• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.23-28
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• 2007

Wood fuel must be dried before combustion to minimize the energy loss. Sawdust of Japanese red pine was dried in a direct contact thermal screw dryer to investigate the drying characteristics of sawdust as a raw material for bio-fuel. Average drying rate and energy efficiency was 1.4%/min and 69.23% at $100^{\circ}C$, respectively, and those at $120^{\circ}C$ was 2.1%/min and 71.03%, respectively.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.58-67
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• 2010

Combustion of the Korean Anthracite and wood-pellet was characterized in air atmosphere with variation of heating rate(5, 10, 20 and $30^{\circ}C/min$) in TGA. The results of TGA have shown that the combustion of the wood-pellet occurred in the temperature range of $200{\sim}620^{\circ}C$ which is much lower than that of Korean anthracite. Activation energies of the wood-pellet and Korean anthracite, determined by using Friedman method were 44.12, 21.45 kcal/mol respectively. Also, their reaction orders(n) and pre-exponential factors(A) were 5.153, 0.7453 and $4.01{\times}10^{16}$, $1.39{\times}10^6(s^{-1})$ respectively. In order to find out the combustion mechanism of the wood-pellet and Korean anthracite, twelve solidstate mechanisms defined by Coats Redfern Method were tested. The solid state combustion mechanisms of the woodpellet and Korean anthracite were found to be sigmoidal curve A3 type and a deceleration curve F1 type respectively. Also, from iso-thermal combustion($300{\sim}900^{\circ}C$) of their char, the combustion characteristics of their char was found. Activation energies of the their char were 27.5, 51.2 kcal/mol respectively. Also, pre-exponential factors(A) were $2.55{\times}10^{12}$, $1.49{\times}10^{10}(s^{-1})$ respectively. Due to the high combustion reactivity of wood-pellet compared with Korean anthracite, combustion atmosphere will be improved by co-combustion with Korean anthracite and wood-pellet.

• Clean Technology
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• v.23 no.3
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• pp.331-342
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• 2017

To estimate the combustion characteristics of sewage sludge and wood pellet, thermogravimetric analysis (TGA) was conducted. As TGA results, combustion characteristics of sewage sludge was worse than wood pellet. In ash fusion temperature (AFT) analysis, slagging tendency of sewage sludge is very high compared to wood pellet. And also, the bubbling fluidized bed reactor with a inner diameter 400 mm and a height of 4300 mm was used for experimental study of combustion characteristics fueled by sewage sludge and wood pellet. The facility consists of a fluidized bed reactor, preheater, screw feeder, cyclone, ash capture equipment and gas analyzer. The thermal input of sewage sludge cases were $54.5{\sim}96.5kW_{th}$, in case of wood pellet experiment, it was $96.1kW_{th}$. As experiment results, the $NO_x$ emission of sewage sludge was averagely about 10 times the $NO_x$ emission of wood pellet. And also CO emission of sewage sludge is about 3.5 times of wood pellet. Lastly as a result of analysis of captured ash in cyclone, the combustion efficiency of all cases were over 99%, but the potential for slagging/fouling was high at all cases by component analysis of ash.

• Journal of Forest and Environmental Science
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• v.30 no.4
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• pp.362-369
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• 2014

This study investigated physical properties and combustion gas characteristics for 8 types of wood pellets (4 domestic and 4 imported products) distributed in the domestic market. Results showed that most pellet types were first-grade pellets in the wood pellet quality standards in Korea with the exception of 3 pellet types from K company (second-grade in mechanical durability), G company (off-grade in nitrogen content) and P company (second-grade in ash percentage). Mixed pellets which contained more lignin and sap content were higher in mechanical durability (%) than that of white pellets. From the combustion gas analysis results, NOx emitted from all pellets combustion was at acceptable levels for national emission standard of the Clean Air Conservation Act except for pellets from G company. In addition, CO levels from all types of wood pellets were acceptable except for pellets from D company and domestic pellets were higher CO levels than imported pellets. These results indicate the higher CO levels in domestic pellets due to the usage of forest thinning materials including logging debris which usually had the high content of bark.

• Journal of the Korean Wood Science and Technology
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• v.47 no.1
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• pp.110-123
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• 2019

This work was conducted to examine the relationship between lignin content and the durability of larch (LAR) pellets. LAR sawdust was immersed in tap water (TW), sulfuric acid (AC) and sodium hydroxide (AK) solutions, and then the immersed sawdust was used for pellet fabrication. Klason lignin (KL) content of the immersed LAR, contents of soluble lignin (SL) and monomeric sugars liberated from the immersion of LAR, and durability of LAR pellets were measured. KL content decreased as the concentration of AC and AK solutions increased, but glucose content increased with increase in AC and AK concentration. Durability of wood pellets fabricated using non-immersed LAR sawdust was the highest, followed by those made using TW-, AK- and AC-immersed sawdust. LAR pellets became more durable as the concentration of KL and SL increased, but a significant positive correlation was found only between pellet durability and KL content. Through the fluorescent microscopic observation and SEM-EDX analysis, it was verified that lignin content of non-immersed LAR pellets was higher than that of AC- and AK-immersed LAR pellets. These results suggest that lignin might contribute to an increase in inter-particle bonding in wood pellets.

• Journal of the Korean Applied Science and Technology
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• v.35 no.1
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• pp.247-253
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• 2018

To replace the imported biomass and to effectively cope with growing RPS(Renewable Portfolio Standard) in power sector, the domestic forest biomass resources for wood pellets were estimated from the preceding research and annual growth rate of forest trees in this study. Assuming that 20% of the by-product from forest trees processing were used as raw material for wood pellet and the wood pellet production capacity was based on the average value derived from the above two methods, unused by-product and residues generated 1.99million tons in 2016, 2.28million tons in 2020 and 3.08million tons in 2030. If 20% of by-products(pebbles, sawdust, etc.) from roundwood processing were used as raw material for wood pellets, the wood pellet could be produced 2.74million tons/year in 2016, 2.95million tons/year in 2020, 3.98million tons/year in 2030. Therefore, total amounts of wood pellet would be increased to 2.74million tons/year in 2016, 3.14million tons/year in 2020, 4.23million tons/year in 2030 when it considered unused by-product and residues from wood processing as raw materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.3
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• pp.315-320
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• 2020

Pellets are manufactured using wood by-products. The combustion efficiency of pellets depends on the pellet manufacturing process, the types of materials mixed while manufacturing and the wood pellet stoves themselves. In this study, we developed a multi-layer combustor to be used in a wood pellet stove, for the purpose of reducing environmental pollution and energy waste due to incomplete combustion. The multi-layer combustor was designed to compensate for the shortcomings of existing combustors. A CAD (Computer Aided Design) model was verified using a 3D printer and a prototype was developed. The combustion experiments were conducted on commercial and proposed combustors using pellets of the same brand, manufacturing date, place and specifications. From the experiments, it was found that the proposed combustor produced the lowest carbon monoxide (CO) emission and highest thermal efficiency.

• New & Renewable Energy
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• v.18 no.3
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• pp.23-31
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• 2022

This study evaluated the potential of coffee waste (CW) and used frying oil (UFO) as an additive in the production of pitch pine (PIP) and Mongolian oak (MOK) pellets. Ash contents obtained from CW and UFO were 0.5% and <0.1%, respectively. The calorific values of UFO (31.4 MJ/kg) and CW (26.3 MJ/kg) are higher than PIP (20.6 MJ/kg) and MOK (19.1 MJ/kg). For pellets fabricated using a pilot-scale flat-die pellet mill, regardless of fabricating conditions, moisture content (MC) and bulk density of PIP and MOK pellets satisfied the A1 wood pellet standard for residential and small-scale commercial uses, as designated by the National Institute of Forest Science (NIFOS) of the Republic of Korea. When CW was used as an additive, durability of PIP pellets made with 12%-MC sawdust and MOK pellets increased. The optimal conditions for producing PIP and MOK pellets could be by adding 20 mesh CW as an additive and the using of 12%-MC sawdust. However, durability of PIP pellets and ash content MOK pellets did not satisfy the A1 wood pellet standard of NIFOS. Thus, further research is needed to improve the properties of wood pellets with additives.

• 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.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).