Thesis (Ph. D.)--Institute of Paper Chemistry, 1954. / Bibliography: leaves 108-109.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1981. / Bibliography: leaves 80-83.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1940. / Bibliography: leaves 98-100.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1939. / Bibliography: leaves 151-156.

Thesis (Ph. D.)--Institute of Paper Science and Technology, 1990. / Bibliography: leaves 125-128.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1941. / Bibliography: leaves 64-65.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1982. / Bibliography: leaves 77-81.

Ο πρωταρχικός στόχος αυτής της εργασίας είναι να μελετηθεί η υποδιαδικασία κατά την παραγωγή χαρτιού, γνώστη και ως πολτοποίηση. Η πολτοποίηση αφορά το στάδιο οπού το πριονίδι, παρουσία νερού περνά μέσα από τον πολτοποιητή ο οποίος αποτελείται από δύο πιάτα που περιστρέφονται με αντίθετη φορά, το πριονίδι διαλύεται και μαζί με το νερό δημιουργούν το μίγμα του χαρτοπολτού. Η εν λόγω διαδικασία χαρακτηρίζεται από υψηλή πολυπλοκότητα λόγω της δυσκολίας που παρουσιάζει στη μαθηματική μοντελοποίηση. Σε αυτή την εργασία, εξετάζονται ήδη υπάρχουσες προσεγγίσεις στο θέμα της μοντελοποίησης. Διαφορετικές προσεγγίσεις πάνω στη μοντελοποίηση εχουν γίνει τα τελευταία χρόνια από τους μηχανικούς, υπό την έννοια οτι χρησιμοποιήθηκαν διαφορετικές μεταβλητές ως έξοδοι και ως είσοδοι και πληθώρα μεθόδων μοντελοποίησης. Τα σημαντικότερα μοντέλα ανοιχτού βρόχου που βρεθήκαν στη βιβλιογραφία εξομοιώνονται και τα χαρακτηριστικά τους αναλύονται. Ο στόχος της εργασίας είναι να καθοριστεί αν οι προαναφερθείσες μοντελοποιήσεις μπορούν να ελεγχθούν με επιτυχία μέσω ενός Model Predictive Controller (MPC). Εκτεταμένες προσομοιώσεις πραγματοποιούνται όπου οι παράμετροι του ελεγκτή εξετάζονται λεπτομέρως ώστε να διαπιστωθεί το αντίκτυπο τους στην όλη διαδικασία. Προκειμένου να εξεταστεί η αποδοτικότητα του ελεγκτή, δεδομένα τα οποία πάρθηκαν από πραγματική βιομηχανία συγκρίνονται με αυτά του MPC τα οποία παράχθηκαν μέσω του MATLAB. / The initial objective of this diploma thesis is to investigate and examine the papermaking’s sub-process also known as pulping. Pulping concerns the stage where wood chip along with water is being passed through a refiner that consists of two counter rotating discs, woodchip is being smashed and with the presence of water the pulp mixture is being created. This process is being characterized as highly complex because of the difficulties that appear in its mathematical modeling. In this thesis, the existing modeling approaches developed for the pulp and paper refining process are also being investigated. Different approaches have been developed towards the modeling of the process during the past years, where engineers utilized different controlled and manipulated variables as well as a variety of modeling methods. The most important pulp and paper refiner open-loop model approximations, extracted from the existing related literature, are being simulated and their characteristics are being examined in detail. This work’s main and final objective is to determine if the aforementioned modeling approaches of the pulp and paper refining process can be successfully controlled via a Model Predictive Control (MPC) based structure. Extensive simulation trials are being carried out, where the MPC parameters are being investigated in detail regarding their effect on the overall control performance of the pulp and paper refining process. In order to further evaluate the efficacy of the proposed control scheme, the MPC related results are being compared to experimental data extracted from a real refining system that utilizes a generic industrial controller.

The stability of hydrogen peroxide (H2O2) is a critical factor for the brightening of mechanical pulps. Inorganic ions, including Fe, Mn and Cu catalytically decompose H2O2. These troublesome metals promote the rapid transformation of H2O2 to nonselective hydroxyl radicals that degrade the cellulose fibres and decrease yields. / The interaction of aqueous metal•complexes with magnesium metal (Mg°) or bimetallic mixtures of magnesium with either palladium (Pd°/Mg°) or silver (Ag°/Mg°) were optimized to remove metals (Mn, Cu and Fe) from solution with concomitant release of the complexing reagent. The analyte metals were removed by both cementation on the surfaces of the excess Mg° and by precipitation as hydroxides. Overall, the reactions were rapid (3 or 10 min) and very efficient. The accelerators (Ag or Pd) were deposited on the surfaces of the Mg°. In a separate study, the excess of Mg° could be reused to mediate more metals removal without apparent loss of reactivity. Among the other iminodiacetate analogs (CDTA, MEDTA, EGTA, HEDTA, DPTA and MTBE), the EGTA and HEDTA proved to be possible substitutes for both efficient metal removal of Mn, Cu and Fe from solution and efficient release of chelating reagent. The measurement of particle size, performed by laser granulometry, demonstrated that smaller particles of precipitate were generated from metal-EDTA complexes by reaction with NaOH than by reaction with Pd°/Mg° bimetallic mixture. If the suspensions of particles were analyzed in the absence of ultrasound, the particles became aggregated into large flocs (up to 150 mum3 ). The reactivity of the bimetallic mixtures was exploited to remove Cu, Mn, Fe, Zn and Al that had been initially chelated with EDTA or DTPA from a thermomechanical pulp (TMP). After 15 min, the metals had been removed efficiently with the bimetallic mixtures. The EDTA released from the TMP filtrate could be recycled efficiently for a total of three cycles. On the other hand, the DTPA was not released as efficiently. Measurements of turbidity and chemical oxygen demand (COD) indicated no appreciable difference between the pulp samples with either chelating reagent. Residual H2O2 and ISO brightness measurements indicated no apparent differences among pulps that had been treated wi

A piezo-ceramic sensor was developed to measure normal and tangential shear forces applied to a bar at one location in the refining zone of a Sunds Defibrator Conflo® JC-00 refiner. Testing was completed at the Pulp and Paper Research Institute of Canada in Vancouver. BC using CTMP pulp with a stock consistency of 3.15%. Distributions have been determined for peak normal and shear forces. peak coefficient of friction. shear work. and shear lead. These distributions were analysed to assess possible correlations with specific edge load. Force magnitudes were found to increase with an increase in specific edge load. The peak coefficient of friction was calculated that ranged from 0.13 to 0.16. Both the normal and shear force magnitudes varied by as much as a factor of 3, due to rotor out-of-tram of only 0.06 mm. These distributions could provide greater insight to the mechanisms responsible for fibre development in papermaking and thus "In Process" control of various refiner conditions.