13. ►A simplest device, collecting dust
of size
>1oµm.
►Settling chambers use the force of
gravity to remove solid particles. The gas
stream
enters a chamber where the velocity of
the gas is reduced. Large particles drop D
f
e
r
t
J
;
:
s
o
u
t of the gas and are recollected in
hoppers. Because settling chambers are
effective in removing only larger
particles, they are used in conjunction
with a more efficient control device.
►T
h
e size, shape of particles and density
and viscosity are important parameters.
C
l
e
a
nG
a
s
Exits
14. . ---···
PROCESS CYCLONE SCHEMATIC...---1
This process is achieved by a sudden
change in the direction of gas flow.
The dust particle is spinning in a
circular path, it is subjected to an
outward force. As a result the
particles collect on the wall and fall
to the bottom of the vessel.
DIRTY
GAS
'
DUST
15. -
---
►Passing the particle laden gases Figure9.
between high voltage discharge Tranf_ormer-
e
1ectrod es.
Rect1f1er"'-'
Sets
►Majority of particles
get charged
and collected on ground
electrodes.
►Atintervals both discharge and c1 :
collecting electrodes are rapped to Out
dislodge collected particles from
the electrodes, which then fall into
hoppers at the bottom of the
precipitator.
►Ele. Precipitator is efficient for
the particle size below o.01µm,
can tolorate operating
temperature as high as 700°k.
ConventionalElectrostatic Precipitator
.., _,..Rappers
.,...._Collection
Plates
Hoppers _J,.,.,;;,.....--·
Flue Gas In
Discharge
Electrodes
16. =
=
:
This method is most often used type of
device, which is required to meet
any future standards limiting the
emission of respirable particles.
The collection efficiency is very high
and even for particle of o.01µm
diameter.
The Fabric filters, or bag houses ,
remove dust from a gas stream by
passing the stream through a porous
fabric.
The fabric filter is efficient at removing
exceed
most
fine particles and can
efficiencies of 99% in
applications.
Figure13. Reverse AirFabricFilter
Induced
6
Draft
rt---'!Fan
Gas
Ol.lllet
.. . B
a
g
GasInlet
Compartment3
Compartment 2
Compartment 1
17. =·=:.. '-
Objective of scrubber is to
entrain the particulate matter
bottom of the scrubber,
in liquid droplets. Water
subsequently flows from the
the
particulate is allowed to settle
and clarified water is re
circulated.
SCRUBBING CUTAWAY
DIRTY
GAS
INLET
CLEAN GAS O UTL E T
i , + - - S C R U B B I N G
MEDIUM
SPRAYS
, . ) = : : - S C R U B B E R
BODY
SCRUBBING LIQUOR A ND
RE CO V E R ED D U S T O UTL E T
20. Vehicle at manufacturing stage 60 Hatridge Smoke Units (HSU)
Vehicle on road 70 HSU
Category Vehicle on
road
Vehicle at
manufacturing
stage
2 or 3 wheeler
vehicles with
engine
displacement less
than 50cc
5.0 5.0
Other 2 or 3
wheelers
4.5 5.5
4 wheelers 4.0 3.5
: : . - - - - ---
Diesel driven vehicles: (Smoke density)
---
Petrol driven vehicles: (Limits of CO in percentage
volume)
23. fOsorption is a process where gases,
vapours or liquids are concentrated
on a solid surface as a result of
surface or chemical force (physical
adsorption
respectively).
and chemisorptions
The amount of
adsorbed substances depends
directly on the internal surface area
of solid and the l<inetics of the
process.
The most important adsorbents in
industrial use to-days are Bauxite,
activated carbon, activated alumina,
silica gel and molecular sieves.
OityGas
CIJGI,
.--1 SIMmfor
Regenetllloc,
I
CondtnNII CM
♦
