As outlined in chapter "2.9 Sizing valves for steam", page 40, it must be determined first whether a supercritical or subcritical pressure ratio exists in the plant.
Example 1:
By way of calculation
Saturated steam = 151.8 °C Prepressure p1 = 500 kPa (5 bar) Steam mass flow |
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Given |
Pressure ratio = 30 % |
Pressure ratio ≥ 42 % |
Subcritical pressure ratio |
Supercritical pressure ratio |
|
Required |
kvs, valve type |
kvs, valve type |
Solution |
 |
|
 |
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kv = 8.83 m3/h |
kv = 8.09 m3/h |
|
Selected |
kvs = 10 m3/h 🡪 VVF53.25-10 |
kvs = 8 m3/h 🡪 VVF53.25-8 |
= 460 kg/h
Example 2:
With chart
Given |
Saturated steam = 111.4 °C Prepressure p1 = 150 kPa (1.5 bar) Steam mass flow Differential pressure = 40 kPa (0.4 bar) |
Required |
kvs, valve type |
Solution |
|
Selected |
kvs value: 5 m3/h 🡪 VVF53.25-5 |
= 75 kg/hExample 3:
With chart
Given |
Superheated steam = 251.8 °C Saturated steam = 151.8 °C Superheating Prepressure p1 = 500 kPa (5 bar) Steam mass flow Differential pressure = 200 kPa (2 bar) |
Required |
kvs, valve type |
Solution |
|
Selected |
kvs value: 3.15 m3/h 🡪 VVF53.15-3.2 |
= 100 K