Session: 25-07 Bearings and Dampers

Paper Number: 82332

82332 - Field Testing and Operation of a 300 kW Active Magnetic Bearing Supported Turboexpander-Generator for Natural Gas Pressure Letdown 

A 300 kW turboexpander-generator was developed by Baker Hughes, in conjunction with Calnetix Technologies, for use in a natural gas pressure letdown application.  A prior technical publication [1] describes the synchronous permanent magnet generator design and presented some preliminary test data from the prototype unit.  In this paper, the machine design, including rotordynamics and active magnetic bearing (AMB) system design, are reviewed.  Unbalance response measurements made during a standard mechanical running test at the manufacturer’s facility are shown, including comparisons to predictions made using API 617 guidelines.  Turboexpander and generator operating data collected from the initial field installation in Bologna, Italy are then covered in detail.  Field data presented includes aerodynamic performance data, closed-loop AMB transfer functions, and plant transfer functions at various power levels, vibration data from spin testing, backup bearing clearance measurements made using the magnetic bearings, thrust load vs. power curves, and generator efficiency at various power levels.  The measurements made in the field confirm that the turboexpander-generator meets all customer requirements.  As of 2020, the machine is operating in parallel with a legacy Joule-Thomson valve.  A future technical paper will discuss results coming from a series of shutdown tests performed on the machine under various shutdown scenarios.

Presenting Author: Rasish Khatri Calnetix Technologies

Presenting Author Biography: Rasish Khatri is the Manager of Rotordynamics and Magnetic Bearing Controls at Calnetix Technologies in Cerritos, CA. He has been with Calnetix for 10 years, serving in various roles within the Magnetic Bearings group. Previously, he has worked as a Systems Engineer at Dresser-Rand in the Synchrony Magnetic Bearings Business Unit. He has 12 years of experience working in the field of magnetic bearings, rotordynamics, and controls, including extensive experience with design, integration, and commissioning. Rasish completed his Master’s degree in Mechanical Engineer with the Texas A&M University Turbomachinery Laboratory, specializing in rotordynamics and bearings.

Authors:

Rasish Khatri Calnetix Technologies
Larry Hawkins Calnetix Technologies
Jeremy Liu Sapphire Technologies
Massimiliano Ortiz Neri Baker Hughes
Davide Biliotti Baker Hughes
Francesco Cangioli Baker Hughes