Blowers for Aerobic tank

Question

Blowers for Aerobic tank

vjr0512 (Mechanical)

(OP)

21 Mar 16 00:50

In an integrated ETP facility ( refinery+ petchem), for an aerobic tank, the contractor is suggesting to go for a Tri-lobe blower ( capacity around 2200 Nm3/hr with a discharge pressure of around 0.7barg. The temperature at the discharge of the blower is said to be around 125 deg C.

Is it ok to go for a Tri-lobe blower for such a huge capacity? i understand from various articles that above 450 Nm3/hr , centrifugal type blowers are preferable. Also will there be such a huge temperature rise across the blower having the suction temperature of around 35 deg C? Will this hot air will have any problem while it is diffused inside the aerobic tank or the diffuser pipe ( CPVC) or the diffusers ( EPDM)?

Thanks to advise

ashtree (Bioengineer) · Answer 1 · 2016-03-21 09:45:58

vjr0512

There are plenty of trilobes on the market for that size and larger. The "recommendation" regarding the centrifugal goes more the other way in that you probably would not choose(perhaps not even be able to buy) one below 450Nm3/hr. You have not really provided enough information to know which is best but each type has its pros and cons.

To have an operating temperature that high means that the specifier must have the blower running very fast to do the duty with a lot of internal compression. If i was doing it i would specify a larger blower and run it a little a little easier. The heat is a concern for downstream equipment but more so for the blower itself and the equipment around it such as motors , belt drives , acoustic covers etc.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

vjr0512 (Mechanical) · Answer 2 · 2016-03-21 13:08:49

Thank you very much ashtree. I thought i have provided all the information. My query was that for a capacity of 2200 Nm3/hr whether we can go for Centrifugal blower or we need to choose only Positive disp blower? Yes you are right that higher temperatures will have serious implications on its downstream equipment and also for the blower, motor drive belt etc.

Please do ask me what other additional information is required from me on the above subject and i will provide.

Thanks once again for your valuable information.

bimr (Civil/Environmental) · Answer 3 · 2016-03-21 13:45:55

There is a newer rotary model out called a rotary screw. The rotary screw blowers use less energy than conventional rotary blowers and even achieve significant energy savings compared to currently available screw blowers. Plus the rotary screw blowers are quieter.

http://us.kaeser.com/Products_and_Solutions/Blower...

The downstream components are generally under water and will not be affected by heat.

The downside of centrifugal blowers is that the turndown is limited and complicated.

ashtree (Bioengineer) · Answer 4 · 2016-03-26 08:32:27

vjr0512

To decide if a PD blower is required or whether or not a centrifugal blower could do the job here are a couple of things that need to be determined:

1) Does the level of the aerobic tank vary much when it is being aerated. For example is the tank decanted at times or is it the same level all the time?
2) How much turn down or control of air volumes do you require and what controls this?
3) Is noise an issue?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

vjr0512 (Mechanical) · Answer 5 · 2016-03-27 03:48:40

Ashree

I am collecting the informations from Operations team. I will get back with the details shortly

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Blowers for Aerobic tank