ejector design

[farahnaz77]

I have never had an experience in ejector designing but I need it now. we are going to provide an ejector to drain a water sump with 4.5 m height to atmosphere .because of some resons we can not use a submerged pump. So, suction inlet feed is saturated air or water? Which consideration should be taken ? what parameter should be calculated ? we have steam at 150 deg. C, 60 psia. Could anyone help me with it?
thanks

 

[25362]

Steam ejectors acting as jet pumps for lifting and delivering liquids are sometimes called siphons(!?) or injectors, depending on their discharge pressure. For details see the Pump Handbook by Igor J. Karassik et al., McGraw-Hill. Googleing around you may find design details of steam ejectors for the job in hand.

 

[Montemayor]

farahnaz77:

I've only heard of two instances where an engineer took to designing and building his own ejector. Both ended in failure. This is understandable, since a lot of the technology is locked up by the existing manufacturers who have spent a lot of time and money in developing their designs.

With proven designs available, why would you feel pressed to design, test, modify, and install your own personal design? Are you limited in being able to buy an existing, proven & warranted design?

What you are proposing is not the conventional case since you yourself admit you know little or nothing of designing such a unit. It is obvious that someone (you or your supervisors) will have to take the risk and gamble of seeing to it that your design works as per specified needs. This is not done in conventional engineering circles. Professional and experienced suppliers are called upon to furnish proven and warranted products.

I have done what you propose by buying a catalog listed unit from Penberthy. Depending on the capacity, it should be very low cost. I hope this experience helps.


Art Montemayor
Spring, TX

 

[steveen]

I have used small steam eductors just for this purpose. To drain water out of a sulfuric acid tankfarm sump. They worked well, were available from vendors such as Granger.
However, consider the cost of the steam to move the liquid.

If you are moving a large volume of water, I suggest you consider consider a siphon to lift the water to a location where you can use a submersible pump. Again, you offer no flowrate, so energy consumption may or may not be an issue.

 

[m777182]

Designing air jet ejectors: Chem Eng, Sept 25, 1978, p135-136;Designing steam jet ejectors: Chem Eng April 9, 1979 p 135-136;Zur Auslegung von Strahlsaugern fuer einphasige Stoffsysteme:Chem Ing Techn 54(1982)Nr 1, S 8-16;VDI Forschungsheft 479,Ausgabe B Band 26 (1960): Die Berechnungund Anwendung der Strahgeblaese.
Item 1 and 2 in form of nomographs.Cool and easy.
M777182

 

[Torricelli]

I agree with A. Montemayor,
std. ejectors (made of cast iron) are very unexpensive,
save your time: start with

http://www.vacuum-guide.com

 

[farahnaz77]

Thanks all;
Sorry, I think there is a misunderstanding, maybe I have not conveyed it. I meant what “steveen” and “25362“ have written, too. I want to determine the characteristic of the ejector and complete data sheet not design and build it.
Required flow rate is about 4-5 m3/hr to drain water.

 

[jalvarez]

So, you simply need a specification sheet to fill in.
Any supplier can provide you with one, but normally they use their own requirements, so you may send these sheets to them and not to others, which is a problem if you are looking for some competition.
If you need a general spec for ejectors, I can send you one, tell me where. I discover that Yahoo don't permit free access to "public" archives anymore. If someone know how to post these archives, our communications would be easier.
Have a safe day
J.Alvarez

 

[steveen]

faranaz77,

Reconsider using a siphon system and submersible pump. At least run through a power consumption calculation.... Include your heating loss for the steam piping to get to your location...

Give me a call on Tuesday 713-204-3615 if you need some help with either the steam eductor or the power calculation. I am in Houston, Texas... Be mindful of the time.
Steve

 

[Homayun]

Dear Farahnaz77,

GEA-Wiegand is a german manufacturer of these type of equipment. On their site they have brouchours available where all your questions are answerd.

Visit

http://www.GEAJET.Com

and then go to Jet Pumps e-catalogue and choose Jet Pumps. There you'll find a write up about to calculate a jet pump and specify the parameters.
Regards,
Homayun

 

[farahnaz77]

thanks Steveen.