【作者】 高习群；

【导师】 马友光；

【作者基本信息】 天津大学 ， 化学工程， 2008， 博士

【摘要】 气液传质在化工过程中普遍存在,由于目前的研究大多局限于宏观的表面现象,尚难揭示其内在的传质特性及传质机理。现有的经典传质理论均是在经验或半经验基础上发展起来的,无法从微观上揭示相际传质机理,因而只适用于某些特定的情况,局限性较大。因此,从微观上进一步深入研究气液传质过程,建立精确的以界面非平衡机理为基础的非线性传质模型是非常必要的。本文利用实时激光全息干涉系统,结合显微放大技术,对不同主体流速下甲醇-CO₂、乙醇-CO₂、正丙醇-CO₂、正丁醇-CO₂气液传质过程及不同浓度十二烷基硫酸钠（SDS）、十二烷基苯磺酸钠（SDBS）、十六烷基三甲基溴化铵（CTAB）、聚丙烯酸（PAA）四种表面活性剂对乙醇-CO₂传质过程的影响进行了研究。得到了气液界面附近液相侧的浓度场分布及界面浓度、浓度边界层厚度。对于气体吸收过程,以分子热力学为基础,结合普遍化的化学势推动力通量方程,提出界面非平衡理论,推导出传质存在时两相界面处的浓度关系,并对静止和运动气泡两种情况分别进行了求解。针对气体组分被吸收进入静态小液滴的传质过程,分别采用平衡模型和非平衡模型对具有较低溶解度的物理吸收过程进行了分析,并对吸收过程中不同时间液滴内的浓度分布进行了求解。另外以对流扩散方程为基础,考虑了界面阻力对传质的影响,得到气泡周围近界面附近的浓度场分布模型,模型计算值和实验值进行了比较,结果吻合较好。气液两相传质强化是化工过程研究的一个重要内容,在恒温反应釜内,对CO₂在不同搅拌速率下、不同浓度活性炭-水浆料体系中的吸收强化进行了实验研究,计算得到不同情况下的增强因子。基于膜模型和界面非平衡原理,提出了一个新的预测增强因子的模型,能很好地解释粒子浓度及搅拌强度对增强因子的影响,并且模型预测值与实验值吻合良好。更多还原

【Abstract】 Gas-liquid mass transfer is often encountered in chemical engineering process. However, up to now, most researches in the field are based on macro phenomenon. The classic mass transfer theories and hypothesis are developed on the basis of some empirical and semi-empirical correlations. Therefore, the inherent mass transfer characteristic and mechanism have not yet been well known. It is of virtual significance to deeply investigate the micro mechanism of interfacial mass transfer and develop accuracy non-linear mass transfer pattern taking into account the interfacial non-equilibrium principle.The mass transfer process of methanol-CO2, ethanol-CO2, n-propanol- CO2, n-butanol-CO2 and influence of various concentrations sodium dodecyl sulfate （SDS）, sodium dodecyl benzene sulfonate （SDBS）, cetyl trimethyl ammonium bromide （CTAB）, polyacrylic acid （PAA） on mass transfer at different body velocities were studied respectively using micro holographic interferometer, and the concentration distribution near the interface, interfacial concentration and concentration boundary layer thickness on liquid side were determined.On the basis of molecule thermodynamics, combining the general chemical potential driving force equation of mass transfer flux, the non-equilibrium principle at the interface was proposed and a concentration correlation between two phases at the interface is derived and solved under both quiescent and mobile conditions in the absorption processes of bubble,respectively, good agreements have been achieved between the calculated data and experimental data. For the absorption process of gaseous species into stationary droplets, equilibrium relation and non-equilibrium relations at the interface were used to analyze and predict the absorption time for a physical absorption at a relatively low solubility of gas, and the concentration distribution within the droplet at different times is solved. In addition, based on convection-diffusion equation, considering the effect of interfacial resistance on mass transfer, concentration field near the interface around bubble in liquid phase was solved, and the results were at good agreement with the experimental data.The enhancement of gas-liquid mass transfer is very important in the intensification of chemical engineering process. CO₂ absorption in the slurries containing different concentration activated carbon particles and water at various stirrer speeds were studied experimentally in a thermostatic reactor, and the enhancement factors were determined. A quantitative model for predicting enhancement factor was proposed based on film model and non-equilibrium principle, which could well explain the effect of particles concentration and stirring intensity on enhancement factor, and the prediction value of present model are at considerable agreement with experimental data.更多还原