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Show ( psig as opposed to the Turbotak nozzle which could only be operated up to 70 psig. COAL ANALYSIS Coal samples were analyzed to determine ultimate and proximate analysis, heating value and particle size distribution. For the ultimate analysis carbon and hydrogen was determined by the method described in Reference 5. Sulphur was done by the Leco Induction method and nitrogen by the Kjeldahl method as _ outlined in ASTM D3179. Oxygen was calculated by difference as the last remaining constituent. Proximate analysis was performed according to ASTM method D3173-D3175 and the calorific value by ASTM method D3286, using an adiabatic bomb calorimeter. Particle size distribution was determined by sieve analysis according to ASTM method D-197. Analysis of the two coal samples used; a 1.7% S US bituminous coal and a 2.8% S Nova Scotia coal is shown in Table 1. PROCEDURES After steady state was achieved with the baseline coal, additive injection into the middle of the furnace at specified locations (II to I,) was initiated. Temperature-time and radial profiles of flue gases under conditions simulating Lakeview and Lambton TGS thermal profiles are shown in Figure 6. Data collected during each test include system temperatures, and pressures, additive - feed rates and stoichiometry, flue gas constituents concentrations (C02, 02, CO, S02 and NOx) and in-situ ash resistivities. Coal and fly ash samples were collected during the tests, and analyzed for chemical composition and particle size distribution. A high volatile, medium sulphur eastern US coal from Lakeview TGS and a high sulphur coal from Nova Scotia were used in the study. The proximate and ultimate analyses and particle size distribution of the coals are given in Table 1. The additives used include: a 13.5 to 50% aqueous solutions of urea, a 5.6% ammonia solution and a 16.1% ammonium carbonate solution. RESULTS AND DISCUSSION The effect of the most important parameters that were found to affect NOx reduction by in-furnace additive injection have been studied. These include: • Nozzle characteristics (particle size distribution, momentum etc.); • Temperature at the point of injection; • Additive stoichiometry; • Additive concentration; and • NOx level in flue gas. |
