Plate filter

Abstract

The present invention relates to a filter (10) comprising a tank (12) which extends along a main axis (A1) and filtration plates (24) arranged parallel to the main axis (A1) and disposed in a star shape in a receiving volume (22) of the tank (12), each of the filtration plates (24) comprising at least one filtering element (34) connected to a collection pipe, the filter (10) comprising an external manifold (28), each of the collection pipes (36) comprising an end portion which extends in the receiving volume (22) of the tank (12) along a secondary axis, parallel to the main axis (A1), the end portion of each of the collection pipes being fluidically connected to the external manifold (28) by a through-channel formed in the main wall (20) of the tank (12), each channel extending through the main wall (20) along the secondary axis.

Description

[0001] DESCRIPTION

[0002] TITLE: TABLET FILTER

[0003] Technical field of the invention

[0004] The present invention relates to a pressure filter with vertical filtration plates having a device for rapid handling of all the plates.

[0005] Technical background

[0006] Among the devices used for the industrial-scale liquid / solid separation of a slurry, there are, in particular, cylindrical pressure filters, also known as "tanks," whose filter plates are arranged vertically. These filter plates comprise one or more filter elements. These filter plates are arranged either parallel to each other or radially around the center of the tank. The first arrangement is called "parallel"; the second is called "star." These plates, whose filter element(s) are covered with a filter medium, generally a fabric, are equipped with a collection tube connected to an external collector for draining the filtered liquid, known as the "filtrate."

[0007] While such filters offer satisfactory filtration efficiency, they are nonetheless complex to install and maintain. Indeed, using these filters requires regular replacement of the filter media in the filter trays to maintain optimal filtration performance. This necessitates removing the filter trays from the tank to replace their filter media.

[0008] Furthermore, on current filters, the connection of the collection tubing to the external collector is made through the tank along a radial axis relative to a main axis of the tank. Therefore, moving the filter plates inside or outside the tank requires several steps, including a radial translation of each collection tube to detach it from the tank, followed by an axial movement towards the outside of the tank. These steps must be performed manually for each filter plate.

[0009] Thus, such manipulations are time-consuming and in the case where the filter is used to separate toxic compounds, the handling of the filtration trays can present a significant health risk for the operator in charge of maintenance.

[0010] Thus, current filters present maintenance that is complex, time-consuming and potentially dangerous for the operator.

[0011] The invention therefore aims to solve the aforementioned problems by providing a filter whose installation or removal of the filter plates in the tank is quick, efficient and safer for the operator.

[0012] Summary of the invention

[0013] The invention proposes a filter comprising at least one tank extending along a main axis and filter plates arranged parallel to the main axis and disposed within a receiving volume delimited by a main wall of the tank, the filter plates being arranged in a star pattern within the receiving volume of the tank, each of the filter plates comprising at least one filter element fluidly connected by one of its axial ends to a collection tube, the filter comprising at least one external collector extending along an external face of the main wall and outside the receiving volume of the tank, each of the collection tubes comprising an end section extending within the receiving volume of the tank along a secondary axis, parallel to the main axis,the end section of each of the collection pipes being fluidly connected to the external collector by at least one through channel formed in the main wall of the tank, each channel extending through the main wall along the secondary axis.

[0014] According to other features of the invention: - the main wall includes a shoulder which extends radially with respect to the main axis, each channel extending through the shoulder;

[0015] - the end section of each of the collection tubes includes a collar which extends radially along an external periphery of the end section relative to the secondary axis, with at least one centering device being interposed axially between each collar and each channel;

[0016] - each of the centering devices includes at least one end fitting on the outer periphery of the end section, the end fitting including a free end having a conical centering surface;

[0017] - each of the centering devices includes a tip receiving device which extends at least partly into each channel, the receiving device comprising a through orifice delimited by an internal wall, the internal wall being at least partly conical so as to form a receiving surface for the tip centering surface;

[0018] - each of the centering devices includes at least one circular seal mounted around the tip, the seal comprising at least two compression surfaces which extend in a plane intersecting the secondary axis;

[0019] - the entire set of filtration trays is attached to a common lifting frame which extends over said filtration trays, in the receiving volume of the tank;

[0020] - the filtration trays are each attached to the lifting frame via their collection tubing; the lifting frame has a circular shape whose axis of revolution is coaxial with the main axis of the tank;

[0021] - the axial support of the filter trays in the tank is ensured by the lifting frame and by the axial contact of the end section of each of the collection tubes on the shoulder of the tank; - the tank includes at least one central conduit which extends along the main axis of the tank, the central conduit including axial guiding means capable of cooperating with complementary guiding elements carried by the lifting frame;

[0022] - the guiding elements of the lifting frame are rods which extend parallel to the main axis, the axial guiding means taking the form of grooves formed on the periphery of the central conduit and intended to house at least part of the rods;

[0023] - a control conduit extends outside the receiving volume of the tank, between each channel and the external collector, each control conduit including a fluid passage control device;

[0024] - the filter includes double trays comprising at least two filter elements fluidly connected to the same collection tubing and single trays comprising a single filter element fluidly connected to a collection tubing, the single trays each extending between two double trays.

[0025] Brief description of the figures

[0026] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0027] [Fig. 1] is a perspective and cut-out view of a filter according to an example of the invention comprising a tank housing filter trays attached to a lifting frame;

[0028] [Fig.2] is an axial cross-sectional view of the filter tank in Figure 1;

[0029] [Fig.3] is an exploded view of the tank and filter trays carried by the filter lifting frame of Figure 1;

[0030] [Fig. 4] is a detail view of an end section of a collection tube of one of the filter trays of the filter of Figure 1, the end section comprising a centering device according to a first example of the invention, the end section being arranged opposite a channel formed in a shoulder of the tank;

[0031] [Fig.5] is a detail view of the end section of a collection tube of one of the filter trays of the filter of figure 1 comprising a centering device according to a second example of the invention;

[0032] [Fig.6] is a detailed view of the end section of figure 5 cooperating fluidly with the channel formed in the shoulder of the tank;

[0033] [Fig.7] is a schematic top view of the filter lifting armature of Figure 1.

[0034] Detailed description of the invention

[0035] For the description of the invention and the understanding of the claims, the vertical, longitudinal and transverse orientations according to the V, L, T frame indicated in the figures, whose longitudinal L and transverse T axes extend in a horizontal plane, will be adopted without limitation and without limiting reference to terrestrial gravity.

[0036] In the description that follows, identical, similar or analogous elements will be designated by the same reference numbers.

[0037] Figure 1 illustrates a filter 10 according to an example of the invention, here a filter 10 with vertical pressure-bearing filter plates for the liquid / solid separation of a loaded suspension.

[0038] It should be considered that initially a structural description of filter 10 will be proposed, then a functional description of the elements of filter 10 will be proposed.

[0039] The filter 10 comprises a cylindrical tank 12 extending along a main axis A1 with a conical lower bottom 14, a domed removable cover 16 and a substantially cylindrical central portion 18.

[0040] According to the example of the invention illustrated, the main axis A1 is here a vertical axis, considering terrestrial gravity.

[0041] Tank 12 includes in particular a main wall 20 which delimits a receiving volume 22 of the filtration trays 24.

[0042] In the illustrated example of the invention, the receiving volume 22 of the filter trays 24 extends essentially between the conical lower bottom 14 and the domed removable lid 16. In other words, the receiving volume 22 of the filter trays 24 extends mainly within the cylindrical central portion 18 of the tank 12.

[0043] As can be seen in figures 2 and 5, the main wall 20 of the tank 12 includes a shoulder 26 which extends radially with respect to the main axis A1 of the tank 12.

[0044] More specifically, the central portion 18 of the tank 12 comprises a first cylinder C1 of a first diameter and a second cylinder C2 of a second diameter strictly greater than the first diameter, the diameters being considered along the main axis A1 of the tank 12. The second cylinder C2 is defined in particular as being in contact with the lid 16.

[0045] Shoulder 26 then forms an intercalary wall which extends here and in a non-limiting way in a plane P, visible in figure 4, perpendicular to the main axis of the tank and in such a way that it connects the first cylinder C1 and the second cylinder C2 to each other as seen in figure 2.

[0046] It is also understood that the removable domed lid 16 includes a base with a diameter identical to the second diameter of the second cylinder C2.

[0047] Tank 12 then has a mushroom shape, particularly visible in figure 2.

[0048] The filter 10 also includes an external collector 28 which extends along an external face 30 of the main wall 20 of the tank 12, and outside the receiving volume 22 of the tank 12. More precisely, and without limitation, the external collector 28 here takes the form of a torus which extends around the central portion 18 of the tank 12. Even more precisely, the external collector 28 extends opposite the shoulder 26 of the tank 12.

[0049] In relation to Figures 1 and 2, the tank 12 comprises three concentric central conduits 32 extending along the main axis A1 of the tank 12. The term "concentric" means that the three central conduits 32 have decreasing diameters such that they fit together. Three outlets, each fluidically connected to one of the central conduits 32, then extend through the conical lower bottom 14 of the tank 12.

[0050] The operation of such central conduits 32 will not be detailed here, however, as they are not the subject of the invention.

[0051] Visible in figures 1 and 3, the filter trays 24 are suspended axially in the tank 12, i.e. parallel to the main axis A1, and are arranged in the receiving volume 22 delimited by the main wall 20.

[0052] In the illustrated example of the invention and without limitation, the filter trays 24 are arranged radially in a star shape around the main axis A1 of the tank 12.

[0053] Each of the filtration trays 24 includes at least one filter element 34 fluidically connected by one of its axial ends to a collection tube 36.

[0054] We identify simple trays 24a comprising a single filter element 34 connected to its collection tube 36 and double trays 24b comprising two filter elements 34 connected to the same collection tube 36.

[0055] Here, the single trays 24a extend radially between two double trays 24b. In other words, the single trays 24a and the double trays 24b are arranged alternately around the main axis A1 of the tank 12.

[0056] Each filter element 34 of the single trays 24a and of the double trays 24b includes at least one drain, not visible, and a cloth 38 which covers the drain(s).

[0057] The collection pipe 36 of each of the filter trays 24 comprises a main section 40, partially visible in Figures 4 to 6, which extends radially with respect to the main axis of the tank. The main section 40 of each of the collection pipes 36 is specifically configured to be integral with the filter element(s) 34 of the filter tray 24, visible in Figures 1 and 3.

[0058] More precisely, the drain(s) of each of the filter elements 34 are configured to fit, at one of their axial ends, into concealed openings in the main section 40 of its associated collection tube 36. A sealing profile, extending from the fabric, then covers the connection between the drains and the main section of the collection tube, and a ring associated with a clamping system locks the filter element in position in fluidic connection with the main section of the collection tube.

[0059] Furthermore, each of the collection pipes 36 includes an end section 42, visible in figures 4 to 6, which extends along a secondary axis A2, parallel to the main axis of the tank.

[0060] It should be noted that in the following description, only the structural and functional characteristics of a single collection tube 36 will be detailed, but it will be understood that these characteristics apply mutatis mutandis to all the collection tubes 36 of the filter 10.

[0061] It is understood from the above that a radial end of the collection tubing 36 takes the form of an elbow such that the end section 42 extends along the second axis A2, that is to say perpendicular to the main section 40 of the collection tubing 36.

[0062] Furthermore, and visible in figure 5, the radial end of the collection pipe 36 comprising the end section 42 is the radial end of the collection pipe 36 which extends in the vicinity of the main wall 20 of the tank 12. More precisely, the end section 42 of the collection pipe 36 extends into the receiving volume 22 of the tank 12 in such a way that it is axially aligned with the shoulder 26 of the latter along the secondary axis A2.

[0063] Thus and as can be seen in Figure 6, the end section 42 is fluidly connected to the external collector 28, shown in Figure 5, by at least one through channel 44, formed in the main wall 20 of the tank 12, here formed in the shoulder 26 of the tank 12. In particular, the channel 44 extends in the shoulder 26 along the secondary axis A2.

[0064] According to the example of the invention illustrated in figure 5, a control conduit 46 extends outside the receiving volume 22 of the tank 12, between the channel 44 formed in the shoulder 26 and the external collector 28 in such a way as to ensure the fluidic connection between the end section 42 and the external collector 28 of the tank 12. It is understood that the external collector 28 includes a connecting opening 48, oriented towards the channel 44, the control conduit 46 being connected to the connecting opening 48 and to the channel 44.

[0065] According to the illustrated example of the invention, the control conduit 46 includes a fluid flow control element 50, for example a valve. The fluid flow control element 50 can then switch between an open position that allows fluid flow between the channel 44 and the external manifold 28 and a closed position that blocks fluid flow between them.

[0066] In addition, the control conduit 46 may include a transparent portion allowing visual control of the fluid flowing within the control conduit 46.

[0067] It is then understood that each end section 42 of each of the collection tubes 36 of the filter is fluidically connected to a channel 44 and to a control conduit 46. We thus take advantage of such a configuration of the filter in that the control conduits 46 associated with each of the end sections 42, and therefore with each filtration tray 24, allow individual control of each of the filtration trays 24.

[0068] As particularly visible in Figure 4, the end section 42 of each of the collection tubes 36 includes a collar 52 which extends radially along the outer periphery of the end section 42, relative to the secondary axis A2. The collar 52 extends in particular around the end section 42 at a non-zero axial distance from the free end of the end section 42 such as to leave a cylindrical space around the free end of the end section 42.

[0069] According to the example of the invention illustrated in figure 4, a centering device 54 is interposed axially between the collar 52 and the channel 44. More precisely, the centering device 54 extends mainly at the level of the cylindrical space described above.

[0070] The centering device 54 includes an end piece 56 fitted onto the outer periphery of the end section 42. The end piece 56 is fitted onto the end section 42 such that it bears axially against the flange 52. It is understood that the end piece 56 is press-fitted around the outer periphery of the end section 42 until it comes into axial contact with the flange 52.

[0071] The tip 56 can thus include a bearing surface 58 which extends radially and is in contact with the collar 52 of the end section 42.

[0072] The end piece 56 also includes a free end having a conical centering surface 60 to facilitate axial insertion guidance of the end section 42 in the channel 44, along the secondary axis A2. Such an assembly will be detailed later in the description.

[0073] Thus, according to the example of the invention illustrated in figure 4, an edge 62 of the channel 44 has a chamfered profile, complementary to the conical centering surface 60 of the tip 56.

[0074] According to another embodiment of the invention, visible in Figures 5 and 6, the centering device 54 comprises a receiving device 64 for the tip 56 which extends at least partially into each channel 44. More specifically, the receiving device 64 extends along the secondary axis A2 and comprises an internal wall 66 which defines a through orifice 68. The through orifice 68 then extends at least partially into the channel 44.

[0075] The internal wall 66 of the receiving device 64 includes at least one conical part such as to form a receiving surface 70 complementary to the conical centering surface 60 of the free end of the nozzle 56.

[0076] Furthermore, the centering device 54 includes at least one circular seal 72 mounted around the nozzle 56. It is understood that the seal 72 comprises two compression surfaces 74, axially opposed to each other and extending in a plane intersecting the secondary axis A2. In other words, it is understood that the seal 72 comprises a first compression surface 74a in axial contact with the bearing surface 58 of the nozzle 56 and a second compression surface 74b in contact either with the edge 62 of the channel 44 according to the embodiment shown in Figure 4, or in contact with the receiving device 64 of the nozzle 56 according to the embodiment shown in Figures 5 and 6. The centering device according to the examples of the invention in Figures 4 to 6 may, without limitation, be made of a plastic material.

[0077] The centering device 54 is thus advantageous according to either embodiment of figures 4 to 6 in that it allows the end section 42 and possibly the channel 44 to be mechanically protected during its axial insertion into the channel 44. In other words, the centering device 54 can be changed if it is damaged and thus represents a lower cost compared to cases of wear of the end section 42 or the channel 44 of the tank which would require their repair.

[0078] As seen in Figure 1, the set of filter trays 24 is attached to a common lifting frame 76 which extends over the filter trays 24, in the volume of the tank 12. More particularly, the lifting frame 76 extends in the volume of the tank 12, between the collection tubes 36 of the filter trays 24 and the domed lid 16 of the tank 12.

[0079] The lifting frame 76, schematically visible in figure 7, has in particular a circular shape whose axis of revolution R is coaxial with the main axis A1 of the tank 12. In particular, a central portion 78 of the lifting frame 76 is defined as taking the form of a cylinder and a peripheral portion 80 as taking the form of a cylinder, the central portion 78 and the peripheral portion 80 being concentric.

[0080] In particular, the peripheral portion 80 is configured to extend to the vicinity of the shoulder 26 of the tank 12.

[0081] Main arms 82 then extend radially between the central portion 78 and the peripheral portion 80 of the lifting frame 76, connecting them. Intermediate arms 84 also extend between the main arms 82, connecting them.

[0082] Each of the filter trays 24 is attached to the lifting frame 76 via its collection tube 36. To this end, the collection tubes 36 include fastening means, not visible here, complementary to fastening elements 77 attached to the lifting frame 76, visible in figures 4 to 6. For example and without limitation, the fastening elements 77 may be rails allowing on the one hand the radial sliding of the collection tubes 36, for example during the maintenance operation of the filter trays 24, and on the other hand the locking in position of said collection tubes 36 once the maintenance of the filter trays 24 has been carried out.

[0083] Furthermore, it should be considered that each of the collection pipes 36 is integral with the lifting frame 76 in such a way that its end section 42 is positioned opposite its associated channel 44, along the secondary axis A2.

[0084] Furthermore, as shown in Figures 1 and 3, the lifting frame 76 includes guide elements 86 which extend axially from the central portion 78, along the main axis A1. The guide elements 86 take the form of rods which extend axially into the receiving volume 22 of the tank 12.

[0085] The rods forming the guide elements 86 are then configured so that they extend from the central portion 78 of the lifting frame 76 and at least axially beyond the filter trays 24.

[0086] Such a configuration of the guide elements 86, here in the form of rods, of the lifting frame 76 is advantageous in the maintenance process of the filter 10 which will be described later in the detailed description.

[0087] The central conduits 32 of the tank 12 mentioned previously, and in particular the outermost radially central conduit 32, include axial guide means 88 capable of cooperating with the guide elements 86 carried by the lifting frame 76.

[0088] According to the illustrated example of the invention, the axial guide means 88 take the form of grooves 88 formed on the periphery of the central conduit 32 and configured to house at least in part the rods of the lifting frame 76.

[0089] It is understood from the preceding description that the filter trays 24 are held radially in the tank 12 by their connection with the lifting frame 76. It is also understood that the filter trays 24 are held axially in the tank 12 at least in part by the axial contact of the end sections 42 of the collection tubes 36 on the shoulder 26 of the tank 12 as described previously.

[0090] Also, the axial support of the filter trays 24 in the tank 12 is ensured by the connection of the filter trays 24 with the lifting frame 76.

[0091] Such a configuration of the tank 12 is particularly advantageous in that the weight of the filter trays 24 and the lifting frame 76 against the shoulder 26 contributes to the sealing between the end sections 42 of the collection pipes 36 and the channels 44 by exerting axial pressure on the seals 72 of the centering devices 54 mentioned previously.

[0092] The operating procedure of filter 10 and its maintenance procedure will now be described in detail in the following description using figures 1 to 7.

[0093] The operating process of filter 10 is particularly notable for two phases called the filtration phase and the debating phase.

[0094] During the filtration phase, the filter tank 12 of the filter 10 is filled with the suspension to be filtered. The tank 12 is then pressurized while the filter trays 24, via their collection tubing 36, are depressurized. The liquid phase of the suspension then passes through the meshes 38 of the filter elements 34, and the solid phase remains on the surface of said meshes 38, forming a cake. Specifically, the liquid phase passes through the meshes and then into the collection tubing 36 to reach the external collector 28 via the control conduit 46. During the filtration phase, the meshes 38 are pressed against the drains of the filter element 34.

[0095] Furthermore, during the filtration phase, the pressure applied in the tank 12 helps to reinforce the compression of the seals 72 of the centering devices 54, at the level of their compression surfaces 74, thus improving the seal between the collection tubes 36 and the channels 44 formed in the shoulder 26 of the tank 12. The filtration phase stops when the resistance of the cakes to the flow of the liquid becomes too great.

[0096] At this stage, the cakes must then be detached from the canvases 38, this is the debating phase.

[0097] Several debasing processes can be implemented, for example, a debasing process using a counter-current flow of the filtrate. Most often, the filtrate used is stored during the filtration phase in a vessel, called a "blowing vessel," located above the filter. During the debasing phase, the filtrate is returned by gravity alone to all the filter elements 34 of the filter 10, after the tank 12 of said filter 10 has been vented to the atmosphere.

[0098] Once detached from their filtering element 34, the cakes settle within the suspension between the trays, to the bottom of the tank 12, before being extracted.

[0099] The operating procedure of the filter 10 can be implemented several times. However, in order to maintain optimal filtration performance, it is necessary to regularly replace the filter cloths 38. It is then necessary to remove the filter trays 24 from the tank 12 to allow an operator to remove the cloths 38 from the filter elements 34.

[0100] The filter 10 according to the invention is therefore advantageous in several structural aspects.

[0101] On the one hand, the lifting frame 76 carrying all the filter trays 24, the extraction of said filter trays 24 out of the tank 12 is feasible in one go.

[0102] Furthermore, since the lifting frame 76 is integrated into the receiving volume 22 of the tank 12, no manipulation of linking the filter trays 24 with the lifting frame 76 is necessary by the operator, the latter only having to secure the lifting frame 76 to an external lifting means, for example an overhead crane.

[0103] On the other hand, the particular structure of the watertight connection between the end sections 42 of the collection pipes 36 and the channels 44 formed in the shoulder 26 of the tank 12, along the secondary axis A2 parallel to the main axis A1 of the tank 12, allows the filtration trays 24 attached to the lifting frame 76 to be extracted along this same main axis A1 of the tank 12.

[0104] Moreover, the sealing between the end sections 42 of the collection tubes 36 and the channels 44 being operated solely by the weight of the lifting frame 76, the filter trays 24 and their collection tubes 36, pressing axially on the shoulder 26 of the tank 12, no disengagement operation between the collection tubes 36 and the channels 44 is necessary.

[0105] It is then understood that the structure of the filter 10 makes it possible to reduce the handling by an operator, necessary to extract the filter trays 24 out of the tank 12, thus reducing the associated health risks while reducing the time required for this operation.

[0106] Thus, once the lifting frame 76 has been extracted axially out of the tank 12, the filter trays 24 can be maintained, in particular by changing their fabric 38.

[0107] Once this operation of changing the canvases 38 has been carried out, the lifting frame 76 carrying the filter trays 24 can be reintroduced into the tank 12.

[0108] To do this, the lifting frame 76 carrying the filter trays 24 is placed axially above the receiving volume 22 of the tank 12 as illustrated in figure 3 and in such a way that the free ends of the rods are outside the tank 12.

[0109] We can then understand the advantage of the configuration of the rods, forming the guide elements 86, which extend axially beyond the filter plates 24, in that it allows visual control of the positioning of the rods in relation to the grooves 88 carried by the central conduit 32 of the tank 12.

[0110] In other words, when repositioning the lifting frame 76 carrying the filter trays 24 in the tank 12, the angular position of the rods relative to the grooves 88 is ensured so that they cooperate with each other during the axial movement of the lifting frame 76 towards the receiving volume 22 of the tank 12. It is then understood that the angular position of the rods relative to the grooves 88 also ensures the angular position of the end sections 42 of the collection tubes 36 relative to the channels 44 formed in the shoulder 26.

[0111] Thus, the positioning of the rods in the grooves 88 ensures the positioning of the end sections 42 of each of the collection tubes 36 in their associated channel 44, the centering device 54 as described previously also helping to facilitate the insertion of the end sections 42 into the channels 44.

[0112] The weight of the lifting frame 76 and the filter trays 24 coupled to the collection tubes 36 subsequently ensure the seal between the end sections 42 and the channels 44, as described previously, and no sealing operation is required by the operator.

[0113] It is then understood that during the maintenance process of the filter 10, the particular configuration of the latter, and in particular the axial cooperation between the end sections 42 of the collection tubes 36 and the channels 44 makes it possible to simplify the repositioning of the filter trays 24 in the tank 12, this operation being carried out in one go thanks to the lifting frame 76 carrying said filter trays 24.

[0114] Moreover, since the lifting frame 76 is configured to remain in the receiving volume 22 of the tank 12, once the filter trays 24 are positioned in it, no additional operation to detach the filter trays 24 from the lifting frame 76 is necessary.

Claims

DEMANDS 1. A filter (10) comprising at least one tank (12) extending along a main axis (A1) and filter trays (24) arranged parallel to the main axis (A1) and disposed within a receiving volume (22) delimited by a main wall (20) of the tank (12), the filter trays (24) being arranged in a star pattern within the receiving volume (22) of the tank (12), each of the filter trays (24) comprising at least one filter element (34) fluidically connected by one of its axial ends to a collection pipe (36), the filter (10) comprising at least one external collector (28) extending along an external face (30) of the main wall (20) and outside the receiving volume (22) of the tank (12), each of the collection pipes (36) comprising an end section (42) extending into the receiving volume (22) of the tank (12) along a secondary axis (A2), parallel to the main axis (A1),the end section (42) of each of the collection pipes (36) being fluidly connected to the external collector (28) by at least one through channel (44) formed in the main wall (20) of the tank (12), each channel (44) extending through the main wall (20) along the secondary axis (A2).

2. Filter (10) according to the preceding claim, in which the main wall (20) comprises a shoulder (26) which extends radially with respect to the main axis (A1), each channel (44) extending through the shoulder (26).

3. A filter (10) according to any one of the preceding claims, wherein the end section (42) of each of the collection tubes (36) comprises a flange (52) extending radially along an outer periphery of the end section (42) relative to the secondary axis (A2), at least one centering device (54) being axially interposed between each flange (52) and each channel (44).

4. Filter (10) according to the preceding claim, in which each of the centering devices (54) comprises at least one tip (56) fitted onto the outer periphery of the end section (42), the tip (56) comprising a free end having a conical centering surface (60).

5. Filter (10) according to the preceding claim, wherein each of the centering devices (54) comprises a receiving device (64) for the tip (56) which extends at least partially into each channel (44), the receiving device (64) comprising a through orifice (68) delimited by an internal wall (66), the internal wall (66) being at least partially conical so as to form a receiving surface (70) for the centering surface (60) of the tip (56).

6. Filter (10) according to any one of claims 4 or 5, wherein each of the centering devices (54) comprises at least one circular seal (72) mounted around the nozzle (56), the seal (72) comprising at least two compression surfaces (74, 74a, 74b) which extend in a plane intersecting the secondary axis (A2).

7. Filter (10) according to any one of the preceding claims, wherein the set of filter plates (24) is integral with a common lifting frame (76) which extends over the said filter plates (24), in the receiving volume (22) of the tank (12).

8. Filter (10) according to the preceding claim, in which the filter trays (24) are each integral with the lifting frame (76) via their collection tube (36).

9. Filter (10) according to any one of claim 7 or 8, wherein the lifting frame (76) has a circular shape whose axis of revolution (R) is coaxial with the main axis (A1) of the tank (12).

10. Filter (10) according to any one of claims 7 to 9 in combination with claim 2, wherein the axial retention of the filter trays (24) in the tank (12) is ensured by the lifting frame (76) and by the axial contact of the end section (42) of each of the collection tubes (36) on the shoulder (26) of the tank (12).

11. Filter (10) according to any one of claims 7 to 10, wherein the tank (12) comprises at least one central conduit (32) extending along the main axis (A1) of the tank (12), the central conduit (32) comprising axial guiding means (88) capable of cooperating with complementary guiding elements (86) carried by the lifting frame (76).

12. Filter (10) according to the preceding claim, wherein the guide elements (86) of the lifting frame (76) are rods extending parallel to the main axis (A1), the axial guide means (88) taking the form of grooves (88) formed on the periphery of the central conduit (32) and intended to house at least part of the rods.

13. Filter (10) according to any one of the preceding claims, in which a control conduit (46) extends outside the receiving volume (22) of the tank (12), between each channel (44) and the external collector (28), each control conduit (46) comprising a control element (50) for the passage of the fluid.

14. Filter (10) according to any one of the preceding claims, comprising double trays (24, 24b) comprising at least two filter elements (34) fluidly connected to the same collection tube (36) and single trays (24, 24a) comprising a single filter element (34) fluidly connected to a collection tube (36), the single trays (24, 24a) each extending between two double trays (24, 24b).

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