Preparative mass-balance model

Niedojadlo, A., K.H. Becker, R. Kurtenbach, P. Wiesen New measurements of NMVOC concentrations in the city air of Wuppertal Source apportionment by Chemical Mass Balance Modelling, Atmos. Environ. manuscript in preparation (2005). 

Prepare a model of the process using the mass balance equations. 

In the equilibrium-dispersive model of chromatography, however, we assume that Eq. 10.4 remains valid. Thus, we use Eq. 10.10 as the mass balance equation of the component, and we assume that the apparent dispersion coefficient Da in Eq. 10.10 is given by Eq. 10.11. We further assume that the HETP is independent of the solute concentration and that it remains the same in overloaded elution as the one meastued in linear chromatography. As shown by the previous discussion this assxunption is an approximation. However, as we have shown recently [6], Eq. 10.4 is an excellent approximation as long as the column efficiency is greater than a few hundred theoretical plates. Thus, the equilibriiun-dispersive model should and does account well for band profiles under almost all the experimental conditions used in preparative chromatography. In the cases in which the model breaks down because the mass transfer kinetics is too slow, and the column efficiency is too low, a kinetic model or, better, the general rate model (Chapter 14) should be used. 

The simulation of the model requires the speciftcation of the maximum availability of all the resources within the plant. These conditions cause constraints to be placed on the simulation flow in the model based on the availability of resources. User specified the purchase cost/cost per use of the resources or built-in cost model based on costestimating factors for biopharmaceutical process equipment were used (Remer Idrovo, 1991). The series of process steps and ancillary operations to manufacture the product, prepare the equipment, test the sample and document the batch were then defined in their respective hierarchical workspaces. Finally, the factors for mass balance calculations were input to determine the characteristics (i.e. mass, volume) of the process streams from each process step. 

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