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Why talk about dust collection?“The accompanying phenomenon of comminution, handling and processing … the material components which finally form Portland cement is the generation of dust .”
- from Duda’s Cement Data-Book
© 2010, General Electric Company
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2000 mtpd = approx. 1400 kg/min of cement production
Typical 2000 mtpd cement plant
2610 kg/min 1400 kg/min
= 1.9 kg of dust collected for every kg of cement produced!
© 2010, General Electric Company
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Major components of a dust collection system
© 2010, General Electric Company
DuctworkFan
Dust Removal SystemVent Hood
Dust Collector
Basic concept of a dust collection system
Ideally, it’s not a dust collect ion system,it’s a dust containment or cont rol system
© 2010, General Electric Company
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Ultimate goal of a dust ventilation system
Provide maximum dust control and containment with a minimumof dust collection
© 2010, General Electric Company
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The volumetric flow rate of air or gas per unit of time
Usual units are:• Cubic feet per minute (cfm)• Cubic meters per minute (m3/min)• Cubic meters per hour (m3/h)
Air flow or gas flow
© 2010, General Electric Company
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Hood design
© 2010, General Electric Company
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Vent points and hoods are probably the most overlooked component of a dust control system
For enclosure type hoods:
Q = V x A
Q = Ventilation Airflow Rate (cfm)
V = Capture Velocity (fpm)
A = Total Open Area on Enclosure (sq. ft .)
© 2010, General Electric Company
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Bucket elevator ventilation
© 2010, General Electric Company
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ImprovedDesign
TypicalDesign
Bet terDesign
Ball mill ventilation (open end mill)
© 2010, General Electric Company
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Exhaust Air
Product discharge
Poor design
Exhaust Air
Product discharge
Bet ter design
Air or gas flow in a duct
Q = V x A
Q = Air or Gas Flow (cfm)
V = Transport Velocity in Duct (fpm)
A = Cross-Sectional Area of Duct (sq. ft .)
© 2010, General Electric Company
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Duct design
© 2010, General Electric Company
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Acceptable Recommended Acceptable Acceptable
Recommended Recommended Recommended Recommended
Avoid Avoid Avoid Avoid
Type of filter Maximum recommendedcleaning system air-to-cloth rat io
Shaker 3.0Reverse Air 2.0Pulse-Jet :A. Cylindrical Filter Bags 6.0B. Pleated Filters (Non-Paper Media) 3.5C. Pleated Filters (Paper Media) 2.0
Plenum Pulse 4.0
Air-to-cloth ratio
© 2010, General Electric Company
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Can velocityIn a pulse jet dust collector with the filter elements suspended from the tubesheet, can velocity is the upward air stream speed passing between the filters calculated at the horizontal cross-sectional plane of the collector housing at the bottom of the filters
© 2010, General Electric Company
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Photohelic® gaugeAn instrument used to measure and control baghouse differential pressure; having adjustable set points that can be used for starting and stopping the baghouse valve-firing timer board, to maintain a desired range of operating differential pressure.
© 2010, General Electric Company
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Cubic Feet per minute (CFM)
Stat ic Pressure
12” } Out let Duct
1” } Pickup Hood
11”
Baghouse + Media
5”
Ductwork to Baghouse
Q1
SP = Constant x Q2
System curve
© 2010, General Electric Company
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System and fan curves
© 2010, General Electric Company
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Pres
sure
(P)
Fan
Desired
BaghousePressure
SystemPressure
Flow Rate (Q)
Recommended