Cavity quantitative leakage detection method and test device

Abstract

A method and test device for quantitative cavity leakage detection. The method is to divide the cavity into several leakage sub-areas and determine the leakage weight factor. Due to the presence of negative pressure inert gas and leakage, the oxygen content will increase linearly with time. At each moment, the oxygen content of the area can be measured, and then the oxygen content of these sub-areas is weighted and calculated by the leakage weight factor to obtain the oxygen content of the cavity at that moment. According to the least squares method, linear fitting is performed to process the data, and the leakage rate and Class A uncertainty in a unit time period can be obtained. The test device for implementing the above method is equipped with a temperature sensor and an oxygen content sensor inside the cavity, which are connected to a computer through a multi-channel multimeter; the pressure measuring port inside the cavity is connected to a high-precision pressure gauge, and the atmospheric pressure gauge and the high-precision digital pressure gauge signal are connected to the computer. The method can conveniently and quickly realize the online quantitative measurement of the leakage rate of the sealed cavity and accurately evaluate its sealing performance.

Description

Technical Field

[0001] The invention relates to an online quantitative leakage detection method and a test device, which are used for measuring and evaluating the leakage of a nuclear cavity and belong to the technical field of intelligent detection. Background Art

[0002] In industrial applications, some cavities are designed as reinforced concrete structures with stainless steel coverings to meet their specific functions. In order to ensure public safety, it is necessary to test and evaluate whether the sealing meets the design requirements. When the medium inside the cavity is dry, room temperature air, leakage rate measurement is relatively easy to achieve. However, in some applications, inert gas needs to be injected to make the cavity operate at a slight negative pressure because the oxygen content in the internal air needs to be strictly controlled. In addition, due to the large volume of the cavity itself, the internal temperature and oxygen content are distributed in different regions, which brings difficulties to its sealing detection. Commonly used sealing detection methods include pressure change method, oxygen content method, absolute pressure method, etc. The above detection methods and detection accuracy cannot meet the detection requirements. Summary of the invention

[0003] In order to solve the above-mentioned problems in the prior art, an object of the present invention is to provide a cavity quantitative leakage measurement method and a test device.

[0004] The present invention adopts the following technical scheme: a quantitative leakage measurement method, characterized in that: leakage modeling and simulation analysis are performed on the cavity, the cavity is divided into several leakage sub-areas, and its leakage weight factor is determined. Due to the leakage of the cavity containing negative pressure inert gas, the oxygen concentration will increase slowly over time, that is, the oxygen content will increase linearly with time. At each moment, the oxygen content of the area can be measured, and then the oxygen content of these sub-areas is weighted and calculated by the leakage weight factor, and the oxygen content of the cavity at that moment can be obtained. According to the least squares method, linear fitting is performed to process the data, and the leakage rate and Class A uncertainty in a unit time period can be obtained.

[0005] A test device for implementing the described cavity quantitative leakage detection method, characterized in that: it includes a test device, a pressure measuring device and a connecting mechanism, the pressure interface of the pressure measuring device is respectively connected to the atmospheric pressure port and to the measured cavity through the connecting mechanism; the electrical signal end of the pressure measuring device is connected to the corresponding interface of the test device through a cable; and the other interface of the test device is connected to the measured cavity through a cable and the connecting mechanism.

[0006] The beneficial effects of the present invention are as follows: the leakage sub-areas are divided, the occupied leakage weights are determined, the oxygen content in the cavity is detected by the oxygen content method, and the data is processed by the least squares method linear fitting, so that the quantitative online measurement of the leakage rate can be realized. The method can quickly and accurately evaluate the sealing performance of the cavity. The test device for realizing the method has a simple structure, high precision, and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic structural diagram of the sealing test device provided by the present invention.

[0008] In the figure: 1. Computer; 2. Multi-channel multimeter; 3. High-precision digital pressure gauge; 4. Acquisition card; 5. Terminal block; 6. Atmospheric pressure gauge; 7. Pressure gauge pressure port; 8. Atmospheric pressure port; 9. Special flange for test; 10. Temperature sensor electrical connector; 11. Oxygen content sensor electrical connector 2; 12. Air inlet; 13. Pressure measuring port; 14. Oxygen content sensor; 15. Temperature sensor; 16. Cavity connecting flange; A. Test device; B. Pressure measuring device; C. Connecting mechanism; D. Cavity to be tested. DETAILED DESCRIPTION

[0009] The present invention is further described below in conjunction with specific implementation examples.

[0010] The present invention provides a quantitative leakage measurement test device, comprising: a test device A, a pressure measuring device B and a connecting mechanism C, wherein the pressure interface of the pressure measuring device B is respectively connected to the atmospheric pressure port 8 and to the measured cavity D through the connecting mechanism C; the electrical signal end of the pressure measuring device B is connected to the corresponding interface of the test device A through a cable. The other interface of the test device A is connected to the measured cavity D through a cable and the connecting mechanism C.

[0011] The test device A comprises a computer 1, a multimeter 2, an acquisition card 4, a temperature sensor electrical connector 10, an oxygen content sensor electrical connector 11, an oxygen content sensor 14 and a temperature sensor 15. The oxygen content sensor 14 and the temperature sensor 15 are connected to one end of the temperature sensor electrical connector 10 and the oxygen content sensor electrical connector 11 provided on the connection mechanism C respectively; the other ends of the temperature sensor electrical connector 10 and the oxygen content sensor electrical connector 11 are connected to the wiring terminal 5, the acquisition card 4 and the computer 1 in sequence through a communication cable. The computer 1 is used to collect and analyze measurement data; the multimeter 2 is used to measure the temperature sensor and the oxygen content sensor; the acquisition card 4 and the wiring terminal 5 are high-precision modules for the multimeter 2 to realize the acquisition function; the temperature sensor 15 is used to measure the temperature inside the measured cavity D; the oxygen content sensor 14 is used to measure the oxygen content inside the measured cavity D.

[0012] The pressure measuring device B includes a high-precision digital pressure gauge 3 and an atmospheric pressure gauge 6. The signal output ends of the high-precision digital pressure gauge 3 and the atmospheric pressure gauge 6 are respectively connected to the corresponding interfaces of the computer 1 through cables to complete the collection of the pressure in the cavity and the ambient atmospheric pressure. The atmospheric pressure gauge 6 is provided with an atmospheric pressure port 8 for collecting atmospheric pressure; the high-precision digital pressure gauge 3 is provided with a pressure gauge pressure port 7, which is connected to the air inlet 12 provided on the connecting mechanism C through a hose, and the air inlet 12 is connected to the pressure measuring port 13 provided in the measured cavity D. Both the high-precision digital pressure gauge 3 and the atmospheric pressure gauge 6 use high-precision, high-resolution transmitters with long-distance signal transmission.

[0013] The connection mechanism C adopts a test-specific flange 9, on which a temperature sensor electrical connector 10, an oxygen content sensor electrical connector 11 and an air inlet 12 are respectively provided. The test-specific flange 9 matches the connection flange 16 of the cavity, and is respectively provided with corresponding screw holes, which are connected together by bolts. The connection between the test-specific flange 9 and the temperature sensor electrical connector 10 and the oxygen content sensor electrical connector 11 is coated with sealant to ensure sealing. All connection parts between the test-specific flange 9 and the connection flange 16 of the cavity are sealed with each other for easy testing.

[0014] When the test device of the present invention is used, the computer 1 periodically collects data from the multi-channel multimeter 2: the four-wire resistance signal and current signal of the temperature sensor 15 and the oxygen content sensor 14 inside the tested cavity are measured regularly, and the analog signal is sent to the computer 1 for conversion into the physical quantities of temperature and oxygen content. In addition, the gas pressure in the cavity is sent to the high-precision digital pressure gauge 3 through the pressure measuring port 13, the air inlet 12, and the pressure gauge pressure outlet 7; the ambient atmospheric pressure is sent to the atmospheric pressure gauge 6 through the atmospheric pressure port 8; finally, the computer 1 converts, displays, analyzes, and stores the above-collected signals.

[0015] The present invention adopts the above-mentioned test device to realize the quantitative leakage measurement method: the measured cavity D containing negative pressure inert gas is subjected to leakage modeling and simulation analysis, and is divided into several leakage sub-areas. The sensors of all sub-areas are connected to the connecting flange 16 with their own connecting cables, and then the connecting flange 16 is connected to the test-specific flange 9 and related components. Since there is leakage in the measured cavity D, the oxygen concentration will increase slowly over time, that is, the oxygen content will increase linearly with time. At each moment, the oxygen content of each leakage sub-area can be measured, and then the oxygen content of these leakage sub-areas is weighted and calculated by the leakage weight factor, and the oxygen content of the cavity at that moment can be obtained, and then the time-oxygen content function curve can be obtained. According to the least squares method, linear fitting is performed to process the data, and the leakage rate and Class A uncertainty in a unit time period can be obtained.

[0016] In order to obtain relatively accurate test results, the weighted average temperature and the pressure in the cavity must be maintained within a certain range during the test.

[0017] By measuring the temperature, oxygen content, pressure and atmospheric pressure parameters inside the cavity, the change in oxygen content in the cavity can be calculated according to the formula given below, thereby obtaining the leakage rate and Class A uncertainty of the sealed cavity.

[0018] The specific calculation method is as follows:

[0019] For each time point t i , the corresponding oxygen content in the cavity O i for:

[0020]

[0021] Where V j is the leakage weight factor of the oxygen content sensor in the jth leakage sub-area; ji is the oxygen content of the oxygen content sensor in the jth leakage sub-area at the i-th moment; k is the number of oxygen content sensors.

[0022] The weighted average temperature inside the cavity is T i The degree is:

[0023]

[0024] Where m is the number of temperature sensors; V fj —The weight coefficient of the jth temperature sensor; T ij — Celsius temperature of the jth temperature sensor at the i-th moment;

[0025] The linear least squares fit of the oxygen content data points is:

[0026]

[0027] In the formula, is the linear regression O i The best estimate of t i is the time from the start of the measurement to the i-th group of data; A is the slope of the least squares regression line (ppm / min); B is the intercept of the least squares regression line (ppm); the specific calculation method of A and B is:

[0028]

[0029]

[0030] Where n is the measurement data set (t i , O i )quantity.

[0031] Estimated value of leakage rate T fam is a function of the slope of the regression line and is calculated as follows:

[0032] T fam =300×A×10 -6 (h- 1 )

[0033] According to the uncertainty assessment principle, the type A uncertainty u A The evaluation formula is:

[0034] u A =300×S A ×10 -6 (h -1 )

[0035] Among them, h is time, unit: hour, h -1 The countdown of the hour; S A It is the unbiased estimate of the standard deviation of the least squares linear regression slope, i.e. the uncertainty component of the Class A assessment, in ppm / min.

Claims

1. A method for quantitative cavity leakage detection, characterized in that: Leakage modeling and simulation analysis are performed on the cavity containing negative pressure inert gas, which is divided into several leakage sub-areas and their leakage weight factors are determined; at each moment, the oxygen content of each leakage sub-area is measured; the oxygen content of these sub-areas is weighted and calculated by the leakage weight factor to obtain the oxygen content of the cavity at that moment and the time-oxygen content function curve data; the data is linearly fitted according to the least squares method to obtain the leakage rate and Class A uncertainty in a unit time period; The test device used in the cavity quantitative leakage detection method comprises a test device (A), a pressure measuring device (B) and a connecting mechanism (C); the pressure interface of the pressure measuring device (B) is respectively connected to the atmospheric pressure port (8) and to the measured cavity (D) through the connecting mechanism (C); the electrical signal end of the pressure measuring device (B) is connected to the corresponding interface of the test device (A) through a cable; the other interface of the test device (A) is connected to the measured cavity (D) through a cable and the connecting mechanism (C); the sensors of all leakage sub-areas in the measured cavity (D) are connected to the test device (A) through a set of connecting mechanisms (C).

2. The method for quantitative cavity leakage detection according to claim 1, characterized in that: The test device (A) comprises a computer (1), a multi-channel multimeter (2), an acquisition card (4), a temperature sensor electrical connector (10), an oxygen content sensor electrical connector (11), an oxygen content sensor (14) and a temperature sensor (15); the oxygen content sensor (14) and the temperature sensor (15) are respectively connected to one end of the temperature sensor electrical connector (10) and the oxygen content sensor electrical connector (11) provided on the connection mechanism (C); the other ends of the temperature sensor electrical connector (10) and the oxygen content sensor electrical connector (11) are connected to the wiring terminal (5), the acquisition card (4) and the computer (1) in sequence through a communication cable.

3. The method for quantitative cavity leakage detection according to claim 2, characterized in that: The pressure measuring device (B) comprises a high-precision digital pressure gauge (3) and an atmospheric pressure gauge (6), wherein the signal output ends of the high-precision digital pressure gauge (3) and the atmospheric pressure gauge (6) are respectively connected to corresponding interfaces of the computer (1) via cables; the atmospheric pressure gauge (6) is provided with an atmospheric pressure sampling port (8) for collecting atmospheric pressure; the high-precision digital pressure gauge (3) is provided with a pressure gauge pressure sampling port (7), which is connected to an air inlet (12) provided on the connecting mechanism (C) via a hose, and the air inlet (12) is connected to a pressure measuring port (13) provided in each leakage sub-area in the measured cavity (D).

4. The method for quantitative cavity leakage detection according to claim 1, characterized in that: The connecting mechanism (C) is a special test flange (9) that cooperates with a connecting flange (16) provided on the measured cavity (D), and a temperature sensor electrical connector (10), an oxygen content sensor electrical connector (11) and an air inlet (12) are respectively provided on the special test flange (9).

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