TOTAL ORGANIC CARBON
Organic carbon may decompose to form acetic, formic, and other carboxylic acids, as well as carbon dioxide in the steam cycle. These anions raise cation conductivity. The rate of conversion of organic carbon to acidic species depends on many parameters.
Organic compounds may also contain other elements such as chlorine and sulfur. For example, if the water source from the plant is treated wastewater, it is often highly chlorinated and charged with ha- logenated organic compounds. These compounds are often non-ionic species that can slip through conventional water pretreatment systems. At elevated temperature and pressure these can breakdown into chloride and sulfate in the steam.
In particular, halogenated organic compounds in the pretreatment and demineralized water should be quantified and steps taken to reduce these to the lowest level possible.
If the cation conductivity exceeds normal values, elevated TOC should be considered as a possible cause. Even with TOC < 300 ppb, high cation conductivity in condensate or steam may require that water treatment equipment be added to remove sufficient TOC to reach acceptable cation conductivity.
Continuous monitoring for organics, (i.e. TOC), may be required on process return condensate if cation conductivity or pH measurement does not detect potential organic contamination. These limits are excluding any TOC added via organic treatment chemicals.