Control of a train of high purity distillation columns for efficient production of 13C isotopes

It is well-known that high-purity distillation columns are difficult to control due to their ill-conditioned and strongly nonlinear behaviour. The fact that these processes are operated over a wide range of feed compositions and flow rates makes the control design even more challenging. This paper proposes the most suitable control strategies applicable to a series of cascaded distillation column processes. The conditions for control and input-output relations are discusssed in view of the global control strategy. The increase in complexity with increased number of series cascaded distillation column processes is tackled. Uncertainty in the model parameters is discussed with respect to the dynamics of the global train distillation process. The main outcome of this work is insight into the possible control methodologies for this particular class of distillation processes

Optimization of 13C enrichment by carbon monoxide cryogenic distillation

The main purpose of this study is the optimization of the operating mode for cryogenic distillation columns that provide an isotopic enrichment in stable isotopes. The analysis is based on an experimental cycle for 13C enrichment by CO cryogenic distillation conducted in semi-batch mode in the column of the National Institute for Research and Development of Isotopic and Molecular Technologies. The experimental run is reproduced closely using the simulation software ProSim-BatchColumn, applied for the first time to this type of separations. It is, then, used to investigate the dynamics of the process and the effect of the feed flowrate on the separation to be achieved. As a result, an optimized cycle is proposed, which allows reaching the desired specifications in around one-third the time. The obtained results are interesting and can be applied to all the mixtures where heavy components have a higher commercial value than the light ones