How to use a rotary film deaerator
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Dear teacher, there is a membrane deaerator in the old workshop; it has been there for 7 years now, and steam has never been fed into it – it has been used as a buffer tank all this time. New installations these days also come equipped with a membrane deaerator, and I would like to know how to use it. Currently, 4 bar of steam is being used; what should be the temperature control for the deaerator? What is the pressure inside the deaerator? Does the deaerator continuously discharge steam? Or is it discharged outward when a certain pressure is reached? An electric contact level gauge is installed on the deaerator; why is such a level gauge also used?
It looks no different from ordinary thermal deaerators. This type of deaerator typically maintains a temperature of 104°C and a pressure of 20 kPaG, with steam being continuously discharged outward； This type of deaerator wastes steam and consumes heat. There is now a technology based on degassing membranes that uses vacuum for deoxygenation and operates at room temperature, which can reduce steam losses and cut the boiler’s steam consumption by about 2-3%
Everything has its advantages and disadvantages; the advantage of steam deaeration is that it serves as a heat exchange process simultaneously, thereby increasing the temperature of the water entering the boiler. And the deoxygenation equipment you mentioned requires additional heat exchange equipment to ensure the temperature of the water entering the boiler.
Membrane deoxidation technology can deoxidize only the boiler make-up water; there is no need to deoxidize the recovered condensate again. As a result, there is no issue related to heat exchange, and steam emissions are reduced, thereby lowering the load on the boiler
I understand what you mean; you are referring to the water used to replenish the boiler (i.e., deionized water or softened water), which is used for deoxygenation. It is precisely this water that needs to be heated in order to reach the required temperature for feeding it into the boiler. Condensate water is itself deoxygenated water; it is merely reused, so it’s fine if deoxygenation is not carried out. Is there no requirement for the temperature of the water used to top up the boilers there; is the water simply supplied at room temperature?
The boiler feed pump delivers water at a higher temperature, but make-up water can be deoxygenated before being added to the water tank, thereby preventing pipe bursts in the boiler due to low water inlet temperature
Got it; it’s still a misunderstanding caused by different concepts. Thanks for clarifying, Lonely. :handshake