National Grid Grain LNG
Project: On site motor testingRead More
A major Polyhalite mine in Cleveland, North Yorkshire operates at a depth of 4,600 ft. Polyhalite is found over 1,200m below the Earth’s surface.
The main dewatering pumps for the mine are a JSH 200 multistage ring section pump at 1,480 RPM, and a KSH 200 centrifugal pump at 3000 RPM. Between overhauls, the JSH 200 pumps between 1.2 – 1.4 billion gallons of water while the KSH 200 pumps 400 – 550 million gallons of water. Both pumps were underperforming due to general wear and tear.
Houghton International proposed to overhaul and upgrade the ageing pumps, improving their efficiency, reducing running costs and extending their working life.
Following the initial inspection of both pumps, a full overhaul was conducted on the JSH 200 pump which included the replacement of the balance disc, plate, impellers and bearings shaft, as well as the repair of mechanical seals and the manufacture of new rings and bushes. This was all reverse engineered using a Hexagon laser scanner, accurate to within thousandths of a mm. The pump was pressure tested to 200 bar and a performance test was carried out, providing a test curve.
Houghton International engineers also performed an overhaul of a KSH 200 pump and redesigned the balance disc, plate and balance sleeve from a three piece to a two piece to improve its efficiency. This type of multi stage pump produces axial movement towards the suction end of the pump and the balance disc and plate counter this thrust. Modifying the pump’s balance disc and balance sleeve to one combined disc reduces the likelihood of wear to the balance sleeve, which would result in an increased balance flow.
Using in-house CAD design expertise, Houghton International produced drawings and patterns to manufacture the redesigned components of the pump utilising a hard-wearing cast material to increase longevity.
Both pumps were fully overhauled, tested and returned to the customer at their site.
The super duplex material that both pumps were originally cast in had not deteriorated and therefore it was only necessary to repair parts that were worn and damaged internally. Choosing to repair rather than replace the pumps not only reduced the cost to the customer but also meant engineering improvements could be made, upgrading the performance of the pump.
As a result of the improvements to the design of the balance disc and plate, the KSH 200 pump now operates at an improved efficiency by reducing the amount of balance water and in turn, generating a higher flow from the same amount of power. By using harder wearing materials, axial wear improved on both pumps.
One of the challenges with older pumps is the supply of spares as the pumps may be obsolete or have much longer lead times. Having worked with pumps for 40 years and by utilising modern design technology to reverse engineer original components, we were able to identify where the major issues lie and what improvements we could make practically to provide a range of solutions.
Using our in-house machine shop we were able to remanufacture the parts required in a reasonable timescale, providing a more convenient and cost-effective alternative to buying a long lead time new pump at a greater cost.
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