Contents
To download the below and all other Useful Books and calculations Excel sheets please click here
To download the below and all other Useful Books and calculations Excel sheets please click here
Main Fans in Cement plant
by Daniel Brassel / Jan C. Kaminsky (CTS – TPT)
Things that I want to talk about…
- Design and Efficiency of Impellers
- Fan Equations and Performance Curves
- Flow Control
- Operational problems
Learning Objectives
- Know principal impeller designs
- Understand basics of fan equations and fan curves
- Know different types of flow control
- Understand what influence the reliability
Enormous power consumption by main fans
Altogether these fans consume between 30% and 50% of the plant’s total electrical energy.
- Kiln ID Fan
- Raw Mill Fan
- Cooler Exhaust Gas Fan
- Kiln Dedusting Fan
The lower the dust load the better the fan can be
power consumption Equation for Main Fans
Saving money with high efficiency fans
Fan performance curves to be proven in plant
derived from laboratory data
conditions at fan inlet
Definitions:
-Fan static pressure
– Fan power
-System resistance curve
Operating point where curves meet
For Plant Performance
Volume Flow
Static Pressure
Power Requirement
Lower pressure achieved at higher temperature
The static pressure generated by the fan is depending on the gas density, i.e. type of gas and temperature.
Influence of density change
Bad and good flow control
Cooler Undergrate Fan: Radial Inlet Van
Preferred: the variable speed drive (VSD)
Flow Regulation by Outlet Damper
Flow Regulation by Inlet Vane Damper
Flow Regulation by Inlet Box Damper
Flow Regulation by Speed Control
fight the false air
Fan capacity low
System changes:
eliminate false air
reduce pressure drop
Fan changes
increase fan speed
increase wheel diameter
replace rotor
Fans Vibration Invisible because inside
Example of Build-ups
Reason of Sticky dust on Fans Blade
- Mineralogical Composition of Raw Mix
- Burning Conditions
- Duct / Fan Arrangement
- High Temperatures
- Inappropriate Blade Shape and Angles
- High Fan Speed
- Dew Point Problems
Fight the build-ups with modifications
Permanent remedy could be gained through:
- Change of duct / fan arrangement
- Change of fan speed or impeller diameter
- Modification of fan inlet or impeller blade shape
- Larger shaft diameter (stronger design)
- Anti-sticking painting
If the above listed measures do not solve the problem, regular cleaning has to be envisaged
Cleaning the fan on-line
- High pressure water spray
- Steam injection
- Compressed air injection
- Sand blasting
- Acoustic Resonance (ultrasonic)
- Dynamic balancing
Acoustic Cleaning Devices
Sand Cleaning Device
Cracking the dust layer
Erosion / Wear of Cement plant Fans
Blade erosion:
varies in the second or third power of the speed of a particle that hits the blade
particle speed is proportional to the rotor speed
is affected by the wheel inlet velocity?
fan flow divided by smallest inlet section
Cement plant Fans Wear Protection
Direct protection
=Increased thickness of wear parts
= Direct hard surfacing
=Glued-on ceramics (but: for example max. 130 °C)
Protection by wear plates
-Corners or mild steel plates
-Abrasion resistant steel plates
-Mild steel plates with hard surfacing
Deflector plates
Wear Protection by Particle Deflection
Example of Deflector Plates
Which fan is right?
Continuous operation
–vibrations
–build-ups
-wear
Fan efficiency
–mechanical design
–type of regulation
for more information please