Fluid distributor and method of distributing fluid

Abstract

A fluid distributor 200, comprises a group of at least two channels 210 arranged in substantially the same plane, the plane being orthogonal to an axis of the distributor which in use extends substant

Description

Technical Field The present invention relates to a fluid or liquid distributor and to a method of distributing fluids or liquids employing a distributor. The distributor may be employed in an evaporation or condensing unit used in the treatment of a fluid. The fluid may be contaminated and the treatment may comprise reducing or removing one or more contaminants from the fluid. An example of a contaminated fluid is water contaminated with salts and / or solid matter. Solid matter may be present if the fluid is from an anerobic digester, for example. The distributor may be employed in any situation where a distribution of droplets of fluid is required. For example, in cooling towers, in irrigation, or when applying chemicals to a surface, such as the application of fertilizer or the application of an industrial surface finish. Although the preferred embodiment described below relates to the use of the distributor in an evaporation or condensing unit used in the reduction or removal of one or more contaminants from a fluid, the invention is not to be construed as being limited to this specific application. Background A known fluid distributor for use in an evaporation or condensing unit used in the treatment of a fluid is disclosed in WO2015 / 114342 (Solaquagen Limited). The distributor comprises two concentric circular channels with a separate fluid feed pipe to feed fluid from underneath to each channel. There is a need to balance the flow of fluid to each channel to take into account the relative sizes / volumes of each channel. Another fluid distributor is disclosed in US 6,722,639 (Ender et al., assigned to Koch-Glitsch, LP) which is a distributor with linear channels. In this distributor, debris can accumulate at the ends of the channels and the holes in the sides of the channels may become blocked. There is a need to address issues with prior art distributors. There may also be a desire to control and optimise the size of droplet falling from the distributor, to customise the droplet pattern, and / or to optimise the distribution of droplets per unit area. In the context of a thermal evaporative process, a more uniform distribution of droplets may help to reduce the energy requirements of the process. Controlling the droplet size and distribution may also help to avoid flooding the fragmentation bodies below the distributor. Summary of the Invention In accordance with a first aspect, the invention provides a fluid distributor, comprising a group of at least two channels arranged in substantially the same plane, the plane being orthogonal to an axis of the distributor which in use extends substantially vertically, wherein each channel is continuous and comprises a base and two upstanding side walls, wherein each channel is spaced from the adjacent channel by an aperture through the distributor, each channel being configured such that fluid supplied to the channel is able to flow over one or both side walls and fall from the distributor, and wherein each channel is connected to the adjacent channel by a bridge section configured to provide fluid communication between the channels and to distribute fluid to the channels. Each channel is continuous, which means that there is no end or stop in the channel. For example, a linear channel is not continuous as the channel stops at each end. In effect, the fluid is able to circulate around the channel in a loop. The shape or path of the channel (in plan view) may be any suitable shape for the application, for example circular, oval, rectangular, square or irregular. The at least two channels making up the group are arranged in substantially the same plane, which may generally be the horizontal plane in use. This, combined with each channel being continuous, effectively requires that the channels lie one inside the other. There may be a central channel, which is the smallest in terms of a width dimension in plan view, and one or more channels will be positioned outside and around the central channel, each one being progressively larger in width than its inner adjacent channel. The channels of the group may be considered to be nested. The channels may have the same centre, and may be concentric, but this does not imply that the channels are circular, although a group of concentric, circular channels is one preferred arrangement. A channel in the group is connected to the adjacent channel in the same group by a bridge section which is configured to provide fluid communication between the channels. The bridge section effectively crosses the aperture between the adjacent channels. Therefore, the aperture between two channels is divided into aperture sections by the bridge section. More than one bridge section may be provided between adjacent channels, and the aperture will be divided into the corresponding number of aperture sections accordingly. The number of bridge channels may be varied according to the size and layout of the distributor channels. If the group comprises more than two channels, the bridge sections may or may not be aligned in the direction of fluid flow. In a preferred arrangement, the group comprises at least three channels and bridge sections connecting different channels are aligned to form a bridge channel connecting all channels of the group. The bridge sections and / or channel may extend in a direction substantially orthogonal to the direction of fluid flow within each channel. If the bridge sections are not aligned in the direction of fluid flow, the bridge sections may be offset from each other. This may help to generate turbulence and reduce the build-up of deposits in the distributor. In an alternative embodiment to the bridge sections being aligned therefore, bridge sections connecting different channels of the group are offset from each other. In a preferred arrangement, a plurality of bridge channels are provided. Each channel may be substantially circular in plan. The one or more bridge channels extend radially. As mentioned above, the circular channels may be concentric. Each channel has a base and two upstanding side walls. In cross-section, i.e. viewed along the plane of the group of channels, each channel may have a generally U-shaped section. The base may be flat, curved, concave or V-shaped. Other cross-sectional shapes for the channel may be suitable. In a preferred embodiment, the channel side walls have an upper edge and the upper edge of at least one side wall of each channel is provided with a plurality of notches spaced around the circumference of the channel. The notches are useful for controlling the exit point of the fluid from the channel. In a further embodiment, both side walls are provided with notches. The notches may be any suitable shape, such as V-shaped, U-shaped, square, curved, semi-circular, etc. In a preferred arrangement, the notch is V-shaped. In a further preferred embodiment, each side wall is provided with a projection vertically below each notch, which depends downwardly from the sidewall, configured to provide a location for the fluid flowing from the notch to form droplets which fall from the distributor. The projection may be any suitable shape to facilitate droplet formation, such as V-shaped, U-shaped, square, curved, semi-circular, etc. In a preferred arrangement, the projection is V-shaped. The distributor may include an inlet or point of supply which is configured to supply fluid to the distributor. A single inlet may be provided, or two or more inlets may be provided. If two or more inlets are provided, the fluids supplied by each inlet may be the same or different. If the fluids are different, the distributor may function as a means of mixing the two fluids. The inlet is preferably configured to supply fluid to the distributor from above the distributor in use, i.e. in a vertically-downwards direction relative to the distributor. The fluid may be supplied into a channel or into a bridge section, or into another part of the distributor in fluid communication with the channel and bridge section network of the distributor. The inlet or the point of supply is preferably located below the level of the upper edge of the channel side walls. The group of connected channels may comprise all of the channels of the distributor or fewer than all of the channels. The distributor may include one or more further channels not connected to the group of connected channels. There may be any appropriate number of channels in the group, for example 3 or more, 4 or more, 5 or more, 3 to 10, 3 to 8 or 4 to 6 channels. In a preferred embodiment, the group of at least two connected channels is a first group of connected channels and the distributor further comprises a second group of at least two connected channels, wherein the first group and the second group are not in fluid communication. The second group may comprise any of the features of the first group discussed above. The first group and the second group may or may not be in the same plane. The second group may be axially-offset from the first group. The distributor may further comprise a first inlet configured to supply a first fluid to the first group of connected channels and a second inlet configured to supply a second fluid to the second group of connected channels. The first fluid and the second fluid may be the same fluid or different fluids. In accordance with a second aspect, the invention provides a unit for evaporating or condensing a fluid comprising a distributor as discussed above. In accordance with a third aspect, the invention provides apparatus for evaporating and condensing a fluid comprising an evaporating unit and a condensing unit, wherein each unit includes a distributor as discussed above. In accordance with a fourth aspect, the invention provides a method of distributing fluid, comprising supplying fluid to the distributor discussed above and distributing the fluid. In accordance with a fifth aspect, the invention provides a method of distributing fluid employing the distributor discussed above having a first group of connected channels and a second group of connected channels, wherein the first group and the second group are not in fluid communication, the method comprising supplying a first fluid to the first group of connected channels, supplying a second fluid to the second group of connected channels, and distributing the fluids. At least in preferred embodiments, the connected network of channels and bridge sections allows a single entry pipe to supply fluid to the distributor. The bridge sections distribute fluid to the continuous distributor channels evenly and automatically. A single feed pipe simplifies the construction, reduces cost and reduces energy requirements. By supplying the fluid from above, feeding downwards into the distributor, a water jet / fountain effect experienced with an upwardly-directed feed through the channel base can be avoided. If the inlet is located below the top of the side wall, the inlet will be normally submerged during operation which prevents splashing. The shape and size of the notches in the channel side walls can be selected to match the requirements of the fluid flow stream. The projection below each notch maintains the definition of vertical fluid streams and the size of the droplets formed. The projections enable the required number of water wetting points to be specified. Without the projections, water may collect at the bottom of the side wall and build up, possibly joining other drips before dropping. The quantity and shape / design of the notches and projections can be modified to suit varying design parameters, including capacity and type of fluid, to form an optimum flow and drop size, and distribution pattern. In an evaporation or condensing unit, controlling the droplet size and distribution may help to avoid flooding the fragmentation bodies below the distributor, rather than wetting them, so that air can pass through in the opposite direction. Several features of the invention may help to limit the build-up of scale and deposits. Continuous channels avoid dead-ends where deposits can build up. Notches are employed in the side walls instead of holes to avoid scale build-up closing the holes in time. V-shaped (and other shaped) notches reduce clogging and allow more regular and even drop formation. Overall, the distributor of at least preferred embodiments is designed so that any buildup of sediment or scale does not affect the flow of the distributor and the formation of droplets. Maintenance may therefore be less frequent than with prior art distributors. The distributor has reduced energy requirements and can be manufactured and operated at reduced cost. Brief Description of the Drawings Embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Fig. 1 shows a schematic diagram of a purification system employing the distributor of the present invention; Figs. 2A and 2B show plan and side elevation views respectively of a distributor in accordance with a first embodiment of the invention having a single group of connected channels; Fig. 3 shows a perspective view of the distributor; Fig. 4 shows an enlarged view of a notch and a projection of the distributor; and Figs. 5A and 5B show plan and perspective views of a distributor in accordance with a second embodiment having two groups of connected channels with the groups not being in fluid communication. Detailed Description of a Preferred Embodiment Fig. 1 shows a schematic diagram of a purification system employing the distributor of the present invention. Fig. 1 shows an evaporation unit 10 and a condensing unit 110. Condensing unit 110 is configured similarly to the evaporation unit 10 and corresponding reference numerals preceded by '1' are employed. The evaporation unit comprises a chamber 12 having a contaminated fluid feed 14 at its upper region 16. The chamber is divided up into five evaporation zones 20 defined at their lower ends by support grilles 18. In the illustrated example, all evaporation zones contain fragmentation bodies 22, for example pall rings or Raschig rings. At the lower region 24 of the chamber 10, a heated air inlet 26 is provided ("return air" from the condensing chamber 110). In use, the evaporation unit 10 is fed with warm or hot fluid via feed 14. The fluid is fed into distributor 19, which is described in more detail below. The support grilles 18 and distributor 19 may be circular, square or rectangular in shape, or be of other shapes. The openings in the support grilles 18 and distributor 19 may be of variable shape and be provided in a regular or irregular pattern, or of different sizes or configurations. The hot fluid fed into the distributor 19 flows over the notches of the distributor and generates hot droplets of the fluid, which fall by gravity, through the chamber 10. The drops are further fragmented into smaller droplets by contacting a fragmentation body 22 such as an electrochemically inert random packing material. Such a material may be plastic, ceramic or stainless steel packing rings, for example Raschig rings. The choice of fragmentation body depends on the type of fluid to be treated and the operating temperatures. The fragmentation body 22 is supported by an electrochemically inert support grill 18 which allows the fluid drops to pass into the next section. Simultaneously, heated air is pumped into the chamber 10 via heated air inlet 26 by fans into the lower region 24 of the chamber 10. The passage of heated air through the hot fluid droplets and fragmentation bodies 22 creates evaporation, saturating the air with fluid vapour at varied temperatures. The residual concentrated contaminant is collected at the bottom of the chamber for eventual discharge via contaminated waste drain 30. In order to maximise evaporation, the air speeds through the evaporation zones 20 are varied by configuring and optimising the heights of each zone 20, thus adjusting the volume that the air / vapour mix must pass through with the relevant input power from the fan. The variation of air speed thus achieves a similar effect to that of lowering the air pressure at a lower energy cost. Fluid which has been evaporated can be removed from the chamber via a series of fluid vapour outlets 32 and are carried away via fluid vapour lines 34. Barriers 36, for example bodies formed of Munters DRIFdek or similar material, are placed at the outlets from the chamber 10 to prevent any cross contamination of droplets in the air / gas flow and also to prevent any other possible contamination issues e.g. legionella. As can be seen, each evaporation zone 20 is provided with a vapour fluid outlet 32 at its upper end. The contaminated fluid fed into the evaporation unit is heated through heat exchange with a heat source 50 which may be a source of waste or exhaust heat from an industrial process, or may be provided by an alternative energy source. In the lower region 24 of the evaporating chamber 10, contaminated fluid / sludge is periodically drained via contaminated waste drain 30 for recycling or disposal. Contaminated fluid feed 54 is split into a fluid take-off line 60 and a feed which is heated by heat exchange (heat exchanger 64) with fluid exiting the condensing chamber 110 via purified fluid outlet 56. The contaminated fluid feed is then passed back into the evaporation chamber 10 via heat exchanger 62 and then via contaminated fluid inlet 14. Condensation zones 120 within the condensation chamber 110 are fed with fluid vapour extracted from evaporation zones 20. Condensing fluid is fed into the distributor 119 which then fragments and passes through the condensing chamber 110 under gravity, in a similar manner to the fluid in the evaporating chamber 10. As this fluid passes through the chamber 110, additional fluid condenses from the cooling saturated vapour. This additional purified fluid is then collected in the lower region 124 of the chamber 110 and extracted therefrom via purified fluid outlet 56. In the illustrated device, similar to the evaporating unit, condensation zones 120 contain fragmentation bodies 122 supported on support grilles 118. Due to the process of condensation, the condensing fluid becomes warmer. This warmed purified fluid is passed via line 56 to a crossflow heat exchanger 64 where the acquired heat is recovered and used to pre-heat the contaminated fluid. The feed of purified fluid 56 is then split into a purified fluid take off line 58, with the remainder of the purified fluid being passed to external chiller 150 for further cooling before being passed into the condensing chamber 110 via cooling fluid inlet 114. The fluid vapour outlet lines 34 carry the evaporated fluid from specific evaporation zones 20 to the most appropriate condensing zones 120 to maximise evaporation and condensation driven by fans 66. As can be seen, the uppermost evaporation zone 20'which operates at the highest temperature of all of the evaporation zones is connected via line 34 to the lowermost condensation zone 120" which operates at the highest temperature of the condensation zones. The lowermost evaporation zone 20" which operates at the lowest temperature is connected to the uppermost condensation zone 120' which operates at the lowest temperature of the condensation zones. The second hottest and second highest evaporation zone is connected to the second lowest and second hottest condensing zone, and the second coolest and second lowest evaporation zone is connected to the second highest and second coolest condensation zone. This system of interconnection can be continued for any number of evaporation / condensation zones. Condensing chamber 110 is provided with a heated air outlet 126 which carries heated air which may contain a small amount of fluid vapour into the evaporation unit via heated air inlet 26. The residual purified fluid is collected at the bottom of the chamber for periodic discharge via purified fluid drain 130. Figs. 2A, 2B and 3 show a distributor 200 which can be employed as the distributors 19 and 119 in the evaporating chamber 10 and condensing chamber 110 respectively of the system described with reference to Fig. 1. Distributor 200 is shown as circular in plan view, although as discussed above, the distributor can be any suitable shape to suit the cross-sectional shape of the evaporating chamber 10 or condensing chamber 110 in which it is employed. In this example, distributor 200 comprises five circular, concentric channels 210, each comprising a base 211 and upstanding side walls 212 and 213 forming a U-shaped section. Each channel is continuous and therefore is not closed by an end wall. There can be any number of channels, all of which are connected in this embodiment to form a single group of connected channels. Each channel 210 is connected to the adjacent channel by a plurality of bridge sections 220 configured to provide fluid communication between the channels and distribute fluid to the channels. In this embodiment, each bridge section 220 is aligned to form a radially-extending bridge channel 221 connecting all channels of the distributor. Three radial bridge channels 221 are provided, equally spaced at 120 degree intervals. It will be appreciated that the number of bridge channels may be varied according to the size and layout of the distributor channels and linkage between the channels may not necessarily be radial or aligned. Each channel 210 is spaced from the adjacent channel by an aperture 230 through the distributor. In this embodiment, due to the presence of three bridge channels, the aperture 230 is split into three sections between each channel 210. In use, fluid is supplied to the distributor 200 via inlet pipe 300 (feeds 14 or 114 shown in Fig. 1) and is distributed evenly to the channels 210 via the bridge sections 220. Pipe 300 provides a single inlet to the distributor. In this embodiment, the pipe is configured to supply the fluid to the second channel from the centre of the distributor, although other locations will work equally as well. The fluid is supplied from above, feeding downwards into the channel 210. The outlet of the pipe 300 is below the top of the side walls 212 and 213 so that the pipe is normally submerged during operation, which prevents splashing. The downwardly-directed feed avoids a water jet or fountain effect. The arrows in Fig. 3 show the general path of the fluid around the distributor from the pipe outlet. The top edges of the side walls 212 and 213 of each channel 210 are provided with a plurality of V-shaped notches 214 spaced around the circumference of the channel. Vertically below each notch 214, a corresponding V-shaped projection 215 is provided which extends downwardly from the side wall 212 and 213. Projection 215 could be other shapes as noted above. In use, when the level of fluid in a channel 210 reaches and then exceeds the level of the notches 214, the fluid will flow over the side walls through the notches. The notches provide a defined exit point for the fluid from the channel. The projections 215 below each notch provide a point at which the fluid flowing from the notch forms droplets, which fall into the chamber below. Fig. 4 shows an enlarged view of a notch 214 and a projection 215 of the distributor 200. The dashed arrows in Fig. 3 show the path of the fluid from the inlet pipe 300 to the notch 214 and via the corresponding projection 215, before falling as droplets into the chamber below. Figs. 5A and 5B show plan and perspective views of a distributor in accordance with a second embodiment. In this embodiment, the three inner channels 210 are connected to form a first group 201 of connected channels and the two outer channels 210 are connected to form a second group of connected channels 202. There are no bridge sections 220 between the third and fourth channels. The first group is supplied with fluid from inlet pipe 301 and the second group is supplied with fluid from inlet pipe 302. In this embodiment, the groups are in the same plane.

Claims

1. A fluid distributor, comprising:a group of at least two channels arranged in substantially the same plane, the plane being orthogonal to an axis of the distributor which in use extends substantially vertically,wherein each channel is continuous and comprises a base and two upstanding side walls,wherein each channel is spaced from the adjacent channel by an aperture through the distributor, each channel being configured such that fluid supplied to the channel is able to flow over one or both side walls and fall from the distributor, andwherein each channel is connected to the adjacent channel by a bridge section configured to provide fluid communication between the channels and to distribute fluid to the channels.

2. The distributor of claim 1, wherein the group comprises at least three channels and wherein each bridge section is aligned to form a bridge channel connecting all channels of the group.

3. The distributor of claim 2, further comprising a plurality of bridge channels.

4. The distributor of claim 1, wherein bridge sections connecting different channelsof the group are offset from each other.

5. The distributor of any preceding claim, wherein each channel is substantially circular.

6. The distributor of claim 2 or 3, wherein each channel is substantially circular and wherein the one or more bridge channels extend radially.

7. The distributor of claim 5 or 6, wherein the channels are concentric.

8. The distributor of any preceding claim, wherein the channel side walls have an upper edge and wherein the upper edge of at least one side wall of each channel is provided with a plurality of notches spaced around the circumference of the channel.

9. The distributor of claim 8, wherein both side walls are provided with notches.

10. The distributor of claim 8 or 9, wherein each side wall is provided with aprojection vertically below each notch, which depends downwardly from the sidewall, configured to provide a location for the fluid flowing from the notch to form droplets which fall from the distributor.

11. The distributor of claim 10, wherein the projection is V-shaped.

12. The distributor of any preceding claim, further comprising an inlet configured to supply fluid to the distributor.

13. The distributor of claim 12, wherein the inlet is configured to supply fluid to the distributor from above the distributor in use, and preferably wherein the inlet is located below the level of the upper edge of the channel side walls.

14. The distributor of any preceding claim, wherein the group of at least two connected channels is a first group of connected channels and the distributor further comprises a second group of at least two connected channels, wherein the first group and the second group are not in fluid communication.

15. The distributor of claim 14, further comprising a first inlet configured to supply a first fluid to the first group of connected channels and a second inlet configured to supply a second fluid to the second group of connected channels.

16. The distributor of claim 15, wherein the first fluid and the second fluid are the same fluid.

17. The distributor of claim 15, wherein the first fluid and the second fluid are different fluids.

18. A unit for evaporating or condensing a fluid comprising the distributor of any preceding claim.

19. Apparatus for evaporating and condensing a fluid comprising an evaporating unit and a condensing unit, wherein each unit includes the distributor of any of claims 1 to 17.

20. A method of distributing fluid, comprising supplying fluid to the distributor of any preceding claim and distributing the fluid.

21. A method of distributing fluid employing the distributor of any of claims 14 to 17, comprising:supplying a first fluid to the first group of connected channels;supplying a second fluid to the second group of connected channels; and distributing the fluids.

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