INTRODUCING A NEW DECISION TOOL USING MPC FOR THE PRODUCTION LINE EVOLUTION

The decision tool presented in this paper links management decisions to production optimization. It identifies the possible lacks of flexibility (physical limitations) and/or agility (unsuitable dynamics) of either product, process or production parameters (PPP) in a production environment that is under the influence of some global turbulence factors and for which profitability objectives have to be maintained. If need be, a particular evolution scenario could be proposed to maintain strategic level targets. In this context, flexibility and agility act as performance measures and quantitative definitions using DCS (Distributed Control System) data are proposed in the paper. A description of the strategy’s implementation, which uses Model Predictive Control (MPC), and some results are presented.

ON-LINE DETERMINATION OF GREEN-LIQUOR REDUCTION EFFICIENCY AND TOTAL TITRATABLE ALKALI USING FOURIER-TRANSFORM-NIR SPECTROMETRY

Precoat and Topcoat Effect on the Final Printability – Part 1: Using mercury intrusion to analyse the Coating structure

D. Matte, Centre International de Couchage (CIC), Trois-Rivières, QC,, A. Dimmick, Bethlehem, PA, USA, P. Mangin, Centre Intégré en Pâtes et Papiers, Trois-Rivières, QC, C. Daneault, Canada Research Chair in Value-added Paper, Trois-Rivières, QC

Mercury intrusion testing is a well established tool, and has been used extensively within the industry to give a great deal of information to the papermaker about the paper and coating structure.  The test has been invaluable in predicting or troubleshooting many areas such as blister resistance and printing issues.  However, results can vary widely depending on the choice of materials (pigments or binder) used in different formulations.  The main goal of this paper is to explain how to achieve a good analysis of mercury intrusion by good manipulations of the data for double-coated paper. 

It is important to define the point in the data collected where the pore diameter is representative of the area located around the low and high mercury pressure and thus eliminate the occlusion and/or defects effects.  An explanation of the way to identify the point of separation between the coating layers and the base paper and between the pre-coat and top coat together is also provided.  The hexadecane method and the correction (performed with blank correction option) in the Autopore™ program from Micromeritics can be used to achieve these results.  An example of the correction for mercury intrusion method used is also shown using data from a study done for a doctorate begin at University of Québec à Trois-Rivières.

Modeling the Effect of Plate Age on the Operation of TMP-Refiners

The inherently interactive nature of the TMP refining processes is one of the most important sources of variability in TMP quality, and the operation of TMP-refiners is directly affected by the condition of the refiner plates. Although in the past two decades much work has been done on the modeling of TMP-refiners, current models do not account explicitly for the effect of plate age on refiner operation and pulp quality. In this work, a methodology is presented for the prediction of motor load changes over the longer-term due to plate age, using real-time data from plant operations and steady state identification techniques. The resulting model is coupled with a pulp quality predictor to study different refining conditions. The model predicts long-term drifts in pulp quality in addition to providing insight on the effect of total specific energy, refining intensity, power split, and plate age on the refining operation. Finally, the model is used to determine optimal policies for TMP-refiner operation as plates wear.

Pretreatment of Over-Dry Grey-Stage Lodgepole Pine Chips

Enhancing Papermaking Properties of Secondary Fibres by Tempo-Mediated Oxidation

A bleached virgin hardwood kraft pulp was refined and recycled one time in laboratory. Recycled samples were then oxidized using TEMPO (4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl radical), sodium bromide and sodium hypochlorite, with variation of the latter’s concentration on each sample. Results showed that all papermaking properties, particularly the tear index, were significantly improved at low NaOCl concentrations. At higher NaOCl charges the burst and tensile indices suffered little decrease, while the tear was strongly reduced.

Factors affecting Chloride and Potassium Removal Efficiency of a Recovery Boiler Precipitator Ash Treatment System

A laboratory study was performed to examine the main factors affecting the removal efficiency of chloride (Cl) and potassium (K) of ash treatment systems operated at a temperature between 60 and 100^oC. The results show that the removal efficiency is directly proportional to the amounts of Cl and K in the liquid that have been separated from the ash-water slurry. For a given system, the Cl and K removal efficiency is determined by the concentration of Cl and K in the liquid and by the Degree of solid-liquid Separation (DS). DS, in turn, is greatly affected by the ash concentration in the slurry and the CO₃ content of the ash.