ECONOMIC AND TECHINICAL CONSIDERATIONS FOR COMBINED-CYCLE PERFORMANCE-ENHANCEMENT OPTIONS

摘要

Over the past several years tumultuous, revolutionary and widespread changes have occurred within the U.S. power generation industry. The deregulation of the industry, coupled with declining reserve margins and climatic temperature extremes have resulted in new economic plant- operation considerations for owners of existing power plants and developers of new power plants. A sustained increase in summer peak period power demands and peak period duration combined with escalation of peak energy rates (*/kWh) have encouraged owners and operators of existing plants and developers of combined-cycle power plants to seek power-enhancing alternatives for optimizing plant performance and revenue streams. Various methods are available for improving the performance of combined-cycle power plants during initial plant design or as up-rate opportunities. Improvements can be made in plant output or efficiency beyond those achievable through higher steam temperatures, multiple steam pressure levels or reheat cycles. For example, it has become commonplace to install gas fuel heating on new combined-cycle power plants to improve plant efficiency. Additionally, cooling the air to the gas turbine inlet is sometimes considered for increasing gas turbine and combined- cycle output. A variety of options available for enhancing combined-cycle performance (primarily plant output) exist; this paper presents a technical description of each alternative, outlines the relative performance benefits of each enhancement alternative and discusses the potential economic valuation of the alternatives and combination of alternatives. There has been a large volume of GE, 7FA (PG7241FA) gas turbine sales and sales commitments. It is expected that many of these will be configured as STAG 207FA (two gas turbines and one steam turbine) combined-cycle plants. Thus, the economic assessment of performance- enhancement alternatives is presented in the form of a case study for a STAG 207FA configuration.