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- Gall, Dan, 1981, et al.
(author)
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Recirculation of NO x and SO x Scrubber Effluent to an Industrial Grate Fired MSW Boiler-Influence on Combustion Performance, Deposition Behavior, and Flue Gas Composition
- 2022
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In: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 36:11, s. 5868-5877
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Journal article (peer-reviewed)abstract
- The concept of scrubber effluent recirculation has recently received attention in connection to NOxemission control. Here, we present data from an industrial-scale MSW-fired plant, where effluent from a combined NOxand SOxscrubber was recirculated and injected into a grate-fired boiler. The combustion characteristics were carefully studied during the injections to observe the potential effects on burnout and flue gas composition. In addition, deposition measurements were performed to observe effects on growth rate and chemical composition of deposits, which are critical factors for any solid fuel-fired heat and power plant. The recirculation of the nitrogen-rich waste streams was performed via pre-existing liquid injection equipment, and the results show that the N-containing compounds in the scrubber effluent were efficaciously reduced to inert nitrogen gas. Furthermore, the recirculation of the scrubber effluent may reduce ammonia demand for selective non-catalytic reduction systems by inhibiting the formation of ammonium chloride. Sulfur and alkali components in the effluent increased the deposition growth rate and also changed the chemical composition of the deposits. Understanding how the local conditions at the injection point influence the distribution and speciation of the injected compounds is essential for a successful recirculation strategy.
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- Heijnesson-Hulten, Anette, et al.
(author)
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Impact of Drying on the Quality of Bamboo Kraft Pulps
- 2013
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In: BioResources. - : NORTH CAROLINA STATE UNIV DEPT WOOD & PAPER SCI, CAMPUS BOX 8005, RALEIGH, NC 27695-8005 USA. - 1930-2126. ; 8:1, s. 1245-1257
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Journal article (peer-reviewed)abstract
- This study investigates how drying affects the quality of bamboo kraft pulps. Two bamboo pulps, cooked to different kappa numbers (i.e. 10 and 26) and D(EOP)D bleached to approximately the same brightness, were used to examine the relationship between cooking, drying, refining, and pulp/fiber properties. Drying of the two pulps caused, as expected, a loss in tensile and burst strength while the tear index was improved. The bleached high kappa pulp required less energy to reach a certain Schopper Riegler value and exhibited greater strength properties than the low kappa number pulp. These differences were also maintained after drying. Results showed that the properties of the pulp before drying determined the final strength potential of the pulp after drying. Thus, kraft cooking of bamboo to high kappa number prior to bleaching gave pulps with improved response to refining and pulp strength properties, which in turn influenced the properties of the dried pulps.
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- Heijnesson Hultén, Anette, 1965
(author)
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Kraft Pulp Fibre Surfaces. Chemical Composition and Effect on Pulp Bleachability
- 1996
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Doctoral thesis (other academic/artistic)abstract
- The work presented in this thesis concerns studies of kraft fibre surfaces in respect of chemical composition and effect on pulp bleachability. Kraft fibre surfaces were studied by mechanical peeling using a disintegrator operated at 20.000-200.000 revolutions and a pulp consistency of 3% or 4.5%. Surfaces of unbleached kraft pulp fibres of different origin and kappa numbers exhibited a high lignin content compared to the bulk of the fibres. The lignin content of pulp fractions enriched in the ray cells was also higher than that of corresponding fibres. In unbleached pine kraft pulp similar contents of xylan were found in the fibre surfaces and ray cells compared to the fibres, whereas these fractions exhibited a relatively high xylan content in birch kraft pulp. Results obtained for pine kraft pulp indicated no extensive reprecipitation of xylan on the pine fibre surfaces during the pulping process. Metal ion enrichment was observed in both surface material and ray cells of unbleached kraft fibres. The distribution patterns of the metal ions, Mn, Fe, Cu, Ca and Mg were similar to those found in wood. Furthermore, the content of Mn and Ca correlated well with the content of lignin and carboxy groups in the different pulp fractions. In unbleached pine kraft fibres, xylanase acted relatively uniformly on all accessible surfaces, whereas the action of mannanase was more pronounced on the outermost fibre surface than in the inner fibre wall. In unbleached birch kraft fibres, attack on the fibre surface was more extensive compared to the inner parts of the fibres. The action of xylanase on pine and birch kraft fibres differed both in site and intensity, probably reflecting the different chemical composition of the two types of pulp fibres. Fibre surface material and ray cells of both pine and birch kraft pulps affected the bleachability in an enzyme-aided bleaching with one stage of peroxide treatment. The effect of the enzymic treatment was enhanced when surface material and ray cells were removed prior to treatment and, following peroxide bleaching, a higher brightness level and lower kappa number were obtained compared to the reference pulp. However, removal of surface material and ray cells from a pulp manufactured according to an extended cooking procedure prior to bleaching in a TCF-sequence had no significant effect on the final brightness and kappa number. However, a higher viscosity and brightness stability, and a lower consumption of hydrogen peroxide, was recorded when surface material and ray cells were removed.
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