blowers 1

[malagigi]

hello,
i would like to ask you which blower is more suitable for a mixed bed regeneration process and also which is the difference between a rotary piston type and a roots blower.
we have as process design 130 Nm3/hr and 400 mBar differential pressure for the air.
thank you in advance
Daniele

 

[Montemayor]

malagigi:

I've used every type of blower that is available out in the marketplace and I've yet to hear of a "rotary piston type". Any displacement machine utilizing a piston is inherently intended for relatively high pressures. This characteristic would, by logic, put it out of the blower classification (inches of water column total head) and into the compressor classification - approx. > 15 psig.

I've used the Roots-Connersville rotary lobe blower for the regeneration of Hydrogenation catalyst and it's worked very well. The Roots patent is now copied by many other manufacturers. I always used the XA model which was for heavier duty and had its bearings on the outside and independent packing glands on both shaft ends. This model also had a higher discharge pressure rating - 15 psig as I recall.

I've also used multi-staged centrifugal blowers for this purpose and found them OK as well - although I don't like the characteristic variance of the capacity with the discharge head. The Roots blower is a semi-positive displacement machine and delivers a pretty constant flow of air - regardless of the discharge pressure variance; therefore, it's easier to design a system for it.

I hope this experience helps out.

Have you thought of posting this query in the Compressor Forum instead of here? I believe it would be more appropriate there and probably get more response from interested parties.

Art Montemayor
Spring, TX

 

[cub3bead]

A Roots type rotary lobe blower is the way to go unless you have a lot of excess air capacity in your instrument air system. If you hook it up to your instrument air system you will likely need a local receiver and make sure that you put a back pressure regulator on the air supply to it otherwise you might dump you header pressure to low and trip off the rest of the plant. The key is to have it oil free, dry is not necessary.

You need about 7 psig of discharge pressure and 7 Scfm/sq. ft. of internal vessel area to do the job.

 

[smckennz]

Hi Malagigi

yeah, I'd go for a Rootes on this one as well. Just make sure you maintain flow; excessive backpressure makes them overheat and they dont like it.
Its a bit small for a centrifugal to be economic (installed) and the pressure is too low for anything else.

Cheers

Steve

 

[Torricelli]

Daniele,

In 1854, Francis and Philander Roots, woolen mill owners in Connersville, IN, stumbled upon the principles that drive the rotary positive displacement concept….

http://www.rootsblower.com/aboutus.cfm?Call=HISTORY

… In 1944, Dresser Industries, Inc. acquired ROOTS to expand its range of services for the gas and oil industries.

“Roots” is a trade name, other manufacturers say “rotary positive blower” or “rotary piston” blower.

ET

http://www.vacuum-guide.com