| 1. |
- Bergström, Dan, et al.
(författare)
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Effects of Extractives on the Physical Characteristics of Scots Pine Sawdust Fuel Pellets
- 2010
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Ingår i: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 60, s. 640-644
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Tidskriftsartikel (refereegranskat)abstract
- In order to evaluate the effect of extractives on particle bonding, pellets were produced from extracted and nonextracted Scots pine sawdust in a laboratory piston press pelletizer. In the experiment, the raw material and process parameters were fresh (nonextracted) and acetone-extracted sawdust, sawdust moisture content (6% and 12%), piston pressure (70 and 150 MPa), and press temperature (1008C and 1808C). The resulting pellets were evaluated and compared for density, compression strength, and moisture sorption. The relationship between factors and responses was evaluated by partial least squares regression. In the present study, it was found that pressure and temperature had a positive effect on both pellet density and compression strength. Extracted sawdust gave pellets with a higher density and compression strength than pellets made from nonextracted sawdust. Moisture sorption between the produced pellets showed no significant differences. Results of this study provide a plausible explanation for why pellets produced from stored sawdust with low amounts of extractives have better strength properties than pellets produced from fresh sawdust
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| 2. |
- Eriksson, Gunnar, et al.
(författare)
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Fuel Characterization of Pellet Chips
- 2011
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Ingår i: Forest Products Journal. - Madison, USA : Forest Products Society. - 0015-7473. ; 61, s. 143-148
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Tidskriftsartikel (refereegranskat)abstract
- Small hardwood chips, known as pellet chips, were characterized and combusted in two different pellet burners, installed in a residential boiler specially designed for pellet combustion. The average particle mass was about 10 percent of the mass of an 8-mm pellet, with a similar surface-to-volume ratio. The bulk density of pellet chips was 160 to 170 kg m(-3) at 10 percent moisture content (about 25% to 35% of 8-mm pellet bulk densities). The combustion performance was good, with average O-2 and CO values (by volume) at 17.6 percent (SD, 0.6%) and 200 ppm (SD, 210 ppm), respectively, for the bottom-fed burner and 14.2 percent (SD, 1.1%) and 330 ppm (SD, 93 ppm), respectively, for the top-fed burner. Thus the study indicates that pellet chips produced with commercially available equipment can be used in ordinary pellet combustors, provided that the fuel feeding rates are increased and the moisture content well below 20 percent. More accurate market assessments will require the investigation of the performance of different types of combustion equipment with fuels of different qualities.
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| 3. |
- Fredriksson, Magnus, et al.
(författare)
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Determination of crosscutting safety zone for finger-jointed Pinus sylvestris furniture components
- 2012
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Ingår i: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 62:2, s. 107-113
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Tidskriftsartikel (refereegranskat)abstract
- A common problem with finger-jointed wooden furniture components is chipping in the finger joints due to fiber deviations around sound knots. To avoid this, a fixed size safety zone between defects and crosscuts is used, but can lead to an excess of material cut away in the crosscutting operation. To reduce chippings in finger joints while maximizing recovery, an adaptive strategy was developed for setting the safety zone size between sound knots and finger joints in Scots pine (Pinus sylvestris L.) furniture components. The strategy was based upon modeling the risk of chipping the finger joint depending on the knot measurement. The model was used in an adaptive strategy in order to minimize the expected loss due to cutting away material around knots, compared with the cost of rejecting components in later stages due to chipped finger joints. Thus, each knot was assigned a unique safety zone. The strategy was tested using computer simulation of the finger-jointing process, and a sensitivity analysis was performed in order to quantify the effect of variations in the input data. The results show that the adaptive strategy improves recovery by at least 3 percent in the process of turning lumber into finger-jointed furniture components. It is very robust toward variations in knot size measurements (e.g., by scanning equipment), but less robust toward variations in crosscutting precision.
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| 4. |
- Lundahl, Carl-Gustav, et al.
(författare)
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Increased yield in sawmills by applying alternate rotation and lateral positioning
- 2010
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Ingår i: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 60:4, s. 331-338
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Tidskriftsartikel (refereegranskat)abstract
- Modern sawmills are increasingly like process industries, running continuously with very large volumes flowing through the process every second. This fact makes it vital for every company to utilize its equipment and raw material as effectively as possible to maximize yield and value. The objective of this simulated breakdown study was to analyze the potential to increase volume yield in Swedish sawmills. While the commonly used horns-down position performs well on an average basis, the results show that the optimal rotation position for an individual log is most often found at another position.Results from extended simulations show that the average volume yield can be increased further by applying the optimal combination of rotation and parallel positioning in cant and deal saw. An increase in average volume yield by 4.5 percentage points (8.6%) would enable a typical Swedish sawmill to produce a further 17,300 m3 of boards per year and thereby increase potential annual income by US$3.7 million per year. This optimization concept requires a preevaluation of every log in order to define the optimal combination of settings.Some of these procedures must be performed online within a split second to accommodate production speed demands. Modern technology such as industrial x-ray in combination with traceability methods, multivariate models, breakdown simulation software, and high-performance computers enables evaluation and optimization of every log online at full production speed. Sawing machines will need development in order to be able to perform optimization online without loss of production capacity.
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| 5. |
- Möller, Björn, 1969-, et al.
(författare)
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A field-tested log traceability system
- 2011
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Ingår i: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 61:6, s. 466-472
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Forskningsöversikt (refereegranskat)abstract
- Today, an information gap exists between log measurements performed in the forest and at the sawmill. By applying a code in the forest during harvesting and then reading it at the sawmill, this information gap would vanish. A log applicator, which applies two-dimensional log codes through the saw bar, and a corresponding detection system based on vision technology have been developed. Key features of this technology are the very low cost of each mark and the zero-time-loss characteristic of both marking and detection. A field test utilizing this equipment was performed on 210 logs in northern Sweden in December 2009. For logs harvested during real harvesting conditions and automatically detected at the log sorting station of a running sawmill, a detection rate of 40 percent was achieved. A comparison between parameters (length and diameter) measured in the forest and at the sawmill is presented, as are a number of suggested improvements to increase the detection rate substantially.
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| 6. |
- Nordvik, Enar, et al.
(författare)
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People's perceptions of the visual appearance of wood flooring : a Kansei engineering approach
- 2009
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Ingår i: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 59:11/12, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- Evaluations of products based on visual stimuli are at the same time both subjective and important. The aim of this study was to examine the relationship between the visual properties of wood flooring and people's reactions to computer visualization of interior wood products. The research strategy involved showing digital pictures of the same room, but with different wood floorings. The impressions of potential consumers were measured by means of rating scales for each descriptive word. This was done using the method of Kansei engineering, in which statistical connections between properties and semantics (descriptions) were analyzed. The research presented here contributes to theory and practice in two important ways. First and most important, the study shows that the chosen method is suitable for measuring people's preferences on visualizations of interior wood. Second, the results indicate that certain properties are important for a floor to be judged as ‘‘good-looking'' and others for a floor to be deemed ‘‘modern'' or ‘‘vivid.''
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| 7. |
- Sehlstedt-Persson, Margot, et al.
(författare)
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Mold growth on sapwood boards exposed outdoors : the impact of wood drying
- 2011
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Ingår i: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 61:2, s. 170-179
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Tidskriftsartikel (refereegranskat)abstract
- Mold growth on dried Norway spruce and Scots pine sapwood boards was investigated in an accelerated outdoor field test for 96 days. The boards were dried using three different methods of stacking: single stacking, double stacking with the sapwood sides in each pair facing toward each other, and double stacking with sapwood sides facing outward. Drying was performed at three temperatures: 25ºC, corresponding to air drying, and kiln drying at 70ºC and 110ºC. The degree of mold growth was visually assessed on both sides of each board. On average, pine boards showed a higher level of mold growth than the spruce boards. The highest average level of mold growth was found on the boards kiln dried at 708C, whereas the air-dried boards and the boards kiln dried at 110ºC showed considerably less mold growth. Stacking the boards during drying had a large impact on mold susceptibility of the sapwood. This study confirmed that, during the drying process, it is possible to direct the migration of nutrients in sapwood toward one chosen side of each board by double stacking; the opposite side leaches out, which has a great impact on surface mold growth. Chemical analyses of monosaccharide sugar gradients beneath the boards’ surfaces confirmed the results.
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| 8. |
- Adamopoulos, Stergios, et al.
(författare)
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Qualitative and quantitative fibre analysis in recycled raw materials for packaging
- 2006
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Ingår i: Forest Products Journal. - : Forest Products Society. - 0015-7473. ; 56:2, s. 58-60
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the influence that heterogeneous recycled raw materials have on packaging-grade paper performance offers great potential value to the corrugated board and packaging industry. Fifty-seven linerboards and corrugating medium were selected to represent all the variety of paper grades available on the Spanish market at the moment for the production of corrugated board. The origin of softwood, hardwood, and nonwood fibers and their percentages by weight were determined with light microscopy and standard fiber analysis techniques.
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| 9. |
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| 10. |
- Breinig, Lorenz, et al.
(författare)
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Effect of knot detection inaccuracy on value recovery improvement when using a CT log scanner for sawing control
- 2013
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Ingår i: Forest Products Journal. - 0015-7473. ; 63:7-8, s. 263-274
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Tidskriftsartikel (refereegranskat)abstract
- Roundwood scanners utilizing X-ray computed tomography (CT) provide the information required for individual log-sawing optimization. However, errors in the automated detection of quality-relevant internal wood features for sawing control may lead to improper log positioning at breakdown, impairing the realization of value recovery potential. It is thus of interest to have an estimation of the impact of feature detection errors on the performance of sawing optimization. A sensitivity analysis was conducted to quantify the effect of errors in knot detection on a breakdown optimization by adjustment of log rotation. Therefore, sawing simulations were performed with the geometric descriptions of log shape and internal knots extracted from the CT scans of 57 Norway spruce (Picea abies (L.) Karst.) logs. Three types of artificially set knot description errors were tested under different pricing and product scenarios, each in different magnitudes as systematic or random error. Errors in knot diameter were found to have the greatest impact for both systematic and random errors. The effect of errors in dead knot border radial position was less pronounced but still substantial for higher error levels, while errors in knot rotational position could be neglected even for the highest magnitudes of error tested. The assumed price differentiation between product qualities had a major influence on the impact of the errors. It could be observed that with errors of higher magnitudes than those reported for present knot detection algorithms, an improvement in value recovery compared with outer-shape–based optimization still resulted in the simulated rotation optimization.
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