Pump system

Abstract

A pump system comprises a longitudinal axis and a plurality of pump stages. Each pump stage comprises a rotary component rotatable about the longitudinal axis, a fluid inlet, a fluid outlet, and a main fluid flow path for fluid to flow from the fluid inlet to the fluid outlet. The rotary component extends radially into the main fluid flow path and is drivable to rotate about the longitudinal axis so as to impart a force to fluid in the main flow path. The rotary component of each of the plurality of pump stages is separately drivable so as to be able to rotate at a different speed from the rotary components of the other pump stages. The pump system further comprises a cooling passage, where the first pump stage is configured to pump fluid through the cooling passage to deliver the fluid to the other pump.

1 . A pump system comprising:
 a longitudinal axis; and.   a plurality of pump stages, wherein each pump stage comprises:
 a rotary component mounted for rotation about the longitudinal axis; 
 a fluid inlet; 
 a fluid outlet; and, 
 a main fluid flow path for fluid to flow from the fluid inlet to the fluid outlet, the rotary component extending radially into the main fluid flow path and being drivable to rotate about the longitudinal axis so as to impart a force to fluid in the main flow path, 
   wherein the rotary component of each of the plurality of pump stages is separately drivable so as to be able to rotate at a different speed from the rotary components of the other pump stages, the pump system further comprising a cooling passage,   wherein a first pump stage of the plurality of pump stages is configured to pump fluid through the cooling passage,   wherein the cooling passage is configured to deliver the fluid to the other pump stages of the plurality of pump stages,   wherein the cooling passage is separate from the main fluid flow path of each of the other pump stages of the plurality of pump stages.   
     
     
         2 . The pump system as claimed in  claim 1 , wherein the plurality of pump stages form or are located within a housing, wherein the housing is sealed from an external environment. 
     
     
         3 . The pump system as claimed in  claim 2 , wherein the pressure internal to the housing is different than that of the external environment. 
     
     
         4 . The pump system as claimed in  claim 1 , further comprising a variable speed drive for driving the rotary components of the plurality of pump stages, wherein the cooling passage is configured to deliver the fluid to the variable speed drive. 
     
     
         5 . The pump system as claimed in  claim 4 , wherein the variable speed drive is located outside the housing. 
     
     
         6 . The pump system as claimed in  claim 1 , further comprising a heat exchanger for cooling the fluid in the cooling passage. 
     
     
         7 . The pump system as claimed in  claim 1 , wherein each pump stage comprises one or more bearings for mounting the rotary component for rotation about the longitudinal axis, wherein the pump system further comprises a further cooling channel configured for cooling the bearings in one or more of the pump stages, wherein the further cooling channel is fluidly connected to the cooling passage so as to supply the fluid to the further cooling channel. 
     
     
         8 . The pump system as claimed in  claim 7 , wherein the one or more bearings include a radial bearing located radially outward of the longitudinal axis, and wherein the further cooling channel comprises a first further cooling channel extending in an axial direction between the radial bearing of at least one of the pump stages and the longitudinal axis. 
     
     
         9 . The pump system as claimed in  claim 8 , wherein the one or more bearings further include an axial bearing extending radially outwardly from the radial bearing, and wherein the further cooling channel further comprises at least one further annular cooling channel extending radially outward from and around the first further cooling channel, the further annular cooling channel being positioned to allow cooling of the axial bearing of at least one of the pump stages. 
     
     
         10 . The pump system as claimed in  claim 9 , further comprising a connecting channel configured to deliver fluid from the first further cooling channel to the further annular cooling channel before re-entering the first further cooling channel. 
     
     
         11 . The pump system as claimed in  claim 1 , wherein the cooling passage forms a closed loop so as to deliver the fluid back to the fluid inlet of the first pump stage, or wherein the cooling passage is configured to expel fluid to an external environment after it has passed through the cooling passage from the first pump stage. 
     
     
         12 . The pump system as claimed in  claim 1 , wherein each pump stage further comprises:
 power features for driving rotation of the rotary component; and,   a cooling arrangement for cooling the power features, wherein the cooling passage is configured to supply the fluid to the cooling arrangement in at least one pump stage.   
     
     
         13 . The pump system as claimed in  claim 1 , wherein the fluid outlet of the first pump stage is fluidly connected to the cooling passage such that the first pump stage is configured to supply the fluid to the cooling passage, wherein the fluid outlet of the first pump stage is fluidly isolated from the main flow paths of the other pump stages of the plurality of pump stages, and wherein the other pump stages of the plurality of pump stages are arranged for sequential flow of a process fluid there-through from the fluid inlet of one of the other pump stages to the fluid outlet of one of the other pump stages. 
     
     
         14 . The pump system as claimed in  claims 1 , wherein the plurality of pump stages are arranged for sequential flow of the fluid there-through from the fluid inlet of the first pump stage to the fluid outlet of one of the other pump stages. 
     
     
         15 . The pump system as claimed in  claim 14 , wherein the fluid outlet of the first pump stage is fluidly connected to the cooling passage such that the first pump stage is configured to supply the fluid to the cooling passage, and wherein the fluid outlet of the first pump stage is fluidly connected to the main flow paths of the other pump stages of the plurality of pump stages.