February 10, 2020

High-Tech Expansion Joints for Geothermal Project in New Zealand

We have successfully designed, manufactured and tested several high-tech expansion joints for Ngawha Extension Geothermal Project in New Zealand.

The expansion of the Ngawha geothermal power station will increase security and reliability of the power supply for Northland. Construction is underway to expand the Ngawha geothermal power station and more than double the power station’s generation capacity to 53 megawatts by June 2021.

Using ‘state of the art’ technology, geothermal fluids are passed through a heat exchanger where energy (heat) is transferred to a working fluid (pentane). The pentane then boils to form a high-pressure vapour which then drives the turbines, turning the generator. After the vapour has passed through the turbines, it is condensed back to a liquid and returned to the heat exchanger in a continuous cycle. The pentane is not consumed as a fuel, but is simply used as a working medium to extract energy from the geothermal water and steam.

Mechanical design, parameters and features of the expansion joint supplied are:

2 Units Pressure Balanced Expansion Joint, MPB-E Series, DN 1650 (66") and 6800 mm long.

  • Bellows in SB443 N06625 with 2 ply testable leak detector.
  • Design Pressure: 8,3 barg
  • Design Temperature: +120 / -29 °C
  • Medium: Pentane

4 Units Universal Tied EXPANSION JOINT, MFL Series, DN 400 (16") and 2000 mm long.

  • Two multiply bellows in SB443 N06625, with 2 ply testable leak detector.
  • Design Pressure: 30 barg
  • Design Temperature: +200 / -29 °C
  • Medium: Pentane