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What the function of air ejector in steam turbine? |
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about steam ejector system in turbine
A steam ejector is a pump-like device, with no moving parts or pistons, that utilizes high-pressure steam to compress vapours or gases. This creates a vacuum in any vessel or chamber connected to the suction inlet of the ejector
The adjacent diagram depicts a typical modern ejector. It consists of a motive fluid inlet nozzle and a converging-diverging outlet nozzle. In this case of a steam ejector, the motive fluid is high-pressure steam.
The Venturi effect, a particular case of Bernoulli's principle, applies to the operation of this device. The high-pressure steam is converted into a high-velocity jet at the throat of the convergent-divergent nozzle which creates a low pressure at that point. The low pressure draws the suction fluid (a vapour or gas in this case) into the convergent-divergent nozzle where it mixes with the high-pressure steam.
In essence, the pressure energy of the inlet steam is converted to kinetic energy in the form of velocity head at the throat of the convergent-divergent nozzle. As the mixed fluid then expands in the divergent diffuser, the kinetic energy is converted back to pressure energy at the diffuser outlet in accordance with Bernoulli's principle.
The compression ratio of the steam jet ejector, P2/P1, is defined as ratio of the ejector's outlet pressure, P2, to the inlet pressure of the suction vapour or gas, P1.
The entrainment ratio of the steam jet ejector, Ws/Wv, is defined as the amount of motive steam, Ws (in kg/hr), required to entrain and compress a given amount, Wv (in kg/hr), of suction vapour or gas.
The compression ratio and the entrainment ratio are key parameters in designing a steam jet ejector.
Multi-stage ejector sets
In practice, for suction pressure below 100 mbar absolute, more than one ejector will be used, usually with condensors between the ejector stages. Condensing of motive steam greatly improves ejector set efficiency. Both barometric and shell-and-tube surface condensers are used for this purpose.
BY M.D.V.PRASAD
mdvprasad007@gmail.com
First answer by ID3705733650. Last edit by ID3705733650. Question popularity: 15 [recommend question]
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