OIL, GAS & ENERGY
Chris Payne, Co-founder & Director, PureTec Separations, says the UK’s Combined Cycle Gas Turbine (CCGT) fleet faces a critical decade ahead, and a water treatment challenge operators can’t ignore
MONITORING AND DIAGNOSTICS A
round 70% of the UK’s Combined Cycle Gas Turbine (CCGT) fleet has exceeded its expected operational life. Most of these stations were built in the 1990s. They were designed for
baseload running. Today they operate in a flexible, start-stop regime, firing up when renewable output drops and sitting idle when it recovers. That cycling pattern puts serious stress on a plant. And one of the areas feeling it most is water treatment. A typical CCGT station uses between 30 and 80 cubic metres of treated water per hour across boiler feed, steam turbine and condensate systems. The quality of that water directly affects the life of HRSGs, condensers and turbine blades. The problem is that most of these stations
are still running decades-old ion exchange (IX) demineralisation systems. Parts are becoming obsolete. Service intervals are shortening. And the water quality these ageing systems produce is becoming harder to keep within specification. The result is a growing continuity risk, and increased reliance on expensive emergency mobile treatment when things go wrong.
Where process control comes in In a new plant, minor chemistry drift is tolerable. In a 25-year-old plant with thinner tube walls, degraded welds and worn oxide layers, the tolerance is far narrower. Corrosion, deposition and flow-accelerated corrosion (FAC) all become more aggressive as infrastructure ages. A condenser tube that might have lasted another decade under tight chemistry control can fail within months if water quality slips. Cycling operations make this worse.
Frequent starts and shutdowns break protective oxide layers, stir up settled iron oxides and introduce oxygen spikes. Poor water chemistry during these events accelerates damage across
26 PROCESS & CONTROL ENGINEERING | JUNE 2026 every vulnerable component.
The challenge for operators is that water chemistry issues rarely present immediate symptoms. Damage accumulates quietly over months or years, then surfaces as what looks like a mechanical failure. A single turbine refurbishment can cost upwards of £1 million. By the time the problem is visible, the cost is already locked in.
Smarter monitoring changes the equation This is where modern process control makes the biggest difference. Replacing ageing IX systems with reverse osmosis and continuous electrodeionisation (RO-CEDI) is the first step. These systems remove the need for regeneration chemicals, reduce the footprint and deliver more consistent output quality. But the real value comes from what sits on top of them. Normalisation and trending programmes track system performance against baseline parameters
over time, providing early warning of membrane fouling, resin degradation or feedwater quality changes. This allows operators to schedule clean-in-place (CIP) procedures at the right time, extending membrane lifespan and avoiding unplanned downtime.
Remote telemetry gives operators and service partners real-time visibility into conductivity, pH, dissolved oxygen and silica, the parameters that most directly affect HRSG and turbine health. When a parameter drifts, alerts trigger before the deviation causes damage. This is a significant step beyond periodic grab sampling, which can miss short-duration excursions entirely. AI-based interpretation takes this further. By analysing trends across multiple parameters simultaneously, AI can identify the early signatures of fouling or chemistry drift well before they would trigger a simple threshold alarm or be spotted during a routine check. Catching these events early, when a dosing adjustment or a scheduled CIP can resolve them, is far cheaper than responding after a system has failed.
The decade ahead The UK’s ageing CCGT fleet is not going anywhere soon. Gas-fired generation remains essential for grid stability, and many of these stations will run well beyond their original design life. For operators, the question is whether they continue relying on decades-old water treatment and periodic manual checks, or invest in modern treatment systems with continuous monitoring and AI-supported diagnostics that can keep pace with the demands of flexible operation. The technology exists. The cost of inaction is becoming harder to justify.
PureTec Separations
www.puretecseparations.com
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