ME321 (Winter 08) - Take-home Quiz 2 --------------- Name________________________

Supercritical Steam Power Plant with Reheat - Part 2

Recall Take-home Quiz 1 in which we analized the proposed supercritical, coal fired steam power plant for Athens, Ohio to be cooled by water from the Hocking river. Following our criticism of the low pressure in the condenser which would allow air to leak into the system, Ace Power Systems resubmitted the design including a de-aerator for our further evaluation. This approach does not alter the system performance, hence we accept it as a solution. In this quiz we would like to evaluate the two turbines as well as the suitability of using the water from the Hocking river to condense the steam in the condenser.

1. Using the data shown on the diagram neatly sketch the the two turbine processes ((1)-(2) and (3)-(4)) on the enthalpy-entropy h-s "Mollier" diagram below. Sketch also the equivalent isentropic turbine processes on the diagram, and indicate the actual turbine specific work as well as the isentropic turbine specific work for both turbines on the h-s diagram.

2. Using steam tables, determine the turbine adiabatic efficiency hT. of both turbines, and state whether you think that they are feasible and suitable choices for this application.

3. Use the steam tables to determine the heat rejected to the cooling water in the condenser (MW).

4. Assume that all the heat rejected in the condenser is absorbed by cooling water from the Hocking River. To prevent thermal pollution the cooling water is not allowed to experience a temperature rise above 10°C. If the steam leaves the condenser as saturated liquid at 40°C, determine the required minimum volumetric flow rate of the cooling water (cubic meters/minute).

5. Discuss whether you think that the proposed system can be cooled by the Hocking river. You will need to do some research to determine the minimal seasonal flow in the river in order to validate your decision.

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Declaration of Honesty - I hereby declare that this take-home quiz is my own work, and that I did not collaborate with or receive help from anyone else while doing it.

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