Transcript
To Study Efficiency of Thermal Power Generation Using Sub Critical and Supercritical Pressure
Department of Chemical EngineeringCollege of Engineering and Technology,
Akola ( B. Tech final year)
PRESENTED BY Prajwal G. Patil
CONTENTS Introduction Mechanism Comparisons Advantages Challenges Implementation Improvement of efficiency in NTPC Coal consumption Conclusion References
INTRODUCTION
What is Super critical pressure ? What is Sub critical pressure ?
Water reaches to this state at a critical pressure above 22.1 MPa and 374 oC.
HISTORY
Since 1950s, The United State (1300 MW/35
MPa/760 ℃) Japan (1050 MW/34.5
MPa/620 ℃) The European Union (1000MW/37.5 MPa/700
℃) China: Main steam pressure >270 Bar
INNOVATIONS Supercritical units have been developed into
proven mature and commercialized advanced technologies in the world
Over 600 supercritical coal‐fired units have been successfully into commercial operation for decades worldwide
The 1300MW class supercritical units with steam parameters of 31MPa/600 ℃ are being developed in industrial economies
EVOLUTION OF THERMAL POWER EFFICIENCY WORLDWIDE
Ƞ (%
) LHV
SCOPE AND OBJECTIVE • CO2 emissions can be lowered by improving the
efficiency of coal fired power plants.
• Increasing the temperature & pressure in a steam turbine increases the efficiency of the Rankine steam cycle used in power generation,
• It decreases the amount of fossil fuel consumed and the emissions generated.
• Large amount of carbon-di-oxide (CO2) emissions produced by them which contribute in a large measure to greenhouse effect and global warming.
PRINCIPAL Coal based thermal power plant works on the
principal of Modified Rankine Cycle.
Basic Rankine Cycle
A SIMPLE RANKINE CYCLE
condenser
3’
Sub Critical Rankine Cycle
2’
Supercritical Rankine Cycle
• 1 - 2 > CEP work• 2 – 2s > Regeneration• 2s - 3 > Boiler Superheating• 3 – 4 > HPT expansion• 4 – 5 > Reheating• 5 – 6 > IPT & LPT Expansion• 6 – 1 > Condenser Heat
rejection
THERMAL POWER PLANT water as working fluid Energy transformation Rotation of turbine Electricity production
Fig.1 Power is produced in thermal power plants by rotating steam turbine
ENERGY ABSORPTION FROM STEAM Loss of energy Expansion of steam Constant Entropy
Fig.2 Pressure and temperature drop of steam when turbine absorbs energy from it
USE OF CONDENSER Expansion Conversion by rejection of heat constant pressure
Fig.3 Use of condenser in order to transform vapour into liquid state
PUMPS To raise the pressure Regained its original pressure
Fig.4 Compressor pumps the fluid to its original pressure
HEAT ADDITION IN BOILER & RANKINE CYCLE External heat Heat exchanger Transform to vapour and regains its original
temperatureThis completes the thermodynamic cycle of a thermal power plant, called Rankine Cycle
Fig.5 Heat addition at boiler brings the fluid to its original temperature
Super Critical Unit
COMPARISION OF SUPER CRITICAL & SUB CRITICAL
DESCRIPTION SUPERCRITICAL(660MW)
SUB-CRITICAL(500MW)
Circulation Ratio 1 Once-thru=1Assisted Circulation=3-4Natural circulation= 7-8
Feed Water Flow Control
-Water to Fuel Ratio (7:1)-OHDR(22-35 OC)-Load Demand
Three Element Control-Feed Water Flow-MS Flow-Drum Level
Latent Heat Addition Nil Heat addition moreSp. Enthalpy Low More
Sp. Coal consumption Low High
DESCRIPTION SUPERCRITICAL(660MW)
SUB-CRITICAL(500MW)
Coal & Ash handling Low High
Pollution Low High
Aux. Power Consumption
Low More
Overall Efficiency High(52-59%)
Low(36-37%)
Total heating surface area Reqd
Low(84439m2)
High(71582m2)
Tube diameter Low High
CONTINUE..
DESCRIPTION SUPERCRITICAL(660MW)
SUB-CRITICAL(500MW)
Material / Infrastructure (Tonnage)
Low7502 MT
High9200 MT
Start up Time Less More
Blow down loss Nil More
Water Consumption Less More
Air flow, Dry flu gas loss Low High
CONTINUE..
ADVANTAGES OF SC TECHNOLOGYPlant efficiency up to 52-59%• Conservation of fuel resources• Reduction of Atmospheric Pollutants - CO2 , SOx & NOxHigher cycle efficiency means• less fuel consumption• less per MW infrastructure investments• less emission• less auxiliary power consumption• less water consumptionOperational flexibility• Better temp. control and load change flexibility• Shorter start-up time• More suitable for widely variable pressure operation
Reductions• Coal Consumption• Ash production• CO2• SO2• NOxImprovements• Startup time• Sliding Pressure Operation• Load following capabilityOther advantages• Reduced emission for each KWH of electricity generated• 1% rise in efficiency reduces the CO2 emission by 2-3%• The Most Economical way to enhance efficiency• Fuel cost saving : Economical• Reduced the Boiler size / MW• Reduced Start-Up Time• Enhancements
• Erection• Operation• Maintenance Practices• Water chemistry is more stringent in super critical once through
boiler.• Metallurgical Challenges• More feed pump power is required due to more friction losses in
spiral water wall.• Maintenance of tube leakage is difficult due to complex design of
water wall.
CHALLENGES OF SUPERCRITICAL TECHNOLOGY
IMPLEMENTATION OF SC TECHNOLGY AND FUTURE IN INDIA
Supercritical units in India:• There haven’t been any supercritical units in use in
India so far. • The National Thermal Power Corporation (NTPC), Sipat
Here are some upcoming projects in India: • North Karanpura, Jharkhand – 3x660 MW• Darlipali, Orissa – 4x800 MW• Lara, Chattisgarh – 5x800 MW• Meja, Uttar Pradesh - 2x660 MW• Sholapur – 2x660 MW• New Nabinagar-3x660 MW
SUPER CRITICAL TECHNOLOGY -EFFICIENCY IMPROVEMENTS IN NTPC
Sub -critical Super -critical unitsOld Recent Plant-I Plant-II Plant-III
Unit Size 500 MW 500 MW 660 MW 660 MW 660 MWMS Pressure
kg/cm2170 170 247 247 247
MS Steam Temp(℃)
537 537 537 537 565
RH Steam Temp(℃)
537 565 565 565 593
Gross Efficiency (HHV) %
38.00 38.26 39.26 39.84 40.14
SUB. VS. SUPERCRITICAL CYCLE IMPACT ON EMISSIONS
Plant Efficiency, %*
Plant Efficiency, %
Fuel Consumption/Total Emissionsincluding CO2
Subcritical Supercritical 34 - 37 52 - 59
Plant Efficiency, Btu / kw-hr 10,000 - 9,200 9,200 - 8,300
34%
Base
37%
Base-8%
52%
Base-17%
COAL CONSUMPTION
500 M
W/ 170
ATA/
537/5
37
500 M
W/ 170
ATA/
537/5
65
600 M
W/ 170
ATA/
537/5
37
600 M
W/ 170
ATA/
537/5
65
660 M
W/ 247
ATA/
565/5
93
800 M
W/ 247
ATA/
565/5
93
800 M
W/ 280
ATA/
593/5
930.560.580.6
0.620.640.66
Chart Title
Parameters
Coa
l Con
sum
ptio
n Kg
/KW
-hr
CONCLUSION• Hence shifting from Subcritical to Supercritical
improve efficiency of thermal power plant • Electric power generation in India will continue to be
dominated by Thermal power generation for at least next 40-50 years
• Development and application of clean, high efficiency, large capacity, Thermal power generation technology is a long term strategic task for India
• In order to meet our increasing demand for electric power, as well as to improve coal utilization efficiency and reduce pollutant emissions from thermal power plants, we have to develop domestic supercritical units
REFERENCES Smith, The Book Thermal Engineering, 2009 “Design Aspects of the Ultra-Supercritical CFB Boiler”; Stephen J.
Goidich, Song Wu, Zhen Fan; Foster Wheeler North America Corp. “Novel conceptual design of a supercritical pulverized coal boiler
utilizing high temperature air combustion (HTAC) technology”; Natalia Schaffel-Mancini, Marco Mancini, Andrzej Szlek, Roman Weber; Institute of Energy Process Engineering and Fuel Technology, Clausthal University of Technology, Agricolastr. 4, 38678 Clausthal-Zellerfeld, Germany; 6 February 2010.
“Supercritical (Once Through) Boiler Technology”; J.W. Smith, Babcock & Wilcox, Barberton, Ohio, U.S.A.; May 1998.
“Steam Generator for Advanced Ultra-Supercritical Power Plants 700 to 760°C”; P.S. Weitzel; ASME 2011 Power Conference, Denver, Colorado, U.S.A; July 12-14, 2011.
“Supercritical boiler technology for future market conditions”; Joachim Franke and Rudolf Kral; Siemens Power Generation; Parsons Conference; 2003.
“Steam Turbine Design Considerations for Supercritical Cycles”; Justin Zachary, Paul Kochis, Ram Narula; Coal Gen 2007 Conference;1-3 August 2007.
“Technology status of thermal power plants in India and opportunities in renovation and modernization”; TERI, D S Block, India Habitat Centre, Lodi Road, New Delhi – 110003.
“Applied Thermodynamics”; Dr. H.N Sawant; January 1992; revised July 2004.
“http://en.wikipedia.org/wiki/Boiler#Supercritical_steam_generator”
Mitsubishi Heavy Industries Technical Review Vol. 50 No. 3 (September 2013)
NETL (National Energy Technology Laboratory) (2008), Reducing CO2 Emissions by Improving the Efficiency of the Existing Coal-Fired Power Plant Fleet, DOE/NETL-2008/1329, NETL, Pittsburgh, PA, www.netl.doe.gov/energy-analyses/pubs/CFPP%20Efficiency-FINAL.pdf.
top related