• Journal of the Korean Wood Science and Technology
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• v.41 no.4
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• pp.346-357
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• 2013

In this study, it was conducted to produce wood pellets using domestic forest thinning residues and examine their quality according to Korean pellet quality standard. Raw materials were composed of larch and mixed broad leaves species. Based on the small-end diameter (6 cm), they were classified into four different types of raw materials such as LM (larch with middle diameter), LS (larch with small diameter), MM (mixed broadleaf with middle diameter), and MS (mixed broadleaf with small diameter). After crushing and drying process, wood pellets were produced by a ring-die type pelletizer using each raw material. Wood pellets made from four different types of raw materials were tested for their quality such as calorific value, moisture content, ash content, inorganic matters and so on. As results of quality analysis, the calorific values of all wood pellets were higher than 198 kcal/kg, and satisfied with the first grade of Korea wood pellet standard. The ash content was slightly increased after pelletizing. Mechanical durability of wood pellets was highly dependent on the types of raw materials. The quality differences among wood pellets were turned out due to different physical and chemical characteristics of raw materials even though the same pelletizing condition was applied.

• Journal of the Korean Wood Science and Technology
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• v.38 no.1
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• pp.36-42
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• 2010

This study has been carried out to investigate the characteristics of pellets manufactured from sawdust, and a mixture of liquid wood-tar and sawdust. Pellets were prepared at room temperature under 2000 kgf/$cm^2$ using an universal testing machine. The pellets prepared from Q. variabilis wood had slightly higher density than those prepared from P. densiflora wood. The amount of fine particles from Q. variabilis wood pellets was smaller than those from P. densiflora wood. The pellets from P. densiflora wood had higher heating values than those from Q. variabilis wood. The wood pellets manufactured with wood tar showed higher moisture content, density and heating value, but lower fine particles. From the experimental results, it is suggested that wood tar can be used to obtain the higher quality wood pellets.

• Journal of the Korean Wood Science and Technology
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• v.39 no.3
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• pp.258-268
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• 2011

This study was conducted to investigate the effects of sawdust size and moisture content, pelletizing temperature and time on the durability of the pellets fabricated with larch and tulip tree sawdust. The durability of larch-pellet was significantly higher than that of tulip tree-pellet. For the larch-pellets, the durability of the pellets fabricated with > 18 mesh sawdust was higher than that of 8~18 mesh sawdust. With the increases of pelletizing temperature and time, the durabilities of larch- and tulip tree-pellets steadily improved. The durabilities of larch- and tulip tree-pellets also increased as the moisture content of sawdust increased. In the comparison of durabilities between commercial pellets and larch- or tulip tree-pellets, the pellets fabricated with larch and tulip tree sawdusts in our study were less denser than commercial pellets, but the durability of most larch-pellets was satisfied with the 1st-grade pellet standard designated by Korea Forest Research Institute. In addition, the durability of tulip tree-pellets were higher than that of the 3rd-grade pellet standard. From the scanning electron microscopic observation of larchand tulip tree-pellets, the gap between the sawdusts of each pellet was reduced with the increases of pelletizing temperature and time. In particular, it was visually confirmed that the surface of the pellets made with the pelletizing temperature of $180^{\circ}C$ for 3 min did not differ from that of commercial pellets.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.258-267
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• 2017

In this study, pitch pine (Pinus rigida, PIR) and Mongolian oak (Quercus mongolica, QUM) pellets were fabricated with bark or/and drying waste liquor (DWL) of larch (Larix kaempferi, LAK) as an additive. Based on the results of fuel characteristics of the pellets, optimal conditions for producing the high-quality pellets were provided. In the analysis of chemical composition, bark contained holocelluose and lignin of 90% and over. DWL had 0.1% solid assumed to sugars which are generated from the oven-drying of LAK logs. QUM showed high ash content (2.2%) by containing of bark in the sawdust. Bark and DWL of LAK had high ash content of 4% and over. Calorific values of all specimens and additives were higher than that of the $1^{st}$-grade standard of wood pellets designated by NIFOS (18.0 MJ/kg). PIR and QUM pellets were fabricated with additive of 2 wt% based on the solid weight of oven-dried sawdust using a piston-type flat-die pelletizer, and thus ash content and calorific value of the pellets did not affect by the use of additive. Durability of the pellets increased with the use of additive. Durabilties of pellets, which were fabricated with bark as an additive and DWL as a controller of moisture content for sawdust, did not differ from those of pellets without additives and were lower than those of pellets either with bark or DWL. However, use of both bark and DWL for the production of wood pellets might be favorable because it can make a profit from the collection process of DWL. Based on the results of fuel characteristics of the pellets, QUM and PIR pellets were produced by a flat-die pelletizer. Moisture content (MC), bulk density and durability of the pellets improved with the use of additive. Particularly, sawdust MC of 10% and the addition of bark or DWL for PIR as well as sawdust MC of 12% and the addition of bark for QUM might be optimal conditions for the production of high-quality pellets. Except for the ash content of QUM pellets, other properties of PIR and QUM pellets exceeded the $1^{st}$-grade wood pellets standards of NIFOS.

• Journal of the Korean Wood Science and Technology
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• v.38 no.1
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• pp.49-55
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• 2010

morphologically different Larix Kaemferi Carr sawdust. The pellet characteristics included moisture contents satisfied the first grade (less than 10%) of quality standard of wood pellets announced by Korea Forest Research Institute. Densities were also adequate for the first grade (640kg/$m^3$) on the quality standard and there was no large difference in other characteristics of pellets, however, pellets manufactured with planer shavings had the highest density. Ash contents also passed the first grade (less than 0.7) of quality standard. But bark pellet exceeded the second grade (1.5%) in ash content. Lower absorption ratio of bark pellet showed the effect on hygroscpicity. The heating value of the manufactured wood pellets in this study exceeded the first grade of quality standard(more than 4,300 kcal/kg).

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.359-369
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• 2011

The study was carried out to investigate the quality characteristics of pellets manufactured with adding soybean oil, waste soybean oil, ozonized soybean oil and ozonized waste soybean oil to Larix kaemferi Carr sawdust. The characteristics of pellet included moisture contents, heating value, ash contents, apparent densities, durabilities, absorption ratio and elementary analysis. Moisture contents were shown 7.66~9.48% which satisfied the first grade (less than 10%) of quality standard of wood pellets announced by Korea Forest Research Institute. The heating value of the manufactured wood pellets in this study exceeded the first grade of quality standard (more than 4,300 kcal/kg) and it appeared that the pellets manufactured with adding oils and ozonized oils had more heating value than the control pellets. Ash contents 0.34~0.42% also passed the first grade (less than 0.7%) of quality standard and apparent densities were adequate for the first grade (640 kg/$m^3$) on the quality standard. Durabilities of the pellets manufactured with adding soybean oil and ozonized waste soybean oil were shown over the first grade (97.5 kg/$m^3$) of quality standard. In the general results of durabilities, the pellets manufactured with additives had better values than the control pellets. After 24 hours absorption ratio experiment, absorption ratio of pellets manufactured with additives also appeared much lower moisture absorption than the control pellets and they still had the same results after 5days absorption ratio experiment. Elementary analysis of the sulfur content was satisfied the first grade (less than 0.05%) of quality standard of wood pellets and the nitrogen content was also adequate for the first grade (less than 0.3%) of quality standard of wood pellets.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.13-19
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• 2015

The wood pellet is standardized of woody type fuel which of small cylindrical shape that is produced compress wood remnants in process of woody processing. The pellet is critical energy which expects to increase of the amount used in future. It consumes fuel which of home, common facilities stove and boiler, district heating, and CHP, etc. This study was to develop a movable pellet manufacturing equipment that can be mounted on a truck. The pellet production volume is approximately 309kg per hour, daily output is about 2ton. One days work based on the expected revenue of approximately \268,000 feasibility is considered sufficient.

• Journal of the Korean Wood Science and Technology
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• v.41 no.6
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• pp.594-605
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• 2013

This study was performed to analyze GHG (Greenhouse gas) reduction effectiveness and economic feasibility in the wood pellet fuel switching project using JCDM (Japan Clean Development Mechanism) and KVER (Korea Voluntary Emission Reduction)data. The major data for the analyses consist of investment costs, annual GHG reductions, fuel prices and GHG credit prices. The wood pellet fuel switching projects are the $CO_2$-zero projects. Therefore, these projects are essential to accomplish the GHG mitigation target, especially in Korea. In order to raise the economic feasibility of the wood pellet fuel switching project, the results of this study suggest that the Korean government should reduce the price of wood pellet through the supply on a large scale and raise the KCER price of wood pellet fuel switching project.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.120-128
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• 2015

This study reports the combustion characteristics, such as burner temperature and the concentration of exhausted gas ($O_2$, $CO_x$, $NO_x$) due to the different types and pitches of the fuel supply feeder of the wood pellet boiler. The 1st grade wood pellets composed of mainly larch have been used for the experiment. In case of using the spring feeder, mean temperature of burner was approximately $821.76^{\circ}C$, and the mean concentration of oxygen, carbon monoxide, carbon dioxide and nitrogen oxide were approximately 8.88%, 93.35ppm, 12.15% and 139.83 ppm, respectively. The test result with the spring feeder was shown to approach the condition of complete combustion compared to that of a screw feeder and were in good agreement with authentication judgement standard. Furthermore, the combustion efficiency was improved according to the growth of screw pitch. The control of air flow rate from the blower and ventilator is needed to achieve the complete combustion.

• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.15-21
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• 2006

The objective of this research is to develop the technique for carbonization of wood pellet and analyze a possibility for the utilization of carbonized wood pellet. The properties of wood pellet charcoals, such as density, yield, elemental composition, higher heating value, and methyleneblue adsorption, were analyzed. Wood pellet was made of sawdust of Hyunsasi-poplar, Japanese larch, Korean pine, Korean red pine, and Jolcharn-oak (serrate oak), respectively. The high density charcoal ($0.5{\sim}0.7g/cm^3$) was yielded from densified wood pellet. The carbon contents and calorific values of wood pellet charcoals were increased with the increase of carbonization temperature. The methyleneblue adsorptivity of wood pellet charcoal was similar to that of wood charcoal.