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# Condensate Pipes - Flash Steam Generated

## Calculate flash steam generation in condensate pipe lines.

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 (h il - h fl ) / h fe (1)

where

w % = ratio of flash steam generated (%)

h il = initial liquid enthalpy (kJ/kg)

h fl = final liquid enthalpy (kJ/kg)

h fe = enthalpy of evaporation (kJ/kg)

The condensate load can be calculated as

w c = w s w % / 100                                          (2)

where

w c = condensate load (kg/h)

w s = 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 :

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

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

h fe = 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

w c = (200 kg/h) (16.1 %) / 100

= 32 kg/h

## Related Topics

• ### Flash Steam

Generation of flash steam in steam and condensate systems. Thermodynamic fundamentals, heat loss, energy recovery and more.
• ### Sizing of Steam and Condensate Pipes

Dimensions of steam and condensate pipe lines. Calculate pressure losses, recommended velocities, capacities and more.

## Related Documents

• ### Condensate Generated in Cold Steam Pipes - SI Units

Huge amounts of condensate are generated when cold steam pipes are heated up must be drained from the pipes.
• ### Condensate Pipe Lines - Friction Resistance Imperial Units

Friction or major resistance in condensate pipe lines.
• ### Condensate Pipe Lines - Sizing

Flow and pressure loss in condensate return lines - SI Units.
• ### Flash Steam Energy Loss

When flash steam is generated and vented to the surroundings a considerable amount of energy is lost
• ### Flash Steam Generation - Fundamental Physics

Tutorial to the basic physics behind flash steam generation
• ### Flash Steam Generation - Imperial Units (psig)

When condensate passes steam traps - flash steam is generated.
• ### 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.
• ### Insulated Steam Pipes - Condensate Generated

Heat loss from steam pipes generates condensate which must be drained from the system - imperial units.
• ### Insulated Steam Pipes - Condensate Generated (kg/h per 100m)

Heat loss from steam pipes generates condensate which must be drained from the system.
• ### Properties of Saturated Steam - SI Units

Saturated Steam Table with steam properties as specific volume, density, specific enthalpy and specific entropy.
• ### Recommended Velocities in Steam Systems

The steam velocity in a steam distribution system should be within certain limits to avoid excessive wear and tear
• ### Saturated Steam - Properties - Imperial Units

Steam table with sensible, latent and total heat, and specific volume at different gauge pressures and temperatures.
• ### Saturated Steam - Properties for Pressure in Bar

Saturated Steam Table with properties like boiling point, specific volume, density, specific enthalpy, specific heat and latent heat of vaporization.
• ### Steam - Condensate Pipe Lines - Capacities (kW)

Maximum capacities for condensate pipe lines in kW steam consumption.
• ### Steam - Gravity Return Condensate Pipes - Capacities

Max. capacities (lb/hour) in gravity condensate return lines.
• ### Steam Flash Generation (bar)

The amount of flash steam generated depends on steam pressure and pressure in the condensate lines.
• ### Vapor and Steam

An introduction to vapor and steam.
• ### Volume Flow - Online Unit Converter

Convert between volume flow units like gpm, liter/sec, cfm, m3/h.

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## Citation

• The Engineering ToolBox (2005). Condensate Pipes - Flash Steam Generated. [online] Available at: https://www.engineeringtoolbox.com/flash-condenate-lines-d_959.html [Accessed Day Month Year].

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6.3.17

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