Method for measuring hydrogen concentration in closed space pipeline environment and application

Abstract

The invention belongs to the technical field of flammable and explosive gas concentration measurement, and particularly relates to a hydrogen concentration measurement method and application thereof. The measurement method comprises the following steps: (1) preparing a plurality of standard samples with different hydrogen concentrations; (2) enabling the standard samples with different hydrogen concentrations to pass through a catalytic sensitive element with a built-in palladium-platinum alloy catalyst respectively, and performing linear regression on the temperature rise value AT by using the hydrogen concentration # imgabs0 # according to a regression equation of # imgabs1 # (3) enabling the sample to be detected to pass through the catalytic sensitive element; and (4) calculating the concentration of hydrogen in the to-be-detected sample according to the regression equation and the temperature rise value of the to-be-detected sample. The measurement method is simple in process and has good stability, and a good prospect is provided for application of hydrogen measurement in a special environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of flammable and explosive gas concentration measurement, and in particular relates to a method for measuring hydrogen concentration in a confined space pipeline environment and its application. Background Art

[0002] In special confined spaces such as aviation or aerospace environments, based on the operating characteristics of manned spacecraft or aerial flight equipment and their long-term operation requirements, there is a need to continuously monitor the hydrogen concentration to ensure the operating environment of the spacecraft and the living environment of astronauts and avoid hydrogen risks.

[0003] Currently, hydrogen concentration measurement in aviation and aerospace environments relies on the principle of catalytic combustion. This principle involves the oxidation reaction of hydrogen with oxygen in the air, triggered by a catalytic metal, generating heat (the heat of flameless catalytic combustion), which is correlated with the hydrogen concentration. However, traditional hydrogen concentration analysis methods use a Wheatstone bridge circuit, which requires additional hardware circuitry and reduces operational reliability.

[0004] In order to achieve low power consumption and safe operation and ensure the life of the equipment, it is necessary to specially design a hydrogen measurement method to meet the use requirements of special confined spaces. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a method and application for measuring the hydrogen concentration in a confined space pipeline environment. The measurement method has low power consumption, is safe and reliable, and is particularly suitable for measuring the hydrogen concentration in special confined spaces.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] A method for measuring hydrogen concentration comprises the following steps:

[0008] (1) Prepare multiple standard samples with different hydrogen concentrations;

[0009] (2) The standard samples with different hydrogen concentrations were passed through the catalytic sensitive element with built-in palladium platinum alloy catalyst, and the temperature T1 (sample gas inlet temperature) before the premixed standard sample passed through the catalytic sensitive element and the temperature T2 (sample gas outlet temperature) after the premixed standard sample passed through the catalytic sensitive element were recorded. Perform linear regression on the temperature rise value AT, and the regression equation is:

[0010]

[0011] In formula (I), is the hydrogen concentration of the premixed standard sample, Vol%; AT is the temperature rise value of the premixed standard sample, AT = T2-T1, °C;

[0012] (3) sampling the gas in the test environment to obtain a test sample; passing the test sample through a catalytic sensitive element with a built-in palladium-platinum alloy catalyst, and recording the temperature rise value of the test sample;

[0013] (4) Calculate the concentration of hydrogen in the sample to be tested based on the regression equation and the temperature rise value of the sample to be tested.

[0014] The present invention utilizes a catalytic sensor with a built-in palladium-platinum alloy catalyst that activates at room temperature without requiring heating. At room temperature, H₂ comes into contact with oxygen, generating a catalytic reaction that produces heat according to the following equation: H₂(g) + 0.5O₂(g) → H₂O(g) + 241.2 kJ. The greater the H₂ concentration in the sample being tested, the greater the heat generated by the oxidation reaction, resulting in a greater temperature change (increase) before and after the sample passes through the catalytic sensor. By measuring the temperature difference and utilizing an algorithm, the hydrogen concentration is calculated. This measurement method offers the advantages of low power consumption, safety, reliability, and a long service life.

[0015] Preferably, step (1) specifically comprises: mixing hydrogen and air in a set ratio, and preparing at least 5 standard samples with different hydrogen concentrations within the hydrogen concentration range of the sample to be tested.

[0016] Further preferably, the hydrogen concentration of the sample to be tested is in the range of 0-4%.

[0017] Preferably, in step (2), the flow rate of the standard sample through the catalytic sensor is 0.3 L / min to 2 L / min. The flow rate of the gas affects the response time and measurement accuracy of the catalytic sensor. Studies have found that within the above flow rate range, the linear relationship of the detection method is good.

[0018] Preferably, in step (2), the palladium platinum alloy catalyst is PdPt / Al2O3, wherein the Pd loading is 0.63%-0.94% by weight and the Pt loading is 0.12%-0.68% by weight. The PdPt / Al2O3 catalyst can efficiently catalyze the hydrogen-oxygen recombination reaction at room temperature without the need for external power supply to heat the gas.

[0019] Preferably, in step (2), the amount of PdPt / Al2O3 catalyst used in the catalytic sensitive element is 1 g to 10 g.

[0020] Preferably, the flow rate of the sample to be tested through the catalytic sensitive element in step (3) is the same as the flow rate of the premixed standard sample through the catalytic sensitive element in step (2).

[0021] The present invention also provides an application of the above-mentioned measurement method in measuring the hydrogen concentration in a confined space environment (such as in aviation or aerospace equipment).

[0022] The beneficial effects achieved by the present invention are:

[0023] (1) The method for measuring hydrogen concentration provided by the present invention causes hydrogen and oxygen to undergo a catalytic chemical reaction at room temperature under the action of a palladium-platinum alloy catalyst, without the need for external energy supply, thereby reducing energy consumption.

[0024] (2) The hydrogen concentration measurement method provided by the present invention does not require heating of the gas to be measured, thus avoiding combustion and explosion caused by power supply or heating process when the hydrogen concentration is high, ensuring stability and safety during use, and is particularly suitable for detecting hydrogen concentration in a confined space environment.

[0025] (3) The hydrogen concentration measurement method provided by the present invention calculates the hydrogen concentration through a temperature rise algorithm, does not require a Wheatstone bridge, and improves working stability and working life.

[0026] (4) The method for measuring hydrogen concentration provided by the present invention has a simple process and good stability, which provides a good prospect for the application of hydrogen measurement in special environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the device used to measure hydrogen concentration in the embodiment; wherein, 1-sampling pipeline; 2-sample gas inlet temperature measuring device; 3-sample gas outlet temperature measuring device; 4-catalytic sensitive element; 5-palladium platinum alloy catalyst; 6-microprocessor. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0029] In the following examples, the devices used are as follows Figure 1 As shown, it includes a sampling pipeline 1, a sample gas inlet temperature measuring device 2, a sample gas outlet temperature measuring device 3, a catalytic sensitive element 4, a palladium-platinum alloy catalyst 5, and a microprocessor 6;

[0030] Wherein, the sample gas inlet temperature measuring device 2 and the sample gas outlet temperature measuring device 3 use thermocouples for temperature measurement;

[0031] The palladium platinum alloy catalyst 5 is PdPt / Al2O3, which is sourced from the 718th Research Institute of China Shipbuilding Industry Corporation, wherein the loading amount of Pd is 0.75 wt % and the loading amount of Pt is 0.34 wt %.

[0032] Example 1

[0033] Example 1 provides a method for measuring hydrogen concentration, comprising the following steps:

[0034] (1) Hydrogen and air were mixed in a set ratio to prepare standard samples with hydrogen concentrations of 0.5%, 1%, 2%, 3%, and 4% respectively;

[0035] (2) Standard samples with different hydrogen concentrations were respectively fed into the sampling pipe 1 at a flow rate of 0.5 L / min, and passed through the catalytic sensitive element 4 with a built-in 3 g palladium platinum alloy catalyst 5. The temperature T1 (the temperature detected by the sample gas inlet temperature measuring device 2) and the temperature T2 (the temperature detected by the sample gas outlet temperature measuring device 3) of the premixed standard sample before passing through the catalytic sensitive element were recorded, and the temperature rise value AT was obtained. The results are shown in Table 1 below:

[0036] Table 1

[0037]

[0038]

[0039] Hydrogen concentration Perform linear regression on the temperature rise value AT, and the regression equation is: when for When , K is taken as 29.8.

[0040] (3) sampling the gas in the test environment to obtain a test sample; feeding the test sample into the sampling pipe 1 at the same flow rate as in step (2), passing through the catalytic sensitive element 4 with a built-in palladium-platinum alloy catalyst 5, and recording the temperature rise value of the test sample;

[0041] (4) Based on the regression equation and the temperature rise value of the sample to be tested, the microprocessor 6 is used to calculate the concentration of hydrogen in the sample to be tested.

[0042] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for measuring hydrogen concentration, characterized in that: The following steps are involved: (1) Prepare multiple standard samples with different hydrogen concentrations; (2) The standard samples with different hydrogen concentrations were passed through the catalytic sensitive element with built-in palladium platinum alloy catalyst, and the temperature T1 before the premixed standard sample passed through the catalytic sensitive element and the temperature T2 after the premixed standard sample passed through the catalytic sensitive element were recorded. Perform linear regression on the temperature rise value AT, and the regression equation is: In formula (I), is the hydrogen concentration of the premixed standard sample, Vol%; AT is the temperature rise value of the premixed standard sample, AT = T2-T1, °C; (3) sampling the gas in the test environment to obtain a test sample; passing the test sample through a catalytic sensitive element with a built-in palladium-platinum alloy catalyst, and recording the temperature rise value of the test sample; (4) Calculate the concentration of hydrogen in the sample to be tested based on the regression equation and the temperature rise value of the sample to be tested.

2. The method for measuring hydrogen concentration according to claim 1, wherein: Step (1) specifically comprises: mixing hydrogen and air in a set ratio, and preparing at least five standard samples with different hydrogen concentrations within the hydrogen concentration range of the sample to be tested.

3. The method for measuring hydrogen concentration according to claim 2, wherein: The hydrogen concentration of the sample to be tested ranges from 0 to 4%.

4. The method for measuring hydrogen concentration according to any one of claims 1 to 3, characterized in that: In step (2), the flow rate of the standard sample through the catalytic sensitive element is 0.3 L / min-2 L / min.

5. The method for measuring hydrogen concentration according to any one of claims 1 to 3, characterized in that: In step (2), the palladium platinum alloy catalyst is PdPt / Al2O3, wherein the loading amount of Pd is 0.63%-0.94%, and the loading amount of Pt is 0.12%-0.68wt%.

6. The method for measuring hydrogen concentration according to any one of claims 1 to 3, characterized in that: In step (2), the amount of PdPt / Al2O3 catalyst used in the catalytic sensitive element is 1g to 10g.

7. The method for measuring hydrogen concentration according to any one of claims 1 to 3, characterized in that: The flow rate of the sample to be tested through the catalytic sensitive element in step (3) is the same as the flow rate of the premixed standard sample through the catalytic sensitive element in step (2).

8. Use of the measurement method according to any one of claims 1 to 7 in measuring hydrogen concentration in a confined space environment.

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