2. COAL HANDLING PLANT
1. Importance of CHP in a Fossil Fuel Based Thermal Power Plant
2. Tarrif and Coal Cost
3. How a CHP is designed
4. Safety aspects in CHP
5. Protection and interlocks
6. Operation
7. Maintenance
8. Components
9. Contracts
10. Environmental norms
11. Hazards
12. Organization chart.
13. Fire Protections
3. COAL HANDLING PLANT
14. CERC NORMS FOR GENERATORS
15. ELECTRICITY GENERATION REGULATED BUSINESS
16. ROLE OF CHEMISTRY
17. LMI, OGEN , OIN AND OTHER CC OS GUIDELINES
18.BIOMASS PELLET FIRING
4. Share of Coal in Power
Generation
Advantages of Coal Fuel
•Abundantly available in
India
•Low cost
•Technology for Power
Generation well developed
•Easy to handle,
transport, store and use
Shortcomings of Coal
•Low Calorific Value
•Large quantity to be
Handled
•Produces pollutants, ash
•Disposal of ash is
Problematic
•Reserves depleting fast
•India’s Coal Reserves are estimated to be 255 billion tonnes.
•Present consumption is about 450 million tonnes.
Coal
55%
Gas
10%
Diesel
1%
Hydel
26%
RES
5%
Nuclear
3%
5. NCPS DADRI at a glance
• IT HOUSES COAL,GAS AND SOLAR BASED GENERATION
COAL (4 x 210 MW + 2 x 490 MW)
GAS (4 x 130.19 MW + 2 x 154.51MW)
SOLAR 5MW
• ANOTHER FEATURE IS 1500 MW - 500 kV HVDC LINK.
• LARGEST SWITCHYARD IN ASIA IN TERMS OF POWER HANDLING
CAPACITY (4500 MW). 8 OUTGOING FEEDERS.
• DRY ASH HANDLING SYSTEM, FIRST IN ASIA.
• NDCT COOLING TOWERS
8. CHP
COAL HANDLING PLANT
• TRANSPORTS COAL FROM TRACK HOPPERS AND
WAGON TIPPLERS TO BUNKERS AT MAIN PLANT
• THROUGH PADDLE FEEDERS,CONVEYOR BELTS,
CRUSHERS ETC
• ALSO STACKS THE COAL IN STACKYARD AND RECLAIMS
WHEN NEEDED THROUGH STACKER RECLAIMER
CHP
- 250 MM - 20 MM
9. SOURCES OF COAL
FSA (LINKAGE)
• CCL: 44.00 LMT/ YEAR (STAGE-I)
• ECL: 33.32 LMT/ YEAR ( STAGE-II)
REST COAL REQUIRMENT MET WITH IMPORTED AND
MOU / E-AUCTION COAL FOM NCL.
• Quality of coal :
• F Grade (raw coal) -3800 kcal/ kg
• E Grade (washed) -4200 kcal/ kg
• Imported coal -5700 kcal/kg
10. COAL CONSUMPTION
• AT FULL LOAD OPERATION PER DAY= 25000 TONNES
• 200 MW UNIT (APPROX 130 T/HR)
• 500 MW UNIT (APPROX 300 T/HR)
11. Anthracite
Semi-anthracite
Bituminous
Semi-Bituminous
Lignite
Peat
High CV, low VM
High CV, low VM
Medium CV, medium VM
Medium CV, medium VM
Low CV, high VM, high
TM
Very low CV, high VM &
TM
13. MGR
COAL @ NTPC DADRI
ONE WAGON CAPACITY: 60-65 TONS
ONE RAKE : 59 WAGON (APPROX 3600 TONS)
TOTAL RAKES IN A DAY~ 8 TO 9
WAGON TYPE:
• BOBR-BOTTOM DISCHARGE (PNEUMATIC)
• BOX-N (OPEN TOP)
14. MGR
COAL @ NTPC DADRI
TYPES OF WAGONS UNLOADED AT
BOBR TRACK HOPPER
BOXN WAGON TIPPLER
15.
16. 3.INFRASTRUCTURE OF MGR-TRACK & BRIDGES AT NTPC DADRI
(A) TRACK
• Total length 45 KM+09 KM (Stg-II)= 54 KM
• Rail 52 Kg (T-12) 1st Quality
• Track Section SWR (Short Welded Rail)
• Maximum Gradient 1 in 250
• Total Track laid on PSC Sleepers for 52 Kg Rail except Curve no. 6
which is laid on Wooden Sleepers, interlacing is done by PSC Sleepers
for required strength of the track .These wooden sleepers are to be
replaced with PSC Sleepers.
17. COAL UNLOADING AT NCPS DADRI
o TRACK HOPPER = 02 NOS
o WAGON TIPPLER = 02 NOS
ALL THE ABOVE UNLOADING POINTS HAVING
INDIVIDUAL LINES FOR TO & FRO MOVEMENT UPTO
R&D YARD.
18. FSA LINKAGE
CCL: 57.10 LMT/ YEAR (STAGE-I)
E CL: 15.00 LMT/ YEAR ( STAGE-II)
BCCL: 8.00 LMT/YEAR (STAGE-II)
4. COAL COORDINATION
19. Sourcing of fuel (coal)
Stage-I
Mostly from Bachra, Piparwar mines of North Karanpura zone of
CCL
FSA quantity – 57.1 LMT per year for stage-I units
Washed Coal (approx. 70%)
Raw Coal (approx. 30%)
Stage-II
FSA was signed with ECL
FSA quantity – 15.00 LMT per year.
Supplies raw coal mostly from Pandeshwar, Salanpur mines
FSA signed with BCCL for 8.00 LMT per year.
Supplies raw coal mostly from Jharia area mines.
Total tie up : 80.10 LMT
20. TYPE OF WAGON BOBR (EOL) BOXN
FREE TIME UPTO 2:29HRS UPTO 07:00 HRS
CREDIT (1 HR)
FOR COMPLETE RAKE
IF UNLOADING TIME IS
LESS THAN 01:30 HRS
N/A
ADJUSTMENT OF
CREDIT HOURS
QUATERLY N/A
DEMMURAGE AND FREE TIME
23. CHP O&M Constraints:
Coal handling Plants are designed for a particular type of coal.
Since coal quality keeps in changing, therefore coal handling
plants bound to have some problem.
We are receiving big boulders in rakes receiving from specially
from ECL Mines. Unloading these rakes without any demurrage
and keeping equipments break down low are big challenges for
us.
24. TRACK HOPPER
• UNDERGROUND HOPPER AT POWER STN END FOR
UNLOADING
• TRACK HOPPER 1 & 2 FOR ST-1 (2x210MW) AND ST-2
(2x490MW) RESPECTIVELY
• TRACK HOPPER –1 CAPACITY : 6000 TON
• TRACK HOPPER –2 CAPACITY : 6000 TON
• TYPE OF HOPPER - RCC UNDERGROUND
29. CHP Equipments Description:
Paddle feeder
Stage-1 Stage-2
Make M/s Elecon M/s Elecon
Mode of Operation Rotary Rotary
Drive Electro- Hydraulic Electro-Hydraulic
Capacity(Rated) 875 TPH 1050 TPH
Travel Speed 2 Meter / Min 2 Meter / MIn
No. of Paddle wheel
Blades
06 06
RPM of Plough Blades 2-9 2-11
40. PRIMARY CRUSHERS
The primary coal crushers may be of different
types such as: (1) coal jaw, (2) coal hammer,
and (3) ring granulator.
Primary crushers are heavy-duty rugged
machines used to crush COAL of (−) 1.5 m
size. These large-sized ores are reduced at
the primary crushing stage for an output
product dimension of 10–20 cm.
41. SECONDARY CRUSHER
The secondary crusher is mainly used to
reclaim the primary crusher product. The
crushed material, which is around 15 cm(-
200MM) in diameter obtained from the COAL
MINES, is disposed as the final crusher
product. The size is usually between 0.5 and
2 cm in diameter so that it is suitable for
grinding.(-20MM)
52. CHP Maintenance System:
Equipment wise Overhauling Schedule
S.No
.
Equipment Name Overhauling
Schedule
1 Coal Crusher Once in Year
2 Paddle Feeder Once in Two Year
3 Tripper Once in Two Year
4 Stacker Reclaimer Once in Two Year
5 Wagon Tipper Once in Two Year
6 Air Compressor Once in Year
7 Conveyor System Once in two Year
55. CHP Equipments Description:
Conveyor System
Stage-1 Stage-2
Conveyor capacity(TPH) 1400 1400
Belt Speed (m/s) 3 3
Belt Width (mm) 1400 (except A1A,A1B) 1400
Belt Cover Grade FR FR
Carcass EP(Polyester Polyamide) EP(Polyester
Polyamide)
Belt Strength(N/m) 630 to 1250 1000 to 1600
Top / Bottom Cover 5 / 3 5 / 3
Troughing Angle(Degree) 35 35
Max Inclination (Degree) 8 9
Total No. of Belt 16 25
Total Population (m) 12674 10836
56. CHP Equipments Description:
Track Hopper
Stage-1 Stage-2
Type of Track Hopper RCC Under
Ground
RCC Under Ground
Length of Track Hopper 201.6 m 300 m
No. of Hopper 66 100
Capacity 6000 mt 6000 mt
Type of Wagon U/G BOBR BOBR
Mode of Bottom release Pneumatic (5-6 kg) Pneumatic (5-6 kg)
Mean of Evacuation Paddle Feeder Paddle Feeder
Out-Coming Conveyor 1A/1B 8A/8B
57. CHP Equipments Description:
Wagon Tipple
Stage-1 Stage-2
Type of Wagon Tippler Rotaside Rotaside
Make M/s L&T Ltd. M/s Elecon
Drive Electro-Mechanical Hydraulic
Clamping Arm 06 no., Gravity base 04 no., Hydraulic
Capacity 12 Tips / Hr 20 Tips / Hr
Type of Wagon U/L Box N Box N
Mean of Evacuation Vibro feeder Apron feeder
Out-Coming Conveyor Conv. A1A/A1B Conv. 9A / 9B
71. MILL/PULVERIZER
• PULVERIZES COAL FROM 20 MM SIZE TO 200 MESH
SIZE i.e > 70% SHOULD PASS THRU 200 MESH
(200 HOLES/SQ.INCH)~ 75 MICRON
• BOWL ROTATED BY MOTOR AND 3 ROLLERS AT 120
DEG APART (BOWL MILL)
• PULVERIZED COAL IS TAKEN TO BOILER BY HOT +
COLD PRIMARY AIR
MAIN PLANT
73. Hot Air
Gate
Cold Air
Inspection Door Coal
Mill
Hot Air
Duct
Scraper
Housing
Hot Air Damper
Gear
Housing
Grinding
Chamber
Discharge
System
Classifying
System
Coal from bunker
Grinding
Rolls
BOWL MILL
76. CARNOT ENGINE
•1-2 - Isothermal Expansion at T1ºK
•2-3 - Adiabatic Expansion up to T2ºK
•3-4 - Isothermal Compression at T2ºK
•4-1 - Adiabatic Expansion up to T1ºK
For Carnot Cycle η = 1 - T2
T1
T1 = Temp. of heat source
where
T2 = Temp. of heat sink
Carnot Cycle gives maximum possible thermal efficiency which can be
obtained between any two Given temperature limits.
1
2
3
4
S
T T1
T2
77. RANKINE CYCLE
The Carnot Cycle is theoretically most efficient, but it is having practical difficulties.
For steam power plant, practical thermal cycle was suggested by Rankine, called
Ideal cycle.
3-3’ – BFP raises pressure from p2 to p1
3’-4 – Heating In feed heaters & eco
4 -1 – Heating In boiler
1-2 – Work done in Turbine from p1 to p2
2-3- HEAT REJECTION IN CONDENSER
1
2
3
3’
4
T
S
T1
T2
p1
p2
78. Q1-Q2 W Useful work
η = ------- = --- = ---------------
Q1 Q Heat supplied
Rejected Heat
η = 1 - --------------------
Useful Heat
T1 - T2 T2
η Carnot = -------- = 1 - ---
T1 T1
To achieve more efficiency T2 should be as low as
possible and T1 should be as high as possible
THERMAL EFFICIENCY OF
RANKINE CYCLE
80. Steam generation principle
Steam power plants operate
on Rankine Cycle, DM water
as working fluid.
Sensible heat is added in
economiser +furnace
Steam generation takes
place in waterwall.
Heat transfer in furnace and
enclosed superheater takes
place thru radiation.
condenser
CEP
LPH
BFP
HPH+Eco
w/w
SH
HPT
IPT
RH
LPT
81. Superheater & Reheater
Heat associated with the flue gas is used
in superheaters & Reheater, LTSH,
Economiser.
Maximum steam temperature is decided
by the operating drum pressure and
metallurgical constraints of the turbine
blade material.
Reheating is recommended at pressure
above 100 ksc operating pressure.
Reheating is done at 20-25% of the
operating pressure.
Carbon steel, alloy steel & SS used for
tubing of SH & RH.
condenser
CEP
LPH
BFP
HPH+Eco
w/w
SH
HPT
IPT
RH
LPT
82. Adiabatic Expansion in
Turbine
Constant Pressure Heat
Rejection in Condenser
Pump Work
Sensible heat Addition in
Economizer
ENTROPY
T
E
M
P
E
R
A
T
U
R
E
Latent Heat Addition in
Evaporator (constt. Pressure) Super Heating
L + V
BASIC RANKINE CYCLE (SUB-CRITICAL)
83. BASIC CONSIDERATIONS
Net change in internal energy is zero
Net heat transfer = Net work output
Qi –Qr = Wo-Wi
Efficiency = 1-(Qr/Qi)
BOILER
CONDENSER
PUMP TURBINE
Qi
Wi
Qr
Wo
84. 1. EFFECTS OF LOWERING THE CONDENSER PRESSURE
Lowering condenser pressure lowers
the temperature at which
condensation takes place thereby
increasing the cycle efficiency.
LIMITATION :
Lower limit is the saturation pressure
corresponding to the temperature of
cooling media.
Creates possibility of ‘Air Leakage’ into
the condenser
Increases moisture content of the steam
at the final stages of turbine that decreases
the turbine efficiency and causes erosion in
turbine blades.
85. 2. EFFECT OF SUPERHEAT
Superheating the steam to higher
temperature without increasing the boiler
pressure increases thermal efficiency.
It also decreases the moisture content of
the steam at the turbine exit.
LIMITATION:
Highest temperature of superheated
steam is limited by the metallurgical
constraint.
86. 3. EFFECT OF INCREASING THE INLET PRESSURE
Increasing the inlet pressure
raises the mean temperature at
which heat is added in the
boiler thereby increasing the
efficiency.
LIMITATION
Increases moisture content at
the final stages of the turbine
that decreases the turbine
efficiency and erodes turbine
blades.
87. POWER PLANT CYCLE
The Working fluid is Water.
Working principle is based on the Modified Rankine
Cycle ( With Single Re- Heat )
The closed cycle consists of three intermediate cycles:
Condensate cycle
Feed Water Cycle
Steam Cycle
88. LPH 1
GSC
LPH2
LPH3
DEA D/C
COND
CEP
Sensible Heat addition to condensate extracted
from condenser by CEP
Starts from Condenser and ends at De- Aerator
GSC, LPH 1,2,3 and Drain Cooler are the heat
exchangers
Driving force is CEP
CONDENSATE CYCLE
89. Sensible Heat addition to feed water being pumped by BFP
Starts from De- Aerator and ends at Economizer
HPH 5 and HPH 6 are the heat exchangers
Driving force is BFP
HPH 5
HPH6
ECONOMIZER FST
BFP
FRS
FW CYCLE
91. BOILER MEANS ANY CLOSED VESSEL
EXEECDING 22.75 L(5 Gallons) IN CAPACITY
WHICH IS EXCLUSIVELY USED FOR
GENERATING STEAM UNDER PRESSURE AND
INCLUDES ANY MOUNTINGS OR OTHER
FITTINGS ATTACHED TO SUCH A VESSEL
WHICH IS WHOLLY OR PARTLY UNDER
PRESSURE WHEN STEAM IS SHUT OFF .
92. Fire-Tube Boilers Fire-tube
boilers rely on hot gases
circulating through the boiler
inside tubes that are
submerged in water
• Electric Boilers Electric
boilers are very efficient
sources of hot water or
steam, which are available
in ratings from 5 to over
50,000 kW
93. Water Tube Boiler:
Here the heat source is
outside the tubes
and the water to be
heated is inside.
Most high-pressure
and large boilers are
of this type. In the
water-tube boiler,
gases flow over
water-filled tubes.
These water-filled
tubes are in turn
connected to large
containers called
drums.
94. 1. FUEL FIRING SYSTEM.
2. DRAFT SYSTEM.
3. STEAM GENERATION.
4 ASH COLLECTION SYSTEM
Main systems of BOILER
102. COAL COMBUSTION PROCESS
At Room Temp. Oxygen is absorbed – Its an
Exothermic reaction. Heat is given out.
At 155 deg. C, Volatile matter released
At 65 deg. C, surface moisture released
At 75 deg. C, Oxidation starts
At 190 - 250 deg. C, start of Thermal
decomposition.
At 250 - 300 deg. C, SELF SUSTAINED
COMBUSTION (FIRE)
104. MAIN PLANT
TURBINE
•THREE CYLINDER: HP,IP AND LP CYLINDER
•ROTATES AT 3000 RPM (DECIDED BY GRID FREQ
AND GENERATOR POLE)
n=120f/P
n=speed, f=frequency of grid, P=no of poles of generator
105. TURBINE
• HP TURBINE (SINGLE FLOW)
• IP TURBINE( DOUBLE FLOW)
• LP TURBINE (DOUBLE FLOW)
NO OF STAGE
• HP TURBINE (25 STAGE)
• IP TURBINE( 20+20 STAGE)
• LP TURBINE(8+8 STAGE)
115. STEPPING UP VOLTAGE
GENERATOR & GENERATOR TRANSFORMER
400 KV BUS IN
SWITCHYARD
GENERATOR
TRANSFORMER
GENERATOR
15.75 KV 400 KV
CIRCUIT BREAKER
OUTGOING
LINE
118. The liquid fuels used in power plants are
Heavy Fuel Oil (HFO)
LSHS (Low Sulfur Heavy stock)
High speed Diesel (HSD)
Light diesel oil (LDO)
Oil firing is preceded by
Lowering viscosity and increasing flowability on heating for
better combustion in given turn down ratio(125oC)
Droplet formation on atomization (by steam/ compressed air/
mechanical pressurization)
Combustion initiation by High energy spark ignition (HEA)
