Online monitoring method for photoacoustic spectrum of decomposition product of sulfur hexafluoride gas

Abstract

The invention discloses an online monitoring method for a photoacoustic spectrum of a decomposition product of sulfur hexafluoride gas. The online monitoring method comprises the following steps: preparing to-be-tested standard gases with different concentrations; setting the modulation frequency of a chopper at 1045Hz under the environmental conditions as follows: the room temperature is 25 DEG C, and the pressure intensity is 0.1MPa; closing an air inlet valve, opening an air outlet valve, vacuumizing a photoacoustic cell by virtue of a vacuum pump, closing the air outlet valve, opening theair inlet valve, introducing to-be-tested standard gas into the photoacoustic cell, and repeatedly carrying out the step for several times; introducing the standard gas with a known concentration intothe photoacoustic cell, and recording a photoacoustic signal value measured by a lock-in amplifier; and detecting partial discharging and decomposing characteristic gas of SF6 so as to obtain the relation between the gas concentration and a photoacoustic signal, and acquiring quantitative relation curves between photoacoustic signal amplitudes and volume fractions of four components. According tothe method, SOF2, SO2, CO2 and CF4 can be detected by virtue of a built photoacoustic experimental platform, and the relation between the photoacoustic signal strength and gas volume fraction of thecharacteristic gas can be obtained.

Description

technical field [0001] The invention relates to the technical field of sulfur hexafluoride, in particular to a photoacoustic spectrum online monitoring method for gas decomposition products of sulfur hexafluoride. Background technique [0002] At present, domestic and foreign 6 Although the traditional detection methods of decomposing components under partial discharge have their own advantages, they all have some shortcomings. It needs to be cleaned and recalibrated after a period of time. The long-term stability is not good, the environmental requirements are high, and the detection time is long, so it is not suitable for continuous online monitoring. At present, the practical detection tube method at home and abroad is used to detect SF 6 When decomposing gas, only HF and SO can be detected 2 、SOF 2 It has no detection effect on other major decomposition gases, and cannot fully reflect SF 6 Discharge decomposes gas, and its performance is greatly affected by temperatu...

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Problems solved by technology

[0002] At present, domestic and foreign 6 Although the traditional detection methods of decomposing components under partial discharge have their own advantages, they all have some shortcomings. It needs to be cleaned and recalibrated after a period of time. The long-term stability is not good, the environmental requirements are high, and the detection time is long, so it is not suitable for continuous online monitoring. At present, the practical detection tube method at home and abroad is used to detect SF 6 When decomposing gas, only HF and SO can be detected 2 、SOF 2 It has no detection effect on other major decomposition gases, and cannot fully reflect SF 6 Discharge decomposes gas, and its performance is greatly affected by temperature and humidity, so it is not suitable for online monitoring; due to the large volume of the gas cell in infrared absorption spectroscopy, the demand for the gas to be measured is increased. When detecting trace gases, the incident light intensity There is little difference from the intensity of transmitted light, the detection sensitivity is not high, and its detection accuracy is greatly affected by reflection and scattered light; the gas sensor method will cause chemical reactions between the measured gas and the semiconductor, long-term use will cause sensor poisoning, thus affecting The detection accuracy of the sensor and the long-term stability are not good; ion chromatography is due to SF 6 Discharge decomposition products are mostly covalent compounds, which is inconvenient to use; traditional mass spectrometry generally has no gas separation ability, and cannot be directly used for real-time qualitative and quantitative analysis of the components to be measured. It is often used in combination with gas chromatography and cannot be used for online monitoring.

[0003] Due to traditional SF 6 The detection method of discharge decomposition components has its own shortcomings. It is very necessary to find a new gas detection method with high sensitivity, good reliability and online monitoring.

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