Rising costs of power generation as a result of increased condenser tube scaling and
corrosion have become critical areas that need intervention at Eskom’s power stations in
South Africa. In the past few years, the quality of cooling and raw water has deteriorated
with increased concentrations of scale formation metals such as calcium (Ca) and
magnesium (Mg) as well as Natural Organic Matter (NOM). The Dissolved Organic Matter
(DOC) fraction of NOM in the water forms complexes with metals Ca and Mg under various
conditions. In this study, the Cooling Water (CW) and Raw Water (RW) at Lethabo and
Duvha power stations were sampled and were analyzed for metals as well as organics and
the data obtained was fitted into a Visual MINTEQ chemical model and Langelier Saturation
Index (SI) calculations coupled with calcium carbonate precipitation potential models. The
data obtained indicated that as the DOC concentration increased, the SI values decreased
which may be attributed to the to complexation of Ca and Mg (the scaling metals) bound
to DOC, leaving relatively lower concentrations of the free Ca and Mg ions until the reactive
sites of DOC were saturated. The seasonal changes affect pH, DOC and concentrations of
other metals present in the water that influenced complex formation and scaling.
Real Time Impact Factor:
Pending
Author Name: Heena Madhav
URL: View PDF
Keywords: Scaling Potential; Metal-organic Complexes; Visual MINTEQ
ISSN: 2517-7427
EISSN:
EOI/DOI: 10.31021/jwt.20181103
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