EP4667423A1

EP4667423A1 - Sacrificial electrode, piping connection structure and method for applying sacrificial electrode

Info

Publication number: EP4667423A1
Application number: EP24183400.1A
Authority: EP
Inventors: Tsuyoshi Hamada; Koji Kawanishi; Yosuka Morita
Original assignee: ThyssenKrupp Nucera AG and Co KGaA; Tosoh Corp
Current assignee: ThyssenKrupp Nucera AG and Co KGaA; Tosoh Corp
Priority date: 2024-06-20
Filing date: 2024-06-20
Publication date: 2025-12-24
Also published as: WO2025262111A1

Abstract

The present invention relates to a sacrificial electrode (10) for arrangement between adjacent conductive and non-conductive pipes (52, 54) to flow electrolyte to or from electrolysis cells, adjoining ends of the pipes (52, 54) being provided with flanges (52A, 54A), respectively. The sacrificial electrode (10) comprises a body (12) configured to be disposed within the non-conductive pipe and/or the conductive pipe (52, 54), a mounting flange (14) extending from the body (12) so as to be detachably sandwiched in a sealed manner between the flanges (52a,54a) of the adjacent conductive and non-conductive pipes (52, 54), and a conductive member (16) configured to electrically connect the mounting flange (14) to the conductive pipe (52).

Description

Technical Field

The invention relates to a sacrificial electrode for arrangement between adjacent conductive and non-conductive pipes to flow electrolyte to or from electrolysis cells of an electrolyser. The invention also relates to a piping connection structure for such an electrolyser. Further, the invention relates to a method for applying such a sacrificial electrode to such a piping connection structure.

Background

Sacrificial electrodes are known in the art and typically utilized in electrolysis processes. In such processes, current flowing into electrodes in the electrolysis cells may leak out to various components of the electrolyser, including electrolyte supply and discharge lines, which are also known as manifolds. Such lines may include plastic, i.e., non-conductive, pipes for the purpose of flexible connection, formation of branches, or the like. However, the leakage current may flow in the electrolyte within the non-conductive pipe, which may cause electrolytic corrosion in the neighbouring conductive pipes in fluid communication with the non-conductive pipe, particularly on the downstream side of the non-conductive pipe. As one example, the corrosion occurs due to hydrogen embrittlement. The hydrogen embrittlement tends to increase in low pH liquid. The corrosion may occur by other causes. In order to prevent or at least reduce such electrolytic corrosion, sacrificial electrodes are directly weld to the inlets and outlets of the conductive pipes. However, if the sacrificial electrode deteriorates due to the corrosion, the deteriorated electrode has to be replaced by a new electrode by cutting off the welded portions and thereafter welding the new electrode to the inner wall of the conductive pipes. These processes are time consuming and costly.
WO 2018 225 239 A1 proposes a detachable sacrificial electrode mounting structure. The sacrificial electrode mounting structure is provided with: a first pipe through which an electrolytic solution flows; a second pipe, which is formed from an insulating material and through which the electrolytic solution flows; a tubular sacrificial electrode unit, which is disposed between the first pipe and the second pipe so that the electrolytic solution flows therethrough. However, this mounting structure requires a first pipe coupling for connecting the first pipe to the sacrificial electrode unit in a liquid-tight, freely detachable manner and a second pipe coupling for connecting the second pipe to the sacrificial electrode unit in a liquid-tight, freely detachable manner. The first and second pipes are indirectly connected via a sacrificial electrode unit. This means that more than two dedicated fixing parts are required, increasing the risk of electrolyte leakage as well as leading to cumbersome replacement works.
Therefore, it is the task of the present invention to eliminate one or more of the above disadvantages.

Summary

According to the present invention, a sacrificial electrode is provided, which is for arrangement between adjacent conductive and non-conductive pipes to flow electrolyte to or from electrolysis cells, adjoining ends of the pipes being provided with flanges, respectively. The sacrificial electrode comprises: a body configured to be disposed within the non-conductive pipe and/or the conductive pipe; a mounting flange extending from the body so as to be detachably sandwiched in a sealed manner between the flanges of the adjacent conductive and non-conductive pipes; and a conductive member configured to electrically connect the mounting flange to the conductive pipe.
According to the invented sacrificial electrode, as the sacrificial electrode is not welded to the conductive pipe, it can easily be removed and replaced with a new electrode, if necessary, especially when the electrode degenerates due to corrosion. Further, since the adjacent pipes are adjoined to each other with their own flanges whilst interposing the mounting flange of the sacrificial electrode therebetween, no extra fixing parts are necessary to retain the sacrificial electrode between these pipes. This reduces the risk of electrolyte leakage as well as eases replacement works. The leakage current in the electrolyte in the non-conductive pipe may flow through the conductive member of the sacrificial electrode into the conductive pipe, leading to sacrificial electrolytic corrosion of the body of the sacrificial electrode.
According to the present invention, a piping connection structure for an electrolyser is provided, which comprises: a conductive pipe having a flange at its end; a non-conductive pipe having a flange at its end, the flange being configured to be adjoined to the flange of the conductive pipe; and a sacrificial electrode according to any one of claims 1 to 10, arranged between adjacent conductive and non-conductive pipes. The body of the sacrificial electrode is disposed within the conductive pipe and/or the non-conductive pipe. The mounting flange of the sacrificial electrode is detachably sandwiched in a sealed manner between the flanges of the adjacent conductive and non-conductive pipes. The conductive member of the sacrificial electrode electrically connects the mounting flange to the conductive pipe.
According to the present invention, a method for applying, preferably retroactively applying, a sacrificial electrode according to any embodiments of the present invention to a piping connection structure for an electrolyser, the piping connection structure including a conductive pipe and a non-conductive pipe to be adjoined to each other, adjoining ends of the pipes being provided with flanges, respectively. The method comprises steps of: disposing the body of the sacrificial electrode within the non-conductive pipe and/or the conductive pipe; sandwiching the mounting flange of the sacrificial electrode between the flanges of the adjacent conductive and non-conductive pipes; and connecting the conductive member of the sacrificial electrode to the conductive pipe.
Further preferable embodiments are given in the dependent claims.

Brief Description of the Drawings

FIG. 1 shows a part of a bipolar electrolyser comprising a plurality of electrolysis cells;
FIG. 2 shows an external view of the electrolyser;
FIG. 3 shows a piping connection structure according to an embodiment of the present invention;
FIG. 4 shows a sacrificial electrode according an embodiment of the present invention;
FIG. 5 shows a variant of the piping connection of FIG.3 which is part of the present invention;
FIG. 6 shows a sacrificial electrode according to another embodiment of the present invention;
FIG. 7 shows a piping connection structure according to another embodiment of the present invention;
FIG. 8 shows a piping connection structure according to yet another embodiment of the present invention, which includes two sets of the sacrificial electrodes shown in FIG.3; and
FIG. 9 illustrates a preferable method for applying the sacrificial electrode of FIG. 3 to establish a piping connection structure in accordance with an embodiment of the present invention.

Detailed Description

One exemplary electrolyser to which the invented sacrificial electrode may be applied is a bipolar electrolyser, such as ion-exchange membrane process electrolyser, in which a plurality of bipolar electrolysis cells are arranged in series, with an ion exchange membrane or diaphragm as a gas separator being interposed between the respective adjacent cells. So-called filter press technology may be utilized to join the adjacent cells so that there is substantially no gap between electrode elements on both sides of the separator. However, the electrolyser may be a monopolar electrolyser in which each cell has either a cathode or anode electrode element on the side (not shown).
The electrolyser in which the invented sacrificial electrode is applied may be used for Chlor-Alkali electrolysis. The sacrificial electrode is also effective for acid electrolysis such as HCl electrolysis (electrolysis of a hydrochloric acid solution), because the electrolysis cells thereof typically use Ti or Ti alloy to have durability for acid. In another example, the electrolyser may be used for alkaline water electrolysis (AWE). More generally, the electrolyser may be applicable to any electrolysis process using a plurality of unit cells arranged in series, with an electrochemical separator being interposed between the respective adjacent unit cells, which requires manifolds to supply or collect electrolyte to or from electrolysis cells.
FIG. 1 shows a cross-sectional view of an exemplary electrolyser 100 to which the invented sacrificial electrode may be applied. The electrolyser 100 includes a plurality of electrolysis unit cells 102, each of which comprises a first electrode element 102A (e.g., cathode), a second electrode element 102B (e.g., anode). Gas separators 104 are interposed between the respective adjacent cells 102. The electrolysis cell 102 further comprises a first compartment 106A (e.g. cathode chamber), a second compartment 106B (e.g., anode chamber) and current collectors to support the electrode elements. The current collectors may also be referred as part of electrode structures. The first and second compartments 106A, 106B are physically divided from each other by a rear wall or partition wall 120. The partition wall 120 faces the separators 104 over the first and second compartments 106A, 106B, and define these compartments together with the separators 104.
Each separator 104 has a first surface side and a second surface side, wherein the first surface side contacts the first compartment 106A and the second surface side contacts the second compartment 106B for electrochemically interconnecting the first compartment 106A and the second compartment 106B of the adjacent cells 102. The separator 104 may be ion-exchange membrane. Alternatively, the separator 104 may be porous diaphragm, particularly an ion-permeable diaphragm. Ion-permeable diaphragms do not allow gases generated by the electrochemical reaction to permeate, but have ion-exchange function. The separator 104 may be a polymeric porous membrane, inorganic porous membrane, woven or nonwoven fabrics, or the like.
FIG. 2 shows an external view of the electrolyser 100. Reference numeral 102 in the figure indicates the electrolysis unit cell. A plurality of tie rods 122 may be provided to apply pressure to a pressure plate 124 for moving this plate against a support plate 126 and further to between the adjacent cells 102. Instead, one or more hydraulic cylinders for moving the pressure plate 124 may be provided (not shown). Adjacent the pressure plate 124, a terminal cell 102, which functions as a cathode, is arranged. The support plate 126 is disposed on the other side of the electrolyser 100, and the other terminal cell 102 functioning as an anode is disposed adjacent to this support plate 126. The cells 102 are suspended from a cell hanger 128, which is part of a frame. A plurality of headers or manifolds 130-133 as process fluid lines are provided on both sides of the cells 102, namely a first electrolyte supply manifold 130 for supplying electrolyte (e.g. catholyte) to the first compartments 106A of the cells 102, a second electrolyte supply manifold 131 for supplying electrolyte (e.g. anolyte) to the second compartments 106B of the cells 102, a first electrolyte discharge manifold 132 for discharging the electrolyte from the first compartments 106A of the cells, and a second electrolyte discharge manifold 133 for discharging the electrolyte from the second compartments 106B of the cells 102. Each manifold is equipped with a number of nozzles 135. Similarly, the cells 102 are also equipped with nozzles 102C for the electrolyte supply and discharge, respectively. The nozzles 135 of the manifolds 130-133 are fluidly connected to the nozzles 102C of the respective cells 102 via respective tubes 140 to supply or collect the process fluid to or from the electrode cells 102.
Any of manifolds 130-133 may constitute, or connected to, the claimed conductive pipe to be prevented from the electrolytic corrosion. As discussed above, assuming that a non-conductive pipe (piping) is connected upstream of the conductive pipe and that the electrolyte as process fluid flows from the non-conductive pipe to the conductive pipe, the electrolytic corrosion is likely to occur in the vicinity of the adjoining end of the conductive pipe. For this reason, in the conventional facility, a sacrificial electrode is welded to the inner surface of the conductive pipe. However, such a sacrificial electrode need to be replaced with a new electrode, periodically or depending on the degree of corrosion, by removing or cutting the welded part. Such a replacement is cumbersome and costly. Furthermore, there is another concern regarding contamination associated with the removal of welded parts.
FIG. 3 is a diagrammatic view of a piping connection structure in accordance with an embodiment of the present invention, which comprises a sacrificial electrode in accordance with an embodiment of the present invention. In the figure, the electrolyte as process fluid flows from the left to the right, as indicted by an arrow. The piping connection structure 50 for an electrolyser (e.g., electrolyser 100) comprises a conductive pipe 52 having a flange 52A at its end and a non-conductive pipe 54 having a flange 54A at its end. These flanges 52A, 54A are configured to be adjoined and fastened to each other with fasteners such as bolts and nuts (not shown). The sacrificial electrode 10 is arranged between the adjacent conductive and non-conductive pipes 52, 54, which will be discussed immediate below.
With reference to FIG. 4, the details of the sacrificial electrode 10 can be seen. The sacrificial electrode 10 has a body 12 configured to be disposed within the non-conductive pipe 54 and/or the conductive pipe 52. The outer diameter of the body 12 is smaller than the inner diameter of the pipe(s) 52, 54 within which the body 12 is disposed.
The shape of the body 12 is not limited so long as it can be disposed within the pipe(s) 52, 54 and any shapes such as a plate, bar, hollow triangle, hollow rectangular and the like are possible, but shapes with a larger contact area with the electrolyte are preferred. In this sense, the body 12 may be formed in a cylindrical shape, preferably having an axis X12 to be aligned with the axes of the pipes 52, 54. More specifically, the body 12 has an annular wall 12a extends around the axis X12. In order to obtain a yet larger contact area with the electrolyte, the body 12 may be formed of a mesh or may have a number of through holes.
The sacrificial electrode 10 may be formed of any material exhibiting high durability during electrolysis. For example, the body of the sacrificial electrode may be formed any of:

1) a platinum group metal (platinum, ruthenium, rhodium, palladium, osmium, iridium) alone;
2) an alloy of two or more kinds of platinum group metals;
3) an alloy of a platinum group metal and another metal;
4) a mixed oxide or multiple oxide including, as constituent elements, a platinum group metal and a valve metal such as titanium/tantalum;
5) transition metals such as titanium (Ti), nickel (Ni), iron (Fe), vanadium (V);
6) metallic strontium;
7) metallic iron, metallic nickel;
8) metallic lead, lead dioxide;
9) silicon;
10)diamond or graphite;
11)oxides such as alumina, mullite and zirconia;
12)carbide such as SiC;
13)nitride such as AIN; and
14)a valve metal alone such as titanium, tantalum, and zirconium.

Alternatively, the body 12 of the sacrificial electrode 10 may be obtained by forming a catalyst layer or oxide top layer on a substrate. In this case, the substrate is made of titanium, zirconium, aluminum, tantalum, niobium, iron, nickel, lead alone, or an alloy thereof, carbon, silicon, ceramics or the like. As the catalyst, any substance exemplified in the above (1) to (12) or titanium, ruthenium, or iridium layer may be applied. The body 12 of the sacrificial electrode 10 may be formed by forming a plate blank made of the above-mentioned material into a cylindrical shape, or may be formed in a cylindrical shape by extrusion or casting.
In further preferable embodiments, the body 12 is made of titanium or titanium alloy, and more preferably of titanium-palladium alloy.
The sacrificial electrode 10 also has a mounting flange 14 extending from the body 12 so as to be detachably sandwiched in a sealed manner between the flanges 52A, 54A of the adjacent conductive and non-conductive pipes 52, 54. The mounting flange 14 may be disc-shaped. The mounting flange 14 has a first surface 14a facing the flange 54A of the non-conductive pipe 54 and a second surface 14b facing the flange 52A of the conductive pipe 52. A gasket 56, preferably annular shaped gasket, may be arranged between the first surface 14a and the flange 54A of the non-conductive pipe 54; another gasket 58, preferably annular shaped gasket, may be arranged between the second surface 14b and the flange 52A of the conductive pipe 52 (see, FIG. 3). In other words, the first and second surfaces 14a, 14b of the mounting flange 14 form sealed surfaces. The outer diameter of the mounting flange 14 is so designed as not to impede the fastening of the pipe flanges 52A, 54A by the fasteners.
In the example in FIG. 3, the radially outer edge of the mounting flange 14 is radially inwards from the holes for the bolts in the pipe flanges 52A, 54A.
The mounting flange 14 is electrically conductive. The mounting flange 14 is preferably made of titanium or a titanium alloy, more preferably a titanium-palladium alloy.
The mounting flange 14 is fixed to the body 12, e.g., by welding. Alternatively, the mounting flange 14 and the body 12 may be an integral part formed from a single blank. Such an integral part may be formed by drawing.
In the embodiment of FIG 4, the mounting flange 14 extends from an end (axial end) of the body 12 so that the body is completely disposed within either the non-conductive pipe 54 or the conductive pipe 52.
The sacrificial electrode 10 has a conductive member or connecting means 16 configured to electrically connect the mounting flange 14 to the conductive pipe 52. Preferably, the conductive member 16 includes a conductive cable or wire 16A. More preferably, the conductive member 16 includes a terminal 16B for electrically and physically connecting the conductive cable 16A to the mounting flange 14. The terminal 16B may be welded to the mounting flange 14. Additionally or alternatively, the bottom part of the terminal 16B may be screwed into the mounting flange 14. Other known terminals, such as ring terminals, spade terminals, receptacles, pin terminals, wire terminals, crimp terminals, solder terminals, and solder splices, may also be applicable. Alternatively, the connection between the conductive member 16 and the mounting flange 14 may be established by socket and plug connectors. In a further alternative, the end of the conductive cable 16A may be directly welded to the mounting flange 14 without using any terminal.
Referring back to FIG.3, the body 12 of the sacrificial electrode 10 is preferably disposed within the non-conductive pipe 54 so that the body 12 protrudes from the mounting flange 14 in the direction away from the conductive pipe 52. It also can be seen from the figure that the body 12 is so configured to be coaxially disposed with respect to the non-conductive pipe 54.
The mounting flange 14 of the sacrificial electrode 10 is detachably sandwiched in a sealed manner between the flanges 52A, 54A of the adjacent conductive and non-conductive pipes 52, 54.
It also can be seen from the figure that the conductive member 16, in the form of the conductive cable 16A in this example, electrically connects the mounting flange 14 to the conductive pipe 52. For secure connection, it is preferable that a terminal 60 is provided on the outer surface of the conductive pipe 52. The conductive cable 16A and the conductive pipe 52 may be connected to each other by welding or using any electric connecting means including ring terminals, spade terminals, receptacles, pin terminals, wire terminals, crimp terminals, solder terminals, and solder splices.
In FIG. 3, the pair of gaskets 56, 58 disposed between the mounting flange 14 and the respective flanges 52A, 54A of the pipes 52, 54 are also confirmed.
The electrolyte flows from the non-conductive pipe 54 on the left in FIG. 3 towards the conductive pipe 52 on the right in the same figure. The body 12 of the sacrificial electrode 10 located in the non-conductive pipe 54 is electrically connected to the conductive pipe 52 via the mounting flange 14 and conductive member 16. Therefore, the body 12 of the sacrificial electrode 10 is to be precedingly corroded, preventing or at least reducing the electrolytic corrosion of the conductive pipe.
Referring to FIG. 5, a variant of the piping connection structure 50 of FIG. 4, which is also part of the present invention, is illustrated. Similar elements or parts are assigned with similar reference numbers and detailed descriptions are thus omitted. In this embodiment, the body 12 of the sacrificial electrode 10 is so configured to be coaxially disposed within the non-conductive pipe 54 and/or the conductive pipe 52 (within the non-conductive pipe 54 in the illustrated example), creating an annular passage P between an exterior of the body 12 and an inner surface of the pipe(s) 52, 54 facing the exterior of the body 12, more preferably thereby admitting the electrolyte into the annular passage P. According to this variant, not only the inner surface of the body 12 but also the outer surface of the body 12 can come into contact with the electrolyte, which may provide greater protection against the electrolytic corrosion for the conductive pipe 52.
FIG. 6 shows a sacrificial electrode 10' according to another embodiment of the present invention, and Fig. 7 shows a piping connection structure 50' according to another embodiment of the invention to which the sacrificial electrode 10' of FIG. 6 is applied. Similar elements or parts are assigned with similar reference numbers and detailed descriptions are thus omitted. The mounting flange 14' extends from a position between the both axial ends of the body 12' so that the body 12' is disposed within both the conductive pipe 52 and the non-conductive pipe 54. Put another way, the short body 12 as shown in FIG. 3 is provided on each of the first and second faces 14a, 14b of the mounting flange 14. Increased total length of sacrificial electrode 10' can be obtained without compromising the mechanical stability of the body 12'. The longer body 12' allows for longer protection against electrolytic corrosion for the conductive pipe 52.
In the piping connection structure 50' of FIG. 7, a gap G is formed between the outer surfaces of the body 12' and the inner surfaces of the pipes 52, 54, forming an annular passage P, but the outer surface of the body 12' may be in contact with the inner surfaces of the pipes 52, 54.
FIG. 8 shows a pipe connection structure 50" according to yet another embodiment of the present invention. Similar elements or parts are assigned with similar reference numbers and detailed descriptions are thus omitted. The piping connection 50" structure has two sets of sacrificial electrodes 10, 10 as shown in FIG. 3. These two sacrificial electrodes 10, 10 are disposed so that their respective mounting flanges 14, 14 facing each other. The respective bodies 12, 12 of the sacrificial electrodes 10, 10 project away from each other; the body 12 of one sacrificial electrode 10 is located in the non-conductive pipe 54 and the body 12 of the other 10 is located in the conductive pipe 52.
An additional gasket 64 may be arranged between the mounting flanges 14, 14 of the sacrificial electrodes 10, 10.
Preferably, one mounting flange 14 is electrically connected to the conductive pipe 52 by a conductive member 16 (e.g. conductive cable 16A) and the other mounting flange 14 is electrically connected to said one mounting flange 14 by another conductive member 16 (e.g. conductive cable 16). Alternatively, two mounting flanges may be electrically connected to the conductive pipe 52 with two conductive members, respectively.
Referring again to FIGS. 3 and 4, a method for applying, preferably retroactively applying, the sacrificial electrode 10 as shown in FIG. 4 to form the piping connection structure 50 as shown in FIG.3, can be confirmed. As discussed above, the piping connection structure 50 includes the conductive pipe 52 and the non-conductive pipe 54 to be adjoined to each other with the fasteners, adjoining ends of the pipes 52, 54 being provided with flanges 52A, 54A, respectively. The method comprises steps of: disposing the body 12 of the sacrificial electrode 10 within the non-conductive pipe 54; sandwiching the mounting flange 14 of the sacrificial electrode 10 between the flanges 52A, 54A of the adjacent conductive and non-conductive pipes 52, 54; and connecting the conductive member 16 of the sacrificial electrode 10 to the conductive pipe 52. In an alternative method, the step of disposing may include disposing the body 12 of the sacrificial electrode 10 within the conductive pipe 52, or within both the conductive pipe 52 and the non-conductive pipe 54.
As shown in FIG. 9, it is preferable in this method that the piping connection structure 50 comprising an existing sacrificial electrode 10X welded to an inner surface of the conductive pipe 52. In such a case, the step of disposing includes disposing the body 12 of the sacrificial electrode 10 within only the non-conductive pipe 52, preferably without removing the existing sacrificial electrode 10X from the conductive pipe 52. According to this, the sacrificial electrode 10 can easily (i.e., retroactively) be applied to existing pipes 52, 54 with the existing electrode 10X.

Reference sign list

10, 10': sacrificial electrode
12, 12': body
14, 14': mounting flange
16: conductive member
16A: conductive cable
16B: terminal
50, 50', 50": piping connection structure
52: conductive pipe (manifold)
54: non-conductive pipe (piping)
52A, 52B: flange
56, 58, 64: gasket
P: annular passage

Claims

A sacrificial electrode (10, 10') for arrangement between adjacent conductive and non-conductive pipes (52, 54) to flow electrolyte to or from electrolysis cells, adjoining ends of the pipes (52, 54) being provided with flanges (52A, 54A), respectively,
comprising:
a body (12, 12') configured to be disposed within the non-conductive pipe (54) and/or the conductive pipe (52);

a mounting flange (14, 14') extending from the body (12, 12') so as to be detachably sandwiched in a sealed manner between the flanges (52A, 54A) of the adjacent conductive and non-conductive pipes (52, 54); and

a conductive member (16) configured to electrically connect the mounting flange (14, 14') to the conductive pipe (52).
The sacrificial electrode (10) according to claim 1, wherein the mounting flange (14) extends from an end of the body (12) so that the body (12) is disposed within either the non-conductive pipe (54) or the conductive pipe (54), preferably within the non-conductive pipe (54) so that the body (12) protrudes from the mounting flange (14) in the direction away from the conductive pipe (52).
The sacrificial electrode (10') according to claim 1, wherein the mounting flange (14') extends from a position between the both ends of the body (12') so that the body (12') is disposed within both the conductive pipe (52) and the non-conductive pipe (54).
The sacrificial electrode (10, 10') according to any one of claims 1 to 3, wherein the conductive member (16) includes a conductive cable (16A).
The sacrificial electrode (10, 10') according to claim 4, wherein the conductive member (16) includes a terminal (16B) for electrically and physically connecting the conductive cable (16A) to the mounting flange (14, 14').
The sacrificial electrode (10, 10') according to any one of claims 1 to 5, wherein the body (12, 12') is so configured to be coaxially disposed within the non-conductive pipe (54) and/or the conductive pipe (52), preferably creating an annular passage (P) between an exterior of the body (12, 12') and an inner surface of the pipe (52, 54) facing the exterior of the body (12, 12'), more preferably thereby admitting the electrolyte into the annular passage (P).
The sacrificial electrode (10, 10') according to any one of claims 1 to 6, wherein the body (12, 12') is formed in a cylindrical shape.
The sacrificial electrode (10, 10') according to any one of claims 1 to 7, wherein the body (12, 12') is formed of a mesh or has a number of through holes.
The sacrificial electrode (10, 10') according to any one of claims 1 to 8, wherein the body (12, 12') is made of titanium or titanium alloy, and more preferably of titanium-palladium alloy.
The sacrificial electrode (10, 10') according to any one of claims 1 to 9, wherein the body (12, 12') has an oxide top layer such as titanium, ruthenium, or iridium layer on a base material.
A piping connection structure (50, 50', 50") for an electrolyser, comprising:
a conductive pipe (52) having a flange (52A) at its end;

a non-conductive pipe (54) having a flange (54A) at its end, the flange (54A) being configured to be adjoined to the flange (52A) of the conductive pipe (52); and

a sacrificial electrode (10, 10') according to any one of claims 1 to 10, arranged between adjacent conductive and non-conductive pipes (52, 54),

wherein the body (12, 12') of the sacrificial electrode (10, 10') is disposed within the conductive pipe (52) and/or the non-conductive pipe (54);

wherein the mounting flange (14, 14') of the sacrificial electrode (10, 10') is detachably sandwiched in a sealed manner between the flanges (52, 54) of the adjacent conductive and non-conductive pipes (52, 54); and

wherein the conductive member (16) of the sacrificial electrode (10, 10') electrically connects the mounting flange (14, 14') to the conductive pipe (52).
The piping connection structure (50, 50', 50") according to claim 11, wherein
the conductive pipe (52) has a terminal (60) on an outer surface thereof, and

the conductive member (16) is connected to the terminal (60).
The piping connection structure (50, 50', 50") according to claim 11 or 12, wherein
the body (12, 12') of the sacrificial electrode (10, 10') is disposed within the non-conductive pipe (54) so that the body (52) protrudes from the mounting flange (14, 14') in the direction away from the conductive pipe (52),

preferably, wherein the piping connection structure (50', 50") further comprising another sacrificial electrode (10) disposed within the conductive pipe (52),

preferably, wherein the another sacrificial electrode (10) has a mounting flange (16) sandwiched between the flanges (52A, 54A) of the conductive and non-conductive pipes (52, 54).
A method for applying, preferably retroactively applying, a sacrificial electrode (10, 10') according to any of claims 1 to 10 to a piping connection structure (50, 50', 50") for an electrolyser, the piping connection structure (50, 50', 50") including a conductive pipe (52) and a non-conductive pipe (54) to be adjoined to each other, adjoining ends of the pipes (52, 54) being provided with flanges (52A, 54A), respectively,
the method comprises steps of:
disposing the body (12, 12') of the sacrificial electrode (10, 10') within the non-conductive pipe (54) and/or the conductive pipe (52);

sandwiching the mounting flange (14, 14') of the sacrificial electrode (10, 10') between the flanges (52A, 54A) of the adjacent conductive and non-conductive pipes (52, 54); and

connecting the conductive member (16) of the sacrificial electrode (10, 10') to the conductive pipe (52).
The method according to claim 14, wherein:
the piping connection structure (50) comprising an existing sacrificial electrode (10X) welded to an inner surface of the conductive pipe (52);

the step of disposing includes disposing the body (12) of the sacrificial electrode (10) within the non-conductive pipe (52), preferably without removing the existing sacrificial electrode (10X) from the conductive pipe (52).