VIBRATION DATA ACQUISITION, ANALYSIS AND TROUBLESHOOTING OF ROOTE CAUSE
PLANT LOCATION: Iraq, Zubair
Zubair 1 is a northern Iraqi based Power Plant that accounts for a single Turbo Generator train manufactured by GE Oil & Gas. The gas turbine is a GE MS5001P DLN1 operating on single gas fuel, the generator is a GE Energy Power Conversion unit. The two units are coupled by a speed decreasing Flender-Graffenstaden gear box.
The plant was commissioned by the end of January 2016 and is intended to operate on a grid- parallel configuration to help with the rising power demand of the Iraqi nation.
Awaiting for the hand-over to the final client South Oil Company the plant was operated for several months by the EPC contractor Unaoil. During this time, problems to the main export breaker had limited the unit power to the lower half of its load capability only to later discover that loading the generator above 13 Mw caused high vibration on the load gear box #1 Bearing. (DE side HS shaft).
By the time the vibration problem first appeared the contractual warranty with General Electric had expired and the GE commissioning team had already left the site. The vibration issue became a major punch list point of argument effectively preventing the final hand over of the plant to SOC and causing considerable financial losses for Unaoil.
SSE was contacted by Unaoil to analyse the vibration problem and recommend corrective actions.
The project was divided into two major tasks:
- Collect and analyse the vibration data, issue a comprehensive RCA and recommend on the corrective action.
- Provide support to the customer by planning the intervention, help with the site readiness for the corrective action and execute the troubleshooting in cooperation of material and resources.
SSE Control and Mechanical Engineers travelled to the site location to carry out the Control and Mechanical inspection task agreed with the customer. The Control Engineer completed the functional check and testing of the vibration probes to ensure the problem was not caused by an instrument malfunction. During two dedicated test run the multi-channel data collector was used to acquire useful information on the turbine, gear box and generator vibration behaviour. The data were remotely sent to the SSE office to be analysed were internal expertise and the use of a specific software helped to determining the most likely cause at the source of the vibration. During the analysis it was immediately evident that the vibration level increased in relation with the thermal growth of the unit during warm up and loading, The vibration was particularly sever on the load gear box HS DE bearing and was tracking the 1X frequency order from start up to the maximum achievable load. The phase analysis across the coupling suggested that something was potentially wrong with the coupling installation/operation or the unit skids alignment.
The customer quickly received a report containing the RCA, recommended troubleshooting actions and recommendations pertaining the planning of the needed mechanical intervention. SSE primarily recommended the removal and inspection of the coupling and carry out an alignment check despite the commissioning quality control record found at site. The intrusive mechanical inspection meant leaving the unit out of service for a certain time window and the intervention was postponed to optimize the preparation of tools, documents, spare parts and resources. During the second phase the coupling was removed and found improperly installed with sign of bolting damage due to mechanical interference and low pre-stretch.
The unit alignment was also found out of specification and corrected. Following additional planned inspections to the gear box and oil piping to unit was reassemble and restarted. Upon restart the unit was allowed a gentle warm-up showing immediate sines of improvement. Following a synchronization and loading to 15MW the maximum vibration levels measured on the train were recorded at a very acceptable 25 microns.
|SUPPLY||N° 1 GE Turbine MS5001P DLN1
N° 1 GE Generator Frame size A183D4
N° 1 Flender-Graffenstaden Gear Box TX80/3C
|CONTROLLER||GE MK VIe, GE MKVIes, GE Bently Nevada 3500 Vibration Monitoring , G60 Generator Protection Systems|
|SUPERVISION||SHINKAWA Kenjin System|
Type of Project:
Vibration data acquisition and analysis.
Scope of supply:
Provide equipment and expertise to carry out a completed vibration data collection from the operating turbo generator. Analyse the data and issue a complete report with potential Root Cause Analyse and recommended corrective action. Provide the expertise to implement the corrective actions and test the effectiveness of the results until the troubleshooting is successfully completed.
The customer was able to complete the loading and final testing of the unit clearing a major hold point of their punch list.
The unit can now be safely operated to its maximum load capacity without exhibiting abnormal vibration levels and the customer has begun the final plant hand over process to the final client