Pressure transfer device and associated system, fleet and use, for pumping high volumes of fluids with particles at high pressures

Abstract

The invention relates to pressure transfer device, system comprising the pressure transfer device, a fleet comprising the system and use of a pressure transfer device for pumping fluid at pressures above 500 bars, the pressure transfer device (1′, 1″) comprising a pressure chamber housing (1′, 1″) and at least one connection port (3′, 3″), the at least one connection port (3′, 3″) being connectable to a dual acting pressure boosting liquid partition device (2) via fluid communication means (26′, 27′; 26″, 27″), the pressure chamber housing comprises: - a pressure cavity (4′, 4″) inside the pressure chamber housing, and at least a first port (5′, 5″) for inlet and/or outlet of fluid to the pressure cavity (4′, 4″), - a bellows (6′, 6″) defining an inner volume (7′, 7″) inside the pressure cavity (4′, 4″), and wherein the inner volume (7′, 7″) is in fluid communication with the connection port (3′, 3″), wherein the pressure cavity (4′, 4″) has a center axis (C′, C″) with an axial length (L) defined by the distance between the connection port (3′, 3″) and the first port (5′, 5″) and a varying cross sectional area over at least a part of the axial length (L), and wherein the bellows (6′, 6″) is configured to move in a direction substantially parallel with the center axis (C′, C″) over a part of the axial length (L) of the pressure cavity (4′, 4″).

Claims

1. A system comprising a dual acting pressure boosting liquid partition device and a pressure transfer device for pumping fluid with particles at pressures above 500 bars, the pressure transfer device comprising a pressure chamber housing and at least one connection port, wherein the at least one connection port is connectable to the dual acting pressure boosting liquid partition device via fluid communication means, the pressure chamber housing comprises: a pressure cavity inside the pressure chamber housing, and at least one first port for inlet and/or outlet of fluid to the pressure cavity, a bellows defining an inner volume inside the pressure cavity, and wherein the inner volume of the bellows is part of a closed hydraulic loop volume with the dual acting pressure boosting liquid partition device and is in fluid communication with the connection port such that drive fluid in the form of pressurized hydraulic fluid from the dual acting pressure boosting liquid partition device is allowed to enter and exit the inner volume of the bellows, wherein the pressure cavity has a center axis (C) with an axial length (L′; L″) defined by the distance between the connection port and the first port, and wherein the bellows is configured to move in a direction parallel with the center axis (C′, C″) over a part of the axial length (L′, L″) of the pressure cavity.

2. The system according to claim 1, wherein the pressure cavity has a varying cross-sectional area over at least a part of the axial length (L′, L″).

3. The system according to claim 1, wherein the bellows is radially rigid and axially flexible, such that any movement of the bellows is in the axial direction thereof.

4. The system according to claim 1, wherein the pressure cavity tapers towards the first port.

5. The system according to claim 1, wherein the bellows has a smaller radial and axial extension than an inner surface of the pressure cavity, thereby forming a gap between an outer circumference of the bellows and an inner circumference of the pressure cavity in all operational positions of the bellows.

6. The system according to claim 1, wherein the first port is arranged in a lower section of the pressure cavity.

7. The system according to claim 1, wherein the pressure cavity is egg-shaped, elliptical, circular, spherical, ball-shaped or oval.

8. The system according to claim 1, wherein the bellows has a shape adapted to the shape of the pressure cavity such that the bellows, in all operational positions thereof, is restricted from coming into contact with an internal surface of the pressure chamber housing.

9. The system according to claim 7, wherein the bellows has a cylindrical shape, accordium-like shape or concertina shape.

10. System according to claim 1, wherein the bellows comprises a guiding system which comprises a guide, the guide being connected to a lower part of the bellows and is configured to be guided in the pressure chamber housing forming part of the connection port, wherein the guide is coinciding with, or being parallel to, a center axis (C′, C″) of the pressure cavity, and wherein the bellows expands and retracts axially in a longitudinal direction along the center axis (C′, C″), and wherein the pressure transfer device further comprises a bellows position sensor monitoring position of the bellows.

11. System according to claim 1, further comprising: a hydraulic pump unit pressurizing and actuating the dual acting pressure boosting liquid partition device (2), and a flow regulating assembly configured to distribute the fluid between an inlet manifold, the pressure cavity and an outlet manifold.

12. System according to claim 11, further comprising a control system for controlling working range of a pump bellows, and configured to decide whether the bellows operates within a predetermined bellows position operating range defined by maximum limitations such as maximum retracting position and maximum extension position of the bellows, the control system being adapted to calculate if an amount of hydraulic fluid volume is outside the predetermined bellows position operating range or not and/or monitor positions of the bellows and the dual acting pressure boosting liquid partition device and comparing with the predetermined bellows position operating range.

13. System according to claim 11, further comprising a feed pump for pumping the fluid with particles into the pressure cavity, and wherein the system comprises two pressure transfer devices and the dual acting pressure boosting liquid partition device being configured to sequentially pressurize and discharge/−depressurize and charge aided by the feed pump, the two pressure transfer devices by operating the hydraulic pump unit, such that one pressure transfer device is pressurized and discharged while the other pressure transfer device is de-pressurized and charged, and vice versa.

14. Fleet comprising at least two trailers, each of the trailers comprising at least one system according to claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an operational setup of a pressure transfer device and associated system in accordance with the present invention;

(2) FIG. 2 shows details of a dual acting pressure boosting liquid partition device used in connection with the pressure transfer device according to the present invention;

DETAILED DESCRIPTION OF THE DRAWINGS

(3) FIG. 1 shows an overview of an operational setup of a pressure transfer device and associated system in accordance with the present invention. It is disclosed a well stimulation pressure transfer device specifically designed for very high pressure (500 bar and above) at high rates (e.g. 1000 liters/min or more for the specific system disclosed in FIG. 1) pumping fluids, such as slurries, containing high amounts of abrasive particles. Two identical setups are disclosed in FIG. 1, having a common dual acting pressure boosting liquid partition device 2, where the elements of the setup on the left side is denoted with a single apostrophe (′) and the elements in the identical setup on the right side is denoted with double apostrophe (′″).

(4) Details of the dual acting pressure boosting liquid partition device used 2 in connection with the pressure transfer device 1′, 1″ is shown in FIG. 2. It is shown a pressure transfer device 1′, 1″ for pumping fluid at pressures above 500 bars, the pressure transfer device 1′, 1″ comprising a pressure chamber housing and a connection port 3′, 3″, the connection port 3′, 3″ being connectable to a dual acting pressure boosting liquid partition device 2 via fluid communication means in the form of first valve port 26′, 26″ and second valve port 27′, 27″ and possibly via an oil management system valve 16′, 16″. The pressure chamber housing comprises a pressure cavity 4′, 4″, and a first port 5′, 5″ connecting the pressure cavity 4′, 4″ to a well via a flow management system 13. The first port 5′, 5″ acting as inlet and/or outlet for fluid or liquid to be pumped. It is further disclosed a bellows 6′, 6″ arranged within the pressure cavity 4′, 4″, and wherein an inner volume 7′, 7″ of the bellows 6′, 6″ is in fluid communication with the connection port 3′, 3″ and the inner volume 7′, 7″ is prevented from fluid communicating with the pressure cavity 4′, 4″. The pressure cavity length L′, L″, extending in a longitudinal direction between the connection port 3′, 3″ and the first port 5′, 5″, has a varying cross sectional area. The bellows 6′, 6″ is configured to move in a direction substantially in the longitudinal direction, which in the drawing is coinciding with the center axis C′, C″ of the pressure cavity 1′, 1″.

(5) The pressure transfer device 1′, 1″ comprises a bellows, exemplified as a hydraulically driven fluid-tight bellows 6′, 6″ comprising an internal guide 9′, 9″ and a bellows position sensor 12′, 12″ with an inductive rod 43′, 43″ adapted to read a magnet 10′, 10″. The magnet 10′, 10″ may be fixedly connected to the guide 9′, 9″. The guide 9′, 9″ is itself guided in the pressure chamber housing, for example along the longitudinal extension of the connection port 3′, 3″. In the disclosed example, the guide 9′, 9″ is connected to the lower end of the bellows 6′, 6″ in one end and is guided in the pressure chamber housing in the upper end thereof. The guide 9′, 9″, and thereby the magnet 10′, 10″, follows the movement of the bellows 6′, 6″. The bellows position sensor 12′, 12″, e.g. the measuring rod 43′, 43″ may comprise means for detecting and determining the position of the magnet 10′, 10″ (and thereby the guide 9′, 9″ and bellows 6′, 6″), for example by inductive detection of the magnet position. Although the description describes that the magnet 10′, 10″ is connected to the guide 9′, 9″ which moves relative to the fixed measuring rod 43′, 43′, it is possible to arrange the magnet 10′, 10″ stationary and e.g. the guide 9′, 9″ inductive to monitor the position. Furthermore, it is possible to use other sensors than the linear position sensor described above as long as they are capable of monitor the exact position of the bellows 6′, 6″.

(6) The bellows 6′, 6″ is placed in a pressure cavity 4′, 4″ with a defined clearance to the internal surface of the pressure chamber housing′. The drive fluid is directed into and out of an inner volume 7′, 7″ of the bellows 6′, 6″ through a connection port 3′, 3″ in the top of the pressure cavity 4′, 4″ (i.e. the top of pressure chamber housing). The bellows 6′, 6″ is fixedly connected in the top of the pressure cavity 4′, 4″ to the internal surface of the pressure chamber housing by means known to the skilled person. The connection port 3′, 3″ is in communication with a dual acting pressure boosting liquid partition device 2 and possibly an oil management system valve 16′, 16′.

(7) The pressure transfer device 1′, 1″ may further comprise an air vent (not shown) to ventilate air from the fluid to be pumped. The air vent may be any vent operable to draw out or ventilate excess air from a closed system, such as any appropriate valves (choke) or similar.

(8) The pumped medium, e.g. fracking fluid with particles, enters and exits the pressure cavity 4′, 4″ through a first port 5′, 5″ in the bottom of the pressure cavity 4′, 4″ (i.e. pressure chamber housing). The first port 5′, 5″ is in communication with a flow regulating device 13, such as a valve-manifold. The flow regulating device 13 is explained in greater detail below.

(9) Driven by the dual acting pressure boosting liquid partition device 2 the pressure cavity 4′, 4″, in combination with the bellows 6′, 6″, is pumping the fluid by retracting and expanding the bellows 6′, 6″ between its minimum and maximum predefined limitation. Keeping the bellows within this minimum and maximum predefined limitation prolongs the life of the bellows. In order to ensure that the bellows 6′, 6″ work within its predefined limitation, this movement is monitored by the bellows position sensor 12′, 12″. Dynamically moving the bellows outside these minimum and maximum predefined limitations, may severely reduce the life time of the bellows. Without this control, the bellows 6′, 6″ will over time, as a result of internal leakage mainly in the dual acting pressure boosting liquid partition device 2, be over-stressed either by over-extending (will eventually crash with pressure cavity 4′, 4″ or over compress (retract) causing particles in fluid to deform or puncture the bellows 6′, 6″ or generate delta pressure). A central guiding system 9′, 9″, exemplified as a guide 9′, 9″, ensures that the bellows 6′, 6″ retract and expand in a linear manner ensuring that the bellows 6′, 6″ do not hit the sidewalls of the pressure cavity 4′, 4″ and at the same time ensures accurate positioning readings from the bellows position sensor 12′, 12″. Thus, the pressure cavity 4′, 4″ is specifically designed to endure high pressures and cyclic loads at the same time as preventing build-up of sedimentation. The defined distance between the outer part of the bellows 6′, 6″ and the internal dimension of the pressure chamber housing ensures pressure balance of the internal pressure of the bellows 6′, 6″ and the pump medium pressure in the pressure cavity 4′, 4″.

(10) This pressure cavity is designed to carry the cyclic loads that this system will be subjected to, and to house the bellows and the bellows positioning system. The connection port 3′, 3″ has a machined and honed cylindrical shape through the base material of the pressure cavity 4′, 4″ “body” and serves as a part of the bellow guiding system 9′, 9″ like a cylinder and piston configuration. The pressure cavity 4′, 4″ is ideally shaped to prevent stress concentrations. The internal bellows guiding system 9′, 9″ ensures a linear movement of the bellows 6′, 6″ without the need of an external guide.

(11) The first port 5′, 5″ of the bottom in the pressure cavity 4′, 4″, is shaped to prevent sedimentation build-up by sloping or tapering the pressure cavity 4′, 4″ towards the first port 5′, 5″. Consequently, sedimentation build-up is prevented because the sediments or particles in the liquid to be pumped naturally flows, i.e. by aid of gravity, out of the pressure cavity 4′, 4″ exiting through the first port 5′, 5″. Without this sloped or tapered shape, the sedimentation build up may lead to problems during start-up of the pressure transfer device and or the sediments may build-up and eventually surround lower parts of the outside of the bellows 6′, 6″.

(12) The dual acting pressure boosting liquid partition device 2 comprises a hollow cylinder having a longitudinal extension, wherein the cylinder comprises a first and second part having a first transverse cross sectional area a1 and a third part having a second transverse cross sectional area a2 of different size than the first and second part. The dual acting pressure boosting liquid partition device comprises a rod movably arranged like a piston inside the cylinder. The rod has a cross sectional area corresponding to the first transverse cross sectional area a1 and defines a second piston area 31′, 31″, and wherein the rod, when arranged within the hollow cylinder, defines a first plunger chamber 17′ and a second plunger chamber 17″ in the first and second part. The rod further comprises a protruding portion 30 having a cross sectional area corresponding to the second transverse cross sectional area a2 and the protruding portion defining a first piston area 30′, 30″ and a first outer chamber 44′ and a second outer chamber 44″ in the third part. A part of the rod defining the first and second plunger chamber 17′, 17″, over at least a part of its length, is formed with a first recess 40′ in pressure communication with the first plunger chamber 17′ and a second recess 40″ in pressure communication with the second plunger chamber 17″.

(13) The first plunger chamber 17′ comprises a first plunger port 18′ that is in communication with the inner volume 7′ of the bellows 6′, alternatively via the first oil management system valve 16′. Similarly, the second plunger chamber 17″ comprises a second plunger port 18″ that is in communication with the inner volume 7″ of the bellows 6″, alternative via the second oil management system valve 16″. The volumes inside the first and second plunger chambers 17′, 17″ are varied with the rod 19 being extracted and retracted in/out of the respective first and second plunger chamber 17′, 17″. The rod 19 may comprise a dual acting pressure boosting liquid partition device position sensor 21. First and second seals 22′, 22″ may be arranged between the protruding portion 30 of the rod and the first plunger chamber 17′ and the second plunger chamber 17″, respectively. Said first and second seals 22′, 22″ may be ventilated and cooled by a separate or common lubrication system 23′, 23″.

(14) The rod 19 is driven back and forth by allowing in sequence pressurized fluid, such as oil or other suitable hydraulic fluid, to flow in to first inlet/outlet port 24′ and out of second inlet/outlet port 24″, then to be reversed to go in the opposite direction. First and second inlet outlet ports 24′, 24″ are in communication with a hydraulic pump unit 11.

(15) The first and second oil management system valves 16′, 16″ are positioned between the bellows 6′, 6″ and the dual acting pressure boosting liquid partition device 2 and are exemplified as two three-way valves which may comprise a first and second actuators 25′, 25″ operating the first and second three-way valves, respectively. The setups of the first and second oil management system valves 16′, 16″ and their connection to the different pressure transfer devices 1′, 1″, are identical. Thus, in the following the system on the left hand side, i.e. the system in communication with the first plunger port 18′, will be described in more detail. The oil management system valve 16′, in the drawings exemplified as a three-way valve, comprises three ports including a first valve port 26′ in communication with first plunger port 18′, a second valve port 27′ in communication with the connection port 3′ of the pressure transfer device, and a third valve port 28′ in communication with an oil reservoir 29′. Similarly, with reference to the pressure transfer device 1″ on the right hand side, the oil management system valve 16″ in communication with the second plunger port 18″, comprises three ports including first valve port 26″ in communication with second plunger port 18″, a second valve port 27″ in communication with the connection port 3″ of the pressure transfer device 1″, and a third valve port 28″ in communication with an oil reservoir 29″.

(16) The hydraulic pump unit 11 may comprise over center axial piston pumps that are controlled by the position data from both bellows position sensor 12′, 12″ and dual acting pressure boosting liquid partition device position sensor 21 in the dual acting pressure boosting liquid partition device 2 and possibly according to input data from Human Machine Interface (HMI) and/or the control system. The hydraulic pumping unit 11 may be driven e.g. by a motor M such as any standard motors used in the specific technical fields.

(17) The flow regulating assembly 13, e.g. a valve manifold, may be a common flow regulating assembly for the identical systems on the left hand side and on the right hand side of the Figure. In relation to the system on the left hand side, the flow regulating assembly 13 may comprise a pump port 36′ in communication with the first port 5′ of the pressure transfer device 1′, a supply port 35′ in communication with the liquid to be pumped via an inlet manifold 14 in the flow regulating assembly 13, and a discharge port 37′ in communication with discharge manifold 15 in the flow regulating assembly 13. To be able to switch and operate between the different inlets and outlets, the flow regulating assembly may comprise supply valve 38′ comprising a check valve allowing supply of pump fluid when the pressure in the inlet manifold 14 is larger than the pressure in the pressure cavity 4′ and less than the pressure in the discharge valve 39′. The inlet manifold 14 is in communication with a feed pump and blender. The blender mixes the liquid to be pumped, and the feed pump pressurizes the inlet manifold 14 and distributes said mixed fluid to the pressure transfer devices 1′, 1″ (pressure cavities 4′, 4″). The blender typically mixes the liquid to be pumped with particles such as sand and proppants. Such feed pump and blender are known for the person skilled in the art and will not be described in further detail herein.

(18) Similarly, for the system on the right hand side of the Figure, the flow regulating assembly 13 may comprise a pump port 36″ in communication with the first port 5″ of the pressure transfer device 1″, a supply port 35″ in communication with the liquid to be pumped via an inlet manifold 14, and a discharge port 37″ in communication with discharge manifold 15. Furthermore, to be able to switch and operate between the different inlets and outlets, the flow regulating assembly may comprise supply valve 38″ comprising a check valve allowing supply of pump fluid when the pressure in the inlet manifold 14 is larger than the pressure in the pressure cavity 4″, and discharge valve 39″ allowing fluid to be discharged to the discharge manifold 15 when the pressure in the pressure cavity 4″ is higher than the pressure in the discharge manifold 15 for pumping fluids at high pressures and flow rates e.g. into a well.

(19) The flow regulating assembly 13 distributes the pumped liquid between the inlet manifold 14, the pressure cavity 4′, 4″ and the outlet manifold 15 by utilizing two check valves, one for inlet and one for outlet, and charge/discharge port positioned between them. The supply valve 38′, 38″ positioned between the supply port 35′, 35″ and the pump port 36′, 36′ allowing fluid to charge the pressure cavity 4′, 4″ when bellows 6′, 6″ is retracting, i.e. the liquid to be pumped provides pressure from below assisting in the retraction/compression of the bellows 6′, 6″. The assisting pressure of the liquid to the pressure transfer device in the inlet manifold 14 is typically in the range 3-10 bars refilling the pressure cavity 4′, 4″ and preparing for next dosage of high pressure medium to be pumped down into the well. When bellows 6′, 6″ starts extending (i.e. pressurized fluid is filling the inner volume 7′, 7″ of the bellows 6′, 6″) the supply valve 38′, 38″ will close when the pressure exceeds the feed pressure in the inlet manifold 14 and thereby force the discharge valve 39′, 39″ to open and thereby discharging the content in pressure cavity 4′, 4″ through the discharge port 37′, 37″ and in to the discharge manifold 15. This will occur sequentially in the setup on the left hand side of the Figure and on the right hand side of the Figure, respectively.

(20) The hydraulic pump unit 11 utilizes over center axial piston pumps configured in an industrially defined closed hydraulic loop volume, also named swash plate pumps. Swashplate pumps have a rotating cylinder array containing pistons. The pistons are connected to the swash plate via a ball joint and is pushed against the stationary swash plate, which sits at an angle to the cylinder. The pistons suck in fluid during half a revolution and push fluid out during the other half. The greater the slant the further the pump pistons move and the more fluid they transfer. These pumps have a variable displacement and can shift between pressurizing first inlet/outlet port 24′ and second inlet/outlet port 24″ thereby directly controlling the dual acting pressure boosting liquid partition device(s) 2.

(21) The oil management system valve 16′, 16″ is exemplified as a three-way valve. However, other setups may be used such as an arrangement of two or more valves. The oil management system valve is controlled by a control system which can determine if correct volume of hydraulic fluid is circulated between the inner volume 7′, 7″ of the bellows 6′, 6″ and the first and second plunger chambers 17′, 17″ by utilizing the position sensors in the bellows and in the dual acting pressure boosting liquid partition device. At the same time, it enables the system to replace the oil in this closed hydraulic loop volume if temperatures in the oil reaches operational limits. This is done by isolating the second valve port 27′, 27″ from the dual acting pressure boosting liquid partition device and opening communication between first valve port 26′, 26″ and third valve port 28′, 28″, thereby allowing the piston 30 or rod 19 in the dual acting pressure boosting liquid partition device 2 to position itself according to the bellows 6′, 6″ position. The control system controlling the oil management system valve 16′, 16″ monitors the position of the bellows 6′, 6″ in co-relation with the position of the plunger 19 and adds or retract oil from the system when the system reaches a maximum deviation limit. It will do this by, preferably automatically, stopping the bellows 6′, 6″ in a certain position and let the plunger 19 reset to a “bellows position” accordingly. A bellows position of the plunger 19 is typically corresponding to a position where the volumes of the first plunger chamber 17′ and the second plunger chamber 17″ are the same, which in most situations will be a position where the bellows 6′, 6″ is in a mid position. Thus, the plunger 19 is preferably positioned relative the actual position of the bellows 6′, 6″.

(22) The dual acting pressure boosting liquid partition device 2 is for example controllable by a variable flow supply from e.g. hydraulic pump unit 11 through the first inlet/outlet port 24′ and second inlet/outlet port 24″ The protruding portion 30 comprising a first end (i.e. via first piston area 30′) in fluid communication with the first inlet/outlet port 24′ and a second end (i.e. via first piston area 30″) in fluid communication with the second inlet/outlet port 24″. The rod 19 further defines a second piston area 31′, 31″ smaller than the first piston area 30′, 30″. The rod 19 separating the first and second plunger chambers 17′, 17″ and is operated to vary volumes of the first and second plunger chambers 17′, 17″ by extracting and retracting the rod 19 in/out of the first and second plunger chambers 17′, 17″, respectively. The rod 19 is a partly hollow and comprises a first recess 40′ and a second recess 40″. The first and second recesses 40′, 40″ are separated from each other. Thus, fluid is permitted from flowing between the first and second recesses 40′, 40″. The first recess 40′ is in fluid communication with the first plunger chamber 17′ and the second recess 40″ is in fluid communication with the second plunger chamber 17′.

(23) The dual acting pressure boosting liquid partition device's 2 function is to ensure that a fixed volume of hydraulic fluid, e.g. oil, is charging/dis-charging the bellows 6′, 6″. At the same time, it functions as a pressure amplifier (booster or intensifier). In the illustrated dual acting pressure boosting liquid partition device 2 the pressure is increased by having a larger first piston area 30′, 30″, than the second piston area 31′ in the first plunger chamber 17′ and second piston area 31″ in the second plunger chamber 17″, respectively. There is a fixed ratio between the first piston area 30′, 30″ and the second piston area 31′, 31″, depending on the difference in the first and second piston areas. Hence, a fixed pressure into the first or second outer chamber 44′, 44″ gives a fixed pressure amplified by the pressure difference of the first and second piston areas. However, the input pressure may be varied to get a different pressure out, but the ratio is fixed. The amplification of the pressure is vital to enable pumping of fluids well over the maximum normal pressure range of the industrial hydraulic pump units 11 that is powering the unit and is varied to best suited industry needs for pressures.

(24) The dual acting pressure boosting liquid partition device 2 may comprise dual acting pressure boosting liquid partition device position sensor 21 which continuously communicates with the overall control system which can operate the oil management system valve 16′, 16″ to refill or drain hydraulic fluid from the closed hydraulic loop volume based on input from the dual acting pressure boosting liquid partition device position sensor 21 in the dual acting pressure boosting liquid partition device 2 and in the bellows position sensor 12′, 12″. In the Figures, the dual acting pressure boosting liquid partition device position sensor 21 is arranged between the rod 19 and inner walls of the first or second plunger chamber 17′, 17″, such that the dual acting pressure boosting liquid partition device position sensor 21 is able to continuous monitor the position of the rod 19 and transmit signals to a control system comparing the position of the bellows 6′, 6″ and the piston or rod 19 in the dual acting pressure boosting liquid partition device 2. However, it is possible to arrange the dual acting pressure boosting liquid partition device position sensor 21 at other locations as well, including outside the dual acting pressure boosting liquid partition device 2, as long as it can monitor the position of the rod 19. As such, any leakage or overfilling of hydraulic fluid in any of the first or second plunger chambers 17′, 17″ can be detected and corrected (e.g. by using the oil management system valve 16′, 16″ to reset the rod to zero deviation position according to bellows position as described above).

(25) Specifically, the first and second plunger chambers 17′, 17′ will be subjected to extreme pressures. All transitions are shaped to avoid stress concentrations. The rod 19 in the dual acting pressure boosting liquid partition device is preferably a hollow rod in order to compensate for ballooning of the shell (shell=the outer walls of the dual acting pressure boosting liquid partition device 2) during a pressure cycle. Preferably, the ballooning of the hollow rod is marginally less than the ballooning of shell to prevent any extrusion-gap between the hollow rod and the shell to exceed allowable limits. If this gap is too large, there will be leakage over the first and second seals 22′, 22″, resulting in uneven volumes of hydraulic fluids in the first and second plunger chambers 17′, 17″. The thickness of the shell and the walls of the hollow rod, i.e. the walls surrounding the first and second recesses 40′, 40″ are chosen such that they deform similarly/equally in the radial direction, and the first and second seals 22′, 22″ are also protected ensuring a long service life of the first and second seals 22′, 22″.

(26) The control system has three main functions. The first main function of the control system is controlling the output characteristics of the pressure transfer device 1′, 1″: the pressure transfer device 1′, 1″ is able to deliver flow based on of a number of parameters like: flow, pressure, horsepower or combinations of these. Furthermore, if two dual acting pressure boosting liquid partition devices 2 are used, the pressure transfer device 1′, 1″ can deliver a pulsation free flow up to 50% of maximum theoretical rate by overlapping the two dual acting pressure boosting liquid partition devices 2 in a manner that one is taking over (ramping up to double speed) when the other is reaching its turning position. Thus, it achieved reduced flow rates at high pressures and high flow rates at reduced pressures, in all embodiments with a substantially laminar flow. This is achieved by having an over capacity on the hydraulic pump unit 11. As the rate increases there will be gradually less room for overlapping and thereby an increasing amount of pulsations. The variable displacement hydraulic pump unit 11 in combination with pressure sensors and bellows position sensor 12′, 12″ and dual acting pressure boosting liquid partition device position sensor 21 is key for the flexibility that the system offers. The control system, which may be computer based, also enables the possibility of multiple parallel pumping systems acting as one by tying them together with a field bus. This may be done by arranging the pumping systems in parallel and use the control system to force or operate the individual pumping systems asynchronous. This minimize the risk of snaking due to interference.

(27) The second main function of the control system is to provide complete control of the bellows 6′, 6″ movement through the cycles in relation to the dual acting pressure boosting liquid partition device 2. This is of relevance in the closing/seating of the valves in the flow regulating assembly 13 (e.g. supply port 35′, 35″, pump port 36′, 36″, discharge port 37′, 37″, supply valve 38′, 38″, discharge valve 39′, 39″) because there is a combination of factors, which needs to work in synchronicity in order for this system to function with these extreme pressures and delivery rates. As for a spring, it is important for the bellows 6′, 6″ to operate within its design parameters, i.e. not over extending or over compressing in order to have a long service life.

(28) The third main function of the control system is the oil management system valve 16′, 16″ of the control system which acts when the control system finds a difference between the positions of the dual acting pressure boosting liquid partition device 2 and the bellows 6′, 6″ or that the temperature is out of predefined limits. The dual acting pressure boosting liquid partition device 2 has in general the same strengths and flaws as a hydraulic cylinder, it is robust and accurate, but it has a degree of internal leakage over the first and second seals 22′, 22″ that over time will accumulate either as an adding or retracting factor in the closed hydraulic loop volume between the first and second plunger chambers 17′, 17″ and the inner volume 7′, 7″ of the bellows 6′, 6″. To address these issues both the bellows 6′, 6″ and the dual acting pressure boosting liquid partition device 2 are fitted with position sensors 12′, 12″, 21 that continuously monitors the position of these units to assure that they are synchronized according to software-programmed philosophy. Over time, the internal leakage of the system will add up, and when the deviation of the position between the bellows 6′, 6″ and the dual acting pressure boosting liquid partition device 2 reaches the maximum allowed limit, the first and/or second oil management system valves 16′, 16″ will add or retract the necessary volume to re-synchronize the system (and adjusting preferably automatically in relation to a known position of the bellows 6′, 6″). In addition, there may be an issue that the liquid in the closed hydraulic loop volume between the pressure transfer device 1′, 1″ and the dual acting pressure boosting liquid partition device 2 generates heat through friction by flowing back and forth. On top of that the first and second seals 22′, 22″ in the dual acting pressure boosting liquid partition device 2 will also produce heat that will dissipate in to the liquid (e.g. oil) in the closed hydraulic loop volume. This issue may be addressed by using the same system as for compensating for internal leakage. The closed loop hydraulic volume can be replaced by the oil management system valve 16′, 16″.

(29) Thus, at least one of the objectives of the invention is achieved by invention as described in the drawings, i.e. a pressure transfer device and a system for fracking which can operate at high pressures with high volume flow.

(30) In the preceding description, various aspects of the invention have been described with reference to illustrative embodiments. For purposes of explanation, systems and configurations were set forth in order to provide a thorough understanding of the system and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiments, as well as other embodiments of the system, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention.

REFERENCE LIST

(31) TABLE-US-00001 1′, 1″ 1 Pressure transfer device 2 3.1 Dual acting pressure boosting liquid partition device 3 2.2 Connection port 4′, 4″ 2.1 Pressure cavity .sup. 5′ 2.3 First port 6 1.1 bellows 7 Inner volume of bellows 8 gap 9′, 9″ 1.2 Guide 10′, 10″ magnet 11  7.1 Hydraulic pump unit 12′, 12″ 1.3 Bellows Position Sensor 13  5.1 Flow regulating assembly 14  10.1 Inlet manifold 15  9.1 Outlet manifold 16′.sup.  4.1 First oil management system valve 16″ 4.1 Second oil management system valve 17′.sup.  3.2 First plunger chamber 17″ 3.2 Second plunger chamber 18′.sup.  3.3 First plunger port 18″ 3.3 Second plunger port 19  3.4 Rod 20  Hollow cylinder housing 21  3.6 Dual acting pressure boosting liquid partition device position sensor 22′.sup.  3.7 First seal 22″ 3.7 Second seal 23  6.1 Lubrication system 24′.sup.  3.8 First inlet/outlet port 24″ 3.9 Second inlet/outlet port 25′.sup.  4.3 First actuator 25″ 4.3 Second actuator 26′.sup.  4.4 First valve port 26″ 4.4 First valve port 27′.sup.  4.5 Second valve port 27″ 4.5 Second valve port 28′.sup.  4.6 Third valve port 28″ 4.6 Third valve port 29′.sup.  8.1 Oil reservoir 29″ 8.1 Oil reservoir 30′.sup.  First piston area 30″ First piston area 31′.sup.  second piston area 31″ Second piston area 35′.sup.  5.2 Supply port 35″ 5.2 Supply port 36′.sup.  Pump port 36″ Pump port 37′.sup.  Discharge port 37″ Discharge port 38′.sup.  Supply valve 38″ Supply valve 39′.sup.  Discharge valve 39″ Discharge valve 40′.sup.  First recess 40″ Second recess .sup. 42, 42″ Temperature sensor 43′.sup.  inductive rod 43″ inductive rod 44′.sup.  First outer chamber