The first direct air-cooled electric generating plant in North America—the 21.7-MW (gross) coal-fired Unit 1 at Neil Simpson Power Plant in Gillette, Wyo—began commercial operation in 1969. Use of air cooling for powerplants grew slowly until the late 1990s, when emissions-control and water-use regulations, and favorable gas prices, strongly influenced the selection of more-efficient combined cycles over coal-fired plants for electric power generation—particularly in the West, where the population was growing rapidly.

Many combined cycles installed during the 200,000-MW bubble (2000-2004) are equipped with air-cooled condensers (ACCs). Early experience with these units revealed shortcomings in design, operating strategies, etc, and especially in the control of water/steam chemistry vital to reliable plant operation.

The result of less than optimal chemistry included flow-accelerated corrosion (FAC) and carryover of corrosion products into the condensate/feedwater circuit. The latter caused problems in some steam generators and required cycle design modifications to remove corrosion products. In severe FAC cases, leaks developed in the tubes, resulting in high air inleakage and consequent operating difficulties.

Owner/operators of ACC-equipped plants quickly recognized the importance of sharing technical information to solve recurring problems in a timely manner. Andy Howell, senior systems chemist, Xcel Energy, began developing an informal list of “interested parties” in 2006 and organized the Air-Cooled Condenser Interest Group in 2007 as an unofficial subcommittee of the ASME Power Plant and Environmental Chemistry (PPEC) Research Committee.

The first technical discussion on ACCs was held at the PPEC meeting in spring 2007 at an end-of-day gathering. Such informal discussions were held at the next several PPEC meetings, focusing on steam-cycle chemistry and corrosion at a high level.

Early in 2009, NV Energy and the editors of the COMBINED CYCLE Journal collaborated on the formation of an ACC Users Group with the goal of expanding the information exchange to problematic mechanical components, field modifications to correct performance deficiencies, control algorithms to reduce power consumption, etc. Another goal was to drive industry knowledge on ACC water chemistry and best practices down to the plant O&M staffs with responsibility for the performance and reliability of this equipment.

The first meeting of the ACC Users Group was held Nov 12-13, 2009 at NV Energy’s headquarters building, attracting about 40 attendees. The presentations from that meeting are accessible by owner/operators of generating plants via the “Presentations” button at the left.

NV Energy’s interest in supporting the development of an ACC Users Group is simple: The company has, perhaps, more dry-cooling cells (283) than any other utility in the country at its six ACC-equipped combined cycles. These are the Chuck Lenzie (two 2 x 1 F-class power blocks), Silverhawk, Walter M Higgins, Frank A Tracy, and Harry Allen Generating Stations and the Goodsprings Energy Recovery Station (organic Rankine cycle).

The second meeting of the ACC Users Group was hosted by Xcel Energy at its Comanche Generating Station, Sept 28-29, 2010. The Comanche location afforded the nearly 70 attendees the opportunity to see first-hand the station’s newly constructed 750-MW coal-fired supercritical unit with both water- and air-cooled condensers arranged in parallel.

Shortly after the meeting at Comanche, several attendees agreed to formalize the group under a steering committee chaired by Howell (click Leadership button at left) and to develop this website to share information on a continuing basis (click the “Forums” button to participate).

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