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8/3/2019 3_1 Operating Multiple Fans
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 1
Basic Mine VentilationBasic Mine Ventilation
Understanding FansUnderstanding Fans
Operating Multiple FansOperating Multiple Fans
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 2
Series fansSeries fans
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 3
Operate in the samesystem and handle the
same air
Fans may be bolted
together or spaced
along the duct
Pressure increases for
the same volume
PTotal = P1 + P2
Series fansSeries fans
Quantity (m3/s)
Pressure
(Pa)
0
0
5 10 15 20
500
100
0
PA
PB
P A+B
Fan A
Fan B
Fan A + B
0 5
A B
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 4
Example
Airflow increase is minimal
Pressure increase is x2
Assuming the motors are250 kW, would you
recommend this?Increase circa 10 m3/s
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 5
Fans & NVPFans & NVP
Quantity (m3/s)
Pressure
(Pa)
0
0
5 10 15 20
500
1000
Operating point varies on a
daily and seasonal basis
NVP -100
-200
NVP +110
Fan - NVP
Fan + NVP
Fan
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 6
Operating fans in parallelParallel fansParallel fans
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 7
Fans installed alongside each other
and operate on the same system
Volume increases for the same
pressure
QTotal = Q1 + Q2
Parallel fansParallel fans
Quantity (m3/s)
Pressure
(Pa)
00
5 10 15 20
50
0
1000
QA
QB
Q A+B
Fan A
Fan B
Fan A + B
A
B
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 8
Example
Pressure increase is minimal
Quantity increase is something
less than x2
Assuming the motors are 250
kW, would you recommend
this?
How would you configure the
fans?
Increase circa 30 m3/s
NOT x2
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 9
If fans that intake (exhaust) air through the same system are in parallel,
then fans that intake (exhaust) from the same place but through different
systems are in partial parallel
Both fans must have sufficient pressure to overcome the resistance of the
common airway.
Partial parallel fansPartial parallel fans
Fan 1A
B
C
Fan 2
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 10
PartialPartial--parallel fansparallel fans
0
500
1000
1500
2000
2500
3000
0 25 50 75 100 125 150 175 200 225 250 275 300
Volume (Q) (m3/s)
Pressure(Pa)
Fan 1
Fan 2
A
B
C
Fan1
Fan2
System
A
System
B
Syste
mC
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0
500
1000
1500
2000
2500
3000
0 25 50 75 100 125 150 175 200 225 250
Volume (Q) (m3/s)
Pressure
(Pa)
Fan1
System
AFan pressure available
Pressure used by the system
2214
810
Residual fan pressure
2214 810 = 1404Fan pressure exactly
overcomes the system
resistance and the residual
pressure is ZERO
Fan 1 in System AFan 1 in System A Residual fan curveResidual fan curve
Fan 1
Fan 2
A
B
C
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 12
Plotting the residual curvesPlotting the residual curves
0
500
1000
1500
2000
2500
3000
0 25 50 75 100 125 150 175 200 225 250 275 300
Volume (Q) (m3/s)
Pressure
(Pa)
Fan1
Fan2 System
A
System
B
SystemC
Fan1-SysA=R
1
Fan2-SysB=R2Fan 1
Fan 2
A
B
C
Paralle
lresidualcu
rve
Q1
Q1+2
Q2
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 13
0
500
1000
1500
2000
2500
3000
0 25 50 75 100 125 150 175 200 225 250 275 300
Volume (Q) (m3/s)
Pressure
(Pa)
Fan1
Fan2 System
A
System
B
Syste
mC
Fan1-SysA=R1
Fan2-SysB=R2
R1+
R2=
Resid
ualcu
rve
Partial parallel fansPartial parallel fans --The solutionThe solution
Fan 1
Fan 2
A
B
C
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 14
When one fan passes the air to another the fans are said to be in
series. But if air enters or leaves the system between the fans the
fans are only in partial series
Because Fan 1 (System A) is assisting Fan 2 (System C) the curve
of Fan 1 needs to be subtracted from the system curve (A) to
determine the residual system curve.
Partial series fans (Circuit booster)Partial series fans (Circuit booster)
Fan 1A
B
C
Fan 2
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 15
0
500
1000
1500
2000
2500
3000
0 25 50 75 100 125 150 175 200 225 250
Volume (Q) (m3/s)
Pressure
(Pa)
Fan1
System
A
Fan pressure exactly
overcomes the systemresistance and the residual
pressure is ZEROPressure for system
Fan pressure2214
640
Residual system pressure
640 2214 = 1574-934
Fan 1
Fan 2A
BC
Fan 1 in System AFan 1 in System A Residual system curveResidual system curve
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 16
Plotting the residual system curvesPlotting the residual system curves
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000
2500
3000
0 25 50 75 100 125 150 175 200 225 250
Volume (Q) (m3/s)
Pressure
(Pa)
Fan 1
Fan 2A
BC
Fan1
Syste
mA
System
B
SysA
Fa
n1
Parallelsy
stemc
urve
Q1
Q2
Q1
Q1+2
System A and System B are in parallel
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Partial series fansPartial series fans --The solutionThe solution
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000
2500
3000
0 25 50 75 100 125 150 175 200 225 250
Volume (Q) (m3/s)
Pressure
(Pa)
Fan1
Fan2
Syste
mASy
stem
B
SysA
Fa
n1System B
40 m3/sSystem A
130 m3/sSystem A+B
170 m3/s
Paralle
lsyste
mcurv
eFan 1
Fan 2A
BC
AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 18
Primary Installations
Parallel at the the same shaft
Partial parallel if at different shafts
Single fan installations are generally less expensive than multiple fan installations.
Multiple fan installations have the advantage of airflow redundancy, i.e. a percentage of
airflow will always be available whilst a fan is off line for maintenance or component
change out.Single fan options do not provide any capacity for redundancy airflow. The purchase of
spares (motor, impeller, shafts, bearings, blades etc) is good management and should be
included as upfront capital expenditure.
Circuit Booster
Partial series
Sometime installed to act as a regulator
Relative merits of single and multiple fan installationsRelative merits of single and multiple fan installations
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AMC - The Business of Mining(C) AMC Consultants Pty Ltd 2005 19
Acknowledgements
DALY, B.B., 1978 Woods Practical Guide to Fan Engineering
(Published by Woods of Colchester 1978)
Le ROUX, W., Le Rouxs Notes on Mine EnvironmentalControl Fourth Edition. (The Mine Ventilation Society of South
Africa).
JORGENSEN, R. 1983 Fan Engineering Eighth Edition (Buffalo
Forge Company. Buffalo, New York.)
BURROWS, J., 1989 Environmental Engineering in South African
Mines (The Mine Ventilation Society of South Africa)
Tien, J.C., 1999 Practical Mine Ventilation Engineering (Intertec
Publishing Corporation. Chicago, Illinois.)
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