Project Background
Tallawarra Power Station, owned by EnergyAustralia, uses seawater for it’s cooling water system. As part of environmental obligations, Tallawarra must filter out marine life and debris and return them to the lake via a separate channel.
Two submersible flushing pumps were being used (2×50% duty) to maintain sufficient water level in the fish return channel. The problem was that these submersible pumps required frequent costly and complicated maintenance, which required a mobile crane to be hired for every maintenance occasion. Despite the high maintenance time and effort put into these submersible pumps, they still failed far too often.
Pump Upgrade
In 2019, funding was granted to replace these submersibles with better quality pumps.
To buy a complete stainless steel pump is very expensive, but there is a unique method to create a saltwater resistant pump without the added expense.
The Gorman-Rupp T8A61S-B model was chosen. These pumps have cast iron casings with marine grade (316) stainless steel rotating parts. Typically, the cast iron would corrode in saltwater. Corrosion is caused by an electrochemical reaction, which will attack cast iron. To combat this, a replaceable sacrificial zinc anode rod is inserted into the pump via an unused casing heater port adjacent to the rotating assembly. The corrosion then attacks the zinc rod, not the cast iron. This is called cathodic protection. The Maintenance team onsite gauge how quickly the zinc rods are corroding – and change the zinc rod periodically. Because the Gorman-Rupp T8 is a surface mounted self-priming pump, maintenance is simple and easy – no cranes required – just one operator and two spanners is all it takes. The zinc rods are easy obtained, as they are stocked by Hydro Innovations.
The benefits of the new pumps are:
- Reduced pump maintenance costs
- Safe access to the pumps at all times for operations and maintenance
- No cranes required for pump maintenance
- Increased pump capacity allows for Duty/Standby operation and channel aeration during station outages.
- Eliminate the need to hire in additional submersible pumps, due to pump failures or channel aeration.
The pumps were commissioned in July 2020 and EnergyAustralia is enjoying the benefits of these rugged and dependable pumps.
