Characteristics and sources of intermediate size particles in recovery boilers : final project report.

Baxter, Larry L. (Brigham Young University, Provo, UT) ; Shaddix, Christopher R. ; Verrill, Christopher L. (Georgia Institute of Technology, Institute of Paper Science and Technology, Atlanta, GA) ; Wessel, Richard A. (Babcock & ; Wilcox Company, Barberton, OH)

Sandia National Laboratories

关键词: Waste Heat Boilers;    Combustion;    Particles-Measurement.;    Spent Liquors;    Chars;   

DOI  :  10.2172/921725
RP-ID  :  SAND2005-0296
RP-ID  :  AC04-94AL85000
RP-ID  :  921725

美国|英语

来源: UNT Digital Library

【 摘 要 】

As part of the U.S. Department of Energy (DOE) Office of Industrial Technologies (OIT) Industries of the Future (IOF) Forest Products research program, a collaborative investigation was conducted on the sources, characteristics, and deposition of particles intermediate in size between submicron fume and carryover in recovery boilers. Laboratory experiments on suspended-drop combustion of black liquor and on black liquor char bed combustion demonstrated that both processes generate intermediate size particles (ISP), amounting to 0.5-2% of the black liquor dry solids mass (BLS). Measurements in two U.S. recovery boilers show variable loadings of ISP in the upper furnace, typically between 0.6-3 g/Nm{sup 3}, or 0.3-1.5% of BLS. The measurements show that the ISP mass size distribution increases with size from 5-100 {micro}m, implying that a substantial amount of ISP inertially deposits on steam tubes. ISP particles are depleted in potassium, chlorine, and sulfur relative to the fuel composition. Comprehensive boiler modeling demonstrates that ISP concentrations are substantially overpredicted when using a previously developed algorithm for ISP generation. Equilibrium calculations suggest that alkali carbonate decomposition occurs at intermediate heights in the furnace and may lead to partial destruction of ISP particles formed lower in the furnace. ISP deposition is predicted to occur in the superheater sections, at temperatures greater than 750 C, when the particles are at least partially molten.