Double pool series photoacoustic spectroscopy gas detecting device and method

Abstract

The invention provides a double pool series photoacoustic spectroscopy gas detecting device. A sample photoacoustic pool comprises a sample gas inlet, a sample gas outlet, a sample incident window, asample exit widow, and a sample detection device, wherein a reference photoacoustic pool comprises a reference gas inlet, a reference gas outlet, a reference incident window, a reference exit window and a reference detection device, the sample exit window and the reference incident window are sealed and connected through a high infrared transmittance window, the sample detection device comprises afirst acoustic sensor, a first preamplifier, a first phase-locked amplifier, and a collection unit, the reference detection device comprises a second acoustic sensor, a second preamplifier, a secondphase-locked amplifier, and a measurement control unit, a laser comprises a laser generator, a laser body, a temperature control unit and a frequency modulation unit, and the reference pool seals to-be-tested gas with high concentration, so as to help lock laser wavelength and modulation frequency automatically, therefore, measured gas content is reliable and accurate, and the whole photoacousticsystem always works in the best state.

Description

technical field [0001] The invention belongs to the technical field of gas detection, and in particular relates to a gas detection device and method of a double-cell series photoacoustic spectrum. Background technique [0002] Trace gases in transformer oil are produced during the long-term operation of the transformer. They reflect the partial operation status of the transformer. The monitoring of trace gases in transformer oil can predict the possible operation risks of the transformer. In recent years, photoacoustic spectroscopy has detected The technology is gradually applied to the detection of trace gases in transformer oil, especially some gases with very low content such as C2H2. Photoacoustic spectroscopy technology is based on the photoacoustic effect of gas. The gas molecules of the sample to be tested can absorb the laser photon energy of a specific wavelength and undergo energy level transitions. The high-energy excited state is an unstable state. A large number...

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Problems solved by technology

[0004] As mentioned earlier, in photoacoustic spectroscopy detection, only when the frequency of expansion and contraction of the gas to be measured is consistent with the characteristic frequency of the photoacoustic cell, resonance can occur and the microphone sensor can output a strong signal, otherwise the signal of the microphone sensor will be weak and difficult to detect

However, changes in temperature, pressure, humidity and other conditions in actual detection may cause the characteristic resonance frequency to drift. Once the drift occurs, the photoacoustic resonance effect will be significantly weakened, and the output signal of the microphone sensor will decrease. If the output signal of the sensor is used as the detection signal, the detection value will be low and the error will be large

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