GB2418374A

GB2418374A - Separator

Info

Publication number: GB2418374A
Application number: GB0500254A
Authority: GB
Inventors: Damone Armstrong
Original assignee: INVERT GROUP Ltd
Current assignee: INVERT GROUP Ltd
Priority date: 2004-09-27
Filing date: 2005-01-07
Publication date: 2006-03-29
Anticipated expiration: 2025-01-07
Also published as: GB0500254D0; IE20050011A1; GB2418374B; GB0421320D0

Abstract

A separator for separating hydrocarbons from surface water before entering a drainage system comprises a filter unit 6 and housing mounted upon an upper section of a sedimentation tank 3. The filter unit comprises a pipe 7, projecting from the lower portion of the housing and into the tank. Surface water enters the housing via inlet 17 passes through a skim hole 19 and into the tank, where silt is deposited. The static head of the water forces water with some hydrocarbons up the pipe 7, coalescent filter material 9 removes hydrocarbons, and cleaner water passes out outlet 18. In storm conditions the skim hole 19 chokes and excess water is directed over weirs 15, which may be screened to prevent ingress of debris, and passes directly out of outlet pipe 18 thus bypassing the filter material 9. A probe holster 20 is provided so that the amount of silt in the tank may be detected. The positioning of the filter unit in the upper section of the tank prevents blockage by silt and facilitates easy removal. The pipe 7 provides easy access to the lower part of the tank using a suction hose for the removal of silt and includes a nut and bolt 13 14 which may be used as a carry handle.

Description

241 8374 A Separator

Field of the Invention

This Invention relates to separators for capturing oll and silt entrained with surface water, and in particular to separators used for collecting run-off surface water from hard-standings such as car parks, fuel station forecourts, airport runways, roadways, etc.

Background of the Invention

From time to time cars parked In car parks leak oil. There is also the possibility that petrol and diesel may leak from vehicles. Such leaked oil/fuel is 111 the course of time washed away from the site of the initial spill by rain water, ultimately funding its way into surface water drains. (contamination of surface water by hydrocarbons IS not desirable and in the United Kingdom legislation has been introduced requrmg the surface water drainage systems of car parks to be provided with means for separating ol/fuel from water, such that only water containing less than a certain threshold (5mg/]itre) of oil/fuel is discharged into the surface water drains. Whilst there is a risk of contamination of surface water by oil/fuel in car parks, hence the legislation, there is nevertheless a recogmton that the risk is low. For this reason the separator Is required to be able to capture and retain all surface water run-off from a car park when rainfall is up to 5mm / hour.

Separators have been developed and are In use in hard-standing areas, such as car parks. These separators Include a tank, and mounted inside the tank a filter. These separators indude a filter and are designed to capture all surface water run-offwhen rainfall Is up to 5mm / hour, but In storm conditions to switch to a by-pass mode whereby no water passes through the filter. In use, these tanks are butted in the ground. Surface water run-off enters the tank where oil/fuel fraction migrates to the top of the liquid In the tank and small particles suspended m the liquid fall out of suspension to the bottom of the tank. An outlet from the tank Is connected to an outfall to a main surface water drain. The path between the tank and the outfall includes the filter. Any water exiting the tank must pass through the filter before entering the sewage system. The type of filter commonly used is a coalescent filter.

As mentioned above, a factor which must be taken into account when desgnmg a separator for collecting ol/fuel entrained with surface water is that small particles are held in suspension with the surface water. These small particles will be referred to herein as silt. Once in the separator a large proportion of entrained silt will tend to fall out of suspension with the water. This poses problems insofar as the separator must be emptied of silt penodcally. Also, commonly used separators mount the coalescent filter for extracting the oil/fuel fraction from the water at the bottom of the tank. The build up of silt in the bottom of the separator can render the filter neffecuve. A number of proposals have been made for dealing with the problem associated with silt. In some separators silt traps are provided up stream of the separator. In other separators additional access manholes are provided to allow vacuum tanks to suck silt laden sludge from a separate silt chamber in the tank.

In known separators, the coalescent filter consists of a sleeve of filter material which is mounted on the outer surface of a perforated tube. lthe downstream end of the perforated tube connects directly or indirectly to a sewage outfall. Any I/fuel not separated from the water must pass through the filter in order to reach the sewage outlet.

One problem associated with known arrangements of the biter is that their exposure to the contents of the tank results in large amounts of silt falling out of suspension with the water collecting on the surface of the filter material. This can lead to the sleeve of filter material being dragged down by the weight of slit gvmg rise to two undesirable effects. First, the filter material does not work as effectively, and second the perforations of the pipe may be exposed allowing potentially contaminated water lo be discharged to the outfall without the filtration required by environmental regulations.

Another problem associated with current separator designs is that of access to the filter unit. As mentioned above, the type of filter used Is usually a coalescent kilter. This type of filter must be either cleaned or replaced from time to time. l ocaton of the filter at the base of the separator tank makes access thereto difficult. Some proposals have been made to mount he filter unit on a hft mechanism, but this adds complexity and can be dfEcult to achieve withm the restricted dimensions of a separator tank.

It would therefore be desrablc to provide an improved separator.

Summary of the Invention

Accordhug to one aspect of the invention, there Is provided a separator as specified in Claim 1.

According to another aspect of the invention, there Is provided a method of separating contaminants from surface water as specified in Claim 22.

Brief Description of the Drawings

In the drawings, which Illustrate a prcterrcd embodiment of a separator according to the invention, and are for exemplary purposes: Fgurc I Is a cross-sectional elevation of a separator according to one embodiment of the mvcnton; Figure 2 Is a plan view of the separator Illustrated In Figure 1; Figure 2a IS an exploded view of the lower part of the filter housing of the separator Illustrated In Figures I and 2; Figure 3 Is a cross-scctonal elevation of a separator according to a second embodiment of the invention; l figure 4 is a plan view of the separator t11ustrated in Figure 3; Figure 4a Is an exploded vow of the lower part of the filter housing of the separator 1lustratcd In ltgurcs 3 and 4; leisure 5 Is a schematic represcntanon of the Inside of a separator according to one aspect of the invention; and Figure 6 llusuratcs the means of fixing an once pipe In a filter housing.

Detailed Description of the Preferred Embodiments

Refcrrng now to Fgurcs 1, 2 and 2a, a separator 1 Is comprised of a tank 2, cylindrical In cross- secuon, having a domed base 3, and a I'd 4. 'lthe hd 4 mounts a filter housing 5 In which Is mounted a filter unit 6. The filter unit 6 Includes a pipe 7, a lower region 8 of which Is perforated, a sleeve 9 of kilter material, and a collar 10. The upper end 12 of the pipe 7 is fixed to a collar 22, which IS removably attachable to the neck 23 of the filter housing 5. The lower end 11 of the pipe 7 Is held in the filter housing by a collar 24 fixed to the outside of the pipe 7 by an adhesive, which Includes a seal 25, made of neoprene in the example. The end of the pipe 11 sits In a pipe coupling 26. 1'hc lower end I I of the plpC opens Into the main body of the tank 2. A lifting handle comprtscs a bolt 13 extending across the pipe 7. 'lithe bolt 13 Is held In place by a nut 14. Also mounted In the lid 4 Is a probe holster 2(), the purpose of which IS to allow a probe to be Inserted into the inside of the tank to sample the tank contents.

I'he filter housing 5 Is substantially square in cross-secton and Nudes weirs 15 In opposing faces of the housmg 5, each set at 9() degrees to the direction of flow of water in a surge condition.

A substantially cylindrical primary chamber 16 fits over the filter housing 5 and onto the upper surface of the lid 4. The primary chamber 16 mounts two pipes, an inlet pipe 17, and an outlet pipe 18. Located to the lid 4 within the Decimeter of the primary chamber 16 is a skim hole 19. The primary chamber 16 is provided with a manhole cover for access to the kilter unit 6 and the mode of the tank 2.

I'hc passage of water through the separator Is descrtbcd below: Surface water enters the separator over through pipe 17. In normal flow condluons Incoming water enters the tank 2 through skim hole 19. Silt and hydrocarbon products tend to separate out of suspension with the water, to leave a silt fraction at the base 3 of the tank 2 and a hydrocarbon layer on the top of the water. 1ALS the level of water In the tank 2 rises liquid in the form of hydrocarbon and water enters the lower end I I of tube 7. 'lihe static head of Squid tends to push the said liquid (water and hydrocarbon) through the kilter material 9. The kilter material 9 Is a coalescent filter, hydrocarbon material kid and grease) coalescing thereon. (:lean water passes through the outlet pipe 18.

In storm conditions, water enters the separator by passing through the Inlet pipe 17. In storm conditions, the 1ncommg volume of water IS such that the skim hole 19 chokes, resmcting Ingress of water to the tank 2. Instead, water passes over the welts 15, hlltog the filter housing 5 until the liquid Icvcl reaches the base of the outlet pipe 18. The hllng of the kilter housing occurs very quickly and the flow of water, in storm conditions, is In effect through the mlct pipe 17, into the primary chamber and straight over the weirs 15 and out via outlet pipe 18.

The pipe 7 provides for easy access to the lower part of the tank 2 with a suction hose for the removal of silt, and other contents of the tank. By containing the filter urut 6 In a filter housing the filter is protected from the contents of the tank 2, and in particular from silt.

Referring now to Figures 3, 4 and 4a, a separator 31 is comprised of a tank 32, cylindrical in cross- secton, having a base 33, and a Ed 34. The Ed 34 mounts a kilter housing 35 in which is mounted a filter unit 36. The filter unit 36 includes a pipe 37, a lower region 38 of which IS perforated, and a sleeve 39 of filter matenal. The upper end 42 of the pipe 37 IS heed to a collar 53, which is removably attachable to the neck 54 of the kilter housing 35. The lower end 41 of the pipe 37 is held m the filter housing by a collar 55 fiend to the outside of the pipe 37 by an adhcsvc, which includes a seal 56, made of neoprene in the example. The end of the pipe 41 sits In a pipe coupling 56. The lower end 41 of the pipe 37 opens Into the main body of the tank 32. A lifting handle composes a bolt 43 extending across the pipe 37. The bolt 43 IS held in place by a nut 44. Also mounted m the lid 34 IS a probe holster 50, the purpose of which IS to allow a probe to be inserted mto the msldc of the tank to sample the tank contents.

The filter housing 35 Is substantially round in cross-secton.

A substantially cylindrical primary chamber 46 fits over the filter housing 35 and onto the upper surface of the lid 33. 1'hc primary chamber 46 mounts two pipes, an inlet pipe 47, and an outlet pipe 48. Located in the lid 34 wthm the perimeter of the primary chamber 46 IS a skim hole 39. The primary chamber 4G Is provided with a manhole cover for access to the filter umt 36 and the Inside of the tank 32.

The passage of water through the separator is described below: Surface water enters the separator through the Inlet pipe 37. In normal flow conditions incoming water enters the tank 32 through skim hole 49. Silt and hydrocarbon products tend to separate out of suspcuslosl with the water, to Icavc a silt fraction at the base of the tank 32 and a hydrocarbon layer on the top of the water. As the level of water In the tank 32 rises liquid In the form of hydrocarbon and water enters the lower end 41 of inlet pipe 37. The static head of Squid tends to push the said liquid (water and hydrocarbon) through the filter material 39. 'lthe filter material 39 Is a coalescent filter, hydrocarbon material (oil and grcasc) coalescing thereon. Clean water passes through the filter and fills the space between the tube 37 and the filter housing 35, exiting via a pipe 51 and subsequently through the outlet ptpe 48 to an outfall to a surface water mate.

In storm conditions, water enters the separator by passing through the inlet ptpe 47. In storm conditions, the tncotntng volume of water Is such that the skim hole 49 chokes, restucnng Ingress of water to the tank 32. Instead, water entering via the mlet pipe 47 builds up and overflows the Internal weir 52 and exits through the outlet pipe 48.

The ptpe 37 provides for easy access to the lower part of the tank 42 with a suction hose for the removal of silt, and other contents of the tank. By containing the filter unit 36 In a filter housmK 35 the filter Is protected from the contents of the tank 32, and in particular from silt.

Figure 5 Illusurates an alternative embodiment of filter housing 6() In which weirs 61 are provided with filter screens 62, which In the example are formed from a metallic mesh material. The filter housing 60 Is otherwise similar to the filter housing Illustrated in Figures 1 and 2 with the lower end of the ptpe 63 locating in a coupling 65 of similar design to the coupling 26 Illustrated In Figures I and 2 and situated In the base of the filter housing 60. The ptpe 63 is surrounded by a sleeve 64 of filter material, the section of ptpe 63 covered by the sleeve being perforated. 'lihe filter housing 60 terminates at Its upper end in a neck 68 through which the ptpe 63 passes. A rim 69 extends radially outward from the neck 6X. 1Y closure member 66 Is attached to the ptpe 63 and cooperates with the neck 68 and rim 69 to secure the ptpe 63 In place In the filter housing 60.

Referring now to Figure 6, the pipe 63 Is fixed to an Inner pornon 74 of lid 66 by means of a collar 75. In the example, the Itd 66 Is formed of a plastics matenal, by mouldtng or vacuum forming. The Itd 66 includes an edge formation induding a wall 71 having an outer rim 70. Radially inward of the wall 71 is a paragon 72 which together with a side wall 77 parallel to the wall 71 and a top ring 78 forms a chatnber 73 In watch a seal 76 Is located. In the example, the seal IS an "O" ring. The chamber 73 extends around the circumference of the Itd 66 and In use locates on the neck 68 of the filter housing 60. The neck G8 passes between the inside of the wall 71 and the O ring 76 to seal the lid 66 onto the filter housing 60. The pipe 63 Is properly located m the filter housing 6() when the lower end of the pipe is secured In the coupling 65 and the neck 68 Is engaged with the O ring 76, and the neck 68 can only engage with the O ring 76 if the pipe 63 Is secured In the coupling 65.

The same type of lid as described with reference to Figures 5 and 6 may be used In conjunction with the filter housings Illustrated in Figures 1 to 4. The manner m which the Ed 66 locates on the neck 68 of filter housing 6() provides a fitter or member of a maintenance crew with an easy tndcanon of whether the pipe 66 Is correctly located In the filter housing 60. The fitter simply aligns the inside of the wall 71 with the neck G8, lowers the Ed G6 onto the neck and pushes downward until the seal 76 engages with the neck 68.

In the illustrated examples the tank Is manufactured from a plastics material, as Is the primary chamber. l lowever, an equally useful separator can be made using a tank of different fabucatton, for example the tank may be made from concrete, with a separator according to the invention being supplied to fit such a tank.

lthe separator of the Invention is particularly advantageous for a number of reasons. The filter unit Is mounted in the upper section of the tank, thereby keeping the filter unit away from silt accumulating In the lower section of the tank. The filter unit includes a pipe through which a tool such as a suction hose may be passed to empty the contents of the tank. In separators of the prior art it Is difficult to clean beyond the filter box. The filter Is protected from the tank environment by a housing. Liquid passes from the inside of the filter to the outside thereof, as opposed to outside to Inside as Is the case for separators of the prior art. The mounting of the pipe In the housing lid facilitates easy assembly, removal and re-fitting of the pipe in the filter housing. Similarly, the provision of a coupling at the base of the filter housing allows the pipe to be located easily m it correct position in the filter housing. 'lithe provision of internal weirs m the filter housing allows for cost effectvc manufacture and assembly of the separator, and screening the weirs prevents debris entrained with storm water from entering the separator.

Claims

Clanns 1. A separator for mounting on a tank having upper and lower

sections comprises an Inlet to the tank, a filter unit having a filter inlet and a filter outlet, m use the filter unit being mounted In the upper section of the tank.
2. A separator according to claim 1, the filter unit composing a housing and a pipe mounted In the housing such that one end of the pipe extends beyond a base of the housing, and in use, Into the tank, the said one end of the pipe being open to the tank.
3. A separator according to claim 2, wherein the filter housing includes a cap and the pipe is mounted in the cap.
4. A separator according to claim 3, wherein the cap is removably mountable on the housing.
5. A separator according to claim 4, wherein the cap Nudes a seal, the seal engaging with the housing to locate the pipe In said housing when the cap is mounted on the housing.
G. A separator according to any of claims 2 to 5, wherein a coupling Is mounted in a lower end of the housing, and one end of the pipe is supported by the coupling when the cap Is mounted on the housing.
7. A separator according to any of claims I to 6, wherein a portion of the pipe located in the housing Includes at least one opening In a wall of the said pipe.
8. A separator according to any of Maims 1 to 7, wherein the filter indudes a filter matenal.
9. A separator according to claim 8, wherein the filter material Is in the form of a sleeve located on the outside of the said pipe covenug the said at least one opening.
10. A separator according to any of claims 2 to 9, wherein the filter inlet Is comprised of the open end of the pipe located, in use, in the tank.
I I. A separator according to any of claims 2 to 10, wherein the filter housing tndudes the kilter outlet.
12. A separator according to claim I I, wherein the filter outlet comprises at least one weir.
13. A separator according to claim 11, wherein the filter outlet comprises two weirs.
14. A separator according to Claim 13, wherein at least one of the two weirs Is an integral part of the filter unit.
15. A separator according to any of Claims 12 to 14, wherein at least one weir is provided with a perforated screen.
16. A separator according to claim I I, wherein the filter outlet comprises a pipe.
17. A separator according to any preceding claim, wherein the tank inlet consists of an opemng.
18. A separator according to claim 17, wherein the size of the opening is such that under normal flow conditions any liquid entering the separator passes through the tank Inlet, and In storm conditions the tank Inlet Is choked.
19. A separator according to any preceding claim, wherein the separator includes an Inlet and an outlet, each mounted above the level of the filter element.
20. A separator according to any preceding claims dependent on Claim 14, wherem water entering the separator in storm conditions by-passes the tank and filter, exiting via the outlet.
21. separator according to any preceding claim, further comprising a tank.
22. A method of separating contaminants from surface water comprising the steps of: a) directing surface water to an Inlet of a separator as claimed In claim 21; b) collecting contaminants in the said separator; and c) directing cleaned water to a sewage outfall.