• 한국수소및신에너지학회논문집
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• 제22권1호
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• pp.21-28
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• 2011

Fe, Ni and Co, typical active components, were dispersed on $Al_2O_3$ and $TiO_2$ for $SO_3$ decomposition. $SO_3$ decomposition was conducted at the temperature ranges from $750^{\circ}C$ to $950^{\circ}C$ using the prepared catalysts. Alumina based catalysts showed the surface areas higher than Titania based catalysts, which resulted from spinel structure formation of alumina based catalysts. Catalytic $SO_3$ decomposition reaction rates were in the order of Fe>Co${\gg}$Ni. The metal sulfate decomposition temperature were in the order of Ni>Co>Fe from TGA/DTA analysis of metal sulfate. During $SO_3$ decomposition, metal sulfate can form on the catalysts. $SO_2$ and $O_2$ can be produced from the decomposition of metal sulfate. In that point of view, the less is the metal sulfate deomposition temperature, the higher can be the $SO_3$ decomposition activity of the metal component. Therefore, it can be concluded that metal component with the low metal sulfate decomposition temperature is the pre-requisite condition of the catalysts for $SO_3$ decomposition reaction.

• Nuclear Engineering and Technology
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• 제41권10호
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• pp.1275-1284
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• 2009

A directly heated $SO_3$ decomposer for the sulfur-iodine and hybrid-sulfur processes has been introduced and analyzed using the computational fluid dynamics (CFD) code CFX 11. The use of a directly heated decomposition reactor in conjunction with a very high temperature reactor (VHTR) allows for higher decomposition reactor operating temperatures. However, the high temperatures and strongly corrosive operating conditions associated with $SO_3$ decomposition present challenges for the structural materials of decomposition reactors. In order to resolve these problems, we have designed a directly heated $SO_3$ decomposer using RA330 alloy as a structural material and have performed a CFD analysis of the design based on the finite rate chemistry model. The CFD results show the maximum temperature of the structural material could be maintained sufficiently below 1073 K, which is considered the target temperature for RA 330. The CFD simulations also indicated good performance in terms of $SO_3$ decomposition for the design parameters of the present study.

• 한국안전학회지
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• 제15권2호
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• pp.70-77
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• 2000

For hazardous air pollutants(HAP) such as NO, $NO_2$ and $SO_2$ decomposition efficiency, power consumption, and applied voltage were investigated by SPCP(Surface induced discharge Plasma Chemical Processing) reactor to obtain optimum process variables and maximum decomposition efficiencies. Decomposition efficiency of HAP with various electric frequencies(5~50 kHz), flow rates(100~1,000 mL/min), initial concentrations(100~1,000 ppm) and additive($CH_4$) were measured and the products were analyzed with FT-IR. Experimental results showed that for the frequency of 10 kHz, the highest decomposition efficiency of 94.3 % for NO, 84.7 % for $NO_2$ and 99 % far $SO_2$ were observed at the power consumptions of 19.8, 20 and 19W, respectively, and that decomposition efficiency decreased with increasing frequency above 20 kHz. And decomposition efficiency per unit power were 5.21 %/W for $SO_2$, 4.76 %/W for NO and 4.24 %/W for $NO_2$ and the highest decomposition efficiency was observed with $SO_2$. Decomposition efficiency was increased with increasing residence times and with decreasing initial concentration of pollutants. When the additive of $CH_4$ was used, decomposition efficiency was increased with increasing $CH_4$ content, and NO, $NO_2$ and $SO_2$ were almost completely decomposed with the efficiency of 99 %, 98 % and 99 %, respectively and therefore $CH_4$ was a good additive material. The optimum power for the maximum decomposition efficiency were 7.5 W for $SO_2$, 9.5 W for NO and 15.5 W for $NO_2$, respectively. Optimum power with the maximum decomposition efficiency were 9.5 W at 1,000 ppm of NO, 7~8 W at 100~500 ppm of NO and 15.5 W at all concentration range of $NO_2$ and 11.5 W at 1,000 ppm, 4.9 W at 500 ppm, 3.7 W at 100~300 ppm of $SO_2$ and power efficiency was best in these case.

• 대한수학회논문집
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• 제10권3호
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• pp.735-750
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• 1995

We present a domain decomposition algorithm for solving large sparse linear systems of equations arising from queuing networks. Such techniques are attractive since the problems in subdomains can be solved independently by parallel processors. Many of the methods proposed so far use some form of the preconditioned conjugate gradient method to deal with one large interface problem between subdomains. However, in this paper, we propose a "nested" domain decomposition method where the subsystems governing the interfaces are small enough so that they are easily solvable by direct methods on machines with many parallel processors. Convergence of the algorithms is also shown.lso shown.

• 한국응용과학기술학회지
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• 제24권3호
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• pp.296-300
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• 2007

This paper presents applicability of photocatalytic decomposition of methyl mercaptan using $TiO_2$. A quartz reactor was used in order to elucidate reaction pathway in photocatalytic decomposition of methyl mercaptan. Experimental results showed that more than 99.9% of methyl mercaptan was decomposed within 30 minutes. It was found that the photocatalytic decomposition of methyl mercaptan followed pseudo first order and its reaction coefficient was $0.05min^{-1}$ During 30 minutes in the photocatalytic reaction, the concentration of methyl mercaptan, dimethyl disulfide, $SO_2$, $H_2SO_4$, COS, $H_2S$ were determined. These results showed that 64% of methyl mercaptan were compensated for the increase in sulfur after 30 minutes through the mineralization. The proposed main photocatalytic decomposition pathway of methyl mercaptan was methyl $mercaptan{\rightarrow}dimethyl$ $disulfide{\rightarrow}SO_2{\rightarrow}H_2SO_4$.

• 자원리싸이클링
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• 제7권5호
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• pp.33-40
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• 1998

명반석[$K_2$$SO_4$.$Al_2$($SO_4$)$_3$.(OH)$4Al_3$]과 석회석(CaCo$_3$)의 혼합소성에서 무수석고(CaSO$_4$)의 생성은 주로 $SO_3$(g)와 CaO(s)가 발생되는 온도와 속도에 의존된다. 그러므로 본 연구에서는 먼저 명번석의 열분해로 생성되는 물질과 $SO_3$(g)가 이탈되는 온도와 속도를 조사하였다. 상압의 공기분위기에서 명반석은 $500~580^{\circ}C$에서 탈수되어 (SO$KAl_4$)$_2$와 $Al_2$$O_3$로 분해된다. 이때에 탈수되는 속도는 kt=${1-(1-{alpha}^{1/3})}^{2}}$에 일치하고, 탈수 활성화에너지는 약 73.01kcal/mol로 계산된다. $SO_3$(g)는 $580~700^{\circ}C$에서도 서서히 발생되지만 $700~780^{\circ}C$에서는 급격히 발생된다. KAl($SO_4$)$_2$가 분해되는 속도는 kt=$1-{(1-{alpha})}^{1/3}$에 일치하며, 분해활성화에너지는 약 66.84kcal/mol로 계산된다. 명반석광석에 함유된 $SiO_2$와 kaolinite는 $SO_3$(g)의 발생온도 및 속도에는 거의 영향을 끼치지 않는다.

• 한국화재소방학회논문지
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• 제18권4호
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• pp.52-56
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• 2004

Methyl Ethyl Ketone Peroxide의 열분해 특성을 파악하기 위하여 TG-DIA의 실험장치를 사용하여 공기 분위기 중에서 실험을 하였다. 그 결과 MEKPO에 98% H₂SO₄의 첨가량이 증가할수록 분해개시온도는 낮아졌으며, MEKPO의 열분해 최대온도는 116.8℃였다. 미분법에 의하여 얻어진 값으로부터 구한 활성화 에너지는 MEKPO와 MEKPO에 98%H₂SO₄ 1%, 3%, 5%를 첨가했을 경우에 각각 0.576㎉/㏖, 0.355㎉/㏖, 0.284㎉/㏖ 및 0.258㎉/㏖을 구하였다.

• 방사성폐기물학회지
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• 제5권3호
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• pp.221-227
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• 2007

음이온교환수지인 IRN-78및 IRN-77과의 혼합 수지를 액체 상태로 직접 분해 처리하기 위하여 Fenton 시약을 이용하였다. 개선된 분해방법의 특징은 수지를 먼저 건조시키고 $FeSO_4$ 용액을 수지에 완전히 흡수시킨 후 일정량의 $H_2O_2$를 첨가하여 분해반응을 유도하는 방법을 적용하였다. 촉매로서 $CuSO_4,\;Cu(NO_3)_2$ 및 IRN-77 수지의 분해시 사용한 $FeSO_4$를 각각 사용하여 각 이온교환수지의 단독 및 혼합수지의 분해에 필요한 적절한 촉매와 그의 농도 및 $H_2O_2$의 소요량을 측정하였다. IRN-78 수지에 대해 $CuSO_4$ 촉매를 사용한 경우, 초기 분해반응을 유도하기 위해 $40^{\circ}C$까지 가열이 필요하였으며, 반응유도시간은 촉매의 적정온도에서 약 20분 이내 개시되는 것으로 나타났다. 동 수지에 $FeSO_4$를 사용한 경우에는 가열 없이 즉시 분해반응이 진행되었으며 분해율도 수% 높게 나타났다. 결론적으로 IRN-78 및 IRN-77과의 혼합수지의 분해를 위한 최적 촉매는 $FeSO_4$로 나타났으며 가열하지 않고 상온에서 반응유도시간 없이 각 수지를 단독으로 분해한 경우보다 적은 양의 $H_2O_2$로 완전히 액상으로 분해시킬 수 있는 좋은 결과를 얻었다. 또한 이들 각각의 수지 및 혼합수지에 대한 적절한 촉매 및 적정 농도와 완전분해에 필요한 $H_2O_2$의 양을 제시하였다.

• 한국안전학회지
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• 제21권6호
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• pp.38-45
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• 2006

Polymeric floorings mainly consisted of PVC are easily decomposed by many kinds of hot environmental factors, then generate hazardous asphyxiate gases and/or toxic gases etc. Therefore the mechanism of decomposition and quantitative toxic indices of products are very important for preventing safety and health disasters, especially in case of confined area. So we have investigated decomposition kinetics, numbers of process involved, toxicity indices of product and so on, using DSC, TGA, FT-IR and Pyrolyzer-GC/MS. The thermal decomposition process of polymeric floorings can be mainly divided by dehydrochlorinated reaction and polyene decomposition step, and activation energies of those are approximately $53.93{\sim}62.42kcal/mol$. Especially lethal concentration($LC_{50}$), fractional effective dose (FED) are calculated by measuring the amount of decomposition product. The values on $LC_{50}$ of sample G are ranged $2,003{\sim}2,019(mg/m^{3})$ in case of sample K and H are $1,877,\;1,998(g/m^{3})$ respectively. Even if the results are estimated by calculation method without animal test and/or clinical demonstration, these values could be very useful data for occupational health, hygiene and safety control.

• 공업화학
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• 제17권5호
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• pp.490-497
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• 2006

$V_{2}O_{5}$/$TiO_{2}$계 선택적촉매환원법(SCR) 촉매는 $SO_{2}$가 존재하는 조건에서 $SO_{2}$의 산화 및 암모니아의 반응에 의해 형성된 황산암모늄염으로 인해 촉매는 비활성화될 수 있다. 본 연구에 의하면, $SO_{2}$에 의한 촉매의 비활성화는 $SO_{2}$의 흡착이후 $SO_{3}$로의 산화 정도에 의존한다. $SO_{2}$의 산화는 배가스 내의 산소 농도에 약하게 영향을 받으며 바나듐 함량에 영향을 받는다. 또한 미반응 암모니아 역시 황산암모늄염 형성의 원인이므로 SCR 반응에 있어서 암모니아 투입비율에 대한 영향을 도출하였다. 황산암모늄염에 의해 비활성화된 촉매가 낮은 SCR 활성을 갖는 이유를 촉매의 기공부피 변화에서 찾을 수 있다. 이러한 황산암모늄염의 분해 반응도출을 위해 TPD (Temperature Programmed Decomposition) 실험이 수행되었다.