1.  PURPOSE OF LUB OIL SYSTEM In the 250 MW KWU turbines :  Single oil is used for  A] Lubrication Of All Bearings,  B] Control Oil For Governing System and  c] Hydraulic Turbine Turning Gear

2.  Recommended brands of oil : a) IOC – Servo Prime 46 b) HPCL – Turbinol 46  The turbine oil which is used in lubricating as well as governing system shall not contain additives having any negative effect on the materials of the oil system. The turbine oil must be capable of withstanding bearing temperature of max.130 0 C and oil tank temperature of max.80 0 C without physical and chemical degradation. The properties of the oil shall not be affected by centrifuging, water washing or filtering.

3. The oil necessary for operation is stored in the MOT. The oil pumps draw the turbine oil from the MOT and forward it to where it is needed. Large solid contaminants in the returning oil are removed by the strainers in the MOT before the oil reaches the suction section of the MOT. Air and oil vapour are drawn out of the MOT by the oil vapour extractor. MOT is kept air tight always. The MOT level is monitored. The turbine oil can be drained from the MOT. Technical Data of MOT : Nominal capacity of the MOT:25 m 3 (Normal operating level/ 40 m3( max capacity) Maximum temperature of oil during operation – 47 0 C Minimum temperature of oil during operation – 38 0 C

4. Side stream filtration by Oil Purifier  From MOT, a portion of the oil from a tapping point just above the drain port, is fed to Centrifuge, where it is heated to desired temp (65-70 0 c) and then purified from Moisture and Debris. Cleaned oil returns to the MOT. :  Type : Centrifugal  Treating capacity: 6000 Liter/hr  Maximum Discharge Pr: 5 kg/cm 2  Heater capacity: 30 KW

5. Auxiliary Oil Pump (AOP):- This pump (capacity 280 m3/hr ) is stared for initial lubrication of TG bearings and generation of control oil during starting of the turbine. Motor is of 110 KW. Takes AUTO START if DG in operation, or control pressure 8 Kg/cm2 and turbine speed > 2950 rpm. Manual START / STOP possible. Main Oil Pump The MOP having capacity of 400 m3/hr is coupled with the turbine rotor & is designed to produce sufficient oil pressure after the rotor is rotated to a certain value.

6. Emergency Oil Pump (EOP), AC :-  This is functional for emergency supply of lubrication oil to all the bearings.  AUTO START if the lub oil press < 1.1 Kg/cm2 or AOP trips. Stop is by manual only. Manual start possible. Emergency Oil Pump (EOP), DC:-  This is functional for emergency supply of lubrication oil to all the bearings in case AC power is not available in case of major power failure.  Both pump discharge head 1.5 Kg/cm2 and fitted with a motor of 5.5 KW.  AUTO START if the lub oil press <.7 Kg/cm2 or ACLOP/AOP trips. Stop is by manual only. Manual start possible.

7. Injector Feeder Pump :  There are 2(two) Injector Feeder pumps located inside the MOT and on the upstream of the Main Oil Pump(MOP). The injectors are submersible pumps which draw the turbine oil directly from the MOT and forward it to the MOP under positive pressure. The injectors ensure a positive pressure of approx.0.2 bar at the suction of the MOP at all operating conditions.

8. Oil vapour Extraction System :  Oil vapors inside MOT as well as in the oil return lines are regularly forming due to turbulent flow of turbine oil in the bearing pedestals and due to release of entrained air in the oil return lines as well as MOT.  These are removed by one of the two oil vapour extractors. Volumetric flow in the oil vapour extraction lines is adjusted with throttle valves so that negative pressures in the bearing pedestals equal the reference value of approx 5 to 10 mm of water column  The negative pressures above the oil surface in the bearing pedestals, oil return lines, MOT etc. prevent turbine oil or vapour from escaping into the atmosphere.  Turbine oil and oil vapour are separated in the oil separator of the oil vapour extractors so that the air released into the atmosphere is almost free of oil.

9. Lub Oil filter (Qty: 2) Type: Duplex,Size (JPI 150LB, flanged), Filtration : 20 micron. There is one Duplex lubricating oil filter provided in the system to protect the turbine and generator bearings against solid contaminants. One element of the switchable oil filter is always in operation. The differential pressure across the lubricating oil filter in operation is a measure of filter clogging. The double multiport butterfly valve is the changeover valve for the lubricating oil filters. Lub Oil Cooler: (Qty: 2) Butterfly valve is the changeover valve for the oil coolers. Type : Shell & Tube (Vertical type) Cooling surface : 195 m 2; Cooling water temperature : 36 o C Cooling water flow : 200 m 3 /hr. There are 2 (two) oil coolers in the system but one oil cooler is always in operation. The second oil cooler is on stand-by. Change-over to the stand-by oil cooler must be made when the oil cooler in operation clogs or leaks. The maximum flow rate of the cooling water through the oil cooler in operation must be maintained for good heat transfer and preventing deposits in the cooler tubes.

10. Operation-  If TG is stand still & all start permissive are available, start auxiliary oil pump for supplying oil to Bearing.  Once steam rolling starts, it supplies the control oil for Governing system. Once the turbine speed crosses 90% of rated speed, the main oil pump (MOP) takes over. It draws oil from main oil tank.  The lubricating oil passes through oil cooler (2 nos.) and oil Filter before can be supplied to the bearing. Under emergency, a DC oil pump can supply lubricating oil.  Before the turbine is turned on barring gear, the Jacking Oil Pump (2 nos.) supplies high-pressure oil to jack-up the TG shaft to prevent boundary lubrication in bearing.

11. Lubricating oil throttle valve :  These valves are located in the upstream of turbine and generator bearings. The oil pressure before the bearings is about 1 ata. The bearing-specific oil flow rates are set with the throttle valves in the lubricating oil lines upstream of the turbine and generator bearings.

12.  PURPOSE: During shutdown of the rotor system or at low turbine generator speed, a hydrostatic lubricating film is built-up between every shaft journal and bearing. This film protects against metal-to-metal contact between the bearing and shaft journal and reduces friction until a hydrodynamic lubricating film builds up at higher circumferential velocity of the shaft journal.  There are Jacking oil pumps (2x100%) – one AC and the other is DC driven. The discharge pressure of JOP is about 150 bar. The JOPs are positive displacement pumps which must be protected against excessive pump discharge pressure if delivery approaches to zero. The excess oil is returned to MOT through safety valves located in downstream of JOPs.

13.  Jacking Oil Pump (JOP), AC:- Jacking oil is used when then the turbine is on turning gear for lifting the rotor by this oil press, So that rotor floats on this high press oil. The normal discharge press is 150 Kg/cm2. AUTO START at turbine speed 500 rpm. Manual START/STOP also possible.  Jacking Oil Pump (JOP), DC:- The pump is the same type as stated above but DC driven. AUTO START if ac driven JOP trips or ac power failure of JOP (ac) or Jacking oil press < 150 Kg/cm2 and turbine speed < 400 rpm. Manual START/STOP also possible.  Both are Vertical plunger type, capacity 5.6m 3 /hr with a discharge head of 160 Kg/cm 2. Motor rating: 37KW.

14. Operation of JOP:  The jacking oil pumps are switched on or off by the respective sub-loop controls (SLC) which must be in AUTO mode. The starting of jacking oil pump -1 depends on turbine-generator speed. It is switched on automatically when turbine-generator speed is less than 120 rpm. Jacking oil pump -2 will be switched on automatically when the operating pressure of the system drops below the pre-set limit during operation of jacking oil pump -1 or there is a AC failure. Parallel operation of the jacking oil pumps is inadmissible.

15.  The differential pressure on the jacking oil filter in operation is a measure of the filter clogging. The Double Multiport Butterfly valve is used for switching between jacking oil filter elements.  The oil pressure in the jacking oil system is regulated and held constant with the overflow valve. The oil pressure necessary for jacking oil system operation can be adjusted by changing the spring load of the overflow valve.  The oil pressure in jacking oil system can be adjusted or relieved completely using the relief valve of the overflow valve. The bearing-specific jacking oil pressures are set using the throttle valves in the jacking oil lines upstream of the bearings. Jacking oil is supplied to small bearings through one jacking oil line and to large bearings through two separate jacking oil lines.

16.  Turning oil supply valve :- For slow speed rolling of turbine, here oil pressure is used to pressurize the turning gear. The oil supplied is taken from the AOP discharge press & fed to turning gear through a valve (on/off type), named turning oil supply valve.

17. TURNING GEAR INTERLOCK AUTO CLOSE by turbine speed > 400 rpm. Manual START/STOP also possible.

18. Starting Of Turbine Lub Oil System & Turning Gear  Start one oil tank vapour extractor and put other in AUTO.  Start AOP, Check discharge pr > 6.5 Kg/cm 2, Oil temp at cooler outlet >35 o C  Select Auto of AC EOP and DC EOP  Start AC Jacking oil pump. Select Auto of DC JOP  Initially rotate turbine manually by hand barring.  Establish Seal Oil Pressure as needed.  Open turning oil supply v/v and put into Auto, Check turbine speed >60 RPM  Select Auto of AOP Stopping of Turbine Lub Oil System & Turning Gear  Check the HP turbine casing metal 50% temperature < 150°C  Check Bearing metal temperature < 90 or 100 or 105°C  Close turning oil supply valve  Measure race time to stopping the rotor. Check JOP running.  Check the rotor stops perfectly  If bearing metal temperature rises to 90, 100 or 105°C, then start AOP to supply lubricating oil again to the bearings.