Enhanced Control of TRS Excursions from Kraft Mill Lime Kilns, 1996 Environmental Conference Proceedings

Kraft pulp and paper facilities utilize lime kilns to incinerate Total Reduced Sulfur (TRS) from lime mud cake. Additionally, non-condensable gases (NCG’s) are vented into the hot kiln where they are oxidized. Plant upsets, insufficient oxygen, and mud filtration problems are a few of the conditions which result in TRS emissions exceeding air quality permit levels. The addition of hydrogen peroxide to the lime mud prior to the lime kiln has been shown to reduce TRS emissions and provide the capability to control excursions. The design of the hydrogen peroxide dosing system is critical to the success of this technology. This paper will review the results of full scale implementation of a hydrogen peroxide system designed to control TRS excursions from lime kilns at a kraft mill. The importance of a control loop to maintain compliance with TRS limits while minimizing hydrogen peroxide usage is discussed. Implementation of this system has successfully controlled TRS excursions for over one year.