equipments to control particulate matter air pollution and control control of particulate matter

1. Equipment to Control
Particulate Metter[part-1]
Ravi Kumar GARRE

2. Contents covered
• Introduction
• Settling chambers
• Inertial separators
• Cyclones
• Filters
• Electrostatic precipitators
• Scrubbers/ wet collectors
[Note: filters, electrostatic precipitators, scrubbers
are not covered in this presentation]

3. Introduction
• To remove particulate matter from gaseous
streams various types of equipments are in
practice.
 Settling chambers
 Inertial separators
 Cyclones
 Filters
 Electrostatic precipitators
 Scrubbers/ wet collectors

4. Introduction
• The data to keep in mind in the
selection of proper equipment is:
 Quantity of gas to be treated and its variation
with time
 Nature of particulate matter
 Concentration of particulate matter
 Temperature and pressure of gas stream
 Nature of gas stream (i.e. solubility, corrosivity,
ignitability, etc.)
 Desired quality of treated effluent

5. Introduction
• Objectives of control equipment
 Prevention of nuisance
 Prevention of physical damage to property
 Recovery of valuable waste product
 Minimization of economic losses
• Efficiency of separating device
η = (quantity of particulates collected
from gas)/(quantity of particulates
present initially)

6. Settling chambers
• Settling chamber is the
simple equipment used
to collect particulate
matter from gaseous
streams.
• It consists of a chamber
in which the carrier gas
is allowed.
• The velocity of gas is
reduced in the large
chamber.

7. Settling chambers
• Under the influence of
gravity, the particles can
get settled at bottom.
• Hoppers/ collectors are
provided at bottom to
collect the settled
particulates.
• Used to remove particles
size greater than 50µm.

8. Settling chambers
Merits
• Simple to design, operate
and maintain
• Low initial cost and
operating cost
Demerits
• Requires large space
• Collection efficiency is
low i.e. about 50%
• Only large sized particles
are separated out

9. Settling chambers
Applications
• Industrial application is
limited
• Widely used for blast
furnaces and kilns
• Some times used in food
industry and metallurgical
industry
• Used as pre-cleaners for
high efficiency collectors

10. Inertial separators
• Inertial separators separate dust from gas
streams using a combination of forces such as
centrifugal, gravitation and inertial.
• These forces move the dust to an area where
the forces exerted by the gas stream are
minimal.
• The separated dust is moved by gravity into a
hopper, where it is temporarily stored.

11. Inertial separators
• These equipment utilise relatively greater inertia of the
dispersoid to effect the particulate gas separation.
• Such technique involves causing sudden change in the
direction of gas stream and there separate the particle
by inertia, impingement on a target or by centrifugal
force.
• There are three fundamental types of inertial/ impact
separators:
1. Baffle type separator
2. Louver type separator
3. Dust traps

12. Baffle type separator
• In this baffle type
separator, the gas
stream is made to follow
a tortuous path.
• Such a flow is obtained
by inserting staggered
plates in series inside a
chamber.
• Such plates causes the
conveying gas stream to
make sudden change of
direction.

13. Baffle type separator

14. Baffle type separator
• While carrier gas is flowing through such a
tortuous flow, particles do not follow the gas
stream, strike on baffle walls and then settle.
• In most of cases, the device is used to remove
particles from power plants and rotary kilns.
• Baffle type inertial separator removes
particles of size greater than 20µm

15. Louver type separator
• This is another type of
gas-particulate separator.
• Here a number of blades
set with an angle are
provided in the path of
gas flow.
• While the gas is flowing
through that path, the
particulate matter strike
the blade and then get
settle down.

16. Louver type separator
• The blades are set to force a
quick sharp change in the
direction of gas stream,
• The dust particles are
separated out and collected
in the bed of the separator.
• This device is suitable for
removing particles larger than
30µm

17. Dust trap
• Dust traps are another
type of inertial
separators.
• In these devices, gas
entered into the chamber,
through a long pipe.
• The entered gas stream
inside the chamber, it is
made to under go a
change in direction by
180˚ and spun rapidly

18. Dust trap
• The centrifugal force created
by the circular flow, throws
the dust particles towards
the walls of the chamber.
• After striking the walls, these
particles fall into the hopper
at bottom of the chamber.
• This device is suitable for
removing particles larger
than 30µm

19. Cyclones/ cyclone separators
• A centrifugal force is
created inside the
chamber.
• This centrifugal force
tend to drive suspended
particulate matter to
walls.
• Then the particles strike
the walls and move
downwards.

20. Cyclones
• The centrifugal force on
particles in a spinning
stream, is much greater
than gravity. Hence
cyclones are effective in
removal of much smaller
particles.
• Cyclones require less
space.
• Cyclones are effective in
removal of particles with
size in between 10µm to
40µm

21. Cyclones/ cyclone separators
• Cyclone separators also
depends on centrifugal
force for its action.
• It can separate
particulates without
moving its parts.
• The velocity of gas
stream near inlet,
transformed into
confined vortex.

22. Cyclones/ cyclone separators
Advantages
• Low initial cost
• Requires less floor area
• Simple construction and
maintenance
• Can handle large
volume of gas at high
temperature
• No moving parts
Disadvantages
• Can cause few
operational problems
such as erosion,
corrosion, etc.
• Cannot remove
particles with size less
than 10µm
• Sensitive to variable
dust load and flow rate

23. Cyclones/ cyclone separators
Applications
• Used in industries like cement, feed and grain
processing, food and beverage processing,
paper & textile industries and wood working
workshops.
• Used in recovery of catalyst ducts in
petroleum industry and reduction of fly ash
emission.

24. THANK YOU