A Methodology for Fabrication of 2nd Generation Gas Foil Thrust and Journal Bearing For Turboexpander Used In Nitrogen Liquefier

Abstract

Oil free turboexpander is one of the most critical parts in large no of cryogenic gas process plants, and it operates at very high speed above 2x106 DN speed. Conventional liquid lubricated bearing cannot be used for such application because of short service life and issue of contamination. The alternative solution for such high-speed operation is gas bearings. Gas bearing using rigid geometry like tilting pad, spiral grooved gas bearing has been successfully developed indigenously, an attempt is made in the present research to develop a compliant surface gas foil thrust and gas foil journal bearing with excellent dynamic properties and possibilities of adaptation to changed conditions at very high speed or demanding operating conditions. This paper explains details fabrication methodology for die and punches for fabricating bump foils, bearing bases, assembly of foils and assembly of foil bearings with the rotor of the turboexpander. By providing the engineering community detailed steps of fabrication of gas foil thrust and journal bearing, the authors hope that the benefit and the true potential of this technology will be realized.