Energy Efficiency in Power Sector
Alok Mathur
General Manager (ARP)
BHEL New Delhi
3rd India –Japan Energy Forum
15-16 February 2010
Importance of Increasing Efficiency in Power Sector
y
y
y
y
y
Less fuel burnt per unit
Less CO2 and other pollutants per unit
Conserves non‐renewable fuel
Reduces cost of generation
Reduces requirement of fresh capacity addition
Predominance of Coal
• Coal is predominant source of energy for power generation
– 40% in world – 70% in India
• Coal likely to remain mainstay of India's electricity generation for next twenty five years
• With explosive growth in energy demand, the consumption of coal is slated to increase many fold
Strategies to Improve Efficiency in Power Sector
y Multi‐pronged strategy has to be adopted:
y Improvements in existing technologies such as subcritical power plants and hydro power plants
y R&M of aged power plants y Introduction of supercritical and ultra supercritical power plants
y Introduction of advanced technologies such as Integrated Gasification Combined Cycle (IGCC)
y Reduce losses in power transmission
Improvements in Steam Turbines
• For every 1 kcal/ kWh reduction in TG cycle heat rate, coal consumption per year reduces by
– 300 tonnes for 210 MW sets – 700 tonnes for 500 MW sets
• Since 1977, heat rate of BHEL’s steam turbines has reduced
– 210 MW by 5.4%
– 500 MW by 3.1%
• Efficiency of steam turbines is being improved by
– More efficient aerodynamic blade profiles
– Re‐designing inlet and outlet sections
– Reduction of primary and secondary heat losses
– Effective inter‐stage sealing
– Using higher steam parameters especially reheat steam temperature
New 500 MW Steam Turbine
• New variant of 500 MW steam turbine introduced by BHEL – Reheat steam temperature raised from 537°C to 565°C
– Flow paths of HP, IP and LP turbines redesigned
– Advanced class blade profiles
• Reduction of heat rate by 10 kcal/kWhr
• Thermal performance 0.6% better than conventional cycle • New cycle adopted for NTPC Dadri, Simhadri, Ennore, Aravali, etc.
New Rating of 600 MW
• New unit rating of 600 MW developed
– Uses existing HP and IP turbine modules of 500 MW – LP turbine changed from N30‐2 x 10.0 to N30‐4 x 6.3 (two LP turbines of 250 MW) • Two alternatives – 6‐heater cycle and 537 °C reheat temperature
– 7‐heater cycle and 565 °C reheat temperature
• Lower cost per MW • One percent improvement in heat rate over conventional 500 MW
• Saving of 24,000 tonnes of coal per year
• First 600 MW plant being installed at North Chennai, with a 7‐
heater cycle
Auxiliary Power Consumption
• Aerofoil bladed PA fans, with inlet guide vane control in place of damper control, has helped reduce fan losses • Replacement of worm gear by planetary gear in pulverisers
has improved energy efficiency.
• Efficiency of boiler feed pumps being enhanced by one percent through thermo hydraulic re‐design
• Use of variable speed drives with ID fans and BFPs can reduce energy losses at part loads
• Use of efficient motors such as H‐compact can increase drive efficiency by 0.6%
Control & Instrumentation
• Modern distributed control systems help to run all power plant equipment at close to their optimum operating points
• PADO (Performance Analysis, Diagnosis and Optimisation) software provides online guidance to run the plant with minimum losses and downtime
• Smart wall blowing system can optimise steam blowing cycle for soot blowers – Improving the heat absorption in boiler surfaces
– Reducing the consumption of auxiliary steam
Supercritical Power Plants
• Power plant cycle above critical pressure (221.2 bar)
• Offers advantage of ‘burn less fuel for the same output’ and low emissions
• Current steam parameters in India: 250 bar, 568 °C main steam and 593 °C hot reheat temperature
• Steam parameters are expected to be raised further, in line with global trends
• During the 12th Five Year Plan, over 50% of the capacity expansion will be through supercritical power plants
Ultra Supercritical Power Plants
• Worldwide, Ultra Supercritical (USC) plants with steam parameters up to 280 bar and 620 OC have been set up • Development of USC plants with steam parameters of 300 bar and 700 OC is in progress • The first such plant is expected by 2015
USC Technology in India
y India also plans to shift to USC steam parameters over the next few years
y India also plans to develop USC technology with 300 bar and 700 OC
y The key challenges
y Development of suitable materials
y Development of an optimum thermodynamic cycle
y Development of major equipment such as steam generators, steam turbines and their auxiliaries
Integrated Gasification Combined Cycle (IGCC)
y Important technology in the context of climate change y Emission of CO2 per MW less than for conventional plants
y Potential efficiency (~45%) higher than that of sub‐critical (~37%) and super‐critical (~40%) y Capture of CO2 is easier in the case of IGCC
y Low NOx and SOx emissions
y Low water consumption
y Fuel flexibility: coal as well as refinery residues
y Syn Gas can be used for conversion to oil, chemicals, fertiliser and hydrogen
IGCC vs. Conventional Coal Plant
Conventional Coal Plant
IGCC Plant
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NOx
350 ppm
SOx
600 ppm
SPM
50 mg/Nm3
CO2 Emission
High
CO2 capture ready No
Fuel consumption
High
less
Water consumption High
<25 ppm
<245 ppm
<2 mg/Nm3
10% Less
Yes
7% 40% Less
BHEL’s Experience in IGCC
• BHEL has been developing IGCC technology since the early eighties
• BHEL has gained a lot of experience in the development and operation of a pilot 6.2 MW IGCC plant at Trichy
• BHEL now well poised to set up a 182 MW IGCC Demonstration Project with APGENCO at Vijaywada
• Uses Pressurised Fluidised Bed Gasification (PFBG) technology, most suited for Indian coals Milestones in IGCC Development
Scale up:
Geometrical - 1:1.14
Capacity
- 1: 1.21
Pressure
- 1:0.9
Scale up:
Geometrical - 1: 2.91
Capacity
- 1: 11.1
Pressure
- 1:3
Scale up:
Geometrical - 1: 3.3
Capacity
- 1: 9.33
Pressure
- 1:1.2
Scale up:
Geometrical - 1: 2.25
Capacity
- 1: 15
Pressure
- 1:5
Dia 0.2 m
Press 2.0 ata
1.2
TPD
(APFBG)
Corp R&D
Hyderabad
182 MW
IGCC
125 MW
IGCC
6.2 MW
CCDP
18
TPD
(PEDU)
Corp. R&D,
Hyderabad
Tiruchy
450- 650 MW
IGCC
Concept
Design
APGENCO
Vijaywada
Future Commercial
Scale IGCC Plant
BHEL’s IGCC Development
6.2 Mwe
IGCC with
moving
bed
gasifier
Process &
Equipment
Developme
nt (PEDU)
pilot plant
based on
PFBG
6.2 Mwe
IGCC
retrofitted
with PFBG
Start
July 1983
Start
May 1986
Start
Sep 1993
Commg
Mar 1988
Commg
May 1988
Commg
Jan 1996
Developmental
testing
Compln
Sep 1992
Developmental
testing
Compln
Jan 1997
Extensive testing
carried out
To gain
experience in
gasification
and IGCC
plant
operation
Design and
fabrication of
major
equipmt and
development
of PFBG
technology
Data for
scale-up of
gasifier and
its integration
with CC
6.2 MW IGCC Pilot Plant at Trichy
6.2 MW IGCC Pilot Plant at Trichy
182 MW IGCC Project
y Rating 182 MW
y Gasifier – 2265 tpd coal capacity using Pressurised
Fluidised Bed Gasification (PFBG) technology y Gasifier Pressure: 28 kg/cm2, Temperature: 1025 °C
y Ash content: 36‐42% (Ash up to 50% can be accepted)
y Gas clean‐up system including barrier filters and wet scrubbers
y Frame 9E Gas Turbine: 102 MW
y Heat Recovery Steam Generator (Two pressure)
y Steam turbine: 80 MW
y Gross efficiency: >40%
y Coal & ash handling system
y Switchyard
Future Directions in IGCC
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y
y
y
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y
450‐650 MW capacity commercial plant
Advanced class gas turbine
Oxygen enriched gasification Low cost oxygen separation technology
Hot gas clean‐up technology
Greater degree of integration
CO2 capture
Hydrogen firing in gas turbines
Integration with fuel cells
Power Transmission
• Flexible AC Transmission Systems (FACTS), have been developed and introduced • Can be used in transmission networks to reduce system losses
• Thyristor Controlled Series Compensation (TCSC) systems enable increased power flow in existing lines
• Controlled Shunt Reactor (CSR) developed to replace “fixed” shunt reactors
• Fixed shunt reactors cause continuous power losses • CSR comes into the circuit only when required • Installed 50 MVAR CSR in PGCIL sub‐station at Itarsi in 2001
• Excellent operational feedback
• MAHAGENCO has placed orders for two sets of CSRs for different locations
HVDC
• High Voltage Direct Current (HVDC) is also employed to reduce transmission losses in long distance power flow.
• Advantages: lower losses, complete control of power flow on the HVDC line, reduced requirement of right of way, etc.
• HVDC can also be used to interconnect electrical grids operating at different frequencies – Surplus power from one region can be transmitted to a power deficit region – More efficient and effective utilization of resources
Conclusion
y India is poised to expand its power sector in a big way
y New technologies are being introduced to enhance energy efficiency
y International cooperation would be greatly welcome in these areas