet undergoes slight deformation under the pressure difference caused by the metal connecting line and vacuum, achieving a tight seal with the outlet pipe. The oxygen supply pipe is in a negative pressure sealed state. Driven by the pressure difference, the lead-based coolant enters the oxygen supply pipe and dissolves after reacting with PbO particles, becoming a high oxygen concentration state. When the liquid level rises to the height of the level gauge, the coolant flows into the outlet pipe, and the arc-shaped metal sheet falls back to a suspended state under the pressure of the coolant. The coolant then flows to the liquid surface of the device. The above process is repeated until the oxygen concentration reaches the target value. Step 2: When the oxygen concentration reaches or exceeds the target value, close the vacuum valve. Due to the tension of the metal connecting wire and the Ni-Ti based high-temperature two-way shape memory alloy spring at the top, some coolant will remain in the outlet pipe. When the vacuum pipe is cooled by the external environment and the internal temperature drops below the phase transition temperature, the Ni-Ti based high-temperature two-way shape memory alloy spring returns to the stretched state, the arc-shaped metal plate leaves the outlet pipe, and the internal and external gas pressures reach the same level. The coolant remaining in the pipe is discharged to the liquid surface under gravity, and the coolant in the oxygen replenishment pipe falls back to the liquid surface of the device. At this time, the oxygen control and oxygen replenishment process is completed.

[0013] The beneficial effects of this invention compared to the prior art are as follows: 1) This invention discloses a vacuum-driven solid-phase oxygen control device for lead-based coolant. The structure is designed to place the solid-phase oxygen control above the coolant liquid surface, avoiding the problem of excessive oxygen caused by long-term immersion of PbO particles in the coolant. It uses the vacuum negative pressure condition as the driving force for the liquid coolant level to be raised and circulated to achieve oxygen concentration replenishment and control. It has the characteristics of small internal volume, simple structure, good economy, safety and easy operation.

[0014] 2) This invention discloses a method for using a lead-based coolant vacuum-driven solid-phase oxygen control device. In this method, a Ni-Ti-based high-temperature two-way shape memory alloy spring is used to achieve tension control of an arc-shaped metal sheet in two different stretching and compression states above and below the phase transition temperature, thereby creating the system's sealing requirements and forming a pressure difference inside and outside the solid-phase oxygen control system to achieve the power for raising the liquid metal level and running. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a lead-based coolant vacuum-driven solid-phase oxygen control device according to the present invention.

[0016] Wherein: 1 is the first liquid level gauge, 2 is the second liquid level gauge, 3 is the top cover, 4 is the oxygen supply pipe, 5 is the liquid outlet pipe, 6 is the metal connecting wire, 7 is the arc-shaped metal sheet, 8 is the metal wire mesh, 9 is the PbO particles, 10 is the liquid inlet, 11 is the vacuum valve, 12 is the shape memory alloy spring, 13 is the vacuum pipe, 14 is the oxygen sensor, and 15 is the coolant tank. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0018] like Figure 1 As shown, the lead-based coolant vacuum-driven solid-phase oxygen control device of the present invention mainly includes an oxygen supply pipe 4, a top cover 3, a liquid inlet 10, and an outlet pipe 5. In the figure: LBE is liquid lead-bismuth eutectic alloy, and Pb is lead, used as a coolant. PbO particles 9 are placed inside the oxygen supply pipe 4. The PbO particles 9 are wrapped and fixed by a metal wire mesh 8 to prevent solid particles from escaping into the liquid lead-based coolant. The oxygen supply pipe 4 is welded and sealed to the top cover 3, and is installed on the experimental device by flange or welding. The oxygen supply pipe 4 is located above the liquid surface of the lead-based coolant and is isolated from the coolant in the non-working state, avoiding the risk of oxygen saturation or even supersaturation caused by PbO particles 9 being immersed below the liquid surface for a long time. The first level gauge 1 and the second level gauge 2 are installed on the top cover 3 to indicate the liquid level during operation. The lower end of the second level gauge 2 is flush with the upper end of the outlet pipe 5, which is the normal operating liquid level when the coolant flows out of the outlet pipe 5. The lower end of the first level gauge 1 is higher than the lower end of the second level gauge 2, which serves as a warning of high liquid level caused by abnormal conditions such as poor coolant flow. The oxygen supply pipe 4 is evacuated by a vacuum pump connected to the vacuum pipe 13 to reduce the covering gas pressure. Driven by the pressure difference, the lead-based coolant enters the oxygen supply pipe 4 through the inlet 10. After flowing through the PbO particles 9, the oxygen concentration increases. When passing through the outlet pipe 5, the arc-shaped metal sheet 7 leaves the outlet pipe 5 due to the pressure of the coolant's own weight. There can be one or more outlet pipes 5. The coolant flows down to the liquid surface, realizing the oxygen supply of the coolant in the device. The arc-shaped metal sheet 7 is connected to the metal connecting wire 6. The upper end of the metal connecting wire 6 is a Ni-Ti based high-temperature two-way shape memory alloy spring 12, which is fixed to the inner wall of the vacuum tube 13. At the phase transition temperature of 100°C... At temperatures above 200℃, the Ni-Ti-based high-temperature two-way shape memory alloy spring 12 is in a compressed state, gradually transitioning to a stretched state below the phase transition temperature. In the non-working state, part of the Ni-Ti-based high-temperature two-way shape memory alloy spring 12 is in a stretched state below the phase transition temperature, with the connected arc-shaped metal plate 7 located outside the outlet pipe 5 and maintaining a certain distance from it. In the working state, the high-temperature gas drawn into the vacuum pump through the vacuum pipe 13 has a temperature higher than the phase transition temperature, causing the Ni-Ti-based high-temperature two-way shape memory alloy spring 12 to become compressed. The connected arc-shaped metal plate 7 is pressed against the outlet pipe 5, sealing the oxygen supply pipe 4. The portion connecting the inlet 10 to the oxygen supply pipe 4 is designed with a trapezoidal structure to facilitate coolant return to the liquid surface and prevent liquid accumulation. Similarly, the outlet pipe 5 is designed as an inclined insertion pipe to facilitate coolant drainage within the pipe and prevent coolant stagnation.

[0019] The specific implementation process of this invention is as follows: 1) When the oxygen concentration signal measured by the oxygen sensor 14 is lower than the target value, the vacuum pump operates and opens the vacuum air valve 11. Since the working coolant temperature is generally above 300℃, and the covering gas also has a high temperature, the Ni-Ti based high-temperature two-way shape memory alloy spring 12 at the upper end of the metal connecting wire 6 reaches the phase transition temperature of 100℃ when the high-temperature covering gas passes through. At temperatures above 200℃, the liquid changes from a stretched state under cold conditions to a compressed state. The arc-shaped metal sheet 7 connected to it blocks the outlet pipe 5 under the action of tension. The arc-shaped metal sheet 7 undergoes slight deformation under the pressure difference caused by the metal connecting line 6 and the vacuum, thus achieving a tight seal with the outlet pipe 5. The oxygen supply pipe 4 is in a negative pressure sealed state. The lead-based coolant enters the oxygen supply pipe 4 under the drive of the pressure difference. After dissolving with the PbO particles 8, it becomes a high oxygen concentration state. When the liquid level rises to the height of the second liquid level gauge 2, the coolant flows into the outlet pipe 5. The arc-shaped metal sheet 7 falls back to a suspended state under the action of coolant pressure. The coolant then flows to the liquid surface of the device. The above process is repeated until the oxygen concentration reaches the target value. 2) When the oxygen concentration reaches or exceeds the target value, the vacuum valve 11 is closed. Due to the tension of the metal connecting wire 6 and the Ni-Ti based high-temperature two-way shape memory alloy spring 12 at the upper end, some coolant will remain in the outlet pipe 5. When the vacuum pipe 13 is cooled by the external environment and the internal temperature drops below the phase change temperature, the Ni-Ti based high-temperature two-way shape memory alloy spring 12 returns to the stretched state, the arc-shaped metal plate 7 leaves the outlet pipe 5, the internal and external gas pressures reach the same level, and the coolant in the remaining pipe is discharged to the liquid surface under the action of gravity. The coolant in the oxygen replenishment pipe 4 falls back to the liquid surface of the device, and the oxygen control and oxygen replenishment process is completed at this time.

[0020] The parts of this invention not described in detail are well-known to those skilled in the art. The above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A vacuum-driven solid-phase oxygen control device using lead-based coolant, characterized in that: It includes a coolant tank and an oxygen supply pipe. The coolant tank stores coolant, and the oxygen supply pipe is installed inside the coolant tank with its lower end below the coolant liquid level. The oxygen supply tube includes a top cover, a vacuum tube, a main body, a liquid outlet tube, a shape memory alloy spring, and an arc-shaped metal plate. PbO particles fixed inside the main body are arranged by a metal wire mesh. The upper end of the main body is sealed to the top cover. The vacuum tube is located on the upper part of the top cover and communicates with the main body. A liquid outlet tube is located on the side of the main body. An arc-shaped metal plate matching the outlet tube is provided at its opening for opening and closing. The arc-shaped metal plate is connected to the shape memory alloy spring via a metal connecting wire. One end of the shape memory alloy spring is fixedly installed on the inner wall of the vacuum tube.

2. The lead-based coolant vacuum-driven solid-phase oxygen control device according to claim 1, characterized in that: An oxygen sensor is installed in the coolant tank.

3. The lead-based coolant vacuum-driven solid-phase oxygen control device according to claim 1, characterized in that: The upper end of the vacuum tube is connected to the vacuum pump.

4. The lead-based coolant vacuum-driven solid-phase oxygen control device according to claim 1, characterized in that: A level gauge is installed in the oxygen supply pipe.

5. A lead-based coolant vacuum-driven solid-phase oxygen control device according to claim 4, characterized in that: The level gauge includes a first level gauge and a second level gauge. The lower end of the second level gauge is flush with the upper end of the outlet pipe, and the lower end of the first level gauge is higher than the upper end of the outlet pipe.

6. The lead-based coolant vacuum-driven solid-phase oxygen control device according to claim 1, characterized in that: The lower end of the oxygen supply tube has a trapezoidal inlet.

7. A lead-based coolant vacuum-driven solid-phase oxygen control device according to claim 1, characterized in that: The liquid outlet pipe and the main body of the oxygen supply pipe are set at an inclined angle.

8. A lead-based coolant vacuum-driven solid-phase oxygen control device according to claim 1, characterized in that: The shape memory alloy spring is a Ni-Ti based high-temperature two-way shape memory alloy spring.

9. The method of using the lead-based coolant vacuum-driven solid-phase oxygen control device according to any one of claims 1-8, characterized in that, Includes the following steps: Step 1: When the oxygen concentration signal measured by the oxygen sensor is lower than the target value, the vacuum pump operates and opens the vacuum valve. When the high-temperature covering gas passes through, the shape memory alloy spring at the upper end of the metal connecting line reaches above the phase change temperature, changing from a stretched state in the original cold state to a compressed state. The arc-shaped metal plate connected to it blocks the outlet pipe under the action of tension. The arc-shaped metal plate undergoes slight deformation under the pressure difference brought by the metal connecting line and the vacuum, achieving a tight seal with the outlet pipe. The oxygen supply pipe is in a negative pressure sealed state. The coolant enters the oxygen supply pipe under the drive of the pressure difference, reacts with the PbO particles and dissolves, becoming a high oxygen concentration state. When the liquid level rises to the measurement height of the second liquid level gauge, the coolant flows into the outlet pipe. The arc-shaped metal plate falls back to a suspended state under the action of coolant pressure, and the coolant flows to the liquid surface of the device. The above process is repeated until the oxygen concentration reaches the target value. Step 2: When the oxygen concentration reaches or exceeds the target value, close the vacuum valve. Due to the tension of the metal connecting wire and the shape memory alloy spring at the top, some coolant will remain in the outlet pipe. When the vacuum pipe is cooled by the external environment and the internal temperature drops below the phase change temperature, the shape memory alloy spring returns to the stretched state, the arc-shaped metal plate leaves the outlet pipe, and the internal and external gas pressures reach the same level. The coolant remaining in the pipe is discharged to the liquid surface under the action of gravity, and the coolant in the oxygen replenishment pipe falls back to the liquid surface of the device. At this time, the oxygen control and oxygen replenishment process is completed.

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