Effects of added materials on black liquor combustion

Black liquor is often mixed with various types of materials before being burned in a recovery boiler to meet specific needs of kraft pulp mills. A systematic study was conducted using a thermogravimetric combustor to examine how added materials might affect the combustion behavior of black liquors obtained from several pulp mills. The results show that adding soap, caustic, white liquor, and sawdust significantly reduces the liquor swelling tendency, thereby requiring a longer time for the liquor to burn completely. Adding makeup saltcake, precipitator ash, sodium sulfate, and biosludge, on the other hand, has little or no effect on the liquor combustion behavior.This work was conducted as part of the research program In - creasing Energy and Chemical Recovery Efficiency in the Kraft Process—III, jointly supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and a consortium of the following companies: Andritz, AV Nacka - wic, Babcock & Wilcox, Boise, Carter Holt Harvey, Celulose Nipo-Brasileira, Clyde-Bergemann, DMI Peace River Pulp, El - dorado, ERCO Worldwide, Fibria, FPInnovations, Internation - al Paper, Irving Pulp & Paper, Kiln Flame Systems, Klabin, StoraEnso Research, Suzano, Tembec, Tolko Industries, Val - met, and WestRock