An Overall Approach for Improving Plant Life and Performance of Aging Fossil-Fired Boilers and Steam Turbines

摘要

Reliability, efficiency and performance of fossil-fired boilers and steam turbines suffer with age due to deterioration of major boiler and turbine components within the steam path. Mineral deposits, foreign object damage, solid particle erosion and general wear and tear of steam path components, including steam tubing, continually reduce the overall performance of fossil-fired power plants and result in an increase in NO_x and CO emissions. As the power plant passes 20 years of age, boiler and steam turbine problems occur more and more frequently on major components, making them ideal candidates for rehabilitation and modernization. Advanced design and analysis tools, such as CFD and FEA, in combination with advanced material technology, present the real possibility of greatly improving power plant reliability, efficiency, and performance. In addition, improvements in firing systems also create the potential to greatly reduce emissions of pollutants and greenhouse gasses. Incorporating the latest design features into aging fossil-fired boilers and steam turbines aimed at obtaining greatly improved results both in terms of reliability and efficiency is a much preferred choice over simply replacing failed or worn original components. This paper reviews performance improvement technologies and reliability considerations, and describes the advanced technology features that can be considered for 20 year old fossil- fired boilers and steam turbines with the purpose of increasing power plant life and overall performance. Adopting an advanced steam path design in the HIP section and the recently developed last stage bucket designs increases maximum obtainable efficiency. This paper also focuses on recent developments and utilization of advanced coal firing technologies to reduce emissions. These advanced technologies will be discussed in an overall assessment approach to cover costs as well as political and social issues.