【作者】 谭琳；

【导师】 刘明言；

【作者基本信息】 天津大学 ， 制药工程， 2009， 硕士

【摘要】 气液固循环流化床作为一种新型的吸附分离装置,具有操作连续化、传质速度快和液固相接触充分等优点,拥有广泛的应用前景。本文提出并初步开展大孔树脂气液固循环流化床分离银杏黄酮的研究,旨在创立大孔树脂气液固循环流化床分离中药及天然药物的新技术及其理论基础。本文首先考察了气相对大孔树脂液固循环流化床吸附银杏黄酮规律的影响。研究结果表明,气相的加入可提高大孔树脂对银杏黄酮的吸附和脱附效果,均优于此条件下的液固循环流化床。气液固循环流化床系统的吸附和脱附效率随大孔树脂颗粒直径及下行床料液流速的增加而降低,随着料液浓度的降低而提高。在单因素考察的基础上,本文进行了大孔树脂气液固循环流化床吸附银杏黄酮的四因素三水平正交实验,并获得了最佳实验条件。为了研究液、固相流动特性对传质过程的影响,本文考察了气液固循环流化床液、固相的扩散特性。结果表明,采用0.6-0.9mm直径的树脂颗粒时,下行床液相轴向扩散系数Daxl在6.320×10-5 - 9.427×10-5m2/s之间,上行床Daxl在1.207×10-3 - 2.414×10-3m2/s之间;随着上、下行床表观气速的增大,上、下行床的Pe准数均减小,Daxl均增大,即表观气速的增大加剧了气液固循环流化床的液相返混,使其更加偏离平推流。当增大颗粒直径时,上行床液相返混加剧,下行床液相返混减弱。上行床固相扩散系数为1.254×10-3m2/s,下行床的固相扩散系数在5.892×10-4 - 9.348×10-4m2/s之间,固含率的增加可减弱下行床的返混程度。对大孔树脂吸附银杏黄酮的动力学进行研究的结果表明,吸附过程由液膜扩散和颗粒内扩散共同控制,但随着粒径的降低,液膜扩散控制逐渐加强而颗粒内扩散控制减弱,同时搅拌速度的增加可以提高传质速率,表明加强扰动对吸附过程具有促进作用。最后,在上述研究结果的基础上,建立了气液固循环流化床下行床吸附和上行床脱附的传质模型。模型计算值与试验结果吻合较好,能够较好地预测床体的吸附和脱附过程。更多还原

【Abstract】 As a novel separation facility for adsorption process, gas-liquid-solid circulating fluidized bed (GLSCFB) has extensive application prospect for its continuous operation, fast mass transfer and well contact between liquid-solid phases. The adsorption of ginkgo flavonoids by macroporous resin GLSCFB was proposed and investigated in the paper to establish a potential method and theoretical basis for the separation of traditional chinese medicine and natural drugs using GLSCFB.First of all, the effect of gas phase on the adsorption of ginkgo flavonoids by liquid-solid circulating fluidized bed (LSCFB ) was investigated. Result revealed that adsorption and desorption efficiency of ginkgo flavonoids were improved as gas phase was pumped into GLSCFB and superior to LSCFB. Investigation on the factors influencing the adsorption of GLSCFB indicated that it was preferable for GLSCFB adsorption and desorption with smaller particle size, lower feed velocity and dilute ginkgo flavonoids concentration. Based on the single factor research, the optimum experimental conditions were obtained from the results of the orthogonal test of four factors at three different levels.Then, the dispersion characteristics of liquid and solid phases in GLSCFB were studied. When the diameter of resin particles was 0.6-0.9mm, the liquid axial dispersion coefficient (Daxl) of downcomer was between 6.320×10-5 and 9.427×10-5m2/s, the Daxl of riser was between 1.207×10-3 and 2.414×10-3 m2/s. With the increasing of gas velocity, the value of Peclet number reduced and Daxl increased which indicated that liquid backmixing was intensified and the flow pattern deviated further from plug flow reactor as gas velocity increased. With increasing particles diameter, the liquid backmixing in riser was enhanced, but in downcomer it was weakened. The axial dispersion coefficients of solid phase (Daxs) in the riser was 1.254×10-3 m2/s,Daxs in the downcomer was between 5.892×10-4-9.348×10-4 m2/s,the increasing of solids holdup could reduce the solid backmixing in downcomer.Investigation on the adsorption kinetics of macroporous resin indicated that adsorption process of ginkgo flavonoids was controlled by film diffusion and intra-pore diffusion, but the film diffusion control become stronger as the particle diameter decreased. Higher stirring speed could increase mass transfer rate demonstrated that disturbance is beneficial for adsorption.Finally, the adsorption model of downer and desorption model of riser were developed. Both models could predict adsorption and desorption process well. And the experimental data were inosculated to the calculated values.更多还原