In this study, defects generated in the YSZ coating layer of the IN738LC turbine blade are investigated using an optical microscope and SEM/EDS. The blade YSZ coating layer is composed of a Y-Zr component top coat layer and a Co component bond coat layer. A large amount of Cr/Ni component that diffused from the base is also measured in the bond coat. The blade hot corrosion is concentrated on the surface of the concave part, accompanied by separation of the coating layer due to the concentration of combustion gas collisions here. In the top coating layer of the blade, cracks occur in the vertical and horizontal directions, along with pits in the top coating layer. Combustion gas components such as Na and S are contained inside the pits and cracks, so it is considered that the pits/cracks are caused by the corrosion of the combustion gases. Also, a thermally grown oxide (TGO) layer of several μm thick composed of Al oxide is observed between the top coat and the bond coat, and a similar inner TGO with a thickness of several μm is also observed between the bond coat and the matrix. A PFZ (precipitate free zone) deficient in γ' (Ni3Al) forms as a band around the TGO, in which the Al component is integrated. Although TGO can resist high temperature corrosion of the top coat, it should also be considered that if its shape is irregular and contains pore defects, it may degrade the blade high temperature creep properties. Compositional and microstructural analysis results for hightemperature corrosion and TGO defects in the blade coating layer used at high temperatures are expected to be applied to sound YSZ coating and blade design technology.

본 연구에서는 해양플랜트설비 건조 현장에서 사용되고 있는 기존 고온 오일 플러싱 장비에 대한 성능개선을 위해 기존의 플 러싱 장치에 사용되던 오일에 질소가스를 혼합한 고온 오일 플러싱 시스템에 대하여 국제표준화기구 코드(ISO code)를 기준으로 이론적 연구를 수행하였다. 연구를 위해 오일-질소가스 혼합유체 플러싱 시스템 공정을 설계 후 청정성능에 영향을 주는 혼합유체의 혼합비율, 온도, 레이놀즈수 및 액상분율 등에 대한 공정모사 결과도 분석하였다. 그 결과 관 직경과 가스상의 체적분률이 일정한 상태에서 혼합유 체의 체적유량이 증가될수록 수평 유압배관 입출구의 액상분율 차이  값은 증가하게 되고 배관길이 방향의 위치에 따라 오일과 질 소가스 기포 사이의 상분포가 달라짐을 확인했다. 이러한 상분포의 변화는 오일-질소가스 혼합유체 플러싱 시스템의 청정성능에도 커다 란 영향을 줄 것으로 예상된다.

The VHTR (Very High Temperature gas-cooled nuclear Reactor) has been considered as a major heat source and the most safe generation IV type reactor for mass hydrogen production to prepare for the hydrogen economy era. The VHTR satisfies goals for the GIF (Generation IV International Forum) policy such as sustainablility, economics, reliability and proliferation resistance and physical protection, and safety. As a part of a VHTR economic analysis, we have studied the VHTR construction cost and operation and maintenance cost. However, it is somewhat difficult to expect the ripple effect on the whole industry due to the lack of information about Inter-industries relationship. In many case, the ripple effect are based on experts’ knowledge or uncertain qualitative assumptions. As a result, we propose quantitative analysis techniques for ripple effects such as the production inducement effect, added value inducement effect, and employment inducement effect for VHTR 600MWt×4 modules construction and operation ripple effect based on NOAK (Nth Of A Kind). Because inducement effect values have been published annually, we predict inducement effect’s relation function and estimated values including production inducement effect value, added value inducement effect value, and employment inducement effect value using time series and estimated values are verified with published inducement effects’ value. This paper presents a new method for the ripple effect and preliminary ripple effect consequence using a time series analysis and inter-industry table. This ripple effect analysis techniques can be applied to effect expectation analysis as well as other type reactor’s ripple effect analysis including VHTR for process heat.

Gas turbines for power generating operate in a very high temperature condition and use natural gas for fuel. For this reason, many cases of damage happen at hot gas parts which are severely affected by high temperature gas and many cases of explosion occur by fuel gas. So a lot of efforts should be made to prevent hot gas parts damage and gas explosion accidents. Though there are many damage cases and explosion accidents, it is very difficult to find out the root causes of hot gas parts damage caused by gas explosion due to gas leakage in the heat exchanger for air cooling and gas heating. To prevent gas turbine from damage caused by gas explosion, removal of leakage gas from gas turbine is inevitably required before firing the gas turbine and installing alarm systems is also required for detecting gas leakage at stop valve to turbine while shut down.

Gas turbines generating power operate in high temperature condition and use natural gas as fuel. For that reason, there are many cases where damage is done to the hot gas parts caused by the high temperature and many accidents occur like gas explosions, then various efforts are needed to maintain the hot gas parts and prevent accidents. It is difficult to find the root causes of damage to the hot gas parts from the gas explosion caused by gas leakage through rotor cooling air line from fuel gas heat exchanger during the shut down. To prevent gas turbine from damage, removal of gas leakage inside of gas turbine is required by purging the turbine before firing, improving the fuel gas heating system and installing alarm systems for detecting gas leakage from stop valve to turbine while the gas turbine has shut down.

The effects of thermal treatment conditions on ADU (ammonium diuranate) prepared by SOL-GEL method, so-called GSP (Gel supported precipitation) process, were investigated for kernel preparation. In this study, ADU compound particles were calcined to particles in air and Ar atmospheres, and these particles were reduced and sintered in 4%-/Ar. During the thermal calcining treatment in air, ADU compound was slightly decomposed, and then converted to phases at . At , the phase appeared together with . After sintering of theses particles, the uranium oxide phases were reduced to a stoichiometric . As a result of the calcining treatment in Ar, more reduced-form of uranium oxide was observed than that treated in air atmosphere by XRD analysis. The final phases of these particles were estimated as a mixture of and .

The use of the gas turbine for power supply is increasing recently. Accordingly, the operation and maintenance cost of the gas turbine is gradually increasing and the various efforts to cut the cost are needed. For an operation and maintenance cost saving of the gas turbine, reductions of the new purchasing charge and the reproduction repair cost of the hot gas parts are required through more effective operation and life management methods for the hot gas parts. The hot gas parts are the main parts of the gas turbine and they are replaced with the periodic. In this research, efficient operation and life management methods for the hot gas parts were presented with the cases. The methods were analyzed and verified based on real data and the cases for improving a lifetime were utilized in the field.

본 연구에서는 고온 가열된 시멘트 페이스트에 나타나는 균열을 CO2 가스 노출을 통한 회복 거동에 대해 관찰하였다. 시 험체는 W/C 40 %의 시멘트 페이스트로 설정하였다. 전기가열로를 목표온도까지 도달시킨 후 가열로 상부에 부착하여 일면 가열을 실시한 후 가열된 면에 나타난 균열을 고배율 카메라로 촬영하였다. 촬영결과 CO2 가스 노출을 통한 회복 재령으로 인하여 시멘트 페이스트의 균열이 더 이상 진행되지 않은 것을 관찰하였다.

상업적으로 HTS (High Temperature Shift reaction) 반응에서 사용되는 Fe2O3/Cr2O3 촉매는 사용 후 6가 크롬 (Cr6+)의 침출에 따른 환경적/인체적 문제를 일으킬 수 있는 잠재성을 가지고 있어 친환경 크롬-프리 촉매개발을 위한 연구가 활발히 진행되고 있다. 본 연구에서는 크롬을 사용하지 않고 우수한 성능을 나타낼 수 있는 Fe/Al, Fe/Al/Cu, 그리고, Fe/Al/Ni 촉매를 제조하고 성능을 비교 평가하였다. 단계함침법으로 금속산화물(Cu와 Ni)과 알루미늄이 함유된 Fe계 촉매를 제조하고 촉매반응장치를 이용하여 각 촉매의 활성을 분석하였다. 그 결과 Fe/Al/Cu 촉매는 가혹한 조건(COconc. = 38.2%; 천연가스 대비 약 5.7 배 높은 CO 농도)에서도 탁월한 성능(XCO = 84.3% at 400 ℃)을 나타내었다. 이 결과는 Fe/Al/Cu 촉매의 강한 환원력과 활성종인 Fe3O4의 높은 열적 안정성에 기인한 것으로 확인되었다. 또한 강한 소결 저항성을 가진 Fe/Al/Cu 촉매는 400°C에서 100시간 동안 뚜렷한 비활성화를 보이지 않아 높은 안정성을 지닌 것으로 확인되었다.

본 연구에서는 폐자원 합성가스를 이용한 고온전이반응용 Ce가 첨가된 Cu/γ-Al2O3 촉매의 물리 화학적 특성을 비교 분석하였다. 합성방법에 따른 촉매의 특성을 비교하기 위해 활성물질의 담지 순서를 변경하여 Ce/Cu/γ-Al2O3, Ce-Cu/γ-Al2O3, Cu/Ce/γ-Al2O3, Cu/γ-Al2O3 촉매를 제조하였다. 제조된 촉매 중 Ce/Cu/γ-Al2O3 촉매가 가장 높은 활성도 및 안전성을 나타냈다. 제조된 촉매의 물리-화학적 특성은 XRD, H2-TPR, XPS, Raman, Photoluminescence 등으로 분석하였다. 그리고 CO 전환율에서도 CeO2로 첨가된 모든 Cu/γ-Al2O3 촉매는 Cu/γ-Al2O3보다 높은 CO 전환율을 보였다. 이 연구결과는 CeO2의 첨가가 고온전이반응에서 Cu/γ-Al2O3 촉매의 성능을 향상 시킨 것을 나타낸다. 또한, Ce/Cu/γ-Al2O3 촉매의 높은 촉매 활성은 주로 고농도 산소저장능 및 환원된 Cu종과 관련이 있음을 알 수 있었다.

본 연구에서는 폐기물가스화 후 생성되는 합성가스의 고순도 수소화를 위해 고온 수성가스전이반응(HT-WGS : High Temperature-Water Gas Shift) 반응용 특정 산화물(CeO2, ZrO2, TiO2 및 Al2O3)에 코발트를 담지한 촉매를 제조하고 그 산화환원특성을 비교 분석하였다. 특정 산화물에 Co를 함침법을 이용하여 담지하여 Co/CeO2, Co/ZrO2, Co/Al2O3, Co/TiO2 촉매를 각각 제조하였다. 제조된 Co 기반 촉매의 물리적 특성 분석은 BET 비표면적과 XRD 분석을 통해 수행하였고 CO 화학흡착과 H2-TPR 분석을 통해 산화환원 특성을 파악하고 동시에 물리-화학적 특성간의 상관관계를 해석하였다. H2-TPR 분석 및 CO 화학흡착 분석 결과, 코발트의 분산이 지지체 산화물의 환원성과 밀접한 상관관계를 가지고 있음을 알 수 있었다. 이 연구 결과는 Co/CeO2가 반응온도 350 ~ 550℃에서 활성 평가한 촉매 중에서 가장 우수한 활성을 나타내었다. 또한, Co/CeO2 촉매가 Co/ZrO2 및 Co/Al2O3 촉매보다 높은 촉매 활성 및 안정성을 나타내었다. Co/CeO2 촉매의 탁월한 활성 및 안정성은 지지체의 환원성과 높은 Co 금속의 분산에 기인하는 것으로 나타났다. 결과적으로 폐기물가스화로부터 생산된 합성가스를 고순도 수소로 전환하기 위한 HT-WGS 반응에서 Co/CeO2 촉매는 매우 유망한 촉매임을 알 수 있었다.

Characteristics of the exhaust gas of a commercial scale (7.2 ton/day) municipal wastes incinerator with recirculation of its high temperature combustion gas were investigated. High temperature combustion gas made by incineration was entrained by an air jet and re-used for incineration. Air was preheated to 384-512oC and diluted to have an oxygen concentration of 16-17%. Incineration of municipal wastes with the preheated and diluted air made extremely uniform and stable flames. Concentrations of nitric oxide (NOx), carbon monoxide (CO), oxygen (O2), and carbon dioxide (CO2) in flue gas were measured at the boiler exit and the stack, simultaneously. Averaged concentrations of NOx and CO were reduced to 54.2 ppm and 3.1 ppm at the boiler exit and to 49.8 ppm and 6.0 ppm at the stack, respectively, at a reference oxygen concentration of 12% without any post treatment of NOx and when the averaged outlet temperature of the combustion chamber was 904oC. The measured NOx emission was only 29% of that of a conventional municipal incinerator. Simultaneous reduction of NOx and CO is significant. Averaged concentrations of O2 and CO2 were 9.7% and 8.6% at the boiler exit and 14.6% and 4.9% at the stack, respectively.

폐기물 가스화는 폐기물 내에 포함되어있는 C, H 성분을 CO, H2가 주성분인 합성가스로 전환하는 기술이다. 가스화로부터 생산된 합성가스는 수성가스전이반응 (Water Gas Shift, CO + H2O → CO2 + H2, ΔH = -41.1 kJ mol-1) 공정을 통해 고순도 수소로 전환이 가능하다. 최근 연구 결과 보고에서 바이메탈 형태의 Ni-Cu-CeO2 촉매는 고온 수성가스전이반응에 매우 높은 활성과 선택도를 보였다. 본 연구에서는 Ni-Cu-CeO2 촉매의 제조방법 최적화를 위해 Ni-Cu-CeO2 촉매를 함침법, 공침법, 졸-겔법, 수열합성법으로 제조하고 활성을 비교 평가 하였다. 다양한 제조방법 중 졸-겔법으로 제조한 Ni-Cu-CeO2 촉매가 가장 높은 CO 전환율을 나타내었다. 이는 졸-겔법으로 제조한 촉매의 높은 표면적과 활성물질-담체간 강한 상호작용에 기인한 결과이다.

폐기물 가스화 합성가스로부터 수소를 생산하기 위해 Cu/Fe2O3, Ni/Fe2O3, 그리고 CuNi/Fe2O3 촉매를 제조하고 고온 수성가스전이반응(High temperature water gas shift reaction, CO + H2O → CO2 + H2)에 적용하였다. 제조된 촉매중 CuNi/Fe2O3 촉매가 매우 높은 공간속도 101,000 h-1에서 가장 높은 CO 전환율 (85%)을 나타내었다. CuNi/Fe2O3 촉매의 뛰어난 활성은 격자변형(lattice strain)의 증가, 격자 산소의 결합에너지 감소, 그리고 촉매 표면에 CuNi 합금의 형성에 기인한 결과이다.

It is known that lowering of peak temperature of flame reduces NOx emission in combustion process. Low oxygenconcentration of diluted combustion air reduces peak flame temperature, but makes flame unstable. So increasing oftemperature of reactants is needed to enhance flame stability. Mixing of high temperature combustion gas with combustionair makes low oxygen concentration and increases air temperature simultaneously. Low oxygen concentration ofcombustion air reduces peak temperature of flame and increased air temperature makes flame stable by enhancement ofcombustion reaction. Special apparatus for recirculation of high temperature combustion gas should be needed, becausegeneral blower cannot be used to return the gas of almost 1,000oC. Air jet type recirculation apparatus has been developedand installed in a commercial scale of 7.2ton/day incinerator and estimated. Oxygen concentration and temperature ofair mixed with inhaled high temperature combustion gas by the apparatus are 16.24~17.78%, 384~512oC, respectively,in a steady state of incineration.