fans efficiancy.pptx

8/17/2019 fans efficiancy.pptx

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Fan SystemsFan Systems

M . Beauprés – Mise à jour D. Dumont avril 2004

+A.Godichon – la!t"oods # Mai 2004


2/82

2June 2009Process Engineering Program – Gas Handling – Fan Systems

ContentContent

System resistance

Performance curves

Fan types and terminology

Fan laws

Flow control

Fan audit


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System Resistance


4/82

June 2009Process Engineering Program – Gas Handling – Fan Systems

Concepts of PressureConcepts of Pressure

Static pressure!

pressure e"erted in all directions #y a fluid at rest

$elocity pressure!

pressure e"erted #y t%e velocity of a fluid ⇒ $% & ' ρ v 2

&otal pressure!t%e sum of static and velocity pressures

'ir flow

&P SP $P

&P ( SP ) $P ⇒ $P ( &P * SP


5/82 +June 2009Process Engineering Program – Gas Handling – Fan Systems

Airflow SystemAirflow System

, ( -onstant c%aracteristic

ρ ( Gas density. ( $olume flow

P/ P2∆P

. .

∆% & ! ρ (2


6/82 June 2009Process Engineering Program – Gas Handling – Fan Systems

System Resistance

Eac% component in a system offers resistance to air flow

System resistance! t%e total of t%ese resistances to flow1

#efore and after t%e fan

&%e system resistance varies wit% air flow rate

System curve! t%e relation #etween system resistance and

flow rate


7/82 June 2009Process Engineering Program – Gas Handling – Fan Systems

Different Types of System Curves

-onstant static %ead airflow t%roug% a li3uid

poolAirflow rate Q

S y s t e m

r e s i s t a n c e P ,P =∆

-ompletely laminar flow airflow t%roug% filter

#agAirflow rate Q

S y s t e m

r e s i s t a n c e

P,.P =∆


8/82 4June 2009Process Engineering Program – Gas Handling – Fan Systems

Airflow rate Q

S y s t e m

r e s i s t a n c e

P

Airflow rate Q

S y s t e m

r e s i s t a n c e

P

Different Types of System Curves

Slig%tly tur#ulent flow airflow t%roug% a grain

#in

-ompletely tur#ulent flow most fan systems

2,.P =∆

+5/,.P =∆


9/82 9June 2009Process Engineering Program – Gas Handling – Fan Systems

System Curve 6imit discussion to t%e completely tur#ulent system curve

Same principles apply to ot%er types

2(! % ρ =∆

0

2

4

/0

/2

0 20 0 0 40 /00

Q (m³/s)

P ( m m

! " )


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Fan Performance Curve


11/82//June 2009Process Engineering Program – Gas Handling – Fan Systems

Fan PressuresFan Pressures Fan &otal Pressure 7F&P8

&%e European way

)% & )% 2 # )% *

& % 2 + $% 2 # % * # $% *

Fan Static Pressure 7FSP8

&%e 'merican way

% & )% 2 # )% * # $% 2

& % 2 # % * # $% *

Fan Static ise

% ,ise & % 2 # % *

/

2


12/82/2June 2009Process Engineering Program – Gas Handling – Fan Systems

Fan Performance CurvesFan Performance Curves

Pressure vs $olumetric flow rate given #y t%e fan 'pplica#le for fi"ed specific operating conditions!

gas density fan speed

:sually1 power curve is given Sometimes1 efficiency curve

Flow rate

P r e s s u r e

P o w

e r / # f f i c i e n c


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/;June 2009Process Engineering Program – Gas Handling – Fan Systems

Fan #fficiency

S

O

S S S S

t P P

P t

W

P t

S F

P t

V

A

F

P Q P ==

×

=×

=×∆=η

0

/00

200

;00

00

+00

00

00

400

0 /00 200 ;00 00 +00 00 00 400 900 /000

Flow Rate (m³/s)

F a n

S t a t i c P r e s s u r e ( P

0

20

0

0

40

/00

/20

/0

/0

P o w e r ( $

P


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/June 2009Process Engineering Program – Gas Handling – Fan Systems

Fan #fficiency

&otal efficiency η t 7mec%anical efficiency8!

Static efficiency η s

S

t P

FTP Q

××=

6362η

S

t s P

FSP Q

FTP

FSP

××

==6362

η η

S

t P

FTP Q ×=η

:S units

S

t s P

FSP Q

FTP

FSP ×==η η

metric units

Q ! m=>s

FTP, FSP ! Pa P S ! ?

Q ! ft=>s

FTP, FSP ! in5 H2< P S ! HP


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/+June 2009Process Engineering Program – Gas Handling – Fan Systems

Typical Fan CurvesTypical Fan Curves

Performance Curve for IE 250 Fan

FSP

BHP

Efciency

0

5

10

15

20

25

0 5000 10000 15000 20000 25000 30000 35000

Flow Rate (cfm)

0

20

40

60

80

100

120

140

Operating conditions

1518 RP

!0"F# 600 $t e%e&'

Operating point(

130!1 c$)

18#0 in' H2O SP

5!#4 BHP


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FSP vs FTPFSP vs FTP


FSP

F*P

BHP

Static

Efciency

*ota%

Efciency

0

5

10

15

20

25

0 5000 10000 15000 20000 25000 30000 35000

Flow Rate (cfm)

0

20

40

60

80

100

120

140


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Fan Performance an% System CurvesFan Performance an% System Curves


FSP

BHP

Efciency

0

2

4

6

8

1012

14

16

18

20

0 5000 10000 15000 20000 25000 30000 35000

Flow Rate (cfm)

0

20

40

60

80

100

120

140


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Fan Types an% Terminolo&y


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/9June 2009Process Engineering Program – Gas Handling – Fan Systems

Types of FansTypes of Fans

-entrifugal Fans E"tensively used in cement plants!

-lin,er cooler fans

@A fan Bill ventilation fans Aust collector fans

'"ial Fans Ciln s%ell cooling fans Hair #lower 'irplaneDs propeller

&wo large classes!


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#'plo%e% iew of a Centrifu&al Fan#'plo%e% iew of a Centrifu&al Fan

Stationary @nlet

@nlet ell

Scroll

-utoff ac,plate

lades

@nlet Guide $anes

@mpeller

@nlet


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2/June 2009Process Engineering Program – Gas Handling – Fan Systems

Centrifu&al Fan PrinciplesCentrifu&al Fan Principles

$t

$r $ $r ! radial velocity

$t ! tangential velocity

$ ! fluid velocity


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Centrifu&al FanCentrifu&al Fan


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2;June 2009Process Engineering Program – Gas Handling – Fan Systems



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2+June 2009Process Engineering Program – Gas Handling – Fan Systems

Cutaway iew of a anea'ial FanCutaway iew of a anea'ial Fan

Aiffuser

&ailpiece

7sometimes omitted8


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Centrifu&al Fan Principles


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Fan la%e TypesFan la%e Types

Aifferent types of fans c%aracteried #y t%eir #lade type! Straig%t radial Forward curve adial tip

ac,ward inclined * flat #lade 'irfoil

Aifferent applications re3uire different #lade type

Eac% type %as different fan performance curves


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Ra%ial la%e Fan (R)Ra%ial la%e Fan (R)

&%e simplest of all centrifugal fans 6ow efficiency 70 to ;8 $ery common due to simple design

Hig% mec%anical strengt% and easy maintenance Power curve increases continually wit% volume Suita#le for %ig% temperatures and very a#rasive environment


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Ra%ial la%e Fan (R)Ra%ial la%e Fan (R)

2824201612840

010

20

30

40

50

60

+0

Volume

F a n S t a t i c P r e s s u r e

80

!0

100

E f c i e n c y


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;0June 2009Process Engineering Program – Gas Handling – Fan Systems

Ra%ial Tip *mpeller (RT)Ra%ial Tip *mpeller (RT)

Bainly used in large sies for process e"%aust and %ot gases &%e ma"imum efficiency moved slig%tly to t%e rig%t of pea, pressure Power still rise continuously @n%erent self*cleaning capa#ility Static efficiency up to /


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;/June 2009Process Engineering Program – Gas Handling – Fan Systems

Ra%ial Tip *mpeller (RT)Ra%ial Tip *mpeller (RT)

0

1020

30

40

50

60+0

80

Volume


E f c i e n c y

!0

100

110


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Forwar% Curve% *mpeller (FC)Forwar% Curve% *mpeller (FC)

Hig% pressure and volume capa#ilities

6ower speed re3uired for same volume and pressure

:sed for furnaces and H$'- applications

Ba"imum efficiency almost at pea, pressure

Power increases constantly wit% volume

lade configuration in%erently wea,

ot recommended wit% %ig% dust loading


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;;June 2009Process Engineering Program – Gas Handling – Fan Systems

Forwar% Curve% *mpeller (FC)Forwar% Curve% *mpeller (FC)

Volume

0

10

20

30

40

50

60

+0

80!0


E f c i e

n c y


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;June 2009Process Engineering Program – Gas Handling – Fan Systems

ac+war% *ncline% la%es (*)ac+war% *ncline% la%es (*)

on*


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;+June 2009Process Engineering Program – Gas Handling – Fan Systems

ac+war% *ncline% la%es (*)ac+war% *ncline% la%es (*)

242220181614121086420

0

10

20

30

40

50

60

+0

80

Volume


E f c i e

n c y

!0

100


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ac+war% *ncline% Airfoil (AF)ac+war% *ncline% Airfoil (AF)

Bost efficient centrifugal fan! 4+*90 and more &wo*s,in airfoil #lade design 7usually %ollow8 Full on*


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ac+war% *ncline% Airfoil (AF)ac+war% *ncline% Airfoil (AF)

302826242220181614121086420

010

20

30

40

50

60+0

80

!0

Volume

100

110

120


E f c i e

n c y


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Types of la%es , Summary

'irfoil 7'F8

90

Backward-curved (BC)85%

Backward-inclined (BI)78%

Radial-tip (RT)70%

!rward-curved (C)65%

Radial "lade (RB)60%


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-nsta.le Ran&e-nsta.le Ran&e

ea!

Flow Rate

"nsta#le Sta#le

P


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Fan aws


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Fan awsFan aws

ρ∗∗ρ∗∗

∗=−

∗ρ∗∗∗ρ∗∗

∗=−

∗∗

∗=−

/

+

/

;

/

2

+

2

;

2/u2u

2p/

2

/

2

/

/p22

22

2

/2

;

//

;

22/2

A

APP!Power

,A

,App!essurePr

A

A..!$olume


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Fan awsFan aws

Fan performance curve made for specific conditions! fan speed air density 7temperature1 pressure8

?%at %appen in ot%er conditionsI ?%at if @ c%ange t%e speed of t%e fanI 78 ?%at if t%e gas density c%angesI 7 8 ?%at if @ c%ange t%e sie of t%e fanI 7A8


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Fan aws , C0an&e in Spee%Fan aws , C0an&e in Spee%

$olume is directly proportional to fan speed

Pressure is proportional to t%e s3uare of t%e velocity

Power is t%e product of volume #y energy

Q

Q

N

N 2

#

2

#

=

TP

TP

SP

SP

VP

VP

N

N 2

#

2

#

2

#

2

#

2

= = =

P P

N N

2

#

2

#

3

=

# l C0 i F S %#'ample C0an&e in Fan Spee%


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#'ample , C0an&e in Fan Spee%#'ample , C0an&e in Fan Spee%

' fan running at /;0+ PB delivering 5/ m=>s wit% a total pressure of +

mm Hg consumes 5+ ,?5 ?%at s%ould #e t%e fan speed to increase t%eflow rate to 45+ m=>s if t%e system curve does not c%angeI

?%at would #e t%e impact on t%e total pressureI

?%at is t%e impact on powerI

N Q N

Q RPM 2

2 #

#

8 5 #305

7 ##562= = × =$

$

TP TP N

N mmHg 2 #

2

#

2 2

57 #562

#3058# 7=

= ×

= $

P P N N

kW 2 #2

#

3 3

66 5 #562

#305##% 0=

= × =

$ $

C0 i S %C0 i S %


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+June 2009Process Engineering Program – Gas Handling – Fan Systems

C0an&e in Spee%C0an&e in Spee%


$5$% RP&

$'0 RP&

$%22 RP&

0

5

10

15

20

25

30

0 5000 10000 15000 20000 25000 30000 35000 40000

Flow Rate (cfm)

0

50

100

150

200

250


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Fans aws , C0an&e in 1as DensityFans aws , C0an&e in 1as Density

Fans are constant volume mac%ines 'ffects t%e pressure generated and power consumed ' c%ange in density also affects t%e system curve

TP

TP

SP

SP

VP

VP

2

#

2

#

2

#

2

#

= = = ρ

ρ

P

P 2

#

2

#

= ρ ρ

C0an&e in 1as DensityC0an&e in 1as Density


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C0an&e in 1as DensityC0an&e in 1as Density


$$* !+,m-

05' !+,m-

0

2

4

6

8

10

12

14

16

18

20

0 5000 10000 15000 20000 25000 30000 35000

Flow Rate (cfm)

0

20

40

60

80

100

120

140

160

Operating conditions1518 RP

!0"F# 600 $t e%e&'


48/82


#ffect of Density on Fan Selection#ffect of Density on Fan Selection

Aust collector on inlet side of fan

total pressure drop! 20 mm Hg

inlet of fan! *20 mm Hg

-lin,er cooler fan

total pressure drop! 20 mm Hg

inlet of fan! atmosp%ere

For same air flow1 fan selection would #e differentdue to density c%ange at fan inlet


49/82


Fans aws , C0an&e in Si2eFans aws , C0an&e in Si2e

:sed mostly to compare two similar fans of same type Some e"amples of tipping outK fans -asing often %as to #e redesigned

Q

Q

D

D

2

#

2

#

3

=

TP

TP

SP

SP

VP

VP

D

D2

#

2

#

2

#

2

#

2

= = =

P

P

D

D2

#

2

#

5

=

C0an&e in Si2eC0an&e in Si2e


50/82

+0June 2009Process Engineering Program – Gas Handling – Fan Systems

C0an&e in Si2eC0an&e in Si2e


.

/$0 .

0

2

4

6

8

10

12

14

16

0 5000 10000 15000 20000 25000 30000 35000

Flow Rate (cfm)

0

10

20

30

40

50

60

+0

80

!0

100


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Flow Control

Fl C l


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Flow ControlFlow Control

e3uirement to control t%e air flow from a fan &%e system resistance curve governs t%e fan output

'ir flow can #e c%anged #y c%anging!

t%e fan curve

t%e system resistance curve 'vaila#le met%ods!


53/82

+;June 2009Process Engineering Program – Gas Handling – Fan Systems

"utlet ouvre Dampers"utlet ouvre Dampers

Bore flow on one side of duct ot very linear response

Parallel la%es "ppose% la%es

Lields more uniform profile

Bore linear response

&%e outlet louvre dampers c%ange t%e

system resistance curve Power wasting devices


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"utlet ouvre Dampers"utlet ouvre Dampers

10 oen

'0 oen

%0 oen

i3e oen

20 oen

0

20

40

60

80

100

120

0 10000 20000 30000 40000 50000 60000 +0000 80000


55/82

++June 2009Process Engineering Program – Gas Handling – Fan Systems

aria.le *nlet anesaria.le *nlet anes

@nstalled at t%e inlet of t%e fan -ontrols volume and direction of air flow Aesigned to give a spin to t%e air in direction of impeller Pre*spin unload t%e impeller reducing t%e pressure 6ess pressure implies less power

Close% Position "pen Position


56/82


aria.le *nlet anesaria.le *nlet anes

100,+5,50,25, open0

10

20

30

40

50

60

+0

80

!0

100

0 10000 20000 30000 40000 50000 60000 +0000 80000

0

10

20

30

40

50

60

+0

80

!0

100


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*nlet ouvre Dampers*nlet ouvre Dampers

Similar to inlet vanes! pre*spin effect

lades always parallel

Bust #e used wit% an inlet #o"

Power efficiency! a little less t%an inlet vanes5 Easier to maintain t%an inlet vanes 7%ot and

dusty applications8

aria.le Spee% Fansaria.le Spee% Fans


58/82


p

Airect application of t%e fan laws!

Baintain same efficiency at different speeds

&%e most efficient met%od of controlling fans

Hig%er initial cost

/

2

/

2

-

-

(

( =2

/

2

/

2

/

2

/

2

===-

-

$%

$%

+%

+%

)%

)% ;

/

2

/

2

=-

-

%

%

Spee% C0an&e , Constant #fficiencySpee% C0an&e , Constant #fficiency


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Spee% C0an&e Constant #fficiencySpee% C0an&e Constant #fficiency

η ## #

#

= ×Q TP

P

Q Q N

N 2 #

2

#

=

TP TP

N

N 2 #

2

#

2

=

P P N

N 2 #

2

#

3

=

η 22 2

2

#2

#

#2

#

2

#2

#

3

# #

#

= × =

×

= ×Q TP P

Q N

N TP

N

N

P N

N

Q TP

P

Fan laws!

Efficiency!

*mpact of Flow Control on Power*mpact of Flow Control on Power


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*mpact of Flow Control on Power p

$aria#le

speed


61/82


Drive Arran&ements

elt drive

Standard speed motors can #e

used no need for slow speed

motors 7e"pensive 8

E"act fan speed for re3uired air

and volume can #e o#tained

Speed can #e adMusted #y simply

c%anging pulley ratio

Airect drive

educes initial cost if standard

speed motor could #e used no e"tra supports1 pulleys1

#earings1 s%afts

Elimination of power loss #y #elt

drive 7+ to /08

o maintenance re3uired from

stretc%ing #elts

o possi#le c%ange to fan speed unless varia#le speed drive

Fan Selection


62/82


Fan Selection

6afarge preferred specifications!

Safety margin! /0 on volume 2/ on pressure

ma"imum fan speed /400 PB for motors N ;00 HP

/200 PB for motors O ;00 HP /200 PB for dusty and>or %ot conditions

$aria#le inlet vane dampers or varia#le speed

$*#elt drive


63/82


Beasured operating point may not fall on t%e fan curve

Aue to measurement errors and fan system effects @n Fan-urves spreads%eet1 t%e flow rate is assumed correct

Actual fan curve (456,!77)


64/82

System #ffect


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#l.ows

Good

ad


66/82


Fan *nlet

Duct ranc0es


67/82


Turnin& anes


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Fan Au%it 1as an%lin& / T5TP Power

Fan Au%it Pro&ram


70/82


Bany fans donDt operate at optimal point


71/82


".9ective

educe energy consumption

@ndicators!

,?% a#sor#ed #y t%e motor Fan efficiency

Fan relia#ility factor

Preparation


72/82


6ist fans t%at ma,e up for 40 of power consumption

flows%eet

'de3uate position of measuring points

-reation of a common 7Baintenance1 Process8 file

:easurements

Fl t


73/82


Flow rate

For one operating point

Bore could #e re3uired for fans wit% wide ranges of operatingpoint

Static pressure at fan inlet

after damper if any

#efore varia#le inlet vane if any

Static pressure at fan outlet

#efore damper if any

Static pressure on ot%er side of damper

to determine pressure drop t%roug% damper

Aamper opening

:easurements


74/82


Gas temperature and composition

for density moisture content if significant

correction for dust load if significant

Fan speed

'#sor#ed power Fan elevation

'tmosp%eric pressure

'm#ient air temperature

:easurements for Fan Static Pressure


75/82


: 0 i l # l ti


76/82


:ec0anical #valuation

E"ternal inspection 7fan running8! earings temperature

$i#rations of #earings and %ousing

oise level 6ea,age 7%oles in %ousing1 ducting1R8

Even air flow distri#ution at fan inlet

Pressure drop t%roug% dust collector 7if any8

:ec0anical #valuation


77/82


@nternal inspection 7fan stopped8!

Fan impeller alignment

@mpeller and %ousing! wear and material accumulation Aampers! proper opening > closing1 damages and material

accumulation

6ouvers! configuration of #lades1 functioning of individual #lade

&urning vanes condition

elt drive! tension and wear -oupling alignment

@nternal cone adMustment 7too large a gapI8

'ccumulation of material in t%e duct

&ype of fan w%eel! to confirm drawings > fan curve

$alidation of e"isting drawings

A%%itional *nformation


78/82


Fan system diagram s%owing!

fan

damper 7position and type8

position in relation wit% its environment

el#ows

duct e"pansions1 contractions

turning vanes

Statistics on flow1 pressures and damper opening

'spen > @P2/

Fan curve

-orrect to actual conditions 7elevation1 temperature1 density1 PB8

Fan and motor nameplate information

# l ti


79/82


#valuation

Position operating point on fan curve Aoes it matc%I ?%yI

-alculate efficiency

@s it goodI How can we improve t%e efficiencyI

How can we increase flow or pressure1 if re3uiredI

Fan Desi&n


80/82


Fan Desi&n

Poor efficiency fan design costs all t%e time

Bany pre*/94+ fans are straig%t radial!

0*+ efficiency

-urrent tec%nology! -urve radial 7dirty air8! to 42 efficiency

'irfoil 7clean air8! to 4+ efficiency

ow Cost Solutions


81/82

4/June 2009Process Engineering Program – Gas Handling – Fan Systems

ow Cost Solutions

@s Hermit -ra# solution possi#leI -an s%aft #earing #e retainedI

-an you ta,e advantage of t%e need to replace an impeller

for maintenance reasonI

@s t%ere a retired fan t%at could do t%e Mo#I @nlet turning vanes can improve efficiency #y 2

@s t%ere a way to modify ducting configuration to reduce

system effectI

Report


82/82


Summary

Beasurements

Bec%anical o#servations

fans efficiancy.pptx

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