Formation of blue deposits in kraft recovery boilers

• Published in: TAPPI Journal
• Main Authors: Mao, Xiaosong, Tran, Honghi
• Format: Article in Journal/Newspaper
• Language: English
• Published: TAPPI Press 2016
• Subjects: Canada; Fireside; Nacka; Wilcox; Peace River
• Online Access: http://hdl.handle.net/1807/97456; https://doi.org/10.32964/tj15.3.195

Fireside deposits in recovery boilers are typically white, red, pink, grey, black, or occasionally yel - low, depending on where they are in the boiler, the mechanisms by which they are formed, and the environment to which they are exposed. Although rare, blue deposits have been reported, and some were “bluer” than others. This study systematically examines the cause of the blue coloration of deposits in recovery boilers. The results show that for a deposit to become blue, it must a) contain sodium carbonate, b) contain a small amount of manganese, c) be molten or partially molten, and d) have exposure to an oxidizing atmosphere. Because deposits always contain sodi - um carbonate and manganese, these requirements suggest that blue deposits can form only in the superheater region of the recovery boiler when oxidizing conditions prevail. Blue coloration is thus more likely to be observed in boilers operating at a reduced firing load with a high excess oxygen target. This work was conducted as part of the research program on “Increasing 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, WestRock, StoraEnso Research, Suzano, Tembec, Tolko Indus - tries, and Valmet.