Marine plant system and method for controlling the same

Abstract

To provide a marine plant system that can operate properly and have excellent productivity even in a case where alginate cannot be produced.SOLUTION: A marine plant system according to one aspect of the present disclosure comprises: a biochar production apparatus configured to produce biochar from seaweed collected from the sea; an alginate production apparatus configured to produce alginate from the seaweed; a power generation apparatus configured to supply electric power generated using renewable energy to the biochar production apparatus and the alginate production apparatus; and a controller configured to control production of the biochar and production of the alginate. When an amount of the electric power is smaller than a predetermined reference value, the controller selects production of the biochar.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a marine plant system and a control method thereof. [Background technology]

[0002] As shown in Patent Document 1, the inventor has developed a marine plant system that cultivates seaweed, absorbs carbon dioxide from the air, and produces various products from the seaweed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent application 2022-134259 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventor is studying a marine plant system that produces alginic acid from seaweed using electricity generated from renewable energy. The use of renewable energy can reduce the LCA (Life Cycle Assessment) of the alginic acid produced. However, if alginic acid cannot be produced due to factors such as a power shortage, the marine plant system must be shut down, resulting in a significant drop in productivity.

[0005] The present disclosure has been made in consideration of the above circumstances, and provides a marine plant system that operates appropriately and has excellent productivity even when alginic acid cannot be produced. [Means for solving the problem]

[0006] A marine plant system according to one aspect of the present disclosure includes: A biochar production device that produces biochar from seaweed collected from the ocean; an alginic acid production apparatus for producing alginic acid from the seaweed; a power generation device that supplies electricity generated using renewable energy to the biochar production device and the alginic acid production device; a controller for controlling the production of the biochar and the production of the alginic acid; The controller If the amount of electricity is less than a predetermined reference value, the biochar production is selected.

[0007] In a marine plant system according to one embodiment of the present disclosure, if the amount of electricity is less than a predetermined reference value, biochar production is selected. In other words, if the marine plant system is unable to produce alginic acid due to a lack of electricity, biochar production is selected and the system operates appropriately, resulting in excellent productivity.

[0008] The marine plant system may further include an intermediate raw material manufacturing device that manufactures an intermediate raw material for manufacturing the alginic acid, and the controller may select the manufacture of the intermediate raw material when the amount of the intermediate raw material is smaller than a predetermined reference value. In other words, when alginic acid cannot be manufactured due to a shortage of intermediate raw materials, the marine plant system selects the manufacture of intermediate raw materials and operates appropriately, thereby achieving excellent productivity.

[0009] The marine plant system may further include a seawater treatment device that separates seawater into freshwater and concentrated seawater, and an electrolyzer that electrolyzes the concentrated seawater separated by the seawater treatment device. The intermediate raw material production device produces calcium chloride and sodium bicarbonate from calcium carbonate using the freshwater separated by the seawater treatment device and hydrogen gas, chlorine gas, and sodium hydroxide produced by the electrolyzer. The alginic acid production device extracts alginic acid from the seaweed and produces calcium alginate using the calcium chloride and sodium bicarbonate produced by the intermediate raw material production device. That is, the marine plant system electrolyzes the concentrated seawater separated by the seawater treatment device using the electrolyzer to produce hydrogen gas, chlorine gas, and sodium hydroxide. Therefore, there is no need to purchase and transport the hydrochloric acid and sodium hydroxide required for calcium alginate production to the marine plant system by container ship, etc., thereby significantly reducing the LCA of the calcium alginate produced.

[0010] The marine plant system may further include a storage device for storing residue generated in the alginic acid production apparatus and a boiler for combusting the residue, and the controller may select combustion of the residue stored in the storage device by the boiler when the available space in the storage device is less than a predetermined reference value. In other words, when alginic acid cannot be produced due to a lack of available space in the storage device, the marine plant system selects combustion of the residue stored in the storage device by the boiler and operates appropriately, resulting in excellent productivity.

[0011] Calcium carbonate contained in ash generated in the boiler may be supplied to the intermediate raw material production device, eliminating the need to purchase calcium carbonate required for calcium alginate production and transport it to the marine plant system by container ship or the like, thereby reducing the LCA of the calcium alginate produced.

[0012] A method for controlling a marine plant system according to one aspect of the present disclosure includes: A biochar production device that produces biochar from seaweed collected from the ocean; an alginic acid production apparatus for producing alginic acid from the seaweed; A power generation device that supplies electricity generated using renewable energy to the biochar production device and the alginic acid production device, a controller for controlling the production of the biochar and the production of the alginic acid, If the amount of electricity is less than a predetermined reference value, the biochar production is selected.

[0013] In a marine plant system control method according to one embodiment of the present disclosure, biochar production is selected when the amount of power is less than a predetermined reference value. In other words, when the marine plant system is unable to produce alginic acid due to a lack of power, the marine plant system selects biochar production and operates appropriately, resulting in excellent productivity.

[0014] The marine plant system may further include an intermediate raw material production device that produces intermediate raw materials for producing the alginic acid, and the controller may select the production of the intermediate raw materials when the amount of the intermediate raw materials is smaller than a predetermined reference value. In other words, when the marine plant system cannot produce alginic acid due to a shortage of intermediate raw materials, the marine plant system selects the production of intermediate raw materials and operates appropriately, resulting in excellent productivity.

[0015] The marine plant system may further include a seawater treatment device that separates seawater into freshwater and concentrated seawater, and an electrolyzer that electrolyzes the concentrated seawater separated by the seawater treatment device. The intermediate raw material production device may produce calcium chloride and sodium bicarbonate from calcium carbonate using the freshwater separated by the seawater treatment device and hydrogen gas, chlorine gas, and sodium hydroxide produced by the electrolyzer. The alginic acid production device may extract alginic acid from the seaweed and produce calcium alginate using the calcium chloride and sodium bicarbonate produced by the intermediate raw material production device. That is, the marine plant system electrolyzes the concentrated seawater separated by the seawater treatment device using the electrolyzer to produce hydrogen gas, chlorine gas, and sodium hydroxide. Therefore, there is no need to purchase and transport the hydrochloric acid and sodium hydroxide required for calcium alginate production to the marine plant system by container ship, etc., thereby significantly reducing the LCA of the calcium alginate produced.

[0016] The marine plant system may further include a storage device for storing residue generated in the alginic acid production apparatus and a boiler for combusting the residue, and the controller may select combustion of the residue stored in the storage device in the boiler when the available space in the storage device is less than a predetermined reference value. In other words, when the marine plant system determines that alginic acid cannot be produced due to a lack of available space in the storage device, it selects combustion of the residue stored in the storage device in the boiler and operates appropriately, resulting in excellent productivity.

[0017] Calcium carbonate contained in ash generated in the boiler may be supplied to the intermediate raw material production device, eliminating the need to purchase calcium carbonate required for calcium alginate production and transport it to the marine plant system by container ship or the like, thereby reducing the LCA of the calcium alginate produced. [Effects of the Invention]

[0018] The present disclosure makes it possible to provide a marine plant system that operates properly and has excellent productivity even when alginic acid cannot be produced. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram showing a configuration of a marine plant system according to a first embodiment. [Figure 2] 1 is a block diagram showing an example of the configuration of a seawater treatment device 10. FIG. [Figure 3] FIG. 1 is a schematic diagram showing an example of the configuration of an electrolyzer 20. [Figure 4] 3 is a flowchart showing a control method for a marine plant system according to the first embodiment. [Figure 5] 1 is a flowchart showing a method for producing calcium alginate according to a first embodiment. [Figure 6] 6 is a flowchart showing an example of details of step ST4 in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, specific embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0021] (First embodiment) <Marine plant system configuration> First, the configuration of the marine plant system according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of the marine plant system according to the first embodiment. As shown in Figure 1, the marine plant system of this embodiment includes a seawater treatment device 10, an electrolysis device 20, an intermediate raw material production device 30, an alginic acid production device 40, a power generation device 50, a boiler 60, a biochar production device 70, a storage device 80, and a controller 100.

[0022] As shown in Fig. 1, a seawater treatment device 10 is, for example, a seawater desalination device that separates seawater into fresh water and concentrated seawater. That is, the seawater treatment device 10 produces fresh water and concentrated seawater from seawater. The fresh water separated by the seawater treatment device 10 is supplied to an intermediate raw material production device 30. On the other hand, the concentrated seawater separated by the seawater treatment device 10 is supplied to an electrolysis device 20. Conventionally, concentrated seawater separated by a seawater desalination device has been discarded, for example, into the sea, but the marine plant system according to this embodiment makes effective use of the concentrated seawater.

[0023] The freshwater separated by the seawater treatment device 10 can be used for a variety of purposes. Therefore, the freshwater may be supplied not only to the intermediate raw material production device 30 but also to the electrolysis device 20, the alginic acid production device 40, etc.

[0024] Here, Fig. 2 is a block diagram showing an example of the configuration of a seawater treatment device 10. The seawater treatment device 10 shown in Fig. 2 includes a reverse osmosis membrane module 11 and a pump 12. As shown in Fig. 2, the reverse osmosis membrane module 11 includes a reverse osmosis membrane RO. Seawater is pressure-fed from the pump 12 to the reverse osmosis membrane module 11, and is separated into freshwater that has passed through the reverse osmosis membrane RO and concentrated seawater that has not passed through the reverse osmosis membrane RO.

[0025] In the seawater treatment device 10, by using a reverse osmosis membrane RO, seawater can be separated into fresh water and concentrated seawater simply and inexpensively. The method for separating seawater into freshwater and concentrated seawater is not particularly limited, and an ion exchange membrane may be used instead of the reverse osmosis membrane RO. Fig. 2 shows a schematic diagram of the separation of seawater into freshwater and concentrated seawater by the reverse osmosis membrane RO, and does not necessarily show the actual structure of the seawater treatment device 10.

[0026] As shown in Fig. 1, the electrolyzer 20 electrolyzes the concentrated seawater separated by the seawater treatment device 10. Hydrogen gas (H2), chlorine gas (Cl2), and sodium hydroxide (NaOH) are produced by the electrolysis of the concentrated seawater in the seawater treatment device 10. The H2, Cl2, and NaOH produced by the electrolyzer 20 are supplied to the intermediate raw material production device 30.

[0027] Here, Fig. 3 is a schematic diagram showing an example of the configuration of an electrolyzer 20. The electrolyzer 20 shown in Fig. 3 includes a DC power supply, an anode AN, a cathode CT, and a cation exchange membrane CEM. As shown in Fig. 3, the cation exchange membrane CEM separates the anode chamber from the cathode chamber.

[0028] As shown in Figure 3, concentrated seawater (NaCl) is supplied to the anode chamber. In the anode chamber, chloride ions (Cl - ) releases electrons to the anode AN, generating chlorine gas (Cl2). + ) passes through the cation exchange membrane CEM and moves to the cathode chamber. As a result, the NaCl concentration in the anode chamber decreases and fresh salt water is discharged from the anode chamber.

[0029] On the other hand, fresh water is supplied to the cathode chamber. This fresh water is, for example, fresh water separated by the seawater treatment device 10. In the cathode chamber, water (H2O) receives electrons from the cathode CT, generating hydrogen gas (H2) and hydroxide ions (OH - ) is generated, and hydroxide ions (OH - ) is sodium ion (Na + ) to produce sodium hydroxide (NaOH).

[0030] That is, throughout the electrolyzer 20, the reaction shown in the following chemical reaction formula (1) occurs. 2NaCl+2H2O→Cl2+H2+2NaOH···(1) Instead of fresh water, a dilute aqueous sodium hydroxide solution may be supplied to the cathode chamber.

[0031] The intermediate raw material production equipment 30 is supplied with fresh water separated by the seawater treatment device 10 and H, Cl, and NaOH produced by the electrolysis device 20. The intermediate raw material production equipment 30 then produces calcium chloride (CaCl) and sodium bicarbonate (NaHCO) from calcium carbonate (CaCO) using the fresh water, H, Cl, and NaOH.

[0032] First, hydrogen chloride (HCl) is produced from H2 and Cl2 as shown in the following chemical reaction formula (2). H2 + Cl2 → 2HCl (2) When HCl is absorbed into fresh water, hydrochloric acid (HClaq) is obtained.

[0033] Next, as shown in the following chemical reaction formula (3), hydrochloric acid and CaCO3 react to produce CaCl2. 2HClaq+CaCO3→H2O+CO2+CaCl2···(3)

[0034] Next, as shown in the following chemical reaction formula (4), the carbon dioxide (CO2) generated in chemical reaction formula (3) reacts with the sodium hydroxide aqueous solution (NaOHaq) to produce a sodium bicarbonate aqueous solution (NaHCO3aq). NaOHaq+CO2→NaHCO3aq···(4)

[0035] The alginic acid production apparatus 40 uses the CaCl2 and NaHCO3 produced by the intermediate raw material production apparatus 30 to extract alginic acid from seaweed collected from the sea and produce calcium alginate.

[0036] First, as shown in the following chemical reaction formula (5), NaHCO3 produced by the intermediate raw material production device 30 is added to seaweed, and alginic acid in the seaweed is extracted as soluble sodium alginate. Here, alginic acid in the seaweed is extracted as soluble sodium alginate, for example, by adding Ca 2+ It combines with multivalent cations such as thiamin and thiamin to form insoluble salts. Calcium alginate (in seaweed) + 2NaHCO3 →2Sodium alginate + Ca(HCO3)2···(5)

[0037] Next, as shown in the following chemical reaction formula (6), CaCl2 produced by the intermediate raw material production device 30 is added to the sodium alginate extract to precipitate insoluble calcium alginate. 2 Sodium alginate + CaCl2 →Calcium alginate + 2NaCl (6) As a result of the above, the product calcium alginate is obtained.

[0038] The various processes performed in the alginic acid production apparatus 40 will be described in detail later. Alternatively, dilute sulfuric acid may be added to the sodium alginate extract in place of CaCl2 to precipitate free alginic acid instead of calcium alginate.

[0039] As shown in FIG. 1, the power generation device 50 supplies electricity generated using renewable energy. The power generation device 50 is one of or a combination of a solar power generation device, a wind power generation device, and a hydrogen power generation device. Here, since solar power generation devices and wind power generation devices are dependent on the weather, it is difficult to provide a stable supply of electricity, which can lead to power shortages. The hydrogen power generation device may be, for example, a fuel cell, and may generate electricity using H2 produced by the electrolyzer 20.

[0040] 1 includes a turbine (not shown) that generates electricity using steam generated by a boiler 60, which will be described later, but the turbine is not essential. Furthermore, the power generation device 50 may also include a battery (not shown) that stores the generated electricity. As shown in FIG. 1, the electric power generated by the power generation device 50 is supplied to, for example, a seawater treatment device 10, an electrolysis device 20, a biochar production device 70, and the like.

[0041] More specifically, the electricity generated by the power generation device 50 is supplied to, for example, the pump 12 of the seawater treatment device 10 shown in Fig. 2, the DC power supply of the electrolysis device 20 shown in Fig. 3, and a heater (not shown) of the biochar production device 70 described below. This configuration can reduce the LCA of the calcium alginate and biochar produced.

[0042] As shown in Fig. 1, the boiler 60 is a device that burns the residue (seaweed after alginic acid extraction) generated in the alginic acid production apparatus 40. The calcium carbonate (CaCO3) contained in the residue, i.e., ash, burned in the boiler 60 is supplied to the intermediate raw material production apparatus 30.

[0043] Therefore, there is no need to purchase CaCO3, which is necessary for producing calcium alginate, and transport it to the marine plant system by container ship, etc., which further reduces the LCA of the calcium alginate produced.

[0044] Furthermore, by burning the residue in the boiler 60, the amount of residue stored in the storage device 80 can be reduced, freeing up space and reducing the amount of waste. Furthermore, the steam generated by the boiler 60 can be used to rotate the turbine of the power generation unit 50 to generate electricity. By using this electricity, the LCA of the calcium alginate and biochar produced can be reduced.

[0045] Biochar production apparatus 70 produces biochar from seaweed collected from the ocean. More specifically, biochar production apparatus 70 heats dried seaweed in a low-oxygen atmosphere using a heater (not shown), for example, to about 300°C. A low-oxygen atmosphere is an atmosphere with an oxygen concentration lower than that of the atmosphere, for example, an oxygen concentration of 1% by volume or less. Compared to alginate production, biochar production consumes less electricity and generates significantly less residue.

[0046] The storage device 80 stores, for example, the products calcium alginate and biochar, as well as residues generated during production. The storage device 80 may also store NaOH produced by the electrolyzer 20, intermediate raw materials such as HClaq, CaCl, and NaHCO produced by the intermediate raw material production device 30, and residues, i.e., ash (including CaCO), generated by combustion in the boiler 60.

[0047] The controller 100 controls the production of biochar and the production of alginic acid, for example, controlling the entire marine plant system. More specifically, the controller 100 controls the allocation between the production of biochar by the biochar production apparatus 70 and the production of alginic acid by the alginic acid production apparatus 40 based on predetermined criteria. The predetermined criteria include, for example, the amount of available electricity, the amount of intermediate raw materials, and the available space in the storage device 80. Here, the amount of available electricity is, for example, the sum of the amount of electricity stored in the battery provided in the power generation device 50 and the predicted amount of electricity generated by the power generation device 50.

[0048] Here, the controller 100 determines whether or not alginic acid can be produced based on the above-mentioned predetermined determination conditions, and if it determines that alginic acid can be produced, it selects the production of alginic acid. In other words, in the marine plant system according to this embodiment, the production of alginic acid is prioritized.

[0049] On the other hand, if the controller 100 determines that alginic acid cannot be produced due to a power shortage, it selects the production of biochar, which consumes less power.Even when alginic acid cannot be produced due to a power shortage, biochar can be produced without shutting down the marine plant system, resulting in excellent productivity.

[0050] Furthermore, if the controller 100 determines that alginic acid cannot be produced due to a shortage of intermediate raw materials (e.g., HClaq, CaCl2, NaHCO3, etc.) even though there is sufficient power, it selects the production of the intermediate raw materials. By producing the intermediate raw materials, the shortage of intermediate raw materials can be resolved, making it possible to produce alginic acid. In this way, even when alginic acid cannot be produced, intermediate raw materials can be produced without shutting down the marine plant system, resulting in excellent productivity.

[0051] Furthermore, if the controller 100 determines that there is sufficient power but that alginic acid cannot be produced due to a lack of free space, it selects burning the residue stored in the storage device 80 in the boiler 60. Burning the residue in the boiler 60 resolves the lack of free space and enables the production of alginic acid. In this way, even when alginic acid cannot be produced, the residue can be burned in the boiler 60 without shutting down the marine plant system, resulting in excellent productivity.

[0052] As described above, the marine plant system according to this embodiment has excellent productivity because, even if it is determined that alginic acid cannot be produced, it continues to operate appropriately depending on the cause of the determination. On the other hand, the marine plant system according to this embodiment preferentially produces alginic acid.

[0053] In addition, in the marine plant system according to this embodiment, concentrated seawater separated by the seawater treatment device 10 is electrolyzed by the electrolyzer 20 to produce HCl and NaOH. In other words, there is no need to purchase HCl and NaOH, which are necessary for producing calcium alginate, and transport them to the marine plant system by container ship or the like, which significantly reduces the LCA of the calcium alginate produced.

[0054] Specifically, in conventional calcium alginate production, CO2 emissions per kg of product are approximately 3.0 to 4.5 kg-CO2 / kg-product. In the marine plant system according to this embodiment, CO2 emissions per kg of product can be significantly reduced to less than 1.0 / kg-product, i.e., approximately 1 / 3 to 1 / 4 or less.

[0055] In the marine plant system according to this embodiment, the alginic acid production apparatus 40, the power generation apparatus 50, the biochar production apparatus 70, and the controller 100 shown in Fig. 1 are essential. On the other hand, the seawater treatment device 10, the electrolysis device 20, the intermediate raw material production apparatus 30, the boiler 60, and the storage device 80 shown in Fig. 1 are not essential.

[0056] <Control method for marine plant system> Next, a control method by the controller 100 of the marine plant system according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the control method of the marine plant system according to the first embodiment. In describing Fig. 4, Fig. 1 will be referred to as appropriate.

[0057] First, as shown in Fig. 4, the controller 100 determines whether or not alginic acid can be produced based on the above-mentioned predetermined determination conditions (step ST101). In the control method for a marine plant system shown in Fig. 4, the determination conditions are three: available power amount, amount of intermediate raw materials, and available space. If it is determined that alginic acid can be produced (YES in step ST101), the controller 100 selects the production of alginic acid (step ST102). Then, the controller 100 ends the control operation.

[0058] On the other hand, if it is determined that alginic acid cannot be produced (NO in step ST101), the controller 100 determines whether the reason is a lack of available power (step ST103). If it is determined that the amount of available power is less than a predetermined reference value and there is a power shortage (YES in step ST103), the controller 100 selects the production of biochar (step ST104). Then, the controller 100 ends the control operation.

[0059] On the other hand, if the amount of available power is equal to or greater than the predetermined reference value and it is determined that there is sufficient power (NO in step ST103), the controller 100 determines whether or not the intermediate raw materials are insufficient, which is the reason why alginic acid cannot be produced (step ST105). If the amount of intermediate raw materials is less than the predetermined reference value and it is determined that there is a shortage of intermediate raw materials (YES in step ST105), the controller 100 selects the production of intermediate raw materials (step ST106). After the intermediate raw materials are produced, the controller 100 updates the amount of available intermediate raw materials, returns to step ST101, and again determines whether or not alginic acid can be produced.

[0060] On the other hand, if it is determined that the amount of intermediate raw material is equal to or greater than the predetermined reference value and that there is a sufficient amount of intermediate raw material (NO in step ST105), the controller 100 determines that the reason for the inability to produce alginic acid is a lack of free space (step ST107). That is, if the free space is less than the predetermined reference value and is insufficient, the controller 100 selects burning the residue stored in the storage device 80 in the boiler 60.

[0061] After the residue stored in the storage device 80 is transferred to the boiler 60, the controller 100 updates the available free space and returns to step ST101 to determine again whether or not alginic acid can be produced. If it is determined that alginic acid can be produced, the residue may be burned in the boiler 60 to produce alginic acid.

[0062] As described above, the control method for the marine plant system according to this embodiment first determines whether or not alginic acid can be produced, and then prioritizes the production of alginic acid. On the other hand, even if it is determined that alginic acid cannot be produced, the marine plant system according to this embodiment operates appropriately depending on the cause, thereby achieving excellent productivity.

[0063] In the marine plant system control method shown in Figure 4, the conditions for determining whether alginic acid can be produced are the amount of available electricity, the amount of intermediate raw materials, and available space, but other conditions may also be included. On the other hand, the amount of available electricity is an essential condition for determination, but the amount of available intermediate raw materials and available space are not essential conditions for determination. Furthermore, a lack of available available space may be determined before determining a lack of available intermediate raw materials.

[0064] <Method of manufacturing calcium alginate> Next, a method for producing calcium alginate according to the first embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the method for producing calcium alginate according to the first embodiment. In describing Fig. 5, Fig. 1 will be referred to as appropriate.

[0065] First, as shown in FIG. 5, seawater is separated into fresh water and concentrated seawater in the seawater treatment device 10 shown in FIG. 1 (step ST1). Next, as shown in FIG. 5, the separated concentrated seawater is electrolyzed in the electrolyzer 20 shown in FIG. 1 to produce H2, Cl2, and NaOH (step ST2).

[0066] Next, as shown in FIG. 5, in the intermediate raw material manufacturing apparatus 30 shown in FIG. 1, CaCl and NaHCO are manufactured from CaCO using the fresh water separated in step ST1 and the H, Cl, and NaOH produced in step ST2 (step ST3).

[0067] Finally, as shown in FIG. 5, in the alginic acid production apparatus 40 shown in FIG. 1, alginic acid is extracted from the seaweed using CaCl2 and NaHCO3 produced in step ST3, and calcium alginate is produced (step ST4).

[0068] Next, step ST4 in Fig. 5 will be described in detail with reference to Fig. 6. Fig. 6 is a flowchart showing an example of the details of step ST4 in Fig. 5. 6, in an alginic acid producing apparatus 40, seaweed collected from the sea is washed with fresh water and swelled in the fresh water (step ST41). Here, the seaweed may be crushed in advance before step ST41.

[0069] Next, as shown in FIG. 6, in an alginic acid production apparatus 40, NaHCO3 is added to the washed and swollen seaweed to extract sodium alginate (step ST42). 2+ It combines with polyvalent cations such as Calcium to form insoluble salts. 2+ The aqueous solution containing water-soluble sodium alginate is extracted by ion exchange between sodium and polyvalent cations such as sodium alginate. This aqueous solution is called sodium alginate extract.

[0070] 6, in an alginic acid production apparatus 40, fresh water is added to the sodium alginate extract to dilute it, separate it from the seaweed, and filter it (step ST43). The fresh water added here is, for example, fresh water separated by a seawater treatment device 10. Dilution reduces the viscosity, making it easier to separate the sodium alginate extract from the seaweed and filter it.

[0071] Next, as shown in FIG. 6, in an alginic acid production apparatus 40, CaCl2 produced by the intermediate raw material production apparatus 30 is added to the filtered sodium alginate extract to precipitate insoluble calcium alginate (step ST44).

[0072] Finally, as shown in FIG. 6, the calcium alginate precipitated by dehydration is collected in an alginic acid production apparatus 40 (step ST45). Through the above series of processes, alginic acid is extracted from seaweed in the alginic acid production apparatus 40, and calcium alginate is produced.

[0073] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present disclosure. This disclosure also promotes the use of blue carbon (seaweed) and contributes to carbon neutrality, decarbonization, and the Sustainable Development Goals (SDGs). [Explanation of symbols]

[0074] 10 Seawater treatment equipment 11 Reverse osmosis membrane module 12 Pump 20 Electrolyzer 30 Intermediate raw material manufacturing equipment 40 Alginic acid manufacturing equipment 50 Power Generation Equipment 60 Boiler 70 Biochar production equipment 80 Storage Device 100 Controllers AN anode CEM Cation Exchange Membrane CT cathode RO reverse osmosis membrane

Claims

1. A biochar production device that produces biochar from seaweed collected from the ocean; an alginic acid production apparatus for producing alginic acid from the seaweed; a power generation device that supplies electricity generated using renewable energy to the biochar production device and the alginic acid production device; a controller for controlling the production of the biochar and the production of the alginic acid; The controller If the amount of electricity is less than a predetermined reference value, selecting the production of biochar. Marine plant systems.

2. Further provided is an intermediate raw material manufacturing device for manufacturing an intermediate raw material for manufacturing the alginic acid, The controller If the amount of the intermediate material is less than a predetermined reference value, select to produce the intermediate material; The marine plant system according to claim 1 .

3. a seawater treatment device that separates seawater into fresh water and concentrated seawater; An electrolysis device that electrolyzes the concentrated seawater separated by the seawater treatment device, the intermediate raw material production device produces calcium chloride and sodium bicarbonate from calcium carbonate using the fresh water separated by the seawater treatment device and the hydrogen gas, chlorine gas, and sodium hydroxide produced by the electrolysis device; The alginic acid production apparatus extracts alginic acid from the seaweed and produces calcium alginate using calcium chloride and sodium bicarbonate produced by the intermediate raw material production apparatus. The marine plant system according to claim 2 .

4. A storage device for storing residue generated in the alginic acid production apparatus; a boiler for burning the residue; The controller If the free space in the storage device is less than a predetermined reference value, selecting to burn the residue stored in the storage device by a boiler. The marine plant system according to any one of claims 1 to 3.

5. supplying calcium carbonate contained in ash generated in the boiler to the intermediate raw material manufacturing apparatus; The marine plant system according to claim 4.

6. A biochar production device that produces biochar from seaweed collected from the ocean; an alginic acid production apparatus for producing alginic acid from the seaweed; A power generation device that supplies electricity generated using renewable energy to the biochar production device and the alginic acid production device, a controller for controlling the production of the biochar and the production of the alginic acid, If the amount of electricity is less than a predetermined reference value, selecting the production of biochar. A method for controlling an offshore plant system.

7. The marine plant system includes: Further provided is an intermediate raw material manufacturing device for manufacturing an intermediate raw material for manufacturing the alginic acid, The controller If the amount of the intermediate material is less than a predetermined reference value, select to produce the intermediate material; The method for controlling a marine plant system according to claim 6.

8. The marine plant system includes: a seawater treatment device that separates seawater into fresh water and concentrated seawater; An electrolysis device that electrolyzes the concentrated seawater separated by the seawater treatment device, the intermediate raw material production device produces calcium chloride and sodium bicarbonate from calcium carbonate using the fresh water separated by the seawater treatment device and the hydrogen gas, chlorine gas, and sodium hydroxide produced by the electrolysis device; The alginic acid production apparatus extracts alginic acid from the seaweed and produces calcium alginate using calcium chloride and sodium bicarbonate produced by the intermediate raw material production apparatus. The method for controlling a marine plant system according to claim 7.

9. The marine plant system includes: A storage device for storing residue generated in the alginic acid production apparatus; a boiler for burning the residue; The controller If the free space in the storage device is less than a predetermined reference value, selecting to burn the residue stored in the storage device by a boiler. The method for controlling a marine plant system according to any one of claims 6 to 8.

10. supplying calcium carbonate contained in ash generated in the boiler to the intermediate raw material manufacturing apparatus; The method for controlling a marine plant system according to claim 9.

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