Method for testing oxygen content in hydrogen compatibility test environment box of hydrogen transmission pipeline

Abstract

The invention relates to a method for testing the content of oxygen in a hydrogen compatibility test environment box of a hydrogen transmission pipeline, belongs to the technical field of gas detection, and solves at least one of the problems that in the prior art, the content of low-concentration oxygen in high-pressure hydrogen is not accurately measured, is easily interfered by oxygen in air, and needs to be sampled for off-line measurement. The invention provides an on-line oxygen content measuring method. The oxygen content in sample gas is obtained through starting preheating, pipeline purging, measuring range calibration and sample gas measurement. The measuring method is suitable for online measurement of the low-concentration oxygen content of 0-100 ppm in high-pressure hydrogen, interference of external oxygen can be eliminated in the measuring process, the measuring result is accurate, and the measuring method is particularly suitable for detection and auxiliary control of the oxygen content in an experimental environment box in hydrogen compatibility experiments of various materials.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology, and in particular to a method for testing the oxygen content in a hydrogen compatibility test environment chamber for hydrogen pipelines. Background Technology

[0002] With the depletion of traditional resources and the deterioration of climate conditions, the accelerated transition of humankind from traditional energy sources such as fossil fuels to new green energy sources is inevitable. Hydrogen energy is a clean secondary energy source and can serve as an efficient energy storage medium. To achieve economical and efficient hydrogen transportation, long-distance pipelines are one of the most suitable methods.

[0003] Due to the significant differences in physical properties between natural gas and hydrogen, high-pressure hydrogen will lead to the deterioration of the relevant mechanical properties of pipeline steel. The higher the hydrogen pressure and the higher the material strength, the more pronounced hydrogen embrittlement and hydrogen-induced cracking will be. Because of the influence of environmental hydrogen embrittlement, the materials used in hydrogen pipelines face certain limitations compared to natural gas pipelines in terms of alloying elements, steel grades, pipe types, and operating pressures. Hydrogen compatibility testing refers to mechanical property tests conducted in a gaseous hydrogen environment, including slow tensile testing, fracture toughness, fatigue life, and fatigue crack propagation rate, to evaluate the degree of deterioration of pipeline steel materials by hydrogen.

[0004] Numerous studies have shown that oxygen content has a significant impact on hydrogen embrittlement sensitivity. O2 occupies the adsorption sites of H2 on the Fe surface and inhibits H2 decomposition. The national standard "Test Method for Compatibility of Metallic Materials with Hydrogen Environment" stipulates that the O2 content in the environmental chamber must not exceed 1 ppm. Variations in oxygen content within the range of 0.1–5 ppm in the environmental chamber can have a significant impact on the hydrogen environmental compatibility test results of pipeline steel; therefore, testing the oxygen content in the environmental chamber is particularly important.

[0005] Currently, existing technologies generally use offline sampling and detection to detect oxygen content in environmental chambers. This method cannot monitor oxygen content in the environmental chamber in real time and has drawbacks such as inaccurate detection results and susceptibility to interference from oxygen in the air. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide an online method for measuring low-concentration oxygen content in high-pressure hydrogen, in order to solve at least one of the problems in the prior art, such as inaccurate measurement of low-concentration oxygen content in high-pressure hydrogen, susceptibility to interference from oxygen in the air, and the need for offline sampling measurement.

[0007] This invention provides an online method for measuring oxygen content, the method specifically including the following steps:

[0008] S1: Turn on and preheat the matching online oxygen content measurement system, and purge the system with high-purity N2;

[0009] S2: After purging, introduce zero-point standard gas and maximum range standard gas respectively to calibrate and standardize the range of the oxygen analyzer.

[0010] S3: After calibration, the gas sample to be tested is introduced into the online measurement system, and the oxygen content in the gas sample to be tested is read by the oxygen analyzer;

[0011] The sample gas to be tested is a mixture of hydrogen and oxygen, with an oxygen content of 0–100 ppm.

[0012] Specifically, the structure of the online oxygen content measurement system is as follows:

[0013] The system includes three air inlets and two air outlets;

[0014] The air inlets are respectively the sample gas inlet, the purge gas inlet, and the standard gas inlet;

[0015] The gas outlets are respectively the vent outlet and the sample gas outlet;

[0016] The sample gas inlet and the purge gas inlet are connected by a first three-way valve, and are connected to the sample gas outlet in sequence via a two-way valve, a first pressure reducing valve, a pressure gauge, a second three-way valve, a flow controller, and a third three-way valve.

[0017] The standard gas inlet is connected to the pressure gauge and flow controller via a second three-way valve;

[0018] The vent outlet is connected to the sample gas outlet and the flow controller via a third three-way valve;

[0019] The sample gas outlet is connected to the oxygen analyzer.

[0020] Specifically, the sample gas inlet is connected to the sample gas environment and the vacuum pump via a sample gas three-way valve;

[0021] The standard gas inlet is connected to the standard gas cylinder outlet, and a standard gas pressure reducing valve is installed at the standard gas cylinder outlet.

[0022] Specifically, in step S1, the first three-way valve, the second three-way valve, and the third three-way valve are adjusted so that the high-purity N2 passes through the purge gas inlet, and then sequentially through the first three-way valve, the two-way valve, the first pressure reducing valve, the pressure gauge, the second three-way valve, the flow controller, the third three-way valve, and the sample gas outlet before entering the oxygen analyzer.

[0023] Adjust the flow controller to achieve a high-purity N2 flow rate of 400 ml / min and a purging time of ≥8 h;

[0024] The oxygen analyzer is in an inactive state before the purging is completed, and the oxygen sensor inside the oxygen analyzer does not come into direct contact with the gas in the pipeline.

[0025] After purging is complete, the oxygen analyzer is switched to the active state, and the oxygen sensor inside the oxygen analyzer comes into contact with the gas in the pipeline.

[0026] Specifically, after purging, high-purity N2 continues to be supplied to the pipeline to prevent damage to the oxygen sensor.

[0027] Specifically, in step S2, the oxygen analyzer is first set to the off state, and then the second three-way valve is adjusted to connect the standard gas inlet, the second three-way valve, the flow controller, the third three-way valve, the sample gas outlet, and the oxygen analyzer.

[0028] Connect the zero-point standard gas cylinder to the standard gas inlet, adjust the flow controller to make the zero-point standard gas flow rate 400 ml / min, and after ventilating for at least 30 minutes, turn the oxygen analyzer into the working state.

[0029] After continuing ventilation for at least 45 minutes, simultaneously adjust the standard gas pressure reducing valve and flow controller to make the zero-point standard gas pressure in the pipeline 0.2 MPa and the flow rate 400 ml / min.

[0030] After continuing ventilation for at least 15 minutes, read the oxygen analyzer reading and calibrate and standardize the zero point of the oxygen analyzer based on the actual oxygen concentration of the zero-point standard gas.

[0031] Replace the zero-point standard gas cylinder with the maximum range standard gas cylinder and repeat the above steps to complete the maximum range calibration and standardization of the oxygen analyzer.

[0032] Specifically, in step S3, the sample gas three-way valve is first adjusted to connect the sample gas three-way valve, the vacuum pump, the sample gas inlet, and the first three-way valve.

[0033] At this time, the sample gas three-way valve and the gas environment are not connected, the first three-way valve is not connected to other pipelines, and a closed pipeline is formed between the sample gas three-way valve and the first three-way valve.

[0034] Turn on the vacuum pump to create a vacuum inside the sealed pipeline.

[0035] Specifically, in step S3, after the inside of the closed pipeline is converted to a vacuum state, the vacuum pump is turned off and the sample gas three-way valve is adjusted to connect it with the sample gas environment.

[0036] Adjust the first three-way valve so that the sample gas enters the oxygen analyzer after passing through the first three-way valve, two-way valve, first pressure reducing valve, pressure gauge, second three-way valve, flow controller, third three-way valve, and sample gas outlet.

[0037] Specifically, adjust the flow controller and the first pressure reducing valve to make the sample gas pressure in the pipeline 0.2MPa and the flow rate 400ml / min. At this time, the oxygen analyzer reading is the oxygen content in the sample gas.

[0038] After the measurement is completed, adjust the first three-way valve to put the system into a purging state, so that the flow rate of high-purity N2 gas through the flow meter is 400 ml / min, and protect the instrument.

[0039] The present invention also provides an online oxygen content measurement system, which is used to implement the above-described measurement method.

[0040] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0041] 1. The measurement method provided by this invention can realize online measurement of low concentration oxygen content in high-pressure hydrogen gas without the need for offline sampling. It can monitor the oxygen content in the sample gas in real time. For hydrogen environmental compatibility tests, it can provide data reference for monitoring and adjusting the gas state in the environmental test chamber.

[0042] 2. The measurement method provided by this invention strictly ensures the purity of the pipelines in the system through rigorous pre-test purging, pre-range calibration purging, and pre-intake vacuuming operations, avoiding interference from oxygen in the air on the measurement results; and a high-sensitivity oxygen analyzer is selected to achieve accurate measurement of oxygen content from 0 to 100 ppm through an oxygen sensor.

[0043] 3. The measurement method provided by this invention avoids exposing the oxygen sensor to a high concentration of oxygen by strictly controlling the on / off state of the oxygen sensor. This protects the oxygen sensor from damage and ensures the accuracy of the oxygen sensor signal, thereby improving detection accuracy.

[0044] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0045] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0046] Figure 1 A schematic diagram of the process / structure of an online oxygen content measurement system;

[0047] Figure 2 This is a schematic diagram of a slow tensile test environment chamber, a common component in hydrogen compatibility testing.

[0048] Figure label:

[0049] 1. Sample gas inlet; 2. Purge gas inlet; 3. First three-way valve; 4. Two-way valve; 5. First pressure reducing valve; 6. Pressure gauge; 7. Second three-way valve; 8. Standard gas inlet; 9. Flow controller; 10. Sample gas outlet; 11. Oxygen analyzer; 12. Third three-way valve; 13. Vent outlet; 14. System boundary;

[0050] 15. Tensile specimen; 16. Air inlet valve of the test environment chamber; 17. Main body of the test environment chamber; 18. Air outlet valve of the test environment chamber. Detailed Implementation

[0051] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0052] This invention provides an online method for measuring low-concentration oxygen content in high-pressure hydrogen gas, the method specifically including the following steps:

[0053] S1: Turn on and preheat the matching online oxygen content measurement system, and purge the system with high-purity N2;

[0054] S2: After purging, introduce zero-point standard gas and maximum range standard gas respectively to calibrate and standardize the range of the oxygen analyzer.

[0055] S3: After calibration, the gas sample to be tested is introduced into the online measurement system, and the oxygen content in the gas sample to be tested is read by the oxygen analyzer;

[0056] The sample gas to be tested is a mixture of hydrogen and oxygen, with an oxygen content of 0–10 ppm.

[0057] Specifically, the structure of the online oxygen content measurement system is as follows:

[0058] The system includes three air inlets and two air outlets;

[0059] The air inlets are respectively the sample gas inlet, the purge gas inlet, and the standard gas inlet;

[0060] The gas outlets are respectively the vent outlet and the sample gas outlet;

[0061] The sample gas inlet and the purge gas inlet are connected by a first three-way valve, and are connected to the sample gas outlet in sequence via a two-way valve, a first pressure reducing valve, a pressure gauge, a second three-way valve, a flow controller, and a third three-way valve.

[0062] The standard gas inlet is connected to the pressure gauge and flow controller via a second three-way valve;

[0063] The vent outlet is connected to the sample gas outlet and the flow controller via a third three-way valve;

[0064] The sample gas outlet is connected to the oxygen analyzer.

[0065] Specifically, the sample gas inlet is connected to the sample gas environment and the vacuum pump via a sample gas three-way valve;

[0066] For example, with Figure 2 Taking the test environment chamber as an example, the gas outlet valve of the test environment chamber is a three-way valve, namely the sample gas three-way valve. One end of the three-way valve is connected to the vacuum pump, and the other end is connected to the sample gas inlet.

[0067] The standard gas inlet is connected to the standard gas cylinder outlet, and a standard gas pressure reducing valve is installed at the standard gas cylinder outlet.

[0068] Specifically, in step S1, the first three-way valve, the second three-way valve, and the third three-way valve are adjusted so that the high-purity N2 passes through the purge gas inlet, and then sequentially through the first three-way valve, the two-way valve, the first pressure reducing valve, the pressure gauge, the second three-way valve, the flow controller, the third three-way valve, and the sample gas outlet before entering the oxygen analyzer.

[0069] Adjust the flow controller to achieve a high-purity N2 flow rate of 400 ml / min and a purging time of ≥8 h;

[0070] The purpose of this step is to fully replace the gas in the pipeline with high-purity N2 to avoid interference from oxygen in the residual gas in the pipeline on the measurement results.

[0071] The oxygen analyzer is in an inactive state before purging is completed, and the oxygen sensor inside the analyzer does not directly contact the gas in the pipeline. After purging is completed, the oxygen analyzer is switched to the active state, and the oxygen sensor inside the analyzer comes into contact with the gas in the pipeline. The purpose of the above operation is to avoid direct contact between the oxygen sensor and high concentrations of oxygen, so as to avoid sensor damage or inaccurate detection results.

[0072] Specifically, after purging, high-purity N2 continues to be supplied to the pipeline to prevent damage to the oxygen sensor.

[0073] Specifically, in step S2, the oxygen analyzer is first set to the off state; this operation is to prevent the oxygen in the residual gas in the pipeline section from the standard gas inlet—the second three-way valve—from damaging the oxygen sensor.

[0074] Then adjust the second three-way valve to connect the standard gas inlet, the second three-way valve, the flow controller, the third three-way valve, the sample gas outlet, and the oxygen analyzer.

[0075] Connect the zero-point standard gas cylinder to the standard gas inlet, adjust the flow controller to make the zero-point standard gas flow rate 400 ml / min, and after ventilating for at least 30 minutes, turn the oxygen analyzer into the working state.

[0076] After continuing ventilation for at least 45 minutes, simultaneously adjust the standard gas pressure reducing valve and flow controller to make the zero-point standard gas pressure in the pipeline 0.2 MPa and the flow rate 400 ml / min.

[0077] The pressure and flow rate of the standard gas (zero-point standard gas and maximum range standard gas) are kept consistent with those used in the final measurement to ensure the accuracy of the measurement and to minimize the decrease in the reliability of the measurement results caused by changes in gas pressure and flow rate.

[0078] After continuing ventilation for at least 15 minutes, read the oxygen analyzer reading and calibrate and standardize the zero point of the oxygen analyzer according to the actual oxygen concentration of the zero point standard gas. For example, if the zero point standard gas with an oxygen content of 0.5 ppm (balance gas: H2) is used, and the oxygen analyzer reading is 0.4 ppm, then the oxygen analyzer reading can be adjusted to 0.5 ppm by manually adjusting the calibration knob or by software debugging.

[0079] Replace the zero-point standard gas cylinder with the maximum range standard gas cylinder, and repeat the above steps to complete the maximum range calibration and standardization of the oxygen analyzer.

[0080] For example, if the oxygen analyzer reads 9.8 ppm when using a standard gas with a maximum range of 10 ppm oxygen content (balance gas: H2), the oxygen analyzer reading can be adjusted to 10 ppm by manually adjusting the calibration knob or by software debugging.

[0081] Preferably, the oxygen analyzer has a range of 0–10 ppm.

[0082] It is worth noting that if a larger oxygen analyzer (such as 100ppm) is selected, the maximum range of standard gas can be adjusted simultaneously.

[0083] Specifically, in step S3, the sample gas three-way valve is first adjusted to connect the sample gas three-way valve, the vacuum pump, the sample gas inlet, and the first three-way valve.

[0084] At this time, the sample gas three-way valve and the gas environment are not connected, the first three-way valve is not connected to other pipelines, and a closed pipeline is formed between the sample gas three-way valve and the first three-way valve.

[0085] Turn on the vacuum pump to create a vacuum inside the sealed pipeline.

[0086] The purpose of this operation is to purge the residual gas inside the closed pipeline to prevent the oxygen in the residual gas from interfering with the measurement results.

[0087] Specifically, in step S3, after the inside of the closed pipeline is converted to a vacuum state, the vacuum pump is turned off and the sample gas three-way valve is adjusted to connect it with the sample gas environment.

[0088] Adjust the first three-way valve so that the sample gas enters the oxygen analyzer after passing through the first three-way valve, two-way valve, first pressure reducing valve, pressure gauge, second three-way valve, flow controller, third three-way valve, and sample gas outlet.

[0089] Specifically, adjust the flow controller and the first pressure reducing valve to make the sample gas pressure in the pipeline 0.2MPa and the flow rate 400ml / min. At this time, the oxygen analyzer reading is the oxygen content in the sample gas.

[0090] After the measurement is completed, adjust the first three-way valve to put the system into a purging state, so that the flow rate of high-purity N2 gas through the flow meter is 400 ml / min, and protect the instrument.

[0091] The present invention also provides an online oxygen content measurement system, which is used to implement the above-described measurement method.

[0092] Furthermore, under long-term operation, the measurement system should be calibrated every 7 days (maximum 30 days). When the measurement system is not in use for an extended period, the air inside the system should be replaced monthly (refer to step S1) to prevent the oxygen sensor from being exposed to an oxygen-rich environment, which could damage the sensor. The oxygen sensor is a consumable and it is recommended to replace it annually (it wears out faster when used in an oxygen-rich environment).

[0093] Example 1

[0094] Adopting such Figure 1 The measurement system shown detects the oxygen content of the gas inside the environmental test chamber.

[0095] S1: Turn on and preheat the matching online oxygen content measurement system, adjust the first three-way valve, the second three-way valve and the third three-way valve so that the high-purity N2 enters the oxygen analyzer after passing through the purge gas inlet, the first three-way valve, the two-way valve, the first pressure reducing valve, the pressure gauge, the second three-way valve, the flow controller, the third three-way valve and the sample gas outlet in sequence.

[0096] Adjust the flow controller to achieve a high-purity N2 flow rate of 400 ml / min and a purging time of ≥8 h;

[0097] After 8 hours of purging, the oxygen analyzer was activated, and the instrument reading fluctuated between 4.65 and 4.72 ppm; the purity (volume) of the high-purity nitrogen gas was ≥99.999%.

[0098] S2: First, set the oxygen analyzer to the off state;

[0099] Then adjust the second three-way valve to connect the standard gas inlet, the second three-way valve, the flow controller, the third three-way valve, the sample gas outlet, and the oxygen analyzer.

[0100] Connect the zero-point standard gas cylinder to the standard gas inlet, adjust the flow controller to make the zero-point standard gas flow rate 400 ml / min, and after ventilating for at least 30 minutes, turn the oxygen analyzer into the working state.

[0101] The zero-point standard gas is hydrogen with an oxygen content of 0.5 ppm, and hydrogen is the balance gas;

[0102] After continuing ventilation for at least 45 minutes, simultaneously adjust the standard gas pressure reducing valve and flow controller to make the zero-point standard gas pressure in the pipeline 0.2 MPa and the flow rate 400 ml / min.

[0103] After continuing ventilation for at least 15 minutes, read the oxygen analyzer reading. The reading is 0.51 ppm. Adjust the reading to 0.50 ppm using the calibration software or by manually turning the calibration knob.

[0104] Replace the zero-point standard gas cylinder with the maximum range standard gas cylinder, and repeat the above steps to complete the maximum range calibration and standardization of the oxygen analyzer.

[0105] The oxygen analyzer has a range of 0 to 10 ppm, and the maximum range standard gas is hydrogen with an oxygen content of 10 ppm. Hydrogen is the balance gas.

[0106] S3: Adjust the sample gas three-way valve to connect the sample gas three-way valve, vacuum pump, sample gas inlet and first three-way valve;

[0107] At this time, the sample gas three-way valve and the gas environment (inside the test environment chamber) are not connected, the first three-way valve is not connected to other pipelines, and a closed pipeline is formed between the sample gas three-way valve and the first three-way valve.

[0108] Turn on the vacuum pump to make the inside of the closed pipeline a vacuum state, so that the pressure in the gas line is ≤2Pa;

[0109] Turn off the vacuum pump and adjust the sample gas three-way valve to connect it to the sample gas environment (inside the test environment chamber);

[0110] Adjust the first three-way valve so that the sample gas enters the oxygen analyzer after passing through the first three-way valve, two-way valve, first pressure reducing valve, pressure gauge, second three-way valve, flow controller, third three-way valve, and sample gas outlet;

[0111] Adjust the flow controller and the first pressure reducing valve to make the sample gas pressure in the pipeline 0.2MPa and the flow rate 400ml / min. After the oxygen analyzer reading stabilizes, the oxygen content in the sample gas is read as 0.80ppm by the oxygen analyzer.

[0112] After the measurement is completed, adjust the first three-way valve to put the system into a purging state, so that the flow rate of high-purity N2 gas through the flow meter is 400 ml / min, and protect the instrument.

[0113] Gas samples were taken from inside the test chamber and analyzed offline. The oxygen content was measured to be 0.79 ppm, with an error of ≤1.5% compared to the result given by this measurement method.

[0114] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for online measurement of oxygen content, characterized in that, The measurement method specifically includes the following steps: S1: Turn on and preheat the matching online oxygen content measurement system, and purge the system with high-purity N2; S2: After purging, zero-point standard gas and maximum range standard gas are introduced to calibrate and standardize the range of the oxygen analyzer (11); S3: After calibration, the gas to be tested is introduced into the online measurement system, and the oxygen content in the gas to be tested is read by the oxygen analyzer (11). The sample gas to be tested is a mixture of hydrogen and oxygen, with an oxygen content of 0–100 ppm.

2. The measurement method according to claim 1, characterized in that, The specific structure of the online oxygen content measurement system is as follows: The system includes three air inlets and two air outlets; The air inlets are respectively the sample gas inlet (1), the purge gas inlet (2), and the standard gas inlet (8); The gas outlets are respectively the vent outlet (13) and the sample gas outlet (10); The sample gas inlet (1) and purge gas inlet (2) are connected by a first three-way valve (3), and are connected to the sample gas outlet (10) in sequence via a two-way valve (4), a first pressure reducing valve (5), a pressure gauge (6), a second three-way valve (7), a flow controller (9), and a third three-way valve (12). The standard gas inlet (8) is connected to the pressure gauge (6) and the flow controller (9) via the second three-way valve (7); The vent outlet (13) is connected to the sample gas outlet (10) and the flow controller (9) via the third three-way valve (12); The sample gas outlet (10) is connected to the oxygen analyzer (11).

3. The measurement method according to claim 2, characterized in that, The sample gas inlet (1) is connected to the sample gas environment and vacuum pump via a sample gas three-way valve; The standard gas inlet (8) is connected to the standard gas cylinder outlet, and a standard gas pressure reducing valve is provided at the standard gas cylinder outlet.

4. The measurement method according to claim 2, characterized in that, In step S1, the first three-way valve (3), the second three-way valve (7), and the third three-way valve (12) are adjusted so that the high-purity N2 passes through the purge gas inlet (2), and then sequentially through the first three-way valve (3), the two-way valve (4), the first pressure reducing valve (5), the pressure gauge (6), the second three-way valve (7), the flow controller (9), the third three-way valve (12), and the sample gas outlet (10) before entering the oxygen analyzer (11); Adjust the flow controller (9) to make the flow rate of high-purity N2 400 ml / min and the purging time ≥ 8 h; The oxygen analyzer (11) is in an inactive state before the purging is completed, and the oxygen sensor inside the oxygen analyzer (11) does not directly contact the gas in the pipeline. After purging is completed, the oxygen analyzer (11) is put into operation and the oxygen sensor inside the oxygen analyzer (11) comes into contact with the gas in the pipeline.

5. The measurement method according to claim 4, characterized in that, After purging, high-purity N2 continues to be supplied to the pipeline to prevent damage to the oxygen sensor.

6. The measurement method according to claim 3, characterized in that, In step S2, the oxygen analyzer (11) is first set to the off state, and then the second three-way valve (7) is adjusted to connect the standard gas inlet (8), the second three-way valve (7), the flow controller (9), the third three-way valve (12), the sample gas outlet (10) and the oxygen analyzer (11). Connect the zero-point standard gas cylinder to the standard gas inlet (8), adjust the flow controller (9) to make the zero-point standard gas flow rate 400 ml / min, and after ventilating for at least 30 minutes, adjust the oxygen analyzer (11) to the start state. After continuing ventilation for at least 45 minutes, simultaneously adjust the standard gas pressure reducing valve and flow controller (9) to make the zero-point standard gas pressure in the pipeline 0.2MPa and the flow rate 400ml / min; After continuing ventilation for at least 15 minutes, read the oxygen analyzer (11) reading and calibrate and standardize the zero point of the oxygen analyzer (11) according to the actual oxygen concentration of the zero point standard gas. Replace the zero-point standard gas cylinder with the maximum range standard gas cylinder and repeat the above steps to complete the maximum range calibration and standardization of the oxygen analyzer (11).

7. The measurement method according to claim 3, characterized in that, In step S3, the sample gas three-way valve is first adjusted so that the sample gas three-way valve, vacuum pump, sample gas inlet (1) and first three-way valve (3) are connected. At this time, the sample gas three-way valve and the gas environment are not connected, the first three-way valve (3) is not connected to other pipelines, and a closed pipeline is formed between the sample gas three-way valve and the first three-way valve (3). Turn on the vacuum pump to create a vacuum inside the sealed pipeline.

8. The measurement method according to claim 7, characterized in that, In step S3, after the inside of the closed pipeline is converted to a vacuum state, the vacuum pump is turned off and the sample gas three-way valve is adjusted to connect it with the sample gas environment. Adjust the first three-way valve (3) so that the sample gas enters the oxygen analyzer (11) after passing through the first three-way valve (3), two-way valve (4), first pressure reducing valve (5), pressure gauge (6), second three-way valve (7), flow controller (9), third three-way valve (12), and sample gas outlet (10).

9. The measurement method according to claim 8, characterized in that, Adjust the flow controller (9) and the first pressure reducing valve (5) so that the pressure of the sample gas in the pipeline is 0.2MPa and the flow rate is 400ml / min. At this time, the reading of the oxygen analyzer (11) is the oxygen content in the sample gas. After the measurement is completed, adjust the first three-way valve (3) to put the system in a purging state, so that the flow rate of high-purity N2 gas through the flow meter is 400 ml / min, and protect the instrument.

10. An online oxygen content measurement system, characterized in that, The measurement system is used to implement the measurement method according to any one of claims 1 to 9.

Images