Rolling Wind Screens help reduce mechanical fan stress

The Challenge

Caithness Long Island LLC commenced commercial operation of its 350 MW natural gas fired power generating facility (Caithness Long Island Energy Center) on August 1, 2009. It was the first major baseload power plant to be built on Long Island in over thirty years and has employed over 400 local workers. The plant uses 34% less fuel than older base load plants.

Long Island experiences strong windy conditions and storms often coming in from the Atlantic Ocean. During these conditions the Energy Center experienced both thermal performance challenges as well as mechanical issues such as fan blade cracks and U-bolt failures. The mitigation of high wind effects on ACCs is rarely addressed in the initial design stage and so any protection solutions considered would have to cope with high wind speeds and be retracted during hurricane season.

The Solution

After a thorough consultation period, with the co-operation of Gary Mirsky (independent consultant), Galebreaker Industrial Services, Pat Sullivan (Siemens) and the Caithness team, motorized perimeter windscreens were installed at the Caithness site capable of being automatically retracted in the event of hurricane force winds. Structural verification services were carried out to ensure the ACC structure would cope with additional wind loads of up to 120mph. Over 880sqm of motorized screens covered all 13 bays – the west side being the largest at 82m long and 5m high.

The Benefits

There have been no fan blade or hardware failures since installation of the screens in 2012. The Galebreaker wind screens created more airflow into the windward side perimeter fans, ultimately improving the performance of the ACC and the power plant as well. They also reduced the variability of static pressure inside the fan module. This reduction can be significant for reducing the stress and vibrations created as the fan blades rotate inside the fan cylinder.

Reducing the stress and vibration has increased the life of the mechanical equipment and also reduced maintenance costs. John Maultbetsch, Howden Fans, the California Energy Commission and Caithness Energy Center agreed to tests and studies at the power plant for 18 months and these were presented at the ACCUG in 2015. You can view these reports in our technical case study area on the website. Click here.