Solid-Liquid Mass Transfer Coefficient in Stirred Tank Reactor

7 SOLID-LIQUID MASS TRANSFER COEFFICIENT IN STIRRED TANK REACTOR 

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R. P. Fishwick, J.M. Winterbottom, E.H. Stitt, "Effect of gassing rate on solid-liquid mass transfer coefficients and particle slip velocities in stirred tank reactors", Chem. Eng. Sci., 2003, 58, 1087-1093. 

Tagawa A, Dohi N, Kawase Y. (2012) Volumetric gas-liquid mass transfer coefficient in aerated stirred tank reactors with dense floating solid particles. Ind. Eng. Chem. Res., 51 1938-1948. 

Increase in total pressure implies a higher capital cost of the reactor and is therefore not the optimum solution. As mentioned earlier, the gas-liquid mass transfer and solid-liquid mass transfer coefficients offered by a venturi loop reactor are at least an order of magnitude higher than their nearest competitor, the conventional stirred tank reactor or gas-inducing reactor. Therefore, if the gas-liquid mass transfer coefficient can be so increased by a factor of 10 through the use of a venturi loop reactor, then the sole reason for excessive reactor pressure to achieve the required higher value of mass transfer rate vanishes. In conclusion, the venturi loop reactor can allow operation at much lower pressures as compared to the stirred reactor or its variants. 

Chapters 7 and 8 present models and data for mass transfer and reaction in gas-liquid and gas-liquid-solid systems. Many diagrams are used to illustrate the concentration profiles for gas absorption plus reaction and to explain the controlling steps for different cases. Published correlations for mass transfer in bubble columns and stirred tanks are reviewed, with recommendations for design or interpretation of laboratory results. The data for slurry reactors and trickle-bed reactors are also reviewed and shown to fit relatively simple models. However, scaleup can be a problem because of changes in gas velocity and uncertainty in the mass transfer coefficients. The advantages of a scaledown approach are discussed. 

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