High-activation aluminum sacrificial anode for FPSO and preparation method thereof

Abstract

This invention discloses a highly activated aluminum sacrificial anode for FPSO and its preparation method, belonging to the field of electrochemical protection technology. This aluminum alloy sacrificial anode is used for cathodic protection of FPSOs, comprising a sacrificial anode body and a core encased within the sacrificial anode body. The sacrificial anode body is mainly composed of Al, and also includes Zn, Sn, Si, Sb, and Ca; by mass percentage, Sn is selected from 0.03-0.25%, Sb from 0.006%-0.05%, and the weight ratio of Sn to Sb is 5:1-3:1. This invention addresses the problem of high cost and applicability of existing high-temperature aluminum alloy anode materials due to the use of rare metals such as lanthanum, yttrium, and actinium, which are only suitable for high-temperature environments such as high-temperature seawater or oil and gas wells. For the high-temperature, high-salt, and oily environments of FPSOs, the cathodic protection effect of the anode needs improvement. This aluminum alloy sacrificial anode is suitable for electrochemical protection of FPSOs in high-temperature (50-80℃), high-salt, and oily environments, and features high current efficiency and uniform surface dissolution.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical protection technology, and particularly relates to a highly activated aluminum sacrificial anode for FPSO and its preparation method. Background Technology

[0002] FPSO (Floating Production Storage and Offloading) is an integrated offshore floating production storage and offloading unit that combines production, storage, and unloading, and has become the mainstream production method for offshore oil and gas field development. FPSOs face harsh corrosive environments. Taking cargo oil tanks as an example, the temperature of the stored crude oil exceeds 50°C, and there is a certain amount of sediment water present. In this high-temperature, high-salt, and oil-contaminated environment, FPSOs suffer from severe corrosion problems, necessitating effective corrosion protection measures. Sacrificial anodes are an effective corrosion protection method in seawater environments, with aluminum alloy and zinc alloy sacrificial anodes being commonly used. The sacrificial anode materials specified in GB4948 and GB4950 exhibit good performance in normal-temperature seawater environments and have been widely applied. However, when the seawater temperature is high (>50°C), the current efficiency of conventional aluminum sacrificial anode materials decreases significantly, the corrosion morphology becomes uneven, and the protective effect is significantly reduced, failing to meet the corrosion protection requirements of steel structures in high-temperature seawater environments. Currently, FPSOs mainly use high-temperature zinc alloy sacrificial anodes for corrosion protection of various compartments, achieving good protective results. However, due to the inherent characteristics of zinc anodes, high-temperature zinc anodes have low capacitance (not exceeding 800 Ah / kg) and high cost. Therefore, developing aluminum alloy sacrificial anode materials suitable for high-temperature environments can significantly reduce the amount of sacrificial anodes used, lower corrosion protection costs, and have significant economic and social benefits.

[0003] Chinese patent CN201110191952.2 discloses an aluminum alloy sacrificial anode suitable for use in Bohai Bay marine mud. The anode's components are as follows (weight percentage): Zn 2.0~5.5%, In 0.01~0.05%, Sn 0.01~0.08%, Mg 4~8%, lanthanum 0.12~0.32%, actinium 0.12~0.32%, cerium 0.03~0.04%, silicon impurity content ≤0.05%, and the balance being aluminum. It exhibits good electrochemical performance in high-temperature marine mud environments, with an anode current efficiency of 70% at 50℃. Chinese patent CN202010968411.5 discloses a high-temperature resistant aluminum alloy sacrificial anode material and its preparation method. The anode's composition, by mass percentage, includes Zn 4%–6%, In 0.035%–0.05%, Sn 0.04%–0.1%, Mg 0.3%–1.0%, La 0.01%–0.02%, Y 0.01%–0.02%, Nd 0.01%–0.02%, impurity content ≤0.26%, and the balance being Al. This invention, based on the Al-Zn-In sacrificial anode system, incorporates alloying elements such as tin, magnesium, lanthanum, yttrium, and neodymium, improving the anode's electrochemical performance and refining its dissolution morphology. In a simulated oil and gas well environment at 70℃, its working potential distribution is between -0.99 and -1.12V, and its current efficiency is ≥60%.

[0004] However, the above high-temperature aluminum alloy anode material formulations all use rare metal elements such as lanthanum, yttrium, and actinium, resulting in high anode costs. They are only suitable for high-temperature environments such as high-temperature seawater or oil and gas wells. For the high-temperature, high-salt, and oily environments where FPSOs are located, the cathodic protection effect of the anodes needs to be improved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem this invention aims to solve is that the use of rare metal elements such as lanthanum, yttrium, and actinium in existing high-temperature aluminum alloy anode material formulations leads to high anode costs and makes them only suitable for high-temperature environments such as high-temperature seawater or oil and gas wells. For the high-temperature, high-salt, and oily environments where FPSOs are located, the cathodic protection effect of the anode needs to be improved. This invention proposes a highly activated aluminum sacrificial anode for FPSOs that is suitable for electrochemical protection in high-temperature (50-80℃), high-salt, and oily environments, and features high current efficiency and uniform surface dissolution, as well as its preparation method.

[0006] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a highly activated aluminum sacrificial anode for FPSO, used for cathodic protection of FPSO, comprising a sacrificial anode body and a core encapsulated within the sacrificial anode body, wherein the sacrificial anode body is mainly composed of Al, and also includes Zn, Sn, Si, Sb and Ca; by mass percentage, Sn is selected from 0.03-0.25%, Sb is selected from 0.006%-0.05%, and the weight ratio of Sn to Sb is 5:1-3:1.

[0008] Preferably, by mass percentage, the Zn is selected from 2-6%, the Si is selected from 0.05-0.20%, the Ca is selected from 0.005-0.15%, the impurity content is ≤0.15%, the balance is Al, and the total content of the Sn and the Sb does not exceed 0.25%.

[0009] Preferably, the mass percentage of Sn is 0.10-0.15%, and the mass percentage of Sb is 0.03-0.05%.

[0010] Preferably, the impurities contain Fe ≤ 0.09% and Cu ≤ 0.005% by mass percentage.

[0011] Preferably, the mass percentage of Si is 0.05-0.10%; and the mass percentage of Ca is 0.03-0.06%.

[0012] Preferably, the core is an iron core.

[0013] Another aspect of the present invention provides a method for preparing a highly activated aluminum sacrificial anode for FPSO as described in any of the above technical solutions, comprising a first alloying element addition step and a second alloying element addition step;

[0014] The first alloying element addition step includes: heating the aluminum ingot to completely melt it into an aluminum solution, adding zinc and aluminum-silicon alloy, stirring to rapidly melt the alloying elements into a first aluminum alloy solution, cooling the first aluminum alloy solution to 680-720℃, and holding it at that temperature for 30-60 minutes.

[0015] The second alloying element addition step includes: heating the first aluminum alloy solution to 820-850°C at a heating rate of not less than 5°C / min, then adding elemental tin, elemental antimony, and aluminum-calcium alloy, and stirring evenly to obtain the second aluminum alloy solution.

[0016] Preferably, during the first alloying element addition step, the aluminum ingot is heated to 780-820°C and completely melted into an aluminum solution. The purity of the aluminum ingot is not less than 99.85%. During the heat preservation process of the first aluminum alloy solution, it is continuously stirred, refined, degassed, and slag is removed.

[0017] Preferably, during the second alloying element addition step, after adding elemental tin, elemental antimony, and aluminum-calcium alloy, the stirring time is 1-3 min and the standing time is 5-10 min; the purity of elemental tin and elemental antimony is not less than 99.99%, and the impurity content in the aluminum-calcium alloy is ≤0.1%.

[0018] Preferably, the method further includes: placing the core in a mold, casting the second aluminum alloy solution into the preheated mold, cooling and forming the aluminum alloy sacrificial anode, and further cooling it to room temperature in air; the preheating temperature of the preheated mold is 150-300℃.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention provides a highly activated aluminum sacrificial anode for FPSOs, which uses Sn, Sb, and Si to replace activation elements such as In, forming a second phase in the aluminum alloy anode. Effective activation of the anode is achieved through the dissolution mechanism of this "second phase." The technical solution of this invention limits the amount of Sn and Sb used. Within this range, both Sn and Sb elements have the effect of refining the grain size of the anode alloy. Furthermore, when the Sn:Sb content is between 5:1 and 3:1, they exhibit a good synergistic effect, reducing Si segregation and preventing Si enrichment at grain boundaries. This invention addresses severe intergranular corrosion by improving the dissolution morphology of the anode and increasing current efficiency. Furthermore, the addition of a small amount of Ca refines the alloy grains, increases the grain boundary area, further reduces the tendency for intergranular corrosion in the aluminum alloy anode, and ensures uniform anode corrosion, thus improving current efficiency. In an FPSO environment of 50-80℃, salinity 20-35‰, and pH 3.5-6.5, the working potential of this aluminum alloy sacrificial anode is between -1.00 and -1.15V (relative to a silver chloride seawater electrode), with a capacitance ≥2200 A·h / kg. The anode dissolves uniformly, and corrosion products are easily detached, solving the problem of severe localized corrosion and low current efficiency in conventional Al-Zn-In aluminum alloys in FPSO environments.

[0021] This invention provides a method for preparing a highly activated aluminum sacrificial anode for FPSO. After the first addition of alloying elements, heat preservation and degassing can improve the homogeneity of the first aluminum alloy solution, reduce the content of impurities in the alloy, and avoid element segregation. After heat preservation and degassing, the temperature is rapidly increased and the alloying elements Sn, Sb and aluminum-calcium alloy are added for the second time. This can avoid the burning loss of Sn, Sb and Ca elements during the melting process. By air cooling to room temperature, the compositional segregation of the aluminum alloy sacrificial anode can be reduced and the sacrificial anode grains can be refined. Attached Figure Description

[0022] Figure 1This is a surface dissolution morphology image of the aluminum alloy sacrificial anode material obtained in Example 1 of the present invention after corrosion in the FPSO oil storage tank environment;

[0023] Figure 2 This is a corrosion and dissolution morphology diagram of a conventional Al-Zn-In-Si anode in an FPSO oil storage tank environment. Detailed Implementation

[0024] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0025] This invention provides a highly activated aluminum sacrificial anode for FPSO, used for cathodic protection of FPSO, comprising a sacrificial anode body and a core encapsulated within the sacrificial anode body, wherein the sacrificial anode body is mainly composed of Al, and also includes Zn, Sn, Si, Sb and Ca; by mass percentage, Sn is selected from 0.03-0.25%, Sb is selected from 0.006%-0.05%, and the weight ratio of Sn to Sb is 5:1-3:1.

[0026] FPSOs operate in high-temperature, high-salt, and oily environments, where the current efficiency of conventional aluminum alloy sacrificial anodes significantly decreases, and corrosion morphology becomes uneven. While high-temperature zinc anodes offer good performance, their capacitance is low (not exceeding 800 Ah / kg) and their cost is high. The aluminum alloy sacrificial anode provided by this invention uses Sn, Sb, and Si to replace activation elements such as In, forming a second phase within the aluminum alloy anode. Effective anode activation is achieved through the dissolution mechanism of this "second phase." This invention's technical solution limits the amount of Sn and Sb used. Within this range, both Sn and Sb elements refine the anode alloy grains. Furthermore, when the Sn:Sb ratio is between 5:1 and 3:1, they exhibit a good synergistic effect, reducing Si segregation and preventing Si enrichment at grain boundaries that could lead to severe grain defects. This invention addresses intergranular corrosion, improves the dissolution morphology of the anode, and enhances current efficiency. Furthermore, by adding a small amount of Ca, the alloy grains are refined, increasing the grain boundary area and further reducing the tendency for intergranular corrosion in the aluminum alloy anode. This results in more uniform anode corrosion and improved current efficiency. In an FPSO environment of 50-80℃, salinity 20-35‰, and pH 3.5-6.5, the working potential of this aluminum alloy sacrificial anode is between -1.00 and -1.15V (relative to a silver chloride seawater electrode), with a capacitance ≥2200 A·h / kg. The anode dissolves uniformly, and corrosion products are easily detached, solving the problem of severe localized corrosion and low current efficiency in conventional Al-Zn-In aluminum alloys in FPSO environments. It is understandable that Sn can also be selected from any point value within the range of 0.05%, 0.10%, 0.15%, 0.20%, and Sb can also be selected from any point value within the range of 0.01%, 0.02%, 0.03%, 0.04%, and the weight ratio of Sn to Sn can also be 4:1.

[0027] In a preferred embodiment, by mass percentage, the Zn is selected from 2-6%, the Si from 0.05-0.20%, the Ca from 0.005-0.15%, the impurity content is ≤0.15%, the balance is Al, and the total content of Sn and Sb does not exceed 0.25%. This embodiment specifically defines the amount of each component. It is understood that the amount of Zn can also be selected from 3%, 4%, 5% and any value within the range thereof, the amount of Si can also be selected from 0.1%, 0.15% and any value within the range thereof, and the amount of Ca can also be selected from 0.05%, 0.10% and any value within the range thereof.

[0028] In a preferred embodiment, the mass percentage of Sn is 0.10-0.15%, and the mass percentage of Sb is 0.03-0.05%.

[0029] In a preferred embodiment, the impurities contain Fe ≤ 0.09% and Cu ≤ 0.005% by mass percentage.

[0030] In a preferred embodiment, the mass percentage of Si is 0.05-0.10%; and the mass percentage of Ca is 0.03-0.06%.

[0031] In a preferred embodiment, the core is an iron core.

[0032] Another aspect of the present invention provides a method for preparing a highly activated aluminum sacrificial anode for FPSO as described in any of the above technical solutions, comprising a first alloying element addition step and a second alloying element addition step;

[0033] The first alloying element addition step includes: heating the aluminum ingot to completely melt it into an aluminum solution, adding zinc and aluminum-silicon alloy, stirring to rapidly melt the alloying elements into a first aluminum alloy solution, cooling the first aluminum alloy solution to 680-720℃, and holding it at that temperature for 30-60 minutes.

[0034] The second alloying element addition step includes: heating the first aluminum alloy solution to 820-850°C at a heating rate of not less than 5°C / min, then adding elemental tin, elemental antimony, and aluminum-calcium alloy, and stirring evenly to obtain the second aluminum alloy solution.

[0035] The method for preparing the aluminum alloy sacrificial anode provided by this invention utilizes a two-stage alloying process. The first addition of alloying elements, followed by heat preservation and degassing, improves the homogeneity of the first aluminum alloy solution, reduces impurities, and prevents elemental segregation. After heat preservation and degassing, rapid heating and the second addition of alloying elements Sn, Sb, and aluminum-calcium alloy prevent the loss of Sn, Sb, and Ca during the smelting process. Air cooling to room temperature further reduces component segregation in the aluminum alloy sacrificial anode and refines its grain size. Specifically, the preparation process of the aluminum alloy sacrificial anode for FPSO oil storage tanks employs a casting method. The heating furnace is selected from crucibles, but is not limited to this. Stirring is done gently with carbon rods, but is not limited to this method.

[0036] In a preferred embodiment, during the first alloying element addition step, the aluminum ingot is heated to 780-820°C and completely melted into an aluminum solution. The purity of the aluminum ingot is not less than 99.85%. During the heat preservation process of the first aluminum alloy solution, stirring, refining, degassing, and removal of slag are continuously carried out.

[0037] In a preferred embodiment, during the second alloying element addition step, after adding elemental tin, elemental antimony, and aluminum-calcium alloy, the stirring time is 1-3 min and the settling time is 5-10 min; the purity of elemental tin and elemental antimony is not less than 99.99%, and the impurity content in the aluminum-calcium alloy is ≤0.1%.

[0038] In a preferred embodiment, the method further includes: placing the core in a mold, casting the second aluminum alloy solution into a preheated mold, and cooling and shaping to obtain the aluminum alloy sacrificial anode, wherein the preheating temperature of the preheated mold is 150-300°C.

[0039] Specifically, during smelting, aluminum ingots are first heated to 780-820℃ in a crucible until completely melted into molten aluminum. Then, elemental zinc and aluminum-silicon alloy are added to the molten aluminum according to the formula ratio. The mixture is then gently stirred with a carbon rod to ensure uniform distribution of the alloying elements. The molten aluminum alloy in the crucible furnace is cooled to 680-720℃ and held for 30-60 minutes, during which continuous stirring, refining, degassing, and removal of scum are performed. The molten aluminum alloy is then rapidly heated at a rate of no less than 5℃ / min to 820-850℃. Elemental tin, elemental antimony, and aluminum-calcium alloy are then added and stirred for 1-3 minutes to rapidly melt and uniformly distribute the alloying elements. Stirring is then stopped, and the mixture is allowed to stand for 5-10 minutes to separate the scum from the molten metal. The scum is then skimmed off. The mold is preheated to 150-300℃, and the molten aluminum alloy is poured into the mold. After cooling and solidification, the mold is opened, and the aluminum alloy sacrificial anode material is removed. The mixture is then further cooled to room temperature in air.

[0040] This invention significantly improves the electrochemical performance of sacrificial anodes in high-temperature, high-salinity, and oily environments by adding alloying elements such as zinc (Zn), tin (Sn), silicon (Si), antimony (Sb), and calcium (Ca) and employing a two-stage alloying element addition process, thereby improving the surface dissolution morphology. In an FPSO environment of 50-80℃, salinity 20-35‰, and pH 3.5-6.5, the anode's operating potential is between -1.00 and -1.15V (relative to a silver chloride seawater electrode), with a capacitance ≥2200 A•h / kg. The anode dissolution is uniform, and corrosion products are easily detached, solving the problem of severe localized corrosion and low current efficiency in conventional Al-Zn-In aluminum alloys in FPSO environments.

[0041] To provide a clearer and more detailed description of the highly activated aluminum sacrificial anode for FPSO and its preparation method provided in the embodiments of the present invention, the following description will be based on specific embodiments.

[0042] Example 1

[0043] The sacrificial anode body of the aluminum alloy sacrificial anode for FPSO oil storage tanks has the following formula (by weight percentage): Zn 2%, Sn 0.03%, Si 0.05%, Sb 0.006%, Ca 0.005%, impurities Fe≤0.09%, Cu≤0.005%, and the balance is Al.

[0044] Aluminum ingots with an aluminum content ≥99.85% were heated to 780℃ in a crucible melting furnace to completely melt the ingots. Then, elemental zinc and aluminum-silicon alloy were added according to the formula ratio and melted. The mixture was then gently stirred with a carbon rod to ensure uniform distribution of the alloying elements. The aluminum alloy solution in the crucible furnace was cooled to 680℃ and held for 60 min, during which continuous stirring, refining, degassing, and slag removal were performed. The aluminum alloy solution was then heated at a rate of 5℃ / min to 850℃. Elemental tin, elemental antimony, and aluminum-calcium alloy were added according to the formula ratio, and stirring was stopped after 3 min. After standing for 10 min, slag was skimmed off. The mold was preheated to 150℃, and the aluminum alloy solution was poured into the mold. After cooling and solidification, the mold was opened, and the aluminum alloy sacrificial anode material was removed. It was then further cooled to room temperature in air to obtain the aluminum alloy sacrificial anode for FPSO oil storage tanks.

[0045] The electrochemical performance of the aluminum alloy sacrificial anode for the FPSO oil storage tank obtained in Example 1 was tested according to the standard test method specified in GB / T 17848-1999. The test medium was simulated FPSO environment containing oily seawater with a salinity of 35‰ and a pH of 6.5. The test temperature was 50℃, and the reference electrode was a silver chloride seawater electrode. Specific experimental results are shown in Table 1. The open-circuit potential was between -1.10V and -1.15V, the operating potential was between -1.00V and -1.15V, the capacitance was 2564 Ah / kg, the sacrificial anode surface showed uniform dissolution, and the corrosion products were easily detached. A comparison of the surface dissolution morphology of the aluminum alloy sacrificial anode material after corrosion is shown in the figure below. Figure 1 , 2 As shown, where, Figure 2 This is a corrosion and dissolution morphology diagram of a conventional Al-Zn-In-Si anode. Figure 1 This is a surface dissolution morphology diagram of the aluminum alloy sacrificial anode material obtained in this embodiment after corrosion.

[0046] Example 2

[0047] The sacrificial anode body of the aluminum alloy sacrificial anode for FPSO oil storage tanks has the following formula (by weight percentage): Zn 6%, Sn 0.25%, Si 0.20%, Sb 0.05%, Ca 0.15%, impurities Fe≤0.09%, Cu≤0.005%, and the balance is Al.

[0048] Aluminum ingots with an aluminum content ≥99.85% were heated to 820℃ in a crucible melting furnace to completely melt the ingots. Then, elemental zinc and aluminum-silicon alloy were added according to the formula ratio and melted. The mixture was then gently stirred with a carbon rod to ensure uniform distribution of the alloying elements. The aluminum alloy solution in the crucible furnace was cooled to 720℃ and held for 30 min, during which continuous stirring, refining, degassing, and slag removal were performed. The aluminum alloy solution was then heated at a rate of 10℃ / min to 820℃. Elemental tin, elemental antimony, and aluminum-calcium alloy were added according to the formula ratio, and stirring was stopped after 1 min. After standing for 5 min, slag was skimmed off. The mold was preheated to 300℃, and the aluminum alloy solution was poured into the mold. After cooling and solidification, the mold was opened, and the aluminum alloy sacrificial anode material was removed. It was then further cooled to room temperature in air to obtain the aluminum alloy sacrificial anode for FPSO oil storage tanks.

[0049] The electrochemical performance of the aluminum alloy sacrificial anode for the FPSO oil storage tank obtained in Example 2 was tested according to the standard test method specified in GB / T 17848-1999. The test medium was simulated FPSO environment containing oily seawater with a salinity of 20‰ and a pH of 3.5. The test temperature was 70℃, and the reference electrode was a silver chloride seawater electrode. The specific experimental results are shown in Table 1. Its open circuit potential is between -1.05V and -1.10V, its operating potential is between -1.00V and -1.10V, its capacitance is 2278 Ah / kg, the sacrificial anode surface is uniformly dissolved, and the corrosion products are easily detached.

[0050] Example 3

[0051] The sacrificial anode body of the aluminum alloy sacrificial anode for FPSO oil storage tanks has the following formula (by weight percentage): Zn 4%, Sn 0.10%, Si 0.10%, Sb 0.03%, Ca 0.07%, impurities Fe≤0.09%, Cu≤0.005%, and the balance is Al.

[0052] Aluminum ingots with an aluminum content ≥99.85% were heated to 800℃ in a crucible melting furnace to completely melt the ingots. Then, elemental zinc and aluminum-silicon alloy were added according to the formula and melted. The mixture was then gently stirred with a carbon rod to ensure uniform distribution of the alloying elements. The aluminum alloy solution in the crucible furnace was cooled to 700℃ and held for 45 min, during which continuous stirring, refining, degassing, and slag removal were performed. The aluminum alloy solution was then heated at a rate of 15℃ / min to 850℃. Elemental tin, antimony, and calcium were added according to the formula, and stirring was stopped after 2 min. After standing for 8 min, slag was skimmed off. The mold was preheated to 200℃, and the aluminum alloy solution was poured into the mold. After cooling and solidification, the mold was opened, and the aluminum alloy sacrificial anode material was removed. It was then further cooled to room temperature in air to obtain the aluminum alloy sacrificial anode for FPSO oil storage tanks.

[0053] The electrochemical performance of the aluminum alloy sacrificial anode for the FPSO oil storage tank obtained in Example 3 was tested according to the standard test method specified in GB / T 17848-1999. The test medium was simulated FPSO environment containing oil and contaminated seawater with a salinity of 30‰ and a pH of 5. The test temperature was 80℃, and the reference electrode was a silver chloride seawater electrode. The specific experimental results are shown in Table 1. Its open circuit potential was between -1.07V and -1.15V, its operating potential was between -1.04V and -1.12V, its capacitance was 2413 Ah / kg, the sacrificial anode surface was uniformly dissolved, and the corrosion products were easily detached.

[0054] Performance testing

[0055] The performance test results of the examples and comparative examples are shown in Table 1.

[0056] Table 1 Electrochemical performance of low-driving-potential aluminum alloy sacrificial anodes

[0057]

Claims

1. A highly activated aluminum sacrificial anode for FPSO, characterized in that, The cathodic protection for FPSO includes a sacrificial anode body and a core enclosed within the sacrificial anode body. The sacrificial anode body is mainly composed of Al, and also includes Zn, Sn, Si, Sb and Ca. By mass percentage, Sn is selected from 0.03-0.25%, Sb is selected from 0.006%-0.05%, and the weight ratio of Sn to Sb is 5:1-3:

1. By mass percentage, the Zn is selected from 2-6%, the Si is selected from 0.05-0.20%, the Ca is selected from 0.005-0.15%, the impurity content is ≤0.15%, the balance is Al, and the total content of the Sn and Sb does not exceed 0.25%. The method for preparing a highly activated aluminum sacrificial anode for FPSO includes a first alloying element addition step and a second alloying element addition step; The first alloying element addition step includes: heating the aluminum ingot to completely melt it into an aluminum solution, adding zinc and aluminum-silicon alloy, stirring to rapidly melt the alloying elements into a first aluminum alloy solution, cooling the first aluminum alloy solution to 680-720℃, and holding it at that temperature for 30-60 minutes. The second alloying element addition step includes: heating the first aluminum alloy solution to 820-850°C at a heating rate of not less than 5°C / min, then adding elemental tin, elemental antimony, and aluminum-calcium alloy, and stirring evenly to obtain the second aluminum alloy solution.

2. The highly activated aluminum sacrificial anode for FPSO according to claim 1, characterized in that, The mass percentage of Sn is 0.10-0.15%, and the mass percentage of Sb is 0.03-0.05%.

3. The highly activated aluminum sacrificial anode for FPSO according to claim 1, characterized in that, The impurities, by mass percentage, contain Fe ≤ 0.09% and Cu ≤ 0.005%.

4. The highly activated aluminum sacrificial anode for FPSO according to claim 1, characterized in that, The mass percentage of Si is 0.05-0.10%; the mass percentage of Ca is 0.03-0.06%.

5. The highly activated aluminum sacrificial anode for FPSO according to claim 1, characterized in that, The core is an iron core.

6. The method for preparing a highly activated aluminum sacrificial anode for FPSO according to any one of claims 1-5, characterized in that, During the first alloying element addition step, the aluminum ingot is heated to 780-820℃ and completely melted into an aluminum solution. The purity of the aluminum ingot is not less than 99.85%. During the heat preservation process of the first aluminum alloy solution, it is continuously stirred, refined, degassed, and slag is removed.

7. The method for preparing a highly activated aluminum sacrificial anode for FPSO according to claim 6, characterized in that, During the second alloying element addition step, after adding elemental tin, elemental antimony, and aluminum-calcium alloy, the stirring time is 1-3 minutes and the standing time is 5-10 minutes; the purity of elemental tin and elemental antimony is not less than 99.99%, and the impurity content in the aluminum-calcium alloy is ≤0.1%.

8. The method for preparing a highly activated aluminum sacrificial anode for FPSO according to claim 6, characterized in that, Also includes: The core is placed in the mold, and the second aluminum alloy solution is poured into the preheated mold and cooled to form the aluminum alloy sacrificial anode. The preheating temperature of the preheated mold is 150-300℃.

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