Lye outlet within a lye filter

Abstract

The present invention relates to a lye filtering unit (10) capable of filtering ferrous residues and iron precipitates as well as any other substance present in an electrolyte solution coming from an electrolysis unit, the lye filtering unit (10) comprising: - a tank (12) extending in a main direction of vertical elongation (A) and comprising a side wall (18); - an inlet pipe (44) for lye to enter the tank (12); and - an outlet pipe (46) for lye to exit the tank (12), the lye filtering unit (10) being characterised in that the lye outlet pipe (46) has a portion of decreasing cross-section (48) in the lye discharge direction.

Description

[0001] DESCRIPTION

[0002] TITLE: Lye outlet within the lye filter

[0003] Technical field of the invention

[0004] The present invention relates to a lye filtering unit capable of filtering ferrous residues and iron precipitates as well as any other impurities present in an electrolyte solution resulting from an electrolysis unit, for example for the production of dihydrogen (H2) and dioxygen (02).

[0005] The invention relates more particularly to a lye filtering unit designed to facilitate its maintenance.

[0006] Technical background

[0007] The lye filter, also called a lye filter unit, is used to filter ferrous residues, iron precipitates and any other impurities present, even in negligible quantities.

[0008] Figures 1 and 2 show a lye filtering unit 100 according to the prior art. The lye filtering unit 100 comprises a tank 12 having a lye inlet pipe 44 and a lye outlet pipe 46 as well as two impurity capture elements placed in the tank 12 including i) at least one magnetic bar 28 for recovering magnetic particles (regardless of size), and ii) a basket 30 supporting an inner screen formed of a tight metal mesh dedicated to capturing non-magnetic particles (regardless of size).

[0009] Following this molecule capture action, the lye 100 filter must be cleaned of these iron agglomerates and / or any other substance on a recurring basis to maintain the efficiency of the system. All iron agglomerates, minority substances and filtered molecules are considered impurities.

[0010] This maintenance operation is quite heavy and not easy, given the mass and steric bulk of the lye filter 100 as well as those linked to the magnetic bar(s) 28 and the basket 30 within the lye filter 100. The elements making the maintenance operation difficult are the following: i) the basket 30 containing a sieve formed of a tight metal mesh, extremely heavy, which is fixed using screws on a wedge of the side wall of the lye filter 100 and which is characterized by the fact that the bottom is located near the lower end of the lye filter 100, and ii) the magnetic bar(s) 28 which is (are) directly fixed on the cover of the lye filter 100, the cover being surmounted by at least one handle necessary to lift the assembly composed of the cover and the magnetic bar(s) 28.

[0011] Conventionally, the lye inlet pipe 44 and the lye outlet pipe 46 are similar in shape and size. As shown in Figures 1 and 2 of the prior art, the lye inlet pipe 44 and the lye outlet pipe 46 are cylindrical, with a circular and constant cross-section. The cross-section of the lye inlet pipe 44 and the cross-section of the lye outlet pipe 46 have identical dimensions. Due to the friction and resistance to the flow of lye induced by the elements inside the tank 12, a pressure drop is observed between the lye inlet pipe 44 and the lye outlet pipe 46. Thus, the pressure in the lye outlet pipe 46 is lower than the pressure in the lye inlet pipe 44, a completely consistent physical phenomenon.

[0012] Added to this is the fact that the junction between the lye inlet pipe 44 or the lye outlet pipe 46 and the tank 12 exceptionally exhibits leaks insofar as the sealing of the junction is not always absolute following a failure identified at the weld between the lye inlet pipe 44 or the lye outlet pipe 46 and the tank 12. The leaks accentuate the pressure losses between the lye inlet pipe 44 and the lye outlet pipe 46.

[0013] The pressure drops between the lye inlet pipe 44 and the lye outlet pipe 46 are detrimental to the proper operation of the lye filter unit 100. In particular, they cause an accumulation of impurities near the lye outlet pipe 46, which fouls the basket 30 locally and impairs filtration. The fouling of the basket 30 near the outlet requires a maintenance operation on the lye filter unit 100 to clean the basket 30.

[0014] Summary of the invention

[0015] The invention relates to a lye filtering unit capable of filtering ferrous residues and iron precipitates as well as any other impurities present in an electrolyte solution resulting from an electrolysis unit, the lye filtering unit comprising:

[0016] - a tank extending along either a main direction of vertical elongation, or a main direction of horizontal elongation, or any main direction of elongation between the horizontal and vertical planes defined according to the reference V, L, T, and comprising a side wall,

[0017] - a lye inlet pipe into the tank, and

[0018] - a lye outlet pipe from the tank, the lye outlet pipe having a portion of decreasing section according to the direction of lye discharge.

[0019] The lye inlet line may be fluidically connected to an inlet port in the side wall.

[0020] The outlet pipe can be fluidically connected to an outlet port in the side wall.

[0021] The outlet pipe may be located below the inlet pipe.

[0022] The outlet pipe may have a funnel shape, so that, thanks to the widening of the outlet pipe in contact with the tank, the lye can be extracted at a significant speed without carrying any impurity since the latter is eliminated in the tank beforehand.

[0023] The decreasing section portion may have a circular section.

[0024] The diameter of the decreasing section portion can decrease linearly.

[0025] The length of the decreasing section portion along the lye discharge direction may be equal to the minimum diameter of the decreasing section portion multiplied by a coefficient. The maximum diameter of the decreasing section portion may be equal to the minimum diameter of the decreasing section portion multiplied by a coefficient.

[0026] The minimum diameter of the decreasing section portion may be equal to the diameter of the section of the inlet pipe.

[0027] Brief description of the figures

[0028] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

[0029] [Fig.1] is a perspective view of a prior art lye filter unit;

[0030] [Fig.2] is a schematic sectional view of the lye filter unit of Fig. 1 showing the arrangement of the magnetic bar and basket in the lye filter unit;

[0031] [Fig.3] is a perspective view of a lye filtering unit according to the invention showing the outlet pipe having a portion of decreasing section;

[0032] [Fig.4] is a cross-sectional view of the lye filter unit of Fig. 3 showing the respective shapes of the inlet and outlet pipes,

[0033] [Fig.5] is a schematic and partial view of the interior of the tank showing one end of the magnetic bar of the lye filter unit of Figure 3.

[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 reference V, L, T indicated in the figures, the longitudinal L and transverse T axes of which extend in a horizontal plane, will be adopted as a non-limiting example and without limiting reference to Earth's gravity. By convention, the vertical axis V is oriented from bottom to top and the longitudinal axis L is oriented from back to front. In the description which follows, identical, similar or analogous elements will be designated by the same reference numbers.

[0036] The invention relates to a lye filtering unit 10 capable of filtering ferrous residues and iron precipitates as well as any other impurities in an electrolyte solution from an electrolysis unit.

[0037] A lye filtering unit 10 according to the invention is shown in Figure 3. The lye filtering unit 10 comprises a tank 12 extending in a main direction of vertical elongation A between a lower face 14 and an upper face 16.

[0038] The tank 12 comprises a side wall 18. The tank 12 has a generally cylindrical shape with axis A and a circular section. The side wall 18 is curved and extends along the circumference of the cylinder formed by the tank 12. The side wall 18 is parallel to the axis A. Any other geometric configuration defining the side wall 18 falls within the description of the present invention given that the technical characteristics associated with the latter are independent of the geometric configuration.

[0039] To allow access to the interior of the tank 12, for example for the intervention of an operator, the upper face 16 has an opening 20. The lye filtering unit 10 has a cover 22 capable of cooperating with the upper face 16 of the tank 12 to close the opening 20 and allow the tank 12 to be hermetically closed.

[0040] The tank 12 has a lye inlet orifice 24 and a lye outlet orifice 26. Thus, the lye coming from the electrolysis unit is introduced into the tank 12 of the lye filtering unit 10 through the lye inlet orifice 24. The lye introduced into the tank 12 through the lye inlet orifice 24 passes through the tank 12 to be filtered and exits through the lye outlet orifice 26. The lye, once filtered, can be reinjected into the electrolysis unit. The lye inlet orifice 24 and the lye outlet orifice 26 are placed in the side wall 18. The lye inlet orifice 24 and the lye outlet orifice 26 can be positioned, for example, one above the other. The lye inlet 24 and lye outlet 26 ports may also be positioned in diametrically opposite positions or may have any orientations.Preferably, the lye inlet orifice 24 is located in an upper portion of the side wall 18 and the lye outlet orifice 26 is located in a lower portion of the side wall 18 to allow the flow of the lye stream by gravity.

[0041] Referring to Figures 4 and 5, the lye filter unit 10 comprises at least one magnetic bar 28 extending vertically, between the inlet orifice 24 and the outlet orifice 26. The magnetic bar 28 is advantageously fixed on a lower face of the cover 22 and extends downwards when the cover 22 is positioned to close the opening 20.

[0042] With this arrangement, the lye flowing from the inlet orifice 24 to the outlet orifice 26 encounters the magnetic bar 28 whose magnetic field allows the capture of magnetic particles. As understood, the magnetic bar 28 ensures an extraction of magnetic particles which may be bathed in the lye entering the tank 12 through the inlet orifice 24, before its reinjection into the circuit of the electrolysis unit through the outlet orifice 26.

[0043] The lye filtering unit 10 comprises a basket 30 delimiting a cavity 32 extending in the vertical direction A. The basket 30 has a cylindrical shape of axis A. The basket 30 comprises an upper face 34 delimiting a central opening 36 capable of receiving the magnetic bar 28. The upper face 34 of the basket 30 also comprises a peripheral rim 38 capable of resting on a wedge 40 projecting from an internal face of the side wall 18. The upper face 34 of the basket 30 is placed here at mid-height in the tank 12 between the lye inlet orifice 24 and the lye outlet orifice 26. Thus, the lye entering the tank 12 flows into the cavity 32, passes through the walls of the basket 30 and exits through the lye outlet orifice 26.

[0044] The lye filter unit 10 has a purge orifice 42 placed in the lower face 14 of the tank 12.

[0045] To allow the circulation of the lye, the lye filter unit 10 comprises:

[0046] - an inlet pipe 44 for lye in tank 12, and

[0047] - an outlet pipe 46 for lye from the tank 12.

[0048] The lye inlet line 44 is fluidly connected to the lye inlet port 24 in the sidewall 18. The lye outlet line 46 is fluidly connected to the lye outlet port 26 in the sidewall 18.

[0049] Lye may circulate in a closed circuit between the electrolysis unit and the lye filter unit 10. Lye fed into the lye inlet pipe 44 comes from the electrolysis unit. Lye discharged into the lye outlet pipe 46 is redirected to the electrolysis unit, potentially after further treatment.

[0050] According to a characteristic of the invention, the lye outlet pipe 46 has a portion of decreasing section 48 in the direction of evacuation of the lye which here corresponds to the direction pointed by the longitudinal vector L, this decreasing section 48 being preceded by a proximal portion 56, placed between the tank 12 and the portion of decreasing section 48, of a size greater than the decreasing section 48 as well as the lye inlet section 44. The outlet pipe 46 further comprises a distal portion 58 which extends the portion of decreasing section 48 downstream.

[0051] This particularity of conformation of the outlet pipe 46 is recommended to serve a double interest.

[0052] On the one hand, by adopting such a progressive reduction in the cross-section of the outlet pipe 46 into which the lye enters when passing the outlet orifice 26, the decreasing cross-section 48 forms a convergent which limits the generation of singular pressure losses in comparison with a sudden reduction in cross-section, namely if the lye were directly conducted into the distal portion 58 at the outlet of the tank 12. This limitation of pressure losses makes it possible to avoid the accumulation of impurities on a portion of the basket 30 near the lye outlet pipe 46.

[0053] According to an exemplary embodiment, the lye outlet pipe 46 is located below the lye inlet pipe 44. The lye outlet pipe 46 is lower than the inlet pipe 44 to promote the flow of lye from the inlet to the outlet. Furthermore, the lye inlet pipe 44 is located vertically above the lye outlet pipe 46. This is conventionally imposed by the arrangement of the circuit connecting the lye filter unit 10 to the electrolysis unit. Alternatively, the lye inlet pipe 44 and lye outlet pipe 46 may be diametrically opposed or may have any orientations.

[0054] The outlet pipe 46 of the lye has the shape of a lying funnel, the axis of the funnel extending in the longitudinal direction L. The decreasing section portion 48 has a section 50 of circular shape.

[0055] The diameter of the decreasing section portion 48 decreases linearly along the direction L between a maximum diameter D and a minimum diameter C.

[0056] The lye outlet pipe 46 comprises a proximal portion 56 placed between the tank 12 and the portion of decreasing section 48, the proximal portion 56 being of cylindrical shape and of diameter equal to the maximum diameter D.

[0057] The distal portion 58 of the outlet pipe 46, placed downstream of the portion of decreasing section 48, is cylindrical in shape and of diameter equal to the minimum diameter C.

[0058] The length B of the decreasing section portion 48 along the lye discharge direction L is equal to the minimum diameter C of the decreasing section portion 48 multiplied by a coefficient.

[0059] The maximum diameter D of the decreasing section portion 48 is equal to the minimum diameter C of the decreasing section portion 48 multiplied by a coefficient.

[0060] The minimum diameter C of the decreasing section portion 48 is equal to the diameter E of the section of the inlet pipe 44 of the lye.

[0061] As described above, the inlet and outlet pipes are advantageously sized so that the diameter E of the inlet pipe 44, through which the lye flows into the tank 12, is smaller than the diameter D of the proximal portion 56 through which the lye is purged from the tank 12. As a direct consequence of the principle of conservation of the flow rate between the inlet and the outlet of the tank 12, this particular sizing of the proximal portion 56 of smaller diameter than the inlet pipe 44 leads to a lowering of the fluid propagation speed at the outlet of the tank compared to the case where these diameters were equal. Since the lye flows at the outlet of the tank 12 with a lower speed, the retention of the particles in the tank 12 is thereby facilitated.

[0062] As understood, this particular dimensioning exacerbates the overpressure effect upstream of the outlet pipe induced by the convergent formed by the decreasing section 48 on the retention of particles in the tank 12, while providing a favorable lye flow at the outlet of the tank 12.

[0063] It should be noted that this conformation of the proximal portion 56 with a diameter D, at the outlet orifice 26, larger than the diameter E of the section of the inlet pipe 44, at the inlet orifice 24, does not in any way cause any geometric and configurational modification of the tank 12 and, therefore, of the overall architecture of the lye filtering unit 10.

[0064] The magnetic bar 28 comprises a tip 52 fitted onto the lower end of the magnetic bar 28. The tip 52 has the shape of a hollow cylinder and also has a solid lower face 54 in contact with the basket 30 making it possible to maintain the basket 30 at a given depth and to prevent it from retracting under the effect of pressure differentials.

[0065] The preferred modes described above nevertheless allow any orientation of the lye filtering unit 10 to be considered. Thus, the latter can be arranged in a horizontal main elongation direction or any main elongation direction between the horizontal and vertical planes defined according to the reference V, L, T. Regardless of the orientation followed, all the technical characteristics associated with the geometric configurations of the lye filtering unit 10 and constituent elements of the invention (lye inlet orifice 24, lye outlet orifice 26, magnetic bars 28, basket 30, etc.) described in the description remain identical, giving a set of identical results.

Claims

AMENDED CLAIMS received by the International Bureau on July 22, 2024 (22.07.2024) CLAIMS 1. Lye filtering unit (10) capable of filtering ferrous residues and iron precipitates as well as any other impurity in an electrolyte solution resulting from an electrolysis unit, the lye filtering unit (10) comprising: - a tank (12) extending along either a main direction of vertical elongation (A), or a main direction of horizontal elongation, or any main direction of elongation between the horizontal and vertical planes defined according to a reference V, L, T, and comprising a side wall (18), - a lye inlet pipe (44) in the tank (12), the lye inlet pipe (44) being fluidically connected to a lye inlet port (24) in the side wall (18), - a lye outlet pipe (46) out of the tank (12), the lye outlet pipe (46) being fluidically connected to a lye outlet orifice (26) in the side wall (18), - a basket (30) delimiting a cavity (32) extending in the main direction of elongation (A), the basket (30) comprising an upper face (34) which is placed between the lye inlet orifice (24) and the lye outlet orifice (26), the lye filtering unit (10) being characterized in that the lye outlet pipe (46) has a portion of decreasing section (48) in the direction of lye discharge.

2. Lye filtering unit (10) according to claim 1, wherein: - the outlet pipe (46) comprises a proximal portion (56) crossed by the lye before the portion of decreasing section (48) at the passage of the outlet orifice (26); - the diameter (D) of the proximal portion (56) of the outlet pipe (46) is greater than the diameter (E) of the inlet pipe (44).

3. Lye filter unit (10) according to any one of the preceding claims, characterized in that the lye outlet pipe (46) is located below the lye inlet pipe (44). AMENDED SHEET (ARTICLE 19) 4. Lye filter unit (10) according to any one of the preceding claims, characterized in that the lye outlet pipe (46) has a funnel shape.

5. Lye filtering unit (10) according to any one of the preceding claims, characterized in that the decreasing section portion (48) has a circular section (50).

6. Lye filtering unit (10) according to the preceding claim, characterized in that the diameter of the decreasing section portion (48) decreases linearly.

7. Lye filtering unit (10) according to claim 5, characterized in that the minimum diameter (C) of the decreasing section portion (48) is equal to the diameter (E) of the section of the lye inlet pipe (44). AMENDED SHEET (ARTICLE 19)

Images