Multiphase screw pump

Abstract

A twin screw pump includes a pair of rotors disposed inside a casing having an inlet and an outlet. Each rotor includes a set of threads disposed on a portion of an outer surface of a shaft. A first bearing is coupled at a first end of the shaft and a second bearing is coupled at a second end of the shaft. The first and second bearings are not separated by one or more seals. The first and second bearings are configured for being lubricated by the liquid medium of the process fluid when the twin screw pump is in an operational mode.

1 . A twin screw pump configured to transfer a process fluid having a liquid medium and a gaseous medium, the pump comprising:
 a casing comprising an inlet and an outlet; and   a pair of rotors disposed inside the casing, each rotor comprising a shaft, a set of threads disposed on a portion of an outer surface of the shaft, a first bearing coupled at a first end of the shaft; and a second bearing coupled at a second end of the shaft,   wherein the first and second bearings are not separated from each other by a seal,   wherein the first and second bearings are configured for being lubricated by the process fluid when the twin screw pump is in an operational mode.   
   
   
       2 . The pump of  claim 1 , wherein the first and second bearings comprise journal bearings. 
   
   
       3 . The pump of  claim 1 , wherein the first and second bearings comprise tilt pads comprising cemented tungsten carbide, ceramic matrix composite, or monolithic ceramic. 
   
   
       4 . The pump of  claim 1 , wherein the first and second bearings comprise sleeves comprising cemented tungsten carbide, ceramic matrix composite, or monolithic ceramic. 
   
   
       5 . The pump of  claim 1 , wherein the first and second bearings are located within the casing. 
   
   
       6 . The pump of  claim 1 , wherein the liquid medium comprises water. 
   
   
       7 . The pump of  claim 1 , wherein the liquid medium comprises oil. 
   
   
       8 . A twin screw pump configured to transfer a multi-phase fluid medium having a liquid medium and a gaseous medium, the pump comprising:
 a casing comprising an inlet and an outlet;   a pair of rotors disposed inside the casing, each rotor comprising a shaft, a set of threads disposed on a portion of an outer surface of the shaft, a first bearing coupled at a first end of the shaft; and a second bearing coupled at a second end of the shaft, wherein the first and second bearings are not separated by a seal, and   a separating unit configured to receive the multi-phase fluid medium and separate the liquid medium from the gaseous medium;   wherein the first and second bearings are configured for being lubricated by the liquid medium when the twin screw pump is in an operational mode.   
   
   
       9 . The pump of  claim 8 , wherein the separating unit is configured to store a predetermined reserve quantity of liquid medium to compensate for an operating condition in which an amount of liquid medium in the multi-phase fluid medium is less than a predetermined quantity. 
   
   
       10 . The pump of  claim 9 , wherein the separating unit is configured to discharge the gaseous medium and excess liquid medium at a boosted pressure from the separating unit. 
   
   
       11 . The pump of  claim 8 , further comprising one or more flow control orifices, and/or auxiliary pumps; wherein the separating unit is configured to transfer the liquid medium to the casing via the flow control orifices and/or auxiliary pumps. 
   
   
       12 . The pump of  claim 8 , further comprising one or more timing gears coupled to the shaft of each rotor; wherein the one or more timing gears are configured for being lubricated by the liquid medium when the twin screw pump is in an operational mode. 
   
   
       13 . The pump of  claim 12 , wherein the timing gears comprises cemented tungsten carbide, ceramic matrix composite, or monolithic ceramic. 
   
   
       14 . A system configured to transfer a process fluid, the system comprising:
 a motor;   a pump coupled to the motor and configured to be driven by the motor, the pump comprising a casing comprising an inlet and an outlet; and a pair of rotors disposed inside the casing; each rotor comprising a shaft, a set of threads disposed on a portion of an outer surface of the shaft, a first bearing coupled at a first end of the shaft, a second bearing coupled at a second end of the shaft, and   a single seal coupled to a shaft of one of the rotor,   wherein the seal is configured to prevent the flow of process fluid into the motor.   
   
   
       15 . The pump of  claim 14 , wherein the first and second bearings comprise sleeves comprising cemented tungsten carbide, ceramic matrix composite, or monolithic ceramic. 
   
   
       16 . The pump of  claim 14 , wherein the first and second bearings comprise tilt pads comprising cemented tungsten carbide, ceramic matrix composite, or monolithic ceramic. 
   
   
       17 . The pump of  claim 14 , wherein the first and second bearings are located within the casing. 
   
   
       18 . A twin screw pump configured to transfer a process fluid, the pump comprising:
 a casing comprising an inlet and an outlet; and   a pair of rotors disposed inside the casing; each rotor comprising   a shaft;   a set of threads disposed on a portion of an outer surface of the shaft;   a first bearing coupled at a first end of the shaft;   a second bearing coupled at a second end of shaft, wherein the first and second bearings comprises ceramic composite bearings; and   a single seal coupled to a shaft of one of the rotors,   wherein the seal is configured to prevent the flow of process fluid into the motor.   
   
   
       19 . The pump of  claim 18 , wherein the first and second bearings comprise sleeves comprising cemented tungsten carbide, ceramic matrix composite, or monolithic ceramic. 
   
   
       20 . The pump of  claim 18 , wherein the first and second bearings comprise tilt pads comprising cemented tungsten carbide, ceramic matrix composite, or monolithic ceramic. 
   
   
       21 . The pump of  claim 18 , wherein the first and the second bearings are located within the casing.