Siemens Industry, Inc. has completed the world’s largest onshore liquefied natural gas (LNG) compressor “mega-train” for Qatargas. The last of the 72 Siemens ROBICON Perfect Harmony Variable Frequency Drives (VFD) has been installed and brought online. As Qatar holds the world’s third largest gas reserves, these new LNG projects have allowed the country to raise its overall LNG production capacity to 77 million tns/yr, meeting the demands of global LNG buyers. Located in Ras Laffan Industrial City, 50 mi north of Qatar’s capital, the project took five years to complete.
The Siemens ROBICON Perfect Harmony 45MW VFDs, manufactured in New Kensington, Pennsylvania, are being used on the main refrigerant compressors in the mega LNG train. These drives play a significant part in the gas liquefaction process, as they allow natural gas to be liquefied then transported to waiting tankers in the Persian Gulf. The variable frequency drives control the speed of the large 45MW motors used for starting the gas turbines and gas compressors strings. They also help the gas turbines run more efficiently while the train is operating during high ambient temperatures.
The amount 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 generate more power than the compressors need. The Siemens ROBICON Perfect Harmony variable frequency drives are capable of directing this excess energy via the motor, back to the electrical grid to improve overall energy use. At the same time, during the summer months, to counter hot temperatures the variable frequency drives can provide up to 45MW of additional power to the compressor train to keep operations running efficiently.
