UPGRADED RECOVERY BOILER MEETS LOW AIR EMISSIONS STANDARDS

In the fall of 1990, the Boise Cascade mill in International Falls, MN , carried out a millwide modernization project. One critical element o f the project was the upgrade of their recovery boiler. As a result of the recovery boiler upgrade, the mill was required to obtain a preven tion of significant deterioration (PSD) air permit. A best available c ontrol technology (BACT) assessment was performed as a requirement of the PSD regulations. Ultimately, a number of more stringent air pollut ion emission limits were established for the boiler, and a continuous emissions monitoring system (CEMS) was purchased and installed to repo rt daily results to the Minnesota Pollution Control Agency. This paper describes our efforets to achieve increased firing capacity in the mi ll's recovery boiler while meeting more severe air emissions regulatio ns. We will show that each of the emissions limits, including CO, SO2, NO(x), TRS, and opacity, are met by the upgraded boiler, while achiev ing an increase in firing capacity over pre-upgrade levels of up to 40 %.