Dear Nishtha
Deaeration are:
1. To remove oxygen, carbon dioxide and other non condensable gases from feed water
2. To heat the incoming makeup water and return condensate to an optimum temperature for:
a. Minimizing solubility of the undesirable gases
b. Providing the highest temperature water for injection to the boiler
Reason to Deaerate
The most common source of corrosion in boiler systems is dissolved gas: oxygen, carbon dioxide and ammonia. Of these, oxygen is the most aggressive. The importance of eliminating oxygen as a source of pitting and iron deposition cannot be over-emphasized. Even small concentrations of this gas can cause serious corrosion problems.
Process for deaeration
1. Mechanical deaeration.
2. Chemical Deaeration
Complete oxygen removal cannot be attained by mechanical deaeration alone. Equipment manufacturers state that a properly operated deaerating heater can mechanically reduce the dissolved oxygen concentrations in the feed water to 0.005 cc per liter (7 ppb) and 0 free carbon dioxide. Typically, plant oxygen levels vary from 3 to 50 ppb. Traces of dissolved oxygen remaining in the feed water can then be chemically removed with the oxygen scavenger.
CHEMICAL DEAERATION
Dosed chemical like hydrazine (N2H4)
O2 + NH2=NH2 = N2 + 2H2O
After chemically operation the O2 Conc. In BFW is ˂0.01 ppb
The inserts Nitrogen vented in atmosphere.
Please find attached herewith article on Deaeration.
Regards,
Prem Baboo
Vented gases from deaerator goes to atmosphere. There is no such point to economically harness the heat energy and DW water from this vented gas.
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