Pressurized laser flow measuring device and measuring method for liquid metal

Abstract

The invention discloses a pressurized laser flow measuring device and measuring method for liquid metal, and the pressurized laser flow measuring device for the liquid metal comprises a laser ranging unit, a data processing unit, a Venturi tube unit, an extension pressure measuring tube unit and a pressure control unit. By adopting a laser measurement technology, non-contact and high-precision liquid metal flow measurement can be realized, and the device is suitable for a corrosive liquid metal working environment.

Description

Technical Field

[0001] The present invention relates to the field of nuclear reactor engineering technology, and in particular to a device and method for measuring the flow rate of liquid metal coolant in a high-temperature, corrosive environment. The device and method adopt laser measurement technology, can realize non-contact, high-precision liquid metal flow measurement, and are suitable for liquid metal working environments in corrosive environments. Background Art

[0002] In the field of nuclear energy, lead-bismuth alloy plays a vital role as a coolant in fast neutron reactors. However, traditional coolant flow measurement technologies, such as turbine flowmeters and electromagnetic flowmeters, are often affected by high temperatures and corrosive environments, which makes the equipment easily damaged, reduces measurement accuracy, and has high maintenance costs, making it difficult to accurately measure liquid metal flow.

[0003] The flow measurement of liquid metal coolant with high temperature corrosive characteristics is a difficult problem in the nuclear industry. Liquid metal cooled reactors are usually in a high temperature corrosive environment, and any leakage or equipment failure may lead to serious nuclear safety accidents. Therefore, there are extremely strict requirements on the safety, accuracy and reliability of flow measurement devices.

[0004] At present, there are many flow meters suitable for liquid metal, such as electromagnetic flow meters, ultrasonic flow meters, vortex flow meters, etc. In order to reduce the risk of corrosion, the current measurement technology of liquid metal usually does not rely on direct contact measurement. For example, electromagnetic flow meters use the induced voltage generated by conductive media in the magnetic field to measure flow, and ultrasonic flow meters use the propagation time difference of ultrasonic waves in the fluid to indirectly measure. However, for electromagnetic flow meters, the problem of solid particle deposition and scaling in the fluid medium will affect the measurement accuracy, and the measurement channel needs to be frequently cleaned and maintained. At the same time, the manufacturing and installation costs are also high. The measurement signal is very sensitive to slight changes in the environment, and the measurement stability is not high. For ultrasonic flow meters, the measurement range is often limited, and it is also affected by bubbles in the tube. At the same time, the measurement accuracy of some ultrasonic flow meters decreases rapidly with the passage of operating time.

[0005] Traditional flow measurement technology is easily affected by liquid metal corrosion or impurities blocking the pipe wall, so a new type of non-contact high-precision flow measurement device is needed. Summary of the invention

[0006] Based on this, the primary purpose of the present invention is to provide a pressurized laser flow measurement device and method for liquid metal. The device and method use laser ranging technology combined with pressure compensation design to achieve flow measurement by accurately calculating the liquid level difference, and design key components to resist high temperature corrosion.

[0007] Another object of the present invention is to provide a pressurized laser flow measurement device and a measurement method for liquid metal. The device and method can measure the flow rate in the liquid metal channel with low cost and high precision. At the same time, due to the non-contact pressure measurement feature, direct contact between the measurement device and the liquid metal medium is avoided, thereby reducing the increase in flow accuracy measurement error caused by the corrosion of the pressure measurement device, and increasing the accuracy and service life of the flowmeter.

[0008] Another object of the present invention is to provide a pressurized laser flow measurement device and a measurement method for liquid metal. The device and method use argon gas pressurization to reduce the height of the extended pressure measurement tube, ensuring the stability of the internal liquid lead-bismuth liquid level; moreover, the measurement accuracy is high and the anti-interference ability is strong; the design is simple and the manufacturing cost is low.

[0009] To achieve the above object, the technical solution of the present invention is as follows:

[0010] A pressurized laser flow measurement device for liquid metal, the device includes a laser ranging unit, a data processing unit, a Venturi tube unit, an extended pressure measurement tube unit and a pressure control unit, wherein:

[0011] Laser ranging unit: Corresponding to the extended pressure measurement tube unit to measure the liquid level data of the "extended pressure measurement tube", including a high-precision laser ranging sensor, a sensor mounting bracket and a data output interface; the laser ranging sensor is arranged on the sensor mounting bracket and outputs the liquid level data of the "extended pressure measurement tube" through the data output interface;

[0012] Data processing unit: The data processing unit receives the liquid level data of the "extended pressure measurement tube" transmitted by the laser ranging unit, uses the built-in differential pressure calculation module to count the liquid level difference of the "extended pressure measurement tube", thereby calculating the static differential pressure of the liquid metal at the contraction section and the throat of the Venturi tube, and further calculating the flow velocity of the liquid metal;

[0013] The Venturi tube unit includes three main parts: a contraction section, a throat and a diffusion section. The contraction section, the throat and the diffusion section are connected in sequence. When the fluid passes through the contraction section, the flow velocity gradually increases and the pressure decreases; it reaches the maximum flow velocity and the minimum pressure when passing through the throat; finally, in the diffusion section, the flow velocity decreases and the pressure rises;

[0014] Extended pressure measurement tube unit: Includes an extended pressure measurement tube and fins. The extended pressure measurement tube is connected to the contraction section and the throat of the Venturi tube to calculate the static differential pressure of the liquid metal at the contraction section and the throat of the Venturi tube. The pipe of the extended pressure measurement tube has annular fins, which increase the heat transfer area of the pipe wall, reduce the internal gas temperature, and avoid the thermal stress cracking of the pressure-resistant glass;

[0015] Pressure control unit: Connected to the extended pressure measuring tube unit, it can effectively adjust the internal pressure of the system, prevent the overflow of lead-bismuth alloy, and set protection measures. When overflow occurs and the internal pressure of the system is disordered, the pipeline will introduce the overflowed lead-bismuth alloy into the overflow tank, thus effectively protecting the equipment and preventing it from polluting the environment.

[0016] Furthermore, the laser ranging unit further includes a protective housing; the protective housing covers the laser ranging sensor and the sensor mounting bracket to protect the laser ranging sensor.

[0017] Furthermore, at the top of the extended pressure measuring tube, it corresponds to the laser ranging unit through a pressure-resistant glass window. The laser ranging unit can accurately measure the liquid level position and height change in the tube through the pressure-resistant glass window, so as to realize non-contact liquid level monitoring.

[0018] Furthermore, the ratio of the throat diameter to the inlet diameter of the contraction section of the venturi tube is 0.6. At this diameter ratio, the measurement accuracy and measurement stability are relatively high. The length of the contraction section is 10 times the pipe diameter, and the diffuser section is 4 times the pipe diameter, ensuring the full development of the flow of liquid metal in the tube and enhancing the flow measurement accuracy.

[0019] Furthermore, the extended pressure measuring tube is connected to the contraction section and the throat of the venturi tube. The inner diameter of the connection of the extended pressure measuring tube is 10 mm, the outer diameter is 12 mm, and the height is 125 mm. 10 annular fins are provided on the pipeline of each extended pressure measuring tube, each with a thickness of 1 mm and a radius extended to 15 mm, so as to increase the total heat transfer surface of the extended pressure measuring tube.

[0020] Furthermore, to prevent the lead-bismuth fluid from contacting the pressure-resistant glass window when the liquid level is too high under high pressure, the pressure control unit is an overflow tank provided beside the extended pressure measuring tube, which is used to collect the overflowed lead-bismuth alloy when the pressure abnormally rises, preventing equipment damage and environmental pollution.

[0021] Furthermore, an argon pressurization window is provided at the connection of the overflow tank. The system is pressurized by controlling the injection amount of argon. At the same time, the argon gas cylinder injects argon into the pipeline through the gas release valve to ensure the stability of the lead-bismuth liquid level in the pressure measuring tube and inhibit the overflow of lead-bismuth fluid; argon is an inert gas. Lead-bismuth alloy reacts with oxygen to form lead oxide, which has strong corrosiveness and is easy to block the pipeline. Therefore, filling argon can reduce the oxygen concentration in the pipeline and avoid the reaction between the two.

[0022] A pressurized laser flow measurement method for liquid metal includes the following steps:

[0023] Step 1: Add a parallel main flow direction pipeline connection between the two extended pressure measuring tubes of the venturi tube to ensure that the air space pressures at the upper parts of the two extended pressure measuring tubes are the same;

[0024] Step 2: Pressurize by connecting argon gas above the extended piezometric tube.

[0025] Step 3: Open a small channel above the extended piezometric tube and encapsulate it with pressure-resistant glass to form a pressure-resistant glass window as the light path for the laser ranging module.

[0026] Step 4: Extend a gas input interface on one side of the connecting pipe in Step 1 for injecting argon gas.

[0027] Step 5: A temporary pressure relief port is provided below the argon gas injection port in Step 4 to prevent instantaneous overflow of the liquid metal surface caused by abnormal pressure, which may lead to thermal stress cracking due to the contact between lead bismuth and the pressure-resistant glass window.

[0028] Step 6: Measure the liquid metal flow rate, including the following steps:

[0029] 6.1: Utilize the light-impermeable property of liquid metal to obtain the liquid level heights in the extended piezometric tubes at the inlet position of the Venturi tube and the throat position of the Venturi tube through the laser ranging module.

[0030] 6.2: Transmit the laser ranging signal to the calculation unit to obtain the liquid level height difference between the two extended piezometric tubes:

[0031] ΔH = H1 - H2 - H3

[0032] 6.4: Consider the mass flow rate formula of the static pressure differential flowmeter:

[0033] ΔP = ρgΔH

[0034]

[0035] For compressible fluids:

[0036]

[0037] The uncertainty limit can be calculated using the procedure given in Chapter 8 of GB / T 2624.1 - 2006.

[0038] For the volume flow rate, it can be determined using the following formula:

[0039]

[0040] Among them, ΔH is the liquid level height difference in the two extended piezometric tubes, H1 is the laser ranging distance of the extended piezometric tube at the throat position, H2 is the laser ranging distance of the extended piezometric tube at the inlet, and H3 is the relative height difference between the two pipes. ρ1 and ρ2 are the fluid densities at the inlet and throat of the Venturi tube, and A1 and A2 are the cross-sectional areas of the inlet and throat of the Venturi tube. ε is the expansibility coefficient of the Venturi tube, and d is the diameter value under the working conditions of the Venturi tube. It is necessary to measure the fluid density and viscosity under the working conditions, which are obtained from the temperature correlation formula pre-input into the acquisition device.

[0041] Furthermore, the gas in the connecting pipe needs to be cooled, and the cooling method is as follows:

[0042] 1. Install annular fins on the upper half of the two extended piezometric tubes for gas heat dissipation and cooling;

[0043] 2. Calculation of the temperature difference after introducing the fins:

[0044]

[0045] For the annular fin, the form of the solution can be expressed by the modified Bessel function, and its solution is:

[0046]

[0047] Among them, T(r) is the fin temperature at the fin radius r, T(R) is the pipe temperature, T ∞ is the ambient temperature, h is the convective heat transfer coefficient, k is the thermal conductivity, t is the fin thickness, and I0, I1, K0, and K1 are the modified Bessel functions.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] 1. The present invention adopts non-contact laser pressure measurement, avoiding the direct contact between the measuring device and the liquid metal medium, and the measuring device is not affected by the corrosion conditions.

[0050] 2. The present invention uses argon pressurization to reduce the height of the extended piezometric tube and ensure the stability of the internal liquid lead-bismuth liquid level. 3. The design of the temporary pressure relief port of the present invention safeguards against the situation where the pressure-resistant glass may be broken due to the contact of liquid metal when the instantaneous height of the liquid level is too high, improving the operating safety.

[0051] 4. The present invention has a simple design and low manufacturing cost.

[0052] 5. The present invention uses the liquid level difference to analyze the pressure difference, with a high measurement accuracy level and strong anti-interference ability.

[0053] In summary, the pressurized laser flow measurement method provided by the present invention can measure the flow rate in a liquid metal channel with low cost and high precision. At the same time, due to its non-contact pressure measurement feature, it avoids the contact between the liquid metal and the pressure measurement device, thereby reducing the measurement error of the flow rate accuracy caused by the corrosion of the pressure measurement device, and increasing the accuracy and lifespan of the flowmeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic diagram of the measurement process implemented by the present invention.

[0055] Figure 2 It is a schematic diagram of the device structure implemented by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following will clearly and completely describe the technical methods in the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described are some embodiments of this application, rather than all embodiments. In addition, in the following description, the descriptions of well-known structures and existing technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0057] Figure 2 As shown, it shows the contraction section, throat section, diffusion section of the Venturi tube, the connection method with the pressure measurement tube, the laser ranging sensor, etc. and their positional relationships. The embodiment of the present invention is a pressurized laser flow measurement device for liquid metal. As shown in the figure, the device includes a laser ranging unit 203, a data processing unit, a Venturi tube 201, an extended pressure measurement tube unit, and a pressure control unit.

[0058] Among them: The laser ranging unit 203: corresponding to the extended pressure measurement tube unit to measure the liquid level data of the "extended pressure measurement tube", including a high-precision laser ranging sensor, a sensor mounting bracket, and a data output interface; the laser ranging sensor is arranged on the sensor mounting bracket and outputs the liquid level data of the "extended pressure measurement tube" through the data output interface.

[0059] The laser ranging unit 203 also includes a protective housing; the protective housing covers the laser ranging sensor and the sensor mounting bracket to protect the laser ranging sensor. The laser ranging sensor uses a red semiconductor laser with a wavelength of 655 nm, and the measurement center distance range is 65 mm - 135 mm, with high repeatability and low temperature drift characteristics to ensure measurement stability in a dynamic environment with floating liquid levels.

[0060] Data processing unit: The laser ranging unit communicates with the data processing unit in a wired manner. The data processing unit receives the liquid level data of the "extended piezometric tube", and uses the built-in differential pressure calculation module to calculate the liquid level difference of the "extended piezometric tube", thereby calculating the static pressure difference of the liquid metal in the contraction section and the throat of the Venturi tube, and further calculating the flow rate of the liquid metal.

[0061] The Venturi tube 201 includes three main parts: a contraction section, a throat, and a diffuser section. The contraction section, the throat, and the diffuser section are connected in sequence. When the fluid passes through the contraction section, the flow rate gradually increases and the pressure decreases; it reaches the maximum flow rate and the minimum pressure when passing through the throat; finally, in the diffuser section, the flow rate decreases and the pressure rises.

[0062] Extended piezometric tube unit: It includes an extended piezometric tube 202 and fins 205. The extended piezometric tube 202 is connected to the contraction section and the throat of the Venturi tube 201 to calculate the static pressure difference of the liquid metal in the contraction section and the throat of the Venturi tube. The pipe of the extended piezometric tube 202 has annular fins 205, which reduce the internal fluid temperature by increasing the heat transfer area of the pipe wall and prevent the thermal stress cracking of the pressure-resistant glass.

[0063] There are two extended piezometric tubes 202. One is located in front of the contraction section of the Venturi tube 201, and the other is located in the throat of the Venturi tube 201. The upper parts of the two extended piezometric tubes 202 are connected by a connecting pipe 212 to ensure that the air space pressures in the upper parts of the two extended piezometric tubes 202 are the same.

[0064] Pressure control unit: It is connected to the extended piezometric tube unit and can effectively adjust the internal pressure of the system. While preventing the overflow of lead-bismuth alloy, protection measures are set. When it overflows and the internal pressure of the system is disordered, the pipe will introduce the overflowed lead-bismuth alloy into the overflow tank, thus effectively protecting the equipment and preventing it from polluting the environment.

[0065] Specifically, as follows:

[0066] 1. Laser ranging unit 203: The laser ranging unit of the present invention is used to measure the height difference of liquid metal in the "extended piezometric tube" in a high-temperature environment and obtain accurate lead-bismuth liquid level information in the "extended piezometric tube". This unit mainly consists of a high-precision laser ranging sensor, a sensor mounting bracket, a data output interface, and a protective housing.

[0067] Laser ranging sensor: The laser ranging sensor used in this device is based on the principle of triangulation. The light source is a red semiconductor laser with a wavelength of 655 nm and a maximum output power of 1 mW, meeting the Class II laser safety standard. The sensor has a small spot diameter and is suitable for high-precision measurements. The measurement center distance range is 65 mm - 135 mm. Through high repeatability accuracy (70 μm) and low temperature drift characteristics (0.03% F.S. / °C), it ensures measurement stability in a dynamic environment with liquid level fluctuations.

[0068] Sensor mounting bracket: The bracket design takes into account the installation angle requirements of the sensor and allows adjustment within the range of 90° ± 15° to ensure that the laser is perpendicular to the liquid metal surface. The bracket is made of high-temperature resistant and corrosion-resistant 316L steel and can be finely adjusted to ensure measurement accuracy and stability.

[0069] Output interface: This sensor supports multiple output modes, including analog output (0 - 5V or 4 - 20mA) and RS485 communication interface, facilitating integration with different types of data processing devices. The output interface has short-circuit protection and overload protection functions, adapting to the complex data transmission requirements in industrial environments.

[0070] Protective housing: The housing is made of corrosion-resistant metal materials and meets the IP67 protection level, effectively preventing the impact of liquid metal splashing and high temperature and humidity on the sensor, and extending the device life. The housing design ensures the cleanliness of the laser emission and reception channels, avoiding light path occlusion, thereby improving measurement reliability.

[0071] 2. Data processing unit: The data processing unit of the present invention has significant advantages in real-time calculation and precise control. This unit receives the liquid level data of the "extended piezometric tube" transmitted by the laser ranging unit, and uses the built-in differential pressure calculation module to calculate the liquid level difference of the "extended piezometric tube", thereby calculating the static pressure difference of the liquid metal at the inlet and throat of the Venturi tube. According to Bernoulli's principle, the flow rate of the liquid metal is further calculated.

[0072] Real-time data processing and filtering function: The data processing unit has real-time calculation capabilities, can quickly process data in a dynamic flow environment, and removes measurement noise through the built-in filtering algorithm to ensure the accuracy and stability of the flow rate data.

[0073] Intelligent compensation and adaptability: To adapt to high-temperature and highly corrosive environments, this unit also has an intelligent compensation function, which can automatically correct the changes in fluid density and viscosity caused by temperature changes to ensure the accuracy of flow rate measurement.

[0074] Multi-interface compatibility: The data processing unit supports multiple data interfaces, including analog output and RS485 interfaces, facilitating integration into the host computer or other monitoring systems to achieve real-time monitoring and remote transmission of flow rate data.

[0075] The calculation module is optimized to quickly respond to changes in liquid flow and adapt to real-time calculations under different flow conditions.

[0076] 3. Venturi tube unit: The Venturi tube unit in the present invention is a key component for measuring the flow rate of corrosive liquid metal. It is necessary to ensure that the flow velocity and pressure difference of the fluid can be accurately measured under high temperature, high pressure and corrosive environments. The Venturi tube 201 includes three main parts: a contraction section, a throat section, and a diffusion section. When the fluid passes through the contraction section, the flow velocity gradually increases and the pressure decreases; it reaches the maximum flow velocity and the minimum pressure at the throat section; finally, in the diffusion section, the flow velocity decreases and the pressure rises. In the present invention, the Venturi tube 201 has a throat diameter of 60 mm and an inlet diameter of the contraction section of 100 mm. The ratio of the throat diameter to the inlet diameter of the contraction section of the Venturi tube 201 is 0.6. At this diameter ratio, the measurement accuracy and measurement stability are relatively high. Through computational fluid dynamics analysis, the length of the contraction section is 10 times the pipe diameter, and the length of the diffusion section is 4 times the pipe diameter, ensuring the full development of the flow of liquid metal in the pipe and enhancing the flow measurement accuracy; to cope with the corrosiveness of liquid metal, the Venturi tube is made of 316L steel, ensuring that a stable protective oxide film can be formed in the lead-bismuth environment, delaying corrosion and erosion.

[0077] 4. Extended pressure measuring tube unit: The extended pressure measuring tube 202 designed in this device is made of 316L steel, with an inner diameter of 10 mm, an outer diameter of 12 mm, and a height of 125 mm. 10 annular fins 205 are used on the pipe, each with a thickness of 1 mm and a radius extended to 15 mm. This design can increase the total heat transfer surface of the extended pressure measuring tube 202 by 4 times. Through numerical simulation methods, the lowest temperature inside the "extended pressure measuring tube" can be ensured to be reduced to below 40 °C to avoid thermal stress cracking of the pressure-resistant glass at the top position of the extended pressure measuring tube.

[0078] 5. Pressure control unit: The pressure control unit in the present invention includes an overflow tank 208, an argon gas pressurization window 209, a bleed valve 210, and an argon gas cylinder 211. It can effectively adjust the internal pressure of the system, prevent the overflow of lead-bismuth alloy, and set protective measures at the same time. When an overflow occurs, when the internal pressure of the system is disordered, the pipeline will lead the overflowing lead-bismuth alloy into the overflow tank, thus effectively protecting the equipment and preventing it from polluting the environment.

[0079] At the same time, in order to ensure that the flowmeter adapts to different operating pressure environments and avoid contact between liquid metal and pressure-resistant glass, the system is provided with an argon gas pressurization system, which is connected to the argon gas cylinder through a bleed valve. The argon gas cylinder injects argon gas into the "extended pressure measuring tube" through the bleed valve, and the injected gas pressure is between one-tenth of an atmospheric pressure and one-half of an atmospheric pressure. The argon gas pressurization system reduces the fluid height inside the extended pressure measuring tube and reduces the volume requirement of the flowmeter.

[0080] Specifically, the Venturi tube 201 is used to throttle the lead-bismuth alloy fluid, thereby generating a differential pressure signal. The extended pressure measuring tube 202 extends in the vertical direction, and annular fins 205 are equidistantly arranged on its outer wall. By increasing the heat transfer area of the tube wall, these fins reduce the internal gas temperature and prevent the thermal stress cracking of the pressure-resistant glass. The top of the extended pressure measuring tube 202 is a pressure-resistant glass window 204. Above the pressure-resistant glass window, a laser ranging unit 203 is provided. The laser ranging unit 203 can accurately measure the liquid level position and height change inside the tube through the pressure-resistant glass window 204, thereby realizing non-contact liquid level monitoring. The pressure-resistant glass window 204 has high strength and high light transmittance, ensuring that it can still provide a clear and reliable measurement path for the laser signal in high-temperature and high-pressure environments. The sensor mounting bracket 206 is used to fix and adjust the position and direction of measurement components such as the laser ranging unit 203, so as to obtain stable measurement data. The data transmission line 207 provides a data output and transmission interface, facilitating data recording and analysis on external devices.

[0081] To prevent the lead-bismuth fluid from contacting the pressure-resistant glass window when the liquid level is too high under high pressure, an overflow tank 208 is provided beside the extended pressure measuring tube 202 of this device, which is used to collect the overflowed lead-bismuth alloy when the pressure abnormally rises, preventing equipment damage and environmental pollution. At the same time, an argon pressurization window 209 is set at the connection of the overflow tank 208, and the system is pressurized by controlling the injection amount of argon. The argon gas cylinder 211 injects argon into the pipeline through the gas release valve 210 to ensure the stability of the lead-bismuth liquid level in the pressure measuring tube and inhibit the overflow of the lead-bismuth fluid.

[0082] In the present invention, the laser ranging unit 203 is combined with the Venturi tube 201. The "extended pressure measuring tube" liquid level difference is obtained by using the extended pressure measuring tube 202, thereby calculating the static pressure difference of the liquid metal at the inlet and throat of the Venturi tube. Furthermore, according to Bernoulli's principle, the flow rate of the liquid metal is calculated.

[0083] Figure 1 As shown, the method of the present invention is a pressurized laser flow measurement method for liquid metal, including the following steps:

[0084] Step 1: A parallel main flow direction pipeline is connected between the two extended pressure measuring tubes led out from the Venturi tube to form a communication pipeline 212, ensuring that the upper air space pressures of the two extended pressure measuring tubes 202 are the same.

[0085] Step 2: The upper part of the extended pressure measuring tube 202 is connected to argon for pressurization.

[0086] Step 3: A small hole is opened above the extended pressure measuring tube 202 and encapsulated with pressure-resistant glass to form a pressure-resistant glass window 204 as the light path of the laser ranging module.

[0087] Step 4: On one side of the connecting pipe 212 in Step 1, a gas inlet pipe 213 extends to inject argon. The gas inlet pipe 213 is connected to the extended pressure measuring pipe 202 and the argon gas cylinder 211. The argon gas cylinder 211 injects argon into the extended pressure measuring pipe 202 through the gas release valve 210. Meanwhile, the connecting pipe 212 is also connected to the overflow tank 208 to collect the overflowing lead-bismuth alloy when the pressure abnormally rises, preventing equipment damage and environmental pollution.

[0088] Step 5: Below the argon gas injection port in Step 4, a temporary pressure relief port is provided to prevent the instantaneous overflow of the liquid metal surface due to an instantaneous abnormal pressure, which may cause thermal stress cracking when the lead-bismuth contacts the pressure-resistant glass window.

[0089] Step 6: Conduct liquid metal flow measurement, including the following steps:

[0090] 6.1. Utilize the light-impermeable property of the liquid metal to obtain the liquid levels in the extended pressure measuring pipes at the entrance position of the Venturi pipe and at the throat position of the Venturi pipe through the laser ranging module.

[0091] 6.2. Transmit the laser ranging signal to the calculation unit to obtain the liquid level height difference between the two extended pressure measuring pipes:

[0092] ΔH = H1 - H2 - H3 (1)

[0093] 6.3. Consider the mass flow formula of the static pressure differential flowmeter:

[0094] AP = ρgΔH (2)

[0095]

[0096] For compressible fluids:

[0097]

[0098] The uncertainty limit can be calculated using the procedure given in Chapter 8 of GB / T 2624.1 - 2006.

[0099] For the volume flow rate, it can be determined using the following formula:

[0100]

[0101] Among them, ΔH is the liquid level height difference between the two extended piezometric tubes, H1 is the laser ranging distance of the extended piezometric tube at the throat position, H2 is the laser ranging distance of the extended piezometric tube at the inlet, and H3 is the relative height difference between the two pipelines. ρ1 and ρ2 are the fluid densities at the inlet and throat of the Venturi tube, and A1 and A2 are the cross-sectional areas of the inlet and throat of the Venturi tube. ε is the expansibility coefficient of the Venturi tube, and d is the diameter value under the working conditions of the Venturi tube. It is necessary to measure the fluid density and viscosity under the working conditions, which are obtained from the temperature correlation formula pre-entered into the acquisition device.

[0102] Among them, the gas in the connecting pipeline 212 needs to be cooled, and the cooling method is as follows:

[0103] 1. Install annular fins on the upper half of the two extended piezometric tubes 202 for gas heat dissipation and cooling.

[0104] 2. Calculation of the temperature difference after introducing the fins:

[0105]

[0106] For the annular fin, the form of the solution can be expressed by the modified Bessel function, and its general solution is:

[0107]

[0108] Among them, T(r) is the fin temperature at the fin radius r, T(R) is the pipe temperature, T ∞ is the ambient temperature, h is the convective heat transfer coefficient, k is the thermal conductivity, t is the fin thickness, I0, I1, K0, and K1 are the modified Bessel functions.

[0109] Combined with Figure 1 as shown, the specific steps implemented by the present invention are as follows:

[0110] 101. Check whether the connections of all components are correct and firm.

[0111] 102. Turn on the power supplies of the laser ranging unit and the data processing unit.

[0112] 103. Open the argon pressure supply device and fill argon into the piezometric tube.

[0113] 104. The laser ranging unit performs self-check and calibration to ensure the measurement accuracy.

[0114] 105. Confirm that the liquid metal in the piezometric tube is within the expected range.

[0115] 106. Measure the pipeline liquid level difference through the laser ranging unit.

[0116] 107. Transmit the measured liquid level height to the data processing unit.

[0117] 108. The data processing unit calculates the pressure difference and flow velocity based on the Bernoulli equation and the fluid mechanics formula.

[0118] 109. Filter the measurement data to eliminate noise and outliers.

[0119] 110. Store the measurement results in a data storage device for subsequent analysis and recording.

[0120] 111. Determine whether the measurement data exceeds a preset safety limit. If yes, proceed to step 112; otherwise, go to step 106.

[0121] 112. Perform alarm processing and display the alarm information and abnormal parameters on the display screen.

[0122] 113. Regulate the system pressure through an argon gas pressurization device.

[0123] In summary, the present invention adopts non-contact laser pressure measurement, avoiding direct contact between the measurement device and the liquid metal medium, and the measurement device is not affected by corrosion conditions. The design is simple and the manufacturing cost is low.

[0124] The pressurized laser flow measurement method provided by the present invention can measure the flow rate in the liquid metal channel with high precision at a low cost. At the same time, due to the non-contact pressure measurement feature, it prevents the liquid metal from being corroded and causing measurement errors in flow accuracy, increasing the accuracy and lifespan of the flowmeter.

[0125] The specific embodiments described above are exemplary and non-restrictive. Various solutions and all their variations that can be conceived by those skilled in the art under the inspiration of the disclosure of the present invention are included in the present invention.

Claims

1. A pressurized laser flow measurement device for liquid metal, characterized in that A pressurized laser flow measurement device for liquid metal, the device comprises a laser distance measuring unit, a data processing unit, a venturi tube unit, an extended pressure measuring tube unit and a pressure control unit, wherein: Laser ranging unit: corresponds to the extended pressure measuring tube unit, to measure the liquid level data of the "extended pressure measuring tube", including a high-precision laser ranging sensor, a sensor mounting bracket, and a data output interface; the laser ranging sensor is arranged on the sensor mounting bracket, and outputs the liquid level data of the "extended pressure measuring tube" to the outside through the data output interface; Data processing unit: The data processing unit receives the "extended pressure measuring tube" liquid level data transmitted by the laser ranging unit, uses the built-in pressure difference calculation module to count the "extended pressure measuring tube" liquid level difference, thereby calculating the static pressure difference of the liquid metal at the inlet and throat of the venturi tube, and further calculates the flow rate of the liquid metal: The venturi tube unit includes three main parts: the contraction section, the throat and the diffusion section. The contraction section, the throat and the diffusion section are connected in sequence. When the fluid passes through the contraction section, the flow velocity gradually increases and the pressure decreases; it reaches the maximum flow velocity and the minimum pressure when passing through the throat; finally, in the diffusion section, the flow velocity decreases and the pressure rises; the ratio of the throat diameter to the inlet diameter of the contraction section of the venturi tube is 0.

6. Under this diameter ratio, the measurement accuracy and measurement stability are high. The length of the inlet section is 10 times the tube diameter, and the outlet section is 4 times the tube diameter, which ensures that the flow of liquid metal in the tube is fully developed and the flow measurement accuracy is enhanced; Extended pressure measuring tube unit: including an extended pressure measuring tube and fins, wherein the extended pressure measuring tube is connected to the venturi tube, and the pipe of the extended pressure measuring tube has an annular fin, which reduces the internal gas temperature by increasing the heat exchange area of ​​the pipe wall and avoids thermal stress cracking of the pressure-resistant glass; Pressure control unit: connected to the extended pressure measuring tube unit, it can effectively adjust the internal pressure of the system to prevent the overflow of lead-bismuth alloy and set up protection measures. When overflow occurs, when the internal pressure of the system is disturbed, the pipeline will guide the overflowed lead-bismuth alloy into the overflow box, thereby effectively protecting the equipment and preventing it from polluting the environment.

2. The pressurized laser flow measurement device for liquid metal according to claim 1, characterized in that The laser distance measuring unit also includes a protective shell; the protective shell covers the laser distance measuring sensor and the sensor mounting bracket to protect the laser distance measuring sensor.

3. The pressurized laser flow measurement device for liquid metal according to claim 1, characterized in that: A pressure-resistant glass window is provided at the top of the extended pressure measuring tube to correspond to the laser ranging unit. The laser ranging unit can accurately measure the position and height change of the liquid surface in the tube through the pressure-resistant glass window, thereby realizing non-contact liquid level monitoring.

4. The pressurized laser flow measurement device for liquid metal according to claim 1, characterized in that: The extended pressure gauge is connected to the contraction section and throat of the venturi tube. The inner diameter of the extended pressure gauge is 10mm, the outer diameter is 12mm, and the height is 125mm. Each extended pressure gauge is provided with 10 annular fins, each with a thickness of 1mm and a radius extended to 15mm, so as to increase the total heat exchange surface area of ​​the extended pressure gauge.

5. The pressurized laser flow measurement device for liquid metal according to claim 1, characterized in that: The pressure control unit is an overflow box provided beside the extended pressure measuring tube, which is used to collect the overflowed lead-bismuth alloy when the pressure rises abnormally to prevent equipment damage and environmental pollution; an argon pressurization window is provided at the connection of the overflow box, and the system is pressurized by controlling the injection amount of argon. At the same time, the argon cylinder injects argon into the pipeline through the vent valve to ensure the stability of the lead-bismuth liquid level in the pressure measuring tube and inhibit the overflow of the lead-bismuth fluid, while reducing the oxygen concentration in the pipeline to prevent the lead-bismuth alloy from reacting with oxygen to block the pipeline.

6. The pressurized laser flow measurement device for liquid metal according to claim 4, characterized in that: Annular fins are installed on the upper parts of the two extended pressure measuring tubes.

7. A pressurized laser flow measurement method for liquid metal, characterized in that; The method uses the measuring device described in claim 1 to perform measurement, and the specific steps are as follows: The steps include: Step 1: Connect two extended pressure measuring tubes from the venturi tube with a parallel pipeline in the mainstream direction to ensure that the upper air space pressure of the two extended pressure measuring tubes is the same; Step 2, extending the pressure measuring tube to connect argon gas for pressurization; Step 3: Open a small channel above the extended pressure measuring tube and encapsulate it with pressure-resistant glass to form a pressure-resistant glass window as a light channel for the laser ranging module; Step 4: Extend a gas input interface on one side of the connecting pipeline in step 1 to inject argon gas; Step 5: A temporary pressure relief port is provided below the argon injection port in step 4 to prevent the instantaneous abnormal pressure from causing the liquid metal surface to overflow instantly, causing thermal stress cracking when the lead and bismuth come into contact with the pressure-resistant glass window; Step 6, measuring the liquid metal flow rate, includes the following steps: 6.

1. Using the opaque property of liquid metal, the laser ranging module is used to obtain the liquid level height in the extended pressure measuring tube at the entrance of the Venturi pipe and the extended pressure measuring tube at the throat of the Venturi pipe; 6.

2. Transmit the laser ranging signal to the calculation unit to obtain the height difference of the liquid levels in the two extended pressure measuring tubes: ΔH=H1-H2-H3 6.3、Mass flow formula of flowmeter considering static pressure difference: ΔP=ρgΔH For compressible fluids: The uncertainty limits can be calculated using the procedure given in Chapter 8 of GB / T2624.1-2006; The volume flow rate can be determined using the following formula: in, ΔH is the height difference of the liquid level in the two extended pressure gauges, H1 is the laser ranging distance of the extended pressure gauge at the throat position, H2 is the laser ranging distance of the extended pressure gauge at the inlet, and H3 is the relative height difference between the two pipes. ρ1 and ρ2 are the fluid densities at the inlet and throat of the Venturi tube, A1 and A2 are the inlet and throat cross-sectional areas of the Venturi tube. ε is the expansion coefficient of the Venturi tube, and d is the diameter value of the Venturi tube under working conditions. The fluid density and viscosity under working conditions must be measured, which is obtained by the temperature correlation formula pre-entered into the acquisition equipment.

8. The pressurized laser flow measurement method for liquid metal according to claim 1, characterized in that; The gas in the Unicom pipeline needs to be cooled down by: A. Annular fins are installed on the upper part of the two outlet pipes to dissipate heat and cool the gas; B. Calculation of temperature difference after introducing fins: For annular fins, the solution can be expressed by the improved Bessel function, and its solution is: Where, T(r) is the fin temperature at the fin radius r, T(R) is the pipe temperature, T ∞ is the ambient temperature, h is the convection heat transfer coefficient, k is the thermal conductivity, t is the fin thickness, I0, I1, K0, K1 are modified Bessel functions.

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