Case Study • Eskom Wet-Cooled Coal
Kriel Power Station
Mexel®432 was applied at Kriel Power Station as part of Eskom's evaluation of film-forming amine chemistry for cooling-water treatment. Station data showed improved condenser performance during the treatment period.
Station type
Wet-cooled coal
Units treated
Selected unit(s)
Chemistry
Mexel®432
Status
Completed
Background
Station context
Kriel Power Station is a wet-cooled coal-fired plant in Mpumalanga. Like many Eskom stations of its generation, it uses large volumes of cooling water and has historically faced challenges with condenser fouling, biofouling and variable raw-water quality.
The condenser and cooling-water system are significant contributors to overall station efficiency. Fouling at the cold end — even modest fouling — can quietly erode heat rate and increase coal consumption per net MWh.
Why Mexel®432 was considered
Traditional multi-chemical programs (biocides, anti-scalants, dispersants, corrosion inhibitors) were in use but did not always deliver stable condenser performance. Mexel®432 was proposed as a single, film-forming treatment that could address multiple fouling mechanisms at once.
The evaluation was conducted through Eskom engineering to ensure a structured, protocol-based approach rather than an ad-hoc trial.
Intervention approach
Phase 1
Baseline data collection
Condenser performance data was collected before Mexel®432 treatment began. Key metrics included terminal temperature difference (TTD), cooling-water temperature rise (TR), condenser vacuum and relevant water chemistry parameters.
Phase 2
Mexel®432 treatment
Mexel®432 was dosed into the cooling-water system at agreed concentrations. The film-forming chemistry was allowed to establish on condenser tube surfaces and other wetted areas. Dosing was monitored and adjusted as needed.
Phase 3
Performance monitoring
Condenser performance was monitored during treatment. The same metrics collected at baseline were tracked to allow direct comparison. Station operating conditions were noted to account for load and ambient variations.
Observed results
The following observations are based on station data collected during the Kriel evaluation. They are presented as indicative results, not as guaranteed outcomes for other stations or conditions.
Condenser cleanliness
Improved
Visual and performance indicators showed cleaner tube surfaces during treatment.
TTD stability
More stable
Terminal temperature difference showed less variability during treatment periods.
Vacuum performance
Maintained
Condenser vacuum remained stable, consistent with improved tube cleanliness.
Biofouling
Reduced
Biofilm and organic deposits were visibly reduced at condenser tube inlets.
Important note on results
These results are specific to the Kriel evaluation and the conditions at that time. Condenser performance depends on many factors including raw-water quality, load profile, ambient conditions and existing asset condition. TES pilots at other stations should establish their own baselines and measure against their own KPIs.
Lessons learned
Baseline data matters
Without clear baseline data, it is difficult to demonstrate improvement. The verification protocol structure (baseline → intervention → post-intervention) is essential for credible evaluation.
Film formation takes time
Mexel®432 works by establishing a protective film. This is not instant — some patience is required before full effect is observed. Rushing to judgement too early can miss the benefit.
Station conditions vary
What works at Kriel may perform differently at another station with different water quality, load patterns or asset condition. Each site needs its own assessment.
TES is a system, not just a chemical
The Kriel experience informed the development of TES as a complete system: Mexel®432 chemistry, IoT dosing, data view and verification framework working together.
From Kriel to TES
The Kriel experience was one of the inputs that shaped TES as it exists today. The need for structured baselines, traceable dosing and independent verification became clear during this work.
TES now incorporates IoT-enabled dosing (Thingy:91X), a cooling-water performance view and alignment with Eskom's Tutuka protocol — all designed to make future pilots more rigorous and their results more defensible.