Hydrogen injection device for pressurized water reactor primary loop based on micro / nano bubbles

Abstract

This invention provides a hydrogen injection device for the primary loop of a pressurized water reactor based on micro / nano bubbles, comprising: a hydrogen supply device and a microbubble generating device; the microbubble generating device includes a Venturi tube, the two ends of which are connected to the primary loop of the pressurized water reactor, and the hydrogen supply device is perpendicularly connected to the middle of the Venturi tube. The Venturi tube breaks up the injected hydrogen bubbles into micro / nano bubbles. The hydrogen injection device disclosed in this invention utilizes the structural characteristics of the Venturi tube to break up the injected bubbles into micro / nano bubbles, significantly improving mass transfer efficiency, accelerating the dissolution and mass transfer process of hydrogen in the coolant, reducing the space occupied by equipment and pipelines, and contributing to the miniaturization of reactor auxiliary equipment.

Description

Technical Field

[0001] This invention relates to the technical field of reactor hydrogen injection, specifically to a hydrogen injection device for the primary loop of a pressurized water reactor based on micro-nano bubbles, and more particularly to a high-efficiency hydrogen injection system using a venturi tube micro-nano bubble generator. Background Technology

[0002] During the operation of a pressurized water reactor nuclear power plant, the primary coolant is easily decomposed into hydrogen and oxygen under radiation, leading to an increase in dissolved oxygen content in the coolant. The dissolved oxygen in the coolant can easily cause electrochemical corrosion of the primary circuit metals, and the resulting corrosion products are easily activated into radioactive activation products under high radiation conditions, resulting in an increase in the radiation dose to the power plant.

[0003] Current deoxygenation methods primarily rely on the reversibility of the water irradiation decomposition reaction. By increasing the dissolved hydrogen content in the coolant (i.e., hydrogen injection), the equilibrium of the irradiation decomposition reaction shifts in the reverse direction, thereby reducing the dissolved oxygen content in the primary loop. However, the amount of hydrogen injected must be strictly controlled. On the one hand, excessive hydrogen injection leads to an excessively high dissolved hydrogen content, which can easily cause hydrogen embrittlement of the material. On the other hand, incompletely dissolved hydrogen bubbles can affect pump operation and core reactivity, requiring additional degassing and separation devices.

[0004] Existing small pressurized water reactors generally employ the traditional primary loop low-pressure hydrogen addition technology: the outflow from the primary loop is cooled and depressurized before entering the control tank, while low-pressure hydrogen is injected into the control tank for reaction. This technology requires depressurization followed by pressurization, resulting in high energy loss. It also increases the functions required of the control tank, and the overall equipment occupies a large space.

[0005] The AP1000 third-generation reactor eliminates the capacity control box and adopts high-pressure hydrogen injection technology, which involves directly injecting hydrogen into the primary loop after it has been cooled by a venting line. Compared to traditional technologies, direct hydrogen injection simplifies the system structure to some extent. However, the injected bubbles are larger, requiring longer pipelines for complete dissolution, resulting in higher space requirements. Furthermore, the slow response to changes in dissolved oxygen content makes it difficult to adjust the hydrogen injection rate in real time. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a hydrogen injection device for the primary loop of a pressurized water reactor based on micro-nano bubbles.

[0007] A hydrogen injection device for the primary loop of a pressurized water reactor based on micro-nano bubbles, provided by the present invention, includes: a hydrogen supply device and a microbubble generating device;

[0008] The microbubble generating device includes a venturi tube, the two ends of which are connected to the primary loop of a pressurized water reactor. The hydrogen supply device is vertically connected to the middle of the venturi tube, and the venturi tube breaks the injected hydrogen bubbles into micro-nano bubbles.

[0009] Preferably, it also includes a measurement section and a control system;

[0010] The measuring section is connected to the fluid outlet of the microbubble generator to obtain hydrogen content data in the circuit. The control system is connected to the hydrogen supply device and the measuring section to adjust the supply rate of the hydrogen supply device according to the measured hydrogen content data.

[0011] Preferably, the hydrogen supply device is connected to the straight section of the throat via an air inlet pipe, the constriction section and the expansion section have the same diameter, and the ratio of the diameter of the air inlet pipe to the diameter of the constriction section is 9:250 to 15:250.

[0012] Preferably, the microbubble generating device further includes an inlet straight pipe and an outlet straight pipe, and the Venturi tube includes a contraction section with a tapering angle of α, a throat straight pipe section with an air inlet, and an expansion section with a tapering angle of β; wherein the contraction section, the throat straight pipe section and the expansion section are connected in sequence, the contraction section is connected to the inlet straight pipe, and the expansion section is connected to the outlet straight pipe.

[0013] Preferably, the inlet straight pipe and the outlet straight pipe have the same diameter, the contraction angle α is 10.5°, the diameter ratio of the throat straight pipe section to the inlet straight pipe is 9:50, the length-to-diameter ratio of the throat straight pipe section is 1:1, and the expansion angle β is 7.5°.

[0014] Preferably, an air inlet for connecting to the air intake pipe is provided through the straight section of the throat, and the air inlet is located at 1 / 3 to 2 / 3 of the distance from the outlet of the constriction section on the straight section of the throat.

[0015] Preferably, the hydrogen injection device further includes a dissolution section, which is connected to the fluid outlet of the microbubble generator. The dissolution section is arranged in a curved spiral configuration, and the ratio of the total length of the dissolution section to the diameter of the outlet straight pipe is 5:1 to 20:1.

[0016] Preferably, the hydrogen supply device includes a high-pressure hydrogen cylinder, an inlet pipe, a solenoid valve, a manual shut-off valve, a hydrogen flow meter, and a pressure sensor. The high-pressure hydrogen cylinder, the solenoid valve, the manual shut-off valve, the hydrogen flow meter, and the pressure sensor are connected in sequence through the inlet pipe, and the pressure sensor is connected to a venturi tube through the inlet pipe.

[0017] Preferably, the measuring section is connected to the fluid inlet of the microbubble generator.

[0018] According to the present invention, a pressurized water reactor nuclear power plant includes a hydrogen injection device for the primary loop of the pressurized water reactor based on micro-nano bubbles.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The hydrogen injection device disclosed in this invention utilizes the structural characteristics of a venturi tube to break the injected bubbles into micro-nano bubbles, which significantly improves mass transfer efficiency, accelerates the process of hydrogen dissolving and transferring in the coolant, reduces the space occupied by equipment and pipelines, and contributes to the miniaturization of reactor auxiliary equipment.

[0021] 2. This invention accelerates the hydrogen dissolution reaction by setting up a dissolution section. The rapid dissolution reaction process helps to adjust the hydrogen injection amount with a low time delay, thereby improving the controllability of the deoxygenation process.

[0022] Other beneficial effects of the present invention will be explained in detail through the introduction of specific technical features and technical solutions in specific embodiments. Those skilled in the art should be able to understand the beneficial technical effects brought about by these technical features and technical solutions through the introduction of these technical features and technical solutions. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 This is a layout diagram of the hydrogen injection system provided by the present invention in the primary loop of a nuclear power plant.

[0025] Figure 2 This is a cross-sectional view of the Chinese-language tube design for the hydrogen injection system provided by the present invention.

[0026] Figure 3 The bubble size distribution diagram obtained by numerical calculation for the breakage of the Venturi tube provided by this invention.

[0027] Figure 4 A comparison chart showing the distances required for mass transfer of bubbles of different sizes, obtained through numerical calculations provided by this invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] Detailed Implementation

[0030] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0031] The present invention provides a compact hydrogen injection device for the primary loop of a pressurized water reactor based on micro-nano bubbles, which is applied to the micro-nano bubble hydrogen injection system for deoxygenation in the primary loop of a small nuclear power plant. It solves the problems of large hydrogen bubble size, long pipeline required for complete dissolution, large space occupation, and slow response to changes in dissolved oxygen content in existing high-pressure hydrogen injection technologies.

[0032] Reference Figure 1 As shown, the hydrogen injection device provided by the present invention includes a control system, a hydrogen supply device, an inlet section 1, a microbubble generating device, a dissolution section 4, a measuring section, and an outlet section 5. The inlet section 1, microbubble generating section, dissolution section 4, measuring section, and outlet section 5 are connected sequentially. The hydrogen supply device is connected to the microbubble generating section, and the measuring section and the hydrogen supply device are respectively connected to the control system.

[0033] In a preferred embodiment, a measuring section is also provided between the inlet section 1 and the microbubble generating device.

[0034] In the actual layout of this device, the inlet section 1 is located after the charging section of the primary coolant pipeline, and the outlet section 5 is located before the reactor coolant pump 12 in the primary coolant pipeline. One to three identical devices can be connected in parallel to increase the repeatability and reliability of the overall system.

[0035] The components of the hydrogen injection unit are described in detail below.

[0036] The microbubble generating device includes an inlet straight pipe, a Venturi tube 3, an inlet pipe 7, and an outlet straight pipe. The inlet straight pipe, Venturi tube 3, and outlet straight pipe are connected sequentially. The hydrogen supply device is vertically connected to the Venturi tube 3 via the inlet pipe 7. The diameters of the inlet straight pipe and the outlet straight pipe are the same as the diameter D0 of the primary loop main pipe, and the diameter d of the inlet pipe 7 is... g The ratio of the main pipeline diameter D0 to the main pipeline diameter D0 should be controlled between 9:250 and 15:250.

[0037] Specifically, refer to Figure 2 As shown, the Venturi tube 3 includes a contraction section with a tapering angle of α, a throat straight section with an inlet, and an expansion section with a diffusing angle of β. The contraction section, the throat straight section, and the expansion section are connected sequentially. The diameter D of the inlet straight pipe... i Same as the primary main pipe diameter D0, with a taper angle α of 10.5° and a throat diameter D. thThe ratio of the inlet diameter to the throat diameter is 9:50, and the throat length is l. th With throat diameter D th The ratio is 1:1, the divergence angle β is 7.5°, and the diameter D of the outlet straight pipe is... o Pipe diameter D of the inlet straight pipe i The same. The throat section passes through the air inlet, and the air inlet diameter d is the same as the throat diameter D. th The ratio is 1:5, and the air inlet is located at 1 / 3 to 2 / 3 of the distance from the outlet of the contraction section at the throat. Air inlets on both the upper and lower sides or on one side can be used. The hydrogen bubble size distribution in the Venturi tube 3 is as follows... Figure 3 As shown.

[0038] Specifically, the pipes in dissolution section 4 are arranged in an S-shaped spiral pattern, with a total length L to main pipe diameter D0 ratio of 5:1 to 20:1. A comparison diagram of the distances required for mass transfer of bubbles of different sizes is shown below. Figure 4 As shown.

[0039] Specifically, the measurement section includes a hydrogen concentration sensor 2 and a liquid flow sensor, and is connected to the control system. The hydrogen concentration sensor 2 is used to monitor the hydrogen content in the primary loop.

[0040] The hydrogen supply system includes a high-pressure hydrogen cylinder 6, a hydrogen control valve, a hydrogen flow meter 10, and a pressure sensor 11. The high-pressure hydrogen cylinder 6 has a pressure of 17–25 MPa and a hydrogen purity of over 99%. Additional hydrogen cylinders can be connected in parallel to meet this requirement. The hydrogen flow meter 10 monitors the hydrogen flow rate, with a required injection flow rate range of 200–600 NL / min. The pressure sensor 11 measures the hydrogen pressure in the inlet pipe 7. The hydrogen control valve, including a solenoid valve 8 and a manual shut-off valve 9, controls the hydrogen flow rate and is connected to the control system. One to three solenoid valves 8 can be connected in parallel to increase reliability. If a solenoid valve 8 fails, the hydrogen flow rate can be manually controlled.

[0041] The control system monitors the hydrogen content in the primary loop and adjusts the hydrogen supply as needed. When the hydrogen content detected in the primary loop is higher than 45-50 cc / kgH2O, the hydrogen supply is reduced by controlling solenoid valve 8; when the hydrogen content is lower than 20-25 cc / kgH2O, the hydrogen supply is increased by controlling solenoid valve 8.

[0042] The present invention also provides a pressurized water reactor nuclear power plant, wherein the pressurized water reactor nuclear power plant adopts the above-mentioned pressurized water reactor primary loop hydrogen injection device based on micro-nano bubbles.

[0043] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A hydrogen injection device for the primary loop of a pressurized water reactor based on micro / nano bubbles, characterized in that, Includes: hydrogen supply device and microbubble generation device; The microbubble generating device includes a venturi tube (3), the two ends of which are connected to the primary loop of the pressurized water reactor, and the hydrogen supply device is vertically connected to the middle of the venturi tube (3). The venturi tube (3) breaks the injected hydrogen bubbles into micro-nano bubbles. It also includes the measurement section and control system; The measuring section is connected to the fluid outlet of the microbubble generator to obtain hydrogen content data in the circuit. The control system is connected to the hydrogen supply device and the measuring section to adjust the supply rate of the hydrogen supply device according to the measured hydrogen content data. The microbubble generating device further includes an inlet straight pipe and an outlet straight pipe. The Venturi tube (3) includes a contraction section with a tapering angle of α, a throat straight pipe section with an air inlet, and an expansion section with a tapering angle of β. The contraction section, the throat straight pipe section, and the expansion section are connected in sequence. The contraction section is connected to the inlet straight pipe, and the expansion section is connected to the outlet straight pipe. The hydrogen supply device is connected to the throat straight pipe section through the air inlet pipe (7). The diameters of the contraction section and the expansion section are the same. The ratio of the diameter of the air inlet pipe (7) to the diameter of the primary loop main pipe is 9:250 to 15:

250.

2. The hydrogen injection device for the primary loop of a pressurized water reactor based on micro / nano bubbles according to claim 1, characterized in that, The inlet straight pipe and the outlet straight pipe have the same diameter, the contraction angle α is 10.5°, the diameter ratio of the throat straight pipe section to the inlet straight pipe is 9:50, the length-to-diameter ratio of the throat straight pipe section is 1:1, and the expansion angle β is 7.5°.

3. The hydrogen injection device for the primary loop of a pressurized water reactor based on micro / nano bubbles according to claim 1, characterized in that, An air inlet is provided through the straight section of the throat for connecting the air inlet pipe (7). The air inlet is located on the straight section of the throat at a distance of 1 / 3 to 2 / 3 from the outlet of the contraction section.

4. The hydrogen injection device for the primary loop of a pressurized water reactor based on micro / nano bubbles according to claim 1, characterized in that, It also includes a dissolving section (4), which is connected to the fluid outlet of the microbubble generator. The dissolving section (4) is arranged in a curved spiral shape, and the ratio of the total length of the dissolving section (4) to the diameter of the outlet straight pipe is 5:1 to 20:

1.

5. The hydrogen injection device for the primary loop of a pressurized water reactor based on micro / nano bubbles according to claim 1, characterized in that, The hydrogen supply device includes a high-pressure hydrogen cylinder (6), an inlet pipe (7), a solenoid valve (8), a manual shut-off valve (9), a hydrogen flow meter (10), and a pressure sensor (11). The high-pressure hydrogen cylinder (6), the solenoid valve (8), the manual shut-off valve (9), the hydrogen flow meter (10), and the pressure sensor (11) are connected in sequence through the inlet pipe (7). The pressure sensor (11) is connected to the venturi tube (3) through the inlet pipe (7).

6. The hydrogen injection device for the primary loop of a pressurized water reactor based on micro / nano bubbles according to claim 1, characterized in that, The measuring section is connected to the fluid inlet of the microbubble generator.

7. A pressurized water reactor nuclear power plant, characterized in that, Includes the hydrogen injection device for the primary loop of a pressurized water reactor based on micro-nano bubbles as described in any one of claims 1-6.

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