Should you inject condensate treatment into the boiler via feedwater or directly into the steam distribution header?
To answer this question, we must first understand how condensate treatment works and what it is for.
When boiler water alkalinity breaks down, it produces carbon dioxide, which dissolves in the condensate and forms carbonic acids. These, in turn, can dissolve metal rapidly, corroding the condensate line. “Condensate Treatment” refers to pH-adjusting treatments: Adding chemicals to the steam to preserve alkalinity and prevent corrosion.
The most common materials for condensate pH conditioning are volatile amines, which, due to their low flash point and alkaline nature, are easily volatilized into the steam, and re-dissolve in the condensate to neutralize the effects of carbonic acid.
So where should you inject them?
Because the cost of organic amines is high, you want to get as much as possible out of them. The neutralizing amines you are using will generally designate a specific distribution ratio, meaning that for every pound fed into the boiler, only a portion is volatized and goes out with the steam. The rest stays in the boiler and is wasted through the blowdown process.
However, when injected directly into the steam header, 100 percent of the chemical is volatized and is carried through the system to treat the condensate.
Therefore, it’s usually best to inject condensate treatment directly into the steam header. In any case, you should feed amines into the steam flow somewhere before the condensation point. This would be immediately after the boiler, if the entire system is being treated, or at a convenient header location if your goal is to treat steam that’s going to a specific piece of equipment or plant section.
Want to learn how Win-Sam can help preserve equipment in your central energy plant? Contact us here.
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