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Papers by Jaroslav Stavik

Research paper thumbnail of Silica Removal of Oil Palm Empty Fruit Bunch Fiber

International Journal of Technology, Feb 5, 2024

Research paper thumbnail of Differences of Chemical and Physical Properties on Fractionated Dissolving Pulp During Alkalizing and Aging Process

International Journal of Technology, Feb 5, 2024

Research paper thumbnail of Měření náboje v dielektrických vrstvách

Research paper thumbnail of Kapacitní měření na strukturách fotovoltaických solárních článků

Research paper thumbnail of Cellulose (Dissolving Pulp) Manufacturing Processes and Properties: A Mini-Review

DOAJ (DOAJ: Directory of Open Access Journals), Mar 1, 2016

The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to ... more The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to a significant development of dissolving pulps in the last decade. In this review paper, the current status of dissolving pulp with respects to raw materials, manufacturing processes, and some key issues are discussed. Non-wood materials and the process concept of upgrading paper-grade pulp into dissolving pulp are also included. Some recent developments related to the analytical methods of the purity and molecular weight distribution based on the ion chromatography and gel permeation chromatography are discussed. Finally, further processing improvements of purification, such as mechanical, chemical, and enzymatic treatment, and their combinations during the manufacturing process of dissolving pulp, are included.

Research paper thumbnail of Pipeline Flooding, Dewatering and Venting

Flooding, cleaning, gauging, dewatering and venting of offshore oil and gas pipelines during prec... more Flooding, cleaning, gauging, dewatering and venting of offshore oil and gas pipelines during precommissioning involves pipeline pigging and expensive deployment vessel time. To aid in the planning of such operations, a number of analyses can be undertaken to determine the duration to perform each of these tasks. The mathematical models can also optimise the equipment required (hoses, pumps, compressors). Problems that could be encountered without a clear knowledge of how the operation will proceed can be avoided. The operation can be monitored by comparing recorded and predicted values, for example inlet pressure. This paper provides an overview of work performed to establish pig velocity, inlet pressure and pigging duration during various precommissioning tasks.

Research paper thumbnail of Applications of enzymatic technologies to the production of high-quality dissolving pulp: A Review

Bioresource Technology

Recently, the worldwide production of dissolving pulp has grown rapidly. Enzymatic technologies p... more Recently, the worldwide production of dissolving pulp has grown rapidly. Enzymatic technologies play an important role in producing high-quality dissolving pulp, due to their green, mild conditions, high specificity and efficiency. In this review, the relevant publications regarding enzyme applications for dissolving pulp are summarized. Cellulase and xylanase are two major enzymes used for this purpose. Cellulase can improve the quality of dissolving pulp, such as improving the reactivity/accessibility, controlling the intrinsic viscosity and adjusting the molecular weight. Xylanase is mainly used to increase the purity of the dissolving pulp and improve the pulp brightness. Furthermore, in order to increase the enzymatic treatment efficiency, the enzymatic technology can be combined with other techniques, including mechanical refining, fiber fractionations, alkali treatment and use of additives. The advantages, disadvantages and practical implications are analyzed. Also, the potential of other enzymes (such as laccase, mannanase) are discussed.

Research paper thumbnail of Managing total reduced sulfur emissions at a Canadian kraft pulp mill

April 2016

This study addresses the challenges a dissolving-grade pulp mill in Canada faced in 2014 in meeti... more This study addresses the challenges a dissolving-grade pulp mill in Canada faced in 2014 in meeting its total reduced sulfur (TRS) gas emission limit. These emissions from the recovery boiler exit are controlled by passing the boiler exit gas through a TRS scrubber system. The mill employs a cyclonic direct contact evaporator to concentrate black liquor to firing solids content. The off-gases from the direct contact evaporator flow to the effluent gas control system that consists of a venturi scrubber, a packed bed scrubber, and a heat recovery unit. Emissions of TRS greater than the regulated limit of 15 ppm were observed for a 4-month period in 2014. The level of emissions measured during this period was significantly higher than about 12 ppm, the expected average value based on historic experience. The problem persisted from mid-June 2014 until the annual mill shutdown in October 2014. The main TRS components detected and the performance of the Teller scrubber in capturing them a...

Research paper thumbnail of Utilisation De Cellulase Pour Améliorer La Régulation De La Viscosité De Pâte À Dissoudre

Research paper thumbnail of Regenerated cellulose by the Lyocell process, a brief review of the process and properties

BioResources

Lyocell fiber has emerged as an important class of regenerated cellulose that is produced based o... more Lyocell fiber has emerged as an important class of regenerated cellulose that is produced based on the N-methyl morpholine-N-oxide (NMMO) dissolution method, and it has unique properties compared to viscose fiber. The NMMO technology provides a simple, resource-conserving, and environmentally friendly method for producing regenerated cellulose fiber. In this paper, the manufacturing process, environmental impact, and product quality of lyocell fiber are reviewed and compared with those of the conventional viscose fiber.

Research paper thumbnail of Cellulose (dissolving pulp) manufacturing processes and properties: A mini-review

BioResources

The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to ... more The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to a significant development of dissolving pulps in the last decade. In this review paper, the current status of dissolving pulp with respects to raw materials, manufacturing processes, and some key issues are discussed. Non-wood materials and the process concept of upgrading paper-grade pulp into dissolving pulp are also included. Some recent developments related to the analytical methods of the purity and molecular weight distribution based on the ion chromatography and gel permeation chromatography are discussed. Finally, further processing improvements of purification, such as mechanical, chemical, and enzymatic treatment, and their combinations during the manufacturing process of dissolving pulp, are included.

Research paper thumbnail of Comparison of acid sulfite (AS)- and prehydrolysis kraft (PHK)-based dissolving pulps

Research paper thumbnail of Silica Removal of Oil Palm Empty Fruit Bunch Fiber

International Journal of Technology, Feb 5, 2024

Research paper thumbnail of Differences of Chemical and Physical Properties on Fractionated Dissolving Pulp During Alkalizing and Aging Process

International Journal of Technology, Feb 5, 2024

Research paper thumbnail of Měření náboje v dielektrických vrstvách

Research paper thumbnail of Kapacitní měření na strukturách fotovoltaických solárních článků

Research paper thumbnail of Cellulose (Dissolving Pulp) Manufacturing Processes and Properties: A Mini-Review

DOAJ (DOAJ: Directory of Open Access Journals), Mar 1, 2016

The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to ... more The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to a significant development of dissolving pulps in the last decade. In this review paper, the current status of dissolving pulp with respects to raw materials, manufacturing processes, and some key issues are discussed. Non-wood materials and the process concept of upgrading paper-grade pulp into dissolving pulp are also included. Some recent developments related to the analytical methods of the purity and molecular weight distribution based on the ion chromatography and gel permeation chromatography are discussed. Finally, further processing improvements of purification, such as mechanical, chemical, and enzymatic treatment, and their combinations during the manufacturing process of dissolving pulp, are included.

Research paper thumbnail of Pipeline Flooding, Dewatering and Venting

Flooding, cleaning, gauging, dewatering and venting of offshore oil and gas pipelines during prec... more Flooding, cleaning, gauging, dewatering and venting of offshore oil and gas pipelines during precommissioning involves pipeline pigging and expensive deployment vessel time. To aid in the planning of such operations, a number of analyses can be undertaken to determine the duration to perform each of these tasks. The mathematical models can also optimise the equipment required (hoses, pumps, compressors). Problems that could be encountered without a clear knowledge of how the operation will proceed can be avoided. The operation can be monitored by comparing recorded and predicted values, for example inlet pressure. This paper provides an overview of work performed to establish pig velocity, inlet pressure and pigging duration during various precommissioning tasks.

Research paper thumbnail of Applications of enzymatic technologies to the production of high-quality dissolving pulp: A Review

Bioresource Technology

Recently, the worldwide production of dissolving pulp has grown rapidly. Enzymatic technologies p... more Recently, the worldwide production of dissolving pulp has grown rapidly. Enzymatic technologies play an important role in producing high-quality dissolving pulp, due to their green, mild conditions, high specificity and efficiency. In this review, the relevant publications regarding enzyme applications for dissolving pulp are summarized. Cellulase and xylanase are two major enzymes used for this purpose. Cellulase can improve the quality of dissolving pulp, such as improving the reactivity/accessibility, controlling the intrinsic viscosity and adjusting the molecular weight. Xylanase is mainly used to increase the purity of the dissolving pulp and improve the pulp brightness. Furthermore, in order to increase the enzymatic treatment efficiency, the enzymatic technology can be combined with other techniques, including mechanical refining, fiber fractionations, alkali treatment and use of additives. The advantages, disadvantages and practical implications are analyzed. Also, the potential of other enzymes (such as laccase, mannanase) are discussed.

Research paper thumbnail of Managing total reduced sulfur emissions at a Canadian kraft pulp mill

April 2016

This study addresses the challenges a dissolving-grade pulp mill in Canada faced in 2014 in meeti... more This study addresses the challenges a dissolving-grade pulp mill in Canada faced in 2014 in meeting its total reduced sulfur (TRS) gas emission limit. These emissions from the recovery boiler exit are controlled by passing the boiler exit gas through a TRS scrubber system. The mill employs a cyclonic direct contact evaporator to concentrate black liquor to firing solids content. The off-gases from the direct contact evaporator flow to the effluent gas control system that consists of a venturi scrubber, a packed bed scrubber, and a heat recovery unit. Emissions of TRS greater than the regulated limit of 15 ppm were observed for a 4-month period in 2014. The level of emissions measured during this period was significantly higher than about 12 ppm, the expected average value based on historic experience. The problem persisted from mid-June 2014 until the annual mill shutdown in October 2014. The main TRS components detected and the performance of the Teller scrubber in capturing them a...

Research paper thumbnail of Utilisation De Cellulase Pour Améliorer La Régulation De La Viscosité De Pâte À Dissoudre

Research paper thumbnail of Regenerated cellulose by the Lyocell process, a brief review of the process and properties

BioResources

Lyocell fiber has emerged as an important class of regenerated cellulose that is produced based o... more Lyocell fiber has emerged as an important class of regenerated cellulose that is produced based on the N-methyl morpholine-N-oxide (NMMO) dissolution method, and it has unique properties compared to viscose fiber. The NMMO technology provides a simple, resource-conserving, and environmentally friendly method for producing regenerated cellulose fiber. In this paper, the manufacturing process, environmental impact, and product quality of lyocell fiber are reviewed and compared with those of the conventional viscose fiber.

Research paper thumbnail of Cellulose (dissolving pulp) manufacturing processes and properties: A mini-review

BioResources

The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to ... more The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to a significant development of dissolving pulps in the last decade. In this review paper, the current status of dissolving pulp with respects to raw materials, manufacturing processes, and some key issues are discussed. Non-wood materials and the process concept of upgrading paper-grade pulp into dissolving pulp are also included. Some recent developments related to the analytical methods of the purity and molecular weight distribution based on the ion chromatography and gel permeation chromatography are discussed. Finally, further processing improvements of purification, such as mechanical, chemical, and enzymatic treatment, and their combinations during the manufacturing process of dissolving pulp, are included.

Research paper thumbnail of Comparison of acid sulfite (AS)- and prehydrolysis kraft (PHK)-based dissolving pulps