MAJOR OVERHAUL OF TURBINE AND GENERATOR FOR UNIT A3

Steam Turbine specifications:

  • Output Power: 200 MW
  • Manufacturer: LMZ (Russia)
  • Type: K-200-130-1 Condensate
  • Three Cylinders: HP, IP, and LP
  • Incorporating Fresh and Reheated Steam
  • Commissioning Year: 1970


Scope of Turbine Works:

  • Exquisite turbine overhaul, encompassing meticulous dismantling, thermal insulation as per manufacturer’s guidelines, precision measurements for outer covers, cross-over pipes, bearing housings, upper parts of journal bearings, rotors couplings, and cylinders (HP, IP, and LP). Comprehensive inspection and maintenance of main oil pump, turbine governing system, stop valves, protection valves, and governing valves for HP and IP Cylinders.
  • Thorough maintenance includes cleaning of integral oil piping systems for lube oil control, generator oil, adjustments, and sealing systems of the generator tank, including oil turbo-coolers 1, 2, 3. This extends to the sealing oil tank of the generator, sumps, and meticulous closure of turbine and generator bearings.
  • Precise measurements conducted include positions and air clearances, rotor-stator displacement, and a comparative analysis with 2012/2013 overhaul values. Assessment of steam flow components, including eccentricity measurement of rotors, and post-dismantling. A thorough examination of turbine diaphragms for deformations, thermal clearances, and self-vibrations of rotor blades in specific stages. Inspection of lower turbine parts post upper part dismantling, balance weight analysis for HP, IP turbine supports, and comprehensive assessment of vertical and horizontal turbine dilatation components (thermal ventilation). Journal bearings are preliminarily prepared with new white metal TEGO 738, leading to the achievement of final dimensions. Evaluation of radial and axial rotor positions follows the definitive alignment of the rotor line, with a focus on vibrations during startup under different regimes (with and without load), encompassing measurement of phases, amplitudes, and frequencies.
  • Non-Destructive Testing encompassing internal and external inspection of cylinders/casing, seizing pipe examination from steam turbines 2, 3, 4, 5, 6, and 7, including return dumpers up to the damper valve of the receivers. Inspection of rotors, nozzles of HP and IP casings, diaphragms, rings of diaphragms, bolts, stop valves, protection valves, governing valves, U-pipes from protection valves of IP casings up to governing valves, and U-pipes from protection valves (repair bearings) of HP, IP, and LP cylinders.
  • Comprehensive repair activities encompass cylinders and rotors of HP, IP, and LP, main oil pump, including turbine governing system, stop valves, protection valves, and governing valves of HP and IP Cylinders. Additional tasks include balance weight analysis for HP, IP turbine supports post upper part dismantling, assessment of vertical and horizontal dilatation components of the turbine (thermal ventilation), addressing cracks in turbine casings based on NDT results. Repair activities extend to turning gear, explosion dampers of LP Cylinder, and preliminary preparation of journal bearings with new white metal TEGO 738, culminating in achieving final dimensions. The scope also covers the heating system of flanges and bolts in HP Casing and IP Casing, with considerations for replacement based on control results, as well as addressing lubrication pumps and the start-up pump of the turbine.
  • Precision assembly involves the application of thermal insulation per manufacturer instructions, oil sealing, and integration of the integral oil piping system for lube oil control, generator oil system, adjustments, and sealing systems of the generator tank, including oil turbo-coolers 1, 2, 3, and the sealing oil tank of the Generator. Additionally, the installation of three new oil coolers and the start-up pump of the turbine is carried out.
  • Commissioning involves the integral oil piping system for lube oil control, generator oil system, adjustments, and sealing systems of the generator tank, including oil turbo-coolers 1, 2, 3, and the sealing oil tank of the Generator. It also covers the commissioning of lubrication pumps and the start-up pump of the turbine.

Generator:

  • Manufacturer: ELEKTROTYAZMAS, Kharkov – Ukraine
  • Output: 200 MW
  • Type: TGV-200, 15,750V, 3,000rpm, 50Hz, 3 Phase
  • Start-up Year: 1971

Stator Works Included:

  • Visual inspection and repair of all electrical and mechanical components

  • Electrical inspection of the Stator conducted both before and after the overhaul

  • In-depth investigation and meticulous mechanical and electrical repair of zero and phase insulators of the generator

  • Precision Painting of stator windings

  • Dismantling, inspection, and repair of bearings, with necessary sealing on the sides of bearing no. 6 and no. 7, as required, including filling with white material

Rotor Works Included:

  • Visual inspection of all electrical and mechanical components of the rotor post-dismantling
  • Precise measurement of rotor eccentricity before and after processing-ratification, including consideration of hats re-tightening rings
  • Rectification of damaged rotor surfaces and Non-Destructive Testing
  • Rectification of collector rings
  • Inspection of rotor cooling channels
  • Inspection and repair of wrap connections (flexible slopes) with the brush collector rings
  • Verification of the connection of the contact bolts seal for current conduction
  • Replacement of brushes and damaged brush holders, along with calibration
  • Procurement and installation of clutch tubes for the brush holder
  • Repairing the seal of the lodge – brush holder and applying a protective coating
  • Dynamic balancing performed after rotor repair
  • Procurement and installation of new metering circuits in the generator for temperature measurement (iron, copper), along with transmitting all these measurements to the control system using new instruments
  • Thorough sealing of the generator, encompassing all metering exits, insulator exits, and mechanical parts

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