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Analysis of Large Turbines

This analysis delves into the principles and rules governing the design of large impulse-reaction turbines, specifically focusing on multistage reaction turbines. The text explores the relationship between momentum and energy transactions, as well as the efficiency and power output of the turbines. Detailed discussions cover the impact of blade shape, height variations, and reaction degrees on turbine performance. The application of the first law analysis in reversible reaction stages is elucidated, along with the significance of degree of reaction in turbine sizing and selection. The text also addresses the specific issues faced in large power plant steam turbines, offering solutions and configurations like Tandem Reheat Steam Turbines and Cross Compound Steam Turbines. For engineers and students in the field of mechanical engineering, this serves as a comprehensive guide to understanding and optimizing large-capacity steam turbines.

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Analysis of Large Turbines

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  1. Analysis of Large Turbines P M V Subbarao Professor Mechanical Engineering Department Generalization of Sir Parsons Concept……

  2. Parsons Steam Turbines : Multistage Reaction Turbines

  3. General Rules for Design of Large Impulse-Reaction turbine • The shape of the blade must be viable . • The height of blade must vary at a uniform rate, thus contributing to more economic designs. • As a result of enthalpy drop occurring in the moving blades, there is a considerable amount of pressure is exerted on the rotor. • This is transmitted to thrust bearing. • To void large axial thrust it is usual to allow: • Low degree of reaction in high pressure stages. • In large steam turbines (>300 MW), it is now usual to allow 60 – 70% of degree of reaction in low pressure stages.

  4. U b1 a2 a1 b2 Va1 Vr1 Va2 Vr2 p va vr Generalization of Degree of Reaction The reaction effect is an addition to impulse effect. Define the degree of reaction A Physical Linkage between Momentum and Energy transactions

  5. First law for fixed blades: First Law Analysis of Reversible Reaction Stage First law for relative flow through moving blades: 2 0 1

  6. DoR of Reversible General Reaction Blading True Power lost by steam in a stage = Power gained by rotor blade 2 0 1

  7. Relative Acceleration of Steam

  8. Capacity of A General Reaction Stage The driving force on wheel Power Output of the blade : Diagram Efficiency or Blade efficiency:

  9. Steam Path Stage Sizing

  10. Linearization of Reaction Stage Equations

  11. Blade velcoity factor, f

  12. For a given shape of the blade, the efficiency is a strong function of U/Vfitc. For maximum efficiency:

  13. Performance of Degree of Reaction Specific Power output

  14. Lincreasing L1 L2 L3 L4 hstage Selection of Degree of Reaction An Isentropic Analysis only !!! Still All the Steam Power Cannot be Converted into Mechanical Power ?

  15. Steam Path Stage Sizing

  16. Large Power Plants : Selection of Speed Swallowing Capacity : Loading Capacity : Power Capacity :

  17. Mechanical Arrangements of Steam Turbines • Solutions to Turbo-machinery Issues. • Tandem Reheat Steam Turbine • Cross Compound Steam Turbine

  18. Tandem Reheat Steam Turbine

  19. Cross Compound Reheat Steam Turbine

  20. Tandem-compound four-flow steam turbine

  21. Large-Capacity Steam Turbines for Fossil Thermal Power Plant

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