• Journal of the Korean Wood Science and Technology
• /
• v.41 no.4
• /
• pp.346-357
• /
• 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 Energy Engineering
• /
• v.24 no.3
• /
• pp.82-88
• /
• 2015

After a reheating furnace installation, the modification of the size and the heat capacity is very difficult. Therefore, the development of design package tool is required for the computation on the correct specifications before the design and the installation. Prior to development of the design tool, a module that calculates the amount of heat loss of each part according to the specifications for determining the thermal efficiency of a continuous heating furnace was developed and applied to the oxy-fuel industrial furnace. Through this, the effects of fuel type, oxygen fraction and recirculation on the efficiency of the furnace of which the output is 110Ton/hour were analyzed. In oxy-fuel combustion condition, the efficiency was 15% higher than air combustion conditions. With the using COG(Coke Oven Gas) instead of LNG, the efficiency was slightly increased. In the air combustion condition, the efficiency was increased about 33% with the preheated air. But, in oxy-fuel condition, the amount of exhaust gas was reduced, so the efficiency was increased about 7%.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.12
• /
• pp.2205-2213
• /
• 2000

To investigate removal efficiency of dissolved matter by NF and RO, a pilot plant was operated for six months using groundwater treated by UF membrane. After the pilot plant operation, we performed autopsy test to identify characteristics of foulant attached on the membrane surface applying the used NF and RO in the pilot plant test. In autopsy test, we measured permeate flux and recovery rate of flux by chemical cleaning in each membrane. We also analyzed chemical cleaning disposal to examine component of foulant. Permeate flux of NF and RO1 showed rapid decline after 100 days of operation. Especially, reduction of specific flux in RO1 was more serious than in NF. Specific flux of RO2 with a low recovery rate resulted in gradual flux decline. Removal efficiencies of dissolved inorganic matters as a conductivity were 76.3%, 88.2% and 95.3% respectively for NF, RO1 and RO2, and RO2 presented the highest removal efficiency. And those of dissolved organic matters as TOC were about 80% for both NF and RO. The specific flux of membranes declined gradually from the feed water inlet to outlet of the membrane module and it showed that membrane fouling increased along the feed flow direction. Namely, concentration of pollutants became higher and volume of feed water was less as the feed flow approached to the outlet. It seemed that major foul ants were Ca consolidated into inorganic material and Si consolidated into organic material on the membrane surface. Fe was a great contribution to irreversible fouling. The SEM results indicated that the organic matter was attached to the first layer, closer to the membrane, and then inorganic matter with tetragonal shape layered over them. We could not observe biofouling because microorganism, which was cause of biofouling, was almost pretreated in UF membrane.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.7
• /
• pp.722-729
• /
• 2010

Over the last decades, much consideration has been given to microbiological and chemical risks, especially when wastewater was reclaimed as water resources for urban water, irrigation water and recreational water etc. We investigated the performance of UV-based processes such as UV and UV/$H_2O_2$ for both the removal of pharmaceuticals and personal care products (PPCPs) as an emerging chemical and the inactivation of pathogen with bench-scale experimental study. 38 kinds of PPCPs including antibiotics and analgesics were detected from secondary effluent used as tested water. Bench-scale experimental study showed that UV process would require considerable UV dose for the effective PPCPs removal. Contrarily, PPCPs removal efficiency significantly improved by the combination of $H_2O_2$ with UV even at a lower UV dose and, moreover, their removal efficiency increased with the increased initial $H_2O_2$ concentration. Besides naproxen (>89%), concentrations of all the investigated PPCPs decreased by more than 90% of their initial concentrations under $923\;mJ/cm^3$ of UV dose and 6.2 mg/L of $H_2O_2$. Previous studies showed that this operational condition could get 4~5 log inactivation for Total coliform, indicating that UV/$H_2O_2$ process will be appropriate to comply with the criteria of California Title 22 for Total coliform.

• Korean Chemical Engineering Research
• /
• v.52 no.4
• /
• pp.516-521
• /
• 2014

Axial and overall heat transfer coefficients were investigated in a bubble column with relatively high viscous and low surface tension media. Effects of superficial gas velocity (0.02~0.1 m/s), liquid viscosity ($0.1{\sim}0.3Pa{\cdot}s$) and surface tension ($66.1{\sim}72.9{\times}10^{-3}N/m$) on the local and overall heat transfer coefficients were examined. The heat transfer field was composed of the immersed heater and the bubble column; a vertical heater was installed at the center of the column coaxially. The heat transfer coefficient was determined by measuring the temperature differences continuously between the heater surface and the column which was bubbling in a given operating condition, with the knowledge of heat supply to the heater. The local heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing axial distance from the gas distributor and liquid surface tension. The overall heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing liquid viscosity or surface tension. The overall heat transfer coefficient was well correlated in terms of operating variables such as superficial gas velocity, liquid surface tension and liquid viscosity with a correlation coefficient of 0.91, and in terms of dimensionless groups such as Nusselt, Reynolds, Prandtl and Weber numbers with a correlation of 0.92; $$h=2502U^{0.236}_{G}{\mu}^{-0.250}_{L}{\sigma}^{-0.028}_L$$ $$Nu=325Re^{0.180}Pr^{-0.067}We^{0.028}$$.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.3 no.2
• /
• pp.69-78
• /
• 1995

When the food garbage of general hospital was dried by the rapid steam drying process, the water content was changed to 1.3% from 77.8~82.8%. In this experiment, weight reduction rate was 80%, and electricity consumption was 2.4Kwh. Dried compost from this rapid steam drying process was brown pellets, which was consist of 27.77% crude protein and 3.19% crude fiber. Even though these pellets were slightly short of crude fat and crude ash content, these were analysed as a possible supplementary feed for pig. On the condition of drying food garbage mixed with 5% pulverized chaff, the necessary drying time was shortened by 1 hour, weight reduction rate was 76%, and reduction rate of electricity consumption was 42%. But contents of crude fiber and crude ash were increased to about 2 times. In case of adding new food garbage continuously to the composted food garbage mixed with 3.4% pulverized chaff, weight reduction rate and contents of crude fiber and crude ash were decreased gradually, but contents of crude protein and crude fat were increased. In case of composting food garbage from buffet, both drying time and electricity consumption were reduced, and ingredients of compost were higher than that of assorted feed for pig in the market.

• Journal of Korea Soil Environment Society
• /
• v.3 no.3
• /
• pp.55-62
• /
• 1998

Soils contaminated with hydrocarbons and residual metals can be effectively treated by soil washing. In developing the soil washing process several major effects for separating contaminants from coarse soils progressively improved upon combinations of mining and chemical processing approaches. The pilot-scale soils washing process consists of the four major parts : 1) abrasive scouring, 2) scrubbing action using a washwater that is sometimes augmented by surfactants or other agents, 3) rinsing, and 4) regenerating the contaminated washwater. The plant was designed based upon the treatment capacity > 5 ton/hr on site. The lumpy contaminated soil fractions first experience deagglomeration and desliming passing through a rolling mill pipe. In the second unit the attrition scrubbing module equipped with paddles uses high-energy to remove contaminants from the soils. And a final rinsing system is assembled to separate the washwater containing the contaminants and very fine soils from the washed coarse soils. For recycling the contaminated washwater passes through a washwater clarifier specifically designed for flocculation, sedimentation and gravity separation of fine as well as flotation and separation of oils from the washwater. In order to more rapidly assess the applicability of soil washing at a potential site while minimizing the expense of mobilization and operation, a mobile-type soil washing process which is self-contained upon a trailer will be further developed.

• Journal of Korea Soil Environment Society
• /
• v.2 no.1
• /
• pp.83-90
• /
• 1997

Aiming at the treatment of large volumes of gas with a low concentration of poorly water soluble VOC(Volatile Organic Compound), a new system is proposed: the combination absorption tower/bioreactor. In the scrubber part of the bioscrubbing system, the contaminating compounds are absorbed in a aqueous phase. The contaminated scrubbing liquid is transported to the bioreactor, where the compounds are biodegraded by aerobic microorganisms (mainly to carbon dioxide, water, and biomass). In this study, separation of a volatile organic compound(VOC) out of a waste gas stream has been carried out using a re-cyclable high boiling point extrant(HBE). The liquid stream containing a high boiling point entrant(HBE) scrubs the gas stream in a direct gas-liquid countercurrent contacting operation in a packed tower for the removal of said component from the gaseous stream. A packed-bed column using Pall Ring was set up in order to simulate practical conditions for the scrubbing tower. The liquid stream transported to the bioreactor is recovered and recycled to the scrubber. The model gas, which contained 400 mg/$\textrm{m}^3$ of toluene, at a rate of 100 L/min, flowed into the packed column where the scrubbing liquid trickled over the packing in countercurrent to the rising gas at 10~15L/min. The bioscrubber designed for large volume air streams containing VOCs showed removal efficiency up to 80% in an optimum operating conditions during the tests fer removing toluene from an air stream by scrubbing the air stream with HBE.

• Korean Chemical Engineering Research
• /
• v.43 no.4
• /
• pp.537-541
• /
• 2005

A bubbling fluidized bed reactor was used to study $CO_2$ capture from flue gas using a sodium-based dry regenerable sorbent, sorbA which was manufactured by Korea Electric Power Research Institute. A dry sorbent, sorbA, consists of $Na_2CO_3$ for absorption and supporters for mechanical strength. $CO_2$ capture was effective in the lower temperature range of $50-70^{\circ}C$, while regeneration occurred in the range of $120-300^{\circ}C$. To increase initial $CO_2$ removal, some amount of steam was absorbed in the sorbents before injecting simulated flue gas. It was possible to remove most $CO_2$ for 1-2 minutes at $50^{\circ}C$ and residence time of 2 seconds with steam pretreatment. Little or no reduction in initial reaction rate and capture capacity was observed in multicycle tests. The carbonated and regenerated sorbent samples were analyzed by NMR to confirm the extent of reaction. The results obtained in this study can be used as basic data for the scale-up design and operation of the $CO_2$ capture process with two fluidized bed reactors.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.9
• /
• pp.1045-1050
• /
• 2014

$N_2O$(Nitrous Oxide) is known as the third major GHG(Green House Gas) following $CO_2$(Carbon Oxide) and $CH_4$(Methane). The GWP(Global Warming Potential) factor of $N_2O$ is 310 times as large as that of $CO_2$ because $N_2O$ in the atmosphere is very stable, and it becomes a source of secondary contamination after photo-degradation in the stratosphere. Investigation on the cause of the $N_2O$ formation have been continuously reported by several researchers on power sources with continuous combustion form, such as a boiler. However, in the diesel engine, research on $N_2O$ generation which has effected from fuel components has not been conducted. Therefore, in this research, author has investigated about $N_2O$ emission rates which was changed by nitrogen and sulfur concentration in fuel on the diesel engine. The test engine was a 4-stroke direct injection diesel engine with maximum output of 12 kW at 2600rpm, and operating condition of that was set up at a 75% load. Nitrogen and sulfur concentrations in fuel were raised by using six additives : nitrogen additives were Pyridine, Indole, Quinoline, Pyrrol and Propionitrile and sulfur additive was Di-tert-butyl-disulfide. In conclusion, diesel fuels containing nitrogen elements less than 0.5% did not affect $N_2O$ emissions in the all concentrations and kinds of the additive agent in the fuel. However, increasing of the sulfur additive in fuel increased $N_2O$ emission in exhaust gas.