Washington to provide EPC for Wisconsin plant

Abstract

A combined cycle consists of combining two power cycles in series to obtain a high overall thermal efficiency, significantly higher than the individual efficiencies of the two cycles making up the combined cycle. In the combined cycle discussed in this chapter, a Brayton cycle or gas turbine is utilized for the topping cycle and a steam Rankine cycle for the bottoming cycle. Combined cycles come in a variety of sizes, depending on the size and number of gas turbines utilized, and may range from less than 10 MW to in excess of 500 MW while using a single gas turbine. In addition to having high thermal efficiencies, outstanding environmental performance, easy start-up and shut-down and low cooling water requirements, combined cycles have significantly lower staffing, capital cost and construction time requirements when compared to boiler based power plants. On the other hand, the clean fuels required by a combined cycle are significantly more expensive when compared to fuels such as coal and biomass that can be directly combusted in a boiler. Included in this chapter are a discussion of types of gas turbines for combined-cycle applications, types of steam cycles in combined-cycle plant, plant design and technology, fuel specifications, control technologies for criteria pollutants as well as for CO2 emissions, and limitations of gas-fired combined-cycle plants. Future trends for improvements in performance and emissions are also discussed.