• Journal of the Korean Society of Combustion
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• v.20 no.2
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• pp.1-13
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• 2015

Drying, which is the oldest and most energy-intensive process, is an essential process for treatment of solid product. The specific procedure to design and evaluate the dryers, which are a rotary kiln dryer and a flash dryer, in case of drying the high-moisture coal was described. From determination of size to the heat and mass balance in one-dimensional model were conducted to evaluate the performance of dryers. Heat consumption, inlet gas temperature and size of the dryers were compared between a rotary kiln dryer and a flash dryer. Further considerations to evaluate the reactor elaborately were also discussed. Performance simulation of dryers along with the design procedure described here will provide helpful basis for understanding the concept of reactor design.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.289-292
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• 2014

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.106-111
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• 2012

Drying characteristic of high moisture coal using a 5 kg/hr bench scale flash dryer was investigated. Moisture content and heating value of raw coal as received basis were 29.74 wt% and 4,270 kcal/kg, respectively. Gas inlet temperature and gas inlet flow rate were $400{\sim}600^{\circ}C$ and 10~20 m/sec, respectively. The raw coal was ground and classified to the particle size range of $100{\sim}2,000{\mu}m$. The moisture removal rate of raw coal was dramatically increased with increasing gas inlet temperature and decreasing gas inlet flow rate. The heating value of dried coal was increased to 5,100~5,900 kcal/kg. To examine the chemical change on the surface of high moisture coal during flash drying process, FT-IR spectral analysis was carried out. As a result, major changes in hydroxyl, carboxyl and carbonyl peak was confirmed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5628-5636
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• 2012

Effective drying method of sewage sludge is researched in this study. To dry the sludge, chain crusher flash dryer was adopted to remove moisture content in the cell which is mostly responsible for the sludge moisture content. And Pilot plant experiment was conducted in real life sewage treatment plant to study effect and characteristics of operating conditions. Operating variables include sludge feeding rate, rotational speed of chain, process temperature and feed moisture content. As rotational speed of chain increased, product yield of sludge increased, and the performance of the testing system increased. And, as process temperature increased, the sludge drying efficiency increased. It is found that optimum feed moisture content is at 60% which shows the maximum sludge product yield and about 10 moisture content(%) of sludge product. Sludge feed rate showed optimal value, and when the sludge feed rate is exceeded, sludge product yield did not increased but the amount of residue increased. Pilot plant experiment results are as follow. The optimal condition for the rotational speed of chain 1600rpm(max. speed), final sludge discharge temperature $80^{\circ}C$, feed moisture content 60%, and feed rate 60kg/h. When the plant was operated at the optimal conditions, the final product showed fairly good results such as sludge product yield 85.5%, moisture content 11.0% and sludge drying efficiency 81.7%.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.313-317
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• 2017

With the continuous increase of energy demand, low-grade coal is regarded as one of new energy sources. However, due to the high water content, the utilization efficiency of low-grade coal is not good to be used in recent conversion plants. Therefore, it requires a drying process to lower the water content in low-grade coals. Although a variety of drying experiments were conducted, drying characteristics in accordance with the pressure change has not been progressed. In this study, the flash drying characteristics of low grade coal with high moisture content (21.5 wt%) were determined in a pressurized micro-riser. The effect of operation conditions such as pressure (1-40 bar), dryer temperature ($200-600^{\circ}C$), and tube length (2-6 m) on drying ratios were investigated.

• Clean Technology
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• v.8 no.2
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• pp.67-76
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• 2002

Dewatered sludge of 400,000t/y from water treatment plants in Korea is being disposed through landfill and ocean dumping. However, the disposal is posing more and more serious environmental problems at the same time not only because of landfill site shortage in municipal suburbs, but because of the concern it will contaminate the oceans. In this study, the research on utilizing the sludge dried by flash dryer as covering soil in the landfill sites was carried out to solve these problems on environmental affinity. Both dewatered and dried sludge were exposed to the natural condition and observed according to the atmospheric changes. An experiment of soil engineering characteristics of the dried sludge and tests on mixed sludge(silty sandy soil : dried sludge = 10:90 ~ 30:70) such as particle size distribution, liquid and plastic limit, moisture content, specific gravity and compaction test were carried out. According to the compaction test, the compaction was confirmed as the optimum water content ratio was observed in the condition of SM-silty sand of particle size distribution, NP of liquid and plastic limit, 101.4% of moisture content, 2.04~2.12 of specific gravity. The results showed that dried sludges mixed with at least 30% of natural soil could be used as daily covering soil in the landfill sites.