What is the Wheel Chamber in a Steam Turbine? What is its purpose?
Answers
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15/06/2013
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A:
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Dhiren Rindani, Reliance Industries Ltd, dhiren.rindani@ril.com
All the rotors of pumps, compressors and turbines experience the axial thrust due to diffrential pressure between suction /discharge or inlet /oulet.
For small machines a thrust bearing, balancing disk are installed on the rotor to absorb axial loading. for large machines a device called balancing piston is keyed/shrunk to the rotorat at high pressure rotor end.
This balance piston is exposed to high pressure on one side and discharge pressure/low pressure on other side. The rotor thrust is balanced based on the area provided on either side of balance piston. (dynemic Pressure x Area)= force which acts on HP/LP side of the balance piston keeps the rotor in position and absorbs major portion of axial thrust. Residual axial loading is absorbed by thrust bearing.
Wheel chamber in case of steam turbine is a chamber provided on HP side of balance piston. It is between fisrt stage( Impilse stage ) nozzle and balance piston. For the same load on the turbine, if wheel chamber pressure increases it indicates turbine fouling.
Based on wheel chamber pressure and turbine loading, it is possible to judge turbine fouling, turbine rotor/stator sealing condition, balance piston sealing condition etc..
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