Transfer in Gas-Liquid Reactors

In this section we consider the rate of absorption of gases into liquids that are agitated so that dissolved gas is transported from the interfacial surface to the interior by convective motion. The next section, based on this one, treats chemical methods for determining interfacial areas and mass-transfer coefficients in agitated gas-liquid reactors. 

When a soluble gas is mixed with an insoluble one, it must first diffuse through the latter to reach the interfacial surface. As a result, the partial pressure of the soluble gas at the interface is generally less than in the bulk of the gas. The liquid in which the soluble gas is absorbed may be agitated in different ways  

If we consider first physical absorption, whereby gas dissolves in the liquid without reacting, the basic representation for transport of the solute gas is based upon the concept of additivity of a gas-phase resistance and a liquid-phase resistance, assuming that the interfacial resistance can be neglected. The rate of absorption is then 

Here a is the interfacial area between gas and liquid per unit volume of the system, is the average rate of transfer of gas per unit area, p and Px are the partial pressures of soluble gas in the bulk gas and at the interface, C is the concentration of dissolved gas corresponding to equilibrium with/ , and Cao is the average concentration of dissolved gas in the bulk liquid. 

This model assumes a stagnant film of thickness 8l at the surface of the liquid next to the gas, while the rest of the liquid below the film boundary is kept uniform in composition by turbulent agitation (W5). Convection is assumed absent in the liquid film, within which the transport of the soluble gas takes place by molecular diffusion alone. The concentration in the film falls from C at the interface toCAo at the inner edge of the film, that is, in the bulk liquid. This simple model leads to 

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So the technique of conducting simultaneous absorption with fast pseudo-mth order reaction and physical absorption or desorption concurrently is certainly a promising attempt to understand the whole complex problem of transfer in gas-liquid reactor (15,... 

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