Flash Steam Generation - Imperial Units (psig)
The amount of flash steam generated depends on steam pressure - the pressure in the condensate before it leaves the condensate trap - and the condensate pressure after the trap - the pressure in the condensate return pipe lines.
The diagram and table below indicates the ratio of flash steam generated at different pressures before and after condensate traps:
Steam Pressure before the Steam Trap (psig) | Flash Steam generated from Condensate (%) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Condensate Pressure after the Trap (psig) | |||||||||||
| 01) | 2 | 5 | 10 | 15 | 20 | 30 | 40 | 60 | 80 | 100 | |
| 5 | 1.7 | 1 | |||||||||
| 10 | 2.9 | 2.2 | 1.4 | ||||||||
| 15 | 4 | 3.2 | 2.4 | 1.1 | |||||||
| 20 | 4.9 | 4.2 | 3.4 | 2.1 | 1.1 | ||||||
| 30 | 6.5 | 5.8 | 5 | 3.8 | 2.6 | 1.7 | |||||
| 40 | 7.8 | 7.1 | 6.4 | 5.1 | 4 | 3.1 | 1.3 | ||||
| 60 | 10 | 9.3 | 8.6 | 7.3 | 6.3 | 5.4 | 3.6 | 2.2 | |||
| 80 | 11.7 | 11.1 | 10.3 | 9 | 8.1 | 7.1 | 5.5 | 4 | 1.9 | ||
| 100 | 13.3 | 12.6 | 11.8 | 10.6 | 9.7 | 8.8 | 7 | 5.7 | 3.5 | 1.7 | |
| 125 | 14.8 | 14.2 | 13.4 | 12.2 | 11.3 | 10.3 | 8.6 | 7.7 | 5.2 | 3.4 | 1.8 |
| 160 | 16.8 | 16.2 | 15.4 | 14.1 | 13.2 | 12.4 | 10.6 | 9.5 | 7.4 | 5.6 | 4 |
| 200 | 18.6 | 18 | 17.3 | 16.1 | 15.2 | 14.3 | 12.8 | 11.5 | 9.3 | 7.5 | 5.9 |
| 250 | 20.6 | 20 | 19.3 | 18.1 | 17.2 | 16.3 | 17.7 | 13.6 | 11.2 | 9.8 | 8.2 |
| 300 | 22.7 | 21.8 | 21.1 | 19.9 | 19 | 18.2 | 16.7 | 15.4 | 13.4 | 11.8 | 10.1 |
| 350 | 24 | 23.3 | 22.6 | 21.6 | 20.5 | 19.8 | 18.3 | 17.2 | 15.1 | 13.5 | 11.9 |
| 400 | 25.3 | 24.7 | 24 | 22.9 | 22 | 21.1 | 19.7 | 18.5 | 16.5 | 15 | 13.4 |
1) It is common to vent the condensate system to the atmosphere - where the gauge pressure is 0 psig.
- 1 psi (lb/in2) = 6,894.8 Pa (N/m2) = 6.895x10-3 N/mm2 = 6.895x10-2 bar
Example - Generated Flash Steam
A condensate system is vented to the surroundings and the pressure in the condensate return system after the steam traps is therefore 0 psig (atmospheric pressure). The steam pressure before the steam traps is 160 psig.
According the table above 16.8% of the condensate evaporates as flash steam passing the traps.
Note! Without any flash recovery system the energy in the flash steam will be lost to the surroundings.
If you prefer SI units - go here!
Related Topics
• Flash Steam
Generation of flash steam in steam and condensate systems. Thermodynamic fundamentals, heat loss, energy recovery and more.
• Steam and Condensate
Design of steam & condensate systems with properties, capacities, sizing of pipe lines, system configuration and more.
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