【作者】 宋爽；

【导师】 白鹏；

【作者基本信息】 天津大学 ， 制药工程， 2010， 博士

【摘要】 本文提出了无塔顶回流罐的全回流-全采出循环全回流间歇精馏的操作方式,模拟和实验验证了无回流全采出操作期间塔顶浓度平台的存在。提出了增加塔中存液罐强化过渡馏分采出的新操作方法并采用甲醇-乙醇-正丙醇三元物系进行了分离过程。建立了具有塔中存液罐过渡馏分操作过程的数学模型。针对新型操作方式提出了多点测温三温控制策略。本文以理论塔板辅助法进行参数设定,结合系统辨识及预测控制理论构建循环全回流间歇精馏的自动化和在线优化平台,并通过数学模拟及实验研究对提出的三温控制策略进行可行性研究。首先,对无回流罐循环全回流间歇精馏过程的基础—全采出过程进行了实验研究和模拟研究,分别讨论了不同的精馏塔参数对于精馏全采出过程的影响,验证了作为全回流-全采出式循环全回流间歇精馏操作的理论基础的塔顶浓度平台的存在;然后,对加有中间储罐的循环全回流间歇精馏用于过渡馏分采出阶段进行了研究,讨论了中间储罐的充、放液操作对塔顶轻组分的变化和对塔釜重组分上升的影响,并建立了新型操作方式的数学模型。在上述研究的基础上提出了理论板辅助法的三温控制方法。该方法采用RBF径向神经网络进行温度系统辨识,通过扩展卡尔曼滤波(EKF)进行时变系统的温度推算和精馏塔浓度预测估计,采用模糊神经网络控制算法FNNC设计控制系统,对系统的采出与回流过程加以控制,形成一个闭环控制系统,达到在线控制间歇精馏全采出-全回流切换过程的目的。最后,建立了带有中间回流罐的全回流间歇精馏三温控制的实验装置,应用本文提出的新型操作及控制方式实现了对甲醇-乙醇-正丙醇三元物系的分离,控制过程有较好的鲁棒性,与恒回流操作方式相比,产品的产量提高了26.2%,过渡馏分采出时间缩短了53.4%,精馏塔利用率提高了66.2%。对于循环全回流三元物系间歇精馏过程,加有塔中回流罐的三温控制方式明显优于传统的固定回流比控制,证明了控制方法的可行性。更多还原

【Abstract】 The operation mode of cyclic total reflux batch distillation in the way of total reflux-total withdrawal without reflux drum was proposed in this paper. The existence of the concentration platform of the top of the column during the total withdrawal period was proven by simulation and experiment. A middle tank which improves the slop cut operation was set up. The new operation mode was applied in separation of the ternary mixture: methanol-ethanol-propanol system. The mathematical model for the slop cut operation process with a middle tank was set up. A control policy based on the multi-temperature measured and tri-temperature controlled was proposed according to the new operation mode. Combined with the system identification and predictive control theory, the automatic control and on-line optimization platform was developed for the cyclic total reflux batch distillation. The operational parameters were set with the assistance of the theoretical plate method, and furthermore, the feasibility of the tri-temperature control policy was validated by the mathematical simulation and experiments in the paper.First, total withdrawal process which is the principle basis of the no-reflux-drum cyclic total reflux batch distillation process was studied computationally and experimentally. The effect of different column parameters on total withdrawal process was discussed respectively. The existence of the concentration platform at the top of the column, which acts as the theoretical basis of total reflux-total withdrawal cyclic batch distillation, was proven. Then, the withdrawal of slop cut of the cycle total reflux batch distillation with an additional middle tank was studied. The effect of filling and dumping of the liquid in middle tank on the change of the top concentration of light component and the rising of the heavy component in still was discussed. Furthermore, the mathematic model of the process of the new operation mode was set up.Based on the above research, tri-temperature control strategy assisted by the theoretical plate method was proposed. RBF (Radial Basis Function) neutral network was adopted to carry out the temperature system identification, and EKF (Extended Kalman Filter) was adopted to estimate the temperature in the time-varying system and predict the concentration variation in the column. In order to realize the on-line control of the switch between total-reflux and total-withdrawal, a closed loop control system based on FNNC (Fuzzy Neural Network Control) method was formed by the control of the withdrawal and reflux process.Finally, the experimental apparatus with tri-temperature controlled cyclic total reflux batch distillation with middle tank was set up. The separation of the ternary mixture methanol-ethanol-propanol was carried out in the new operation mode and control method proposed by the paper. During the process the control performance showed good robustness. Compared with the constant reflux operation, the product amount was increased by 26.2%, and the operation time for slop cut withdrawal was decreased by 53.4%, the efficiency of the distillation column was increased by 66.2%. Therefore in the separation of ternary mixture, the tri-temperature controlled cyclic total reflux batch distillation with middle tank is obviously advantageous over the conventional constant reflux control policy. And the feasibility of this control policy was verified.更多还原