Consider a cogeneration power plant modified with regeneration. Steam enters the turbine at 6 MPa and 450°C at a rate of 20 kg/s and expands to a pressure of 0.4 MPa. At this pressure, 60 percent of the steam is extracted from the turbine, and the remainder expands to a pressure of 10 kPa. Part of the extracted steam is used to heat feedwater in an open feedwater heater. The rest of the extracted steam is used for process heating and leaves the process heater as a saturated liquid at 0.4 MPa. It is subsequently mixed with the feedwater leaving the feedwater heater, and the mixture is pumped to the boiler pressure. The steam in the condenser is cooled and condensed by the cooling water from a nearby river, which enters the adiabatic condenser at a rate of 463 kg/s.
1. The total power output of the turbine is
(a) 17.0 MW (b) 8.4 MW (c) 12.2 MW
(d) 20.0 MW (e) 3.4 MW
2. The temperature rise of the cooling water from the river in the condenser is
(a) 8.0°C (b) 5.2°C (c) 9.6°C
(d) 12.9°C (e) 16.2°C
3. The mass flow rate of steam through the process heater is
(a) 1.6 kg/s (b) 3.8 kg/s (c) 5.2 kg/s
(d) 7.6 kg/s (e) 10.4 kg/s
4. The rate of heat supply from the process heater per unit mass of steam passing through it is
(a) 246 kJ/kg (b) 893 kJ/kg (c) 1344 kJ/kg
(d) 1891 kJ/kg (e) 2060 kJ/kg
5. The rate of heat transfer to the steam in the boiler is
(a) 26.0 MJ/s (b) 53.8 MJ/s (c) 39.5 MJ/s
(d) 62.8 MJ/s (e) 125.4 MJ/s

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h 3302.9 kJ/kg 20 kg/s Boiler- -2665.6 kJ/kgTurbine 2128.8 Process heater #610.73 Condenser) ΔΤ FWH 463 kg/s h -h- ho-604.06 P h2192.20 191.81