아산화질소(N2O, Nitrous Oxide)는 6대 온실가스 중 하나로 대기 중에서 적외선을 흡수하여 온실효과를 유발하는 것으로 알려져 있다. 특히 지구온난화지수(GWP)는 CO2에 비해 310배 높아 국내뿐만 아니라 전 세계적으로 이슈화되고 있으며, 그에 따른 강력한 환경 규 제 강화법들이 발의되고 있다. N2O 저감 기술에는 물리적인 방식에 따라 농축회수, 촉매분해, 그리고 열분해로 구분할 수 있는데, 본 연구 에서는 그 중 가장 효과적인 열분해 처리방식에 대해 논의하고자 일반적인 연소 조건 내 고온 열분해 방식을 이용하여 비용 저감과 함께 질소산화물을 저감시키는 온도 조건 및 반응 시간에 대한 정보를 제공하고자 한다. 열분해 조건으로 선정된 고온 영역은 1073 K부터 1373 K 까지 100 K 간격을 두고 계산을 수행하였다. 1073 K과 1173 K의 온도조건에 경우, N2O 저감율과 일산화질소 농도가 체류시간에 따라 비례관 계를 이루는 것이 관측되었으며, 1273 K에 경우, 체류시간이 증가함에 따라 발생되는 역반응으로 인해 N2O 저감율이 감소되는 것이 관측되 었다. 특히 1373 K에 경우, 모든 체류시간에 대해 정반응과 역반응이 화학 평형상태에 도달하여 N2O 저감에 대한 반응진행율이 오히려 감 소하는 것으로 확인되었다.

In this study, nano-sized indium oxide powder with the average particle size below 100 nm is fab-ricated from the indium chloride solution by the spray pyrolysis process. The effects of the reaction temperature, the concentration of raw material solution and the inlet speed of solution on the properties of powder were studied. As the reaction temperature increased from 850 to , the average particle size of produced powder increased from 30 to 100 nm, and microstructure became more solid, the particle size distribution was more irregular, the intensity of a XRD peak increased and specific surface area decreased. As the indium concentration of the raw material solution increased from 40 to 350 g/l, the average particle size of the powder gradually increased from 20 to 60 nm, yet the particle size distribution appeared more irregular, the intensity of a XRD peak increased and spe-cific surface area decreased. As the inlet speed of solution increased from 2 to 5 cc/min., the average particle size of the powder decreased and the particle size distribution became more homogeneous. In case of the inlet speed of 10 cc/min, the average particle size was larger and the particle size distribution was much irregular compared with the inlet speed of 5 cc/min. As the inlet speed of solution was 50 cc/min, the average particle size was smaller and microstructure of the powder was less solid compared with the inlet speed of 10 cc/min. The intensity of a XRD peak and the variation of specific area of the powder had the same tendency with the variation of the average par-ticle size.

In this study, nano-sized powder of Ni-ferrite was fabricated by spray pyrolysis process using the Fe-Ni complex waste acid solution generated during the shadow mask processing. The average particle size of the produced powder was below 100 nm. The effects of the reaction temperature, the inlet speed of solution and the air pressure on the properties of powder were studied. As the reaction temperature increased from 80 to 110, the average particle size of the powder increased from 40 nm to 100 nm, the fraction of the Ni-ferrite phase was also on the rise, and the surface area of the powder was greatly reduced. As the inlet speed of solution increased from 2 cc/min. to 10 cc/min., the average particle size of the powder greatly increased, and the fraction of the Ni-ferrite phase was on the rise. As the inlet speed of solution increased to 100 cc/min., the average particle size of the powder decreased slightly and the distribution of the particle size appeared more irregular. Along with the increase of the inlet speed of solution more than 10 cc/min., the fraction of the Ni-ferrite phase was decreased. As the air pressure increased up to 1 , the average particle size of the powder and the fraction of the Ni-ferrite phase was almost constant. In case of 3 air pressure, the average particle size of the powder and the fraction of the Ni-ferrite phase remarkably decreased.

This study focuses on computational particle fluid dynamics (CPFD) modeling for the fast pyrolysis of biomass in a conical spouted bed reactor. The CPFD simulation was conducted to understand the hydrodynamics, heat transfer, and biomass fast pyrolysis reaction of the conical spouted bed reactor and the multiphase-particle in cell (MP-PIC) model was used to investigate the fast pyrolysis of biomass in a conical spouted bed reactor. A two-stage semi-global kinetics model was applied to model the fast pyrolysis reaction of biomass and the commercial code (Barracuda) was used in simulations. The temperature of solid particles in a conical spouted bed reactor showed a uniform temperature distribution along the reactor height. The yield of fast pyrolysis products from the simulation was compared with the experimental data; the yield of fast pyrolysis products was 74.1wt.% tar, 17.4wt.% gas, and 8.5wt.% char. The comparison of experimental measurements and model predictions shows the model’s accuracy. The CPFD simulation results had great potential to aid the future design and optimization of the fast pyrolysis process for biomass.

해마다 증가하는 폐타이어의 발생 및 그에 따른 처리 문제가 대두되는 현 상황에서 폐타이어의 재생에너지화 기술개발 중요성이 날로 증대되고 있다. 특히, 국내에서 폐타이어 처리는 시멘트 킬른 및 단순소각에 의한 열원으로의 이용이 대부분을 차지하는데 이는 연소 시 발생되는 오염물질로 인한 2차 환경오염 또한 야기하는 문제이므로 폐타이어의 안정적인 처리를 통한 재생에너지원으로서의 경제성 향상 및 환경오염 저감 등의 해결책에 관한 기술개발 필요성이 촉구되고 있다. 폐타이어를 자원화하기 위한 열적처리 기술 중 열분해 공정은 무산소의 조건에서 500℃ 정도 온도 조건으로 간접 가열하여 1~2초 이내로 반응시킨 후 고분자 물질을 분해하여 연료로 변환하는 공정으로서 연소 반응과는 달리 오염물질이 발생하지 않는 친환경적인 처리 기술이며, 공정을 통하여 생산되는 열분해오일, 카본블랙, 철심 등과 같은 유용자원의 회수는 부가가치의 창출을 통하여 경제성 향상에 이바지 할 수 있는 이점을 가지고 있다. 따라서 본 연구에서는 폐타이어의 다양한 급속열분해 운전 조건을 통하여 재생에너지화 연구를 수행하였다. 실험에는 유동층 반응기에 비하여 시료와 유동매질 간 열 및 물질전달 속도가 높고, 비교적 큰 입자도 열분해 가능하며, 내부에 분산판이 없어 압력강하량이 적은 장점을 지닌 원뿔형 분사층 반응기를 사용하였다. 폐타이어 급속열분해 실험은 반응온도와 질소유량 및 시료의 투입속도 등 여러 인자를 변수로 두어 진행하였으며, 실험을 통하여 조건별로 생산된 열분해오일 및 카본블랙의 물리-화학적 특성을 분석하여 폐타이어의 급속열분해 반응 특성을 고찰하였다. 특히, 열분해 오일은 재생에너지원으로서 연료로서의 가치가 있는지에 대하여 알아보고자 하였다.

전 세계적으로 가금류의 소비가 증가함에 따라, 가금류와 관련된 폐기물 증가해왔다. 이 가금류 관련 폐기물의 지속적으로 처리함과 동시에 에너지 회수를 위하여, 본 연구에서는 이산화탄소 조건하에서 열분해를 진행하였다. 이산화탄소의 영향을 조사하기 위해, 일반적으로 열분해 공정에서 사용되는 질소조건을 기준으로 하여, 열중량 분석, 열분해에서 발생한 가스 및 타르를 분석, 비교하였다. 먼저 열중량 분석은 25℃부터 900℃로 진행하였으며, 분석한 결과에 의하면 650℃까지 물리적인 차이가 없었다. 다음으로 이산화탄소의 화학적인 영향을 조사하기 위해, 열분해(270℃부터 720℃)에서 발생한 주요 가스인 수소, 메탄, 이산화탄소 각각의 농도에 대해 분석하였고, 최종적으로 발생한 타르의 양을 측정하였다. 이산화탄소의 효과로서 일산화탄소가 증가하고 타르발생량이 감소하였다. 이 결과에 의하면, 열분해에서 발생한 VOCs가 이산화탄소 조건에서 더 쉽게 분해되었고, 이에 따라 일산화탄소가 증가한 것으로 보여진다. 본 연구는 잠재적인 지구온난화 가스인 이산화탄소를 이용함으로써 효율적인 에너지회수를 동반한 폐기물을 처리할 수 있는 새로운 방법을 제시한다.

Converting biomass to biocrude oil has been extensively studied worldwide as a renewable energy technology and a solution to global warming caused by overuse of fossil fuels because it is a carbon neutral fuel that originates from biomass and, thus, could help prevent climate change. Fast pyrolysis is an effective technology for producing biocrude-oil, and woody biomass is usually used as feedstock. Although many studies have been performed with this feedstock, high production cost and low higher heating value (HHV) have frequently reported as challenging barriers to commercialization. Thus, coffee ground residue was selected as an alternative feedstock to overcome this barrier due to its higher HHV than other biomasses, as well as an expected improvement in the recycling rate of organic waste from many coffee shops. A kinetic study on the thermal decomposition reaction of ground coffee residue was carried out previously to investigate pyrolysis characteristics by thermogravimetric analysis, and its kinetic parameters were studied using two calculation models. A bubbling-fluidized-bed reactor was used for fast pyrolysis and the yield and characteristics of the biocrudeoil from ground coffee residue were investigated at reaction temperatures of 400-600°C. The activation energy of the decomposition reaction was calculated separately to be 41.57 kJ/mol and 44.01-350.20 kJ/mol with the above two methods. The highest biocrude-oil content was about 51.7wt% at 550°C.

산업발달로 인한 화석 연료의 급격한 사용으로 기후변화와 연료고갈 문제가 대두되고 있어 폐기물자원화 및 신재생에너지에 대한 관심이 급증하고 있다. 선행되어온 연구들은 바이오매스나 플라스틱의 대체연료 가능성 연구들로 국한되어 진행되었다. 폐플라스틱 필름의 경우 많은 연구가 진행되어 왔으나, 현재 발생되는 폐플라스틱 필름에 관한 연구는 미비한 상황이다. 많은 폐플라스틱 필름의 발생량에 비해 절반정도를 웃도는 재활용처리 비율은 다른 폐플라스틱 필름 처리방안 마련이 필요하다는 점을 시사한다. 열분해를 이용한 오일 및 화학원료 생산에 대한 관심이 높아지고 있다. 따라서 본 연구에서는 폐플라스틱 필름의 물리･화학적 특성 분석 및 열중량분석기를 통한 동역학분석과 파이롤라이저-가스크로마토그래피 /질량분석기를 이용한 반응 생성물 분석하여 폐플라스틱 필름의 열분해 공정 도입 가능성을 추가 확인하고자 한다. 또한 현재 배출되는 폐플라스틱 필름류의 열분해 특성과 어떤 성분이 생성되는지 알아보고 공정설계 기초자료로 활용되고자 폐플라스틱 필름의 열분해 특성연구를 수행하였다.

Non-CO2 온실가스인 염화불화탄소(Chlorofluorocarbons, CFCs)와 수소염화불화탄소(Hydro-Chlorofluorocarbons, HCFCs)는 오직 인류의 경제(산업) 활동에 의해 발생하며 인체에 무해하고 안정한 물질이기 때문에 냉매, 분사제, 발포제 등 여러 분야에서 다양하게 사용되었지만 오존층 파괴물질으로 국제협약인 몬트리올 의정서에 의해 생산과 사용이 규제되었다. 이에 대한 대체물질로써 수소화불화탄소(Hydrofluorocarbons, HFCs)와 과불화탄소(Perfluorinated compounds, PFCs)가 개발되었지만 여전히 높은 지구온난화지수(Global Warming Potential, GWP)를 지닌 것으로 알려져 있다. 또한 국내 HFCs 소비량은 꾸준히 증가하고 있는 추세로 HFCs 중 전기･전자제품 및 자동차에 99% 이상 냉매로 사용되는 HFC-134a(1,1,1,2-Tetrafluouroethane, CH2FCF3)는 물리･화학적으로 안정된 난처리성 물질로써 처리 시 많은 에너지(높은 온도)가 필요하며, 강산으로 알려진 불산(Hydrogen fluoride, HF)의 발생으로 처리시설의 부식을 야기시킨다. 이에 따라 HFC-134a의 안정적이고 효율적인 분해 기술 개발을 위한 연구가 필요하다 사료되며 본 연구는 수직형 관형흐름 반응기를 이용한 촉매열분해를 적용하여 촉매별 HFC-134a 분해효율 연구하고, 각 촉매별 열분해 반응 생성물의 비교를 통해 HFC-134a의 촉매열분해 특성을 알아보고자 하였다.

This paper attempted to elucidate pyrolysis reaction characteristics of waste paper laminated phenolic-printed circuit board (p-PCB). Thermogravimetric analysis was performed for the pyrolysis kinetic analysis of waste p-PCB and Pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) was also employed to analyze the product distribution of waste p-PCB pyrolysis reaction under isothermal condition (230, 350, 600oC). Kinetic analysis and isothermal Py-GC/MS results showed that the pyrolysis reaction of waste p-PCB has three reaction temperature regions: 1) low temperature decomposition region (< 280oC), 2) medium temperature decomposition region (280 ~ 380oC), 3) high temperature decomposition region (> 380oC). At the first region, triphenyl phosphate used as fire retardant, water, and phenol were vaporized. At the second region, phenolic resin, tetrabromobisphenol-A (TBBA), and laminated paper are decomposed and produce phenols, brominated compounds, and levoglucosan which were the specific pyrolysis reaction products of phenolic resin, TBBA, and laminated paper, respectively. In the final region, cresol and alkyl benzene were detected which can be considered as the decomposition products of phenolic resin. By above results, pyrolysis reaction pathway of waste p-PCB is accounted for a series reaction with four independent reactions of phosphate based frame retardant, TBBA, laminated paper, and phenolic resin.

This paper analyzed thermal and carbonization properties of sewage sludge in fixed bed reactor and obtained following results. The heavy metal (Pb, Ni, Mn, Cr, Cu) content of Char showed the highest level at unprocessed sewage sludge, followed by carbonized sludge at 600, 400, and 500oC. It was thought to be mainly due to the yield of char rather than the influence of temperature. Also, the migration-test results of heavy metals satisfied the landfill directive in all samples, which may be possible to use it as landfill cover materials. The concentration of dioxin by changes of pyrolysis temperature was higher in the low temperature conditions and the proportion of PCDDs was higher than that of PCDFs.

This research was designed to elucidate the pyrolysis reaction characteristics of waste epoxy printed circuit board (e- PCB). The samples were pulverized after removing coppers by gravity separator. Non-isothermal pyrolysis kinetic results by Thermogravimetric Analyzer (TGA) displayed two apparent reaction regions : 1) fast degradation zone and 2) slow degradation zone. According to batch experiments, solid by-products are responsible for about 78%, while liquid and gas by-products, respectively, represent 13 and 9%. The high content of solid by-products is ascribed to that of SiO2 that is a major components of e-PCB. Liquid by-products exhibit high content of oxygen (19%) and contain the nitrogen of about 1%. It is recommended that gas, liquid, and solid by-products of waste e-PCB would not be applied directly as fuels. Instead, pyrolysis of e-PCB would be applied to recover valuable rare metals and coppers from solid by-products. Application of liquid by-products is likely to be limited due to the presence of brominated oils precursor in liquid byproducts. It is necessary to develop upgrading methods for improving the quality of liquid by-products of waste e-PCB. According to kinetic analysis and product characterization, pyrolysis reaction model of waste e-PCB is accounted for by a series reaction with two independent reactions of two resins: brominated epoxy resins and non-brominated epoxy resins. At the first-stage, two resins are independently decomposed to generate thermally stable intermediates followed by slow degradation of the intermediates to be converted into char.

The pyrolysis reactions of atomic hydrogen with chloroform were studied in a 4 cm i.d, tubular flow reactor with low flow velocity (518 ㎝/sec) and a 2.6 ㎝ i.d. tubular flow reactor with high flow velocity (1227 ㎝/sec). The hydrogen atom concentration was measured by chemiluminescence titration with nitrogen dioxide, and the chloroform concentrations were determined using a gas chromatography. The chloroform conversion efficiency depended on both the chloroform flow rate and linear flow velocity, but did not depend on the flow rate of hydrogen atom. A computer model was employed to estimate a rate constant for the initial reaction of atomic hydrogen with chloroform. The model consisted of a scheme for chloroform-hydrogen atom reaction, Runge-Kutta 4th-order method for integration of first-order differential equations describing the time dependence of the concentrations of various chemical species, and Rosenbrock method for optimization to match model and experimental results. The scheme for chloroform-hydrogen atom reaction included 22 elementary reactions. The rate constant estimated using the data obtained from the 2.6 cm i.d. reactor was to be 8.1 × 10 exp (-14) ㎤/molecule-sec and 3.8 × 10 exp (-15) ㎤/molecule-sec, and the deviations of computer model from experimental results were 9% and 12%, for the each reaction time of 0.028 sec and 0.072 sec, respectively.