Performance Study of Cryogenic Turboexpander Using Gas Foil
Bearing

Abstract

Due to industrialisation these days every industry increases the use of liquid nitrogen, liquid helium, liquid oxygen and argon exponentially. For liquefaction of above gases cryogenic process is used. And turbo expander is the heart of the cryogenic plant as heart is the most vital part of the human body same in the cryogenic plant turbo expander play the role. It also called rotating expansion device. In cryogenic plant reciprocating expander can be used but it is not efficient then rotary and also less reliable. Due to the lake of native technology India couldn’t reach to the up to the mark in cryogenic technology. So for this India depend upon the other country so for not to depend upon other country NIT Rourkela made two turbo expander.it will be tested by using gas foil bearing. The turbo expander rotates with very high speed around 1 lakhs RPM, any sort of imbalance creates problem. And the turbo expander normally used in cryo plant. So to support the shaft both the journal and thrust bearing is used. but normal bearing cannot handle this much of rpm, for this situation gas foil bearing is the best option. Gas foil bearing works self-adjusted the shaft due to its damping action of the bump foil. And this bearing is also self-lubricated. This bearing consists of three-part bump foil, top foil, and the bearing sleeve. The main part of this bearing is the bump foil. It made up of phosphor bronze material as this material has a good damping characteristic. And to giving some static stiffness it converted to a bump structure. By forming operation this bump foil is fabricated. There 2 methods are adopted for fabrication of the bump foil and compare the results. Same fabrication methodology is adopted for both journal and thrust bearing. For fabrication 2 sets of die are used, for one method both die is rigid and for another method one is rigid and another is flexible. By giving the forming load bump is fabricated and calculated its stiffness, spring back and compare the result. As the height of bump is 0.6 mm and the foil thickness also 0.1 mm. so here the fabrication process deal in micron level and the height a major role so precision and accuracy in dimension should be maintained.