Boiler Blowdown Flash Steam Recovery Calculator

Boiler Blowdown Flash Steam Recovery Calculator

When high-pressure boiler blowdown water drops into a lower-pressure flash tank, some of it instantly turns to steam - simply because that water was carrying more energy than liquid water can hold at the lower pressure.

The Formula

Flash % = (h1 - hf2) / hfg2 × 100

Worked Example

Blowdown enthalpy 900 kJ/kg, flash tank saturated liquid enthalpy 419 kJ/kg, flash tank latent heat 2,257 kJ/kg: Flash % = (900-419)/2257 × 100 ≈ 21.3%.

How to Use This Calculator

1. Enter the blowdown water's enthalpy at boiler pressure.
2. Enter the saturated liquid enthalpy at the flash tank's (lower) pressure.
3. Enter the latent heat of vaporization at the flash tank pressure.

This recoverable flash steam can be routed to a deaerator or low-pressure steam system rather than wasted, making blowdown heat recovery a genuine efficiency opportunity many facilities overlook.