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Germgård, Ulf
Alternative names
Publications (10 of 174) Show all publications
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: 2019-11-25Bibliographically 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)
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: 2019-09-12Bibliographically 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: 2018-09-06Bibliographically 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: 2019-11-21Bibliographically 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: 2018-09-10Bibliographically 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: 2018-07-05Bibliographically 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: 2018-09-07Bibliographically approved
Germgård, U. (2017). The Arrhenius Equation is Still a Useful Tool in Chemical Engineering. Nordic Pulp & Paper Research Journal, 32(1), 21-24
Open this publication in new window or tab >>The Arrhenius Equation is Still a Useful Tool in Chemical Engineering
2017 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 1, p. 21-24Article in journal (Refereed) Published
Abstract [en]

The Arrhenius equation correlates the rate of a chemical reaction with the corresponding activation energy, reaction time and reaction temperature, where the latter is measured in Kelvin. Although the equation is rather simple it can be used to summarize the kinetics of most chemical reactions in a surprisingly good manner. The activation energy is an interesting parameter that can be seen as an energy barrier which the reacting chemicals have to pass before a chemical reaction is initiated. Thus, the higher the activation energy, the lower is the rate of the chemical reaction. Moreover, the equation can also be used, for example, to forecast the influence of a higher temperature on the composition of a product consisting of components with different activation energies. In such a case, a component with higher activation energy will increase its rate of reaction more than a component with lower activation energy. The composition of the original product will thus obtain a shrinking fraction of the fast reacting component. The report gives some guidelines of how to calculate the activation energy for a given case in a pulp mill.

Place, publisher, year, edition, pages
AB SVENSK PAPPERSTIDNING, 2017
Keywords
Activation energy, Cellulose, Hemicellulose, Kinetics, Kraft pulping, Lignin, Sulfite pulping
National Category
Chemical Engineering
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-65407 (URN)10.3183/NPPRJ-2017-32-01-p021-024 (DOI)000398384400003 ()
Available from: 2017-12-14 Created: 2017-12-14 Last updated: 2018-08-15Bibliographically approved
Hellström, P., Heijnesson-Hulten, A., Paulsson, M., Håkansson, H. & Germgård, U. (2016). A comparative study of enzymatic and Fenton pretreatment applied to a birch kraft pulp used for MFC production in a pilot scale high-pressure homogenizer. TAPPI Journal, 15(6), 375-381
Open this publication in new window or tab >>A comparative study of enzymatic and Fenton pretreatment applied to a birch kraft pulp used for MFC production in a pilot scale high-pressure homogenizer
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2016 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 15, no 6, p. 375-381Article in journal (Refereed) Published
Abstract [en]

Microfibrillated cellulose (MFC) was produced in pilot scale from a bleached birch (Betula verrucosa) kraft pulp that was pretreated with either Fenton's reagent or with a combined mechanical and enzymatic method used at the Centre Technique du Papier (CTP; Grenoble, France). The change in fiber fibrillation during the homogenization treatment was monitored by analyzing the fiber and the fines content, size fractionation, rheological properties and visualization by light-and scanning electron microscopy (SEM). The Fenton pretreatment resulted in MFC suspensions that contained a high amount of small sized elements. After five passes through the high-pressure homogenizer, the amount of particles smaller than 20 mu m was 37% for the Fenton pretreated MFC compared to 13% for the enzymatically (endoglucanase) pretreated MFC. Altogether, the Fenton pretreatment enabled preparation of MFC with a higher degree of fibrillation after the same number of passes through the high-pressure homogenizer. Another option is to produce MFC of the same amount of fibrillation as after an enzymatic stage, but at significantly lower energy consumption.

Place, publisher, year, edition, pages
TAPPI Press, 2016
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-46239 (URN)000380267900004 ()
Available from: 2016-09-21 Created: 2016-09-21 Last updated: 2019-11-21Bibliographically approved
Wilke, C., Andersson, N., Van Fleet, R., Mathur, A. & Germgard, U. (2016). Impact of dissolved lignin in oxygen delignification and chlorine dioxide stages. Paper presented at Conference on Pulping, Engineering, Environmental, Recycling, Sustainability (PEERS), OCT 25-28, 2015, Atlanta, GA. TAPPI Journal, 15(3), 167-174
Open this publication in new window or tab >>Impact of dissolved lignin in oxygen delignification and chlorine dioxide stages
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2016 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 15, no 3, p. 167-174Article in journal (Refereed) Published
Abstract [en]

While carryover of dissolved lignin between stages in the pulp mill fiber line is a well-known problem, it is still typically seen only as a minor disturbance factor or bias in the control of oxygen (O-2) delignification and bleaching stages. The present study, however, reveals that it plays a larger role than anticipated, and that it should be properly analyzed in order to correctly control the process stages. This is especially important for the O-2 and D-0 stages as the lignin content is still high in these positions. The results of the study show that dissolved lignin carried over between stages may have a significant impact on the bleaching chemical consumption and, indirectly, on the pulp quality. Mill investigations have shown very large variations in the dissolved lignin content in the pulp before the oxygen delignification stage and before the D-0 stage that have significantly influenced the bleaching chemical demand and, subsequently, the degree of delignification. In order to develop a better understanding of the mechanisms of the dissolved lignin's reactions, laboratory O-2 and D-0 experiments with controlled levels of dissolved lignin were conducted. It was anticipated that a better feedforward control could be achieved using an online dissolved lignin measurement, and results from mill trials are presented. Chlorine dioxide laboratory experiments using different levels of carryover (i.e., different dissolved lignin contents) were conducted. It was concluded that the filtrate kappa number provides a relevant measure of the bleach demand due to the dissolved lignin and that, subsequently, the combined fiber and filtrate kappa number provides an appropriate measure for optimum feedforward control of the stages. Mill results support these findings, which show that the chemical consumption is reduced significantly using the total kappa number. The post-D or post-DE kappa number feedback control can most probably be eliminated by using this technology.

National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-42029 (URN)000373923900004 ()
Conference
Conference on Pulping, Engineering, Environmental, Recycling, Sustainability (PEERS), OCT 25-28, 2015, Atlanta, GA
Available from: 2016-05-13 Created: 2016-05-13 Last updated: 2018-07-02Bibliographically approved
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