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Analysis of Reheat Rankine Cycle

Analysis of Reheat Rankine Cycle. P M V Subbarao Professor Mechanical Engineering Department. Means to Eliminate Hurdles while Adopting high Live Steam Pressures ……. Hurdles in Implementation of High Pressure Cycles. T max = 546 C &T min =40 C. x turbine -exit.

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Analysis of Reheat Rankine Cycle

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  1. Analysis of Reheat Rankine Cycle P M V Subbarao Professor Mechanical Engineering Department Means to Eliminate Hurdles while Adopting high Live Steam Pressures ……

  2. Hurdles in Implementation of High Pressure Cycles Tmax = 546C &Tmin=40 C xturbine-exit Main SteamPressure, MPa

  3. Reheating of Steam to Enhance Quality at the Turbine Exit Single Turbine drum

  4. Reheaters • The pressure drop inside reheater tubes has an adverse effect on the efficiency of turbine. • Pressure drop through the reheater should be kept as low as possible. • Higher pipe diameter and low steam will velocities can lower the pressure drop, but leads to higher capital cost. • Techno-economically viable Range: Tube diameter : 42 – 60mm.

  5. Cost to Benefit Ratio of Reheat Cycle

  6. Analysis of Reheat Cycle • Consider reheat cycle as a combination of Rankine cycle and horn cycle. • Cycle 1-2-3-4-5-6-1 = Cycle 1-2-3-4-4’-1 + Cycle 4’-4-5-6-4’. • Therefore, 4’ 6

  7. Analysis of Horn Cycle Horn Cycle: 4’ – 4 Isentropic Compression. 4 – 5 Isobaric Heat Addition. 5 – 6 Isentropic Expansion 6 – 4’ Isobaric(thermal) cooling. 4’ 6

  8. Condition for Development of Efficient Reheat Cycle

  9. Change in Efficiency due to Reheating Condition for increased efficiency: Select appropriate reheat pressure, pRH, such that left hand side is maximum.

  10. Selection of Reheat Pressure pmax= 15 MPa Tmax= 550 0C Tsat= 342.20C

  11. Effect of Reheat Pressure Dh,% 1.0 0.2 0.4 0.6 0.8 ~0.3 prh/pmax

  12. Optimal Selection of Reheat Point

  13. Reheating : A Means to implement High Live Steam Pressure Supercritical 593/6210C 593/5930C 565/5930C 565/5650C 538/5650C Improvement in Efficiency, % 538/5380C

  14. Effect of Reheating on Overall Tm,in

  15. Procedure to Determine Optimum Reheat Pressure • Calculate the efficiency of Rankine cycle, hRankine. • Calculate mean effective temperature of heat addition, Tm,in using • Find out pressure corresponding to Tm,in and entropy at HP turbine exit. • Add reheating at this pressure and calculate efficiency of the Reheat Cycle. • Repeat above steps for few iterations.

  16. pmax= 15 MPa Tmax= 550 0C Tsat= 342.20C

  17. Super Critical Cycle ~ 1990

  18. Effect of Various Steam Parameters on Reheat Cycle

  19. Ultra Supercritical Installations of The World

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