Liquid Filtration - Chapter 4
This section contains resources on liquid filtration (Chapter 4) including: online simulations of both constant pressure and
constant rate filtrations; video explanations of the modelling taking place in these simulations; a Look-up table for values
of specific resistance and cake solids concentration by volume fraction, and how they vary with pressure, for commonly encountered
materials; and a Utilities section relevant to filtration.
The utilities section includes an online calculator for specific surface area per unit volume from particle size data, which then links to the online prediction of permeability and specific resistance of the filter cake. There is also an online calculator to convert from solids concentration by mass, to concentration by volume fraction, for a suspension.
Filtration simulations online
The two simulations below have data input that may be varied according to the user's requirements, within predefined limits.
The results are tables of data including filtration time, filtrate volume, and filter cake height. It is suggested that
the user copies the data in to a spreadsheet for data plotting, if required.
1) Constant pressure filtration
2) Constant rate filtration
Explanation of filtration online simulations
1) The model used in the online simulation of constant pressure filtration is explained here:
2) The model used in the online simulation of constant rate filtration is explained here:
Filtration constants Look-up table
The two most important parameters in filtration modelling, related to the particles present in the filter cake, are the specific resistance of the filter cake and the dry cake mass per unit filtrate volume of the filter cake. The latter can be deduced from the slurry concentration (by mass) and the filter cake concentration by volume fraction. The filter cake concentration may vary with applied pressure and the Filter Look-up Table includes equations for both the specific resistance and cake concentration and how they vary with applied pressure for many common materials.
1) calculator for specific surface area per unit volume of a particle size distribution given a particle size distribution,
2) calculator for permeability and specific resistance to filtration from the specific surface (above), and
3) calculator to convert from concentration by weight to concentration by volume for a suspension.