Parameters in Mass Balance Equations

The values for parameters in the mass balances have to be determined either theoretically or experimentally. These parameters are equilibrium ratio (Kj), mass transfer coefficients (fcLi and kci), diffusion coefficients in the gas and liquid phases (Du and Da), volume ratios (Uy and Op), and liquid holdup (bl). The equilibrium ratio, Kj, can be estimated using thermodynamic theories [4] for gases with a low solubility, the equilibrium ratio, Ki, can sometimes be replaced by Hemy s constant [5]. In Refs. [6,7], some methods for estimating ku and ka are discussed. The correlation equations for ku and ka contain the diffusion coefficients, D i and Dci, in the gas and liquid phases, respectively. The mass transfer coefficients, ku and ka, are formally related to the diffusion coefficients by the film theory  

In practice, the mass transfer coefficients are obtained from semiempirical correlations that predict a somewhat lower dependence of the mass transfer coefficient on the diffusion coefficient, for example, ku oc The gas-phase diffusion coefficients can be 

Characteristics Column Stirred Tank Concurrent Concurrent Countercurrent Fluidized Bed 

Source Data from Trambouze, R, van Landeghem, H., and Wauquier, J.-P., Chemical Reactors—Design/ Engineering/Operation, Editions Technip, Paris, 1988. 

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