• Membrane and Water Treatment
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• 제9권6호
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• pp.435-445
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• 2018

In this work, desalination experiments were performed on vacuum membrane distillation (VMD). Process parameters such as feed flow rate, vacuum degree on permeate side, feed bulk temperature and feed salt concentration were optimized using sensitivity analysis and Taguchi method. The optimum values of process parameters were found to be 2 lpm of feed flow rate, $60^{\circ}C$ of feed bulk temperature, 5.5 kPa of permeate-side pressure and 5000 ppm of salt concentration. The permeate flux at these conditions was obtained as $26.6kg/m^2{\cdot}hr$. The rejection of salt in permeate was found to be 99.7%. The percent contribution of various process parameters using ANOVA results indicated that the most important parameter is feed bulk temperature with its contribution of 95%. The ANOVA results indicate that the percent contribution of permeate pressure gets increased to 5.384% in the range of 2 to 7 kPa as compared to 0.045% in the range of 5.5 to 7 kPa.

• 에너지공학
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• 제17권1호
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• pp.15-22
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• 2008

본 연구는 감압증류장치(Vacuum Distillation Unit)를 이용하여 캐나다산 아사바스카 오일샌드 역청 (Athabasca Oilsands Bitumen)의 증류액(Distillates)및 잔사유(Residue)에 대한 물리화학적 특성변화를 살펴보기 위하여 수행되었다. 감압증류장치를 이용하여 생성된 증류액 및 잔사유의 원소분석, SARA 분석, 비점분포 분석, 분자량 측정, API 비중 등을 측정하였으며, 감압증류실험장치는 6 l 용량의 Vessel, 충진컬럼, 응축기, 리플럭스, 증류액 포집플라스크, 온도제어장치 등으로 구성되었다. 증류액의 구분 조건은 최대 감압 및 최대 $320^{\circ}C$의 승온조건 하에 총 4단계로 수행되었다. 분석 결과 오일샌드 역청에 비해 증류액의 황분 및 평균분자량은 현저히 감소하였다. 증류액의 온도가 고온으로 갈수록 증류액의 수소함량은 감소하고, 황 함량 및 평균분자량은 증가하는 경향을 보였다.

• 상하수도학회지
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• 제31권4호
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• pp.311-319
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• 2017

Scale formation is inevitable problem when seawater is treated by vacuum membrane distillation. The reason is the high concentration of calcium ion($Ca^{2+}$), sulfate ion(${SO_4}^{2-}$) and bicarbonate ion(${HCO_3}^-$). These ions form calcium sulfate($CaSO_4$) and calcium carbonate($CaCO_3$) on the membrane. The scale formed on membrane has to be removed, because the flux can be severely reduced and membrane wetting can be incurred. This study was carried out to investigate scale formation and effectiveness of acid cleaning in vacuum membrane distillation for SWRO brine treatment. It was found that permeate flux gradually declined until volume concentration factor(VCF) reached around 1.55 and membrane wetting started over VCF over 1.6 in the formation of precipitates containing $CaSO_4$ during VMD operation. In contrast, when calcium carbonate formed on membrane, permeate flux was gradually reduced until VCF 3.0. The precipitates containing both $CaSO_4$ and $CaCO_3$ were formed on the membrane surface and in the membrane pore.

• Membrane and Water Treatment
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• 제6권3호
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• pp.237-249
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• 2015

In this study we investigate a laboratory scale vacuum membrane distillation system to produce pure water from model oil in water emulsion. Experimental determination of liquid entry pressure (LEP) of a commercial Durapore$^{TM}$ GVPH flat sheet membrane using model emulsions in various oil concentrations has been carried out. Two different methods of liquid entry pressure determination - a frequently used, so-called static and a novel dynamic method - have been investigated. In case of static method, LEP value was found to be 2.3 bar. No significant effect of oil content on LEP was detected up to 3200 ppm. In contrast, LEP values determined with dynamic method showed strong dependence on the oil concentration of the feed and decreased from 2.0 bar to a spontaneous wetting at 0.2 bar in the range 0-250 ppm, respectively. Vacuum membrane distillation tests were also performed. The separation performance is evaluated in terms of flux behavior, total organic carbon removal and droplet size distribution of the feed and final retentate. No significant effect of oil content on the flux was found ($5.05{\pm}0.31kgm^{-2}h^{-1}$) up to 250 ppm, where a spontaneous wetting occurred. High separation performance was achieved along with the increasing oil concentration between 93.4-97.0%.

• Nuclear Engineering and Technology
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• 제40권3호
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• pp.163-174
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• 2008

As part of the spent fuel treatment program at the Idaho National Laboratory, a vacuum distillation process is being employed for the recovery of actinide products following an electrorefining process. Separation of the actinide products from a molten salt electrolyte and cadmium is achieved by a batch operation called cathode processing. A cathode processor has been designed and developed to efficiently remove the process chemicals and consolidate the actinide products for further processing. This paper describes the fundamentals of cathode processing, the evolution of the equipment design, the operation and efficiency of the equipment, and recent developments at the cathode processor. In addition, challenges encountered during the processing of irradiated spent nuclear fuel in the cathode processor will be discussed.

• Membrane and Water Treatment
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• 제10권4호
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• pp.251-257
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• 2019

Fabricating hydrophobic porous membrane is important for exploring the applications of membrane distillation (MD). In the present paper, poly(vinylidene fluoride) (PVDF) hollow fiber membrane was modified by coating polydimethylsiloxane (PDMS) on its surface. The effects of PDMS concentration, cross-linking temperature and cross-linking time on the performance of the composite membranes in a vacuum membrane distillation (VMD) process were investigated. It was found that the hydrophobicity and the VMD performance of the PVDF hollow fiber membrane were obviously improved by coating PDMS. The optimal PDMS concentration, cross-linking temperature and cross-linking time were 0.5 wt%, $80^{\circ}C$, and 9 hr, respectively.

• Journal of Ginseng Research
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• 제14권3호
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• pp.353-356
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• 1990

The isolation of volatile compounds by vacuum-distillation with freeze-drying was tested 1 with fresh ginseng roots. The roots were frozen at-8$0^{\circ}C$; they were dried at-4$0^{\circ}C$ tinder vacuum(40 tory), for 24 hours; and the ice condensed at the silrface of condenser in the freeze-dryer was thauved at room temperature. The ether extract of the resulting aqueous solution was analyzed by gas chromatography (GC) equipped with a flame ionization detector (FID) or a nitrogen-phosphorils detecto(NPD) and by gas : chromatography/mass spectrometry(GC/MS). More than forty peaks were observed in the CG(FID) profile. and more than ten peaks were observed in the GC(NPD) profile. Among them, thirteen components 1including one aldehyde, four hydrocarbons, two esters, folly alcohols, and two vyrazines were identified: six components the molesuiar ions of which were m/z, 204 were estimated to be a series of azulene compounds; and the other components unidentified were estimated to have molecular weights of lower than 254. Therefore, the freeze-drying technicue is thought to be usefu1 for the isolation of volatile compounds of such low molecufilar weights from vegetables, fruits and biological fluids as well as fresh ginseng roots under the tested conditions.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 춘계학술논문요약집
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• pp.83-83
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• 2017

Electrorefining is a key step in pyroprocessing. The electrorefining process is generally composed of two recovery steps - the deposit of uranium onto a solid cathode and the recovery of the remaining uranium and TRU elements simultaneously by a liquid cadmium cathode. The solid cathode processing is necessary to separate the salt from the cathode since the uranium deposit in a solid cathode contains electrolyte salt. Distillation process was employed for the cathode processing. It is very important to increase the throughput of the salt separation system due to the high uranium content of spent nuclear fuel and high salt fraction of uranium dendrites. In this study, a mesh-covered crucible was investigated for the sat distillation of electrorefiner uranium deposits. A liquid salt separation step and a vacuum distillation step were combined for salt separation. The adhered salt in uranium deposits was efficiently removed in the mesh-covered crucible. The salt distiller was operated simply since repeated cooling - heating step was not necessary for the change of the crucible. The operation time could be reduced by the use of the mesh-covered crucible and the combined operation of the two steps. A method to preserve a vacuum level was proposed by double O-rings during the operation of the distiller with the mesh-covered crucible. After the salt distillation, the salt content was measured and was below 0.1wt% after the salt distillation. The residual salt after the salt distillation can be removed further during melting of uranium metal.

• 방사성폐기물학회지
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• 제12권3호
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• pp.179-189
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• 2014

파이로 공정은 사용후핵연료 관리 이슈 해결과 유용자원 재활용 제고의 목적으로 개발되고 있다. 파이로 공정 중 전해환원 공정은 LiCl을 전해질로 사용하여 산화물을 금속으로 전환시키는 공정으로 금속 전환체에 잔류염이 포함되므로 후속 공정이 요구된다. 진공 증류 공정은 다양한 용융염계에서 적용되어 왔으며 금속 전환체에서도 활용될 수 있다. 전해환원 금속 전환체 잔류염은 LiCl과 알카리 및 알카리토 금속 염화물을 포함한다. 본 연구에서는 이들 염화물들의 증기압을 추산하여 진공 증류 공정에서 잔류 액체의 조성변화를 계산하였다. 증류된 기체가 일정하게 제거되는 조건에서 물질수지와 기-액 평형식을 결합한 모델을 개발하였으며 증기압을 이용하여 무차원 시간에 대한 액체 조성 변화를 계산하였다. 공정 조건 변화 모사를 위해 온도와 용융염 조성을 변화시켜 거동을 비교하였다. 잔류염의 증류는 주성분인 LiCl에 의해 지배되었으며 LiCl 보다 증기압이 높은 CsCl은 쉽게 제거될 것이 예상되었다. 증기압이 유사한 RbCl은 LiCl과 일정한 조성이 유지되었다. 반면 증기압이 낮은 $SrCl_2$와 $BaCl_2$는 시간에 따라 농축되며 초기 조성이 높은 경우 증류 과정에서 석출될 가능성이 있는 것으로 예상되었다.

• 청정기술
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• 제17권1호
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• pp.56-61
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• 2011

감압잔사유를 고압 회분식 반응기에 넣고, 상용 Ni-Mo/$Al_2O_3$ 촉매를 이용하여 $450^{\circ}C$, $500^{\circ}C$에서 수첨분해하였다. 그리고 반응 생성물을 단증류 혹은 GC-SIMDIS 방법으로 각각 분석하였다. 먼저 수첨분해반응에서는 두 온도 조건 모두 촉매 반응뿐만 아니라 열분해 반응도 같이 일어나고 있음을 확인하였고, 온도가 증가할수록 전환율이 증가하고, 생성물 중 가솔린 및 납사 비율이 높아졌다. 생성물 분석 결과, $500^{\circ}C$ 반응에서는 단증류와 GC-SIMDIS 분석 결과의 차이가 없었지만, $450^{\circ}C$ 반응에서는 단증류에서는 디젤이, GC-SIMDIS에서는 vacuum gas oil이 주 생성물로 드러났다. 이는 $450^{\circ}C$ 반응에서의 단증류 분석은 단증류에 의한 열분해 반응으로 인해 생성물의 선택도가 정확하지 않음을 알려준다.