A shaft of a compressor may include a first shaft section defining a first cavity axially extending therein and a second shaft section defining a second cavity axially extending therein. A plurality of inlet holes may be defined on an outer surface of the first shaft section, and a plurality of outlet holes may be defined on an outer surface of the second shaft section. The plurality of inlet holes may be in fluid communication with the first cavity and the plurality of outlet holes may be in fluid communication with the second cavity. The first cavity and the second cavity may form a passageway fluidly coupling the plurality of inlet holes and the plurality of outlet holes.

A turbo compressor assembly of a cooling machine has a shaft mounted in a common housing with first and second radial dynamic gas bearings and a thrust bearing. A supply stream of working gas supplied to the first radial bearing is formed between an inner wall of a compressor body and the shaft, and a supply stream of working gas from a turbo expander supplied to the second radial bearing and to the thrust bearing is formed between an inner wall of a turboexpander body and the shaft. The first radial dynamic gas bearing is sealed towards the electric motor rotor by a shaft seal. A surface in a shape of an annulus is formed on the shaft between the first radial bearing and the shaft seal, the annulus perpendicular to an axis of the shaft and functioning as a piston for balancing an axial force acting on the shaft.

A pump (110) is disclosed comprising: an inlet (114) being in fluid communication with an inlet cavity (115); an outlet (118) being in fluid communication with an outlet cavity (119); a motor (120) being arranged in a motor cavity (121); a pump axis (122) being rotatably drivable by the motor; impellers (124) being positioned between the inlet cavity and the outlet cavity and being actuatable by the pump axis to cause a differential pressure across the inlet cavity and the outlet cavity; and a balance arrangement (126) configured to at least partially offset an axial thrust affected upon the axis by the impellers when the pump is in operation, the balance arrangement comprising: a balance cavity (132); a balance drum (128) arranged between the outlet cavity and the balance cavity; and a balance line (134) extending between and fluidly connecting the balance cavity and the inlet cavity. The inlet is in fluid communication with the inlet cavity via the balance cavity and the balance line. A related method is also disclosed.

A fluid transport device defining a centerline axis therethrough includes at least one rotatable member including a first portion and a second portion axially opposite the first portion. The fluid transport device also includes at least one stationary member positioned proximate the at least one rotatable member. The at least one rotatable member and the at least one stationary member define at least one stage. The at least one rotatable member defines at least one pressure balance port extending from the second portion to the first portion. The at least one pressure balance port is configured to substantially equalize a fluid pressure proximate the second portion with a pressure of a fluid proximate the first portion.

A pump (110) is disclosed comprising: an inlet (114) being in fluid communication with an inlet cavity (115); an outlet (118) being in fluid communication with an outlet cavity (119); a motor (120) being arranged in a motor cavity (121); a pump axis (122) being rotatably drivable by the motor: impellers (124) being positioned between the inlet cavity and the outlet cavity and being actuatable by the pump axis to cause a differential pressure across the inlet cavity and the outlet cavity; and a balance arrangement (126) configured to at least partially offset an axial thrust affected upon the axis by the impellers when the pump is in operation, the balance arrangement comprising: a balance cavity (132); a balance drum (128) arranged between the outlet cavity and the balance cavity; and a balance line (134) extending between and fluidly connecting the balance cavity and the inlet cavity. The inlet is in fluid communication with the inlet cavity via the balance cavity and the balance line. A related method is also disclosed.

A multistage centrifugal pump (1) has impellers (9) arranged on a common shaft (8), which is rotatably arranged within a pump casing (2-4). One end of the shaft (8) is led out of the casing (2-4) for connection to a drive motor and another shaft end (15) is rotatably mounted in the pump casing (2-4). The shaft end (15) which is mounted within the pump casing (2-4) is subjected to a counter-force which is produced by way of pressure subjection via a conduit connection to a delivery side of the pump. An axial seal (11) is provided on the shaft end (15) arranged within the pump casing (2-4). The rotating part of the axial seal is led on the shaft end and the non-rotating part is led, axially movably, within the pump casing (2-4). A sealing arrangement is provided between the pump casing and the axially movably mounted part.

The axial reaction force generated by a subsea pump or compressor is partially counteracted by a pressure differential in a barrier fluid across a thrust element. The pressure differential is created using impellers or other structures on the thrust element that increases the barrier fluid pressure on one side of the thrust element when the main shaft of the pump or compressor is rotated. The pressure differential across the thrust element partially offloads the bearing surface of the thrust element.

A pump includes a housing having an inlet and an outlet configured to convey fluid, an impeller configured to convey the fluid from the inlet to the outlet, the impeller being arranged on a rotatable shaft, and a balance drum configured to relieve axial thrust. The balance drum includes a rotor rotationally fixedly connected to the shaft, the rotor having a high and low pressure sides, a stator stationary with respect to the housing, a relief passage extending between the rotor and the stator from the high pressure side up to the low pressure side of the rotor, a return passage connecting the low pressure side of the rotor to the inlet. An intermediate passage opens into the relief passage between the high pressure side and the low pressure side of the rotor. A blocking member is configured to influence the flow through the intermediate passage.

A balance piston seal assembly for a balance piston of a compressor is provided. The balance piston seal assembly may include a balance piston seal configured to be disposed about the balance piston such that an inner radial surface of the balance piston seal and an outer radial surface of the balance piston define a radial clearance therebetween. The balance piston seal assembly may also include a plurality of heaters in thermal communication with the balance piston seal and configured to heat and thermally expand the balance piston seal and thereby increase a radial length of the radial clearance.

A balance piston for a compressor is provided. The balance piston may include an annular body and a seal extending from an axial surface of the annular body. The annular body may be configured to be disposed about and coupled with a rotary shaft of the compressor. The seal may be configured to form a sealing engagement with at least one component of the compressor to prevent a flow of a process fluid from an impeller of the compressor to a seal cavity of the compressor.