Nicely describe everything about super critical technology in thermal power plant.This slide is very useful for the freshers.Anybody can get the basic fundamental idea about super critical technology from this slide. In India now we have to think some new technology for power sources as sub critical power plants are less efficient and emit more pollutant to the environment and the alternative is the 'Super Critical Power Plant'.

1. 1
Presented by
Raghab Gorain
Mid-Term Appraisal
Regional Learning Institute
NTPC Vindhyachal
A Maharatna Company
ACT-2016
Date/ 23rd May, 2017

2. Coal Storage
Conveyer Belt
Coal
Pulverizer
Furnace
Boiler
Turbine
Condenser
Generator
Transformer
Fly Ash
Chimney
ESP
DM
Plant
PT Plant
Cooling
Tower
Bus Bar
Overview OF Thermal Power Plant
Eco
Bottom
Ash
2

3. 3
Types Of Power Plants
Sub Critical
Super Critical
Ultra Supercritical
Disadvantages of Sub Critical
 High Coal consumption
 Low efficiency
 Emission of high pollutant
 Less capacity with high
Land capture
 More CO2 emission
 Large Boiler size
 High start up time require
Sub Super Ultra
Pressure
(kg/cm2)
<225 250-
270
>270
Temperature
(0C)
540-
565
565-
600
>600
Efficiency
(%)
35-38 42-47 48-55

4. 4
What is Super Critical Thermal Power Plant
Power plants that work above the critical point is called ‘Super
Critical’ power plant.
‘Supercritical’ is a thermodynamic expression describing the
state of a substance where there is no clear distinction between
the liquid and the gaseous phase.
Absolute press. Saturation Temp. Latent Heat
(Bar) (0C) (KJ/KG)
50 264 1640
150 342 1004
200 366 592
221 374 0
Critical pressure and temperature of water is
225 Kg/Cm2 and 374.15 0C

5. 5
Super Critical Power Plant
Pressure(Kg/Cm2)
125500
Temperature (0C)
374
Critical pressure and temperature of water is
225 Kg/Cm2 and 374.15 0C
225

6. 6
Super Critical Thermal Power Plant
Rankine Cycle
Super Critical Condition:
Temp: >374.15 0C
Press: >225 Kg/Cm2
Entropy
Temperature
240Kg/Cm2
Super
Critical
5900C
6
5
7
4
32a
2
1
4’
5’
6’
3’
1-2 >BFP work
2–3’ >Regeneration
3’-4’ >Superheating
4’-5’ >HPT expansion
5’– 6’ >Reheating
6’-7 >IPT & LPT Expansion
7-1 >Condenser Heat rejection
2-2a >Feed water heat addition (sub)
2a-3>In boiler drum heat
addition(Sub)

7. 7
METHODS OF INCREASING RANKINE
CYCLE EFFICIENCY
 Raising inlet temperature by superheating
 Raising inlet pressure of steam
 Dropping the final pressure and temperature
 Regenerative Heating
 Raising reheating temperature
Carnot Efficiency
h=(1- T2/T1)
T1=Source Temp. (or Steam Temp.)
T2=Sink Temp. (or Feed Water Temp.)

8. 8
Boiler of Thermal Power Plant
Types  Drum type
 Once Through
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
 Separated water mixed with incoming feed water
 Water flows in recirculation pathway

9. 9
Once Though Boiler
A boiler in which water
flows, without recirculation,
sequentially through the
economizer, furnace wall,
and evaporating and
superheating tubes.
Once-through boilers are better suited to frequent load
variations than drum type boilers, since the drum is a
component with a high wall thickness, requiring controlled
heating.So once through boiler is more suitable for fast start up
as well as for transient condition.

10. 10
Technology Used in Super Critical Boiler
 Vertical Tube
 Spiral Tube Vertical Tube
Advantages Disadvantages
Can be used in Large
Capacity Boilers
Uniform heating of water
doesn't occur
Tube are self supporting Tube leakages are very
frequent due to localized
heating
Corners are easier to form Less stable operation
Reduced Pressure Drop and
Auxiliary Power.
Presence of both water and
steam
Faster Erections due to
easier geometry
Travelling time water is less
because it's length is short

11. 11
Advantages Disadvantages
Can be used in boilers in any
Capacity.
Furnace walls are not self
supporting because they are
inclined.
Fabrication and installation
is difficult and time
consuming.
As the tubes pass through all
the furnace walls more
uniform heat absorption.
High stable operation
Evaporator steam outlet
temperature is more
uniform.
Spiral Tube Boiler
For super critical, spiral tube boiler is more suitable because of more heat
extraction, lower chance of tube leakage, high stable operation etc.

12. 12
Super Critical Thermal Power Plant
 Higher Efficiency. Increased upto 46%-47%
 Low coal consumption
 Low SOx, Nox emission to the environment.
 Reduction of auxiliary power consumption
 Reduction of requirement of ash dyke land
and consumptive water.
 Shorter start-up time.
 Significantly reduced CO2 emission.
Challenges
Advantages
 Materials Limitation, due to high thermal stress
 Water chemistry is more stringent
 High levels of corrosion
 Increased supervision and maintenance costs
 Limited scope for retrofitting opportunities

13. 13
Requirements of Tube Material
 Strength to resist rupture at design condition
 Ability to resist stress concentrations
 Resistance to oxidation, corrosion and erosion
 Ability to withstand damaging metallurgical changes
 Ease of fabrication
 Good physical properties to minimize thermal stresses

14. 14
Challenges In Super Critical Power Plant
Metallurgical
Challenge
Stainless steel which are usually used for boiler parts
are not suitable for SC and USC boilers because
 They do not have the enough creep strength to
resist the high pressure,
 Also there is high rate of oxidation at such high
temperature and pressures which are beyond the
capability of these materials to resist,
 Corrosion and erosion rate is very high in
supercritical condition.
Major components, such as
 In furnace tubing for the water walls
 Super-heater and re-heater sections
 Headers, external piping, and other accessories
require advancements in materials technology to
allow outlet steam temperature increases to reach
760°C (1400F).

15. 15
Heat surface Tube material Header material
Economizer SA-210 C SA-106 C
Furnace
Walls
SA-213 T12 SA-106 C
Super heater/
Reheater
SA-213 T12
SA-213 T23
SA-213 TP 304H
SA-213 TP347HFG
SA-335 P12
SA-335 P91
SA-335 P911
Steam Piping SA 335 P91
Comp-
oud
Chemical
Componant
Material
SA-
106C
C, Mn, P, Si, S Carbon steel
SA-
210 C
C, Mn, P, Si, S Carbon steel
SA-
335
P12
C, Mn, P, Si,
S,Cr, Mo
Alloy steel
SA-
335
P91
C, Mn, P, Si,
S,Cr, Mo
Alloy steel
Super Critical Power Plant’s Material
New alloys based upon 10% Cr. Mo.W.V.Nb.Ni.B are becoming available
for turbine rotors and casings for construction of 300-325bar/600-610C
steam turbines. Creep testing to 40,000h, together with large-scale
fabrication trails, has so far demonstrated reliable results. Hence,
turbine parameters of 600C/325bar can be considered achievable
Turbine

16. 16
Advanced control techniques should be developed to
optimize plant operation and maintenance
Maintain uniform temperatures across the boiler by
Control of burner parameters
Minimize carbon-in-ash or NOx formation in the same
way
Better match of load and firing during load changes, to
avoid temperature excursions and improve ramp rates
Improve reliability and repeatability of cycling procedures
Condition-monitor both boiler and turbine components
Forecast damages accumulation and allows targeted
preventative maintenance.
Ensure higher reliability of temperature sensors
Monitor high temperature fire side corrosion in super
heater section
Intelligent soot blower control
Control and Instrumentation

17. 17
Water Chemistry In Super Critical Boiler
Water chemistry in super critical boiler is very important as it
determines the life of boiler, deposits, heat transfer efficiency,
tube failure, chemical cleaning of boiler etc.
Importance of water chemistry much more due to the following
reasons:
 No boiler blow down or solid treatment.
 No physical separator of impurities. It will deposit on super
heater, reheater, and turbine blades.
Main parameters Parameters Sub critical Super critical
Silica(Feed water) <20 ppb <10 ppb
pH(feed, steam) 9.2- 9.5 9.2-9.6
DO(feed) <7 ppb <7 ppb
Conductivity <0.2 ms/cm <0.15 ms/cm
CPU Optional Must present

18. 18
Sub Critical vs Super Critical
Similarities
 Basic operation cycle is same-Rankine cyle
 Constructional features are also same except
in super critical drum less boiler is there.
 Equipment and philosophy are almost same. Like
APH, Economizer, PA, SA & ID, ESP, BFP, Turbine
CEP, Condenser etc…
Differents
Parameters Sub Critical Super Critical
Boiler Drum type Once Through
Efficiency(%) 35-37 42-47
Emission of CO2 Higher Comparatively
Lower
Load changing
capacity
Lower (3%) Higher (5%)
Sox, Nox Emission Higher Lower
Weight of Boiler Higher Lower

19. 19
Conclusion
Supercritical boiler is probably the best and clean
technology for the upcoming project in India due to the
higher plant efficiency & less environment pollution
which reduces the amount of coal used per MWh.

20. 20
Acknowledgement
S Bhattacharya Sir (AGM RLI)
K L Mourya Sir (Co-ordinator)
NTPC Vindhyachal
All friends and stuff of RLI
NTPC

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U
T NH
A
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S CP E R I T IC R L
E C GL O