Planning and Selection of the Main Fans for the Grasberg ... - SME
Planning and Selection of the Main Fans for the Grasberg ... - SME
Planning and Selection of the Main Fans for the Grasberg ... - SME
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<strong>Planning</strong> <strong>and</strong> <strong>Selection</strong> <strong>of</strong><br />
<strong>the</strong> <strong>Main</strong> <strong>Fans</strong> <strong>for</strong> <strong>the</strong><br />
<strong>Grasberg</strong> Block Cave Mine<br />
Ian Loomis <strong>and</strong> Ian Duckworth<br />
June 2012<br />
www.fcx.com CONNECTING THE FUTURE ®
Introduction<br />
• <strong>Grasberg</strong> Block Cave – continuation <strong>of</strong> <strong>Grasberg</strong><br />
orebody below <strong>the</strong> current open-pit<br />
• Designed <strong>for</strong> 160,000 tpd peak production<br />
• Undercutting begins late 2015<br />
• Full-production by 2023<br />
2
Prefeasibility Study<br />
• Scoped <strong>the</strong> <strong>Grasberg</strong> Block Cave at 115 ktpd<br />
• Peak Ventilation dem<strong>and</strong>: 1,755 m 3 /s at 3,490 Pa<br />
4500<br />
Operating Point Pr<strong>of</strong>ile<br />
System Total Pressure (Pa)<br />
4000<br />
3500<br />
3000<br />
2500<br />
2000<br />
1500<br />
1000<br />
500<br />
Prefeasibility<br />
0<br />
0 500 1000 1500 2000 2500 3000<br />
Air flow (m 3 /s)<br />
3
Feasibility Study<br />
• Scoped <strong>the</strong> <strong>Grasberg</strong> Block Cave at 160 ktpd<br />
• Peak Ventilation dem<strong>and</strong>: 1,992 m 3 /s at 2,225 Pa<br />
4500<br />
Operating Point Pr<strong>of</strong>ile<br />
System Total Pressure (Pa)<br />
4000<br />
3500<br />
3000<br />
2500<br />
2000<br />
1500<br />
1000<br />
500<br />
Prefeasibility<br />
Feasibility<br />
0<br />
0 500 1000 1500 2000 2500 3000<br />
Air flow (m 3 /s)<br />
4
Air Flow Requirements<br />
• Review <strong>of</strong> 160 ktpd <strong>Grasberg</strong> Block Cave mine<br />
• 4000 Separation <strong>of</strong> circuits<br />
• 3500 Active Ventilation Management<br />
• 3000 Work place vs. Diesel power load<br />
System Total Pressure (Pa)<br />
4500<br />
• 2500 Peer comparisons<br />
• 2000 Ventilation requirements revisited:<br />
1500<br />
1000<br />
- Air flow dem<strong>and</strong> increased to 2,800 m 3 /s<br />
- System total pressure increased to 4,100 Pa<br />
500<br />
Operating Point Pr<strong>of</strong>ile<br />
Prefeasibility<br />
Feasibility<br />
Fan selection basis<br />
0<br />
0 500 1000 1500 2000 2500 3000<br />
Air flow (m 3 /s)<br />
5
System Configuration<br />
• <strong>Fans</strong> located underground<br />
- Lack <strong>of</strong> surface space<br />
- Underground installation experience at DOZ <strong>and</strong> Big<br />
Gossan Mines<br />
• <strong>Fans</strong> added sequentially (2012, 2013, 2016, 2017)<br />
• <strong>Main</strong> intake <strong>and</strong> exhaust drifts in parallel – one <strong>for</strong><br />
each fan<br />
• Drive – 13.8 kV, DOL start<br />
6
System Configuration<br />
7
System Configuration<br />
• Application <strong>of</strong> Mixed-Flow fans considered from <strong>the</strong><br />
outset.<br />
- Experience constructing <strong>and</strong> operating 6 units at<br />
3.5 meters diameter; 5 @ 1,600 kW <strong>and</strong> 1 @ 2,200<br />
kW.<br />
- Robust design, durability, stability <strong>and</strong> buildup/wear<br />
characteristics<br />
8
Considerations<br />
• Push-Pull system<br />
- 3 axial flow fans intake <strong>and</strong> 4 mixed-flow exhaust<br />
- 17,400 kW total<br />
- Lower pressures ≠ Smaller Fan diameter<br />
- Intake fans 4.90 m dia. (850 m 3 /s at 1.7 kPa)<br />
- Exhaust fans 4.45 m dia. (700 m 3 /s at 2.7 kPa)<br />
- Intake <strong>and</strong> exhaust both at 590 rpm<br />
9
Considerations<br />
• Exhausting System (early)<br />
- 4 mixed flow exhaust fans<br />
- 15,400 kW total<br />
- Lower speed – lower max pressure capability<br />
- Impellors 4.20 m dia. (700 m 3 /s at 4.0 kPa)<br />
- 590 rpm<br />
10
Options<br />
3000<br />
2000<br />
Extraction Level<br />
1000<br />
Relative Pressure (Pa)<br />
0<br />
-1000<br />
<strong>Main</strong> Intake Drifts<br />
Exhausting<br />
Push-Pull<br />
-2000<br />
<strong>Main</strong> Exhaust Drifts<br />
-3000<br />
-4000<br />
Intake<br />
Gallery Drifts<br />
Exhaust<br />
Gallery<br />
Drifts<br />
0 1000 2000 3000 4000 5000 6000 7000 8000 9000<br />
Distance along Circuit (m)<br />
11
Options<br />
• <strong>Fans</strong> near bottom <strong>of</strong> exhaust inclines<br />
- More room <strong>for</strong> chambers<br />
- Drier conditions<br />
• <strong>Fans</strong> near <strong>the</strong> portals (~200m)<br />
- More rapid excavation completion<br />
- Early construction<br />
- Availability <strong>of</strong> power<br />
- Ability <strong>for</strong> integration to future projects<br />
12
Fan Requirements<br />
• Four fans working in parallel<br />
• Delivered pressure<br />
• Ability to start at maximum pressure on system<br />
• Airflow conditions<br />
- Temperature<br />
- Humidity<br />
- Elevation/Barometric pressure<br />
- Density<br />
- Contaminant<br />
• Component size restrictions<br />
13
<strong>Selection</strong><br />
• Design – Mixed Flow<br />
• Diameter – 4.05 m<br />
• Speed – 710 rpm<br />
• Blade material – steel<br />
• Design airflow – 700 m 3 /s<br />
• Design Pressure – 4,100 Pa<br />
• Rated efficiency – 83%<br />
• Motor power – 4,100 kW<br />
• Flow control – Inlet vortex<br />
14
<strong>Selection</strong><br />
• Two variants <strong>of</strong> <strong>the</strong> same fan were <strong>of</strong>fered, difference<br />
is in <strong>the</strong> impellor solidity<br />
- 91% solidity impellor<br />
- 74% solidity impellor<br />
• Selected higher solidity<br />
- Ability to reach <strong>the</strong> maximum pressure<br />
- However, lower operating efficiency at rated duty<br />
- Extreme cases limited by motor selection<br />
15
<strong>Selection</strong><br />
8.000<br />
7.000<br />
System Total Pressure (kPa)<br />
6.000<br />
5.000<br />
4.000<br />
3.000<br />
2.000<br />
1.000<br />
0.000<br />
Maximum duty<br />
Rated duty<br />
+30°<br />
+20°<br />
+10°<br />
0°<br />
-90° -80° -70°<br />
-60° -50° - -30° -20° -10°<br />
0 100 200 300 400 500 600 700 800 900 1000 1100<br />
Flow (m³/s)<br />
16
Installation<br />
• Use <strong>of</strong> Gantry Crane vs. mono-rail<br />
17
Installation<br />
18
Installation<br />
19
Installation<br />
20
Installation<br />
21
Installation<br />
22
Installation<br />
23
Summary <strong>and</strong> Conclusions<br />
• Establish <strong>the</strong> desired operating points based on<br />
Feasibility Studies <strong>and</strong> peer comparisons against<br />
ventilation modeling.<br />
• Comparison <strong>of</strong> possible configurations <strong>and</strong><br />
arrangements.<br />
• <strong>Main</strong>tain consistency with implemented technologies<br />
• <strong>Planning</strong> <strong>for</strong> Safety during Construction <strong>and</strong><br />
<strong>Main</strong>tenance<br />
• <strong>Planning</strong> <strong>for</strong> <strong>the</strong> future<br />
24
Thank you<br />
25
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