1 / 72

Achieving High Efficiency with Reheating in Supercritical Steam Cycles

This article explores the benefits and implementation of reheating in steam Rankine cycles to achieve high efficiency. It discusses the process of reheating steam and its impact on cycle efficiency, with a focus on double reheat cycles and optimization of reheat pressures. Various aspects of supercritical and ultra supercritical cycles are analyzed to improve net efficiency in power plants. Additionally, the regeneration cycle with mixers and open feed water heaters is examined for minimizing wastage and enhancing performance.

duncane
Download Presentation

Achieving High Efficiency with Reheating in Supercritical Steam Cycles

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Generation of Most Eligible Steam for Rankine Cycle P M V Subbarao Professor Mechanical Engineering Department Means to AchieveQualities of Working Fluid Preferred by Sir Carnot …..

  2. 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

  3. Classification of Rankine Cycles

  4. 3sup 3sub T More Bottlenecks to Achieve Supercritical Steam Cycle 2 4sup 4sub 1 s

  5. Quality and Saturated Liquid-Vapor (Wet) Mixture • Now, let’s review the constant pressure heat addition process for water shown in Figure. • The state 3 is a mixture of saturated liquid and saturated vapor. • How do we locate it on the T-v diagram? • To establish the location of state 3 a new parameter called the quality x is defined as

  6. Adiabatic Expansion of Steam • The liquid in the LP turbine expansion flow field is seen to progressively appear, with lowering pressure, in four forms, namely as: • A fine mist (or fog) suspended in the steam; • As a water stream running in rivulets along the casing (mainly OD); • As a water film moving on the surface of the blades (mainly stator; not particularly evident on the rotor blades owing to centrifugal-flinging action); • As larger droplets created when the water flowing along the surface of the blades reaches the trailing edge.

  7. 3sup 3sub T More Bottlenecks to Achieve Supercritical Steam Cycle 2 4sup 4sub 1 s

  8. Ill Effects of High Pressure Cycles x Pressure, MPa

  9. Old Last Stage LP Blade

  10. Modified Loss Region

  11. Why should steam condense during Adiabatic Expansion?????

  12. Thermodynamic Characterization of Working Fluid

  13. Philosophical Recognition of Working Fluid Organic Substances must be selected in accordance to the heat source temperature level (Tcr < Tin source)

  14. Progress in Steam Rankine Cycle

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

  16. 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

  17. Analysis of the Reheat Cycle 4’ 6

  18. Clues to Achieve Double Benefit Consider the ratio of Define Increment in efficiency

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

  20. Effect of Reheat Pressure on New Tm,in pmax= 15 MPa Tmax= 550 0C Tsat= 342.20C

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

  22. Optimal Selection of Reheat Point

  23. 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

  24. Super Critical Cycle ~ 1990

  25. Ultra Supercritical Installations of The World

  26. Double Reheat Ultra Super Critical Cycle 8

  27. Reheater Pressure Optimization forDouble Reheat Units 97bar 69bar 110bar

  28. 21st century Rankine Cycles Improvement in Efficiency, %

  29. Super Critical Cycle of Year 2005

  30. Double Reheat Super Critical Plants Net efficiency on natural gas is expected to reach 49%. Net efficiency on coal is expected to reach 47%.

  31. Advanced 700 8C Pulverised Coal-fired Power Plant Project

  32. FUTURE ULTRA SUPERCRITICAL PLANT – UNDER DEVELOPMENT EFFICIENCY 55 %

  33. h Steam Generation : Explore more Causes for Wastage x=s

  34. Look for More Opportunities to Reduce Wastage

  35. Follow the Steam Path : Early Stage

  36. Follow the Steam Path : Middle Stage

  37. Follow the Steam Path : End Stage

  38. Follow the Steam Path : The End

  39. Save Wastage thru Recycling !?!?

  40. Regeneration Cycle with Mixer (Open Feed Water Heater)

  41. 6 4 6’ 3 2 Synthesis of Rankine Cycle with OFWH 5 T p2=p6 1 7

  42. Regeneration Cycle with Mixer (Open Feed Water Heater)

  43. Analysis of mixing in OFWH

  44. Analysis of mixing in OFWH y h6 (1-y) h2 Constant pressure mixing process Consider unit mass flow rate of steam thru the turbine h3 Conservation of energy:

  45. Analysis of Regeneration through OFWH

  46. Optimal Location of FWH

  47. Performance of OFWH Cycle ~ 12MPa htotal pbleed, MPa

More Related