| Cooling systems
“They’re composed of a mesh fabric, making them lightweight but durable. The best engineered solutions can last upwards of 20 years, as we’ve seen with the screens at Coryton power station in the UK. Typical payback periods for the screens range between four to 12 months.”
Perimeter (top) and cruciform windscreen arrangement (below). Top-mounted perimeter screens mitigate windshear to protect ACC fans, while cruciform screens – in a cross formation, beneath the fans – stabilise airflow, reducing the risk of recirculation. Screens attach to the ACC steel support frames via ratchets and hooks
The role of CFD modelling Computational fluid dynamics (CFD) modelling is at the heart of windscreen placement optimisation, providing an evidence-based approach to enhancing ACC performance. By virtually recreating a plant’s layout, CFD analysis allows engineers to test how wind flows around the surfaces and structures of a plant, determining how it will impact ACC efficiency. “CFD has been transformative,” Gary says. “It helps us identify where windscreens should be placed to stabilise airflow around the fans, to maintain efficiency and protect mechanical components.”
Through this modelling, Galebreaker has learned that a dual windscreen approach — incorporating both perimeter and cruciform screens — delivers the best results. “Initially, the focus was on top-mounted screens to mitigate wind shear. However, it became clear that while these screens reduced mechanical vibrations, they had a lower impact on increasing thermal performance than the cruciform screens, which sit in a cross-formation beneath the fans to ensure better airflow, reducing the risk of recirculation and interference.”
The processing of CFD results using this ‘digital twin’ approach allows a detailed analysis of how plant managers can expect windscreens to impact performance. “By applying typical wind conditions to the model, we can calculate the effect on steam back pressure and megawatt output. Translating these performance gains into financial projections enables us to calculate the payback period for plant managers, helping them justify the investment.”
Insights from the ACC Users Group conference
ACC fan blade damage. Extreme crosswinds can lead to fan trips and fan blade damage. A single fan replacement could cost over £40k and take up to four weeks to install
One of the key advantages of windscreens is their adaptability and cost-effectiveness as a retrofit solution. “Wind issue mitigation is not always considered during the design phase,” says Gary. “Add to that the fact that many power plants face spatial or planning restrictions that dictate where they are located. Operational budgets may further limit design modifications after construction.”
“We can’t control the ambient temperature or wind speed, but we can influence how wind interacts with the plant’s components. Windscreens offer a flexible, non-intrusive solution - often installed using simple ratchet and strap fastenings, attached to existing infrastructure. This makes them a cost-effective alternative to structural changes,” says Gary.
The Air-Cooled Condenser Users Group – the only professional member network dedicated to resolving issues with air-cooled condensers, held their annual conference for the first time in the UK
Ferrybridge 1 (foreground) and adjacent sister site, Ferrybridge 2 (photo: enfinium)
www.modernpowersystems.com | October 2024 | 29
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