Consider a cogeneration power plant that is modified with reheat and that produces 3 MW of power and supplies 7 MW of process heat. Steam enters the high-pressure turbine at 8 MPa and 500°C and expands to a pressure of 1 MPa. At this pressure, part of the steam is extracted from the turbine and routed to the process heater, while the remainder is reheated to 500°C and expanded in the low-pressure turbine to the condenser pressure of 15 kPa. The condensate from the condenser is pumped to 1 MPa and is mixed with the extracted steam, which leaves the process heater as a compressed liquid at 120°C. The mixture is then pumped to the boiler pressure. Assuming the turbine to be isentropic, show the cycle on a T-s diagram with respect to saturation lines, and disregarding pump work, determine (a) the rate of heat input in the boiler and (b) the fraction of steam extracted for process heating.
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Thermodynamics: An Engineering Approach
- An ideal cogeneration steam plant is to generate power and 9400 kJ/s of process heat. Steam enters the turbine from the boller at 7 MPa and 500°C. One-fourth of the steam is extracted from the turbine at 600 kPa pressure for process heating. The remainder of the steam continues to expand and exhausts to the condenser at 10 kPa. The steam extracted for the process heater is condensed in the heater and mixed with the feedwater at 600 kPa. The mixture is pumped to the boiler pressure of 7 MPa. (5) ↑ Boiler Pump II 6 O process process Process heater (3) Turbine (D) Condenser Pump I Show the cycle on a T-s diagram with respect to saturation lines. (8) 1arrow_forwardSteam is generated in the boiler of a cogeneration plant at 8 MPa and 400C at a steady rate of 5 kg/s. In normal operation, steam expands in a turbine to a pressure of 0.4 MPa and is then routed to the process heater, where it supplies the process heat. Steam leaves the process heater as a saturated liquid and is pumped to the boiler pressure. In this mode, no steam passes through the condenser, which operates at 15 kPa. Draw the schematic and T-S diagrams. Label the points by setting point 1 at the condenser outlet, point 2 at the 1st pump (after the condenser) outlet, point 3 at the process heater outlet, point 4 at the 2nd pump (after the process heater) outlet, point 5 at the boiler inlet (after mixing chamber), point 6 at the boiler outlet, point 7 at the process heater inlet (no throttle valve), and point 8 at the condenser inlet. Use 2 decimal places for the enthalpy and other energies in solving and for the final answers. For the steam quality (x) and entropy (s), use 4 decimal…arrow_forwardSteam is generated in the boiler of a cogeneration plant at 9 MPa and 450C at a steady rate of 5 kg/s. In normal operation, steam expands in a turbine to a pressure of 0.5 MPa and is then routed to the process heater, where it supplies the process heat. Steam leaves the process heater as a saturated liquid and is pumped to the boiler pressure. In this mode, no steam passes through the condenser, which operates at 20 kPa. Draw the schematic and T-S diagrams. Label the points by setting point 1 at the condenser outlet, point 2 at the 1st pump (after the condenser) outlet, point 3 at the process heater outlet, point 4 at the 2nd pump (after the process heater) outlet, point 5 at the boiler inlet, point 6 at the boiler outlet, point 7 at the process heater inlet, and point 8 at the condenser inlet. Use 2 decimal places for the enthalpy and other energies in solving and for the final answers. For the steam quality (x) and entropy (s), use 4 decimal places in solving. For the specific…arrow_forward
- Steam is generated in the boiler of a cogeneration plant at 9 MPa and 450C at a steady rate of 5 kg/s. In normal operation, steam expands in a turbine to a pressure of 0.5 MPa and is then routed to the process heater, where it supplies the process heat. Steam leaves the process heater as a saturated liquid and is pumped to the boiler pressure. In this mode, no steam passes through the condenser, which operates at 20 kPa. Draw the schematic and T-S diagrams. Label the points by setting point 1 at the condenser outlet, point 2 at the 1st pump (after the condenser) outlet, point 3 at the process heater outlet, point 4 at the 2nd pump (after the process heater) outlet, point 5 at the boiler inlet, point 6 at the boiler outlet, point 7 at the process heater inlet, and point 8 at the condenser inlet. Use 2 decimal places for the enthalpy and other energies in solving and for the final answers. For the steam quality (x) and entropy (s), use 4 decimal places in solving. For the specific…arrow_forwardAn Ideal cogeneration steam plant is to generate power and 9400 kJ/s of process heat. Steam enters the turbine from the boller at 7 MPa and 500°C. One-fourth of the steam is extracted from the turbine at 600 kPa pressure for process heating. The remainder of the steam continues to expand and exhausts to the condenser at 10 kPa. The steam extracted for the process heater is condensed in the heater and mixed with the feedwater at 600 kPa. The mixture is pumped to the boller pressure of 7 MPa. Boiler Pump II Determine the utilization factor. The utilization factor is process Process heater %. (3 Turbine Condenser Pump I (8)arrow_forwardSteam is generated in the boiler of a cogeneration plant at 10 MPa and 450C at a steady rate of 5 kg/s. In normal operation, steam expands in a turbine to a pressure of0.5 MPa and is then routed to the process heater, where it supplies the process heat. Steam leaves the process heater as a saturated liquid and is pumped to the boiler pressure. In this mode, no steam passes through the condenser, which operates at 20 kPa. (a) Determine the power produced and the rate at which process heat is supplied in this mode. (b) Determine the power produced and the rate of process heat supplied if only 60 percent of the steam is routed to the process heater and the remainder is expanded to the condenser pressurearrow_forward
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