Hirotsugu Kodama

Recent Upgrading and Life Extension Technologies for Existing Steam Turbines

Electricity generation utilities are increasingly looking for cost-effective solutions to maximise the value of aging steam turbine generator plant assets. To this end, retrofits of steam turbines after many years of operation have been carried out for the purpose of life extension of units, performance improvements, capacity up-rating, availability improvement, and improved environmental compliance. Major steam turbine manufacturers have continued to push forward the development of advanced technologies to satisfy demand from utilities by provided retrofit design that optimise the above criteria. This paper describes the advanced technologies adopted in the recent retrofits, including advanced steam path design and new last stage blades of improved efficiency, improved reliability, and of simplified or no maintenance. Retrofit case-studies of capacity up-rating and life extension are introduced to illustrate how these technologies have been applied and what has been the gain.Copyright

Steam Turbine Retrofits Technology for Improved Performance and Reliability

Improved efficiency has been one of the most significant aspects of the development and application of steam turbines, along with the improvement of reliability and gains in terms of both reduced maintenance and extended operation. There is now extra emphasis on evolving increased efficiency, due to the pressure to reduce carbon dioxide emissions with environmental problems in mind. Therefore, several approaches have been made to upgrade the internal turbine efficiency with the advanced steam path stage, by reducing the exhaust loss with long last stage blades, by improving the steam turbine cycle efficiency such as in terms of ultra super-critical pressure and double reheat cycle and by applying an advanced combined cycle with high firing temperature gas turbines.