Transcript Analyzing Air Distribution in Open

12th Mine Ventilation Symposium
Reno, Nevada USA
DPM Dispersion Study Using CFD for
Underground Metal/Nonmetal Mines
Yi Zheng [email protected]
Jerry C. Tien [email protected]
Mining & Nuclear Engineering Department
Missouri University of Science & Technology
OUTLINE
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DPM Regulation for U/G M/NM Mines
DPM Situation and Control Strategies
Simulation Method and Assumption
Main Airflow Simulation
Single Heading Airflow-Blowing &
Exhausting
Results and Discussion
Summary and Conclusions
DPM Regulation for U/G M/NM Mines
• Diesel-powered equipments are widely used in
U.S. U/G M/NM mines for the power, reliability,
easy to operate and repair, fuel efficiency,
durability, etc.
• However, it can cause health problems.
• Therefore, beginning May 20, 2008, 160 μg/m3
of TC or less is required by MSHA.
DPM Situation
• 2001 - 2002, MSHA 358 valid samples from 30 mines:
488 µg/m3 of TC for metal mines, 372 µg/m3 of TC for
stone mines…
• 2002 - 2003, MSHA 1,194 valid DPM from 183 mines:
354 µg/m3 of TC for metal mines, 235 µg/m3 for stone
mines…
• 2003 – 2006, MSHA 1,798 valid samples from all mines
covered by the regulation:
64% (1,151) exceeded 160 µg/m3 of TC…
DPM Control Strategies
• MSHA six available DPM control strategies:
Modern low-DPM emission diesel engines;
upgrade ventilation system; environmental cabs;
work practices; alternative fuels; DPM filters.
• Ventilation is a critical one:
1 gram of DPM can pollute 6,250 m3 of space to
final limit if without ventilation.
Simulation Method and Assumption
• Simulation Method: Computational Fluid
Dynamics
• Program: FLUENT
• Assumption:
DPM movement will be entirely dictated by the
airflow patterns
Main Airflow Simulation
South section of an underground metal mine
Main Airflow Simulation—without Stoppings
Path of small particles without stoppings
Main Airflow Simulation—with Stoppings
Stoppings to guide the air
Main Airflow Simulation—with Stoppings
Path of small particles with stoppings
Main Airflow Simulation—with Stoppings
Three types of working face with ventilation problems
Main Airflow Simulation—with Stoppings
Main airflow velocity near the dead end opening
Single Heading Airflow Simulation
Layout of a single heading with blower fan and tubing
Single Heading Airflow Simulation
Layout of a single heading with exhaust fan and tubing
Single Heading Airflow Simulation
CAT 725 articulated truck
CAT 980H wheel loader
Results and Discussion—Blowing System
Airflow velocity of the main entry and single heading
Results and Discussion—Blowing System
Airflow velocity in the face area
Results and Discussion—Blowing System
Exhaust airflow pattern in the face area
Results and Discussion—Blowing System
DPM concentration dispersion in the face
Results and Discussion—Exhausting System
Airflow velocity of the main entry and single heading
Results and Discussion—Exhausting System
Airflow velocity in the face area
Results and Discussion—Exhausting System
Exhaust airflow pattern in the face area
Results and Discussion—Exhausting System
DPM concentration dispersion in the face
Summary and Conclusions
1. CFD method can be used to simulate the airflow patterns
for the entire mine or for a part of it. Areas with poor
ventilation can be identified and local ventilation control
measures designed and evaluated.
2. Single heading face usually has the worst working
condition in underground mines. Local ventilation
facility is needed to improve the situation.
3. In a single heading face, loader driver is working in a
higher DPM environment for both blowing and
exhausting systems. More work need to be done to meet
the regulation.
Summary and Conclusions
4. DPM is distributed in a much smaller space in a
blowing face ventilation system than in an exhausting
face system, which means high air velocity is more
effective than quantity to control DPM.
5. In the near future, a validation experiment is planed
to take out. After that, a single measurement in the
face (near the exhaust pipe) can give the DPM
concentration distribution for the whole face area.
Thank You!