水力喷射-空气旋流器中气液传质特性及其机理

Mass transfer characteristics and mechanism in a water-sparged aerocyclone

对一种新型高效的气液传质设备——水力喷射-空气旋流器(WSA)的传质机理进行了研究。分别采用化学吸收法(CO2-空气-NaOH体系)和物理吸收法(CO2-空气-H2O体系)测定了不同进口气速、不同液体喷射速度下的有效相界面积a和液膜传质系数kL,并由此得到体积传质系数kL a。结果表明,由于WSA中气液间的强交互作用,a、kL以及kL a均随进口气速和液体喷射速度增大而增大。采用量纲分析法对实验数据进行了归纳,拟合出了a、kL和kL a随气相Reynolds数Reg、液相Weber数WeL之间的经验公式:a=0.0024Re1.25g We0.079L,ShL=35.31Re0.2303g We0.13L,kL a=6.52×10-8 Re1.48g We0.21L,这些关联式能较好地预测WSA的传质性能。研究还表明,在WSA中的气液射-旋流传质体系中,传质过程符合双膜理论、表面更新理论和溶质渗透理论,但以表面更新机理为主。

Water-sparged aerocyclone （WSA） is a new type of gas-liquid mass transfer equipment with high efficiency, the mass transfer mechanism in WSA was investigated in this paper. The interracial area （a） was determined by the chemical reaction method with CO2-NaOH solution system, and the liquid mass transfer coefficient （ku） was measured by the physical absorption method with CO2-H20 system. The a, kL and kLa increase with gas inlet velocity （Ug） and liquid jet velocity （UL） because of the gas-liquid intense interaction in WSA. The empirical formulae were developed for a, kL and kLa, i. e, a= 1.2 0.79 WeL kLa= 6. 52 X 1,,-8 n .8.. 0. zl 0.0024Reg WeE SHE=35.31Re2a3 o. 13 , , iv Keg weE , which fit the experimental data well and could be well used to predict the mass transfer characteristics in WSA. The mass transfer models of Whitman＇ double film theory, Higbie＇ penetration theory and Danckwerts＇ surface renewal theory can be well used to interpret the mass transfer mechanism of gas-liquid jet-aerocyclone system in WSA, and the surface renewal theory is the primary mass transfer mechanism.