Abstract: The influence of activated carbon dispersed particles on the variation of bubble diameter and volumetric mass transfer coefficient of the system of CO₂-water absorption in ultrasonic field of a single frequency and multi-frequency was investigated in real time in a bubble column with a bubble feature measuring system called duplex conductivity probe.The results showed that multi-frequency ultrasonic field was superior to single-frequency ultrasonic field in enhancing volumetric mass transfer coefficient without dispersed activated carbon particles.Volumetric mass transfer coefficient increased by 40%-64% in the ultrasonic field of multi-frequency of 20-50-100 kHz and input power of 100 W.As activated carbon particles of 38 μm were added to the system,volumetric mass transfer coefficient firstly increased and then gradually decreased. However,the trend of variation in bubble diameter was on the contrary. Enhancement of mass transfer was most significant when solids content was 1.0 kg·m^-3.When solids concentration was at a specific value,volumetric mass transfer coefficient decreased with the increase in activated carbon particle diameter.Compared with the system without activated carbon particles,when solids content was 1.0 kg·m^-3,volumetric mass transfer coefficient was enhanced about by 1.58 times,and volumetric mass transfer coefficient further increased by 2.02 times under combined action of particles and reverberating ultrasonic field of multi-frequency of 20-50-100 kHz and input power 100 W,which suggested that multi-frequency ultrasonic field and dispersed particles had a significant synergistic effect on enhancement of mass transfer in CO₂-water absorption system.

Key words: bubble column, ultrasonic field, particle, bubble Sauter diameter, volumetric mass transfer coefficient

摘要： 用双电导探针气泡特征参数测量系统实时测定超声场与分散颗粒(活性炭)对鼓泡塔水+CO₂体系气泡Sauter直径和体积传质系数影响的变化规律。实验结果表明:无活性炭颗粒添加时,多频超声场比单频超声场更有利于提高体积传质系数,输入功率为100 W、组合超声频率为20-50-100 kHz时,体积传质系数增幅达40%~64%;加入活性炭颗粒后,体积传质系数随加入活性炭固含量的增大呈现先增大后逐渐减少的趋势,气泡Sauter直径变化规律相反,当体系中活性炭固含量为1.0 kg·m^-3时,传质增强最明显。体积传质系数随加入活性炭粒径的减小呈现增大的趋势。与无活性炭颗粒(d_s=0)比较,活性炭(固含率1.0 kg·m^-3)粒径d_s=38 μm时,液相体积传质系数在扣除吸附传质效果后仍增大1.58倍,同时引入超声场后,当组合超声频率为20-50-100 kHz,超声功率100 W时,液相体积传质系数增大2.02倍,可见超声场和分散颗粒对气液传质有显著的协同强化作用。

关键词: 鼓泡塔, 超声场, 颗粒, 气泡Sauter直径, 体积传质系数