The fuels program for the Nucla AFBC plant

The Nucla Station originally consisted of three 1959 vintage, 36 (3 x 12) MWe, stoker-fired boilers. The plant was built under the Rural Electrification Administration program to service the scenic, western slope of Colorado. In 1988, the stokers were replaced by a new, dual combustor, 110 MWe AFBC boiler in EPRI`s fluidized bed demonstration program. A new 74 MWe topping steam turbine/generator, with extraction to the existing turbines, was installed at that time. The Nucla Plant was a key project in EPRI`s program to demonstrate the commercialization of AFBC technology. This program has been the subject of numerous reports and papers on fluidized bed combustion. The fuel used by the Nucla Station was a relatively good quality, bituminous coal. Nucla`s coal was trucked more than 100 miles to the plant from a mine in Colorado. In addition, some high sulfur coal was test burned in the plant. This coal was trucked to the plant from a mine located near Kayenta, Arizona. The primary purpose of the demonstration program was to scale-up the size of the combustor and examine parameters that affect fluidization, heat transfer, erosion, and other boiler related issues. Sulfur capture and the ability to utilize lower grade fuelsmore » was previously demonstrated in other, smaller scale programs. To utilize project funds efficiently, the 1988 AFBC retrofit was dedicated to adding the 110 MWe combustor and related equipment. The plant was revamped specifically for test purposes. To conserve funds, silo storage of coal for the AFBC unit was limited to an 8-hour supply. Existing plant auxiliaries, that could adequately perform during the demonstration, were not upgraded. These included the coal handling system.« less