CONTINUOUS FILTRATION
Since testing and scale-up are different for batch and continuous
filtration, discussion in this section will be limited to continuous
filtration.
It is both convenient and reasonable in continuous filtration, except
for precoat filters, to assume that the resistance of the filter cloth plus
filtrate drainage is negligible compared to the resistance of the filter cake
and to assume that both pressure drop and specific cake resistance remain
constant throughout the filter cycle.
Equation (18-54), integrated under these conditions, may then be
manipulated to give the following
relationships:
where W is the
weight of dry filter cake solids/unit
area, Vf is the volume of cake formation filtrate/unit area, Vw is the volume of cake wash filtrate/unit
area, Θf is the cake formation time, Θw
is the cake wash time, and N is the wash ratio, the volume of cake wash/volume
of liquid in the discharged cake.
As long as the suspended solids concentration in the feed remains constant, these equations
lead to the following convenient correlations:
.png)
.png)
There are two other useful empirical correlations as follows:
.png)
.png)
where R is percent remaining—the percent of solute in the unwashed cake
that remains after washing.
Genk, Wayne J., dkk. 2008. Perry’s chemical engineers handbook, Section 18: Liquid-solid Operations and equipment. New York: The McGraw-Hill Companies, Inc
0 comments:
Post a Comment