Electrolysis of seawater anti-fouling system for seawater delivery pipeline

Abstract

This invention discloses a seawater antifouling system for transporting seawater via pipeline, comprising a pipeline and multiple in-situ electrolysis devices. The pipeline is used to transport seawater and includes a water intake head connected to a water intake channel, where sodium hypochlorite is added. Multiple in-situ electrolysis devices are sequentially and spaced apart along the length of the pipeline. These devices utilize ocean currents to directly generate electricity to electrolyze the seawater into sodium hypochlorite, which is then added to the pipeline. The effective chlorine concentration of sodium hypochlorite at various points within the pipeline is C, where C > 0.5 ppm. This invention solves the problem of inconvenience in adding sodium hypochlorite at multiple points within existing pipelines, improving the accuracy and convenience of sodium hypochlorite concentration addition.

Description

Technical Field

[0001] This invention relates to the field of antifouling technology for seawater electrolysis, and in particular to an antifouling system for seawater electrolysis in a seawater pipeline. Background Technology

[0002] The primary method for preventing biofouling in existing long-distance seawater pipelines is the addition of sodium hypochlorite as a disinfectant. Due to the long pipeline distances, this often requires multi-point, segmented addition of the disinfectant. However, this multi-point, long-distance addition method is inconvenient, whether using sodium hypochlorite produced through seawater electrolysis or as a finished product. Each addition point requires a power source or pipeline, conditions rarely found in the middle sections of long-distance pipelines. Seawater electrolysis for sodium hypochlorite production involves numerous devices, consumes a large amount of electricity, and requires a dedicated plant for setup and installation. For addition points far from the electrolysis plant, additional pipelines need to be laid, and each point requires at least one pump. Therefore, this approach is unsuitable for long-distance or multi-point addition. Summary of the Invention

[0003] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide an electrolytic seawater antifouling system for seawater pipelines, which solves the problem of inconvenience in adding sodium hypochlorite at multiple points in the pipeline and improves the accuracy and convenience of adding sodium hypochlorite concentration.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] This invention provides a seawater antifouling system for transporting seawater via pipeline electrolysis, comprising a pipeline and multiple in-situ electrolysis devices. The pipeline is used to transport seawater and includes a water intake head connected to a water intake channel, into which sodium hypochlorite is introduced. The multiple in-situ electrolysis devices are sequentially and spaced apart along the length of the pipeline. The in-situ electrolysis devices utilize ocean currents to directly generate electricity to electrolyze the seawater to obtain sodium hypochlorite, which is then introduced into the pipeline. The effective chlorine concentration of sodium hypochlorite at various points in the pipeline is C, where C > 0.5 ppm.

[0006] In one embodiment, the in-situ electrolysis device includes an impeller, a rotating shaft, and a power generation-electrolysis component. The impeller is connected to the power generation-electrolysis component via the rotating shaft, and the kinetic energy of the impeller is transmitted to the power generation-electrolysis component via the rotating shaft.

[0007] In one embodiment, the power generation-electrolysis component includes a generator, a rectifier, and an electrolysis electrode. The generator is connected to the impeller via the rotating shaft. The generator converts water energy into alternating current (AC). The rectifier converts the AC into direct current (DC). The electrolysis electrode uses the DC to electrolyze seawater into sodium hypochlorite.

[0008] In one embodiment, the electrolytic electrode has a bipolar structure, with the electrodes at both ends of the electrolytic electrode connected to the positive and negative terminals of the rectifier, respectively. One side of each electrode in the middle of the electrolytic electrode is an anode, and the other side is a cathode.

[0009] In one embodiment, the power generation-electrolysis component further includes a housing, wherein the generator, the rectifier, and the electrolysis electrode are integrated and mounted on the inner wall of the housing.

[0010] In one embodiment, the shell is provided with a mesh structure at both ends along the direction of water flow.

[0011] In one embodiment, the system further includes an electrolytic chlorination device, wherein sodium hypochlorite prepared by the electrolytic chlorination device is fed into the water intake head.

[0012] In one embodiment, the arrangement method of the plurality of in-situ electrolysis devices in the pipeline specifically includes:

[0013] S1. Design a dynamic simulation test to obtain the decay curve and kinetic equation of the effective chlorine concentration of sodium hypochlorite in seawater over time during the flow of seawater in the pipeline, and obtain the slow decay segment of sodium hypochlorite concentration, which includes the highest concentration point and the lowest concentration point. Set an in-situ electrolysis device at the position corresponding to the lowest concentration point so that the chlorine concentration after chlorination can reach the highest concentration point again. As the seawater flows, install another in-situ electrolysis device at the position where the effective chlorine concentration reaches the lowest concentration point again. In this way, install multiple in-situ electrolysis devices in the pipeline.

[0014] The initial chlorine concentration of sodium hypochlorite added at the water intake head is C0, and the highest concentration point in the slow decay section is set as the chlorine concentration C after each chlorination. 11 The lowest concentration point in the slow decay phase is set as the chlorine concentration C before each chlorination. 10 C 10 ≥0.5ppm, the decay curve shows that C0 changes to C 10 The time is T1, C 11 Change to C 10 The time is T2;

[0015] S2. N in-situ electrolysis device dosing points are sequentially installed in the pipeline along the direction of coastal water flow. The distance between the first dosing point and the water intake head is calculated according to formula (i):

[0016] (i)

[0017] In the formula:

[0018] L1—Distance between the first dosing point and the water intake head, in meters;

[0019] v — seawater velocity, m / s;

[0020] T1——C0 becomes C 10 Time, s;

[0021] The distance between two subsequent adjacent dosing points is calculated using formula (ii):

[0022] (ii)

[0023] In the formula:

[0024] L2—the distance between two adjacent dosing points, in meters;

[0025] v — seawater velocity, m / s;

[0026] T2——C 11 Change to C 10 Time, s;

[0027] The number of injection points is calculated according to formula (iii):

[0028] (iii)

[0029] In the formula, Take the integer part.

[0030] In one embodiment, the method for calculating the initial available chlorine requirement of sodium hypochlorite added at the water intake head includes:

[0031] The initial amount of available chlorine added is calculated according to formula (1):

[0032] (1)

[0033] In the formula:

[0034] G0 – Initial available chlorine requirement, kg / h;

[0035] C0—Design initial chlorine dosage concentration, mg / L;

[0036] Q – Seawater flow rate, m³ / h;

[0037] The seawater flow rate is calculated according to formula (2):

[0038] (2)

[0039] In the formula:

[0040] Q – Seawater flow rate, m³ / h;

[0041] D—Pipe inner diameter, in meters;

[0042] v — Seawater flow velocity, m / s.

[0043] In one embodiment, the method for calculating the effective chlorine requirement at the first dosing point includes:

[0044] The amount of available chlorine added at the first dosing point is calculated according to formula (3):

[0045] (3)

[0046] In the formula:

[0047] G1 – Available chlorine requirement at the first dosing point, kg / h;

[0048] C 11 —The chlorine concentration after chlorination at the first dosing point, in mg / L;

[0049] C 10 —Chlorine concentration before chlorination at the first dosing point, mg / L;

[0050] Q – Seawater flow rate, m³ / h;

[0051] Within the pipeline, the effective chlorine requirement at the second dosing point is G2, the effective chlorine requirement at the third dosing point is G3, ..., and the effective chlorine requirement at the Nth dosing point is G... N G1=G2=G3=......=G N .

[0052] The beneficial effects of this invention are as follows: Multiple in-situ electrolysis devices are dispersedly installed at the chlorination points where chlorination is required. When seawater flows through these devices, the ocean current directly generates electricity to electrolyze the seawater and produce sodium hypochlorite. The sodium hypochlorite diffuses downstream with the water flow, solving the problems of complex engineering and inconvenience of long-distance multi-point addition methods caused by setting up addition pipelines and pumps at multiple addition points. This improves the convenience of adding sodium hypochlorite into pipelines. Furthermore, since the amount of sodium hypochlorite produced is directly proportional to the seawater flow rate, and the seawater flow rate is also directly proportional to the seawater flow rate, the greater the seawater flow rate, the more sodium hypochlorite is produced, and the smaller the seawater flow rate, the less sodium hypochlorite is produced, thus maintaining a stable sodium hypochlorite concentration in the seawater. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of the in-situ electrolysis device of an embodiment of the present invention installed in a pipeline;

[0055] Figure 2 This is a schematic diagram of the in-situ electrolysis device;

[0056] Figure 3 This is a schematic diagram of the antifouling system for seawater electrolysis in the seawater transport pipeline of Example 1;

[0057] Figure 4 This is a graph showing the decrease in the concentration of available chlorine in seawater in Example 1.

[0058] In the diagram: 1. Pipeline; 11. Water intake head; 2. In-situ electrolysis device; 21. Impeller; 22. Rotating shaft; 23. Power generation-electrolysis component; 231. Shell; 3. Electrolytic chlorination device; 4. Water diversion channel; 5. Ship barrier net; 1#, first injection point; 2#, second injection point; 3#, third injection point; 4#, fourth injection point; 5#, fifth injection point. Detailed Implementation

[0059] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. Based on the description of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0060] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0061] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0062] The terms “first,” “second,” “third,” etc., are used merely to distinguish elements with similar properties, not to indicate or imply relative importance or a specific order.

[0063] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0064] The existing long-distance seawater transport pipeline 1 primarily employs sodium hypochlorite as a biofouling agent to prevent marine biofouling. Due to the long distance of the pipeline 1, it often requires multi-point, segmented addition of the biofouling agent. However, this multi-point, long-distance addition method is inconvenient, regardless of whether the sodium hypochlorite is prepared by electrolysis of seawater or is a pre-prepared product. This is because each addition point requires a power source or pipeline, conditions that are rarely available in the middle sections of the long-distance pipeline 1. Figures 1 to 3 As shown, the present invention provides a seawater antifouling system for transporting seawater via pipeline electrolysis, comprising a pipeline 1 and multiple in-situ electrolysis devices 2. The pipeline 1 is used to transport seawater and includes a water intake head 11 connected to a water intake channel 4, into which sodium hypochlorite is introduced. A ship-blocking net 5 is provided at the water intake channel 4 to prevent ships from accidentally entering. Multiple in-situ electrolysis devices 2 are installed sequentially and at intervals along the length of the pipeline 1. The in-situ electrolysis devices 2 use ocean currents to directly generate electricity to electrolyze the seawater to obtain sodium hypochlorite, which is then introduced into the pipeline 1. The effective chlorine concentration of sodium hypochlorite at each point in the pipeline 1 is C, where C>0.5ppm.

[0065] In this embodiment, after sodium hypochlorite is added to the water intake head 11 of pipeline 1, as seawater flows along pipeline 1, the effective chlorine concentration in the seawater decreases after a certain distance from the water intake head 11, making it difficult to achieve a sterilization effect. Therefore, sodium hypochlorite needs to be added again. The in-situ electrolysis device 2 is distributed and installed at the points where chlorination is needed. When seawater flows through this device, the ocean current directly generates electricity to electrolyze the seawater and produce sodium hypochlorite. The sodium hypochlorite diffuses downstream with the water flow, solving the problems of complex engineering and inconvenience of long-distance multi-point addition methods caused by setting up addition pipelines and pumps at multiple addition points. This improves the convenience of adding sodium hypochlorite into pipeline 1. Furthermore, since the amount of sodium hypochlorite produced is proportional to the seawater flow rate, and the seawater flow rate is also proportional to the seawater flow rate, the greater the seawater flow rate, the more sodium hypochlorite is produced; conversely, the smaller the seawater flow rate, the less sodium hypochlorite is produced, maintaining a stable sodium hypochlorite concentration in the seawater. This invention provides an effective and reliable measure to prevent marine biofouling in seawater transport pipeline 1. The effective chlorine concentration of sodium hypochlorite at various points within pipe 1 is C, where C > 0.5 ppm. This ensures that the effective concentration of sodium hypochlorite is within the range required to effectively prevent biofouling of the seawater transport pipe 1 and avoids the problem of incomplete sterilization caused by excessively low sodium hypochlorite concentration.

[0066] As one implementation method, such as Figure 1 and Figure 2As shown, the in-situ electrolysis device 2 includes an impeller 21, a rotating shaft 22, and a power generation-electrolysis component 23. The impeller 21 is connected to the power generation-electrolysis component 23 via the rotating shaft 22, and the kinetic energy of the impeller 21 is transferred to the power generation-electrolysis component 23 through the rotating shaft 22. In this embodiment, the seawater flow drives the impeller 21 to rotate, thereby driving the rotating shaft 22 to rotate and transferring kinetic energy to the power generation-electrolysis component 23. The power generation-electrolysis component 23 converts the kinetic energy of the seawater into electrical energy, and then uses this electrical energy to electrolyze the seawater to produce sodium hypochlorite, which is then introduced into the seawater in the pipeline 1. As the seawater flows, it carries the sodium hypochlorite downstream to ensure the concentration of sodium hypochlorite at various points in the pipeline 1.

[0067] As one implementation method, such as Figure 2 As shown, the power generation-electrolysis unit 23 includes a generator (not shown), a rectifier (not shown), and electrolysis electrodes (not shown). The generator is connected to the impeller 21 via a rotating shaft 22. The generator converts water energy into alternating current (AC). The rectifier converts the AC into direct current (DC). The electrolysis electrodes use the DC to electrolyze seawater into sodium hypochlorite. Specifically, the seawater in pipe 1 flows in a directional manner, driving the impeller 21 on the in-situ electrolysis device 2 to rotate. The rotation of the impeller 21 drives the generator to generate electricity. The rectifier rectifies the generated electricity and supplies it to the electrolysis electrodes. After the seawater flows through the electrodes, sodium hypochlorite is produced and diffused downstream with the water flow to ensure that the concentration of sodium hypochlorite in the seawater in the subsequent section of pipe 1 is within a range that effectively prevents marine biofouling.

[0068] The generator comprises a rotor (not shown), a stator (not shown), and a transmission mechanism (not shown). The rotor is a permanent magnet, and the stator is a coil. The generator produces alternating current (AC), which is converted to direct current (DC) by a rectifier to power the electrolytic electrodes. The rectifier consists of a bridge circuit composed of multiple diodes. This ensures that only one diode conducts during each half-cycle of the AC current, resulting in unidirectional DC current at the output. The rectifier not only converts AC to DC but also includes a filter circuit to reduce output voltage ripple, making the output smoother.

[0069] In one implementation, the electrolytic electrode has a bipolar structure, with the electrodes at both ends of the electrolytic electrode connected to the positive and negative terminals of the rectifier, respectively. One side of each electrode in the middle of the electrolytic electrode is the anode, and the other side is the cathode.

[0070] As one implementation method, such as Figure 2 As shown, the power generation-electrolysis component 23 also includes a housing 231, on which the generator, rectifier, and electrolysis electrodes are integrated and installed on the inner wall of the housing 231. The housing 231 is made of fiberglass.

[0071] As one implementation method, such as Figure 2As shown, the shell 231 has a mesh structure at both ends along the direction of water flow to prevent large particles from entering.

[0072] As one implementation method, such as Figure 3 As shown, the system also includes an electrolytic chlorination unit 3, from which sodium hypochlorite prepared by the electrolytic chlorination unit 3 is introduced into the water intake head 11. The electrolytic chlorination unit 3 is located near the water intake head 11 and includes a seawater pump (not shown), a filter (not shown), an electrolytic cell (not shown), a rectifier (not shown), a sodium hypochlorite storage tank (not shown), and a dosing pump (not shown). The sodium hypochlorite solution is added to the water intake head 11 of the pipeline via the dosing pump and a dosing pipeline. Alternatively, a sodium hypochlorite storage tank can be installed directly at the water intake head 11, and the sodium hypochlorite in the tank can be directly pumped into the water intake head 11 of the pipeline.

[0073] As one implementation method, the arrangement of multiple in-situ electrolysis devices 2 in pipeline 1 specifically includes:

[0074] S1. Design a dynamic simulation test to obtain the decay curve and kinetic equation of the effective chlorine concentration of sodium hypochlorite in seawater as it changes with time during the flow of seawater in pipe 1. Obtain the slow decay segment of sodium hypochlorite concentration, which includes the highest concentration point and the lowest concentration point. Set up an in-situ electrolysis device 2 at the position corresponding to the lowest concentration point so that the chlorine concentration after chlorination can reach the highest concentration point again. As the seawater flows, install another in-situ electrolysis device 2 at the position where the effective chlorine concentration reaches the lowest concentration point again. In this way, install multiple in-situ electrolysis devices 2 in pipe 1.

[0075] The initial chlorine concentration of sodium hypochlorite added at the water intake head 11 is C0, and the highest concentration in the slow decay section is set as the chlorine concentration C after each chlorination. 11 The lowest concentration point in the slow decay phase is set as the chlorine concentration C before each chlorination. 10 C 10 ≥0.5ppm, the decay curve shows that C0 changes to C 10 The time is T1, C 11 Change to C 10 The time is T2;

[0076] S2. N in-situ electrolysis device 2 injection points are sequentially installed in the pipeline 1 along the direction of coastal water flow. The distance between the first injection point and the water intake head 11 is calculated according to formula (i):

[0077] (i)

[0078] In the formula:

[0079] L1—Distance between the first dosing point and the water intake head 11, in meters;

[0080] v — seawater velocity, m / s;

[0081] T1——C0 becomes C 10 Time, s;

[0082] The distance between two subsequent adjacent dosing points is calculated using formula (ii):

[0083] (ii)

[0084] In the formula:

[0085] L2—the distance between two adjacent dosing points, in meters;

[0086] v — seawater velocity, m / s;

[0087] T2——C 11 Change to C 10 Time, s;

[0088] The number of injection points is calculated according to formula (iii):

[0089] (iii)

[0090] In the formula, Take the integer part.

[0091] In this embodiment, as Figure 3 and Figure 4 As shown, a dynamic simulation experiment was designed. After sodium hypochlorite was added at the water intake head 11 of pipeline 1, the CO concentration was measured. Samples were taken at corresponding locations downstream of pipeline 1 at different time points to measure the effective chlorine concentration of sodium hypochlorite in seawater at those locations. For example, sampling was set at 0.5-hour intervals. The first sampling location was S1 = v * 0.5, the second sampling locations were S2 = v * 1, S3 = v * 1.5, ..., where v is the seawater flow velocity, and S1~Sn are the distances from the sampling point to the water intake head 11. The effective chlorine concentration of sodium hypochlorite in seawater can be measured using an online chloride ion detector. A curve was plotted showing the change in effective chlorine concentration over time, thus obtaining the decay curve and kinetic equation of the effective chlorine concentration of sodium hypochlorite in pipeline 1 over time. Analysis of the decay curve revealed a slow decay segment, where the effective chlorine concentration changes minimally over time, exhibiting a flattened curve. Maintaining the effective chlorine concentration in pipe 1 within this range ensures that sodium chlorate inhibits fouling organisms while minimizing the amount of sodium hypochlorite required, resulting in good economic benefits. Therefore, the highest point of the slow decay segment was taken as the chlorine concentration C after each chlorination. 11 The lowest point of the slow decay phase is taken as the chlorine concentration C before each chlorination. 10 That is, when the effective chlorine concentration is C each time 10At that time, an in-situ electrolysis device 2 is set up at the corresponding location. The initial chlorine concentration is C0, which is then changed to C. 10 If the time T1 is the distance between the first dosing point and the water intake head 11, then... An in-situ electrolysis device 2 is installed at this location, so that the chlorine concentration after chlorination returns to C. 11 Downstream of the first dosing point, a slow-decay concentration change curve reappeared, where the effective chlorine concentration returned to C. 10 The location is the second injection point, where another in-situ electrolysis device 2 is installed; multiple in-situ electrolysis devices 2 are thus arranged and installed to ensure that the effective chlorine concentration at the outlet of pipeline 1 is >0.5ppm.

[0092] Furthermore, the method for calculating the initial available chlorine requirement of sodium hypochlorite added at point 11 of the water intake includes:

[0093] The initial amount of available chlorine added is calculated according to formula (1):

[0094] (1)

[0095] In the formula:

[0096] G0 – Initial available chlorine requirement, kg / h;

[0097] C0—Design initial chlorine dosage concentration, mg / L;

[0098] Q – Seawater flow rate, m³ / h;

[0099] The seawater flow rate is calculated according to formula (2):

[0100] (2)

[0101] In the formula:

[0102] Q – Seawater flow rate, m³ / h;

[0103] D—Inner diameter of pipe 1, in meters;

[0104] v — Seawater flow velocity, m / s.

[0105] Furthermore, the method for calculating the effective chlorine requirement at the first dosing point includes:

[0106] The amount of available chlorine added at the first dosing point is calculated according to formula (3):

[0107] (3)

[0108] In the formula:

[0109] G1 – Available chlorine requirement at the first dosing point, kg / h;

[0110] C 11 —The chlorine concentration after chlorination at the first dosing point, in mg / L;

[0111] C 10 —Chlorine concentration before chlorination at the first dosing point, mg / L;

[0112] Q – Seawater flow rate, m³ / h;

[0113] Within pipeline 1, the effective chlorine requirement at the second dosing point is G2, the effective chlorine requirement at the third dosing point is G3, ..., and the effective chlorine requirement at the Nth dosing point is G... N G1=G2=G3=......=G N .

[0114] The present invention will be further described below with reference to specific embodiments to increase its implementability.

[0115] Example 1

[0116] Seawater from a certain project enters the intake head 11 through a water diversion channel 4. The pipeline is 19 km long, with an inner diameter of 2 m and a flow velocity of 0.85 m / s. A dynamic simulation experiment is used to determine a suitable and effective prevention and control scheme. The dynamic simulation experiment data is as follows:

[0117] The initial concentration of sodium hypochlorite was 10 mg / L, the seawater flow rate was 0.85 m / s, the effective chlorine concentration of sodium hypochlorite decreased to 1.415 mg / L in 1 hour and to 0 mg / L in 2 hours, and the test water temperature was 24.8℃.

[0118] Using this invention for marine biofouling, the decay curve and kinetic equation of sodium hypochlorite in seawater were determined based on dynamic simulation experiments. Then, a comprehensive analysis was conducted to determine the number of application points. To ensure that sodium hypochlorite inhibits the attachment of fouling organisms, the concentration of available chlorine in the seawater should be greater than 0.5 ppm.

[0119] from Figure 4 As shown in the curve, with an initial dosage concentration of 10 ppm, the effective chlorine concentration decreased to approximately 0.5 ppm after 1.5 hours. The curve also indicates that the chlorine decay is relatively slow at an effective chlorine concentration of 3.325 ppm. Therefore, controlling the effective chlorine concentration at 3.325 ppm at the intermediate dosing point is more economical. Specifically, the initial chlorine dosage of sodium hypochlorite added at the water intake point 11 is C0, which is 10 ppm. The highest concentration in the slow decay phase is set as the chlorine concentration C after each chlorination. 11 The concentration was 3.325 ppm, and the lowest concentration in the slow decay phase was set as the chlorine concentration C before each chlorination. 10 C 10The value should ideally be 0.5 ppm, but in actual experiments, for the sake of calculation simplicity, C is used here. 10 The decay time corresponding to 0.685 ppm is 1 hour, which simplifies the calculation process. The decay curve shows that C0 becomes C... 10 The time T1 is 1.5h, C 11 Change to C 10 The time T2 is 1 hour, meaning that it takes about 1 hour for the concentration to decrease from 3.325 ppm to 0.5 ppm.

[0120] N in-situ electrolysis device 2 injection points are sequentially arranged in the direction of coastal water flow within pipeline 1. The distance between the first injection point 1# and the water intake head 11 is calculated according to formula (i):

[0121] (i)

[0122] In the formula:

[0123] L1—The distance between the first dosing point 1# and the water intake head 11, in meters;

[0124] v — seawater velocity, m / s;

[0125] T1——C0 becomes C 10 Time, s;

[0126] In this first embodiment,

[0127] The distance between two subsequent adjacent dosing points is calculated using formula (ii):

[0128] (ii)

[0129] In the formula:

[0130] L2—the distance between two adjacent dosing points, in meters;

[0131] v — seawater velocity, m / s;

[0132] T2——C 11 Change to C 10 Time, s;

[0133] The number of injection points is calculated according to formula (iii):

[0134] (iii)

[0135] In the formula, Take the integer part.

[0136] In this first embodiment, That is, the distance between any two subsequent adjacent application points is 3km; the total number of application points In this embodiment, five in-situ electrolysis devices 2 are required to be installed at five feeding points, and the specific data of each feeding point are shown in Table 1.

[0137] Table 1. Record of the location arrangement of each dosing point in Example 1

[0138]

[0139] Therefore, the proposed solution for this project is:

[0140] (1) The electrolytic chlorination device 3 is located near the water intake head 11. The electrolytic chlorination device 3 includes a seawater pump, a filter, an electrolytic cell, a rectifier, a sodium hypochlorite storage tank, and a dosing pump. The sodium hypochlorite solution is added to the water intake head 11 of the pipeline through the dosing pump and the dosing pipeline. The chlorine concentration at the water intake head 11 is 10 ppm. The chlorine concentration of 10 ppm can ensure that the facilities in contact with seawater are not damaged by chlorine, and can also effectively inhibit the growth of fouling organisms. It also has a killing effect on some fouling organisms and can reduce the number of subsequent dosing points.

[0141] The available chlorine requirement is calculated using formula (1):

[0142] (1)

[0143] In the formula:

[0144] G0 – Initial available chlorine requirement, kg / h;

[0145] C0—Design initial chlorine dosage concentration, mg / L;

[0146] Q – Seawater flow rate, m³ / h.

[0147] Seawater flow rate is calculated according to formula (2):

[0148] (2)

[0149] In the formula:

[0150] Q – Seawater flow rate, m³ / h;

[0151] D—Inner diameter of pipe 1, in meters;

[0152] v — Seawater flow velocity, m / s.

[0153] In this first embodiment:

[0154] kg / h

[0155] That is, the output of the electrolytic chlorine production device 3 in this embodiment is 97 kg / h.

[0156] (2) As the seawater flows, the concentration of sodium hypochlorite in the seawater gradually decreases. When it reaches point 1, it is already 4.5 km away from the water intake head 11, and the concentration of sodium hypochlorite has dropped to a level that cannot guarantee the inhibition of seawater fouling (0.5 ppm). The in-situ electrolysis device 2 installed at point 1 produces a corresponding amount of sodium hypochlorite according to the flow rate of the seawater in the pipeline, increasing the concentration of sodium hypochlorite in the seawater in the pipeline to about 3.3 ppm.

[0157] The design output of the in-situ electrolysis device 2 installed at point 1 is calculated according to formula (3):

[0158] (3)

[0159] In the formula:

[0160] G1—Available chlorine requirement at point #1, kg / h;

[0161] C 11 —The designed chlorine concentration after adding chlorine at point 1, mg / L (3.325 ppm in this example);

[0162] C 10 —Chlorine concentration before chlorination at point 1, mg / L (0.685 ppm in this example);

[0163] Q – Seawater flow rate, m³ / h.

[0164] The designed output of the in-situ electrolysis unit 2 at point 1 of this project is:

[0165] kg / h

[0166] (3) When the seawater reaches point 2, it is already 7.5 km away from the water intake head 11. The concentration of sodium hypochlorite drops again to a level that cannot guarantee the inhibition of marine fouling (0.5 ppm). The in-situ electrolysis device 2 installed at point 2 produces a corresponding amount of sodium hypochlorite according to the flow rate of the seawater in the pipeline, so that the concentration of sodium hypochlorite in the seawater in the pipeline increases again to about 3.3 ppm. The concentration of sodium hypochlorite in the seawater in the pipeline continues to be maintained within the effective range that can inhibit marine fouling, so as to ensure that the entire transmission pipeline is not fouled by marine organisms. Subsequently, seawater in the pipeline passed sequentially through points 3, 4, and 5. The in-situ electrolysis unit 2 at points 3, 4, and 5 was designed with a capacity of 25.4 kg / h. At point 5, the in-situ electrolysis unit 2 produced a corresponding amount of sodium hypochlorite based on the flow rate of the seawater in the pipeline, increasing the sodium hypochlorite concentration in the seawater to approximately 3.3 ppm. The remaining distance is 2.5 km (<3 km), ensuring that the effective chlorine concentration at the outlet of pipeline 1 is greater than 0.5 ppm, thus protecting the pipeline from marine biofouling. The corresponding in-situ electrolysis unit was designed based on the effective chlorine requirements at each dosing point.

[0167] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content without departing from the scope of the technical solution of the present invention, which are equivalent embodiments with equivalent changes. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A seawater antifouling system for transporting seawater via pipeline electrolysis, characterized in that, The system includes a pipeline (1) and multiple in-situ electrolysis devices (2). The pipeline (1) is used to transport seawater. The pipeline (1) includes a water intake head (11) connected to a water intake channel (4). Sodium hypochlorite is introduced into the water intake head (11). Multiple in-situ electrolysis devices (2) are installed sequentially and at intervals along the length of the pipeline (1). The in-situ electrolysis devices (2) use ocean currents to generate electricity directly to electrolyze seawater to obtain sodium hypochlorite, which is then introduced into the pipeline (1). The effective chlorine concentration of sodium hypochlorite at each point in the pipeline (1) is C, where C>0.5ppm. The specific arrangement method of the multiple in-situ electrolysis devices (2) in the pipeline (1) includes: S1. Design a dynamic simulation test to obtain the decay curve and kinetic equation of the effective chlorine concentration of sodium hypochlorite in seawater as it changes with time during the flow of seawater in the pipeline (1). Obtain the slow decay segment of sodium hypochlorite concentration, which includes the highest concentration point and the lowest concentration point. Set an in-situ electrolysis device (2) at the position corresponding to the lowest concentration point so that the chlorine concentration after chlorination can reach the highest concentration point again. As the seawater flows, install another in-situ electrolysis device (2) at the position where the effective chlorine concentration reaches the lowest concentration point again. In this way, install multiple in-situ electrolysis devices (2) in the pipeline (1). The initial chlorine concentration of sodium hypochlorite added at the water intake head (11) is C0, and the highest concentration point in the slow decay section is set as the chlorine concentration C after each chlorination. 11 The lowest concentration point in the slow decay phase is set as the chlorine concentration C before each chlorination. 10 C 10 ≥0.5ppm, the decay curve shows that C0 changes to C 10 The time is T1, C 11 Change to C 10 The time is T2; S2. N in-situ electrolysis device (2) injection points are sequentially arranged in the pipeline (1) along the direction of coastal water flow. The distance between the first injection point and the water intake head (11) is calculated according to formula (i): (i) In the formula: L1—the distance between the first dosing point and the water intake head (11), in meters; v — seawater velocity, m / s; T1——C0 becomes C 10 Time, s; The distance between two subsequent adjacent dosing points is calculated using formula (ii): (ii) In the formula: L2—the distance between two adjacent injection points, in meters; v — seawater velocity, m / s; T2——C 11 Change to C 10 Time, s; The number of injection points is calculated according to formula (iii): (iii) In the formula, Take the integer part.

2. The antifouling system for seawater electrolysis in a seawater pipeline as described in claim 1, characterized in that, The in-situ electrolysis device (2) includes an impeller (21), a rotating shaft (22) and a power generation-electrolysis component (23). The impeller (21) is connected to the power generation-electrolysis component (23) through the rotating shaft (22), and the kinetic energy of the impeller (21) is transmitted to the power generation-electrolysis component (23) through the rotating shaft (22).

3. The antifouling system for seawater electrolysis pipelines as described in claim 2, characterized in that, The power generation-electrolysis component (23) includes a generator, a rectifier, and an electrolysis electrode. The generator is connected to the impeller (21) via the rotating shaft (22). The generator converts water energy into alternating current. The rectifier is used to convert alternating current into direct current. The electrolysis electrode uses direct current to electrolyze seawater into sodium hypochlorite.

4. The antifouling system for seawater electrolysis pipelines as described in claim 3, characterized in that, The electrolytic electrode has a bipolar structure. The electrodes at both ends of the electrolytic electrode are connected to the positive and negative terminals of the rectifier, respectively. One side of each electrode in the middle of the electrolytic electrode is an anode, and the other side is a cathode.

5. The antifouling system for seawater electrolysis pipelines as described in claim 3, characterized in that, The power generation-electrolysis component (23) also includes a housing (231), on which the generator, the rectifier and the electrolysis electrode are integrated and installed on the inner wall of the housing (231).

6. The antifouling system for seawater electrolysis in a seawater pipeline as described in claim 5, characterized in that, The shell (231) is provided with a mesh structure at both ends in the direction of water flow.

7. The antifouling system for seawater electrolysis pipelines as described in claim 1, characterized in that, The system also includes an electrolytic chlorine generator (3), and the sodium hypochlorite prepared by the electrolytic chlorine generator (3) is fed into the water intake head (11).

8. The antifouling system for seawater electrolysis in a seawater pipeline as described in claim 1, characterized in that, The calculation method for the initial available chlorine requirement of sodium hypochlorite added at the water intake head (11) includes: The initial amount of available chlorine added is calculated according to formula (1): (1) In the formula: G0 – Initial available chlorine requirement, kg / h; C0—Design initial chlorine dosage concentration, mg / L; Q – Seawater flow rate, m³ / h; The seawater flow rate is calculated according to formula (2): (2) In the formula: Q – Seawater flow rate, m³ / h; D——Inner diameter of pipe (1), m; v — Seawater flow velocity, m / s.

9. The antifouling system for seawater electrolysis pipelines as described in claim 8, characterized in that, The calculation method for the effective chlorine requirement at the first dosing point includes: The amount of available chlorine added at the first dosing point is calculated according to formula (3): (3) In the formula: G1 – Available chlorine requirement at the first dosing point, kg / h; C 11 —The chlorine concentration after chlorination at the first dosing point, in mg / L; C 10 —Chlorine concentration before chlorination at the first dosing point, mg / L; Q – Seawater flow rate, m³ / h; Within pipeline (1), the effective chlorine requirement at the second dosing point is G2, the effective chlorine requirement at the third dosing point is G3, ..., the effective chlorine requirement at the Nth dosing point is G... N G1=G2=G3=......=G N .

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