FILTRATION

A. Material Balance

Over time filter cake is being deposited on the filter. Simultaneously, accumulated volume of product filtrate is being collected. The feed is a mixture of solids (dry) and filtrate (solvent).

 

B. Filtration Resistance

In filtration operation, there are two resistances to flow: cake resistance and filter medium resistance. Hence, filtration must be operated at a total operating pressure, ∆P, to overcome these resistances.

 

C. Ruth Equation for Filtration

The Ruth equation is established from the basic principle of flow, resistance and driving force.

Form 1:

\frac{ \frac{dV}{dT} }{A} = \frac{- \Delta P}{ \frac{\alpha \mu Vc_{s}}{A} + \mu R_{m}}

\mu V \frac{c_{s}}{A} – cake resistance
\mu R_{m} – filter medium resistance
\alpha – specific cake resistance
\mu– viscosity of the filtrate
Form 2:

\frac{dV}{dT} = \frac{- \Delta P}{ \frac{\alpha \mu c_{s} }{ A^{2} }(V + V_{e}) }

V – Volume of the collected Product Filtrate
c_{s} – solids/filtrate
A – Cross-sectional area
R_{m} – resistive property of the filter to flow
V_{e} – fictitious volume of the filtrate which is equivalent to the resistance applied by the filter medium

 

Pages: 1 2

Leave a Reply

Your email address will not be published. Required fields are marked *