Deaerator
Thermal deaerators are commonly used to remove dissolved gases in feedwater for steam-generating boilers.
[1][2] Dissolved oxygen in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment forming oxides (like rust).
Most deaerators are designed to remove oxygen down to levels of 7 parts per billion by weight or less, as well as essentially eliminating carbon dioxide.
[11][12][13] Between 1921 and 1933, George Gibson, Percy Lyon, and Victor Rohlin of Cochrane received deaerator / degasification patents for bubbling steam through liquid.
Deaeration is done by spraying feedwater into a chamber to increase its surface area, and may involve flow over multiple layers of trays.
The type of chemical added depends on whether the location uses a volatile or non-volatile water treatment program.
Flow-accelerated corrosion related failures have caused numerous accidents in which significant loss of property and life has occurred.
Dissolved oxygen in feedwater will cause serious corrosion damage in a boiler by attaching to the walls of metal piping and other equipment forming oxides (like rust).
Most deaerators are designed to remove oxygen down to levels of 7 parts per billion by weight or less, as well as essentially eliminating carbon dioxide.
Combined action of spray valves & trays guarantees very high performance because of longer contact time between steam and water.
[21][verification needed] Some designs use various types of packed beds, rather than perforated trays, to provide good contact and mixing between the steam and the boiler feed water.
[citation needed] The steam strips the dissolved gas from the boiler feedwater and exits via the vent valve at the top of the domed section.
If this vent valve has not be opened sufficiently, the deaerator will not work properly, resulting in feed water with a high oxygen content going to the boilers.
[citation needed] The deaerated water flows down into the horizontal storage vessel from where it is pumped to the steam generating boiler system.
[24][25] Vacuum deaerators can be rubber lined on the inside to protect the steel heads and shell from corrosion.
[26] In a typical design, the product is distributed as a thin layer on a high speed spinning disc via special feed system.
ASME Boiler and Pressure Vessel Code, NACE International, and HEI (Heat Exchange Institute) have recommendations on the type of testing required.
[31] NACE International (now known as Association for Materials Protection and Performance (AMPP)) and CIBO (Council of Industrial Boiler Owners) have several recommendations to increase the life of the deaerator unit.
[45] Deaerators are used in many industries such as co-generation plants, hospitals, larger laundry facilities, oil fields, oil refineries, off-shore platforms, paper mills, power plants, prisons, steel mills, and many other industries.
