Opening of lye filter

Abstract

The invention relates to a lye filter unit (10) capable of filtering ferrous residues, iron deposits and any other impurities in an electrolyte solution coming from an electrolysis unit, comprising:-a tank (12) extending in a main vertically extending direction (A) and comprising a side wall (18) and an upper face (16) comprising an opening (20), and the side wall (18) comprises a gasket (64) on a bearing edge (68) placed at a distance E from the opening (20); and-a cover (22) capable of cooperating with the upper face (16) of the can body (12) in order to seal the opening (20); -a filter basket (54) comprising an upper face (58) and a peripheral rim (62) able to rest on the gasket (64); and-a bearing edge (68) capable of exerting pressure on the upper face (58) of the filter basket (54).

Description

TECHNICAL FIELD

[0001] The present invention relates to a caustic solution filtration unit capable of filtering out ferrous residues, iron precipitates and any other impurities present in an electrolyte solution coming from an electrolysis unit, such as an electrolysis unit for producing molecular hydrogen (H2) and molecular oxygen (O2).

[0002] The present invention more particularly relates to a caustic solution filtration unit designed to be more easily maintained, and to a method for maintaining this caustic solution filtration unit. BACKGROUND

[0003] The caustic solution filter (also called caustic solution filtration unit) is mainly used to filter out ferrous residues and iron precipitates, but also to filter out any other impurities, even if their content is negligible.

[0004] Figure 1 And Figure 2 A caustic solution filtration unit 100 according to the prior art is shown. The caustic solution filtration unit 100 comprises a tank body 12 having a caustic solution inlet pipe 28, a caustic solution outlet pipe 30 and two impurity capture elements placed in the tank body 12, namely:

[0005] i) at least one bar magnet 72 for collecting magnetic particles, whatever their size, and

[0006] ii) a filter basket 54 supporting a lower screen consisting of a tight metal mesh intended to capture non-magnetic particles, whatever their size.

[0007] After this particle capture action, the agglomerates of iron and / or any other substance on the caustic solution filter 100 must be cleaned periodically to maintain the effectiveness of the system. All the filtered-out iron agglomerates, trace substances and molecules are considered as impurities.

[0008] Currently, this maintenance operation is quite laborious and not very simple due to the quality and the steric hindrance of the caustic solution filter 100 and the factors associated with the bar magnet(s) 72 and the filter basket 54 inside the caustic solution filter 100.

[0009] The factors that make the maintenance operation tricky are as follows:

[0010] i) the filter basket 54, which contains a screen formed of a very heavy tight metal mesh, is fastened to the gaskets of the lateral wall of the caustic solution filter 100 by means of screws, and the bottom of the filter basket is positioned close to the lower end of the caustic solution filter 100, and

[0011] ii) one or more bar magnets 72 directly fastened to the lid 22 of the caustic filter 100, the top of which is fitted with at least one handle necessary for lifting the assembly consisting of the lid 22 and the one or more bar magnets 72.

[0012] Therefore, during the maintenance of the caustic filter 100, various non-negligible obstacles related to the above-defined points i) and ii) can be listed as follows, including:

[0013] - the disassembly of the filter basket 54, which is rather complex because:

[0014] a) the filter basket 54 is difficult to access since it is positioned at a certain depth with respect to the inlet of the caustic filter 100,

[0015] b) the mass of the filter basket 54 to be removed is very large, and

[0016] c) human intervention is required to remove the screws, which is difficult due to the tightness of the space inside the caustic filter 100,

[0017] - the manipulation of the lid 22 with the aid of at least one handle during the opening of the caustic filter 100 by human intervention, which is particularly tricky since the mass of the lid 22 itself is quite large.

[0018] During this manipulation, it is also important to take into account the mass and volume of the one or more bar magnets 72 directly attached to the lid 22 to be lifted. In other words, the overall mass is very high and, in addition, the manipulation is also complicated due to the length of the one or more bar magnets 72 to be lifted and removed.

[0019] Therefore, there is an advantage of easier maintenance operations of the caustic filter unit 100, including the cleaning of the various elements of the caustic filter unit 100.

[0020] Another example of a filter unit is described and illustrated in document US2014 / 0373325A1. SUMMARY

[0021] In order to eliminate all the obstacles mentioned above, this innovation is based on several modifications, which ultimately enable quick and easy maintenance, even if it still requires human intervention as before.

[0022] The present invention relates to a caustic filter unit capable of filtering out ferrous residues, iron precipitates and any other impurities from an electrolyte solution coming from an electrolysis unit, comprising:

[0023] - a tank body extending along a main direction of vertical extension, or along a main direction of horizontal extension, or along any main direction of extension between a horizontal plane and a vertical plane defined by reference systems V, L, T, and comprising a side wall and an upper face, the upper face having an opening, the side wall having a gasket on a supporting edge placed at a distance E from the opening, and

[0024] - a cover that can cooperate with the upper surface of the tank to close the opening,

[0025] - a filter basket having an upper face and a peripheral lip capable of resting on a gasket,

[0026] The alkali liquid filtration unit is characterized in that the alkali liquid filtration unit further comprises:

[0027] - A supporting edge capable of exerting pressure on the upper face of the filter basket.

[0028] The lye filtration unit may further comprise a fastening support extending substantially in a first horizontal plane P1 and capable of securely receiving at least one bar magnet on a lower face, to which a supporting edge is fixed and whose lower part extends in a second horizontal plane P2.

[0029] The alkali filtering unit may further comprise a compression element which is placed between the fastening support and the cover and which is capable of being compressed when the cover is in the closed position.

[0030] The compression element may include an upper plate and at least one spring extending vertically between the upper plate and the fastening support.

[0031] The sum of the spacing H between the planes P1 and P2 and the height h of the compression element when in the compressed state may be substantially equal to the distance E: H+h=E.

[0032] The fastening support and the bearing edge may be connected by at least one vertical rod.

[0033] The alkali solution filtration unit may further comprise a pipe with a pressure reducing valve mounted on the top.

[0034] The assembly consisting of the tube and the pressure relief valve may be located in the cover.

[0035] The lye filtration unit may further comprise a cam sleeve designed to actuate the cover between the closed position and the open position.

[0036] The present invention also relates to a method for maintaining the alkali solution filter unit according to the present invention, characterized in that the method comprises the following steps:

[0037] - unlocking the cover,

[0038] - removing the cover from the upper face of the tank, under the action of the decompression of the compression element,

[0039] - placing the cover in the open position,

[0040] - removing the assembly placed in the tank, comprising the compression element, the fastening support, the bearing edge and the bar magnet(s),

[0041] - removing the filter basket placed in the tank,

[0042] - performing a maintenance operation. BRIEF DESCRIPTION OF DRAWINGS

[0043] Other characteristics and advantages of the application will become apparent on reading the following detailed description, made with reference to the attached drawings, in which:

[0044] [ Figure 1 ] is a perspective view of a lye filtering unit of the prior art;

[0045] [ Figure 2 ] is a cross-sectional view of the lye filtering unit in Figure 1 , in which the arrangement of the bar magnets and of the filter basket in the lye filtering unit is shown;

[0046] [ Figure 3 ] is a perspective view of a lye filtering unit according to the application, in which a general view is shown;

[0047] [ Figure 4 ] is a partial perspective view of the lye filtering unit in Figure 3 , in which the inside of the tank is shown, taken at a 90° angle along the axis A;

[0048] [ Figure 5 ] is a partial exploded view of the lye filtering unit in Figure 3 , in which the elements arranged inside the tank are shown;

[0049] [ Figure 6 ] is a perspective view showing the intermediate element of the lye filtering unit in Figure 3 , provided with a plurality of bar magnets;

[0050] [ Figure 7 ] is an enlarged view of the upper portion of Figure 6 , in which the intermediate element is shown;

[0051] [ Figure 8 ] is a partial perspective view of the lye filtering unit in Figure 3partial perspective view of the lye filtration unit in the tank 10 in the closed position, in which the cover is shown in the locked position;

[0052] [ Figure 9 ] is a 90° angular section taken along the axis A of the Figure 3 partial perspective view of the lye filtration unit in the tank 10 in the closed position, in which the cover is shown in the unlocked position;

[0053] [ Figure 10 ] is a 90° angular section taken along the axis A of the Figure 3 partial perspective view of the lye filtration unit in the tank 10 in the closed position, in which the cover is shown in the open position;

[0054] [ Figure 10 ] is a 90° angular section taken along the axis A of the Figure 3 partial perspective view of the lye filtration unit in the tank 10 in the closed position, in which the cover is shown in the open position; DETAILED DESCRIPTION

[0055] For the purposes of describing the present application and understanding the claims, the vertical, longitudinal and transversal orientations will be adopted, by way of non-limiting indication and without being limited to, with reference to the terrestrial gravity, according to the reference system V, L, T indicated in the drawings, whose longitudinal axis L and transversal axis T extend in a horizontal plane. By convention, the vertical axis V is oriented from bottom to top and the longitudinal axis L is oriented from back to front.

[0056] In the following description, identical, similar or analogous elements will be indicated by the same reference numerals.

[0057] The present application relates to a lye filtration unit 10, which is able to filter out ferrous residues, iron precipitates and any other impurities from an electrolyte solution coming from an electrolysis unit.

[0058] Figure 3 The lye filtration unit 10 according to the present application is shown in the tank 10. The lye filtration unit 10 comprises a tank body 12, which extends between a lower face 14 and an upper face 16 along a vertical extension main direction A.

[0059] The tank body 12 comprises a lateral wall 18. The tank body 12 is generally in the shape of a cylinder having an axis A and a circular section. The lateral wall 18 is curved and extends around the circumference of the cylinder formed by the tank body 12. The lateral wall 18 is parallel to the axis A. Any other geometric configuration defining the lateral wall 18 is described in the present application, provided that the technical features related to the lateral wall are independent of the geometric configuration.

[0060] In order to be able to access the interior of the tank 12, for example in order to intervene by an operator, the upper face 16 has an opening 20. The caustic filtration unit 10 comprises a lid 22 which can cooperate with the upper face 16 of the tank 12 in order to close the opening 20 and to be able to seal the tank 12 in a gas-tight manner.

[0061] The tank 12 has a caustic inlet orifice 24 and a caustic outlet orifice 26. Thus, the caustic coming from the electrolysis unit is introduced into the tank 12 of the caustic filtration unit 10 via the caustic inlet orifice 24. The caustic introduced into the tank 12 via the caustic inlet orifice 24 flows through the tank 12 to be filtered and flows out again via the caustic outlet orifice 26. The caustic, after being filtered, can be reinjected into the electrolysis unit. The caustic inlet orifice 24 and the caustic outlet orifice 26 are located in the lateral wall 18. The caustic inlet orifice 24 and the caustic outlet orifice 26 can for example be positioned one above the other. The caustic inlet orifice 24 and the caustic outlet orifice 26 can also be located in diametrically opposite positions, or can have any desired orientation. Preferably, the caustic inlet orifice 24 is located in the upper part of the lateral wall 18 and the caustic outlet orifice 26 is located in the lower part of the lateral wall 18, in order to allow the caustic flow to flow under gravity.

[0062] In order to implement the circulation of the caustic, the caustic filtration unit 10 comprises:

[0063] - a caustic inlet duct 28 which opens into the interior of the tank 12, and

[0064] - a caustic outlet duct 30 which opens to the outside of the tank 12.

[0065] The caustic inlet duct 28 is fluidly connected to the caustic inlet orifice 24 in the lateral wall 18.

[0066] The caustic outlet duct 30 is fluidly connected to the caustic outlet orifice 26 in the lateral wall 18.

[0067] The caustic can circulate in a closed circuit between the electrolysis unit and the caustic filtration unit 10. The caustic delivered into the caustic inlet duct 28 comes from the electrolysis unit. The caustic which is evacuated from the caustic outlet duct 30 can be redirected towards the electrolysis unit, possibly after additional treatment.

[0068] In this example, the caustic outlet duct 30 has a portion of reduced section 32 which decreases along the caustic evacuation direction, which in this case corresponds to the direction indicated by the longitudinal vector L. The diameter of this portion of reduced section 32 decreases linearly between a maximum diameter B and a minimum diameter C along the direction L. The minimum diameter C substantially corresponds to the diameter D of this section of the inlet duct 28.

[0069] The caustic filtration unit 10 has a purge orifice 34 located in the lower face 14 of the tank 12.

[0070] The tank 12 has a horizontal fastening disc 36 protruding from the outer face of the side wall 18 of the tank 12. The tank 12 also has fins 38 which form abutments and extend vertically along the side wall 18 from the upper face of the fastening disc 36.

[0071] The lye filtering unit 10 has a base 40 with at least two feet 42. The top of each foot 42 is fitted with a threaded rod 44. Each threaded rod 44 passes through a fastening orifice 46 provided in the fastening disc 36. The fastening orifices 46 are regularly distributed along the fastening disc 36. In the non-limiting example described in Figure 3 , when four feet 42 are considered, this corresponds to the four corners of a square. Nuts 48 screwed onto the threaded rods 44 on either side of the fastening orifices 46 make it possible to locally adjust the height of the tank 12. Washers can be added between the fastening disc 36 and the nuts 48 in order to more finely adjust the height of the tank 12.

[0072] The base also has a horizontal base 50 configured to have any geometric shape, the base 50 being provided with a weight 52 protruding from the base 50 in the horizontal plane of the base. In the non-limiting example described in Figure 3 , the base has an annular shape, while the weight 52 is T-shaped, the foot of the T being fastened to the base 50.

[0073] With reference to Figure 4 and Figure 5 , the lye filtering unit 10 has a filter basket 54 in any geometric shape, the filter basket supporting an internal screen consisting of a close metal mesh and delimiting a cavity 56 extending along the vertical direction A. In the non-limiting example described in Figure 4 and Figure 5 , the filter basket 54 has a cylindrical shape with an axis A. The filter basket 54 has an upper face 58 delimiting a central opening 60. The upper face 58 of the filter basket 54 also has a peripheral lip 62 which can rest on a spacer 64 protruding from the internal face of the side wall 18. The upper part of the spacer 64 can have a vertical positioning rod 65 for accurately positioning the filter basket 54 on the spacer 64. The filter basket 54 then has an orifice for receiving the vertical rod 65. The upper face 58 of the filter basket 54 is positioned at a distance E from the opening 20, this distance corresponding to the height between the lye inlet orifice 24 and the lye outlet orifice 26. Preferably, the upper face 58 of the filter basket 54 is located directly below the inlet orifice 24, as shown in Figure 4 . Thus, the lye flowing into the tank 12 will rush into the cavity 56, flow through the wall of the filter basket 54 and exit via the lye outlet orifice 26.

[0074] According to one feature of the application, the lye filtering unit 10 has, between the filter basket 54 and the lid 22, an intermediate element 66 of any geometry, so that the pressure exerted by the lid 22 on the intermediate element 66 can be transmitted to the filter basket 54.

[0075] The intermediate element 66 is depicted in a non-limiting manner, but more particularly in Figure 6 and Figure 7 The intermediate element 66 has a bearing edge 68 which rests on the upper face 58 of the filter basket 54 when the intermediate element 66 is in place in the tank 12. In this example, the bearing edge 68 is annular. The shape of the bearing edge 68 is similar to that of the upper face 58 of the filter basket 54. In variants, the bearing edge 68 can have a discontinuous shape so as to exert pressure only at certain points of the upper face 58 of the filter basket 54.

[0076] According to one advantageous embodiment of the application, the lye filtering unit 10 has a fastening support 70 of any geometry, capable of receiving at least one bar magnet 72 intended to be fastened to a lower face 74 of the fastening support 70. In a non-limiting example, the fastening support 70 is a disc which has been hollowed out to form a central cross strut 75. In variants, the fastening support 70 can be a solid disc. The lower face 74 of the fastening support 70 extends substantially in the first horizontal plane PI.

[0077] In the example shown, the lye filtering unit 10 has four bar magnets 72. In variants, the lye filtering unit 10 can have a different (higher or lower) number of bar magnets 72, or even none. Each bar magnet 72 is fastened to the lower face 74 of the fastening support 70 and extends downwards when the fastening support 70 is in place in the tank 12. In the example, each bar magnet 72 is fastened to the arm of the cross strut 75 by means of a circlip pin. In variants, each bar magnet 72 can be fastened by means of a screw, the head of which is located above the fastening support 70, while the threaded part is screwed into a complementary orifice in the upper face of the bar magnet 72. In the case where the bar magnets 72 are distributed on each arm of the cross strut 75, they are arranged in a square centred on the axis A. This approach can be modified by considering any bar magnet 72 (as long as the device contains one) positioned randomly (ranging from zero to at least one) on each arm of the cross strut 75, both in terms of the total number of bar magnets 72 and in terms of the number of bar magnets 72 on each arm of the cross strut 75. The bar magnets 72 make it possible to capture magnetic particles, whatever their size.

[0078] In the illustrated embodiment, the fastening support 70 is integrated into the intermediate element 66. The intermediate element 66 is in the form of a cylindrical cage formed with:

[0079] - an upper ring comprising the fastening support 70 extending in a first horizontal plane P1, and

[0080] - a lower ring comprising the bearing rim 68 extending in a second horizontal plane P2 located below the first horizontal plane P1.

[0081] The upper and lower rings have the same shape and the same dimensions, except for the central cross strut 75. The intermediate element 66 also comprises four vertical side struts 76 of equal length. The struts 76 are distributed along the lower and upper rings and are designed to hold the bearing rim 68 and the fastening support 70 horizontal and parallel to each other. In variants, the fastening support 70 and the bearing rim 68 can be connected by a different (fewer or greater) number of struts 76. Thus, within the intermediate element 66, the bearing rim 68 is fixed to the fastening support 70.

[0082] The intermediate element 66 is, for example, metallic.

[0083] The lye filtration unit 10 also comprises a compression element 78 positioned between the fastening support 70 and the lid 22 and able to be compressed when the lid 22 is in the closed position. The compression element 78 can be part of the intermediate element 66 or a separate element.

[0084] The spacing H between the planes P1 and P2 is substantially equal to the sum of the height h of the compression element 78 when in the compressed state and the distance E: H + h = E.

[0085] According to a preferred embodiment, the compression element 78 has an upper plate 80 and six springs 82 extending vertically between the upper plate 80 and the fastening support 70. The upper plate 80 is a disc whose center is hollowed out and extends in a horizontal plane located above the planes P1 and P2. The upper plate 80 is of the same shape and has the same dimensions as the lower ring comprising the bearing rim 68. In variants, the upper plate 80 can be a solid disc or have cross struts similar to the fastening support 70. The springs 82 are regularly distributed under the upper plate 80. In variants, the number of springs 82 can vary, with the number of springs being greater than or less than the number mentioned in the above example.

[0086] The springs 82 are able to store the energy transmitted to them when compressed and release the energy when the lid 22 is unscrewed, causing the lid 22 to be slightly raised. Figure 8 and Figure 9 This phenomenon is demonstrated.

[0087] InFigure 8 In this position, the lid 22 is locked so that the spring 82 is compressed and the lid 22 is in contact with the upper face 16 of the tank 12.

[0088] In this position, the lid 22 is unlocked, the spring 82 releases its energy and expands. Under the action of the spring 82, the lid 22 is slightly raised relative to the upper face 16 of the tank 12. Figure 9 In this position, the lid 22 is unlocked, the spring 82 releases its energy and expands. Under the action of the spring 82, the lid 22 is slightly raised relative to the upper face 16 of the tank 12.

[0089] The screw defined between the upper face 16 of the tank 12 and the lid 22 has already played a locking role. The tabs 83 and 85 are intended for equipotential connection.

[0090] In variants, the locking system is a peg fixed to the lid 22, which can be retained in a pivotable hook fastened to the tank 12, or a peg that is translatable and can be housed in a recess of the tank 12. A magnetic locking can also be envisaged.

[0091] The pressure inside the tank 12 can be different from atmospheric pressure. In order to allow the inside of the tank 12 to return to atmospheric pressure, the lye filtration unit 10 also comprises a tube 84, commonly called a "nozzle", provided at the center of the outer face of the lid 22. A pressure relief valve (not shown in the figures) is attached above this tube 84. The return of the tank 12 to atmospheric pressure makes it easier to open the lid and avoids any risk of splashing.

[0092] Unlike the filtration units of the prior art, the lye filtration unit 10 of the invention has been improved since the bar magnet 72 is not fastened to the lid 22, so that the lid 22 can be pivoted to open the opening 20 without having to lift the lid 22. In particular, the rod no longer hinders the pivoting of the lid 22. Reference will be made to Figure 10 and Figure 11 This improvement is described more particularly.

[0093] The lye filtration unit 10 has a cam sleeve 86 designed to actuate the lid 22 between a closed position and an open position. The cam sleeve 86 has a hollow cylindrical portion 88 which forms a cam by means of two diametrically opposed notches 90 provided in the lower face of the cylindrical portion 88.

[0094] The cam sleeve 86 also has a T-shaped tube 92 mounted in the cylindrical portion so that the vertical stem of the T-shaped tube passes through the cylindrical portion 88. The tube 92 is for example welded or adhesively bonded in the cylindrical portion 88. One end of the horizontal stem of the T-shaped tube 92 is fastened to the side face of the lid 22. The tube 92 is fastened to the lid 22, for example by interlocking, welding, adhesively bonding or by any other fastening means not listed above.

[0095] The lye filtering unit 10 has a support 94 in the form of a hollow cylinder which can receive the lower portion of the tube 92. The support 94 is fastened to the lateral wall 18 of the tank body 12 via horizontal fastening arms 96. The horizontal fastening arms 96 are for example welded or adhesively bonded to the tank body 12. The cam sleeve 86 can then pivot in the support 94 about the axis of the tube 92.

[0096] The support 94 has an upper face which is complementary in shape to the lower face of the cylindrical portion 88. When the cover body 22 is in its closed position, the upper face of the support 94 exactly conforms to the lower face of the cylindrical portion 88, so that the top end of the support 94 is housed in the recess 90 in the cylindrical portion 88.

[0097] When the cover body 22 is pivoted about the axis of the tube 92 through 90° relative to the closed position, the top end of the support 94 is positioned opposite the bottom end of the cylindrical portion 88, so that the height I by which the cover body 22 is lifted is equal to twice the height i of the recess in the cylindrical portion 88. Thus, according to the working principle of the cam, the rotational movement about the axis of the tube 92 is accompanied by a translational movement along the axis of the tube 92.

[0098] The lye filtering unit 10 according to the application makes it possible to implement a less risky and less tricky method of maintenance. The method for maintaining the lye filtering unit 10 comprises the following steps.

[0099] The operator, when he wishes to clean the elements of the lye filtering unit 10, performs a first step which consists in unlocking the cover body 22, for example by removing the screw which holds the cover body 22 closed.

[0100] After the cover body 22 has been unlocked, the cover body 22 is automatically detached from the upper face 16 of the tank body 12 under the effect of decompression of the compression element 78, for example under the pushing action of the spring 82. The lye filtering unit 10 is then in the state shown. Figure 9

[0101] The operator can then easily manually pivot the cam sleeve 86 in the support 94 in order to place the cover body 22 in its open position. The cover body 22 is then offset to the side in order to open the opening 20 and to lift the cover body to a height I above the tank body 12, as shown. Figure 10

[0102] The operator then removes the assembly which is placed in the tank body 12, this assembly comprising the compression element 78, the fastening support 70 and the bearing rim 68, in order to release the filter basket 54 and to remove the bar magnet(s) 72.

[0103] The operator can then remove the filter basket 54 from the tank body 12.

[0104] ​​The operator can then clean the group of elements that make up the lye filter unit 10.

[0105] After the maintenance operation has been completed, in order to return the lye filter unit 10 to the operating condition, the operator needs to replace the filter basket 54 and carefully place the vertically positioned rod 65 into the corresponding receiving orifice in the filter basket 54. Then, when the intermediate element 66 is one piece, the operator replaces the intermediate element, which comprises the support rim 68, the fastening support 70 and the compression element 78. When the intermediate element 66 is not one piece, the operator needs to replace the support rim 68, the fastening support 70 and the compression element 78 in succession.

[0106] Finally, the operator pivots the lid 22 with the aid of the cam sleeve 86 until the lid is in the closed position and finally locks the lid 22 by screwing the screw back into the nut, so that the lid 22 remains pressed against the upper face 16 of the tank 12.

[0107] The improvement based on the compression and decompression of the internal spring 82 makes it easier to open the lid 22, to keep the bar magnet(s) 72 and to keep the filter basket 54. After opening the lid 22, the human effort is greatly reduced because:

[0108] i) the bar magnet(s) 72 are partially lifted away from the lye filter unit 10 and are no longer associated with the lid 22, and

[0109] ii) the filter basket 54, which is also partially lifted, is more easily accessible, since it is no longer attached to the sidewall 18 of the lye filter unit 10 by a screw, but is kept under pressure only by the force of the intermediate element 66, which is located vertically above the filter basket when the lid 22 is closed.

[0110] Opening the lid 22 is also made easier thanks to the addition of the following two essential elements:

[0111] i) the tube 84 provided at the center of the outer face of the lid 22 and topped with a decompression valve, and

[0112] ii) the cam sleeve 86.

[0113] The assembly consisting of the tube 84 and the decompression valve makes it possible to gradually decompress the lye filter unit 10, so that it is not faced with the excessively violent opening and the excessively rapid lifting of the internal components (the bar magnet(s) 72 and the filter basket 54) with splashing.

[0114] The cam sleeve 86 makes it easier to control the opening of the lid 22, since the lid no longer needs to be lifted as before, but is moved in translation and in rotation with the aid of this cam sleeve 86, which gradually loosens after a slight vertical pulse to remove it from its recess.

[0115] Nevertheless, the preferred embodiments described above make it possible to consider any desired orientation of the lye filtration unit 10. Thus, the lye filtration unit can be arranged along a horizontal extension main direction, or any extension main direction defined between a horizontal plane and a vertical plane by the reference system V, L, T. Regardless of the orientation followed, all the technical features described in the description relating to the geometry of the lye filtration unit 10 and the constituent elements of the application (fastening support 70, compression element 78, bar magnet 72, filter basket 54, etc.) remain the same to give the same set of results.

Claims

1. A lye filtration unit (10) capable of filtering out ferrous residues, iron precipitates and any other impurities from an electrolyte solution coming from an electrolysis unit, the lye filtration unit (10) comprising: - a tank body (12) extending along a vertically extending main direction (A), or along a horizontally extending main direction, or along any extending main direction defined between a vertical plane and a horizontal plane by a reference system V, L, T, and comprising a lateral wall (18) and an upper face (16) having an opening (20), and the lateral wall (18) having a gasket (64) on a support edge (68) placed at a distance E from the opening (20), and - a cover body (22) capable of cooperating with the upper face (16) of the tank body (12) to close the opening (20), - a filter basket (54) having an upper face (58) and a peripheral lip (62) capable of resting on the gasket (64), - a support edge (68) capable of exerting a pressure on the upper face (58) of the filter basket (54), - a fastening support (70) extending substantially in a first horizontal plane PI and capable of firmly receiving at least one bar magnet (72) on a lower face (74), the support edge (68) being fixed to the fastening support (70) and the lower part of the support edge extending in a second horizontal plane P2, the lye filtration unit (10) being characterized in that it further comprises: - a compression element (78) placed between the fastening support (70) and the cover body (22) and capable of being compressed when the cover body (22) is in a closed position.

2. The caustic filtration unit (10) according to claim 1, characterized in that The compression element (78) comprises an upper plate (80) and at least one spring (82) extending vertically between the upper plate (80) and the fastening support (70).

3. The lye filter unit (10) according to claim 1 or 2, characterized in that The sum of the distance H between the planes PI and P2 and the height h of the compression element (78) in the compressed state is substantially equal to the distance E: H + h = E.

4. The caustic filtration unit (10) according to any one of claims 1 to 3, characterized in that The fastening support (70) and the support edge (68) are connected by at least one vertical rod (76).

5. The lye filtration unit (10) according to any one of the preceding claims, characterized in that The lye filtration unit further comprises a tube (84) on which a pressure relief valve is mounted.

6. The caustic filtration unit (10) according to the preceding claim, characterized in that The assembly constituted by the tube (84) and the pressure relief valve is located in the cover body (22).

7. The lye filtration unit (10) according to any one of the preceding claims, characterized in that The lye filtration unit comprises a cam sleeve (86) designed to actuate the cover body (22) between a closed position and an open position.

8. A method for maintaining the lye filter unit (10) as claimed in claim 1, characterized in that, The method comprises the following steps: - unlocking the cover body (22), - detaching the cover body (22) from the upper face (16) of the tank body (12) under the effect of the decompression of the compression element (78), - placing the cover body (22) in the open position, - placing the cover body (22) in the open position, - removing the assembly placed in the tank body (12), said assembly comprising the compression element (78), the fastening support (70) and the bearing edge (68), - removing the filter basket (54) placed in the tank body (12), - performing maintenance operations.

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