6 replies to this topic

[Aditvad]

Friends,
i want to calculate the motive fluid requirement for a given entrained gas load. Please help me.

[Art Montemayor]

There is no calculation that I know of for the required motive fluid flow rate and pressure. The manufacturer of any venturi jet ejector is the indicated source of this information and you obtain that when you submit your Data sheet to them.

This type of information is usually proprietary because it is linked to the design and type of ejector supplied.

[breizh]

As stated :

This type of information is usually proprietary because it is linked to the design and type of ejector supplied.

I've attached an example to support.

Breizh

[katmar]

The problem with doing a standard energy and momentum balance for an ejector is that there are efficiency factors involved that can only be known by experiment. So even if you can do the theoretical balance (which is no trivial task) it will not tell you how your particular ejector will work. The efficiency factors vary from design to design and as the replies above indicate you have to rely on the particular manufacturer knowing the efficiencies for their own designs.

The best resource I know of for estimating the performance of ejectors is the one in Perry. This is page 10-57 in the 7th edition, but it has been in Perry at least since the 4th Ed.

[ankur2061]

Harvey,

The "Heat Exchange Institute" (HEI) publishes a standard for "Steam Jet Vacuum Systems" which has a chapter devoted on performance test standards. Refer the links below:

http://www.heatexcha...pub/default.htm

http://www.heatexcha...cuum System.pdf

The link provided for an Iranian standard provides a figure for motive stam consumption per kg of air or non-condensable load to the ejector, which I thinks is a modified version of what I have seen in Ernest Ludwig's book "Applied Process Design for Chemical and Petrochemical Plants".

http://igs.nigc.ir/I...PS/e-pr-745.pdf

Regards,
Ankur.

[isbarqi]

see book: Ludwig - Applied Process Design For Chemical And Petrochemical Plants_ Volume 1 chapter 6.
Very complete reference for ejector and vacuum system

[MAGICAL_RUPI]

A good estimate can be made from curves provided by R,B power. Generally, they are really very close to manufacturers figure.