Title: EXPERIMENTAL VERIFICATION OF DYNAMIC OPERATION OF CONTINUOUS AND MULTIVESSEL BATCH DISTILLATION COLUMNS
Abstract: Distillation is probably the most important unit operation in chemical industries for the separation of liquid mixtures into pure products. In a single batch distillation column, multicomponent mixtures can be separated into a number of product fractions, whereas in continuous distillation a sequence of columns is necessary to perform the same task. Batch distillation columns offer greater flexibility with respect to variations of feed mixtures, feed composition, relative volatilities and product specification. However, batch distillation columns in general require more energy input compared to a continuous distillation column. A newly developed batch distillation column, for the simultaneous separation of a multicomponent mixture might represent a process which combine the energy consumption of continuous distillation and the flexibility of conventional distillation. In recent years research on the dynamics of distillation column was focused on the development of models suitable for dynamic simulation of the composition dynamics. The purpose of research was on e.g. the selection of control structures. Few of these models were verified experimentally on distillation columns. A rigorous model based on first principles of a staged high purity continuous distillation column is presented and experiments are performed to verify the model. The importance of the tray hydraulics to obtain good agreement between simulation and experiment is demonstrated. Further, analytical expressions are derived for hydraulic time constants for the application in models with simplified liquid and vapor dynamics. Over the last centuries, chemical industries has more and more changed from conventional batch columns to continuous distillation columns, because of the lower energy demand. However, this trend is about to change especially in the production of fine chemicals or pharmaceuticals where batch distillation is recently becoming more important. The production of fine chemicals is characterized by small amounts of product and frequent changes with respect to feedstock and product specifications. With this renewed interest, investigations on the operation of batch distillation processes are needed or alternatively, new column configurations should be considered. The newly developed multivessel batch distillation column consists of a reboiler, intermediate vessels and a condenser vessel and provides a generalization of previously proposed batch distillation schemes. The total reflux operation of the multivessel batch distillation column was presented recently, a simple feedback control structure based on temperature measurements has been developed. The feasibility of this strategy is demonstrated by simulations and verified on a laboratory scale multivessel column. The experiments show very good agreement with the simulations, and confirm that the multivessel column can be easily operated with simple temperature controllers. A simple procedure to determine the setpoint of the temperature controller is presented and show that final product compositions are independent on the feed composition. The multivessel batch distillation column is compared to a conventional batch column, both operated under feedback control. It is found that the energy consumption for separation of a multicomponent mixtures into high purity product requires considerably less energy in a multivessel column compared to a conventional batch distillation column. Besides the reduction in energy consumption the much simpler operation of the new column is established.
Publication Year: 1999
Publication Date: 1999-01-01
Language: en
Type: article
Access and Citation
Cited By Count: 5
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot