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Rapid nitrogen intervention helps with the repair of a New Zealand geothermal power station

6 August 2021

When a geothermal power plant breaks down, urgent repairs are required to avoid high costs. As the rotor chamber contains highly flammable pentane gas, adding nitrogen speeds up the repair process, limiting downtime of the plant. Atlas Copco Specialty Rental managed to get this geothermal power plant up and running again in 3 days.

Providing safety

Nitrogen is used to push out highly flammable gas in the rotor chamber

Minimizing downtime

Same day delivery and high purity nitrogen speeds up the repair process, minimizing the downtime of the geothermal power plant

Setting new standards

The same solution can also be replicated to other geothermal power plants

If a geothermal power station breaks down, urgent repairs are required. In order to access the pentane turbine rotor you first have to remove the highly flammable pentane gas which is in a pressurized chamber. Every day the turbine is out of commission has a costly effect in lost generation! This is precisely the predicament in which Ngawha Generation Ltd, the owner of a number of geothermal power plant units found itself. Luckily, Atlas Copco Specialty Rental came up with a fast, efficient and fully compliant solution for assisting with safe access.  It also delivered both the equipment and personnel required to launch the project on the very same day. 

Geothermal power plant turbine defect triggers specialized support

The Ngawha geothermal power plant

The Ngawha geothermal power plant

A simple failure in the bearings of Ngāwhā Geothermal Power Station’s pentane turbine required a timely intervention. This was the first time a breakdown of this kind had occurred on the new plant. Fabian Hanik, Assistant Plant Manager and his team along with the Atlas Copco Specialty Rental New Zealand team worked towards an innovative solution. Preferably one that complied with stringent local regulations –& preferably fast – since every day the problem went unsolved was also costing the client.

Planning a solution, reacting to clients’ needs at short notice

The solution came in the form of two state-of-the-art Atlas Copco NGM7+ nitrogen generating membranes. The modular design of the equipment also meant it could be easily connected to the customer’s own two 75kW compressors. The installation subsequently ran without fault for 3 days straight until a reading of 0 pentane was obtained and the sealed rotor chamber could be safely accessed. 

And back in again: recommissioning the turbine safely and reliably

Pentane vapour could, when mixed with the oxygen present in air, form a flammable mixture. So once the pentane rotor was stripped, repaired and finally reassembled, it was critical that the housing be depressurized to a negative pressure and then fully purged once more with high-purity nitrogen. 

The NGM+ generates onsite nitrogen with high purity

The NGM+ generates onsite nitrogen with high purity

A positive chain reaction: the power of a proven solution

The turbines of the geothermal power plant

The turbines of the geothermal power plant

Atlas Copco Specialty Rental’s rapid solution gave our customer the added peace of mind in case it ever happens again. However, it also means that other geothermal plants using pentane turbines will be able to follow the same procedure as well. Ensuring the continued viability of this renewable energy source, while also safeguarding the health and safety of workers and surrounding communities.

Time is money: a rapid response matched with efficient operation

The original call came in at 7.30 a.m. After devising and confirming a suitable solution, we succeeded in delivering the nitrogen units and all auxiliary equipment from Hamilton on the same day. We were also able to get 2 technicians from New Plymouth to drive to site and commission it straight away.

Simon Darby , Sales representative with Atlas Copco Specialty Rental (Australia)

Our team’s rapid intervention not only saved our customer at least 1 day at the beginning of the project. The second purging operation was also completed in just 2 days instead of 3. Needless to say, the total savings in terms of lost power generation offset the cost of the rental many, many times over. A textbook example of what it means to make agility count!

Simon darby

Simon Darby

Sales engineer Atlas Copco Specialty Rental New Zealand

Discover how we helped various industries to restart their production after an unforeseen breakdown.