紫外差分吸收光谱法定量分析SF_6分解物SO_2和H_2S技术

Quantitative Detection of SO_2 and H_2S from SF_6 Decomposition Mixed Gases Based on UV Absorption Spectrometry

分解物SO_2和H_2S表征SF_6电气设备内部缺陷,是SF_6电气设备试验必检项,对两种气体的准确定量分析直接关系到SF_6电气设备内部缺陷种类和定位的正确判断。现有的现场检测技术不足以解决气体组分之间的干扰问题,因此,本文开展了相关选型和设计工作,获得基于紫外差分吸收光谱法的SO_2和H_2S混合气体检测装置。采用差分法提取SO_2和H_2S紫外吸收光谱的快变部分,通过吸光度的扣减和浓度反演,去除在紫外吸收光谱区域H_2S和SO_2的交叉干扰问题。对其测试的原始谱图进行数字滤波处理,去噪后获得平滑波形,进一步进行FFT变换和线性拟合,拟合优度达到0.999 9,提高了SF_6背景气体中SO_2和H_2S混合气体检测的灵敏度。所研制装置在系统信噪比为1时,混合气体中SO_2在190～230 nm和280～320 nm波段的检测极限分别为0.108μL/L和0.444μL/L,H_2S在190～230 nm波段检测极限为0.490μL/L,为现场检测应用奠定了基础。

The decomposition products SO2 and H 2S characterize the internal defects of SF 6 electrical equipment and they are also mandatory inspection items for testing of SF6 electrical equipment.Accurate quantitative analyses of these two gases are directly related to the correct judgment of the defect type judgment and defect location within the SF6 electrical equipment.The existing detection technology is not sufficient to solve the problem of interference between gas components.Therefore,related selection and design work have been carried out in this paper.A SO2 and H 2S mixed gas detection device based on ultraviolet differential absorption spectroscopy has been obtained.Differential methods are used to extract the fast-changing part of the UV absorption spectra of SO2 and H2S,and remove the intersection problem between SO2 and H 2S in the UV-absorbing spectral region by absorbance deduction and concentration inversion.The original spectrum is processed by digital filtering,a smooth waveform is obtained after denoising,and further FFT transformation and linear fitting are carried out.The result of the goodness of fit is 0.999 9,proving that the detection sensitivity of SO2 and H 2S mixed gases in background gas SF 6 has been improved.Using this device,when the signal-to-noise ratio of system is 1,the detection limit of SO2 in the mixed gas at 190 nm to 230nm is 0.108μL/L,and 280 nm to 320 nm is 0.444μL/L,the detection limit of H2S at 190 nm to 230 nm is 0.490μL/L,which lays the foundation for on-site inspection applications.