Simple pump upgrade raises pressure and saves energy

Kia Motors happy with Grundfos screw pump and frequency converter in drilling machine

At a Kia Motors plant in Hwaseong, Korea, the drilling machine operators were losing patience. The gear pumps (not from Grundfos) for cooling lubricant performed poorly and broke down often. Kia was forced to replace entire pump sets after breakdowns, forcing up repair costs.

Furthermore, a fixed-speed motor drove the pumps. This meant that the pumps supplied a constant flow of emulsion no matter what the machine tool actually needed for the required pressure.

The global automotive manufacturer needed a better solution. Grundfos suggested that Kia Motors try a Grundfos MTS screw pump along with a CUE frequency converter – something Grundfos advised was more reliable and would save money.

At first, Kia was not convinced that a pump of this kind needed an inverter concept, says Wonjae Kim, Industry Sales Engineer, Grundfos Korea. So Kia agreed to try out the concept in a field test.

The test
With the integrated frequency converter, the MTS cut the flow rate and rotation speed in half, Kim says.

“We reduced the bypass flow that was wasted by the existing pump and eliminated the flushing flow, so that we could set the pump speed at 49% (about 30 Hz) – still keeping a higher pressure than the previous pump,” he says. He adds that the operating noise was reduced along with the motor speed.

In addition, the MTS reduced power consumption by 60%.
“The previous pump had been operating at the highest pressure (60 bar) at the highest power consumption when the discharge valve was closed,” says Kim. “The CUE frequency inverter lowered the pressure when the discharge valve closed. The valve is closed for almost half of the total pump operation time, so we could get much more energy saving through the pump system.”

The previous pump used 110 kWh/day, whereas the Grundfos MTS used 45 kWh/day. The operator from Kia Motors, Il Pyo Hong, was very satisfied with the Grundfos field test.

“We think that this decision to have a pilot project with Grundfos’ inverter solution was a good decision,” Hong says. “We have witnessed a remarkable performance. This system will help us to save the operation cost.”

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