GAS BEARING TURBOEXPANDERS FOR SHIPBOARD NITROGEN/OXYGEN LIQUEFIERS

SHIPBOARD LIQUEFIERS IN USE BY THE NAVY FOR PRODUCING LIQUID OXYGEN AND LIQUID NITROGEN EMPLOY HIGH-SPEED TURBOEXPANDERS WITH OILLUBRICATED BEARINGS. MECHANICAL SHAFT SEALS WITH BUFFER GAS STAGES ARE USED IN THESE MACHINES TO PREVENT CONTAMINATION OF THE SYSTEM BY THE LUBRICANT. SUCCESSFUL CONTINUOUS OPERATION OF THE TURBOEXPANDERS,AND THE LIQUEFIER SYSTEM AS A WHOLE, DEPENDS UPON THE INTEGRITY OF THE TURBOEXPANDER SHAFT SEALS, AND ON THE RELIABILITY OF THE OIL LUBRICATION PUMP AND FILTERING SYSTEM. OIL CONTAMINATION FROM LEAKINGSEALS, OR INTERRUPTION OF THE TURBOEXPANDER BEARING OIL SUPPLY RESULTS IN EXTENSIVE SYSTEM DOWNTIME AND RELATED HIGH MAINTENANCE COSTS.THE NAVY NEEDS AN ALTERNATIVE TURBOEXPANDER DESIGN WHICH IS HIGHLY RELIABLE IN OPERATION, AND WHICH WILL ELIMINATE THE POTENTIAL FOR CONTAMINATION OF THE PRODUCT GASES INHERENT IN THE PRESENT HARDWARE. THIS PROPOSAL DESCRIBES PHASE I OF A PROJECT TO DEVELOP A TURBOEXPANDER OPERATING IN GAS BEARINGS FOR SHIPBOARD LIQUEFIERS. PHASE I CONSISTS OF ESTABLISHING SPECIFICATIONS FOR THE TURBOEXPANDER, DESIGNING A SHAFT/GAS-BEARING SYSTEM WHICH WILL MEET THESE SPECIFICATIONS AND PRODUCING A PRELIMINARY DESIGN OF THE TURBOEXPANDER.