Question 12.27: Steam at 70 bar and 450°C is supplied to a steam turbine. Af...
Steam at 70 bar and 450°C is supplied to a steam turbine. After expanding to 25 bar in high pressure stages, it is reheated to 420°C at the constant pressure. Next ; it is expanded in intermediate pressure stages to an appropriate minimum pressure such that part of the steam bled at this pressure heats the feed water to a temperature of 180°C. The remaining steam expands from this pressure to a condenser pressure of 0.07 bar in the low pressure stage. The isentropic efficiency of H.P. stage is 78.5%, while that of the intermediate and L.P. stages is 83% each. From the above data, determine :
(i) The minimum pressure at which bleeding is necessary.
(ii) The quantity of steam bled per kg of flow at the turbine inlet.
(iii) The cycle efficiency.
Neglect pump work.
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