In refineries, chemical plants and power generation plants, essential process fluids are cooled by forcing air through a heat exchanger with a fan. These ACHE fans (Air-Cooled Heat Exchangers) use roller bearings to support the shaft that, due to the environment in which they operate, usually experience short lifetimes and frequent failures. These failures cause plant shutdowns with potential losses of up to 25% of refining capacity. In addition, replacement of these bearings requires that the fan unit be completely disassembled – a process that can exceed $20,000 per repair and take 2–3 days to complete. Greene, Tweed’s AFB assembly addresses this challenge, providing a turn-key solution that dramatically reduces maintenance requirements and replacement costs.
Developed with a patent-pending split design, Greene, Tweed’s AFB assembly consists of a WR®600 sleeve with MSE® seals and a locking ring contained in a one-piece metallic housing. The unique split design eliminates the need to disassemble the fan unit, reducing repair turnaround time from 2–3 days to less than 4 hours. Shaft seals prevent the ingress of dirt and moistures, and the non-contact bearing design minimizes wear for extended life. In addition, the non-galling WR600 sleeve enables dry run capability and will not damage the shaft in case of bearing failure. The result is an overall reduction in life cycle cost of the ACHE fan through less maintenance, easier repair, and avoidance of unplanned shutdowns.
Upper roller bearing replacement for ACHE fans found in refineries, chemical and gas processing plants, and power generation facilities.
The original contact bearing required three repairs within a 60-month period, totaling nearly $70,000 in costs. Greene, Tweed’s AFB assembly was repaired once during the same 60-month period, with costs remaining under $25,000. On a site with 400 units, upgrading the lowest performing 20% (80 units) improved life cycle cost by $3.4 million over 5 years.
*As of September 2013, all installations were performing as anticipated with enhanced rollout programs under discussion. Simulated second fit bearing installation and set-up time was confirmed at less than 1 hour.
The first AFB assembly was installed in June 2010. It had been running for 39 months as of September 2013 – twice as long as the previous MTBF. Subsequent installations have performed similarly.
Greene, Tweed provides all components of the AFB assembly together with the metallic housing. Three standard sizes, listed below, are available in stock with typical delivery in 1 week. Custom shaft sizes up to 3 in. (8 cm) can be accommodated, but may have a longer lead time. Please contact a Greene, Tweed representative for more information.