Steam Turbines..
Steam is expanded from 90 bar, 412°C to 4.5 bar saturation in a high pressure turbine, afterwhich a certain percentage of the steam is bled off to a feed heater. The remaining steam is then expanded through a low pressure turbine to 1.0 bar and dryness fraction of 0.93. All ‘steam’ entering the feed pumps shall be a saturated fluid. Produce a schematic diagram of the system, together with appropriate Ts diagram. Using steam tables only, calculate
a)the isentropic efficiencies of both turbines
b)the percentage of steam bled of to the feed heater
c)the power generated by the turbines per unit mass of steam leaving the boiler
d)the energy available for low grade heating from the condenser
Neglect feed pumps and state any assumptions made
For question a) i have the following working, however im not sure if its correct Isentropic Efficiency = (h1h2/h1h2s)
= (31522745)/(31522525)
=407/627
= 0.6491
Isentropic Efficiency for high pressure turbine= 65%
As for the other 3 questions, they have my stumped, im not even sure where to start. I cant find any equations online. Any help in being pushed in the right direction would be greatly appreciated.
Thanks in advance.
