- After removing all bearing upper liners, labyrinths clearances w.r.t rotor surface are taken, by means of feeler gauge.
- The labyrinths are air labyrinth and the oil resisting labyrinth.
First Stage Nozzle and Inner Support Ring
- The first stage nozzle is in two halves, bolted together, and supported with the side supporting blocks. The blocks are removed first, then the nozzle rings bolting is removed. The upper half of the nozzle ring is lifted up, whereas, the lower one slides from one end to remove from the housing. Nozzle ring rests on the inner support ring which is bolted with the CDC inner cylinder aft end.
- Before unbolting the marriage turbine couplings, U-clamp along the bearing stand is attached prior, at the aft end of the compressor rotor.
- Similarly, while unbolting the load shaft turbine couplings, the fwd flange of the load shaft coupling is hanged by the chain block or lever hoist.
Methods for unbolting the coupling bolts are:
- Hammering with the Striking Spanner
- Pressure Source (Avanti-350 to 400bars)
Disengaging the Marriage Coupling
- After the unbolting, the jacking bolts are used for pushing the turbine rotor for getting free the rabbit of compressor rotor.
- Jacking bolts are accessed from the opening holes of the compressor rotor aft flange to the surface of fwd flange of the turbine rotor.
- The bolts are jacked uniformly from both end, so that, turbine rotor travels smoothly.
- The compressor rotor should be at active side of thrust bearing. The turbine clearances should also be under consideration while pushing the rotor.
- Thrust bearing should be removed after the disengagement of the marriage coupling.
Thrust Bearing Removal
- The base rings of thrust bearings are composed of lower and upper halves, which are connected to each other by male and female fittings. Pads are pivoted inside the base rings and can be inserted by sliding into each pad housing.
Uplifting of the Compressor Rotor
- The guides are placed at the fwd and aft flanges of the rotor.
- Dial indicators are appointed at the rotor surface by keeping their mountings on surface free from the rotor.
- As, the crane booms up, the dial indicators indicate the readings of lifting.
- The lifting beam is used for lifting the rotor.
- A turn buckle is introduced at the fwd end of the beam, whereas, the aft end only has the trunnion on both sides. Slings/polyester belts are used for lifting as per lifting plan. The equilibrium is maintained by varying the length of fwd end of beam through turn buckle.
- Equilibrium, while lifting, achieved, if both dial gauges assures the equal readings.
- Weight factor should also consider while booming up the rotor, and it shouldn’t exceed from the S.W.L as per lifting procedure. If it does, should the rotor be resisted at any end. Stop the lifting, and check for any abnormality.
- The blade clearances should continuously be monitored, while lifting.