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Publications (10 of 176) Show all publications
Germgård, U., Sjöstrand, B. & Fiskari, J. (2023). Screening of chemical pulp, revisiting technology options, and the state-of-the-art equipment—A critical review. Canadian Journal of Chemical Engineering, 101(10), 5643-5655
Open this publication in new window or tab >>Screening of chemical pulp, revisiting technology options, and the state-of-the-art equipment—A critical review
2023 (English)In: Canadian Journal of Chemical Engineering, ISSN 0008-4034, E-ISSN 1939-019X, Vol. 101, no 10, p. 5643-5655Article in journal (Refereed) Published
Abstract [en]

Screening of pulp can be expressed as a process where solid contaminants are removed from a pulp slurry without an excessive loss of fibres of acceptable quality. The impurities originate from the feedstock, or they are generated during the transport, handling, storage, or pulping process. The most typical impurities include bark, fibre bundles or shives, knots, plastic, rubber, and sand. Moreover, there are also other objectives for screening, such as the improvement of the pulp quality, savings in bleaching chemical consumption, and protection of process equipment. In industrial applications, pulp screening is typically carried out with more than one screen for a more beneficial screening result. The pulp screening equipment can be divided into different types by the separation technique employed, such as atmospheric or pressurized screens, centrifugal screens, vibrating screens, etc. In addition, there are other types of related equipment that are common in the pulp screening process, such as knotters, refiners, and hydrocyclones. The main objective of this review is to discuss the advantages and disadvantages of modern screening equipment as well as introduce contemporary screening strategies for chemical pulp mills.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
Keywords
Kraft pulp, reject, screening, shives, wood fibres
National Category
Paper, Pulp and Fiber Technology
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-93710 (URN)10.1002/cjce.24856 (DOI)000931004700001 ()2-s2.0-85148364922 (Scopus ID)
Available from: 2023-02-18 Created: 2023-02-18 Last updated: 2024-02-07Bibliographically approved
Wilke, C., Lestelius, M. & Germgård, U. (2021). Integrated Forest Biorefinery: A Proposed Pulp Mill of 2040. Karlstad: Karlstads universitet
Open this publication in new window or tab >>Integrated Forest Biorefinery: A Proposed Pulp Mill of 2040
2021 (English)Report (Refereed)
Abstract [en]

Negative environmental impact from greenhouse gas emissions and a dwindling oil supply have resulted in an interest in biorefineries based on renewable resources. The objective of a biorefinery is to upgrade the biomass to more valuable products such as biofuels, electricity, materials, and chemicals. Wood biomass is a suitable raw material for a biorefinery since it is abundant, renewable and can be harvested all year round.

In the kraft pulping process, only half of the wood biomass is converted into pulp while the remaining part is turned into energy. A conventional kraft pulp mill could be transformed into an integrated forest biorefinery, and thus produce for example biofuels and chemicals in addition to the traditional pulp and paper products, by implementing several new processes that could utilize the byproducts. Utilization of the byproducts for other purposes than energy would obviously affect the energy balance but also the important sodium/sulfur balance.

The processes that are discussed in this report have the potential to be included in a BAT pulp mill built in 2040. The processes are black liquor gasification, on-site production of sulfuric acid, production of tall oil diesel, and lignin and hemicellulose extraction. The possibility to produce a cleaner green liquor through a new membrane filter is also discussed.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2021
Series
Karlstad University Studies, ISSN 1403-8099 ; 2021:4
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-82467 (URN)978-91-7867-180-9 (ISBN)978-91-7867-181-6 (ISBN)
Available from: 2021-01-19 Created: 2021-01-19 Last updated: 2021-02-10Bibliographically approved
Wilke, C., Andersson, N. & Germgård, U. (2019). Impact of dissolved organic matter in DO-and ADO-stages in bleaching of birch kraft pulp. Nordic Pulp & Paper Research Journal, 34(4), 433-441
Open this publication in new window or tab >>Impact of dissolved organic matter in DO-and ADO-stages in bleaching of birch kraft pulp
2019 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 34, no 4, p. 433-441Article in journal (Refereed) Published
Abstract [en]

To be able to charge a correct amount of chlorine dioxide in the D-0-stage, a pulp mill needs good control of the bleaching process and good sensors to keep the variability of the bleaching result on an acceptable level. It is also important to include the bleaching agent demand from the dissolved matter in the pulp slurry. If this is done correctly, over- or undercharging of bleaching agents can be reduced, which lead to lower bleaching chemical cost, lower polluting emissions and higher pulp quality. Our previous research has shown that the dissolved organic carryover from the O-2-stage varies significantly when bleaching softwood kraft pulp. The present study investigated the corresponding impact in the case of bleaching of birch pulp. Different mill configurations and process conditions have been simulated in laboratory trials, including proceeding A-stage treatment, different degrees of washing before and between the stages, and a comparison of the effects of recycled and non-recycled wash filtrates. The results have confirmed the significant impact of the dissolved organic matter, and the knowledge which have been generated can be used to understand how measurement and control concepts can be developed to improve the pulp quality control and to decrease production cost.

Place, publisher, year, edition, pages
Walter de Gruyter, 2019
Keywords
acid treatment; carryover; chlorine dioxide bleaching; HexA; kappa number
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-67506 (URN)10.1515/npprj-2018-0047 (DOI)000497995600004 ()
Note

Denna artikel var publicerad som manuskript i Wilkes doktorsavhandling The Impact of Dissolved Matter on Fiberline Processes (2018)

Available from: 2018-06-08 Created: 2018-06-08 Last updated: 2020-06-26Bibliographically approved
Wilke, C., Andersson, N. & Germgård, U. (2019). Impact of dissolved organic matter in hydrogen peroxide reinforced alkaline extraction stages. Appita journal, 72(1), 4-14
Open this publication in new window or tab >>Impact of dissolved organic matter in hydrogen peroxide reinforced alkaline extraction stages
2019 (English)In: Appita journal, ISSN 1038-6807, Vol. 72, no 1, p. 4-14Article in journal (Refereed) Published
Abstract [en]

It has been demonstrated in previous studies that carryover of dissolved organic matter to a following bleaching stage has a significant impact on the reactions in oxygen delignification and chlorine dioxide stages. Since hydrogen peroxide is commonly used in the bleach plant in various positions, the present study was conducted to investigate the impact of dissolved matter on the performance of a hydrogen peroxide reinforced alkaline extraction stage. The results of a study using an OD(EP) bleaching sequence showed that chlorine dioxide filtrates have a negative impact on delignification and brightening. In the case studied, the kappa number after the laboratory (EP)-stage was up to 26% higher and the brightness was up to 10% ISO lower when carryover of dissolved matter from a chlorine dioxide stage was present. Compensating for these reductions by increasing the sodium hydroxide charge improved the brightness significantly less than the delignification.

Place, publisher, year, edition, pages
Appita, 2019
Keywords
Bleaching; bleach plant control; carryover; chlorine dioxide; dissolved lignin; dissolved matter; filtrate; hydrogen peroxide; kappa number; washing
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-67510 (URN)
Note

Artikeln ingick som manuskript i Wilkes doktorsavhandling The Impact of Dissolved Matter on Fiberline Processes.

Available from: 2018-06-30 Created: 2018-06-30 Last updated: 2020-06-26Bibliographically approved
Wilke, C., Andersson, N. & Germgård, U. (2019). Oxygen delignification: Laboratory evaluation of the impact of dissolved organic matter, sodium car­bonate and sodium thiosulfate. Holzforschung, 73(7), 645-652
Open this publication in new window or tab >>Oxygen delignification: Laboratory evaluation of the impact of dissolved organic matter, sodium car­bonate and sodium thiosulfate
2019 (English)In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 73, no 7, p. 645-652Article in journal (Refereed) Published
Abstract [en]

Dissolved matter (DM) in the oxygen delignification (O2Del) stage affects the lignin and carbohydrate degradation. To understand this topic better, laboratory O2Del experiments were conducted with controlled addition of either unoxidized dissolved matter (UnoxDM) originating from the cooking stage or oxidized dissolved matter (OxDM) recycled from the post-O2Del washing. The presence of UnoxDM decreased the delignification, while the presence of OxDM showed the opposite effect, both compared to a well-washed pulp and at the same alkali charge level. However, both types of DM had a negative impact on the carbohydrate degradation. The distribution between these DMs will affect the resulting lignin degradation, because the filtrate accompanying the fibers into the O2Del stage is a mixture of UnoxDM and OxDM. It is proposed that the positive impact on the delignification by OxDM is due to the high carbonate ion concentration in the filtrate. Further, the high content of thiosulfate ions in the UnoxDM was one of the reasons for the lower delignification in its presence.

Place, publisher, year, edition, pages
Walter de Gruyter, 2019
Keywords
carbonate, carryover, COD; dissolved lignin, dissolved organic matter, filtrate, oxidized dissolved matter, oxygen delignification, thiosulfate, unoxidized dissolved matter
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-67509 (URN)10.1515/hf-2018-0179 (DOI)000472884800005 ()
Note

Artikeln ingick som manuskript i Wilkes doktorsavhandling The Impact of Dissolved Matter on Fiberline Processes.

Available from: 2018-06-30 Created: 2018-06-30 Last updated: 2020-12-10Bibliographically approved
Deshpande, R., Germgård, U., Grundberg, H., Sundvall, L., Giummarella, N., Henriksson, G. & Lawoko, M. (2018). The Reactivity of Lignin Carbohydrate Complex (LCC) During Manufacture of Dissolving Sulphite Pulp from Softwood. Industrial crops and products (Print), 315-322
Open this publication in new window or tab >>The Reactivity of Lignin Carbohydrate Complex (LCC) During Manufacture of Dissolving Sulphite Pulp from Softwood
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2018 (English)In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, p. 315-322Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Lignin carbohydrate complexes, pine heartwood, acid sulfite pulping, two-stage sulfite pulping, covalent bonds
National Category
Chemical Engineering
Research subject
Chemistry; Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-46925 (URN)10.1016/j.indcrop.2018.02.038 (DOI)000428824100037 ()
Funder
Domsjö FabrikerKnowledge FoundationMoRe ResearchKnut and Alice Wallenberg FoundationThe Kempe Foundations
Available from: 2016-10-24 Created: 2016-10-24 Last updated: 2020-06-26Bibliographically approved
Germgård, U., Magnusson, H. & Henriksson, G. (2017). Benefits obtained by integration of a dissolving pulp mill and a textile fiber plant: Final meeting in COST FP1205. In: Cellulosic material properties and industrial potential: . Paper presented at COST ACTION FP1205 Conference Stockholm, Sweden, March 7-9, 2017 (pp. 91-93). RISE
Open this publication in new window or tab >>Benefits obtained by integration of a dissolving pulp mill and a textile fiber plant: Final meeting in COST FP1205
2017 (English)In: Cellulosic material properties and industrial potential, RISE , 2017, p. 91-93Conference paper, Poster (with or without abstract) (Other academic)
Place, publisher, year, edition, pages
RISE, 2017
Keywords
dissolving pulp, integration, kraft pulp, process benefits, regenerated cellulose, sulphite pulp
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-48066 (URN)
Conference
COST ACTION FP1205 Conference Stockholm, Sweden, March 7-9, 2017
Available from: 2017-03-03 Created: 2017-03-03 Last updated: 2020-06-26Bibliographically approved
Andersson, N., Wilke, C. & Germgård, U. (2017). Impact of dissolved lignin in peroxide bleaching. In: PEERS Conference 2017: Maximizing Success Through Innovation. Paper presented at PEERS Conference 2017: Maximizing Success Through Innovation, 5 November 2017 through 8 November 2017 (pp. 597-604). TAPPI Press
Open this publication in new window or tab >>Impact of dissolved lignin in peroxide bleaching
2017 (English)In: PEERS Conference 2017: Maximizing Success Through Innovation, TAPPI Press , 2017, p. 597-604Conference paper, Published paper (Refereed)
Abstract [en]

It has been demonstrated in previous studies that dissolved lignin carryover has a significant impact in oxygen delignification and chlorine dioxide stages. Specifically for chlorine dioxide stages, it has been shown that the total kappa number of the pulp, i.e. the sum of the fiber kappa number and the filtrate kappa number, corresponds very well to its bleach demand and should be used for accurate feedforward based control. Since peroxide also is commonly used for pulp bleaching, and gaining in popularity, the present study was conducted in order to investigate the basic relations and mechanisms, using laboratory peroxide bleaching experiments comparing different carryover lignin concentrations and types. The results show that in particular chlorine dioxide filtrates have significant negative impact on delignification and brightening, likely due to alkali consumption of e.g. dissolved lignin, and that compensation using a higher alkali charge will result in lower brightness at a given kappa number. The paper also touches upon the opportunities using advanced process control systems for bleach plants, and the process and economic improvements which can be made by properly accounting for disturbances such as carryover variability.

Place, publisher, year, edition, pages
TAPPI Press, 2017
Keywords
Bleach plant control, Dissolved lignin carryover, Filtrate kappa number, Peroxide bleaching, Pulp washing, Bleaching, Cleaning, Delignification, Dissolution, Dissolved oxygen, Intelligent control, Lignin, Oxidation, Peroxides, Advanced Process Control, Bleach plant, Dissolved lignin, Economic improvements, Kappa numbers, Lignin concentration, Oxygen delignifications, Process control
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-69135 (URN)2-s2.0-85052155700 (Scopus ID)9781510852464 (ISBN)
Conference
PEERS Conference 2017: Maximizing Success Through Innovation, 5 November 2017 through 8 November 2017
Available from: 2018-09-07 Created: 2018-09-07 Last updated: 2020-06-26Bibliographically approved
Wilke, C., Andersson, N. & Germgård, U. (2017). Impact of dissolved matter in the oxygen delignification stage. TAPPI Journal, 16(5), 275-284
Open this publication in new window or tab >>Impact of dissolved matter in the oxygen delignification stage
2017 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 16, no 5, p. 275-284Article in journal (Refereed) Published
Abstract [en]

The presence of dissolved matter in the pulp suspension in an oxygen (O-2) delignification stage, consisting mainly of dissolved lignin, is normally considered to negatively affect the delignification rate due to the competing reactions between the fiber bound lignin and the lignin dissolved in the filtrate. Recirculated oxidized filtrate from the post-O-2 washing is usually considered to be less harmful to the delignification efficiency than unoxidized dissolved matter originating from the cooking stage. To develop a better understanding of the mechanisms of the dissolved matter's reactions and impact on the O-2 stage performance, laboratory oxygen delignification experiments with varying levels of unoxidized and oxidized dissolved matter were conducted. The results showed that unoxidized dissolved matter had a negative impact on the delignification in the O-2 stage, whereas oxidized dissolved matter actually had a positive effect. The delignification efficiency of the laboratory experiments thus depends on both the amount of dissolved matter and its origin. The pulp viscosity decreased with increasing dissolved matter content irrespective of its origin but at higher COD levels; however, the viscosity drop was larger for the unoxidized dissolved matter. In terms of selectivity, the oxidized filtrate had a similar impact as additional NaOH charge. Both types of filtrates consumed hydroxide and the final pH decreased with increasing dissolved matter content. The final pH was significantly lower in the unoxidized filtrate experiments at higher COD levels, indicating a high reactivity between the unoxidized dissolved matter and the oxygen in the reactor. Based on the results, further understanding is achieved about the relation between pre-O-2 washing performance and process configuration in an actual mill case, as well as the impact of dissolved matter on delignification. The importance of efficient removal of harmful unoxidized dissolved matter is verified, but the results also suggest that the oxidized dissolved matter that is recirculated from post-O-2 washing actually has a significant positive impact on the delignification and is not just a potential problem in case of carryover to the bleach plant. Subsequently, pulp washing efficiency is critical both pre- and post-O-2.

Place, publisher, year, edition, pages
TAPPI Press, 2017
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-65647 (URN)000403367800004 ()
Available from: 2018-01-17 Created: 2018-01-17 Last updated: 2020-06-26Bibliographically approved
Andersson, N., Wilke, C., Akhlesh, M., Smith, D. & Germgård, U. (2017). Measurement of Dissolved Lignin, and its Impact in Fiberline Unit Operations. In: : . Paper presented at The 19th International Pulp Bleaching Conference, Aug. 28-30, 2017. Porto Seguro, BA, Brazil (pp. 1-7).
Open this publication in new window or tab >>Measurement of Dissolved Lignin, and its Impact in Fiberline Unit Operations
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2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Keywords
Online measurement; Advanced process control; Dissolved lignin; Oxygen delignification; Chlorine dioxide bleaching
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-62607 (URN)
Conference
The 19th International Pulp Bleaching Conference, Aug. 28-30, 2017. Porto Seguro, BA, Brazil
Available from: 2017-08-10 Created: 2017-08-10 Last updated: 2020-06-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6470-6019

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