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Show ADDITIVE INJECTION FOR NOy CONTROL by: R. Mangal, M. Mozes, R. Gaikwad , R. Thampi and D. MacDonald Ontario Hydro Research Division 800 Kipling Avenue Toronto, Ontario M8Z 5S4 Canada ABSTRACT Paper #2 Injecting aqueous solutions of nitrogen-based additives into the furnace for reducing NOx emissions from coal -fired utility boilers has been studied at Ontario Hydro's 640 MJjh Combustion Research Facility under conditions simulating full scale operation. Three additives were tested: urea, ammonia and ammonium carbonate. NOx reduction was found to be a function of inj ection temperature and ~ode of injection, additive stoichiometry, additive concentration and initial NOx concentration. Under optimized operating conditions while burning a 1.7% S eastern US bituminous coal and injecting urea cocurrently with the flue gas at a temperature of 1100°C, up to 90% NOx reduction can be achieved at an additive/NOx stoichiometry of 1.7. Under similar operating conditions, 84% removal was achieved with ammonia and 80% with ammonium carbonate. Ash resistivities and the performance of the electrostatic precipitator are not affected by in-furnace injection of these sorbents. INTRODUCTION In Ontario, the Government announced stricter acid gas limits for Ontario industries and Ontario Hydro has to reduce its acid gas emissions from the present level of 430,000 tonnes/year to 215,000 tonnes per year starting in 1994. Although the regulation limits the amount of sulphur dioxide (S02) emissions, nitrogen oxides (NOx) emissions are not regulated as long as the aggregate emissions of the two (S02 and NOx) do not exceed 215,000 tonnes/year and no more than 175,000 tonnes is S02/1/. The United Nations Economic Commission for Europe (ECE) , of which Canada is a member is negotiating an international agreement to control emission of NOx into the atmosphere/l/. The protocol will likely limit NOx emissions at the 1987 level, and future reductions may be necessary after 1994. In accordance with this protocol Ontario Hydro is investigating ways to accomplish the required reductions. Hydro has installed NOx abatement technology in the form of low NOx burners (LNB) at Nanticoke/l/. Hydro is also reviewing other NOx control techniques such as selective catalytic reduction (SCR) and noncatalytic reduction (in-furnace additive injection). |