Steam ejector design 2

[formz]

Good afternoon,

I am now trying to calculate a steam ejector for vacuum production.

Does anyone have some suggestions about where (how) to start or a spreadsheet already done for an application like this?

Thank you very much in advance.

 

[rmw]

Yeah, call your local Graham representative or go to

http://www.graham-mfg.com

and ask for a copy of their software "vacworks." That program will figure it as close as you ever could by starting from scratch which I would never set out to do on my own.

rmw

 

[KenA]

Alternative vendors inlude Korting (

http://www.northvalekorting.co.uk/products-fluidjet.asp)

and Transvac (

http://www.transvac.co.uk/)

amongst others.

 

[dogtop]

Birgenheier, David B. et al, "Designing Steam-Jet Vacuum Systems," Chemical Engineering, July 1993.

Heat Exchange Institute, Inc., "Standards for Steam Jet Vacuum Systems," October 2000. Heat Exchange Institute Inc,, 1300 Sumner Avenue, Cleveland, OH 44115-2851

HTH

 

[insult2injury]

Birgenheier paper:

http://www.graham-mfg.com/downloads/23.pdf

I2I

 

[katmar]

I agree with rmw that it is best to get a specialist to make it. There is a lot of empirical knowledge that goes into the design and manufacture. But for initial estimates there is a graphical design procedure in Perry. Probably won't lend itself to spreadsheeting though.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[formz]

Thank you very much for your answers.

 

[PISA]

Formz,

also GEA have published curves and charts for a rough sizing:

http://www.niro.com/nuk/cmsresources.nsf/filenames/dvp1.pdf/$file/dvp1.pdf

and more manufacturers are listed in vacuum-guide:

http://www.vacuum-guide.com/vacuum_pump/vacuum_ejector/vacuum_ejector_america.htm

Hope it helps,

Anne

 

[formz]

All of the data you've sent me is being useful.

But I'm still curious about one thing: everything I see in my searches is empirical or semi-empirical.

Does anyone know exactly (sizing equations) what's "behind" a jet pump?

For me, conceptually talking, everything makes sense (Venturi effect).

Mathematically the things don't seem to be very clear for anyone...

Nice weekend for all of you!

 

[rmw]

There is a lot of an emperical component to vacuum jet design and manufacturing. Speaking for my experience with at least one of them, they calculate a design and then make one and test it. If it works as designed, then they produce curves and that becomes the performance standard for that particular design. Change something and they have to do the process all over again.

Over the years they have done enough tests that they can exptrapolate from those that they have tested so they rarely have to verify by testing these days, but they have the labs and test stands to do so if needs be.

rmw

 

[djack77494]

It's not something you want to try to do from first principles.

 

[katmar]

This list of references was sent to me by Matija Gregorka. I have not checked them myself.

1. Hans Peter Schlag
Experimentelle und theoretische Untersuchungen zur Berechnung der Kennlinien von gasbetriebenen Einphaseninjektoren und Gutaufgabe Injektoren
VDI Verlag 1993
Reihe 3: Verfahrenstechnik Nr 313

2 Uwe Wagenknecht
Untersuchun der Stroemungsverhaeltnisse und des Druckverlaufes in Gas/Feststoff-Injektoren
Dissertation
UB/TIB Hannover 105 585 165

3.Werner Hutt
Untersuchun der Stroemungsvorgaenge und Ermittlung von Kennlinien an Gutaufgabe Injektoren zur pneumatischen Foerderung
Dissertation Universitaet Stuttgart RA 4212(84) 1983
UB/TIB Hannover 118 842 161

4. Th. Messing
Dampfstrahlverdichter als Waermepumpen
Chem-Ing.-Techn 30 Jahrg. 1958 Nr9 p 589-592
5. Oak Ridge national laboratory
Martin Marietta Energy Systems Inc
C.T.Hsu
Investigation of an Ejector Heat Pump by Analytical Methods
ORNL/con 144 Dist Category UC 95-d 1984

5. VDI Forschungsheft 479 Ausgabe B Band 26 1960
R.Jung
Die Berechnung und Anwendung der Strahlgeblaese

This source has been translated to English

6. A K Jeelani, A Rajkumar, K V Kasipathi Rao
Designing Air Jet Ejectors
Chemical engineering september 25 1976 p135

6. S A K Jeelani,K V Kasipathi Rao, G R Balasubramanian
Designing Steam Jet Ejectors
Chemical engineering April 9 1979

7. H J Henzler
Das Sogverhalten von Strahlsaugern fuer das Stoffsystem fluessig-gasfoermig
Verfahrenstechnik 15 (1981) Nr10 p 738-749

 

[Imak]

Is anyone know if it is possible for steam to back up from discharge backwards. For example, if someone shuts valve downstream.

Thanks

I_mak

 

[ash9144]

Absolutely. If discharge side of ejector is blocked in and steam is not the steam is going to path of least resistance, back to process.

You can also get wet steam into an ejector and this will cause "back firing" on the ejector also putting material back into process.

 

[Imak]

Thank you ash9144 !

I_mak

 

[rmw]

The same can happen with severely plugged inter or after condensers, or direct contact condensers with cooling water temperatures way too high.

If the steam can't leave the jet at the design velocities, it ceases to be a jet and just becomes a dumb piece of pipe. Imak has stated well what happens to steam flowing in pipes.

rmw