100% oil-free air PTS 1600 compressors quickly and safely cool down a 500°C steam turbine

About six months ago, one of the largest power plants in Hong Kong needed a complete overhaul. In order to carry out the necessary maintenance to the plant’s steam turbine, it had to be shut down. Allowing the turbine to cool naturally would have been a very time-consuming process.

That is why, together with our customer, we looked for a safe, both time and cost efficient way to speed up the cooling process while keeping in mind Hong Kong’s strict noise regulations. Thanks to our efficient coordination and state-of-the-art equipment, we managed to deliver the best solution to our customer. The customer contacted us in the run-up to a complete overhaul of one of the largest power plants in Hong Kong. Their main concern was cooling down the plant’s steam turbine, which can mean approximately 10 days downtime in advance of the maintenance period. This interruption in activity could lead to a potential loss of several millions of USD. Our task was to speed up the cooling process.

Cooling down a steam turbine: a risky and time-consuming job!

Just after the shutdown of a steam turbine, the temperature of the impellers is still close to 500 °C. With such high initial temperatures, safely cooling a steam turbine with air presents significant hazards. A large volume of air can deform the impellers, therefore it is essential to calibrate air volume very carefully. This meant that the ideal solution for the customer consisted of compressors able to provide oil-free low-pressure air at a high flow rate.

How we managed in only 3 days

To meet the client’s demands we supplied two PTS 1600 100% oil-free mobile air compressors. Each compressor provides air at a flow of 30 m3/min at 1.1 bar. Using both compressors together at the start of the cooling process would have resulted in excessive air pressure and volume. To avoid damages, we started the cooling process with just one PTS 1600 compressor with an export temperature of 30°C. After two days, when the impeller temperature had successfully dropped to 150°C and the risk of deformation had decreased, we activated the second compressor. In this way we were able to provide compressed with both low pressure and high flow, which successfully sped up the process and resulted in a much shorter cool-down period of only 3 days instead of the expected 10.

Keeping it quiet

We also had to make sure our equipment complied with Hong Kong’s noise regulations for large, imported industrial machinery - which are some of the strictest in the world. To avoid unnecessary administrative delays, we tested the noise levels of the compressors before starting the customs clearance process to import the equipment. The tests showed that the noise level of our equipment was 79dB, which is substantially lower than the noise level limit of 90dB predefined by the Hong Kong Environmental Protection Department. We were ready to begin the cooling process!

Efficient coordination

Once the project took off, we focused on working in an efficient and organized manner in order to save as much time as possible.

Thanks to our efficient coordination of the shipping, customs clearance and installation processes, cooling down the steam turbine only took only a few days. Our way of working was much appreciated by the customer, who was really satisfied and is planning to rent our equipment again for other maintenance projects.

Liu Guo Xiong , National Key Account Manager at Atlas Copco Rental China

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Great ideas accelerate innovation. At Atlas Copco we have been turning industrial ideas into business-critical benefits since 1873. By listening to our customers and knowing their needs, we deliver value and innovate with the future in mind. Atlas Copco is based in Stockholm, Sweden with customers in more than 180 countries and about 37 000 employees. Revenues of BSEK 95/ 9 BEUR in 2018. Learn more at www.atlascopcogroup.com. Great ideas reinforce sustainable development. At Atlas Copco Specialty Rental we team up with our customers to set up state-of-the-art temporary air, power, flow, steam and nitrogen solutions. Our passionate experts have extended application as well as equipment knowledge. We understand our customers' needs and can provide a total solution for any industry, no matter if it is for emergencies or planned projects. We are a division of the Power Technique business area, headquartered in Boom, Belgium and offer specialty rental solutions under several brands around the globe.