Sulfur Hexafluoride as a Gas Tracer in Soil Venting Operations

1995 ◽  
Vol 29 (1) ◽  
pp. 264-266 ◽  
Author(s):  
Andre. Olschewski ◽  
Ulrich. Fischer ◽  
Markus. Hofer ◽  
Rainer. Schulin
Keyword(s):  
Sulfur Hexafluoride ◽  
Soil Venting ◽  
Gas Tracer

Sulfur Hexafluoride Gas Tracer Studies in Streams

1998 ◽  
Vol 124 (8) ◽  
pp. 752-760 ◽  
Author(s):  
David E. Hibbs ◽  
Kenneth L. Parkhill ◽  
John S. Gulliver
Keyword(s):  
Sulfur Hexafluoride ◽  
Tracer Studies ◽  
Gas Tracer

A Quest for Effective Hygroscopic Cloud Seeding

2010 ◽  
Vol 49 (7) ◽  
pp. 1548-1562 ◽  
Author(s):  
Daniel Rosenfeld ◽  
Duncan Axisa ◽  
William L. Woodley ◽  
Ronen Lahav
Keyword(s):  
Size Distribution ◽  
Sulfur Hexafluoride ◽  
Field Experiments ◽  
Cloud Condensation Nuclei ◽  
Cloud Droplet ◽  
Cloud Base ◽  
Seeding Rate ◽  
Warm Rain ◽  
Seeding Agent ◽  
Gas Tracer

Abstract It is shown here that hygroscopic seeding requires two orders of magnitude more hygroscopic agent than can be delivered by flare technology for producing raindrop embryos in concentrations to detect by cloud physics aircraft the microphysical signature of rain initiation. An alternative method of finely milled salt powder is shown to be capable of achieving this goal. During field experiments the use of a sulfur hexafluoride (SF6) gas tracer to identify the exact seeded cloud volume and to quantify dilution of the seeding agent showed that the seeding agent dilutes to the order of 10−10 of its released concentration in updrafts at a height of ≥1 km above cloud base. This means that the theoretically expected changes in the cloud drop size distribution (DSD) would not be detectable with a cloud droplet spectrometer in a measurement volume collected during the several seconds that the seeded volume is traversed by an aircraft. The actual measurements failed to identify a clear microphysical seeding signature from the burning of hygroscopic flares within the seeded convective clouds. This uncertainty with respect to hygroscopic flare–seeding experiments prompted an experimental and theoretical search for optimal hygroscopic seeding materials. This search culminated in the production of a salt powder having 2–5-μm-diameter particle sizes that are optimal according to model simulations, and can be distributed from a crop duster aircraft. Such particles act as giant cloud condensation nuclei (GCCN). Any potential broadening of the DSD at cloud base by the competition effect (i.e., when the seeded aerosols compete with the natural ambient aerosols for water vapor) occurs when the seeding agent has not been substantially diluted, and hence affects only a very small cloud volume that dilutes quickly. Therefore, the main expected effect of the GCCN is probably to serve as raindrop embryos. The salt powder–seeding method is more productive by two orders of magnitude than the hygroscopic flares in producing GCCN that can initiate rain in clouds with naturally suppressed warm rain processes, because of a combination of change in the particle size distribution and the greater seeding rate that is practical with the powder. Experimental seeding of salt powder in conjunction with the simultaneous release of an SF6 gas tracer produced strong seeding signatures, indicating that the methodology works as hypothesized. The efficacy of the accelerated warm rain processes in altering rainfall amounts may vary under different conditions, and requires additional research that involves both observations and simulations.

EQUIPMENT FOR MAINTENANCE OF HIGH-VOLTAGE DEVICES WITH SULFUR HEXAFLUORIDE (SF6) INSULATION

2015 ◽  
pp. 42-45
Author(s):  
V.B. Moskalenko ◽  
◽  
I.G. Chizhov ◽  
O.V. Varakin ◽  
Y.A. Pavlenko ◽  
...  
Keyword(s):  
High Voltage ◽  
Sulfur Hexafluoride

EXPERIMENTAL PHASE EQUILIBRIUM OF SULFUR HEXAFLUORIDE AND MINERAL OIL

2020 ◽  
Author(s):  
Afonso Ferreira Miguel Junior ◽  
Luiz Fernando Santos de Vasconcelos ◽  
Celina Kakitani ◽  
césar yutaka ofuchi ◽  
Moisés Marcelino Neto ◽  
...  
Keyword(s):  
Phase Equilibrium ◽  
Sulfur Hexafluoride ◽  
Mineral Oil ◽  
Experimental Phase ◽  
Experimental Phase Equilibrium

scholarly journals Sub- and Supercritical Extraction of Slovenian Hops (Humulus lupulus L.) Aurora Variety Using Different Solvents

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1137
Author(s):  
Katja Bizaj ◽  
Mojca Škerget ◽  
Iztok Jože Košir ◽  
Željko Knez
Keyword(s):  
Sulfur Hexafluoride ◽  
Total Yield ◽  
Extraction Yield ◽  
Operating Conditions ◽  
Influence Of Process Parameters ◽  
Humulus Lupulus L ◽  
Bitter Acids ◽  
Temperature And Pressure ◽  
Carbon Dioxide Co2 ◽  
The Mathematical Model

This work investigates the efficiency of supercritical fluid extraction of hops with a variety of solvents including carbon dioxide (CO2), propane, sulfur hexafluoride (SF6), and dimethyl ether (DME) at various densities (low-density and high-density). Operating parameters were 50 bar, 100 bar and 150 bar and 20 °C, 40 °C, 60 °C and 80 °C for all solvents, respectively. The influence of process parameters on the total yield of extraction and content of bitter acids in the extracts has been investigated. The mathematical model based on Fick’s second law well described the experimental extraction results. Furthermore, HPLC analysis has been used to determine α- and β-acids in extracts. The yield of bitter compounds in hop extracts was largely influenced by the type of solvent, the temperature and pressure applied during extraction. The results show that CO2 and propane were roughly equivalent to DME in solvating power, while SF6 was a poor solvent at the same conditions. The highest yield as well as the highest concentration of bitter acids in extracts were obtained by using DME, where the optimal operating conditions were 40 °C and 100 bar for the extraction of α-acids (max. concentration 9.6%), 60 °C and 50 bar for the extraction of β-acids (4.5%) and 60 °C and 150 bar for the maximum extraction yield (25.6%).

Reservoir Study for Shale Gas Horizontal Casing Completion Multi-Stage Frac Using Gas Tracer Technology

2017 ◽  
Author(s):  
Yun Miao ◽  
Bo Zeng ◽  
Changlin Zhou ◽  
Yaoguang Wu ◽  
Yongbin Shan
Keyword(s):  
Shale Gas ◽  
Multi Stage ◽  
Gas Tracer
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