In April, Monadelphous completed a major shutdown at the Kwinana Cogeneration Plant, south of Perth, on a tight 28-day schedule. The shutdown involved upgrading, repairing and inspecting hardware and equipment.
Monadelphous – The Australian engineering group providing construction, maintenance and industrial services to the energy sector – has operated and maintained the plant since 2011, after the acquisition and integration of asset management company Pearl Street Energy Services.
The plant comprises of a General Electric (GE) Frame Six Gas Turbine, with an Alstom Electrical Generator and a heat recovery steam generator. The plant produces steam and electrical power – supplying the steam and power to industry, and electricity to the homes of West Australians.
The shutdown involved stripping the gas turbine, removing the turbine rotor and upgrading the hardware across the turbine to the GE 24K T-Fire specification. This was undertaken upon recommendation and in collaboration with GE.
Some repairs and alterations were made throughout this outage to include weld repairs and alignment moves, to bring the turbine and generator within the recommended specifications and ensure the reliability and longevity of the facility.
GE completed a major inspection of the generator, including removal of the rotor, a full mechanical and electrical inspection of the generator stator. The assessment included a ‘tap’ test to measure the tightness of the wedges, which uncovered the need to completely re-wedge the stator.
The first ‘time of flight ultrasonic testing’ of the 18/18 material retaining rings in Australia, was carefully completed by industrial service provider Quest Integrity Group.
Other major upgrades include the new GE Mark 6 ES speedtronic system installation (which controls the entire facility) and an upgrade of the Ethernet connection to Modbus, enabling a clearer, faster connection and communication between the Siemens DCS T3000 control system and the GE speedtronic.
The single helix gears were removed and upgraded to double helix gears inside the load gearbox, and the Triple S clutch removed, with this work being completed by gearbox manufacturer Flender Graffenstaden. Freudenberg Filtration Technologies manufactured and fitted both the new silencer and elbow, which connect the filter housing to the gas turbine.
They also repaired the filter housing and installed a full complement of depth load filters for the turbine and the generator, delivering 50 per cent more airflow across the machine.
Global Testing Services manufactured and installed the high-grade marine aluminium medium-voltage (MV) cell and all six radiators on the 11KV transformer.
A life assessment of the high energy pipework was completed as part of the shutdown. The critical welds in the high pressure and NOx steam pipeworks were selected based on the piping analysis and risk assessment conducted by Quest Integrity Group. Advance inspection tests, including time of flight ultrasonic testing and phase array tests, were also carried out on the selected welds to assure integrity of the steam pipeworks.
Monadelphous engaged more than 10 contractors for the shutdown, with approximately 60 personnel on site each day, and a total of 17,754 man hours worked in the 28-day outage.
Despite a tight schedule and the complexity of multiple contractors on site, the work was completed on time, incident- and injury-free.
Site manager Jamie Dunkley attributes these achievements to the commitment and focus of all involved and Monadelphous’s highly evolved safety culture.
“These results were achieved through the precise planning, hard work and determination of our team at the facility and all our contractors, suppliers and connections. All our onsite employees are passionate about the facility and committed to safe working practices,” he said.
As an additional outcome, Monadelphous received The Most Powerful Frame Six Gas Turbine Award from GE AN&Z for achieving 47.8MW post shutdown, which currently is the most powerful 6B turbine outcome in the region using the 24K and T-Fire upgrade.
“Monadelphous has performed five shutdowns at the plant since acquiring the contract, however this latest shutdown was the largest and most complex, involving more than 10 different contractors working simultaneously as one team, ensuring the tight schedule was achieved,” Jamie said.
