Application of Staged Combustion and Reburning to the Co-Firing of Nitrogen-Containing Wastes

Abstract

ABSTRACT

A 0.6 MW (2,000,000 Btu/hr) precombustion chamber burner, designed for infurnace nitrogen oxide (NO_x) control, high combustion efficiency, and retrofit applications was evaluated for use with high nitrogen content fuel/waste mixtures. The 250- to 750-ms residence time precombustion chamber burner mounted on a prototype watertube package boiler simulator used air staging and in-furnace natural gas reburning to control NO_x emissions. Previous work (13) has reported on tests in which natural gas doped with ammonia (NH₃) and No. 2 distillate fuel oil doped with pyridine (C₅H₅N) were used to simulate high nitrogen content fuel/waste mixtures. The present study reports on research in which the low NO_x precombustor was used to examine the co-firing characteristics of a nitrogen-containing pesticide, containing dinoseb (2-sec-butyl-4,6 dinitrophenol) in a fuel-oil/xylene solvent. The dinoseb formulation as fired contained 6.4% nitrogen. NO_x emissions without in-furnace control exceeded 4400 ppm (corrected to 0% O₂). When NO_x controls in the form of air staging and natural gas reburning were employed, these emissions were reduced to below 150 ppm (96% reduction). Average CO and total hydrocarbon (THC) emissions were typically less than 15 and 2 ppm, respectively. Dinoseb was not detected in any emission sample, and the destruction efficiency (DE) was determined to be greater than 99.99%. Mutagenicity studies of the dinoseb emissions showed that the mutagenic emission factors measured with either air staging or air staging and reburning were similar to those measured for the burning of fuel oil for residential heating (22, 28).