1. Supercritical boilers operate above the critical pressure of water (221 bar), where there is no distinction between water and steam. 2. Operating above the critical pressure provides benefits like higher cycle efficiency, lower fuel consumption and emissions, and improved load change flexibility compared to subcritical boilers. 3. The key difference between subcritical and supercritical boilers is that supercritical boilers are drumless, with evaporation occurring in a single pass and flow induced by the feed pump rather than natural circulation.

1. SUPERCRITICAL BOILER
SHIVAJI CHOUDHURY

2. What is SUPER CRITICAL
 The term "supercritical" refers to
main steam operating conditions,
being above the critical pressure of
water (221. bar).
 Above the critical pressure there is no
distinction between steam and water,
i.e. above 221. bar, water is a fluid.

3. What is Supercritical Pressure
Pressure range
 Sub critical
: Below 221 bar-a
 Super critical
: 221bar-a and
above
STATES OF WATER : Critical Pt.= 221BAR,374 deg C

4. Two Phase Vs Single Phase Boiling

5. Impact of critical point on the
Boiling Process
 Beyond critical point of water, the latent
heat of vaporization becomes zero and
there is no distinction between liquid and
vapor phase of water.
Absolute Pressure
(Bar)
Saturation Temperature
(o
C)
Latent Heat
(K J/Kg.)
50
150
200
221
264
342
366
374
1640
1004
592
0

6. 6
Supercritical & Subcritical cycle

7. Benefit of supercritical technology
I ) Higher cycle efficiency means
 Primarily
 less fuel consumption
 less per MW infrastructure investments
 less emission
 less auxiliary power consumption
 less water consumption
II ) Operational flexibility
 Better temp. control and load change flexibility
 Shorter start-up time
 More suitable for widely variable pressure operation

9. Natural Circulation Vs. Once
Through System

10. Supercritical boiler

11. Similarities-subcritical &
supercritical
 Basic operation of cycle is same i.e. Rankine Cycle.
Constructional Features are also same except supercritical is
drumless Boiler.
 The equipments & philosophy of working are similar in both
the cases like:
 Air preheater
 Economiser
 PA, SA & ID fans
 Electrostatic precipitator
 Boiler feed pump
 Feed water heaters
 Turbine
 Condenser
 CEP

12. Difference between subcritical and
supercritical power plants
 Sub-Critical Power Plant
 A typical example of this
system is the drum-type steam
generator.
 Natural circulation is produced
by heating of the risers. The
water/steam mixture leaving
the risers is separated into
water & steam in the drum.
 The steam flows into the
superheater and the water is
returned to the evaporator inlet
through down comers.
 If the system is operated only
with natural/assisted
circulation, the application
range is limited to a max drum
pressure of approx. 190 bar.
 Super-Critical Power
Plant
 This type of boiler is Drumless
steam generator.
 Evaporation takes place in a
single pass.
 Flow through the evaporator is
induced by the feed pump.
 The evaporator & superheater
areas thus automatically adjust
to operational requirements.

13. Comparison of Drum and Separator
Drum for NC Boiler
Steam-Water separator
for Benson Boiler

15. Supercritical boilerSubcritical boiler

16. Supercritical thermal power plant

18. Increase of Cycle Efficiency due to
Steam Parameters
300
241
175 538 / 538
538 / 566
566 / 566
580 / 600
600 / 620
6,77
5,79
3,74
5,74
4,81
2,76
4,26
3,44
1,47
3,37
2,64
0,75
2,42
1,78
0
0
1
2
3
4
5
6
7
8
9
10
HP / RH outlet temperature [deg. C]Pressure [bar]
Increase of efficiency [%]

19. Supercritical Tube Materials

20. Super criticalSub critical

21. Boiler Tube

22. Spiral Waterwall

23. Advantages of Spiral Water Wall
 High Reliability of Water Wall Tube
 Proven Operating Record
 Low Water System Pressure Drop
 High Stable Operation
 Easy Boiler Commissioning
 Maintenance Free
 Performance Evaluation

24. Drum boiler vs benson boiler-
feedwater control

25. Temperature Control

28. HBD 660 MW Supercritical

29. Technological Journey to Supercritical
Boiler in India.
Steam Parameters for 500 MW units & Super-critical thermal
Power plants :
660 MW500 MW
Steam Flow-
1625 T/hr
SH Presr.- 179 kg/cm2
SH Temp.- 540 0
C
RH Temp - 540 o
C
Steam Flow-
2225 T/hr
Steam Flow-
2120 T/hr
SH Pres- 255 kg/cm2
SH Temp.- 540 0
C
RH Temp - 568 o
C
SH Presr.- 255 kg/cm2
SH Temp.- 568 0
C
RH Temp - 596 o
C
200 MW
SH Presr.- 150 kg/cm2
SH Temp.- 537 0
C
RH Temp - 537 o
C
SH Pres.- 255 kg/cm2
SH Temp.- 5680
C
RH Temp - 596 o
C
Steam Flow-
2550 T/hr
Steam Flow-
550 T/hr
800 MW
SH Presr.- 179 kg/cm2
SH Temp.- 540 0
C
RH Temp - 568 o
C
Steam Flow-
1590 T/hr
Note:
1.200 & 500 MW – Subcritical thermal power plant
2.660 & 800 MW - Supercritical thermal power plant

30. Turbine cycle heat rate (norms)

31. Sipat ,supercritical boiler 660 MW

32. Rankine Cycle –Sasan UMPP
Super Critical Condition -660 MW unit
Turbine Cycle Heat rate - 1900 kCal/kWh

33. THANKING YOU