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This application note on oxidation corrosion discusses how to reduce corrosion in power plant water systems, and therefore prevent damage to critical and expensive equipment. One of the major causes of corrosion of the metallurgy of a water system includes the presence of dissolved oxygen. To maintain appropriate water quality, it is essential to control oxygen concentration. The measurement and control of dissolved oxygen levels is a major tool to reduce corrosion in power plants.
First, the application note explains the two primary strategies to control corrosion, which is caused by dissolved oxygen contamination. The first strategy is all volatile treatment – reducing (AVT(R)). AVT(R) is used when copper alloys are present in the feedwater train and/or where the feedwater quality is low. This strategy uses deaeration and a reducing agent to decrease the DO to low, single-digit ppb concentrations. An inaccurate measurement can lead to the addition of either too much or not enough reducing agent. This can cause continued corrosion or represents a waste of money and can lead to other unwanted side effects.
The alternate strategy, all volatile treatment – oxidizing (AVT(O)) is employed for all-ferrous feedwater trains and can only be used when feedwater quality is high.
Finally, this application note provides information on the exact locations where dissolved oxygen is measured and how a complete METTLER TOLEDO system, including the Pure Water Optical Dissolved Oxygen Sensor with the M800 Transmitter, provides optimum dissolved oxygen measurements to reduce the risk of corrosion and expensive equipment downtime.
