Rotary filters and related filtration methods

Abstract

The present invention provides a rotary filter (10) for liquid / solid separation of suspensions, the rotary filter comprising a tank (12), a spraying device (32), and at least one disc (14) non-rotatably connected to a main shaft (16), characterized in that: - each disc (14) comprises a first series (S1) of at least one filter sector (50), the first series being separated from a second series (S2) of at least one filter sector (50) by means of two non-filtration zones (54); - the main shaft (16) comprises a first tube (56) and a second tube (58), the first tube communicating with the first series (S1) of at least one filter sector (50) of each disc (14), the second tube communicating with the second series (S2) of at least one filter sector (50) of each disc (14); - the rotary filter (10) comprises comb teeth (102). The present invention also provides a filtration method.

Description

[0001] This invention relates to a rotary filter and related filtration methods, particularly of the type used in industrial facilities for liquid / solid separation under vacuum or pressure. This type of filter is typically used to filter liquids carrying solid particles (referred to as suspensions), which are produced, for example, by ore processing, crystallization, etc.

[0002] In many industries, the separation of solid particles from suspension is carried out by means of filtration, preferably using decanting technology which requires large-volume facilities and excessively long decanting times, or preferably using centrifugation technology which cannot achieve the required degree of separation and becomes expensive due to the energy required and maintenance.

[0003] The basic principle of filtration involves propelling a suspension through a filter medium whose porosity allows liquid to pass through but prevents solid particles from passing. The liquid produced by filtration is commonly referred to as "filtrate." As the filtrate flows through the filter medium, a layer of solid particles accumulates on its surface. As it grows, this layer of solid particles (often called a "filter cake") creates greater resistance to the passage of the liquid phase. Therefore, it is sometimes necessary to remove the filter cake while it is as thin as possible. The filter cake is removed by an operation called cake release. In the case of a thin filter cake, effective cake release involves sweeping the cake away by spraying fluid. This cake release method is called "detachment."

[0004] For example, in a disc rotary filter, the filter includes a tank, referred to as a trough, that contains a suspension to be filtered, and a main horizontal shaft equipped with at least two tubes and at least one disc. The at least one disc includes at least two independent filter sectors, each equipped with filter media and regularly distributed around the shaft. The interior of each filter sector communicates with a tube. The disc is partially immersed in the suspension so that the filter sector is immersed in the suspension for a portion of its travel during shaft rotation.

[0005] In disc rotary filters operating under pressure, the discs are placed within a pressurized housing that tends to push the suspension through the filter media toward the tubes. A filter cake forms on the media of the filter sector. As the filter sector emerges from the suspension during its journey, the filter cake undergoes rotation, which in turn facilitates its release.

[0006] Currently, in order to release the filter cake using detachment, the tank containing the suspension must be emptied beforehand. Therefore, detachment results in idle time, which is detrimental to the filter's efficiency, as it leads to a shorter time for thin filter cake formation.

[0007] The purpose of this invention is to provide a rotary filter and related filtration method that allows the thin filter cake to be operated by means of detachment to release the thin filter cake without having to empty the tank containing the suspension, thereby ensuring maximum filtration efficiency.

[0008] According to the invention, this objective is achieved by means of a rotary filter for liquid / solid separation of a suspension, the rotary filter comprising a tank for containing the suspension, means for spraying a detached fluid, and at least one disc non-rotatably connected to a main shaft, each disc being partially immersed in the suspension, and each disc comprising a plurality of filter sectors, each filter sector comprising a structural element covered by a filter medium and a conduit for connecting the sector to a first or second pipe arranged along the main shaft, characterized in that:

[0009] - Each disk includes a first series of at least one filter sector, which is separated from a second series of at least one filter sector by means of two non-filtering zones.

[0010] The spindle includes a first tube and a second tube, the first tube communicating with a first series of at least one filter sector of each disk, and the second tube communicating with a second series of at least one filter sector of each disk.

[0011] - The rotary filter includes comb teeth arranged above the level of the suspension on either side of each disc.

[0012] - The main axis is intended to occupy at least:

[0013] -- In the first corner position, the first series of at least one filter sector of each disc is located below the comb teeth and immersed in the suspension to be filtered, and in the first corner position, the second series of at least one filter sector of each disc is located above the comb teeth, with each non-filtered area adjacent to one comb tooth on each face of its surface.

[0014] -- In the second corner position, the second series of at least one filter sector of each disc is located below the comb teeth and immersed in the suspension to be filtered, and in the second corner position, the first series of at least one filter sector of each disc is located above the comb teeth, with each non-filtered area adjacent to one comb tooth on each of its faces.

[0015] This allows one of the first and second series of at least one filter sector on each disc above the comb teeth to disengage, while filtration of the suspension continues on the other of the first and second series of at least one filter sector on each disc below the comb teeth.

[0016] Other advantageous features according to the invention:

[0017] - The rotary filter includes at least one seal, which is arranged between each non-filtering zone and the adjacent comb tooth when the spindle occupies the first angular position and when the spindle occupies the second angular position;

[0018] - Each seal includes a retractable portion that is controlled between an extended state and a retracted state. In the extended state, the retractable portion establishes a sealing contact between the non-filtering area and the adjacent comb tooth. In the retracted state, there is no longer a sealing contact between the non-filtering area and the adjacent comb tooth.

[0019] - Each seal includes at least one elastically deformable portion;

[0020] - Each seal is arranged on the non-filtered area;

[0021] - Each unfiltered zone includes a disc sector, referred to as an unfiltered sector, which is inserted between the first series of filter sectors and the second series of filter sectors;

[0022] - Each unfiltered sector includes at least one inlet pipe for pressurized fluid, the inlet pipe being connected to a feed channel arranged along the main axis to allow each seal to expand by means of expansion and retract by means of contraction;

[0023] - Each seal is a diaphragm, which is secured to a non-filtering sector by its peripheral edge and includes a movable main wall connected to the peripheral edge by a connecting portion in the form of a gusset plate;

[0024] - The comb teeth are fixed to the edge of the groove;

[0025] - Each comb tooth slopes downward toward the outside from the main shaft to facilitate the flow of sludge formed by the fluid mixture used during the removal of the filter cake from the filter sector toward the outside of the tank;

[0026] - The spindle is equipped with a first downstream valve and a second downstream valve, the first downstream valve enabling the first tube to be closed when the first series of at least one filter sector of each disc undergoes a disengagement operation, and the second downstream valve enabling the second tube to be closed when the second series of at least one filter sector of each disc undergoes a disengagement operation.

[0027] - The rotary filter includes multiple disks;

[0028] - The trough is joined to the interior of the box, which includes a hopper arranged below the trough to recover sludge originating from the detached material;

[0029] - The device for spraying the detachment fluid includes an upper chamber having at least one inlet for the detachment fluid, and includes a series of perforations positioned above the disc, such that pressurization of the detachment fluid in the upper chamber causes a detachment jet toward the main surface of the filter sector.

[0030] The present invention also proposes a filtration method for liquid / solid separation of a suspension by means of a rotary filter, the rotary filter comprising: a tank for containing the suspension, a device for spraying off the fluid, and at least one disc non-rotatably connected to a main shaft, each disc being partially immersed in the suspension, and each disc comprising a plurality of filter sectors, each filter sector comprising a structural element covered by a filter medium and a conduit for connecting the filter sector to a first or second pipe arranged along the main shaft, the method comprising the following operations:

[0031] a) The suspension on each disc is filtered by means of a first or second series of at least one filter sector.

[0032] b) By spraying away the fluid, at least one filter sector of the first or second series is removed from each disc.

[0033] The method is characterized in that it includes a nominal operation cycle, during which:

[0034] The filtration operation of the first series of at least one filter sector of each disk and the disengagement operation of the second series of at least one filter sector of each disk are performed simultaneously. The spindle is controlled to a first angular position, in which the first series of at least one filter sector of each disk is immersed in the suspension, and in the first angular position, the second series of at least one filter sector of each disk is arranged above the suspension.

[0035] The filtration operation of the second series of at least one filter sector of each disc is performed simultaneously with the disengagement operation of the first series of at least one filter sector of each disc, the spindle is controlled to a second angular position, in which the second series of at least one filter sector of each disc is immersed in the suspension, and in the second angular position, the first series of at least one filter sector of each disc is arranged above the suspension.

[0036] Other advantageous methods according to the invention:

[0037] - The spindle includes a first tube and a second tube, the first tube being in communication with a first series of at least one filter sector of each disk, the second tube being separate from the first tube and in communication with a second series of at least one filter sector of each disk, and characterized in that the first tube is closed during the disengagement operation of the first series of at least one filter sector of each disk, and the second tube is closed during the disengagement operation of the second series of at least one filter sector of each disk.

[0038] - A sealing step is performed before each disengagement operation, during which a sealing contact is established between each disc and the adjacent comb teeth, and is characterized in that a stopping sealing step is performed after each disengagement operation, during which the sealing contact is stopped;

[0039] - The sealing step includes controlling the retractable portion of the seal to an extended state, in which the retractable portion ensures the sealing contact, and stopping the sealing step includes controlling the retractable portion to a retracted state, in which the retractable portion ensures the sealing contact stops.

[0040] - The seal expands by means of expansion caused by pressurization of the fluid circuit, which feeds at least two unfiltered sectors to each disc through a feed channel arranged along the main shaft, the at least two unfiltered sectors being arranged between the first series and the second series of at least one filtered sector in each disc, and the seal retracts by means of contraction caused by pressure drop in the fluid circuit.

[0041] - During the nominal operating cycle, the spindle is alternately controlled to pivot 180 degrees clockwise and then counterclockwise between the first angular position and the second angular position;

[0042] - The sludge originating from the detachment operation is partially reinjected into the feed circuit of the device for spraying detachment fluid into the disc during the detachment operation.

[0043] Those skilled in the art may also recognize additional advantages as they read the examples below, illustrated by the accompanying figures:

[0044] - Figure 1 It is based on Figure 2 A perspective view of the longitudinal section of plane II, showing the rotating filter according to the invention;

[0045] - Figure 2 It is shown in the sectional view based on plane II-II. Figure 1 Rotary filter;

[0046] - Figure 3 The longitudinal sectional view based on plane III-III shows the unfolded seal, in which case it is shown equipped with Figure 1 The expansion of the non-filtering sector diaphragm in the rotary filter;

[0047] - Figure 4 It is shown Figure 1 A perspective cross-sectional view of a portion of a rotating filter;

[0048] - Figure 5 It is shown Figure 1 A perspective view of a non-filtering sector of a rotary filter equipped with a diaphragm;

[0049] - Figure 6 It is based on Figure 5 A cross-sectional view along plane IV-IV shows the non-filtering sector of the rotating filter as the diaphragm contracts;

[0050] - Figure 7 It is based on Figure 5 A cross-sectional view along plane IV-IV shows the non-filtering sector of the rotating filter as the diaphragm expands;

[0051] - Figure 8 This is a schematic diagram illustrating the first step of the filtration method according to the present invention, wherein the main shaft of the rotating filter occupies a first angular position, and during this period, filtration begins simultaneously on the first series of filter sectors of each disc, the rotation of the filter cake occurs on the second series of filter sectors of each disc, and the diaphragm expands on the non-filter sectors.

[0052] - Figure 9 This is a schematic diagram illustrating the second step of the filtration method according to the invention, wherein the main shaft of the rotating filter occupies the same angular position, and during this period, filtration continues simultaneously on the first series of filter sectors, a disengagement operation occurs on the second series of filter sectors, and these diaphragms are controlled to be in an expanded state on the non-filter sectors.

[0053] - Figure 10 This is a schematic diagram illustrating the third step of the filtration method according to the invention, wherein the main shaft of the rotating filter is kept at the same angular position, and during this period, filtration continues simultaneously on the first series of filter sectors, and the diaphragm contracts on the non-filter sectors;

[0054] - Figure 11 This is a schematic diagram illustrating the fourth step of the filtering method according to the present invention, during which the main shaft pivots toward the second angular position;

[0055] - Figure 12 It is a longitudinal sectional view based on plane III-III, showing that in Figure 8 The sealing is achieved during the first step shown by the expansion of the diaphragm;

[0056] - Figure 13 It is a longitudinal sectional view based on plane III-III, showing that in Figure 9 The expansion state of the diaphragm during the second step is shown;

[0057] - Figure 14 It is shown in the longitudinal sectional view based on plane III-III. Figure 10 The sealing is stopped during the third step shown by the contraction of the diaphragm;

[0058] - Figure 15 It is a longitudinal sectional view based on plane III-III, showing that in Figure 11 The diaphragm is in a contracted state during the fourth step shown.

[0059] Figure 1 A rotary filter 10 is shown for use in industrial facilities for the separation of liquids and solids in suspensions.

[0060] In the remainder of the specification, as a non-limiting example, the following will be used: Figure 1 The reference points V, L, and T, which define the vertical, longitudinal, and transverse orientations, are shown. Furthermore, identical or similar elements may be indicated by the same reference numerals.

[0061] according to Figure 1 In the illustrated embodiment, the rotary filter 10 includes a slot 12 and a plurality of discs 14 non-rotatably connected to a main shaft 16. In this case, the main shaft 16 is mounted to be rotatable about a longitudinal axis A1, which extends in the longitudinal direction through a housing 18 that receives the slot 12 and the discs 14.

[0062] Especially Figure 2 and Figure 3 As shown, the tank 12 is generally semi-cylindrical in shape with an opening at the top, and its diameter is slightly larger than that of the disc 14. In this case, the suspension is fed into the tank 12 through the feed pipe 20.

[0063] In this configuration, the trough 12 is suspended at the center of the box 18. In this embodiment, the box 18 includes a main cylindrical wall 22 having a vertical axis A2, which extends from the hopper 26 at its lower axial end 24 and from the bell-shaped cover 30 at its upper axial end 28.

[0064] According to the embodiment shown, the rotary filter 10 is designed to operate under pressure, i.e., the chamber defined by the housing 18 is placed under a pressure higher than atmospheric pressure in order to force the filtrate through the disc 14, then toward the interior of the spindle 16, and finally toward the outlet of the spindle 16, as will be seen in more detail below.

[0065] In this configuration, the spray device 32 is housed within a cover 30 above the disc 14. According to the illustrated embodiment, the spray device 32 includes a spherical cap 34, which is welded to the truncated conical wall 36 of the cover 30 to define an upper chamber 38 in the top portion of the housing 18 capable of receiving detached fluid. The spherical cap 34 includes a series of perforations 40 positioned above the disc 14, such that pressurization of the detached fluid in the upper chamber 38 causes a detached jet J1 to pass through the perforations 40 toward the disc 14. The spray device 32 typically operates as a shower head.

[0066] The cover 30 is advantageously provided with an access port 42, which makes it possible to facilitate the cleaning and maintenance of the spraying device 32. In this case, the access port 42 is provided with a feed opening 44 for discharging fluid.

[0067] According to another advantageous embodiment, the perforation 40 may be equipped with a nozzle capable of forming a plane or any other shape of detached jet J1 toward the main surface (i.e., radial surface) of the disk 14.

[0068] In the remainder of the instruction manual, for disk elements or disk sectors, the main surface refers to the radial surface, that is, the surface extending in a transverse plane relative to the axis of the disk.

[0069] According to the embodiment shown, the flange 46 (in this case, in the form of a plate parallel to the disc 14) is fixed to the lower surface of the spherical cap 34 on either side of the stack formed by all the discs 14 of the rotating filter 10, so as to define a spray area above the discs 14.

[0070] It should be noted that flange 46 also helps to reinforce the rigidity of spherical cap 34 by means of reinforcing ribs.

[0071] The hopper 26 is terminated at its lower axial end by a plug 48, which allows the discharge of slurry produced by the disengagement operation.

[0072] The detachment fluid (also known as the cleaning fluid, filter cake release fluid, or flushing fluid) is, for example, a mixture of water and slurry derived from the detachment operation.

[0073] In this case, each disc 14 is formed by a first series S1 and a second series S2 of filter sector 50, the first series S1 and the second series S2 being separated from each other by two non-filtered zones 52 with opposite diameters.

[0074] In the illustrated embodiment, each of the first series S1 and the second series S2 includes four filter sectors 50, and each non-filtered zone 52 is a non-filtered sector 54.

[0075] It should be noted that the present invention is also applicable to the rotary filter 10, wherein the first series S1 and the second series S2 comprise only one filter sector 50.

[0076] The first series S1 of the filter sector 50 is intended to communicate with the first tube 56 arranged in the main shaft 16, and the second series S2 of the filter sector 50 is intended to communicate with the second tube 58 arranged in the main shaft 16.

[0077] according to Figure 4 In the illustrated embodiment, each filter sector 50 includes a structural element 60 covered by a filter medium 62 (e.g., filter cloth), and at least one conduit 64 (in this case, two conduits), which... Figure 1 The visible connection opening 66 leads to one of the first tube 56 and the second tube 58 of the main shaft 16.

[0078] Structural element 60 is used to support filter medium 62. Filter medium 62 defines the internal volume of filter sector 50 in which filtrate flows.

[0079] Advantageously, such as Figures 3 to 7 As shown, each non-filtering fan-shaped body 54 includes a solid body 68 in the shape of a disc fan, wherein the solid body is provided with a through hole 70, and the solid body includes seals 74, 75 on each of its main faces 72, 73.

[0080] In this configuration, each seal 74, 75 is an elastically deformable diaphragm 76, 77. Each diaphragm 76, 77 is secured to the solid body 68 by means of a mounting flange 80 via its peripheral edge 78. Thus, the peripheral edge 78 of each diaphragm 76, 77 is clamped between the mounting flange 80 and the solid body 68.

[0081] Each diaphragm 76, 77 includes a retractable portion 82, which consists of a movable main wall 84 and a connecting portion 86 in the form of a gusset plate connecting the movable main wall 84 to a peripheral edge 78. Figure 6 As can be seen, in this case, the connecting portion 86 has an S-shaped profile. The connecting portion 86 is designed to be as follows: Figure 7 As shown, it unfolds, thus allowing the movable main wall 84 to move in the opposite direction to the solid body 68.

[0082] Advantageously, each mounting flange 80 includes a concave curved edge 88 on the side of the movable main wall 84, which is designed to match the S-shape of the connecting portion 86.

[0083] In this case, the diaphragms 76 and 77 are made primarily of elastomer or rubber-type materials in order to benefit from the sufficient flexibility of the connecting portion 86, thereby undergoing elastic deformation and thus naturally returning to their initial shape after deformation.

[0084] The material of each diaphragm 76, 77 may advantageously include a core made of textiles or another material, which allows a certain amount of structural tension to be maintained in the diaphragms 76, 77.

[0085] These diaphragms 76 and 77 seal against the suspension. They do not have a filtering function. They act as seals, which will be explained in more detail below.

[0086] An inlet pipe 90 for pressurized fluid is arranged within a solid body 68. For example... Figure 2 As shown, the inlet pipe 90 communicates with a feed channel 92 for pressurized fluid (e.g., compressed air), which is arranged along the main shaft 16, in this case internally, to allow each diaphragm 76, 77 to expand by pressurization. The diaphragms 76, 77 thus form retractable seals.

[0087] The solid body 68 is formed, for example, from a steel plate, or actually from another material. In this case, it is fixed to the spindle 16 by a base 94, which is specifically provided with two pins 96 and a radial connecting pipe 98, which communicates on one side with a feed channel 92 for pressurized fluid and on the other side with a compressed fluid inlet pipe 90.

[0088] Pin 96 ensures proper positioning of the unfiltered sector 54 on the spindle 16, thereby preventing the unfiltered sector 54 from pivoting.

[0089] from Figure 6 As the contracted state of the diaphragms 76 and 77 begins, the feeding of pressurized fluid through the inlet pipe 90 causes an increase in pressure inside the unfiltered sector 54 of the cavity 100 defined by the two diaphragms 76 and 77 on either side of the solid body 68. This increase in pressure within the cavity 100 tends to push the movable main wall 84 back towards the outside of the unfiltered sector 54 until the movable main wall 84 occupies its expanded state, as shown... Figure 7 As shown.

[0090] For example, especially in Figure 2 , Figure 3 and Figure 4 As can be seen, the groove 12 includes comb teeth 102 arranged above the level of the suspension on either side of each disc 14. In this case, each comb tooth 102 is fixed against the longitudinal edge 104 of the groove 12, for example by a threaded connection, and extends toward the main shaft 16.

[0091] To ensure good rigidity of the comb teeth 102, each comb tooth 102 includes a body and a bar 108. The body is typically dovetail-shaped and has a support foot 106 for securing it to the inner surface of the longitudinal edge 104 of the slot 12. The bar extends from the upper end of the support foot 106 to the free end 110 near the main shaft 16. In this case, each comb tooth 102 includes a reinforcing plate 112 that extends below the bar 108 to the support foot 106.

[0092] Advantageously, the first series D1 of the comb teeth 102 is arranged on one side of the main shaft 16, while the second series D2 of the comb teeth 102 is arranged on the other side of the main shaft 16.

[0093] Therefore, each disc 14 is held by four comb teeth 102, two of which belong to the first series D1 and two of which belong to the second series D2.

[0094] Advantageously, the upper surface 114 of the bar 108 of each comb tooth 102 is inclined downward from the main shaft 16, as will be seen below, which promotes the flow of sludge from the disengagement operation to the outside of the tank 12.

[0095] As described above, the spindle 16 includes a first tube 56 and a second tube 58 or chamber separated by a longitudinal partition wall 116. The spindle 16 is intended to be rotated by a drive device 118 between two extreme angular positions: a first angular position P1 and a second angular position P2, the first angular position being determined by… Figures 1 to 3 It is shown that in the first corner position, the first series S1 of the filter sector 50 is immersed in the suspension, and in the second corner position, the diameter is opposite to that of the first corner position P1, and in the second corner position, the second series S2 of the filter sector 50 is immersed in the suspension.

[0096] In the first corner position P1, all filter sectors 50 of the first series S1 are located in the groove 12, below the comb teeth 102, while all filter sectors 50 of the second series S2 are located above the groove 12, above the comb teeth 102. The non-filter sectors 54 that separate the filter sectors 50 of each disc 14 from those of the first series S1 and the second series S2 are located at the height of the comb teeth 102, such that the expansion of the diaphragms 76, 77 in the region of the rod 108 causes a sealing contact between the diaphragms 76, 77 and the sidewalls 120, 121 of the adjacent comb teeth 102.

[0097] Advantageously, all discs 14 (eight in this case) are positioned relative to the spindle 16 in the same manner as the slot 12. Thus, in the first angular position P1, the first series S1 of the filter sectors 50 of all discs 14 are immersed in the suspension, while the second series S2 of their filter sectors 50 are positioned above the first series D1 and the second series D2 of the comb teeth 102.

[0098] The second angular position P2 is symmetrical about the first angular position P1 with respect to the longitudinal axis A1.

[0099] Advantageously, the spindle 16 is equipped with a first downstream valve 122 and a second downstream valve 124 at its downstream end. In this case, the first downstream valve enables the closure of the first pipe 56 on the filtrate discharge side, and in this case, the second downstream valve enables the closure of the second pipe 58 on the filtrate discharge side.

[0100] The operation of the rotary filter 10 will now be described, with particular reference to Figures 8 to 15 This illustrates the different steps of the filtering method. It should be noted that... Figures 12 to 15 They are shown respectively in Figures 8 to 11 The shapes of diaphragms 76 and 77 are shown during the steps illustrated.

[0101] The rotary filter 10 continuously supplies the suspension to keep the tank 12 full.

[0102] Figure 8 The rotary filter 10 is shown after it has undergone multiple operating cycles, such that the second series S2 of the filter sector 50, positioned above the first series D1 and the second series D2 of the comb teeth 102, is covered with filter cake. Furthermore, the hopper 26 is filled with sludge originating from the previous separation step.

[0103] Figure 8 The first step of the filtration method is illustrated, in which the suspension is filtered by a first series S1 of filter sectors 50 inserted into the suspension. Thus, under the pressure present throughout the chamber 18, the filtrate passes through the filter medium 62 of the filter sectors 50. The filtrate enters the first tube 56 of the main shaft 16 through the connecting opening 66 and is discharged from the main shaft 16 through the first downstream valve 122, which is controlled to be in the open position.

[0104] Simultaneously, during the first step, the second downstream valve 124 is controlled to the open position. This maintains a positive pressure difference between the pressure in the housing 18 and the pressure in the second pipe 58 of the main shaft 16, which allows for the rotation of the filter cake on the filter sector 50 of the second series S2.

[0105] Simultaneously, during the first step, diaphragms 76 and 77 are pressurized, such as... Figure 12As shown, this allows them to expand, thereby establishing a sealed contact between the comb teeth 102 and the non-filtering fan-shaped body 54.

[0106] Figure 9 The second step of the method is shown, in which the suspension continues to be filtered by the first series S1 of the filter sector 50 because the spindle 16 still occupies its first angular position P1 and the first downstream valve 122 is still open.

[0107] Simultaneously, during the second step, the second downstream valve 124 is controlled to the closed position. This creates a balance between the pressure in the housing 18 and the pressure in the second pipe 58 of the main shaft 16, allowing an effective disengagement operation to be performed on the filter sector 50 of the second series S2 by means of a spraying device 32, which sprays a disengagement jet J1 onto the filter sector 50, and more specifically onto the main surface of the filter sector 50 of the second series S2. The diaphragms 76, 77 remain in an expanded state on their non-filtering sectors 54.

[0108] like Figure 9 As shown, the separation operation produces sludge, which is a mixture of the separated fluid and solid particles derived from the filter cake. The sludge flows downward along the comb teeth 102 into the hopper 26.

[0109] like Figure 13 As shown, the seal achieved before the expansion of the diaphragms 76 and 77 prevents sludge from seeping into the tank 12 by passing between the disc 14 and the comb teeth 102. This thus makes it possible to ensure perfect effectiveness of filtration on the first series S1 of the filter sector 50 in the tank 12 and detachment on the second series S2 of the filter sector 50.

[0110] Figure 10 The third step of the method is shown, in which the suspension continues to be filtered by the first series S1 of the filter sector 50 because the spindle 16 still occupies its first angular position P1 and the first downstream valve 122 is still open.

[0111] Simultaneously, during the third step, since the disengagement operation has ended and the diaphragms 76 and 77 have contracted, the spraying device 32 stops, as... Figure 14 As shown. The spindle 16 still occupies its first angular position P1, and the second downstream valve 124 remains closed.

[0112] The contraction of diaphragms 76 and 77 prevents them from rubbing against adjacent comb teeth 102 when the main shaft 16 rotates, which would otherwise lead to the risk of premature wear.

[0113] Figure 11The fourth step of the method is shown, in which the spindle 16 rotates from its first angular position P1 to its second angular position P2, in this case counterclockwise. Figure 11 In the diagram, the main axis 16 is shown as the intermediate angular position Pi between the first angular position P1 and the second angular position P2.

[0114] During the fourth step, the first downstream valve 122 remains in the open position, allowing filtration to continue in the filter sector 50 of the first series S1 as long as it remains immersed in the suspension. Figure 11 As can be seen, the rotation step begins with the first series of filter sectors 50 of S1 where the suspension appears, while those filter sectors still immersed in the suspension continue to filter.

[0115] During the fourth step, the second downstream valve 124 remains in the closed position, so that the filter sector 50 of the second series S2 that gradually enters the tank 12 does not begin filtration.

[0116] During the fourth step, diaphragms 76 and 77 remain contracted, as... Figure 15 As shown.

[0117] At the end of the fourth step, after rotating 180 degrees counterclockwise relative to the first angular position P1, the main shaft 16 occupies its second angular position P2, so that the filter sector 50 of the first series S1 is in a high position above the first series D1 and the second series D2 of the comb teeth 102, while the filter sector 50 of the second series S2 is immersed in the suspension.

[0118] Therefore, as Figure 8 and Figure 12 As shown, after the fourth step, a new first step begins, but includes filtration by the filter sector 50 of the second series S2 at the bottom, and includes rotation by the filter sector 50 of the first series S1 at the top.

[0119] Therefore, the complete nominal operating cycle includes the above four steps, repeated twice, so that the first series S1 and the second series S2 of the filter sector 50 have been filtered and removed.

[0120] Preferably, at the end of the nominal operation cycle, the spindle 16 rotates in the opposite direction, in this case clockwise, so as to return from the second angular position P2 toward its first angular position P1.

[0121] In particular, the alternating pivoting in both clockwise and counterclockwise directions prevents the control cables of the first downstream valve 122 and the second downstream valve 124 carried by the spindle 16 from becoming entangled. This also facilitates the arrangement of the device for feeding pressurized fluid into the feed channel 92 of the spindle 16.

[0122] Advantageously, some of the sludge from the separation step is recovered at the outlet of hopper 26 and then partially reinjected into the feed circuit of spraying device 32. Thus, it forms part of the separation fluid. This recirculation reduces the consumption of other fluids used for separation and minimizes the volume of the resulting sludge, regardless of the filter cake formation time.

[0123] The rotary filter 10 and filtration method according to the invention are particularly suitable for industrial facilities where it is desirable to minimize the cake formation time, for example, if the cake formation time is less than 2 minutes.

[0124] For example, the filtering method according to the invention can be implemented by limiting the first step to 15 seconds, the second step to 90 seconds, the third step to 5 seconds, and the fourth step to 10 seconds.

[0125] The rotary filter 10 according to the invention has the advantage of facilitating maintenance operations. For example, removing the cover 30 allows access to the interior of the housing 18 and relatively easy removal of the main shaft 16 or disc 14 for replacement of the filter media 62. Similarly, the access port 42 arranged in the cover 30 allows easy access to the spraying device 32 for cleaning and to clear any perforations 40 that may be clogged due to sludge recycling.

[0126] According to a variant, the spraying device 32 can be replaced by a ramp device with multiple spray nozzles distributed above the disc 14.

[0127] Of course, the present invention is also applicable to a rotary filter 10 operating under vacuum, wherein the liquid phase of the suspension is drawn through the filter sector 50 and through the first tube 56 and the second tube 58 of the main shaft 16.

[0128] According to a variant (not shown), the comb teeth 102 can be mounted on the slot 12 so that they can move between a movable position and a retracted position, such as... Figures 2 to 4 As shown, in the active position, the comb teeth are in sealed contact with the non-filtering sector 54, and in the retracted position, the comb teeth are no longer in contact with the non-filtering sector 54. In this case, the diaphragms 76 and 77 can be omitted, and the comb teeth 102 are controlled to the retracted position during the third and fourth steps to allow the disc 14 to rotate.

[0129] List of reference numerals

[0130] 10: Rotary Filter

[0131] 12: Slot

[0132] 14: Plate

[0133] 16: Spindle

[0134] 18: Box

[0135] 20: Feed pipe

[0136] 22: Main cylindrical wall

[0137] 24: Lower axial end

[0138] 26: Hopper

[0139] 28: Upper axial end

[0140] 30: Cover

[0141] 32: Spraying device

[0142] 34: Spherical Cap

[0143] 36: Truncated conical wall

[0144] 38: Upper chamber

[0145] 40: Perforation

[0146] 42: Inspection port

[0147] 44: Feed opening

[0148] 46: Flange

[0149] 48: Stopper

[0150] 50: Filter sector

[0151] 52: Unfiltered area

[0152] 54: Non-filtered sector

[0153] 56: First tube

[0154] 58: Second tube

[0155] 60: Structural Components

[0156] 62: Filter media

[0157] 64: Catheter

[0158] 66: Connection opening

[0159] 68: Solid main body

[0160] 70: Through hole

[0161] 72, 73: Main side

[0162] 74, 75: Seals

[0163] 76, 77: Diaphragm

[0164] 78: Peripheral Edge

[0165] 80: Install flange

[0166] 82: Retractable section

[0167] 84: Movable main wall

[0168] 86: Connection part

[0169] 88: Concave curved edge

[0170] 90: Inlet pipe

[0171] 92: Feeding channel

[0172] 94: Base

[0173] 96: Sales

[0174] 98: Radial connecting pipe

[0175] 100: Cavity

[0176] 102: Comb teeth

[0177] 104: Vertical edge

[0178] 106: Support foot

[0179] 108: pole

[0180] 110: Free End

[0181] 112: Reinforcing plate

[0182] 114: Upper surface

[0183] 116: Longitudinal partition wall

[0184] 118: Drive unit

[0185] 120, 121: Sidewall

[0186] 122: First downstream valve

[0187] 124: Second downstream valve

[0188] A1: Longitudinal axis

[0189] A2: Vertical axis

[0190] J1: Detaching from the jet.

Claims

1. A rotary filter (10) for liquid / solid separation of a suspension, the rotary filter comprising a tank (12) for containing the suspension, a device (32) for spraying a detached fluid, and at least one disc (14) non-rotatably connected to a main shaft (16), each disc (14) being partially immersed in the suspension, and each disc (14) comprising a plurality of filter sectors (50), each filter sector (50) comprising a structural element (60) covered by a filter medium (62) and a conduit (64) for connecting the filter sector (50) to a first tube (56) or a second tube (58) arranged along the main shaft (16), characterized in that: - Each disc (14) includes a first series (S1) of at least one filter sector (50), which is separated from a second series (S2) of at least one filter sector (50) by means of two non-filtered zones (52). - The main shaft (16) includes a first tube (56) and a second tube (58), the first tube being connected to the first series (S1) of at least one filter sector (50) of each disc (14), and the second tube being connected to the second series (S2) of at least one filter sector (50) of each disc (14). - The rotary filter (10) includes comb teeth (102) arranged above the level of the suspension on either side of each disc (14). - The main shaft (16) is intended to occupy at least: -- First corner position (P1), in the first corner position, the first series (S1) of at least one filter sector (50) of each disc (14) is located below the comb teeth (102) and immersed in the suspension to be filtered, and in the first corner position, the second series (S2) of at least one filter sector (50) of each disc (14) is located above the comb teeth (102), and each non-filtered area (52) is adjacent to one comb tooth (102) on each face of its surface. -- Second corner position (P2), in which the second series (S2) of at least one filter sector (50) of each disc (14) is located below the comb teeth (102) and immersed in the suspension to be filtered, and in the second corner position, the first series (S1) of at least one filter sector (50) of each disc (14) is located above the comb teeth (102), and each non-filtered area (52) is adjacent to one comb tooth (102) on each of its faces. This allows one of the first series (S1) and the second series (S2) of at least one filter sector (50) of each disc (14) above the comb teeth (102) to disengage, while filtration of the suspension continues on the other of the first series (S1) and the second series (S2) of at least one filter sector (50) of each disc (14) below the comb teeth (102). A sealing step is performed before each disengagement operation, during which a sealing contact is established between each disc (14) and the adjacent comb tooth (102), and a stopping sealing step is performed after each disengagement operation, during which the sealing contact is stopped.

2. The rotary filter (10) according to claim 1, characterized in that, The rotary filter includes at least one seal (74, 75) which is arranged between each non-filtering zone (52) and the adjacent comb tooth (102) when the main shaft (16) occupies the first corner position (P1) and when the main shaft (16) occupies the second corner position (P2).

3. The rotary filter (10) according to claim 2, characterized in that, Each seal (74, 75) includes a retractable portion (82) that is controlled between an extended state and a retracted state, wherein in the extended state the retractable portion establishes a sealing contact between the non-filtering area (52) and the adjacent comb tooth (102), and in the retracted state there is no longer a sealing contact between the non-filtering area (52) and the adjacent comb tooth (102).

4. The rotary filter (10) according to claim 3, characterized in that, Each seal (74, 75) includes at least one elastically deformable portion.

5. The rotary filter (10) according to claim 3, characterized in that, Each seal (74, 75) is arranged on the non-filtered area (52).

6. The rotary filter (10) according to claim 5, characterized in that, Each unfiltered zone (52) includes a disc sector called an unfiltered sector (54), which is inserted between the filter sectors (50) of the first series (S1) and the filter sectors (50) of the second series (S2).

7. The rotary filter (10) according to claim 6, characterized in that, Each unfiltered sector (54) includes at least one inlet pipe (90) for pressurized fluid, the inlet pipe being connected to a feed channel (92) arranged along the main shaft (16) to allow each seal (74, 75) to expand by means of expansion and retract by means of contraction.

8. The rotary filter (10) according to claim 6, characterized in that, Each seal (74, 75) is a diaphragm (76, 77) which is fixed to the non-filtering fan (54) by its peripheral edge (78) and includes a movable main wall (84) connected to the peripheral edge (78) by a connecting portion (86) in the form of a gusset plate.

9. The rotary filter (10) according to claim 1, characterized in that, The comb teeth (102) are fixed to the edge of the groove (12).

10. The rotary filter (10) according to claim 1, characterized in that, Each comb tooth (102) is inclined downward toward the outside from the main shaft (16) to facilitate the flow of sludge, consisting of the fluid mixture used during the removal of the filter cake from the filter sector (50), toward the outside of the tank (12).

11. The rotary filter (10) according to claim 1, characterized in that, The spindle (16) is equipped with a first downstream valve (122) and a second downstream valve (124), the first downstream valve enabling the first tube (56) to be closed when the first series (S1) of at least one filter sector (50) of each disc (14) undergoes a disengagement operation, and the second downstream valve enabling the second tube (58) to be closed when the second series (S2) of at least one filter sector (50) of each disc (14) undergoes a disengagement operation.

12. The rotary filter (10) according to claim 1, characterized in that, The rotary filter includes multiple discs (14).

13. The rotary filter (10) according to claim 1, characterized in that, The trough (12) is engaged inside the box (18), which includes a hopper (26) arranged below the trough (12) to recover sludge originating from the detached material.

14. The rotary filter (10) according to claim 1, characterized in that, The device (32) for spraying the detachment fluid includes an upper chamber (38) provided with at least one inlet opening (44) for the detachment fluid, and includes a series of perforations (40) positioned above the disc (14) such that pressurization of the detachment fluid in the upper chamber (38) causes a detachment jet (J1) toward the main surface of the filter fan (50).

15. A filtration method for liquid / solid separation of a suspension by means of a rotary filter (10), the rotary filter comprising: The method comprises a tank (12) containing the suspension, a device (32) for spraying off the fluid, and at least one disc (14) non-rotatably connected to a main shaft (16), each disc (14) being partially immersed in the suspension, and each disc (14) including a plurality of filter sectors (50), each filter sector (50) including a structural element (60) covered by a filter medium (62) and a conduit (64) for connecting the filter sector to a first tube (56) or a second tube (58) arranged along the main shaft (16), the method comprising the following operations: a) The suspension on each disc (14) is filtered by means of a first series (S1) or a second series (S2) of at least one filter sector (50). b) A first series (S1) or a second series (S2) of at least one filter sector (50) on each disc (14) is detached by spraying off the fluid. The method is characterized in that it includes a nominal operation cycle, during which: The filtration operation of the first series (S1) of at least one filter sector (50) of each disc (14) and the disengagement operation of the second series (S2) of at least one filter sector (50) of each disc (14) are performed simultaneously, the spindle (16) is controlled to a first angular position (P1), in which the first series (S1) of at least one filter sector (50) of each disc (14) is immersed in the suspension, and in the first angular position, the second series (S2) of at least one filter sector (50) of each disc (14) is arranged above the suspension, and The filtration operation of the second series (S2) of at least one filter sector (50) of each disc (14) and the disengagement operation of the first series (S1) of at least one filter sector (50) of each disc (14) are performed simultaneously, the spindle (16) is controlled to a second corner position (P2), in which the second series (S2) of at least one filter sector (50) of each disc (14) is immersed in the suspension, and in the second corner position, the first series (S1) of at least one filter sector (50) of each disc (14) is arranged above the suspension. The sealing step is performed before each disengagement operation, during which a sealing contact is established between each disc (14) and the adjacent comb tooth (102), and is characterized in that the sealing step is stopped after each disengagement operation, during which the sealing contact is stopped.

16. The filtration method according to claim 15, characterized in that, The spindle (16) includes a first tube (56) and a second tube (58), the first tube being in communication with the first series (S1) of at least one filter sector (50) of each disc (14), the second tube being separate from the first tube (56) and in communication with the second series (S2) of at least one filter sector (50) of each disc (14), and characterized in that the first tube (56) is closed during the disengagement operation of the first series (S1) of at least one filter sector (50) of each disc (14), and the second tube (58) is closed during the disengagement operation of the second series (S2) of at least one filter sector (50) of each disc (14).

17. The filtration method according to claim 15, characterized in that, The sealing step includes controlling the retractable portion (82) of the seal (74, 75) to an extended state, in which the retractable portion ensures the sealing contact, and stopping the sealing step includes controlling the retractable portion (82) to a retracted state, in which the retractable portion ensures the sealing contact stops.

18. The filtration method according to claim 17, characterized in that, The seals (74, 75) expand by means of expansion caused by pressure from a fluid circuit that feeds at least two unfiltered sectors (54) of each disc (14) through a feed channel (92) arranged along the main shaft (16), the at least two unfiltered sectors being arranged between the first series (S1) and the second series (S2) of at least one filtered sector (50) of each disc (14), and the seals (74, 75) retract by means of contraction caused by pressure drop from the fluid circuit.

19. The filtration method according to claim 15, characterized in that, During the nominal operating cycle, the spindle (16) is alternately controlled to pivot 180 degrees clockwise and then counterclockwise between the first angular position (P1) and the second angular position (P2).

20. The filtration method according to claim 15, characterized in that, The sludge originating from the detachment operation is partially reinjected into the feed circuit of the device (32) for spraying detachment fluid into the disc (14) during the detachment operation.

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