  
When latent heat of steam is given to process, steam condenses to water at saturated temperature. Thus depending on the pressure during condensation, the temperature of water may be 100 oC or more. Sub-cooled condensate is always below 99 oC as this condensate loses it's specific heat to the process. The condensate is at saturation temperature and therefore contains usable heat energy; it would be waste of money and resources, if not recycled for reuse as boiler feed water or any process hot water requirement. The condensate recovery lines always contain mixture of Flash Steam and Condensate. Flash steam occupies upto 80 to 95 % of pipe volume depending upon steam pressure at discharge of the equipment. The best arrangement is to return it to the boiler house, where it can be used as boiler feed water without any further treatment, saving fuel, raw water and chemicals needed for boiler feed treatment. You can also use the condensate as hot process water, so you use the important enthalpy for heating coils or heat exchange units. Alternatively, it is common practice in the plating processes to run the condensate directly into hot rinse tanks. This provides the hot water necessary for final rinsing of articles that have been treated and produces a saving of live steam that would otherwise be needed to heat the water. Flash steam from condensate When hot condensate under pressure is released to a lower pressure, its temperature must drop very quickly to the boiling point for the lower pressure as shown in the steam tables. The surplus heat is utilized by the condensate as enthalpy of evaporation, causing some of it to re-evaporate into steam. This steam is called "flash steam". The best way to recover and utilize flash steam is to let the steam and condensate mixture pass through what is known as a Flash Vessel. The flash vessel separates the steam from the condensate, so there is some additional steam you can use for your process as well. Compressing flash steam for higher pressure The flash steam pressure may vary from 0 bar g to any pressure depending on the condensate pressure. If this pressure is not enough for the use of the inline equipment, the pressure of the flash steam must be raised to the required level. A Thermocompressor is the right tool in this situation. It compresses low pressure steam to usable pressure levels and thereby reclaims the heat energy in the low pressure steam, which otherwise would have been wasted.
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