Flash line1/22/2024 The resulting volumetric ratio can be contrasted as follows: Calculating Flash to Condensate Ratio (Metric) When high temperature condensate at 1.0 MPaG (145 psig) is discharged to lower pressure such as atmosphere, 16.1% by mass of that condensate flashes into steam. To understand with great detail, the specific volume of condensate at 100 ☌ (212 ☏) is 0.00104 m 3/kg (0.0167 ft 3/lb), and the specific volume of atmospheric steam is 1.67 m 3/kg (26.8 ft 3/lb). The greater the pressure difference, the larger the amount of flash steam generated at discharge. The animation below shows the difference in ratio of steam to condensate for examples 1 and 2 (see above) when applied to condensate return piping. Steam is much less dense than water, which means that a small increase in the percentage of flash steam generated can appear as a large increase in volume of steam generated. These steam clouds can often be misinterpreted as a live steam leak when in fact they are simply comprised of flashed condensate with fine water droplets in suspension, caused by the flashing of hot condensate being released to atmosphere.įor a more detailed explanation, please read the article: Is My Trap Leaking Live Steam?. One of the first things that come to mind when visualizing flash steam are the steam clouds that can appear outside a non-sub-cooling trap releasing to atmosphere. To compensate for the excess amount of energy, part of the water molecules absorb the excess energy as latent heat and evaporate to form steam. In other words, when hot condensate is discharged into a lower pressure environment, its enthalpy (total energy) remains the same, but its saturation point drops (the temperature at which condensate can exist in both the liquid and gaseous state). This phenomenon is known as flash evaporation. So what happens when condensate kept under pressure at 184 ☌ (363 ☏) is released to atmosphere? The condensate contains too much energy (enthalpy) to remain entirely liquid, and a portion of it evaporates, causing the temperature of the remaining condensate to drop to the saturation temperature (i.e., 100 ☌ or 212 ☏ if discharging to atmosphere). For example, the saturation point of water is 100 ☌ (212 ☏) at atmospheric pressure, but is 184 ☌ (363 ☏) at 1.0 MPaG (145 psig). Flash steam occurs because the saturation point of water varies according to pressure.
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