JP4841148B2 - Method of measuring deterioration of electrode of seawater electrolyzer and method of calculating limit of use of electrode of seawater electrolyzer - Google Patents

Description

The present invention relates to the use limit calculating how the electrodes of the deterioration degree measurement method及beauty sea water electrolysis device electrodes of seawater by electrolysis seawater electrolysis apparatus to produce sodium hypochlorite.

  At power plants, seawater is used in condensers that cool steam. If the taken seawater is used as it is, microorganisms and the like adhere to the pipe, so sodium hypochlorite is injected into the seawater for the purpose of preventing them. Sodium hypochlorite injected into seawater can also be obtained by electrolyzing seawater. When seawater is electrolyzed, chlorine is produced at the anode and sodium hydroxide is produced at the cathode, which react to produce sodium hypochlorite. This power plant also obtains sodium hypochlorite by electrolyzing seawater.

  When a seawater electrolyzer that electrolyzes seawater is operated for a long period of time, scale adheres to the cathode. The scale is a hydroxide produced by reaction of calcium and magnesium contained in seawater with hydroxide ions generated on the cathode side during seawater decomposition. Since adhesion of the scale leads to degradation of the performance of the electrolyzer, the scale is removed by washing with an acid once a year.

  FIG. 7 is a diagram showing a schematic flow of the seawater electrolysis system used in this power plant. Seawater is pumped up by the seawater electrolysis pump 1, solids are removed by the filter 2, and then the seawater is fed to the electrolyte solution receiving tank 3. The electrolyte solution receiving tank 3 is provided with a recycle pump 4, and the recycle pump 4 quantitatively feeds the solution in the electrolyte solution receiving tank 3 to the seawater electrolyzer 5. The seawater electrolyzer 5 includes a seawater electrolyzer main body 6 having an electrode therein and a power supply device 7 for supplying power to the electrode, where the seawater is electrolyzed and sodium hypochlorite is generated. .

  Seawater electrolyzed by the seawater electrolyzer 5 and containing sodium hypochlorite is returned to the electrolyte receiver 3 again. As described above, the seawater electrolysis system electrolyzes seawater while circulating seawater containing sodium hypochlorite between the electrolyte solution receiving tank 3 and the seawater electrolysis apparatus 5. Part of the seawater containing sodium hypochlorite is taken out and sent to the waterway. In addition, a cleaning liquid supply pipe and an industrial water supply pipe are disposed in the lower pipe of the seawater electrolysis tank body 6, and the cleaning liquid and the industrial water are supplied through these.

  As the anode electrode of the seawater electrolysis apparatus, durability is ensured by using a base material having corrosion resistance such as titanium coated with platinum or the like. However, when a seawater electrolysis apparatus is used for a long time while repeating washing with an acid, the amount of chlorine generated may decrease, or the coating coated on the surface of the substrate may be peeled off or consumed. It is also pointed out that this is mainly due to the anode material forming a cathode and a battery during cleaning with an acid, and the anode material being exposed to a base potential environment (see, for example, Patent Document 1).

When the coating coated on the surface of the base material is peeled off or consumed, the base material itself is damaged. Therefore, the seawater electrolyzer body is periodically disassembled, and inspection of the electrode such as peeling of the coating is performed. When peeling of a film of a predetermined amount or more is recognized, the film is used again by coating the surface of the substrate.
JP-A-8-170187

  As described above, the management of the electrodes of the seawater electrolysis apparatus, especially the management of the anode, is to periodically disassemble the seawater electrolysis apparatus, visually observe the electrodes, and confirm the peeling state of the coating coated on the substrate surface It is not possible to clearly grasp the degree of deterioration. Further, since visual observation cannot quantitatively grasp the degree of electrode deterioration (film peeling), it is impossible to predict the time when the film is again coated on the substrate surface, that is, the current use limit of the electrode. Further, a technique for quantitatively measuring the peeling of the electrode coating of the seawater electrolysis apparatus and managing the electrode is not disclosed in prior art documents.

An object of the present invention is to provide a use limit calculating how the deterioration degree measurement method and electrodes of the electrode of the calculated quantitatively capable seawater electrolysis device deterioration of the electrode in a simple manner.

The present invention measures the degree of deterioration of an electrode of a seawater electrolysis apparatus comprising an electrolytic cell provided with an electrode for electrolyzing seawater and a power supply means for applying a voltage to the electrode of the electrolytic cell and capable of changing an output voltage. a method, during the operation of the seawater electrolysis device, through said power supply means to apply a plurality of different voltages to the electrodes, and measuring a current value flowing through the electrode at that time, the voltage-current characteristic data of the electrode An electrode deterioration degree measuring method for a seawater electrolysis apparatus characterized in that the deterioration degree of an electrode is measured from the obtained voltage / current characteristic data of the electrode and predetermined voltage / current characteristic data of the electrode.

Further, the present invention calculates the limit of use of an electrode of a seawater electrolysis apparatus comprising an electrolytic cell comprising an electrode for electrolyzing seawater and a power supply means for applying a voltage to the electrode of the electrolytic cell and capable of changing an output voltage. A plurality of different voltages are applied to the electrodes via the power supply means during the operation of the seawater electrolysis apparatus at predetermined intervals, and the current values flowing through the electrodes at that time are measured, An electrode usage limit calculation method for a seawater electrolysis apparatus, characterized in that voltage / current characteristic data of an electrode is obtained and an electrode usage limit is calculated from a change with time of the voltage / current characteristic data of the electrode.

The method for measuring the degree of deterioration of an electrode of a seawater electrolysis apparatus according to the present invention applies a plurality of different voltages to the electrode during operation of the seawater electrolysis apparatus, measures the current value flowing through the electrode at that time, and measures voltage-current characteristic data of the electrode And the degree of deterioration of the electrode is measured from the voltage-current characteristic data of the electrode and the predetermined voltage-current characteristic data of the electrode, so that the degree of deterioration of the electrode of the seawater electrolysis apparatus can be measured easily and quantitatively. . In particular, since the voltage / current characteristic data of the electrode can be acquired without stopping the operation of the seawater electrolysis apparatus, the voltage / current characteristic data can be appropriately acquired. For this reason, when there is a concern about the deterioration of the electrode, the deterioration of the electrode can be accurately grasped by acquiring the voltage-current characteristic data at short intervals. Furthermore, since it is not necessary to stop the seawater electrolysis apparatus when acquiring the voltage-current characteristic data of the electrodes, it is preferable without affecting the operation of the power plant or the like. Moreover, since the power supply means for applying a voltage to the electrodes is used for acquiring the voltage-current characteristic data, a special device is not necessary and it is convenient.

In the seawater electrolysis apparatus electrode usage limit calculation method of the present invention , a plurality of different voltages are applied to the electrode during the operation of the seawater electrolysis apparatus at predetermined intervals , and the current value flowing through the electrode at that time is measured. Since the electrode current limit data is obtained and the electrode use limit is calculated from the change over time of the electrode voltage current characteristic data, the electrode use limit of the seawater electrolyzer can be calculated quantitatively and easily. In particular, since the voltage / current characteristic data of the electrode can be acquired without stopping the operation of the seawater electrolysis apparatus, the voltage / current characteristic data can be appropriately acquired. For this reason, when the use limit of the electrode is approaching, the use limit of the electrode can be accurately grasped by acquiring the voltage-current characteristic data at short intervals. Furthermore, since it is not necessary to stop the seawater electrolysis apparatus when acquiring the voltage-current characteristic data of the electrodes, it is preferable without affecting the operation of the power plant or the like. Moreover, since the power supply means for applying a voltage to the electrodes is used for acquiring the voltage-current characteristic data, a special device is not necessary and it is convenient.

  FIG. 1 is a diagram showing a schematic configuration of a seawater electrolysis apparatus 10 as an embodiment of the present invention. A seawater electrolysis apparatus 10 shown in FIG. 1 is a part of a seawater electrolysis system, and an actual seawater electrolysis system includes a plurality of seawater electrolysis apparatuses. The seawater electrolysis apparatus 10 includes a plurality of electrolytic cells 20a, 20b, 20c, 20d, 20e, and 20f that electrolyze seawater, a power supply device 60 that supplies power to the electrolytic cell 20, and a data processing device 70. Here, the electrolytic cells 20a, 20b, 20c, 20d, 20e, and 20f have the same shape and structure.

  FIG. 2 is an exploded view of one electrolytic cell 20a constituting the seawater electrolysis apparatus 10 of FIG. 3 is an assembly diagram of one electrolytic cell 20a constituting the seawater electrolysis apparatus 10 of FIG. The electrolytic cell 20a has pipe connection parts at the top and bottom, an electrolytic cell main body 21 having a space part capable of receiving electrodes therein, and electrodes 22 and 23 for electrolyzing seawater upon receiving power supply from a power supply device 60. In addition, it includes packings 24 and 25 that serve to prevent leakage of seawater when the electrodes 22 and 23 are assembled to the electrolytic cell main body 21, and copper strips 26 and 27 that supply electricity to the electrodes 22 and 23. Further, the packings 24 and 25 ensure electrical insulation between the electrodes 22 and 23. Of the electrodes 22 and 23, the electrode 22 is an anode and the electrode 23 is a cathode.

  The anode 22 includes a vertically long flat plate 30 and six vertically long flat plates 31 (31a, 31b, 31c, 31d, 31e, and 31f), and the six flat plates 31 are substantially perpendicular to the flat plate 30 in plan view. It is fixed at regular intervals. The flat plate 30 and the flat plate 31 use titanium as a base material, and a base metal surface is coated with a noble metal. The cathode 23 includes a vertically long flat plate 32, seven vertically long flat plates 33 (33a, 33b, 33c, 33d, 33e, 33f, 33g) and a flat plate 34 having an opening at the center. In plan view, one side of the seven flat plates 33 (33a to 33g) is fixed at a regular interval substantially perpendicular to the flat plate 32, and the other sides of the flat plate 33a and the flat plate 33g are fixed to the flat plate 34. The cathode is stainless steel.

  When the electrolytic cell is assembled, each of the six flat plates 31 (31a to 31f) of the anode is inserted between each of the seven flat plates 33 (33a to 33g) of the cathode. A cathode 23 is inserted into the electrolytic cell body 21 via a packing 24, and an anode 22 is inserted into the electrolytic cell body 21 via a packing 25, and an anode copper strip 26 for supplying electricity to the flat plate 30 of the anode 22 is applied. The electrolytic cell 20 can be assembled by contacting the electrolytic cell 21 main body, the packing 24, the cathode 23, the packing 25, the anode 22 and the anode copper strip 26 together with a bolt. A cathode copper strip 27 for supplying electricity to the cathode 23 is fixed to the flat plate 34 of the cathode 23 with a bolt.

  In the electrolyzer 20 of the seawater electrolyzer 10, the electrolyzers 20a, 20b, and 20c constitute one system, and the electrolyzers 20d, 20e, and 20f constitute another system. Seawater is supplied to a system constituted by the electrolytic cells 20a, 20b, and 20c from a pipeline 40a connected to the bottom of the electrolytic cell 20a. The supplied seawater is partly electrolyzed in the electrolytic cell 20a, and sent to the electrolytic cell 20b through a conduit 40b that connects the upper part of the electrolytic cell 20a and the lower part of the electrolytic cell 20b. Also in the electrolytic cell 20b, a part of seawater is electrolyzed similarly to the electrolytic cell 20a. The electrolytic bath 20c also receives seawater containing an electrolytic solution through a conduit 40c that connects the upper portion of the electrolytic bath 20b and the lower portion of the electrolytic bath 20c, and electrolyzes part of the seawater in the electrolytic bath 20c. The electrolytic solution generated by electrolysis in the electrolytic bath 20c is sent to the electrolytic solution receiving bath (not shown) through the pipe line 41 together with undecomposed seawater.

  As described above, seawater is fed in series in the order of the electrolytic cells 20a, 20b, and 20c, and is electrolyzed in each electrolytic cell. The electrolytic baths 20d, 20e, and 20f are similar to the electrolytic baths of another system, and the electrolytic baths 20d, 20e, and 20f receive seawater through the conduits 40d, 40e, and 40f, and electrolyze them. The electrolyte solution and undecomposed seawater are discharged through 42.

  Pipe lines 43 and 44 for supplying and discharging the cleaning liquid are disposed at the lower part of each series of electrolytic cells. A pipe line 43 is provided in the system constituted by the electrolytic cells 20a, 20b, and 20c. The pipe 43 is provided with valves 45 and 46 at the inlet and outlet, respectively, and a branch pipe is provided in the middle of the pipe, and valves 47a, 47b and 47c are mounted on the branch pipe. One end of each of the valves 47a, 47b, and 47c is connected to the conduits 40a, 40b, and 40c. Through these, the electrolytic cells 20a, 20b, and 20c can be cleaned by sending an acid as a cleaning solution to the electrolytic cells 20a, 20b, and 20c.

  Similarly, a pipe 44 is provided in a system constituted by the electrolytic cells 20d, 20e, and 20f. The pipe 44 is provided with valves 48 and 49 at the inlet and outlet, respectively, and has a branch pipe in the middle of the pipe, and valves 47d, 47e and 47f are mounted on the branch pipe. One end of each of the valves 47d, 47e, and 47f is connected to the conduits 40d, 40e, and 40f. Through these, the electrolytic cells 20d, 20e, and 20f can be cleaned by sending an acid as a cleaning solution to the electrolytic cells 20d, 20e, and 20f.

  A predetermined amount of electricity is sent to the electrodes 22 and 23 of the electrolytic cell 20 through the power supply device 60. The power supply device 60 includes an output voltage variable device that can change an output voltage (not shown), a voltage measuring device 61, and a current measuring device 62. In the seawater electrolysis apparatus 10, the power supply systems of the electrolyzers 20 a to 20 f are connected in series, and electricity is transmitted integrally from the power supply device 60.

  The data processing device 70 includes a data storage unit 71 and a data processing unit 72 that store data. The data storage unit 71 receives and stores voltage data and current data applied to the electrodes 22 and 23 from the power supply device 60 through a data input unit (not shown). The data processing unit 72 performs calculations using the data in the data storage unit 71. A computer can be used as the data processing device 70.

  The seawater electrolysis apparatus 10 having the above-described configuration operates continuously for a long period of time while periodically repeating the cleaning operation of the electrode with an acid. As described above, since the electrodes, particularly the anode, deteriorate and wear with long-term operation, the degree of deterioration was conventionally determined by visual observation. In the present invention, the deterioration degree of the electrode of the electrolytic cell is grasped by measuring the voltage-current characteristic data of the electrode. Specifically, the following procedure is performed.

  A predetermined voltage is applied to the electrolytic cells 20a to 20f through the power supply device 60, and the voltage and current at that time are measured by the voltage measuring device 61 and the current measuring device 62 of the power supply device 60. The voltage applied to the electrolytic cell 20a to the electrolytic cell 20f may be a single value, but it is desirable to change several points from the point of accuracy improvement and measure the current value at that time. The measurement of the voltage and current value of these electrodes can be performed when the seawater electrolysis apparatus 10 is maintained and inspected, but can also be performed during normal operation. Since the time required for measuring the voltage and current value of the electrode is very short, even if the voltage applied to the electrode during normal operation is changed and the current value is measured, the seawater electrolysis process is hardly affected.

  Using the measured voltage and current values of the electrodes 22 and 23, the degree of electrode degradation is calculated in the following manner. The actual measurement data of the voltages and currents of the electrodes 22 and 23 is sent from the power supply device 60 to the data processing device 70 and stored in the data storage unit 71. The data processing unit 72 calculates the voltage / current characteristic data of the electrodes using the measured voltage and current data stored in the data storage unit 71. The voltage / current characteristic data of the electrode is compared with predetermined voltage / current characteristic data of the electrode to measure the degree of deterioration of the electrode. In this manner, the data processing unit 72 functions as a calculation unit that calculates the degree of electrode degradation.

  In order to calculate the voltage / current characteristic data, several voltage / current data are not necessarily required. Of course, the voltage / current characteristic data can be calculated from the voltage / current data at one point. In the case of consisting of voltage and current data at one point, it can be said that measuring the current value will calculate the voltage-current characteristic data. In order to increase the accuracy, it is desirable to calculate the relationship between the voltage and the current value, that is, the voltage-current characteristic data of the electrode, using several points of voltage and current data.

  Use the following procedure to calculate the electrode usage limit. The electrode voltage and current data are measured at a predetermined interval, for example, every year, and the actual measurement data is stored in the data storage unit 71 of the data processing device 70. The data processing unit 72 uses the actual measurement data stored in the data storage unit 71 to calculate the voltage / current characteristic data of the electrodes. The calculation of the voltage / current characteristic data is performed for several times of data stored in the data storage unit 71. From these voltage-current characteristics data, the data processor 72 calculates the change over time in the degree of deterioration of the electrode, and calculates the usage limit of the electrode. In this way, the data processing unit 72 functions as a calculation unit that calculates the use limit of the electrode.

In the calculation of the electrode usage limit, it is also possible to calculate the electrode usage limit from the voltage and current values at one point in the same manner as the degree of deterioration of the electrode. In this case, the voltage / current characteristic data of the electrodes measured at a predetermined interval can be obtained at the same voltage every time. In addition, the measurement interval of the voltage and current data of the electrode is not necessarily constant, and it is needless to say that the voltage and current data at the time of measuring the deterioration degree of the electrode may be used.

  In the seawater electrolysis system 10 of the present embodiment, electricity is supplied in series to the six electrolyzers 20a to 20f, so that the voltage / current characteristic data of the electrodes as a whole of the six electrolyzers is grasped. In this case, it is difficult to grasp the voltage-current characteristic data of the electrodes of each of the six electrolytic cells, but the degree of deterioration and use of the electrodes of each electrolytic cell by supplying electricity to each individual electrolytic cell It goes without saying that it is possible to grasp the limits. If the use limit of the electrode is calculated by the method of the present invention and it is found that the electrode has reached the use limit, the electrolytic cell is disassembled, the electrode is taken out, and the surface of the anode is covered again. On the other hand, when the electrode has not reached the limit of use, it is not necessary to disassemble the electrolytic cell in order to check the electrode, so that it is less time-consuming than the conventional visual observation method.

(Example 1) The results of measuring the degree of deterioration of the electrode of the electrolytic cell of the present invention are shown in the Examples.
In this example, among the three series of seawater electrolyzers A to C, the deterioration degree of the electrodes of the B series and C series seawater electrolyzers was measured. Each of the B series and the C series was provided with 12 electrolytic cells, and the electric circuits of the 12 electrolytic cells were connected in series. FIG. 4 is a diagram showing a result of measuring voltage / current specifying data of electrodes of a B-series seawater electrolysis apparatus. FIG. 5 is a diagram showing the results of measuring voltage / current identification data of electrodes of a C-series seawater electrolysis apparatus. 4 and 5, each cell voltage on the vertical axis is a value obtained by dividing the voltage of each of the 12 electrolytic cells as a unit and dividing by the number of electrolytic cells.

  From FIG. 4 or FIG. 5, it was found that a linear relationship was established between the electrode voltage and current during seawater electrolysis, and this tendency was the same even when the number of working days increased. In addition, if the maximum current flowing through the electrodes of each series of electrolytic cells is set to 3000A and the allowable voltage at that time is set to 6V, the B series electrolytic cells pass current 3000A as of December 3, 2003. Therefore, it is necessary to apply a voltage of about 6.3 V to the electrode of each electrolytic cell, and it is understood that it is time to repair the electrode (anode). On the other hand, as for the C-series electrolytic cell, as of March 3, 2004, the voltage required to pass a current of 3000 A is about 5.2 V, and it can be seen that there is room for repair.

  FIG. 6 is a diagram in which the use limit of the electrode is predicted based on the measurement result of the voltage-current characteristic of the C-series electrolytic cell in FIG. The voltage on the vertical axis in FIG. 6 is a voltage required when a current of 3000 A flows through the electrode. It can be seen from FIG. 6 that, if the usage method is the same as before, the C-series electrodes can be used until about 55 when the allowable voltage value is 6V.

It is a figure which shows schematic structure of the seawater electrolyzer 10 as one Embodiment of this invention. It is an exploded view of one electrolysis tank 20a which constitutes seawater electrolysis device 10 as one embodiment of the present invention. It is an assembly figure of one electrolytic vessel 20a which constitutes seawater electrolysis device 10 as one embodiment of the present invention. It is a figure which shows the voltage current specific result of the electrode of the B series seawater electrolysis apparatus measured using the degradation degree measuring method of the electrode of this invention. It is a figure which shows the voltage-current specific result of the electrode of the C series seawater electrolysis apparatus measured using the degradation degree measuring method of the electrode of this invention. It is the figure which estimated the use limit of the electrode based on the voltage-current specific result of the electrode of the C series seawater electrolysis apparatus measured using the degradation degree measuring method of the electrode of this invention. It is a figure which shows the schematic flow of the seawater electrolysis system of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Seawater electrolysis apparatus 20 Electrolysis tank 22, 23 Electrode 60 Power supply device 61 Voltage measuring device 62 Current measuring device 70 Data processing device 71 Data storage part 72 Data processing part

Claims (2)

A method for measuring the degree of deterioration of an electrode of a seawater electrolysis apparatus comprising an electrolytic cell comprising an electrode for electrolyzing seawater, and a power supply means for applying a voltage to the electrode of the electrolytic cell and capable of changing an output voltage. ,
During operation of the seawater electrolysis device, via the power supply means to apply a plurality of different voltages to the electrodes, and measuring a current value flowing through the electrode at that time, calculated voltage-current characteristic data of the electrode, of the electrode An electrode deterioration degree measuring method for a seawater electrolysis apparatus, comprising measuring an electrode deterioration degree from voltage / current characteristic data and predetermined voltage / current characteristic data of the electrode. A method for calculating a use limit of an electrode of a seawater electrolysis apparatus comprising an electrolytic cell provided with an electrode for electrolyzing seawater, and a power supply means for applying a voltage to the electrode of the electrolytic cell and capable of changing an output voltage. ,
At predetermined intervals, during operation of the seawater electrolysis apparatus, a plurality of different voltages are applied to the electrodes via the power supply means, current values flowing through the electrodes at that time are measured, and voltage-current characteristic data of the electrodes And calculating a use limit of the electrode from the time-dependent change in the voltage-current characteristic data of the electrode.

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