Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

Condensate Pipes - Flash Steam Generated

Sponsored Links

In general condensate lines should be designed to handle start-up conditions with huge amounts of condensate generated from cold steam pipes and cold heating equipment. As a rule of thumb - the maximum condensate load at start up is often twice the maximum steam load during operation.

Sometimes, especially in high pressure steam systems with heavy load heat exchangers, generated flash steam may be the limitation of the condensate lines.

Flash steam generated  can be calculated as

w% = 100 (hil - hfl) / hfe                                      (1)


w% = ratio of flash steam generated (%)

hil = initial liquid enthalpy (kJ/kg)

hfl = final liquid enthalpy (kJ/kg)

hfe = enthalpy of evaporation (kJ/kg)

The condensate load can be calculated as

wc = ws w% / 100                                          (2)


wc = condensate load (kg/h)

ws = steam flow rate (kg/h)

Example - Generated Flash Steam

The gauge pressure in a heat exchanger before the steam trap is 10 bar. The condensate lines and condensate receiver are vented so the gauge pressure is equal to 0 bar (atmospheric).

From the steam properties table

hil = 781 kJ/kg, initial liquid enthalpy at 11 bar abs

hfl = 418 kJ/kg, final liquid enthalpy at 1 bar abs

hfe = 2258 kJ/kg, enthalpy of evaporation at 1 bar abs

The flash steam generated  can be calculated as

w% = 100 ((781 kJ/kg) - (418 kJ/kg)) / (2258 kJ/kg)

     = 16.1 %     

If the steam flow rate through the heat exchanger is 200 kg/h - the condensate load can be calculated as

wc = (200 kg/h) (16.1 %) / 100

    = 32 kg/h  

Sponsored Links

Related Topics

Flash Steam

Flash steam generation - thermodynamic fundamentals, heat loss, energy recovery and more.

Pipe Sizing

Sizing of steam and condensate pipe lines - pressure loss, recommended velocity, capacity and more.

Related Documents

Condensate Pipe Lines - Capacities (kW)

Maximum capacities for condensate pipe lines in kW steam consumption.

Flash Steam Generation - SI-units

When condensate leaves the steam traps - flash steam is generated. Amount of flash steam generated at different pressures - kN/m2.

Properties of Saturated Steam - SI Units

Saturated Steam Table with steam properties as specific volume, density, specific enthalpy and specific entropy.

Sponsored Links


Search Engineering ToolBox

  • the most efficient way to navigate the Engineering ToolBox!

SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!


We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

This website use cookies. By continuing to browse you are agreeing to our use of cookies! Learn more