GB2356466A

GB2356466A - Flow control device

Info

Publication number: GB2356466A
Application number: GB0020770A
Authority: GB
Inventors: Dennis Reginald Dring
Original assignee: Yorkshire Water Services Ltd
Current assignee: Yorkshire Water Services Ltd
Priority date: 1999-11-16
Filing date: 2000-08-24
Publication date: 2001-05-23
Anticipated expiration: 2020-08-24
Also published as: GB2356466B; GB0020770D0; GB9926962D0

Abstract

A flow control device for regulating discharge at a CSO is described. The device includes a plate 44 operable to be located upstream of a CSO control inlet 26 through which fluid flow is to be regulated. The height of the plate is such as to be above the fluid level B to allow plate unregulated fluid flow beneath the plate and to the control inlet up to a predetermined fluid head but is at least partially below the fluid level C to regulate fluid flow to the control inlet when the fluid is above a predetermined fluid head. The plate is disposed at a downstream and upward angle with respect to any incoming fluid surface so as to cause fluid shear D in the reverse direction to the fluid flow when the fluid is above the predetermined fluid head. A method of controlling fluid flow through an control inlet is also defined.

Description

2356466 A FLOW CONTROL DEVICE The present invention relates to a flow

control device, in particular, but not exclusively, to a hydraulic flow control device to control f low of sewage at a combined storm overflow (CSO).

The discharge of sewage through a CSO is generally critical to the sewerage system and the sewage treatment process. The CSO itself generally has a defined control inlet. The geometry and the size of the control inlet will regulate the flow through the CSO. However, if the head of water upstream of the CSO exceeds the depth of the inlet, the flow through the inlet will also be determined by the head of water upstream of the CSO. Once the depth of the control inlet has been significantly exceeded, it is no longer possible to regulate the flow rate through the CSO. This may lead to sewage flow rates which exceed the regulatory maximum levels.

According to a first aspect of the present invention there is provided a flow control device for regulating discharge at a CSO comprising a plate operable to be located upstream of a control inlet through which fluid flow is to be regulated, the height of the plate being such as to be above the fluid level to allow plate unregulated fluid flow beneath the plate and to the said control inlet up to a predetermined fluid head, and to be at least partially below the fluid level to regulate fluid flow to the control inlet when the fluid is above a predetermined fluid head, the plate being disposed at a downstream and upward angle with respect to any incoming fluid surface so as to cause fluid shear in the reverse direction to the fluid flow when the fluid is above the predetermined fluid head.

Advantageously, the fluid shear effected by the plate effectively reduces the water pressure at the control inlet, thus reducing flow through the control inlet. The f low at the control inlet is determined by the head of f luid upstream of the control inlet, a low head gives a low flow and a high head gives a high f low. Up to a certain head, the rate of flow will be acceptable and will not require further regulation but once the head reaches a certain level, the pressure at the control inlet may cause the flow to exceed acceptable levels. The shear plate acts to direct flow upstream and thus reduce the effective 1S flow at the control inlet. Thus, the adjustment of the shear plate and the effective control over the control inlet that this gives regulates. the velocity of the flow within certain limits and effectively gives steady downstream flow conditions for variable head of fluid upstream.

Preferably, the angle of the plate with respect to the plate downstream surface of the fluid is between 10-800, more preferably, 40-800, most preferably, 50-700.

By angling the shear plate, the reverse shear may be regulated and it has been found especially advantageous to angle the shear plate between 550 and 650 with respect to the downstream surface of the fluid, a particularly preferred angle is 60.

Preferably, the device includes a backplate operable to be located above the fluid control inlet.

Preferably, the shear plate is suspended from the backplate. Preferably, the backplate extends upwardly from the control inlet and, preferably, the lowermost edge of the backplate def ines the upper edge of the control inlet. Preferably, the backplate extends upwardly from the control inlet in a substantially vertical manner and is, preferably, secured in such a position.

Preferably, suitable suspending means are employed to suspend the shear plate from the backplate.

Preferably, the shear plate has a support plate. Typically, the support plate is secured to part of a surrounding fixed structure. Preferably, the shear plate and support plate are located, at least partially, one over the other, preferably, extending at substantially the same angle with respect to the horizontal plane. Preferably, the shear plate extension is adjustable.

Typically, the support plate extends at a fixed angle and the shear plate is secured thereto. The shear plate length is, typically, adjustable so that variable overlap with respect to the support plate is possible and so that the extension of the shear plate and, consequently, the position of the shear plate lower edge with respect to the fluid level, may be varied to suit particular control inlet flow requirements. Typically, the length of the shear plate is adjustable within a range of + 30% of its mid-range length.

one possible adjustable securing mechanism for the two plates is to provide a longitudinally extending slot in the shear plate and to bolt the shear plate to the support plate via the slot so that by loosening the bolt the position of the shear plate may be varied by moving the slot with respect to the bolt, the length of the slot may thus define the upper and lower extent of adjustment 5 possible.

Typically, the shear plate is located at least partially over the top of the support plate as viewed from upstream of the plates.

In use, the support plate may act as an upper extension to the shear plate to also provide reverse shear to the incoming flow. Accordingly, typically, the support plate extends upwardly as far as the backplate. Preferably, the upper edge of the support plate is secured to the backplate by suitable means, preferably, by welding. The shear plate may or may not extend upwardly as far as the backplate depending on its manner of securement above the control inlet and whether it is adjustable or not. if non-adjustable, it may itself be secured at its upper edge to the backplate.

Preferably, the shear and/or support plate comprises a lower edge, an upper edge and two side edges. Preferably, the said plate is square or rectangular, more preferably, rectangular. Preferably, the width of the shear plate is substantially equivalent to that of the control inlet.

Preferably, the device includes side plates and, preferably, a base plate.

Typically, the backplate is rectangular and typically of substantially the same width as the shear plate. The support plate is, preferably, square or rectangular and, typically, of the same width as the shear plate. Spaced parallel side plates may extend upstream from the sides edges of the backplate, beyond the shear and support plate and the shear and support plate may be further secured to the side plates. A base plate may also extend upstream from the base of the control inlet, the base plate may be secured at its lateral edges to the bottom edges of the side plates which may extend downwards to the level of the bottom edge of the control inlet.

The backplate, side plates and/or base plate may be secured to the surrounding structure by suitable means, in some embodiments, lugs extend outwardly from the outside surface of one or more of the respective plates. These lugs may embed in the surrounding structure. The lugs may be of a suitable design such as for embedding in concrete, earth or other surrounding structure or excavation.

In a preferred embodiment, the flow control device comprises a box having two open sides corresponding to the incoming flow side and the top side. Two co-extensive opposed parallel side plates, a co-extensive base plate between the side plates so that the two side plates and 2S the base plate form a channel through which fluid is to flow, a backplate also between the side plates and extending from the height of the upper edges of the parallel side plates to the upper edge of the control inlet which edge is, typically, defined by the backplate lower edge.

The base plate is located on the bed of a channel through which flow is to be controlled with the open side upstream and the open top uppermost.

Advantageously, the flow control device may be used as a sewage flow control device, preferably, at a CSO. Sewage flow control is essential to the sewage treatment industry as incoming fluid into the works needs to be controlled so as not to exceed a level whereby complete treatment may not be effected. The device of the invention allows the fluid flow into a treatment works to rise and fall within acceptable ranges but when incoming fluid exceeds a certain head so that flow through the control inlet would ordinarily exceed acceptable levels, the shear plate provides reverse shear to reduce the effect of the fluid head and consequently reduce flow through the control inlet.

Accordingly, the invention extends to a method of controlling fluid flow through an control inlet and, more preferably, to a method of controlling sewage flow, preferably through a CSO, comprising locating a device according to the first aspect of the invention at a fluid flow control inlet to control flow therethrough. The methods may comprise the step of adjusting the length or extension of the plate to regulate flow through the control inlet. The methods may also comprise the step of adjusting the angle of the said plate to regulate flow through the control inlet.

Preferably, the control inlet is substantially the same width as the shear plate. The area beneath the shear plate and through which the flow is regulated may be defined as the flow regulation area. Preferably, the flow regulation area is substantially the same width as the shear plate and, preferably, has four sides defined by the three sided channel and the lower edge of the shear plate.

Preferably, the flow regulation area height/width value as adjusted by the shear plate is between 0.7 and 1.2, more preferably 0.6-1.2, most preferably, approximately 0.850.95.

Preferably, the flow regulation area is defined by a rectangular opening. Preferably, the flow regulation area is an effective distance upstream of the control inlet. Preferably, the control inlet is formed in the body, preferably, the backplate of the flow control device, preferably, at the base of the backplate thereof.

optionally, the flow control device may not include a separate control inlet and the effective control inlet may be defined by the flow regulation area. Preferably, the width of the flow regulation area and the control inlet is substantially the same. Preferably, the height of the control inlet is greater than or equal to the height of the flow regulation area. Preferably, the control inlet/flow regulation area height ratio is no greater than 1.2, most preferably, no greater than 1.1. The control inlet is, preferably, of a square section.

Preferably, the flow control device includes channel forming means extending upstream of the control inlet and shear plate so that the water approaching the shear plate has flow characteristics determined by the channel. Preferably, the channel is substantially the same width as the shear plate. Preferably, the channel is formed by the base plate and side plates of the device.

Preferably, the ratio of the channel width:length is at least 1:2, more preferably, at least 1:2.5, most preferably, at least 1:2.6. Preferably, the said ratio is between 1:2 and 1:3.2, more preferably, between 1:2.4 and 1:2.8, most preferably between 1:2.5 and 1:2.7.

Especially preferred is a ratio of 1:2.6. Preferably, the sides of the channel extend upwardly. Preferably, the ratio of the upward extent of the channel to the width is at least 2:1, more preferably, at least 3:1, most preferably, at least 3.5:1. An especially preferred ratio is 3.75:1. Preferably, the range of the ratio of the height:width of the channel is between 2.0:1.0 and 5.5:1.0, more preferably between 3.0:1.0 and 4.5:1.0, most preferably between 3.5:1.0 and 4.0:1.0.

Preferably, the channel has lateral shoulders on either 20 side thereof. Preferably, shoulders extend laterally from the side plates, preferably level with the upstream leading edge of the base and side plates at the upstream limit of the channel. Typically, the shoulders extend upwardly as far as the uppermost rim of the back plate for channel fluid dynamics for water levels below such a level. The shoulders may be made from concrete or other suitable material and may themselves define the channel or act as the substrate for the side plates of the device.

An embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings in which:Figure la is a side cross-section through a flow control device according to the present invention; Figure lb is a plan cross section through line AA of figure 1a; and Figure 1c is a front cross section through line CC of figure 1b.

Referring to figures la-c, a discharge regulating CSO device 2 comprises a rectangular base plate 4, two spaced parallel co-extensive rectangular side plates 6, 8 extending upwardly from the side edges 10, 12 of the base plate 4 and co-extensive therewith. A backplate 14 extends between the rearmost edges 16, 18 of the side plates 6,8 and extends from the height of the upper edges 20, 22 of the side plates 6, 8 downwards, to terminate by forming the upper edge 24 of the control inlet 26. The control inlet 26 defines a rectangular hole formed by the gap between the lower edge 24 of the backplate 14 and the rear edge 27 of the base plate 4. The sides of the control inlet hole 26 are -defined by the lower edges of the side plates 6, 8. In this manner, the main housing of the device comprises a rectangular box having a gap at the bottom of the back plate to provide the control inlet, an open top and an open front side opposite the back plate to allow the inflow of fluid through the device to the control inlet 26. Two longitudinally spaced butterfly lugs 28, 30 for concrete securement depend downwardly from the underside of the base plate 4 located centrally with respect to the side edges 10, 12 thereof and approximately one third of the length of the base plate from the front and rear edge respectively. Similarly, located toward the rear of the side plate, two longitudinally spaced concrete securing lugs 32, 34 and 36, 38 extend outwardly from the outside surface of the side plates 6, 8 respectively. Similar matching sets of longitudinally spaced outwardly extending lugs 40, 42 are also located toward the front of the side plates 6, 8 respectively. Each lug is located directly above or below its corresponding lug in the set on the side plate and each lug of each set of two is located at the same height as the corresponding lug on the corresponding set of two lugs on the same side.

An extendable shear plate 44 is slidably mounted on a fixed support plate 46 which support plate depends downwardly and forwardly from the backplate 14 and is welded thereto along its upper edge 48 at a level approximately midway down the length of the backplate 14.

The fixed plate 46 and the slidably mounted shear plate 44 co-extend between the side plates 6, 8. The support plate 46 is fillet welded on its under side to the side walls 6, 8 as well as to the backplate. However, for strength, the support plate 46 is fillet welded on both sides to the backplate 14. A stainless steel mounting tube 50 extends upwardly and forwardly from the backp late 14 at a point just above the lower edge 24 thereof so that the front edge 52 of the mounting tube abuts against the underside of the support plate 46 to which it is fillet welded. The mounting tube is also fillet welded to the backplate 14 at the other end thereof. The mounting tube is internally threaded for receiving bolt 54 through the front edge 52 thereof. The shear plate 44 is slidably mounted on the fixed plate 46 as has been previously mentioned. The shear plate 44 has located therein a pair of spaced coextensive longitudinal slots 56, 58. The length of the slots defines the range of adjustment of the shear plate 44. Each slot 56, 58 has a bolt S4, 60 respectively passing therethrough with a location washer 62, 64 between the bolt head and the surface of the shear plate 44. Each bolt passes through its respective slot into the internal thread of a mounting tube such as 50. The second mounting tube which accommodates bolt 60 is not shown in figure lb but corresponds to the mounting tube 50 shown in figure la. By the use of slots such as 56, 58 the securing bolts 54, 60 may be loosened and the shear plate 44 may be extended or retracted by sliding downwardly or upwardly with respect to the support plate 46. Once the predetermined extension of the shear plate is achieved, the bolts may be tightened to fix the shear plate in the required position. In f igure la, the lower edge of the support plate 46 is at the same height as the upper edge of the control inlet 26 and the shear plate 44 may be retracted so that its lower edge is at the same height as the lower edge of the support. plate 46. However, the shear plate 44 may be adjusted to overlap the support plate downwardly therefrom at the same angle by loosening the bolts 54, 60 and sliding the shear plate down the support plate 46 until the lower edge 66 of the shear plate 44 is located at the required height for control inlet flow regulation.

In use, sewage flow is in the direction of arrow A towards the control inlet 26. When the sewage fluid level is at level B, the fluid flow is self regulating through control inlet 26 but when the fluid reaches the level of head C, the head of fluid is too great causing a resultant flow through the control inlet 26 which is unacceptably high. By lowering the shear plate 44 to the level below head C as shown in figure la, a resultant reverse shear D is set up causing the control inlet flow through control inlet 26 to be lowered. Advantageously, by use of the invention, it is possible to substantially fix the control inlet flow rate for varying heads of incoming fluid. This creates the advantage of a constant flow rate for sewage treatment S or other treatment process despite varying heads of incoming f luid. The reverse shear set up by the shear plate 44 may be varied by varying the depth of the shear plate below the surface of the head of fluid. For a given required control inlet flow and for given dimensions of the shear plate 44 it is possible to regulate the control inlet flow through the control inlet 26 for a given depth of head. Regulation takes place by varying the depth and/or area of the shear plate below the head of incoming fluid.

Although sewage treatment has been specifically mentioned herein, other applications for the invention are envisaged where control inlet flow needs to be regulated for varying heads of inlet fluid. For instance, potable water treatment and chemical treatment.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1 A flow control device for regulating discharge at a CSO comprising a plate operable to be located upstream of a control inlet through which f luid f low is to be regulated, the height of the plate being such as to be above the fluid level to allow plate unregulated fluid flow beneath the plate and to the control inlet up to a predetermined fluid head, and to be at least partially below the fluid level to regulate fluid flow to the control inlet when the fluid is above a predetermined f luid head, the plate being disposed at a downstream and upward angle with respect to any incoming fluid surface so as to cause fluid shear in the reverse direction to the fluid flow when the fluid is above the predetermined fluid head.

2.A flow control device according to claim 1, wherein the angle of the plate is fixed.

3.A flow control device according to claim 1 or 2, wherein the angle of the plate with respect to the plate downstream surface of the fluid is between 10-800.

4. A flow control device according to claim 1, 2 or 3, wherein the angle of the shear plate is between 5S' and G50 with respect to the downstream surface of the fluid.

5. A flow control device according to any preceding claim, wherein the height of the plate is adjustable.

6. A flow control device according to any preceding claim, wherein the height of the plate is fixedly locatable at a predetermined height.

7. A flow control device according to any preceding claim, wherein the device includes a backplate operable to be located above the fluid control inlet.

8. A flow control device according to any preceding claim, wherein the shear plate is suspended from the backplate.

9. A f low control device according to claim 7 or 8, wherein the backplate extends upwardly from the control inlet.

10. A flow control device according to any of claims 7-9, wherein the lowermost edge of the backplate defines the upper edge of the control inlet.

11. A flow control device according to any preceding claim, wherein suitable suspending means are employed to suspend the shear plate in position.

12. A flow control device according to any preceding claim, wherein the shear plate has a support plate.

13. A flow control device according to claim 12, wherein the support plate is secured to part of a surrounding fixed structure.

14. A flow control device according to claim 12 or 13, wherein the shear plate and support plate are located, at least partially, one over the other.

15. A flow control device according to any preceding claim, wherein the shear plate extension is adjustable.

16. A flow control device according to any of claims 12 15, wherein the adjustable mechanism for the two plates is provided by at least one longitudinally extending slot in the shear plate or the support plate and the securement of the shear plate to the support plate via the slot using loosenable securing means so that by loosening the securing means the position of the shear is plate may be varied by moving the slot with respect to the securing means.

17. A flow control device according to any preceding claim, wherein the area below the shear plate lower edge and above the base of the flow channel is def ined as the flow regulation area.

18. A flow control device according to claim 17, wherein the width of the channel is substantially equivalent to the shear plate width.

19. A flow control device according to any preceding claim, wherein the flow control device comprises a box having two open sides corresponding to the incoming flow side and the top side respectively.

20. A flow control device according to any preceding claim, wherein the flow control device is operable to be used as a sewage flow control device.

21. A flow control device according to any preceding claim, wherein, the sewage flow control device is operable to regulate the flow of fluid through a CSO.

22. A flow control device according to any preceding claim wherein the control inlet is defined by the body of the flow control device.

23. A flow control device according to any preceding claim wherein the control inlet is the same width as the shear plate.

24. A flow control device according to any preceding claim wherein the flow regulation area height/width value is between 0.7 and 1.2.

25. A flow control device according to any preceding claim, wherein the flow control device includes channel forming means extending upstream of the control inlet and shear plate.

26. A flow control device according to claim 25, wherein the channel is substantially the same width as the shear plate.

27. A flow control device according to claim 25 or 26, wherein the ratio of the channel width:length isat least 1:2.

28. A flow control device according to any of claims 25 27, wherein the sides of the channel extend upwardly and the ratio of the upward extent to the width of the channel is at least 3:1.

29. A flow control device according to any of claims 25 28, wherein the channel has lateral shoulders, which may define the channel, on either side thereof and which extend laterally, vertically and downstream as far as the control inlet to present a predetermined fluid barrier on either side of the upstream end of the channel.

30. A method of controlling fluid flow through an control inlet comprising the steps of:

locating a flow control device according to any of claims 1-29 at the control inlet; and allowing the shear plate to come into contact with an incoming stream of fluid prior to the fluid reaching the control inlet to thereby control flow through the control inlet.

31. A method of controlling sewage flow through an control inlet comprising the steps of:

locating a flow control device according to any of claims 1-29 at the control inlet; and allowing the shear plate to come into contact with an incoming stream of sewage prior to the sewage reaching the control inlet to thereby control flow through the control inlet.

32. A method of controlling fluid flow through a CSO comprising the steps of:

locating a flow control device according to any of claims 1-29 at the control inlet; and allowing the shear plate to come into contact with an incoming stream of fluid prior to the fluid reaching the control inlet to thereby control flow through the control inlet

33. A method according to any of claims 30-32, which includes the step of adjusting the length or extension of the plate to f ixedly locate it at a required height and thereby regulate flow through the control inlet.

34. A flow control device as hereinbefore described with reference to the drawings.

35. A method of regulating fluid flow through an control inlet as hereinbefore described with reference to the drawings.