By Neal R. Hood, Maintenance Specialist and Kristi Simmons, Air and Gas Engineer, Alabama Power Company
Plant engineers at Alabama Power decided to upgrade damper drives for each of two coal-fired units at the James H. Miller, Jr. Electric Generating Plant. The two units, similar in design and having 25 years or more of service, each have a 720 megawatt capacity. High maintenance levels for the original Bailey drives, along with a growing scarcity of parts, provided the economic justification for replacing 45 damper drives for each boiler.
After a comprehensive engineering study, the plant chose Intelligent Contrac electric rotary actuators from ABB Instrumentation to replace the Bailiey drives (Bailey was acquired by ABB in 1999.). The replacement drives have smaller footprints and are relatively simple to retrofit. Replacements went smoothly during planned successive month-long outages of the two units.