Patent Description:
One arrangement for pumping medium, particularly a medium which contains a mixture of liquid and solid particles, includes making use of one or more PECs.

A PEC pumping system typically includes an elongate pipe having a medium or pumped fluid valve arrangement at one end and a driving fluid valve arrangement at the other end. The medium valve arrangement includes a medium inlet valve whereby medium to be pumped can be admitted into the PEC and a medium outlet valve whereby pumped medium can be discharged from the PEC along a discharge pipe, riser, or the like. Similarly, the driving fluid valve arrangement includes a driving fluid inlet valve through which a high-pressure driving fluid can be admitted into the PEC and a driving fluid outlet valve whereby driving fluid can be discharged from the PEC. Different configurations and layouts of elongate pipes are possible.

In use, medium to be pumped is typically fed to the medium inlet valve at a relatively low pressure by means of a medium delivery pump, usually a centrifugal pump. With the medium inlet valve open and the driving fluid outlet valve open medium enters the PEC and displaces driving fluid out of the PEC through the driving fluid outlet valve.

When the PEC has been charged with medium, i.e., a desired quantity of medium has entered the PEC, the medium inlet valve and driving fluid outlet valve are closed. The medium outlet valve and the driving fluid inlet valve are opened such that high pressure driving fluid enters the PEC and displaces the medium out of the chamber through the medium outlet valve. Naturally, the exact sequence and timing associated with the opening and closing of the valves may vary to optimise operation of the PEC pumping system.

Once the medium has been discharged from the PEC the medium outlet valve and driving fluid inlet valve close and the medium inlet valve and the driving fluid outlet valve open to charge the PEC with medium in the manner described above.

As mentioned above, the medium to be pumped is typically fed to the PEC by means of a centrifugal pump since this type of pump is able to handle a medium containing relatively large particles at a flowrate suitable for filling the PEC within a typical cycle time used by the PEC system.

To permit continuous pumping, use is made of a plurality of PECs (typically three or more) arranged in parallel. By controlling the operation of the valves, the timing of the filling or charging of the PECs with medium and the discharge of the medium therefrom can be staggered to provide a substantially continuous flow of pumped medium. To avoid clogging in the PEC, the flow velocity should be maintained, i.e., by ensuring that the switch-over time from one PEC to the next is as short as possible.

To be able to operate with a medium containing solid particles, the medium inlet valves are typically cone valves which have a downwardly open inlet. The medium inlet valves are connected in flow communication with the centrifugal pump by means of feed lines. More particularly, each feed line has a downstream end which is connected to the inlet of the associated medium inlet valve and an upstream end which is connected in flow communication with the centrifugal pump.

One problem is that when pumping medium including coarse solid particles, these coarse solid particles settle when the flow is stopped causing clogging or a blockage in the feed line, which can potentially prevent proper operation of the medium inlet valve (since the valve cannot close fully when coarse solid particles are on the valve seat) necessitating a shutdown of the pumping system. A manifold is known from <CIT>. However this manifold is not provided with angular pipes around a central axis, but intended to be arranged in a horizontal direction.

It is an object of this invention to provide means to at least ameliorate this problem or provide a useful alternative.

This summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify indispensable features of the claimed subject matter, nor is it intended for use as an aid in limiting the scope of the claimed subject matter. Features of one aspect described below may be combined with features of another aspect.

In this application ordinal numbers (first, second, third, etc.) are assigned arbitrarily herein, and are used to differentiate between parts, and do not indicate a particular order, sequence, or importance.

According to a first aspect of the invention there is provided a distribution manifold for a pressure exchange chamber (PEC) pumping system having a plurality of PEGs arranged in parallel, which includes: a hollow manifold body defining a distribution chamber and positioned in an upright orientation; an inlet leading into the body for receiving medium to be pumped, comprising solid particles transported in a liquid; a plurality of spaced apart outlets opening operatively upwardly out of the manifold body; and a plurality of pipes, each pipe extending upwards from a respective outlet to an associated medium inlet valve of one of the pressure exchange chambers, the medium inlet valves being in an upright orientation, whereby on closure of a medium inlet valve, solid particles settle down the associated pipe under gravity and away from the medium inlet valve to prevent blockage thereof.

The pipes may have any cross-sectional shape.

The medium inlet valves may be substantially vertical.

The outlets may be vertically offset (spaced apart vertically) from each other; alternatively, the hollow manifold body may comprise a plurality of outlets circumferentially spaced at approximately the same altitude (for example, in the same generally horizonal plane).

The body optionally includes a base and a top which is secured to the base to define the distribution chamber, the inlet extending through the base and the outlets extending through the top.

Each of the pipes may comprise an upstream end which is connected to one of the outlets and a downstream end which is connected to an associated medium inlet valve, each pipe being inclined operatively upwardly away from the body such that, in use, the upstream end is positioned at a level which is lower than the downstream end.

Each pipe may have a coupling formation at its downstream end whereby it is connectable to an associated medium inlet valve.

The pipes preferably are equiangularly spaced around a central axis of the manifold and each pipe is preferably inclined at an angle of inclination of approximately <NUM> degrees or less relative to the central axis of the manifold.

In a preferred embodiment of the invention the angle of inclination is between <NUM> degrees and <NUM> degrees, advantageously between <NUM> degrees and <NUM> degrees, such as approximately <NUM> degrees.

The distribution manifold may include an inlet pipe having a downstream end which is connected to the base and an upstream end which is connectable to the medium supply to connect the inlet of the distribution manifold in flow communication with the medium supply. A connecting formation may be provided at the upstream end of the inlet pipe for connection with a feed line in flow communication with a discharge side of a feeder or delivery pump.

The medium may comprise a slurry. Slurries typically have a solids concentration of at least <NUM>% by weight, but sometimes significantly more (typically at least <NUM>% by weight) because pumping efficiency increases with increasing solids concentration, provided there is no clogging of the pipes due to the solids content, because the aim is to transfer as much solids as possible.

The hollow manifold body may further define a sump into which solid particles from each pipe may flow under gravity, whereby these solid particles may be entrained with new medium being pumped through the hollow manifold body and through another pipe connected to an open medium inlet valve. The sump may comprise one or more sloping sides.

The distribution manifold may form part of a common slurry input device. The common slurry input device may further comprise a plurality of medium inlet valves, each medium inlet valve being associated with a respective pressure exchange chamber.

According to a second aspect of the invention there is provided a common medium input device comprising a distribution manifold according to the first aspect, and a plurality of medium input valves; wherein each of the pipes has an upstream end which is connected to one of the outlets and a downstream end which is connectable to an associated medium inlet valve, each pipe being inclined operatively upwardly away from the body such that, in use, the upstream end is positioned at a level which is lower than the downstream end.

According to a third aspect of the invention there is provided a method of operating a PEC pumping system having at least one PEC which method includes feeding medium comprising solid particles transported in a liquid to an upright medium inlet valve of the PEC along a flow path through a manifold body and a pipe having an upstream end connected to the manifold body and a downstream end which is connected to the medium inlet valve and positioned higher than the upstream end, such that on closure of a medium inlet valve, solid particles settle down the associated pipe under gravity and away from the medium inlet valve to prevent blockage thereof.

When the PEC pumping system has a plurality of PECs, the method may include feeding medium to be pumped from a distribution chamber to a medium inlet valve of the or each PEC along an inclined flow path such that solids settling in a flow path are fed under gravity towards the distribution chamber.

The method may include using a delivery pump to feed medium to be pumped into the distribution chamber and from the distribution chamber along the associated flow path to the or each medium inlet valve which is open. The method may also include feeding back into the distribution chamber at least some of the solids which settle in a flow path connected to a medium inlet valve which is closed, thereby ensuring that the settled solids are entrained in medium flowing through the distribution chamber and along a flow path to an open medium inlet valve.

It will be appreciated that medium will be pumped to the distribution chamber from a medium delivery pump on a continuous basis. Further, by virtue of the staggered operation of a plurality of PECs, at any given time at least one medium inlet valve will be open to permit charging of the associated PEC with medium to be pumped. This arrangement permits continuous flow of medium through the distribution chamber. Solids which settle in a feed line for a PEC that has been filled flow downwardly along the feed line from the associated medium inlet valve that is, or will be, closed, and at least some of the solids (typically the heavier or larger solids) flow back into the distribution chamber where they are entrained in the medium flowing through the distribution chamber and are fed along the feed line connected to the open medium inlet valve.

According to a fourth aspect of the invention, there is provided a PEC pumping system which comprises: (i) at least one PEC comprising a pipe and a medium valve arrangement in flow communication with the pipe; (ii) a feed arrangement for feeding medium comprising solid particles transported in a liquid to the PEC; and (iii) a common medium input device according to the second aspect coupled to both the at least one PEC and the feed arrangement.

In a preferred embodiment of the invention, the PEC pumping system includes a plurality of PECs arranged in parallel, a distribution manifold defining a distribution chamber which has an inlet connected in flow communication with a source of medium to be pumped, and a plurality of spaced apart outlets, each connected by a feed line to a respective medium inlet valve, each of the feed lines being inclined such that solids settling in a feed line are fed under gravity towards the distribution chamber. In other words, solids which settle in a feed line will not be deposited in the feed line but will move downwardly away from the medium inlet valve to which the feed line is connected and into the distribution chamber, thereby reducing the risk of a blockage in the feed line or that the solids may interfere with the operation of the valve.

To ensure that any solids which settle in a feed line do not clog the feed line, each feed line may have an angle of inclination relative to the vertical of approximately <NUM> degrees or less, or approximately <NUM> degrees or less. In a preferred embodiment of the invention, the angle of inclination is between <NUM> and <NUM> degrees.

The distribution manifold may be a distribution manifold of the type described above.

The PEC pumping system may further comprise a driving fluid valve arrangement in flow communication with the pipe at a position longitudinally spaced from the medium valve arrangement.

The components of the PEC pumping system may be transported in a disassembled or knocked-down kit form for assembly at site.

Hence, according to a fifth aspect of the invention, there is provided a PEC pumping system kit which includes: a plurality of PECs, each comprising a pipe and an associated medium valve arrangement, each medium valve arrangement including a medium inlet valve whereby medium to be pumped can be admitted into the pipe and a medium outlet valve whereby pumped medium can be discharged from the pipe; and a distribution manifold as described above whereby the medium inlet valves are connectable in flow communication with a medium supply.

The PEC pumping system kit may further comprise a plurality of driving fluid valve arrangements which are connected or connectable to the pipes at a position longitudinally spaced from the medium valve arrangements, each driving fluid valve arrangement including a driving fluid inlet valve through which a high-pressure driving fluid can be admitted into the pipe and a driving fluid outlet valve whereby driving fluid can be discharged from the pipe.

According to a sixth aspect of the invention, there is provided a method of modifying a PEC pumping system which includes a plurality of PECs arranged in parallel, each PEC including a medium inlet valve, and a feed arrangement for feeding medium to be pumped to the medium inlet valves, the feed arrangement including a feeder pump having a suction side and a discharge side, which method includes providing a distribution manifold of the type described above and connecting the manifold in-line between the feeder pump and the medium inlet valves.

According to a seventhth aspect of the invention there is provided a method of reducing clogging in a PEC pumping system, the method comprising: receiving pumped medium through a common medium entry inlet; upwardly directing pumped medium from the common medium entry inlet to an open medium inlet valve; downwardly directing stationary medium from beneath a closed medium inlet valve; and mixing the downwardly directed medium with the upwardly directed medium in a distribution chamber to reduce clogging caused by the stationary medium.

The method may comprise the further step of upwardly directing mixed downwardly and upwardly directed medium to the open medium inlet valve.

According to an eighth aspect of the invention there is provided a distribution manifold for a pressure exchange chamber pumping system having a plurality of pressure exchange chambers arranged in parallel, which includes: a hollow manifold body defining a distribution chamber; an inlet leading into the body and connectable in flow communication with a medium supply providing a slurry comprising solid particles transported in a liquid; a plurality of spaced apart outlets opening operatively upwardly out of the manifold body, each outlet being connectable in flow communication with a medium inlet valve of one of the pressure exchange chambers; and a plurality of lengths of pipe, each of which has an upstream end which is connected to the manifold body in flow communication with one of the outlets and a downstream end which is connectable to an associated medium inlet valve of one of the pressure exchange chambers, the medium inlet valve being in an upright orientation, and each length of pipe being inclined operatively upwardly away from the manifold body such that, in use, the upstream end is positioned at a level which is lower than the downstream end, whereby solid particles that settle are fed under gravity away from the medium inlet valve to prevent blockage thereof.

These and other aspects of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which:.

In <FIG> of the drawings, reference numeral <NUM> refers generally to part of a pressure exchange chamber (PEC) pumping system in accordance with the prior art.

The PEC pumping system <NUM> includes three PEGs <NUM>, <NUM>, and <NUM> defined by lengths of pipe <NUM>, <NUM>, <NUM> (which act as pump chambers) and associated valves. The associated valves include three medium or pumped fluid valve arrangements <NUM>, <NUM>, <NUM>, which are connected respectively to the pipes <NUM>, <NUM>, <NUM> at a medium entry ends thereof. The associated valves also include three driving fluid valve arrangements <NUM>, <NUM>, <NUM>, which are connected, respectively, to the lengths of pipe <NUM>, <NUM>, <NUM> at the driving fluid entry ends thereof, i.e., longitudinally spaced from the medium valve arrangements <NUM>, <NUM>, <NUM>.

Each medium valve arrangement <NUM>, <NUM>, <NUM> includes a medium inlet valve <NUM>, <NUM>, <NUM> whereby medium to be pumped can be admitted into the associated PEC <NUM>, <NUM>, <NUM> and a medium outlet valve <NUM>, <NUM>, <NUM> whereby pumped medium can be discharged from the PEC <NUM>, <NUM>, <NUM> along a discharge pipe <NUM> (which may be a riser). Similarly, each driving fluid valve arrangement <NUM>, <NUM>, <NUM> includes an inlet valve <NUM>, <NUM>, <NUM> through which a high-pressure driving fluid can be admitted into the associated PEC <NUM>, <NUM>, <NUM> and an outlet valve <NUM>, <NUM>, <NUM> whereby driving fluid can be discharged from the associated PEC <NUM>, <NUM>, <NUM>.

The PEC pumping system <NUM> further includes a feed arrangement, part of which is generally indicated by reference numeral <NUM>, configured to feed medium to be pumped to the medium inlet valves <NUM>, <NUM>, <NUM> as described in more detail herebelow. The feed arrangement <NUM> includes a feeder or delivery pump (not shown) having a suction side and a discharge side, although other pump arrangements are possible. The feeder pump is typically a centrifugal pump which can pump a medium which includes fairly large solid particles, e.g., particle sizes between <NUM> and <NUM>. with some particles up to approximately <NUM>. The feed arrangement <NUM> further includes a common feed pipe <NUM> which is connected to a discharge side of the feeder pump and three feed lines <NUM>, <NUM>, <NUM> each of which has an upstream end connected to the common feed pipe <NUM> and a downstream end. The downstream ends of the feed lines <NUM>, <NUM>, <NUM> are connected , respectively, to the medium inlet valves <NUM>, <NUM>, <NUM>. Hence, in use medium to be pumped is pumped from the centrifugal pump through the pipe <NUM> and the feed lines <NUM>, <NUM>, <NUM> to the medium inlet valves <NUM>, <NUM>, <NUM>.

In use, once the volume in the relevant pipe <NUM>, <NUM>, <NUM> is decompressed, the medium inlet valve <NUM>, <NUM>, <NUM>,<NUM> is opened and the corresponding driving fluid outlet valve <NUM>, <NUM>, <NUM> is opened, so that medium enters the associated pipe <NUM>, <NUM>, <NUM> and displaces the driving fluid out of that pipe <NUM>, <NUM>, <NUM> through the associated driving fluid outlet valve <NUM>, <NUM>, <NUM>. When a desired quantity of medium has entered a particular PEC pipe <NUM>, <NUM>, or <NUM>, the associated medium inlet valve <NUM>, <NUM>, or <NUM>,<NUM> and the associated driving fluid outlet valve <NUM>, <NUM>, or <NUM> are closed. The volume in the relevant pipe <NUM>, <NUM>, <NUM> is pressurised (by a compression step) and then the medium outlet valve <NUM>, <NUM>, or <NUM> and the associated driving fluid inlet valve <NUM>, <NUM>, or <NUM> are opened such that high-pressure driving fluid enters that PEC pipe <NUM>, <NUM>, or <NUM> and displaces the medium out of the pipe <NUM>, <NUM>, or <NUM> through the medium outlet valve <NUM>, <NUM>, or <NUM> and into the discharge pipe <NUM>.

Once the medium has been discharged from the pipe <NUM>, <NUM>, or <NUM>, the associated medium outlet valve and driving fluid inlet valve close, the pipe <NUM>, <NUM>, or <NUM> is decompressed, and the medium inlet valve and driving fluid outlet valve open, once again, to charge the pipe <NUM>, <NUM>, or <NUM> with medium in the manner described above.

To permit more or less continuous pumping, the operation of the valves of the different PEGs <NUM>, <NUM>, <NUM> is staggered such that the filling of the PECs <NUM>, <NUM>, <NUM> with medium and the discharge of medium occurs in a more or less continuous basis.

It will be appreciated that when the medium inlet valve <NUM>, <NUM>, <NUM> of a particular PEC <NUM>, <NUM>, <NUM> is opened, medium will be flowing through the associated feed line <NUM>, <NUM>, <NUM> and solid particles in the medium will be entrained or suspended in the liquid (which is typically water). However, when one of the medium inlet valve closes, the medium in the associated feed line <NUM>, <NUM>, <NUM> will be stationary until the medium inlet valve once again opens. Whilst the medium is stationary, the solids in the medium settle in the feed line. This can lead to a blockage in (clogging of) the feed line <NUM>, <NUM>, <NUM>. In addition, with the accumulation of sufficient solids in the feed line, the proper operation of the medium inlet valve is not possible, necessitating a shutdown of the PEC pumping system <NUM> to effect suitable repairs (e.g., unclogging) to restore the medium inlet valve to full operation.

Reference is now made to <FIG> of the drawings, in which reference numeral <NUM> refers generally to an embodiment of a PEC pumping system in accordance with the invention. Unless otherwise indicated, like reference numerals used above are used to designate similar parts.

The PEC pumping system <NUM> of the present invention makes use of a distribution manifold generally indicated by reference numeral <NUM>. The distribution manifold <NUM> replaces the feed lines <NUM>, <NUM>, <NUM> in the prior art PEC system <NUM> and provides an interface between the common feed pipe <NUM> and the medium inlet valves <NUM>, <NUM>, <NUM>.

As can best be seen in <FIG> of the drawings, the distribution manifold <NUM> includes a hollow body <NUM> defining a distribution chamber <NUM>.

The body <NUM> includes a domed or frusto-conical base <NUM> and a domed or frusto-conical top <NUM> which is secured to the base by circumferentially spaced bolts <NUM> extending through complementary annular flanges.

The distribution manifold <NUM> includes an inlet <NUM> which extends through the base <NUM> and an inlet pipe <NUM> having a downstream end which is connected, e.g., by welding, to the base <NUM> and an upstream end which is connected to the pipe <NUM> by means of a coupling <NUM> thereby connecting the inlet <NUM> in flow communication with the discharge side of the feeder pump.

The medium inlet valves <NUM>, <NUM>, <NUM> are in the form of cone valves which have a downwardly facing inlet and are positioned in a spaced apart configuration above the distribution manifold <NUM>. Three equiangularly spaced apart upwardly open outlets 57a, 57b, 57c extend through the top <NUM> and are connected to the inlets of the medium inlet valves <NUM>, <NUM>, <NUM> by feed lines <NUM>, <NUM>, <NUM>, respectively. Each feed line <NUM>, <NUM>, <NUM> comprises a length of pipe having a straight lower section <NUM> and a curved upper section <NUM>. The lower ends of the lower sections <NUM> are secured to the top <NUM>, e.g., by welding, such that they extend upwardly outwardly away from the top <NUM> at an angle of inclination A relative to a vertical center line <NUM> through a centre of the distribution manifold <NUM>. The upper sections <NUM> curve upwardly and a flange <NUM> is connected to the upper end of the upper section whereby the feed line <NUM>, <NUM>, <NUM> is connected to the associated medium inlet valve <NUM>, <NUM>, <NUM>.

Important to note is that each of the feed lines <NUM>, <NUM>, <NUM> is inclined downwardly for its entire length from its downstream end which is in flow communication with the inlet of the associated medium inlet valve <NUM>, <NUM>, <NUM> to its upstream end connected in flow communication with the distribution chamber <NUM> defined in the body <NUM> of the distribution manifold <NUM>.

In use, the PEC pumping system <NUM> functions in substantially the identical manner to the PEC pumping system <NUM> described above. However, as explained in more detail below, when a medium inlet valve is closed and the medium contained in the associated feed line <NUM>, <NUM>, <NUM> is stationary, solids contained in the feed line will settle and flow downwardly, under the influence of gravity, along the feed line towards the distribution chamber <NUM> of the distribution manifold <NUM>. The lower part of the distribution chamber <NUM> defines a sump <NUM> (best seen in <FIG>) having sloping sides and into which the solids settle from each of the feed lines <NUM>, <NUM>, <NUM> when their respective medium inlet valves are closed. Solids which flow back into the distribution chamber <NUM>, and which collect in the sump <NUM>, will be entrained in the medium passing through the distribution chamber <NUM> and be fed along the feed line connected to whichever medium inlet valve which is open.

With reference to <FIG> of the drawings, the flow of medium through the distribution manifold <NUM> is illustrated in a first operative condition of the PEC pumping system <NUM> in which the medium inlet valve <NUM> is open and the medium inlet valve <NUM> is closed. In this condition, medium is fed along the pipe <NUM> in the direction of arrow <NUM>. The medium passes through the inlet pipe <NUM> and enters the distribution chamber <NUM> through the inlet <NUM>. The medium exits the chamber <NUM> through the outlet 57c and flows along the feed line <NUM> connected to the medium inlet valve <NUM> as indicated by arrow <NUM> (which indicates the slurry feed flow direction in both <FIG> and <FIG>). Since the medium inlet valve <NUM> is closed the medium in the feed line <NUM> is stationary. Solid particles which settle in the feed line <NUM> flow downwardly under the influence of gravity, as illustrated by arrow <NUM> (which indicates the solids settling direction in both <FIG> and <FIG>), back through the outlet 57b into the distribution chamber <NUM> where they are entrained in the medium flowing through the chamber and fed to the open medium inlet valve <NUM>.

With reference to <FIG> of the drawings, the flow of medium through the distribution manifold <NUM> is illustrated in a second operative condition in which the medium inlet valve <NUM> is closed and the medium inlet valve <NUM> is open. In this condition, medium is fed along the pipe <NUM> in the direction of arrow <NUM>. The medium passes through the inlet pipe <NUM> and enters the distribution chamber <NUM> through the inlet <NUM>. The medium exits the chamber <NUM> through the outlet 57b and flows along the feed line <NUM> connected to the medium inlet valve <NUM> as indicated by arrow <NUM>. Since the medium inlet valve <NUM> is closed the medium in the feed line <NUM> is stationary. Solid particles which settle in the feed line <NUM> flow downwardly under the influence of gravity, as illustrated by arrow <NUM>, back through the outlet 57c into the distribution chamber <NUM> where they are entrained in the medium flowing through the chamber and fed to the open medium inlet valve <NUM>.

The operation of the system has been described above by way of illustration without reference to the medium inlet valve <NUM> and the associated feed line <NUM>. It will be appreciated however, that when the medium inlet valve <NUM> is open, medium will flow through the outlet 57a along the feed line <NUM> into medium inlet valve <NUM> and when the medium inlet valve <NUM> is closed solid particles settling in the feed line <NUM> will flow back through the outlet 57a into the chamber <NUM> to be entrained in the medium flowing through the chamber <NUM> in the manner described above. To ensure continuous pumping, at all times at least one of the medium inlet valves <NUM>, <NUM>, <NUM> is open. This in turn ensures that there is continuous flow of medium through the common feed pipe <NUM>, inlet pipe <NUM> and chamber <NUM>. In some systems, a fourth PEC may be included for redundancy, for example in case of failure of one of the other three PEGs <NUM>, <NUM>, <NUM>.

The angle of inclination A of the feed lines <NUM>, <NUM>, <NUM> is selected to ensure that solids settling in the feed line do in fact flow back towards the distribution chamber <NUM>. To this end, the angle of inclination A is between <NUM>°, i.e., vertical, and approximately <NUM>° for some types of slurry (e.g., where the particles are spherical and roll), although for many embodiments the angle will be between approximately <NUM>° and <NUM>°, such as approximately <NUM>° to <NUM>°.

It will be appreciated that potentially not all the solids contained in a feed line <NUM>, <NUM>, <NUM> will flow back into the chamber <NUM> before the associated medium inlet valve <NUM>, <NUM>, <NUM> opens for the following charging cycle. However, the movement of the solids in the feed lines will reduce the risk of a build-up which could cause a blockage (clogging). In addition, the settling solids will move away from the associated medium inlet valve <NUM>, <NUM>, <NUM> thereby reducing the risk that they may interfere with the proper functioning of the associated medium inlet valve <NUM>, <NUM>, <NUM>.

In this way, the risk of a medium build-up which could block the feed line or inhibit operation of the medium inlet valve is greatly reduced.

An additional advantage of the invention is that the concentration of solids in the medium can be increased substantially from the current level, for example, up to approximately <NUM>%. This in turn allows more solids to be pumped for a given power input or alternatively for a smaller system to be used to pump the same volume of solids as may be pumped with the prior art.

In other embodiments, the outlets 57a,b,c may not be equally (or equiangularly) spaced around a central axis <NUM> of the manifold <NUM>. For example, an alternative distribution manifold <NUM> is shown in <FIG>. This distribution manifold <NUM> may be used in embodiments where the PECs <NUM>, <NUM>, <NUM> are located at different heights or altitudes). The distribution manifold <NUM> comprises four outlet 157a,b,c,d each being coupled to a respective feed line <NUM>, <NUM>, <NUM> and <NUM>; and each of the outlets 157a,b,c,d being vertically spaced (or offset) from its adjacent outlet. The distribution manifold <NUM> comprises an elongate body <NUM> extending generally vertically and defining a circular or cylindrical distribution chamber <NUM> therein.

In other embodiments, as illustrated in <FIG> of the drawings, a distribution manifold <NUM> may include a vertical spacing pipe <NUM> between the upper section <NUM> and the flange <NUM> associated with each outlet 57a,b,c. The medium inlet valves <NUM>, <NUM>, <NUM> each define a chamber <NUM> in which a valve seat <NUM> is mounted. A valve body <NUM> moves within the chamber <NUM> towards and away from the valve seat <NUM> to close and open the valve, respectively. The vertical spacing pipe <NUM> is provided to assist with flow of solid particles downwardly under the influence of gravity, away from that part of the chamber <NUM> beneath the valve body <NUM> and down the vertical spacing pipe <NUM>. The volume of the upper section <NUM> and the vertical spacing pipe <NUM> combined equals or is greater than the volume of the chamber <NUM> of the medium input valve <NUM>. In other embodiments, vertical spacing pipe <NUM> may be incorporated into the upper section <NUM> to provided an upper section having an extended vertical portion immediately below the flange <NUM>.

In other embodiments an input vertical spacing pipe may be provided between the inlet pipe <NUM> and the base <NUM>.

Claim 1:
A distribution manifold (<NUM>, <NUM>, <NUM>) for a pressure exchange chamber pumping system (<NUM>, <NUM>) having a plurality of pressure exchange chambers (<NUM>, <NUM>, <NUM>) arranged in parallel, which includes:
a hollow manifold body (<NUM>, <NUM>) defining a distribution chamber (<NUM>, <NUM>) and positioned in an upright orientation and defining a central, upright axis (<NUM>);
an inlet (<NUM>) leading into the body (<NUM>, <NUM>) for receiving medium to be pumped, comprising solid particles transported in a liquid;
a plurality of spaced apart outlets (<NUM>, <NUM>) opening operatively upwardly out of the manifold body (<NUM>, <NUM>); and
a plurality of pipes (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), each pipe extending upwards from a respective outlet (<NUM>, <NUM>) to an associated medium inlet valve (<NUM>, <NUM>, <NUM>) of one of the pressure exchange chambers and the pipes (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are spaced around the central axis (<NUM>) of the manifold (<NUM>, <NUM>, <NUM>) and each pipe (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is inclined at an angle in the range of approximately <NUM> degrees to <NUM> degrees relative thereto, the medium inlet valves (<NUM>, <NUM>, <NUM>) being in an upright orientation, whereby on closure of a medium inlet valve (<NUM>, <NUM>, <NUM>), solid particles settle down the associated pipe (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) under gravity and away from the medium inlet valve (<NUM>, <NUM>, <NUM>) to prevent blockage thereof.