Liquid lithium flow level measurement device and method

Abstract

The application discloses a liquid lithium flowing liquid level measuring device and method, and relates to the technical field of flowing liquid level measurement.The device comprises a probe for collecting a voltage signal of liquid lithium, a displacement table for moving the probe, a digital multimeter for measuring the voltage signal value collected by the probe, and a processing unit for processing the voltage signal of liquid lithium to obtain a square wave signal and maximum and minimum liquid levels of liquid lithium.A waveform diagram of a target measuring point is obtained according to the square wave signal and the maximum and minimum liquid levels of liquid lithium, and liquid level information of the target measuring point changing with time is obtained.The application measures the conductivity when liquid lithium and the probe are in contact, and uses the displacement table to gradually move the probe to obtain the square wave signal and the voltage signal during the measurement process.A time-liquid level scatter diagram is drawn according to the square wave signal and the voltage signal, and fitting is performed, so that the change of the liquid level at the measuring point with time and the liquid level extreme value can be obtained.

Description

Technical Field

[0001] This invention relates to the field of flowing liquid level measurement technology, and in particular to a liquid lithium flowing liquid level measurement device and method. Background Technology

[0002] Currently, in the research of controlled nuclear fusion, it has been found that the interaction between solid plasma-facing components (PFCs) and the strong heat and ion fluxes from high-temperature plasma can cause damage to the first wall, thus forcing the controlled nuclear fusion device to shut down. Liquid metal PFCs, with their excellent heat transfer properties and self-healing capabilities, hold promise as a replacement for solid PFCs, enabling the entire device to operate more sustainably.

[0003] Liquid lithium, with its fusibility and good plasma compatibility, is considered the preferred material for designing liquid metal PFCs. Liquid metals have higher conductivity than ordinary fluids, and the strong magnetic field present in controlled nuclear fusion devices means their flow characteristics are affected by magnetohydrodynamic effects. Furthermore, due to the opacity, easy oxidation, and high conductivity of liquid metals, existing optical-based measurement techniques, such as particle image velocimetry (PIV) and fluorescence imaging, are unusable. Moreover, liquid lithium has a melting point of 180°C, while experimental environments typically operate at around 350°C, making measurement techniques like laser profilometry (LPP), which have a maximum ambient temperature of 50°C, unsuitable. Additionally, the strong magnetic field severely interferes with eddy current sensors' inductance measurements, rendering this measurement technique unsuitable.

[0004] In summary, measuring the liquid level of liquid lithium under strong magnetic fields and high temperatures presents significant challenges. Summary of the Invention

[0005] This invention provides a liquid lithium flow level measurement device and method, which solves the problem of great difficulty in measuring the flow level of liquid lithium under strong magnetic field and high temperature environment.

[0006] This invention provides a liquid lithium flow level measuring device, comprising:

[0007] A probe used to collect voltage signals from liquid lithium;

[0008] A displacement stage, wherein the probe is mounted on the displacement stage and moves accordingly;

[0009] A digital multimeter, wherein the probe is connected to the positive terminal of the digital multimeter via a wire, and the negative terminal of the digital multimeter is connected to liquid lithium metal via another wire, and the digital multimeter is used to measure the voltage signal value collected by the probe;

[0010] The processing unit is used to process the voltage signal of liquid lithium to obtain the maximum and minimum liquid lithium level and the square wave signal.

[0011] The processing unit is also used to obtain the waveform of the target measuring point based on the square wave signal and the maximum and minimum values ​​of the liquid lithium level, and to obtain the liquid level information of the target measuring point changing over time through the waveform.

[0012] A method for measuring the liquid level of a liquid lithium flow device includes the following steps:

[0013] The probe is moved by a displacement stage to determine the zero point of the liquid level at the target measurement point of liquid lithium and the initial position of the probe.

[0014] Set the movement step size, move the probe downwards step by step, measure the first voltage signal in each step with a digital multimeter, and obtain the maximum liquid lithium level based on multiple first voltage signals;

[0015] Continue to move the probe downwards step by step, and measure the second voltage signal at each step using a digital multimeter. The minimum liquid lithium level is obtained based on multiple second voltage signals.

[0016] The first and second voltage signals at each step are processed to obtain the corresponding square wave signals;

[0017] The waveform of the target measuring point is obtained based on multiple square wave signals and the maximum and minimum values ​​of the liquid lithium level. The liquid level information of the target measuring point changing over time is obtained from the waveform.

[0018] Preferably, the probe is moved by a displacement stage to determine the zero point of the liquid lithium target measurement point and the initial position of the probe, including the following steps:

[0019] Move the probe to the target measurement point, move it downwards so that the tip of the probe contacts the bottom of the container, record the absolute coordinates of the displacement stage and set them as the zero point of the liquid lithium target measurement point;

[0020] Move the probe upwards until its tip is 1-2 mm away from the highest liquid level, and record this position as the initial position of the probe.

[0021] Preferably, obtaining the maximum liquid lithium level based on multiple first voltage signals includes the following steps:

[0022] Set the first signal acquisition time as the dwell time for each step, and measure the current first voltage signal value using a digital multimeter within the first signal acquisition time;

[0023] When the current value of the first voltage signal is much greater than 0, calculate the current moving distance of the probe;

[0024] The maximum liquid lithium level is obtained by subtracting the current moving distance from the initial position of the probe.

[0025] Preferably, the maximum liquid lithium level is as follows:

[0026] h max1 =h0-n1*Δh

[0027] In the formula, h max1 denoted as the maximum liquid lithium level, h0 as the initial position of the probe, n1 as the total number of steps when the first voltage signal value is much greater than 0, and Δh as the step size.

[0028] Preferably, obtaining the minimum liquid lithium level based on multiple second voltage signals includes the following steps:

[0029] Set the second signal acquisition time as the dwell time for each step, and measure the current value of the second voltage signal using a digital multimeter within the second signal acquisition time;

[0030] If the current value of the second voltage signal does not equal 0, calculate the current moving distance of the probe;

[0031] The minimum liquid lithium level is obtained by subtracting the current moving distance from the initial position of the probe.

[0032] Preferably, the minimum liquid lithium level is as follows:

[0033] h min =h0-n2*Δh

[0034] In the formula, h min Δh represents the minimum liquid lithium level, h0 represents the initial position of the probe, n2 represents the total number of steps to move when the current second voltage signal value does not equal 0, and Δh represents the step size.

[0035] Preferably, the waveform of the target measurement point is obtained based on multiple square wave signals and the maximum and minimum values ​​of the liquid lithium level, including the following steps:

[0036] Obtain the duty cycle and period of the square wave signal at each step;

[0037] Multiply the duty cycle and period of each square wave signal to obtain the time corresponding to the displacement over one period, and obtain a time-displacement scatter plot.

[0038] By performing Fourier fitting on the time-displacement scatter plot, the maximum and minimum liquid lithium levels, the waveform of the target measurement point is obtained.

[0039] Preferably, the following steps are also included:

[0040] By employing a combination of transverse array probes and controlling the movement of the probes with a displacement stage, the measurement steps at the target measurement point are repeated to obtain liquid level and waveform information at different transverse positions.

[0041] Compared with the prior art, the beneficial effects of the present invention are:

[0042] This invention utilizes the conductivity of liquid lithium in contact with a probe for measurement. During the measurement process, a displacement stage is used to gradually move the probe to obtain a voltage signal. Based on the voltage signal, the maximum and minimum liquid lithium levels, as well as a square wave signal, are obtained. The duty cycle and period of a given square wave signal are used to calculate the corresponding liquid level over the entire fluctuation period. A time-level scatter plot is plotted and fitted to obtain the change in liquid level at the measurement point over time and its waveform. This invention is mainly used for measuring the liquid level of flowing liquids in strong magnetic fields and high-temperature environments. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a structural diagram of a liquid lithium flow level measuring device according to the present invention;

[0045] Figure 2 This is a schematic diagram of the square wave signal acquired by the present invention;

[0046] Figure 3 This is a waveform diagram of the target measurement point of the present invention;

[0047] Figure 4 This is a schematic diagram of a multi-point lateral measurement probe array according to an embodiment of the present invention.

[0048] In the diagram: 1-Probe, 2-Displacement stage, 3-Digital multimeter, 4-Liquid flow channel, 5-Wire. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Reference Figure 1This invention provides a liquid lithium flow level measuring device, including a probe 1, a displacement stage 2, a digital multimeter 3, a liquid flow channel 4, wires 5, and a processing unit. Liquid lithium metal is placed inside the liquid flow channel 4. The probe 1 is mounted on the displacement stage 2, and the displacement stage 2 moves the probe 1 to collect the voltage signal of the liquid lithium. The probe 1 is connected to the positive terminal of the digital multimeter 3 via one wire 5, and the negative terminal of the digital multimeter 3 is connected to the liquid lithium metal via another wire 5. The digital multimeter 3 is used to measure the voltage signal value collected by the probe 1.

[0051] The processing unit processes the voltage signal of liquid lithium to obtain the maximum and minimum liquid lithium level. It also uses the square wave signal and the maximum and minimum liquid lithium level values ​​to obtain the waveform of the target measurement point, thus acquiring the liquid level information of the target measurement point over time.

[0052] In this embodiment, probe 1 is a 0.4 mm diameter copper wire with an insulating layer. The copper wire passes through and is fixed in a 1 mm diameter hollow copper tube, extending 5 mm to 7 mm beyond the tube. The exterior of the copper tube and the portion of the copper wire extending beyond the tube are insulated with an insulating coating, with only the tip of the copper wire conducting electricity to ensure the accuracy of the measurement results. Probe 1 can be fixed to the displacement stage 2 using a clamp.

[0053] The displacement stage 2 is a high-precision displacement stage with a movement accuracy of 0.01mm, and can move along the X, Y, and Z directions.

[0054] To overcome the difficulty of measuring the flowing liquid level of liquid metals such as liquid lithium, this invention proposes a method for measuring the flowing liquid level based on the electrical conductivity of liquids, capable of operating under strong magnetic fields and high temperatures. A method for measuring the flowing liquid level of liquid lithium includes the following steps:

[0055] Step 1: Move probe 1 by moving it through displacement stage 2 to determine the zero point of the liquid lithium target measurement point and the initial position of probe 1.

[0056] First, use the displacement stage 2 to move probe 1 to the target measuring point, then move it downwards until the tip of probe 1 contacts the bottom of the container. Set the absolute coordinates of the displacement stage 2 at this point as the zero point of the liquid level. Then, estimate the liquid level and move probe 1 upwards until the tip of probe 1 is about 1-2 mm away from the highest liquid level. Record this position as the initial position information of probe 1.

[0057] Step 2: Set the movement step size, move probe 1 downwards step by step, collect the first voltage signal in each step, and obtain the maximum value of the liquid lithium level based on multiple first voltage signals.

[0058] Probe 1 is moved downwards gradually, with the step size Δh determined by the target measurement accuracy and the accuracy of the displacement stage 2. Before probe 1 contacts the liquid surface, the first voltage signal acquired is approximately 0V, containing no valid information. Therefore, the time the probe remains at this position can be shortened to 10s, which is the first signal acquisition time. When a conduction signal (a voltage value much greater than 0V) begins to appear in the first signal, it is considered that probe 1 has begun to contact the peak. The maximum liquid level can be obtained by subtracting the moving distance at this point from the initial position of probe 1.

[0059] The maximum liquid lithium level is shown below:

[0060] h max1 =h0-n1*Δh

[0061] In the formula, h max1 denoted as the maximum liquid lithium level, h0 as the initial position of the probe, n1 as the total number of steps when the first voltage signal value is much greater than 0, and Δh as the step size.

[0062] Step 3: Continue to move probe 1 downwards step by step, collect the second voltage signal in each step, and obtain the minimum liquid lithium level based on multiple second voltage signals.

[0063] The automatic signal acquisition time is extended to 30 seconds, which is the second signal acquisition time. When there is no voltage signal approximately equal to 0V in the acquired second voltage signal, it is considered to be fully conductive, and probe 1 has contacted the trough of the surface wave. The minimum liquid level can be obtained by subtracting the current moving distance from the initial position of probe 1.

[0064] The minimum liquid lithium level is shown below:

[0065] h min =h0-n2*Δh

[0066] In the formula, h min Δh represents the minimum liquid lithium level, h0 represents the initial position of the probe, n2 represents the total number of steps to move when the current second voltage signal value does not equal 0, and Δh represents the step size.

[0067] Then, the displacement stage 2 automatically changes its direction of motion and begins to move upwards gradually. When no voltage signal greater than 0V is found in the collected voltage signal, it indicates that probe 1 has left the peak and completely disconnected from the liquid, and the measurement stops. At this point, a maximum liquid level h can also be obtained. max2 Because the influence of the liquid on probe 1 is smaller and the error is smaller before the first contact, the maximum liquid level h obtained on the first contact is used. max1 The measurement result of the maximum liquid level, i.e., h max =h max1 .

[0068] Step 4: Process the first and second voltage signals from each step to obtain the corresponding square wave signals.

[0069] Reference Figure 2 When probe 1 and the surface wave generated by the liquid flow are in different relative positions, square wave signals with different duty cycles can be obtained.

[0070] Step 5: Based on the square wave signal and the maximum and minimum values ​​of the liquid lithium level, obtain the waveform of the target measuring point and the liquid level information of the target measuring point changing over time.

[0071] Reference Figure 3 The acquired square wave signals are processed, and the duty cycle D of the square wave signals at each step is calculated. i And the period T, combined with the displacement h recorded by the displacement stage. i Calculate displacement h i The corresponding time t in a period i =T*D i This allows us to obtain the liquid level information at the measuring point as a function of time. Plotting (t...) i ,h i The time-displacement relationship curve, i.e., the waveform of the measuring point, is obtained by scatter plotting and Fourier fitting.

[0072] Example

[0073] (1) Horizontal liquid level measurement

[0074] Reference Figure 4 By using a combination of array probes along the lateral direction, and controlling the movement of the probes by a displacement stage, the above-mentioned target measurement steps can be repeated to obtain liquid level and waveform information at different lateral positions.

[0075] (2) Flow direction liquid level measurement

[0076] After the previous measurement point is completed, the probe is moved along the flow direction using a displacement stage. The steps of single-point measurement or multi-point transverse measurement are repeated to obtain the liquid level and waveform information at different flow direction positions.

[0077] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0078] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for measuring the liquid level of a liquid lithium flow device, characterized in that, The measuring device includes: Probe (1) is used to collect the voltage signal of liquid lithium; The displacement stage (2) is used to move the probe (1). The digital multimeter (3) has a probe (1) connected to the positive terminal of the digital multimeter (3) via a wire (5) and a negative terminal of the digital multimeter (3) connected to liquid lithium metal via another wire (5). The digital multimeter (3) is used to measure the voltage signal value collected by the probe (1). The processing unit is used to process the voltage signal of liquid lithium to obtain the maximum and minimum liquid lithium level and the square wave signal. The processing unit is also used to obtain the waveform of the target measuring point based on the square wave signal and the maximum and minimum values ​​of the liquid lithium level, and to obtain the liquid level information of the target measuring point changing over time through the waveform. The measurement method includes the following steps: The probe (1) is moved by the displacement stage (2) to determine the zero point of the liquid lithium target measurement point and the initial position of the probe (1); Set the moving step size, move the probe (1) downward step by step, measure the first voltage signal in each step with a digital multimeter (3), and obtain the maximum liquid level of liquid lithium based on multiple first voltage signals; Continue to move the probe (1) downwards step by step, and measure the second voltage signal in each step using a digital multimeter (3). Based on the multiple second voltage signals, obtain the minimum liquid level of liquid lithium. The first and second voltage signals at each step are processed to obtain the corresponding square wave signals; Based on multiple square wave signals and the maximum and minimum values ​​of the liquid lithium level, the waveform of the target measuring point is obtained, and the liquid level information of the target measuring point changing over time is obtained through the waveform. The probe (1) is moved by the displacement stage (2) to determine the zero point of the liquid lithium target measurement point and the initial position of the probe (1), including the following steps: Move the probe (1) to the target measuring point and move it downwards so that the end of the probe (1) contacts the bottom of the container. Record the absolute coordinates of the displacement stage and set them as the zero point of the liquid lithium target measuring point. Move the probe (1) upwards so that its end is 1-2 mm away from the highest liquid level, and record this position as the initial position of the probe (1); The maximum liquid lithium level is obtained based on multiple first voltage signals, including the following steps: Set the first signal acquisition time as the dwell time for each step, and measure the current first voltage signal value using a digital multimeter (3) within the first signal acquisition time; When the current value of the first voltage signal is much greater than 0, calculate the current moving distance of probe (1); The maximum liquid lithium level is obtained by subtracting the current moving distance from the initial position of probe (1); The minimum liquid lithium level is obtained based on multiple second voltage signals, including the following steps: Set the second signal acquisition time as the dwell time for each step, and measure the current second voltage signal value using a digital multimeter (3) within the second signal acquisition time; If the current value of the second voltage signal does not equal 0, calculate the current moving distance of probe (1); The minimum liquid lithium level is obtained by subtracting the current moving distance from the initial position of probe (1).

2. The measurement method of the liquid lithium flow level measuring device as described in claim 1, characterized in that, The maximum liquid lithium level is shown below: In the formula, This represents the maximum liquid lithium level. This is the initial position of the probe. This represents the total number of steps taken when the first voltage signal value is significantly greater than 0. This represents the movement step size.

3. The measurement method of the liquid lithium flow level measuring device as described in claim 1, characterized in that, The minimum liquid lithium level is shown below: In the formula, This represents the minimum liquid lithium level. This is the initial position of the probe. This represents the total number of steps taken when the current value of the second voltage signal does not equal 0. This represents the movement step size.

4. The measurement method of the liquid lithium flow level measuring device as described in claim 1, characterized in that, The waveform of the target measurement point is obtained based on multiple square wave signals and the maximum and minimum values ​​of the liquid lithium level, including the following steps: Obtain the duty cycle and period of the square wave signal at each step; Multiply the duty cycle and period of each square wave signal to obtain the time corresponding to the displacement over one period, and obtain a time-displacement scatter plot. By performing Fourier fitting on the time-displacement scatter plot, the maximum and minimum liquid lithium levels, the waveform of the target measurement point is obtained.

5. The measurement method of the liquid lithium flow level measuring device as described in claim 1, characterized in that, It also includes the following steps: By using a combination of transverse array probes, the movement of the probes is controlled by a displacement stage (2), and the measurement steps of the target measurement point are repeated to obtain liquid level and waveform information at different transverse positions.

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