GB2056024A

GB2056024A - Valve Nozzle Assembly for Use in Water Treatment Systems

Info

Publication number: GB2056024A
Application number: GB7927587A
Authority: GB
Original assignee: DEGREMONT LAING Ltd
Current assignee: DEGREMONT LAING Ltd
Priority date: 1979-08-08
Filing date: 1979-08-08
Publication date: 1981-03-11

Abstract

The assembly has a hollow head portion 16 for location in a vessel, and a hollow stem 10. Internally is a valve 15 movable between the full-line open position in which it permits normal forward flow via slits 22 and passages 18, 19, and the dash-line closed position in which a regenerative reverse flow occurs via one or more restricted bypass orifices 18. The valve 15 has an S.G. below 1 and is moved forward flow but on cessation of this flow it closes ready for reverse bypass flow. The assembly may be inverted in which case a valve is provided with an S.G. greater than 1. <IMAGE>

Description

SPECIFICATION Nozzle for Use in Water Treatment System This invention relates to a nozzle for use in a water treatment system.

In many water treatment systems, particularly those involving ion exchange, the system is periodically regenerated with a flow which occurs in the opposite direction to the normal operating flow. In such systems, water flows through a vessel in contact with the ion exchange medium and is collected by one or more water collectors at the downstream end. During the regeneration stage, the water collectors must function to distribute the regenerating medium uniformly so that it flows in the opposite direction through the vessel. When the operating flow rate and the regeneration flow rate are of the same magnitude there is no problem as both good collection and even distribution during regeneration can be obtained.However, it is common for the two rates to be significantly different, the operating rate generally being higher than the regeneration flow rate with the result that the system which is designed adequately to collect during the operating phase will not provide particularly even distribution of the regenerating medium during the regeneration phase. Although provided the ratio of operating to regenerating flow is not too great, systems can be devised providing reasonably good distribution during regeneration, at higher ratios this is not at present possible without employing separate systems, one for operation and one for regeneration; this is excessively expensive.

The aim of the present invention is to provide a nozzle which provides different head losses when the flow through it is in opposite directions.

According to the present invention there is provided a nozzle for use in water treatment systems, the nozzle having a hollow head for location in a water treatment vessel and connected to a hollow stem, and providing alternative flow paths between the exterior of the head and the interior of the stem, one of said flow paths being closable by a valve arrangement including a freely movable valve member of appropriately selected specific gravity and being openable in the event of flow from the exterior of the head to the stem, and the other flow path bypassing the valve arrangement at least when there is no such flow from the exterior of the head to the stem.

As a result, the said one flow path is used during the operating mode of the water treatment system and the bypass only is employed when flow is in the reverse direction, for instance, in an ion exchange system, during regeneration. The bypass flow path offers greater resistance to flow in the one flow path.

Normally, the seat for the valve member is in the upper part of the head, remote from the stem, and the main flow path enters the head above the valve. In this case, if the nozzle is to be used with the head uppermost then the specific gravity of the valve member will be less than one so that except when it is displaced downwardly by the operating flow, the valve member will move upwardly against the valve seat to close the main flow path and allow the bypass only to operate.

With this type of arrangememt, if the nozzle is to be used the other way up, that is to say with the head at the bottom and the stem extending upwardly therefrom, then the valve member should have a specific gravity greater than one so that it closes the main flow path due to gravitational forces except when flow occurs. It is possible, of course, for the valve arrangement to have an alternative construction whereby the inlet to it from the exterior of the head is below the valve member and, in the case where the head is positioned above the stem, the valve member should have a specific gravity reater than one so as to close the first main path except in the event of operational flow. The reverse situation, with the specific gravity less than one obviously can also obtain.

The valve member can be spherical but preferably it is a part sphere attached to a stem in order to keep it correctly oriented as this requires less space.

The head of the nozzle is preferably surrounded by an outer shield with small slits which allowfor the passage of liquid but not for that of the ion exchange medium. Internally of the shield, there is preferably an annular channel with passages therefrom to the main and bypass paths through the valve arrangement in the head. In the head there is a valve seat against which the valve member locates when closing the main flow path and there are also preferably stops to limit the movement of the valve member away from the valve seat while allowing passage of fluid around the valve member.

In order that the invention may be more clearly understood the following description is given by way of example only with reference to the accompanying drawings, in which the sole Figure is a part sectional side view of one form of the nozzle according to the invention.

The illustrated nozzle consists essentially of a hollow screw threaded stem 10 with an outwardly directed flange 11 and an upstanding extension 12 to which is screw threadedly attached a cap 13 defining at its lower inner periphery a valve seat 14 against which a valve member 15 which comprises a part spherical head and a stem can seat. Screw threaded to the exterior of the cap 13 is a shield 21 which has a plurality of thin slits 22 to allow water to flow into and out of an annular chamber 16 defined between the shield and the cap 13. Four radially directed apertures 17 extend through the side wall of the cap 13, and a selected number of significantly smaller apertures 18 are provided in the upstanding part 12 of the stem 10.Shown at 19 is one of a plurality, preferably four, abutments at the end of the stem which limit the downward motion of the valve member 1 5 to the position in which it is shown in full lines.

Below the flange 1 1 on the stem 10 is a bleed hole 20 leading to the hollow interior of the stem, this is only required when the head is at the top.

If the nozzle is to be used with the head above the stem, for instance by being mounted in a plate at the bottom of a vessel to contain ion exchange medium, then the valve 15 will be selected to have a specific gravity less than one with the result that it would tend to move upwardly to the position in which it shown in dashed lines against the valve seat 14. When in this position, the passage forfluid from the exterior of the shield 21 through the annular chamber 16 and the holes 17 is blocked and liquid will not pass by this route to the interior of the stem 10.However, in the event of flow from the exterior of the head to the interior of the stem, for instance being brought about by suction applied to the stem or pressure applied to the vessel, then the valve 15 will move downwards, thus providing a flow path around it, even should it abut the abutments 19, and this is the normal operating mode for this embodiment.

During flow in the reverse direction, the valve will remain in the position it tends to adopt when there is no flow, abutting the seating 14, but flow of a more restricted nature can occur through the stem 10, through the single or more holes 18 into the annular chamber 16 and thence outwardly through the slits 22 and the shield 21. In the event of the nozzle being used the other way up, with the head below the stem, which is an alternative and common arrangement wherein the head can still be located adjacent the bottom of a vessel with the stem being connected to lateral pipes near the bottom of the vessel, then exactly the same function can be achieved if the valve member is in this case of a specific gravity greater than one so that in the event of no flow gravity causes it to seat on the valve seating 14.

As mentioned above in alternative constructions the main flow inlet to the head from the annular chamber 16 could be at a level below the valve member 15 in which case the specific gravities for the two possible orientations would be reversed, that is to say with the head above the stem of the nozzle the valve member can be lifted off its seating by flow from the exterior of the shield, through the chamber 16 and the inlets, beneath the valve member 15 into the stem.

The number and diameter of orifices 18 will be selected according to the particular application, depending for instance on the desired flow rate and the number of nozzles in relation to the volume of the liquid vessel.

The nozzle can be made entirely of plastics material, typically polypropylene although the valve member may in certain circumstances be more appropriately made of ABS plastics or polyvinylchloride. The nozzle can be connected to a header by nuts screwed on the threaded exterior of the stem 10. Instead of the various connections between the parts of the nozzle being screwed, as illustrated and above described, the parts could be connected together by welding.

Claims

1. A nozzle for use in water treatment systems, the nozzle having a hollow head for location in a water treatment vessel and connected to a hollow stem, and providing alternative flow paths between the exterior of the head and the interior of the stem one of said flow paths being closeable, except when there is flow from the exterior of the head to the stem, by a valve arrangement including a freely movable valve member of appropriately selected specific gravity, and the other path bypassing the valve arrangement at least when there is no such flow from the exterior of the head to the stem.

2. A nozzle according to claim 1, for use with the head above the stem, wherein the specific gravity of the valve member is less than one and the valve member is movable downwardly to open the first flow path.

3. A nozzle according to claim 1 for use with the stem above the head, wherein the specific gravity of the valve member is greater than one and the valve member moves to open the first path upwardly.

4. A nozzle according to claim 1 for use with the head above the stem, wherein the specific gravity of the valve member is greater than one and the valve member is moved upwardly to open the first flow path.

5. A nozzle according to claim 1 the use with the stem above the head, wherein the specific gravity of the valve member is less than one and the valve member moves downwards to open the first flow path.

6. A nozzle according to any preceding claim, wherein the valve head comprises the valve arrangement surrounded by a shield.

7. A nozzle according to claim 6, wherein the shield has a plurality of slits to admit water but not an ion exchange medium.

8. A nozzle according to any preceding claim, wherein the valve member is spherical or part spherical.

9. A nozzle according to claim 8, wherein the valve member is part spherical and attached to a stem extending within the hollow stem of a nozzle.

10. A nozzle according to any preceding claim including a lateral flange on the stem, an extension of the stem beyond the lateral flange, a valve cap attached to the extension, the valve member being movable within the extension and valve cap, main bores through the valve cap for defining the first flow path and one or more bypass bores through the extension on the stem to define the bypass flow path.

11. A nozzle for use in water treatment systems constructed and arranged substantially as hereinbefore described with reference to and as. illustrated in the accompanying drawings.

12. A water treatment system, in particular of the ion exchange type, including a vessel and a plurality of nozzles according to any preceding claim mounted in the vessel.