⑦ High-P Low-P turbine 斠書 Water in Boiler Water xing mber Steam trap Steam trap
A Rankine steam cycle modified for reheat and three closed feedwater heaters is shown below. The high-pressure turbine receives 80 kg/s of steam from the steam boiler. The feedwater heater exit states for the boiler feedwater and the condensed steam are the normally assumed ideal states. The following data tables give the saturation data for the pressures and data for h and s at selected states. Take cp, water = 4.18 kJ/kg·K.
| Process states and selected data | ||||
| State | P, kPa | T, °C | h, kJ/kg | s, kJ/kg·K |
| 1 | 10 | |||
| 2 | 5000 | |||
| 3 | 5000 | |||
| 4 | 5000 | |||
| 5 | 5000 | |||
| 6 | 5000 | |||
| 7 | 5000 | 700 | 3900 | 7.5136 |
| 8 | 2500 | 3615 | 7.5136 | |
| 9 | 2500 | 600 | 3687 | 7.5979 |
| 10 | 925 | 3330 | 7.5979 | |
| 11 | 300 | 3011 | 7.5979 | |
| 12 | 75 | 2716 | 7.5979 | |
| 13 | 10 | 2408 | 7.5979 |
| Saturation data | ||||
| P, kPa | T, °C | vf, m3/kg | hf, kJ/kg | sf, kJ/kg·K |
| 10 | 45.8 | 0.001010 | 191.8 | 8.149 |
| 75 | 91.8 | 0.001037 | 384.4 | 7.456 |
| 300 | 133.5 | 0.001073 | 561.4 | 6.992 |
| 925 | 176.5 | 0.001123 | 747.7 | 6.612 |
| 2500 | 224.0 | 0.001197 | 961.9 | 6.256 |
| 5000 | 263.9 | 0.001286 | 1154.5 | 5.974 |
Determine the net power output of the cycle in MW. Use steam tables. (You must provide an answer before moving on to the next part.)
The net power output of the cycle is ______________MW.
a) Sketch the T-s diagram for the cycle.
b) Write down equations to determine the mass flow rates at locations 2, 3, 6 and 7. In your calculations, for every 1 kg steam going through the boiler, x, y, z, and w are extracted at 2, 3, 6 and 7 , respectively
. c) Write down equations to determine the rate of work output (kJ/s) from turbines (total from both turbines) and the rate of work input (kJ/s) for pumps (total from both pumps)
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