A combustion turbine combined cycle that uses coal-derived dirty fuels can be economical if the fuel is processed at the plant site and cost of electricity (COE) is used as the criterion for configuring the power system and selecting its components. In a DOE/METC-sponsored study, 12 combinations of power components and conditioning components were evaluated for each of two fuels: a gas made from coal and a coal/water slurry. One baseline system was selected from each group of 12 systems, based on its potential to achieve a low COE. Each baseline system was then parametrically evaluated to show the effects of specific components on the COE of the power plant. In one of these studies, on-site coal conversion was shown as the key to reducing the COE and the operating cost of the plant, thus improving the chances of the plant being used for baseload operation. Power TrainsClean-Up Systems

The development of pressurized fluidized bed combustors (PFB) as an efficient, economical, and enviromentally acceptable means of utilizing the nation’s coal reserves has been underway for a short time. Although at least a dozen PFB facilities are in existence or under construction, and other PFB plants (1) are being designed, the technology is not fully developed. This paper presents the results of an investigation into achieving high efficiency with a PFB system. The base case was a novel cycle, with the PFB combustor is located at an intermediate pressure between the maximum cycle pressure and atmospheric pressure. This configuration eliminates many of the technical problems associated with conventional PFB systems, and has a higher heating value net efficiency of 38 percent. Gas reheat, topping combustion, carbonizer systems, and compressor intercooling are added to the base system to yield a cycle efficiency of 45 percent.

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This paper describes the operating experience with the Westinghouse PACE 260 Combined Cycle Power Plant at Public Service Company of Oklahoma’s COMANCHE Station. This plant was the first PACE 260 unit to go into operation and had many new design features in the major components. The paper deals mainly with the problems that occurred and their solutions.

In the traditional pressurized fluid bed (PFB) power system, the PFB is located in the highest pressure portion of the power cycle, Figure 1. This results in the smallest volume flow through the PFB, but also requires the combustion products to flow through the entire expansion train. This is not expected to be a major problem when the PFB temperature is limited to 1600°F for effective sulfur capture and to avoid alkali vapors in the products of combustion. However, when topping combustion is added ahead of the turbine so as to reach state-of-the-art turbine inlet temperatures, a major risk for turbine corrosion and fouling develops.