Method and device for measuring content of dissolved iron in liquid lead bismuth

Abstract

The invention is suitable for the field of nuclear power detection, and discloses a method and device for measuring the content of dissolved iron in liquid lead bismuth, and the method comprises the following steps: S1, taking out the liquid lead bismuth, adding the liquid lead bismuth into a test container, and heating the liquid lead bismuth to a set temperature by a heating assembly; s2, argon is injected into the test container to exclude other gases, then oxygen is input, and the change of the concentration of dissolved oxygen in the liquid lead bismuth is measured through an oxygen detection sensor; s3, substituting the measured oxygen concentration change rate and the net oxygen adding rate into a differential equation, and calculating to obtain a solubility product; and S4, deducing the content of the dissolved iron according to the measured equilibrium oxygen concentration in the saturated iron and the solubility product obtained in the step S3. The method for measuring the oxygen activity of the dissolved lead-bismuth eutectic through the oxygen detection sensor is easy and convenient to operate, the content of dissolved iron can be rapidly and accurately measured, the liquid metal system is always in a balanced state by adjusting the oxygen adding rate in the system, and the experiment efficiency is higher.

Description

Technical Field

[0001] The invention relates to the field of nuclear power detection, and in particular to a method and a device for measuring the content of dissolved iron in liquid lead and bismuth. Background Art

[0002] Lead bismuth eutectic (LBE) was selected as the coolant for the fourth-generation nuclear reactor lead-cooled fast reactor. The main alloying elements of the primary circuit structural material undergo dissolution and corrosion under the action of lead and bismuth. The dissolved metal impurities react in LBE to form intermetallic compounds or oxides, which contaminate the coolant and reduce its thermal performance, and may even cause operational failures of pumps and valves, posing a threat to the safety of the entire nuclear energy system. In order to study the content, morphology and transport properties of metal impurities in LBE, it is necessary to develop monitoring methods. Existing measurement methods are mainly based on chemical analysis or spectral analysis, which are complex to operate and have high requirements for samples. Most existing testing methods are slow and inefficient. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method and device for measuring the dissolved iron content in liquid lead and bismuth, aiming to solve the problems of slow liquid detection and low efficiency in the prior art.

[0004] The present invention solves the technical problem by using a method for measuring the content of dissolved iron in liquid lead and bismuth, comprising the following steps:

[0005] Step S1, taking out liquid lead bismuth, adding it into a test container, and heating the component to raise the temperature to a set temperature;

[0006] Step S2, first injecting argon into the test container to exclude other gases, and then injecting oxygen, and measuring the change of dissolved oxygen concentration in liquid lead and bismuth through an oxygen detection sensor;

[0007] Step S3, iron interacts with dissolved oxygen to generate Fe 3 O 4 , the chemical reaction balance can be expressed in terms of the activities of dissolved iron and oxygen. The measured rate of change of oxygen concentration and the net oxygen addition rate are substituted into the differential equation to calculate the solubility product;

[0008] Step S4, calculating the dissolved iron content by the measured equilibrium oxygen concentration in the saturated iron and the solubility product obtained in step S3.

[0009] In one embodiment, the solubility product K sp Calculated using the following formula:

[0010] Solubility product K sp Expressed as:

[0011] Among them, C Fe(LBE) is the Fe content in liquid lead bismuth, C O(LBE) is the content of O in liquid lead bismuth.

[0012] In one embodiment, the dissolved iron content in step S4 can be calculated by the following formula:

[0013]

[0014] In one embodiment, the oxygen detection sensor is located away from the heating assembly.

[0015] The present invention solves the technical problem by using a device for measuring the content of dissolved iron in liquid lead and bismuth, comprising: an air supply module, a test container, a detection module and a heating component; the air supply module is connected to the test container through an air pipe, the test container is used to hold liquid lead and bismuth, the detection module comprises an oxygen detection sensor, the oxygen detection sensor is inserted into the liquid lead and bismuth, and the heating component is arranged on the outer wall of the test container and heats the test container.

[0016] In one embodiment, the gas supply module includes an argon unit, an oxygen unit and an argon-hydrogen mixing unit; the argon unit includes an argon gas source, a first gas valve and a first flow meter, and the argon gas source, the first gas valve and the first flow meter are connected in sequence through a gas pipe; the oxygen unit includes an oxygen gas source, a second gas valve and a second flow meter, and the oxygen gas source, the second gas valve and the second flow meter are connected in sequence through a gas pipe; the argon-hydrogen mixing unit includes an argon-hydrogen mixed gas source, a third gas valve and a third flow meter, and the argon-hydrogen mixed gas source, the second gas valve and the second flow meter are connected in sequence through a gas pipe.

[0017] In one embodiment, the detection module is further provided with a first temperature sensor and a second temperature sensor, wherein the first temperature sensor is arranged at the oxygen detection sensor, and the second temperature sensor is arranged in liquid lead bismuth away from the oxygen detection sensor.

[0018] In one embodiment, a retractable iron rod is further provided on the upper portion of the test container, and the retractable iron rod extends toward the liquid lead bismuth.

[0019] The implementation of the present invention has the following beneficial effects: the method of measuring the oxygen activity of dissolved lead-bismuth eutectic (LBE) by an oxygen detection sensor is simple to operate, and can quickly and accurately estimate the dissolved iron content under saturation conditions. By adjusting the oxygen addition rate in the system, the liquid metal system is always in a state of equilibrium, and the experimental efficiency is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work. In the drawings:

[0021] Figure 1 It is a flowchart of a method for measuring the content of dissolved iron in liquid lead and bismuth in one embodiment of the present invention;

[0022] Figure 2 This is an overall structural diagram of a device for measuring the content of dissolved iron in liquid lead and bismuth in one embodiment of the present invention;

[0023] Figure 3 It is the solubility product of Fe-LBE-O of a device for measuring the content of dissolved iron in liquid lead and bismuth in one embodiment of the present invention.

[0024] Figure Annotation

[0025] 1. Argon gas source; 2. Oxygen gas source; 3. Argon-hydrogen mixed gas source; 4. First gas valve; 5. Second gas valve; 6. Third gas valve; 7. First flow meter; 8. Second flow meter; 9. Third flow meter; 10. Inlet pipe; 11. Second temperature sensor; 12. Oxygen detection sensor; 13. First temperature sensor; 14. Retractable iron rod; 15. Exhaust pipe; 16. Flange cover; 17. Test container; 18. Heating component; 19. Liquid lead bismuth. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0027] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0028] Figure 1 to Figure 2 A method for measuring the dissolved iron content in liquid lead bismuth in an embodiment of the present invention is shown. The method for measuring the dissolved iron content in liquid lead bismuth 19 can be used to measure the oxygen activity of dissolved liquid lead bismuth (19). Based on the thermodynamic assumption, the dissolved iron content under saturation can be quickly and accurately estimated, which may include the following steps:

[0029] Step S1, taking out liquid lead bismuth 19, adding it into the test container 17, and the heating component 18 raises the temperature to a set temperature;

[0030] Step S2, first inject argon gas into the test container 17 to exclude other gases, then input oxygen, and measure the change of dissolved oxygen concentration in the liquid lead bismuth 19 through the oxygen detection sensor 12;

[0031] Step S3, iron interacts with dissolved oxygen to generate Fe 3 O 4 , the chemical reaction balance can be expressed in terms of the activities of dissolved iron and oxygen. The measured rate of change of oxygen concentration and the net oxygen addition rate are substituted into the differential equation to calculate the solubility product;

[0032] Step S4, calculating the dissolved iron content by the measured equilibrium oxygen concentration in the saturated iron and the solubility product obtained in step S3.

[0033] The method of measuring the oxygen activity of dissolved lead-bismuth eutectic (LBE) by oxygen detection sensor is simple to operate and can quickly and accurately estimate the dissolved iron content under saturation conditions. By adjusting the oxygen addition rate in the system, the liquid metal system is always in equilibrium, making the experiment more efficient.

[0034] It can be understood that liquid lead bismuth 19 contains iron elements. When argon gas is used to exclude air, the iron-oxygen ratio in the liquid lead bismuth 19 will no longer change. When oxygen is introduced and oxygen is integrated into the liquid lead bismuth 19, the iron and oxygen will combine to produce magnetite.

[0035] It can be understood that saturated iron refers to the saturated solubility of iron, the concentration of iron to be precipitated, and the saturation range is 10 at 400°C. -11 wt% to 10 -7 wt%.

[0036] In one embodiment, oxygen can be replaced by normal air, reducing testing costs.

[0037] In one embodiment, the formation of magnetite (Fe) may be performed based on the interaction of iron with dissolved oxygen in liquid lead bismuth (LBE). 3 O 4 ), iron interacts with dissolved oxygen in LBE to form magnetite (Fe 3 O 4 ), the reaction is as follows:

[0038] Fe 3 O 4(s) f3Fe (LBE) +4[O] (LBE)

[0039] It can be expressed by the activities of iron and oxygen dissolved in liquid lead bismuth (LBE):

[0040]

[0041] Where K is the equilibrium constant of the magnetite formation reaction, α Fe(LBE) is the activity of dissolved iron in liquid lead-bismuth-19, α O(LBE) is the dissolved oxygen activity in liquid lead-bismuth-19;

[0042] The activity of iron in LBE is generally defined as the ratio of iron concentration to solubility:

[0043]

[0044] The activity of oxygen is expressed in terms of the Sievert constant k o Means: a O(LBE) =k O ·C O(LBE) .

[0045] The solubility product is most often expressed as the concentration of the solute (usually expressed in units of wt% of liquid lead and bismuth). This conversion means that the standard state of dissolved metal and oxygen atoms is changed from the pure phase standard state to the Henry's law standard state. Therefore, the solubility product K sp It can be expressed as:

[0046] refer to Figure 3 In one embodiment, the rate of change of the iron concentration in step S2 can be expressed by a differential equation derived from the mass balance of oxygen in the system and the solubility product: First, the solubility product K sp Formula (1) is differentiated with respect to time, because K sp Only the temperature changes, so the time derivative is 0:

[0047] Differentiate the consumption of the chemical reaction with respect to time t to obtain the solubility K sp :

[0049]

[0050] Substituting formula (3) into formula (2), we get:

[0051]

[0052] Among them, M o and M Fe are the molar masses of oxygen and iron, respectively, K sp is the solubility product of magnetite, r o (t) is the net oxygen addition rate that varies with time, C o(LBE) Detected oxygen concentration of liquid lead bismuth 19.

[0053] Understandably, the oxygen mass balance refers to the chemical reaction balance, and the oxygen concentration is about 10 -8 wt% to 10 - 4 Between wt%.

[0054] It is understood that the maximum rate of net oxygen addition is 10 -9 wt% / s.

[0055] The dissolved iron content in step S4 can be calculated by the following formula:

[0056]

[0057] Figure 1 to Figure 2 As shown, the oxygen detection sensor 12 may include an oxygen detection sensor ( 12 ) located away from the heating assembly 18 in one embodiment.

[0058] In one embodiment, step S2 may include inputting a mixture of argon and hydrogen again after inputting oxygen, and the hydrogen may combine with the dissolved oxygen in the liquid lead bismuth 19 to become H 2 O molecules will tend to reduce the concentration of dissolved oxygen in liquid lead-bismuth-19.

[0059] Understandably, hydrogen and oxygen will undergo a microscopic redox reaction in a 200-500℃ liquid lead-bismuth environment due to the high temperature, generating H 2 O and heat, thereby consuming the oxygen content in the liquid lead bismuth.

[0060] In one embodiment, the input argon and hydrogen may include a ratio of 19 parts argon to 1 part hydrogen. The low concentration of hydrogen can effectively reduce the reaction rate between hydrogen and oxygen, and the ignition point of the mixed gas can be increased after mixing with argon, thereby avoiding explosion caused by violent reaction between hydrogen and oxygen.

[0061] Figure 2 A device for measuring the dissolved iron content in liquid lead-bismuth in an embodiment of the present invention is shown, comprising a gas supply module, a test container 17, a detection module and a heating assembly 18; the gas supply module is connected to the test container 17 through an air pipe, the test container 17 is used to hold liquid lead-bismuth 19, the detection module comprises an oxygen detection sensor 12, the oxygen detection sensor 12 is inserted into the liquid lead-bismuth 19, the heating assembly 18 is arranged on the outer wall of the test container 17 and heats the test container 17, the gas supply module supplies gas to the test container 17 through the air pipe, and the oxygen detection sensor 12 detects the oxygen change rate in the liquid lead-bismuth 19.

[0062] In one embodiment, a flange cover 16 is further provided on the upper portion of the test container 17 , and the air pipe and the detection module are both passed through the flange cover 16 .

[0063] In one embodiment, the air pipe includes an air inlet pipe 10 and an air outlet pipe, the air supply module is connected to the air inlet pipe 10, and the air outlet pipe is connected from the inside of the test container 17 to the external space.

[0064] In one embodiment, an argon unit may include an argon gas source 1, a first gas valve 4 and a first flowmeter 7, which are connected in sequence through a gas pipe; an oxygen unit may include an oxygen gas source 2, a second gas valve 5 and a second flowmeter 8, which are connected in sequence through a gas pipe; an argon-hydrogen mixing unit may include an argon-hydrogen mixed gas source 3, a third gas valve 6 and a third flowmeter 9, which are connected in sequence through a gas pipe. By using flow meters and gas valves to control gas delivery and ensure that the gas delivery rate is within a control range, the reaction rate is controlled.

[0065] In one embodiment, the detection module may include a first temperature sensor 13 and a second temperature sensor 11. The first temperature sensor 13 is arranged at the oxygen detection sensor 12, and the second temperature sensor 11 is arranged in the liquid lead bismuth 19 away from the oxygen detection sensor 12. The first temperature sensor 13 is used to detect the temperature at the oxygen detection sensor 12, and the second temperature sensor 11 is used to detect the liquid lead bismuth 19.

[0066] In one embodiment, a retractable iron rod 14 may be provided on the upper portion of the test container 17 , and the retractable iron rod 14 extends toward the liquid lead-bismuth 19 . The retractable iron rod 14 is used to extend into the liquid lead-bismuth 19 to increase the iron content in the liquid lead-bismuth 19 .

[0067] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope covered by the claims of the present invention.

Claims

1. A method for measuring the content of dissolved iron in liquid lead and bismuth, characterized in that: The following steps are involved: Step S1, taking out liquid lead bismuth (19), adding it into a test container (17), and heating the heating component (18) to raise the temperature to a set temperature; Step S2, first injecting argon gas into the test container (17) to exclude other gases, then injecting oxygen, and measuring the dissolved oxygen concentration in the liquid lead bismuth (19) through the oxygen detection sensor (12); Step S3, iron interacts with dissolved oxygen to generate Fe3O4, the chemical reaction balance can be expressed by the activities of dissolved iron and oxygen, and the measured oxygen concentration change rate and net oxygen addition rate are substituted into the differential equation to calculate the solubility product; Step S4, calculating the dissolved iron content by the measured equilibrium oxygen concentration in the saturated iron and the solubility product obtained in step S3.

2. The method for measuring the dissolved iron content in liquid lead and bismuth according to claim 1, characterized in that: Solubility product K sp Calculated using the following formula: Solubility product K sp Expressed as: Among them, C Fe(LBE) is the Fe content in liquid lead bismuth, C O(LBE) is the content of O in liquid lead bismuth.

3. The method for measuring the dissolved iron content in liquid lead and bismuth according to claim 2, characterized in that: The dissolved iron content in step S4 can be calculated by the following formula:

4. The method for measuring the dissolved iron content in liquid lead and bismuth according to claim 1, characterized in that: The oxygen detection sensor (12) is located away from the heating component (18).

5. The method for measuring the dissolved iron content in liquid lead and bismuth according to claim 1, characterized in that: The method comprises the following steps: after oxygen is inputted in step S2, a mixture of argon and hydrogen is inputted again.

6. The method for measuring the dissolved iron content in liquid lead and bismuth according to claim 4, characterized in that: The ratio of argon to hydrogen is 19 parts argon and 1 part hydrogen.

7. A device for measuring the content of dissolved iron in liquid lead and bismuth, applicable to any one of claims 1 to 6, characterized in that: include: A gas supply module, a test container (17), a detection module and a heating component (18); The gas supply module is connected to a test container (17) via an air pipe. The test container (17) is used to contain liquid lead bismuth (19). The detection module comprises an oxygen detection sensor (12). The oxygen detection sensor (12) is inserted into the liquid lead bismuth (19). The heating component (18) is arranged on the outer wall of the test container (17) and heats the test container (17).

8. The device for measuring the content of dissolved iron in liquid lead and bismuth according to claim 7, characterized in that: The gas supply module includes an argon unit, an oxygen unit and an argon-hydrogen mixing unit; The argon gas unit comprises an argon gas source (1), a first gas valve (4) and a first flow meter (7), wherein the argon gas source (1), the first gas valve (4) and the first flow meter (7) are connected in sequence via a gas pipe; The oxygen unit comprises an oxygen source (2), a second gas valve (5) and a second flow meter (8), wherein the oxygen source (2), the second gas valve (5) and the second flow meter (8) are connected in sequence through a gas pipe; The argon-hydrogen mixing unit comprises an argon-hydrogen mixed gas source (3), a third gas valve (6) and a third flow meter (9); the argon-hydrogen mixed gas source (3), the second gas valve (5) and the second flow meter (8) are connected in sequence via gas pipes.

9. The device for measuring the content of dissolved iron in liquid lead and bismuth according to claim 7, characterized in that: The detection module is also provided with a first temperature sensor (13) and a second temperature sensor (11), wherein the first temperature sensor (13) is arranged at the oxygen detection sensor (12), and the second temperature sensor (11) is arranged in liquid lead bismuth (19) away from the oxygen detection sensor (12).

10. The device for measuring the content of dissolved iron in liquid lead and bismuth according to claim 7, characterized in that: A retractable iron rod (14) is also provided on the upper part of the test container (17), and the retractable iron rod (14) extends in a direction toward the liquid lead bismuth (19).

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