Published in September 2007 Australian Longwall Magazine
Traditionally hydraulic pump stations have been designed using 300 litre per minute pumps working together to provide the longwall roof supports with hydraulic fluid. Physical cut through size constraints restricts the amount of pump units, making it difficult to keep adding more 300 litre/min pumps. More pumps also mean greater maintenance and a larger spare parts inventory.
New South Wales-based Longwall Hydraulics, through its KAMAT pumps, has kept abreast of this trend and carved a reputation in the industry as the supplier of large capacity pumping stations. The company has installed 16 385 litre/min pumps, one 439 litre/min pump and 12 523 litre/min pumps in NSW and Queensland.
"With any new technology there is a learning curve associated with its introduction and some inevitable growing pains. Large flow pump stations require new technology, such as suction boost pumps and suction stabilisers, in order to ensure smooth performance," Longwall Hydraulics managing director John Abercrombie said.
To overcome these issues Longwall Hydraulics has trialled and tested different configurations to get the design right.
One of the main challenges was achieving a net positive suction head (NPSH) to avoid cavitation. Large flow pumps require boosted suction to achieve the NPSH required as height restrictions underground limit tank and head size.
"Having a centrifugal boost pump in the suction line poses technological challenges in order to minimise emulsion shear and aeration problems which can result in cavitation. The type of oil used is also taken into consideration when the boost pump specification is selected," Abercrombie said.
The selection of the correct boost pumps was a challenge for Longwall Hydraulics and two models were trialled before a model was chosen which gave the pumps a steady flow of fluid at all performance levels.
The set up of the pump's suction side was a learning curve for the company. The diameter of the feed lines, the use of hydraulic hose and piping section and suction stabiliser selection must all be coordinated to achieve a steady flow of fluid to the pump head. Since Longwall Hydraulics' first boosted pumps were installed three years ago, the company has fine-tuned the suction set-up via testing, and now uses an improved suction stabiliser to minimise pulsations.
The latest installation for Longwall Hydraulics was the design, manufacture and installation of two complete pump stations at Anglo Coal's Moranbah North longwall in Queensland. Each pump station consists of three K25055 system pumps, each supplying 385 litres/min and two K25040 hi set pumps supplying 203 litres/min, making this pump station the largest capacity pump station in Australia, Abercrombie said.
Previously, Longwall Hydraulics supplied two complete pump stations to Illawarra Coal's Appin colliery. Each pump station consists of two K35060 system pumps, each supplying 523 lires/min and one K35040 hi set pump supplying 232 litres/min. This station also uses two centrifugal Sunflo shearer water pumps which supplies 770 litres/min.
Capitalising on its success in Queensland - Longwall Hydraulics has supplied five of the last six pump stations ordered by Queensland coal mines - the company opened a workshop in Mackay in June, and has expanded its Queensland service staff.
Also, Abercrombie and project manager David Saint have recently returned from a trip to the US, setting up a deal to launch a new range of products into Australia. The launch is planned for this year's AIMEX.
