• 한국자동차공학회논문집
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• 제20권5호
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• pp.102-112
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• 2012

The vast stores of biomass available in the worldwide have the potential to displace significant amounts of fuels that are currently derived from petroleum sources. Fast pyrolysis of biomass is one of possible paths by which we can convert biomass to higher value products. The wood pyrolysis oil (WPO), also known as the bio crude oil (BCO), have been regarded as an alternative fuel for petroleum fuels to be used in diesel engine. However, the use of BCO in a diesel engine requires modifications due to low energy density, high water contents, low acidity, and high viscosity of the BCO. One of the easiest way to adopt BCO to diesel engine without modifications is emulsification of BCO with diesel and bio diesel. In this study, a diesel engine operated with diesel, bio diesel (BD), BCO/diesel, BCO/bio diesel emulsions was experimentally investigated. Performance and gaseous & particle emission characteristics of a diesel engine fuelled by BCO emulsions were examined. Results showed that stable engine operation was possible with emulsions and engine output power was comparable to diesel and bio diesel operation. However, in case of BCO/diesel emulsion operation, THC & CO emissions were increased due to the increased ignition delay and poor spray atomization and NOx & Soot were decreased due to the water and oxygen in the fuel. Long term validation of adopting BCO in diesel engine is still needed because the oil is acid, with consequent problems of corrosion and clogging especially in the injection system.

• Environmental Engineering Research
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• 제17권3호
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• pp.157-165
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• 2012

This experimental study was performed to obtain thermal energy from the combustion of synthetic gas, produced by the pyrolysis of insulating oil containing polychlorinated biphenyls (PCBs) in a high temperature and high pressure reactor. The average synthetic gas generated was $59.67Am^3/hr$ via the steady state gasification of insulating oil waste (20 kg/hr) with average concentrations (standard deviation) of $CO_2$, CO, and $H_2$ in the synthetic gas of $38.63{\pm}3.11%$, $35.18{\pm}1.93%$, and $28.42{\pm}1.68%$, respectively. The concentrations of the PCBs in the transformer insulating oil and synthetic gas after its gasification, and the concentrations of the dioxins that could be produced from the incomplete degradation of PCBs were measured. It was revealed that the PCBs in the insulating oil were composed of the series from tetrachlorobiphenyl to octachlorobiphenyl. However, only the #49, #44, #52, and #47/75/48 congeners were detected from the synthetic gas after gasification of the insulating oil and in the flue gas from the combustor. In conclusion, the experimental conditions suggested in this study were very useful for the appropriate treatment of insulating oil containing PCBs. Also, fuel gas containing CO and $H_2$ can be obtained from the pyrolysis of insulating oil containing PCBs.

• 한국재료학회지
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• 제24권6호
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• pp.277-284
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• 2014

Using the spray pyrolysis process, nano-sized cobalt oxide powder with average particle size below 50 nm was prepared from cobalt chloride solution. The influences of the raw material solution on the properties of the powder formed examined. When the concentration of Co was low(20 g/L), the average particle size of the powder formed was roughly 20 nm, and the cohesion between these particles was significantly strong. When the concentration of Co increased to 100 g/L, the droplets nearly failed to exist in circular form and reflected a severely divided form. Furthermore, the average size of the particles formed was roughly 40 nm, and the particles reflected a polygonal form. When the solution was increased to nearly saturation level (Co at 200 g/L), the particle size distribution reflected significant unevenness due to severe droplet division while the surface also reflected significant unevenness. Furthermore, the average size of the particles formed increased significantly to 70 nm. The results of XRD analysis showed that the strength of the peaks reflected very little change when the concentration of Co was increased from 20 g/L to 50 g/L. Alternatively, when the concentration was increased to 100 g/L, the strength of the peaks increased compared to when the concentration was 50 g/L. However, when the concentration was increased to 200 g/L, the strength of the peaks failed to reflect significant change compared to when the concentration was 100 g/L. The specific surface area dramatically decreased by 30 % when the concentration of Co was increased from 20 g/L to 50 g/L. Alternatively, when the concentration of Co the solution increased to 100 g/L, the specific surface area decreased by roughly 15 %. Furthermore, when the concentration of Co was increased to nearly saturation level(200 g/L), the specific surface area decreased by roughly 35%.

• 대한환경공학회지
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• 제36권7호
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• pp.461-468
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• 2014

바이오차(biochar)는 산소가 제한된 환경에서 바이오매스를 열분해를 시켜 얻을 수 있는 고체물질을 말한다. 원료가 되는 바이오매스는 에너지작물, 임업부산물, 농업부산물 등의 폐기물을 사용할 수 있으며, 토양으로 적용 시 기후변화 완화, 화석연료 소비저감, 폐기물 처리비용저감 등의 장점이 있다. 본 연구에서는 폐목재를 원료로 바이오차를 생산하는 시스템을 대상으로 전과정평가 기법에 의해 환경에 미치는 영향을 평가하고자 하였다. 폐목재 1톤을 기능단위로 하였을 때 생산되는 바이오차를 토양에 적용하는 시나리오를 구성하고 지구온난화에 미치는 영향을 중심으로 환경영향을 분석한 결과, 파쇄 및 건조의 전처리 공정에서 4.048E-01 kg, 가스화 열분해공정에서 4.579E-01 kg, 토양살포 공정에서 9.070E-02 kg의 온실가스를 발생하여 총 9.534E-01 kg의 온실가스가 발생하는 것을 확인하였다. 바이오차의 토양적용 시 탄소저장효과는 252 kg으로 분석되어 251 kg의 탄소 네거티브 효과를 보였다.

• 한국응용과학기술학회지
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• 제34권2호
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• pp.327-337
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• 2017

반 건조 소화 하수슬러지와 폐플라스틱을 혼합하여 파일롯 규모(85.3kg/hr)의 연속식 저온($510^{\circ}C{\sim}530^{\circ}C$) 열분해 실험을 하였다. 실험결과 열분해가스 발생량은 투입물 건량의 최대 68.3%, 발열량은 $40.9MJ/Nm^3$이었으며, 연속식 열분해에 따른 외기 유입율이 19.6%이었다. 오일은 투입물 건량의 4.2%가 발생하였고, 저위발열량은 32.5 MJ/kg이었으며 시설부식 등을 일으킬 수 있는 황과 염소의 함량이 각각 0.2% 이상이었다. 투입물 건량의 27.5%가 발생한 탄화물의 저위 발열량은 10.2 MJ/kg이었고, 용출시험 결과 지정폐기물에 해당하지 않았다. 열분해가스의 연소 배가스는 일산화탄소, 황산화물, 시안화수소 등의 배출농도가 특히 높았고, 다이옥신 (PCDDs/DFs)은 $0.034ng-TEQ/Sm^3$로서 법적 기준치 이내였다. 건조 배가스 응축으로 발생한 폐수는 수질오염물질 47개 항목 중 총질소, n-H 추출물질, 시안 등의 고농도 항목이 많아 전처리 후 하수처리장 등에서의 병합처리 방식을 고려할 필요가 있었다.

• 전기학회논문지
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• 제61권2호
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• pp.339-341
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• 2012

The high Tc superconductor of YBCO system with the nominal composition of precursor was prepared from mixed powders of $Y_2O_3$, $BaCO_3$, CuO and $TiO_2$ by the thermal pyrolysis method. The effect of $TiO_2$ doping to Y based ceramics superconductors fabricated by the thermal pyrolysis reaction, to investigate the effect of the dopant on the superconductivity. The voltage appearing across the field-cooled HTS sample increased with external magnetic field. The improvement of critical current property as well as the mechanical property is important for the application. The improvement of the critical current can be achieved by forming the nano size defect working as a flux pining center inside the superconductor. We simply added $TiO_2$ to starting materials to dope $TiO_2$ and observed an increase in the trapped field and the critical current density up to at least 5 wt % $TiO_2$. The $TiO_2$ was converted to fine $BaTiO_3$ particles which were trapped in YBCO matrix during the sintering process. We observed a peak effect of Jc that can be attributed to $TiO_2$ doping and results suggest that introducing a proper amount of pinning centers can significantly enhance current density.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.33-36
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• 2014

Gasification of biomass produces syngas containing CO, $H_2$ and/or $CH_4$, which can then be converted into energy or value-added fuels. One of key issues for efficient gasification is to minimize tar concentration in the syngas for use in a final conversion device such as gas engine. This study investigated the decomposition of primary tar by catalytic cracking using char as catalyst, of which the feature can be integrated into a fixed bed gasifier design. The pyrolysis vapor containing tar from pyrolysis of wood at $500^{\circ}C$ was passed through a reactor filled with or without char at $800^{\circ}C$ for a residence time of 1, 3 or 5 sec. Then, the condensable vapor (water and tar) and gases were analyzed for the yields and elemental composition. Four types of char particles with different microscopic surface area and pore size distribution: wood, paddy straw, palm kernel shell and activated carbon. The results were analyzed for the mass and carbon yields of tar and the composition of product gases to conclude the effects of char types and residence time.

• 한국전기전자재료학회논문지
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• 제25권8호
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• pp.626-631
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• 2012

$SnO_2$ nanoparticles were synthesized by flame spray pyrolysis, which were directly deposited on Pt interdigitated substrates. Gas sensing performance was evaluated for various gases such as $H_2$, CO, $H_2S$, and $NH_3$, and it was compared with that of commercial $SnO_2$ nanopowder. The synthesis of $SnO_2$ nanoparticles was also conducted in various solvents. As a result, the primary particle size was changed with the solvent of precursor solution, and their $H_2$ sensing properties were significantly affected.

• Journal of Biosystems Engineering
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• 제43권1호
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• pp.14-20
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• 2018

Purpose: The purpose of this study was to investigate the performance of a vacuum pyrolysis system, to analyze bio-oil characteristics, and to examine the applicability for farm-scale capacity. Methods: The biomass was pyrolyzed at 450, 480, and $490^{\circ}C$ on an electric heat plate in a vacuum reactor. The waste heat from the heat exchanger of the reactor was recycled to evaporate water from the bio-oil. The chemical composition of the bio-oil was analyzed by gas chromatography-mass spectrometry (GC-MS). Results: According to the analysis, the moisture content (MC) in the bio-oil was approximately 9%, the high heating value (HHV) was approximately 26 MJ/kg, and 29 compounds were identified. These 29 compounds consisted of six series of carbohydrates, 17 series of lignins, and six series of resins. Conclusions: Owing to low water content and the oxygen content, the HHV of the bio-oil produced from the vacuum reactor was higher by about 6 MJ/kg than that of the bio-oil produced from a fluidized bed reactor.

• Macromolecular Research
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• 제15권6호
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• pp.565-574
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• 2007

In this study, five representative, commercially available polymers, Ultem 1000 polyetherimide, Kapton polyimide, phenolic resin, polyacrylonitrile and cellulose acetate, were used to prepare pyrolyzed polymer membranes coated on a porous {\alpha}-alumina$ tube via inert pyrolysis for gas separation. Pyrolysis conditions (i.e., final temperature and thermal dwell time) of each polymer were determined using a thermogravimetric method coupled with real-time mass spectroscopy. The surface area and pore size distribution of the pyrolyzed materials derived from the polymers were estimated from the nitrogen adsorption/desorption isotherms. Pyrolyzed membranes from polymer precursors exhibited type I sorption behavior except cellulose acetate (type IV). The gas permeation of the carbon/{\alpha}-alumina$ tubular membranes was characterized using four gases: helium, carbon dioxide, oxygen and nitrogen. The polyetherimide, polyimide, and phenolic resin pyrolyzed polymer membranes showed typical molecular sieving gas permeation behavior, while membranes from polyacrylonitrile and cellulose acetate exhibited intermediate behavior between Knudsen diffusion and molecular sieving. Pyrolyzed membranes with molecular sieving behavior (e.g., polyetherimide, polyimide, and phenolic resin) had a $CO_2/N_2$ selectivity of greater than 15; however, the membranes from polyacrylonitrile and cellulose acetate with intermediate gas transport behavior had a selectivity slightly greater than unity due to their large pore size.