Siemens completes world's largest LNG train, raises Qatar output to 77mn tonnes/year
Siemens said it has successfully completed the world’s largest onshore liquefied natural gas (LNG) compressor “mega-train” for Qatargas in the Middle Eastern country of Qatar.
The last of the 72 Siemens drives was installed and brought online, the company said over the weekend.
Qatar sits atop the world’s third largest gas reserves, and these new LNG projects have allowed the country to raise its overall LNG production capacity to 77mn tonnes/year, thereby meeting the demands of global LNG buyers.
In addition to the 72 ROBICON drives, the Siemens supply also included 72 VFD control houses and four 33KV switchgear, the company said. The first order for the initial 12 drives was placed in 2004.
The project, located in Ras Laffan Industrial City, was five years in the making. “The culmination of this project is monumental, as it has involved the hard work and dedication from hundreds of Siemens’ team members across dozens of countries,” says Doug Keith, president of the drive technologies division for Siemens.
According to Agnes Armstrong, manager of the Qatar LNG projects, the massive scale of the series of projects, in addition to the number of partners that worked toward its completion, demonstrated a teamwork approach.
“Our team continually worked with Qatargas to meet the customer quality and safety requirements, resulting in a job well done,” says Armstrong.
The Siemens 45-megawatt VFDs, manufactured in New Kensington, Pennsylvania, are being used on the main refrigerant compressors (MR, C3 & N2 strings) in the mega LNG train. These drives play a key role in the gas liquefaction process, the company said, allowing natural gas to be liquefied then transported to waiting tankers in the Persian Gulf.
The variable frequency drives control the speed/torque of large 45Megawatt motors/generators used for starting the gas turbines and gas compressors strings. In addition to starting the gas turbines, Siemens’ ROBICON variable frequency drives also help the gas turbines run more efficiently while the train is operating during high ambient temperatures. The quantity of power generated by the gas turbines is dependent on the air temperature.
During the winter when the air is cool, the gas turbine can, at times, generate more power than the compressors need. The Siemens drives are able to direct this excess energy via the motor (acting as a generator) back to the electrical grid to improve overall energy use, the company said.
To counter hot temperatures during the summer, these variable frequency drives can provide up to 45 megawatts of additional power to the compressor train to keep operations running smoothly.
Siemens drives were also selected for the project because of their high reliability.
These drives also have the best electrical waveforms on the market, providing superior smooth rotational performance of the compressor and the highest waveform quality into the Qatar electrical grid system. That can reduce the harmonic distortion that can negatively affect electrical grid performance, the company said.
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