• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.647-653
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• 2007

The ultimate objective of this study is to develop a reliable oxygen-enriched combustion techniques especially for the case of the flue gas recycling in order to reduce the $CO_2$ emissions from practical industrial boilers. To this end a systematic numerical investigation has been performed, as a first step, for the resolution of the combusting flame characteristics of lab-scale LNG combustor. One of the important parameters considered in this study is the level of flue gas recycling calculated in oxygen enriched environment. As a summary of flame characteristics, for the condition of 100% pure $O_2$ as oxidizer without any flue gas recycling, the flame appears as long and thin laminar-like shape with relatively high flame temperature. The feature of high peak of flame temperature is explained by the absence of dilution and heat loss effects due to the presence of $N_2$ inert gas. The same reasoning is also applicable to the laminarized thin flame one, which is attributed to the decrease of the turbulent mixing. These results are physically acceptable and consistent and further generally in good agreement with experimental results appeared in open literature. As the level of $CO_2$ recycling increases in the mixture of $O_2/CO_2$, the peak flame temperature moves near the burner region due to the enhanced turbulent mixing by the increased amount of flow rate of oxidizer stream. However, as might be expected, the flue gas temperature decreases due to presence of $CO_2$ gas together with the inherent feature of large specific heat of this gas. If the recycling ratio more than 80%, gas temperatures drop so significantly that a steady combustion flame can no longer sustain within the furnace. However, combustion in the condition of 30% $O_2/70% $ $CO_2$ can produce similar gas temperature profiles to those of conventional combustion in air oxidizer. An indepth analyses have been made for the change of flame characteristics in the aspect of turbulent intensity and heat balance.

• Journal of Welding and Joining
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• v.12 no.1
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• pp.51-58
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• 1994

Amount of spatter, welding conditions and welding costs were investigated for MAG welding. $CO_2$, Ar+18%;$CO_2$ and Ar+8%$O_2$ were used for shielding gases. As results, arc characteristics and appropriate range for welding were obtained. Amount of spatter in Ar+18%$CO_2$ gas welding was 20% of that of $CO_2$ welding, and Ar+8%$O_2$ was 10% of that of $CO_2$ welding. Therefore by using Ar+18%$CO_2$and Ar+8%$O_2$ gases, welding costs could be reduced compared with $CO_2$ welding due to avoiding spatter.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.103-103
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• 2006

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.04a
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• pp.107-110
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• 1996

연료전지 발전방식중 용융탄산염형 연료전지 발전방식은 동작온도가 $650^{\circ}C$의 고온에서 동작되기 때문에 발전효율이 높고 석탄가스를 연료로 사용할 수 있으며 또한 배기가스를 이용하여 복합발전시스템으로 구성할 수 있는 등 전력사업에 적용가능성이 가장 큰 새로운 발전방식이다. 이와 같은 이유로 전력연구원에서 개발하고 있는 2kW급 용융탄산염형 스택은 전극유효면적이 1,000$ extrm{cm}^2$인 단위전지를 20단 적층한 Co Flow형 MCFC스택으로, 연료로, 연료극에 H2, CO2, H2O 혼합가스를 그리고 산소극에는 공기, CO2 혼합가스를 이용하여 150A 정부하 상태에서 초기성능이 전압 14.28V, 출력 2.142W의 발전 운전시험에 성공하였고 이때 스택의 단위전지 평균전압은 0.714V를 나타내었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.227-235
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• 2003

The WSGG-based narrow band model was employed to solve the radiative transfer equations along isothermal and non-isothermal paths through $CO_2-H_2O-N_2$ gas mixtures at 1 atm. When the WSGGM is applied for arbitrary gas mixtures by considering the multiplication property of transmissivity in overlapping bands, the number of gray gases is significantly increased. To reduce the computation time, three different regrouping methods for the gray gases are tested in obtaining the mean absorption coefficient for each gray gas group. Among them, the regrouping method by minimizing the regrouping error shows the best results. For the isothermal media, 10 gray gases show fairly good agreement with the results by statistical narrow band(SNB) model which are regarded as reference solutions. For non-isothermal media, 20 gray gases show good agreement with reference solutions.

• Clean Technology
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• v.17 no.2
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• pp.142-149
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• 2011

The adsorption and desorption behaviors of NO and $N_2O$ over two mixed oxide catalysts, AlCoPd (1/1/0.05) and AlCoFe (1/1/2), have been investigated for the lean $NO_x$ trap applications. The catalysts showed good adsorption capabilities for NO and $N_2O$ without needing oxidation step. The adsorption decreased a lot when they are co-adsorbed with oxygen. While NO kept high adsorbability and selectivity with respect to oxygen, those of $N_2O$ decreased sharply. From the TPD results, NO and $N_2O$ are considered to decompose into nitrogen and oxygen in the higher temperature range and the oxygen seems to be strongly attached to the catalysts even at high temperature.

• Resources Recycling
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• v.29 no.3
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• pp.3-10
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• 2020

The chlorination kinetics of synthetic rutile prepared by selective chlorination of ilmenite with Cl₂ and CO gas mixture were studied in a fluidized bed. Th e effects of reaction temperature, reaction time, and the ratio of Cl₂ and CO partial pressure ($p_{Cl_2}/p_{CO}$) on the conversion rate of TiCl₄ were investigated. The conversion rate of TiC₄ was low under the high $p_{Cl_2}/p_{CO}$ conditions. Moreover, it was considered that the partial pressure of CO gas was more effective than that of Cl₂ gas when comparing the stoichiometric conversion rate and experimental results of high CO partial pressure. Considering the porous structure of particles, the rate controlling step of the chlorination of synthetic rutile was determined to be chemical reaction and the activation energy was calculated as 53.77 kJ/mol.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.476-482
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• 1997

A portable electronic nose system has been fabricated and characterized using an oxide semiconductor gas sensor array and pattern recognition techniques such as principal component analysis and back-propagation artificial neural network. The sensor array consists of six thick-film gas sensors whose sensing layers are Pd-doped $WO_{3}$, Pt-doped $SnO_{2}$, $TiO_{2}-Sb_{2}O_{5}-Pd$-doped $SnO_{2}$, $TiO_{2}-Sb_{2}O_{5}-Pd$-doped $SnO_{2}$ + Pd coated layer, $Al_{2}O_{3}$-doped ZnO and $PdCl_{2}$-doped $SnO_{2}$. The portable electronic nose system consists of an 16bit Intel 80c196kc as CPU, an EPROM for storing system main program, an EEPROM for containing optimized connection weights of artificial neural network, an LCD for displaying gas concentrations. As an application the system has been used to identify 26 carbon monoxide/hydrocarbon (CO/HC) car exhausting gases in the concentration range of CO 0%/HC 0 ppm to CO 7.6%/HC 400 ppm and the identification has been successfully demonstrated.

• Journal of Energy Engineering
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• v.4 no.3
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• pp.379-386
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• 1995

0.5 T/D 용량의 슬러리를 이용한 분류층가스화기에서의 인도네시아 탄인 Roto탄을 이용한 가스화 실험을 통하여 개발된 가스화기의 성능과 석탄가스화 특성을 파악하였다. 200 mesh 이하로 분쇄된 미분탄을 62.5%(H2O/coal=0.6)로 물과 혼합된 슬러리를 0.5%의 유도화제와 화재의 20%의 CaO를 화재의 융점강하를 위하여 첨가시켰다. 화재의 융점이 1511$^{\circ}C$에서 130$0^{\circ}C$까지 떨어진 것이 관측되었다. 생성된 슬래그는 Quenching 부위에서 물에 의한 급랭으로 인한 열 충격으로 1~2 cm의 크기로 분쇄되었다. 실험결과 생성된 가스는 CO는 O2/coal의 비가 증가할수록 감소하였고, H2 및 CO2는 증가하는 것으로 관찰되었다. 생성된 가스의 발열량은 천연가스의(10,000 Kcal/Nm3)/약 1/8인 1700~1300 Kcal/Nm3로 측정되었다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.361-363
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• 2008

탄소 개질반응은 $1200^{\circ}C$(도1) 이상에서 모든 탄화물질과 수분 또는 $CO_2$ 사이에서 흡열/환원반응이 일어나서 합성가스를 생성한다. 개질반응로는 산화반응로와 연결되어, 수소가스와 CO 가스의 혼합인,합성가스가 산화반응로 내에서 산소가스와 연소하여 열과 $H_2O+CO_2$를 생성하여 환원 반응로 내로 유입되어, 환원 반응로를 $1200^{\circ}C$ 이상으로 유지하고, $H_2O$와 $CO_2$는 석탄 속의 모든 탄소를 CO로 개질한다(도2). 동시에 수소가스가 생성되어 합성가스를 생성하게 된다. 석탄 속의 비탄소 물질인 슬래그(Slag)는 개질로 내에 남게 되는데, 개질로를 슬래그 융점(non-fluid point) 이하에서 고체상태로 포집함으로서 Fly-ash로 처리된다. 개질로 내의 온도를 $1200{\sim}1300^{\circ}C$(석탄 슬래그 융점)로 유지함으로서 개질반응이 지속되어 합성가스가 생성된다. IGCC 시스템에서는 합성가스를 가스터빈 속에서 $O_2E가스와 연소하여 고온의 가스를 생성하여 터빈을 가동해 발전을 하고 배출가스를 $1500{\sim}1700^{\circ}C$에서 배출한다. 재래식 IGCC(도4)에서는 ${\sim}1500^{\circ}C$의 배출가스를 열교환 시스템에 의해 증기를 생성하여 Steam turbine(증기터빈)을 가동하여 추가 전력을 생산했다. 그러나 본 시스템에서는 배출가스(증기와 $CO_2E 가스)를 위의 개질로에 유입하여 개질로 온도를 $1200{\sim}1300^{\circ}C$로 유지함으로서 더 많은 합성가스를 생성 하게 된다(도3). 이렇게 하여 Oxidation-reduction cycle을 형성하게 된다. 새로운 IGCC 시스템에서 가스 터빈의 배출가스가 석탄 개질로에 연결되고 석탄개질로의 합성가스 출구가 가스터빈의 가스 입구에 연결됨으로서,외부에너지 주입 없이 지속 가능한 가스화 반응과 터빈 사이클(Cycle)을 완성하여 IGCC 시스템의 석탄 열효율을 1단계 상승시켰다. 이렇게 설계된 석탄가스화기는 Lurgi형 석탄가스화 기와 달리 석탄개질반응의 효율을 높일 수 있고, 슬래그 처리가 간단하기 때문에 석탄가스화기가 소형화 될 수 있으며 슬래그(Slag)용융에 따른 석탄가스화기의 외벽손상을 피할 수 있다.