基于激光光谱法的尿素水溶液液膜多参数测量

摘要

在选择性催化还原（SCR）系统中，对尿素水溶液液膜多个参数（厚度、浓度及温度）进行高精度的定量分析，对减少液膜形成、提高SCR系统的催化反应效率、降低NOx对环境的污染至关重要。基于比尔-朗伯定律，通过结合1420 nm和1488 nm两个波长的半导体激光器，提出一种恒温度条件下尿素水溶液液膜厚度和浓度同步测量，以及恒浓度条件下尿素水溶液液膜厚度和温度同步测量的新方法。并在此基础上，利用标准具验证了该方法的测量精度。结果表明恒温度条件下，该方法同步测量尿素水溶液液膜厚度和浓度的平均测量误差分别为0.82%和3.93%；恒浓度条件下，同步测量尿素水溶液液膜厚度和温度的平均测量误差分别为0.79%和2.58%。%In selective catalytic reduction (SCR) system, quantitative analysis of multi-parameter of liquid film (film thickness, temperature and mass fraction) for urea-water-solutions is crucial to control the formation of liquid film, improve the efficiency of SCR system and reduce the NOx emissions. A new method based on Beer-Lambert law was developed to simultaneously measure the thickness and mass fraction of liquid film for urea-water-solutions at constant temperature, and the thickness and temperature at constant mass fraction by combining two different wavelengths, 1420 nm and 1488 nm, respectively. Furthermore, measurement accuracy of this method was validated by a calibration tool which provided liquid film with known film thickness, temperature and mass fraction, respectively. It was found that the averaged deviation of film thickness and mass fraction measured simultaneously at constant temperature was 0.82% and 3.93%, respectively. It also revealed that the mean deviation of film thickness and temperature measured simultaneously at constant mass fraction was 0.79%and 2.58%, respectively.