| Combined cycle
reduced visibility into the chemistry of an increasingly vulnerable system. Older plants need more chemistry control at a time when they typically have less.
Figure 2. A PureTec SCADA interface showing real-time monitoring of a water treatment system. Similar control and telemetry architecture is applied to CCGT water treatment installations, providing operators with live visibility into system status, capacity and alarm conditions
expansion and contraction damage, stir up settled iron oxides and introduce air ingress that causes oxygen spikes. Poor water chemistry during cycling magnifies every one of these effects. The result is faster degradation in plant that is already more vulnerable than it was at commissioning.
The problem with invisible damage Water chemistry issues rarely present immediate symptoms. Instead, they slowly damage the most expensive assets on site, HRSG tube bundles, condensers and turbine blades, through steam purity degradation. Failures often appear to be mechanical events,
but the root cause is usually years of quiet chemistry drift.
The numbers concentrate the mind. A single turbine refurbishment can cost upwards of £1 million. A full resin replacement on a large IX system, where vessels hold 30 to 40 tonnes of media, can run to £200 000 to £300 000. These are costs that proper water chemistry management can defer or avoid entirely. The difficulty is compounded by a trend across ageing plant fleets: as stations age, budgets are cut and experienced water chemistry specialists retire or move on. Instrumentation such as conductivity meters, pH meters and dissolved oxygen sensors degrades or is taken offline. The result is
From legacy IX to RO-CEDI For operators looking to address ageing water treatment infrastructure, the technology path is well established. Replacing IX demineralisation with reverse osmosis and continuous electrodeionisation (RO-CEDI) removes the need for regeneration chemicals on site, reduces the physical footprint and simplifies the treatment process. See Figure 1. RO-CEDI systems are easier to maintain and deliver more consistent water quality than IX plant operating beyond its design life. For stations running flexible duty cycles, that consistency matters. It means tighter control of conductivity, silica and sodium, the three parameters that most directly affect turbine and HRSG health.
Containerised treatment units also offer a practical route for stations that cannot afford extended downtime during an upgrade. A pre-commissioned containerised unit can be connected alongside the existing system, allowing the switchover to happen with minimal interruption to generation.
Monitoring and early intervention New treatment hardware is only part of the answer. Equally important is what happens after installation.
Normalisation and trending programmes track system performance against baseline parameters over time. This data provides early warning of membrane fouling, resin degradation or changes in feedwater quality, allowing operators to schedule clean-in-place (CIP) procedures at the right time rather than
Figure 3. Example of a remote monitoring dashboard showing real-time water quality parameters including conductivity, pH and dissolved oxygen. Telemetry-based monitoring enables faster response to chemistry deviations than periodic sampling
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