Textile Filtration

1. WELCOME TO
OUR
PRESENTATION
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2. Presentation Topic-
Textile Filtration
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3. FILTRATION
 Filtration is a process of separating dispersed particles from a dispersing fluid by means of
porous media. The dispersing medium can be a gas (or gas mixture) or a liquid
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Upstream
Dispersing
fluid
Dispersed
particles
Filter
thickness
Face of the filter with „filter cake“ of
deposited particles
Downstream
Particles deposited
inside the filter
Filter
Channel
wall

4. Types of filtration
 Flat filtration
 Deep filtration
 Pleated filters
 Pocket filters
 Cartridge filters
 Drum filters
 Bag filters, pulse-jet filters
 Disc filters
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Flat filtration
All particles which are bigger than pores are captured on the flat filter surface. It is
typical for example for fabric or spunbond filters. Thus for these filters the pores
distribution and permeability are important properties. Flat filtration is common for liquid
filtration. Flat filters are described in subject „High funcional textiles“
Direction
of flow
Textile filter expressed as a set
of cylinders placed in parallel
Captured
particles

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6 Deep filtration
Depth filter are able to capture particles that are too small to be sieved out as in flat filtration.
Particles, which can be a lot of smaller than the distances between the fibers penetrate into the
fiber structure. Filtered particles are captured in terms of the filtration mechanisms. This type of
the filtration process is importatn for the most of filter applications.
Direction
of flow
Textile filter expressed as a set
of cylinders placed in parallel
Captured
particles

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7 Pleated filters
It is suitable for high efficient filters. Pleating process leads to bigger filter surface and
consequently to smaller pressure drop. It is possible to pleat flat materials, which stiffness and
elongation is similar to paper. It is necessary to hold textile pleats by rigid frame. Filter thickness
is usually from 1 to 3 cm.
Polluted
air
Clean
air
Rigid
frame
Filter
Air flow
direction
Filter
thickness

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Examples of pleated filters

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9 Pocket filters
Principle is similar to pleated filters, only filter thickness is similar to other filter dimensions.
Generally it is possible to use nearly all textile fabrics. At first are stitched or bonded each
pockets and then it put into the frame.
Polluted air
Clean
air
Filter

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Cartridge filters
Flat (bulky) filter or pleated filter is wrapped around the perfored tube. The advantage is
smaler dimension of filter with regard to acting surface.
Variants of cartridge filter
cross-section
Flat (bulky) filter Pleated filter
Filter
Perforated
tube
Polluted air
Clean air

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11 Examples of cartridge filters

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Drum filters
1.The rotating drum is actually a frame with
mounted filter panels. The filter panels use a
polyester or stainless steel filter cloth that is
of a specific micron porosity.
2. Waterborne solid waste particles enter the
Drum Filter from the inside of the rotating drum.
3. Solid waste particles (larger than the micron
porosity rating of the filter screens) are
ocaptured n the filter screens.

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Examples of Drum
filters

14. Bag filters, pulse-jet filters
Principle is similar as cartridge filters however bag length is much bigger than diameter and usually filter is
cleanable by reverse pressure pulse. Commonly many bag filters are used for one application (hundreds).
Most of the dust is collected on the surface of filters. When the increasing pressure drop reached a set value,
the filters are cleaned by a short burst of compressed air moving in reverse direction. Typical maximum
pressure drop is 1000 – 2000 Pa, typical pressure pulse is in range 0,5 – 1 MPa and cleanig time 0,1 - 100
sec.

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Examples of pulse-jet filters
Steel
frames

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16 Disc filters
A disc filter is a type of water filter used primarily
in irrigation, similar to a screen filter, except that
the filter cartridge is made of a number of discs
stacked on top of each other like a pile
of poker chips. The water passes through the
small grooves in between and the impurities are
trapped behind

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Example of Disc filters

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18 Filtration variables
Filtration variables are divided onto three groups:
1. Variables of filter material
2. Variables of filtered particles
3. Variables of filtration process
Variables of filter material:
•Filtration area
•Filter thickness
•Density and surface density of filter
•Uniformity of fibrous material

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19 Variables of filtered particles
•Particle size
•Concentration of particles
•Shape and surface of particles
•Electrical properties
Variable of filtration process
•Face velocity (speed of filtered particles in front of filter)
•Viscosity of the flow
•Temperature, pressure, humidity

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20 PRINCIPLES OF FILTRATION
Objective of filter medium is to maximize the possibility of collision and the subsequent
retention of the suspended particles with fibrous structures while minimizing the energy loss of
the system. The efficiency of filtration in industrial fabrics are affected by there porosity.
Knowledge of air permeability is also important for suitability for use. Permeability is capacity
of porous materials to transmit the fluids. Liquid and gas permeability increases with the
increase in porosity of the fabric. The type of finish also affects the permeability. When
Porosity increases pressure drop tends to decrease. When flow rate increases, pressure drop
increases.
There are five principles of filtration:
 Interception
 Inertial disposition
 Random diffusion (Brownian motion)
 Electrostatic disposition
 Gravitational forces

21. FILTRATION AND TEXTILES
Essential part of countless industrial processes, contributing to purity of product, savings in
energy, improvements in process efficiency, recovery of precious materials and General
improvements in pollution control. In the coming decades, fabric filtration will play a very
critical role in day to day life, and there is no single type of fabric being used in all the
process.
Filtration fabrics are used widely in:
 Vacuum cleaners
 Medical uses
 Power stations
 Petrochemical plants
 Sewage disposal
 Water filtration
 Geotextiles etc
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22. FABRIC CONSTRUCTION
 Three basic types of construction are found in Filter fabrics, viz., woven fabrics, need lefelts
and knitted structures. The first two are produced in flat form and will require (i) slitting to
appropriate width and (ii) converting into tubular sleeves, whereas knitted fabrics may be
produced directly in tubular form.
 The technologist has basically four types of yarn to choose from when designing a filter
fabric, namely monofilament, multifilament, fibrillated tape and staple-fibre Yarns.
IMPORTANT CHARECTERISTICS OF FILTER FABRICS
 With the fabric warp and weft density increases, the filtration resistance of the filter cloth
increases gradually.
 With the increase in the fabric warp, weft twist, the filtration resistance of the
 filter cloth is reduced gradually
 Fabric tissue filtration resistance: resistance of plain weave, twill path of least
 resistance.
 Porosity of the fabrics.
 Air permeability of the fabrics
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23 VARIOUS APPLICTIONS OF TEXTILES INFILTRATION
In vaccum cleaners - The bag used in
vaccum cleaners is the typical method to
capture the debris vacuumed up. It
involves a paper or fabric bag that
allows air to pass through, but attempts
to trap all dust and debris in the bag.
The bag may be disposable, or designed
to be cleaned and re-used.
In medical uses – Woven filters set the
standard for safe and efficient filtration
solutions in medical devices. Precision
woven fabrics is a critical component
for medical filter devices, blood
filtration : precision woven fabrics set
the standard for safe and efficient
filtration

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24 In Power Stations- A baghouse (BH, B/H)
or fabric filter (FF) is an air pollution control
device that removes particulates out of air or
gas released from commercial processes or
combustion for electricity generation. Power
plants, steel mills, pharmaceutical producers,
food manufacturers, chemical producers and
other industrial companies often use
baghouses to control emission of air
pollutants
Water filtration- This type of filter is a
common solution to the problem of
obtaining clean water in many parts of the
world, especially rural parts of developing
nations. It is a fairly simple process that
involves only materials that are available in
most parts of the world.

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In Geo-textiles- The non-woven geo-textile
fabric is a common choice for areas looking
to stabilize, separate or filter materials. All
non-woven fabrics come with a needle-
punched exterior that allows thin water
particles to filter through the fabric while
keeping soil from filtering through. This
geo-textile filter fabric helps to retain fine
particles when water passes from fine to
coarse-grained soil layers

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26 Fibres and Polymers used in Filtration Media
Natural - fibres from vegetable matter such as
cotton, flax, jute, wood cellulose
- or fibres from animals such as
silk, wool, fur, hair
Fibres from Vegetable matter
cotton Flax
jute
Wood cellulose

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27 Fibres from animals
silk wool hair
Fibres and Polymers used in Filtration Media
Artificial - fibres from natural resources such as glass, ceramic, carbon,metal,
reconstituted cellulose
synthetic – fibres derived from oil such as thermoplastic polymers

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Artificial fibres
reconstituted cellulosecarbonceramicglass
Out of these fibres Polyester and Polypropylene would be the most widely used

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