filtration

1. Filtration
Md: Kamrujjamal
Student ID: 17ACE013
Dept. of Applied Chemistry and Chemical Engineering
Bangabandhu Sheikh Mujibur Rahman Science and Technology University
Gopalganj, Bangladesh

2. Centrifugation
Centrifugation is the separation process that relies on the action of centrifugal
force to separate particles in a solid–liquid mixture into two distinct phases
consisting of the sediment and centrifugate (also called supernatant liquid).

3. Sedimentation
• Sedimentation is the tendency for particles in suspension to settle out of the fluid
in which they are entrained and come to rest against a barrier. This is due to their
motion through the fluid in response to the forces acting on them: these forces can
be due to gravity, centrifugal acceleration, or electromagnetism.
For example, sand and silt can be carried in suspension in river water and on reaching
the sea bed deposited by sedimentation; if buried, they may eventually become
sandstone and siltstone (sedimentary rocks) through lithification. ... Desert sand dunes
and loess are examples of aeolian transport and deposition

4. Equipment of filtration

17. Centrifuge
• A centrifuge is a device that uses centrifugal force to separate various
components of a fluid. This is achieved by spinning the fluid at high speed
within a container, thereby separating fluids of different densities (e.g. cream
from milk) or liquids from solids. It works by causing denser substances and
particles to move outward in the radial direction

18. Principles of centrifuge
A centrifuge is used to separate particles suspended in a liquid according to particle
size and density, viscosity of the medium, and rotor speed.
Within a solution, gravitational force will cause particles of higher density than the
solvent to sink, and those less dense than the solvent to float to the top. Centrifugation
takes advantage of even minute differences in density to separate particles within a
solution.
As the rotor spins around a central axis, it generates a centrifugal force acting to move
particles away from the axis of rotation. If the centrifugal force exceeds the buoyant
forces of liquid media and the frictional force created by the particle, the particles will
sediment.

19. Industrial Centrifuge Applications
• The main application of decanter centrifuges is to separate large amounts of solids from
liquids on a continuous basis. They are also used to wash and dry various solids in industry,
such as polystyrene beads, clarify liquids and concentrate solids
• Petrochemical/oil Industry Examples Industrial and Biological Wastewater
* Treatment Industry Examples
1. Refining 1.Municipal wastewater
2. De-watering 2. Cleaning of wash water
3. Oil well drilling
4. Lubricating oil additives
5. Waste oil stream recycling

20. Classifiers
• There are many different types of classifiers which can be broadly grouped into two classes depending on
the direction of flow of the carrying current.
• Horizontal current classifiers such as mechanical classifiers are essentially of the free-settling type and
accentuate the sizing function.
• Vertical current or hydraulic classifiers are usually hindered-settling types and so increase the effect of
density on the separation.
Types
1. Settling cones
2. Mechanical classifiers
3. The rake classifier
4. Spiral classifiers
classifiers

21. Air Classifier Mills
Air Classifier Mills are designed for producing micro-fine particle size. High air, unique multi teeth
rotor and serrated liners fitted in the air classifier mills create numerous air whirls, turbulence and
progressive grinding. The air classifier mills are designed to control the top cut size, great turbulence,
and high air whirls to ensure minimum temperature increase to handle heat sensitive materials. The
classifier retains coarser particles while suction fan discharges fine powder through cyclone separators
and dust is collected in filter bag units. All air classifier mills are supplied with pneumatic conveying
system.

22. Operating Principle
Referring to the schematics given, most of the processing air or gas enters through the bottom
section of the mill. Up to 30% of the total airflow can be introduced with the feed material.
Concurrent with this constant mass flow of gas, feed material is introduced to the mill ideally
in a constant mass flow manner.
For most applications, material is introduced to the tip of the rotating hammers through a port
opening at the side of the mill. Feed material can be either pneumatically conveyed or screw
fed. The rotating hammers attached to the impact rotor disc serve to fracture the process
material.
A serrated liner mounted on the periphery of the grinding chamber in the hammer path serves
to improve grinding efficiency by preventing particles from accelerating to the speed of the
hammers thereby increasing the relative speed difference.

23. Operating Principle cont……
• The primary airflow passing through the narrow annular gap formed in
between the liner and impact rotor disc in conjunction with the fanning
action of the hammers transports the material to the top of the mill. A
dispersion ring then directs the material downward toward the classifier.
Baffles welded to a shroud ring straighten the flow of material and air so that
particle vortexing at the dispersion ring area is avoided.
• The shroud assembly effectively separates the grinding zone from the
classification zone as well as providing a defined path for the material and air
to flow through.

24. Applications
• Metallurgical Powders
• Pigments
• Fly Ash
• Silica
• Soya flour
• Hydrated lime
• Food Products
• Chemicals
• Aluminium Oxide
• Graphite
• Calcined Magnetite
• P.V.C. Resin
• Cement
• Limestone
• Talc
• Clays

25. Cyclotron
• A cyclotron is a type of compact particle accelerator which produces
radioactive isotopes that can be used for imaging procedures. Stable, non-
radioactive isotopes are put into the cyclotron which accelerates charged
particles (protons) to high energy in a magnetic field.

26. The principle of cyclotron
Cyclotron is a device used to accelerate charged particles to high energies. It was
devised by Lawrence. Cyclotron works on the principle that a charged particle
moving normal to a magnetic field experiences magnetic lorentz force due to which
the particle moves in a circular path.
• Use of Cyclotron
Cyclotrons can be used in particle therapy to treat cancer. Ion beams
from cyclotrons can be used, as in proton therapy, to penetrate the body and kill
tumors by radiation damage, while minimizing damage to healthy tissue along their
path.

27. Centrifugal Sedimentation
The sedimentation (separation) process which is induced by centrifugal-
Coriolis forces in a mixture of buoyant particles (droplets, bubbles) in a
suspending fluid, remains very much on the frontier of fluid flow research.
Sedimentation is a process where molecules or particles sediment downward
due to gravitational force. Larger and denser particles sediment faster.
Centrifugation facilitates sedimentation with centrifugal force, separating the
particles into solid pellet (precipitate) and liquid solvent (supernatant)