Fiber variability of european spruce and wood assortments for improved tmp production

Deliverables

Variations in paper properties may often originate from variations in wood properties. Better knowledge about the relationships between wood properties and properties of mechanical pulp is important for more efficient use of wood resources. - AFOCEL has developed a TMP laboratory pilot refiner suitable for the refining of small wood samples. This two-stage laboratory procedure was used within the EU project EuroFiber which aims at the definition of wood assortments better adapted to the end-product qualities of different European paper mills with Thermo Mechanical Pulping plants. - Norway spruce trees were sampled in four European countries (Estonia, France, Norway and Sweden). In each country many stands were selected and characterized in order to cover a maximum range of growth conditions, such as climate, site fertility and tree age. The stands were located in the wood supply areas of the participating mills to make industrial applications possible. Samples were taken at different heights of the trees and were split into juvenile, transition and mature wood, resulting in a total of 450 samples of Norway spruce with different properties. - In a first step these wood samples were characterized with regard to the number of growth rings, mean ring width, latewood content, fiber morphology, density as well as chemical composition. In a second step the wood samples were processed with the two-stages refining procedure. Each pulp was characterized for physical and optical properties, fiber morphology and specific energy consumption. All these data on forest, wood and pulp properties were compiled and statistically analysed. Large variations in pulp properties within and between trees and between stands were observed in this study. Relationships between forest, wood and pulp properties were modelled. - Models for pulp properties are issued from refining on the AFOCEL 12" laboratory refiner. Multiplicative model structure was found to be the best models type. As these models should be used to predict properties, process parameters, wood characteristics, assortment types, age and country were used as explanatory variables. These models could be used to increase pulp properties and evaluate how those properties will be affected by modifying wood and specific energy consumption, this one important factor showing the importance of controlling process conditions. - AFOCEL could support EuroFiber partners on the application of these models to an industrial production, using these tools completed by others parameters available in the case of mill trials. Benefiting from the large range of variations in the pulp properties, AFOCEL has also prospected the possibility to predict pulp quality directly from wood using NIR spectroscopy. This technology gives useable values for wood chemical composition prediction. Some limits exist for pulp properties based on wood NIRS spectra.

Norske Skog ASA has mills producing wood-containing printing papers in six European countries. In all countries Norway spruce is the dominating species for virgin fibre production. In addition a substantial amount of recovered paper is used in the Norske Skog paper production. The majority of the mechanical pulp fibres contained in the recovered paper originate from Norway spruce. Thus in all respects our European operations are dominated by the fibre properties derived from Norway spruce. Prior to the EuroFiber project there was only fragmented knowledge about the variability of Norway spruce grown at different European locations. The early conclusions of the project that spruce can be characterised reasonably well by two variables, basic wood density and fibre length, regardless of growth location and conditions is important as such. This result may seem somewhat remarkable as relates to basic density as e.g. thin walled small fibres may have the same basic density as thick walled large fibres. The combination of basic wood density and fibre length has, however, proven to be sufficient for characterisation of wood within the European region studied in the project. Thus this conclusion provides: - A proper basis for assessing the potential of wood collected from different sites; - A clarity on which wood variables to trace whether physically measured or calculated based on models generated in this project or elsewhere. - An opportunity to select suitable wood for different end product demands In practise there are several other conditions and constraints to be considered in this selection of wood such as: - Costs of wood in different areas; - Costs of transportation; - Time from felling to fibre processing; - Natural availability of different combinations of wood properties e.g. high density and short fibre length. If all conditions are known this project has provided a fair basis for assessing the economical value of a particular type of wood supplied to a selected mill. The cost of wood is and will most likely continue to be the dominating cost of virgin fibre production in Europe. Thus this information will be used for wood raw material cost optimisation. Different grades of printing paper have different demands on the fibre furnish used to produce the paper. As an example super calandered magazine paper (SC) put higher demands on surface properties and optical properties than newsprint. Wood with short fibre length is to be preferred for SC paper. While wood with long fibre lengths is to be preferred for sheets where strength properties are prioritised. Some of this knowledge was available earlier but rarely quantified to the point that it can be used for comparison between wood cost and fibre processing costs. In particular the pilot plant trial runs of the project have contributed and have shown: - The possibility to select wood with targeted properties when harvesting in the forests; - The ability to predict certain paper properties based on basic density, fibre length and degree of refining; - The possibility to select refining intensity and yet reach equivalent paper properties for given wood properties but at different specific energy applications. The major contribution of this work is to provide information for optimisation of the combination of wood properties and fibre processing. For a particular mill the selection of a particular type of wood can be compared to further fibre development. The former will have an impact on logistics & transportation costs and the latter on capital & energy costs less suitable wood will demand more fibre treatment i.e. increased specific energy input to reach desirable paper quality targets. The results derived from the pilot plant trials were tested in full-scale operation at the Norske Skog Follum mill in Norway. Two different wood assortments were selected and run on a high intensity refining line and applied to one paper machine. The results of the two wood assortments were compared both to each other and to the yearly averages of this production line. There are some interesting observations: - The results achieved in the pilot plant trials were confirmed in full scale operation for the two selected wood assortments. - The uniformity of the pulp produced with selected wood assortments was superior to that of the mix normally used. - The specific energy demands compared at equal drainage (CSF) of the two assortments were less than that of the yearly average of the wood mix normally used. - There are good possibilities for selecting certain more suitable wood assortments within the currently available wood to the mill for certain paper grades. - The targeted wood selection will achieve a better cost benefit ratio of the paper production than is currently the case. The implementation has started in the Follum mill. We have already seen some promising results. Hopefully the full potential will be reached within a year.

A mill trial was performed at the Iggesund Paperboard Workington site, comparing the quality and energy requirements of pulp produced from pulpwood with varying levels of sawmill chip contents. The mill trial findings were that the variation in wood density and fibre length in practice was less than had been measured for the more extreme wood sorts in the lab refining study, and in the pilot trials. This result followed through to the pulp test results, which showed a smaller difference with sawmill chip content than had been seen in the lab and pilot trials. The most likely explanation for this result is that the earlier studies were aimed at measuring the extremes of wood density and fibre length within the trees. The mill trial was performed using the available wood resources, which, as a result of the forestry practices in the UK, do not show the same levels of variation. This result allows the Workington mill greater flexibility when selecting wood materials to be used in the pulpmill, since the quality achieved from roundwood and sawmill chips were quite similar. It is hoped that this will also allow greater efficiency in utilising the available wood sorts.

The overall analysis of the results from the different parts of the project gave the following results: - There are large variations in wood and fiber properties in the forest. The differences between wood raw materials of various origins are characterized. The data are compiled in a database. - Prediction models are developed for the most important wood and fiber properties. - The variations are larger within each region than between regions. - The differences in wood properties will in most cases affect the properties of the pulp and paper produced. This was shown in comprehensive laboratory, pilot-plant and full-scale mill trials, with consistent results. - The use of chips from pulpwood, especially from thinning, may improve the optical properties of the products. - The use of sawmill chips, especially from large-diameter timber, may improve strength properties. - The specific energy consumption is lower for sawmill chips than for chips from pulpwood. - Benefits from selective use of the available wood materials in relation to product and process are proven in the mill trials. - The potential to benefit from this and the manner in which it should be implemented differ among mills. Practices have to be designed according to the specific demands and possibilities of each mill and company. - Tools are needed for the efficient analysis of such demands and possibilities and for the development of dedicated applications. - Tools are also needed for prediction of wood and fiber properties in the forest and for allocation of materials to mills and products. The tools should be integrated into efficient system for planning, operations and logistics in "forestry-wood chains" from tree to product. - The project results may play an important role in the development of new sound solutions for improved product quality and production efficiency in mills and companies. Such solutions should take all the production chain from tree to product into account. Examples of results useful in such applications are the models for prediction of wood and fiber properties in trees. For each participating mill, the project has provided a basis to decide if and how the mill can benefit from a more selective utilization of the available wood and fiber materials, related to its products and processes. Applications are being prepared in most mills: - Mill one is preparing the introduction of wood selection for different products. - Mill two will use the data and models to optimise its use of wood. - Mill three has started to use a more favourable mix of raw materials and has simplified its wood handling. - Mill four has a potential to save bleaching chemicals, but will not proceed now. - Mill five has a potential to vary its chip supply according to availability more than today. - The mills have acquired better knowledge about relationships between raw materials, energy consumption, process conditions and product properties. This will contribute to the development of better products, reduced energy consumption and costs and thus increased competitiveness. The process supplier may supply its customers with process solutions, refiner plates and operating conditions better designed for production of products with specified properties from available raw materials. The knowledge is now utilized in development, marketing and services. The research institutes have developed new and improved methods, databases, models and approaches, which are now further developed in new projects and used for fundamental research as well as development of applications. Also other products, wood species and regions are addressed. Examples are: - Tools for optimal allocation of wood to mills and products, to be used for strategic planning as well as on-line during harvesting. - Data and models for other wood species, regions and products. - Studies of "best use" of the regionally available wood raw materials for specific companies, mills and products. Also other stake-holders than the project partners may benefit from the results: - Better use of the European forest resources and improved competitiveness of the wood based industry are positive for forestry and society in regions dependent on the forest industry sector. - Better quality of paper is positive for other enterprises in the value chain (printers, converters, etc.) as well as for the end-user. - The results are useful in education. The results of the EuroFiber project have been disseminated though many channels to various target groups. The partners are now using the results of the EuroFiber project in further research and development. The paper companies are communicating results to other mills within the companies. The research institutes and the process supplier are ready to support their customers in the development of applications based on the project results.

The objective of Andritz was to obtain a better understanding of the relationships between wood properties, process design, and operation and product properties, to be able to offer better process solutions. The following results related to this objective were obtained from the measurements on wood and the trials performed in a laboratory refiner, in pilot scale and in commercial scale in mills: A. Large differences exist in wood and fibre properties, both between and within trees. Some major findings are: - Correlations and trends prove that wood density and virgin fibre length are two major parameters useful for the practical selection of wood for spruce in Europe. These parameters reflect the influence of geography, latitude, altitude, age of trees, etc. on pulp properties such as light scattering coefficient, tear strength and surface smoothness. Equal density and fibre length in a tree grown in Norway, Sweden or France bring similar paper properties. These parameters can probably be used in a similar way within other regions, too, for certain species. - Juvenile wood fibres have thinner fibre walls and tend to be shorter than mature fibres. - Slabwood, especially from final cuttings, represent 100% mature wood, while top logs and logs from first thinning mostly consist of juvenile fibres. - Slabwood gives significantly better strength properties than pulpwood. - Pulpwood chips with low density give pulps with better optical properties. - The wood type has greater influence on pulp properties than the refining method used to produce TMP. - The low-density wood consumed more energy than the high-density wood from each of the three countries. - The wood with short fibers requires more energy than the wood with long fibers. Based on these results, the papermakers will in the future have new possibilities to select the wood, which they are using in their mills according to the needs of the end product (paper & board). The selection can be based not only on wood species but also on other parameters like basic wood density and virgin fibre length, which can give more information about the suitability of the wood. The results also have influence on the design of processes and equipment in the future, which is important for both equipment suppliers and process engineers who plan new plants. B. Process Applications: - Sorting of Wood: In order to make full use in pulp production of the fundamental knowledge we have on the differences on wood qualities, we have to develop techniques and skills for planting, growing, harvesting, sorting and separate storage of wood with different properties in the forests, sawmills and in a paper mill. - Refining: The pilot plant trials which were carried out in Springfield (OH, USA) demonstrated that refining of mature long fibres, which mainly come from slabwood (sawmill chips), need 10V 15% less SEC. Thus, mills can expand their productions by using such wood and still use the existing refiners and refiner motors. Freeness of the TMP can be decreased by mainly using sawmill chips. The equipment can remain the same. With high-intensity refining (RTS), similar pulp strength can be achieved at lower specific energy consumption on the same wood species and quality. Typical energy savings are in the range of 300V 400kWh/t. Even higher energy savings could be achieved, if both advantages were superimposed. In that case the savings could be in the range of 500V 700kWh/t. This still has to be proven. High-intensity refining is also known to give better surface properties compared to conventional TMP. Thus, by combining the effects of the wood species and process options, new possibilities appear. Energy consumption has a direct impact on the emission of greenhouse gases and thus these findings and new process designs may help to achieve the goals of the Kyoto Protocol in the future. - Dewatering and Bleaching: It is well known today that there exist big differences in the bleaching response of different wood species, e. g. softwoods (spruce, pine, fir) and hardwoods (aspen, poplar, birch). Certain differences in the drainage capacity of roundwood and sawmill chips have also been experienced in various TMP installations, but no clear dependencies are known today. However, little is known about the effects of basic density and virgin fibre length on the bleaching response or dewatering behaviour of such fibres. Thus, no predictions can be made on future process design without doing further research work. - Process Control: New developments in process control try to make use of model predictive control systems to optimise the pulp quality and production quantity while minimising operating costs. Correlations and trends based on wood density and fiber length, which were developed in the EuroFiber project, can be used in such advanced process control packages to achieve the goals.

The physical manufacturing of wood based products starts at harvesting in forest stands. Different wood sources have different wood and fibre properties. This has been clearly stated by a systematic sampling of different log heights from individual trees of different ages (maturity) growing under different climatic and soil and other stand conditions. The EuroFiber project has developed, improved and adapted models predicting fiber (e.g. fiber length, fiber width, cell-wall thickness and basic density) wood properties of logs from Norway spruce growing in many parts of northern and central Europe. By measuring or assessing tree diameter, age and height of sample trees from a stand, wood and fiber properties can be predicted with commonly acceptable accuracy at the pile level. Pilot and mill trials included in the EuroFiber project clearly indicate that fiber length, fiber width, cell-wall thickness and wood basic density all have relevance for TMP-based products. There are several opportunities to improve different production chains by using these models in forestry practice. We have now started to introduce applicable prediction models (from different sources including EuroFiber) into software components useful for forest planning systems, tree harvesters, logistics and industrial production planning systems. Three examples of forestry applications are given below: 1.Wood procurement strategies, 2.Stand selections and 3. Sorting by wood and fibre properties. - Wood procurement strategy: The properties of wood vary: from one region to another, among stands, among trees in a given stand and within individual trees. Given the low haulage costs, it is often prudent to use all the acceptable raw material that can be harvested close to a mill. Over longer haulage distances, however, it becomes more important to supply wood having the desirable properties. When there are two mills sharing an intermediate zone, and their processes and product mixes differ, they can both benefit by splitting the raw material between them according to the wood properties. This makes for more dynamic procurement areas, with raw-material supplies being better suited to the needs of the individual mills. Examples of other situations in which it may be advantageous to adjust the procurement area according to the wood properties include: -- Areas in which there is a surplus of timber; and -- Where a mill increases its consumption of raw materials and, hence, its procurement needs. In principle, this strategy is much the same as that used at present, whereby the haulage distance is weighed against the availability of raw materials and the needs of the mill. However, wood properties provide an added dimension to logging and haulage planning. Thus, with the aid of some simple rules of thumb, predictive models and modern planning techniques, an overriding strategy for raw-material supplies, closely adapted to the needs of the individual mill, can now be implemented. - Stand selection: The wood properties of trees vary widely even among stands in the same tract. Pulpwood from thinning, for example, has different properties from that harvested in final felling. Similarly, old stands yield different properties from those of younger stands; fertile soils produce different pulpwood from that grown on poor-quality soils... and so on. This knowledge can be used in scheduling stands to be felled, or to allocate pulpwood from a particular stand to a given mill, in order to improve the properties of the raw material and, thereby, to reduce unwanted variations. - Selection by wood and fibre properties: A large percentage of the variation that occurs in the wood and fibre properties is found within and among trees in a given stand. Consequently, it is possible to improve the properties in the pulpwood by sorting the wood into a greater number of assortments than is customary today. However, handling more assortments increases the cost of felling, extraction and road haulage. Beside the EuroFiber project Skogforsk has developed computer software (Sortkost) that calculates the cost of sorting in conjunction with harvesting. If the revenue covers the cost of sorting, it pays to increase the number of assortments extracted from the stand. If several additional assortments are to be extracted, the harvester can be programmed, using the models, to determine the average wood properties in the individual logs. Data that can be used include the length and diameter measured by the harvester, together with the stand age, latitude and elevation of the stand. Thus, it will be possible to optimise the sorting strategy continuously to meet the woodproperty and volume requirements specified by the mills and, at the same time, to take into account the wood, logging and logistics costs.

Large efforts have been devoted to compilation and dissemination of the project results to different target groups through various information activities. 5EuroFiber - Fiber variability of European spruce and wood assortments for improved TMP production.) During the first three years, most of the results of the EuroFiber project were available only for the consortium companies. A series of project internal workshops were arranged to communicate results and to motivate persons entering the project well before new project phases were started. During the last year of the project, a phase of wider dissemination of results was started. The results of the project have been and will be exploited and disseminated in different ways: some will be made publicly available, some will be exploited by the partners. A large part of the results of the research institute partners have been published through reports, presentations at conferences, articles, etc. The general findings of the industry partners, the mills and the supplier, will also be presented. STFI, Skogforsk and AFOCEL have all efficient channels to disseminate the project results to their financing companies. A large part of the European pulp and paper companies and many mills in different European countries are included. The industrial partners have also access to a number of efficient internal and external channels, through which the results of the project may be transformed into applications to improve the competitiveness of the European industry. During the project, many meetings and presentations have been arranged, where results have been disseminated between the partners and in the next step through the internal information channels of each company. The internal project workshops arranged every year have played an important role in this. At these workshops, a wider group of people engaged in production, research and development within the participating companies had the opportunity to take part. The project results are also disseminated within the companies to other mills and to their suppliers of wood and fiber raw materials. The participating mills and their companies have already during the project started to interpret how they best can benefit from the results of the project for improved competitiveness. They have also started to test applications of the project ideas in full-scale trials. Some applications of the project results are already prepared. The mills and companies are not expected to disclose details of importance for their competitiveness, but they will report on the general benefits achieved and industrially verify the project results, and have in fact already done that. They will disseminate the detailed results within their companies, for rapid application of successful solutions. The participating process supplier will use the project results to improve its process equipment and to better relate equipment and process conditions with current wood raw material properties. These improvements will be supplied to the mills on commercial terms and will improve the market position of the supplier and improve the product quality and production efficiency of its customers. The first public presentations of the results were made at a full day seminar in May 2003, with 55 participants from many countries. Results were presented by the project partners from characterization and modelling of wood and fiber properties, laboratory refining, pilot plant refining and the four mill trials. The comprehensive documentation from the Seminar is available on the internet and in the CD-ROM report. The documentation includes presentation materials covering the project as a whole as well as all its parts, which makes possible further dissemination of selected results within companies, institutes, universities, etc. The wider international public has been addressed through the arrangement of a special session on the EuroFiber project at the "International Mechanical Pulping Conference 2003" (IMPC) in Quebec, Canada, June 1-6. At the conference, four papers were presented, which are publicly available through the conference proceedings. Efforts are made for scientific publication. In different workpackages, data and models of large importance for future research, development and applications have been developed. These data and models are owned by the responsible partners of the relevant workpackages, but shared between the partners via a common project database. The database will be made publicly available in 2005, when the partners have had the opportunity to finalize their own activities based on these assets. The ambition is that these data and models will form a basis for continued cooperation between the partners, also involving other research groups and companies. More reports, articles and presentations are expected to emanate from the project results. The published results may be used as is for better data and knowledge about wood and fiber properties and their variations in available forest resources, better allocation of different wood raw material resources in relation to product and process demands as well as optimisation of the production. Some examples of potential further application include: - The results may be used for research on growth and properties of trees and stands in relation to growth conditions, etc., and not only for production of mechanical pulp, but also for other pulp and paper products as well as for other products based on fibers or solid wood. - The methodology applied in the project may also be used to widen the application to other products, wood species and regions/countries. - Variations in wood and fiber properties of available forest resources may be characterized (wood species, regions, stands, trees). - The procedures used may also be applied on other wood species in other regions and for other purposes.

Stora Enso is a paper company with production units in many European countries and worldwide. The Stora Enso Corbehem Mill in France is part of the Publication Paper division. The main quality demands of the products are high levels of brightness, surface properties, printability and good strength properties for high runnability in papermaking and printing. The wood raw material used is a mixture of sawmill chips and pulpwood and also of spruce and poplar. Raw materials are supplied from a northern supply area (Northern France, Belgium and Germany) and a southern area (Central and Southern France). Prior to the EuroFiber project, new process equipment had been installed. The goal of the sub-project at Corbehem was to improve the LWC paper quality and runnability through a more favourable wood utilization. Today the wood from the different regions is handled separated at the wood yard and mixed into the mill in defined proportions. The availability and prices are better for sawmill chips. It would thus be beneficial if more sawmill chips could be introduced. Questions to be answered were: Is it important to separate the raw materials from the two regions? Could a more favourable wood mixture be used with respect to availability, costs and quality, considering also the changed situation due to new process equipment? Very clear results are normally needed to convince about changes. The combined results from the characterization of wood and fiber properties in various wood raw material alternatives and the refining trials performed on such different materials in laboratory and pilot scales were interpreted from the Corbehem perspective. Commercial-scale mill trials were designed in order to answer the questions above. In the trials, different types of materials from the two regions and proportions of sawmill chips were compared. During the trials, comprehensive measurements were performed on wood raw materials and pulps. Also the quality of the paper was carefully followed; the trials were performed under full-scale production of sellable paper. Samples were taken from all tested raw materials and the samples were analysed for wood density and fiber length. The data showed that there were no systematic differences in wood density and fibre length between the two regions. There was, however, one big difference compared to normal and daily supply: during the trials, the wood from the south was transported by truck instead of by train transport. Therefore, the delivery time was shorter than under normal operation and more similar to the one for wood from the north. The process conditions in pulp production were exactly the same during the trials as at normal operation. The stability in and control of operation was as usual and the specific energy used was also the same. The pulp analyses showed that there were differences in fiber length after the first refining, which were related to the percentage of sawmill chips. The difference could, however, be handled by the process. After the complete process, there were no differences in the main pulp properties between the pulps from different wood sorts. With the process equipment installed in the Corbehem mill, the process has the strongest impact on the final fiber quality. And with similar pulp properties, no significant differences in the paper properties were observed when the different wood sorts were run during the trials. More studies are needed for further optimisation. The results were so convincing that an action plansoon was implemented: - The wood from the different regions will not be handled separately, which will simplify and decrease the cost of wood handling. - The content of sawmill will be controlled and be increased. Larger raw material volumes will then be availability and at a lower cost. - With these measures, the Corbehem mill will be able to decrease the cost of the pulp, increase its certified wood content, while producing the same paper quality.

The ambition of this project for Norske-skog Golbey was to achieve tmp pulp quality improvement and/or production costs reduction through a better sorting of the round wood received at the mill. During this project and with the mills trials made in Norske-skog Golbey, we observed that it was possible to improve the characteristics of the tmp pulp by modifying the wood supply. For example, it was possible to improve the optics properties of the tmp pulp with more roundwood chips. Applications will nevertheless be limited because the results obtained cannot justify a major change of the wood supply in Golbey. The costs optimisation is very important and wood supply must comply with this rule as soon as the wood standard quality requirements are fulfilled. Golbey uses more recovered paper than wood. This limits also the application of this project. These results will interest papermakers which use mainly woods.

Data and knowledge on wood and fiber properties and their variation in European spruce forest resources. Classification of wood for mechanical pulp. Objectives of these tasks were: - To build up data on wood and fiber properties in wood resources from different European regions, emphasizing spruce resources and properties important for paper production. And, based on these data: - To analyse the variability of these properties within and between various types of stands and trees. - To select suitable materials for the pilot plant and mill trials. Norway spruce is the wood species most used in Europe for production of printing paper grades from mechanical pulp. Large volumes of Sitka spruce are also available soon. Prior to the project, there was only fragmented knowledge about the variability of Norway spruce grown at different European locations and even less information about Sitka spruce. The project has provided a fair basis in the form of data and models for assessing the value of a particular type of wood supplied to a specific mill. This is now being used for wood raw material optimisation. Comprehensive sampling of wood materials was performed from stands of Norway spruce in Estonia, France, Norway and Sweden and of Sitka spruce in Great Britain. The sampling strategy was designed to provide data about the effects of the major sources of variation in the most important wood and fiber properties, as a structured basis for modelling (result 8880). The stands and trees were characterized. Sampled were taken at different heights in trees of various sizes from stands of different ages, climatic and growth conditions. Sub-samples were prepared to provide data also on the radial variations from juvenile to mature wood. An arsenal of measurement methods was applied to determine wood and fiber properties for different parts of the trees, including growth ring widths, content of latewood, juvenile wood and heartwood, basic wood density, moisture content, fiber length, fiber width and fiber wall thickness. This way, information was obtained about internal growth patterns and variations in wood and fiber properties in the stems of the samples spruce trees. The data were crosschecked for errors to improve the data quality. Individual widths of growth rings and latewood bands from pith to bark and property averages for radial sub-samples and full cross-sections were compiled into a comprehensive database. The procedures for sampling, measurements and the database structure were adapted from a previous project Forest-Pulp-Paper on softwood species in Sweden, which also provided some data on Swedish stands, but the EuroFiber database is unique in providing related information on properties of stands, trees, wood and fibers of Norway spruce and Sitka spruce on the European level. Statistical analysis of the data showed large variations in fiber dimensions and wood density within each region. The differences between regions were limited compared to the variations within each region. This means that each mill will have to deal with, or has the opportunity to make use of the major part of the total variability. Trials to relate raw material properties and process conditions to product properties and energy demand have often failed, due to difficulties to control the input material. Therefore, large efforts were made to provide selected materials with different but uniform properties for the trials and to monitor the materials carefully during the trials. For this selection, differences between industrially feasible wood classes were analysed based on the database. Parameters related to the functionality of the fibers in paper were estimated for all samples and subjected to multivariate data analysis. Fiber length and wood density were selected to describe the suitability of fibers in the samples for different products. (This result is not generally applicable but valid for the investigated spruce resources in Europe). The property-based selection rules were translated into forestry terms, defining suitable wood materials for the trials. The usefulness of selection by fiber length and wood density was proven in the following trials. The database proved to be useful for the development of models for wood and fiber properties. Various types of models may be designed for different applications, for instance for new tools and practices in forestry planning and operation. The database is also a strong and unique basis for fundamental research on growth and properties of wood, trees and stands as well as for education. The methods and practices used will be applied in other projects to other wood species and regions/countries, to address problems and possibilities also for other types of products as well as for research and education. The wood and fiber database is owned and managed by STFI but available to all project partners and will be made publicly available in 2005. It is being used in further research projects and in the development of applications.

The subproject run within Holmen Paper was performed at the Hallsta Papermills mechanical pulping plant with help form Holmen Forestry regarding planning and selection of for mill scale trial suitable large pulpwood and saw mill chips samples. Four different pulpwood classes of Norway spruce (Picea abies (L.) Karst.) were tested in mill scale production of TMP at Hallsta Papermill. The objectives of the trial were to evaluate both rather extreme and more traditional roundwood classes in a full-scale TMP-plant with respect to pulp properties and energy requirements. The experiment was partly based on the results from the preceding pilot plant trial within the project. In general the results confirmed the findings in the pilot plant trial. Young wood with a high proportion of juvenile wood gave a pulp with attractive optical properties, but somewhat lower tear index and higher electrical energy consumption to the same paper tensile strength. The other extreme wood class, sawmill chips from old trees of heavy dimensions, required lower electrical energy input and gave higher tear index, but inferior optical properties. The two more traditional classes gave pulps with properties between the two extremes. The findings from this project can be used to further improve the product profiles and process efficiency when producing printing papers from spruce wood based mechanical pulps.

Data and knowledge on the large variability in wood and fiber properties of spruce from different European regions was made available through result 8879. In order to make this knowledge more useful in applications, models have been developed, improved and adapted to predict fiber and wood properties of importance for paper production in stems and logs from European spruce resources. Fiber length, fiber width, fiber wall thickness and basic wood density have been emphasized. Fiber length and wood density are the parameters selected to indicate the suitability of the different resources for use in different products. These parameters have, thus, special importance for the optimal use of the resources. Fiber width and wall thickness are parameters with large importance for the structural and surface properties of paper and from these variables, other variables more closely related to paper properties may be calculated. Models for cross-sectional averages for Norway spruce have been emphasized at this stage, corresponding to averages of stems and logs. The properties at different positions in stems different ages, sizes, etc., from stands with various characteristics in different regions are described. The aim of the modelling work was to arrive at robust and useful models, where the meaning of each term may preferably be interpreted, based on data in the database and on knowledge on the growth processes in trees under different conditions. It is also important to use input data, which are possible to gather in applications. A number of different model structures have been tested, including non-linear transformations of input variables. The models are based on general input parameters such as number and average width of growth rings, log diameter, log position (height) in the stem, latitude and altitude, etc., which may be determined or assessed in applications. The large variations found within and between trees and stands can be predicted with the following coefficient of determination (R2-value) and estimation errors (RMSE), (for basic density the prediction error): - For fiber length: RMSE = 0,18mm; R2 = 0,80; - For fiber width: RMSE = 1,30m; R2 = 0,68; - For fiber wall thickness: RMSE = 0,20 m; R2 = 0,65; - For basic density: prediction error = 26,6 kg/m3; R2 = 0,64. The fiber models are based on data from about 350 samples and the wood density models on 580 samples from Estonia, France, Norway and Sweden. The model for fiber length provides stable and fairly reliable predictions. The current models for fiber width, fiber wall thickness and basic density will result in predictions with somewhat lower relative precision at the individual sample level. As long as wood material to be predicted by these models stay within the range of the EuroFiber wood samples, fairly reliable pile averages would be expected. (To confirm this statement scientifically, further validation of the models is needed.) With these models and measured or assessed tree parameters of stands, the properties may be predicted with sufficient accuracy to improve the production in different forestry-wood chains. The models can be utilized to identify useful raw material resources and to define suitable criteria for selection of wood and fiber for specific mills and products, considering properties and volumes needed for various products and processes. Different types of models may be designed for different applications. The models can be used to develop practices and tools to optimise the allocation of the available wood resources to the specific demands and possibilities of each product, mill and company, considering planning, operations and logistics in all the "forestry-wood chains" from tree to product. The prediction models from the project and other sources are now used in the development and introduction of such systems for forest planning, tree harvesters, logistics and industrial production planning.

Searching for OpenAIRE data...

Deliverables

Share this page

Download