| 摘要 |
<p>A submersible pump system comprises a lowermost electrically driven pump unit (4,55) providing an inlet to the system for liquid to be pumped and one or more like pumps (5,55) positioned above it and connected in series. Electric power is supplied to the units by way of conductors within a central pipe (14) concentric with an outer cofferdam pipe (12), dielectric oil being circulated through the conductor pipe and between it and the cofferdam pipe and thus through the pump unit motors which have hollow drive shafts (21) around the conductor pipe. The pump stack may be located within a well casing (52), by sealing rings (62) expanded by the dielectric oil pressure, or surrounded by an outer load-bearing pipe (10). The liquid pumped flows externally of the pump stack and the system can be constructed in separate lengths which can be readily assembled on installation.</p> |
