Consider a steam turbine in which steam enters at 10.45 MPa and 780 K with a flow rate of 38.739 kg/s. As shown in the sketch for Problem 3.55, a portion of the steam is extracted from the turbine after partial expansion at three different locations. 

The extracted steam is then led to various heat exchangers. The mass flow rates and the temperatures and pressures at each extraction point are given in the following table:

The remaining wet steam exits the turbine at 11.5 kPa with a quality of 0.88.

(i) Determine the minimum pipe diameters required to restrict the maximum inlet velocity to 50 m/s, the maximum extraction velocities each to 75 m/s, and the turbine outlet velocity to 130 m/s. Use the NIST software to obtain any necessary steam properties.

(ii) Use the NIST software to create a temperature specific volume plot showing the various state points and their associated isobars. You will have to locate the state points by hand, but the software can create the isobars.

Problem 3.55

Consider a steam turbine in which steam enters at 10.0 MPa and 780 K with a flow rate of 39.0 kg/s. As shown in the sketch, a portion of the steam is extracted from the turbine after partial expansion at three different locations. The extracted steam is then led to various heat exchangers. The mass flow rates and the temperatures and pressures at each point are given in the following table:

The remaining wet steam exits the turbine at 12.0 kPa with a quality of 0.88. 

(i) Determine the minimum pipe diameters required to restrict the maximum inlet velocity to 40 m/s, the maximum extraction velocities each to 65 m/s, and the turbine outlet velocity to 120 m/s. Use the tables in Appendix B to obtain any necessary steam properties.

(ii) Sketch a temperature–specific-volume plot showing the various state points and their associated isobars.

Transcribed Image Text:

Extraction location 123 2 in (kg/s) 4.343 4.345 2.871 P (MPa) 3.054 0.332 0.136 T (K) or x 620 482 X = 0.949