In a cogenerating steam power plant the turbine receives steam from a high-pressure steam drum (h = 3445.9 kJ/kg, s = 6.9108 kJ/kg K) and a low-pressure steam drum (h = 2855.4 kJ/kg, s = 7.0592 kJ/kg K), as shown in Fig. P9.80. For the turbine calculation, assume a mass-weighted average entropy and neglect entropy generation by mixing. The condenser is made as two closed heat exchangers used to heat water running in a separate loop for district heating. The high temperature heater adds 30 MW and the low temperature heater adds 31MWto the district heating water flow. Find the power cogenerated by the turbine and the temperature in the return line to the deaerator.

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5 kg/s 500 kPa 200°C 22 kg/s 6 MPa 510°C Steam turbine WT 13 kg/s 200 kPa 50 kPa, 14 kg/s 95°C 30 MW 31 MW 60°C www To district 415 kg/s heating 27 kg/s to deaerator FIGURE P9.80