الموضوع: Air Ejectors (2 of 3)
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قديم 03-27-2011, 05:14 PM
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تاريخ التسجيل: Aug 2010
الدولة: Egypt
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Lightbulb Air Ejectors (2 of 3)


Air Ejectors (2 of 3)
-An air ejector or steam ejector is a device which uses the moti** of moving fluid (Motive Fluid) to transport another fluid (Sucti** fluid). It is has a wide range of applicati** in steam ejector in boiler c**denser, fresh water generator and in priming the centrifugal pump.
-It works ** the principle of c**vergent /divergent nozzle as it provides the venturi effect at the point of diffusi** as the tube gets narrows at the throat the velocity of the fluid increases and because of the venturi affect it pressure decreases, vacuum will occur in the diffuser throat where the sucti** line will be provided.




-The operating medium of an air ejector can be either high-pressure gas or liquid. This is passed through a nozzle and the pressure energy is c**verted into velocity energy. The high-velocity fluid aspirates the air and the n**-c**densable gases and the mixture is projected into a diffuser which rec**verts the velocity energy into pressure energy.






-Steam is suitable operating medium and is used in the steam-jet air ejector. The steam c**sumpti** is c**trolled by the compressi** ratio of the air and this factor influences the decisi** to adopt either single or multiple stage ejectors for a particular c**diti**.
-To meet the requirements when raising vacuum a starting ejector is provided. This is high capacity, high steam c**sumpti** ejector, of single stage and without an after c**denser.
-A main air ejector with standby unit is usually provided for normal operati**. The heat in the operating steam is partially recovered in the c**densate which flows through the inter and after coolers.



-If an installati** is to operate with a direct cooling system, as is provided by the sea or a river, vacuum as high as 29.2 in.Hg would be expected during the winter m**ths.
-A cooling tower installati** will operate at a slightly poorer vacuum than a direct cooled stati** and this vacuum can usually be handled by a two-stage ejector.




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