Dump valve arrangement

Abstract

A dump valve configuration for use in a discharge riser is described. The dump valve configuration comprises a settling chamber configured to be coupled to the bottom of a discharge riser; a dump valve operable to allow or prevent the flow of a medium from the discharge riser to the settling chamber; a compression input to the settling chamber to pressurize the settling chamber before opening the dump valve to reduce the pressure difference between the settling chamber and the bottom of the discharge riser; a depressurization output to reduce the pressure in the settling chamber after the dump valve is opened; and an outlet to empty the contents of the settling chamber after the pressure in the settling chamber has been sufficiently reduced.

Description

Technical Field

[0001] The present invention relates to dump valve arrangements, particularly to dump valve arrangements for use in a hydraulic ore hoist system (HOHS). This further relates to a method of operating a dump valve arrangement, particularly in a HOHS.

Background Art

[0002] In a HOHS, a pump arrangement pumps ore into and up a discharge riser connected thereto. One such use of a HOHS is in undersea mining.

[0003] One type of pump arrangement used, which is particularly suitable for use with a pump medium containing relatively large particles, is a pressure exchange chamber (PEC)-based pump system. A PEC pump system typically includes at least one pressure chamber (sometimes in the form of an elongated pipe) having a medium or pump feed fluid valve arrangement at one end and a drive fluid valve arrangement at the other end. The medium valve arrangement includes a medium inlet valve capable of admitting the medium to be pumped into the PEC and a medium outlet valve connected in fluid communication with the discharge riser to enable the pumped medium to be supplied into the discharge riser. Similarly, the drive fluid valve arrangement includes a drive fluid inlet valve for admitting high-pressure drive fluid into the PEC via a drive riser and a drive fluid outlet valve for discharging the drive fluid from the PEC.

[0004] In use, the medium to be pumped can be supplied to the medium inlet valve at a relatively low pressure by a medium delivery pump such as a centrifugal pump. When the medium inlet valve is open and the drive fluid outlet valve is open, the medium enters the pressure chamber and the drive fluid is discharged from the pressure exchange chamber through the drive fluid outlet valve.

[0005] When the PEC is filled with the medium, i.e., when the desired amount of medium enters the PEC, the medium inlet valve and the drive fluid outlet valve are closed. The medium outlet valve and the drive fluid inlet valve are opened to allow the drive fluid to enter the PEC at high pressure and to discharge the medium from the PEC into the discharge riser through the medium outlet valve. The exact sequence and timing related to the opening and closing of the valves can be modified to optimize the operation of the pump system.

[0006] When the medium is discharged from the PEC, the medium outlet valve and the drive fluid inlet valve close, and the medium inlet valve and the drive fluid outlet valve open to refill the PEC with medium in the manner described above.

[0007] Typically, a PEC pump system includes multiple chambers arranged in parallel (usually in the form of pipes, but not necessarily), and the order of operation of the medium or pump-pressure fluid valve arrangement and drive fluid valve arrangement is selected so that the medium is continuously supplied to the discharge riser. As a result, the medium in the riser moves continuously upward, and solid particles remain suspended in the liquid and are transported upward through the discharge riser.

[0008] The discharge riser can be relatively long, depending on the depth at which mining operations are carried out, and can be several thousand meters long.

[0009] If, for any reason, such as a system trip, the supply of media to the discharge riser is interrupted, the solids in the media contained within the discharge riser may begin to settle under the influence of gravity, potentially forming a self-blocking plug at the bottom of the discharge riser. If this occurs, it may not be possible to restart the HOHS without removing and cleaning the discharge riser, which is time-consuming, inefficient, and very expensive.

[0010] In an attempt to avoid plug formation, prior art systems employ a full-bore dump valve arrangement with a dump valve directly connected to the discharge riser near its bottom to communicate with the flow. In the event of a system trip or dump event, the dump valve opens, discharging the medium from the discharge riser.

[0011] One problem with this configuration is that if the valve opens too late, there is a risk that the discharge riser will become blocked when the settled solids accumulate against the dump valve before the valve opens sufficiently to allow the solids contained in the medium to pass through.

[0012] Another problem with this configuration is that if the valve opens too rapidly, the discharge riser may depressurize explosively, causing a violent water hammer pulse to propagate through the discharge riser, and the dynamic force could have a destructive effect on the HOHS. In addition, the very high velocity of the fluid flow through the dump valve when fully open can lead to rapid and considerable erosive wear, making it difficult to reuse the dump valve after a dump event.

[0013] An object of embodiments of the present invention is to provide means that can improve this problem, or to provide useful alternatives. [Overview of the Initiative]

[0014] This summary is provided to introduce a selection of concepts that will be further described in the embodiments for carrying out the following invention. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended to be used as an aid to limit the scope of the claimed subject matter.

[0015] In this application, sequential numbers (first, second, third, etc.) are arbitrarily assigned herein and used to distinguish parts, and do not indicate any particular order, sequence, or importance.

[0016] The features listed for one embodiment are intended to be options for use in other embodiments, unless such combinations are impossible.

[0017] According to a first embodiment, a dump valve arrangement is provided for use in a discharge riser, the dump valve arrangement comprising: (i) a settling chamber configured to be coupled to the lower part of a discharge riser; (ii) a dump valve operable to allow or prevent the flow of a medium from the discharge riser to the settling chamber; (iii) a compression input for pressurizing the settling chamber before opening the dump valve to reduce the pressure difference between the settling chamber and the lower part of the discharge riser; (iv) a depressurization output for reducing the pressure in the settling chamber after the dump valve has been opened; and (v) an outlet for emptying the contents of the settling chamber after the pressure in the settling chamber has been sufficiently reduced.

[0018] It is preferable that the dump valve is displaceable between a closed position that obstructs the flow of medium from the discharge riser to the sedimentation chamber and an open position that connects the discharge riser to the sedimentation chamber in flow communication.

[0019] The dump valve may be located at the top of the sedimentation chamber, at the bottom of the discharge riser, or in the coupling (such as a pipe) between the sedimentation chamber and the discharge riser.

[0020] Optionally, the outlet includes a discharge valve, which is displaceable between a closed position that obstructs the flow of medium from the sedimentation chamber through the outlet and an open position that allows the flow of medium from the sedimentation chamber through the outlet.

[0021] Optionally, the compression input is in fluid communication with the high-pressure output from the drive fluid riser. Optionally, the compression input is in fluid communication with the high-pressure output from the pressure exchange chamber supplying the discharge riser. In such embodiments, the sedimentation chamber is pressurized when both the dump valve and the discharge valve are closed, maintaining the pressure in the sedimentation chamber at a pressure approximately corresponding to the pressure at the bottom of the discharge riser.

[0022] The compression input can pressurize the sedimentation chamber to substantially the same pressure as the pressure at the bottom of the discharge riser.

[0023] Optionally, the depressurization output includes a depressurization valve that fluidly communicates with the sedimentation chamber, which allows for controlled depressurization of both the sedimentation chamber and the connected discharge riser when opening the dump valve, before opening the discharge valve.

[0024] In this embodiment, the dump valve arrangement provides controlled pressure reduction and prevents a high pressure difference from occurring on either side of the valve when the valve is open or partially open in the presence of solids. Such a pressure difference can cause wear and / or blockage. The dump valve moves in the presence of some solids, but there is no significant pressure difference. The pressure reducing valve opens when a pressure difference exists, but there is no substantial amount of solid. The discharge valve opens when there is no substantial pressure difference and there is no substantial amount of solid.

[0025] The dump valve configuration can be used in conjunction with a discharge riser supplied by any convenient pump configuration, such as a pressure exchange chamber.

[0026] A hydraulic ore hoist system is provided, comprising (i) a hydraulic discharge riser having a lower end and an upper end; (ii) an inlet connected to the discharge riser and in flow communication with a pressurized supply source of the medium being hoisted; and (iii) a dump valve arrangement according to the first embodiment, and configured to allow controlled depressurization of the discharge riser during a dump event before the solid is discharged from the system.

[0027] In a typical embodiment, during normal operation of the hydraulic ore hoist system (HOHS), the dump valve, discharge valve, and depressurization output are closed, and the HOHS operates in the conventional manner as described above. The medium to be hoisted is supplied under pressure to the discharge riser through the inlet and flows upward within the discharge riser in the conventional manner. The settling chamber is separated from the discharge riser by the dump valve and pressurized to a pressure approximately corresponding to the pressure at the bottom of the discharge riser.

[0028] However, if a trip occurs where the supply of the medium to the discharge riser is interrupted or the supply rate significantly decreases such that solids in the medium within the discharge riser settle downward under the influence of gravity, the dump valve opens.

[0029] When the dump valve opens, the solids in the settled medium do not settle to the bottom of the discharge riser. Instead, they pass through the dump valve and enter the settling chamber, preventing the accumulation of solids at the bottom of the discharge riser. By maintaining the discharge riser and the settling chamber at approximately the same pressure, no (or only a relatively small shock wave) is generated when the dump valve is opened to connect the settling chamber in fluid communication with the discharge riser.

[0030] When the dump valve is open, the pressure reducing valve opens and the pressure within the settling chamber can be decreased in a controlled manner that avoids the generation of shock waves that could cause damage. After the pressure reducing valve is open and the pressure within the settling chamber has sufficiently decreased, the discharge valve can be opened, thereby enabling the solids to be discharged from the settling chamber.

[0031] When the discharge valve is open, the pressure reducing valve can optionally be closed again. This prevents solids that could wear this valve and potentially clog it from passing through the pressure reducing valve.

[0032] To control the downward velocity of the discharge riser during depressurization, an optional additional flow resistance may be used downstream of the upper end of the sinking chamber. The optional additional flow resistance can be located anywhere in the flow path from the sinking chamber through the discharge valve to the outlet of the dump valve. The use of such flow resistance is particularly advantageous in onshore systems such as HOHS from underground mines. In underwater HOHS, the ambient pressure around the bottom of the discharge riser is high due to hydrostatic pressure, so the discharge riser discharges the medium into a pressurized underwater environment. In contrast, in onshore HOHS, the ambient pressure around the bottom of the discharge riser is low (atmospheric pressure), so the discharge riser generally discharges the medium at atmospheric pressure. This can result in very high flow velocities of the medium as it is discharged. The additional flow resistance will limit the downward velocity of the discharge riser to an acceptable level.

[0033] The HOHS may include a pump arrangement connected to the inlet of the discharge riser and configured to supply pressurized medium to the discharge riser. The pump arrangement may be a PEC pump system.

[0034] The settling chamber may be positioned below the discharge riser (and, in some embodiments, coaxially aligned with it) so that when the dump valve is opened, the settling chamber effectively forms a downward extension of the discharge riser. This allows solid material settling in the discharge riser to flow downward into the settling chamber under the influence of gravity.

[0035] The sedimentation chamber may be elongated, spherical, convoluted, or have any other convenient shape.

[0036] Preferably, the length and width (which may be the diameter) of the sedimentation chamber are selected such that the time it takes for the medium in the discharge riser to reach the discharge valve exceeds the time it takes to depressurize the sedimentation chamber.

[0037] The compression input may include, or be coupled to, a pressurized bypass line extending between the sedimentation chamber and the pressurized drive fluid or pumped medium of the PEC. The pressurized bypass line bypasses the dump valve to ensure that the sedimentation chamber is pressurized to a pressure similar to that of the lower part of the discharge riser. An advantage of using a drive fluid to pressurize the sedimentation chamber is that it inherently does not contain solid particles that could potentially clog the balance line.

[0038] The depressurization output may be configured to allow controlled depressurization of the sedimentation chamber, and accordingly, when both the dump valve and the discharge valve are fully open and the depressurization output is operating (e.g., if the depressurization output includes a depressurization valve, that valve is open), it may be configured to guide the backflow velocity of solids in the medium within the discharge riser (i.e., the velocity of solids falling under the influence of gravity) into a steady-state dump flow. In one embodiment, the depressurization valve may comprise a cone valve that, as it moves from a closed position to an open position, provides an increasing cross-sectional area for the medium flow, thereby providing a desirable gradual increase in flow to enable controlled depressurization.

[0039] Optionally, at least one of the dump valve, discharge valve, and pressure reducing valve is biased toward its open position and includes a retaining means configured to ensure fail-safe operation of the valve by removably holding the valve in its closed position to ensure safe operation of the valve fails. Optionally, each of the dump valve, discharge valve, and pressure reducing valve is biased toward its open position but is held in its closed position during normal HOHS operation (i.e., when there is no dump event).

[0040] Optionally, the dimensions of the settling chamber are selected such that the pressure reducing valve and the discharge valve can be moved to the fully open position before the settling solid reaches the discharge valve. In particular, the settling chamber may be long enough such that the time it takes for the solid entering the chamber to reach the bottom of the chamber is longer than the time it takes for the pressure reducing valve and the discharge valve to move to their fully open positions.

[0041] The sedimentation chamber may have a larger diameter than the discharge riser to provide a larger volume for a given sedimentation length, thereby increasing the volume of medium that can be discharged from the discharge riser into the sedimentation chamber during decompression, and thereby providing additional time for decompression to occur.

[0042] A third aspect provides a method for discharging a medium from a discharge riser during a trip event, the method comprising: (i) pressurizing a sedimentation chamber coupled to the bottom of a discharge riser; (ii) detecting a trip event leading to sedimentation of a solid in the discharge riser; (iii) discharging the medium from the discharge riser into the sedimentation chamber; (iii) reducing the pressure difference between the sedimentation chamber and a dump area outside the sedimentation chamber; and (iv) discharging the medium culture medium from the sedimentation chamber into the dump area until a removal criterion is met.

[0043] Optionally, the removal criteria include either (i) the majority of the settled solids have been removed from the discharge riser, or (ii) all of the medium has been removed from the discharge riser.

[0044] The step of pressurizing the sedimentation chamber may include pressurizing the sedimentation chamber to the pressure at or near the pressure at the bottom of the discharge riser.

[0045] The process of detecting a trip event may be carried out by a controller coupled to a pressure exchange chamber that supplies a medium to the discharge riser.

[0046] The step of detecting a trip event may be active (or direct), for example, by the control system detecting a condition indicating a trip event. Alternatively, or additionally, the step of detecting a trip event may be passive (or indirect), for example, by detecting a loss of power.

[0047] The process of reducing the pressure difference between the sedimentation chamber and the dump area outside the sedimentation chamber may be carried out using a pressure reducing output. The pressure reducing output may include a pressure reducing valve.

[0048] The dump area may be located on the seabed below the discharge riser. If the HOHS is installed on land, the dump area may be a pit, a wastewater pond, or any other convenient location.

[0049] According to a fourth aspect, a method is provided for operating a hydraulic ore hoist system having a discharge riser and a dump valve arrangement coupled thereto, the method comprising: (i) detecting a trip event leading to the sedimentation of solids in the discharge riser; (ii) reducing the pressure difference between the lower part of the discharge riser and the ambient pressure around the lower part of the discharge riser; and (iii) discharging the medium from the discharge riser and the dump valve arrangement after the pressure difference has been reduced to less than a predetermined pressure difference.

[0050] According to a fifth aspect, a method is provided for removing a medium from a discharge riser in a hydraulic ore hoist system that is experiencing a trip event, the method comprising pressurizing a settling chamber; detecting a trip event; opening a primary clearing valve to allow the medium to flow from the discharge riser into the settling chamber; depressurizing the settling chamber to allow the settling chamber pressure to approximate the ambient pressure outside the settling chamber; and opening a secondary clearing valve to allow the medium in the settling chamber to flow out of the settling chamber.

[0051] According to a sixth aspect, a hydraulic ore hoist system kit is provided, which includes a hydraulic discharge riser having a lower end and an upper end; an inlet at the lower end or adjacent to the lower end connected to the discharge riser; a pump arrangement connectable to the inlet of the discharge riser and configured to supply a pressurized medium to the discharge riser; and a dump valve arrangement connectable to the discharge riser and configured to allow controlled depressurization of the discharge riser during a dump event before solid is discharged from the system when in use.

[0052] The dump valve arrangement according to the first embodiment can be used with a riser that transports the settling mixture vertically, regardless of which pump arrangement is used to supply the settling mixture to the riser.

[0053] Herein, these and other embodiments of the present invention will be described with reference to the attached schematic drawings as examples. [Brief explanation of the drawing]

[0054] [Figure 1] This is a schematic arrangement of HOHS including the dump valve arrangement according to one embodiment of the present invention. [Figure 2] A portion of the dump valve arrangement in Figure 1 is shown at an enlarged scale. [Modes for carrying out the invention]

[0055] In Figure 1 of the drawings, reference numeral 10 refers generally to a part of a hydraulic ore hoist system ("HOHS") pump system according to one embodiment of the present invention. The HOHS 10 comprises a pressure exchange chamber (PEC) 12. In a typical embodiment, the entire PEC 12 is located at an elevation lower than the final delivery point to which the medium is delivered by the pump system 10. The medium typically contains ore particles suspended in a liquid. In this embodiment, the HOHS 10 is a submarine system, the PEC 12 is located on or near the seabed, the ore contains polymetallic nodules, and the liquid carrier contains seawater. Other embodiments may be land-based or may be at the bottom of a freshwater lake or estuary.

[0056] The PEC 12 is coupled to a drive fluid pump 14 via a drive fluid riser 16. The drive fluid pump 14 (which is a positive displacement pump in this embodiment) is located on a surface 18 at an elevated level, and a discharge riser 20 extends from the PEC 12 to the surface 18. The discharge riser 20 delivers the medium raised from the PEC 12 to an ore removal station 22, which dewaters the ore (polymetal knots in this embodiment) in the medium.

[0057] The PEC12 comprises a pump chamber (not shown in detail) having valve arrangements 24, 26 (referred to as the drive fluid valve arrangement 24 and the pump-pressure-delivered medium valve arrangement 26) at each end thereof. The operation of the PEC12 is known. A preferred PEC is described in PCT application number PCT / IB2019 / 055957 in the name of the applicant, Wir Minerals Netherlands BV. Briefly, the PEC12 is filled with medium at a relatively low pressure by a filling mechanism 28 such as a centrifugal pump. The PEC12 is then pressurized, and a high-pressure drive fluid from the drive fluid pump 14 pushes the medium in the PEC12 out of the PEC medium output line 30, raising the discharge riser 20 and pushing it to the surface 18.

[0058] A unique feature of the HOHS10 is the presence of a dump valve arrangement 32 located at the bottom of the discharge riser 20. The dump valve arrangement 32 is used to purge the discharge riser 20 in the event of a failure or malfunction (trip event) of the HOHS10 that results in the medium in the discharge riser 20 not being delivered to the surface level. If not purged, solid particles (clumps) in the medium will settle at the bottom of the discharge riser 20, clogging it. The purged (or emptied) medium is deposited in the dump area indicated by the dashed ellipse 34.

[0059] A dump control circuit 36 ​​is provided that monitors the operation of the PEC 12 to ensure that the dump valve arrangement 32 is properly pressurized during normal operation and to detect when a trip event occurs and send a trip signal to the dump valve arrangement 32. In some embodiments, the trip detection circuit 36 ​​may be incorporated into a PEC controller (not shown).

[0060] The pressurized bypass line 38 connects the dump valve arrangement 32 to the lower (or bottom) of the discharge riser 20 (which is coupled to the high-pressure PEC output line 30). The pressurized bypass line 38 includes a compression valve 40 that opens when a portion of the dump arrangement 32 is pressurized, as will be described in more detail below. The pressurized bypass line 38 operates as a compression input.

[0061] The outlet 42 is provided at the bottom of the dump valve arrangement 32 through which the purged (or emptied) medium is deposited into the dump area 34.

[0062] The characteristics of the dump valve arrangement 32 are shown in detail in Figure 2, and the operation of this dump valve arrangement 32 will be explained with reference to it.

[0063] The discharge riser 20 has a lower end 60 and an upper end 61. The splitter inlet 62 is provided at the lower end 60, which is in flow communication with the PEC medium output line 30, and receives medium from there via the medium inlet pipe section 62a. The splitter inlet 62 redirects the received medium through the upper (medium hoist) pipe section 62b and leads it to the discharge riser 20.

[0064] The dump valve arrangement 32 is coaxial with the discharge riser 20 and includes an elongated housing 64 that defines an elongated settling chamber 66 therein. The settling chamber 66 has an upper end 68 and a lower end 70. The upper end 68 is connected to the lower end 60 of the hydraulic riser, and a dump valve 72 is provided between them. In this embodiment, the dump valve 72 is a ball valve, but in other embodiments, different types of valves may be used.

[0065] The sedimentation chamber 66 is positioned directly below the discharge riser 20 and extends vertically downward, thereby effectively forming a downward extension of the discharge riser 20.

[0066] The dump valve 72 may be located at the upper end 68 of the settling chamber 66, in the lower part of the discharge riser 20, or in the pipe between them.

[0067] The splitter inlet 62 also has a lower (media dump) pipe portion 62c connected to the dump valve 72.

[0068] The dump valve 72 is closed during normal operation of the HOHS 10 to prevent the medium from passing through it. However, during a trip event (described below), the dump valve 72 is opened to allow the medium to flow freely from the discharge riser 20, through the splitter inlet pipe sections 62b and 62c, and then through the dump valve 72. The dump valve 72 is positioned as close as possible to the splitter inlet 62 to minimize deposits on the top of the valve 72.

[0069] The lower end or outlet 70 of the settling chamber 66 is open downward and connects to a pressure reducing splitter 74. The pressure reducing splitter 74 defines a lateral pressure reducing path 76 to a pressure reducing valve 78, which is normally closed during normal operation of the HOHS (i.e., when there are no trip events). The pressure reducing valve 78 is an actuated cone valve, which has a cone valve whose cross-sectional flow area increases when the valve is open, thereby allowing an increase in the flow rate of fluid through the pressure reducing valve 78 when the valve is open.

[0070] The pressure reduction path 76, either alone or in combination with the pressure reducing valve 78, forms a pressure reduction output.

[0071] The pressure reducing valve 78 regulates the flow of the medium through the sedimentation chamber outlet 70 during the depressurization, but is typically closed, and as a result, the sedimentation chamber 66 remains pressurized until a trip event occurs.

[0072] The depressurizing splitter 74 defines a downward-opening discharge path 79 to the outlet 42, which includes a discharge valve 80, a discharge joint 82, and a flared outlet 84. In this embodiment, the discharge valve 80 is a ball valve, but another type of valve can be used instead. The discharge valve 80 is typically kept closed so that the settling chamber 66 remains pressurized until a trip event occurs. When opened, any medium passing through the discharge valve 80 is emptied in the dump area 34.

[0073] The discharge joint 82 connects the output line (or pipe) 86 of the pressure reducing valve 78, the output of the discharge valve 80, and the surrounding environment (in this embodiment, seawater on or near the seabed) at the flared outlet 84.

[0074] The pressure reducing valve 78 is positioned as a bypass around the discharge valve 80 so that when the pressure reducing valve 78 is open, the pressure in the sedimentation chamber 66 decreases before the discharge valve 80 is opened. The pressure reducing valve 78 is in flow communication with the discharge joint 82 when the pressure reducing valve 78 is open.

[0075] At the start of operation of HOHS10, the dump valve 72, pressure reducing valve 78, and discharge valve 80 are each closed to prevent fluid flow through them and to allow the settling chamber 66 to be sufficiently pressurized and ready for use in the event of a trip event.

[0076] When the PEC 12 is driving the medium by raising the discharge riser 20, the dump control circuit 36 ​​opens the compression valve 40 for a length of time sufficient to pressurize the settling chamber 66 to approximately the same pressure as the upper (medium hoist) pipe section 62b. This may be determined based on the timing (of the compression valve 40 being open for a defined period of time) or on feedback from a pressure sensor that senses the pressure in the settling chamber 66.

[0077] When the sedimentation chamber 66 is sufficiently pressurized, the compression valve 40 may be closed.

[0078] Next, HOHS10 operates normally, and the medium pumped from PEC12 passes through the PEC medium output line 30 and enters the discharge riser 20. The velocity of the medium is such that the medium and the solids (clumps) that form part of it are transported upwards in the discharge riser 20.

[0079] However, if the velocity of the medium in the discharge riser 20 decreases to the rate or flow rate at which the solids contained in the medium settle under gravity, the dump control circuit 36 ​​detects this as a trip event. The dump control circuit 36 ​​may also detect a trip event if there is a problem with the PEC 12 at some point during the operation of the HOHS 10. Loss of power is also detected as a trip event by the dump control circuit 36, which may then passively initiate a dump sequence.

[0080] In response to this detected trip event, the dump control circuit 36 ​​opens the dump valve 72, which connects the discharge riser 20 and the sedimentation chamber 66 in a flow communication, thereby causing the contents of the discharge riser 20 to fall into the sedimentation chamber 66 as a result of gravity acting on the medium in the discharge riser 20.

[0081] Because the pressure inside the sedimentation chamber 66 is approximately the same as the pressure inside the discharge riser 20, when the dump valve 72 is opened, only a relatively small shock wave is generated (or sometimes no shock wave is generated at all).

[0082] The pressure reducing valve 78 is opened simultaneously with, or immediately after, the opening of the dump valve 72. This reduces the pressure in the sedimentation chamber 66 and the discharge riser 20 in a controlled manner, particularly due to the use of a cone valve as the pressure reducing valve 78.

[0083] The pressure in the settling chamber 66 decreases to, for example, the pressure of the dump area 34 (the ambient pressure below the dump valve arrangement 32), or close to that pressure, at which point the discharge valve 80 is opened and the pressure reducing valve 78 is closed. This ensures that the medium in the settling chamber 66 exits from the dump valve arrangement 32 to the dump area 34 via the discharge valve 80, rather than via the pressure reducing valve 78.

[0084] In this embodiment, the elongated housing 64 has a substantially spherical or laterally expanded appearance, but the lower end 70 narrows to define a cross-sectional area similar to that of the discharge riser 20.

[0085] The settling chamber 66 has a length L and a width (or diameter) D, and their combination is selected such that the above operating sequence, namely the time it takes for the dump valve 72 to open, the time it takes for the pressure reducing valve 78 to open, the time it takes to reduce the pressure in the settling chamber 66, and the time it takes for the discharge valve 80 to open, is shorter than the time it takes for the solid to settle or flow through the settling chamber 66 and reach the bottom of the settling chamber 66. If a diameter D is selected that is at least three times the diameter of the discharge riser 20, the following calculation of the length L may be useful.

[0086] L≧(t1+t2+t3).vs During the ceremony, t1 is the time it takes for the dump valve 72 to open. t2 is the time it takes to reduce the pressure in the sedimentation chamber 66 to a pressure that allows the discharge valve 80 to open. t3 is the time it takes for the discharge valve 80 to open. vs represents the solid velocity, that is, the speed at which a solid moves downward.

[0087] The solid velocity (vs) is the combination of the mixture velocity (vm) and the settling velocity of the solid in the carrier fluid.

[0088] The mixture velocity (vm) is also affected by the diameter D of the sedimentation chamber 66. Therefore, both the length L and diameter D of the sedimentation chamber 66 are important considerations in sizing the sedimentation chamber 66.

[0089] In this embodiment, the length L is at least 15 meters, but can be optionally selected as at least 20 meters or at least 25 meters.

[0090] In this embodiment, the sedimentation chamber 66 has a diameter D that is at least twice, and in some embodiments at least three times, the diameter of the discharge riser 20.

[0091] In other embodiments, the pressurizing bypass line 38 may be connected to the bottom of the drive fluid riser 16 so that a relatively clean fluid is used to pressurize the sedimentation chamber 66.

[0092] In this embodiment, the HOHS10 allows for controlled depressurization of the pressurizing riser during trip or dump events, minimizing the dynamic effects of water hammer and erosive wear on the valve by released solids. This allows for repeated dump events without compromising the integrity of the HOHS10, while reducing the risk of plug formation in the discharge riser 20.

[0093] HOHS10 may be transported in kit form and then assembled at the location where it will be installed.

[0094] When the HOHS is installed and used on land, the ambient pressure around the bottom of the dump valve arrangement 32 is low (atmospheric pressure), and the discharge riser 20 discharges the medium against low pressure. This can result in a very high flow velocity of the medium as it is discharged. To mitigate this effect, an additional flow limiter 88 is provided for land-based HOHS. This is shown in the enlarged area 90 of Figure 2, and while not required for deep-sea embodiments, if used, it provides an alternative embodiment of the dump valve arrangement 32 for land-based systems. The flow limiter 88 is effectively a reduced-diameter orifice located at the lower end 70 of the sinking chamber 66. This limits the downward velocity of the medium in the discharge riser 20 to an acceptable level. The flow limiter 88 may comprise a localized short limit (such as an orifice) or a longer, smaller-diameter pipe (i.e., an extension pipe with a reduced diameter). Both of these can create sufficient flow resistance to limit the downward flow velocity of the discharge riser 20. The flow limiter 88 may be located in one (or more) of several positions in the dump valve arrangement. For example, the flow limiter 88 may be located (i) downstream of the sedimentation chamber 66 and upstream of the pressure reducing splitter 74, as shown in Figure 2, (ii) downstream of the pressure reducing splitter 74 and upstream of the discharge valve 80, (iii) downstream of the discharge valve 80 and upstream of the discharge joint 82, or (iv) downstream of the discharge joint 82. The flow limiter 88 may be located at any position in the flow path from the sedimentation chamber 66 through the discharge valve 80 to the flared outlet 84.

[0095] In other embodiments, the dump valve arrangement 32 may be used in conjunction with a discharge riser 20 supplied by a pump arrangement different from the pump arrangement in Figure 1. [Explanation of symbols]

[0096] Hydraulic Ore Hoist System (HOHS) 10 Pressure exchange chamber (PEC) 12 Drive fluid pump 14 Driving fluid riser 16 Surface 18 (of the rising level) Discharge Riser 20 Ore Removal Station 22 Drive fluid valve arrangement 24 Pump pressure-delivered medium valve arrangement 26 Filling mechanism 28 PEC medium output line 30 Dump valve arrangement 32 Dump area 34 Dump control circuit 36 Pressurized bypass line 38 Pressure reducing valve 40 Outlet 42 (of the dump valve configuration) (The lower end of the ejection riser) 60 (The upper end 61 of the ejection riser) Splitter inlet 62 (of the discharge riser) Media inlet pipe section 62a Upper (media hoist) pipe section 62b Lower (media release damping) pipe section 62c Housing 64 Sedimentation chamber 66 Upper end 68 (of the sedimentation chamber) Lower end 70 (of the sedimentation chamber) Dump valve 72 Pressure reducing splitter 74 Decompression path 76 Pressure reducing valve 78 Discharge route 79 Discharge valve 80 Discharge joint 82 Flared outlet 84 (The output line or pipe of the pressure reducing valve) 86 Flow limiter 88 Alternative embodiment extension portion 90

Claims

1. A dump valve configuration for use in a discharge riser, (i) A sedimentation chamber configured to be coupled to the lower part of the discharge riser, (ii) A dump valve that can be operated to allow or prevent the flow of a medium from the discharge riser to the sedimentation chamber, (iii) Before opening the dump valve, compressive input to the sedimentation chamber to pressurize the sedimentation chamber and reduce the pressure difference between the sedimentation chamber and the lower part of the discharge riser, (iv) After the dump valve is opened, a depressurization output for reducing the pressure in the sedimentation chamber, (v) A dump valve arrangement comprising an outlet for emptying the contents of the sedimentation chamber after the pressure in the sedimentation chamber has been sufficiently reduced.

2. The dump valve arrangement according to claim 1, wherein the compression input pressurizes the sedimentation chamber to substantially the same pressure as the pressure at the lower part of the discharge riser.

3. The dump valve arrangement according to claim 1 or 2, wherein the outlet is a discharge valve that is displaceable between a closed position that obstructs the flow of the medium from the sedimentation chamber through the outlet and an open position that allows the flow of the medium from the sedimentation chamber through the outlet.

4. The dump valve arrangement according to any one of claims 1 to 3, wherein the compression input is in fluid communication with the high-pressure output from the drive fluid riser.

5. The dump valve arrangement according to any one of claims 1 to 3, wherein the compression input is in fluid communication with the high-pressure output from the pressure exchange chamber supplied to the discharge riser.

6. The dump valve arrangement according to any one of claims 1 to 5, wherein the depressurization output includes a depressurization valve flow-communicated with the sedimentation chamber, thereby enabling controlled depressurization of both the sedimentation chamber and the connected discharge riser when the dump valve is opened before the discharge valve is opened.

7. The dump valve arrangement according to claim 6, wherein the pressure reducing valve comprises a cone valve that provides a desired gradual increase in flow to enable controlled pressure reduction.

8. The dump valve arrangement according to claim 6, wherein the pressure reducing output further comprises a bypass arrangement around the discharge valve such that the pressure in the sedimentation chamber decreases before the discharge valve is opened when the pressure reducing valve is open.

9. The dump valve arrangement according to any one of claims 1 to 8, further comprising a flow resistance downstream of the upper end of the sedimentation chamber.

10. The dump valve arrangement according to any one of claims 1 to 9, wherein the settling chamber is elongated, located below the discharge riser, and coaxially aligned with the discharge riser, such that when the dump valve is opened, the settling chamber effectively forms a downward extension of the discharge riser.

11. A hydraulic ore hoist system comprising: (i) a hydraulic discharge riser having a lower end and an upper end; (ii) an inlet connected to the discharge riser and in flow communication with a pressurized supply of the medium to be hoisted; and (iii) A hydraulic ore hoist system comprising: a dump valve arrangement according to any one of claims 1 to 10, configured to allow controlled depressurization of the discharge riser during a dump event before the solid is discharged from the system.

12. A method for discharging a medium from a discharge riser during a trip event, (i) Pressurizing the sedimentation chamber connected to the lower part of the discharge riser, (ii) Detecting a trip event that leads to the sedimentation of solids in the discharge riser, (iii) Discharging the medium from the discharge riser into the sedimentation chamber, (iv) To reduce the pressure difference between the sedimentation chamber and the dump area outside the sedimentation chamber, (v) A method comprising discharging the medium from the sedimentation chamber into the dump area until the majority of the solid or all of the medium has been removed from the discharge riser.

13. The method according to claim 12, wherein the step of pressurizing the sedimentation chamber includes pressurizing the sedimentation chamber to a pressure equal to or close to the pressure in the lower part of the discharge riser.

14. The method according to claim 12 or 13, wherein the step of detecting a trip event is performed by a controller coupled to a pressure exchange chamber that supplies a medium to the discharge riser.

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