Anthracite oxy-combustion characteristics in a 90 kWth fluidized bed reactor

Abstract A comprehensive experimental characterization of Spanish anthracite oxy-combustion has been conducted, and the results are discussed in this paper, encompassing combustion efficiency, heat transfer, and pollutant emissions. The experimental work has been carried out in a 90 kW th bubbling fluidized reactor under a variety of O 2 /CO 2 atmospheres and operating conditions (fluidization velocity, Ca:S ratio, and secondary oxidant supply). Combustion efficiency is improved under oxy-firing compared to air-firing, mainly due to the multiple-bubble regime and the lower fluidization velocities. The share of radiative heat transfer also rises, since O 2 /CO 2 operation leads to an increase of the temperature in the dense zone of the reactor. Concerning SO 2 emissions, the minimum values are found under the richest O 2 atmosphere, yielding maximum values of sulfur capture efficiency in the temperature range of 880–890 °C. A decrease of NO x emissions is also observed under oxy-firing conditions, while the benefit of secondary oxidant supply has to be optimized for every specific O 2 concentration.

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