2. Use and performance comparison of blowers in the cement industry
Across cement plant operations, the blowers most commonly found are Roots blowers and conventional centrifugal blowers, both of which are high-energy, high-noise machines.
(1) Roots blowers. The Roots blower is a constant-flow machine. It has the advantages of a simple design, good adaptability and a low price, but its drive train needs lubricating oil and it has the drawbacks of high energy consumption, high noise, strong vibration and high maintenance costs. In the cement industry it is commonly used for the rotary kiln, kiln-head primary air, and air supply to raw meal silos and precalciners.
(2) Conventional centrifugal blowers. The conventional centrifugal blower is a constant-pressure machine, classified as single-stage or multistage according to the number of impellers. In operation its air flow varies with the piping or load while the pressure changes little. It is characterized by high noise, fairly stable pressure and a relatively wide flow range. In the cement industry it is commonly used for kiln-head and kiln-tail stack exhaust, coal mill exhaust, the kiln-tail high-temperature fan and similar duties.
Performance comparison of common blowers (Table 1)
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Blower type
Roots blower
Multistage centrifugal blower
Single-stage centrifugal blower
Air-bearing centrifugal blower
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Compression principle
Positive displacement
Centrifugal
Centrifugal
Centrifugal
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Overall efficiency, %
< 62
< 65
< 70
> 70
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Flow turndown, %
100
60-100
50-100
45-100
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Noise, dB
> 100
95-100
90-95
< 85
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Vibration
Very high
High
High
None
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Lubrication
Lubrication system
Lubrication system
Lubrication system
None
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Maintenance
Frequent maintenance
Periodic maintenance
Periodic maintenance
Periodic replacement of the air filter element
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Service life, years
1-5
< 10
< 10
> 15
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Size
Large
Large
Large
Small
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Installation and civil works
requirements
Must be anchored to the floor;
sound insulation required
Must be anchored to the floor;
sound insulation required
Must be anchored to the floor;
sound insulation required
No anchoring required;
no sound insulation required
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Price
Low
Medium
Medium-high
High