Qatargas LNG Uses Siemens VFD Drives

Siemens Energy and Automation recently participated in the successful completion of a liquefied natural gas (LNG) compressor train for the Qatargas 2 project. The LNG train uses Siemens Perfect Harmony Variable Frequency Drives (VFD). Siemens Perfect Harmony 45-megawatt Variable Frequency Drives are used on the main refrigerant compressors in the train.

Siemens director of project systems Huw Carey explained how Siemens variable frequency drives play a key role in the gas liquefaction process. “The variable frequency drives start a motor generator that powers the gas turbines and gas compressors used to process the gas for transport.”

In addition to starting the gas turbines, Siemens variable frequency drives also help the gas turbines run more efficiently while the train is operating. 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 variable frequency 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 Siemens global team who worked on this project has helped create history in the LNG world by designing, developing and commissioning critical equipment for this application,” said Anne Cooney, vice president of the Power Conversion Division, Siemens Energy & Automation. “This five-year project is a historic milestone for Qatargas, our project team and Siemens employees in the United States and around the world.”