Page 258 - Chiral Separation Techniques

236 9 Modeling and Simulation in SMB for Chiral Purification

Table 9-4. SMB operating conditions and model parameters for the reference case.

SMB operation conditions: Model parameters:
Feed concentration: 2.9 g/l each Solid/fluid volumes, (1 – ε)/ε = 1.5
Switch time interval: 3 min Ratio between fluid and solid velocities:
*
Recycling flow rate: 35.38 ml/min γ = 7.65 ; γ * II = 5.23
I
Eluent flow rate: 21.45 ml/min γ * = 5.72 ; γ * = 4.76
III IV
Extract flow rate: 17.98 ml/min Number of mass transfer units,
–1
Feed flow rate: 3.64 ml/min α = 18.0 (k = 0.1 s )
k
Raffinate flow rate: 7.11 ml/min Peclet number, Pe = 1000
k
Columns: Column diameter: 2.6 cm
Configuration: 2 columns per section Column length: 10.5 cm
The equivalent TMB operating conditions and model parameters for the reference
case were given in Table 9-1 and Fig. 9-9 presents the corresponding steady state
internal concentration profiles obtained with the simulation package. The extract and
raffinate purities were 97.6 % and 99.3 %, respectively; the recoveries were 99.3 %
and 97.6 % for the extract and raffinate streams. The solvent consumption was
–1
1.19 L g and the productivity was 68.2 g/day · L of bed.

Fig. 9-9. Steady-state internal concentration profiles for the reference case.

9.5.1.1 Effect of the Switch Time Interval

The influence of the switch time interval on the purity is shown in Fig. 9-10. A change
on the switch time interval will lead to a change on the equivalent solid flow rate
throughout the system. In all runs the inlet and outlet flow rates, as well as the inter-
nal liquid flow rates in all the four sections of the SMB unit, are kept constant.