Combined Cycles—Alternative for Process Steam Systems

The state-of-the-art combined cycle system consisting of combustion turbines, heat recovery steam generators, and steam turbine-generator units, offers a high-efficiency method for the production of electrical and heat energy at relatively low installed and operating costs. Regional fuel usage projections for major petrochemical areas of the country indicate a substantial continued usage of lighter fuels for the next 15 to 20 yr by electric utilities and industrials. Only the highest efficiency utilization of these premium fuels should be considered, and this paper discusses systems for this higher utilization. Typical plant systems are compared to more efficient systems, the relative economic incentives are considered, applications for specific requirements representative of industry practice are developed, and alternative fuel considerations for combined cycle systems are included.