PROJECTS  Development of Active Damper for LNG Compressors Train

Modern plants for LNG production (Liquefied Natural Gas) are making use of multiple compressors connected in series (same shaft) for the refrigeration and liquefaction of the natural gas. The compressor train is usually driven by a gas turbine and/or VFD fed electric motor. One of the main problems associated with long shaft trains, especially ones with VFD, is the phenomena of torsional resonance which can lead to high cyclic torques in the train shaft leading to premature failure of the mechanical components, reduced reliability and undesired plant shutdown. 
Usually, a conventional mechanical damping (friction/hysteresis based) is used to damp the torque ripples. However, those methods considerably reduce the energetic efficiency of the system. A2Z Consulting ltd. team developed and patented a novel, observer based control method for active damping of those torque ripples. The same VFD driving the electric motor is used to inject counter phase torque harmonies, effectively reducing torque ripple while keeping high system efficiency.