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Cracking of exhaust blower Impellor

We supplies exhaust blower for Impellor Service. This is used downstream of Flue Gas scrubber, to create draft in the Incinerator. The Impellor gets cracked very fast. Material for Impellor is SS 304 grade. Flue gases contain SO2, traces of dust and it is saturated with moisture, temperature of flue gas is 75 to 80 °C.

Ajay Tulpule
- Pune, Maharashtra, India
2001

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2001

Hi Ajay!

Re your fan, I assume it has to be, should be, a centrifugal design.

On the data you gave, I'd like to think that it is the scrubber design that is at fault allowing dust, condensate and moisture + (wetted!) S02 to contact the fan.

A good scrubber means that it should also have a good mist eliminator!

Mind you, your stainless isn't top grade, is it? But even if you had used 3l6, you'd most probably eventually get cracking around the weld areas.

A good 'eliminator' would be mesh. Highly efficient but also, due to the given dust content, highly liable to plug up, too. On top of that it should be horizontal (for a vertical airflow) and would be quite bulky.

The other alternative is to use a baffle type mist eliminator. Blades made of 3l6. For horizontal airflows. Efficiencies, if you get the 'right' design, to be around or better than 20 micron capture. Disadvantages, apart from price, could be an increase in fan SP performance of around 2" SP depending upon air velocity (max. l,500 fpm!)and twice as much as those higher velocities.

I have fitted many a blade type mist eliminator to so-called wet 'scrubbers' to prevent carry-over and attack ... but your temperatures preclude using my old favourite, PVC!

It's not fair to any fan, irrespective of material of construction, to allow materials to attack it ... which then get wafted into the atmosphere!

Cheers!

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

Have you thought about going to 501 SS? This is a speciality steel made by Carpenter that is used for fuel injector nozzles for Cummins Engine. Very strong and tough. Just a thought.

Chris Kozlik
- Chicago, Illinois, USA
2001