An ejector has two inlets. One to admit steam, and the other to admit the gas/vapor mixture to be evacuated. Motive steam, at high pressure and low velocity, enters the inlet 1 and exits the steam nozzle at design suction pressure and supersonic velocity, entraining the vapor to be evacuated into the suction chamber through inlet 2. The nozzle throat diameter controls the amount of steam to pass through the nozzle at a given pressure and temperature.
Then, in the diverging section of the diffuser, the velocity of the mixture is sub-sonic and the increasing cross sectional area increases the pressure but further decreases the velocity. The net result of these energy transformations is an increase of the absolute pressure of the mixture on discharge to several times the pressure at which it entered the ejector inlet. The choice of the ejector system will primarily depend on the final vacuum to be achieved. The presence and, indeed, the amount of condensables in the gas stream will influence the choice of system, as will the operating costs and capital available.
These are available in single & double stage and are oil sealed, rotary vane type positive displacement pumps where, not only complete assembly is immersed in oil but shaft seal is also designed in such a way that it totally eliminates the possibility of suction of air through it. These are designed to achieve maximum vacuum in a very short time and rise in temperature of the unit also remains under check, which in turn reduces the wear and tear of its components and makes it suitable for noiseless and trouble free performance for years and thus helps in reduction of repair bills.
These are normal compressors. The vacuum line is connected to the inlet of compressor (instead of air filter) and discharge is left to atmosphere. The vacuum produced is lower in this case (10 mm Hg). It can be used where the air contains water vapor (which will dilute oil in case of vacuum pump). It is inexpensive as compared to vacuum pump, for operation.
3D Piping Models
Agitator / Mixer
Design & Drawings
Agitator / Mixer
Zero Hold up Filter
Cross Country Piping