Sulfuric acid emissions from combination boilers.

APPLICATION: This paper provides a better tool for estimating sulfuric acid emissions from sources such as combination boilers burning wood residues, or when the widely-used AP-42 emission factor estimates are not appropriate.

Four coal-bark boilers and one residual oil-bark boiler were tested for sulfuric acid ([H.sub.2]S[O.sub.4]) emissions. Emissions were found to depend on the bark-to-sulfur rations 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, [H.sub.2]S[O.sub.4] emissions measured during this study were considerably lower than the U.S. Environmental Protection Agency's emission factor compilation (AP-42) estimates for coal and residual oil 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 [H.sub.2]S[O.sub.4] removal across the scrubbers ranged from 25.7% to 85.2%. View this paper online at http://www.tappi.org/index.asp?pid=29258

Vipin K. Varma is senior research engineer and Ashok K. Jain is regional manager, NCASI, Southern Region, 402 SW 140th Terrace, Newberry, FL, USA. Email Varma at [e-mail].