Marine plant system and method for producing calcium alginate

Abstract

To provide a marine plant system capable of reducing the LCA of calcium alginate to be produced.SOLUTION: A marine plant system according to an aspect of the present disclosure comprises: 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; an intermediate raw material production device that uses the fresh water separated by the seawater treatment device and hydrogen gas, chlorine gas, and sodium hydroxide generated by the electrolysis device to produce calcium chloride and sodium hydrogen carbonate from calcium carbonate; and a calcium alginate production device that uses the calcium chloride and sodium hydrogen carbonate produced by the intermediate raw material production device to extract alginic acid from seaweed collected from the sea and produce calcium alginate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a marine plant system and a method for producing calcium alginate. [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 extracts and recovers specific nutrients and the like 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 extracts alginic acid contained in seaweed as sodium alginate and recovers it as calcium alginate. However, if hydrochloric acid (HCl) and sodium hydroxide (NaOH), which are necessary for the production of calcium alginate, are purchased and transported to the marine plant system by container ship, the LCA (Life Cycle Assessment) of the calcium alginate produced will be large.

[0005] The present disclosure has been made in consideration of the above circumstances, and provides a marine plant system that can reduce the LCA of calcium alginate produced. [Means for solving the problem]

[0006] A marine plant system according to one aspect of the present disclosure 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; an intermediate raw material production device that 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; and a calcium alginate production apparatus that uses the calcium chloride and sodium bicarbonate produced by the intermediate raw material production apparatus to extract alginic acid from seaweed collected from the sea and produce calcium alginate.

[0007] In a marine plant system according to one embodiment of the present disclosure, concentrated seawater separated by a seawater treatment device is electrolyzed by an electrolyzer to produce hydrogen gas, chlorine gas, and sodium hydroxide. This means that there is no need to purchase hydrochloric acid and sodium hydroxide, which are necessary for producing calcium alginate, and transport them to the marine plant system by container ship or the like, thereby significantly reducing the LCA of the calcium alginate produced.

[0008] The seawater treatment device may include a reverse osmosis membrane that separates seawater into fresh water and concentrated seawater. With this configuration, seawater can be separated into fresh water and concentrated seawater simply and inexpensively.

[0009] The seawater treatment device may further include a hydrogen power generation device that generates electricity using the hydrogen gas produced by the electrolysis device, and the seawater treatment device may include a pump that pumps seawater through the reverse osmosis membrane, the pump being driven by electricity generated by the hydrogen power generation device. With this configuration, the power required to produce calcium alginate can be reduced, further reducing the LCA of the produced calcium alginate. Here, the hydrogen power generation device may be a fuel cell.

[0010] The apparatus may further include a boiler for burning residue generated in the calcium alginate production system, and calcium carbonate contained in the ash generated in the boiler may be supplied to the intermediate raw material production system. This eliminates 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, further reducing the LCA of the calcium alginate produced.

[0011] A method for producing calcium alginate according to one embodiment of the present disclosure includes the steps of: Separating seawater into freshwater and concentrated seawater; Electrolyzing the separated concentrated seawater; a step of producing calcium chloride and sodium bicarbonate from calcium carbonate using the separated freshwater and hydrogen gas, chlorine gas, and sodium hydroxide produced by electrolysis of concentrated seawater; and a step of extracting alginic acid from seaweed collected from the sea using the produced calcium chloride and sodium bicarbonate and producing calcium alginate.

[0012] A method for producing calcium alginate according to one embodiment of the present disclosure involves electrolyzing separated concentrated seawater to produce hydrogen gas, chlorine gas, and sodium hydroxide. This eliminates the need to purchase hydrochloric acid and sodium hydroxide, which are necessary for producing calcium alginate, and transport them to a marine plant system by container ship or the like, thereby significantly reducing the LCA of the calcium alginate produced.

[0013] Seawater may be separated into fresh water and concentrated seawater by a reverse osmosis membrane. With this configuration, seawater can be separated into fresh water and concentrated seawater simply and inexpensively.

[0014] The electrolyzed hydrogen gas may be used to generate electricity, which may then be used to drive a pump that pumps seawater through the reverse osmosis membrane. This configuration reduces the amount of electricity required to produce calcium alginate, further reducing the LCA of the calcium alginate produced. Here, in the fuel cell, the electrolyzed hydrogen gas may be used to generate electricity.

[0015] Residues generated in the process of producing calcium alginate may be burned, and calcium carbonate contained in the ash generated by the combustion of the residues may be used in the process of producing calcium chloride and sodium bicarbonate. This eliminates the need to purchase the calcium carbonate required for calcium alginate production and transport it to a marine plant system by container ship or the like, further reducing the LCA of the calcium alginate produced. [Effects of the Invention]

[0016] The present disclosure provides a marine plant system that can reduce the LCA of the calcium alginate produced. [Brief explanation of the drawings]

[0017] [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] 1 is a flowchart showing a method for producing calcium alginate according to a first embodiment. [Figure 5] 5 is a flowchart showing an example of details of step ST4 in FIG. 4. [Figure 6] FIG. 10 is a block diagram showing the configuration of a marine plant system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] 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.

[0019] (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 FIG. 1, the marine plant system according to this embodiment includes a seawater treatment device 10, an electrolysis device 20, an intermediate raw material production device 30, and a calcium alginate production device 40.

[0020] 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.

[0021] 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 and the calcium alginate production device 40.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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).

[0028] 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.

[0029] 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.

[0030] 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.

[0031] Next, as shown in the following chemical reaction formula (3), hydrochloric acid and CaCO3 react to produce CaCl2. 2HClaq+CaCO3→H2O+CO2+CaCl2···(3)

[0032] 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)

[0033] The calcium alginate 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.

[0034] 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)

[0035] 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. The various processes performed in the calcium alginate production apparatus 40 will be described in detail later.

[0036] As described above, 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.

[0037] 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.

[0038] <Method of manufacturing calcium alginate> Next, a method for producing calcium alginate according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the method for producing calcium alginate according to the first embodiment. In describing Fig. 4, Fig. 1 will be referred to as appropriate.

[0039] First, as shown in FIG. 4, 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. 4, the separated concentrated seawater is electrolyzed in the electrolyzer 20 shown in FIG. 1 to produce H2, Cl2, and NaOH (step ST2).

[0040] Next, as shown in FIG. 4, 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).

[0041] Finally, as shown in FIG. 4, in the calcium alginate producing 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).

[0042] Next, step ST4 in Fig. 4 will be described in detail with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the details of step ST4 in Fig. 4. 5, in calcium alginate production 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.

[0043] Next, as shown in FIG. 5, in a calcium alginate 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.

[0044] 5, in calcium alginate manufacturing apparatus 40, fresh water is added to the sodium alginate extract to dilute it, separate it from the seaweed, and filter it (step ST43). Here, the fresh water added is, for example, fresh water separated by seawater treatment device 10. Dilution reduces the viscosity, making it easier to separate the sodium alginate extract from the seaweed and filter it.

[0045] Next, as shown in FIG. 5, in calcium alginate production equipment 40, CaCl2 produced by intermediate raw material production equipment 30 is added to the filtered sodium alginate extract to precipitate insoluble calcium alginate (step ST44).

[0046] Finally, as shown in FIG. 5, the calcium alginate is dehydrated and precipitated in the calcium alginate production apparatus 40, and the precipitated calcium alginate is collected (step ST45). Through the above series of processes, alginic acid is extracted from seaweed in the calcium alginate production apparatus 40, and calcium alginate is produced.

[0047] As described above, in the method for producing calcium alginate 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, since 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, the LCA of the calcium alginate produced can be significantly reduced.

[0048] (Second embodiment) Next, the configuration of the marine plant system according to the second embodiment will be described with reference to Fig. 6. Fig. 6 is a block diagram showing the configuration of the marine plant system according to the second embodiment.

[0049] As shown in FIG. 6, the marine plant system according to this embodiment includes a hydrogen power generation device 50 and a boiler 60 in addition to the seawater treatment device 10, electrolysis device 20, intermediate raw material production device 30, and calcium alginate production device 40 shown in FIG. 1.

[0050] 6, the hydrogen power generation device 50 generates electricity using H2 produced by the electrolyzer 20. The hydrogen power generation device 50 is, for example, a fuel cell. The electricity produced by the hydrogen power generation device 50 is supplied to the seawater treatment device 10.

[0051] Specifically, the electricity generated by the hydrogen power generation system 50 is supplied to the pump 12 shown in Fig. 2. That is, the pump 12 is driven by the electricity generated by the hydrogen power generation system 50. With this configuration, it is possible to reduce the electricity required to produce calcium alginate, and further reduce the LCA of the calcium alginate produced.

[0052] As shown in Figure 6, the boiler 60 is a device that burns the residue (seaweed after alginic acid extraction) generated in the calcium alginate 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. 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.

[0053] Additionally, by burning the residue in the boiler 60, the amount of waste can be reduced. Furthermore, the electricity generated by the boiler 60 may be effectively utilized in the marine plant system. This reduces the electricity required to produce calcium alginate, further reducing the LCA of the calcium alginate produced.

[0054] As described above, in the marine plant system according to this embodiment, concentrated seawater separated by the seawater treatment device 10 is also 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.

[0055] In addition, in the marine plant system according to this embodiment, the residue from the combustion in the boiler 60, that is, CaCO 3 contained in the ash, is supplied to the intermediate raw material manufacturing apparatus 30. In other words, 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.

[0056] Furthermore, in the marine plant system according to this embodiment, the electricity generated by the hydrogen power generation device 50 is supplied to the seawater treatment device 10. This reduces the electricity required to produce calcium alginate, further reducing the LCA of the calcium alginate produced.

[0057] The other configurations are the same as those in the first embodiment, and therefore the description will be omitted. The marine plant system according to this embodiment may include only one of the hydrogen power generation device 50 and the boiler 60 shown in FIG.

[0058] 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]

[0059] 10 Seawater treatment equipment 11 Reverse osmosis membrane module 12 Pump 20 Electrolyzer 30 Intermediate raw material manufacturing equipment 40 Calcium alginate manufacturing equipment 50 Hydrogen power generation equipment 60 Boiler AN anode CEM Cation Exchange Membrane CT cathode RO reverse osmosis membrane

Claims

1. 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; an intermediate raw material production device that 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; and a calcium alginate production apparatus for extracting alginic acid from seaweed collected from the sea and producing calcium alginate using the calcium chloride and sodium bicarbonate produced by the intermediate raw material production apparatus. Marine plant systems.

2. The seawater treatment device includes a reverse osmosis membrane that separates seawater into fresh water and concentrated seawater. The marine plant system according to claim 1 .

3. The electrolysis device further includes a hydrogen power generation device that generates electricity using the hydrogen gas produced by the electrolysis device. The seawater treatment device includes a pump that pumps seawater to the reverse osmosis membrane, The pump is driven by the electric power generated by the hydrogen power generation device. The marine plant system according to claim 2 .

4. The hydrogen power generation device is a fuel cell. The marine plant system according to claim 3 .

5. The apparatus further includes a boiler for burning residue generated in the calcium alginate production apparatus. supplying calcium carbonate contained in ash generated in the boiler to the intermediate raw material manufacturing apparatus; The marine plant system according to any one of claims 1 to 4.

6. Separating seawater into freshwater and concentrated seawater; Electrolyzing the separated concentrated seawater; a step of producing calcium chloride and sodium bicarbonate from calcium carbonate using the separated freshwater and hydrogen gas, chlorine gas, and sodium hydroxide produced by electrolysis of concentrated seawater; and a step of extracting alginic acid from seaweed collected from the sea using the produced calcium chloride and sodium bicarbonate and producing calcium alginate. A method for producing calcium alginate.

7. Seawater is separated into freshwater and concentrated seawater using a reverse osmosis membrane. The method for producing calcium alginate according to claim 6.

8. Generate electricity using electrolyzed hydrogen gas, The generated electricity drives a pump that pumps seawater through the reverse osmosis membrane. The method for producing calcium alginate according to claim 7.

9. In a fuel cell, electrolyzed hydrogen gas is used to generate electricity. The method for producing calcium alginate according to claim 8.

10. The residue generated in the calcium alginate manufacturing process is burned, In the step of producing calcium chloride and sodium hydrogen carbonate, calcium carbonate contained in ash generated by combustion of the residue is used. The method for producing calcium alginate according to any one of claims 6 to 9.

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