基于特征波长积分吸收光谱法的H2S体积分数监测

H2S Volume Fraction Monitoring Based on Characteristic Wavelength-Integrated Absorption Spectroscopy

通过厌氧消化产生清洁燃气是目前处理餐厨垃圾的主要手段之一。由于餐厨垃圾中含有硫元素,厌氧消化过程中会不可避免地产生H2S气体。H2S不仅会腐蚀管路还会污染环境,因此对其体积分数进行在线测量具有重要意义。传统的H2S体积分数测量方法如亚甲基蓝分光光度法、碘量法和电化学法等具有操作复杂、测量速度慢、易受其他气体干扰等缺点,无法用于指导脱硫系统工况及时调整。将紫外吸收光谱法和连续波长积分法相结合用于H2S体积分数的在线测量,选择210~230 nm波段作为特征波段,得到吸收光谱积分特征值与H2S体积分数之间的线性关系,其拟合度大于0.999。对实验室配制200×10^(-6)~1200×10^(-6)范围的H2S标气进行体积分数测量,测量值的最大误差为3.1%,结果表明,该技术能够应用于沼气中H2S体积分数的准确监测。最后将测量仪器应用于餐厨垃圾厌氧消化工程并进行现场测试,结果表明,该仪器能够较准确地监测厌氧消化过程中沼气中的H2S体积分数变化。

At present,producing clean gas through anaerobic digestion is one of the main means to treat food waste.As food waste contains sulfur,H2S gas will inevitably be generated during anaerobic digestion.H2S gas is inevitably generated during anaerobic digestion due to the presence of sulfur in food wastes.The produced H2S can lead to corrosion in pipelines and environmental pollution.Thus,it is essential to measure its volume fraction online.Traditional H2S volume fraction measurement methods,such as methylene blue spectrophotometry,iodometry,and electrochemical methods,involve complex operation,slow measurement speed,and can easily be affected by other gases.In addition,these methods cannot be used to guide the timely adjustment of the working conditions of the desulfurization system.Therefore,we develope an approach combined the ultraviolet absorption spectroscopy and continuous wavelength integration method for the online measurement of H2S volume fraction.The linear relationship between the characteristic value of the absorption spectrum integration and H2S volume fraction is obtained by selecting a 210‒230 nm band as the characteristic band,with a fitting degree>0.999.To measure the volume fraction of H2S,we prepare 200×10^(-6)‒1200×10^(-6) of H2S standard gas in a laboratory,and the maximum error of the measured value is 3.1%.Finally,the measurement device is applied to the anaerobic digestion of kitchen wastes,and the field test is conducted.The results demonstrate that the instrument can accurately monitor the change in H2S volume fraction of biogas during the anaerobic digestion process.