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Show 45.0 >(c) - 40.0 CD () Ew 35.0 • Coal A c0 30.0 ~ -D--CoaIB ~ 25.0 c 0 0 20.0 • CoalC c mCD 15.0 ¢ Coal 0 -2 Z.. 10.0 aIL CoalE as .c 5.0 0 0.0 <1.0 1.0 >1.0 Stoichiometric Ratio Figure 7 Char Nitrogen Conversion Efficiencies as a Function of Stoichiometry 5. MODEL COMPARISONS WITH FIELD SCALE DATA JASPER has been configured to simulate the combustion environment of two full-scale units for this study. The first unit (Unit A) was originally rated at 160 MW and, for the test cases of interest, the average load was 170 MW firing a medium volatile Bituminous (mv8) coal. Five test cases for this unit were modeled, 2 baseline cases and 3 with overfire air. The second unit (Unit B) was rated at 180 MW firing a high volatile A Bituminous (hvAB) coal. Two baseline cases were modeled where the average load was 165 MW. Following baseline testing, the unit was then retrofitted to include an overfire air system and another set of data was taken. Two cases from the new firing system were modeled and for these cases the load was 180 MW. Between the two units, 9 simulations have been completed for a comparison with FOT, 0/0 carbon in the ash, and NO formation. As shown previously in Figure 1, three sets of inputs are required for JASPER, fuel information, DTFS-1 Experimental Information, and Boiler Information. The char activation energy and frequency factors are validated/calibrated in a JASPER simulation of that coal in the DTFS-1. In order to account for lower furnace slagging, a wall model has been included in JASPER which adds a variable wall resistance as a function of furnace height. This value must be calibrated for a single test case by matching the furnace outlet temperature. For subsequent tests the code can be used in a predictive mode. Wall resistances and the corresponding heat flux profile for Unit A remained constant between the baseline tests and the OFA tests. This is because Unit A had the ability to operate in a baseline configuration and then in an OFA with out any hardware changes. Unit 8, on the other hand, had two different wall resistance and heat flux profiles between the pre-retrofit and post-retrofit tests. This is 14 |