Centrifugal pump
A centrifugal pump includes a housing including a pump inlet and a pump outlet, a rotor arranged in the housing, and including an impeller to convey fluid from the inlet to the outlet and a pump shaft extending from a first end to a second end, the impeller fixedly connected to the pump shaft, a balance disk fixedly connected to the first end of the pump shaft and cooperating with a stationary counter ring, to provide a radial gap between the balance disk and the counter ring, so that a movement of the pump shaft in the axial direction closes or opens the radial gap, and a balance drum fixedly connected to the pump shaft adjacent the second end of the pump shaft and cooperating with a stationary counterpart to provide an axial gap between the balance drum and the counterpart.
1 . A centrifugal pump comprising:
a housing comprising a pump inlet configured to receive a fluid at a suction pressure and a pump outlet configured to discharge the fluid at a discharge pressure;
a rotor arranged in the housing, and comprising an impeller configured to convey the fluid from the inlet to the outlet and a pump shaft to rotate about an axial direction, with the pump shaft extending from a first end to a second end, the impeller fixedly connected to the pump shaft;
a balance disk fixedly connected to the first end of the pump shaft and configured to cooperate with a stationary counter ring, to provide a first gap extending in a radial direction and disposed in the axial direction between the balance disk and the counter ring, so that a movement of the pump shaft in the axial direction closes or opens the first gap; and
a balance drum fixedly connected to the pump shaft adjacent the second end of the pump shaft and configured to cooperate with a stationary counterpart to provide a second gap extending in the axial direction axially disposed between the balance drum and the stationary counterpart.
2 . The centrifugal pump in accordance with claim 1 , wherein the first end of the pump shaft is configured as a non-drive end, and the second end of the pump shaft is configured as a drive end of the pump shaft.
3 . The centrifugal pump in accordance with claim 1 , wherein the pump inlet is arranged at the first end of the pump shaft, and the pump outlet is arranged at the second end of the pump shaft.
4 . The centrifugal pump in accordance with claim 1 , wherein the balance drum has a high-pressure side and a low-pressure side, a cavity is arranged at the low-pressure side, and a balance line provides a fluid connection between the cavity and the pump inlet, so that a pressure in the cavity is the suction pressure.
5 . The centrifugal pump in accordance with claim 1 ,
wherein the balance drum and the stationary counterpart are configured to provide an axial counterthrust directed opposite to an axial thrust generated by the impeller, and a diameter of the balance drum is selected such that the axial counterthrust is smaller than the axial thrust generated by the impeller.
6 . The centrifugal pump in accordance with claim 1 , wherein the balance disk comprises an axial face, delimiting a chamber and a transfer line is provided to supply the fluid to the chamber with a pressure higher than the suction pressure.
7 . The centrifugal pump in accordance with claim 6 , wherein the transfer line is connected to a high-pressure side of the balance drum.
8 . The centrifugal pump in accordance with claim 6 , further comprising a throttle to adjust the flow of the fluid supplied to the chamber.
9 . The centrifugal pump in accordance with claim 1 , wherein a rotating bushing is fixed at the first end of the pump shaft and a stationary bushing is arranged to surround the rotating bushing, the rotating bushing and the stationary bushing forming a radial bearing lubricated by the fluid.
10 . The centrifugal pump in accordance with claim 9 , wherein the radial bearing at the first end of the pump shaft is in fluid communication with the pump inlet.
11 . The centrifugal pump in accordance with claim 1 , wherein the balance drum and the stationary counterpart function as a product lubricated radial bearing.
12 . The centrifugal pump in accordance with claim 11 , wherein the balance drum and the stationary counterpart are the sole radial bearing at the second end of the pump shaft.
13 . The centrifugal pump in accordance with claim 1 ,
wherein a mechanical seal to seal the pump shaft is arranged between the balance drum and the second end of the pump shaft.
14 . The centrifugal pump in accordance with claim 1 , wherein the stationary counterpart of the balance drum comprises a bushing surrounding the balance drum.
15 . The centrifugal pump in accordance with claim 1 , wherein a stationary inboard counter ring is configured to cooperate with the balance disk to provide an inboard radial gap between the balance disk and the inboard counter ring, so that the movement of the pump shaft in the axial direction closes or opens the inboard radial gap.