particulate emissions control by cyclone

1. PRESENTATION TOPIC;
Control of particulate emissions using cyclones
Presentation by
Komal Aroosh
M.Sc (4th semester)
DEPARTMENT
CENTER FOR COAL TECHNOLOGY
PUNJAB UNIVERSITY LAHORE

2. Control of particulate emissions using cyclones
QUESTIONS
 What are the particulate emissions?
 Why its necessary to control the particulate emissions?
 What systems are available to control the particulate emissions?
 History of high efficiency cyclones
 What is agglomeration spray?
 Commercial applications of high efficiency cyclones
 Working principle
 Advantages
 disadvantages
 Can a cyclone reach efficiencies of ESP / Bag filter / Wet scrubber?
 Selection criteria
 Outlook

3. Control of particulate emissions using cyclones
What are the particulate emissions?
Particulate emissions are emissions characterized by
the presence of small particles of solids and liquids.
These common byproducts of combustion are a
major health and environmental concern in many
regions of the world, and steps have been taken to
reduce particulate emissions and to educate people
about their risks. These emissions are also known as
particulate pollution or particulate matter.

4. Control of particulate emissions using cyclones
Sources of particulate emissions
Sources of particulate emission can be man made or
natural.
 the vast majority of such emissions coming from
factories
 around 10% coming from vehicles on the road.
 Combustion of fossil fuels also releases other
substances and particulates into the air
 Some particulates occur naturally, originating from
volcanoes, dust storms, forest and grassland fires,
living vegetation, and sea spray.

5. Control of particulate emissions using cyclones
Why its necessary to control the particulate emissions?
Sometimes, particulate emissions are visible in
the form of soot or smoke, because the particles
are so large. Most are not visible, however,
which is part of what makes them dangerous,
because people do not realize that the emissions
are occurring. Small particles are also more
dangerous because they are less likely to be
trapped in the mucus linings of the nose and
throat.

6. Control of particulate emissions using cyclones
Effect of particulate emissions on the humans
If the particles, which can be composed of any
combination of hundreds of chemicals and
elements, are able to get through the defenses of
the nose and mouth, then they can find their way
into the lungs and possibly even pass into the
blood stream. This can cause respiratory problems
and potentially contribute to a higher risk for
certain types of cancer or heart disease.

7. Control of particulate emissions using cyclones
Effect of particulate emissions on the plants
 The particulates may block their leaves so that
they cannot photosynthesize properly.
 The climate as a whole can be heavily impacted by
such emissions, as they can block the sunlight so
that it cannot reach the Earth.
 Cause a decrease in crop yields, and contribute to
global warming trends.

8. Control of particulate emissions using cyclones
Effect of particulate emissions on the animals
For animals, particulate emissions pose a threat to
cardiovascular and lung health. In the lungs,
particulates can block or rupture the alveoli,
interfering with lung function. A number of
respiratory conditions including asthma and
cancer are linked to exposure to particulate
emissions. The heart muscle and blood vessels can
also be damaged by particulates if they enter the
bloodstream through the lungs, causing
widespread medical problems.

9. Control of particulate emissions using cyclones
Many stacks
Are still emitting
high levels
of particulate
But particulate emission control requirements
will become more and more stringent

10. Control of particulate emissions using cyclones
What systems are available to control
Particulate emissions ?
• Electrostatic precipitator
• Bag house fabric filter
• Wet scrubber
• High efficiency cyclones

11. Control of particulate emissions using cyclones
Main steps of ESP
The processes of
electrostatic precipitator
are known as three main
stages:
particle charging
transport
collection.
Evaluation of ESP:
• High cost (investment, maintenance & operation)
• Complex large size plant with sub-systems
• Requires constant gas conditions (sulphur, temp, moisture)

12. Control of particulate emissions using cyclones
Main process of bag house fabric filter
Bughouses are very efficient particulate
collectors because of the dust cake formed
on the surface of the bags. The fabric
provides a surface on which dust collects
through the following four mechanisms:
•Inertial collection
•Interception
•Brownian movement
•Electrostatic forces
Evaluation of bag filters for industrial boilers:
• High cost (investment, maintenance & filter bags)
• Difficult to handle sulphur and sparks
• Not robust (one faulty bag destroys efficiency)

13. Control of particulate emissions using cyclones
Mechanism
Main process of wet scrubber
Wet scrubbers relay on the liquid spray to
remove dust particles from the gas stream.
It is also useful in fume extraction systems.
It removes air pollutants by inertia of
diffusional impaction, reaction with
absorbent or reagent slurry or absorption
into a liquid solvent. The inlet gas stream
usually enters the bottom of the tower and
moves upward, while liquid is sprayed
downward from one or more levels.
Evaluation of wet scrubbers for industrial boilers:
• High cost (large water treatment plant)
• Difficult to separate fine particulate
• Sulphur control costly & difficult

14. Control of particulate emissions using cyclones
History:
1975 - 1980 work with Prof. Stairmond (UK)
Cyclones for coal fired gas turbine 80 MW PFBC
1993 – 1998
basic research in
cyclone technology
Cape Town
development center

15. Control of particulate emissions using cyclones
Project 1996 / 97
30 year old Büttner solid fired wood chip dryer equipped
with low efficiency cyclone. Emission > 650 mg / Nm3
Solution:
Step 1 = retrofitting of high efficiency cyclones
Reduction of emission to < 100 mg / Nm3
First idea of agglomeration spray in 1997
Step 2 = installation of THERMAX agglomeration sprays
upstream of cyclones
Reduction of emission to < 20 mg / Nm3

16. Control of particulate emissions using cyclones
What is the agglomeration spray?
•Water spray with very fine droplets
•Fully evaporative (dry system)
•Droplets capture small particles
•and agglomerate them
•Larger particles are easily collected
Typical water consumption
30 liter / t steam generation

17. Control of particulate emissions using cyclones
High efficiency cyclone plant
with fully evaporative
fine agglomeration sprays
(Installation 1997)
Efficiency > 99 %
Emission < 20 mg / Nm3

18. Control of particulate emissions using cyclones
Cyclones
Cyclones are inertial
separators that operate on
the principle of centrifugal
force to remove particles
from gas streams. A
standard cyclone design is
able to remove particles
that have a size greater
than 20 μm.

19. Control of particulate emissions using cyclones
Cyclones
Cyclones can be used as it is or combined
with other control device. Cyclones are used
to pretreat the gas stream by removing the
purge particles while the second device will
function to collect smaller particles present at
a much reduced particulate loading but at
higher collection efficiency.

20. Control of particulate emissions using cyclones
 The dirty airs enter
the side.
 The airs swills
around the cylinder.
 Particulate falls out
from the bottom of
the cone and out.
Dust discharge

21. Control of particulate emissions using cyclones
Working principle
The working principle of the cyclone is as follow:
 The gas stream enters the cyclone in a manner that spirals around
inside of the cyclones.
The particles with a great inertia will be forced to the outside walls of
the device.
The particles will then fall to the cone to the collection hopper due to
the collision with the outside walls of the cyclone.
The clean gas will then rise near the center and is exhausted through
the top of the device.
There are two methods that cause the gas to spin in the cyclone.
VII. One of it's by introducing the gas to the device in a tangential
manner. The gas will curve around the body of the device.
VIII. The second method is by using axial vanes at the inlet of the
cyclones which will cause the gas to spin when it passes through the
vanes.

22. Control of particulate emissions using cyclones
Commercial applications of high efficiency cyclones:
BurnerMax
Fluidized bed furnace
High efficiency cyclones
operating at 400 C

23. Control of particulate emissions using cyclones
Current CyDesign specifications for
advanced cyclone technology:
Integrated cyclone system with
fully evaporative agglomeration
water spray (20 l / h per cyclone)
To provide a robust, economic,
low maintenance,
very high performance,
flue gas cleaning system

24. Control of particulate emissions using cyclones
Cyclone parts are manufactured to high precision as
erosion & corrosion resistant castings
Wax dies
Cyclone vortex blade ring
with pressure recovery Castings

25. Control of particulate emissions using cyclones
Advantages
• Relative simplicity and few
maintenance problems
• Relatively low operating pressure
drop (for the degree of particulate
removal obtained) in the range of
approximately 5–15 cm (2–6 inches)
water column
• Temperature and pressure
limitations imposed only by the
materials of construction used
• Dry collection and disposal
• Relatively small space requirements

26. Control of particulate emissions using cyclones
Disadvantages:
Low collection efficiency due to:
• Bad manufacturing quality
• Lack of maintenance (blockage of cyclone cells)
• Inability to handle sticky materials
But cyclone system advantages are low cost and robust installation
Can a cyclone reach efficiencies of ESP / Bag filter / Wet scrubber?
This question triggered our cyclone development Program
in 1994 to improve cyclone efficiency and to invent the
“dry spray agglomeration principle”

27. Control of particulate emissions using cyclones
Examples where the common control devices used
Common control devices Pollutants Examples where they used
Electrostatic precipitators Particulate matters Power plants ,steel and paper
mills, cement plants ,oil refineries
Bag houses fabric filter Particulate matters Steel mills, fertilizer plants and
other industrial processes
Wet scrubber Gasses ,vapors , solid particles, Coal burning power plants:
liquid particles facilities that emit sulphur oxide,
hydrogen sulphide,ammonia and
other gasses that can be absorbed
in the water and can neutralized
with the appropriate reagent
Cyclones Large particulate matters Wood working shops, cotton gins,
rock crushers, cement plants

28. Control of particulate emissions using cyclones
Selection criteria
ESP Bag house Scrubber High efficiency
Cyclones
Emission 100 30 200 < 100
mg/Nm 3
Reliability ++ + ++ ++++
Cost ++++ ++++ +++ +

29. Control of particulate emissions using cyclones
Outlook:
Its necessary to
control the
particulate
emissions
For a cleaner
Environment!