Q & A > Question Details
What is the difference between the Eductor and Ejectors?
03/12/2009 A: Vishnu Ram A S, RIL, vishnu.selvaraj@ril.com
Yes, Mr.G.S.Singh. This is the answer I wrote for Answers.com, FYI.
02/12/2009 A: GS Singh, NPCC, gssingh2003@yahoo.co.in
The ejectors are used to maintain a system vacuum in the upstream (Example maintaining the vacuum column pressure) whereas eductor's main objective is to take out the volume of any fluid out of the system by maintaining a system pressure in the upstream.
1. The eductors are used to remove the air 4 times the volume of the vessel per hour for the vessel entry jobs. We use compressed air as a motive fluid.
2. The water jet eductors are used to suck the muddy water, or a oily water from the storm water channel or a pit (an alternative for a de-watering pump). Here the motive fluid is high pressure water.
Hence the Eductors can be used to transfer a considerable volume of fluid from low pressure to high pressure with high compression ratio than ejectors. whereas the ejectors just suck the excess volume of the system and maintains the system pressure accurately.
The difference is with respect to their function and not with respect with their motive fluid. The diameter of the ejector's throat is lesser than the eductor.
30/11/2009 A: Alan Goelzer, Jacobs Consultancy, alan.goelzer@jacobs.com
Personally within the context of petroleum refining and non-conventional oil upgrading, I use the term Eductor when the principal function of a given stage within one-to-five stage steam jet ejector system becomes 'compression of vapours or gases'.
I use the term Ejector when the principal function of one or more given stages within a steam jet ejector system is 'creation of vacuum'.
For example, within a deep cut vacuum distillation tower, the vacuum diesel pumparound zone at the top is not able to fully capture enough of the lower boiling components [kerosene and heavy diesel gas oil] and thus the first stages of a four or five stage Vacuum System is really an Eductor compressing the as yet uncaptured condensible vapours and 'non-condensibles' and 'process steam' to a sufficient absolute pressure where these can be condensed via a 'surface condenser' [using cooling water]. The remaining four stages might involve two steam jet ejectors and two liquid ring vacuum pumps.
In any case, the vapours and steam going to the Vacuum System should be carefully modeled using 'vetted' computer simulation models and the eductor or ejector purchased from technically qualified 'technology suppliers'.