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| 3. |
- Bialik, Marta, et al.
(författare)
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Design, optimization and modelling of a chemical recovery system for wet spinning of cellulose in sodium carbonate solutions
- 2020
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Ingår i: Cellulose. - : Springer. - 0969-0239 .- 1572-882X. ; 27, s. 8681-8693
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to present the design, optimization and modelling of a chemical recovery system for a novel CS2-free viscose-type process that entails dissolution of pre-treated dissolving pulp in a continuous-flow reactor in cold alkali and wet spinning of cellulose in sodium carbonate solutions. Technologies already known to other industries for the recovery and reuse of chemicals, such as causticizing, recalcination, recarbonization and freeze-separation, were used. Chemical equilibria simulations were performed with OLI Studio 9.5, with the purpose to select experimental conditions which avoid undesired precipitations in each unit operation. Synthetic solutions mimicking the spent coagulation liquor were used in the laboratorial experiments. The proposed chemical recovery system was shown to be technically feasible and reduce chemical make-ups to a minimum of 45 kg/ton of NaOH and 4 kg/ton of H2SO4. Small amounts of Zn are expected to precipitate during recarbonization of the coagulation liquor at 30 °C and causticizing at 98 °C. Thus, a filter for ZnO particles should be included in the design of the recarbonization unit and a continuous purge of lime mud and input of fresh lime make-up should be needed to keep burnt lime availability at an acceptable level. Overall, the results presented in this study portray a solution to reduce operating costs and the environmental impact of novel viscose-type processes with alkaline spin dopes and wet spinning of cellulose in sodium carbonate solutions. © 2020, The Author(s).
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- Brännvall, Elisabet, et al.
(författare)
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Consequences in a softwood kraft pulp mill of initial high alkali concentration in the impregnation stage
- 2019
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Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 34:1, s. 28-35
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Tidskriftsartikel (refereegranskat)abstract
- Impregnation with high initial concentration is fast and efficient, leading to a homogeneous delignification in the subsequent cook, resulting in improved screened pulp yield. To obtain high initial alkali concentration, the white liquor flow needs to be significantly increased. The moisture content of the wood chips and the alkali concentration of the white liquor limit the initial alkali concentration of the impregnation liquor that can be reached. It is therefore of interest to evaluate the possibility to implement high alkali impregnation (HAI) industrially and the consequences this would have on the mill system. The effect of HAI on mass and energy balances in a kraft pulp mill has been studied using mill model simulations. The sensitivity to disturbances in important parameters for process control has been compared to impregnation scenarios used industrially. It was shown that high initial alkali concentration can be achieved on industrial scale by increased white liquor flow. HAI has a positive effect on recovery flows and reduces the need for make-up chemicals. The HAI concept is less sensitive to variations in process parameters, such as chip moisture and white liquor concentration, thus diminishing the risk of alkali depletion in chip cores. © 2019 Brännvall and Kulander.
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- Jafri, Yawer, 1988-, et al.
(författare)
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Multi-aspect evaluation of integrated forest-based biofuel production pathways : Part 2, economics, GHG emissions, technology maturity and production potentials
- 2019
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 172, s. 1312-1328
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Tidskriftsartikel (refereegranskat)abstract
- Promoting the deployment of forest-based drop-in and high blend biofuels is considered strategically important in Sweden but many aspects of the overall performance of the foremost production technologies are as yet unexamined. This paper evaluates the technology maturity, profitability, investment requirements, GHG performance and Swedish biofuel production potential of six commercially interesting forest-based biofuel production pathways.Significant heterogeneity in technology maturity was observed. Lack of technical demonstration in industrially representative scales renders the liquefaction-hydrotreatment route for drop-in biofuels less mature than its gasification-catalytic upgrading counterpart. It is a paradox that short-term priority being accorded to pathways with the lowest technology maturity. Nth-of-a-kind investments in (a) gasification-based methanol, (b) hydropyrolysis-based petrol/diesel, and (c) lignin depolymerization-based petrol/diesel were profitable for a range of plant sizes. The profitability of pulp mill-integrated small gasification units (<100 MW) goes against the common perception of gasification being economically feasible only in large scales. New low-cost options for debottlenecking production at recovery boiler-limited kraft mills appear worth investigating. GHG emission reductions ranged from 66 to 95%; a penalty was incurred for high consumption of natural gas-based hydrogen. Swedish biofuel production potentials ranged from 4 to 27 TWh/y but a more feasible upper limit is 12–15 TWh/y.
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- Jafri, Yawer, 1988-, et al.
(författare)
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Multi-aspect evaluation of integrated forest-based biofuel production pathways : Part 1. Product yields & energetic performance
- 2019
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 166, s. 401-413
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Tidskriftsartikel (refereegranskat)abstract
- Forest-based biofuels are strategically important in forest-rich countries like Sweden but the technical performance of several promising production pathways is poorly documented. This study examines product yields and energy efficiencies in six commercially relevant forest-based “drop-in” and “high blend” biofuel production pathways by developing detailed spreadsheet energy balance models. The models are in turn based on pilot-scale performance data from the literature, supplemented with input from technology developers and experts. In most pathways, biofuel production is integrated with a market pulp mill and/or a crude oil refinery. Initial conversion is by pyrolysis, gasification or lignin depolymerization and intermediate products are upgraded by hydrotreatment or catalytic synthesis. While lignin oil (LO) hydrodeoxygenation had the highest expanded system efficiency, considerable uncertainty surrounds product yields owing to absence of suitable experimental data on LO upgrading. Co-feeding vacuum gas oil and fast pyrolysis oil in a fluidized catalytic cracker has a complex and uncertain effect on fossil yields, which requires further investigation. Co-locating bio-oil hydrotreatment at the refinery improves heat utilization, leading to higher system efficiencies. Explicit consideration of mill type and energy requirements is required to avoid performance misestimation as an assumption of energy surplus can confer a definite advantage.
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- Lindgren, Karin, et al.
(författare)
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Full mill model for dissolving pulp based biorefinery
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Material and energy balances of a modern theoretical dissolving softwood kraft pulp mill, using pre-hydrolysis in water, have been established. The mill produces 1000 ADt/day and there is an energy excess in the mill that could be used to produce power. If lignin is removed with the LignoBoost process the recovery boiler is unloaded enabling an increased pulp production. With a lignin removal of 0.2 ton/ADt the pulp production could increase 8.5%. According to a sensitivity analysis the lignin price has the largest impact on the economic performance.
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| 12. |
- Lindgren, Karin, et al.
(författare)
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Soap separation : A new option for removal of NPEs
- 2018
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Ingår i: Pulping Engineering and Environmental Recycling Sustainability Conference, PEERS 2018. - : TAPPI Press. ; , s. 272-277
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Non-process elements (NPEs) are elements present in the process streams without taking part in the desired reaction. With increasing process closure and new NPE-rich input streams such as gasified bark in the lime kiln and the destruction of biosludge in the recovery boiler, the traditional purge points may prove insufficient. A new method to remove NPEs is suggested: Removal of NPEs from tall oil brine. The idea is based on the fact that many elements are enriched in the soap and separated from the black liquor but are later led back to the black liquor with the brine. The results showed strong enrichment of Ba, Ca, Mg, Mn, P and Zn in soap; an enrichment factor of 8 or higher was observed. Laboratory experiments where tall oil brine has been alkalized and subjected to a separation stage have been conducted. The laboratory experiments showed that more than 90% of Al, Ba, Mg, Mn and P precipitates and could be removed with the solid phase if alkalized to pH 11. The separation efficiency varied for Ca and Si from 70-85 %. To conclude, removal of non-process elements from tall oil brine is a promising new kidney, especially for P and Si.
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| 13. |
- Lindgren, Karin, et al.
(författare)
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Techno economic evaluation of lignin extraction in a dissolving pulp biorefinery
- 2017
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Ingår i: The 7th Nordic Wood Biorefinery Conference held in Stockholm, Sweden, 28-30 Mar. 2017. - Stockholm : RISE Bioekonomi. - 9789186018207 ; , s. 118-123
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Konferensbidrag (refereegranskat)abstract
- A simulation model for dissolving pulp production using prehydrolysis kraft process has been developed at Innventia, which reflects a greenfield dissolving softwood kraft pulp mill producing 1,000tpd. The fibrelines comprised a separate prehydrolysis stage before the impregnation stage, with condensate from black liquor evaporation and steam being added to the prehydrolysis stage. The liquor was then removed from the chips and fed to the evaporation plant. The prehydrolysed chips were subjected to impregnation, cooking and oxygen delignification in double stages, with the oxygen delignified pulp being bleached in a four stage sequence D1(EOP)D2P. The simulation program WinGEMS 5.0 was used to establish material and energy balances. A lignin production of 0.2t/t increased pulp production by 8.5%. The heat value of the black liquor decreased but would still be high enough for stable and favourable combustion properties in the recovery boiler. It was found that the lignin price had the largest impact on the economic performance. Lignin removal increased the pulp production and was economically viable, especially if the possibility to produce electricity was low.
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