FR2677057A1 - SCREENING GRID FOR TOO FULL OF RAINWATER. - Google Patents

Abstract

The sieve grid for storm water overflow basins and similar installations consists of a frame (2) inside which bars (3) placed parallel side by side are inserted. Between said bars (3) penetrates a comb (17) having teeth (31) and capable of pivoting about an axis (A). Said teeth (31) are resiliently mounted in the direction of the axis (A). The pivot axis. (A) arranged above the grid (4) has the effect that the teeth (31) penetrate to depths (31) between the bars (3) and clean themselves and the grid (4) automatically at each pivoting movement.

Description

The subject of the present invention is a screening grid for a

  rainwater overflow, flood weirs and similar installations comprising a grid consisting of parallel bars and arranged side by side at a certain mutual distance and a comb movable longitudinally whose teeth are arranged

  way to penetrate the interstices between the bars.

  In the event of heavy rain, the wastewater arriving in a treatment plant can no longer be subjected in its entirety to the treatment process because the capacity of these stations does not allow to treat the maximum possible quantities of input For this reason , rainwater overflow basins into which water first enters are installed upstream of these treatment plants As long as the quantity of input water can be accepted by the treatment plant, there no passage of water occurs to an evacuator or directly to a watercourse If the quantity of water supply exceeds the capacity of the treatment plant, the excess part is diverted To be able, however, retain the coarsest impurities, in particular floating impurities, the water passes through sieves or grids It has proved advantageous to pass the water from bottom to top through such sieves or grids in order to power, l when the rain has stopped, also lead these impurities to the treatment plant. Such sieves or screens through which the water flows from top to bottom must be cleaned periodically, even during their operation, that is to say during the passage water, to prevent waterlogging, i.e. backflow of water and therefore a change

  hydraulic conditions of the entire station.

  By European patent application 0358952, a screen is known which is made up of a large number of thin bars arranged side by side and held inside a frame serving as a clamping device. On one side of the grid are fixed chains using which a carriage carrying teeth can move back and forth along the grid The teeth arranged on this carriage are rigid

  or can be tilted when the carriage returns.

  This known grid is of very complex manufacture and is provided with elements such as toothed wheels, chains, etc. which rotate in polluted water. Such a construction is not suitable for use in waste water and easily falls into failure In addition, the thin bars which extend over the entire length of the grid must be held tight by a clamping device to prevent large impurities in the water from spreading the bars and passing through Another drawback of this device lies in the fact that the direction of rotation of the chain motor must be reversed, in the end positions of the grid, by feelers. In the event of defection of one of these feelers, damage may occur on the bars, motor or grille teeth If any part of the installation is damaged, there is a risk of obstruction of the entire grille

  and therefore a reflux of wastewater to the station.

  The invention proposes to remedy these

disadvantages -

  The object of the invention is to provide a screening grid which eliminates the drawbacks of known devices, which operates without control elements and which can be manufactured at an advantageous cost. This problem is essentially solved by the fact that the grid consists of several sections arranged one behind the other and that on each section is disposed a yoke which can slide back and forth along said section and comprising a comb with teeth penetrating from the top to

  the bottom in the interstices - against the bars.

  Surprisingly, it is possible, thanks to the screening grid according to the invention, to continuously clean the passage section of the grid and to keep it clear during a heavy rain The teeth passing along the bars of the grid divided itself into segments can, when they come into contact with an obstacle, be tilted in groups outwards in both directions Tipping elements attached to the reversing points cause the teeth to be cleaned with each movement of back and forth By this movement of entry and exit is carried out a continuous self-cleaning of the teeth which are themselves animated by a mutual movement perpendicular to the surface of the bars As a result, the impurities adhering to the bars can be detached and transported to the side The teeth are spaced apart on two bars at the base of the comb and held in place by spacing discs of different thicknesses this results in a great elasticity in the transverse direction with respect to that of the movement. The drive elements are located outside of rainwater and it is therefore unnecessary to take expensive measures to e: prevent their fouling The grids can be driven by a motor without the need for electrical or mechanical control elements or a probe driven by a simple crank motor, the latter being able to be axially elastic The round profiles fixed on the bars on the side of the inlet of the flow have for effect of preventing impurities from becoming trapped between the bars and preventing any deterioration of teeth

  isolated or from the whole mechanism.

  With reference to an exemplary embodiment shown in the accompanying drawing, the invention will be explained in more detail

detail below On this drawing.

  FIG. 1 shows a plan view of a rainwater overflow basin equipped with a screening screen in five parts; Figure 2 is a cross section along line II-II of Figure 1 of the overflow basin; Figure 3 is a cross section along the line III-III of Figure 1 (without the comb); Figure 4 is an enlarged partial cross-section of the grid in area A of Figure 3; Figure 5 is an enlarged perspective view of a tooth of the cleaning comb; Figure 6 is a cross section of a package of pivotable teeth; Figure 7 is an enlarged cross section of the grid provided with the teeth; FIG. 8 is a diagrammatic representation of a screen grid fitted with a motor arranged outside the grid; FIG. 9 is a schematic representation of a two-part sieving grid, fitted with a motor; FIG. 10 is a top view of a screening grid equipped with a motor placed laterally; FIG. 11 shows a screening grid equipped with a linear motor; and Figures 12 to 14 are schematic representations of two discharge facilities for

  floods equipped with different cleaning systems.

  In a wastewater treatment plant for which, for better visibility, only the rainwater overflow basin 1 has been shown by way of example, the latter consists of a chamber 3 separated into three sections extending longitudinally Section 5 reaches the bottom 7 of the chamber 3 and is delimited laterally by a discharge wall of height hl and by the side wall il of the basin 1 (see FIGS. 1 and 3) The chamber 3 is connected - to an evacuator from the treatment plant (not shown) The two sections 13 and 15 of the chamber located laterally to section 5 are connected to each other on their slab 17 A scum-proof wall 17 whose lower edge 21 opens out under the upper edge 10 of the discharge wall 9 and whose _ the upper edge 24 is located at height h 2, separates the two chamber sections 13 and 15 On the slab 17 of the chamber section 13 is a outlet 23 in l equel can be inserted a throttle valve 25 which limits the flow rate of the outflow from the two

chamber sections 13, 15.

  A screen grid 29 is inserted into a frame 27 between the discharge wall 9 and the foam screen wall 19 In the example shown, this screen 29 consists of five individual screens 29 a, 29 b, 29 c, 29 d and 29 e separated by a cross member 31, the grid being situated at the height hl On the parts 27 of the frame extending longitudinally, which can be constituted for example in profiled rectangular tube, guide rails 33 are fixed on their upper edge by means of screws 35 The guide edges 37 oriented towards the grid 29 protrude from the internal face placed below the frame 27 a cleaning comb 39 is inserted between the rails 33 facing each other, movably longitudinally, by means sliding jaws 41 This comb 39 consists of a yoke 43 at the ends of which the jaws 41 are fixed and on the lower side of which are arranged packages consisting of teeth 49 disposed at a certain mutual distance by spacing discs 48 and 81 and stored side by side on a bar 45 and a tube 46 (Figure 4) The round bar 47 supporting the tube 46 is fixed, at least by its ends, on two legs 51 fixed themselves on the yoke 43 Other legs 51 can be placed between the legs 51 arranged at the ends so

  to provide additional guidance for the round bar 47.

  The tube 46 is held by means of sockets 50 on the round bar 47 so as to rotate between the legs 51. This tube 46 and the upper round tube 45 are fixedly connected to each other by strips 52 De this fact, the whole package of teeth can be tilted outwards on the bar 47 in the form of a complete unit. The round bar 45 located at the top is divided into short sections which are located between the legs 51 without being fixed on them In Figure 5, a single tooth 49

  of the package is shown for better visibility.

  Between two neighboring teeth 49 are pivotally inserted on the bar 45 at least two tension plates 53 and 55 instead of a spacer disc 48, these sheets each being connected to a tension spring 57 and 59 of which l end is fixed on the yoke 43 The tension springs 57, 59 are designed so that the teeth 49 come to lie vertically in the unloaded state

(figure 6).

  On the crosspieces 31 which separate the sections 29a, 29e of the grid, elements 83 for tilting towards the outside can be fixed, produced in the form of plates or tubes on which the teeth 49 abut just before the reversal point. and are flipped

up for cleaning.

  These teeth 49 penetrate into the intermediate spaces of bars 61 of the grid, located parallel side by side at regular distances and the ends of which are fixed on the crossbars 31 The bars 61 are made of flat steel 63 placed on edge and d '' a round steel 65 of greater thickness and fixed on the lower edge of the flat steel Of course the bars 61 of the grid can also be produced in a drawn profile whose cross section corresponds to what has just been described The distances between the round steels 63 placed side by side are slightly greater than the thickness b of the teeth 49 (FIG. 7) As regards the bars 61 placed in the vicinity of the parts 27 of the frame, the sections of flat steel 63 can be placed horizontally (not shown) The ends of the teeth 49 penetrating through the bars 61 of the grid are made in trapezoidal form, the sides placed s obliquely becoming the parallel sides of the teeth 49 only above the round steel 65 The yokes 43 associated with each grid section 29 a to 29 e and supporting the teeth 49 are connected to each other by assembly elements 67 (see FIGS. 2 and 8 to 11) The last yoke 43 placed above the grid element 29 e is connected by another assembly element 67 at the end of a rod d drive 71 fixed oscillatingly on the cover 69 of the chamber 3 The drive rod 71 is in connection with a crankshaft 73 which can be driven by a drive pulley 75 placed on a motor 77 The drive motor 77 can, as shown in Figures 1 and 2, be arranged inside the rainwater overflow basin 1 or outside thereof In the case of an engine 77 disposed outside of the pelvis, the drive rod 71 passes through an orifice 74 provided for this purpose in the

cover 69 (see figure 8).

  If the construction height is very low, the drive rod 71 and the crankshaft 73 can be arranged so as to pivot around vertical axes X and

  Y or next to grid 29 (figure 10).

  In the two arrangements of the motor, the drive rod 71 can act directly on the last yoke 43 located outside, on any of the

  other yokes or between two yokes 43.

  Moreover, the crankshaft drive can be replaced by an electric, pneumatic or hydraulic linear motor 80 (figure 11) The number of comb strokes and therefore the cleaning cycle can be adjusted to

degree of water pollution.

  For all training variants, it is-

  possible to incorporate elastic ei'Crayages and / or overload fuses to prevent overloading the mechanism. The mode of operation of the device is explained in more detail below. In the event of normal supply of polluted water to the chamber sections 13 and 15 (pipe not visible) the polluted water is led to a station.

  purifying through the orifice 23 and the reduction valve 25.

  If, then, the quantity of water supplied exceeds the flow rate which can be discharged through the valve 25, the level of

  water rises in the two chamber sections 13 and 15.

  When the level h1 is reached, the water which has not been discharged through the orifice 23 can penetrate from below through the grid 29 and reach, passing over the upper edge 10 of the discharge wall 9, in the chamber section 5 and from there be led to an evacuator The entrained impurities 79 remain attached to the lower face of the grid 29 and successively reduce the cross section of passage Through the teeth 49 (not shown in FIG. 3) fixed on the yoke 43 and penetrating between the bars 61 of the grid, the impurities 79 attached to the underside of the bars 61 of the grid can be removed from the zones traversed by the flow of water. To this end, the yokes 43 connected together by the connecting elements 67 perform a back-and-forth movement under the action of the motor

77.

  If an impurity 79 is wedged between the bars 61 of the grid without being able to be pushed to the side by the teeth 49, said teeth 49 of a pack tilt, inside this segment, between two legs 51 according to the arrows B towards the outwardly tilted position shown in FIG. 6 This effectively prevents any deterioration of the teeth 49 or other mechanical parts of the installation. In many cases, the impurity which caused this jamming will be expelled from the bars. 61 when the teeth return 39 Otherwise, only a small part of a single grid section will remain in the uncleaned state. Therefore, any blockage of the whole installation is impossible and in no case will it be necessary to stop the device

cleaning.

  In the case where elements 83 for tilting outwards are fixed on the crosspieces 31, the teeth 49 are tilted and cleaned at each reversal of their direction. In this example, if the amount of water entering the chamber sections 13 and 15 is greater than that which can be discharged through the reducing valve and the bars 61 of the grid, the water level continues to rise and reaches the height h 2 The water can then flow over the upper edge 24 of the foam screen 19 and reach directly into the chamber section 5 This makes it possible to effectively prevent any backflow from the water to the wastewater circuit. The screening grid according to the invention which, of course, is not exclusively intended for rainwater overflow basins and spillways, can be advantageously used in a combined breakwater installation and flush In such an installation like that shown in FIGS. 12 and 13, the feed water comes, in a first phase, to fill the basin with rainwater. 161 During this filling, the water passes through the valve of closure 162 open downstream of a foam screen 163 fixedly arranged and from there crosses the grid 29 from bottom to top and leaves the basin 161 passing through the channel 163 to reach an evacuator When the arrival of the the water is finished, the valve 162 is closed and the basin 161 is emptied by means of a pump or by gradient After the evacuation of the basin 161, the valve 162 is abruptly opened and the water accumulated behind the foaming wall 163 rushes big e speed by opening the valve 162 to go beyond the bottom 165 of the basin by cleaning it by passing it through the well or channel 166 At the same time, when the water accumulated behind the wall 163 flows down, the part of this accumulated water located above the grid 29 cleans the grid 29 and entrains towards the well 166 the impurities adhering to its underside In a flood weir according to FIG. 14, the cleaning of the sieving grid 4 s after the rain by means of a sprinkler system 167 arranged above the grid 4 The cleaning of the channel 164 by which the sieved water flows towards the grid can be carried out by means of a flush of water 169 So that the coarsest 1 l floating impurities, which enter the structure as indicated by arrow 171 and which float on the surface of the water, can be removed from the grid 4, it is possible to use a foam barrier 173 This keeps the impurities constantly in the right part of the submerged part of

said wall.

  The installation described for a horizontal arrangement of the; gril-ie 29 can, of course, be

  also used for a grid placed vertically.

Claims (1)

CLAIMS 1 Screening grid for rainwater overflow basin comprising a grid composed of bars arranged side by side at a certain mutual distance and a comb movable under the action of a motor along said bars, the teeth of said comb coming to engage in the interstices between the bars, characterized in that the grid (29) consists of several sections arranged one behind the other (29 a, 29 b, 29 c, 29 d, 29 e) and that on each section (29 a to 29 e) is disposed a yoke (43) which can slide in a reciprocating movement along said section and comprising a comb (39) provided with teeth (49) penetrating from the top the bottom in the interstices between the bars (61). 2 screening screen according to claim 1, characterized in that the yokes (43) are connected to each other by connecting elements (67) and by a drive bar (71) equipped with a motor d training (77, 80). 3 screening screen according to claim 2, characterized in that the driving of the yokes (43) is carried out by a motor with a connecting rod rotating continuously, disposed above or next to the screen (29) or on the cover (69) of the overflow basin (1), or by a linear motor (80) with electric, pneumatic or hydraulic control. 4 screening screen according to one of claims 1 to 3, characterized in that the teeth (49) are fixed in rows on two tubes or round bars (46, 45) arranged one on the other and qu 'they are arranged at a certain mutual distance by spacers (81, 48). Screening grid according to claim 4, characterized in that the lower tube (47) is fixed to the yoke (43) of a sliding beam (41) by means of lugs (51) and that the upper tube (45) is divided into sections and connected to the teeth (49) at a certain axial distance from the legs (51). 6 screen grate according to claim 5, characterized in that on the upper tubes (45) are placed tension plates (53, 55) which are connected to the yoke (43) by means of tension springs (57), 59) fixed on said tubes (45). 7 screen grating according to claim 5 or 6, characterized in that the teeth (49) are arranged so that they can be tilted in groups, outwards, around the longitudinal axis of the round bar (47) . 8 screen grate according to claim 7, characterized in that in the vicinity of the crosspieces (31) separating the sections (29 a to 29 e) of the grid, are fixed abutment elements (83) intended to make tilt the teeth (49) outwards. 9 Screening grid according to one of claims   1 to 8, characterized in that the grid (29) is mounted between the upper edge (10) of a discharge wall (9) and the lower edge (21) of a foam barrier wall and by the fact that the upper edge (24) of the foam screen (19) is designed to serve emergency overflow.   Screening grid according to claim 5 or 6, characterized in that the teeth (49) can be tilted individually around the longitudinal axis of the round bar (47).