Research on On-line Detection Method and Device Development of HF and Micro Water Content with Optical Image Processing

Abstract

In this paper, the infrared absorption spectrum characteristics of H2O and HF are studied in detail. The subsequent experimental research is carried out at the wave number of 1392nm for H2O and 1278nm for HF. A spectral analysis system based on the FTIR infrared spectrometer is established to study the spectral absorption characteristics of H2O and HF with temperature and pressure. The TDLAS experimental system was built, and the preliminary experimental research on H2O and HF gas was carried out, which reached the detection limit of ppmv level. After determining research scheme, the project team, combined with TDLAS technology, designed four kinds of optical path tanks made of aluminum alloy, stainless steel, PTFE and PVDF for gas adsorption experiments. The analysis of the experimental results shows that there are differences in adsorption saturation time of optical path tanks made of different materials, but it does not affect the accuracy of measurement results. In practical application, the adsorption of H2O and HF gas by tank materials can not be considered. With the help of TracePro ray tracing software, the Herriott multiple reflection gas absorption cell is theoretically studied and simulated. The detection experiments of H2O and HF were carried out. The results show that when using TDLAS technology combined with 1392nm laser to detect H2O, the accuracy can reach 2 ℃; When using TDLAS technology combined with 1278nm QCL laser to detect HF, the detection limit can be less than 1ppmv. The results meet the requirements of project indicators. Considering the volume, cost, the anti-interference performance, the gas consumption, convenience of assembly and commissioning and wide application of later achievements, the project team finally designed and trial produced an optical gas absorption cell in the form of pure optical fiber for on-line detection of high-voltage equipment. At present, the project team has completed the trial production of key components of the prototype, such as optical path cell unit, laser driving unit, laser temperature control unit and digital processing unit. Fill the gap of H2O and HF live detection at home and abroad, improve and improve the evaluation means of SF6 Electrical equipment operation, and further effectively ensure the safe and stable operation of the equipment.