Integration of Advanced Gas Turbine and Combined Cycle Technologies for High Efficiency with Operational Flexibility

While efficiency is still the major driver in combined cycle power plant design, there is an increasing need for operational flexibility along with additional operating cost reduction. nightly and weekend shutdowns and subsequent start-up capabilities should be considered during the overall evaluation of a power plant. Technological advancements in power plant design involving gas and steam turbines, heat recovery steam generators (HRSGs), generators and comprehensive plant component integration have increased thermal performance and allowed greater operational flexibility. Advancements in gas turbine technology have increased power and efficiency while decreasing emissions and life-cycle costs without sacrificing reliability. Siemens advanced gas turbines are equipped with 3-D aero blading, high temperature tolerant coatings, advanced cooling technology and low emissions combustion systems. These features have been incorporated into a well-proven technology base that includes many gas turbine design features that have been adopted as industry standards. Despite advances in gas turbine power and efficiency, when used in combined cycle application, plants were traditionally forced to choose between high efficiency or operational flexibility (at the expense of efficiency). Although it has always been important to provide operational flexibility in order to enhance the value and agility of power generation assets, it has not been economical. Gas turbines have traditionally been required to compromise their fast-loading capability to accommodate the limitation of the HRSG, steam turbine and other components. By properly designing and integrating the plant components to allow a fast start capability while dramatically reducing startup fuel and water consumption as well as emissions, an economical solution is now available. Plants capable of achieving traditional base-load combined-cycle efficiency, incorporating fast starting and cycling capability now allow owners to meet a variety of challenging and sometimes changing market demands. This paper addresses results of a comprehensive integrated program within the authors’ company to develop the FlexPlant a combined-cycle plant design that offers fast starting and cycling flexibility without jeopardizing efficiency or reliability. The FlexPlant design integrates proven plant concepts with highly efficient components and advanced technology to exceed the capabilities of existing combined cycle plant designs.