Produce a schematic diagram of the system:
The steam that leaves the super-heater is expanded from 130bar at 535°C to 25.2bar at 310°C in a high pressure turbine. The steam from the exit of the HP turbine is reheated to 535°C in the boiler. The reheated steam is then expanded to 8.5bar at 378°C in the intermediate pressure turbine, after which a certain percentage of the steam is bled off to a feedwater heater. The remaining steam is then expanded through a low pressure turbine to 0.05bar and a dryness fraction of 0.94. All 'steam' entering the feed pumps shall be a saturated fluid.
a) Produce a schematic diagram of the system, together with an appropriate labelled T-s diagram.
b) Using steam tables only, calculate:
(i) The isentropic efficiencies of the three turbines;
(ii) The cycle efficiencies;
(iii) The percentage of steam bled off to the feedwater heater;
(iv) If the turbines generate 200MW power, how much cooling water must be used per hour, assuming that water can be returned to the river at only 10°C above its extraction temperature? (Assume that the specific heat capacity of water is 4.18 kJ/(kg·K));
(v) If a high pressure surface-type feedwater heater is placed between the boiler and HP feedwater pump to raise the feedwater temperature, configure the cycle and analyse the impact on the cycle performance.