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Advanced Reheat-Regeneration Cycles

Advanced Reheat-Regeneration Cycles. P M V Subbarao Professor Mechanical Engineering Department. Continuous and Meticulous Efforts for Better Carnotization of Rankine Cycle……. Some of The Operating Double Reheat Units Around The World.

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Advanced Reheat-Regeneration Cycles

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  1. Advanced Reheat-Regeneration Cycles P M V Subbarao Professor Mechanical Engineering Department Continuous and Meticulous Efforts for Better Carnotization of Rankine Cycle……

  2. Some of The Operating Double Reheat Units Around The World

  3. Super Critical Cycle of Nordjylland NO.3 Unit in Denmark T1=580C p1=29.0MPa h1=3389 kJ/kg s1=6.183 kJ/kg.K T5=580C p5=2.0MPa h5=3645kJ/kg s4=7.65 kJ/kg.K T6”=19.7C p6”=2.3kPa h6”=1808kJ/kg s6”=6.183 kJ/kg.K X6”=70.3% T3=580C p2=7.5MPa h2=3598kJ/kg s2=6.998 kJ/kg.K T6’=19.7C p6’=2.3kPa h6’=2047kJ/kg s6’=6.998 kJ/kg.K x6’=80.01% T2=350.8C p2=7.5MPa h2=3005kJ/kg s2=6.183 kJ/kg.K T4=361.9C p4=2.0MPa h4=3163kJ/kg s4=6.998 kJ/kg.K T7=19.7C p7=2.3kPa h7=82.8kJ/kg s7=0.2927 kJ/kg.K T6=19.7C p6=2.3kPa h6=2238kJ/kg s6=7.65 kJ/kg.K x6=88% T8=20.2C p8=29MPa h8=111.7kJ/kg s8=0.2927 kJ/kg.K

  4. Super Critical Cycle of year 2010 > 50 %

  5. Interaction between Regeneration & Reheat in An AUSC Rankine Cycle T, C p, MPa

  6. More Clues for Carnotization of Modern Rankine CycleTemperature Central Idea 1: Selection of Heater Locations and maximization of feasible Final Feed Water • In order to maximize the heat rate gain possible with ultra-supercritical steam conditions, the feedwater heater arrangement also needs to be comprehensively optimized. • In general, the selection of higher steam conditions will result in additional feedwater heaters and a economically optimal higher final feedwater temperature. • Concurrence from turbine designers limited the freedom of optimal location of FWHs.

  7. Restrictions due to Concurrence • 20th Century turbine designers didn’t allow steam bleeding from HP drum. • The highest pressure allowed was reheat location. • The range of pressures for the location of FWHs is limited to prh to pcondenser. • This is known as Heater Above Reheat Pressure (HARP) issue. • In many 21st century designers showed that the selection of a heater above the reheat point (HARP) will enhance the relative efficiency for same number of FWHS.

  8. Temperature Enthalpy diagram for HP CFWH Bleed steam TTD Saturation temperature of Bleed Steam Tbleed-sat Condensate DCA h

  9. 900 MW Advanced ultra-supercriticalpower unit with single reheat 7.5MPa &720C 35MPa &700C 330C 0.005 MPa

  10. The impact of the feed water temperature and thereheat pressure on the cycle efficiency FFWT = 330C FFWT = 350C FFWT = 320C FFWT = 310C FFWT = 340C No HARP

  11. Typical Single Reheat Heater Cycle with HARP

  12. Double Reheat Cycle with Heater above Reheat Point

  13. Inconsistent Effect of HARP

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