Centrifugal pump

Abstract

A centrifugal pump for conveying a process fluid, includes a pump unit, a drive unit to drive the pump unit, a pump inlet to receive the process fluid, a pump outlet to discharge the process fluid. The pump unit includes an impeller configured to convey the process fluid from the pump inlet to the pump outlet, and a pump shaft, on which the impeller is mounted. The drive unit includes a drive shaft to drive the pump shaft, and an electric motor to rotate the drive shaft about an axial direction. A plurality of bearings is configured to support the pump shaft and the drive shaft, and a hydrodynamic coupling has a casing and is configured to hydrodynamically couple the drive shaft to the pump shaft by a transmission fluid. At least one of the plurality of bearings is arranged in the casing of the hydrodynamic coupling.

What is claimed: 
     
         1 . A centrifugal pump for conveying a process fluid, comprising:
 a pump unit;   a drive unit configured to drive the pump unit;   a pump inlet configured to receive the process fluid;   a pump outlet configured to discharge the process fluid,   
       the pump unit comprising at least one impeller configured to convey the process fluid from the pump inlet to the pump outlet, and a pump shaft, on which each impeller is mounted, the drive unit comprising a drive shaft configured to drive the pump shaft, and an electric motor configured to rotate the drive shaft about an axial direction;
 a plurality of bearings configured to support the pump shaft and the drive shaft; and 
 
       a hydrodynamic coupling having a casing and configured to hydrodynamically couple the drive shaft to the pump shaft by a transmission fluid, 
       at least one of the plurality of bearings is arranged in the casing of the hydrodynamic coupling. 
     
     
         2 . The pump in accordance with  claim 1 , the hydrodynamic coupling comprises a pump wheel connected to the drive shaft, a turbine wheel connected to the pump shaft, and a stator arranged between the pump wheel and the turbine wheel configured to guide the transmission fluid. 
     
     
         3 . The pump in accordance with  claim 1 , wherein the plurality of bearings comprises a first radial pump bearing configured to support the pump shaft, the first radial pump bearing is arranged between the pump unit and a drive end of the pump shaft, and the first radial pump bearing is arranged in the casing of the hydrodynamic coupling. 
     
     
         4 . The pump in accordance with  claim 1 , wherein the plurality of bearings comprises a first radial drive bearing configured to support the drive shaft, the first radial drive bearing is arranged between the pump unit and the electric motor, and the first radial drive bearing is arranged in the casing of the hydrodynamic coupling. 
     
     
         5 . The pump in accordance with  claim 1 , wherein the pump is a process fluid lubricated pump, and includes a common housing, the pump unit and the drive unit are arranged in the common housing, and the plurality of bearings is configured to receive the process fluid as lubricant and coolant. 
     
     
         6 . The pump in accordance with  claim 1 , wherein the hydrodynamic coupling is configured to receive the process fluid as the transmission fluid. 
     
     
         7 . The pump in accordance with  claim 1 , wherein the pump is a seal-less pump without a mechanical seal. 
     
     
         8 . The pump in accordance with  claim 1 , further comprising a balance line configured to recirculate the process fluid from a high pressure side to a low pressure side of the pump. 
     
     
         9 . The pump in accordance with  claim 1 , wherein the process fluid is configured to pass through and cool the electric motor. 
     
     
         10 . The pump in accordance with  claim 8 , wherein the balance line is arranged and configured to receive the process fluid discharged from the drive unit. 
     
     
         11 . The pump in accordance with  claim 5 , further comprising an external cooling loop configured to cool and lubricate the drive unit and the plurality of bearings, the external cooling loop comprising a heat exchanger configured to cool the process fluid, the heat exchanger is arranged outside the common housing and configured to receive the process fluid from the common housing and to recirculate the process fluid to the common housing. 
     
     
         12 . The pump in accordance with  claim 1 , wherein the pump unit comprises an intermediate take-off connected to a cooling loop, the intermediate take-off configured to supply the process fluid to the cooling loop with a pressure that is larger than a pressure of the process fluid at the pump inlet, and the cooling loop is configured to supply process fluid to at least one bearing of the plurality of bearings or to the drive unit. 
     
     
         13 . The pump in accordance with  claim 1 , further comprising at least one balance drum or center bush or throttle bush fixedly connected to the pump shaft and defining a front side facing the pump unit and a back side, and further comprising a relief passage, between the balance drum and a stationary part stationary with respect to the common housing, the relief passage is extending in axial direction along the balance drum from the front side to the back side. 
     
     
         14 . The pump in accordance with  claim 1 , wherein the pump is a vertical pump with the pump shaft extending in the direction of gravity, and the drive unit is arranged on top of the pump unit. 
     
     
         15 . The pump in accordance with  claim 1 , wherein the pump is configured to be installed on a sea ground. 
     
     
         16 . The pump in accordance with  claim 15 , wherein the pump is a water injection pump configured to inject seawater into a subterranean region