A 15 kg/s steady supply of saturated-vapor steam at 500 kPa is required for drying a wood pulp slurry in a paper mill (see Fig. P9.79). It is decided to supply this steam by cogeneration; that is, the steam supply will be the exhaust from a steam turbine. Water at 20◦C, 100 kPa is pumped to a pressure of 5 MPa and then fed to a steam generator with an exit at 400◦C. What is the additional heat transfer rate to the steam generator beyond what would have been required to produce only the desired steam supply? What is the difference in net power?

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100 kPa Water + 20°C 10 kg/s Sat. vapor Steam 500 kPa supply FIGURE P9.79