Electrolytic system for descaling, structure comprising said system and method for descaling submerged structures

Abstract

An electrolysis system (S) for descaling comprising: a first substrate (1) comprising titanium wherein a surface (11) of the first substrate (1) intended to be in contact with water is defined in the first substrate (1); the invention relates to an electrolysis system (S) comprising a first substrate (1), an electrically conductive second substrate (2) provided with a surface (21) intended to be in contact with water, the electrolysis system (S) comprising a power source (U) connected in series between the first substrate (1) and the second substrate (2) such that an electrolysis circuit can be established from water, the first substrate (1), the second substrate (2) and the power source (U) providing electrical energy, the power supply (U) is configured to provide a current density such that the first substrate (1) operates as an anode, to periodically reverse the polarity of the circuit such that the first substrate (1) and the second substrate (2) periodically alternate their function as an anode or a cathode, and / or to provide a pulse current density.

Description

Technical Field

[0001] The invention belongs to the field of electrolysis systems for descaling submerged structures by applying an electric current to the surface immersed in water. Background Art

[0002] An electrolysis system known in the art comprises: a first substrate comprising titanium, wherein a surface of the first substrate intended to be in contact with water is defined in the first substrate; a second conductive substrate provided with a surface intended to be in contact with water, the electrolysis system comprising a power source connected in series between the first substrate and the second substrate so that an electrolysis circuit formed by water, the first substrate operating as an anode, the second substrate operating as a cathode, and a power source providing electrical energy can be established.

[0003] An example of such an electrolysis system is disclosed in patent document JP2003328164A, which relates to a method for preventing marine organisms from attaching to titanium vessels.

[0004] This document describes the 1.2V AG / AgCl Various potentials at various levels (particularly a reference voltage relative to a reference electrode (silver / silver chloride in seawater)) are applied to an immersed substrate containing titanium in the hope of producing a microbial-killing substance at the anode in the hope of reducing scaling.

[0005] The document discloses an experiment in which a 50 mm x 30 mm sample was immersed for three months and then checked for the presence of scaling. According to the document, the experiment showed that at 1.2 V Ag / AgCl No marine life was observed on the samples.

[0006] The inventors of the present application attempted to reproduce these results, but using a larger plate in order to obtain a realistic measurement, since the hull of a ship will typically be exposed to water for tens, hundreds or even thousands of square meters. The plate used was 0.6 m 2 However, when 1.2V is applied Ag / AgCl to 2V Ag / AgCl or even 3V Ag / AgCl The results were poor when the reference voltage was used, and the titanium surface covered with algae and barnacles showed that the electrolyte solution was not feasible at a larger scale and for a longer period of time.

[0007] Throughout this specification it is important to point out that the titanium electrodes are not active titanium electrodes (MMO or platinum-plated electrodes) where the surface has been modified to make it stable and facilitate current output when subjected to an electrical signal.

[0008] The document "Development of an electrochemical antifouling system for seawater cooling pipelines of power plants using titanium" discloses that the electrochemical antifouling system for seawater cooling pipelines of power plants using titanium is used to generate an electrochemical antifouling system at about 0.9 V by using the following two types of signals: Ag / AgCl Titanium-based substrates that operate at potentials of 100 to 200 ppm without generating chlorine or changing pH:

[0009] -With 50 / 100mA / m 2 The constant current control signal is fixed. AG / AgCl to start, but it is disclosed that in order to maintain this current, the potential must be increased to 6 / 7V Ag / AgCl . (It should be noted that the inventors of the present invention have confirmed this fact).

[0010] - At 0.9V Ag / AgCl Anode cycle and -0.3 / -0.9V Ag / AgCl The cathode signal under the alternating signal.

[0011] According to the paper, the main goal was to try to avoid chlorine generation and pH changes. We point out that the current densities published in the paper do not correspond to the current densities indicated in the study graphs.

[0012] The current densities described in the paper are inconsistent with the data presented in the graphs in the article, and some of the photographs show coated test specimens rather than bare as would be necessary to achieve the described antifouling effects, unless they are conductive coatings such as those described in other articles in the same group (Electrochemical Prevention of Biofouling - Matsunaga 2000-68_847) which describe signals similar to those disclosed in this article for conductive coatings.

[0013] In any case, it should be noted that the paper does not specify anything about the iron counter electrode they use, which must corrode under the conditions described in the anodic cycle, and on which calcic salts and biofouling, such as those shown in Figures 18 and 19, must precipitate under constant current conditions, and that the paper's recommendations focus on keeping substrate 1 clean without considering substrate 2, which in many applications may limit the application of the technology as explained below. Summary of the invention

[0014] In order to overcome the above limitations, the present invention proposes an electrolysis system for descaling, the electrolysis system comprising: a first substrate, the first substrate comprising titanium, wherein a surface of the first substrate intended to be in contact with water is defined in the first substrate; a conductive second substrate, the second substrate being provided with a surface intended to be in contact with water, the electrolysis system comprising a power source, the power source being connected in series between the first substrate and the second substrate, so that an electrolysis circuit formed by water, the first substrate, the second substrate and a power source providing electrical energy can be established, wherein the power source is configured to provide a current density so that the first substrate operates as an anode; and

[0015] - periodically reversing the polarity of the circuit so that the first substrate and the second substrate periodically alternate their function as anode or cathode; and / or

[0016] - Provides pulse current density.

[0017] In some embodiments, the second substrate is titanium, active titanium, or a consumable electrode, and / or the electrolysis system may include a plurality of second substrates, and the electronic device is configured such that at least one of the second substrates is subjected to an anodic potential by a power source such that the at least one of the substrates serves as an anode to eliminate calcic salts that may have been precipitated on its surface.

[0018] In some embodiments, the power source is configured to provide greater than or equal to 30 mA / m 2 of current density.

[0019] In some embodiments, the power supply is configured to apply a periodic signal comprising a sequence of the following currents:

[0020] - a constant current by which the first substrate operates as an anode and the second substrate operates as a cathode;

[0021] - a reverse current, by which the first substrate operates as a cathode and the second substrate operates as an anode.

[0022] In some embodiments, the power supply is configured to apply a periodic signal comprising a sequence of the following currents:

[0023] - a pulsed current by which the first substrate operates as an anode and the second substrate operates as a cathode;

[0024] - a reverse current, by which the first substrate operates as a cathode and the second substrate operates as an anode.

[0025] In some embodiments, the electrolysis system includes a lower substrate to which the first substrate is attached.

[0026] In some embodiments, the lower substrate is made of steel, aluminum or bronze, and the first substrate is made of pure titanium, and wherein the first substrate is made of two layers, namely a thick outer layer and an attachment layer, the attachment layer forming a joint between the outer layer and the lower substrate, and preferably, the attachment layer is a PVD deposited layer or a CVD deposited layer.

[0027] In some embodiments, the lower substrate is made of a titanium alloy and the first substrate is made of pure titanium.

[0028] In some embodiments, the lower substrate is made of composite material and the first substrate is a blank made of pure titanium and has a thickness comprised between 0.1 mm and 4 mm.

[0029] In some embodiments, the composite material includes resin, glass fiber, carbon fiber, and / or structural plastic.

[0030] In some embodiments, the lower substrate is made with an inner layer made of metal and an outer layer made of insulating material, the first substrate being a blank made of pure titanium and having a thickness comprised between 0.1 mm and 4 mm, the blank being attached to the outer layer.

[0031] In some embodiments, the first substrate is divided into a plurality of substrates such that when a reversal of polarity is applied, some of the substrates form the second substrate.

[0032] This option seeks to avoid biofouling in both substrate 1 and substrate 2 and allows avoiding salt precipitation and biological growth in the counter electrode and avoiding the need to use an auxiliary counter electrode which is difficult to position correctly in many cases.

[0033] For example, in the case of a plate heat exchanger. Here, the distance between the plates is very small and it would be necessary to position the counter electrode in the tube, and the distribution of the electrical signal is difficult. In addition, the counter electrode would fill with salts and biofouling, becoming able to clog the pipes, heat exchangers or refrigeration circuits.

[0034] However, by operating the plates as anodes and cathodes alternating the signal, the signal can be applied alternately between the plates so that the plates remain clean, free of salt deposits and the signal propagates evenly through the small distance between the electrodes.

[0035] To emphasize the difference between this embodiment of the invention and the previously published ones, it is worth mentioning the document “Construction of an Electrochemical Antibiofouling System for Plate Heat Exchangers, Hitoshi Wake, Toshihiro Takimoto, Hirokazu Takayanagi, Kinichi Ozawa, Hideo Kadoi, Shigeki Mukai, Yoshinari Komura, Mina Okochi, Hiroyuki Honda, Tadashi Matsunaga”. Firstly, the document proposes working with active titanium in the plates, which is expensive and reduces the exchange performances, which is different from the concept of the invention (that is why the document mentions such low potentials), and the document proposes adding auxiliary counter and reference electrodes. The method of the document makes it difficult to implement this solution, and the important difference is that it only targets the cleanliness in electrode 1, while according to the invention, both electrodes are kept clean by alternating the signal, using different parts of the structure as working and counter electrodes.

[0036] Therefore, the present invention is simpler and more feasible because it involves working with inactive titanium, avoiding the problem of counter electrodes and facilitating the application of signals.

[0037] The same can be applied to pipelines, where segmenting the pipeline into sections allows the distance between electrodes to be maintained in a controlled manner, thereby eliminating auxiliary counter electrodes and achieving this by dividing the structure into sections that are electrically isolated from each other. Fig.24 and Fig.25 In fact, we have obtained the result that the titanium is completely clean inside. The invention also relates to a vessel, a pipeline, a heat exchanger, a propeller or a shaft etc. provided with an electrolysis system according to any of the above mentioned variants.

[0038] The invention also relates to an assembly comprising a pipe and an electrolysis system according to the variant disclosed above, the electrolysis system comprising an inner layer corresponding to a first substrate, the pipe comprising an intermediate layer corresponding to a structural material that imparts rigidity to the pipe, and the electrolysis system comprising an outer metal layer corresponding to a second substrate.

[0039] The invention also relates to a method for descaling a vessel, a pipe, a heat exchanger, a propeller, a shaft, a turbine, in particular a tidal turbine, a subsea valve box (for ship refrigeration), a hydrofoil and / or a pump component using an electrolysis system according to any of the inventive variants, the method comprising:

[0040] - Calculate the area of ​​the first substrate;

[0041] - arranging the power supply such that the power supply preferably provides an anode potential greater than a limit to avoid biofouling in the first substrate;

[0042] - having a plurality of second substrates, the electrolysis system being configured such that at least one of the second substrates is subjected to the same potential as the first substrates by a power supply, so that said at least one of the substrates acts as an anode to eliminate calcic salts that may have been deposited on its surface.

[0043] Finally, the invention also relates to a method for descaling a vessel, a pipe, a heat exchanger, a propeller, a shaft, a turbine, in particular a tidal turbine, a subsea valve box (for ship refrigeration), a hydrofoil and / or a pump component using an electrolysis system according to any of the variants of the invention, the method comprising:

[0044] - Calculate the area of ​​the first substrate;

[0045] - arranging the power supply such that the power supply preferably provides an anode potential greater than a limit to avoid biofouling in the first substrate;

[0046] - Dividing the first substrate into multiple substrates and reversing the polarity between these substrates so that all substrates act as anodes and cathodes, thereby avoiding the growth of biofouling on their surfaces, the precipitation of calcic salts on their surfaces, avoiding the need for additional counter electrodes and reducing the working area and, therefore, energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to complete the description and to provide a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the specification and illustrate embodiments of the invention, which should not be interpreted as limiting the scope of the invention, but only as examples of how the invention may be implemented. The drawings include the following figures:

[0048] Figure 1 A diagram showing a system according to the invention is shown.

[0049] Figure 2 A layer scheme according to an embodiment of the invention is shown, wherein a titanium layer is adhered to a third substrate.

[0050] Figure 3 A layer scheme according to an embodiment of the invention is shown, wherein the lower substrate is in turn formed by a third substrate and an interface layer.

[0051] Figure 4 The layer scheme according to an embodiment of the invention is shown, wherein the titanium is a blank adhered to a substrate with an interposed insulating material.

[0052] Figure 5 Shown has been immersed and applied 3V Ag / AgCl Titanium plate with electric potential.

[0053] Figure 6 Shown is an experimental setup on a ship's hull and adhesion results after several months of immersion.

[0054] Figure 7 yes Figure 6 Enlarged photo of .

[0055] 8 to 11 show panels of a system to which a voltage lower than 6V is applied.

[0056] 12 to 16 show panels of a system according to the invention.

[0057] Fig.17 Another plate is shown used under the conditions of the invention to which an alternating signal has been applied.

[0058] 18 and 19 show calcium deposition in the cathode when no inversion is applied.

[0059] Fig. 20 An applied pulse signal is shown which allows energy saving.

[0060] Fig.21 and Fig. 22 A pulse signal combined with cathode cleaning is shown.

[0061] Fig.23 A method for renewing the anode surface is shown.

[0062] Figure 24 to Figure 26 The results of applying the present invention to the interior of a pipe are shown ( Fig.26 Shown is a pipeline without antifouling system ( Fig.25 )’s external part). Fig. 27 Shown is what happens when the alloy is operated above the rupture potential. DETAILED DESCRIPTION

[0063] like Figure 1 , Fig. 20 , Fig.21 , Fig. 22 or Fig.23As shown in, according to an embodiment, an electrolysis system S for descaling comprises: a first substrate 1, the first substrate 1 comprises titanium, wherein a surface 11 of the first substrate 1 intended to be in contact with water is defined in the first substrate 1; a second conductive substrate 2, the second conductive substrate 2 is provided with a surface 21 intended to be in contact with water, the electrolysis system S comprises a power source U, the power source U is connected in series between the first substrate 1 and the second substrate 2, so that an electrolysis circuit formed by water, the first substrate 1, the second substrate 2 and the power source U providing electrical energy can be established, and the power source U is configured as follows:

[0064] - providing a current density such that the first substrate 1 operates as an anode, the current density preferably being applied in pulses in order to save energy; and

[0065] - The polarity of the circuit is periodically reversed so that the first substrate 1 and the second substrate 2 periodically alternate their function as anode or cathode.

[0066] The second substrate 2 is titanium or activated titanium or a consumable electrode, and / or the electrolysis system may include a plurality of second substrates, and the electrolysis system is configured such that at least one of the second substrates 2 is subjected to an anodic potential by a power supply, so that the at least one of the substrates acts as an anode to eliminate calcic salts that may have been precipitated on its surface.

[0067] Furthermore, among other things, the first substrate can be divided into different electrically independent surfaces that will work as substrate 1 and substrate 2, making them work alternately as anode and cathode, thereby eliminating the need to use electrodes (unlike previously proposed) and keeping both substrate 1 and substrate 2 clean and free from biofouling. In addition, the polarity change is beneficial to the output of the anodic current because it reverses the surface anodic process and reduces the resistance of the system. Our alternating signal can be symmetrical with similar working and counter electrodes, or vary according to the area of ​​substrate 1 and substrate 2, but must always be sufficient to avoid biofouling in both surfaces.

[0068] The structure can be divided into different titanium areas that are electrically disconnected from each other so that the signal can be applied alternately between them. Thereby, the precipitation of salts and the growth of organisms on the counter electrode are avoided and also the need to use a counter electrode is avoided, which in many cases is difficult to position in the right place. For example, in the case of a plate heat exchanger. The distance between the plates is very small and the counter electrode must be positioned in the tube, and the distribution of the electrical signal is difficult. In addition, the counter electrode will be filled with salt and biofouling. However, if we use the plates as anodes and cathodes that alternate the signal, we can apply the signal alternately between the plates, so that the plates remain clean, without precipitation of salts, and we can make the signal spread evenly by having a small distance between the electrodes.

[0069] exist Figure 2 In the embodiment shown in , the electrolysis system comprises a lower substrate 3, to which the first substrate 1 is attached. Here, the lower substrate 3 is made of a titanium alloy, and the first substrate 1 is made of pure titanium.

[0070] exist Figure 2 In another variant of the embodiment shown in , the lower substrate 3 is made of composite material, the first substrate 1 is a blank 14 made of pure titanium and has a thickness comprised between 0.1 mm and 4 mm. The composite material 3 may comprise resin, glass fiber, carbon fiber and / or structural plastic.

[0071] Figure 3 The following embodiment is depicted: wherein the lower substrate 3 is made of steel, aluminum or bronze, the first substrate 1 is made of pure titanium, and wherein the first substrate is made of two layers, namely a thick outer layer 1E and an attachment layer 1A, the attachment layer 1A forming an interface between the outer layer 1E and the lower substrate 3, and preferably, the attachment layer 1A is a PVD deposited layer or a CVD deposited layer.

[0072] Figure 4 An embodiment is depicted in which the lower substrate 3 is made by means of an inner layer 31 made of metal and an outer layer 32 made of insulating material, the first substrate 1 being a blank 14 made of pure titanium and having a thickness comprised between 0.1 mm and 4 mm, the blank 14 being attached to the outer layer.

[0073] Voltage and current density

[0074] To obtain the preferred voltage and current density, the tests were performed by applying the electrical signal in different ways. From potentiostatic control, galvanostatic control, constant voltage pulses to alternating pulses or periodic pulses. The tests were standardized by using grade 2 titanium electrodes for both anode and cathode. Tests were also performed using other materials for the cathode, such as steel for example.

[0075] In the initial stage, the system evolves over time and the resistance of the anode changes significantly due to anodic oxidation occurring on its surface. The resistance of the system increases over time. Salts precipitate on the cathode. This is the expected effect.

[0076] The following tests were then carried out by applying a constant voltage. The system current follows Ohm's law and it is necessary to consider that the system resistance changes with time due to the reactions occurring on the electrodes, mainly the anodic oxidation reactions occurring in the titanium anode. In all tests, both current and voltage were measured.

[0077] In summary, as will be apparent below, the inventors have concluded from testing that there is a critical current at which an antifouling effect on titanium surfaces begins to be observed. Below this current, algae continue to grow even if the electrode is anodically polarized.

[0078] When the voltage applied in the constant signal was less than 6 V, an effect on biofouling was seen but biofouling was not completely eliminated because the minimum anode current required to avoid biofouling was not reached.

[0079] The following table shows the parameters used in the unsuccessful tests (the area of ​​the plate used was 0.6 m 2 ):

[0080] Current Applied voltage Anode potential Current density mA / m2 17.7mA 5.5V <![CDATA[5.45V AgAgCl ]]> 28.3 14.6mA 5.5V <![CDATA[5.32V AgAgCl ]]> 24.3 14.4mA 5.31V <![CDATA[5.31V AgAgCl ]]> 24.0 13mA 5.13 V <![CDATA[5V AgAgCl ]]> 21.7

[0081] Figures 8 to 11 show plates subjected to these conditions: none of the plates showed satisfactory results. We note that these voltages are already significantly higher than those suggested in the prior art and disclosed as being effective in preventing the adhesion of microorganisms. Under these polarization conditions, the plates showed lower levels of biofouling than the plates without polarization, but the results were not satisfactory.

[0082] Then, voltages above 7V were tested and the results are summarized in the table below:

[0083] Current Applied voltage Anode potential Current density mA / m2 19mA 7.7V <![CDATA[6.61V AgAgCl ]]> 31.7 23.4mA 7.5V <![CDATA[6.96V AgAgCl ]]> 39.0 17.9mA 7.5V <![CDATA[7.05V AgAgCl ]]> 29.8 19mA 8.2V <![CDATA[7.84V AgAgCl ]]> 31.7

[0084] Figures 12 to 16 show plates subjected to these conditions: all plates showed virtually no microbial adhesion.

[0085] Comparison Test

[0086] By applying a voltage of 7.5V and a current of more than 30mA / m² over a period of 8 months, Figure 6 and Figure 7 The photo clearly shows that there is not a single barnacle B in the titanium.

[0087] Fig.17 Another sample is shown which in this case was immersed for four months under alternating pulses. No single adhesion was seen on the blank either, but the cable subjected to the same conditions was completely covered with algae.

[0088] Finally, the inventors have developed a layered structure that can be used in the context of the present invention. This layered structure, which can be considered as an invention per se, comprises the following layers:

[0089] - a lower base plate made of steel;

[0090] - a first substrate made of titanium; and wherein

[0091] The first substrate is made of two layers, namely a thick outer layer 1E and an attachment layer 1A, which forms the interface between the outer layer 1E and the lower substrate 3 and is a PVD deposited layer or a CVD deposited layer.

[0092] The structure can be used in particular in ships, pipelines, heat exchangers, propellers, shafts, turbines, subsea valve boxes, hydrofoils and / or pump components.

[0093] In the layered structure, the first substrate made of titanium may be pure titanium and / or a titanium alloy.

[0094] It can also be applied to other metal substrates with an insulation system or other structural materials between the metal and the titanium sheet, such as structural polymers or composites. It is important to emphasize that the application of these titanium coatings to avoid biofouling is not a trivial concept and in many cases means making the technology feasible by keeping both the electrode and the counter electrode clean and requiring special resins, mechanical reinforcement and specific electrical connections in addition to having to be able to segment the surface of the part to keep it free of biofouling to be able to apply the alternating signal and eliminate the counter electrode to reduce electrical consumption.

[0095] Inventive method for renewing anode surfaces

[0096] As explained above, in order to avoid biofouling in submerged structures, a minimum anodic current must be applied.

[0097] However, by applying this anodic current over time, the resistance of the system increases due to the anodic reaction occurring on the titanium surface (substrate 1) and the working potential required to maintain this current increases until it reaches a stationary state where it remains constant at a value of several positive volts (hence the 6VAg / AgCl indicated above).

[0098] Pure titanium has no problem supporting this working potential, however, titanium alloys with different alloying elements that modify the properties of the native oxide layer present on the surface of the titanium alloy present lower rupture potentials relative to the potential necessary to maintain an anodic current capable of avoiding the occurrence of biofouling and under these conditions they degrade. Fig. 27 Shown is what happens when the alloy is operated above the rupture potential.

[0099] In order to avoid biofouling on these alloys, it must be ensured that the operating voltage can be kept below the mentioned limit (rupture potential or breakdown potential), with sufficient safety margins, but ensuring sufficient anodic current circulation to prevent biofouling.

[0100] To achieve these two objectives, the inventors have verified a method for renewing the anodic surface of substrate 1 by applying a sufficient cathodic signal that allows the resistance of the system to decrease and thus operate at an operating potential below the rupture potential of the alloy, while maintaining the minimum current required to avoid biofouling.

[0101] The intensity and duration of cathodic polarization required to lower the operating potential is proportional to the anodic current density desired to flow through the system, and the cathodic cycling required to be applied depends on the intensity and duration of the anodic cycling.

[0102] Fig.23 An example of the effect of "cathode cleaning" on the potential required for operation is shown for a given anodic current and a cathodic current applied for different times (hence, different cathodic charges applied). It is observed that when sufficient cathodic charge is applied, the operating potential stabilizes at a constant value below the limiting potential for a period of time.

[0103] exist Fig.23 In the graph, the voltage required to maintain the anodic current is expressed as a function of time and the following phases are distinguished:

[0104] - a first phase of anodizing voltage, in which the pressure is positive and operates to protect scaling on the main anodizing surface. During the anodic phase, the resistance of the system increases due to the anodic reactions generated during the anodic cycle;

[0105] - In the second phase, the polarity is reversed by applying a cathodic cycle (the operating voltage becomes negative) and the substrate starts to work as a cathode. During this second phase, surface renewal occurs and the anodic processes generated during the anodic polarization phase are reversed;

[0106] - In the third phase, the polarity is reversed again, forcing sufficient anodic current to circulate to prevent biofouling. The graph records the electrode potential required to maintain the indicated anodic current. It can be observed that insufficient cathodic circulation does not allow surface renewal and the operating potential required to achieve the minimum anodic current required to avoid biofouling exceeds the limiting potential of the alloy. However, when the cathodic circulation used is large enough, the required operating potential remains stable and below the breakdown potential for the desired period of time.

[0107] These tests showed that:

[0108] - If the surface is not completely renewed during the cleaning phase of the cathode, the required voltage can even be greater than the maximum permissible voltage (rupture potential or breakdown potential). That is because the cleaning is not sufficient;

[0109] If the reversal voltage and its application time are properly combined, the time will occur when the required subsequent voltage stops increasing: for each material, determination of this combination allows the reversal signal to be optimized to ensure that the anode voltage will be minimal.

[0110] Therefore, another invention is disclosed herein comprising a method for renewing an anode surface, the method comprising the following periodically performed steps:

[0111] - Apply sufficient anode circulation to avoid biofouling;

[0112] - application of a cathodic signal sufficient to produce a renewal of the surface of the substrate 1 , which allows the subsequent application of the anodic current necessary to prevent biofouling at potentials below the limiting potential;

[0113] - Applying the anodic signal for the desired time to achieve the anodic current necessary to prevent biofouling at potentials below the breakdown potential.

[0114] Preferably, these steps are performed for different values ​​depending on the desired anode current.

[0115] In addition, another effect is claimed. At sufficiently large cathodic polarization, hydrogen generation occurs on the polarized surface. If this is done with sufficient intensity, mechanical cleaning of the surface is possible, since a large number of gas bubbles can be generated that can mechanically tear off biofilms and bacterial veils.

[0116] However, if only this cathodic polarization is carried out, precipitation of salts occurs and the alloy may become embrittled. This is why it is good to combine it with an anodic cycle.

[0117] Finally, disclosed herein is a method for eliminating biofouling by mechanically cleaning submerged surfaces by applying cathodic polarization with sufficient voltage to generate hydrogen bubbles.

[0118] In this document, the term "include" and its derivatives (such as "comprises", etc.) should not be understood in an exclusive sense, that is, these terms should not be interpreted as excluding the possibility that the described and defined contents may include other elements, steps, etc.

[0119] The present invention is obviously not limited to the specific embodiments described herein, but also covers any variants (for example, regarding the selection of materials, dimensions, components, configurations, etc.) that may be considered by a person skilled in the art within the general scope of the invention as defined in the claims.

Claims

1. An electrolysis system (S) for descaling, the electrolysis system (S) comprising: A first substrate (1), wherein the first substrate (1) comprises titanium, wherein a surface (11) of the first substrate (1) intended to be in contact with water is defined in the first substrate (1); a conductive second substrate (2), wherein the second substrate (2) is provided with a surface (21) intended to be in contact with water, the electrolysis system (S) comprising a power source (U), wherein the power source (U) is connected in series between the first substrate (1) and the second substrate (2), so that an electrolysis circuit formed by water, the first substrate (1), the second substrate (2) and the power source (U) providing electrical energy can be established, characterized in that the power source (U) is configured to provide a current density such that the first substrate (1) operates as an anode; and - periodically reversing the polarity of the circuit so that the first substrate (1) and the second substrate (2) periodically alternate the function of the first substrate (1) and the second substrate (2) as an anode or a cathode; and / or - Provides pulse current density.

2. An electrolysis system according to any one of the preceding claims, wherein The second substrate (2) is titanium or activated titanium or is a consumable electrode, and / or the electrolysis system can include a plurality of second substrates, and the electrolysis system is configured so that at least one of the second substrates (2) is subjected to an anodic potential by the power supply, so that the at least one of the substrates serves as an anode to eliminate calcic salts that have been precipitated on the surface of the at least one substrate.

3. An electrolysis system (S) according to any one of the preceding claims, wherein: The power source (U) is configured to provide a current greater than or equal to 30 mA / m on the surface. 2 of current density.

4. An electrolysis system (S) according to any one of the preceding claims, wherein: The power source (U) is configured to apply a periodic signal, the periodic signal comprising the following sequence: - a constant current, by which the first substrate (1) operates as an anode and the second substrate (2) operates as a cathode; - a reverse current, by which the first substrate (1) operates as a cathode and the second substrate (2) operates as an anode.

5. The electrolysis system (S) according to claim 1 or claim 2, wherein: The power source (U) is configured to apply a periodic signal, the periodic signal comprising the following sequence: - a pulse current, by which the first substrate (1) operates as an anode and the second substrate (2) operates as a cathode; - a reverse current, by which the first substrate (1) operates as a cathode and the second substrate (2) operates as an anode.

6. The electrolysis system according to any of the preceding claims, comprising a lower substrate (3), the first substrate (1) being attached to the lower substrate (3).

7. The electrolysis system according to claim 6, wherein: The lower substrate (3) is made of steel, aluminum or bronze, the first substrate (1) is made of pure titanium, and wherein the first substrate is made of two layers, namely a thick outer layer (1E) and an attachment layer (1A), the attachment layer (1A) forming a joint between the outer layer (1E) and the lower substrate (3), and preferably, the attachment layer (1A) is a PVD deposited layer or a CVD deposited layer.

8. The electrolysis system according to claim 6, wherein: The lower substrate (3) is made of titanium alloy, and the first substrate (1) is made of pure titanium.

9. The electrolysis system according to claim 6, wherein: The lower base plate (3) is made of composite material, the first base plate (1) is a blank (14) made of pure titanium and having a thickness comprised between 0.1 mm and 4 mm.

10. The electrolysis system according to claim 9, wherein: The composite material (3) comprises resin, glass fiber, carbon fiber and / or structural plastic.

11. The electrolysis system according to claim 6, wherein: The lower substrate (3) is made of an inner layer (31) made of metal and an outer layer (32) made of insulating material, the first substrate (1) being a blank (14) made of pure titanium and having a thickness comprised between 0.1 mm and 4 mm, the blank (14) being attached to the outer layer.

12. An electrolysis system according to any one of the preceding claims, wherein: The first substrate (1) is divided into a plurality of substrates such that when polarity reversal is applied, some of these substrates form the second substrate (2).

13. A vessel, pipeline, heat exchanger, propeller, shaft, turbine, subsea valve box, hydrofoil and / or pump component provided with an electrolysis system (S) according to any of the preceding claims.

14. An assembly comprising a pipe and an electrolysis system according to claim 1, the electrolysis system comprising an inner layer corresponding to the first substrate (1), the pipe comprising an intermediate layer corresponding to a structural material that gives rigidity to the pipe, and the electrolysis system comprising an outer metal layer corresponding to the second substrate (2).

15. A method for descaling a vessel, a pipeline, a heat exchanger, a propeller, a shaft, a turbine, a subsea valve box, a hydrofoil and / or a pump component (S) according to any one of claims 1 to 12, the method comprising: - Calculate the area of ​​the first substrate; - arranging the power source (U) such that the power source (U) preferably provides an anode potential greater than a limit for avoiding biofouling in the first substrate; - having a plurality of second substrates, and the electrolysis system is configured so that at least one of the second substrates (2) is subjected to the same potential as the first substrate (1) by the power supply, so that the at least one of the substrates acts as an anode to eliminate calcic salts that have been precipitated on the surface of the at least one substrate; - or dividing the first substrate into a plurality of substrates and reversing the polarity between these substrates so that all substrates act as anodes and cathodes, thereby avoiding biofouling growth on the surfaces of the substrates, precipitation of calcic salts on the surfaces of the substrates, avoiding the need for an additional counter electrode, and reducing the working area and therefore reducing energy consumption.

16. A method for renewing an anode surface, the method periodically comprising the steps of: - Apply sufficient anodic cycles to avoid biofouling; - applying a cathodic signal sufficient to produce a surface renewal of the substrate (1) which allows the subsequent application of an anodic current necessary to prevent biofouling at potentials below the breakdown potential; - Applying the anodic signal for the time required to achieve the anodic current required to prevent biofouling at potentials below the breakdown potential.

17. The method of claim 16, the method being performed for different values ​​depending on the desired anode current.

18. A method for removing biofouling by generating hydrogen bubbles using cathode polarization.

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