Page 294 - Chiral Separation Techniques

10.4 Example of process design 273

10.4.1.3 SMB: Nonlinear Conditions

˜
˜
F
F
Calculation of the SMB flowrates: The criterion K · C + K · C ≤ 0.1 (Equation 10)
A A B B
equaling now approximately 0.22, the system is operating under nonlinear adsorp-
tion isotherm conditions.
Conditions of nonlinear chromatography prevail, and the set of Equations (15–19)
leads to the following optimum reduced flowrates:
ω = 2.2116 ω = 1.2785
G F
m = 3.14 m = 1.988 m = 2.831 m = 2.022
I II III IV
and the region of complete separation is given in Figure 10.7.

Figure 10.7. Zone of complete separation according to the equilibrium theory.

–1
Knowing that the feed flow rate should equal Q feed = 125 l h , one can estimate
–
–1
the required solid flow rate: Q = Q /(m –m ) = 149 l h leading to all the inter-
Feed III II
nal flow rates:
Q = 466 l h –1 Q = 295 l h –1 Q = 420 l h –1 Q = 300 l h –1
I u m IV
Calculation of SMB flowrates: The flow rate in each zone of a SMB is related
to the flow rate of a TMB by Equation (20):

Q SMB = Q TMB + ε ⋅ Q
I I 1− ε

Consequently, one obtains for the SMB:

Q = 564 l h –1 Q = 394 l h –1 Q = 519 l h –1 Q = 399 l h –1
I II III IV
the mean value of the flow rates in the different zone is thus approximately Q mean =
–1
469 l h .