Estimation of dewatering intensity of the paper web in the wet part of paper machine
and selection of alternative additives to improve dewatering intensity 2009
2
Table of content ................................................................................................................... 2
Preface .................................................................................................................................. 4
Summary .............................................................................................................................. 5
Objectives and scope of the thesis ...................................................................................... 6
1. Theoretical introduction ....................................................................................... 7
1.1. General information and definitions concerning papermaking process,
construction of paper machine and basic functions of its elements ........................ 7
1.1.1. Pulp preparation ............................................................................................ 7
1.1.2. Stock and water systems of paper machine .................................................. 8
1.1.2.1. Stock preparation ............................................................................. 9
1.1.2.2. Stock approach flow system ............................................................. 14
1.1.2.3. Short and long circulation systems ................................................... 14
1.1.3. Wet part of paper machine ............................................................................ 15
1.1.4. Press section of paper machine .................................................................... 20
1.1.5. Dry part of paper machine............................................................................. 23
1.2. Classification and characteristic of water contained in formed paper web ............. 25
1.3. Intensity of paper web dewatering and energy consumption
in conventional paper making process .................................................................... 33
1.4. Dewatering phenomenon ........................................................................................ 39
1.4.1. Mechanisms of dewatering ........................................................................... 39
1.4.2.1. Kozeny-Carman equation ................................................................. 40
1.4.2.2. Hydrodynamic specific surface area assessment .............................. 42
1.4.3. Factors affecting drainage intensity .............................................................. 48
1.4.3.1. Stock preparation ............................................................................. 49
1.4.3.2. Initial solid content and fiber alignment .......................................... 49
1.4.3.3. Stock temperature ............................................................................ 50
1.4.3.4. Permeability of pulp fiber mat ......................................................... 51
1.4.3.5. Fines content .................................................................................... 52
1.4.3.6. Fiber flexibility ................................................................................ 54
1.4.4.7. Retention aids .................................................................................. 56
2. Research phase ...................................................................................................... 59
2.1. Characteristic of raw materials and alternative materials used ............................... 59
2.2. Microscopic pictures ............................................................................................... 62
2.3. Pulp preparation ...................................................................................................... 66
2.4. Methodology of analysis ......................................................................................... 67
2.4.1. Methods of pulp dewatering analysis ............................................................ 67
2.4.1.1. Schopper-Riegler freeness ................................................................ 69
2.4.1.2. Water retention value ........................................................................ 70
2.4.1.3. Rapid-Kthen number ...................................................................... 71
2.4.1.4. Hydrodynamic specific surface area ................................................. 72
2.4.1.5. FiberXPress....................................................................................... 74
2.4.2. Methods of paper sheet properties analysis .................................................. 77
3. Results and discussion .......................................................................................... 79
3.1. The influence of addition of alternative materials on pulp dewatering .................. 79
3.1.1. Dewatering in the wire section ...................................................................... 79
3.1.2. Dewatering in the press section..................................................................... 84
3.2. The influence of addition of alternative materials on paper sheet properties .........
4. Conclusions ............................................................................................................ 157
Estimation of dewatering intensity of the paper web in the wet part of paper machine
and selection of alternative additives to improve dewatering intensity 2009
4
Preface
The main objective of this thesis is to assess factors affecting dewatering behavior of the
paper web in the wet part of paper machine with a clear focus on the influence and the role of
additives and fibers, and to search for alternative bio-based additives that can reduce the
required drying energy without negatively affecting of paper quality. The aim is to elucidate
the balance between dewatering and water retention value of different raw materials and
additives used during paper production in relation to paper quality. This thesis contains
description of researches carried out in order to find out what is the effect of the addition of
bio-based additives in different ratios on pulp dewatering properties, water retention value and
paper properties. Within Thesis the comparison of influence of additives was done and also
comparison of different dewatering methods used was performed.
Researches were carried out using wide range of dewatering apparatus available, inter
alia, at Institute of Papermaking and Printing at the Technical University of Lodz in Poland
and also abroad.
Hydrodynamic specific surface area measurements were performed according to
Dresden method with usage of the unique analyser, placed in Germany, at Dresden University
of Technology, at Faculty of Mechanical Engineering, Professorship of Paper Technology.
This cooperation was possible within European Union program called Short Term Scientific
Mission during COST E54 Action with title: Characterization of the fine structure and
properties of papermaking fibres using new technologies.
Investigations in participating paper mills were carried out with coordination of Centre
of Competence Paper and Board, the Netherlands, and cooperation with experts from paper
mills. Analysis was also performed in the laboratory of Smurfit Kappa Roermond Papier
B.V. in Roermond with the usage of new FiberXPress device, invented and developed by
Voith and Smurfit Kappa.
This thesis has been based on a part of a larger project performed in the framework of
the projects: Briljant, Susprise Green biorefinery, Biorefinery program of Energy
Transition as well as the Fibre Raw Material program of KCPK in pulp and paper industry.
Coordination of the project is performed by Centre of Competence Paper and Board, the
Netherlands with the cooperation from Institute of Papermaking and Printing.
