ABB AEG KANIS G20 9.445MW Steam turbine Major Repair after Reverse Power in generator
After a power failure in the power supply of the control/protection system, a situation occurred in which the generator operated as a motor after the steam supply to the turbine was cut off (turbine trip). The turbine operated at reverse power for about 4 hours causing damage in the turbine. Energetic was called in to investigate this situation and to submit a repair proposal.
Figure 1: Inner casing
Figure 2: Installation
This industrial turbine from the paper and pulp industry had been in operation for approximately 30 years.
Our team of experts rapidly arrived at the client’s site to investigate this situation. After dismounting the turbine it was observed that several rotor blades from the second carrier were damaged, some were out of position including the locking blades. Moreover 2 rotor blades from the second to the last row had flown off. The complete section blades were to be replaced.
Figure 3: Damaged rotor blades and seal strips
The seal strips on the rotor and those of the first and second carriers were also worn. Damaged blades were also found at the last 2 rows of the second carrier.
Figure 4: Damaged carrier blades and seal strips
Following the damage, microstructure examination by replica was carried out on the blades. The purpose of the investigation was to determine the degradation and condition of the blades and to determine the presence of creep damage. The result from this examination showed some thermal degradation on the material, but however the material was free from detrimental defects and creep.
Firstly our engineering team scanned the rotor with a high accurate and fast 3D scanning machine to get all the data of the blades. Then we performed reverse engineering activities to create new models of the blades. All the rotor blades of the second carrier were completely renewed and quality checks were performed with highly advanced 3D inspection software. The static blades of the Last 2 rows of the second carrier were also renewed by applying the same techniques.
Figure 5: Scan rotor blades
Figure 6: 3D quality check rotor blades
Figure 7: New rotor blades
The rotor and the carriers were fully equipped with new sealing strips. With our experience in this technology we are able to replace sealing strips very fast and at low cost.
Figure 8: New seal strips rotor
Figure 9: New seal strips carriers
The turbine bearings DE and NDE which were damaged were completely repaired and replaced.
Figure 10: Turbine bearing DE damaged
Figure 11:Turbine bearing DE repaired
The bearing journals of the gearbox pinion showed deep grooves all over the surface and were repaired by laser cladding and then machined.
Figure 12: Grooves on bearing journals gearbox pinion
Figure 13: Bearing journals gearbox pinion repaired by laser cladding
The white metal of the pinion bearings showed some damages and were completely renewed.
Figure 14: White metal pinion bearings damaged
Figure 15: White metal pinion bearings repaired
Other repair activities
By applying reverse engineering we manufactured new DE and NDE steam boxes. The parts were scanned, 3D models created with advanced 3D software and production drawings were made, then the parts were produced in our facility. Following production we perform quality checks of the parts. Having all this process in hand makes us deliver quick service with undisputable quality.
Figure 16: Scan & 3D model steambox NDE
Figure 17: New steambox manafactured
New oil labyrinth were manufactured by the same techniques.
Figure 18: New oil seals manufactured
Manufactured spare parts
Besides manufacturing parts for immediate installation we also manufactured spare parts for our client such as the bearing pads DE, NDE and axial pads. In this way we can quickly help our clients in case of emergency situations.
Figure 19: New spare bearings
With our extensive knowledge of turbomachinery, reverse engineering, a well-equipped in-house production facility and a dynamic team we are able to solve turbomachinery issues at affordable costs and we beat all concurrence in terms of flexibility and quality.
*Energetic nv has no agreements or any relationship with the original equipment manufacturer