• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.49-59
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• 2008

The effects of design parameters on the pellet transport rate in the ejector system which is widely used in the production processes of automotive parts were investigated experimentally. The primary nozzle geometry, the area ratio (R) of nozzle exit cross-sectional area to mixing chamber cross-sectional area and the distance (S) from primary nozzle exit to mixing chamber entrance were considered as the design parameters. The area ratios of the primary nozzle were varied from R=0.10 to R=0.25, 0.30, 0.40 and 0.55. The primary nozzle was positioned at the non-dimensional distance (S/D) of 1.30, 1.87, 2.44, 3.00 and 3.75, normalized using the mixing chamber diameter (D). The design parameters were determined to run with high efficiency by measuring the pellets transport rate. The geometry and the area ratio (R) of the primary nozzle had an effect on the pellet transport rate of the ejector system, and the area ratio of R=0.3 was carefully selected after taking the minimum fluidization velocity and transport rate of applied pellets into account. The higher pellet transport rate with the variation of the distance (S/D) was observed at S/D of 2.44.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.4
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• pp.472-482
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• 2007

This study deals with the design and implementation results for a high-capacity vol-oxidizer that can convert Uranium Dioxide pellets to $U_3O_8$ powder for up to several tens of kg HM/batch. We developed two versions of the $1^{st}$ vol-oxidizer and the $2^{nd}$ vol-oxidizer. Through an experiment with the $1^{st}$ vol-oxidizer, we deduced some problems concerning the design considerations such as the recovery rate of $U_3O_8$, the oxidation time of the Uranium Dioxide pellets, the exothermic reaction, and the powder dispersion. From the analyses of the drawbacks of the $1^{st}$ vol-oxidizer, we devised some novel items such as a folding type mesh, vibrators, and mixing blades. Also, we used the Stokes and Density ratio Eq. to determine the most reasonable flux for preventing a powder dispersion. Compared with the results of the $1^{st}$ vol-oxidizer, we showed that both the permeability of the $U_3O_8$ powders and the oxidation rate of the Uranium Dioxide pellets of the $2^{nd}$ vol-oxidizer were remarkably increased, and the temperature of the reactor was controlled well in spite of an exothermic reaction. Also, the powder was not entirely dispersed through the outlet of the voloxidizer. The experimental results of this work can help in the design of a novel and efficient vol-oxidizer with a higher capacity.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.818-826
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• 2017

In accordance with the New and Renewable Energy Supply Statistics, biomass power generation has surged since 2013, and use of wood pellet has the most sharply increased, 696Gwh in 2013, 2,764Gwh in 2014 and 2,512Gwh in 2015. Total domestic wood pellet consumption was 1.48million tons in 2015, of which wood pellets consumed for power generation account for about 1.08million tons, about 73%. In this study, we gained the result that the wood pellet would be consumed 2.61million tons in 2020, 6.85million tons in 2025, 11.39million tons in 2030. We also calculated the optimum biomass power generation, on the premise that the power plant co-fire 50% biomass, and the result was that 2.26million tons of wood pellets should be produced domestically in 2021 to operate the present licensed wood pellet power plant from this study.

• Resources Recycling
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• v.21 no.1
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• pp.75-81
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• 2012

Porous pellets for immobilizing heavy metals were manufactured from coal tailings and iron oxide powder. Coal tailings was pulverized and mixed with iron oxide powder. The mixed powder was granulated into spherical pellets and roasted. Over $1100^{\circ}C$, residual coal in coal tailings reduced iron oxide to ZVI(Zero-Valent Iron). The pellets have 34.63% of porosity, 1.31 g/mL of bulk density, and 9.82.urn median pore diameter. The pellets were reacted with synthetic solutions containing each heavy metals: arsenic(V), copper(II), chrome(VI), and cadmium(II), respectively. On the test of immobilizing heavy metal, the pellets made at $1100^{\circ}C$ were superior to the other pellets made under $1000^{\circ}C$. Immobilizing over 99.9% of 10ppm heavy metal solutions required I hour for arsenic, 2 hours for chrome, and 4 hours for copper. However, immobilizing capacity of cadmium was inferior to that of the other metals and it was decreased in reversely proportion to initial concentration of the solutions.

• New & Renewable Energy
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• v.18 no.2
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• pp.1-8
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• 2022

This study aimed to determine the optimal conditions for fabricating pitch pine (PCP) and Mongolian oak (MOK) pellets using chestnut-shell tea waste (CSW) and castor oil (CSO) as additives. For pellets fabricated using a pilot-scale flat-die pellet mill, all moisture content (MC) was in line with A1 wood pellet standards for residential and small-scale commercial uses designated by the National Institute of Forest Science at the Republic of Korea (NIFOS), regardless of fabricating conditions; the durability of PCP pellets prepared using PCP particles with 10% MC, and CSW addition also satisfied these criteria. The moisture tolerance of PCP pellets improved with combination of 2 wt% CSW and 2-6 wt% CSO. Overall, use of 20 mesh CSW as an additive, PCP with 10% MC, and MOK with 12% MC was found to be optimal. Moreover, using CSO as an additive, high-quality PCP and MOK pellets can be fabricated by adjusting the particles to 12% MC. However, the durability of PCP and MOK pellets prepared using these conditions did not meet the wood pellet standards for residential and small-scale commercial use. Therefore, further research is needed to improve the durability of these pellets.

• Plant Journal
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• v.18 no.3
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• pp.52-61
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• 2022

This study tested the effect of de-NOx Facility operating condition on Nox emisiion in a 125 MW wood pellet power plant in Yeongdong Eco Power Plant Unit 1, which is in operation. As SNCR urea flow rate increased, NOx emission gradually decreased, but ammonia slip after SCR increased. The boiler under test has a structure that is unfavorable to SNCR operation due to the high internal temperature, and the optimum location of the nozzle will be required. SCR dilution air temperature change did not affect the amount of NOx generated. Increasing SCR ammonia flow reduced the NOx emission at SCR outlet and also increased the NOx removal efficiency. However, the ammonia flow rate of 111 kg/h, which does not exceed the ammonia slip its own reference limit, is estimated to be the maximum operating standard. The increase in SCR mixer pressure reduced NOx emission and the removal efficiency was also measured to be the most effective variable to inhibit NOx production.

• Journal of Hydrogen and New Energy
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• v.34 no.4
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• pp.327-333
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• 2023

The water gas shift reaction was carried out using the commercial catalyst pellet and the simulated gases expected to occur from waste plastic gasification. In the water gas shift reaction, the high temperature shift reaction and the low temperature shift reaction were continuously performed with CO:H₂O ratio of 1:2, 1:2.5, and 1:3, and the CO conversion and H₂ increase rate were evaluated. The H₂ increase rate increased in order to CO:H₂O ratio of 1:3 > CO:H₂O ratio of 1:2.5 > CO:H₂O ratio of 1:2. The CO conversion showed a high value of more than 97% at each CO:H₂O ratio. The water gas shift reaction at a CO:H₂O ratio of 1:3 showed the highest H2 increase rate and CO conversion.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.122-134
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• 2015

This study was conducted to investigate the potential of torrefied larch wood as a raw material of pellets. First of all, larch chip was torrefied at the temperatures of 230, 250 and $270^{\circ}C$ for 30, 50 and 70 min. Secondly, moisture content, moisture absorption, higher heating value and ash content of the torrefied chip were measured to examine the effects of torrefaction conditions on the fuel characteristics of larch. Thirdly, surfaces of the torrefied chip were observed by light microscope (LM), field emission scanning microscope (FE-SEM) and SEM-energy dispersive spectroscopy (EDXS). With the increases of torrefied temperature and time, contents of lignin increased and those of hemicellulose reduced. Moisture content of torrefied larch chip was greatly lower than that of non-torrefied chip. Moisture absorption of the torrefied chip decreased as torrefaction temperature increased. As torrefaction temperature increased, higher heating value and ash content of larch chip increased. However, durability of torrefied-larch pellets was remarkably lower comparing to non-torrefied-larch pellets. When surface of larch chip was observed by LM and FE-SEM, surface color and cell wall of the chip was getting darker and more collapsed with the increases of torrefaction conditions. Through the analysis of SEM-EDXS, distribution and quantity of lignin existing on the surface of larch chip increased with the increases of torrefied conditions. In conclusion, $270^{\circ}C$/50 min might be an optimal condition for the torrefaction of larch with the aspect of fuel characteristics, but torrefaction condition of $230^{\circ}C$/30 min should be considered according to the durability of torrefied-larch pellets.

• Journal of Forest and Environmental Science
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• v.25 no.2
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• pp.127-130
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• 2009

This study has been carried out to investigate the characteristics of the commercial wood pellets such as moisture content, heating value, ash content, and chemical component. The wood pellets from national forestry cooperatives federation and China were evaluated to see if they can be 1st or 2nd class of Korea standard. Indonesian pellet was estimated to be a 3rd class because of the heating value and high ash content. It is considered that there is a quality difference in wood pellets in accordance with the production nations. It could be originated from the difference of raw materials produced in different region.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.165-166
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• 2014

The application of particle reaction model in the packed bed process modeling is discussed for iron ore pellet induration process. Combustion of coke breeze in the pellet is estimated by using shrinking unreacted-core model and grain model in which the progress of chemical reaction is described in different concepts. Under the identical inlet gas and solid conditions, the calculation using shrinking core model showed deviated results in terms of temperature profile and conversion fraction, which may imply the significance of selecting proper particle reaction model in consideration of particle characteristics and process operation conditions.