Lead-bismuth liquid metal medium liquid level measuring system and device

Abstract

A lead-bismuth liquid metal medium liquid level measuring system and device relates to the technical field of liquid level measurement, and comprises a measuring part and a core rod, the measuring part is located in a sleeve, and the bottom end of the measuring part is correspondingly located at the bottom of a container; the top end of the measuring part is electrically connected with the core rod, the core rod is positioned on a rod body outside the container and is correspondingly connected with the sleeve through a flange, and the top end of the core rod is electrically connected with a signal input end of the junction box; the system can conveniently and accurately measure the liquid level in the lead-bismuth liquid metal.

Description

Technical Field

[0001] The invention relates to the technical field of liquid level measurement, and in particular to a lead-bismuth liquid metal medium liquid level measurement system and device. Background Art

[0002] In a nuclear power reactor operating system, multiple cooling vessels are generally provided to cool down various important nodes in the reactor system; Lead-bismuth liquid metal is an alloy of lead and bismuth. This alloy has the characteristics of a low melting point and can remain in liquid form at a relatively low temperature. It is used as a cooling medium. The cooling effect of lead-bismuth liquid metal is directly related to its liquid level in the cooling container. Therefore, a corresponding liquid level measuring device is generally provided in the cooling container. Since the lead-bismuth liquid metal in the reactor is high in temperature and highly corrosive, the liquid level measurement method and sensor design of the lead-bismuth liquid metal are very different from those of the traditional water reactor level gauge. In addition, the thermal-hydraulic properties and physical properties of the lead-bismuth alloy in terms of heat transfer and flow are also very different from those of water. At present, most of the lead-bismuth devices at home and abroad adopt an integrated design, which does not allow holes to be opened on the side wall or bottom of the container. Therefore, the liquid level measurement method of the traditional pressurized water reactor is difficult to be directly applied to the lead-bismuth alloy medium.

[0003] Chinese patent (CN113155221B) discloses a liquid metal flowmeter and a lead-bismuth cooling system. The metal flowmeter adopts a double-probe sensor. By extending the double-probe sensor into the inner wall of the pipeline, it can contact the liquid metal to be measured, ensuring the accuracy of the flowmeter measurement. The structural design of the probe sensor hole can prevent the leakage of lead / lead-bismuth melt, and ensure the insulation between the electrode probe and the conductive materials such as the steel cylinder, so that the reliability and safety of the liquid metal flowmeter are guaranteed. In addition, according to the multi-layer tube body design of the liquid metal flowmeter, the temperature between the external space of the flowmeter and the internal liquid metal can be isolated, ensuring that the external space is in the low temperature environment required for superconductivity, improving the sensitivity of the detection during the period, and achieving the effect of high precision and high resolution; However, the system still needs to open a hole in the side wall of the cooling tube. Even if the structure of the probe sensor hole is uniquely designed, there is still a certain risk of leakage. If the medium containing lead and bismuth metals leaks, it will cause serious harm to the environment and workers.

[0004] Therefore, in combination with the characteristics of lead-bismuth liquid metal and engineering measurement requirements, the present invention proposes a measurement system that can conveniently and accurately measure the liquid level in lead-bismuth liquid metal. Summary of the invention

[0005] In order to overcome the deficiencies in the background technology, the present invention discloses a lead-bismuth liquid metal medium level measurement system and device.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions: A lead-bismuth liquid metal medium level measuring device comprises a measuring part and a core rod, wherein the measuring part is located in a sleeve, and the bottom end of the measuring part is correspondingly located at the bottom of a container 7; The top end of the measuring part is electrically connected to the core rod, the core rod is located outside the container 7, and is correspondingly connected to the sleeve through the flange, and the top end of the core rod is electrically connected to the signal input end of the junction box.

[0007] Preferably, the measuring part comprises a frame, an induction coil and an excitation coil; An induction coil and an excitation coil are wound on the frame in sequence from the inside to the outside, and both the induction coil and the excitation coil are electrically connected to the core rod.

[0008] Preferably, the induction coils are arranged in a plurality of groups, each group of induction coils is arranged with an odd number of winding segments, the induction coils in each group are staggered, and the winding directions of adjacent winding segments are opposite.

[0009] Preferably, the excitation coil is configured as a multi-section structure.

[0010] Preferably, a compensation coil is provided at the end of the skeleton, and the compensation coil is located above the initial winding section of the induction coil.

[0011] Preferably, the outer wall surface of the skeleton is provided with a plurality of convex rings, and the multi-segment induction coil and the compensation coil are respectively located between any two adjacent convex rings.

[0012] A lead-bismuth liquid metal medium level measurement system, comprising the lead-bismuth liquid metal medium level measurement device, the level measurement device is based on a magnetic induction method and is used to generate a corresponding induction signal according to the change of the lead-bismuth liquid metal level height; A sleeve, which is sealed through the top of the container and is located inside the container, and is used to isolate the liquid level measuring device from the lead-bismuth liquid metal medium; A junction box, which is used to transmit sensing signals; The signal processing unit is used to analyze the liquid level height of the lead-bismuth liquid metal according to the sensing signal.

[0013] Preferably, a lead-bismuth leakage detector is provided outside the casing, and the lead-bismuth leakage detector is electrically connected to the junction box.

[0014] Preferably, the sleeve is made of 316L stainless steel.

[0015] Preferably, the liquid level measuring device is electrically connected to the junction box via a high-temperature insulating glue sealing structure.

[0016] Due to the adoption of the above-mentioned technical solution, the present invention has the following beneficial effects: The present invention discloses a lead-bismuth liquid metal medium level measurement system and device, which can indirectly obtain the liquid level height of the lead-bismuth liquid metal medium, thereby avoiding the damage of the high temperature and high corrosiveness of the lead-bismuth liquid metal medium to the liquid level measurement device, thereby improving the service life of the liquid level measurement system and device; at the same time, the measurement device can enter the container from the container top cover, thereby improving the convenience of the liquid level measurement system when in use; And by generating and processing the corresponding induction signal by means of magnetic induction, the liquid level height of the lead-bismuth liquid metal medium can be accurately obtained; In addition, the liquid level measuring device adopts a multi-segment induction coil arrangement, which can effectively and continuously measure the liquid level height of the lead-bismuth liquid metal medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A structural schematic diagram of the present invention; Figure 2 It is a structural schematic diagram of a liquid level measuring device; Figure 3 Schematic diagram of the distributed structure of the induction coil; Figure 4 It is a Gray code waveform diagram; Figure 5 It is a schematic diagram of a high temperature insulating adhesive sealing structure; Figure 6 It is a schematic diagram of the voltage variation of the induction coil under different liquid levels; Figure 7 It is a schematic diagram of the comparison between the reference liquid level and the measured liquid level at 200°C; Figure 8 It is a schematic diagram of the comparison between the reference liquid level and the measured liquid level at 350°C; Fig. 9 It is a schematic diagram of the comparison between the reference liquid level and the measured liquid level at 550°C; Fig.10 It is a schematic diagram for analyzing the influence of excitation frequency on the sensitivity of liquid level measurement device; Fig.11 This is a schematic diagram for analyzing the effect of casing wall thickness on the sensitivity of the liquid level measurement device; Fig.12 Schematic diagram for analyzing the effect of medium temperature on the sensitivity of the liquid level measurement device.

[0018] In the figure: 1. liquid level measuring device; 11. core rod; 12. frame; 13. induction coil; 14. excitation coil; 15. convex ring; 2. sleeve; 3. junction box; 4. signal processing unit; 5. high temperature insulating glue sealing structure; 51. protective sleeve; 52. protective cover; 53. insulating sleeve; 54. wiring nose; 55. sealant; 6. compensation coil; 7. container. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention. In the description, it should be understood that if there are terms such as "upper", "lower", "front", "back", "left", "right" and the like indicating directions or positional relationships, they are only corresponding to the drawings of the present invention, for the convenience of describing the present invention, and do not indicate or imply that the devices or components referred to must have a specific direction: Embodiment 1 is: Combined with Figure 1 The lead-bismuth liquid metal medium level measurement system comprises a lead-bismuth liquid metal medium level measurement device 1, which generates a corresponding voltage signal according to the change of the lead-bismuth liquid metal level height based on magnetic induction; The liquid level measuring device 1 utilizes the good electrical conductivity and inert magnetic conductivity of the lead-bismuth metal medium to generate electromagnetic eddy current induction in the alternating magnetic field, converts the measured liquid level position change into the change of the coil mutual inductance voltage signal value, and then outputs the change of the voltage signal value; A sleeve 2, which is located inside the container 7 after passing through the top of the container 7 in a sealed manner, and is used to isolate the liquid level measuring device 1 from the lead-bismuth liquid metal medium; That is, the sleeve 2 is located in the container 7, and part of the sleeve 2 is directly immersed in the lead-bismuth liquid metal medium, and the part of the liquid level measuring device 1 responsible for measurement is located in the sleeve 2, and the liquid level measuring device 1 is also connected to the top of the sleeve 2 to keep the position of the liquid level measuring device 1 and the sleeve 2 fixed; In particular, the sleeve 2 is made of 316L stainless steel, that is, austenitic stainless steel, which has very good corrosion resistance and a low carbon content, usually not exceeding 0.03%, which helps to reduce intergranular corrosion problems that may occur during welding. It also has high temperature resistance and is therefore suitable for isolating the lead-bismuth liquid metal and liquid level measuring device 1 in the container 7.

[0020] Junction box 3, used for transmitting sensing signals; The junction box 3 is used to receive the sensing signal and then transmit the sensing signal to the signal processing unit 4 of the host computer, wherein the junction box 3 is connected to the host computer by a cable, and the cable and the junction box 3 are connected by an aviation plug, and the protection level of the housing of the junction box 3 is IP65; As required, the liquid level measuring device 1 is electrically connected to the junction box 3 through a high-temperature insulating glue sealing structure 5, wherein the high-temperature insulating glue sealing structure 5 includes a protective sleeve 51, a protective cover 52, an insulating sleeve 53 and a wiring nose 54, wherein the protective sleeve 51 is provided with a wiring nose 54, and a sealant 55 is filled between the wiring nose 54 and the inner wall of the protective sleeve 51, and an insulating sleeve 53 is provided on the top of the protective sleeve 51, and a protective cover 52 is fixedly provided at the connection between the insulating sleeve 53 and the protective sleeve 51, and the bottom of the protective sleeve 51 is used to insert the electrical connection line of the liquid level detection device, and the insulating sleeve 53 is used to insert the wire of the junction box 3, and the electrical connection line and the wire are respectively soldered to the two ends of the wiring nose 54; through this structure, the connection point between the electrical connection line of the liquid level detection device and the wire of the junction box 3 can be sealed, and the connection point between the two can be effectively protected, and the high temperature resistance effect at the connection point can also be improved through the sealant 55; A signal processing unit 4, the signal processing unit 4 is used to analyze the liquid level height of the lead-bismuth liquid metal according to the sensing signal; The signal processing unit 4 first determines whether the change in the voltage signal is positive or negative based on the received continuously changing voltage signal, and then calculates the corresponding liquid level height value using formulas.

[0021] In addition, a lead-bismuth leakage detector is provided outside the bushing 2, and the lead-bismuth leakage detector is electrically connected to the junction box 3. When the metallic lead-bismuth liquid leaks into the bushing 2, the detector will send a switching signal, indicating that the lead-bismuth liquid metal medium is in contact with the detection part of the liquid level measuring device 1, thereby judging that lead-bismuth leakage occurs.

[0022] Embodiment 2 is: Based on Example 1, Figure 2 , the liquid level measuring device 1 is further defined, wherein a lead-bismuth liquid metal medium liquid level measuring device 1 comprises a measuring part and a core rod 11, wherein the measuring part is located in the sleeve 2, and the bottom end of the measuring part is correspondingly located at the bottom of the container 7; The top end of the measuring part is electrically connected to the core rod 11, the core rod 11 is located outside the container 7, and is correspondingly connected to the sleeve 2 through the flange, and the top end of the core rod 11 is electrically connected to the signal input end of the junction box 3; The measuring part is used to sense the liquid level change of the lead-bismuth liquid metal and generate a corresponding electrical signal, which is output to the junction box 3 through the core rod 11.

[0023] Embodiment 3 is: On the basis of Embodiment 2, the measuring part is further defined, that is, the measuring part includes a skeleton 12, an induction coil 13 and an excitation coil 14; The induction coil 13 and the excitation coil 14 are wound around the skeleton 12 in sequence from the inside to the outside. The induction coil 13 and the excitation coil 14 are both electrically connected to the core rod 11 .

[0024] Among them, the induced voltage of the induction coil 13 is: ; (1) In the formula, is the magnetic flux, For The induced electromotive force in the coil is for Number of coil turns, for The magnetic induction intensity of the coil, for exist The cross-sectional area in, t is the time; By passing a constant alternating current through the excitation coil 14, an excitation signal is generated. As the coil is submerged in the lead-bismuth medium, an induced eddy current is generated in the lead-bismuth, and the direction of its magnetic field Be is opposite to the direction of the magnetic field B1 of the excitation coil 14, thereby weakening the synthetic magnetic field B, causing the induced voltage U2 in the induction coil 13 to decrease as the lead-bismuth liquid level increases, thereby measuring the height of the lead-bismuth liquid level; The induced voltage signal is proportional to the number of coil turns. The ratio of the induced voltage to the total induced voltage when the entire coil is immersed is measured. At the same time, the length of the coil is known, and the height information of the submerged coil can be obtained from the proportional relationship, that is, the liquid level at a certain coil x Position; ; (2) in, , and are the induced electromotive force, the number of coil turns and the metal liquid level when the liquid level is at the position x of the induction coil, respectively. , and are the induced electromotive force, coil turns and metal liquid level at full liquid level respectively; The induced voltage can be measured by an electronic unit, so the induced voltage of the coil is measured, and the length of the coil winding is known, the liquid level l can be measured.

[0025] Embodiment 4 is: On the basis of Example 3, the Gray coding principle of digital electronic technology is absorbed in the structural design of the measuring part, and the measuring part is further limited. The induction coils 13 are set to multiple groups, each group of induction coils is set to an odd number of winding segments, and the induction coils 13 of each group are staggered, and the winding directions of adjacent winding segments are opposite; The number of coils in each group of induction coils is an odd number, namely 2n-1 (n=1, 2..), and each group of induction coils 13 is composed of unit coils with the same number of turns. Each group of induction coils 13 is arranged to be wound on the 2n-1th, 2*(2n-1), 22*(2n-1), 23*(2n-1), ... coil positions of the frame 12, and a compensation coil 6 is wound separately on the end of the frame 12. In addition, the excitation coil 14 is configured as a multi-segment structure; An AC current with a constant amplitude and frequency is passed through the excitation coil 14 to generate an AC excitation signal. Each group of induction coils is an odd number of 2n-1 (n=1,2..), and each group of coils is wound in an alternating manner by forward and reverse winding. In the case of a lead-bismuth-free medium, the even number of coils are complementary and cancel each other out. The signal on each group of coils is only the signal of a single coil. When the lead-bismuth medium gradually rises, the first coil of the first group is immersed, and the electrical signal on the first group of induction coils decreases. The change in the initial electrical signal and the electrical signal during the immersion process increases, and it is determined to be code 0 at this time. When it increases to a certain value, it is greater than the determination threshold, and the code value changes from 0 to 1. When the even number of coils in each group are immersed, the current direction is opposite due to the forward and reverse winding of the coils, and the signal change of the previous coil caused by the medium is gradually canceled out. When the canceled signal makes the electrical signal lower than the determination threshold, the code value changes from 1 back to 0. In the process of each group of coils being submerged from bottom to top, the waveform of each group of coils rises and falls alternately. The voltage signals of each group of induction coils 13 and compensation coils 6 are collected in parallel. When an odd number of coils are submerged in the medium, the change in the induction signal caused by the medium is the largest, which is taken as 1. When an even number of coils are submerged in the medium, the change in the induction signal offset is the smallest, which is taken as 0. Then, the signals of multiple groups of induction coils 13 can form a corresponding number of signal codes. The signal code gradually changes from all 0, and after each section, only one group of signal codes changes. Its change law conforms to the Gray Code change law. Therefore, the section where the liquid level is located can be determined by determining the change in the value of each group of signals; and the position of a certain section can be obtained by the proportional relationship between the change voltage of the current section and the total length of the coil. The excitation signal is generated by the excitation coil 14, and the induction signal of the induction coil 13 and the induction signal value of the compensation coil 6 are collected. From this, the liquid level calculation formula can be deduced. The liquid level of the lead-bismuth liquid level meter The calculation equation is written in the following form: The segment where the coil signal change increases ; (3) The segment where the coil signal change decreases ; (4) Where m is the segment number where the current liquid level is located, which can be obtained by decoding the Gray code of the signal combination of each group, and L is the length of each section of the coil. is the relative change in induced voltage of a group of coils currently submerged, , when m=0, Take the empirical value, when m≠0, is the maximum change in the induced voltage of the coil except the coil that has been completely submerged, and To compensate the real-time voltage value of coil 6, It is the real-time voltage value of the induction coil 13 currently selected to participate in the calculation.

[0026] When the liquid level in a certain section m is determined, the odd and even number of coils in a certain group of coils that are flooded in this section can also be determined. When the liquid level floods the odd coils in a certain group of coils, the signal change of this group of coils is in an upward state, and the liquid level formula is (3). When the liquid level floods the even coils in a certain group of coils, the signal is offset and gradually decreases, and the liquid level formula is (4). The mutual inductance of two coils in free space is only related to the relative orientation, that is, the magnitude of the mutual inductance coefficient depends on the geometric shape, size, relative position, number of turns of the two coils, and the magnetic permeability and electrical conductivity of the surrounding medium. From the measurement model, we know that the geometric shape, size, relative position and number of turns of the coil are known after winding. The variables that affect the mutual inductance are magnetic permeability and electrical conductivity. Therefore, non-magnetic materials are selected in the design to reduce the influence of magnetic materials on the mutual inductance. In addition, since the working temperature of 200°C-550°C has a great influence on the material of the liquid level measuring device 1 and the conductivity of the lead-bismuth medium, the induced voltage will drift due to the temperature and affect the liquid level measurement. Therefore, as needed, a compensation coil 6 is provided at the end of the skeleton 12, and the compensation coil 6 is located above the initial winding segment; That is, since each group of induction coils 13 has an odd number, there is an even number of coils before the last coil, which are wound forwards and reversely and are in the same environmental field. The affected signals are of the same magnitude and opposite directions and cancel each other out. The last coil is affected by temperature and produces signal drift.

[0027] Therefore, a compensation coil 6 is designed at the top of the liquid level measuring device 1. When there is no lead-bismuth liquid, the signal of each group of induction coils 13 in the same temperature field at the same time is equal to the signal of the compensation coil 6; when the lead-bismuth liquid level enters the first coil of a group of coils, the difference signal between the induction signal of the compensation coil 6 and the group of coils gradually increases, and the increased signal amount comes from the change of the mutual inductance voltage between the medium and the induction coil 13. When the lead-bismuth liquid level submerges the second reverse coil of this group of coils, the signal gradually decreases, and the mutual inductance voltage caused by the medium decreases until it is 0, and so on.

[0028] The consistency between the compensation coil 6 and the induction coil 13 is used in the structural design, and the difference between the signals of the compensation coil 6 and the induction coil 13 is used in the software design to calculate the liquid level, which can offset the drift caused by temperature without changing the Gray code law of the signal change; To calculate the height information of the lead-bismuth liquid medium, we need to obtain and value, The value is measured in real time by the electronic unit. It is the voltage change when a coil is completely immersed in the lead-bismuth medium. The coil needs to be immersed in the medium for calibration to be obtained. Therefore, the calibration problem needs to be solved in order to measure the liquid level.

[0029] If the coil measuring range is long, immersing the entire coil in the lead-bismuth medium will bring difficulties to the calibration work. The present invention designs the liquid level measuring device 1 as a multi-group multi-section coil structure of equal length. In the same environment, the signal change amount is consistent, and only a small section is required to be calibrated. Therefore, the multi-section structure shortens the calibration range.

[0030] A specific example of the measuring unit is: Figure 3 As shown, the multiple groups of induction coils 13 wound by the skeleton 12 are divided into 5 groups, namely, A induction coil, B induction coil, C induction coil and D induction coil and compensation coil 6, a total of 11 coils, each group of coils is composed of a plurality of identical coils of equal length, wherein the excitation coil 14 is wound on the outer layer of the induction coil 13, and for intuitive display, the excitation coil 14 is not marked in the figure; The number of coils in each group of induction coils 13 is an odd number, namely 2n-1 (n=1,2...), ABCD and the compensation coil 6 are marked with different colors in the figure, and each group of induction coils 13 is composed of unit coils with the same number of turns. For example, there are 5 coils in group A in the figure, which are yellow, there are 3 coils in group B in the figure, which are blue, there are 1 coil each in CD, which are red and green respectively, and there is one compensation coil 6, which is purple; the 5 coils of group A are arranged in a forward winding and a reverse winding alternately, and the winding methods of other induction coils 13 are wound in the same way; the arrangement of A, B, C, D induction coils are wound at the 2n-1, 2*(2n-1), 22*(2n-1), 23*(2n-1)th coil positions of the skeleton 12 respectively, and a compensation coil 6 is wound alone at the end position of the skeleton 12; In this example, the electrical signal acquisition process of the lead-bismuth liquid metal level change is as follows: 1) Gray code liquid level calculation, The coil is passed through an alternating current of constant amplitude and frequency to generate an AC excitation signal. Each group of signal coils is an odd number, represented by 2n-1 (n=1, 2...). Since each group of coils is wound in an alternating manner using forward and reverse winding, in the case of a lead-bismuth-free medium, the even number of coils complement each other and cancel each other out. The signal on each group of coils is only the signal of a single coil. When the lead-bismuth medium gradually rises, the first coil of group A is immersed, and the electrical signal on group A coil decreases. The change in the initial electrical signal and the electrical signal during the immersion process increases, and it is judged to be code 0 at this time. When it increases to a certain value, it is greater than the judgment threshold, and the code value changes from 0 to 1. When the even number of coils in each group are immersed, the current direction is opposite due to the forward and reverse winding of the coil, and the signal change caused by the medium of the previous coil is gradually canceled out. When the canceled signal makes the electrical signal lower than the judgment threshold, the code value changes from 1 back to 0. The process of coils in groups ABCD being submerged from bottom to top, the waveform of each coil group rises and falls alternately, and the generation process of Gray code is shown in the attached figure. Figure 4 As shown, the horizontal direction E in the figure is the position where the lead-bismuth medium gradually submerges the measuring part, and the vertical direction is the change in the coil electrical signal; Collect the signals of ABCD and compensation coil 6 in parallel, and do not consider the change of the signal in each section. When an odd number of coils are submerged by the medium, the change of the induction signal caused by the medium is the largest, which is taken as 1. When an even number of coils are submerged by the medium, the change of the induction signal is the smallest, which is taken as 0. The four groups of signals ABCD form a four-bit signal, and its signal code gradually changes from 0000. After each section, only one group of signal codes changes. Its change law conforms to the Gray Code change law. Therefore, the section where the liquid level is located can be determined by judging the change of each group of signal values; and the position of a certain section can be obtained by the proportional relationship between the change voltage of the current section and the total length of the coil. Generate an excitation signal by the excitation coil 14, collect the induction signal of the induction coil 13 and the induction signal value of the compensation coil 6, and the liquid level calculation formula can be derived from this. The liquid level calculation equation of the lead-bismuth liquid level meter is as follows: The segment where the coil signal change increases ; (5) The segment where the coil signal change decreases ; (6) Where m is the segment number of the current liquid level, which can be obtained by decoding the Gray code of the signal combination of each group ABCD. L is the length of each section coil. is the relative change in induced voltage of a group of coils currently submerged: ; (7) When m=0, Take the empirical value; when m≠0, , is the maximum change of the induced voltage of the coil except the coil that has been completely submerged. When the liquid level is determined in a certain section m, the odd and even number of coils in a certain group of coils that are currently submerged can also be determined. When the liquid level submerges an odd number of coils in a certain group of coils, the signal change of this group of coils is in an upward state, and the liquid level formula is (5). When the liquid level submerges an even number of coils in a certain group of coils, the signal is offset and gradually decreases, and the liquid level formula is (6); 2) Temperature compensation, The mutual inductance of two coils in free space is only related to the relative orientation, that is, the size of the mutual inductance coefficient depends on the geometry, size, relative position, number of turns of the two coils, and the magnetic permeability and conductivity of the surrounding medium. From the measurement model, it can be seen that the geometry, size, relative position and number of turns of the coils are known after winding. The variables that affect the mutual inductance coefficient are magnetic permeability and conductivity. The operating temperature of the equipment environment is 200℃-550℃, which has a great influence on the conductivity of the measuring body medium and the lead-bismuth medium. The induced voltage will drift due to the influence of temperature, affecting the liquid level measurement.

[0031] Since each group of coils is an odd number, there is an even number of coils before the last coil. They are wound forward and backward and are in the same environmental field. The affected signals are of the same magnitude and opposite direction and cancel each other out. The last coil is affected by temperature and produces signal drift. Therefore, a compensation coil 6 is designed at the top of the measurement part. When there is no lead-bismuth liquid, the signal of each group of coils in the same temperature field at the same time is equal to the signal of the compensation coil 6. When the lead-bismuth liquid level enters the first coil of a certain group of coils, the difference signal between the compensation coil 6 and the induction signal of the group of coils gradually increases. The increased signal comes from the change of the mutual induction voltage between the medium and the induction coil 13. When the lead-bismuth liquid level submerges the second reverse coil of this group of coils, the signal gradually decreases, and the mutual induction voltage caused by the medium decreases until it is 0, and so on. In terms of structural design, the consistency of the compensation coil 6 and the induction coil 13 is used for design, and in terms of software design, the difference between the signals of the compensation coil 6 and the induction coil 13 is used for liquid level calculation, which can offset the drift caused by temperature and does not change the Gray code law of signal change.

[0032] After adding the compensation coil 6, in formulas (5) and (6), = - , = - . To compensate the real-time voltage value of coil 6, is the real-time voltage value of the induction coil 13 currently selected for calculation, is the voltage value when the single-section induction coil 13 is completely submerged in the lead-bismuth dielectric, thereby eliminating the measurement influence caused by temperature; 3) Self-calibration and liquid level correction, From the liquid level measurement formulas (5) and (6), it can be seen that to calculate the height information of the lead-bismuth liquid medium, it is necessary to obtain and value, The value is measured in real time by the electronic unit. The voltage change when a coil is completely immersed in the lead-bismuth medium can only be obtained by immersing the coil for calibration. Therefore, the calibration problem must be solved to measure the liquid level. If the coil measurement range is long, immersing the entire coil in the lead-bismuth medium will also bring difficulties to the calibration work.

[0033] Moreover, in the present invention, the induction coil 13 is designed as a coil structure of multiple groups and multiple sections of equal length. In the same environment, the signal change amount is consistent, and only one small section is required to be calibrated. Therefore, the multi-section structure shortens the calibration range. For example, the 10-section structure in this embodiment shortens the calibration length of the measurement range by 1 / 10. As long as one small section is obtained, if the measurement range is longer, one or more groups can be added to increase the number of sections, and the length of a single section can be shortened.

[0034] According to the Gray code law of signal change, when the medium is empty, that is, lead-free bismuth, the Gray code is 0000. When the first coil is flooded, at least one code is 1, which means that at least one group of coils ABCD has an odd number of coils that are all flooded. The signal change of the coil with code 1 is measured in real time by the electronic measurement unit. , or the difference between the real-time voltage value of the compensation coil 6 and the real-time voltage value of each group of induction coils 13 The maximum value in , so that the real-time under different temperatures can be obtained ,in refers to the real-time voltage value of the i-th group of induction coils 13, ,Right now , , , , They are the real-time measured voltage values ​​of induction coil A, induction coil B, induction coil C and induction coil D. The maximum voltage signal change obtained in real time avoids the signal temperature drift caused by different temperatures, reduces the signal variable drift caused by the change of the conductivity of the lead-bismuth medium caused by temperature, and achieves real-time calibration, that is, simultaneous measurement and calibration, that is, self-calibration.

[0035] when When the lead-bismuth dielectric does not flood the first coil, Take a fixed value. When the fixed value is used in the calibration test, the test obtains the value of the first section of the flooding. , record it in advance and enter it into the secondary instrument parameters.

[0036] when When m is decoded by Gray code, the specific value of m can be obtained. The calculation equation is modified to the following form: ; (8) or ; (9) In formula (8), , while in formula (9), .

[0037] when , like , take formula (8); otherwise, take formula (9).

[0038] like , take formula (8); otherwise, take formula (9).

[0039] like , take formula (8); otherwise, take formula (9).

[0040] ,like , take formula (8); otherwise, take formula (9).

[0041] like , take formula (8); otherwise, take formula (9).

[0042] ,like , take formula (8); otherwise, take formula (9).

[0043] ,like , take formula (8); otherwise, take formula (9).

[0044] If , take formula (8); otherwise, take formula (9).

[0045] like , take formula (8); otherwise, take formula (9).

[0046] in: is the voltage value measured in real time of each induction coil 13; The number of segments of the induction coil is 13. is the length of each section of the induction coil 13; is the real-time voltage value of the compensation coil 6; is the real-time voltage value of the induction coil 13 currently selected to participate in the calculation; For real-time conditions The maximum value of refers to the real-time voltage value of the i-th group of induction coils 13, ,Right now , , , ; In addition, the outer wall surface of the skeleton 12 is provided with a plurality of convex rings 15, and the multi-segment induction coil 13 and the compensation coil 6 are respectively located between any two adjacent convex rings 15, which can reserve sufficient winding space for the induction coil 13 in advance and facilitate the subsequent coil winding operation.

[0047] In addition, as a specific example of a lead-bismuth liquid metal medium level measurement system in Example 1, a specific example of this embodiment is: Since the material of the sleeve 2 has a great influence on the life of the coil cable, a metal sleeve 2 is selected, and the skeleton 12 needs to be resistant to high temperature and also a metal skeleton 12 is selected, and the cable needs to be a high temperature resistant cable, and both are non-magnetic materials. Therefore, the skeleton 12 is non-magnetic austenitic stainless steel, and the sleeve 2 is 316 lStainless steel.

[0048] The upper part of the sleeve 2 is designed with a welding ring to be welded to the container 7. The level measuring device 1 is connected to the sleeve 2 with a flange interface, sealed with a metal sealing ring and fixed with a nut. The upper end of the mandrel 11 of the level measuring device 1 leads to the junction box 3, which is connected to the cable with an aviation plug. The housing protection level is IP65.

[0049] Under the condition of using temperature of 200~550℃ and designed withstand voltage of about 1Mpa, each coil uses Cr10Ni90 nickel-chromium wire armored cable with high temperature resistance, low resistance temperature coefficient, surface oxidation resistance and high temperature non-magnetization as winding material. The skeleton 12 is used to support and fix the induction coil 13, the excitation coil 14 and the compensation coil 6. The skeleton 12 uses austenitic 06CR19NI10 stainless steel with high temperature resistance, high strength and non-magnetic properties, which has the lowest impact on the electromagnetic induction signal.

[0050] The lead-bismuth leakage detector is used to detect when the metallic lead-bismuth liquid leaks into the casing 2 and sends a switch signal, that is, the lead-bismuth liquid contacts the probe, causing the switch to close, thereby judging that the lead-bismuth leakage occurs. A single-core armored cable is selected, and its core wire is used as a contact probe.

[0051] In order to prevent the coil of the liquid level measuring device 1 from being in contact with the outside air for a long time, resulting in a decrease in insulation, the lead end of the coil of the liquid level measuring device 1 is sealed and welded. Figure 5 In the high temperature insulating adhesive sealing structure 5 shown, the core wire of the armored cable passes through the wiring nose 54 and then is welded, the outer layer is protected by a stainless steel protective cover 52, and the interior is filled with high temperature epoxy adhesive for sealing.

[0052] According to the above two examples, a model is built in ANSYS Maxwell, and the liquid level measuring device 1 and the casing 2 are modeled together. The casing 2 is made of 316L, the core rod 11 and the skeleton 12 are made of non-magnetic austenitic stainless steel 06CR19NI10, and the winding cable is made of high temperature resistant nickel-chromium Cr10Ni90 armored cable.

[0053] Based on this model, the voltage variation of the induction coil 13 at different liquid levels is obtained, as shown in the attached figure. Figure 6 As shown in the figure, the comparison between the reference liquid level and the measured liquid level at different temperatures is shown in the attached figure. Figure 7 As shown. Figure 6 It can be seen that the voltage change of the induction coil 13 is consistent with the Gray code change, and the liquid level algorithm is reasonably designed. Figure 7-9 It can be seen that at different temperatures, the error between the liquid level measurement value and the reference value is within ±11mm, accounting for 1% of the total range, and the error is less than 2%.

[0054] Based on the model, the variable factors affecting the liquid level are analyzed, including the excitation frequency, such as the attached Fig.10 As shown, the thickness of the sleeve 2 is as shown in the attached Fig.11 As shown, temperature, as attached Fig.12 The factors shown are fed back to the structural design of the liquid level measuring device 1 and the corresponding algorithm compensation design, and the liquid level measuring device 1 and the corresponding algorithm are adjusted.

[0055] The parts of the present invention that are not described in detail are prior art. It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the appended claims rather than the above description. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention, and any figure marks in the claims should not be regarded as limiting the claims involved.

Claims

1. A lead-bismuth liquid metal medium level measuring device, characterized in that: It comprises a measuring part and a core rod (11), wherein the measuring part is located in the sleeve (2), and the bottom end of the measuring part is correspondingly located at the bottom of the container (7); The top end of the measuring part is electrically connected to the core rod (11); the core rod (11) is located on a rod body outside the container (7) and is correspondingly connected to the sleeve (2) via a flange; and the top end of the core rod (11) is electrically connected to a signal input end of the junction box (3).

2. The lead-bismuth liquid metal medium level measuring device according to claim 1, characterized in that: The measuring part comprises a frame (12), an induction coil (13) and an excitation coil (14); An induction coil (13) and an excitation coil (14) are wound in sequence from the inside to the outside on the skeleton (12), and both the induction coil (13) and the excitation coil (14) are electrically connected to the core rod (11).

3. The lead-bismuth liquid metal medium level measuring device according to claim 2, characterized in that: The induction coils (13) are arranged in a plurality of groups, each group of induction coils is arranged with an odd number of winding segments, the induction coils (13) in each group are arranged in a staggered manner, and the winding directions of adjacent winding segments are opposite.

4. The lead-bismuth liquid metal medium level measuring device according to claim 2, characterized in that: The excitation coil (14) is configured as a multi-segment structure.

5. The lead-bismuth liquid metal medium level measuring device according to claim 3, characterized in that: A compensation coil (6) is provided at the end of the frame (12), and the compensation coil (6) is located above the initial winding section of the induction coil (13).

6. The lead-bismuth liquid metal medium level measuring device according to claim 5, characterized in that: The outer wall surface of the skeleton (12) is provided with a plurality of convex rings (15), and the multi-segment induction coil (13) and the compensation coil (6) are respectively located between any two adjacent convex rings (15).

7. A lead-bismuth liquid metal medium level measurement system, characterized by: The liquid level measuring device (1) comprises the lead-bismuth liquid metal medium as claimed in any one of claims 1 to 6, wherein the liquid level measuring device (1) is based on magnetic induction and is used to generate a corresponding induction signal according to the change of the lead-bismuth liquid metal level height; A sleeve (2), the sleeve (2) is located inside the container (7) after passing through the top of the container (7) in a sealed manner, and is used to isolate the liquid level measuring device (1) from the lead-bismuth liquid metal medium; A junction box (3), the junction box (3) is used to transmit the sensing signal; A signal processing unit (4) is used to analyze the liquid level height of the lead-bismuth liquid metal according to the sensing signal.

8. The lead-bismuth liquid metal medium level measurement system according to claim 7, characterized in that: A lead-bismuth leakage detector is provided outside the sleeve (2), and the lead-bismuth leakage detector is electrically connected to the junction box (3).

9. The lead-bismuth liquid metal medium level measurement system according to claim 7, characterized in that: The sleeve (2) is made of 316L stainless steel.

10. The lead-bismuth liquid metal medium level measurement system according to claim 7, characterized in that: The liquid level measuring device (1) is electrically connected to the junction box (3) via a high-temperature insulating glue sealing structure (5).

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