Dynamic response to process disturbances-A comparison between TMB/SMB models in transient regime

- Evaluation of the equivalence between TMB/SMB models under dynamic regime.
- The orthogonalization method was used to identify the processes variables with greatest influence in the SMB units responses.
- Under certain conditions the TMB-SMB equivalence is not valid.
- In some cases, the transient behaviour of the four columns SMB can resemble more the TMB than the eight columns SMB.

The modelling and design of Simulated moving bed (SMB) processes is normally done using the True moving bed (TMB) approximation. Several studies show that average values obtained at cyclic steady state for SMB units approach the TMB unit at steady state and that this approach is better as the number of columns in the SMB increases. However, studies that evaluate this equivalence under dynamic conditions are scarce. The objective of this work is to perform an analysis of the transient behaviour of two SMB units, with four and eight columns, and compare the results with the ones obtained for a TMB unit. An analysis of the impact of operating variables on the processes performance parameters is performed. The results show that TMB/SMB equivalence is valid only for conditions that do not violate the regeneration/separation regions and that the transient behaviour of the four columns SMB can resemble more the TMB.