19-08-2014, 10:16 AM
Chromatography is one of the important separation technique in the realms of biotechnology. In general, the preparative scale chromatographic operations are carried out in packed and expanded bed mode. Despite the advantages, adsorptive separations carried out on expanded bed or packed bed have a disadvantage that they are all batch operations (in terms of solid phase) and require large inventory of adsorbent for the process. To facilitate efficient contact between solid and liquid there is a need to design equipment which works continuously and be economical.
Chromatography is one of the important separation technique in the realms of biotechnology. In general, the preparative scale chromatographic operations are carried out in packed and expanded bed mode. Despite the advantages, adsorptive separations carried out on expanded bed or packed bed have a disadvantage that they are all batch operations (in terms of solid phase) and require large inventory of adsorbent for the process. To facilitate efficient contact between solid and liquid there is a need to design equipment which works continuously and be economical. Moving beds are emerging as solution to this. A Liquid Solid Circulating Fluidized Bed (LSCFB) has been used in processes for continuous recovery of ions of interest. But in LSCFB desorption or elution is carried out in co-current mode, resulting in reduced process efficiency and for steady state operation the system requires stringent control of pressure balance. So an attempt is made to overcome its limitations by designing a Multistage Continuous Countercurrent Contactor, wherein at every stage countercurrent contact of solid and liquid is carried out. The present work includes erection and hydrodynamic study of preparative scale Multistage Fluidized Moving Bed system (FMB). A tracer study was carried out using 1 M NaCl to elucidate the origin of possible flow instabilities. Effects of primary and auxiliary liquid flow rate on bed expansion and solid circulation rate were studied. Operating range of the current system was found to be 96 to 295 ml/min in terms of solid circulation rate and feed rate was limited by required expansion in the contacting zone. Expansion studies were carried out in different diameter columns (i.e.2.5cm, 5cm, 10.5cm, 22.5cm and 30 cm) and results are matching well with Richardson–Zhaki index. Performance of the system is studied by comparing Copper sulphate as a model solute on ion exchange resins in packed bed, expanded bed and in Fluidized Moving Bed.