2. OVERVIEW
NTPC Ltd, India’s largest power company, was set up in 1975 to
accelerate power development in India.
NTPC-BRBCL Nabinagar project has capacity of 1000 MW.
It has 4 units, each of 250 MW.
Total area of land acquired for the project is approximately 1700
acres, which is near the Dhundhua village used for plant, township
and ash disposal area.
Water requirement: 4300 cubic m/hr as makeup water of cooling
tower and 5900 cubic m/hr for ash water recirculation system.
3. CONTENTS
INTRODUCTION ABOUT BOILERS
COAL ANALYSIS
FUEL OIL
FIRING IN BOILERS
COAL BUNKERS
COAL MILLS
PA, FD AND ID FANS
AIR PREHEATER
ESP
OVERVIEW
5. BOILER
A Boiler is a closed vessel in which water under pressure Is transformed
into steam by application of heat. The primary function of coal & oil
burning system in steam generation process is efficient conversion of
chemical energy of fuel into heat energy. This heat energy is transferred
to water which further used to convert water into steam using Rankine
cycle.
Controlled Circulation, Radiant Reheat, Single Drum, Top Supported,
Balanced Draft Furnace
Tilting Tangential type Firing
Steam Generating Capacity of 1675 T/Hr at 172 Bar & 5400C
340 T/Hr of Pulverized Coal (Calorific Value 3300 kcal/Kg) is Fired
Generates 2240 T/Hr of Flue Gas at 110-1200C and 150 T/Hr of Ash as
waste
6. COAL ANALYSIS
TYPE
Anthracite
Semi-Anthracite
Bituminous
Semi Bituminous
Lignite
Peat
PROPERTIES
High Calorific value
High Calorific value
Medium Calorific value
Medium Calorific value
Low Calorific value
Very Low Calorific value
8. FUEL OIL
Three liquid fuels used in power plants
Heavy Fuel Oil (HFO)
LSHS (Low Sulfur Heavy stock)
High speed Diesel (HSD)
Oil firing is preceded by
Lowering viscosity and increasing the flow on heating
for better combustion.(110-125oC)
Droplet formation on atomization (by steam/
compressed air)
Combustion initiation by High energy spark ignition
9. FIRING IN BOILERS
Tangential corner firing:
• Tangential firing is a
method of firing a fuel to
heat air in thermal power
stations.
• The flame envelope rotates
ensuring thorough mixing
within the furnace,
providing complete
combustion and uniform
heat distribution.
10. COAL BUNKERS
Coal Bunkers at BRBCL
• Coal bunkers are used to
feed coal to coal mills from
the conveyer.
• The coal from conveyer first
goes to coal bunkers.
• There are seven coal
bunkers in one boiler unit of
BRBCL.
11. COAL FEEDER
Coal feeder at BRBCL
• From the coal bunkers the
coal goes to feeder.
• Feeder regulates the flow of
coal into the mills as per the
requirement
12. COAL MILL
Coal mill at BRBCL
• The coal from feeder is supplied
to mills where the coal is
pulverised.
• It is reduced to fineness such
that 70-80 % of it passes through
200 mesh sieve.
• The pulverised coal is then
transported to burners by the
heated air from PA fan.
14. PRIMARY AIR(PA) FAN
Primary air fan at BRBCL
• This fan sucks atmospheric air and
sends it to APH where it gets heated
up and then reaches the coal mills.
• To transport pulverized coal to the
furnace the speed of PA fans 1400
rpm and they supply 83800 m3 per
hour.
• It is used to remove the moisture
content from the powdered coal and
transport it to boiler.
15. FORCED DRAFT FAN(FD FAN)
Forced draft fan at BRBCL
• The main work of FD fan is
to provide air to the
furnace for combustion
• Atmospheric air is sucked by
FD fan; this air is taken to
the APH.
• After getting heated it
enters the furnace
16. INDUCED DRAFT FANS(ID FANS)
Induced draft fan at BRBCL
• The induced draught fans are
single stage, double inlet
centrifugal fans.
• The flue gases after passing
through the electrostatic
precipitator come to ID fan.
• Flue gases are taken out by
means of induced Draft fans and
the furnace is maintained under
vacuum
• It is installed after ESP
17. AIR PREHEATER
Air preheater at BRBCL
• Air preheater are heat
exchanger to preheat or air
heating of the combustion air
by means of flue gas, steam,
water or thermal oil.
• It is divided into 3 parts (1part
for PA fan, 1part for FD fan
and other part for FLUE gas).
