The time consumed in starting up the distillation unit with appreciable holdups can be an important fraction of the total distillation time,particular for catalytic distillation systems with large holdups.To optimize ...The time consumed in starting up the distillation unit with appreciable holdups can be an important fraction of the total distillation time,particular for catalytic distillation systems with large holdups.To optimize the whole process,the start-up period has to be considered as a part of the complete catalytic distillation process.In this paper,BP artificial neural network model was presented as a tool to estimate the start-up process for a given catalytic distillation system.It can been seen that through the examination of the case studied in this work,a good start-up policy can reduce both the energy and time requirements in the start-up phase of catalytic distillation processes.The results based on 20 start-up policies showed that the time consumed in start-up period with an average error of 4.140% and a maximum error of 10.291% for the case studied in this work.The accuracy of the model will depend upon the data available and the type of model.展开更多
The batch extractive distillation (BED) process has the advantages of both batch and extractive distillation. It is one of the most promising means for the separation of azeotropic and close-boiling point systems. How...The batch extractive distillation (BED) process has the advantages of both batch and extractive distillation. It is one of the most promising means for the separation of azeotropic and close-boiling point systems. However, so far this process has not been applied in industry due to its over-complexity. A new shortcut model was proposed to simulate the operation of the batch extractive distillation operations. This algorithm is based on the assumption that the batch extractive distillation column can be considered as a continuous extractive distillation column with changing feed at any time. Namely, the whole batch process is simulated as a succession of a finite number of steady states of short duration, in which holdup is considered as constant mole. For each period of time the batch extractive distillation process is solved through the algorithm for continuous extractive distillation. Finally, the practical implementation of the shortcut model is discussed and data from the laboratory and literature are presented. It is found that this model has better adaptability, more satisfactory accuracy and less calculative load than previous rigorous model. Hence the algorithm for simulating BED is verified.展开更多
文摘The time consumed in starting up the distillation unit with appreciable holdups can be an important fraction of the total distillation time,particular for catalytic distillation systems with large holdups.To optimize the whole process,the start-up period has to be considered as a part of the complete catalytic distillation process.In this paper,BP artificial neural network model was presented as a tool to estimate the start-up process for a given catalytic distillation system.It can been seen that through the examination of the case studied in this work,a good start-up policy can reduce both the energy and time requirements in the start-up phase of catalytic distillation processes.The results based on 20 start-up policies showed that the time consumed in start-up period with an average error of 4.140% and a maximum error of 10.291% for the case studied in this work.The accuracy of the model will depend upon the data available and the type of model.
基金Supported by National Development and Reform Commission (2005 No1899)
文摘The batch extractive distillation (BED) process has the advantages of both batch and extractive distillation. It is one of the most promising means for the separation of azeotropic and close-boiling point systems. However, so far this process has not been applied in industry due to its over-complexity. A new shortcut model was proposed to simulate the operation of the batch extractive distillation operations. This algorithm is based on the assumption that the batch extractive distillation column can be considered as a continuous extractive distillation column with changing feed at any time. Namely, the whole batch process is simulated as a succession of a finite number of steady states of short duration, in which holdup is considered as constant mole. For each period of time the batch extractive distillation process is solved through the algorithm for continuous extractive distillation. Finally, the practical implementation of the shortcut model is discussed and data from the laboratory and literature are presented. It is found that this model has better adaptability, more satisfactory accuracy and less calculative load than previous rigorous model. Hence the algorithm for simulating BED is verified.
