二维流化床光反应器中的光强分布及波动规律

考察了外部平行光源照射下液-固及气-液-固二维流化床中流体流动状况对床层光强分布和波动规律的影响. 采用朗伯-比尔定律建立了两相及三相流化床中光强分布的数学模型，分析了液含率、气含率及气、固相吸光系数对床层光强分布的影响，并采用自制光纤光强传感器测定了床层中的光强分布和波动信号. 二维流化床中床层光强沿径向呈指数衰减，随着液含率和气含率增大而增大，理论计算与实验结果相吻合. 对光强波动信号的功率谱分析表明，液-固流化床中功率谱密度由低频至高频呈规律性衰减，气-液-固三相流化床中由于受气泡的影响功率谱密度出现起伏，在5~12 Hz处出现谱峰，与气泡的产生频率一致. 上述模型可推广应用于其他光源和不同结构流化床光反应器的数学描述.

Distribution and Fluctuation of the Light Intensity in Two-dimensional Fluidized Bed Photoreactors

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.