Regarding my personal background in supply of modern Deaerators for BFW treatment , I developed a degassing system based on “spray &tray and reboiler ” technology which improves the degree of fluid purification, so reducing the gas quantity dissolved in the fluid on termination of thermal degassing compared with traditional Deaerators .
In brief, the deaerating Tower is composed by three stages , each of them is named respectively : atomizing , raining and reboiler part.
1st stage ) in the atomizing part the water is sprayed by means of gases are removed . It’s very important that the layer of water outgoing from each spray valve is the thinner as possible.
2nd stage ) in the second stage the water rains through a series of special designed stainless steel perforated trays , counter current to the steam flow. Fresh gas-free steam enters from the bottom of deaerating Tower and flows upwards by cross flow , perpendicular to the water flow. It reverses direction from tray level to level, entering at the bottom and exiting at the top. This is essential to achieve less than 7 ppb of oxygen effluent quality , as measurable following ASME PTC 12.3 test code according to HEI Std recommendations .
3rd stage) the peculiarity which makes the difference from other similar designs is the use of reboiler part. The entering steam goes through a column of water so that its pressure causes a gurgling through the water , stripping out the residual gases.
Gases O2 and CO2 mixed with a little steam flow-rate , are discharged to the external atmosphere through vent nozzles completed with calibrated orifices and vent condenser direct-contact type.
More than 200 installation give the prove of an high reliability in this process , officially covered by Patent in 2009 _N° WO 2009/068616 dated 04 June 2009 ( see attached copy and reference list).