Prof. D.N. Reddy

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STEAM POWER CYCLE
OPTIMISATION

• Prof. D.N. Reddy
• Director
• Centre for Energy Technology
• University College of Engineering
• Osmania University.

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• Thermal performance
• The main impact of the Supercritical Cycle is to
  increase the overall plant efficiency by reducing
  Fuel consumption for Unit of Power Generated.

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• Reduction in CO2 emissions to the extent of 15
• ? sub-critical 38 ? supercritical 45
  at 600 oC
• Temp 650 700oC ? 50 55

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• Steam Cycle performance
• 1969 - 36
• 1985 - 40
• 1990 - 43-44
• 2000 Double Re-heat - 45-46

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• Improvement in Efficiency
• Increase in Main Steam Pressure and Re-heat Steam
  Temp
• Final Feed Water Temperature
• ( Depends on Increase in No.of Re-heat stages
  and Number of Feed Water Heaters)

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• BOILER EXIT GAS TEMPERATURE
• ( 20oC reduction increases Efficiency by 1.1)
• Condensor pressure
• Reduction of Auxillary Power Consumption
• Improvement in Component Efficiencies

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• Part Load Efficiency
• Part load Reduction on Efficiency
• Sub-critical 75 - 4
• 50 - 10-11
• Super-critical 75 - 2
• 50 - 5.5 8

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• Boiler Design Optimisation
• Sub-Critical Boilers - Drum Boilers Steam
  and Water Separated in the evaporator
• Super-Critical - Once-through design

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• Two pass and Tower Design
• Combustion Zone - Spirally Wound Membrane /
  inclined tubing preferable
• Increase in Pressure - Thicker sections /
  Higher and Temp grade composition

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• Current state of Art
• Boiler out let Steam Pressure and Temperature
  300 bar/580-600 oC
• Limitations
• Boiler Furnace Wall
• Complex Welding

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• Vertical Furnace Tube Design
• Cheaper and less Complex Furnace Design
• Easier Furnace Framing
• Lower Pressure Drop (higher efficiency)

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• Current status of Turbine Design
• Shaft Speeds - 3000-3600 rpm
• Inlet Steam conditions - 240 bar/565oC
• 300 bar/600oC
• Output 1100 MW

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• Feed Water Pumps
• Boiler Feed Water Pumps - 3-4 of gross
• power output
• Feed Water Temperature - 280 300oC
• Flue Gas Temperature - 120oC
• (can be reduced to 80oC using Heat Recovery
  System)
• Upstream Flue gas De-Sulfurization

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• Improvement in Efficiency
• Heat Recovery System 0.6 Coal Fired
• 1.0 Lignite Fire

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• Turbine and Cycle Optimisation
• Improved blading profiles making use of Modern
  CFD Technologies
• Higher Final Feed Temperature and Bled Steam
  Temperature
• Bled Steam Tapping off the HP cylinder

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• Improved Efficiency of Auxillaries
• Lower condenser pressures using larger condensers
  and large exhaust areas
• Large unit sizes improving Turbine Efficiencies
• Increasing automation and level of controls
• Optimising plant layout

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• Alternate Boiler Technologies
• Gasification Cycles
• FBCs AFBC
• PFBC
• CFBC
• HRSG to Power a Turbogenerator

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Schematic Diagram of a Steam Power Plant
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Process Plant Diagram
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Steam Turbine Cycle
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The Ideal Reheat Cycle
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The Ideal Regenerative Cycle
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Regenerative Cycle with Open Feed Water Heater
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Closed Feed Water Heater
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Effect of Boiler Pressure on Rankine-Cycle
Efficiency
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Pressure of Turbine Inlet
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THANK 'U'