Doldan J.,LATU |
Poukka O.,Oy Metsa Botnia Ab |
Salmenoja K.,Oy Metsa Botnia Ab |
Battegazzore M.,UPM Fray Bentos Mill |
And 2 more authors.
O Papel | Year: 2011
Modern pulp mills tend to apply cleaner and environment friendly processes generally by recycling and reusing various streams into the evaporation system and the reduction of discharges. This kind of closure leads to a build-up of non-process elements (NPEs) mainly in the chemical recovery system. Chemicals which accumulate in the mill cycles originate either from the wood raw material, process water and make-up chemicals. Natural purging places, generally referred as kidneys, are associated to the removal of these elements as green liquor dregs, grits or lime mud. The purpose of this study is to evaluate the routes of NPEs in a modern eucalyptus kraft pulp mill. An extensive sampling campaign was carried out at the studied mill. Samples were taken from all the main process streams to achieve an overall picture of the inputs, outputs, and enrichment in the mill. Complete mass balances were accordingly constructed for the entire mill. The results of this study can be utilized in the non-process element management at the mill and they serve as a good basic material for the further mill specific simulations.
Antonsson S.,KTH Royal Institute of Technology |
Pulkkinen I.,Aalto University |
Fiskari J.,Oy Metsa Botnia Ab |
Karlstrom K.,KTH Royal Institute of Technology |
And 2 more authors.
Appita Journal | Year: 2010
Hygroexpansion coefficient and tensile stiffness are important parameters in many paper applications. This study compares several bleached industrial hardwood kraft pulps, comprising five eucalypt pulps from South America, Europe, and Africa as well as an acacia pulp from Asia and a birch pulp from Scandinavia. Refined and unrefined pulps are compared. The results indicate significant differences in hygroexpansion but smaller differences in tensile stiffness index at comparable densities. No single factor offering a reasonable explanation of these differences in hygroexpansion coefficient, such as carbohydrate composition, fibre dimensions, or fibre form, was found. However, correlation between hygroexpansion coefficient and the mechano-sorptive creep stiffness was observed. We suggest that the hygroexpansion coefficient at a given tensile stiffness level can be used to rank pulps in terms of their mechano-sorptive creep properties.
Ruiz J.,Center Technique du Papier chFibres |
Eichorn S.,SGA Hygiene Products GmbH |
Bley L.,BTG |
Sabei H.,Oy Metsa Botnia Ab |
And 4 more authors.
ATIP. Association Technique de L'Industrie Papetiere | Year: 2010
In the manufacture of tissue, producers observe day to day that tissue softness is influenced by the pulp origin. Indeed, it's really relevant to analyse continuously the morphological characteristics of the fibres. Meanwhile, the softness potential, that means part of the final softness mainly due to the fibres used, can be calculated and exploited. This softness potential coming from the pulp is then more or less developed on the paper machine, depending on the operating conditions, including chemicals uses. After the Yankee cylinder, the structure of paper is fixed, and gives interesting information of the process actions. This structure is characterised with the TSSA device developed for the surface state analysis of the tissue. This paper explains how a robust and accurate softness measurement has been established and check on an industrial paper machine. An online fibres analyser was installed in a mill producing tissue with a conventional process. The pulp flow entering into the head-box is analysed continuously. The TSSA device has also been installed in this mill, analysing the surface of the tissue, just after the Yankee cylinder. Samples of tissue were taken, at the end of each reel, and manually assessed by tactile panel. A statistical model has been obtained allowing to predict the tissue softness. It combines both fibres and tissue surface characteristics. The correlation between the assessed softness and the objective value is about 94%.This on-line softness value is available allowing a continuous control of the ongoing production, instead of one subjective evaluation at the end of the reel, based on the assessments of the tactile panel.
Isoaho J.P.,University of Jyväskylä |
Tarkkanen S.,University of Jyväskylä |
Alen R.,University of Jyväskylä |
Fiskari J.,Oy Metsa Botnia Ab |
Fiskari J.,University of Helsinki
Nordic Pulp and Paper Research Journal | Year: 2012
Softwood-based kraft mill bleaching effluents from the initial bleaching stages D0 and E1 (the bleaching sequence being D0E1D 1E2D2) were treated by the oxidative Fenton method (H2O2-FeSO4) to decompose organic pollutants containing adsorbable organic halogens (AOX). Experiments designed using the Taguchi method were applied to predict the process conditions that would result in a cost-effective and adequate removal of AOX. In addition to the composition and concentration of the reagents (H2O2 and Fe2+), the main process parameters selected were temperature and reaction time, while pH was adjusted to an approximate value of 4 (the volumetric ratio of the mixed effluents D0:E1 was 3:2). The results indicated that an AOX removal of about 70% for this mixture (corresponding to about 50% for the mill) was achieved when the effluent samples were treated for 60 min at 70°C with H2O2 and Fe 2+ at a concentration of 1600 mg/l and 28 mg/l, respectively.
Ruiz J.,Centro Tecnico do Papel |
Sacon V.M.,Votorantim Celulose e Papel |
Silva F.P.,Votorantim Celulose e Papel |
Eichhorn S.,SCA Hygiene Products GmbH |
And 6 more authors.
O Papel | Year: 2010
A method for producing specific handsheets to assess the pulp potential softness for tissue manufacture was developed. A panel of people was formed and trained to evaluate the softness of tissue products and the softness of these handsheets. A protocol was designed for pulp softness assessment. 13 market bleached pulps - 7 eucalyptus, 3 softwoods, 2 hardwoods and 1 deinked pulp -, were studied for their softness potential before and after refining, according to the developed pro tocol. Ranking these pulps was possible and their softness assessment revealed important differences between the pulp grades, and according to refining. Hardwood pulps - and more particularly eucalyptus pulps -, produced the softest papers, whereas softwood pulps presented the lowest softness potential. Furthermore, the hardwood pulps lost less in softness potential during conventional refining than the softwood pulps. Their softness rating remained positive, whereas that of the softwood pulps always presented a negative value. A statistical model was developed for predicting pulp softness from the fibre characteristics. This model was proven sufficiently reliable and used to determine pulp softness potential, and then follow the softness through tissue manufacture, especially during the stock preparation and pulp refining. Finally, a comparison between the CTP - Centre Technique du Papier, France - panel results and those of four other panels was made, demonstrating that the five panels could evaluate softness in the same manner, and that the new protocol for assessing softness on specific handsheets was relevant for such an application.
Poykio R.,Valtakatu 26 |
Kivilinna V.-A.,Oy Metsa Botnia Ab |
Nurmesniemi H.,Stora Enso
Chemija | Year: 2010
Tis study presents the most recent data on Na and Ca concentrations in Scots pine (Pi-nus sylvestris L.) needles sampled in bioindicator surveys carried out in 2009 at Kemi (Northern Finland), as well as at Pietarsaari (Western Finland) in 2007, at Eno (Eastern Finland) in 1994-1996 and in the Jyväskylä region (Central Finland) in 2006, which are areas with operating pulp and paper mills. Na and Ca concentrations in Scots pine needles at Kemi varied within 7-280 mg/kg (d. w.) and 1 410-5 450 mg/kg (d. w.), respectively. Na concentrations in both C and C + 1 needles at Kemi in 2009 were in good agreement with the values of 31-105 mg/kg (d. w.) and 54-151 mg/kg (d. w.), respectively, observed at Eno. Ca concentrations in C + 1 needles at Kemi were in good agreement with the values of 2 432-5 598 mg/kg (d. w.) observed at Pietarsaari in 2007 and with the values of 2 700-7 900 mg/kg (d. w.) observed in the Jyväskylä region in 2006, although the highest Ca concentrations - 7 900 mg/kg (d. w.) - in the C + 1 needles in the latter area was obviously higher than the corresponding value of 5 450 mg/kg (d. w.) observed in our study at Kemi. © 2012 Lietuvos mokslu̧ akademija.
Ahvenlampi T.,University of Oulu |
Malmi T.,Oy Metsa Botnia Ab |
Liedes M.,Oy Metsa Botnia Ab |
Ikonen E.,University of Oulu
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2010
Energy efficiency is one of the main aspects in the Kraft pulping process. In Kraft pulping, the delignification of the pulp is mainly controlled by temperature and alkali. However, the quality is usually measured only in the blowline of the digester resulting in a control delay several hours. This affects to the quality control and also the energy efficiency of the plant. In this study, energy efficiency in the continuous Downflow Lo-Solids® cooking application is studied using model-based approach. Temperature and alkali controls are considered and some suggestions are proposed.
Long-term changes in the effluent loads from pulp and paper mills, the introduction of BAT technology, and their effects on extractable organic halogens concentrations in sediment in part of the Bothnian Bay
Nurmesniemi H.,Stora Enso |
Kivilinna V.A.,Oy Metsa Botnia Ab |
Kuokkanen T.,University of Oulu
Water Science and Technology | Year: 2010
The Bothnian Bay at Kemi, which is the northernmost basin of the Gulf of Bothnia in the Baltic Sea, is affected by effluents from point sources such as pulp and paper mills and municipal sewage plant. During the period 1988-2008, the accumulated values of effluent volume, BOD7, CODCr, Tot-P, Tot-N, TSS and AOX from these point sources fell considerably as follows: 1) effluent volume by 24%, BOD7 by 92%, CODCr by 74%, Tot-P by 79%, Tot-N by 38%, TSS by 76% and AOX by 93%. The decrease in the effluent loadings is due to the introduction of Best Available Techniques (BAT) for the production processes and wastewater treatment at the pulp and paper mills. According to the long-term monitoring program that has been carried out every third year between 1997-2009, the decreasing trend in EOX - concentrations in the top 2 cm of the bottom sediment reflects the decrease in organochlorine discharges (AOX) from the mills. In 1997, the EOX concentrations in bottom sediment varied between 3-70 μg of Cl g-1 (dry weight), and in 2009 between 1.2-31 μg of Cl g-1 (dry weight). © IWA Publishing 2010.
Pulkkinen I.,Aalto University |
Fiskari J.,Oy Metsa Botnia AB |
Alopaeus V.,Aalto University
Holzforschung | Year: 2010
The activation parameter developed is based on the fiber wall thickness distribution, fiber curl distribution, and water retention value of the unrefined fibers. The mechanical properties of paper that contain chemical pulp depend, among other things, on the free fiber segment activation between fiber-fiber crossings that is created during drying. Experimental data revealed that the degree of fiber swelling is responsible together with the fiber shape factor (curl) and fiber wall thickness for the extent of fiber network activation. The amount of bonding between fibers also affects fiber segment activation. Based on the experimental data, it was deduced that interfiber bonding ability of fibers, characterized as the water retention value, was mainly responsible for the development of handsheet density. Tensile index development was more affected by the morphology of fibers, which was the main determinant for high activation potential of fibers. Factor analysis was used to identify the main causes of variation for a refining data set of 20 Eucalyptus grandis samples. Three independent escriptors were found to be responsible for the majority of the variation: the bonding and activation factor, the factor of microcompressions, and the factor of fiber wall thickness and fiber curl. The activation parameter developed in this study can be used to determine the effect of fiber segment activation and inter-fiber bonding on the inplane mechanical properties of paper. © 2010 by Walter de Gruyter Berlin New York.
Skrifvars B.-J.,Åbo Akademi University |
Westen-Karlsson M.,Åbo Akademi University |
Hupa M.,Åbo Akademi University |
Salmenoja K.,Oy Metsa Botnia Ab
Corrosion Science | Year: 2010
This paper is the second in a series of two papers where we report results from laboratory-scale corrosion studies in which tailor-made well-characterized synthetic alkali salt deposits were used for corrosion testing of typical kraft recovery boiler super-heater steel materials. The corrosion testing was done in temperatures ranging from 450 to 600 °C. Six different alkali salts and six different steel types were used in the tests. In the first paper we reported generally on the corrosion tendencies of the six steels. In this second paper we continue the corrosion behavior mapping of the tested steels. © 2009 Elsevier Ltd. All rights reserved.