Chemical paste problem?

Posted on 2015-10-19 06:20:00 in Engineering by KEVIN LEE

The intermediate product of a chemical process is a chemical paste that is saturated with water. The paste is rolled into a thin layer and placed to dry in a flat area 30m long 15m wide. Drying is enhanced by blowing hot air over the paste, and the mass transfer coefficient is 0.017 m/s. Diffusion of water through the paste is rapid so that the concentration of water vapor at the surface of the paste remains constant at 0.002 gmol/L. Water must be removed from the paste remains at a minimum rate of 9.5 L/min (liquid volume). (Note:MW water=18 and p water=1 g/cm^3.)

a.) What mechanism controls the transfer of water from the paste in the air?

b.) What is the molar rate of water removal that corresponds to a volumetric removal rate of 9.5 L/min?

C.) What is the maximum concentration of water vapor allowable in the air (far from the paste surface) if water must be removed at a rate of at least 9.5 L/min?

D.) Assuming that the mass transfer coefficient remains constant, what can be done to increase the rate of water removal from the paste?

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