Suggest the methods to improve the performance of steam turbine. Explain anyone in brief.

(i) Suggest the methods to improve the performance of steam turbine. Explain anyone in brief. 

(ii) Identity the different losses occurred in steam turbine. 
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1 Answer

Answer :

i) Methods to improve turbine efficiency

1) Reheating of Steam

2) Regenerative feed heating

3) Binary Vapour Plant


Regenerative feed heating System : The process of draining steam from turbine at certain points during it’s expansion and using this steam for heating feed water supplied to boiler is known as regenerative feed heating. It increases the thermal efficiency of plant, The temperature stresses in the boiler are reduced due to decreased range of working temperature.


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ii) Losses occurred in steam turbine :

 Residual velocity loss- The steam leaves the turbine with a certain absolute velocity which results in loss of KE. This loss is about 10 to 12% .It can be reduced by multistaging. 

Losses in regulating valves-Due to throttling action in valve , steam pressure drop occurs. Hence steam pressure at entry to turbine is less than the boiler pressure.


Losses due to friction in nozzle-Friction occurs both in nozzle and turbine blades. In nozzle, nozzle efficiency is considered, whereas in turbines, blade velocity coefficient is taken into account. This loss is about 10% 


Loss due to leakage-The leakage occurs between the shaft, bearings and stationary diaphragms carrying the nozzles in case of impulse turbines. In reaction turbine the leakage occurs at blade tips. This is about 1-2%. 


Loss due to mechanical friction-This occurs in bearings and may be reduced by lubrication 


Loss due to wetness of steam-In multistage turbine, condensation occurs at last stage ,so in dragging water particles with steam, some KE of stem is lost 


Radiation loss-As turbines are heavily insulated to reduce the heat loss to surroundings by radiation and so these losses are negligible

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