Pressure booster with integrated speed drive

Abstract

Pressure booster (1) for boosting the pressure of petroleum fluids, produced water or seawater, comprising a pressure booster (2) with a motor (3), a rotatable motor shaft (4) and a rotatable pump or compressor shaft (5) where the pressure booster in the form of a centrifugal pump (2) or compressor is arranged. The pressure booster further comprises: a hydraulic variable speed drive (6) arranged between the motor and the pressure booster, the hydraulic variable speed drive comprising an impeller (7) and a turbine (8), wherein the impeller of the hydraulic variable speed drive is arranged on the motor shaft and the turbine of the hydraulic variable speed drive is arranged on the pump or compressor shaft, a common driver side fluid (10) for cooling, lubricating, flushing and powering of the hydraulic variable speed drive, and cooling, lubricating and flushing of the motor and bearings, circulated by one of an impeller (9) on the motor shaft, a pump and a hydraulic power unit, a control system (11) for controlling the coupling of the motor shaft to the pump or compressor shaft by the hydraulic variable speed drive, wherein the motor shaft drives the pump or compressor shaft via the hydraulic variable speed drive.

Claims

1. A pressure booster adapted to boost pressure of petroleum fluids, produced water or seawater, with the pressure booster submerged in sea, the pressure booster comprising: a motor; a pressure booster in the form of a centrifugal pump or a compressor; a rotatable motor shaft; and a pressure booster shaft; a coupling between the rotatable motor shaft and the pressure booster shaft, wherein the coupling consists of: a hydraulic variable speed drive arranged between the rotatable motor shaft and the pressure booster shaft with an impeller arranged on the rotatable motor shaft and a turbine arranged on the pressure booster shaft; a common driver side fluid configured for cooling, lubricating, flushing and powering of the hydraulic variable speed drive and cooling, lubricating and flushing of the motor and bearings; a control system adapted to control a coupling of the rotatable motor shaft to the pressure booster shaft by the hydraulic variable speed drive, wherein the rotatable motor shaft drives the pressure booster shaft via the hydraulic variable speed drive; a driver side impeller on the rotatable motor shaft that pressurizes the common driver side fluid to at least 5 bar overpressure, wherein the driver side impeller is configured to power an actuator system of the control system and power the hydraulic variable speed drive, further comprising: a common driver side compartment containing the motor and the hydraulic variable speed drive; a cooler for cooling the common driver side fluid, wherein the cooler is arranged outside the common driver side compartment; and wherein the cooler and inlet and outlet pipe sections to and from the cooler are the only structure outside the common driver side compartment to which the common driver side fluid is configured to flow, wherein the actuator system comprises a valve and a vane actuator, the common driver side fluid is supplied from the valve to and from the vane actuator, and further wherein the actuator system controls vane angle of a guide wheel.

2. A method for boosting the pressure of petroleum fluids, produced water or seawater, without an electric variable speed drive, the method consisting of: fluidly connecting the pressure booster according to claim 1 to an inlet for petroleum fluids, produced water or mixtures thereof, or seawater and an outlet for the petroleum fluids, produced water or seawater; connecting an electric power supply line; connecting a control link; operating the pressure booster by starting at no overpressure and then pressurizing the common driver side fluid, by the driver side impeller on the rotatable motor shaft, to power the actuator system of the control system and power the hydraulic variable speed drive in one of the separate motor housing and the common driver side compartment containing the motor and the hydraulic variable speed drive; and wherein the apparatus is controlled via an active closed-circuit control system integrated in the apparatus, controllable via the control link, wherein control is based on signals from transmitters for at least rotational speed of the pump or compressor shaft and the rotatable motor shaft, and vane angle of vanes of the hydraulic variable speed drive, and, if a process fluid to be pressure boosted is a multiphase fluid containing gas, torque on the pump or compressor shaft.

3. An apparatus for boosting pressure a process fluid, the apparatus consisting essentially of: a motor; a pressure booster in the form of a centrifugal pump or a compressor; a rotatable motor shaft; and a pressure booster shaft in the form of a centrifugal pump shaft or compressor shaft; a coupling between the rotatable motor shaft and the pressure booster shaft, the coupling consisting of: a hydraulic variable speed drive arranged between the rotatable motor shaft and the pressure booster shaft, the hydraulic variable speed drive comprising an impeller, a turbine, a guide wheel with vanes, and an actuator system comprising a valve and a vane actuator, the common driver side fluid is supplied from the valve to and from the vane actuator, and further wherein the actuator system controls an angle of the vanes, wherein the impeller of the hydraulic variable speed drive is arranged on the rotatable motor shaft and a turbine of the hydraulic variable speed drive is arranged on the centrifugal pump shaft or compressor shaft of the pressure booster; a common driver side fluid for cooling, lubricating, flushing and powering of the hydraulic variable speed drive and cooling, lubricating and flushing of the motor and bearings; a control system for controlling a coupling of the rotatable motor shaft to the pump or compressor shaft by the hydraulic variable speed drive, without any electric variable speed drive, wherein the rotatable motor shaft drives the centrifugal pump shaft or compressor shaft via the hydraulic variable speed drive; and a driver side impeller on the rotatable motor shaft that pressurizes the common driver side fluid, wherein the driver side impeller is configured to power an actuator system of the control system and power the hydraulic variable speed drive in one of a separate motor housing and a common driver side compartment containing the motor and the hydraulic variable speed drive, a cooler for cooling the common driver side fluid, arranged outside the motor housing or the common driver side compartment, fluidly coupled to the common driver side fluid; and wherein the cooler and inlet pipe to and outlet pipe from the cooler are the only structure outside the motor housing or the common driver side compartment to which flow of the common driver side fluid is configured to flow, wherein the common driver side fluid circulates in the apparatus only in the motor housing or the common driver side compartment and directly to and from the cooler.

4. The apparatus according to claim 3, wherein the impeller of the hydraulic variable speed drive is arranged directly on the motor shaft and the turbine is arranged directly on the centrifugal pump shaft or compressor shaft.

5. The apparatus according to claim 3, wherein, in addition to a process fluid inlet and a process fluid outlet, external connections consist of an electric power supply line and a control link.

6. The apparatus according to claim 3, wherein the motor and the hydraulic variable speed drive are arranged in the common driver side compartment isolated from the process fluid, wherein the hydraulic variable speed drive comprises a separation wall on a side of the hydraulic variable speed drive facing the motor or compressor, the separation wall isolates the common driver side compartment from the process fluid.

7. The apparatus according to claim 3, comprising internal lines, gaps, channels or external pipe sections for circulating the common driver side fluid internally in the motor housing and a hydraulic variable speed drive housing and between the motor housing and the hydraulic variable speed drive housing, or internally in the common driver side compartment.

8. The apparatus according to claim 3, wherein: the pressure booster comprises a control system that maintains a set point or state based on internal feedback and without external input; and the control system comprises a closed loop control system.

9. The apparatus according to claim 3, wherein: the driver side impeller on the rotatable motor shaft pressurizes the common driver side fluid to an overpressure of 5-50 bar at normal operation, to power the actuator system of the control system and power the hydraulic variable speed drive while eliminating any risk of cavitation, in the common driver side compartment containing the motor and the hydraulic variable speed drive; and the common driver side fluid is a common driver side liquid or liquid mixture.

10. The apparatus according to claim 3, wherein the hydraulic variable speed drive comprises vanes arranged in a common driver side fluid flow path coupling the impeller to the turbine, and the actuator system, coupled to the vanes, wherein the actuator system controls vane angle of a guide wheel, thereby controlling a rotational coupling from the rotatable motor shaft to the centrifugal pump shaft or compressor shaft.

11. The apparatus according to claim 3, wherein the control system comprises transmitters for at least rotational speed of the centrifugal pump shaft or compressor shaft and the rotatable motor shaft, and vane angle of a non-rotating guide wheel with vanes of the hydraulic variable speed drive and torque on the centrifugal pump shaft or compressor shaft if a process fluid to be pressure boosted is a multiphase fluid.

12. The apparatus according to claim 10, wherein: a valve differential pressure is at least 5 bar between a valve inlet and a valve outlet and an actuator differential pressure is at least 3 bar between an actuator inlet and an actuator outlet, and the absolute inlet pressure to the vane is 20 bar minimum.

13. The apparatus according to claim 3, comprising an electric actuator.

14. The apparatus according to claim 3, wherein the motor is an asynchronous induction motor.

15. The apparatus according to claim 3, wherein the hydraulic variable speed drive controls a speed of the pressure booster to be in a range from 0 to at least 2 times a rotational speed of the motor.

16. A method for boosting the pressure of petroleum fluids, produced water or seawater, without an electric variable speed drive, the method consisting essentially the steps of: fluidly connecting the apparatus according to claim 3 to an inlet for petroleum fluids, produced water or seawater and an outlet for the petroleum fluids, produced water or seawater; connecting an electric power supply line; connecting a control link; operating the pressure booster by pressurizing the common driver side fluid, by the driver side impeller on the rotatable motor shaft, to power the actuator system of the control system and power the hydraulic variable speed drive in one of the separate motor housing and the common driver side compartment containing the motor and the hydraulic variable speed drive; and wherein the apparatus is controlled via an active closed-circuit control system integrated in the apparatus, controllable via the control link, wherein control is based on signals from transmitters for at least rotational speed of the pump or compressor shaft and the rotatable motor shaft, and vane angle of vanes of the hydraulic variable speed drive, and, if a process fluid to be pressure boosted is a multiphase fluid, torque on the pump or compressor shaft.

17. An apparatus for boosting pressure of petroleum fluids, produced water or seawater, the apparatus consisting essentially of: a motor; a pressure booster in the form of a centrifugal pump or a compressor; a rotatable motor shaft; and a pressure booster shaft in the form of a centrifugal pump shaft or compressor shaft; a coupling between the rotatable motor shaft and the pressure booster shaft, the coupling comprising: a hydraulic variable speed drive arranged between the rotatable motor shaft and the pressure booster shaft, the hydraulic variable speed drive comprising an impeller, a turbine, a guide wheel with vanes, and an actuator system comprising a valve and a vane actuator, the common driver side fluid is supplied from the valve to and from the vane actuator, and further wherein the actuator system controls an angle of the vanes, wherein the impeller of the hydraulic variable speed drive is arranged on the rotatable motor shaft and a turbine of the hydraulic variable speed drive is arranged on the centrifugal pump shaft or compressor shaft of the pressure booster, wherein the hydraulic variable speed drive is the only coupling rotatably coupling the motor shaft and the pressure booster shaft; a common driver side fluid for cooling, lubricating, flushing and powering of the hydraulic variable speed drive and cooling, lubricating and flushing of the motor and bearings; a control system for controlling a coupling of the rotatable motor shaft to the pump or compressor shaft by the hydraulic variable speed drive, wherein the rotatable motor shaft drives the centrifugal pump shaft or compressor shaft via the hydraulic variable speed drive, without control of any electric variable speed drive; a driver side impeller on the rotatable motor shaft, or a pump or a hydraulic power unit, that pressurizes the common driver side fluid, wherein the driver side impeller, the pump or hydraulic power unit are configured to power an actuator system of the control system and power the hydraulic variable speed drive in one of a separate motor housing and a common driver side compartment containing the motor and the hydraulic variable speed drive; a cooler for cooling the common driver side fluid, arranged outside the motor housing or the common driver side compartment, fluidly coupled to the common driver side fluid; wherein the cooler is the only structure outside the motor housing or the common driver side compartment to which flow of the common driver side fluid is configured to flow, wherein the common driver side fluid circulates in the apparatus only in the motor housing or the common driver side compartment and the cooler; and wherein the rotatable coupling between the motor shaft and pump or compressor shaft is by the hydraulic variable speed drive only.

18. The apparatus according to claim 17, wherein, in addition to a process fluid inlet and a process fluid outlet, external connections consist of an electric power supply line and a control link.

19. The apparatus according to claim 17, wherein the motor and the hydraulic variable speed drive are arranged in the common driver side compartment isolated from a process fluid to be pressure boosted by the centrifugal pump or compressor, wherein the hydraulic variable speed drive comprises a separation wall on a side of the hydraulic variable speed drive facing the motor or compressor, the separation wall isolates the common driver side compartment from the process fluid.

20. The apparatus according to claim 17, comprising internal lines, gaps, channels or pipe sections for circulating the common driver side fluid internally in a motor housing and a hydraulic variable speed drive housing and between the motor housing and the hydraulic variable speed drive housing, or internally in the common driver side compartment wherein the motor and the hydraulic variable speed drive are arranged to and from the external cooler.

21. The apparatus according to claim 17, wherein the pressure booster comprises a closed loop control system.

22. The apparatus according to claim 17, wherein: the driver side impeller on the rotatable motor shaft pressurizes the common driver side fluid to an overpressure of 5-50 bar at normal operation, to power the actuator system of the control system and power the hydraulic variable speed drive while eliminating any risk of cavitation, in one of the separate motor housing and the common driver side compartment containing the motor and the hydraulic variable speed drive; and the common driver side fluid is a common driver side liquid or liquid mixture.

23. The apparatus according to claim 17, wherein the hydraulic variable speed drive comprises vanes arranged in a common driver side fluid flow path coupling the impeller to the turbine, and the actuator system, coupled to the vanes, wherein the actuator system controls vane angle of a guide wheel, thereby controlling a rotational coupling from the rotatable motor shaft to the centrifugal pump shaft or compressor shaft.

24. The apparatus according to claim 17, wherein the control system comprises transmitters for at least rotational speed of the centrifugal pump shaft or compressor shaft and the rotatable motor shaft, and vane angle of a non-rotating guide wheel with vanes of the hydraulic variable speed drive and torque on the centrifugal pump shaft or compressor shaft if a process fluid to be pressure boosted is a multiphase fluid.

25. The apparatus according to claim 23, wherein: a valve differential pressure is at least 5 bar between a valve inlet and a valve outlet and an actuator differential pressure is at least 3 bar between an actuator inlet and an actuator outlet, and the absolute inlet pressure to the vane is 20 bar minimum.

26. The apparatus according to claim 17, comprising an electric actuator.

27. The apparatus according to claim 17, wherein the motor is an asynchronous induction motor.

28. The apparatus according to claim 17, wherein the hydraulic variable speed drive controls a speed of the pressure booster to be in a range from 0 to at least 2 times a rotational speed of the motor.

29. A method for boosting the pressure of petroleum fluids, produced water or mixtures thereof, or seawater, without an electric variable speed drive, the method consisting essentially of: fluidly connecting the apparatus according to claim 17 to an inlet for petroleum fluids, produced water or seawater and an outlet for the petroleum fluids, produced water or seawater; connecting an electric power supply line; connecting a control link; operating the pressure booster by pressurizing the common driver side fluid, by the driver side impeller on the rotatable motor shaft, to power the actuator system of the control system and power the hydraulic variable speed drive in one of the separate motor housing and the common driver side compartment containing the motor and the hydraulic variable speed drive; and wherein the apparatus is controlled via an active closed-circuit control system integrated in the apparatus, controllable via the control link, wherein control is based on signals from transmitters for at least rotational speed of the pump or compressor shaft and the rotatable motor shaft, and vane angle of vanes of the hydraulic variable speed drive, and, if a process fluid to be pressure boosted is a multiphase fluid, torque on the pump or compressor shaft.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 illustrates an embodiment of a pressure booster of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(2) Reference is made to FIG. 1, illustrating a pressure booster 1 of the invention. More specifically, the embodiment is a pressure booster 1 for boosting the pressure of petroleum fluids, produced water or seawater, comprising a pressure booster 2 with a motor 3, a rotatable motor shaft 4 and a rotatable pump or compressor shaft 5 where a centrifugal pump 2 or compressor is arranged. An inlet 29 receives process fluid. Pressure boosted process fluid is delivered through an outlet 30. The pressure booster 2 is a pump if the process fluid is liquid or multiphase fluid, and a compressor if the process fluid is gas. A hydraulic variable speed drive 6 arranged between the motor and the pump or compressor, rotatably couples the motor shaft and the pump or compressor shaft 5. The hydraulic variable speed drive comprises an impeller 7 and a turbine 8, wherein the impeller of the hydraulic variable speed drive is arranged on the motor shaft and the turbine of the hydraulic variable speed drive is arranged on the pump or compressor shaft.

(3) A driver side impeller 9 is arranged on the rotatable motor shaft. The pressure booster contains a common driver side fluid 10 for cooling, lubrication, flushing and powering and control of the hydraulic variable speed drive, and cooling, lubrication and flushing of the motor and bearings, circulated by the driver side impeller 9. A control system 11 controls the coupling of the motor shaft to the pump or compressor shaft by the hydraulic variable speed drive, wherein the motor shaft drives the pump or compressor shaft via the hydraulic variable speed drive. Furthermore, an electric power supply line 12 delivers the required electric power, and a control link 13 allows transmitting control signals to and from the pressure booster.

(4) The illustrated embodiment comprises a common driver side compartment 14 isolated by a separation wall 15 from a process fluid to be pressure boosted by the pump or compressor, in a single pressure booster unit 1. The walls of the process compartment 31 can be dimensioned for higher pressure than the walls of the common driver side compartment, except for the separation wall 15 that is common between the compartments.

(5) The separation wall 15 comprises a seal or packer, between the separation wall and pump or compressor shaft. To eliminate continuous common driver side fluid supply, a common driver side fluid accumulator is preferably arranged for common driver side fluid replacement or supply, if or when required. Alternatively, a port for common driver side fluid supply via an ROV-remotely operated vehicle, is arranged. Alternatively, a flow bore in an umbilical can be used to supply common driver side fluid, for example in the electric power supply line 12. Preferably, the pressure booster of the invention comprises coupling to an umbilical flow bore or separate line with supply of fluid for flow assurance, in the form of glycol, glycol and water mixture, or methanol, for use as and supply of common driver side fluid (10). Alternatively, common driver side fluid leakage and supply can be eliminated by arranging a magnetic coupling with a separation wall between magnetic coupling sides, arranged between the driver side compartment and pump or compressor compartment, in the common pressure booster housing, thereby separating the compartments hermetically and eliminating any leakage and thereby any requirement for supply of common driver side fluid.

(6) The common driver side fluid is circulating internally in the common driver side compartment through internal lines, gaps, channels 16; and externally through external pipe sections 17, through a cooler 32.

(7) The hydraulic variable speed drive comprises a non-rotating guide wheel 19 with vanes 20 arranged between the impeller and turbine, and an actuator system 18, coupled to the guide vanes. The actuator system 18 controls vane angle of the guide wheel, thereby controlling the rotational coupling from motor shaft to pump or compressor shaft. The actuator system 18 is a part of the control system 11. Alternatively, the vanes are arranged in the common driver side fluid flow path coupling the impeller to the turbine, wherein vane angles are controllable by an electric actuator, a rotating vane actuator or another actuator. Controlling the vane angles control how much of the common driver side fluid shall flow through the flow path acting to couple the impeller to the turbine, and how much of the fluid shall bypass the coupling.

(8) Alternatively, only static vanes or static guide structure are used. This is preferable if the pressure booster motor is a permanent magnet motor, which require a topsides or subsea VFD/VSD for start of the motor, which topsides or subsea VFD/VSD can readily be used for speed control, whilst the hydraulic variable speed drive of the pressure booster acts like a step up gear. Frictional losses of the common driver side fluid, or any alternative fluid, follows fluid velocity at an exponent of about 2,7, therefore the benefit of reduced motor rpm is substantial.

(9) The control system comprises transmitters for at least rotational speed 21 of the pump or compressor shaft and the motor shaft, and vane angle 22 of a non-rotating guide wheel with vanes of the hydraulic variable speed drive; and torque 23 on the pump or compressor shaft if the process fluid to be pressure boosted is a multiphase fluid.

(10) The illustrated actuator system 18 comprises a valve 11 and a vane actuator 24, wherein the common driver side fluid is supplied from the valve to and from the vane actuator, wherein a valve differential pressure is at least 5 bar or 10 bar between a valve inlet 25 and a valve outlet 26 and an actuator differential pressure is at least 3 bar or 5 bar between an actuator inlet 27 and an actuator outlet 28, and the absolute inlet pressure to the vane is 5, 10, 15 or 20 bar minimum.

(11) The pressure booster, method and use of the invention enables the following features, advantages or technical effects: Soft start and stop of pump (motor protectionreduce mechanical wear/tear) Variable speed control (with constant speed motor), which is essential in subsea rotating machinery Operating pump at higher than motor speed (up to at least 2 motor speed)less viscous losses than if both pump and motor shaft spins at for example 6000 rpm and more stable system (less vibration) Inherent regulating capabilityconstant power transmitted provided guide vane position is constantif gas enters pump then torque drops and rpm increases to keep kW (power) constantand higher speed removes the gas (and vice versa) Improved rotodynamic stability in general (by having non-mechanical contact between motor and pump shafts) Closed Loop Electric Control system preferably used to regulate Hydraulic variable speed drive HVSD in a subsea or unmanned Rotating Machine; has not been used subsea before. Using the inherent differential pressure in the common driver side fluid to actuate the actuator. Using the same fluid in the HVSD as is in the el. motor (no separating seal or wallthis is normally present, not separate volumes or fluids, in principle not separate pressures either) Actuator (such as RVA) position measurementdifferential measurements instead of single endedas the actuator or RVA moves in many directions due to pressures and exact position is neededunique Overpressure of the common driver side fluidat least 5 bar absolute pressure as opposed to conventional hydraulic couplings. Driver side arrangement with orifices and gaps and lines to control the fluid flows and pressure throughout the Motor-HVSD-Pump system (stabilize, cool and lubricate) Allow to eliminate barrier fluid supply from topsides or onshore, at least continuous supply or/and continuous connection. Eliminate a separate barrier fluid and accordingly any separate barrier fluid supply.

(12) The pressure booster of the invention may include any feature or step here described or illustrated, in any operative combination, wherein each such operative combination is an embodiment of the present invention. The method of the invention may include any feature or step here described or illustrated, in any operative combination, wherein each such operative combination is an embodiment of the present invention.