分时双光路校正法在线测量白酒酒精度

Determination of baijiu alcohol content based on time-sharing calibration of dual optical path

为满足生产应用中白酒酒精度的在线快速测量,设计了一种基于分时双光路校正的白酒酒精度测量装置。首先,分析白酒中主要成分乙醇和水的短波近红外吸收光谱的特征,考察光程、酒精含量对吸收光谱的影响,从而选择合适的波长和光程。随后,采用双光路分时测量的光路结构设计,修正光源变化引起的吸光度测量误差,并设计实验验证该装置的可靠性。研究结果表明,水分子在980nm处有一个独立的吸收峰,当光程增至40mm时,吸光度与酒精度的线性方程的相关系数(R~2)为0.9998,部分市售白酒的预测值与参考值的最大相对偏差小于0.4%,明显优于单光路测量的最大相对偏差4%。该装置可作为一种快速测量白酒酒精度的有效手段。

Firstly,the appropriate wavelength and optical distance are selected by analyzing the short-wave near-infrared absorption spectrum of ethanol and water,the main components of baijiu,and the influence of optical distance and alcohol content on the spectrum is investigated.Furthermore,the optical structure of time-sharing calibration of dual optical path is designed to correct the absorbance measurement error caused by light source change.The reliability of this device is tested though a series of customized experiments.The results show that water molecules have an independent absorption peak at 980nm.When the optical distance increases to 40mm,the correlation coefficient(R2)of the linear equation between absorbance and alcohol content is 0.9998.The maximum relative deviation between the predicted value and the reference value is less than 0.4%,which is obviously better than the maximum relative deviation of 4%measured by single optical path.This device can determine baijiu alcohol content rapidly.