Combined cycle |
too late. Getting CIP timing right extends membrane lifespan considerably. Remote monitoring through telemetry gives operators and their service partners real-time visibility into plant chemistry. See Figures 2 and 3. When a parameter drifts, alerts can trigger before the deviation causes damage. This is a significant step beyond the traditional model of periodic grab sampling and laboratory analysis, which can miss short-duration excursions entirely.
AI is now being applied to this data. By analysing trends across multiple parameters simultaneously, AI-based interpretation can identify the early signatures of fouling, scaling or chemistry drift well before they become visible to operators or trigger a simple threshold alarm. Catching these events early, when a CIP or a dosing adjustment can resolve
them, is far more cost-effective than waiting for a system to fail or for an operator to notice a gradual change during a routine check. For stations where the original
instrumentation has degraded or been taken offline, the installation of modern monitoring alongside a treatment upgrade restores the visibility that ageing plant needs.
Where the industry goes from here
The UK’s ageing CCGT fleet is not disappearing any time soon. Gas-fired generation remains essential for grid stability, and many of these stations will be called on to run for years beyond their original design horizon. That makes water chemistry a strategic priority rather than a routine maintenance line item. Operators who invest in modern
treatment systems, continuous monitoring and proactive service programmes will see longer asset life, fewer forced outages, lower maintenance costs and more reliable startups. Those who continue running decades- old water treatment on ageing plant are accepting a growing risk of equipment failure and unplanned reliance on expensive emergency mobile treatment. That is the kind of reactive spending that proper investment would have prevented.
The technology to manage this transition exists today. The question for operators is whether they act before the next forced outage makes the decision for them.
Mike Roberts, Process and Systems Specialist at PureTec Separations, provided technical input for this article.
European HRSG forum: the view from Prato
The twelfth annual IAPWS European HRSG Forum, held in Prato, Italy, 19–21 May 2026, helped to address the urgent need for international information exchange on heat recovery steam generator operating experience, degradation mechanisms, cycle chemistry, problems and solutions
EHF2026 was chaired by Barry Dooley of Structural Integrity, UK and Bob Anderson of Competitive Power Resources, USA. It attracted 105 participants from 22 countries and included 38 users. Developed and supported by IAPWS (International Association for the Properties of Water and Steam), it is held in association with the Australasian Boiler and HRSG Users Group (ABHUG). The EHF2026 event was organised by Mecca Concepts, Australia and had 15 sponsors: Precision Iceblast Corporation; Bang & Clean; Tuff Tube Transition; Dekomte; Fuel Tech Srl; Metroscope; New Componit Srl; Testex; Emerson/Flexim; Ionix Technologies; Freudenberg Flow Technologies; Cormetech; Kurita; Arnold Group; and NEM. There were 20 presentations, including a workshop on attemperators. The meeting provided a forum for the presentation of new information and technology related to HRSGs, case studies of plant experiences and solutions, and for open discussion among plant users, equipment suppliers, and industry consultants. The mix of topics (materials, cycle chemistry, operation, valves, tube failures and assessment techniques, inspection and remaining life aspects, and HRSG gas-side cleaning) kept the attendees interested, alert and participating. The forum again provided a unique opportunity for plant users to discuss questions relating to all aspects of HRSG operation with the industry’s international
experts. These discussions underlined once more the urgent need for the international exchange of information, which is excellently provided by this IAPWS forum.
Highlights from EHF2026 ● Updates from around the world were
provided on HRSG cycle chemistry and thermal transients, indicating why the main mechanisms of HRSG failure and damage continue to occur: - The latest chemistry influenced reliability statistics collected over 20+ years from over 400 HRSGs worldwide, referred to as Repeat Cycle Chemistry Situations (RCCS), indicate that 85% of plants have ineffective corrosion products monitoring programmes, 77% have reduced cycle chemistry instrumentation when compared to IAPWS guidance, 80% don’t monitor drum carryover and about 74% are not challenging the status quo. During 2026 IAPWS is planning to incorporate this information into a benchmarking process so plants can assess their cycle chemistry and flow- accelerated corrosion (FAC) programmes and compare themselves with other plants worldwide.
- The latest thermal transient influenced reliability statistics, collected since 2009, continue to show only moderate overall improvement, with most
24 | July/August 2026 |
www.modernpowersystems.com
problems continuing to be associated with attemperators and drains. This international database indicates that only 21% of plants routinely inspect attemperator hardware, 86% experience leaking attemperator spray water, of which 93% use block valve/ control valve sequencing logic that encourages leaking, 39% experience attemperator overspray conditions in the superheater and 17% in the reheater, 29% allow operators to manually control attemperators, and 35%/41% effectively drain the HPSH/RH during startup.
● The expected growing demand in Europe for NOx reduction for new and existing power plants was considered, indicating that selective catalytic reduction (SCR) systems are available, but detailed investigations will be required into how these SCR solutions can be integrated into new and existing HRSG designs. The anticipated changes (increases) in plant operating and maintenance costs were explored based on experience in countries like the USA, which has mandated the use of SCR for many years. Also presented were state-of-the art designs for SCR catalysts.
● Effective attemperator implementation for steam temperature control remains one of the key elements in HRSG design. Improper operation/maintenance or
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75
