Varicol Process Research Articles

Multiobjective optimization of simulated moving bed and Varicol processes using a genetic algorithm

The size of the packing material, the total number of columns and the total feed concentration have significant impacts on the economics of a preparative chromatographic separation, through their effects on column pressure drop, column efficiency and thermodynamics. In this work, the role of these parameters on the performances of a simulated moving bed and a Varicol process is investigated on a chiral separation system from literature, using an equilibrium stage model. A multiple objective optimization technique based on a genetic algorithm is adopted, which allows to maximize simultaneously the purity of the extract and productivity of the unit. In this way, it is possible to optimize and compare the performances of both processes in a wide range of parameter values, so as to assess their relative potential under equally optimized conditions. The optimization results, i.e. the so-called Pareto sets, have been discussed in the frame of equilibrium theory and the roles of these three parameters have been clarified.

Multiobjective optimization of SMB and varicol process for chiral separation

AbstractThe multiobjective optimization of continuous countercurrent chromatography separation units, such as simulated moving bed (SMB) and Varicol, is considered. The Varicol system is based on a nonsynchronous shift of the inlet and outlet ports instead of the synchronous one used in the SMB technology. The optimization problem is complicated by the relative large number of decision variables, including continuous variables, such as flow rates and lengths, as well as discontinuous ones, such as column number and configuration. It is also important to reformulate the optimization problem as multiobjective, since the factors affecting the cost of a given separation process are multiple and often in conflict with each other. A typical example is simultaneous maximization of the productivity of the process and the purity of the corresponding products. A new optimization procedure based on a genetic algorithm allows handling these complex optimization problems. An existing literature chiral separation model was used to illustrate the potential of this optimization procedure. This work also offered a unique opportunity to compare the optimal separation performance achievable with the SMB and Varicol technologies.

Optimal Operation of Continuous Chromatographic Processes: Mathematical Optimization of the VARICOL Process

Continuous chromatographic processes have gained a lot of attention due to the increasing use as a preparative separation step for life science products. The simulated moving bed (SMB) process is a well-known example. A new multicolumn continuous chromatographic process was recently introduced as the VARICOL process [Ludemann-Hombourger, O. et al. The “VARICOL” Process: A New Multicolumn Continuous Chromatographic Process. Sep. Sci. Technol. 2000, 35(12), 1829]. Although in SMB chromatography a continuous operation is realized by periodic and simultaneous shifting of all inlet and outlet ports, VARICOL uses individual movements of the ports resulting in a more efficient use of the expensive adsorbent. This paper presents a more general definition of the VARICOL process than given previously. For this flexible process description, an optimization strategy for determining optimal operating parameters is presented. Based on a detailed mathematical process model, optimal operating conditions are computed for...

Application of the “VARI COL” process to the separation of the isomers of the SB-553261 racemate

A new continuous chromatographic process (VARI COL) has been presented recently. The basic principle of the new VARI COL process consists of an asynchronous shift of the inlet/outlet lines in a multi-column system on a recycle loop. This process has been used to perform the separation of the optical isomers of the SB-553261 racemate. In this paper, we illustrate that for this specific separation, the VARI COL process is more efficient than the well-known SMB process.

The “VARICOL” Process: A New Multicolumn Continuous Chromatographic Process

A new continuous chromatographic process is presented. This is in contrast to the known simulated moving bed (SMB) process which employs a synchronous shift of inlet/outlet lines. The basic principle of the new VARICOL process is based on a non-synchronous shift of the inlet/outlet valves in a multicolumn system. A numerical example compares the performances of the new VARICOL process to the well-known SMB process. This study shows that the VARICOL performances can be better than those of the SMB process. For example, a 5-columns VARICOL permits the same purities to be reached as a 6-columns SMB with the same productivity. Interest in the process is also validated experimentally. Both SMB and VARICOL are optimized to reach the highest achievable productivity for given outlet purities. The productivity of a 5-columns system can be improved 18.5% by using the VARICOL process.