Life extension of coal-fired power plants (Ambrosini, 12-2005)

Large coal-fired power generating units built in the 1960s and 1970s were designed for a nominal 25-year life. Units exceeding 25 years´ operational service today account for more than 45% of worldwide coal-fired power generating capacity. It is often standard procedure to extend the life of a power plant to 40 years, with some cases of units exceeding 50 years of operation. There has been much progress in recent years in plant life extension: by refurbishing boiler parts, upgrading the turbines, and adding flue gas cleaning to meet new emission regulations. Life extension is often possible due to the conservative nature of the original plant design and the fact that only a relatively small number of the components are life limited.

This report examines life extension options. It begins with a survey of the age of coal-fired plant around the world. The main focus of the report is on near-term life extension alternatives, with specific attention given to material issues, degradation mechanisms, condition assessments, and remaining life assessments. Condition assessments and remaining life assessments are prerequisites to a comprehensive plant modernisation leading to improved operating efficiencies. Longer-term life extension alternatives are then described. Case studies of older plant which can, or have been, modified in order to increase their efficiency compared to the original design are presented. Plant life extension projects that have been completed in different countries are outlined. Incentives and barriers to plant upgrade are then discussed. Case studies are presented of radical conversion to coal-fired generation.