The Integral Benefits of Iron Monitoring for Steam Generation Chemistry Control

By District Energy posted 01-21-2019 00:00


Brad Bueker, Ken Kuruc and Luke Johnson


In the early 1980s, researchers had concluded that dissolved oxygen (DO) ingress into condensate/feedwater was a prime factor for carbon steel corrosion (and unarguably corrosion of copper alloys) during normal operation of utility steam generators.

So, both mechanical deaeration and chemical methods (i.e., oxygen scavenger feed) were typically utilized to reduce DO concentrations to near zero as measured at the economizer inlet of conventional fossil-fired utility boilers. Oxygen scavenger (the more correct term is reducing agent) treatment combined with ammonia or a neutralizing amine for pH control came to be known as all-volatile treatment reducing [AVT(R)]. The chemistry induces formation of the familiar gray-black magnetite (Fe3O4) layer on carbon steel surfaces.

In 1986, the foundations of this chemistry received a severe jolt.

 “On December 9 of that year, an elbow in the condensate system ruptured at the Surry Nuclear Power Station (Virginia),” according to a 2005 report from the Electric Power Research Institute (EPRI). “The failure caused four fatalities and tens of millions of dollars in repair costs and lost revenues.”

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