WO1989008751A1

WO1989008751A1 - Liquid control apparatus

Info

Publication number: WO1989008751A1
Application number: PCT/GB1989/000265
Authority: WO
Inventors: William Anthony Carr
Original assignee: Conder Group Plc
Priority date: 1988-03-15
Filing date: 1989-03-15
Publication date: 1989-09-21
Also published as: AU3416789A; GB2231596A; GB2231596B; GB9012033D0; GB8806093D0

Abstract

A water retention and flow control tank is divided into a head development chamber (2) and a much larger retention chamber (3) by a baffle-weir (4) which provides an overflow from the head development chamber (2) to the retention chamber (3). The head development chamber (2) has an outlet (7) associated with a vortex flow controller (8), and there are non-return flap valves (10) which allow the retention chamber (3) to drain back into the head development chamber (2) whilst preventing substantial flow from the head development chamber (2) to the retention chamber (3). When there is e.g. heavy rainfall, the water level builds up very quickly in the head development chamber (2) and the vortex flow controller (8) rapidly reaches its operating head, ensuring that the water discharge from the tank is at a predetermined maximum flow rate for the maximum period of time.

Description

Liquid Control Apparatus

Background of the Invention

The present invention relates to liquid control apparatus, comprising a head development chamber, an inlet directing inlet flow into the head development chamber, an outlet from the head development chamber, a second chamber of a capacity substantially greater than that of the head development chamber, and an overflow which passes overflow to the second chamber when the head development chamber is full.

It is desirable to provide liquid retention and flow control, principally for a drainage system that, has to cope with storm water, but also for other systems such as a sewage balancing system. Increased demand on new and existing drainage systems due to further development, peak discharge of sewage, or the influx of stormwater, can result in intermittent overloading. In such circumstances, it is known to use a retention tank (also called an attenuation tank or balancing tank), but the discharge is directly proportional to the head in the tank, and therefore the maximum discharge rate is only achieved briefly when the tank is full. DE-A-3 022 997 and DE-A-3 022 998 describe liquid control apparatus which is also illustrated in a brochure entitled "Automatisch wirkende Wehrsys terae" . The apparatus is for discharging storm water so that it does not burden the sewerage system, and instead of a simple overflow, a float with a raisable barrier is used so that the liquid discharged is taken from the middle zone of the channel. In order to do this, there is a type of head development chamber with a weir and a raisable baffle above, which discharges into a second chamber which is of a capacity substantially greater than that of the head development chamber. However, the second chamber merely acts to collect the excess water, which is apparently immediately discharged and by-passes the remainder of the system.

The Invention

According to the present invention, the second chamber is a retention chamber in which excess liquid is retained. Furthermore, there is a low level interconnection between the retention chamber and the head development chamber for allowing the retention chamber to drain into the head development chamber, the low level interconnection having means preventing gross flow through the low level interconnection from the head development chamber to the retention chamber. The apparatus will be incorporated in a drainage system in which the maximum design rate of flow through the inlet to the apparatus is substantially greater than the rate of flow through the outlet when the head development chamber is full. If there is a surge, the head development chamber creates the required head before the retention chamber is filled. The maximum designed discharge rate is therefore maintained from an early stage, i.e. the discharge is at a predetermined maximum flow rate for the maximum period of time; as a result, the required retention capacity is significantly reduced, ie the retention chamber can be made significantly smaller.

The capacity of the head development chamber is preferably as small as practicable, e.g. for installation and inspection. Depending on the expected excess flow into the apparatus, the retention chamber could be quite small, but in other applications, the retention chamber could be very large - for instance, the size of the retention chamber could very from say 20000 litres to 240000 litres. In practice, the retention chamber can have a capacity of more than about twice or preferably more than about three or four times that of the development chamber.

The outlet from the head development chamber will incorporate a flow controller of some type, e.g. a submerged orifice or a vortex flow controller; a suitable vortex flow controller is described in GB-A-2 141 561. Most flow controllers are dependent on head. An advantage of the invention is that the required head is reached very quickly.

The drainage system will incorporate some means effectively resisting the flow through a drainage duct leading from the head development chamber, whether it is in the actual outlet or not. A restriction in flow either at the outlet or in the downstream drainage could act as such means - if in the downstream drainage, the outlet pipe would surcharge and back-up into the head development chamber and create the working head.

If the flow restricting means is downstream of the head development chamber, the low level communication with the valve means can communicate with the drainage duct between the head development chamber and the flow restricting means, and the invention extends to a drainage system with such an arrangement.

The means in the interconnection can be of any suitable type, and complete liquid-tightness is not required. In practice, it is desirable to prevent substantial flow through the low level interconnection into the retention chamber and a non-return flap valve is suitable as such means, for this purpose. However, at least in theory. all that is necessary is that the rise in level in the retention chamber should not be as fast as the rise in the head development chamber, and for instance a vortex flow controller could be used as said means, or any means which permits a faster flow out of the retention chamber than into it.

For convenience of design, the overflow will normally lead directly out of the head development chamber to the retention chamber, but this is not necessarily so. For instance, an inlet duct to the head development chamber could incorporate a weir immediately upstream of the head development chamber, to pass overflow to the retention chamber without it passing through the head development chamber.

The Drawings

The invention will be further described, by way of example, with reference to the accompanying drawings, in which:-

Figures 1, 2 and 3 are a top view, a longitudinal section along the line II-II in Figures 1 and 3, and a vertical section along the line III-III in Figures 1 and 2, of a first embodiment of the invention;

Figures 4-6 correspond to Figures 1-3, but are of a second embodiment of the invention; Figures 7-9 correspond to Figures 1-3, but are of a third embodiment of the invention;

Figures 10 and 11 correspond to Figures 1 and 2, but are of a fourth embodiment of the invention.

Figures 1 to 3

The liquid retention apparatus of Figures 1 to 3 has a single tank 1 which is divided into an inlet or head development chamber 2 and a retention chamber 3 by a baffle-weir 4 which provides an overflow from the head development chamber 2 to the retention chamber 3. The capacity of the retention chamber 3 is about four or four and a half times that of the head development chamber 2. One suitable apparatus has a tank diameter of about 2.5 metres, the overall tank length being about 7.56 metres, though the size depends upon the flow and retention requirements.

There is a high level inlet 5 which directs water flow into the head development chamber 2, associated with an inlet flow deflector 6. There is an outlet 7 from the head development chamber 2, the outlet 7 incorporating a flow controller 8. Flow controllers such as vortex flow controllers are designed to a specific head - it is preferred that this specific head be the top of the tank 1, i.e. designed to the maximum head that could be in the tank. There is a low level interconnection 9 between the retention chamber 3 and the head development chamber 2 for allowing the retention chamber 3 to drain into the head development chamber 2, the interconnection 9 having valve means in the form of a non-return flap valve 10 (two such interconnections 9 and two such flap valves 10 are shown in F igur e 3 ) . The f lap valves 10 prevent substantial flow from the head development chamber 2 to the retention chamber 3. The interconnections 9 and the flap valves 10 are such that the rate of flow through them permits the level in the retention chamber 3 to fall at substantially the same rate as that in the head development chamber 2 when the head development chamber 2 is emptying, though the level in the retention chamber 3 must be slightly higher for the flow through the interconnections 9 to occur.

Inspection openings, ladders and vent tubes are shown but need not be described in detail.

The retention apparatus can be manufactured in a variety of materials, including steel, glass-reinforced plastics, or stainless steel (all of which may be encased in concrete), or concrete which can be sectional (built up of pre-formed sections) or formed in situ with say steel or wooden shuttering. Figures 4 to 6

In the remaining Figures, parts having the same or similar functions to those in Figures 1 to 3 are referenced with the same references.

The retention apparatus of Figures 4 to 6 is very similar to that of Figures 1 to 3, but a slightly different design of flow controller 8 and of non-return flap valve 10 is used, the flow controller 8 being associated with a special sump 11.

Figures 7 to 9

The retention apparatus of Figures 7 to 9 is generally similar to that of Figures 1 to 3, but the inlet 5 and outlet 7 are at right angles to the tank 1 rather than longitudinal.

Figures 10 and 11

The retention apparatus of Figures 10 and 11 is most similar to that of Figures 4 to 6, but the tank 1 contains a baffle-weir 4 in the form of a cylindrical shell which divides the tank 1 into an inner head development chamber 2 and an outer retention chamber 3. As seen in horizontal section, the head development chamber 2 is wholly surrounded by the retention chamber 3. The tank 1 has its axis vertical, and can have various diameters, e.g. of about 1.2, 1.8, 2.25, 2.5, 3 or 4 metres.

* * * * *

The embodiments described above can control the discharge of overloaded drainage systems and provide storage capacity. The unique combination of features significantly reduces the storage requirement when compared with traditional systems. In each case, there is a single tank 1 divided into a head development chamber 2 and a retention chamber 3 by a suitable baffle-weir 4. There can be one or more high level inlets 5 and one or more low level outlets 7. The flap valve(s) 10 in the baffle-weir 4 allow free flow from the retention chamber 3 to the head development chamber 2 when the inlet flow decreases and the head in the head development chamber 2 falls.

The apparatus will be incorporated in a drainage system, specifically intermediate ends of a drainage duct, in which the maximum design rate of flow through the inlet 5 is considerably greater than the rate of flow through the flow controller 8 and outlet 7 when the head development chamber 2 is full, though it would be expected that the inlet 5 would only be subject to its maximum flow rate for relatively short periods of time. In operation:

i. Water flows in through the inlet 5 and is deflected downwards by the inlet flow deflector 6 (or by a similar arrangement such as the specially-shaped inlet 5 in Figures 10 and 11) into the head development chamber 2.

ii. The water will flow out through the flow controller 8 and the outlet 7.

iii. As the inlet flow rate increases, the flow controller 8 will restrict the discharge and the head of water will build rapidly within the head development chamber 2 until the top of the baffle-weir 4 is reached.

iv. At this point the flow controller 8, due to the effect of the induced head, is operating close to its maximum designed discharge rate.

v. The water will then spill over the baffle-weir 4 into the retention chamber 3.

vi. Whilst the high inlet flow is maintained, the level in the retention chamber 3 will increase, possibly utilising the full capacity of the tank. vii. During the entire period taken to fill the retention chamber 3, the flow controller 8 continues to discharge at, or close to, its designed maximum discharge rate.

viii. When the inlet flow rate reduces, the level in both chambers 2, 3, will decrease, roughly at the same rate. Water from the retention chamber 3 will pass through the low level interconnection(s) 9 and the non-return flap valve(s) 10 into the head development chamber 2, continuing to feed the flow controller 8 and discharging from the tank 1. As the retention chamber 3 keeps the level in the head deveopment chamber 2 as high as possible, the rate of discharge from the apparatus as a whole is maximised.

Example

In practice, the appartus will be designed in dependence on the site and Water Authority requirements. The restriction on the surface water discharge imposed by the Water Authority dictates the maximum permissible rate of discharge. The flow off the whole of the site dictates the size of the inlet 5, which in turn dictates the size of the valves 10. The relationship between the flow into the apparatus, the flow out of the apparatus and the retantion required then dictate the overall size of the apparatus. Thus the details given below are just by way of example. The details can be applied to any of the embodiments described above and are taken for a maximum permissable outflow rate of 150 1/s, with a surge of up to 325.5 1/s for a maximum duration of 6 minutes.

Data:

Flow controller - "Hydrobrake" type "C", size 279 mm. Storage volume required - 65.13 m³

Full height flow - 150 1/s

Inlet diameter - 450 mm

Maximum inlet flow - 325.5 1/s

Diameter of both flap valves 10 - 450 mm Volume of head development chamber 2 - 12 m³ Volume of retention chamber 3 - 53.13 m ³

Time to fill whole tank with maximum inlet flow - 9.86 minutes

* * * * *

The present invention has been described above purely by way of example, and modifications can be made within the spirit of the invention. For instance, there may be more than one tank or more than one retention chamber.

INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)

(51) International Patent Classification ^**•^* : (11) International Publication Number: WO 89/ 087 E03F 5/10 Al (43) International Publication Date

21 September 1989 (21.09.

(21) International Application Number: PCT/GB 89/00265 (81) Designated States: AT, AT (European patent), AU, BE (European patent), BG, BJ (OAPI patent),

(22) International Filing Date: 15 March 1989 (15.03.89) CF (OAPI patent), CG (OAPI patent), CH, CH ( ropean patent), CM (OAPI patent), DE, DE (Eu pean patent), DK, FI, FR (European patent),

(31) Priority Application Number: 8806093 (OAPI patent), GB, GB (European patent), HU, (European patent), JP, KP, KR, LK, LU, LU (Eu

(32) Priority Date: 15 March 1988 (15.03.88) pean patent), MC, MG, ML (OAPI patent), MR (O PI patent), MW, NL, NL (European patent), N

(33) Priority Country: GB RO, SD, SE, SE (European patent), SN (OAPI tent), SU, TD (OAPI patent), TG (OAPI patent), U

(71) Applicant (for all designated States except US): CON-

DER GROUP PLC [GB/GB]; Kingsworthy Court, Published Kings Worthy, Winchester, Hampshire S023 7SJ With international search report. (GB). Before the expiration of the time limit for amending claims and to be republished in the event of the rece

(72) Inventor; and of amendments.

(75) Inventor/ Applicant (for US only) : CARR, William, Anthony [GB/GB]; Dingley Dell House, Beacon Bottom, Swanwick, Southampton S03 7AS (GB).

(74) Agent: LYNDON-STANFORD, Edward, Willoughby, Brooke; Marks & Clerk, 57-60 Lincoln's Inn Fields, London WC2A 3LS (GB).

(54) Title: LIQUID CONTROL APPARATUS

(57) Abstract

A water retention and flow control tank is divided into a head development chamber (2) and a much larger retentio chamber (3) by a baffle-weir (4) which provides an overflow from the head development chamber (2) to the retentio chamber (3). The head development chamber (2) has an outlet (7) associated with a vortex flow controller (8), and there ar non-return flap valves (10) which allow the retention chamber (3) to drain back into the head development chamber (2 whilst preventing substantial flow from the head development chamber (2) to the retention chamber (3). When there is e.g heavy rainfall, the water level builds up very quickly in the head development chamber (2) and the vortex flow controlle (8) rapidly reaches its operating head, ensuring that the water discharge from the tank is at a predetermined maximu flow rate for the maximum period of time.

FOR THE PURPOSES OF INFORMAHON ONLY

Codes used to identify States party to the PCT on the frontpages of pamphlets publishing international applications under the PCT.

AT Austria FR France ML Mali

AU Australia GA Gabon MR Mauritania

BB Barbados GB United Kingdom MW Malawi

BE Belgium HU Hungary NL Netherlands

BG Bulgaria rr Italy NO Norway

BJ Benin JP Japan RO Romania

BR Brazil KP Democratic People's Republic SD Sudan

CF Central African Republic ofKorea SE Sweden

CG Congo KR Republic ofKorea SN Senegal

CH Switzerland LΓ Liechtenstein su Soviet Union

CM Cameroon LK Sri Lanka TD Chad

DE Germany, Federal Republic of LU Luxembourg TG Togo

DK Denmark MC Monaco US United States of America

Liquid Control Apparatus

Background of the Invention

It is desirable to provide liquid retention and flow control, principally for a drainage system that has to cope with storm water, but also for other systems such as a sewage balancing system. Increased demand on new and existing drainage systems due to further development, peak discharge of sewage, or the influx of stormwater, can result in intermittent overloading. In such circumstances, it is known to use a retention tank (also called an attenuation tank or balancing tank), but the discharge is directly proportional to the head in the tank, and therefore the maximum discharge rate is only achieved briefly when the tank is full. DE-A-3 022 997 and DE-A-3 022 998 describe liquid control apparatus which is also illustrated in a brochure entitled "Automatisch wirkende Wehrsysteme". The apparatus is for discharging storm water so that it does not burden the sewerage system, and instead of a simple overflow, a float with a raisable barrier is used so that the liquid discharged is taken from the middle zone of the channel. In order to do this, there is a type of head development chamber with a weir and a raisable baffle above, which discharges into a second chamber which is of a capacity substantially greater than that of the head development chamber. However, the second chamber merely acts to collect the excess water, which is apparently immediately discharged and by-passes the remainder of the system.

The Invention

The means in the interconnection can be of any sui table type, and complete liquid-tightness is not required. In practice, it is desirable to prevent substantial flow through the low level interconnection into the retention chamber and a non-return flap valve is suitable as such means, for this purpose. However, at least in theory. all that is necessary is that the rise in level in the retention chamber should not be as fast as the rise in the head development chamber, and for instance a vortex flow controller could be used as said means, or any means which permits a faster flow out of the retention chamber than into it.

The Drawings

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: -

Figures 1 to 3

There is a high level inlet 5 which directs water flow into the head development chamber 2, associated with an inlet flow deflector 6. There is an outlet 7 from the head development chamber 2, the outlet 7 incorporating a f low controller 8 . Flow controllers such as vor tex flow controllers are designed to a specific head - it is preferred that this specific head be the top of the tank 1, i.e. designed to the maximum head that could be in the tank. There is a low level interconnection 9 between the retention chamber 3 and the head development chamber 2 for allowing the retention chamber 3 to drain into the head development chamber 2, the interconnection 9 having valve means in the form of a non-return flap valve 10 (two such interconnections 9 and two such flap valves 10 are shown in Figure 3). The flap valves 10 prevent substantial flow from the head development chamber 2 to the retention chamber 3. The interconnections 9 and the flap valves 10 are such that the rate of flow through them permits the level in the retention chamber 3 to fall at substantially the same rate as that in the head development chamber 2 when the head development chamber 2 is emptying, though the level in the retention chamber 3 must be slightly higher for the flow through the interconnections 9 to occur.

The retention apparatus of Figures 4 to 6 is very similar to that of Figures 1 to 3 , but a slightly different design of flow controller 8 and of non-return flap valve 10 is used, the flow controller 8 being associated with a special sump 11.

Figures 7 to 9

Figures 10 and 11

* * * * *

ii. The water will flow out through the flow controller 8 and the outlet 7.

Example

Data:

Full height flow - 150 1/s

Inlet diameter - 450 mm

Maximum inlet flow - 325.5 1/s

Time to fill whole tank with maximum inlet flow - 9.86 minutes

* * * * *

Claims

Cla ims :

1. Liquid control apparatus, comprising a head development chamber (2), an inlet (5) directing inlet flow into the head development chamber, an outlet (7) from the head development chamber, a second chamber (3), of a capacity substantially greater than that of the head development chamber, and an overflow (4) which passes overflow to the second chamber when the head development chamber, is full, characterised in that the second chamber is a retention chamber in which excess liquid is retained, and in that there is a low level interconnection between the retention chamber and the head development chamber for allowing the retention chamber to drain back into the head development chamber, the low level interconnection having means (10) preventing gross flow through the low level interconnection from the head development chamber to the retention chamber.

2. The apparatus of Claim 1, wherein the outlet (7) has a vortex flow controller (8).

3. The apparatus of Claim 1 or 2, wherein the overflow (4) leads directly out of the head development chamber (2).

4. The apparatus of Claim 3, and comprising a single tank (1) which is divided into the head development chamber (2) and the retention chamber (3) by a baffle which also acts as a weir (4) to provide the overflow.

5. The apparatus of any of the preceeding Claims, wherein, as seen in horizontal section, the head development chamber (2) is wholly surrounded by the retention chamber (3).

6. The apparatus of any of the preceding Claims, wherein the rate of flow through the low level interconnection (9) when the level in the head development chamber (2) is falling is such that the level in the retention chamber (3) falls at substantially the same rate,

7 The apparatus of any of the preceding Claims, wherein the means (10) preventing substantial flow are valve means.

8. A drainage system incorporating the apparatus (1) of any of the preceeding Claims, with the maximum design rate of flow through the inlet (5) substantially greater than the rate of flow through the outlet (7) when the head development chamber (2) is full.

9. A drainage system, comprising an inlet drainage duct, a head development chamber (2) into which the inlet drainage duct directs flow, an outlet drainage duct leading from the head development chamber, a second chamber (3), of a capacity substantially greater then that of the head development chamber, an overflow (4) which passes overflow to the second chamber when the head development chamber is full, and means (8) effectively restricting flow through the outlet drainage duct, characterised in that the second chamber is a retention chamber in which excess l iquid is reta ined , and in that there is a low level interconnection (9) between the retention chamber and a point upstream of the flow restricting means (8) for allowing the retention chamber to drain into the outlet drainage duct, the low level interconnection having means (10) preventing gross flow through the low level interconnection to the retention chamber.

10. The drainage system of Claim 9, wherein the outlet (7) has a vortex flow controller (8), and/or the rate of flow through the low level interconnection (9) when the level in the head development chamber (2) is falling is such that the level in the retention chamber (3) falls at substantially the same rate, and/or the means ( 10 ) pr even t ing su bs ta n t i a l f low a r e valve means .