Two months into its operation and a nitrogen gas generator from Atlas Copco is reported to be paying dividends in maintenance at the Tapada do Outeiro combined cycle power station in Portugal.

Situated in Gondomar, in the north area of Portugal, the Tapada do Outeiro combined cycle power station produces 15-20% of the country’s electrical needs.

The power plant has represented a new era in the production of electrical energy in Portugal since it started in 1999 and, using combined cycle gas turbine (CCGT) technology to generate power, was the first project of its kind on the Iberian Peninsula.

For the last two months it has relied on an NG 81 nitrogen generator from Atlas Copco Rental, to supply pure nitrogen to replace the air in the steam generator’s tubes when they are not in use, eliminating corrosion.

According to Atlas Copco, Tapada do Outeiro is ‘very satisfied’ with the quality and reliability of the equipment, which has required no maintenance since it has been in operation, as well as the technical team supporting the equipment.

Carlos Carqueja

Source: Atlas Copco

Carlos Carqueja, Engineering Manager at Tapada do Outeiro, said, “Nitrogen is used to preserve the steam generators. When they are not in use, air goes into the tubes, so the steam generators can suffer corrosion.”

“The replacement of air by high-quality nitrogen eliminates the corrosive effect on the steam generator.”

“The rental option, allows us, at a very reasonable cost, to test the technical viability of keeping a very poor oxygen atmosphere with the nitrogen generators for long periods.”

“I would not hesitate to recommend a rental solution from Atlas Copco to other plants with the same needs,” stated Carqueja.


CCGT power station at-a-glance

The CCGT power station has three groups of turbo generators, producing electric power from natural gas. The gas is burned in a gas turbine, which is similar in operation to an airplane turbine.

The gas from the exhaust, which is extremely hot, goes into the steam generator like a steam boiler, heating the water and transforming it into super-heated vapour. The vapour is then used to engage another turbine similar those used in coal thermoplants.

An alternator is then driven by both turbines, gas and vapour, creating power.