Degassed Cation Conductivity

I just got back from the Electric Utility Chemistry Workshop held in Champaign, Illinois last week. There were quite a lot of topics...some of them even interesting! 

Several papers focused on "new" technologies that were not really new at all. One paper in particular highlighted a method using capillary electrophoresis as a new way of determining chloride and sulfate in the parts-per-billion range. Unfortunately, the cost of the device was hinted at being "merely" 2/3 the cost of an Ion Chromatograph (which can exceed $100,000)! 

Degassed cation conductivity measurements, while not as definitive as an IC, can provide a lot of data for a fraction of the cost. For example, see the data below showing the relationship between conductivity and parts-per-billion of chloride:

• 0.055 uS/cm = 0.00 ppb Chloride
• 0.075 uS/cm = 2.00 ppb Chloride
• 0.095 uS/cm = 4.00 ppb Chloride
• 0.115  uS/cm = 6.00 ppb Chloride

So, with every 0.02 uS/cm increase, we can assume a 2 ppb increase in chloride (this does not take into account sulfate or lighter amines such as acetate and formate). EPRI and IAPWS Guidelines list a steam turbine quality limit of 2 ppb for chloride. My personal experience utilizing the Martek Dissolved Carbon Dioxide Analyzer in dozens of power plants has resulted in degassed cation conductivity measurements anywhere between 0.065 to 0.93 uS/cm. Therefore, one could easily "guesstimate" a parts-per-billion chloride measurement within a few ppb and pocket at least $50,000 in savings.

Not a bad return on investment. 

If you're interesting in learning more about degassed cation conductivity (and any other water quality measurement), or want to learn more about what was presented at the Conference, don't hesitate to contact us.