Gas-liquid contacting systems

The model in its present form cannot be used for the design of gas-liquid contacting systems, for several reasons. The model requires a knowledge of the average bubble velocity relative to the fluid, U, a variable that is not available in most cases. This model only permits the calculation of the average rate per unit of area, and unless data are available from other sources on the total surface area available in the vessel, the model by itself does not permit the calculation of the overall absorption rate. 

These are often vertically mounted cylindrical tanks, up to 10 m in diameter, which typically are filled to a depth equal to about one diameter, although in some gas-liquid contacting systems tall vessels are used and the liquid depth is up to about three tank diameters multiple impellers fitted on a single shaft are then frequently used. The base of the tanks may be flat, dished, or conical, or specially contoured, depending upon factors such as ease of emptying, or the need to suspend solids, etc., and so on. 

Gas-liquid contacting systems can be modelled in a manner similar to liquid-liquid contactors. There are however some modelling features which are peculiar to gas-liquid systems. The single well-mixed contacting stage is shown in Fig 3.56. 

Table 2-4 Characteristic features of gas-liquid contacting systems (Martin et al., 1994).

Figure 3.8 Adiabatic gas-liquid contact system for problem 3.9.

G.B. Dillon, I.J. Harris, The determination of mass transfer coefficients and interfacial areas in gas-liquid contacting systems, Can. J. Chem. Eng. 44 (1966) 307-312. 

Gas-liquid contacting systems are utilized for transferring mass, heat, and momentum between the phases, subject to constraints of physical and chemical equihbrium. Process equipment for such systems is designed to achieve the appropriate transfer operations with a minimum expenditure of energy and capital investment. 

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