Download - Selection of a novel mine tracer gas for assessment of ventilation systems in underground mines
February 21, 2012
Selection of a novel mine tracer gas for assessment of ventilation systems in underground minesSusanne Underwood, Rosemary Patterson, Kimberly Jackson, Kray Luxbacher, Harold McNair
Acknowledgements
This publication was developed under Contract No. 200-2009-31933, awarded by the National Institute for Occupational Safety and Health (NIOSH). The findings and conclusions in this report are those of the authors and do not reflect the official policies of the Department of Health and Human Services; nor does the mention of trade names, commercial practices, or organizations imply endorsement by the U.S. Government.
Outline
• Ventilation surveys using trace analysis• Tracer characteristics• Previous uses of considered tracer elements
Background
• Results of tracer analysis• Selection of a tracer element• Development of analysis method
Application
• Future work• Conclusions
Summary
Project ObjectiveBackground
• To select a safe novel tracer• Novel tracer must have similar sensitivity to
current tracers• Develop one analysis method to allow for
concurrent deployment of tracers
Tracer TechniqueBackground
• Directly measures air quantity• When traditional point measurement of
velocity cannot be used including– Where cross-sectional area cannot be easily
measured– Locations deemed unsafe due to emergency– Places with very low or irregular flow
How does the tracer technique work?Background
• Tracer is directly released into atmosphere• Gas chromatography analysis• Two methods
– Continuous tracer release– Pulse tracer release
• Limited applications due to time
How will a novel tracer help?Background
• Increase ventilation survey versatility• Simultaneous analysis of airways/leakages• Reduces the time limitations of traditional
tracer analysis
Tracer RequirementsBackground
• Easily detected and analyzed• Absent from mine air• Nonreactive, nontoxic, noncorrosive, nor
explosive• Readily attainable• Easily transported• Highly sensitive
Tracers ConsideredBackground
• Industry standard is Sulfur Hexafluoride (SF6)• Freons
– Carbon Tetrafluoride (CF4)– Octofluoropropane (C3F8)
• Perfluorocarbon tracers
Previous Tracer ApplicationsBackground
• Freon testing in mines• Perfluorocarbon Tracers
– Urban environments– European Tracer Experiment– Oil and gas reservoirs– Home ventilation systems– No evidence that PFTs have been used in mines
PMCH CharacteristicsBackground
• C7F14
• Volatile liquid• Boiling point of 67⁰C• Biologically inert• Molecular weight of 350 g/mol• Very low ambient backgrounds
Experimental DesignApplication
• Shimadzu 2014 Gas Chromatograph• Electron Capture Detector• Columns tested for Freons
– SBP-1 Sulfur– ZB-624– TG Bond Q+– TG Bond Q
• PMCH tested using HP-AL/S column
GoalsApplication
• Achieve separation between peaks• Attain Gaussian shaped peaks• Apply an acceptable method
O2 SF6 CF4 C3F8 PMCH
40 1.1 1.22 1.1 1.2 ---20 1.08 1.19 1.1 1.24 ---40 2.14 2.22 --- 2.23 ---20 2.14 2.22 --- 2.27 ---0 2.14 2.24 --- 2.17 ---
40 1.94 2.22 2.12 3.49 ---20 1.96 5.22 --- 5.22 ---0 1.96 9.65 --- 9.84 ---
60 2.3 3.1 --- 3,09 ---50 2.33 3.42 --- 3.41 ---40 2.24 3.88 --- 3.88 ---20 2.27 5.74 --- 5.7 ---0 2.27 10.6 --- --- ---
70 2.09 2.43 --- --- 9.6167 2.07 2.44 --- --- 9.69
65 2.08 2.48 --- --- 9.74
Column Temperature (
⁰
C)Column
SBP-1 Sulfur Column
ZB-624 Column
TG Bond Q+ Column
TG Bond Q Column
HP-AL/S Column
Average Retention Time (min)
SF6 CF4 C3F8 PMCH
40 8.91x107 1.43x104 1.44x104 ---20 7.69x107 1.56x104 1.30x104 ---40 5.93x107 2.07x103 1.02x104 ---20 6.12x107 --- 8.63x103 ---0 6.57x107 --- 2.20x105 ---40 5.93x107 2.79x103 1.15x105 ---20 1.091x108 --- 6.15x104 ---0 1.100x106 --- 4.13x104 ---60 2.56x107 --- 3.34x105 ---50 2.60x107 --- 4.18x105 ---40 7.26x106 --- 3.88x103 ---20 4.50x106 --- 1.960x103 ---0 3.70x106 --- --- ---70 3.44x107 --- --- 4.95x107
67 4.24x107 --- --- 6.34x107
65 6.18x107 --- --- 7.97x107
Column Column Temperature (
⁰
C)Average Peak Area of Gases
SBP-1 Sulfur Column
ZB-624 Column
TG Bond Q+ Column
TG Bond Q Column
HP-AL/S Column
Chromatogram ResultsApplication
µV(x10,000)
min
Chromatogram ResultsApplication
µV(x100,000)
min
Chromatogram ResultsApplication
Column Name HP-AL/SColumn Type Capillary
Column Length 30 mInner Diameter 0.250 mmFilm Thickness 5 µm
Split Injector Temperature 150⁰CSplit Ratio 50:1Pressure 16.2 psi
Carrier Gas HeTotal Flow 60.8 mL/min
Make Up Gas N2
Column Flow 1.15 mL/minLinear Velocity 30 cm/s
Septum Purge Flow 2.0 mL/minDetector Temperature 200⁰C
Initial Column Temperature 67⁰C hold 2.75 minRamp 120⁰C/min
Final Column Temperature 180⁰C hold 12.30 minTotal Program Time 15.99 min
µV(x10,000,000)
min
Future WorkSummary
• PMCH vulnerabilities to sample loss• Methods of release
– Permeation tubes– Fluoroelastomer plug source– Gas Cylinders
ConclusionsSummary
• Unsuccessful separation when using Freon gases
• PMCH is a favorable tracer selection– Successful separation– Encouraging previous applications
• A simple GC method has been developed
Thank youSummary
Questions?