Online performance recovery method and device for electrolytic cell

Abstract

The invention discloses an online performance recovery method and device for an electrolytic bath, and the online performance recovery method comprises the steps: raising the temperature of an electrolyte to a first temperature, and introducing the electrolyte into the electrolytic bath; the electrolytic cell continuously electrolyzes for the first time at the first current density in a constant current mode, the first current density is larger than the rated current density, online performance recovery of the electrolytic cell is achieved, an original electrolytic cell system does not need to be changed, new equipment does not need to be added, the performance recovery process is simple, and the performance recovery efficiency is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of electrolytic cells, and in particular to an online performance recovery method and device for an electrolytic cell. Background Art

[0002] Proton Exchange Membrane (PEM) electrolyzer has become a hot research topic in countries around the world due to its high current density, rapid response, high purity hydrogen production, lightweight and miniaturization.

[0003] PEM electrolyzers generally use water as a reactant. Impurity ions in the water or in the pipeline accumulate in the proton exchange membrane for a long time, causing the membrane conductivity to decrease and the performance to decay due to the temporary deactivation of active sites on the catalyst surface, resulting in reduced water electrolysis efficiency and increased energy consumption. Therefore, the PEM electrolyzer needs to be shut down for recovery, and the shutdown recovery process is cumbersome, affecting the production efficiency of the equipment. Summary of the invention

[0004] The present invention provides an online performance recovery method and device for an electrolytic cell, which realizes the online performance recovery of the electrolytic cell without changing the original electrolytic cell system or adding new equipment, and the performance recovery process is simple, thereby improving the performance recovery efficiency.

[0005] In a first aspect, an embodiment of the present invention provides an online performance recovery method for an electrolytic cell, comprising:

[0006] Raising the temperature of the electrolyte to a first temperature and passing it into the electrolytic cell;

[0007] The electrolytic cell continuously electrolyzes at a first current density for a first time, wherein the first current density is greater than a rated current density.

[0008] Optionally, after the electrolytic cell continues electrolyzing at a first current density and constant current for a first time, the method further comprises:

[0009] obtaining a first electrolysis voltage at the first current density;

[0010] If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues electrolysis at the first current density for a second time, and the second time is greater than the first time.

[0011] Optionally, after the electrolytic cell continues electrolyzing at a first current density and constant current for a first time, the method further comprises:

[0012] obtaining a first electrolysis voltage at the first current density;

[0013] If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues to electrolyze at a second current density for the first time; the second current density is greater than the first current density.

[0014] Optionally, the first temperature ranges from 60-85°C.

[0015] Optionally, the resistivity of the electrolyte is greater than or equal to 10 MΩ·cm.

[0016] Optionally, the first current density is 1.5-2.5 times the rated current density.

[0017] Optionally, the first current density is 2A / cm 2 -6A / cm 2 .

[0018] Optionally, the first time is 10 min-2 h.

[0019] In a second aspect, an embodiment of the present invention provides an online performance recovery device for an electrolytic cell, comprising:

[0020] A temperature raising module, used for raising the temperature of the electrolyte to a first temperature and passing the electrolyte into the electrolytic cell;

[0021] A current control module is used to enable the electrolytic cell to continuously electrolyze at a first current density for a first time, wherein the first current density is greater than a rated current density.

[0022] Optionally, the online performance recovery device of the electrolytic cell further comprises:

[0023] An acquisition unit, used for acquiring a first electrolysis voltage under the first current density;

[0024] The current control module is also used for, if the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues electrolysis at the first current density for a second time, and the second time is greater than the first time.

[0025] The technical solution provided by the embodiment of the present invention heats the electrolyte to a first temperature, and after passing the electrolyte into the electrolytic cell, the electrolytic cell continues to electrolyze for a first time at a first current density greater than the rated current density, thereby reducing the accumulation of impurities in the proton exchange membrane, improving the membrane conductivity and the surface activity of the catalyst, and realizing online performance recovery of the electrolytic cell. There is no need to change the original electrolytic cell system or add new equipment, the performance recovery process is simple, and the performance recovery efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1A schematic flow chart of an online performance recovery method for an electrolytic cell is provided for an embodiment of the present invention;

[0027] Figure 2 A schematic flow chart of another method for online performance recovery of an electrolytic cell is provided for an embodiment of the present invention;

[0028] Figure 3 A schematic flow chart of another method for online performance recovery of an electrolytic cell is provided for an embodiment of the present invention;

[0029] Figure 4 Polarization curves of performance recovery at different current densities;

[0030] Figure 5 A structural schematic diagram of an online performance recovery device for an electrolytic cell is provided for an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Figure 1 A schematic flow chart of an online performance recovery method for an electrolytic cell is provided for an embodiment of the present invention. This embodiment is applicable to the online performance recovery of an electrolytic cell. The method can be performed by an online performance recovery device for an electrolytic cell, and the device can be implemented in hardware and / or software. The method specifically includes the following steps:

[0033] S110, raising the temperature of the electrolyte to a first temperature and passing the electrolyte into the electrolytic cell;

[0034] Specifically, the working process of the PEM electrolyzer is based on the reaction of electrolyzing water. When direct current passes through the electrolyzer, water molecules are oxidized into oxygen and hydrogen ions at the anode. The hydrogen ions migrate to the cathode through the proton exchange membrane under the action of the electric field and combine with electrons to form hydrogen. Among them, based on the process of online recovery, the electrolyte passed into the electrolyzer can use pure water as the electrolyte. Therefore, there is no need to set up an electrolyte passing device separately. The original electrolyte storage device and output device can be used. It only needs to be replaced with an electrolyte without impurities or with less impurities. Exemplarily, the resistivity of the electrolyte is greater than or equal to 10MΩ·cm. By limiting the resistivity of the electrolyte to ensure that there are fewer impurity ions in the electrolyte, new impurity ions are avoided, thereby improving the subsequent performance recovery effect. The electrolyte temperature is raised to a first temperature. By increasing the water inlet temperature of the electrolyzer, the activity of the reactants accumulated in the proton exchange membrane can be increased, making the electrolysis reaction easier to carry out. And heating the electrolyte can also increase the conductivity of the proton exchange membrane and reduce the internal resistance of the battery, thereby improving the performance and efficiency of the electrolyzer. Among them, the first temperature can be the rated temperature of the electrolyte in the electrolyzer, and the temperature can be increased by the existing equipment of the electrolyzer without setting up new hardware equipment. In some embodiments, the first temperature can also be greater than the rated temperature, so that a higher water inlet temperature can increase the conductivity of the electrolyte, thereby reducing the tank pressure, thereby reducing the power consumption required for electrolysis. Exemplarily, the range of the first temperature is 60-85°C, wherein the first temperature can be 60°C, 65°C, 70°C, 75°C, 80°C or 85°C, and the range of the first temperature is preferably 70-80°C, which can not only ensure the stress effect caused by thermal expansion and contraction inside the electrolyzer, but also optimize the reaction conditions of the electrolyzer, increase the conductivity of the proton exchange membrane, and reduce the internal resistance of the battery, thereby improving the performance and efficiency of the electrolyzer.

[0035] S120, the electrolytic cell continues electrolysis at a first current density for a first time, wherein the first current density is greater than the rated current density.

[0036] Specifically, after the electrolyte is passed into the electrolyzer, the electrolyzer begins to electrolyze at a first current density, wherein the first current density is greater than the rated current density, that is, the electrolyzer is operated at a higher current density, which helps to promote the rebalance of impurity ions and protons (H+) at the first current density, and discharges from the proton exchange membrane. Thereby reducing the accumulation of impurities in the proton exchange membrane, improving the membrane conductivity and the surface activity of the catalyst. Among them, the first time of continuous electrolysis can be determined according to the specific needs of performance recovery, if the time is too short, the impurity ions are not removed sufficiently, and if the time is too long, the service life of the electrolyzer will be affected at a high current density. Therefore, the first time range can be 10min-2h, wherein the first time can be 10min, 30min, 50min, 1h 10min, 1h 30min, 1h50min or 2h. Preferably, the first time range is 30min-1h, to ensure that the electrolyzer has a significant and efficient recovery effect.

[0037] The technical solution provided by the embodiment of the present invention heats the electrolyte to a first temperature, and after passing the electrolyte into the electrolytic cell, the electrolytic cell continues to electrolyze for a first time at a first current density greater than the rated current density, thereby reducing the accumulation of impurities in the proton exchange membrane, improving the membrane conductivity and the surface activity of the catalyst, and realizing online performance recovery of the electrolytic cell. There is no need to change the original electrolytic cell system or add new equipment, the performance recovery process is simple, and the performance recovery efficiency is improved.

[0038] Figure 2 A schematic diagram of a flow chart of another online performance recovery method for an electrolytic cell is provided for an embodiment of the present invention, see Figure 2 ,include:

[0039] S210, raising the temperature of the electrolyte to a first temperature and passing the electrolyte into the electrolytic cell;

[0040] S220, the electrolytic cell continues electrolysis at a first current density for a first time, wherein the first current density is greater than the rated current density.

[0041] S230, obtaining a first electrolysis voltage at a first current density;

[0042] Specifically, the first electrolysis voltage can be obtained by measuring, or by calculating the electrolysis voltage using a known formula or an empirical formula.

[0043] S240: If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues electrolysis at the first current density constant current for a second time, and the second time is greater than the first time.

[0044] Specifically, when the electrolytic cell has performance attenuation, the attenuated electrolysis voltage obtained under the same current density will increase compared to the initial electrolysis voltage, and the electrolysis voltage obtained after performance recovery at the first current density is less than the attenuated electrolysis voltage. The first electrolysis voltage obtained after performance recovery is equal to or greater than the initial electrolysis voltage. In order to ensure the performance recovery effect, the first electrolysis voltage obtained after performance recovery is compared with the initial electrolysis voltage. If the difference between the first electrolysis voltage and the initial electrolysis voltage falls within a preset voltage range, it can be considered that the recovery requirement is met under the first current density.

[0045] If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, it is considered that the recovery requirement is not met under the first current density. Then the electrolysis time can be increased from the first time to the second time, that is, by increasing the electrolysis time, the electrolysis replacement of the reactants accumulated in the proton exchange membrane is made more sufficient, and the recovery effect is improved. Wherein, the second time range can be 10min-2h, wherein, the second time can be 10min, 30min, 50min, 1h 10min, 1h30min, 1h50min or 2h. Preferably, the second time range is 30min-1h.

[0046] Figure 3 A schematic diagram of a flow chart of another online performance recovery method for an electrolytic cell is provided for an embodiment of the present invention, see Figure 3 ,include:

[0047] S310, raising the temperature of the electrolyte to a first temperature and passing the electrolyte into the electrolytic cell;

[0048] S320, the electrolytic cell continues electrolysis at a first current density for a first time, wherein the first current density is greater than the rated current density.

[0049] S330, obtaining a first electrolysis voltage at a first current density;

[0050] S340: If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues to electrolyze at a second current density for a first time; the second current density is greater than the first current density.

[0051] Specifically, when the electrolytic cell has performance attenuation, the attenuated electrolysis voltage obtained under the same current density will increase compared to the initial electrolysis voltage, and the electrolysis voltage obtained after performance recovery at the first current density is less than the attenuated electrolysis voltage. The first electrolysis voltage obtained after performance recovery is equal to or greater than the initial electrolysis voltage. In order to ensure the performance recovery effect, the first electrolysis voltage obtained after performance recovery is compared with the initial electrolysis voltage. If the difference between the first electrolysis voltage and the initial electrolysis voltage falls within a preset voltage range, it can be considered that the recovery requirement is met under the first current density.

[0052] If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, it is considered that the recovery requirement is not met under the first current density, and the electrolysis effect can be improved by increasing the current density, that is, increasing the first current density to the second current density, and operating the electrolyzer at a higher current density, which helps promote the rebalance of impurity ions and protons (H+) at the first current density, and discharges them from the proton exchange membrane. Thereby reducing the accumulation of impurities in the proton exchange membrane, improving the membrane conductivity and the surface activity of the catalyst.

[0053] Based on the above embodiment, optionally, the first current density is 1.5-2.5 times the rated current density. Specifically, under the premise of ensuring the safe operation of the electrolyzer, the electrolysis rate can be increased by increasing the current density, and at high current density, the electrochemical reaction of impurities in the proton exchange membrane is promoted, which helps to promote the rebalance of impurity ions and protons (H+) and the discharge of impurity ions from the proton exchange membrane. Therefore, by limiting the first current density to 1.5-2.5 times the rated current density, it is ensured that the electrolyzer operates at a higher current density and improves the performance recovery efficiency. However, excessively high current density may lead to increased polarization and corrosion of the electrode, affecting the life and performance of the electrolyzer. Therefore, it is necessary to flexibly adjust the current density according to the actual situation of the electrolyzer and the electrolysis requirements. Exemplarily, the range of the first current density is 2A / cm 2 -6A / cm 2 , the first current density can be 2A / cm 2 、3A / cm 2 , 4A / cm 2 , 5A / cm 2 or 6A / cm 2 Further, the first current density may preferably be 3A / cm 2 -5A / cm 2 .

[0054] The embodiment of the present invention provides an exemplary online energy recovery process, wherein ultrapure water with a resistivity of 18.2MΩ·cm is heated from room temperature (25°C) to 80°C and passed into an electrolytic cell. The electrolytic cell has been running continuously for a period of time to reflect the reversible attenuation caused by long-term operation. Constant current electrolysis is performed for 40 minutes at the first high current density. Figure 4 For the polarization curves of performance recovery at different current densities, see Figure 4 , respectively showing the initial polarization curve of the electrolyzer, the polarization curve after 2000h of operation, and the polarization curve after online performance recovery. As can be seen from the figure, when the electrolyzer runs for 2000h, at the same current density, the voltage has increased significantly compared with the initial polarization curve. 2 The current density increased by 27mV at 3A / cm2 The current density increased by 47mV, and after online recovery, compared with the initial polarization curve at 2A / cm 2 The voltage increased by only 6mV at a current density of 3A / cm 2 The current density increased by 21mV. Through the online recovery process, the electrolysis voltage after performance recovery was significantly reduced.

[0055] Figure 5 The present invention provides a schematic diagram of the structure of an online performance recovery device for an electrolytic cell, see Figure 5 ,include:

[0056] A temperature increasing module 110 is used to increase the temperature of the electrolyte to a first temperature and pass it into the electrolytic cell;

[0057] The current control module 120 is used to make the electrolytic cell continue to electrolyze at a first current density for a first time, wherein the first current density is greater than the rated current density.

[0058] Specifically, the working process of the PEM electrolyzer is based on the reaction of electrolyzing water. When direct current passes through the electrolyzer, water molecules are oxidized into oxygen and hydrogen ions at the anode. The hydrogen ions migrate to the cathode through the proton exchange membrane under the action of the electric field and combine with electrons to form hydrogen. Among them, based on the process of online recovery, the electrolyte passed into the electrolyzer can use pure water as the electrolyte. Therefore, there is no need to set up an electrolyte passing device separately. The original electrolyte storage device and output device can be used. It only needs to be replaced with an electrolyte without impurities or with less impurities. Exemplarily, the resistivity of the electrolyte is greater than or equal to 10MΩ·cm. By limiting the resistivity of the electrolyte to ensure that there are fewer impurity ions in the electrolyte, new impurity ions are avoided, thereby improving the subsequent performance recovery effect. The heating module 110 raises the temperature of the electrolyte to a first temperature. By increasing the water inlet temperature of the electrolyzer, the activity of the reactants accumulated in the proton exchange membrane can be increased, making the electrolysis reaction easier to carry out. And heating the electrolyte can also increase the conductivity of the proton exchange membrane and reduce the internal resistance of the battery, thereby improving the performance and efficiency of the electrolyzer. Among them, the first temperature can be the rated temperature of the electrolyte in the electrolyzer, and the temperature can be increased by the existing equipment of the electrolyzer without setting up new hardware equipment. In some embodiments, the first temperature can also be greater than the rated temperature, so that a higher water inlet temperature can increase the conductivity of the electrolyte, thereby reducing the tank pressure, thereby reducing the power consumption required for electrolysis. Exemplarily, the first temperature ranges from 60-85°C, preferably 70-80°C, which can not only ensure the stress effect caused by thermal expansion and contraction inside the electrolyzer, but also optimize the reaction conditions of the electrolyzer, increase the conductivity of the proton exchange membrane, and reduce the internal resistance of the battery, thereby improving the performance and efficiency of the electrolyzer.

[0059] After the electrolyte is passed into the electrolyzer, the current control module 120 controls the electrolyzer to start electrolysis at a first current density, wherein the first current density is greater than the rated current density, that is, the electrolyzer is operated at a higher current density, which helps to promote the rebalance of impurity ions and protons (H+) at the first current density, and discharges them from the proton exchange membrane. Thereby reducing the accumulation of impurities in the proton exchange membrane, improving the membrane conductivity and the surface activity of the catalyst. Among them, the first time of continuous electrolysis can be determined according to the specific needs of performance recovery. If the time is too short, the impurity ions are not fully removed. If the time is too long, the operation at a high current density will affect the service life of the electrolyzer. Therefore, the first time range can be 10min-2h, preferably, the first time range is 30min-1h, to ensure that the electrolyzer has a significant and efficient recovery effect.

[0060] Optionally, the online performance recovery device also includes:

[0061] An acquisition unit, used for acquiring a first electrolysis voltage under a first current density;

[0062] The current control module is also used for, if the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues to electrolyze at the first current density constant current for a second time, and the second time is greater than the first time.

[0063] Specifically, when the electrolytic cell has performance attenuation, the attenuated electrolysis voltage obtained under the same current density will increase compared to the initial electrolysis voltage, and the electrolysis voltage obtained after performance recovery at the first current density is less than the attenuated electrolysis voltage. The first electrolysis voltage obtained after performance recovery is equal to or greater than the initial electrolysis voltage. In order to ensure the performance recovery effect, the first electrolysis voltage obtained after performance recovery is compared with the initial electrolysis voltage. If the difference between the first electrolysis voltage and the initial electrolysis voltage falls within a preset voltage range, it can be considered that the recovery requirement is met under the first current density.

[0064] If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, it is considered that the recovery requirement is not met under the first current density. The electrolysis time can be increased from the first time to the second time, that is, by increasing the electrolysis time, the electrolysis replacement of the reactants accumulated in the proton exchange membrane is more sufficient, thereby improving the recovery effect. The second time range can be 10 min-2 h, preferably, the second time range is 30 min-1 h.

[0065] Alternatively, the electrolysis effect can be improved by increasing the current density, that is, increasing the first current density to the second current density, and operating the electrolyzer at a higher current density, which helps promote the rebalance of impurity ions and protons (H+) at the first current density and discharges them from the proton exchange membrane, thereby reducing the accumulation of impurities in the proton exchange membrane and improving the membrane conductivity and the surface activity of the catalyst.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering the online performance of an electrolytic cell, characterized in that: include: Raising the temperature of the electrolyte to a first temperature and passing it into the electrolytic cell; The electrolytic cell continuously electrolyzes at a first current density for a first time, wherein the first current density is greater than a rated current density.

2. The online performance recovery method of the electrolytic cell according to claim 1, characterized in that: After the electrolytic cell continues electrolyzing at a first current density constant current for a first time, the method further comprises: obtaining a first electrolysis voltage at the first current density; If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues to electrolyze at the first current density for a second time, and the second time is greater than the first time.

3. The online performance recovery method of the electrolytic cell according to claim 1, characterized in that: After the electrolytic cell continues electrolyzing at a first current density constant current for a first time, the method further comprises: obtaining a first electrolysis voltage at the first current density; If the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within the preset voltage range, the electrolytic cell continues to electrolyze at a second current density constant current for the first time; the second current density is greater than the first current density.

4. The method for online performance recovery of an electrolytic cell according to any one of claims 1 to 3, characterized in that: The first temperature ranges from 60-85°C.

5. The method for online performance recovery of an electrolytic cell according to claim 4, characterized in that: The resistivity of the electrolyte is greater than or equal to 10 MΩ·cm.

6. The method for online performance recovery of an electrolytic cell according to claim 5, characterized in that: The first current density is 1.5-2.5 times the rated current density.

7. The method for online performance recovery of an electrolytic cell according to claim 5, characterized in that: The first current density is 2A / cm 2 -6A / cm 2 .

8. The method for online performance recovery of an electrolytic cell according to claim 7, characterized in that: The first time is 10min-2h.

9. An online performance recovery device for an electrolytic cell, characterized in that: include: A temperature raising module, used for raising the temperature of the electrolyte to a first temperature and passing the electrolyte into the electrolytic cell; A current control module is used to enable the electrolytic cell to continuously electrolyze at a first current density for a first time, wherein the first current density is greater than a rated current density.

10. The online performance recovery device of the electrolytic cell according to claim 9, characterized in that: Also includes: An acquisition unit, used for acquiring a first electrolysis voltage under the first current density; The current control module is also used for, if the difference between the first electrolysis voltage and the initial electrolysis voltage does not fall within a preset voltage range, the electrolytic cell continues electrolysis at the first current density for a second time, and the second time is greater than the first time.

Images