Generator cooling and sealing system 2

Training report:
Generator Cooling and Sealing
           System




           Mohd Basid Azmi
           B.Tech(Electrical)
Generator Specifications

                                          Rating of Turbo Generator


                          KVA Rating                                                  Coolant:
                           :247MVA                                                    Water And
                                                                                      Hydrogen
   Connection:                                 KW Rating :         Phase
                                                                                                       Gas Pressure:
    Star-Star                                   210MW            Connection:
                                                                                                        3.5 Kg/Cm3
                                                                 Double Star

                                                 Voltage :
   Phases: 3
                                                 15750 V-       Rated Speed:                              Insulation:
RatedFrequency
                                               Stator,310 V -    3000 Rpm                                   Class B
    :50 Hz
                                                   Rotor


                                        Amperes : 9050               Maker & Year:
       Rated Power                                                  BHEL (Haridwar)               Type: Thw-210-2
                                       A- Stator,2600 A -
     Factor : 0.85 Lag                                                 1986-87
                                             Rotor
NEED FOR GENERATOR COOLING SYSTEM



     Large no. of
     conductors


                    • insulation blisters:
                      conductors grow
                      and elongate
                    • generation of
                      large amount of
         high         heat.
       currents
      flowing in
     the windings
Hydrogen Cooling

           Minimize drag - “windage”


         Keep generator internals clean


           Maximize generator output

       Minimize electrical, mechanical and
              corrosion problems

              better heat transfer


          increase breakdown voltage
Rotor cooling system

                            gas flow maintained
                                 by pressure
                            difference between
                            the inlet wedge and
                                outlet wedge



                                                                        Specifications:
     This method gives
    uniform distribution
    of temperature and
                              Gap                 Flow directed along
                                                     the ventilating
                                                                        A) H2 Pressure : 3.5kg/cm2
       eliminates the
       deformation of
                             Pickup               canals made on the
                                                    hot zone of the     B) Purity : 97%
     copper due to high
        temperatures         Cooling                      rotor.
                                                                        C) Gas Volume : 66 m3



                            Hydrogen gas in the
                              air gap is sucked
                            through the scoops
                             on rotor wedges
.
Stator cooling system

•   The stator winding is cooled by distillate,      •   The system is designed to maintain a
    which is fed from one end of the machine by          constant rate of cooling water flow to the
    a Teflon tube and flows through the upper            stator winding at a normal inlet water
    bar and returns back through the lower end           temperature of 40°C.
    of the other slot.

•   The stator winding is cooled by circulating          Specifications:
    the dematerialized water.                            A) Water Pressure : 3.5 kg/cm2
•   DM water used for the cooling of the stator          B) Qty. Of Water :130 m3/Hr
    winding calls for the use of very high quality
    of cooling water. For this purpose DM water
    of specific resistance is selected.
Generator Sealing system

•   Sealings are employed to prevent leakage of hydrogen from the stator at the point
    of rotor exit.

•   The seal oil is a portion of the lube oil, diverted from the lube oil system. It is then
    fed to a separate system of its own with pump, motor, hydrogen detraining or
    vacuum degassing equipment, and controls to regulate the pressure and flow.

•   A continuous film between the rotor collar and seal liner is maintained by the
    means of oil at a pressure, which is about O.5 atm above the casing of hydrogen
    gas pressure.

•   The thrust pad provides a positive maintenance of the oil film thickness.
Generator Seal Oil System
 System functions:

 • supplying the generator shaft with seal oil with hydrogen.

 • permanent monitoring and differential pressure
    regulation of hydrogen and oil,

 • oil seal maintenance
     – air and hydrogen separation,

     – oil filtration,

     – temperature regulation,

 • removing oil vapors and hydrogen from the hall.
Generator Seal Oil System

• This system follows the following path:
 •   Main Oil Tank
 •   Main Oil Pump
 •   Seal Oil Cooler
 •   Seal Oil Filter
 •   Damper Tank
 •   DPR (Differential Pressure Regulator)
 •   Hydrogen Seal
 •   Seal Oil Fans
 •   Main Oil Tank
• This system has two more pumps:
•    AC Seal Oil Pump
•    DC Seal Oil Pump
Generator Seal Oil System

•   The pressure of seal is 4.2kg per sq Cm. while the pressure of hydrogen is 3.5 kg
    per sq. cm. The purpose of this system is to provide seal to the hydrogen used for
    cooling of stator. If the seal breaks, the system also breaks down.

•   MOT(main oil tank):- It contains 28000ltrs of turbine oil. It supplies oil to all
    bearings and seal.

•   MOP(main oil pump):-It takes from the main oil tank and supplies further.

•   Seal oil cooler:- It contains clarified water and distilled mineral water. The outer
    covering area is called   housing. It covers an assembly of about 200 tubes
    assembled on plates. Air gaps are found between the tubes (25mm above, below
    and on each side of each tube).These gaps are filled using hydrogen which cools
    the stator.
Generator Seal Oil System
•   Seal oil filters:- These are rounded mesh like structures kept over each
    other. There are about 34 filters present.

•   Damper tank:-It is kept at 14mtrs of height above the ground. If MOP
    fails A/C or D/C pump works and if these fail then damper pump comes
    into action. Here the hydrogen pressure is .7% to .9% less than the oil
    pressure because if the hydrogen pressure increases, the seal would
    break down.

•   DPR(differential pressure regulator):- The function of DPR is to
    regulate the pressure of the oil and balance it. Whenever main oil
    pump fails, the AC seal oil pumps starts automatically .DC seal pump
    fails but it can supply the oil up to an hour. The generator is kept at a
    height of 8meters so that oil is supplied by pressure.
Generator Seal Oil System
 Sealing Data:

 A) Seal Oil Pressure :4.1 To 4.4 Kg/Cm2

 B) Quantity :80 Lt/Min

 C) Type :Radial Flow, Double Chamber Thrust Type

 AC Seal Oil Pump:

 A) Type :Multistage Vertical Split Centrifugal Type

 B) Capacity : 3.34 Lit/Se At 12kg/Cm2

 DC Seal Oil Pump:

 A) Type : Multistage Vertical Split Centrifugal Type

 B) Capacity : 4.16 Liters At 12 Kg/Cm2
 Line Charge Capacity :75 MVAR
References

•   Kothari, D. P. , Nagrath, I. J. " Electric Machines" (2012)
•   Mehta, Rohit, Mehta, V. K., “Principles Of Electrical Machines,”(2006)
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Generator cooling and sealing system 2

  • 1. Training report: Generator Cooling and Sealing System Mohd Basid Azmi B.Tech(Electrical)
  • 2. Generator Specifications Rating of Turbo Generator KVA Rating Coolant: :247MVA Water And Hydrogen Connection: KW Rating : Phase Gas Pressure: Star-Star 210MW Connection: 3.5 Kg/Cm3 Double Star Voltage : Phases: 3 15750 V- Rated Speed: Insulation: RatedFrequency Stator,310 V - 3000 Rpm Class B :50 Hz Rotor Amperes : 9050 Maker & Year: Rated Power BHEL (Haridwar) Type: Thw-210-2 A- Stator,2600 A - Factor : 0.85 Lag 1986-87 Rotor
  • 3. NEED FOR GENERATOR COOLING SYSTEM Large no. of conductors • insulation blisters: conductors grow and elongate • generation of large amount of high heat. currents flowing in the windings
  • 4. Hydrogen Cooling Minimize drag - “windage” Keep generator internals clean Maximize generator output Minimize electrical, mechanical and corrosion problems better heat transfer increase breakdown voltage
  • 5. Rotor cooling system gas flow maintained by pressure difference between the inlet wedge and outlet wedge Specifications: This method gives uniform distribution of temperature and Gap Flow directed along the ventilating A) H2 Pressure : 3.5kg/cm2 eliminates the deformation of Pickup canals made on the hot zone of the B) Purity : 97% copper due to high temperatures Cooling rotor. C) Gas Volume : 66 m3 Hydrogen gas in the air gap is sucked through the scoops on rotor wedges .
  • 6. Stator cooling system • The stator winding is cooled by distillate, • The system is designed to maintain a which is fed from one end of the machine by constant rate of cooling water flow to the a Teflon tube and flows through the upper stator winding at a normal inlet water bar and returns back through the lower end temperature of 40°C. of the other slot. • The stator winding is cooled by circulating Specifications: the dematerialized water. A) Water Pressure : 3.5 kg/cm2 • DM water used for the cooling of the stator B) Qty. Of Water :130 m3/Hr winding calls for the use of very high quality of cooling water. For this purpose DM water of specific resistance is selected.
  • 7. Generator Sealing system • Sealings are employed to prevent leakage of hydrogen from the stator at the point of rotor exit. • The seal oil is a portion of the lube oil, diverted from the lube oil system. It is then fed to a separate system of its own with pump, motor, hydrogen detraining or vacuum degassing equipment, and controls to regulate the pressure and flow. • A continuous film between the rotor collar and seal liner is maintained by the means of oil at a pressure, which is about O.5 atm above the casing of hydrogen gas pressure. • The thrust pad provides a positive maintenance of the oil film thickness.
  • 8. Generator Seal Oil System System functions: • supplying the generator shaft with seal oil with hydrogen. • permanent monitoring and differential pressure regulation of hydrogen and oil, • oil seal maintenance – air and hydrogen separation, – oil filtration, – temperature regulation, • removing oil vapors and hydrogen from the hall.
  • 9. Generator Seal Oil System • This system follows the following path: • Main Oil Tank • Main Oil Pump • Seal Oil Cooler • Seal Oil Filter • Damper Tank • DPR (Differential Pressure Regulator) • Hydrogen Seal • Seal Oil Fans • Main Oil Tank • This system has two more pumps: • AC Seal Oil Pump • DC Seal Oil Pump
  • 10. Generator Seal Oil System • The pressure of seal is 4.2kg per sq Cm. while the pressure of hydrogen is 3.5 kg per sq. cm. The purpose of this system is to provide seal to the hydrogen used for cooling of stator. If the seal breaks, the system also breaks down. • MOT(main oil tank):- It contains 28000ltrs of turbine oil. It supplies oil to all bearings and seal. • MOP(main oil pump):-It takes from the main oil tank and supplies further. • Seal oil cooler:- It contains clarified water and distilled mineral water. The outer covering area is called housing. It covers an assembly of about 200 tubes assembled on plates. Air gaps are found between the tubes (25mm above, below and on each side of each tube).These gaps are filled using hydrogen which cools the stator.
  • 11. Generator Seal Oil System • Seal oil filters:- These are rounded mesh like structures kept over each other. There are about 34 filters present. • Damper tank:-It is kept at 14mtrs of height above the ground. If MOP fails A/C or D/C pump works and if these fail then damper pump comes into action. Here the hydrogen pressure is .7% to .9% less than the oil pressure because if the hydrogen pressure increases, the seal would break down. • DPR(differential pressure regulator):- The function of DPR is to regulate the pressure of the oil and balance it. Whenever main oil pump fails, the AC seal oil pumps starts automatically .DC seal pump fails but it can supply the oil up to an hour. The generator is kept at a height of 8meters so that oil is supplied by pressure.
  • 12. Generator Seal Oil System Sealing Data: A) Seal Oil Pressure :4.1 To 4.4 Kg/Cm2 B) Quantity :80 Lt/Min C) Type :Radial Flow, Double Chamber Thrust Type AC Seal Oil Pump: A) Type :Multistage Vertical Split Centrifugal Type B) Capacity : 3.34 Lit/Se At 12kg/Cm2 DC Seal Oil Pump: A) Type : Multistage Vertical Split Centrifugal Type B) Capacity : 4.16 Liters At 12 Kg/Cm2 Line Charge Capacity :75 MVAR
  • 13. References • Kothari, D. P. , Nagrath, I. J. " Electric Machines" (2012) • Mehta, Rohit, Mehta, V. K., “Principles Of Electrical Machines,”(2006)