Apparatus and method for acidizing brine

Abstract

A method for acidifying brine, comprising the steps of: - supplying brine into a central chamber (2) of an acidification device (1), said central chamber (2) being separated from an anodic chamber (3) of the acidification device (1) by a first cation-selective membrane (11) and from a cathodic chamber (4) of the acidification device (1) by a second cation-selective membrane (12), - performing electrolysis, wherein: i) H + ions and O2 are generated at an anode (9) of the anodic chamber (3); ii) H + ions migrate from the anodic chamber (3) into the central chamber (2), thereby generating an acidified brine in the central chamber (2); iii) Na + ions migrate from the central chamber (2) into the cathodic chamber (4); iv) OH ‑ ions and N2 are generated at a cathode (10) of the cathodic chamber (4), - removing NaOH from the cathodic chamber, - collecting at least a part of the acidified brine from the central chamber (2). The invention also relates to an acidification device.

Description

Technical Field

[0001] This invention relates to an apparatus and method for acidifying brine. Background Technology

[0002] For example, energy supplied by renewable power sources can be stored by electrolyzing water to produce hydrogen. This is particularly advantageous for offshore wind power equipment surrounded by water. However, this water is seawater, which must be purified, especially desalinated, before it can be electrolyzed. The presence of carbonates and bicarbonates is a limiting parameter determining the efficiency of the desalination process.

[0003] US 9,108,844 BB discloses a method and system for producing hydrogen chloride or an aqueous solution of hydrogen chloride using untreated brine. The system includes an electrodialysis cell having an anion-selective membrane, a cation-selective membrane, a cathode, and an anode. Due to the negative polarity of the cathode, Cl... - Ions are released from the cathode chamber. The disadvantages of this system are the high sensitivity of the anion-selective membrane to oxidants and the high pH value caused by the cathode reaction. H+ is released at the anode. + Ions migrate through the cation-selective membrane to the cathode. In the product space between the cation-selective and anion-selective membranes, these two ionic substances combine to form the desired product, hydrogen chloride (HCl). The product is then pumped to a consumer, such as in a seawater desalination unit. Summary of the Invention

[0004] The objective of this invention is to provide an apparatus and method for acidifying brine that do not suffer from the disadvantages of the prior art.

[0005] This invention relates to a method for acidifying brine according to claim 1, and an acidification apparatus according to claim 6. Advantageous embodiments of the invention are the subject of the dependent claims and the description.

[0006] This invention provides a method for acidifying brine, the method comprising the following steps: - Brine is supplied to the central chamber of the acidification device, wherein the central chamber is separated from the anode chamber of the acidification device by a first cation-selective membrane and from the cathode chamber by a second cation-selective membrane.

[0007] - Perform electrolysis, where: i. Generate H at the anode of the anode chamber + Ions and O2; ii. The H mentioned + Ions migrate from the anode chamber through the first cation-selective membrane into the central chamber, thereby generating acidic brine in the central chamber; iii. Na + Ions migrate from the brine in the central chamber to the cathode chamber; iv. OH is generated at the cathode of the cathode chamber. - Ions and H2.

[0008] - Remove NaOH from the cathode chamber.

[0009] - Collect at least a portion of the acidified brine from the central chamber.

[0010] Preferably, the brine is pumped through the central chamber of the acidification unit, thereby discharging brine with a pH value between 2 and 4.5. The brine can be fed into the central chamber from a brine reservoir. The brine can be, for example, seawater—especially having a salt content of up to 4% by mass. The brine particularly contains NaCl. The discharged acidified brine can be fed into a desalination unit.

[0011] The following reaction occurs in the anode chamber of the acidification unit: 2 H2O → 4H + + O2 + 4e - According to this reaction, protons H are released at the anode in the anode chamber. + And oxygen (O2). Proton (H) + Attracted by the negative charge of the cathode in the cathode chamber, it then migrates through the first cation-selective membrane to the central chamber, causing the brine flowing through the central chamber to be acidified. Simultaneously, Na... + Ions from the brine in the central chamber are attracted by the negative charge of the cathode in the cathode chamber, and thus migrate through the second cation-selective membrane to the cathode chamber of the acidification device.

[0012] The following reaction occurs in the cathode chamber: 2 H2O + 2e - → 2 OH - + H2 According to this reaction, H2 is released at the cathode in the cathode chamber. Furthermore, due to OH... - An increase in ion concentration leads to a rise in pH within the cathode chamber. To prevent OH groups from entering the cathode chamber... - To prevent excessive concentration of ions and the deposition of impurities on the cathode, the cathode chamber can be flushed with a portion of the brine from the brine reservoir.

[0013] In this way, brine—and especially seawater—can be acidified without the need for a separate acid tank that must be refilled and / or transported to where it is needed. The brine is acidified “in the flow,” eliminating the need for space-consuming equipment. This is particularly advantageous for use in water purification systems located in hard-to-reach places, such as in marine applications.

[0014] According to one embodiment of the invention, during cycling, a carrier compound, particularly a carrier electrolyte, is added to and removed from the anode chamber. The carrier electrolyte can improve conductivity and thus support the process. The electrolysis reaction itself depends on temperature and environment, but not on the conductivity of the aqueous solution.

[0015] According to one embodiment of the invention, the carrier electrolyte is an alkali metal salt of sulfuric acid (H₂SO₄), phosphoric acid, nitric acid, or a non-oxidizable acid, preferably sodium sulfate, sodium nitrate, or sodium phosphate, or mixtures thereof. When sulfuric acid is used as the carrier electrolyte, it is preferably used as 1% to 10% sulfuric acid. If a salt such as sodium sulfate is used as a catalyst, this salt can be converted into its corresponding acid after a short electrolysis time.

[0016] According to one embodiment of the present invention, acidified brine is supplied to the desalination unit.

[0017] The acidified brine is preferably supplied to the desalination unit in a continuous process, such that at least some of the products of the reaction occurring in the acidification unit (especially the acidified brine) are continuously discharged from the central chamber, and some of the reactants for the reaction occurring in the acidification unit are continuously supplied to the central chamber so that the reaction does not stop.

[0018] The present invention also provides an acidification apparatus for acidifying brine, comprising: - A central chamber, defined by a first cation-selective membrane and a second cation-selective membrane. - An anode chamber, comprising an anode and separated from the central chamber by the first cation-selective membrane. - A cathode chamber, which includes a cathode and is separated from the central chamber by the second cation-selective membrane.

[0019] Salt water can contain sodium. + Cl - SO4 ions and other ions, such as other alkali metal or alkaline earth metal ions, are present. The anode and cathode are connected to a direct current (DC) power supply, which provides DC current to the cathode and anode, allowing the cathode to be negatively charged and the anode to be positively charged. This forces a stable flow of cations to the cathode within the acidification device. Furthermore, Na+ is present in each chamber... + and H + The high difference in H concentrations led to + The first cation-selective membrane is permeated, and Na +A second cation-selective membrane is permeated. Both the first and second cation-selective membranes are selectively permeable to cations. Preferably, the first cation-selective membrane is selectively permeable to protons, and the second cation-selective membrane is selectively permeable to Na+. + Ions can selectively penetrate.

[0020] According to an extended embodiment of the invention, the acidification apparatus includes a brine reservoir. A pump can be provided to pump brine from the brine reservoir into a central chamber. The central chamber can be designed such that brine from the brine reservoir flows through it. An anode chamber and a cathode chamber can be filled with aqueous solutions. A cathode can be arranged in the cathode chamber. Alternatively, the cathode chamber can be cathode-bounded, such that the cathode chamber is bounded by a cathode and a first cation-selective membrane, wherein the cathode and the second cation-selective membrane are opposite each other. An anode can be arranged in the anode chamber. Alternatively, the anode chamber can be anode-bounded, such that the anode chamber is bounded by an anode and by a first cation-selective membrane, wherein the anode and the second cation-selective membrane are opposite each other. The anode can be designed to generate protons and O2 in the anode chamber when it is positively charged. The cathode can be designed to generate OH- in the cathode chamber when it is negatively charged. - Ions and H2. Protons generated in the anode chamber can be attracted by the negative charge of the cathode. The acidification device is designed such that protons from the anode chamber can migrate through a first cation-selective membrane to the central chamber, thereby generating acidified brine. The central chamber can be connected to a desalination unit. A pump can be provided to pump the acidified brine from the central chamber to the desalination unit, where it can be further processed. Due to the second cation-selective membrane's effect on Na+, the acidification process is more efficient. + Ions can selectively permeate, including Na+ from the brine in the central chamber. + Ions migrate through a second cation-selective membrane into the cathode chamber, where they are attracted by the negative charge of the cathode. Acidification devices with these features provide a compact and cost-effective system for acidifying brine, especially seawater.

[0021] In one embodiment of the invention, the acidification apparatus includes a brine reservoir. Preferably, the brine reservoir is connected to both the central chamber and the cathode chamber—particularly via piping—so that the cathode chamber can be flushed with brine from the brine reservoir. A pump can be provided to pump brine from the brine reservoir into the cathode chamber. This helps prevent impurities from precipitating on the cathode, which would otherwise lead to cathode failure. Furthermore, this avoids over-concentration, especially of OH. - and Na + Excessive concentration of ions can lead to process stagnation in the acidification unit. An increase in pH value is detrimental to Ca... 2+ and Mg 2+ The precipitation of ions is decisive. In the presence of a pure NaCl aqueous solution, Na...+ The precipitation of ions occurs at a mass fraction of approximately 5% NaOH (pH 13). However, for Ca... 2+ and Mg 2+ The precipitation of ions is considered to be determined by a pH value of approximately 10.

[0022] In one embodiment of the invention, the acidification apparatus includes an alkaline waste container that can be connected to the cathode chamber—particularly via piping. The alkaline waste container is preferably designed to contain and store the alkaline waste, particularly NaOH, generated within the cathode chamber. A pump can be provided to pump NaOH from the cathode chamber into the alkaline waste container. This prevents a sharp rise in pH within the cathode chamber, which could also cause process stall.

[0023] In one embodiment of the invention, the acidification apparatus includes a carrier electrolyte reservoir that can be connected to the anode chamber, allowing the carrier electrolyte to be added to and removed from the anode chamber. Preferably, the carrier electrolyte is sulfuric acid, particularly 1% to 10% sulfuric acid (H₂SO₄). The carrier electrolyte can increase conductivity and thus increase process speed.

[0024] Other advantages and embodiments of the present invention are shown in the specification and drawings.

[0025] The present invention is illustrated schematically with reference to the accompanying drawings, and is described below with reference to the drawings. Attached Figure Description

[0026] Figure 1 An acidification apparatus according to one embodiment of the present invention is disclosed. Detailed Implementation

[0027] The figure discloses an acidification apparatus 1, which includes an anode chamber 3, a central chamber 2, and a cathode chamber 4. The anode chamber is bounded by an anode 9 and a first cation-selective membrane 11, wherein the anode 9 and the first cation-selective membrane 11 are opposite each other. The cathode chamber 4 is bounded by a cathode 10 and a second cation-selective membrane 12, wherein the cathode 10 and the second cation-selective membrane 12 are opposite each other. The cathode 10 and the anode 9 are connected to a direct current power supply (not shown), such that the cathode 10 can be negatively charged and the anode 9 can be positively charged. The anode chamber 3 may be filled with an aqueous solution, which reacts at the positively charged anode 9 to generate O2 and protons. The cathode chamber 4 may be filled with an aqueous solution, which reacts at the negatively charged cathode 10 to generate H2 and OH-. -Ions. The central chamber 2 is connected to the brine reservoir 6 via the inlet line 13 and to the desalination unit 8 via the outlet line 14. Brine, especially seawater, can be pumped from the brine reservoir 6 into the central chamber 2 via a pump (not shown). Attracted by the negative charge of the cathode 10, protons migrate through the first cation-selective membrane 11 into the central chamber, where the brine in the central chamber 2 is acidified. The acidic brine is discharged into the desalination unit 8 via the outlet line 14.

[0028] The brine reservoir 6 is connected to the cathode chamber 4 via a flushing line 15 including a valve, allowing the cathode chamber 4 to be flushed with brine from the brine reservoir 6 to prevent impurities from precipitating on the cathode 10. The cathode chamber 4 is connected to the alkaline waste container 7 via a pipe, allowing the NaOH generated in the cathode chamber 4 to be discharged from the cathode chamber 4.

[0029] The anode chamber 3 can be connected to the carrier electrolyte reservoir 5 through two pipelines. One pipeline is used to supply the carrier electrolyte (H2SO4 in this case) into the anode chamber 3, and the other pipeline is used to discharge the carrier electrolyte from the anode chamber 3.

Claims

1. A method for acidifying brine, comprising the following steps: - The brine is supplied to the central chamber (2) of the acidification device (1), wherein the central chamber (2) is separated from the anode chamber (3) of the acidification device (1) by a first cation-selective membrane (11) and from the cathode chamber (4) of the acidification device (1) by a second cation-selective membrane (12). - Perform electrolysis, where: i. H is generated at the anode (9) of the anode chamber (3). + ion, ii. H + Ions migrate from the anode chamber (3) to the central chamber (2), thereby generating acidic brine in the central chamber (2). iii. Na + Ions migrate from the central chamber (2) to the cathode chamber (4). iv. OH is generated at the cathode (10) of the cathode chamber (4). - Ions and H2, - Remove NaOH from the cathode chamber - Collect at least a portion of the acidic brine from the central chamber (2).

2. The method for acidifying brine according to claim 1, wherein, During the cycle, the carrier compound is added to the anode chamber (3) and removed from the anode chamber.

3. The method for acidifying brine according to claim 2, wherein, The carrier compound contains sulfuric acid.

4. The method for acidifying brine according to any one of the preceding claims, wherein, The acidic brine is supplied to the desalination unit (8).

5. The method for acidifying brine according to any one of the preceding claims, wherein, The cathode chamber (4) is flushed with brine from the brine reservoir (6).

6. An acidification apparatus (1) for acidifying brine, comprising: - Central chamber (2), which is bounded by a first cation-selective membrane (11) and a second cation-selective membrane (12), - Anode chamber (3), which includes an anode (9) and is separated from the central chamber (2) by the first cation-selective membrane (11), - Cathode chamber (4), which includes a cathode (10) and is separated from the central chamber (2) by the second cation-selective membrane (12).

7. The acidification apparatus (1) according to claim 6, comprising a brine reservoir (6), wherein, The brine reservoir (6) is connected to the central chamber (2) and preferably to the cathode chamber (4) so ​​that the cathode chamber (4) can be flushed with brine from the brine reservoir (6).

8. The acidification apparatus (1) according to any one of claims 7 or 6, comprising a reservoir (5) for a carrier compound, wherein, The carrier compound is preferably sulfuric acid, and the reservoir of the carrier compound is connected to the anode chamber (3) so that the carrier compound can be added to the anode chamber (3) and removed from the anode chamber.

9. The acidification apparatus (1) according to any one of claims 6 to 8, having an alkaline waste liquid container (7) connected to the cathode chamber (4).

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