TURBINE OILING SYSTEM

1.  OIL SUPPLY

A single oil supply line lubricates and cools the bearing, governs the m/c and operates the hydraulic actuators and safety and protective devices.

During start-up & shut-down, aux oil pump supplies the control oil. Once the turbine speed is more than 2850 rpm, the main oil pump (M.O.P) takes over. It draws oil from main tank .The lubricating oil passes through oil cooler, before can be supplied to the bearing (Under emergency, lube oil can be supplied by a DC oil pump).Before the turbine is turned or barred, Jacking oil pump  (2 nos.) supplies high pressure oil to the jack up the TG shaft to prevent boundary lubrication and also supplies high pressure oil to drive the hydraulic motor(turning gear)

2)Turbine lubricating oil system

•  Function:

          1. Provides a supply of oil to journal bearings to give an oil wedge as the shaft rotates.
          2. Maintains the temperature of turbine bearings constant at the required level.
         3. Provides a medium for hydraulically operating the governor gear and controlling the steam 

             admission valves.               
         4. Provides for hydrogen cooled generators a sealing medium to
             prevent hydrogen leaking out along the shaft.   

3)Main components

     1) Main Oil Pump

     2)Auxiliary Oil Pump

     3) Emergency Oil Pump

     4) Jacking Oil Pump

     5) Main Oil Tank (MOT)

     6) Centrifugal

3.1) Main Oil Pump

•  This pump is located at the front bearing pedestal of the HP turbine.
• It is coupled to the turbine rotor through a gear coupling.
• When the turbine is running at a normal speed of 3000rpm, then the desired quantity of oil to the governing systems and the lubrication systems is supplied by this pump.

3.2)Auxiliary Oil Pump

•  Auxiliary Oil Pump can meet the requirements of lubrication system under emergency conditions

• One stage vertical centrifugal pump driven by an A.C. electric
  motor.
• It has radial impeller and volute casing.
•  The pump automatically takes over under interlock action
  whenever the oil pressure in the lubrication system fails below
  certain desired level. 

3.3) Emergency Oil Pump

•  Emergency oil pump has been foreseen by as a back-up
  protection to AC driven standby oil pump.
•  This is a centrifugal pump, driven by DC electric motor.
•  This automatically cuts in whenever there is a failure of AC
  supply at power station

3.4)Jacking Oil Pump:

•  JOP ensures that there is no metal contact between a journal
  and the bearing.
•  Positive displacement pumps that provide high pressure supply
  of oil under strategic journals of the turbo generator and oil lifts
  the shaft slightly.
•  This greatly reduces the static friction and bearing wear.
• The JOP can be stopped after the lubricating oil film is
  established between the shaft and bearings.
•  Pressure produced is 120 bars

3.5) Main oil tank

•  The oil used for lubrication is stored in the Mai Oil Tank.
•  Capacity -20/32 m3.
•  The Main Oil Tank holds the oil inside the tank for a period long
  enough to ensure liberation of air from the oil.
•  Filters are located inside the tank to filter the oil during its
  normal course.
•  The oil tank is supported on a framed structure just below the
  turbine floor at the left hand side of the turbine.