• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.120-131
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• 1995

Thermodynamic analysis of extraction process from the constant pressure LNG(Liquefied Natural Gas) vessel was performed in this study. LNG was assumed as a binary mixture of 90% methane and 10% ethane by mole fraction. The thermodynamic properties such as temperature, composition, specific volume and the amount of cold energy were predicted during extraction process. Pressure as a parameter ranges from 101.3kPa to 2000kPa. The result shows the peculiar phenomena for the LNG as a mixture. Both vapor and liquid extraction processes were investigated by a computer model. The property changes are negligible in the liquid extraction process. For the vapor extraction process, the temperature in the vessel increases rapidly and the extracted composition of methane decreases rapidly near the end of extracting process. Specific volume of vapor has the maximum and that of liquid has the minimum during the process. When pressure is increased, specific volume of vapor decreases and that of liquid increases. It was found that specific volume of vapor phase had a major effect on the heat absorption at constant pressure during vapor extraction process. If the pressure of the vessel increases, the total cold energy which can be utilized from LNG decreased.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.285-288
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• 2003

When the soil vapor extraction as a remediation method of contaminated soil and groundwater has been used, the effects of curtain wall, mode of pump operation were examined by numerical simulation. Consequently, it was found that the removal rate was enhanced in case that the curtain wall was established around the extraction well with the extraction pumps operated alternatively. It was because that the removal of high density gas around the extraction well was possible.

• Journal of Korea Water Resources Association
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• v.32 no.2
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• pp.121-129
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• 1999

When the soil vapor extraction as a remediation method of contaminated soil and groundwater has been used, the effects of curtain wall, mode of pump operation and magnitude of extraction flowrate were examined by numerical simulation. Consequently, it was found that the removal rate was enhanced in case that the curtain wall was established around the extraction well with the extraction pumps operated alternatively. It was because that the removal of high density gas around the extraction well was possible. It was found that the removal efficiency of TCE gas did not depend on the extraction flowrate. However, the removal rate of TCE gas at varying extraction flowrate was not enhanced flowrate increase.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.382-388
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• 2005

Soil vapor extraction(SVE) is an effective and cost efficient method of removing volatile organic compounds(VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. Prefabricated vertical drains(PVDs) have been used for dewatering fine-grained soils for more than 25 years. Incorporating PVDs in and SVE system can extend the effectiveness of SVE to lower permeability soils by shortening the air flow-paths and ultimately expediting contaminant removal. The objective of the work described herein was to effectively incorporate PVDs into a SVE remediation system and to demonstrate a PVDs enhanced SVE system at full scale. The finding from this research will facilitate the design of field PVD-SVE systems in terms by providing insight into the optimal spacing between PVDs, the radius of influence of the wells and the flow rates to be used to capture and extract gas phase contaminants.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.354-355
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• 2003

In this study, a risk-based cleanup approach using the leaching potential was suggested for the soil vapor extraction (SVE) process. A multi-component model was adopted with local equilibrium assumption (LEA), and Raoult's law was applied to estimate the leaching potential for BTEX. Finally, a risk analysis was conducted based on the leaching pontential calculated. To complete the feasibility of this approach, more investigations and discussions will be required in future.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1233-1241
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• 2000

The purpose of this study is to see the remediability and pilot system operating condition on diesel contaminated areas. Air permeability(k) and trend of gas phase ($O_2/CO_2/VOCs$) concentration to determine the remediation rate of the contaminated sites are very important. So we tested air permeability and trend of gas phase concentration. Throughout soil vapor extraction(SVE) and bioventing hybrid pilot test on different conditions, the range of air permeability(k) was 1985~1194 darcy. The tests result in soil vapor extraction and bioventing hybrid system was appropriate on this test sites, and the suitable injection air flow rate was $3.5m^3/hr$.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.9-18
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• 2007

Soil vapor extraction (SVE) is an effective and cost efficient method of removing volatile organic compounds (VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. Incorporating PVDs in an SVE system can extend the effectiveness of SVE to lower permeability soils by shortening the air flow-paths and ultimately expediting contaminant removal. The objective of the research described herein was to effectively incorporate PVDs into a SVE remediation system. The test results show that the gas permeability was evaluated for four different equivalent diameters, increasing the equivalent diameter results in a decrease in the calculated gas permeability. It was found that the porosity for the dry condition was greater than that of the wet condition and will allow flow rate for the same vacuum flow, offering a low resistance to the air flow.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.13-23
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• 2000

The effects of operating condition of soil vapor extraction system and the characteristics of site on the remediation of oil contaminated soil were investigated. Thorough investigation showed that the site was contaminated with gasoline leaked from underground storage tank and the maximum concentration of BTEX and TPH were 1,081 ppm and 5,548 ppm respectively. The leaked gasoline were diffused to 6m deep and the area and volume of the polluted soil were assumed to 170$m^2$ and 1,000$\textrm{m}^3$respectively. The site were consisted of three different vertitical layers, the top reclaimed sandy soil between the earth surface and 3~4m deep, middle silty sand between 3~4m and 6m deep, and the bottom bedrock below the 6m deep. The air pemeability of soil was measured to 1.058-1.077$\times$10$^{-6}$ $\textrm{mm}^2$ by vacuum pump tests. The groundwater which level was 3~4m deep was observed in some areas of this site. The soil vapor extraction system which had 7.5 HP vacuum pump and 8 extraction wells was constructed in this site and operated at 8 hrs/day for 100 days. The BTEX was removed with above 90% efficiency where no groundwater and silty sand were observed. On the contrary, the efficiency of BTEX and TPH were dramatically decreased where groundwater and silty sand were observed. The flow rate of soil air induced by soil vapor extraction system was reduced in deeper soil.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.223-226
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• 2004

In this paper, removal of diesel hydrocarbons (C$_{10}$-C$_{22}$) for dry and moist soil was investigated so that microwave-enhanced soil vapor extraction(SVE) reduced soil treatment time and raised remediation efficiency. Kinetic constants of diesel hydrocarbons with microwave energy were 7 times on dry soil and 1580 times on moist soil as much as those of SVE process without microwave energy. The diesel removals were 67.7～78.4% for $C_{10}$ and $C_{12}$, and 0～18.5% for $C_{14}$～C$_{22}$ for dry and moist soil with SVE process only. On the other hand, dry soil with microwave-enhanced SVE process showed 89.3～99.4% removal for $C_{10}$ and $C_{12}$ and 35.6～67.0% for hydrocarbons over $C_{14}$. All hydrocarbons(C$_{10}$～C$_{22}$) studied were significantly removed (93.6～99.8%) for moist soil with microwave-enhanced SVE process. Almost all diesel hydrocarbons were usually considered as semi-volatile compounds(SVOCs). Microwave-enhanced SVE process might have a great potential for remediation of soils contaminated with SVOCs.OCs.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.1
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• pp.60-68
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• 2000

Biofiltration is an environmentally-sound technology for elimination of VOCs and odorous compound from low-concentration, high-volume waste gas streams because of its simplicity and cost-effectiveness. It can be appled to the treatment of gases from publicly owned treatment works, composting facilities, landfill sites, and soil vapor extraction systems. The ability to design an effective biofilter system involves a combination of fundamental biofilter knowledge, practical experience, and bench- and pilot-scale testing. The objective of this paper was to review principle, design parameters, operational conditions, case studies, and economy of biofiltration through literature.