eq. (A.168)
The main objective of this operation model is to estimate the time for loading a column, track recovery yield, and estimate the number and size of columns required (in Design Mode).
● Expanded Bed Adsorption (EBA) Chromatography Procedure
The total binding capacity of the resin refers to all compounds that bind to the resin under actual operating conditions.
If Vc is the volume of material processed by the column per cycle, Ci is the concentration of component i in the feed stream, Fi is the fraction of component i that binds to the resin, then the volume, Vb, of the sedimented bed is:
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eq. (A.168) |
where k is the total number of components in the feed stream, ODF is the overdesign factor, and C is the binding capacity of the resin. The bed height (Hb) is either specified by the user (even in Design Mode) or calculated by the program based on the degree of expansion and other parameters (see below). The bed diameter is calculated using the following equation:
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If D > Dmax, then multiple columns are assumed in parallel. The column diameter is assumed identical to the bed diameter. Analogous calculations are done for columns with a square cross sectional area.
The user specifies one of the above three variables and the program calculates the other two. If the bed height (Hb) is specified by the user, we have the following cases:
Fluidization Linear Velocity Specified
In this case, the residence time (tr) is estimated using the following equation:
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where U is the fluidization linear velocity. The loading (process) time (tp) is estimated using the following equation:
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Residence Time Specified
In this case, the loading (process) time is estimated using eq. (A.171) and eq. (A.170) is solved for U to estimate the linear fluidization velocity.
Process Time Specified
In this case, eq. (A.171) is solved for tr to estimate the residence time and eq. (A.170) is solved for U to estimate the fluidization linear velocity.
If the user does not specify the bed height, it is estimated based on bed expansion and the expansion safety margin. We have the following cases:
Fluidization Linear Velocity Specified
In this case, the bed height is estimated using the following equation:
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eq. (A.172) |
The column height, Hc, is always specified by the user. The bed expansion (H/H0) is either specified by the user (3.0 is the default value) or calculated using the following empirical equation:
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eq. (A.173) |
The multiplier (A) and the liquid viscosity are specified by the user. Then, eq. (A.170) and eq. (A.171) are used to calculate the loading and residence times.
Residence Time Specified
In this case, the loading time is estimated using eq. (A.171). Then, through an iterative algorithm, the program estimates the maximum bed height that does not lead to an overexpansion of the bed. The linear velocity that corresponds to that is estimated using eq. (A.170).
Loading Time Specified
In this case, the residence time is estimated using eq. (A.171). The rest of the calculations are the same as in the previous case.
For a component that binds to the resin its amount in the product stream is equal to its amount in the feed stream times its binding fraction and its elution yield. All components present in the feed stream, which do not bind to resin, exit into the waste stream. Also, all materials in the wash-regeneration-equilibration streams end up in the waste stream. For elution operations, the ‘Volume in Product Stream’ factor which is expressed in ‘Sedimented Bed Volumes’ determines the fraction of an elution buffer that ends up in the product stream. The remaining exits in the waste stream.
The cost associated with resin replacement is estimated as for all consumables (see Consumables Cost). For resins that last several years, the user may decide to depreciate the first resin fill-in by checking the ‘Is First Resin capitalized’ check box in the equipment consumables tab.
1. Pharmacia Biotech (1997). Expanded Bed Adsorption – Principles and Methods, ISBN 91-630-5519-8, Edition AA.
2. Hjorth, R., P. Leijon, A.-K. Barnfield Frej and C. Jagersten (1998). Expanded Bed Adsorption Chromatography.
The interface of this operation has the following tabs:
● Oper. Cond’s, see EBA Column Loading: Oper. Conds Tab
● Resin Binding, see EBA Column Loading: Resin Binding Tab
● Labor, etc, see Operations Dialog: Labor etc. Tab
● Description, see Operations Dialog: Description Tab
● Batch Sheet, see Operations Dialog: Batch Sheet Tab
● Scheduling, see Operations Dialog: Scheduling Tab
