Reliable geothermal power generation in New Zealand through advanced flow control

As the new plant was built, the customer aimed to ensure high reliability from the start. The process conditions at the site are known for their complexity, especially for flow control equipment. This project brought together Valmet, the EPC and the end user to develop a solution tailored to the plant's operating requirements. However, the customer already had experience with numerous models of Valmet's Neles^TM control valves, which had been operating successfully in parts of an older plant for more than five years.

Addressing corrosion, scaling and control issues

Equipment exposed to geothermal steam and brine is subject to some of the harshest conditions in the energy sector.

At the site, the geothermal process media contain hydrogen sulphide and chlorides. These chemicals can cause stress corrosion cracking if the wrong materials or designs are used.

Scaling adds another challenge. In the older plant, heavy scale often caused valves to stick, which made accurate control difficult and caused interruptions that reduced plant output.

Because issues like corrosion and scaling are common in geothermal plants, the customer wanted solutions based on proven performance in similar environments.

Building a solution based on geothermal experience

Valmet's flow control experts worked closely with the EPC and the end user to review process conditions and operating history. Our industry experts contributed insights from similar geothermal applications to support the final solution.

The scope included:

• Neles L6 butterfly valves, some with a Neles Q2-disc attenuator for noise reduction
• Neles Finetrol^TM control valves
• Neles X Series metal-seated ball valves
• Neles NDX^TM intelligent valve controllers for diagnostics and precise control

The Neles NDX controller has been especially valuable for operators. Its clear diagnostics help them understand valve behavior, monitor operating conditions, and detect early signs of issues before they affect power generation.

Built for demanding process conditions: the Neles Finetrol eccentric rotary plug valve combines advanced cavitation control with superior wear and scaling resistance, paired with the Neles NDX intelligent valve controller for precise performance and actionable diagnostics.

Improved reliability through proven performance

The customer's previous experience with Valmet's valves in the older plant gave them confidence to select our equipment for the new facility. The improved reliability they saw there has now been carried into the new plant.

The solution helps the customer:

• Reduce issues caused by scale-related sticking
• Maintain predictable valve performance
• Lower the risk of unplanned downtime
• Improve day-to-day operating stability

By combining robust valve design with advanced monitoring, the plant can operate more consistently, even when conditions change.

A partnership based on application knowledge

The customer was looking for a partner with a strong understanding of geothermal power generation and equipment that performs reliably in corrosive and scaling-heavy environments. Through proven valve designs, diagnostics and close collaboration throughout the project, Valmet was able to meet these needs and support the long-term performance of the separation plant and power plant.