This lecture explains Ash Handling Plant, Economizer, Boilers and CLASSIFICATION OF BOILERS, Water tube and fire tube, Impulse & Reaction turbines

1. The Ash from the boiler is collected in two forms:
1. Bottom Ash(Slurry):It’s a waste which is
dumped into a Ash Pond
2. Fly ash: Fly ash is separated from Flue Gases
in ESP(Electro static Precipitator).
Ash Handling Plant
Fly Ash &
Flue
Gases
Economizer ESP
Bottom
ash(wet ash)
Ash Pond
Boiler
Cylo
Cement Factory
Economizer : Reduces the temperature
Chimney
Fly ash
Flue Gases
Flue Gases

2. Economizer
• Flue gases coming out
of the boiler carry lot of
heat. An economizer
extracts a part of this
heat from flue gases
and uses it for heating
feed water. This use of
economizer results in
saving coal
consumption and
higher boiler efficiency

3. Air preheaters
• After flue gases leave
economizer, some further
heat can be extracted from
them and used to heat
incoming heat. Cooling of flue
gases by 20 degree centigrade
increases the plant efficiency
by 1%.
• Air preheaters may be of
three types
 Plate type
 Tubular type
 Regenerative type

5. Boiler is a closed vessel in which water under pressure is
transferred into steam by the application of heat.
In the furnace, the chemical energy in the fuel is converted
into heat.
It is the function of the boiler to transfer this heat to the
water in the most efficient manner.
A boiler should be designed to absorb the maximum amount
of heat released in the process of combustion.
Boiler

6. CLASSIFICATION OF BOILERS
• According to what flows in the TUBE
1. Water tube.
2. Fire tube.

7. A fire-tube boiler is a type of boiler in
which hot gases from a fire pass
through one or more tubes running
through a sealed container of water.
The heat energy from the gases
passes through the sides of the tubes
by thermal conduction, heating the
water and ultimately creating steam.

8. Boiler Types and Classifications
• Fire Tubes submerged in water
Application
• Used for small steam capacities
( upto 25T/hr and 17.5kg/cm2
Merits
• Low Capital Cost and fuel
Efficient (82%)
• Accepts wide & load
fluctuations
• Packaged Boiler
Fire Tube Boiler

9. Fire – tube Boilers

10. A water tube boiler is a type of boiler in which water
circulates in tubes heated externally by the fire. Water
tube boilers are used for high-pressure boilers. Fuel is
burned inside the furnace, creating hot gases which
heats water in the steam-generating tubes.

11. Boiler Types and Classifications
Water Tube Boiler• Water flow through tubes
• Water Tubes surrounded by hot
gas
Application
• Used for Power Plants
• Steam capacities range from
4.5- 120 T/hr
Characteristics
• High Capital Cost
• Used for high pressure high
capacity steam boiler
• Demands more controls
• Calls for very stringent water
quality

12. Water tube boilers
•

13. •

14. A steam turbine is a thermo-
mechanical device that extracts
thermal energy from pressurized
steam, and converts it into rotary
motion.
Steam turbine

15. Steam
Steam is vaporized water. It is a transparent gas. At standard
temperature and pressure, pure steam (unmixed with air, but in
equilibrium with liquid water) occupies about 1,600 times the volume
of an equal mass of liquid water.
Saturated steam is steam at equilibrium with liquid water at the
same pressure and temperature.
Superheated steam is steam at a temperature higher than its
boiling point at a given pressure

16. Impulse & Reaction turbines
An impulse turbine has fixed nozzles that orient the
steam flow into high speed jets.
These jets contain significant kinetic energy, which the
rotor blades, shaped like buckets, convert into shaft
rotation as the steam jet changes direction.
A pressure drop occurs across only the stationary
blades, with a net increase in steam velocity across the
stage.

17. Reaction turbine
In the reaction turbine, the rotor blades themselves are arranged
to form convergent nozzles.
This type of turbine also makes use of the reaction force produced
as the steam accelerates through the nozzles formed by the rotor.
Steam is directed onto the rotor by the fixed vanes of the stator.
It leaves the stator as a jet that fills the entire circumference of
the rotor.
The steam then changes direction and increases its speed relative
to the speed of the blades.
A pressure drop occurs across both the stator and the rotor, with
steam accelerating through the stator and decelerating through
the rotor, with no net change in steam velocity across the stage but
with a decrease in both pressure and temperature, reflecting the
work performed in the driving of the rotor.

19. Working of steam turbine based power plant

20. Working
•Steam is generated in steam generator and supplied to steam
turbine at high pressure. (Usually sub critical pressure)
•This steam enters the high pressure rotor and expands , to
produce work.
•Low pressure turbine stage is provided to extract more amount of
work from the steam leaving into the condenser.