This document discusses fans and their operation. It defines different types of fans including axial fans like propeller, tube-axial, and vane-axial fans. It also defines centrifugal fans and describes their impeller types like backward curved, forward curved, and airfoil. The document discusses factors that determine the suitable fan type like aerodynamic and operational requirements. It also provides equations for calculating fan power requirements and performance at variable speeds. Examples are given showing potential energy savings from improving fan efficiency or using variable speed control instead of a throttle valve.

1. FANS

2. Introduction ‫المقدمة‬
o Air makes 90 – degree – angel turn from inlet to outlet.
o Several arrangements of fan blades.
o Air foil or backward curved (curved blades and similar to cross section
of an airplane wing).
o Backward curved blades (simple thickness).
o Straight radial.
o Forward curved blades.
 In modern cement plants, fans consumes 25-30% of total electrical power used
for cement manufacture.
 Design of fans involves the required ranges of gases flow, static pressure, gas
density and optimization efficiency.
 Most fans type used axial flow fans, centrifugal flow fans according to the
direction of flow through impeller.
 Axial fan sub decided into 3 categories:
1- Propeller.
2- Tube axial.
3- Vane axial.
 Centrifugal fans:

3. A Fan
is a device that causes flow of a gaseous
fluid by creating a pressure difference on
the medium to be transported
A Blower
blower is similar to fan, except that it can
produce a much higher static pressure
Definitions
‫تعريفات‬
‫مروحة‬
‫مروحة‬
(
‫هواء‬ ‫نافخ‬
)

4. Centrifugal fans Axial fans
Forward curved
Backward inclined
Airfoil
Radial blades
Tube-axial fan
Propeller fan
Vane-axial fan

5. Vane-axial fan
Propeller fan
Axial fan types

6. Tube-axial fan
Axial fan types
‫المحورية‬ ‫المراوح‬ ‫أنواع‬

7. ,
Centrifugal fans characteristics
‫الطاردة‬ ‫المراوح‬

8. Impeller types
‫الريش‬ ‫أنواع‬

9. Radial
Fan Blades
Flat
S-Shape
‫المروحة‬ ‫ريش‬

10. Backward curved
Forward Curved

11. Airfoil

12. Inlet control vanes
‫المدخل‬ ‫هواء‬ ‫موجه‬

13. Inlet control vanes
‫المدخل‬ ‫موجهات‬

14. Two groups of factors will determine suitable type of
fan
Aerodynamic requirements (flow, pressure rise,
temperature, gas analysis)
Operational considerations (dust content,
temperature fluctuations, variation in load etc
Fan selection ‫المروحة‬ ‫إختيار‬

15. Access Doors
Inlet Bell
Outlet Dampers
Inlet Vanes Inlet Boxes
Shaft Coolers Shaft Seals
Drains
Other Accessories
Fan accessories ‫المروحة‬ ‫ملحقات‬

16. Airflow entering a round duct with a venturi inlet at duct entrance.

17. Rectangular duct
Round duct
Measurement points
Total pressure = static pressure + velocity pressure
Pitot tube
Flow measurements
Velocity
pressure
Static
pressure
total
pressure
Volume air
flow rate
pt
ps
pv
‫التدفق‬ ‫قياسات‬

18. The performance of fans is easily determined by calculations based on
measured data taken at the fan inlet and outlet
Factors can affect the accuracy of the field measurements
Air flow not at right angles to the measurement plane
Non-uniform velocity distribution
Irregular cross sectional shape of the duct or passageway.
Air leaks between the measurement plane and the fan
Fan Performance Measurements
‫المروحة‬ ‫أداء‬ ‫قياسات‬

19. Fan curves
system curves
Performance curve
‫األداء‬ ‫منحنى‬

22. Sheave alignment
Always use matched v-belts and never
mix new and used v-belts on a drive
V-belt drive installation
‫الحركة‬ ‫نقل‬ ‫سيور‬ ‫تركيب‬

23. Fan Equations ‫المروحة‬ ‫معادالت‬
]
[
10 3
kw
Px
Vx
N




Power requirement
Where
V = Quantity of gas delivered [m3/s]
ΔP = Total increase of pressure in fan [Pa]
η = Fan efficiency according to curve [%]

24. Formula for rough calculation o f the total pressure p (static pressure +
dynamic pressure)
Total Pressure ‫الكلى‬ ‫الضغط‬
Where
∫ = density [kg/m3]
N = Fan speed [rpm]
D = Impeller diameter [m]

25. 1
1
2
2 V
n
n
V 
Fan Equations at Variable Speed ‫مختلفة‬ ‫سرعات‬ ‫عند‬ ‫المروحة‬ ‫معادالت‬
1
2
2
1
2
st
st P
n
n
P 








3
1
2
1
2 








n
n
N
N
Volume flow
Power Requirement
Static Pressure
For η1 = η2

26. 3000 t/d 4 stage SP kiln, kiln ID-fan
V = 115 m3/s at 350 oC
ΔP = 6000 Pa
η1 = 0.75
η2 = 0.85
Example no. 1: Effect of fan efficiency ‫رقم‬ ‫مثال‬
(
1
:)
‫المروحة‬ ‫كفاءة‬ ‫تأثير‬
kw
x
x
Vx
N 920
75
.
0
10
6000
115
P 3
1
1 





kw
x
x
Vx
N 812
85
.
0
10
6000
115
P 3
2
2 





Power saving = 108 kw
Corresponding to = 0.86 kwh/t cli
Assuming an operation time of 7500 h/year and an energy price of 0.05
US$/kwh the yearly saving will amount to 40'500 US$.

27. Energy Saving Aspects ‫الطاقة‬ ‫توفير‬ ‫مظاهر‬
Depending on the blade shape of the impeller, the power requirement to draw
the gas through a given system (and therefore for determined pressure losses)
can vary in a relatively wide range.
As the required fan power is given by the equation

3
10


Px
Vx
N
Where
N = Required power [kw]
V = Quantity of gas delivered [m3/s]
ΔP = Total increase of pressure in fan [Pa]
η = Fan efficiency
it is obvious that considerable savings can be achieved with the most
efficient impeller.

28. Example no. 2: Throttle Valve Control vs. Variable Speed Control
‫رقم‬ ‫مثال‬
(
2
:)
‫المورحة‬ ‫سرعة‬ ‫تغيير‬ ‫أو‬ ‫الخانق‬ ‫الصمام‬ ‫بإستخدام‬ ‫الهواء‬ ‫كمية‬ ‫فى‬ ‫التحكم‬
Design operating point A
Volume flow = 120 m3/s
ΔP of the system = 6500 Pa (at 120 m3/s)
η of fan = 0.82
Fan speed = 1000 rpm
Power consumption = 907 kw [100%]
Actual operation point B
Variable valve control (BVSC)
Throttle valve control (BTVC)
90 m3/s
90 m3/s
Volume flow
x 6500 = 3650 Pa
7500 Pa
ΔP of the system
0.82
0.82
η of fan
x 1000 = 750 rpm
1000 rpm
Fan speed
2
120
90






120
90
Power Consumption
%]
90
[
823
82
.
0
10
7500
90 3
kw
x
x
N TVC
B 


%]
44
[
400
82
.
0
10
3650
90 3
kw
x
x
N VSC
B 



29. Any Questions ?