ITEM | ROTARY PRESS | THE CENTRIFUGE |
1. | Simple : | More complex : |
---|---|---|
A single drive driving a single rotor. | Two (2) drives – A main drive and a back drive driving two (2) rotors, the bowl and the scroll. | |
Low maintenance. | High maintenance. | |
2. | Low speed: 0,5 to 2,5 RPM max. | High speed: 1500 to 3500 RPM |
No (or very low) live floor loads. Nothing special is required. | High live floor loads. Building needs to be designed especially to deal with these loads. | |
Reduced noise: Nothing special is required. Acoustic protection is not required. | High noise: Noise attenuation is required as part of the building construction. | |
Vibration and temperature: Monitoring is not required for the Rotary Press. | Vibration and temperature: Monitoring of the electric motor, bowl and scroll is very critical. | |
3. | Low Power Consumption : | High Power Consumption : |
Low installed HP and reduced power consumption: 10 kW-hr/dry ton. | High installed HP and high power consumption estimated at 171 kW?hr/dry ton* . The additional power cost over the life of equipment is very significant. | |
No consideration for power factor. | Consideration for power factor. | |
Reduced installation costs for the electrical connection. | High installation costs for the electrical connection. | |
4. | Simple and short start-up and shut down procedures. | More complex and lengthy start-up and shut down procedures. Bowl may continue to rotate for a while after shut down. |
Frequent stops and starts are possible. | Frequent starts and stops are not possible. | |
5. | In the event of an eventual shut down, repairs can be completed at the waste water treatment plant by regular mechanics. | In the event of a shut down, the centrifuge may have to be shipped to the manufacturing plant for specialized repairs. The centrifuge may require visits from specialty mechanics. |
6. | For a multi-channel machine, one or more channel(s) may be removed for maintenance purposes, while the machine with the remaining channel(s) may still be operated. | The whole machine is in operation or it is shut down. |
7. | Vibration analysis and preventative maintenance are not critical. | Vibration analysis and preventative maintenance are very critical. Additional training of plant personnel may be required. |
8. | The Rotary Press includes a flocculator with a variable speed agitator to optimize flocculation and polymer dosage, which most likely results in a reduced polymer consumption. | Flocculation takes place inside the centrifuge and cannot easily be controlled, and may result in a higher polymer consumption and higher annual expenditures. |
9. | More reliable: | Less reliable: |
Very few components of the Rotary Press may cause catastrophic shut down of the equipment due to its low speed and simple design. | Many more components may cause a shut down due to the high speed and high power. | |
10. | A high capture rate is intrinsic in the Rotary Press design giving a reasonable flocculation. | The centrifuge will operate at a lower capture rate, which will reduce further if left unattended. |
11. | The effects of grit are greatly reduced in the slow-moving Rotary Press. | The centrifuge may be affected by the presence of grit in the sludge in the form of unpredictable premature abrasion wear. |
12. | With the Rotary Press, it is possible to obtain very high cake dryness at reduced flow. | The same cake dryness may not be possible with the centrifuge. |
13. | No external lube system is required. | External lubrication system is usually required. |
14. | Low maintenance cost. | High maintenance cost. |
15. | Generally, no shredder is required upstream. | May require a shredder upstream. |
* According to an article written by Mr. Chuzo Nishizaki in the “The Proceedings of the Management of Water and Waste Water Solids for the 21st Century June 19-22, 1994” published by the Water Environment Federation, U.S.A. (p 7?35). |
THE ROTARY PRESS VS THE CENTRIFUGE SYSTEM
Lower power, polymer maintenance costs.
ADVANTAGES
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3787 West Frontenac blvd,
Thetford Mines Quebec, Canada G6H 2B5
Phone: (418) 423-4241
Fournier Rotary Press ™ & Full-Auto Filter Press
Specializes in dewatering municipal wastewater sludge. Discover the advantages of a Fournier Rotary Press ™ vs belt filter press, decanter centrifuge, plate and frame press and screw press.