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Turbine shaft material has its own natural frequency, when turbine rotates on such a speed that frequency of shaft become close to its natural frequency, machine causes noise & high vibrations because of resonance due to matching of frequency. Running of Steam "TURBINE" on this speed is avoided & this is called Critical speed. A turbine may have more then one critical speed, which may depend upon number of couplings.
A second critical speed is when the Turbine blade tips approach the speed of sound. This effectively limits the speed of a turbine and explains why power plants tend to have turbines of the same capacity.
Critical speed of the turbine is the rotor speed at which natural frequency of the assembled rotor (rotor shaft with discs, blades, shrouding strips etc in assembled condition) becomes equal to the operating speed. This is usually a expressed as a range (critical speed range).
There are multiple critical speeds. However, the operating speed of the turbine may be above or below the first / lowest critical speed. Accordingly it is called as a flexible or a rigid rotor.
Venkatesh
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∙ 13y ago
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What steps needs for start a steam turbine from cold conditon?
steam turbine cold start up list:
When was Robert Turbin born?
Robert Turbin was born on 1989-12-02.
How tall is Robert Turbin?
NFL player Robert Turbin is 5'-10''.
What NFL team does Robert Turbin play for?
Robert Turbin plays for the Seattle Seahawks.
Why steam enter at bottom and exit at top in gland of steam turbin rotor?
Gland steam always send from bottom because if we send the gland steam from top then it has a tendency to pass directly to the bottom (condenser) .Due to this reason gland steam is send from bottom so that it occupies total turbine inside vacuum space and seal it.
What is Robert Turbin's number on the Seattle Seahawks?
Robert Turbin is number 22 on the Seattle Seahawks.
What position does Robert Turbin play?
Robert Turbin plays Running Back for the Seattle Seahawks.
Why steam turbine neends gear box?
Steam turbin memerlukan gear box sebagai penyalur tenaga putaran yang dihasilkan oleh turbin. Gear box itu harus berfungsi sebagai reducer gear yang melakukan reduksi terhadap putaran turbin sesuai dengan kebutuhan putaran yang dihasilkan. Misal dari high to low atau low to high. Dalam hal ini kebutuhan dan kapasitas serta aspek-aspek yang lain juga harus diperhitungkan jangan sampai terjadi over load yang akan mengakibatkan kerusakan fatal atau kekurangan tenaga untuk melakukan putaran sehingga tidak maksimal yang berakibat pada pemborosan energi. Steam turbin memiliki putaran yang sangat tinggi dan membutuhkan coupling sebagai penghubung dengan gear box. Menurut saya yang terbaik adalah fluid coupling, dimana pada saat awal steam turbin berputar, tidak akan melakukan hentakan atau sentakan secara mendadak terhadap shaft gear yang dapat mengakibatkan kerusakan pada shaft gear seperti melintir, patah/putus. Tetapi percepatannya bertambah secara bertahap sehingga memiliki kecepatan yang sama dengan steam turbin.
How high can steam pressure achieve?
Steam pressure can be raised as high as the rating of the steam generator. Some super-critical steam generators actually operate at over 15,000 psi. Critical pressure/temperature for steam is 3206 psia, and 705^F. This is the point at which steam and water are indistinguishable from one another. All critical and super-critical steam generators require forced flow, (the water/steam is pumped through the generator). The temperature or the pressure can be raised above critical values, with the use of specialized equipment. Generally speaking, non-forced flow boilers can only achieve about 1500 psia, as the density of the steam approaches the density of the water, preventing natural circulation.
How much does NFL player Robert Turbin weigh?
NFL player Robert Turbin weighs 222 pounds.
How old is Robert Turbin?
As of the end of the 2013-2014 NFL season Robert Turbin is 24 years old.
What college did NFL player Robert Turbin play for?
NFL player Robert Turbin played for Utah State.
