valve

Abstract

The valve (18.1) includes a first port and a second port (50, 52) connected by a flow passage to allow passage therethrough of a medium containing solid particles. The valve also includes a valve seat (61), a closure unit (62), and a cavity (85) configured to receive at least a portion of the closure unit. The closure unit further includes (i) a barrier piston (74) that inhibits flow of solid particles from the second port when the closure unit is in its closed position, (ii) a bleed passage that provides a pressure balancing arrangement that communicates the cavity with the second port and reduces pressure therebetween, and (iii) a downwardly sloping top that extends from a central portion of the barrier piston to an outer surface of the barrier piston and allows particulates in the cavity to settle through the bleed passage toward the second port.

Description

[Technical field]

[0001] The present invention relates to a valve. It further relates to a valve closing unit and a pressure exchange chamber pump system. In addition, it relates to a pressure exchange pump system kit. It also relates to a method for modifying a pressure exchange chamber pump system. [Background technology]

[0002] Cone valves are often used to regulate the flow of media, especially media consisting of a mixture of liquid and solid particles, such as slurries.

[0003] One application in which this finds itself is in pressure exchange chamber (PEC) pumping systems. A PEC pumping system typically includes a pipe that defines a PEC and has a media or pumped fluid valving arrangement at one end and a drive fluid valving arrangement at the other end. The media valving arrangement includes a media inlet valve that allows the pumped media to enter the pressure exchange chamber, and a media outlet valve that allows the pumped media to exit the PEC along a discharge pipe, riser, or the like. Similarly, the drive fluid valving arrangement includes a drive fluid inlet valve that allows high pressure drive fluid to enter the PEC, and a drive fluid outlet valve that allows the drive fluid to exit the PEC.

[0004] In use, the pumped media may be supplied at relatively low pressure to the media inlet valve by a media delivery pump, such as a centrifugal pump. With the media inlet valve open and the drive fluid outlet valve open, the media enters the PEC and expels the drive fluid from the pressure exchange chamber through the drive fluid outlet valve. The pumped media is supplied to the PEC at a relatively low pressure, but if the PEC is located on the seabed, the ambient pressure, although it may be higher, will be lower than the pressure of the high pressure drive fluid.

[0005] Once the PEC is filled with media, i.e., the desired amount of media has entered the PEC, the media inlet valve and drive fluid outlet valve are closed. The media outlet valve and drive fluid inlet valve are opened to allow drive fluid to enter the PEC at high pressure and expel the media from the PEC through the media outlet valve. Naturally, the exact sequence and timing associated with the opening and closing of the valves can be varied to optimize operation of the pump system.

[0006] Once the media has been discharged from the PEC, the media outlet valve and drive fluid inlet valve close and the media inlet valve and drive fluid outlet valve open to fill the PEC with media in the manner described above.

[0007] As mentioned above, the media inlet valve is typically a conical valve so as to be able to operate with media containing solid particles.

[0008] A conical valve typically comprises a valve housing defining an elongated cavity, an inlet opening leading upwardly into a bottom of the cavity, and an outlet opening in fluid communication with a side of the cavity at a location spaced from the inlet opening. A valve seat is provided between the inlet and outlet openings. The valve includes a closure unit and an actuator whereby the closure unit is movable between a closed position against the valve seat to inhibit flow of medium through the valve, and an open position away from the valve seat to allow flow of medium through the valve.

[0009] A problem with conical valves is that solid particles from the media tend to settle in the housing cavity above the closure unit, which can interfere with proper functioning of the valve.

[0010] It is an aim of embodiments of the present invention to provide a means by which this problem may be ameliorated, or to provide a useful alternative. Summary of the Invention

[0011] This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

[0012] In this application, sequence numbers (first, second, third, etc.) are assigned arbitrarily herein and are used to distinguish components, but do not indicate a particular order, sequence, or importance.

[0013] Features or steps disclosed as alternatives with respect to one embodiment are intended to apply as alternatives to other embodiments, unless such combination is not possible.

[0014] According to a first aspect of the present invention, there is provided a valve comprising a first port, a second port spaced from the first port, a flow passage connecting the first port and the second port in fluid communication and allowing a medium containing solid particles to pass therethrough, a valve seat positioned within the flow passage, a closure unit movable between a closed position positioned against the valve seat to inhibit flow of the medium through the flow passage and an open position to allow flow of the medium through the flow passage, and a cavity configured to receive at least a portion of the closure unit in its open position, wherein the closure unit further comprises a barrier piston defining: (i) an outer surface configured to inhibit flow of solid particles from the second port when the closure unit is in its closed position, thereby inhibiting passage of such solid particles into the cavity; (ii) one or more bleed passages connecting the cavity in fluid communication with the second port and providing a pressure balancing arrangement to reduce a pressure differential therebetween; and (iii) a downwardly sloping upper portion extending from a central portion of the barrier piston to an outer surface of the barrier piston to allow particulates in the cavity to settle through the one or more bleed passages towards the second port.

[0015] The reduction in pressure differential may be the creation of a zone of reduced pressure above the piston that would inhibit closing of the valve. Alternatively, the reduction in pressure differential may be the creation of a zone of higher pressure above the piston that would inhibit opening of the valve. Reducing the pressure differential has the advantage of ensuring that the piston can move at a desired velocity for a given actuator force.

[0016] The barrier piston may have any suitable shape, in a preferred embodiment the barrier piston has a cylindrical shape and a circular cross-section, although in other embodiments elliptical, rectangular or polygonal cross-sections may be used.

[0017] Optionally, the valve comprises an actuated valve.

[0018] The valve may define a cylindrical chamber having a first end, a second end, and a side extending therebetween, with the first port opening into the chamber through the first end and the second port leading out of the chamber through the side at a location spaced from the first end. The first end may be an operable bottom end of the chamber. The valve seat may be frusto-conical in shape and tapered inwardly and downwardly, and the closure unit may be axially movable within the chamber between its open and closed positions.

[0019] A barrier piston may be mounted for reciprocating movement within the chamber above the first port. The barrier piston is preferably dimensioned to inhibit the passage of large solid particles into the chamber above the piston, particularly particles large enough to potentially interfere with the movement of the closure unit. To this end, the radial clearance between the piston and the interior surfaces of the housing defining the sides of the chamber may be less than 2 mm. In a preferred embodiment of the invention, the clearance may be approximately 0.5 mm.

[0020] The piston may extend axially beyond the second port (in some embodiments, an outlet), thereby effectively closing or blocking the second port when the closure unit is in its closed position to inhibit backflow of medium through the second port into the chamber above the piston. Impeding the flow of solid particles from the second port when the closure unit is in its closed position may include inhibiting the backflow of solid particles when the second port is an outlet.

[0021] Optionally, one or more bleed passages may be defined in the outer surface of the barrier piston, for example as grooves extending axially in the radially outer surface of the piston, such that a bleed passage is defined by each of the grooves and the portion of the chamber side adjacent the groove.

[0022] The valve may include a housing and a sleeve positioned within the housing that defines at least a portion of the chamber.

[0023] The housing may define a cylinder having a central axis. The sleeve may be concentric with the housing cylinder and may define a cylinder in which the barrier piston is mounted. The sleeve may define a hole transverse (in some embodiments, perpendicular) to the central axis of the sleeve. The sleeve and the housing may provide support to the piston to reduce or prevent lateral movement that may occur when ore particles are trapped between a portion of the closure unit and the valve seat. In particular, the sleeve may absorb eccentric forces on the piston caused by solids trapped between the engagement surface of the piston and the valve seat (where the engagement surface abuts) when the piston is closed. The sleeve may also protect the chamber from high velocity ore particles that would otherwise impact the chamber when the closure unit moves to the closed position and the gap between the closure unit and the valve seat decreases (through which particle velocity increases).

[0024] The sleeve may define an opening having a width (or diameter) smaller than the width (or diameter) of the second port. The opening may be vertically offset from the opening such that a portion of the sleeve may act as a protruding wall extending upward from a lower portion (floor) of the second port. This protruding wall may prevent solid particles at the bottom of the second port (larger particles may settle due to gravity) from flowing toward the first port.

[0025] By using the sleeve as a liner for the chamber, the sleeve can be hard faced to resist wear since it is not a dynamically pressure loaded part.

[0026] During use, the media pressure deforms the housing, which reduces and expands the sleeve gap (i.e., the gap between the sleeve and the piston) as the pressure increases and decreases, respectively. A bleed passage connecting the cavity with the second port reduces damage to the sleeve and piston, for example, by allowing pressure to be relieved through an axially extending groove in the piston.

[0027] The valve seat, valve, and sleeve typically wear over time due to particle erosion. The piston stroke length and piston height are selected to provide sufficient overlap to cover (or close) the second port.

[0028] Optionally, the barrier piston comprises a downwardly sloping upper surface extending from a central portion of the barrier piston to a radially outer surface. The central portion may comprise a horizontal (e.g., horizontal when the valve is mounted with its longitudinal axis in a vertical orientation) surface or a surface having the same or different slope relative to the downwardly sloping upper surface. The downwardly sloping upper surface may comprise a conical downwardly sloping upper surface. The downwardly sloping upper surface directs particles trapped within the cavity toward an axially extending groove in the barrier piston such that small particles flow through the groove and are guided back into the flow path. The size of the particles that can be guided back into the flow path depends on the size of the groove. In one embodiment, the groove is 2 mm deep (i.e., extends 2 mm radially inward toward the longitudinal axis) and 15 mm long. In other embodiments, the groove may be 1 mm to 3 mm deep and may extend relative to the height of the barrier piston.

[0029] The downwardly sloping upper surface of the barrier piston may extend at an angle of at least 10, 12, 15, 18, 20, 25, 30, 35, 40, or 45 degrees relative to the horizontal.

[0030] The downwardly sloping upper surface of the barrier piston may extend at an angle of less than 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, or 35 degrees relative to the horizontal.

[0031] A preferred embodiment may have a downwardly sloping upper surface of the barrier piston that extends at an angle of 20 to 40 degrees relative to the horizontal.

[0032] The valve may be in the size range DN80 to DN500.

[0033] According to a second aspect of the present invention there is provided a pressure exchange chamber pump system comprising at least one pressure exchange chamber, a media or pump fluid valve arrangement in fluid communication with the pressure exchange chamber, and a drive fluid valve arrangement in fluid communication with the pressure exchange chamber at a location longitudinally spaced from the media valve arrangement, wherein the media valve arrangement and / or the drive fluid valve arrangement comprises at least one valve of the type described above.

[0034] The media valve arrangement may include a media inlet valve through which the pumped media can enter the pressure exchange chamber, and a media outlet valve through which the pumped media can be discharged from the pressure exchange chamber along a discharge pipe, riser, etc., where at least the media inlet valve is a valve of the type described above.

[0035] In a preferred embodiment of the present invention, the pressure exchange chamber pump system includes a plurality of pressure exchange chambers arranged in parallel and a supply arrangement including a feeder pump having a suction side and a discharge side connected in fluid communication with the medium inlet valve.

[0036] The components of the pressure exchange chamber pump system can be shipped in the form of a disassembled kit or a prefabricated kit for on-site assembly.

[0037] Thus, according to a third aspect of the present invention there is provided a pressure exchange chamber pump system kit comprising pressure exchange chamber defining means defining a plurality of elongated pressure exchange chambers; a plurality of media valve arrangements each connected or connectable to one of the pressure exchange chambers, each media valve arrangement including a media inlet valve by which a pumped medium can enter an associated pressure exchange chamber and a media outlet valve by which the pumped medium can be exhausted from the associated pressure exchange chamber; and a plurality of drive fluid valve arrangements connected or connectable to the pressure exchange chambers at locations longitudinally spaced from the media valve arrangements, each drive fluid valve arrangement including a drive fluid inlet valve through which drive fluid can enter an associated pressure exchange chamber and a drive fluid outlet valve by which drive fluid can be exhausted from the associated pressure exchange chamber, at least one of the valves being of the type described above.

[0038] According to a fourth aspect of the present invention, there is provided a valve closure unit for use with a valve of the type described above defining an elongated cavity having a pair of opposing ends and sides extending therebetween, a first opening in fluid communication with one end of the cavity, a second opening spaced from the first opening and in fluid communication with the cavity, a flow passage fluidly connecting the first and second openings, and a valve seat provided in the flow passage, the valve closure unit including: (i) a head configured to be positioned sealingly against the valve seat; and (ii) a barrier piston coupled to the head and defining a bleed passage between the barrier piston and the side, the barrier piston being receivable within the cavity for reciprocation between a closed position in which the head is positioned sealingly against the valve seat and an open position in which the head is spaced from the valve seat to allow flow through the flow passage.

[0039] The valve closure unit may include an annular elastomeric seal. The seal may be trapped and held between the barrier piston and the head.

[0040] The barrier piston may have a cylindrical radially outer surface.

[0041] The barrier piston may define a bleed passage between its outer surface and the elongated cavity. The bleed passage may comprise an annular gap. Alternatively, or additionally, the bleed passage may be defined by one or more channels defined in part by one or more longitudinally extending grooves. Each longitudinally extending groove may extend the entire length of the outer surface of the barrier piston. In a preferred embodiment of the invention, a plurality of circumferentially spaced grooves are provided in the radially outer surface of the barrier piston.

[0042] The elongated cavity may be lined by a sleeve.

[0043] According to a fifth aspect of the present invention, there is provided a method of modifying a pressure exchange chamber pump system comprising a plurality of pressure exchange chambers, each chamber including (i) a fluid container, (ii) a medium inlet valve by which a pumped medium can enter an associated fluid container, (iii) a medium outlet valve by which the pumped medium can be exhausted from the associated fluid container, (iv) a drive fluid inlet valve by which a drive fluid can enter the associated fluid container, and (v) a drive fluid outlet valve by which the drive fluid can be exhausted from the associated fluid container, the method comprising removing at least one valve and replacing it with the above-mentioned valve.

[0044] The method may in particular comprise removing each medium inlet valve and replacing it with the above-mentioned valve.

[0045] According to a sixth aspect of the present invention, there is provided a valve comprising a first port, a second port spaced from the first port, a flow path fluidly connecting the first and second ports, a valve seat positioned within the flow path, a closure unit movable between a closed position positioned against the valve seat to inhibit flow of a medium through the flow path and an open position to allow flow of a medium through the flow path, and a barrier piston configured to inhibit passage of solid particles that may interfere with movement of the closure unit into a closure unit receiving cavity in which at least a portion of the closure unit is received when the closure unit is in its open position and / or to inhibit flow of a medium from the second port when the closure unit is in its closed position. [Brief description of the drawings]

[0046] These and other aspects of the invention will now be described, by way of example, with reference to the accompanying schematic drawings.

[0047] [Figure 1] FIG. 1 shows a schematic diagram of a pressure exchange chamber pump system according to an embodiment of the present invention. [Diagram 2] FIG. 2 shows a longitudinal section through a valve according to another embodiment of the invention forming part of the pressure exchange chamber pump system of FIG. 1, the closure unit of the valve being shown in the closed position. [Diagram 3] FIG. 3 shows a cross-sectional view similar to FIG. 2, with the closure unit of the valve in the open position. [Figure 4] FIG. 4 shows a three-dimensional view of a barrier piston forming part of the valve of FIGS. [Diagram 5] FIG. 5 is a partial cross-sectional view of a valve according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] In FIG. 1 of the drawings, the numeral 10 generally refers to a portion of a pressure exchange chamber (PEC) pump system according to an embodiment of the present invention.

[0049] The PEC pump system 10 includes three PECs 11.1, 11.2, 11.3 defined by lengths of pipes 12, 14, 16, each having a media or pumped fluid valve arrangement 18, 20, 22, respectively, connected at one end thereof and a drive fluid valve arrangement 19, 21, 23, respectively, connected at its other end, i.e., in this embodiment, spaced longitudinally from the media valve arrangements 18, 20, 22. However, in other embodiments, different configurations of PECs (such as loops) may be used such that the media valve arrangements 18, 20, 22 may be located proximate the drive fluid valve arrangements 19, 21, 23.

[0050] Each media valve arrangement 18, 20, 22, according to an embodiment of the invention, as described in detail below, comprises a media inlet valve 18.1, 20.1, 22.1, by which the pumped medium can enter the associated pipe 12, 14, 16, and a media outlet valve 18.2, 20.2, 22.2, by which the pumped medium can be discharged from the pipe 12, 14, 16 along the discharge pipe 24. Similarly, each drive fluid valve arrangement 19, 21, 23 includes an inlet valve.

[0051] 19.1, including inlet valves 21.1, 23.1 through which the drive fluid can be admitted into the associated pipes 21.2, 23.2, and outlet valves 19.2, 21.2, 23.2 by which the drive fluid can be discharged from the associated pipes.

[0052] The PEC pump system 10 further comprises a supply arrangement, a part of which is generally indicated by the reference numeral 26, configured to supply the medium to be pumped to the medium inlet valves 18.1, 20.1, 22.1 as will be explained in more detail below.

[0053] 18.1, 20.1, 22.1 are described in more detail below. The supply arrangement 26 includes a supply or delivery pump (not shown in more detail). The supply arrangement 26 further includes a pipe 32 connected to a source of ore particles, and three supply lines 35, 36, 37, each of which has an upstream end and a downstream end connected to the pipe 32. The downstream ends of the supply lines 35, 36, 37 are connected to the medium inlet valves 18.1, 20.1, 22.1, respectively. Thus, in use, the pumped medium is transported through the pipe 32 and the supply lines 35, 36, 37 to the medium inlet valves 18.1, 20.1, 22.1.

[0054] In use, with the media inlet valves 18.1, 20.1, 22,1 open and the corresponding drive fluid outlet valves 19.2, 21.2, 23.2 open, media enters the associated pipes 12, 14, 16, displacing the drive fluid out of the associated drive fluid outlet valves 19.2, 21.2, 23.2. When a desired amount of media has entered the pipes 12, 14, 16, the media inlet valves 18.1 and drive fluid outlet valves 19.2 are closed. The media outlet valves 18.2, 20.2, 22.2 and drive fluid inlet valves 19.1, 21.1, 23.1 are opened so that high pressure drive fluid enters the pipes at high pressure, displacing the media through the respective media outlet valves 18.2, 20.2, 22.2 and thereby out of the pipes 12, 14, 16 and into the discharge riser 24.

[0055] Once the medium has been discharged from the pipes 12, 14, 16, the associated medium outlet and drive fluid inlet valves close and the medium inlet and drive fluid outlet valves open, again filling the pipes 12, 14, 16 with medium in the manner described above.

[0056] To allow for near continuous pumping, the operation of the valves of the different PECs 11.1, 11.2, 11.3 are staggered so that the filling and discharging of the medium into the pipes 12, 14, 16 occurs nearly continuously.

[0057] The medium inlet valves 18.1, 20.1, 22.1 are substantially identical and, for the sake of simplicity, only the medium inlet valve 18.1 will be described in detail below with reference to Figures 2 to 5 of the drawings.

[0058] Valve 18.1 includes a hollow housing 40 partially defining a cylindrical chamber 42 having a circular cross section, and a cap 43 above housing 40. Chamber 42 is defined by a bottom 44, a top 46, and a side 48 extending between bottom 44 and top 46. Top 46 is defined by the underside of cap 43. A cylindrical sleeve or liner 55 is positioned within the housing, with a radially inner surface of liner 55 abutting side 48 and extending into cap 43. A first port 50 extends through housing 40 into bottom 44 of chamber 42. A second port 52 extends through housing 40 and liner 55 into chamber 42 through side 48 at a location spaced from port 50. In this embodiment, port 50 forms an inlet and port 52 forms an outlet. However, in other embodiments, port 52 can be an inlet and port 50 an outlet.

[0059] An annular seat ring 54 is mounted in the chamber 42 adjacent the inlet 50. In the embodiment shown, a sleeve or liner 55 extends between the seat ring 54 and the cap 43. An opening 57 is provided in the liner 55 and is aligned with the port 52. The ports 50, 52 are fluidly connected by a flow path, a portion of which is formed by a passage 56 (see FIG. 3) that extends through the seat ring 54. The passage 56 includes a cylindrical portion 58 (having a circular cross section) (FIG. 3) in fluid communication with the port 50, and a frusto-conical portion 60 (FIG. 3) that opens into the chamber 42. A surface 61 of the frusto-conical portion 60 forms a valve seat, as described in more detail below.

[0060] The valve 18.1 further comprises a closure unit generally indicated by the reference numeral 62 and an actuator, a part of which is generally indicated by the reference numeral 64.

[0061] Valve 18.1 extends along a longitudinal axis 66 that is coaxial with cylindrical chamber 42, inlet port 50, and liner 55, and perpendicular to outlet port 52. In this embodiment, valve 18.1 is generally vertically oriented (i.e., longitudinal axis 66 is vertical), with first port 50 being lower than second port 52.

[0062] The closure unit 62 includes (i) an annular seal 68, typically formed from an elastomeric material, having a frustoconical sealing surface 70 that complements the valve seat 61, (ii) a head 72, and (iii) a barrier piston 74.

[0063] The seal 68 is sandwiched between a head 72 and a barrier piston 74, which are secured together by a retaining stud bolt 76 that extends axially through the head 72 and piston 74 and a retaining nut 78 that is attached to an end portion of the stud bolt 76, urging the head 72 and piston 74 inwardly toward one another and holding the seal 68 in place. The stud bolt 76 and the retaining nut 78 may also be considered part of the closure unit 62, although different techniques for coupling the seal 68, head 72, and barrier piston 74 together may be used in other closure units.

[0064] Head 72 defines a frustoconical surface 80 that complements valve seat 61 .

[0065] The barrier piston 74 has a cylindrical outer surface 75 with dimensions selected to be snugly receptive to reciprocation within the sleeve 55 with only a small clearance between the outer surface 75 of the piston 74 and the radially inner surface 59 of the sleeve 55. In some embodiments, the small clearance may include an annular gap that functions as a bleed passage.

[0066] The actuator is typically in the form of a linear actuator, such as a hydraulic piston and cylinder arrangement, that includes a coaxially extending elongated actuator rod 82 that extends through the cap 43 at the top of the housing 40 and is connected to a stud bolt 76 to facilitate movement of the closure unit 62 and piston 74 between a closed position (shown in FIG. 2) and an open position (shown in FIG. 3).

[0067] As best seen in Figure 4 of the drawings, a plurality of circumferentially spaced, axially extending grooves 84 are provided in the radially outer surface 75 of the piston 74 which, together with the radially inner surface 59 of the sleeve 55 (or side 48 for embodiments in which a sleeve is not used), form a bleed passage to prevent the creation of a vacuum, as will be described in more detail below. Additionally, the grooves 84 allow particulates to exit the cavity 85 and settle towards the second port 52, thereby preventing blockage of the cavity 85. The grooves 84 also assist in reducing viscous forces during movement of the piston 74.

[0068] The barrier piston 74 defines an upper portion 86 having a flat central portion 88 that defines a bore 90 for receiving the actuator rod 82, and an outer portion 92 that slopes downwardly (toward the valve seat 61 in this embodiment) as it extends toward the radially outer surface 75. The outer portion 92 may be referred to as the downwardly sloping portion when the valve is mounted in an upright orientation, as shown in Figures 2 and 3. In this embodiment, the downwardly sloping portion 92 extends at an angle of 25 to 35 degrees relative to the horizontal (i.e., perpendicular to the longitudinal axis 66).

[0069] As mentioned above, the medium typically comprises a liquid (such as water) in which solid particles are entrained, some of the solid particles may be small (fine), others may be of medium size, and others may be relatively large.

[0070] 2 of the drawings, in the closed position of the valve 18.1, the sealing surface 70 and the frustoconical surface 80 of the head 72 abut sealingly against the valve seat 61 formed by the frustoconical portion 60 of the seat ring 54, preventing the flow of medium through the valve. In this regard, the seal 68 projects radially beyond the surface 80, such that the sealing surface 70 of the seal 68 abuts the valve seat 61 before the frustoconical surface 80, when the closure unit 62 is moving towards its closed position. Thanks to the seal 68 being made of an elastomeric material, a reliable seal can be formed even if small solid particles are trapped between the surface 80 and the valve seat 61.

[0071] It is important to note that in the closed position, the piston 74 projects axially upwardly beyond the port 52 and opening 57 into the chamber 42 from a position below the lower edge of the opening 57, thus effectively closing the opening 57 and forming a barrier that resists the flow of material or medium through the port 52 and into the chamber 42, even when the valve is in its closed position. The portion of the chamber 42 above the piston 74 forms a closure unit receiving cavity, generally indicated by the reference numeral 85, into which at least a portion of the closure unit 62 (e.g., the piston 74) is moved when the valve is in the open position as described below.

[0072] Referring to Figure 3 of the drawings, to open valve 18.1, rod 82 is moved in the direction of arrow 96 so that piston 74 and closure unit 62 are withdrawn upwardly into the portion of chamber 42 defining closure unit receiving cavity 85, thereby fluidly connecting inlet 50 and outlet 52 and permitting the free flow of medium through valve 18.1.

[0073] To close the valve 18.1, the piston 74 and closure unit 62 are moved in a direction opposite to the direction of the arrow 96 to the closed position shown in Figure 2 of the drawings.

[0074] Due to the sliding fit of the piston 74 within the chamber 42, and in particular the limited clearance between the radially outer surface 75 of the piston 74 and the inner surface 59 of the liner 55, large solid particles cannot pass between the piston 74 and the liner 55 and into the portion of the cavity above the piston 74 where they could potentially accumulate and inhibit movement of the piston 74 and the closure unit 62 to its open position.

[0075] The provision of the grooves 84 allows for a restricted flow of medium into the chamber 42 (the closure unit receiving cavity 85) above the piston 74 when the piston 74 and the closure unit 62 are moving towards the closed position, and out of the closure unit receiving cavity 85 when the piston 74 and the closure unit 62 are moving towards the open position. This avoids any significant pressure difference between the closure unit receiving cavity 85 and the second port 52. Without this pressure balance, a pressure reduction zone could be created above the piston 74, which could resist the movement of the closure unit 62 towards its closed position. Similarly, a pressure increase zone could be created above the piston 74, which could resist the movement of the closure unit 62 towards its open position. The dimensions of the grooves are selected to inhibit the passage of large solid particles therethrough. In this embodiment, each groove 84 has a width of 12.5 mm and a maximum depth of about 1.5 mm. The number and depth of the grooves required may increase for larger diameters of the barrier piston. In alternative embodiments of the invention, if desired, grooves may alternatively or additionally be provided in the radially inner surface 59 of the liner 55 and may have any convenient cross-sectional shape or configuration.

[0076] The barrier piston 74, head 72, seal 68, stud bolt 76, and nut 78 together may form a valve closure unit, which may be replaced as a unit if the seal 68 or one of the other components wears or fails. Similarly, the liner 55 and seat ring 54 may be replaceable wear items. Wear parts such as the valve seat ring 54, valve head 72, barrier piston 74, liner 55, and valve seat 68 are easily replaced by removing the top cover (not shown) and loosening and removing the retaining nut 78.

[0077] Valve 18.1 is particularly suitable for use in environments where the medium contains solid particles, such as in pressure exchange chamber pump systems, and will provide reliable operation thereof.

[0078] Reference is now made to Figure 5, which is a partial cross-sectional view of a valve 118.1 according to another embodiment of the invention. Valve 118.1 is substantially identical to valve 18.1, except that valve 118.1 has a sleeve (or liner) 155 (instead of sleeve 55) that defines an opening 157 having a diameter smaller than that of second port 52. The opening 157 is vertically offset from the opening 52 such that a portion of the sleeve 157 acts as a protruding wall 163 that extends upward from the lower portion (floor) of second port 52. This protruding wall 163 prevents solid particles at the bottom of second port 52 (where larger particles may settle due to gravity) from flowing toward first port 50. When second port 52 is an outlet, this prevents backflow toward first port (inlet) 50.

[0079] Although the valve has been described with particular reference to its application as a medium inlet valve in a pressure exchange chamber pump system, it will be appreciated that it would be suitable for use in many other applications. In particular it may be used as a medium outlet valve, a drive fluid inlet valve, and / or a drive fluid outlet valve. Indeed, a valve according to the invention may be used in applications other than PECs.

[0080] First, it will be appreciated that a pressure exchange chamber pump system can be constructed in accordance with the present invention. The components of the pressure exchange chamber pump system can be shipped prefabricated or in kit form for on-site assembly. Alternatively, a prior art pressure exchange chamber pump system can be modified by replacing one or more of the valves with valves in accordance with the present invention. [Explanation of symbols]

[0081] Pressure Exchange Chamber (PEC) Pump System 10 PEC 11.1, 11.2, 11.3 Pipes 12, 14, 16 Media valve arrangement 18, 20, 22 Media inlet valve 18.1, 20.1, 22.1, 118.1 Media outlet valve 18.2, 20.2, 22.2 Drive fluid valve arrangement 19, 21, 23 Drive fluid inlet valve 19.1, 21.1, 23.1 Drive fluid outlet valve 19.2, 21.2, 23.2 Discharge riser (pipe) 24 Supply Distribution 26 Pipe 32 Supply lines 35, 36, 37 Hollow Housing 40 Cylindrical chamber 42 Cap 43 Bottom (of chamber) 44 Top (of chamber) 46 Side (of chamber) 48 Ports 50, 52 Seat ring 54 Liner (sleeve) 55, 155 Aisle 56 Opening 57, 157 Cylindrical section 58 Inner surface (of liner) 59 Cone-shaped part 60 Valve seat 61 Closure Unit 62 Actuator 64 Longitudinal axis 66 Seal 68 Seal Surface 70 head 72 Piston 74 outer surface 75 Stud bolt 76 Retaining nut 78 Cone-shaped surface 80 Actuator Rod 82 groove 84 Closed unit receiving cavity 85 upper part 86 central part 88 Hole (center) 90 outer part 92 Arrow 96 (Sleeve) protruding wall 163

Claims

1. A first port; a second port spaced apart from the first port; and a flow path connecting the first port and the second port in fluid communication and allowing a medium containing solid particles to pass therethrough; a valve seat positioned within the flow passage; a closure unit movable between a closed position against the valve seat to obstruct flow of the medium through the flow passage and an open position to permit flow of the medium through the flow passage; and a cavity configured to receive at least a portion of the closure unit, the closure unit further comprising: (i) a barrier piston configured to impede flow of the solid particles from the second port when the closure unit is in its closed position, thereby impeding passage of such solid particles into the cavity; (ii) one or more bleed passages connecting the cavity in fluid communication with the second port and providing a pressure balancing arrangement that reduces a pressure differential therebetween; and (iii) a downwardly sloping top extending from a central portion of the barrier piston to an outer surface of the barrier piston to allow particulates within the cavity to settle through the one or more bleed passages towards the second port.

2. 2. The valve of claim 1, defining a cylindrical chamber having a first end, a second end and a side extending therebetween, said first port opening into said chamber through said first end and said second port leading from said chamber through said side at a location spaced from said first end.

3. 3. The valve of claim 2, wherein the first end is an operable bottom end of the chamber, the valve seat is frusto-conical and tapers inwardly, and the closure unit is axially movable within the chamber between its open and closed positions.

4. 4. The valve of claim 3, wherein the annular gap between the barrier piston and an inner surface defining the side of the chamber is less than 2 mm.

5. 5. The valve of claim 4, wherein when the closure unit is in its closed position, the piston extends axially beyond the second port to obstruct flow of the medium from the second port into the chamber above the piston.

6. 6. The valve of claim 5, wherein the one or more bleed passages are defined by one or more axially extending grooves provided in a radially outer surface of the piston.

7. 7. The valve of claim 6, wherein the piston includes a conical upper surface for directing trapped particles in the cavity toward the axially extending groove in the piston such that the particles are guided back into the flow path.

8. 8. The valve of claim 1, further comprising a housing defining a cylinder having a central axis, and a sleeve concentrically mounted within the housing cylinder and defining a bore transverse to the central axis of the sleeve.

9. 9. The valve of claim 8, wherein the sleeve bore is offset from a center of the second port and defines a wall that protrudes into the second port.

10. At least one pressure exchange chamber; 10. A pressure exchange chamber pump system comprising a medium valve arrangement in fluid communication with the pressure exchange chamber and a drive fluid valve arrangement in fluid communication with the pressure exchange chamber at a position longitudinally spaced from the medium valve arrangement, wherein the medium valve arrangement and / or the drive fluid valve arrangement comprises at least one valve according to any one of claims 1 to 9.

11. 1. A valve closure unit for use with a valve defining an elongated cavity having a pair of opposing ends and sides extending therebetween, a first opening in fluid communication with one end of the cavity, a second opening spaced from the first opening and in fluid communication with the cavity, a flow passage connecting in fluid communication the first and second openings, and a valve seat provided within the flow passage, (i) a head configured to be sealingly positioned against the valve seat; (ii) a barrier piston coupled to the head and defining a bleed passage between the barrier piston and the side, the barrier piston being receivable within the cavity for reciprocation between a closed position in which the head is positioned sealingly against the valve seat and an open position in which the head is spaced from the valve seat to allow flow through the flow passage.

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