Device for preparing sodium hypochlorite by electrolyzing seawater and supporting polarity reversal

Abstract

The utility model relates to a device for preparing sodium hypochlorite by electrolyzing seawater and supporting polarity reversal. The sodium hypochlorite electrolytic bath is electrically connected with a polarity variable electrolysis power supply, the polarity variable electrolysis power supply comprises a rectifying circuit, the rectifying circuit is connected to alternating current mains supply, the rectifying circuit is connected with an inverter and provides direct current input for the inverter, the direct current input is converted into controllable alternating current through the inverter, and the controllable alternating current is connected with the polarity variable electrolysis power supply. The inverter is connected with two polarity-variable cascade direct current generation circuits, the output polarities of the polarity-variable cascade direct current generation circuits are opposite, the polarity-variable cascade direct current generation circuits are electrically connected with a controller, the controller is electrically connected with a second conductivity sensor arranged on the sodium hypochlorite electrolytic cell, and the controller collects the output voltage of a polarity-variable electrolytic power supply. And the controller is electrically connected with the electrolytic current sensor. Deposition condition detection is supported, and through polarity conversion, sediments such as calcium hydroxide and magnesium hydroxide on the original cathode act with hydrogen ions to generate water and corresponding cations, so that the sediments are eliminated.

Description

Technical Field

[0001] The utility model relates to the technical field of sodium hypochlorite preparation devices, in particular to a device for preparing sodium hypochlorite by electrolyzing seawater that supports polarity inversion. Background Art

[0002] Seawater contains sodium chloride, which is the raw material for preparing sodium hypochlorite. Preparing sodium hypochlorite from seawater has a cost advantage. The process of preparing sodium hypochlorite by electrolyzing seawater involves a series of chemical reactions. In this process, chloride ions in seawater are electrolyzed in the electrolytic cell to produce sodium hypochlorite. The chemical reactions are as follows: Anodic reaction: 2Cl - →Cl2 + 2e - ; Cathodic reaction: 2H2O + 2e - →2OH - + H2↑. Chemical reaction between electrodes: Cl2 + 2OH - →ClO - + Cl - + H2O, and then ClO - + H2O → HClO + OH - . Total reaction: NaCl + H2O → NaClO + H2↑. However, seawater contains a large amount of calcium and magnesium ions. During the process of electrolyzing seawater, calcium and magnesium ions will form deposits such as calcium hydroxide and magnesium hydroxide on the cathode, resulting in an increase in the cell voltage of the electrolytic cell, a decrease in current efficiency, an increase in energy consumption when preparing the same amount of sodium hypochlorite. On the other hand, the large accumulation of deposits between the electrodes affects the contact between the electrodes and ions, further reducing the efficiency of preparing sodium hypochlorite. Summary of the Utility Model

[0003] In order to solve the above technical problems or at least partially solve the above technical problems, the utility model provides a device for preparing sodium hypochlorite by electrolyzing seawater that supports polarity inversion.

[0004] The utility model provides a device for preparing sodium hypochlorite by electrolyzing seawater, which supports polarity inversion, and includes: a sodium hypochlorite electrolytic cell, the sodium hypochlorite electrolytic cell is electrically connected to a polarity-variable electrolytic power supply, and the polarity-variable electrolytic power supply includes: a rectifying circuit, the rectifying circuit is connected to the AC mains, the rectifying circuit is connected to an inverter to provide DC input for the inverter, and the DC input is converted into controllable alternating current through the inverter. The inverter is connected to two polarity-variable cascade DC generating circuits, and the output polarities of the polarity-variable cascade DC generating circuits are opposite. The polarity-variable cascade DC generating circuit includes: five diodes D7, D8, D9, D10, and D11 arranged in sequence of positive and negative directions. Diodes D7, D8, D9, D10, and D11 are connected to capacitors C2, C3, C4, and C5 through a multiplexer switch; the multiplexer switch connects D7, D8, D9, and D10, or, connects D8, D9, D10, and D11 to the polarity-variable cascade DC generating circuit to control the change of polarity; the multiplexer switch is electrically connected to a switch driving circuit, the switch driving circuit is connected to a controller, the controller is electrically connected to a second conductivity sensor arranged in the sodium hypochlorite electrolytic cell, the controller collects the output voltage of the polarity-variable electrolytic power supply, and the controller is electrically connected to an electrolytic current sensor.

[0005] Furthermore, the sodium hypochlorite electrolytic cell is provided with a sewage outlet, a discharge port, and a liquid inlet; a first electric valve, a second electric valve, and a third electric valve are respectively arranged at the sewage outlet, the discharge port, and the liquid inlet. The third electric valve is connected to a seawater pretreatment mechanism and a water replenishing mechanism. The second electric valve is connected to the inlet of a gas-liquid separator, and the liquid outlet of the gas-liquid separator is communicated with a sodium hypochlorite storage tank.

[0006] Furthermore, the seawater pretreatment mechanism includes: a water pump, the water pump is connected to a seawater reaction filter, the seawater reaction filter is connected to a brine storage tank, and the outlet of the brine storage tank is connected to the inlet of a brine booster pump; the outlet of the brine booster pump is connected to a first one-way valve, and the first one-way valve is connected to the third electric valve through a pipeline. The first one-way valve allows brine to flow from the brine booster pump to the third electric valve.

[0007] Furthermore, a stirring mechanism is arranged in the brine storage tank, a salt addition port is arranged on the brine storage tank, and a first conductivity sensor is arranged downstream of the brine storage tank.

[0008] Furthermore, the water replenishing mechanism includes: a water tank, a water replenishing valve is arranged at the water outlet of the water tank, the water replenishing valve is connected to a flow regulating valve through a pipeline, a flow meter is arranged on the downstream pipeline of the flow regulating valve, the downstream of the flow meter is connected to a second one-way valve, and the second one-way valve is connected to the liquid inlet of the sodium hypochlorite electrolytic cell. The second one-way valve allows water to flow from the water tank to the liquid inlet of the sodium hypochlorite electrolytic cell.

[0009] Furthermore, the rectifier circuit includes: a rectifier bridge formed by series-connected diodes, and a capacitor C1 is connected in parallel with the series-connected diodes; the inverter is connected in parallel with the capacitor C1. The rectifier circuit provides DC input for the inverter. The inverter includes a single-phase bridge arm composed of two insulated gate bipolar transistors. The inverter is electrically connected to an inverter drive circuit, and the two single-phase bridge arms of the inverter are respectively connected to two polarity-variable cascade DC generating circuits.

[0010] Furthermore, the N pole of the diode D7 is connected to an optional contact of the sub-selection switch S1, and the P pole of the diode D7 is connected to an optional contact of the sub-selection switch S5; the P pole of the diode D8 is connected to another optional contact of the sub-selection switch S1 and an optional contact of the sub-selection switch S2, and the N pole of the diode D8 is connected to another optional contact of the sub-selection switch S5 and an optional contact of the sub-selection switch S6; the N pole of the diode D9 is connected to another optional contact of the sub-selection switch S2 and an optional contact of the sub-selection switch S3, and the P pole of the diode D9 is connected to another optional contact of the sub-selection switch S6 and an optional contact of the sub-selection switch S7; the P pole of the diode D10 is connected to another optional contact of the sub-selection switch S3 and an optional contact of the sub-selection switch S4, and the N pole of the diode D10 is connected to another optional contact of the sub-selection switch S7 and an optional contact of the sub-selection switch S8; the N pole of the diode D11 is connected to another optional contact of the sub-selection switch S4, and the P pole of the diode D11 is connected to another optional contact of the sub-selection switch S8; the selection terminals of the sub-selection switch S1 and the sub-selection switch S2 are interconnected and connected between the serially connected capacitor C2 and capacitor C4, the selection terminals of the sub-selection switch S3 and the sub-selection switch S4 are interconnected and connected to the plate of the capacitor C4 far from the capacitor C2; the selection terminals of the sub-selection switch S5 and the sub-selection switch S6 are connected to both ends of the capacitor C3, the selection terminals of the sub-selection switch S7 and the sub-selection switch S8 are connected to both ends of the capacitor C5, the capacitor C3 and the capacitor C5 are connected in series, and the plate of the capacitor C3 far from the capacitor C5 is grounded.

[0011] Furthermore, the signal interlocking of the switch drive circuits of the multi-way selection switches in the two polarity-variable cascade DC generating circuits.

[0012] The above technical solutions provided by the embodiments of the present invention have the following advantages compared with the prior art:

[0013] This application measures the conductivity of the electrolyte through a second conductivity sensor. This application supports detecting the electrolysis voltage and electrolysis current at the corresponding conductivity, thereby determining the impedance, and supports determining the situation of electrode deposition according to impedance anomalies. When the impedance anomaly reaches the set threshold, the polarity is temporarily reversed. The original anode of the sodium hypochlorite electrolytic cell becomes the cathode, and the cathode becomes the anode. Deposits such as calcium hydroxide and magnesium hydroxide on the original cathode react with hydrogen ions to produce water and corresponding cations, thereby realizing the elimination of deposits on the electrolysis electrodes. Description of the Drawings

[0014] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present utility model, and are used together with the specification to explain the principles of the present utility model.

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] Figure 1 It is a schematic diagram of a device for preparing sodium hypochlorite by electrolyzing seawater that supports polarity reversal provided by an embodiment of the present utility model.

[0017] Figure 2 It is a schematic diagram of a polarity-variable electrolysis power supply provided by an embodiment of the present utility model;

[0018] Figure 3 It is a schematic diagram of a polarity-variable cascade DC generating circuit provided by an embodiment of the present utility model.

[0019] The numbers and their meanings in the figures are as follows:

[0020] 1. Sodium hypochlorite electrolytic cell, 11. First electric valve, 12. Second electric valve, 13. Third electric valve, 14. Second conductivity sensor; 2. Seawater pretreatment mechanism, 21. Water pump, 22. Seawater reaction filter, 23. Brine storage tank, 24. Brine pressure pump, 25. First one-way valve, 26. First conductivity sensor; 3. Water replenishing mechanism, 31. Water tank, 32. Water replenishing valve, 33. Flow regulating valve, 34. Flowmeter, 35. Second one-way valve; 4. Gas-liquid separator; 5. Sodium hypochlorite storage tank; 6. Polarity-variable electrolysis power supply. Detailed Embodiments

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0022] It should be noted that, in this text, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0023] Referring to Figure 1 as shown, the embodiments of the present utility model provide a device for preparing sodium hypochlorite by electrolyzing seawater with support for polarity inversion, comprising:

[0024] A sodium hypochlorite electrolytic cell 1, the sodium hypochlorite electrolytic cell 1 is provided with a sewage outlet, a discharge outlet and a liquid inlet; a first electric valve 11, a second electric valve 12 and a third electric valve 13 are respectively arranged at the sewage outlet, the discharge outlet and the liquid inlet. The third electric valve 13 is connected to a seawater pretreatment mechanism 2 and a water replenishing mechanism 3. In the specific implementation process, the seawater pretreatment mechanism 2 is used to provide electrolytic brine. The seawater pretreatment mechanism 2 includes: a water pump 21, the water pump 21 is connected to a seawater reaction filter 22, and a sodium carbonate precipitant is added to the seawater reaction filter 22 to precipitate part of the calcium and magnesium ions through carbonate radicals, and the precipitate is filtered out by the seawater reaction filter. Most of the calcium and magnesium ions are removed by the reaction precipitation method to reduce the deposition of calcium and magnesium ions in the subsequent electrolysis process. The seawater reaction filter 22 is connected to a brine storage tank 23. The outlet of the brine storage tank 23 is connected to the inlet of a brine pressure pump 24; the outlet of the brine pressure pump 24 is connected to a first check valve 25, and the first check valve 25 is connected to the third electric valve 13 through a pipeline. The first check valve 25 allows the brine to flow from the brine pressure pump to the third electric valve 13. A first conductivity sensor 26 is arranged downstream of the brine storage tank 23. The first conductivity sensor 26 is used to detect the conductivity of the added seawater. A stirring mechanism is arranged in the brine storage tank 23. The brine storage tank 23 is provided with a salt addition port. The concentration of NaCl in seawater is relatively low, which is not conducive to electrolysis. During the pretreatment process, NaCl is added to the brine storage tank 23 until the conductivity of the seawater reaches the set threshold.

[0025] The water replenishing mechanism 3 is used to replenish water during the electrolysis process. Specifically, the water replenishing mechanism 3 includes: a water tank 31, a water replenishing valve 32 is arranged at the water outlet of the water tank 31, the water replenishing valve 32 is connected to a flow regulating valve 33 through a pipeline, a flow meter 34 is arranged on the downstream pipeline of the flow regulating valve 33, the downstream of the flow meter 34 is connected to a second one-way valve 35, and the second one-way valve 35 is connected to the liquid inlet of the sodium hypochlorite electrolyzer 1. The second one-way valve 35 allows water to flow from the water tank to the liquid inlet of the sodium hypochlorite electrolyzer 1. During the water replenishing process, the water replenishing valve 32 is turned on, and the flow rate of the replenished water is adjusted by the flow regulating valve.

[0026] The second electric valve 12 is connected to the inlet of the gas-liquid separator 4, and the liquid outlet of the gas-liquid separator 4 is communicated with the sodium hypochlorite storage tank 5; the generated hydrogen and liquid are separated by the gas-liquid separator 4.

[0027] The first electric valve 11 is connected to the sewage pool.

[0028] The sodium hypochlorite electrolyzer 1 is electrically connected to a polarity-variable electrolysis power supply 6. In the specific implementation process, as Figure 2 shown, the polarity-variable electrolysis power supply 6 includes a rectifying circuit, the rectifying circuit is connected to the AC mains power, converts the AC power into DC power, and then converts the DC input into controllable AC power through an inverter. The inverter is connected to two polarity-variable cascade DC generating circuits, and the output polarities of the polarity-variable cascade DC generating circuits are opposite.

[0029] In the specific implementation process, the rectifying circuit includes: a rectifying bridge formed by series-connected diodes, and a capacitor C1 is connected in parallel with the series-connected diodes. The inverter is connected in parallel with the capacitor C1, the rectifying circuit provides DC input for the inverter, the inverter includes a single-phase bridge arm composed of two insulated gate bipolar transistors, and the two single-phase bridge arms of the inverter are respectively connected to two polarity-variable cascade DC generating circuits.

[0030] As Figure 2 and Figure 3As shown in the figure, the polarity-variable cascade DC generating circuit includes five diodes D7, D8, D9, D10, and D11 arranged in sequence in the forward and reverse directions. The diodes D7, D8, D9, D10, and D11 are connected to a multiplexer switch, and the multiplexer switch connects D7, D8, D9, and D10, or connects D8, D9, D10, and D11 to the polarity-variable cascade DC generating circuit to control the change of polarity. In the specific implementation process, the multiplexer switch includes sub-switch S1, sub-switch S2, sub-switch S3, sub-switch S4, sub-switch S5, sub-switch S6, sub-switch S7, and sub-switch S8.

[0031] Among them, the N pole of diode D7 is connected to an optional contact of sub-switch S1, and the P pole of diode D7 is connected to an optional contact of sub-switch S5; the P pole of diode D8 is connected to another optional contact of sub-switch S1 and an optional contact of sub-switch S2, and the N pole of diode D8 is connected to another optional contact of sub-switch S5 and an optional contact of sub-switch S6; the N pole of diode D9 is connected to another optional contact of sub-switch S2 and an optional contact of sub-switch S3, and the P pole of diode D9 is connected to another optional contact of sub-switch S6 and an optional contact of sub-switch S7; the P pole of diode D10 is connected to another optional contact of sub-switch S3 and an optional contact of sub-switch S4, and the N pole of diode D10 is connected to another optional contact of sub-switch S7 and an optional contact of sub-switch S8; the N pole of diode D11 is connected to another optional contact of sub-switch S4, and the P pole of diode D11 is connected to another optional contact of sub-switch S8; the selection terminals of sub-switch S1 and sub-switch S2 are interconnected and connected between the serially connected capacitors C2 and C4, the selection terminals of sub-switch S3 and sub-switch S4 are interconnected and connected to the plate of capacitor C4 far from capacitor C2; the selection terminals of sub-switch S5 and sub-switch S6 are connected to both ends of capacitor C3, the selection terminals of sub-switch S7 and sub-switch S8 are connected to both ends of capacitor C5, capacitor C3 and capacitor C5 are serially connected, and the plate of capacitor C3 far from capacitor C5 is grounded.

[0032] For the convenience of explanation only, the multiplexer switch is decomposed into multiple sub-switches to describe the principle. In the actual operation process, sub-switch S1, sub-switch S2, sub-switch S3, sub-switch S4, sub-switch S5, sub-switch S6, sub-switch S7, and sub-switch S8 are synchronously driven by an enable signal to form as Figure 2 or Figure 3Two states in it.

[0033] In the specific implementation process, in order to ensure that the polarities of the two variable-polarity cascade DC generation circuits are opposite, the signals of the switch drive circuits of the multi-way switches in the two variable-polarity cascade DC generation circuits are interlocked. The multi-way switch is electrically connected to the switch drive circuit, the switch drive circuit is connected to the controller, the controller is electrically connected to the second conductivity sensor 14 arranged in the sodium hypochlorite electrolytic cell, the controller collects the output voltage of the variable-polarity electrolytic power supply, and the controller is electrically connected to the electrolytic current sensor 61. In this application, the conductivity of the electrolyte is measured by the second conductivity sensor 14. This application supports detecting the electrolytic voltage and electrolytic current at the corresponding conductivity, so as to determine the impedance, and supports determining the situation of electrode deposition according to abnormal impedance. When the abnormal impedance reaches the set threshold, the polarity is temporarily reversed, the original anode in the sodium hypochlorite electrolytic cell becomes the cathode, the cathode becomes the anode, and the deposits such as calcium hydroxide and magnesium hydroxide on the original cathode react with hydrogen ions to produce water and corresponding cations, thereby realizing the elimination of deposits on the electrolytic electrodes.

[0034] In the embodiments provided by the present utility model, it should be understood that the disclosed structure can be implemented in other ways. For example, the structure embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some interfaces, and the indirect coupling or communication connection of structures or units can be in electrical, mechanical or other forms.

[0035] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0036] In addition, in each embodiment of the present utility model, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0037] The above are only specific embodiments of the present utility model, enabling those skilled in the art to understand or implement the present utility model. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present utility model. Therefore, the present utility model will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. An apparatus for preparing sodium hypochlorite by electrolyzing seawater with support for polarity reversal, characterized in that, Comprising: A sodium hypochlorite electrolyzer (1), the sodium hypochlorite electrolyzer (1) being electrically connected to a polarity-variable electrolysis power supply (6), the polarity-variable electrolysis power supply (6) comprising: a rectification circuit, the rectification circuit being connected to the AC mains, the rectification circuit being connected to an inverter to provide a DC input to the inverter, converting the DC input into a controllable alternating current through the inverter, the inverter being connected to two polarity-variable cascade DC generation circuits with opposite output polarities, the polarity-variable cascade DC generation circuit comprising: five diodes D7, D8, D9, D10, and D11 arranged in sequence of positive and negative, the diodes D7, D8, D9, D10, and D11 being connected to capacitors C2, C3, C4, and C5 through a multiplexer switch; the multiplexer switch connects D7, D8, D9, and D10, or, connects D8, D9, D10, and D11 to the polarity-variable cascade DC generation circuit to control the change of polarity; the multiplexer switch is electrically connected to a switch drive circuit, the switch drive circuit is connected to a controller, the controller is electrically connected to a second conductivity sensor (14) disposed in the sodium hypochlorite electrolyzer, the controller collects the output voltage of the polarity-variable electrolysis power supply, and the controller is electrically connected to an electrolysis current sensor (61).

2. The device for preparing sodium hypochlorite by electrolyzing seawater supporting polarity inversion according to claim 1, characterized in that, The sodium hypochlorite electrolyzer (1) is provided with a sewage outlet, a discharge outlet, and a liquid inlet; a first electric valve (11), a second electric valve (12), and a third electric valve (13) are respectively arranged at the sewage outlet, the discharge outlet, and the liquid inlet, the third electric valve (13) is connected to a seawater pretreatment mechanism (2) and a water replenishment mechanism (3), the second electric valve (12) is connected to the inlet of a gas-liquid separator (4), and the liquid outlet of the gas-liquid separator (4) communicates with a sodium hypochlorite storage tank (5).

3. The device for preparing sodium hypochlorite by electrolyzing seawater that supports polarity reversal according to claim 2, wherein, The seawater pretreatment mechanism (2) comprises: a water pump (21), the water pump (21) being connected to a seawater reaction filter (22), the seawater reaction filter (22) being connected to a brine storage tank (23), the outlet of the brine storage tank (23) being connected to the inlet of a brine booster pump (24); the outlet of the brine booster pump (24) is connected to a first one-way valve (25), the first one-way valve (25) is connected to the third electric valve (13) through a pipeline, and the first one-way valve (25) allows brine to flow from the brine booster pump to the third electric valve (13).

4. The device for preparing sodium hypochlorite by electrolyzing seawater with support for polarity inversion according to claim 3, characterized in that, A stirring mechanism is arranged in the brine storage tank (23), a salt addition port is arranged on the brine storage tank (23), and a first conductivity sensor (26) is arranged downstream of the brine storage tank (23).

5. The device for preparing sodium hypochlorite by electrolyzing seawater with support for polarity reversal according to claim 2, wherein, The water replenishing mechanism (3) includes: a water tank (31), a water replenishing valve (32) is arranged at the water outlet of the water tank (31), the water replenishing valve (32) is connected to a flow regulating valve (33) through a pipeline, a flow meter (34) is arranged on the downstream pipeline of the flow regulating valve (33), the downstream of the flow meter (34) is connected to a second one-way valve (35), the second one-way valve (35) is connected to the liquid inlet of the sodium hypochlorite electrolyzer (1), and the second one-way valve (35) allows water to flow from the water tank to the liquid inlet of the sodium hypochlorite electrolyzer (1).

6. The device for preparing sodium hypochlorite by electrolyzing seawater that supports polarity inversion according to claim 1, wherein, The rectifier circuit includes: a rectifier bridge formed by series-connected diodes, and a capacitor C1 is connected in parallel with the series-connected diodes; the inverter is connected in parallel with the capacitor C1, the rectifier circuit provides a DC input for the inverter, the inverter includes a single-phase bridge arm composed of two insulated gate bipolar transistors, the inverter is electrically connected to an inverter drive circuit, and the two single-phase bridge arms of the inverter are respectively connected to two polarity-variable cascade DC generating circuits.

7. The device for preparing sodium hypochlorite by electrolyzing seawater that supports polarity inversion according to claim 1, wherein, The N pole of the diode D7 is connected to an optional contact of the sub-selection switch S1, and the P pole of the diode D7 is connected to an optional contact of the sub-selection switch S5; the P pole of the diode D8 is connected to another optional contact of the sub-selection switch S1 and an optional contact of the sub-selection switch S2, and the N pole of the diode D8 is connected to another optional contact of the sub-selection switch S5 and an optional contact of the sub-selection switch S6; the N pole of the diode D9 is connected to another optional contact of the sub-selection switch S2 and an optional contact of the sub-selection switch S3, and the P pole of the diode D9 is connected to another optional contact of the sub-selection switch S6 and an optional contact of the sub-selection switch S7; the P pole of the diode D10 is connected to another optional contact of the sub-selection switch S3 and an optional contact of the sub-selection switch S4, and the N pole of the diode D10 is connected to another optional contact of the sub-selection switch S7 and an optional contact of the sub-selection switch S8; the N pole of the diode D11 is connected to another optional contact of the sub-selection switch S4, and the P pole of the diode D11 is connected to another optional contact of the sub-selection switch S8; the selection terminals of the sub-selection switch S1 and the sub-selection switch S2 are interconnected and connected between the serially connected capacitor C2 and capacitor C4, the selection terminals of the sub-selection switch S3 and the sub-selection switch S4 are interconnected and connected to the plate of the capacitor C4 far from the capacitor C2; the selection terminals of the sub-selection switch S5 and the sub-selection switch S6 are connected to both ends of the capacitor C3, the selection terminals of the sub-selection switch S7 and the sub-selection switch S8 are connected to both ends of the capacitor C5, the capacitor C3 and the capacitor C5 are serially connected, and the plate of the capacitor C3 far from the capacitor C5 is grounded.

8. The device for preparing sodium hypochlorite by electrolyzing seawater supporting polarity inversion according to claim 1, characterized in that, The signals of the switch drive circuits of the multi-selection switches in the two polarity-variable cascade DC generating circuits are interlocked.

Images