Combustion properties of spruce black liquor droplets: Sulfur-free pulping and influence of hot-water pretreatment
Chengcong Chen, Raimo Alén, Joni Lehto and Hannu Pakkanen, University of Jyväskylä, Jyväskylä, Finland
Hot-water pretreatment of lignocellulosics prior to sulfur-free alkaline pulping is an interesting approach for recovering value-added carbohydrate- and lignin-derived materials. This paper investigated the chemical composition variations and combustion properties of the black liquors (BLs) from three different cooking processes: two sulfur-free soda-anthraquinone (soda-AQ) and oxygen-alkali (O2-NaOH) cooks and kraft cook, before and after hot-water pretreatment of the spruce sawdust. Relatively less aliphatic acids but more lignin were present in the BLs after hot-water pretreatment as cooking time prolonged. In general, the burning time decreased as follows: soda-AQ BL > O2-NaOH BL kraft BL. With the same cooking time, the increase in the total burning time for soda-AQ BLs compared with kraft BLs was 11-17% (without pretreatment) and 25-39% (with pretreatment). Compared to kraft BLs with the same cooking time, the swelling for soda-AQ and O2-NaOH BLs decreased by 8-25% and 4-23%, respectively.
Black liquor, Combustion properties, Hot-water pre-treatment, Spruce, Sulfur-free pulping
Nordic Pulp & Paper Research Journal (NPPRJ) is an international scientific magazine covering science and technology for the areas of wood or bio-mass constituents, pulp and paper and including new fiber-based materials, recovery and by-products from pulping processes, bio-refining and energy issues. Articles meeting required scientific standards are accepted from any continent. Open Access: Articles not available through Gold Open Access may be purchased by credit card as a pdf file, to be downloaded within 24 h after ordering, at a price of 22 EUR per article. (Value added tax may apply depending on your location, which you enter at payment logout.) Such articles have Green Open Access, i.e. authors may share articles on their personal non-commerical homepage immediately after publication on the website and download them to non-commercial hosting platforms one year after publication in a full issue of NPPRJ. ISSN: 0283-2631