Vacuum ejector1/8/2024 ![]() Using a cooling tower to receive HRSG blowdown is another method to be considered. Providing vacuum pumps should be evaluated. This is not necessarily effective over a wide range of part-load operations. Read more Navigate DownĮstablishing and maintaining vacuum in the condenser is usually done with staged SJAEs (one set for hogging one set for steady state operation). High power fluid usage is associated with efficiencies as high as 70%. Low power-fluid usage is associated with efficiencies as low as 30%. Oddly, the more power fluid you use, the higher the overall efficiency of the unit will be. Except in very specific cases, greater than three compression ratios require uneconomic quantities of power fluid. The exhaust pressure for an ejector can be as much as 10 times suction pressure, but there is a strong relationship between compression ratios and mass-flow rate of power fluid-more ratios requires significantly more power fluid. ![]() The exhaust pressure for an eductor is limited to about 1.5–3 times the suction pressure (in absolute units). The combined stream is left at an intermediate pressure. In both cases the high pressure/high velocity power fluid entrains the suction fluid at the no-flow boundary between the two fluids, which causes energy to transfer from the power fluid to the suction fluid. Simpson P.E., in Practical Onshore Gas Field Engineering, 2017 8.4.1 Eductor vs ejectorīoth eductors and ejectors are in the family of equipment that includes air ejectors, evacuators, sand blasters, certain kinds of paint sprayers, hose-end sprayers, and jet pumps. ![]() The nozzle is usually made of stainless steel while the extraction chamber and diffuser are of steel castings or steel plates however, the material may differ according to the condition of the steam handled. The diffuser raises the entrained air pressure. High-velocity steam jets from the nozzle entrain the air. The second-stage ejector extracts air with a small amount of saturated steam and discharges it into the atmosphere. The cooler is divided into the intercooler and the aftercooler, which are mounted on the outlets of two stages of the ejector, respectively. This air ejector is designed to extract saturated steam and air from the condenser about 2.3 times the volume of air. The two-stage, twin-element air ejector can extract a specified amount of dry air with its single element and maintain a very high vacuum on the order of 735 mmHg. The volumes of the individual nozzles add up to form a total suction rate.Swapan Basu, Ajay Kumar Debnath, in Power Plant Instrumentation and Control Handbook (Second Edition), 2019 3.5.6.4 Performance With ejectors featuring eco-nozzle technology, the vacuum passes through several venturi nozzles arranged in a row. ![]() The aspirated air and the compressed air escape through the silencer (C). Air is drawn in this way through the vacuum connection (D). After passing through the nozzle, the accelerated air slows down once again and a vacuum is created. The air is accelerated and compressed during this process. The compressed air is supplied through connection (A) to ejectors. Ejectors work on the Venturi principle they are divided into singlestage ejectors and ejectors featuring eco-nozzle technology.
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