(398c) Ash Emittance Characterization
AIChE Annual Meeting
Wednesday, November 10, 2010 - 9:20am to 9:45am
When fuels are burned in boilers ash starts to build up on the interior walls of the boiler. This ash build-up decreases the amount of heat transferred from the fuel, through the boiler walls, and ultimately to the water side of the boiler, thereby decreasing the amount of steam generated by the boiler. The effect of this ash build up on the inside walls of the boiler decreases the efficiency of the boiler it also effects the size and design of new boilers when accounted for properly. The aim of this research is to characterize different ash deposits from a variety of fuel sources by using an FT-IR spectrometer to measure the absorbance of each sample. Applying Kirchoff's Law, we assume that the absorbance is equal to the emittance, and are able to measure the total emittance of each ash sample. Once the emittance of each sample is known, the effect that each sample has on heat transfer can be calculated. A few examples of the fuel samples that have been tested are Pebble River Basin Coal, Class C Bituminous Coal, Class F Sub-bituminous Coal, wood, and several other biofuels. These ash samples have been gathered from various power-plants that use each of these fuels. Each ash sample is mixed with KBr (potassium bromide) powder to make a 2.5 wt% mixture of ash sample inside KBr. This mixture is then pressed into a thin circular wafer, 1.5cm in diameter and about 1mm thick. These wafers are placed in the FT-IR and tested against a KBr background to measure percent absorbance. Emittance is then calculated from the FT-IR data. Presently, our results have agreed with our predictions. Testing will be continued to strengthen the validity of the model.
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