February 7, 2014
“There’s a lot of work ahead of us, but it’s all really good positive work.” These were the thoughts today of Tarong Power Station site manager Dennis Franklin as he explained the processes that Stanwell employees and teams of contractors will now tackle to get the mothballed Unit 4 generating unit up and running.
Further down the track, Unit 2 may be a slightly more complicated job, but it was also something to look forward to.
Mr Franklin said it was good to be able to talk about something really positive after a couple of tough years at Tarong.
Stanwell’s announcement this week that the two power generating units, which were put into “cold storage” in late 2012, are to be restarted has been welcomed by everyone at Tarong.
Employees have taken it has a vote of confidence in the future of the power station.
However, the timing of the actual restart will depend on several factors.
A minor overhaul of the Tarong North generating unit is scheduled for May and a major overhaul of Unit 3 at Tarong is scheduled for August-September.
“Ideally, Unit 4 should restart a few weeks before the Unit 3 overhaul. If we can get it by mid-July that would be great,” Mr Franklin said.
But the restart is not a simple process. While it was in storage, Unit 4’s boiler was filled with nitrogen. Dehumidified air was also pumped through the turbine area to stop corrosion and to keep surfaces dry.
Holes were also drilled in some parts of the machinery.
These processes will now have to be reversed and any deferred maintenance attended to.
Unit 4 had a minor overhaul just before it went into storage so it is not scheduled for a major overhaul for another two years.
However, when Stanwell employees “lifted the lid” recently to inspect the turbine, cracks were detected in the rotor.
It wasn’t totally unexpected as similar problems had been found previously on Units 1 and 3.
The cracks reflect the age of the turbines, which have been in place – and spinning at 3000rpm – since the station was commissioned 30 years ago.
Unit 4’s 48.5 tonne turbine rotor will now have to be removed and shipped to NSW for repairs, which should take three to four months. It will then be returned to Tarong, re-fitted and re-balanced.
The repairs to the turbine rotor is the main critical job on the timetable to restarting the unit, along with the process of reversing the “cold storage”. Specialist testing and statutory inspections will also have to be carried out.
Stanwell also plans to take the opportunity to bring forward some work to air heaters in the plant.
Mr Franklin said restarting Unit 2 could prove a bit more problematic than Unit 4 as it was due for an overhaul when it was put into storage.
He also fully expected the turbine rotor on this unit would have to be repaired or replaced.
However, he rejected union criticism that “at least one of the mothballed Tarong units” had been “pilfered for spare parts”.
Mr Franklin said using parts that were on hand instead of waiting for ordered parts to arrive was an efficient use of resources. Any parts that had been removed from either unit had been recorded in registers and replacements ordered.
