miun.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Berg, Jan-Erik
Publications (10 of 23) Show all publications
Sandberg, C., Berg, J.-E. & Engstrand, P. (2019). Low Consistency Refining Combined with Screen Fractionation: Reduction of Mechanical Pulping Process Complexity. BioResources, 14(1), 882-894
Open this publication in new window or tab >>Low Consistency Refining Combined with Screen Fractionation: Reduction of Mechanical Pulping Process Complexity
2019 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 1, p. 882-894Article in journal (Refereed) Published
Abstract [en]

Process intensification is a process development methodology aimed at a considerable reduction in the energy consumption and process complexity. The approach has been applied to mechanical pulping process design. A process denoted as HC-LC-S consisting of single stage high consistency (HC) refining, followed by low consistency (LC) refining and screening was evaluated in mill trials at the Holmen Paper Braviken Mill in Sweden. After LC refining, the pulp was screened, and the reject fraction was fed back to LC refining. Two HC primary refiner types were evaluated, namely single disc (SD) and double disc (DD). Double disc chip refining was more suitable than SD refining for the HC-LC-S process because of the higher light scattering and lower shives content of the final pulp. The tensile index and shives content of the pulp produced with the DD-LC-S process was similar to that of the reference process, consisting of single stage DD refining and HC reject refining, but the fibre length and light scattering were somewhat lower. The specific refining energy was approximately 200 kWh/adt lower for the DD-LC-S process compared with the reference. Additionally, the auxiliary specific energy was 100 kWh/adt lower for the HC-LC-S processes, since a number of equipment units were omitted.

Keywords
mechanical pulping, TMP, low consistency refining, screening, fractionation, process intensification
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-35393 (URN)000459494400063 ()2-s2.0-85061297839 (Scopus ID)
Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-08-07Bibliographically approved
Sandberg, C., Nelsson, E., Engberg, B. A., Berg, J.-E. & Engstrand, P. (2018). Effects of chip pretreatment and feeding segments on specific energy and pulp quality in TMP production. Nordic Pulp & Paper Research Journal, 33(3), 448-459
Open this publication in new window or tab >>Effects of chip pretreatment and feeding segments on specific energy and pulp quality in TMP production
Show others...
2018 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 3, p. 448-459Article in journal (Refereed) Published
Abstract [en]

Increased wood softening and refining intensity have earlier been utilized to improve refining efficiency in mechanical pulping. We have evaluated a combination of increased softening by low dose sulphite chip pretreatment and increased intensity by feeding segment design in a TMP line for production of high quality printing papers. Norway spruce wood chips were preheated, compressed in an Impressafiner and impregnated with water or sodium sulphite solutions (Na2SO3 charges 3.6 and 7.2 kg/t). Chips were refined in two parallel 68" double disc refiners using two different refining conditions: standard bidirectional segments at normal production rate (9 t/h) and feeding segments at increased production rate (11.1-12.1 t/h). The feeding segments enabled a 30 % increase in production rate. Refining with feeding segments at 12.1 t/h production rate combined with chip pretreatment with 3.6 kg/t sodium sulphite reduced the specific energy 360 kWh/t (19 %) compared to refining with standard segments and no pretreatment. Pulp properties were similar for the two configurations. The combination of feeding segments and chip pretreatment with water reduced the specific energy 180 kWh/t (9 %). Implementation of most of the technology presented has reduced the electrical energy use for the mill by approximately 80 GWh/year.

Keywords
chip pretreatment, double disc refiner, energy efficiency, mechanical pulping, refining intensity, sodium sulphite
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-34604 (URN)10.1515/npprj-2018-3052 (DOI)000450923900011 ()2-s2.0-85053157973 (Scopus ID)
Available from: 2018-10-03 Created: 2018-10-03 Last updated: 2018-12-11Bibliographically approved
Sandberg, C., Berg, J.-E. & Engstrand, P. (2018). LC refining combined with screen fractionation – Reduction of system complexity for mechanical pulping. In: IMPC 2018: . Paper presented at International Mechanical Pulping Conference (IMPC) 2018, May 27-30, 2018, Trondheim, Norway. Trondheim, Norway
Open this publication in new window or tab >>LC refining combined with screen fractionation – Reduction of system complexity for mechanical pulping
2018 (English)In: IMPC 2018, Trondheim, Norway, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Process intensification - a process development method used in the chemical process industry has been appliedto mechanical pulping process design. Process intensification is characterized by significant reduction of energyconsumption and process complexity.A process with single stage high consistency (HC) refining followed by low consistency (LC) refining andscreening was evaluated in mill trials at the Holmen Paper Braviken mill, Sweden. After LC refining, pulp wasscreened and the reject was fed back to LC refining. The process is called HC-LC-S. Two different HC primaryrefiner types were evaluated – single disc (SD) and double disc (DD).High intensity DD chip refining was more suitable than single disc refining for the process due to higher lightscattering and lower shives content of the final pulp. It was also easier to reach high enough tensile index beforeLC refining with the DD refining. The DD-LC-S process required 1940 kWh/adt total specific energy for newsgrade TMP, which was 300 kWh/adt lower than the reference TMP line; DD chip refining and HC rejectrefining. The auxiliary specific energy was reduced with 100 kWh/adt.Six unit operations and three chests with agitators and pumps were omitted compared to a conventional TMPline.

Place, publisher, year, edition, pages
Trondheim, Norway: , 2018
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:miun:diva-34674 (URN)
Conference
International Mechanical Pulping Conference (IMPC) 2018, May 27-30, 2018, Trondheim, Norway
Available from: 2018-10-09 Created: 2018-10-09 Last updated: 2018-10-09Bibliographically approved
Sandberg, C., Berg, J.-E. & Engstrand, P. (2017). Low consistency refining of mechanical pulp - system design. TAPPI Journal, 16(7), 419-429
Open this publication in new window or tab >>Low consistency refining of mechanical pulp - system design
2017 (English)In: TAPPI Journal, ISSN 0734-1415, Vol. 16, no 7, p. 419-429Article in journal (Refereed) Published
Abstract [en]

Many mechanical pulping mills use low consistency (LC) refining for energy efficient fiber development. In this study, energy efficiency and pulp quality were evaluated for six processes, of which four included LC refining. We studied two different types of chip refiners - single disc (SD) and double disc (DD) - with LC refining in the main and reject lines. All process combinations have been used in the Holmen Paper Braviken mill, Sweden, to make thermomechanical pulp for printing papers. LC refining was more energy efficient than high consistency (HC) refining at certain tensile index increases in all evaluated combinations. LC refining in the main line had somewhat higher energy efficiency than did LC refining in the reject line. The type of chip refiner (DD or SD) did not affect the efficiency or pulp property development in LC refining. The process with a combination of DD chip refining and LC refining had the highest energy efficiency (tensile index at certain specific energy consumption). All processes with LC refining produced pulp with somewhat lower light scattering and fiber length than did the corresponding system with only HC refining. Thus, for printing papers, the best combination was LC refining with DD chip refining. LC refiners seem to have a narrow range in specific energy for maximum energy efficiency and a good balance between tensile index increase and fiber length reduction. Much higher specific energy was applied on reject pulp. However, the reject share was only around 30%. The LC refining specific energy, based on main line production, was around 80 kWh/air-dried metric ton (a.d. metric ton), whereas up to 180 kWh/a.d. metric ton was applied in main line.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-31894 (URN)000411860500005 ()2-s2.0-85026809547 (Scopus ID)
Available from: 2017-10-18 Created: 2017-10-18 Last updated: 2017-11-29Bibliographically approved
Sandberg, C., Berg, J.-E. & Engstrand, P. (2017). Mill evaluation of an intensified mechanical pulping process. Nordic Pulp & Paper Research Journal, 32(2), 204-210
Open this publication in new window or tab >>Mill evaluation of an intensified mechanical pulping process
2017 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 2, p. 204-210Article in journal (Refereed) Published
Abstract [en]

Mill-scale demonstration of a process concept inspired by Process Intensification (PI) principles was performed in Holmen Paper Braviken mill, Norrkoping, Sweden. The intensified process consists of wood softening by means of chip pretreatment with sodium sulphite, high intensity refining followed by low consistency refining. This process yields very low shives content and thus the unit operations screening and reject refining can be eliminated and the pulp is fed directly to the paper machine. Thorough evaluation of key paper-and print quality data showed that it is possible to produce pulp for newsprint at 1500 kWh/adt total specific energy (including auxiliary drives such as pumps, screw feeders, etc.). The total specific energy consumption was 900 kWh/adt lower compared to the normal process used for newsprint in Braviken, and 500 kWh/adt lower compared to today's best available technology. The auxiliary equipment energy demand was 120 kWh/adt, which was less than half of that of the reference TMP line. The PIinspired process reduces the number of machines drastically compared to a conventional TMP line, as well as the number of pumps, chests and other auxiliary equipment.

Keywords
Chip pre-treatment, Double disc refining, Energy efficiency, High intensity, Low-consistency refining, Mechanical pulping, Process control, Process intensification, TMP
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-31366 (URN)10.3183/NPPRJ-2017-32-02-p204-210 (DOI)000405197000006 ()2-s2.0-85052714078 (Scopus ID)
Available from: 2017-08-10 Created: 2017-08-10 Last updated: 2018-10-03Bibliographically approved
Sandberg, C., Berg, J.-E. & Engstrand, P. (2017). Process intensification in mechanical pulping. Nordic Pulp & Paper Research Journal, 32(4), 615-622
Open this publication in new window or tab >>Process intensification in mechanical pulping
2017 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 32, no 4, p. 615-622Article in journal (Refereed) Published
Abstract [en]

Process intensification is a term used in the chemical process industry for major improvements in the process design leading to radical changes in process complexity, equipment size and efficiency. We suggest that a similar approach is applied in the pulp and paper industry. We have focused on the production of mechanical pulp, but a similar approach can be applied to other areas within the pulp and paper industry. Inspired by process intensification methodology, we suggest five principles for development of the mechanical pulping process. Three fundamental principles; 1. Break up the wood and fibre wall structure in the right positions. 2. Give each fibre, of certain morphology, the same processing experience. 3. Optimize the applied mechanical forces and the physiochemical state of the wood and fibre material.  and two system oriented principles; 1. Select wood raw material based on final product specifications. 2. Design the process to facilitate observability, controllability and maintenance. Implications of these principles on process design and future challenges for mechanical pulping are discussed.

Keywords
Energy efficiency, High intensity, Low consistency refining, Mechanical pulping, Process control, Process intensification, Softening, TMP
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:miun:diva-32571 (URN)10.3183/NPPRJ-2017-32-04-p615-622 (DOI)000418122100012 ()2-s2.0-85052688960 (Scopus ID)
Projects
e2mp, energy efficient mechanical pulping
Funder
Knowledge Foundation, 20100281Swedish Energy Agency, 32326-1
Available from: 2017-12-21 Created: 2017-12-21 Last updated: 2018-10-03Bibliographically approved
Gradin, P., Berg, J.-E. & Nyström, S. (2016). Measuring Tangential Forces in a Pulp Refiner: A Novel Approach. Experimental techniques (Westport, Conn.), 40(2), 789-793
Open this publication in new window or tab >>Measuring Tangential Forces in a Pulp Refiner: A Novel Approach
2016 (English)In: Experimental techniques (Westport, Conn.), ISSN 0732-8818, E-ISSN 1747-1567, Vol. 40, no 2, p. 789-793Article in journal (Refereed) Published
Abstract [en]

To get some insight into the processes that are active during the refining of wood, the tangential force distribution in the plate gap is of interest. Over the years several designs of force sensors have been developed for this purpose. One drawback with these designs is that each sensormeasures forces over quite a small area such that in order to cover the whole disc with a reasonably good resolution, many sensors have to be used. Also, there are problems to protect the active parts of the sensors from the harsh environment in the plate gap. In this paper a different concept is presented, in that the sensor is continuous and consists of a hollow radial bar equipped with strain gages on the inside. The force sensor was calibrated before mounting by loading it with a known load in the tangential direction and in different positions while measuring the strains in the points where the gages are located. This makes it possible to determine the so-called influence (or Green) functions. Knowing these it is possible to determine the tangential force distribution from strain values measured during operation of the refiner. Guidelines for doing this are presented together with a detailed description of the load sensor and some experimental results.

Keywords
Pulp Refining, Plate Gap, Force Sensor, Refiner Disc, Strain Gages
National Category
Applied Mechanics
Identifiers
urn:nbn:se:miun:diva-23849 (URN)10.1007/s40799-016-0079-8 (DOI)000384752900031 ()2-s2.0-84969722092 (Scopus ID)
Projects
Filling the gap
Funder
Swedish Energy AgencyVINNOVA
Available from: 2014-12-17 Created: 2014-12-17 Last updated: 2017-12-05Bibliographically approved
Sandberg, C., Engstrand, P. & Berg, J.-E. (2016). System Aspects on Low Consistency Refining of Mechanical Pulp. In: TAPPI 2016 International Mechanical Pulping Conference (IMPC): . Paper presented at 2016 International Mechanical Pulping Conference (IMPC), September 26 -28, 2016, Jacksonville, US (pp. 485-495). TAPPI Press, 1
Open this publication in new window or tab >>System Aspects on Low Consistency Refining of Mechanical Pulp
2016 (English)In: TAPPI 2016 International Mechanical Pulping Conference (IMPC), TAPPI Press, 2016, Vol. 1, p. 485-495Conference paper, Published paper (Refereed)
Abstract [en]

Several combinations of high consistency (HC) and low consistency (LC) refiners were evaluated both in main line and reject line for production of pulp for printing papers. HC-LC processes were compared with processes with only HC refining. Processes with two different types of chip refiners were studied – single disc (SD) and double disc (DD). All process combinations were evaluated during continuous production in the Holmen Paper Braviken mill, Sweden. The purpose of this work was to evaluate energy efficiency and pulp quality for the processes.

LC refining was more energy efficient than HC refining for certain tensile index increase in all evaluated combinations. The highest energy efficiency was attained when LC refining was utilized in main line, but the difference was small compared to application on reject. Much higher specific energy was applied on reject pulp, but since the reject share was only around 30%, the LC refining specific energy, based on main line production, was around 80 kWh/air dry ton (adt) whereas up to 180 kWh/adt was applied in main line.

The combination of DD chip refining and LC refining had the highest energy efficiency (tensile index at certain specific energy consumption) and produced pulp with somewhat lower fibre length but higher light scattering and lower shives content compared to a line with only SD HC refining. Thus, for printing papers it seems beneficial to combine LC refining with high intensity HC chip refining. All processes with LC refining had lower light scattering and fibre length compared to the corresponding system with only HC refining.

Place, publisher, year, edition, pages
TAPPI Press, 2016
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-29540 (URN)2-s2.0-85006494192 (Scopus ID)978-151083073-8 (ISBN)
Conference
2016 International Mechanical Pulping Conference (IMPC), September 26 -28, 2016, Jacksonville, US
Projects
e2mp
Funder
Swedish Energy Agency, 32326-1Knowledge Foundation, 20100281
Available from: 2016-12-13 Created: 2016-12-13 Last updated: 2017-01-09Bibliographically approved
Sandberg, C. & Berg, J.-E. (2015). Effect of flow recirculation on pulp quality and energy efficiency in low consistency refining of mechanical pulp. Nordic Pulp & Paper Research Journal, 30(2), 230-233
Open this publication in new window or tab >>Effect of flow recirculation on pulp quality and energy efficiency in low consistency refining of mechanical pulp
2015 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 2, p. 230-233Article in journal (Refereed) Published
Abstract [en]

The effect of pulp flow recirculation on energy efficiency and pulp properties development in low consistency refining of TMP has been studied. Trials were made with TwinFlo 58 refiners in two mills in Sweden. The refiners were operated at constant specific refining energy but different flow conditions. No effect of recirculation was seen on refining energy efficiency, pulp quality or fibre wall delamination/internal fibrillation. At high degree of recirculation though, a somewhat larger fibre length reduction was seen. This means that a large degree of recirculation can be used to attain a high specific energy in one stage low consistency refining, without significant negative effects on fibre properties. If a high specific energy input is desirable, it is more cost effective to install one large refiner with recirculation compared to several small without recirculation in series. When recirculation was increased by means of increased flow through the refiner, the outlet pressure dropped. The lower pressure drop over the refiner probably decreased the internal recirculation between rotor and stator, which could explain the observation that there was little effect on fibre development by recirculation. This means that at certain conditions the distribution in fibre treatment might not increase so much when the outer recirculation is increased, since the internal recirculation might be reduced simultaneously.

Keywords
Low consistency refining, Flow recirculation, Fibre properties, Energy efficiency, Mechanical pulping, TMP
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-25691 (URN)000354806700007 ()2-s2.0-84951927913 (Scopus ID)
Available from: 2015-08-24 Created: 2015-08-18 Last updated: 2017-08-10Bibliographically approved
Berg, J.-E., Sandberg, C., Engberg, B. A. & Engstrand, P. (2015). Low-consistency refining of mechanical pulp in the light of forces on fibres. Nordic Pulp & Paper Research Journal, 30(2), 225-229
Open this publication in new window or tab >>Low-consistency refining of mechanical pulp in the light of forces on fibres
2015 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 2, p. 225-229Article in journal (Refereed) Published
Abstract [en]

The aim of this investigation was to find new approaches to evaluate the performance of low-consistency refiners. Data from a paper mill producing TMP from Norway spruce was used in order to find a possible way to calculate the power split between the zones in a TwinFlo refiner. An assumption of equal amount of fibres captured between overlapping bars was found successful in order to develop equations for the power split. The equations predicted equal power in both zones at equal disc gaps. The power was found to increase approximately linearly with decreasing disc gap over the range, 0.1-0.2 mm. The power split was essential to know for calculating refining intensities expressed as specific edge load and forces on fibres in the two zones. The reduction in fibre length was about 5% at 0.17 mm disc gap or at 0.03 N forces on fibres or at 0.7 J/m specific edge load. Disc gap, forces on fibres and specific edge load was found to predict fibre shortening approximately equally upon changes in power and flow rate through the refiner.

Keywords
Low consistency, Two-zoned refiners, Fibre length, Refining intensity, Disc gap, Specific edge load, Forces on fibres, Thermomechanical pulping
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-25656 (URN)10.3183/NPPRJ-2015-30-02-p225-229 (DOI)000354806700006 ()2-s2.0-84951952932 (Scopus ID)
Available from: 2015-08-28 Created: 2015-08-18 Last updated: 2017-08-10Bibliographically approved
Organisations

Search in DiVA

Show all publications