关键词: 二维流化床, 光反应器, 光强分布, 光强波动, 功率谱分析

Abstract: The distribution and fluctuation of the light intensity in a liquid-solid and three-phase fluidized bed are influenced by the fluid flow under the illumination of external parallel light. The mathematical models of the light intensity distribution in liquid-solid and three-phase flat fluidized beds are established based on the Lambert-Beer law. The light intensity is attenuated along the lateral distance in the fluidized bed and the influence of the gas holdup, liquid holdup, the specific absorbance of gas and solid on the distribution of light intensity is analyzed. The light intensity signals are measured using a fiber sensor made in our laboratory and the calculation of the model is consistent with experimental results. The analysis about the fluctuating signals shows that the PSD (power spectral density) is attenuated regularly from the low frequency to the high frequency in the liquid-solid fluidized bed, the PSD undulates because of the bubbles in the three phase fluidized bed and the peaks occur at 5~12 Hz, which is coincident with the frequency of bubbles. The model can be easily extended to other light sources and other types of fluidized bed photoreactor.

Key words: flat fluidized bed, photoreactor, light intensity distribution, light intensity fluctuation, power spectral analysis