Considerations for Making the Switch from Steam Turbines to Large Motor Drives for Ethylene Plants

In many locations, due to a motivation for decarbonization, emission reductions and the need for replacement of aging equipment, electric motors are being considered as replacements for steam turbine drives on the primary ethylene plant compressors. This paper will explore the considerations in switching from a steam turbine drive in terms of electric motor controls, motor starts / stops, variable frequency drive (VFD) sizing for motor starting, speed / torque curves and the possibility of compressor modifications (speed changes, rewheels
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, or rotor change-outs for higher efficiencies). This project relies on previous experiences as a supplier with large power (>20 MW) motor drive replacement projects worldwide at various ethylene / propylene refinery sites.