LNG 펌프용 깊은 홈 구름 베어링 시험장치: 동역학적 안정성 평가

Abstract

The ball bearings used to support the shaft of LNG pumps are nonstandard bearings. The bearings operate in the cryogenic environment(-162°C) and they are a type of self-lubricated ball bearing using solid lubricant and have larger internal clearance grade than general standard bearings. The defect in ball bearings is the most common failure cause of LNG pumps. In order to ensure the stable operation of LNG pumps, it is important to optimize the design of bearings with the performance evaluation test and reliability test that ensure fatigue life is also needed. In this paper, the tribo-test apparatus was developed for the performance test and reliability test. This test apparatus is designed to evaluate the performance by measuring friction torque and cage orbit of test bearings. Prior to the perform the ball bearing test, the verification test of the test apparatus was done by operating for about 4 hours with the LN2(-189°C) submerged chamber. The stability of the rotor system(motor to shaft) was monitored with the motor input current. The relation between motor input current and torque was confirmed by the test. After the verification of the test apparatus, the performance test of a ball bearing was performed. As we verified, the rotor system was stable and friction torque and cage whirling orbit was measured properly. From these results, we can expect that this apparatus would be helpful in developing the process of ball bearings used in LNG pumps.