500 MMSCFD of supercritical steam generated in the steam generator (shown in the sketch below) at 1 1 250 and 550o P bar T C = = are expanded into a series of two condensing steam turbines (CSTs) to a final pressure of 5P kPa = 8 as shown in the diagram below. To improve the efficiency of the cycle, part of the exhaust of the High Pressure (HP) Turbine at 2 3 P P bar = = 40 is reheated to 4 550o T C = and sent to the Low Pressure (LP) Turbine for further expansion, and part is throttled down to 8P bar = 8 and mixed with the discharge of the Condensate Pump of the Condenser effluent in the Overflow Feed Water Heater (OFWH) tank in order to preheat the boiler feed water (which also serves as the Deaerator). This power cycle is known as the Regenerative Rankine Cycle with Open Feed Water Heater and it is shown in the diagram below:

If the efficiency of the each turbine is 80% and that of the condensate and boiler feed water pumps 75% calculate:

1. The flow rate of the steam bypass to the throttling valve (Stream ) in MMSCFD

2. The amount of power generated by the cycle in MW.

3. The efficiency of the Regenerative Rankine Cycle with OFWH.

4. The amount of cooling water in gpm (gallons per minute) required for the condenser, assuming a water temperature rise of 11 . o C You may take the specific heat capacity of water to be C kJ kg C P = 4.184 / . ( )

5. If the power plant is using bituminous coal as fuel in the steam generator give an estimate of the annual CO2 emissions in tonnes [1 tonne= 1000 kg]. You may take the ash content of coal to be 15% and the heating value of coal to be approximately 18 MJ/kg. (FYI see Heating Values of Various Fuels below)

Heating Values of Various Fuels. The heat value of a fuel is the amount of heat released during its combustion. Also referred to as energy or calorific value, heat value is a measure of a fuel's energy density, and is expressed in energy (joules) per specified amount (e.g. kilograms). Uranium figures are based on 45,000MWd/t burn-up of 3.5% enriched U in LWR MJ=106Joule,GJ=109J MJ to kWh @ 33% efficiency: x0.0926 One tonne of oil equivalent (toe) is equal to 41.868GJ