Flash Steam Calculator | Steam Recovery & Energy Balance
Flash Steam Calculator
Phase Separation & Stream Property Analysis
1. System Configuration
2. Process Parameters
bar g
Saturated Condensate
bar g
kg/h
Flash Efficiency
-- %
% Vaporization (Weight)
-- %
% Vaporization (Volume)
Stream Properties Matrix
| Property | Feed (Sat. Liquid) |
Vapor Out (Flash Steam) |
Liquid Out (Condensate) |
|---|---|---|---|
| Pressure | -- | -- | -- |
| Temperature | -- | -- | -- |
| Mass Flow | -- | -- | -- |
| Specific Enthalpy | -- | -- | -- |
| Density | -- | -- | -- |
| Specific Volume | -- | -- | -- |
| Volumetric Flow | -- | -- | -- |
Note: Assumes isenthalpic expansion (h_in = h_out) and complete phase
separation.
Technical Notes
Variable Definitions
- P1: Feed pressure to flash tank (gauge). Converted to absolute as P1,abs=P1,g+Patm.
- P2: Flash tank pressure (gauge). Converted to absolute as P2,abs=P2,g+Patm.
- αΉ: Inlet condensate mass flow rate.
- hf: saturated liquid enthalpy at given pressure.
- hg: saturated vapor enthalpy at given pressure.
- hfg: latent heat at P2, hfg=hgβhf.
- x: flash mass fraction (quality) generated in tank.
- αΉvap, αΉliq: vapor and liquid outlet mass flow rates.
- vf, vg: saturated specific volumes (mΒ³/kg) for liquid and vapor.
Formulas / Logic
- Thermo basis: throttling (isenthalpic) across the let-down/flash valve: hin=hout.
- Feed assumption: saturated condensate at P1 β hin=hf(P1).
- Flash fraction (mass): x = (hf(P1) β hf(P2)) / (hg(P2) β hf(P2)).
- Outlet streams: αΉvap=xΒ·αΉ, αΉliq=(1βx)Β·αΉ.
- Volumetric flow: QΜ = αΉΒ·v using saturated specific volumes at respective states.
- % Vaporization (volume): 100Β·(QΜvap/(QΜvap+QΜliq)).
Steam properties are obtained by linear interpolation of a
simplified saturation table. For high accuracy, use IAPWS-IF97 or
project-approved steam tables.
Assumptions / Notes
- Complete phase separation is assumed in the flash tank (no carry-under/carry-over).
- Feed is assumed saturated liquid at P1. If condensate is subcooled, calculated flash fraction will be lower; the tool flags negative flash.
- Atmospheric pressure is assumed Patm=1.01325 bar(a) for gaugeβabsolute conversion.
- Heat loss and kinetic energy changes are neglected (standard throttling approximation).
Standards / References
- Throttling/flash calculation is based on fundamental thermodynamics (steady-flow energy equation).
- For certified values, use IAPWS-IF97 steam properties or ASME steam tables.
- Design/operation should follow plant standards for flash tank sizing, venting, and safety (e.g., API/ASME practices as applicable).