Cooling systems |
Reducing wind impact on ACC performance
With the increasing popularity of dry cooling systems, air cooled condensers (ACCs) are becoming key to power plant efficiency, yet these systems are notoriously sensitive to environmental factors like wind, leading to power generation losses and increased operational costs. As energy security and climate change take centre stage, fabric-engineered windscreens are helping power plants maintain efficiency
Left, perimeter windscreen at Ferrybridge 1. Right, cruciform windscreen at Fadhili combined heat and power plant
Air-cooled condensers (ACCs) use ambient air to condense turbine exhaust steam, eliminating the need for water cooling.
The systems use a series of large motor- driven fans to force air over finned tubes, cooling the steam and converting it into condensate, which is returned to the boiler. Removing water from the equation allows for more flexibility in locating plants and addresses concerns around using water as a resource – which can be costly to treat.
However, the challenges facing this cooling method are many and varied, according to Gary Dicker, UK, European, and Middle Eastern cooling specialist at Galebreaker.
“When wind disrupts ACC operations, it can cause significant mechanical and thermal inefficiencies.”
“One of the main issues we see is wind shear, which destabilises the airflow and causes imbalances across the fan cells. This results in mechanical stress, particularly on fan blades,
which can lead to increased vibration and eventual component failure. Additionally, poor airflow reduces the cooling efficiency and can be a cause of hot air recirculation,” he says. For plant managers, this drop in performance often leads to de-rating, meaning the plant operates below its designed capacity, directly impacting power output and creating lost revenue. In some cases, the financial cost of reduced ACC performance can be severe, with plants forced to burn more fuel to compensate for lost power generation, or even temporarily shut down to protect equipment, creating further losses or incurring financial penalties.
Why windscreens?
“Wind is an air thief, stealing air away from where the condenser needs it most,” says Gary. “By moderating the wind’s speed and redirecting its flow, windscreens counter this effect, stabilising airflow and ensuring the condenser can access the air it needs for optimal performance. “The screens act as a barrier, slowing down crosswinds and stabilising air underneath the fan, allowing the ACC to use the air more effectively for cooling, while also reducing mechanical vibration.”
Impact of crosswinds on an ACC. Crosswinds have a detrimental impact on the performance of ACCs. As air collides with the wind wall it accelerates underneath the fans, causing wind shear, changes in fan static pressure, and dynamic fan blade loading. Increases of windspeed by just 5m/s can equate to a 30% reduction in airflow
28 | October 2024|
www.modernpowersystems.com
“The focus is to provide stability and consistent operation. The windscreen’s main objective is to protect performance by mitigating wind issues; not necessarily to increase output beyond original design levels,” he explains.
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