| 摘要 |
Electric motor driven pump units, especially suited for pumping liquefied gases, including cryogenic fluids, which are lubricated, cooled and balanced with small amounts of fluid pumped by the unit (pumpage), such as 1 to 3 percent of the designed flow capacity of the pump. These small amounts of pumpage are divided into a major flow path through the most heated portions of the units discharging on the pressure side of the pump and a minor flow path through a thrust bearing for the unit and then through the lesser heated portions to discharge on the intake side of the pump. The major flow path, receiving about 75 percent of the lubricating pumpage, is downwardly through the motor shaft radial bearings and rotor compartment to an impeller and a pumping or collection chamber. The minor flow path, receiving about 25 percent of the lubricating pumpage, is through variable thrust bearing orifices tending to raise the motor shaft and carry the axial load of the unit on a thin film discharging through the hollow interior of the shaft to the pump inlet. The pumpage in the major flow path is maintained under pressure and will not boil even when appreciably heated. The minor flow path picks up very little heat and is primarily for balancing the axial thrust load on the shaft.
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