WO2013045868A1

WO2013045868A1 - A nozzle for a media filter system

Info

Publication number: WO2013045868A1
Application number: PCT/GB2012/000410
Authority: WO
Inventors: Stephen Cupples; Andrew Evans
Original assignee: Stephen Cupples; Andrew Evans
Priority date: 2011-09-26
Filing date: 2012-05-08
Publication date: 2013-04-04
Also published as: GB201116486D0; EP2741859A1

Abstract

A vortex stabilizer which is an outlet for a main water inlet pipe in a down flow type of media water filter system. The stabiliser comprises an upper main body (7) connected to the said inlet pipe (4) containing a plurality of radially drilled fine spray holes (9a) and a lower threaded insert (10) which engages with the main body (7) and is equipped with a plurality water outlets (9) which are cut vertically and tangentially into the threaded side wall of the said lower threaded insert (10) so as to provide a water jet which is tangential to side wall of the vortex stabiliser and which varies in size depending on the extent to which the threaded insert is screwed into the main body (7).

Description

A NOZZLE FOR A MEDIA FILTER SYSTEM

The present invention relates to a down flow type of advanced media water filter system and introduces a new and improved method of feeding the water into the filter vessel via at least two independent inlets, where at least one of the inlets is a multiple jet, variable geometry, vortex stabiliser nozzle. The system is designed to improve the efficiency of filtration systems by removing the inefficiencies which can occur due to the flow arrangements in existing filter systems.

Water or media filters as they are sometimes known, are used in many different areas but the more common are drinking and bottled water filtration, industrial process water filtration, sea, river, canal or loch water filtration, swimming pool filtration, contaminant removal for environmental uses and cooling tower, chiller or air conditioning applications.

The typical construction of a media base water filter is a down flow arrangement using a sealed cylindrical vessel with a water inlet at the top and an outlet at the bottom, though there are some cross flow systems. Contained within the vessel are various layers of filter media, which, in a typical down flow system, starts with a very fine layer at the top and finishing with a coarse layer at the bottom. At the top of the vessel above the medial layers, is a receiving area known as the upper plenum into which the inlet pipe feeds and at the bottom separated from the coarse media by a plate through which water can pass is a water collection area known as the lower plenum to which the outlet pipe is attached. Various piping arrangements are possible for reversing the water flow, a process known as backwashing which is done to clean the filter. For reverse flow, usually there would be a takeoff pipe at the top and a feed pipe at the bottom connected either independently or to one of the existing pipes via appropriate valves.

Traditional self cleaning media filters can remove solids down to 20 micron and at this level efficiencies are as high as 80% removal, but can be as low as 30%. Media filters; which employ sand and other minerals as the filter material; are also used but on filtration of less than 10 micron, however the sand soon binds and bacteria colonise the sand. The bacteria then start to grow and soon block the filter bed. Because of this media based filtration generally only offers reliable filtration down to the 20 micron level. Theoretically 10 micron filtration is possible but this can only be sustained if the feed water contains only a low level of contamination thus reducing the amount of work the filter has to perform. The design of these filters relies on a steady flux rate. The flux rate is the rate of unit flow per hour, per unit area of the filter usually expressed as m3/hr/m2 of filter. Traditionally for fine filtration to 10 micron the flux rate is reduced to flows typically 10-15 m3/hr/m2.

The problem is that by using even finer media to give high quality water filtering, the flow rate or flux rate as it is often known, needs to be slow. The traditional media is either sand or garnet or a mix. The finer the media, the finer the filtration, but also there will be a higher pressure drop and a lower flux rate. Biological contamination in this type of filter can cause rapid pressure build up which is the trigger for the system to automatically stop and backwash out the contamination. Backwashing is brought about by shutting off valves in the supply inlet or inlets and the outlet to the filter and opening valves in the backwash pipes which effectively reverses the flow of water through the filter thus driving out the contamination through a separate backwash outlet at the top or what is normally input side of the filter system.

The water borne contamination can and often does contain biological elements which combine within the bed and start to proliferate, this is helped by the near ideal conditions within the filter environment which are normally required for such proliferation. The colonies of bacteria then create high pressure areas within the top bed surface, thereby diverting the water to less high density areas of the filter bed. The result of this is to create high velocity areas, which in turn causes channelling, sometimes known as rat holing, and the result is filter media bypass and a loss of filtration efficiency. When the filter is backwashed the higher density bacterial colonies are heavier than normal contamination and are therefore less likely to be removed under the backwashing process, they therefore remain within the bed to act as seed for the next batch of dirty water. This results in ever shortening periods between backwash times using more and more backwash water which is run out to waste treatment. Filtration efficiency is typically less than 80% at 10-20 micron. In our previous application number GB0811513.1 the introduction of the water to be filtered is by means of a top mounted tangential main inlet. This gives the water a circular motion within the filter vessel which prevents surface binding or clogging.

The introduction of the water in this manner allows the special filter media - Advanced Filter Media - to be in constant circular rotation and this action grades the surface media into fine and ultrafine granules, the fine granules remain in rotation at the interface between the water and the filter media, whilst the ultrafine media becomes fluidized and occupies the water space above the bed, this allows interaction between the latent electrical charge of the media and the opposing charge of the fine contamination to attract each other enabling the filter to filter down to less than 1.0 micron, this takes place in the water space above the filter primary bed.

As the attraction increases the total density of the ultrafine media increases and it sinks to the fine media layer where the rotational effect of the water scrubs the ultrafine media free of the attracted contamination, at this point the accumulated contamination is retained by the primary rotating bed whilst the ultrafine media is again released to the upper reactive zone of the incoming water above the bed. In this manner this filter can remove contamination to lower than 1.0 micron in size.

The rotation of the bed caused by the tangential main inlet creates differing water/media velocities across the full width of the vessel, this in turn creates a pilling of the media in the low velocity central zone which take the form of a conical mound with the lowest section at the periphery of the vessel and its height at the centre of the vessel. This phenomenon leads to contamination break through at the lower sections of the cone.

In order to eliminate this, our previous patent application GB 0811513.1 , covers the introduction of a percentage of the inlet process water which is re directed via a secondary inlet which is much smaller than the main inlet and is known as the Vortex Stabiliser. This secondary supply is introduced into the filter at a centre line position close to the flat height of the filter media level. The secondary water flow is introduced tangentially into the centre of the media cone and this is sufficient to cause the cone to collapse and reform within the normal flat bed level of the filter. This gives the moving media bed a flat uniform depth across its total area which is fluidised and in rotary motion, but still releasing ultrafine media into suspension above the main rotating bed, this enables this system to filter water down to below 1.0 micron. The vortex stabiliser has been designed to produce 4 jets of water which are presented into the vessel in a tangential flow, this has the effect of producing a media bed which is rotating and fluidized and of an even depth. This enables the filter to perform at high flux rates whilst maintaining a high efficiency in the removal of fine solids. The present invention introduces significant improvements to the Vortex Stabiliser in combination with modified advance filter media. According to the invention the basic shape of the Vortex stabiliser has changed from a hollow disc with 4 off tangential holes, to a profiled machined part with expanding cross sectional area consisting of upper main body and lower threaded insert. This change of profile allows for the addition of a set of radial drilled fine spray holes to be strategically positioned in the upper main body of the stabilizer which are additional to the lower main spray jets. Four hole positions are preferred but any number may be used. These holes are set on a radial angle to the rotation of the media bed. This modification causes the very fine elements of the modified advanced media bed, which is rotating and fluidized, to aggressively mix with the incoming water in void space above the media which we now define as the "Media interaction zone". The new holes are manufactured to give a broad angle spray of water delivered radially and upwards to the centre of the vessel. This fine spray of water acting only on the finer elements of the media causes the fine grade of the filter bed media to be diffused into the incoming water volume in the "media interaction zone".

This fine media has a latent static electrical charge, and by dispersing sufficient amounts of this media into the "media interaction zone"; which is the water inlet volume, sited above the filter bed; significant additional removal performance can be achieved. By these radial jets only interacting with the fine grade of media, (the smaller the grain the larger to surface area available) we achieve a high mixing interaction between the incoming contamination and the media. The original tangential holes have been re positioned to tangentially orientate as before but also slightly downwards onto the bed, This ensures that the finer elements of the media are "thrown" up to a position to be captured by the new spray jets. The bed still maintains a flat rotating profile. This allows a major interaction to occur between the media and the fine contamination and the latent electrical charge of the media attracts the fine contamination by means of electrical attraction. The attraction of the contamination to the media continues until the mass becomes too heavy to remain in suspension over the bed, this then falls onto the rotating bed, the circular motion of the bed ensure bed fouling cannot occur, eventually this process loads the void above the bed with high residual solids causing the filter to backwash.

The advantage of this modification to the process flow is significant, namely increasing the processing time "on line" by some 30% over the previous design, this reduces total backwash water losses for the process by backwashing less frequently. The modification also allows a reduction in the backwash time by up to 50% due to the fact that the majority of the contamination is contained within the void water volume above the bed - this reduces backwash water waste and energy. In addition the removal of finer solids is improved due to the increase in interaction of the media and the contamination improving overall efficiency by up to 8%. This new innovation to the Vortex stabiliser has no detrimental effect on the original process claims and maintains a rotating fluidized bed with all of the benefits defined in our previous application. g

As mentioned previously, construction of the of the Vortex stabiliser has changed from a hollow disc with 4 off tangential holes, to a profiled machined part with expanding cross sectional area consisting of upper main body and lower threaded insert. This allows the introduction of variable geometry tangential slots which replace the tangential outlet in our previous application.

To form the lower main spray jets a threaded insert is provided which in use screws into the bottom of the upper main body of the vortex stabilizer. This insert contains vertical slots which provide the lower main spray jets. The insertion depth of the threaded insert determines the geometry of these spray jets in that the further the insert is screwed into the main body the shorter are exposed areas of the vertical slots. Therefore the geometry of the vertical slots can be changed by the depth of the engaged screw thread. The number of slots is preferred to be four but any number may be used.

The invention will now be described by way of example with reference to the drawings in which. - Figure 1 Is a cross section of the water filter showing all of the working parts including the media filters.

Figure 2 Is a detailed drawing of the vortex stabiliser with the lower threaded insert partially inserted.. Figure 3 Is a further illustration of the vortex stabiliser with the lower threaded insert fully inserted reducing the exposed length of the vertical discharge slots. Figure 4 Is Cross section of the vortex stabiliser.

Figure 5 Is a top view showing the position of the upper radial drilled fine spray holes. Figure 6 Shows a cross section of the lower threaded insert illustrating the angle of the lower main spray slots.

Figure 7 Is a view of the upper main body. Figure 8 Shows the lower threaded insert containing the vertical slots.

Referring now to figure 1 , the filter vessel 1 , is fed at the top by the main inlet pipe 2, through inlet valve 3 and on to tangential main outlet 8. The inlet flow is divided and part of the flow goes into secondary inlet pipe 4, it passes through the flow adjustment valve 6, and travels on to the distribution head 7 known as the vortex stabiliser. In this mode the valve 10, in pipe 11 is closed. The main water volume is presented to the vessel in a tangential manner via pipe entry 2 and outlet 8, this main tangential flow creates the vortex within the top of the plenum chamber. The inlet 8, from the main inlet pipe 2, is in the side of the vessel therefore the water flow within the vessel would tend to be circular or tangential. However the flow in these arrangements tends to thin down the level of the filter media on the periphery of the vessel and carry it to the centre of the vessel where it builds up so that the level of the top of the filter media is a slope downwards from the centre or one side of the vessel. The effect of this is to reduce the efficiency of the filter media by allowing breakthrough of water to the support media, as this presents itself as the area of least resistance. To overcome this difficulty in the present invention the vortex bed stabiliser 7, also inputs water through holes 9 and 9a. These holes are arranged so that a further circular or tangential motion is imparted to the water flow.

The secondary water flow is along pipe 4 through valve 6, and on to the vortex bed stabiliser 7 where it exits into the upper plenum chamber via discharge holes 9 and 9a. The angle of the discharge holes 9 and 9a is arranged to facilitate a circular motion in the water flow.

The flow arrangements so far described have the effect of stabilising the media by dispersing the conical build up created by the inlet vortex in the top filter and thereby eliminating the possibility of water by pass within the bed seen in other filters of this type. The flow arrangement described also ensures that biological colonisation cannot occur. The continual motion of the filter media eliminates the possibility of biological fouling. _Π

Flow through the filter system itself follows conventional practise in that water passes through different layers of media shown as 16, 17, 18, 19, in figure 1. These layers are gradually coarser until layer 19 which is the coarsest of all. The water then passes through nozzles 20 into a lower plenum chamber 21 and finally leaves the filter through valve 14 into pipe 15. During normal flow, valve 12, the backwash inlet valve, would be closed.

The backwashing operation would reverse the flow by closing valve 14 and opening valve 12 at the bottom of the filter and closing valves 3 which in turn stops the flow to valve 6 and opening valve 10 at the top of the filter. The flow would then be from pipe 13 to pipe 11 , upwards through the filter. The backwash water is of such a flow that the bed is fluidised which in turn releases all of the contamination contained within the filter bed and within the top plenum chamber, this is ejected via pipe 11 , to waste, the backwashing process lasts 5- 6 minutes which is far less then conventional filters due to the volume of contamination held away from the bed by the action of the vortex and associated stabiliser.

Referring now to figure 2, construction of the vortex stabiliser can be seen more clearly. Connected to supply pipe 4 by means of a screw thread is the main upper body of the vortex stabiliser 7. Located in the upper main body 7 are radial drilled fine spray holes which are upward facing nozzles 9a also known as media suspension nozzles. These nozzles may be in one of at least three possible style variations. Firstly a cone style which gives large area coverage with good dispersion in the cone's limit of influence. Secondly a horizontal fan style or horizontal ellipse, which gives lift in the vertical axis to the suspended media. Thirdly there is a vertical fan or vertical ellipse arrangement, which gives vertical dispersion to the media in suspension. The addition of these jets 9a, causes the very fine elements of the advanced media bed; which is rotating and fluidised; to aggressively mix with the incoming water in the void space above the media which area can be defined as the media interaction zone.

The main jets 9 are located in the lower part of the vortex stabiliser 7 and are variable geometry tangential slots. These are formed by a threaded insert or plug 10 which screws into the base of the upper main body 7, and in this insert are the vertical slots which are cut to provide a tangential water flow. The volume of the flow can be varied by screwing the insert or plug in or out by applying a tool to the integral hexagonal bolt head 11.

The combination of the number of tangential slots in the threaded insert or the spray nozzles in the upper main body can be varied from filter to filter to optimise performance. This will depend on the differences in the diameter of the filter vessel, the media being used in the vessel, the water volume and/or the application to which the vessel is put.

Further clarification is provided by Figure 3 which shows the same anrangement as Figure 2 but with a reduced water flow which is achieved by screwing the threaded insert further into the main body. Figure 4 is a cross sectional view where the full extent of the slots 9 can be seen. These slots are tangential but may be left or right hand orientated and may also be cut to encourage a slightly downward flow.

Figure 5 illustrates the flow from the upper nozzles as seen from above and Figure 6 shows the flow from the lower main jets.

Finally referring to Figures 7 and 8 a three dimensional view of the two main components of the vortex stabiliser can be seen. The upper main body is shown in figure 7 and the threaded insert is shown in figure 8. The slots 9 and bottom edge of the upper main body 7 may be formed to encourage a downwards water flow by providing a downwards angle on the horizontal surfaces over which water passes.

The term "Vortex Stabiliser" in this specification is a registered trademark belonging to the applicant and is intended to be a functional description and to include any secondary water inlet in addition to the main water inlet which by directing a secondary water inlet flow is intended to assist in stabilising the movement of the filter media comprising the top media bed and is not intended to be limited to the positions shown in the drawings or to the shape and configuration of the vortex bed stabiliser 7, shown in the drawings.

Claims

2013/045868 14 CLAIMS

1. A vortex stabilizer which terminates a main water inlet pipe in a down flow type of media water filter system characterised in use in that the said stabiliser comprises an upper main body connected to the said inlet pipe containing a plurality of radially drilled fine spray holes and a lower threaded insert which engages with the main body and is equipped with a plurality water outlets which are cut tangentialiy into the threaded side wall of the said lower threaded insert so as to provide a water jet which is tangential to side wall of the vortex stabiliser.

2. A vortex stabiliser according to claim 1 in which in use a lower threaded insert is provided with water outlets comprising vertical slots cut tangentialiy into the threaded side wall of the said lower threaded insert so that the depth to which the lower threaded insert is engaged with the upper main body determines the size of the tangential water outlet.

3. A vortex stabiliser according to any previous claim in which the said plurality of radially drilled fine spray holes which are cut into the main body may be positioned at a variety of different angles relative to the outer wall of the main body.

4. A vortex stabiliser according to any previous claim in which the said plurality of radially drilled fine spray holes which are cut into the main body may be positioned into groups of more than one spray hole and where the diameter of any hole may different to its next nearest hole.

5. A vortex stabiliser according to any previous claim in which in use a lower threaded insert is provided with water outlets comprising vertical slots cut tangentially into the threaded side wall of the said lower threaded insert so that the depth to which the lower threaded insert is engaged with the upper main body determines the size of the tangential water outlet and where the said vertical slots and or the main body are cut so as to provide a downward angle to the water flow.

6. A lower threaded insert for use with a vortex stabiliser as claimed in any previous claim which is equipped with means for attaching a spanner or suitable grip for the purpose of screwing the said inset into and out of the said main body.

7. A vortex stabiliser according to any previous claim which in use is threaded at the top so that it can engage with the downward pointing threaded end of a vertical outlet pipe.