System for cleaning equipment intended to be placed in a solid / liquid separation settler, and associated installation and method

Abstract

The system (14) comprises: - a cleaning boom (54), defining an internal cleaning fluid circulation passage (74) that opens out via at least one ejection orifice (76); - a drive shaft (50) for rotating the cleaning boom (54), extending vertically between a lower end (60) and an upper end (62), the drive shaft (50) internally defining an internal cleaning fluid circulation channel (66) fluidically connected to the internal passage (74); - a system (56) for rotating the drive shaft (50) about the axis of rotation (A-A'). The internal cleaning fluid circulation channel (66) is configured to be supplied with cleaning fluid through the lower end (60) of the drive shaft (50).

Description

[0001] DESCRIPTION

[0002] TITLE: Cleaning system for equipment intended to be placed in a solid / liquid separation decanter, associated installation and process

[0003] The present invention relates to a system for cleaning equipment intended to be placed in a solid / liquid separation decanter, the cleaning system comprising:

[0004] - a cleaning ramp, defining an internal passage for circulation of a cleaning fluid opening through at least one cleaning fluid ejection orifice;

[0005] - a rotary shaft for driving the cleaning ramp in rotation extending vertically between a lower end and an upper end, the drive shaft being rotatably mounted about a vertical axis of rotation, the cleaning ramp projecting laterally relative to the axis of rotation, the drive shaft internally defining an internal channel for circulating cleaning fluid fluidically connected to the internal passage of the cleaning ramp;

[0006] - a system for driving the drive shaft in rotation around the axis of rotation.

[0007] The cleaning device is intended in particular to be placed in a settling plant carrying out liquid / solid separation to treat water, in particular wastewater, industrial water or drinking water.

[0008] Some settling facilities include settling tanks equipped with lamellar modules, for example formed from honeycomb structures. These modules are placed in a settling basin, above the point of introduction of the water to be treated.

[0009] Lamellar modules contribute to solid-liquid separation by at least partially capturing solids to allow them to sediment, while clarified liquids can rise through the lamellar module.

[0010] Decanters equipped with lamellar modules are efficient in terms of separation, which can reduce the space occupied by the water treatment plant for a given treatment flow rate. However, they require periodic maintenance to prevent clogging.

[0011] Cleaning of lamellar modules is often carried out manually by an operator from outside the structure, in particular by high-pressure water spray.

[0012] Alternatively, EP 0 958 849 describes an automated system comprising a pressurized air cleaning ramp, provided on the underside of the lamellar modules. The use of a cleaning ramp increases the time between two manual cleaning operations by an operator and therefore contributes to reducing operating costs.

[0013] Other types of lamellar decanters are equipped with a cleaning device comprising one or more scraper arms driven in rotation by a shaft. The cleaning device is equipped with a rotating drive head composed of a drive crown, and a geared motor offset from the crown.

[0014] It is then known to provide the device with at least one unclogging ramp which is driven in rotation jointly with the scraping arms.

[0015] To supply the ramp with air, the cleaning device has an air inlet which passes through the rotating drive ring of the cleaning device shaft.

[0016] A rotating joint connects the fixed overhead pipe to a second rotating pipe placed in the drive shaft and hydraulically connected to the cleaning boom.

[0017] The cleaning ramp has calibrated orifices that allow pressurized air to escape towards the upper part of the decanter. This air detaches solids (particularly sludge) stuck to the lamellae of the lamella module. The rotation of the shaft exposes the entire lamella surface to the flow of pressurized air ejected by the ramp.

[0018] Such a cleaning device is therefore particularly effective. However, it can still be improved.

[0019] In particular, the manufacturing of the rotating drive head requires precise machining involving special tools to produce the frame in which the crown rests, and the pinion which connects the geared motor and the crown. The manufacturing cost of such a system is therefore high.

[0020] In addition, when using the drive system, the crown is immersed in several dozen liters of oil which must be kept at the correct level.

[0021] The swivel joint is also a wear part and a source of air leaks, as it is made up of bearings. It must be replaced periodically, for example every 4 to 5 years.

[0022] This generates significant operating costs, which could be reduced.

[0023] An aim of the invention is therefore to provide a cleaning device allowing frequent and effective cleaning of a decanter, in particular equipped with lamellar modules, the cleaning device being simpler to manufacture and less expensive to operate.

[0024] To this end, the invention relates to a cleaning device of the aforementioned type, characterized in that the internal cleaning fluid circulation channel is configured to be supplied with cleaning fluid through the lower end of the drive shaft.

[0025] The cleaning device according to the invention may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination:

[0026] - the cleaning system comprises an internal pipe for supplying the internal channel with cleaning fluid, fixed in rotation during rotation of the drive shaft, the internal pipe extending vertically through the drive shaft;

[0027] - the internal conduit projects downwards beyond the lower end of the drive shaft, the cleaning system comprising at least one part for closing the intermediate space defined between the internal conduit and the drive shaft positioned at the lower end of the drive shaft;

[0028] - the internal conduit extends to an upper end, and opens at its upper end or in the vicinity of its upper end;

[0029] - the point at which the internal pipe opens is located at a height of at least 250 mm, in particular at least 400 mm, above a tapping point of the internal passage in the internal cleaning fluid circulation channel;

[0030] - the internal pipe is provided at its upper end with a part for guiding the rotation of the drive shaft projecting radially towards the drive shaft, the part for guiding the rotation defining at least one axial passage through which cleaning fluid circulates;

[0031] - the drive shaft and the internal pipe define an intermediate space between them, the internal passage of the cleaning ramp opening opposite the intermediate space;

[0032] - the drive shaft has a cover, in particular a solid flange, closing the intermediate space upwards;

[0033] - the rotational drive system comprises a geared motor group arranged in the axis of rotation of the drive shaft above its upper end, the geared motor group being advantageously configured to directly drive the drive shaft without an additional reduction ratio;

[0034] - the cleaning system comprises at least one scraper arm carried by the drive shaft and projecting laterally relative to the drive shaft, the cleaning ramp being advantageously arranged in a higher position than the scraper arm, preferably above and opposite the scraper arm;

[0035] - the cleaning fluid is chosen from water or air.

[0036] The invention also relates to a decantation installation, comprising: - a solid / liquid separation decanter comprising at least one basin having a bottom;

[0037] - a cleaning system as defined above, mounted in the basin, the settling installation comprising a cleaning fluid supply pipe opening at the bottom of the basin, the supply pipe being fluidically connected to the internal channel of the drive shaft through the lower end of the drive shaft.

[0038] The installation according to the invention may include one or more of the following characteristics, taken in isolation or in any technically possible combination:

[0039] - the equipment comprises at least one lamellar module comprising a plurality of lamellas and / or hollow tubular elements arranged above the cleaning ramp;

[0040] - the decanter has a bridge crossing the basin, the bridge carrying the rotation drive system of the drive shaft.

[0041] The invention also relates to a method for cleaning a settling installation as defined above, the method comprising the following steps:

[0042] - activation of the drive shaft rotation drive system to rotate the drive shaft around its rotation axis;

[0043] - supplying the internal channel of the drive shaft with cleaning fluid through the lower end of the drive shaft;

[0044] - circulation of the cleaning fluid from the internal channel of the drive shaft through the internal passage of the cleaning ramp, and ejection of the cleaning fluid from the cleaning ramp into the basin through the or each ejection orifice.

[0045] The invention will be better understood by reading the following description, given solely by way of example, and made with reference to the appended drawings, in which:

[0046] - [Fig.1] Figure 1 is a schematic top view of a decanter of a decantation installation, equipped with a cleaning system according to the invention;

[0047] - [Fig.2] Figure 2 is a schematic view in partial section of the decanter of Figure 1;

[0048] - [Fig.3] Figure 3 is a bottom view of the drive shaft of the cleaning system according to the invention, taken along plane III of Figure 2;

[0049] - [Fig.4] Figure 4 is a view taken in partial section of the drive shaft of the cleaning system according to the invention, taken along plane IV of Figure 2.

[0050] A first settling installation 10 according to the invention is illustrated schematically by Figures 1 to 4. The installation 10 is intended to be arranged in a water treatment unit to receive wastewater, industrial water, or drinking water with a view to treating them to obtain clarified water.

[0051] With reference to figures 1 and 2, the installation 10 comprises a decanter 12, suitable for receiving water to be clarified 13, containing solids, in particular suspended matter, and liquids, to separate it into clarified water 15 having a reduced solids content and into sedimented solids 17, in particular sludge, intended to be treated.

[0052] The installation 10 further comprises a rotating cleaning system 14 for the decanter 12, and an assembly 16 for supplying cleaning fluid to the cleaning system 14, visible in FIG. 2.

[0053] With reference to figures 1 and 2, the decanter 12 comprises at least one basin 18 receiving the water to be clarified 13, and separation equipment 20 mounted in the basin 18, the equipment 20 comprising in this example at least one lamellar module 22.

[0054] The basin 18 is advantageously rectangular in outline and has a central axis A-A'. It comprises side walls 28, a bottom 24 inclined towards its center, and a mud collection pocket 26, arranged at the lowest point of the bottom 24.

[0055] The basin 18 further comprises at least one inlet 30 for water to be clarified 13, at least one outlet 32 ​​for clarified water 15, and at least one outlet 34 for discharging sedimented solids 17.

[0056] The bottom 24 here comprises at least one sloped section from the side wall 28 towards the pocket 26. The angle of inclination of the bottom 24 relative to a horizontal plane is for example between 15° and 30°.

[0057] The side walls 28 are here vertical. The side walls 28 and the bottom 24 delimit an interior volume 38 for separating the water to be clarified 13, which opens upwards into the atmosphere.

[0058] Volume 38 further opens downwards into pocket 26, to collect the sedimented solids.

[0059] The interior volume 38 is for example greater than 30 m 3 and including in particular between 20 m 3 and 2500 m 3 .

[0060] The inlet 30 of water to be clarified 13 opens laterally into a side wall 28. It is preferably located under the separation equipment 20, in particular under the lamellar modules 22.

[0061] The discharge 32 of clarified water 15 is located above the separation equipment 20, in particular above the lamellar modules 22, in particular on the surface of the basin 18. It advantageously extends opposite the inlet 30 of water to be clarified 13 relative to the axis A-A'. It comprises, for example, an overflow discharge above the side wall 28 of the basin 18.

[0062] The pocket 26 opens upwards at the lowest point of the bottom 24. It defines a volume for collecting sedimented solids. It is delimited by a lateral surface 29 having an angle of inclination relative to a horizontal plane greater than the angle of inclination of the inclined side or sides of the bottom 24 relative to the same horizontal plane.

[0063] The outlet 34 for discharging sedimented solids 17 opens at the bottom of the pocket 26. It is connected to a pump 39 for discharging the sedimented solids, for the purpose of their treatment.

[0064] The equipment 20 is arranged in the interior volume 38 of the basin 18, in the vicinity of the surface of the basin 18. It comprises at least one lamellar module 22, for example several lamellar modules 22 advantageously covering a horizontal section of the interior volume 38 around the cleaning system 14.

[0065] Each lamellar module 22 is formed from a plurality of lamellae 40, preferably inclined relative to the vertical, which delimit between them through passages 42 from a lower surface 43A of the module 22 to an upper surface 43B of the module 22.

[0066] Alternatively, the lamellar module 22 is formed from a plurality of tubular elements opening downwards into the lower surface 43A of the module 22 and upwards into the upper surface 43B of the module 22.

[0067] The internal passages 42 delimited within the lamellar module therefore constitute an obstacle for the solid elements contained in the water to be clarified 13. These are therefore preferentially maintained under the lamellar module 22. On the contrary, the clarified water 15 is able to rise and travel through the lamellar module 22.

[0068] Thus, the concentration of solids maintained under the lamellar module 22 is likely to increase, causing sedimentation of the solids towards the bottom 24 of the basin 18.

[0069] As illustrated in Figure 2, the cleaning system 14 comprises a rotating drive shaft 50, mounted vertically in the basin 18, and at least one scraper arm 52, projecting radially from the rotating shaft 50.

[0070] The cleaning system 16 further comprises at least one cleaning ramp 54 of the equipment 20, projecting radially relative to the rotary shaft 50 advantageously above and opposite a scraping arm 54, and a rotation drive system 56 of the rotary shaft 50.

[0071] According to the invention, the cleaning system 16 further comprises a system 58 for supplying cleaning fluid through a lower end 60 of the hollow shaft 50. The rotary shaft 50 extends vertically along its axis of rotation (which is here the central axis AA' of the basin 18), between the lower end 60 and an upper end 62, connected to the rotation drive system 56.

[0072] In this example, the rotary shaft 50 is formed of several segments 64A, 64B, 64C assembled end to end along the axis A-A'. Alternatively, the rotary shaft 50 is made in one piece in a single segment.

[0073] The rotating shaft 50 defines a central cleaning fluid circulation channel 66 which extends at least between the lower end 60 and an inlet of the cleaning ramp 54.

[0074] The circulation channel 66 extends here above the cleaning ramp 54, up to a cover 68 formed of a solid flange between two successive sections 64A, 64B of the rotating shaft 50.

[0075] The rotary shaft 50 is mounted to rotate about its axis AA' while being driven in rotation by the rotation drive system 56. It jointly drives in rotation the or each cleaning ramp 54, and the or each scraping arm 52.

[0076] Each scraper arm 52 projects radially from an outer surface of the rotary shaft 50. It extends radially away from the rotary shaft 50 opposite the bottom 24. It comprises scraper members (not shown), for example scraper blades, configured to scrape the solids settled on the bottom 24 and carry them towards the pocket 26.

[0077] The cleaning ramp 54 also projects radially from the outer surface of the rotating shaft 50. It is for example mounted on a radial flange 70 present on the outer surface of the rotating shaft 50.

[0078] Preferably, the cleaning boom 54 extends horizontally above a scraper arm 52, and is connected to the scraper arm 52 by members 72.

[0079] The cleaning ramp 54 defines an internal cleaning fluid circulation passage 74, fluidically connected to the circulation channel 66 and at least one cleaning fluid ejection orifice 76, preferably a plurality of cleaning fluid ejection orifices 76 distributed along its length.

[0080] The cleaning ramp 54 is here formed of a hollow tube extending perpendicular to the axis AA' and internally defining the internal passage 74.

[0081] The internal passage 74 opens radially into the internal circulation channel 76 through the flange 70.

[0082] The orifices 76 are preferably oriented upwards to extend opposite the lower surface 43A. The linear density of orifices 76 is for example greater than 5 orifices per meter. The area of ​​each orifice 76 is for example greater than 2 mm 2 and is notably between 2 mm 2 and 10 mm 2 , for example 4 mm2 .

[0083] Thus, the cleaning fluid is able to circulate along the internal passage 74, and to be ejected through the orifices 76 to rise towards the lower surface 43A of the equipment 20.

[0084] The rotational drive system 56 comprises a geared motor group 80 coupled in rotation with the rotary shaft 50.

[0085] The geared motor group 80 is carried by the bridge 36. It extends here coaxially with the axis of rotation A-A' of the rotary shaft 50. It directly drives the rotary shaft 50 in rotation. This drive is carried out by direct transmission of torque from the geared motor group 80, without being multiplied by an additional reduction ratio linked to a drive crown. The rotation drive system 56 is thus without an oil bath.

[0086] The rotating shaft 50 is driven at a speed generally between 0.03 revolutions per minute and 0.5 revolutions per minute.

[0087] The cleaning fluid supply system 58 comprises a vertical internal conduit 90, fixedly mounted in the circulation channel 66 of the rotating shaft 50, through the lower end 60 of the rotating shaft 50.

[0088] The cleaning fluid supply system 58 comprises a closing part 92 of the intermediate space 94 defined between the internal conduit 90 and the rotary shaft 50, and advantageously, a rotational guide part 96 of the rotary shaft 50.

[0089] The internal conduit 90 preferably extends along the axis of rotation A-A'. It projects downwardly beyond the lower end 60 of the rotary shaft 50, for connection to the supply assembly 16.

[0090] It extends continuously to an upper end 100 arranged above the cleaning ramp 54.

[0091] Thus, the internal conduit 90 is connected at its lower end 101 to the supply assembly 16 under the lower end 60 of the rotary shaft 50. It opens at its upper end 100 above the tapping point of the internal passage 74 of the cleaning ramp 54, and above the rotation guide part 96.

[0092] Advantageously, the point at which the internal pipe 90 opens (here the upper end 100) is located at a height (taken along the axis A-A') at least 250 mm higher, in particular at least 400 mm, above the tapping point of the internal passage 74, for example 500 mm above the tapping point of the internal passage 74.

[0093] In the example shown in Figure 2, the height of the internal conduit 90, taken from the lower end 60 of the rotary shaft 50 to the upper end 100, is greater than 30% of the height of the rotary shaft 50, taken between its lower end 60 and its upper end 62. This height is preferably between 30% and 50% of the height of the rotary shaft 50.

[0094] The closing part 92 is visible in Figure 3, seen from below. It closes downwards the intermediate space 94 defined between the internal conduit 90 and the rotary shaft 50 within the internal channel 66. It is here formed by a plurality of shells 102, for example by two half-shells 102 extending around the internal conduit 90 up to the internal surface of the rotary shaft 50.

[0095] With reference to Figure 4, the rotation guide part 96 is mounted in the vicinity of the upper end 100 of the internal conduit 90. It has a plurality of guide fingers 104, delimiting between them at least one through passage 106 for axial circulation of the cleaning fluid.

[0096] In this example, the number of circulation passages 106 is equal to the number of fingers 104. The number of fingers is for example greater than two, and is in particular between two and five, for example three in the example of figure 4.

[0097] Each finger 104 has an outer surface 108, of a shape complementary to the inner surface of the rotating shaft 50 delimiting the internal channel 66.

[0098] Thus, the rotation of the rotary shaft 50 around its axis AA' is guided at the level of the closing part 92 by cooperation between the periphery of the shells 102 and the internal surface of the rotary shaft 50. It is guided at the level of the upper end 100 of the internal conduit 90 by the fingers 104.

[0099] The cleaning fluid is preferably a gas, in particular under pressure, at a pressure greater than 100 mbar and between 100 mbar and 1000 mbar. The gas is, for example, air.

[0100] The cleaning fluid is thus able to travel successively from bottom to top through the internal conduit 90 from its lower end 101 to the upper end 100, then to pass into the intermediate space 94 between the rotating guide part 96 and the cover 68, before descending via the transverse passages 106 towards the internal passage 74 of the cleaning ramp to the cleaning fluid ejection orifices 76.

[0101] The supply assembly 16 comprises at least one fluid supply pipe 110, arranged in the masonry at the foot of the basin 18. It comprises a vertical tapping 112, extending along the axis AA' in the pocket 26 for the connection of the lower end 101 of the internal pipe 90.

[0102] The operation of the settling plant 10 will now be described. Initially, water to be clarified 31 is advantageously supplied continuously into the interior volume 38 of the basin 18 through the inlet 13 of water to be clarified 31 located under the separation equipment 20.

[0103] As indicated previously, at least a portion of the solids contained in the water to be clarified 31, in particular the suspended matter, are retained below the or each lamellar module 22 of the separation equipment 20. On the contrary, the clarified water 15 rises through the interior passages 42 between the lamellae 40 and is continuously evacuated via the clarified water 15 evacuation 32.

[0104] The solids retained under the separation equipment sediment and gradually settle on the bottom 24.

[0105] The rotary shaft 50 is driven in rotation around the axis A-A', intermittently or continuously, by activation of the geared motor group 80.

[0106] This causes the joint rotation of the or each scraping arm 52 which scrapes the sedimented solids deposited at the bottom 24 to carry them towards the pocket 26.

[0107] The pocket 26 collects the sedimented solids 17, which are discharged intermittently or continuously through the discharge outlet 34.

[0108] In some cases, solid residues accumulate on the lower surface 43A of the equipment 20, in particular at the entrance to the interior passages 42 defined between the slats 40, partially or totally blocking these passages 42.

[0109] To overcome this problem, cleaning fluid is supplied from the pipe 110 through the tapping 112, to the internal pipe 90.

[0110] The cleaning fluid successively travels upwards through the lower end 60 of the drive shaft 50 in the internal conduit 90 to the upper end 100 of the internal conduit 90, then passes into the intermediate space 94 between the rotating guide part 96 and the cover 68, before descending via the transverse passages 106 towards the internal passage 74 of the cleaning ramp 54. It then circulates to the cleaning fluid ejection orifices 76.

[0111] The fluid ejected through the orifices 76, particularly in the form of gas bubbles, creates local turbulence under the lower surface 43A of each module 22 of the equipment 20, cleaning the lower surface 43A. Thus, the internal passages are unclogged and the decanter 12 operates with maximum efficiency.

[0112] The or each cleaning ramp 54 is driven in rotation around the axis AA' by the movement of the rotary shaft 50 around the same axis A-A', produced by the geared motor group 80.

[0113] This rotational drive does not interfere with the injection of cleaning fluid to supply the cleaning ramp 54. This injection is carried out according to the invention through the lower end 60 of the rotating shaft 50, without having to provide a rotating joint within the rotational drive system 56 or in the rotating shaft 50.

[0114] Indeed, the internal pipe 90 being fixed in rotation and opening into the circulation channel 66 present in the rotating shaft 50, the injection of fluid is direct and is directed towards the cleaning ramp 54.

[0115] In addition, cleaning fluid remains permanently trapped in the circulation channel 66, which keeps the internal pipe 90 clear of water. This prevents the internal pipe 90 from clogging with water to be clarified 13.

[0116] Furthermore, the cleaning fluid is advantageously supplied by a buried network to supply the internal pipe 90 inserted in the rotating shaft 50, which limits the size of the installation 10 and simplifies the utility networks.

[0117] All these measures greatly simplify the manufacture of the rotary shaft 50 and its rotation drive system 56, making it possible to completely eliminate the use of a drive ring and a rotating joint. No wear part is then present at the level of the rotation drive of the rotary shaft 50, which limits the maintenance to be carried out and reduces operating costs.

[0118] Furthermore, the design of the rotational drive system 56 is facilitated, thanks to the alignment of the rotational drive system 56 with the rotation axis A-A' of the rotary shaft 50.

[0119] In one variant (not shown), the rotating shaft 50 remains driven at its periphery by a geared motor. However, the injection of cleaning fluid is carried out by a cleaning fluid supply system 58 similar to that described above.

Claims

CLAIMS 1. Cleaning system (14) for equipment (20) intended to be placed in a solid / liquid separation decanter (12), the cleaning system (14) comprising: - a cleaning ramp (54), defining an internal passage (74) for circulation of a cleaning fluid opening through at least one orifice (76) for ejecting cleaning fluid; - a rotary drive shaft (50) for rotating the cleaning ramp (54), extending vertically between a lower end (60) and an upper end (62), the drive shaft (50) being rotatably mounted about a vertical axis of rotation (A-A'), the cleaning ramp (54) projecting laterally relative to the axis of rotation (A-A'), the drive shaft (50) internally defining an internal channel (66) for circulating cleaning fluid fluidically connected to the internal passage (74) of the cleaning ramp (54); - a system for driving the drive shaft (50) in rotation about the axis of rotation (A-A'); characterized in that the internal channel (66) for circulating cleaning fluid is configured to be supplied with cleaning fluid through the lower end (60) of the drive shaft (50).

2. Cleaning system (14) according to claim 1, comprising an internal conduit (90) for supplying the internal channel with cleaning fluid, fixed in rotation during rotation of the drive shaft (50), the internal conduit (90) extending vertically through the drive shaft (50).

3. Cleaning system (14) according to claim 2, wherein the internal conduit (90) projects downwardly beyond the lower end (60) of the drive shaft (50), the cleaning system (14) comprising at least one closing part (92) of the intermediate space (94) defined between the internal conduit (90) and the drive shaft (50) positioned at the lower end (60) of the drive shaft (50).

4. Cleaning system (14) according to any one of claims 2 to 3, in which the internal conduit (90) extends to an upper end (100), and opens at its upper end (100) or in the vicinity of its upper end (100).

5. Cleaning system (14) according to claim 4 wherein the point at which the internal conduit (90) opens is located at a height greater than at least 250 mm, in particular at least 400 mm, above a tapping point of the internal passage (74) in the internal channel (66) for circulating cleaning fluid.

6. Cleaning system (14) according to any one of claims 2 to 5, in which the internal conduit (90) is provided at its upper end (100) with a rotation guide part (96) of the drive shaft (50) projecting radially towards the drive shaft (50), the rotation guide part (96) defining at least one axial through passage (106) for circulation of cleaning fluid.

7. Cleaning system (14) according to any one of claims 2 to 6, in which the drive shaft (50) and the internal conduit (90) define between them an intermediate space (94), the internal passage (74) of the cleaning ramp (54) opening opposite the intermediate space (94).

8. Cleaning system (14) according to claim 7, wherein the drive shaft (50) comprises a cover (68), in particular a solid flange, closing the intermediate space (94) upwards.

9. Cleaning system (14) according to any one of the preceding claims, in which the rotational drive system (56) comprises a geared motor group (80) arranged in the axis of rotation (A-A') of the drive shaft (50) above its upper end (62), the geared motor group (80) being advantageously configured to directly drive the drive shaft (50) without an additional reduction ratio.

10. Cleaning system (14) according to any one of the preceding claims, comprising at least one scraper arm (52) carried by the drive shaft (50) and projecting laterally relative to the drive shaft (50), the cleaning ramp (54) being advantageously arranged in a higher position than the scraper arm (52), preferably above and opposite the scraper arm (52).

11. Cleaning system (14) according to any one of the preceding claims, wherein the cleaning fluid is selected from water or air.

12. Settling installation (10), comprising: - a solid / liquid separation decanter (12) comprising at least one basin (18) having a bottom (24); - a cleaning system (14) according to any one of the preceding claims, mounted in the basin (18), the settling installation (10) comprising a pipe (110) for supplying cleaning fluid opening at the bottom of the basin (18), the supply pipe (110) being fluidically connected to the internal channel (66) of the drive shaft (50) through the lower end (60) of the drive shaft (50).

13. Settling installation (10) according to claim 12, in which the equipment (20) comprises at least one lamellar module (22) comprising a plurality of lamellae (40) and / or hollow tubular elements arranged above the cleaning ramp (54).

14. Settling installation (10) according to any one of claims 12 or 13, in which the decanter (12) comprises a bridge (36) crossing the basin (18), the bridge (36) carrying the rotational drive system (56) of the drive shaft (50).

15. Method for cleaning a settling installation (10) according to any one of claims 12 to 14 comprising the following steps: - activation of the rotation drive system (56) of the drive shaft (50) to rotate the drive shaft (50) around its axis of rotation (A- A'); - supplying the internal channel (66) of the drive shaft (50) with cleaning fluid through the lower end (60) of the drive shaft (50); - circulation of the cleaning fluid from the internal channel (66) of the drive shaft (50) through the internal passage (74) of the cleaning ramp (54), and ejection of the cleaning fluid from the cleaning ramp (54) into the basin (18) through the or each ejection orifice (76).

Images