A further jet ejector stage compresses the suction flow components of the first surface condenser which cant be condensed to atmospheric pressure. The inter stage condensers economise on the use of motive steam as the operating steam from the upstream stage of the system is condensed leaving only the saturated non condensable gas to be handled by the next stage.
The diagram illustrates typical vacuum levels that can be achieved economically for a specific number of stages.
You can find out more Diagram below
3 stage ejector vacuum system proces flow diagram. They are used with or without precondensers. The motive steam of the upstream jet ejector is condensed in the downstream surface condenser. Flow chart of a multi stage steam jet vacuum system with surface condenser.
Rough to medium vacuum 1013 to 10 3 mbar compression from momentum transfer. Different tower operating pressures and overhead load characteristics of wet damp or dry operation affect only the configuration of an ejector system but the basic operating principle remains unchanged. Multi stage ejector systems are used to evacuate and maintain the vacuum in many industrial processes degassing desalination deodourising an more.
Thermocompressors recompression boosters are single stage ejectors designed to boost low pressure steam to a high pressure and temperature. The ejectors which are distinguished from other types of compressors as having no moving parts work on the ejector venturi principle of converting the pressure energy of a motivating fluid to velocity energy in order to entrain the suction fluid. Ejector systems have been the mainstay for refinery vacuum distillation.
Ejectors are available in either single nozzle or multiple nozzle designs. Whether a crude vacuum tower operates as a wet damp or dry tower an ejector system is the vacuum producer. Lvi also offers water gas and air operated ejectors for a wide variety of applications.
These are the most simple systems producing vacuum from just a few inches of water draft to approximately 50 torr. Single nozzle units are also available with an automatic spindle for special applications. Transvac design and manufacture a comprehensive range of steam jet ejectors from coarse vacuum single stage units.
Multi stage steam ejectors enable lower suction pressures to be achieved than can be produced by a single stage unit. Such as rapid evacuation ejectors hoggers up to 5 stage steam jet ejector systems fully packaged to produce vacuum levels of up to 25 microns hg abs. Energy terms to use multi stage ejectors this requires the use of intercondensers to remove the operating steam so that only the incondensable gases pass to the second stage reducing the amount of steam required.
Ejector systems range from the simple single ejector stage to very complex systems with as many as six ejectors in combination with intercondensers. Vacuum is created air or gas is entrained and mixture. Two stage vacuum ejectors generally cover vacuum ranges between 3mm hga to 130mm hga however depending up on actual operating conditions a single stage may be more economical if at the upper limit of the operational envelope or a three stage ejector system if conditions are at the lower end.
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