arvind fta
TRANSCRIPT
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SUPER CRITICAL
TECHNOLOGYBy- Arvind Kumar Yadav
(Executive Trainees-09)Employee No -101917
Operation Group - 3
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Te mp e ra t u re (
0 C )
Enthalpy
Critical point (221.25 bar, 374.15 0 C)
S a t u r a t e d v a p o u r l i n e
Wet Region
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Reasons for changeover from Sub
Critical to Super critical Higher Cycle efficiency. Conservation of fuel resources (Coal)
Reduction of Pollutants - SO X& NO X
Reduction in CO 2 emission (linked to globalwarming)
Better economy in power generation where fuel costsare high and pollution control requirements arestringent
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Steam Generation Process
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Super critical Operation
SC Steam generator Boiler Steam Pressure above the critical point Critical Point
221 bar, 374 c
S
T
1
2
3
4
Entropy
Temperatu
1 - 2 Feed Water Pumping Process 2 - 3 He at addition in the Feed
Water Heaters & Boiler 3 - 4 Expansion in HP Turbine 4 - 5 Reheating in Boiler 5 - 6 Expansion in IP & LP Turbine 6 - 1 Heat rejection in Condenser
5
6
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Approximate improvement in Cycle
Efficiency
Pressure increase : 0.005 % per bar
Temp increase : 0.011 % per deg K
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SUPERCRITICAL ADVANTAGESEnhancements Plant efficiency 0.69% to 1.64% Fuel tolerance More tolerant to coal quality changes
Reductions Coal Consumption Ash production CO 2
SO 2
NoxImprovements Startup time Sliding Pressure Operation Load following capability
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Reduction in CO 2, SO 2 and NO x between 1.79% to4.24%
Reduction for 500 MW at 68.5% PLF per year is- CO
278300 tons
- SO 2 365 tons
- No x 71 tons
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Critical PipMain Stea
Si
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Steam TuCasings
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TurbineBoiler F
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Types of Boilers
Drum type
Once Through
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Drum type boiler Steam generation takes place in furnace water walls
Fixed evaporation end point - the drum
Steam -water separation takes place in the drum
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Drum type boiler Natural Circulation Boiler
Circulation thru water walls by thermo-siphon effect
Controlled Circulation Boiler
At higher operating pressures just belowcritical pressure levels, thermo-siphon effectsupplemented by pumps
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The mass flow rate thru all heat transfer circuits
from Eco. inlet to SH outlet is kept same except at
low loads wherein recirculation is resorted to
protect the water wall system.
THE CONCEPT
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Major differences from Drum type boiler :
Evaporator system Low load circulation system
Separator
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Evaporator system
Formed by a number of parallel tubes Tubes spirally wound around the furnace to reduce
number of tubes and to increase the mass flow ratethru the tubes
Small tube diameter Arrangement ensures high mass velocity thru the
tubes
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VERTICAL TYPE
SPIRAL TYPE
Furnace Arrangement
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Spiral wall arrangement
Advantage1.By spiraling around the furnace, every tube is part of all four walls
which means that not only the difference in the length of the paralleltube is minimized but also the heat pick up of individual tubes isparticularly equalized.
2.At low load also sufficient cooling of the tubes can be assured.
Disadvantage Complicated manufacturing, construction of tubes. Greater ash accumulation on water walls.
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Straight Tube Wall vs. Spiral Tube Wall
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Low load circulation system : At part loads once -thru flow not adequate to cool the
tubes.
To maintain required mass velocities boiler operates oncirculating mode at low loads.
Excess flow supplied by feed pump or a dedicatedcirculating pump.
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LOW LOAD SYSTEM WITH CIRC. PUMP
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Separator
Separates steam and water during thecirculating mode operation
Runs dry during once-thru flow mode Smaller in size compared to drum in a
drum type boiler
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EATURES OF SUPER CRITICAL BOILEREATURES OF SUPER CRITICAL BOILER ::
FEEDWATER
PUMPECONOMISER WATER WALL/
EVAPORATORSEPERATOR SUPERHEATER
STORAGETANK
RECIRCULATION
PUMP
CONSTANT WATER WALL FLOW
FEEDWATER
PUMPECONOMISER
WATER WALL/EVAPORATOR
SEPERATOR SUPERHEATER
ONCE THROUGH FLOW OPERATION
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ONCE - THROUGH OPERATING
RANGE
540C, 255 Ksc
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HPT
IPTLPTCONDENSER
FEED WATER
FRS
STORAGE
TANK
SEPARATOR
BWRP
Spira
l wate
r walls
MS LINE
HRH LINE
VERTICAL WW
ECO I/L
ECOJUNCTION
HDR
ECO HGRO/L HDR
FUR LOWER HDR
FUR ROOFI/L HDR
DIV PANELS SH PLATENSH
FINALRH
FINAL SH
LTRH
ECONOMISER
290C, 302 KSC
411C,277Ksc
411C,275 Ksc
492C, 260 Ksc
3 0 5 C , 49 Ks c
457C, 49 Ksc
568C, 47Ksc
GLPT
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The sliding pressure operation is a control system in which the main steamis controlled by sliding pressure in proportion to the generation output.Steam quality at the turbine inlet can be changed at constant volume flowswhile keeping the turbine governing valve open. Utilizing sliding pressure,the thermal efficiency of the steam turbine is improved at partial operatingloads through decreasing thermodynamic efficiency as follows, bycomparison with constant pressure type operation:
(1) A smaller governing value loss enables improvement of high pressureturbine internal efficiency(2) Decrease of feed water pump throughput
(3) Boiler reheat steam temperature can be maintained at higher levelsbecause of higher temperatures in high-pressure turbine exhaust steam.
Sliding Pressure Operation
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Enthalpy Variations vs Pressure andBoiler Load
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Sliding pressure V/s Constant
pressureIn sliding operation, turbine inlet valves remains fully open duringnormal operation. As a result the live.Advantages
lower thermal stresses
Reduce pressure level at low loads prolong the life span of plantcomponents.
Overall reduction in power consumption
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Pressure Operation Mod
140
160
180
200
220
240
260
280
30 50 70 90 110
Boiler Load (%
Pressure(bar)
Constant pressure mode
Sliding pressureModified Sloding pressur
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REQUIREMENT OF WATER QUALITY
The contents of dissolved and undissolved solids and other materialshould be practically zero.
In order to maintain above conditions continuous purification of thereturn condensate by means of CPU is mandatory.
It employ the use of all volatile treatment in order to maintain thelow TDS in water.
O.T. Is recent method employed for the treatment of water/steamcycle
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Super Critical Technology in NTPCs Plant
Plants in advance stage of construction
3x660MWSipatSTPPStage-I 3x660MWBarhSTPPStage-I
Upcoming Plants
Barh-II,Bihar2x660MW
NorthKaranpura,Jharkhand3x660MW Darlipali,Orissa4x800MW Lara,Chattisgarh5x800MW Cheyyur,Tamilnadu3x800MW
Marakanam,Tamilnadu4x800MW Tanda-II,UttarPradesh-2x660MW Meja,UttarPradesh-2x660MW
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Thankyou !