Emissions of Sulfuric, Hydrochloric, and Hydrofluoric Acids from Combination Boilers, 2002 Environmental Conference Proceedings

V. K. Varma and A. K. Jain

Four coal/bark boilers and two residual oil/bark boilers were tested for sulfuric acid (H2SO4), hydrochloric acid (HCl), and hydrofluoric acid (HF) emissions. H2SO4 emissions were found to depend on the bark to sulfur ratios in the fuel and on the stack oxygen, a surrogate for the oxygen level in the superheater and economizer sections. An emission model representing this two-fold dependence has been developed for use as a predictive tool. With a few exceptions, the H2SO4 emissions measured during this study were considerably lower than the AP-42 emission estimates for coal and residual oil firing. HCl and HF emissions decreased with increasing bark to chlorine and bark to fluorine ratios in the fuel, respectively. Non-linear regression models have been developed to illustrate these dependencies on fuel composition. The results obtained during this study highlight the benefits of co-firing. On the two boilers equipped with venturi scrubbers, sulfuric acid testing was carried out both at the inlet and outlet of the scrubbers. The efficiency of H2SO4 removal across the scrubbers ranged from 25.7 to 85.2% at these facilities.