1. Advanced Ultra Supercritical Steam Generators
&
Advanced Ultra Supercritical
Steam Generators
New trends in Boiler Technology
M. Anandaraj
Deputy General Manager
BHEL, Tiruchirappalli

2. Contents BHEL Steam Generators Emerging Market Requirements
Trends in Cycle parameters
Supercritical Boilers
Major Systems
Startup System
Pressure part Arrangement
Firing System
High Temperature Materials
Ultra Supercritical Boilers
Advanced Ultra Supercritical Boilers

3. BHEL Utility Units - A Summary
62 % Total Installed Capacity of India is Contributed by BHEL Utility Sets

4. BHEL Industrial Units - A Summary
Contracted
Commissioned
VU 40 46 45
VU 40 S 15
VU 60 38 19 MU 3 VP 23 16
V2R 17
HRSG
177
121
AFBC 72 59
CFBC 28 10
Others
Total
447
333

5. BHEL is currently adopting
Advanced Steam Cycles to Improve the Environmental & Economic Performance of India’s Power Generation

6. Reference List of Supercritical Boilers
NTPC / BARH 2 x 660MW
APPDCL / Krishnapatnam 2 x 800 MW
PPGCL / BARA 3 x 660 MW
RPCL / Yermaras 2 x 800 MW
RPCL / Edlapur 1 x 800 MW
KPCL / Bellary 1 x 700 MW
LPGCL/Lalithpur- BHL 3 x 660 MW
DB Power / Singrauli 2 x 660 MW
NTPC / Mouda St. II 2 x 660 MW
18 Boilers Contracted

7. Emerging Market Requirements For Thermal Power Generation
High Reliability & Availability
Highest Plant efficiency
Suitable for differing modes of operation
Suitable for varying fuel quality
Minimum emission of Pollutants
Lowest cost

8. Higher Plant efficiency for
Conservation of fuel resources
Reduction of Atmospheric Pollutants
- CO2 , SOX & NOX

9. Measures to improve Plant Efficiency
Cycle Parameters :
Higher steam parameters with Once Thro’ Boilers
Boiler side measures :
Highest Boiler Efficiency
Minimum RH spray
Minimum SH spray (if tapped off before feed heaters)
Reduced auxiliary power consumption

10. Increase of Plant Cycle Efficiency due to Steam Parameters

11. 500 MW Steam Generator Coal Consumption and Emissions

12. Current Trends in Steam Parameters
1980s : Pressure increased from bar to 225 bar; Temperature mostly around 540 °C
1990 : Pressures raised to 285 bar; Temperature raised to °C
300 bar & 620 °C not unusual today
255 bar & 568/596 °C commonly used presently

13. Coal will continue to have maximum share towards installed capacity for electricity at least upto 2050
CLEAN COAL TECHNOLOGY
Minimise CO2 emissions and environmental impact
Extend life of coal reserves
Approach: Develop technology for SC, USC & Adv-USC power plants

14. Efficiency and CO2 Emission
Plant type with power rating
Steam Pressure (kg/cm2)
Steam Temperature (C)
Efficiency (%)
CO2 Emissions (g/kW-hr)
Sub Critical (500 MWe)
170
540 35
900
# Super Critical
247
565 40
830
Ultra Super Critical
250
600 42
784
Advanced Ultra Super Critical
300
700 45
740
# The improvements are with respect to the best units under construction in India
Extension of coal reserves by 11%
Competitive in electricity cost on deployment

15. Trend in unit sizes & Cycle parameters
SHO Pressure (kg/cm2(a))
SHO/RHO Temperature (Deg.C)
Year of Introduction
60 / 70 MW 96
540
1965
110 / 120 MW
139
540/540
1966
200 / 210 MW
137 / 156
1972
250 MW
156
1991
500 MW
179
540/568
1979
1985
660 MW
256
568/596
2008
800 MW

16. Type of boilers Drum type - for sub-critical parameters
Once-through type
- for sub/super Critical Parameters

17. 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

18. Types of Circulation

19. Drum type boiler Natural Circulation Boiler
Circulation thru water walls by thermo-siphon effect
Controlled Circulation Boiler
At higher operating pressures just below critical pressure levels, thermo-siphon effect supplemented by pumps

20. Natural Circulation
Controlled Circulation

21. What is Super critical pressure ?
Pressure range
Sub critical : Below 221 bar
Super critical : 221 bar and above

22. What is a Super critical Steam Generator?

23. Supercritical Boilers
Supercritical pressure boiler has no drum and heat absorbing surface being, in effect, one continuous tube, in which the water & steam generated in the furnace water walls passes through only once hence called ‘Once through Supercritical pressure boilers’
The water in boiler is pressurized by Boiler Feed Pump, sensible heat is added in feed heaters, economizer and furnace tubes, until water attains saturation temperature and flashes instantaneously to dry saturated steam and super heating commences.

24. The Concept
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

25. Once Through Boiler Flow Diagram
Evaporator
Water separator
Feedwater
Economizer
FW-
Pump
Live steam
Superheater
Features
Increased mass flow through spiral waterwall tubing, or improved heat transfer through rifled vertical wall tubing.
No fixed evaporator end point
No thick wall components

26. Supercritical Boilers- Major Systems

27. General Arrangement of Steam Generator – Elevation

28. General Arrangement of Steam Generator – Plan

29. Once through Supercritical Boilers
Major differences from Drum type boiler :
Evaporator system
Low load Recirculation system
Separator

30. Circulation Systems
Drum Type
Once-through

31. Once -through Operating Range

32. Once -thru Boiler Requirements : Stringent water quality
Different control system compared to drum type
Low load circulation system
Special design to support the spiral furnace wall weight
High pressure drop in pressure parts
Higher design pressure for components from feed pump to separator

33. Features of Once Through Steam Generator
To ensure adequate mass flow rates through water wall, spirally wound water wall tubes are used.
Start-up and low load system up to 30-40% BMCR required.
Feed water quality requirements are very stringent.
Can be designed for both sub-critical and super-critical pressures.
Ideally suited for sliding pressure operation due to the absence of thick walled components.

34. Once -thru Boiler 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 rate thru’ the tubes
Small tube diameter
Arrangement ensures high mass velocity thru the tubes

35. Spiral Tube Arrangement
Features
Reduced number of tubes with pitch.
Increased mass flow.
Mass flow rate can be selected by number of tubes.

36. Once -thru Boiler - Furnace Wall

37. Spiral Water wall Tubing
Lateral Heat Flux Profile

38. Sliding Pressure Supercritical Design
Spiral Wall Windbox

39. Sliding Pressure Supercritical Design
Spiral to Vertical Transition Area - Load Transfer
Support Fingers
SPIRAL WALL SUPPORT

40. Furnace Wall Designs Spiral Wall Configuration
Vertical Wall Configuration

41. Supercritical Boiler with Vertical wall
Unit Mwe:
Max. Continuous Rating: t/h
SH Outlet Press: 262 bar
SH Outlet Temp: 568°C
RH Outlet Temp: 596 °C
Fuel: Sub-bituminous

42. Vertical Wall Sliding Pressure Supercritical Design
FRONT WALL
SIDE WALL
RIFLED TUBING
RIFLED TUBING
SCREEN TUBES
SMOOTH TUBING
HANGER TUBES
SMOOTH TUBING
ARCH
RIFLED TUBING
SIDE WALL
RIFLED TUBING
REAR WALL
RIFLED TUBING
FRONT WALL
RIFLED TUBING
SMOOTH TUBING
FROM THIS ELEVATION
ALL WALLS

43. Vertical Furnace Wall Design
Vertical tube furnace walls will provide all the operational benefits of the currently popular spiral design while significantly reducing the cost and construction time for the furnace and providing some reduction in pressure drop.

44. Vertical Wall Design - Advantages
The tubes are self supporting.
Transition headers at spiral/vertical interface are avoided.
Ash hopper tubing geometry simplified
Corners are easier to form
Reduced pressure drop, auxiliary power

45. Spiral Vs. Vertical Wall Comparison
Spiral Furnace System Applicable for all size units
Benefits from averaging of lateral heat absorption variation (each tube forms a part of each furnace wall)
Simplified inlet header arrangement
Large number of operating units
Use of smooth bore tubing throughout entire furnace wall system
One material utilized throughout entire waterwall system
No individual tube orifices – Less maintenance & pluggage potential
Vertical Furnace Wall System Limited to larger capacity units . 
Less complicated windbox openings
Traditional furnace water wall support system
Elimination of intermediate furnace wall transition header
Less welding in the lower furnace wall system
Easier to identify and repair tubes leaks
Lower water wall system pressure drop thereby reducing required feed pump power

46. Vertical Wall Wind box
Straight Tubes
Only a Few Bends at the Top and Bottom

47. Supercritical Boilers- Start-up and Low load recirculation Systems

48. Low load system with circulating pump

49. Once -thru Boiler Separator :
Separates steam and water during the circulating mode operation
Runs dry during once-thru flow mode
Smaller in size compared to drum in a drum type boiler

50. Start-up System

51. Overview of Firing Systems
Close-Coupled
Overfire Air
CFS Air Nozzle Tips
Flame Attachment
Coal Nozzle Tip
NOx < 0.18 – 0.30 kg/Mkcal*
Furnace
Diagonal
Separated Overfire Air
HP Pulverizer
with Dynamic Classifier
*NOx at furnace outlet

52. Wind Box arrangement

53. Plan View for SOFA arrangement
Lower SOFA in Corners
Tilt +/-30o
Yaw +/-20o
Upper SOFA on Walls

54. Materials in 660 MW (Typical)

55. Material Comparison Pressure part 660 MW OTSC (Supercritical) 500 MW
(Sub-critical)
Drum
Not applicable
SA 299 (Carbon Steel)
Vertical Separator
SA 335 P91
Water Walls
SA 213 T22
SA 210 Gr C
Economiser
Sa 210 Gr C SH
T91, TP 347H
T11/T22/T91/ TP 347H RH
T12/T23/T91/TP347H/ Super 304H
T22, T91, TP 347H

56. Boiler Parameters Description Unit 660 MW (Supercritical) 500 MW
(Sub critical)
Boiler Parameters -
BMCR
SH steam flow
t/h
2120
1625
SHO pressure
kg/cm2(a)
256
179
SHO/RHO temp. oC
568/596
540/540
Feed water temp.
294
254

57. Description (Source/Type)
Fuel Analysis - Coal
Description (Source/Type)
Unit
Design Coal
Worst Coal
Best Coal
Proximate Analysis
Fixed Carbon %
26.00
23.00
32.00
Volatile matter
19.00
18.00
22.00
Moisture
15.00
17.00
12.00
Ash
40.00
42.00
34.00
Total
100
HHV
kcal/kg
3300
2800
4000
Ultimate Analysis
Carbon
31.37
28.93
40.08
Hydrogen
3.40
2.40
3.50
Sulphur
0.40
0.5
0.36
Nitrogen
1.5
1.45
1.78
Oxygen(difference)
7.75
7.26
8.03
15.0
17.0
12.0
40.0
42.0
34.0
Carbonates + Phosphorous
0.58
0.46
0.25
Hard Grove Index 55 50 60

58. General Arrangement of Steam Generator – Plan

59. ULTRA SUPER CRITICAL TECHNOLOGY &
ADVANCED ULTRA SUPER CRITICAL TECHNOLOGY

60. The Basic Heat Cycle
Sub-critical units: Main steam pressure < bar
Super-critical units: Main steam pressure > bar
Ultra-supercritical units:
Higher steam pressure and temperature than supercritical units
Japan: Main steam pressure >242 Bar, or Steam temperature >593 ℃
Demark: Main steam pressure >275 Bar
China: Main steam pressure >270 Bar
USA (EPRI) : Main steam temperature>593 ℃

61. STEAM PARAMETERS
Plant with steam pressure exceeding 225 kg/cm2 is said “Supercritical”
Supercritical plant with main steam temperature  600C is said “Ultra Super-Critical”
Supercritical plant with main steam temperature  700C is “Advanced Ultra Super-Critical

62. Evolution of Steam Power Stations Efficiency Worldwide

64. EUROPEAN PERSPECTIVE AND ADVANCEMENT FOR ADVANCED USC
Pulverised Fuel-importance in World Power Generation
Background of Development Of USC Plant with Steam Temperature around 600 0C
Immediate Possibility of going to 650 0C & 700 0C with Nickel Alloy
Best Strategy for reduction of CO2 Emission 64

66. AD700 TECHNOLOGY USC steam parameters-700 0C and 350 bar
This can be achieved only by using Nickel based alloys
In July 2005 :COMTES 700 testing most important components – started operation in power plant Scholven in Gelchen-kirchen
Completed in During operation phase, valuable operational experience and processing technical knowledge were gained
Welding of thick walled materials must be improved
More test needed for improved welding techniques for 617 or Alloy 740 or Nimonic 263 66

67. R&D PROGRAM FOR A-USC MATERIAL DEVELOPMENT WITH CREEP STRENGTH/DEGRADATION ASSESMENT STUDIES
Japanese programme 2007 & 2008 (finding out and stabilising the structure parameters affecting creep strength and degradation for accurately estimating 1,00,000 hr creep strength)
New alloys
Fundamental studies on creep strength degradation assessment needed to ensure long term safe use.(FS->650 0C AS ->700 0C Ni-> 750 0C)
FS-> C beyond hrs without any type IV degradation
AS->generated by means of inter metallic compound precipitation strength grain boundary, strongest creep. 67

68. USC POWER PLANT DEVELOPMENT IN JAPAN68

69. METI/NEDO MATERIAL R&D PROGRAM69

70. China first established use with parameters 600 0C/25 MPa in 2006
STRUCTURAL STABILITY STUDY ON USE POWER PLANT ADVANCE HEAT RESISTANCE STEELS AND ALLOYS IN CHINA
China first established use with parameters 600 0C/25 MPa in 2006
TP347FGH & Super304H
GH984, Nimonic 80A
Ni-Cr-Co Inconel 740 studied with Special Metal Corp. USA for steam temperature of 700 0C 70

71. ECONOMIC ANALYSIS (EPRI)
A cost effective CO2 emission reduction option
Engineering design study(EPRI)
Cost and performance of USC with conventional coal power plants
Slightly more expensive
Cost of avoided CO2 emission was less than $25 per metric ton of CO2 capture and storage 71

72. MATERIAL SELECTION STEAM SIDE OXIDATION FIRE SIDE CORROSION
CREEP STRENTH 72

73. GKM TEST RIG 73

74. GKM TEST RIG 74

75. ADVANCES IN MATERIAL TECHNOLOGY
Strengthening and degradation of long term creep properties and the relevant microstructural evolution in advance high Cr-Ferritic steels and Austenitic steels at high temperature
GKM TEST RIG
Investigation of the long term operation behaviour tubes and forgings made of alloys for future high nuclear power plants
Qualification of key materials for 700°C fossil fuel power plant
Demonstration of material performance with special consideration of oxidation and corrosion behaviour
Creep damage development
Early detection of damage in new material in connection with advance calculation tools for components 75

76. ADVANCES IN MATERIAL TECHNOLOGY
ADVANCE CONCEPT FOR MAINTANENCE AND REPAIR FOR COMPONENTS MADE OF NEW MATERIALS
SH Test Track
Creep Test Track (upto 630 °C Austenite steel & upto 725 °C Ni based alloys)
Monitoring devices for evolution of ongoing damage 76

77. OPTIMIZATION OF INCONEL ALLOY 740
BY SPECIAL METALS CORPORATION
Developed for operating with 700°C steam temperature and higher pressure.
EUROPEAN TARGET
Stress rupture requirement of 1,00,000 Hrs rupture life at 750°C and 100 MPa stress.
Metal loss of less than 2 mm in 2,00,000 hrs of Superheater service.
DISADVANTAGE OF INCONEL ALLOY 740
Thick section fabrication posed weldability challenges.
Grain boundary microfissuring occurred in the heat affected zone (HAZ) of the base metal. 77

78. Robust Roadmap for Success of Mission
BHEL
Development, Design & Manufacture of Power Cycle Equipment, System Engineering,
Test Facility and Evaluation
NTPC
Detailed Project Report Project Management Operation and Maintenance Testing of Real Life Components in an existing plant
IGCAR
Advanced Design Analysis
Materials Development
Manufacturing Technology
Testing and Evaluation
800 MWe
Advanced
Ultra Super Critical
Power Plant
MoU
&
Synergy

79. Advanced Ultra Super Critical Plants
Gearing-up to introduce Advanced Ultra supercritical boilers (AUSC)
AUSC Boilers (300 ata, 700 C / 700 C) will be developed based on OTSC technology
Test Facility (400 bar, 700 Deg. C) installed and tests are on to collect critical design data
BHEL is one among the Five MNC’s to have this facility
Member of the National Technology Mission program to install AUSC plant by 2017

80. SUMMARY OTSC plants offer better cycle efficiency
Proven technologies leading to lower GHG emissions and lesser fuel burnt
BHEL has the technology for offering 660/700/800 MW supercritical units

81. Thank
You