FR2704449A1 - Screen mesh device for overflow tanks. - Google Patents

Abstract

The screen-screen device is disposed on, or in, the top of an overflow wall (7) and consists of a screen (11) and a retaining wall (31). On the bottom of the chamber (37) located between the retaining wall (31) and the grid (11) is disposed a tank (45) whose bottom surfaces (39) are inclined relative to the horizontal and whose the lower part has a check valve (41) which is closed by the action of the water present in the discharge channel in the event of rain and which, at the end of the rain, opens so as to allow the impurities (38) which have settled in the chamber (37) to be evacuated to the discharge channel (5) and, from there, to the purification installation.

Description

Screen mesh device for overflow tanks.

  The invention relates to grid devices.

  sieve for overflow tanks, flood discharge installations and the like, comprising a grid mounted on an overflow wall and formed of parallel bars or cables, fixed to a frame by their ends and arranged at a distance from each other, grid the useful passage surface of which is at an angle between 45 and with the horizontal, the device further comprising a retaining wall for placing the retaining height at the

  height of the upper edge of the grid.

  In the event of heavy rain, the runoff water arriving in a treatment plant can no longer be brought in one piece to the treatment process, since the capacity of the treatment plants is not adapted to the flows highest arrival. This is why provision is made upstream of the treatment plants for rainwater overflow basins into which the water arriving in such circumstances is first introduced. As long as the quantity of incoming water can be taken over by the treatment plant, there is no water flowing to an outlet or directly to a watercourse. If the quantity of water that occurs exceeds the capacity of the treatment plant, the part that exceeds this capacity is diverted to the rainwater overflow basin. However, in order to retain the coarsest impurities, in particular those which float, the water is passed through screens or grids. To do this, the water can be passed from the bottom to the top through these sieves or grids, so that, after the rain, the accumulated impurities can be flushed backwards and, if necessary , take them to the treatment plant. Instead of a grid or a horizontal sieve, you can also

  use a vertical grid to perform this function.

  These grids are generally arranged on an overflow edge which separates the overflow basin from the

rain from the emissary's entrance.

  The flow passing through a grid mounted on an overflow edge is mainly concentrated in the vicinity of this, insofar as, in most cases, the level of the inflowing water does not reach the upper edge of Grid. There is therefore very quickly an accumulation in this zone or a clogging and consequently an undesirable raising of the overflow threshold and consequently a modification of the

hydraulic characteristics.

  It is already known to have, on the overflow edge and on the downstream side, a retaining plate or a retaining wall corresponding, or whose upper edge corresponds, to the desired height of the hydraulic overflow threshold . This makes it possible to start the flow through the grid only when at least most of it is below the level of the water upstream. This grid device solves the problem of partial clogging of the grid in the case where small amounts of water cross the edge of the overflow. On the other hand, when the water level exceeds the upper edge of the grid, the impurities can cross this edge, reach the intermediate chamber located between the grid and the means raising the overflow threshold and, during the decline of the influx of water, these impurities, along with the finer ones which have passed through the grid and deposited, may accumulate behind the grid, in the V-shaped space between the grid and the means for raising the overflow threshold. The cleaning of these grids and of the surrounding parts of the essentially concrete wall is expensive. The invention therefore aims to provide a grid device for overflow basin which allows to keep the fouling of the grid at a low level in the case where small quantities of water overflow and which allows, after the rain, easily remove

impurities retained.

  The subject of the invention is therefore a grid device of the type described at the start, which is characterized in that the bottom parts delimiting the bottom of the chamber formed by the grid and the retaining wall form an acute angle with the bars or the grid cables and, at their lowest part, are connected to a check valve

  retainer opening into the discharge channel.

  Other interesting features of the invention are as follows: At its lower part, the chamber may have the shape of a tank arranged so that it can be mounted or

  recessed at the top of the overflow wall.

  - The bottom parts of the tank can also be inclined to form a slope towards the discharge channel. - Upstream of the grid can be fixed a closure wall which is movable in height under the effect

  a float and / or an electrical actuation means.

  - The closing wall can be arranged so as to be able to pivot with respect to a horizontal axis or

  so that it can slide vertically in a guide.

  - A discharge bridge can be placed over the

  grid to pass water over the room.

  - The overflow bridge can have a vertical part connecting to the upper edge of the grid and a horizontal part, these two parts can be fixed

  or adjustable or adjustable in height or length.

  - In the bedroom, a pressurized watering system can be arranged to clean the grid

and / or the bottom parts.

  - To clean the grid, a comb can be mounted

  so that it can be moved parallel to the grid.

  - The comb drive means can be arranged in

  a pipe mounted on the upper edge of the grid.

  Thanks to the inclination in sections of the top of the overflow wall on which the grid and the retaining wall are mounted, the impurities remaining between the grid and this wall collect and, after the rain, can be sent to the wastewater treatment plant. Dirt is removed automatically after the water level has dropped. A wall, which is arranged upstream of the grid, which penetrates below the water level upstream and is adjustable in height according to the water level, prevents floating impurities from accumulating on the grid when the water rises. A float ensures the lifting of this wall as soon as the water level has reached a suitable predetermined height. In the case of heavy rain where the volumes of water can no longer be taken care of by the grids alone, the impurities are prevented from reaching between the grate and the retaining wall by a bridge extending over the wall. overflow. In a particular embodiment, the height and the length of the discharge bridge are both adjustable in size and in position. The cleaning of the grid can be ensured by a comb actuated by

  roller and motor or by a sprinkler system.

  The invention will now be described in more detail using the embodiment examples shown in the drawing. We see: - in Figure 1, a sectional view of a rainwater basin, taken along line I-I of Figure 2;

  - in Figure 2, a sectional view of the overflow wall

  solid, taken along line II-II of the figure; - in Figure 3, a sectional view of another embodiment of a grid device placed on an overflow wall; and - in Figure 4, a sectional view of an overflow or rainwater discharge basin in the vicinity

  which is arranged a flood water discharge channel.

  In the flood water discharge installation 1 shown schematically and in section in FIG. 4, one can see, on the left side of the figure, a basin 3 for rainwater overflow or discharge basin and, on the right side, a discharge channel 5. The latter is situated at a height greater than that of the discharge basin 3 and is separated from it by an overflow wall 7 comprising an overflow edge 9. On this edge 9 is arranged, vertically, a grid 11 provided with bars 13, for example metal profiles. At their ends, these bars 13 are fixed to the vertical uprights of a

frame 15.

  A movable comb 21 can be placed on the upstream side or on the downstream side of the grid 11. The teeth of this comb are fixed to a vertical beam 24 and penetrate into the spaces between neighboring bars 13. The comb 21 can be suspended from a support roller and be guided in a slide carried by the frame 15 of the grid 11 while being actuated for horizontal displacement by a motorized chain actuating means or by a linear actuating means. hydraulic, pneumatic or electric. In the first embodiment according to FIGS. 1 and 2, the grid 11 is mounted by being inclined relative to the vertical, which makes it possible to increase the passage section of the grid while maintaining an identical height of grid 11. This grid is placed on the upper edge 23 of the overflow wall 7, so that

  its lower edge makes an acute angle with the horizontal.

  At the upper edge of the frame 15 of the grid 11 is connected a discharge bridge 25 which has a vertical part 27 extending up to a height h2 and a horizontal part 29 extending horizontally so as to be found practically above the edge upper of a retaining wall 31 creating the retaining height hl. The vertical part 27 and the horizontal part 29 can be arranged so that they can be adjusted or adjusted in

  height, respectively in length.

  In the horizontal part 29 of the overflow bridge 25 is provided a tubular sleeve 33 through which the actuation of the comb 21 can be ensured without the overflowing water being able to reach from above into the intermediate V-shaped chamber 37 located between the retaining wall 31 and the downstream face of the grid 11. The discharge bridge 25 and the retaining wall 31 are both made of sheet metal. To offset the effects of the pressure exerted upstream by the rising water, the grid 11 can be connected

  to the roof or to the walls of structure 1 by props 35.

  The chamber 37 essentially in V, located between the retaining wall 31 and the grid 11, has at its lower part bottom portions 39 which form an acute angle (see FIG. 1) with the bars 13 of the grid, in d 'other terms which deviate from the horizontal, and which, at their lowest part, all have a check valve opening into the discharge channel 5 and

  comprising a duct 41 provided with a tilting cover 43.

  The bottom parts 39 can be formed in the overflow wall 7 during the manufacture thereof or be made in the form of a tank 45 in sheet metal. The bottom parts 39 are also advantageously inclined in the direction of the discharge channel 5 (see FIG. 2). This tank 45 can be directly fixed to the retaining wall 31 or else the latter can be a part of the tank which is then mounted in one piece on the wall of

overflow 7.

  Depending on the length of the grid 11, there may be one, two or more than two V-shaped tanks 45 of this type, juxtaposed on the overflow wall 7. The tanks can be made in advance in the factory and be reported in the structure once it is completed,

  i.e. mounted on top of the overflow wall

full 7.

  On the upstream side of the grid 11, a closure wall 49 is pivotally mounted on the frame O10 15 by a horizontal articulation 47. A float 51 is also fixed to the closure wall 49, this float 51 allowing the position of the closure wall 49 to follow the level of the water upstream side in the discharge channel 5. When the water level rises sharply, a shock absorber pad 53 is there to prevent the closure wall 49 from deviating from the vertical position shown in FIG. 3 when it pivots in the anti-clockwise direction. The lower edge of the closure wall 49 may have a folded portion in order to prevent the passage of impurities towards the grid when the water rises. In addition to the pivoting closure wall 49, a rigid diving wall 50 can be fixed to the roof or to the walls of the structure 1 to stop the impurities during the emergency discharge above the bridge.

spill 25.

  In the embodiment of Figure 3, the grid 11 is vertical. The arrangement and the position of the overflow bridge 25 corresponds to the first embodiment. Instead of a pivoting closure wall, in the second embodiment, a closure wall 55 is slidably mounted vertically in two guide rails 57 mounted vertically. As in the first embodiment, a float 51 is fixed to the closure wall 55 and serves to adapt the position of the latter to the height each time reached by the water level in the discharge channel 5. In its highest position, this closure wall 55 serves as a diving wall

  for emergency discharge, when the water flows out

  above the discharge bridge 25 from height h2.

  The closure wall 55 can not only retain floating impurities 61, but also oil. Preferably, a sealing strip 59 is mounted on the overflow wall 7 at the level of the lower end of the guide rails 57 to prevent the passage of floating impurities 61 behind the wall

shutter 55.

  We will now describe the operation of

grid devices.

  At the start of a rain and while the water level in the discharge channel 5 has not yet reached the float 51, the closure wall 49 is in the position shown in solid lines in FIG. 2 o it bears against the overflow wall 7 and, at the start of the rise in the water, prevents impurities 61 floating on the surface of the water from passing into the space delimited by the overflow wall 7, the grid 11 and the closure wall 49. As soon as the water level rises, the closure wall 49 pivots counter-clockwise under the effect of the float 51 and the water can rise and enter the chamber 37 by passing through the grid 11. Water thus flows until the chamber 37 is filled. It is only when the water level in the discharge channel 5 has reached the height hi that a continuous flow begins, which means that a continuous flow of water with the impurities which had already been partially retained by the closure wall 49 only occurs when the entire surface of the grid is submerged. This gives a regular distribution of the impurities 61 retained by the grid 11. During the residence time of the water passing through the chamber 37, the impurities 38 therein, which have managed to pass through the grid 11, are deposited. The impurities 38 which are deposited slide on the bottom parts 39 to the check valve 41 where they are retained. This check valve 41 or its cover 43 is closed when the inflowing water is above the hi level, since it is kept closed by the static pressure of the water in the

discharge channel 5.

  x5 If the water in the discharge channel substantially exceeds the level hi, this, although not purified, can escape from the discharge channel 5 by passing over the discharge bridge 25. As a result, the room 37 is not

does not fill with impurities 61.

  As soon as water decreases in the discharge channel, i.e. the water level drops below the hi level, water can no longer escape over it

  the retaining wall 31. As soon as the water level drops below

  below the check valve 41, the cover 43 opens and the impurities 38, which have settled on the bottom parts 39, return, with the water which has also been thus retained, in the discharge channel 5 by the check valve 41 now open and, from this channel, into a

purification plant.

  The operation of the embodiment shown in FIG. 3 differs from the previous one only in that, under the action of the water rising in the discharge channel 5, the closure wall 55 slides vertically upward to allow the water to pass through the grid 11. As long as there is a low water level, the float 51 is not raised, so that, also here, the impurities threatening only the part grid 11 cannot penetrate. Here too, the grid 11 does not operate fully until the water reaches the level hl (position of the wall

  shutter 55 shown in broken lines).

  The covers 43 of the check valves 41 can alternatively be also actuated for their opening or closing by an electric or pneumatic actuating means. In this way, it is possible to retain, in the tanks 45, a greater quantity of water when the water level in the discharge channel 5 decreases and to release it suddenly, so that the impurities 38 which have accumulated in these tanks

  are swept away by a powerful flush.

  The actuating means 12 of the comb 21 can also be disposed directly above the grid 11, in a pipe 14, and be constituted by a linear actuating means (pneumatic cylinder, hydraulic cylinder or electrical actuating means ) (see it

figure 3).

  In place of the comb 21 shown in FIG. 4, or in addition to this comb, one can provide, in the chamber 37, a sprinkler installation 63 or a pressurized jet device for cleaning the grid 11. The installation 63 can also be used for

tank cleaning 45.

  Instead of bars 13 of the grid fixed in a frame 15, it is also possible to use stretched metal cables (not shown).

Claims (8)

  1- Grid device for rain overflow basins, flood discharge installations and the like, comprising a grid mounted on an overflow wall and formed of parallel bars or cables, fixed to a frame by their ends and arranged at a distance each other, a grid whose useful passage surface makes an angle between 45 and 90 with the horizontal, the device further comprising a retaining wall for placing the retaining height at the height of the upper edge of the grid, characterized in that the bottom parts (39) delimiting the bottom of the chamber (37) formed by the grid (11) and the retaining wall (31) form an acute angle with the bars or cables (13) of the grid and, at their lowest part, are connected to a check valve (41) opening into the discharge channel (5).  2- grid device according to claim 1, characterized in that, at its lower part, the chamber (37) has the shape of a tank (45) which is arranged so that it can be mounted or embedded at the top of the wall of overflow (7).   3- Grid device according to claim 1 or 2, characterized in that the bottom parts (39) of the tank (45) are also inclined to form a slope in   direction of the discharge channel (5).   4- Grid device according to one of   claims 1 to 3, characterized in that, upstream of the   grid (11) is fixed a closure wall (49, 55) which is movable in height under the effect of a float (51)   and / or an electrical actuation means.   - Grid device according to claim 4, characterized in that the closure wall (49) is arranged so as to be able to pivot relative to a horizontal axis or in that the closure wall (55) is arranged so able to slide vertically in a guide (57).   6- Grid device according to one of   claims 1 to 5, characterized in that a bridge   spill (25) is placed above the grid (11),   to pass water over the chamber (37).   7- Grid device according to claim 6, characterized in that the discharge bridge (25) comprises a vertical part (27) connecting to the upper edge of the grid (11) and a horizontal part (29), these two parts (27, 29) being fixed or adjustable or   adjustable in height or length.   8- Grid device according to one of   claims 1 to 7, characterized in that, in the   chamber (37), there is a sprinkler system or a nozzle (63) under pressure jet to clean the grid   (11) and / or the bottom parts (39).   9- Grid device according to one of   Claims 1 to 8, characterized in that, for cleaning   the grid (11), a comb (21) is mounted so as to   can be moved parallel to the grid (11).   - Grid device according to one of   claims 1 to 9, characterized in that the means   drive (12) of the comb (21) is arranged in a pipe (14) mounted on the upper edge of the grid (11).