• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.113.1-113.1
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• 2010

IGCC(Integrated Coal Gasification and Combined Cycle) plants can be among the most advanced and environmental systems for electric energy generation from various feed stocks and is becoming more and more popular in new power generation fields. In this work, the performance of IGCC plants employing Shell gasification technology and a GE 7FB gas turbine engine was simulated using IPSEpro open-equation modeling environment for different operating conditions. Performance analyses and comparisons of all operating cases were performed based on the design cases. Discussions were focused on gas composition, syngas production rate and overall performance. The validation of key steady-state performance values calculated from the process models were compared with values from the provided heat and material balances for Shell coal gasification technology. The key values included in the validation included the inlet coal flow rate; the mass flow rate, heating value, and composition of major gas species (CO, H2, CH4, H2O, CO2, H2S, N2, Ar) for the syngas exiting the gasifier island; and the HP and MP steam flows exiting the gasifier island.

• Korean Chemical Engineering Research
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• 제51권4호
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• pp.506-512
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• 2013

바이오매스 및 저등급 석탄인 갈탄은 잠재력이 큰 에너지원으로 이들을 가스화하여 합성가스를 얻으면 발전을 하거나 수송용 연료를 생산할 수 있다. 본 연구에서는 상압의 열천칭 반응기(thermobalance)에서 woodchip, 톱밥, 갈탄의 수증기 가스화반응의 kinetics를 조사하였다. 가스화 온도 $600{\sim}900^{\circ}C$, 수증기 분압 20~90 kPa 범위에서 수증기 가스화 반응을 수행하였다. 세 가지의 기체-고체 화학반응모델들이 가스화반응의 거동을 묘사하는 능력을 비교하였다. 이들 중에서 탄소전환율의 변화를 가장 잘 나타내는 modified volumetric model을 사용하여 가스화반응의 kinetic 정보를 도출하였다. Arrehenius plot으로부터 얻어진 시료들의 활성화에너지는 문헌상의 범위 내에서 얻어졌으며 톱밥 > woodchip > 갈탄의 순으로 나타났다. 각 시료에 대하여 수증기 분압에 대한 반응차수를 결정하였으며, 가스화공정 설계의 기초 데이터로서 겉보기 반응속도식을 제시하였다.

• Nuclear Engineering and Technology
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• 제33권2호
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• pp.241-253
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• 2001

Under severe accidents, the pressure and temperature response has an important role for the integrity of a nuclear power plant containment. The history of the pressure and temperature is characterized by the amount and state of steam/air mixture in a containment. Recently, the heat transfer rate to the structure surface is supposed to be increased by the wavy interface formed on condensate film. However, in the calculation by using CONTAIN code, the condensation heat transfer on a containment wall is calculated by assuming the smooth interface and has a tendency to be underestimated for safety. In order to obtain the best- estimate heat transfer calculation, we investigated the condensation heat transfer model in CONTAIN 1.2 code and adopted the new forced convection correlation which is considering wavy interface. By using the film tracking model in CONTAIN 1.2 code, the condensate film is treated to consider the effect of wavy interface. And also, it was carried out to investigate the effect of the different cell modelings - 5-cell and 10-cell modeling - for KNGR(Korean Next Generation Reactor) containment phenomena during a severe accident. The effect of wavy interface on condensate film appears to cause the decrease of peak temperature and pressure response . In order to obtain more adequate results, the proper cell modeling was required to consider the proper flow of steam/air mixture.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.589-596
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• 2013

In a pressurized heavy water reactor, following loss of the primary coolant, severe core damage would begin with the depletion of the liquid moderator, exposing the top row of internally-voided fuel channels to steam cooling conditions on the inside and outside. The uncovered fuel channels would heat up, deform and disassemble into core debris. Large inventories of water passively reduce the rate of progression of the accident, prolonging the time for complete loss of engineered heat sinks. The efficacy of available backup and ultimate heat sinks, available in a CANDU 6 reactor, in mitigating the consequences of a prolonged station blackout scenario was analysed using the MAAP4-CANDU code. The analysis indicated that the steam generator secondary side water inventory is the most effective heat sink during the accident. Additional heat sinks such as the primary coolant, moderator, calandria vault water and end shield water are also able to remove decay heat; however, a gradually increasing mismatch between heat generation and heat removal occurs over the course of the postulated event. This mismatch is equivalent to an additional water inventory estimated to be 350,000 kg at the time of calandria vessel failure. In the Enhanced CANDU 6 reactor ~2,040,000 kg of water in the reserve water tank is available for prolonged emergencies requiring heat sinks.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1505-1515
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• 2009

A new method to semicontinuously determine $PM_{2.5}$ ionic species with a short time resolution is described in detail. In this system, a particle collection section (mixing part, particle collection chamber, and air/liquid separator) was developed. A Y-type connector was used to mix steam and an air sample. The particle collection chamber was constructed in the form of a helix coil and was cooled by a water circulation system. Particle size growth occurred due to the high relative humidity and water absorbed particles were efficiently collected in it. Liquid samples were drained out with a short residence time (0.08-0.1 s). The air/liquid separator was also newly designed to operate efficiently when the flow rate of the air sample was 16.7 L $min^{-1}$. For better performance, the system was optimized for particle collection efficiency with various types of test aerosols such as ($NH_4)_2SO_4,\;NaCl,\;NH_4HSO_4,\;and\;NH_4NO_3$. The particle collection efficiencies were almost 100% at different concentration levels in the range over 500 nm in diameter but 50-90% in the range of 50-500 nm under the following experimental conditions: 15 coil turns, a water flow rate for steam generation of 0.65 mL $min^{-1}$, and an air sample flow rate of 16.7 L $min^{-1}$. Finally, for atmospheric applications, chemical compositions of $PM_{2.5}$ were determined with a time resolution of 20 min on January 11-24, 2006 in Seoul, Korea, and the chemical characteristics of $PM_{2.5}$ ions were investigated.

• 한국수소및신에너지학회논문집
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• 제30권1호
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• pp.21-28
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• 2019

Reversible solid oxide fuel cell (ReSOC) system was integrated with waste steam for electrical energy storage in distributed energy storage application. Waste steam was utilized as external heat in SOEC mode for higher hydrogen production efficiency. Three system configurations were analyzed to evaluate techno-economic performance. The first system is a simple configuration to minimize the cost of balance of plant. The second system is the more complicated configuration with heat recovery steam generator (HRSG). The third system is featured with HRSG and fuel recirculation by blower. Lumped models were used for system performance analyses. The ReSOC stack was characterized by applying area specific resistance value at fixed operating pressure and temperature. In economical assessment, the levelized costs of energy storage (LCOS) were calculated for three system configurations based on capital investment. The system lifetime was assumed 20 years with ReSOC stack replaced every 5 years, inflation rate of 2%, and capacity factor of 80%. The results showed that the exergy round-trip efficiency of system 1, 2, 3 were 47.9%, 48.8%, and 52.8% respectively. The high round-trip efficiency of third system compared to others is attributed to the remarkable reduction in steam requirement and hydrogen compression power owning to fuel recirculation. The result from economic calculation showed that the LCOS values of system 1, 2, 3 were 3.46 ¢/kWh, 3.43 ¢/kWh, and 3.14 ¢/kWh, respectively. Even though the systems 2 and 3 have expensive HRSG, they showed higher round-trip efficiencies and significant reduction in boiler and hydrogen compressor cost.

• 공업화학
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• 제10권2호
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• pp.190-195
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• 1999

테트라 플로오르에틸렌의 제조를 위한 클로로디플루오르메탄 (R22) 열분해 반응에 대해 저자들이 고안한 관형 반응기에서 반응온도 ($600{\sim}850^{\circ}C$), 체류시간 (0.005~0.6초) 및 희석비 (수증기/R22, 3~30)를 변수로 하여 전환율, 테트라플로오로에틸렌의 수율 및 선택도에 대한 영향을 고찰하였다. 이상의 결과로부터 이 반응기의 최적조업 및 설계를 위한 지침을 제시하였다. 반응온도는 $700{\sim}750^{\circ}C$, 체류시간은 0.07~0.1초일 때 최적 조업 조건이었다. 희석제인 과열 수증기의 사용은 반응 전환율 뿐만 아니라, TFE의 선택도도 증진시키는 것으로 나타났다. 속도론적 분석을 통하여 R22열분해 반응의 주반응이 $CF_2$ 라디칼 생성반응인 것인 것을 보였으며, 1차 속도식으로 잘 표현되었다. 이 주반응의 활성화 에너지는 44.7~48 kcal/mol이었다.

• 공업화학
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• 제19권2호
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• pp.157-160
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• 2008

탄화수소 계열의 연료로부터 고순도의 수소를 생산하는 것은 연료전지의 효율적인 운전과 밀접하다. 일반적으로 대부분의 탄화수소 연료에서 수소를 생산하는 과정은 수소, 일산화탄소, 이산화탄소와 수증기 혼합물이 생성되는 개질 과정 및 일산화탄소를 저감하는 전이반응과 선택적 산화반응 과정으로 구성되어 있다. 전이반응은 일산화탄소를 이산화탄소로 전환하는 동시에 수소가 생성되는 고온 전이와 저온전이로 구성된 두 단계의 촉매전환 공정이다. 일반적으로 개질기에서 생성된 개질 가스는 고온전이 반응기를 거쳐 일산화탄소 농도를 3~5%까지 저감한다. 본 연구에서는 고온전이 반응기를 설계 및 제작하여 일산화탄소 농도를 2~4%까지 저감하였다. 고온전이 반응에서 철이 첨가한 촉매(G-3C)를 사용하여 부분산화 개질에서 생성된 일산화탄소를 이산화탄소로 전환하였다. 그리고 고온전이 영향인자인 수증기 주입량, 개질 가스 조성, 반응온도, 개질 가스 주입량변화에 대한 연구를 진행하였다.

• 설비공학논문집
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• 제17권4호
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• pp.325-332
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• 2005

This paper addresses the development of a scroll expander for power generation from relatively low temperature steam source. It has a double-sided orbiting scroll member so that no thrust bearing is needed to support the base plate of the orbiting scroll. Three power transmission shafts are placed at the periphery of the orbiting scroll base plate, and these shafts can also function as anti-rotation devices. Final output is obtained from the main central shaft engaged with the three power transmission shafts through gear assembly. The clearance between the fixed and orbiting scroll elements was estimated by comparing measurement of the mass flow rate with calculation results of a computer simulation. Due to large clearance, the expander total and volumetric efficiencies were measured to be $34\%\;and\;43\%$, respectively. It has been shown through the computer simulation that the total and volumetric efficiencies could be improved to $65\%\;and\;83\%$, respectively, if the current clearance is reduced by half.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.329-330
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• 2009

Food waste contains almost no heavy metals and high fuel ratio 0.14-0.17 that makes it a good candidate for solid fuel. Thermogravimetric analysis showed that volatile matter volatilizes at $200-400^{\circ}C$, and ignition temperature is $460^{\circ}C$. Combustion efficiency measured from energy balance before and after combustion was over 99%. Pulverized fuel made from food waste is a new and renewable energy which contribute to low carbon green economic growth.