Seawater electrolysis antifouling system for seawater conveying pipeline

Abstract

The invention discloses a seawater conveying pipeline seawater electrolysis antifouling system, which comprises a pipeline and a plurality of in-situ electrolysis devices, the pipeline is used for conveying seawater, the pipeline comprises a water taking head part connected with a diversion canal, and sodium hypochlorite is put into the water taking head part; the multiple in-situ electrolysis devices are sequentially installed in the pipeline at intervals in the length direction of the pipeline, the in-situ electrolysis devices utilize ocean current to directly generate power to provide energy to electrolyze seawater to obtain sodium hypochlorite, then the sodium hypochlorite is put into the pipeline, and the effective chlorine concentrations of the sodium hypochlorite at all positions in the pipeline are C and Cgt; and the concentration is 0.5 ppm. The problem that sodium hypochlorite is inconvenient to add at multiple positions in a pipeline at present is solved, and the accuracy and convenience of the concentration of added sodium hypochlorite are improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrolyzed seawater anti-fouling, and in particular to an electrolyzed seawater anti-fouling system for a seawater transport pipeline. Background Art

[0002] The existing long-distance seawater pipeline anti-fouling measures mainly include adding sodium hypochlorite fungicide. Due to the long distance of the pipeline, it is often necessary to add fungicides in multiple sections. Whether it is sodium hypochlorite prepared by electrolysis of seawater or finished sodium hypochlorite, multi-point long-distance addition is very inconvenient. Because the addition point needs to be equipped with a power supply or addition pipeline, and it is difficult for the middle area of ​​the long-distance pipeline to have such conditions. The system for electrolyzing seawater to produce sodium hypochlorite has many equipment and consumes a lot of electricity, and requires a special plant for layout and installation. For addition points far away from the electrolytic chlorine production plant, the corresponding addition pipelines need to be laid, and each addition point requires at least one addition pump, so it is not suitable for long-distance addition or multi-point addition. Summary of the invention

[0003] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a seawater electrolysis anti-fouling system for transporting seawater pipelines, solve the inconvenience of adding sodium hypochlorite at multiple locations in the existing pipeline, and improve the accuracy and convenience of adding sodium hypochlorite concentration.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] The present invention provides a seawater electrolysis anti-fouling system for conveying seawater, comprising a pipeline and a plurality of in-situ electrolysis devices, wherein the pipeline is used to convey seawater, the pipeline comprises a water intake head connected to a water diversion channel, and sodium hypochlorite is put into the water intake head; the plurality of in-situ electrolysis devices are sequentially installed in the pipeline at intervals along the length direction of the pipeline, the in-situ electrolysis devices utilize ocean currents to directly generate electricity to provide energy to electrolyze seawater to obtain sodium hypochlorite, which is then put into the pipeline, and the effective chlorine concentration of the sodium hypochlorite at various locations in the pipeline is C, and C>0.5ppm.

[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. The rectifier is used to convert alternating current into direct current. The electrolysis electrode uses direct current to electrolyze seawater into sodium hypochlorite.

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

[0009] In one embodiment, the power generation and electrolysis component further comprises a shell, and the generator, the rectifier and the electrolysis electrode are integrally mounted on the inner wall of the shell.

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

[0011] In one embodiment, the system further comprises an electrolytic chlorine production device, and the sodium hypochlorite produced by the electrolytic chlorine production device is input into the water intake head.

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

[0013] S1. Design a dynamic simulation test to obtain the attenuation curve and kinetic equation of the effective chlorine concentration of sodium hypochlorite in seawater changing with time during the flow of seawater in the pipeline, and obtain a slow decay section of the sodium hypochlorite concentration, wherein the slow decay section includes a maximum concentration point and a minimum concentration point, and an in-situ electrolysis device is arranged at a position corresponding to the minimum concentration point, so that the chlorine concentration after chlorination can reach the maximum concentration point again, and as the seawater flows, another in-situ electrolysis device is installed at a position where the effective chlorine concentration reaches the minimum concentration point again, and thus a plurality of the in-situ electrolysis devices are installed 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 section is set as the chlorine concentration C before each chlorination. 10 , C 10 ≥0.5ppm, from the decay curve, C0 becomes C 10 The time is T1, C 11 Change to C 10 The time is T2;

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

[0016] L1=ν×T1 (i)

[0017] Where:

[0018] L1 - the distance between the first dosing point and the water intake head, m;

[0019] v——seawater velocity, m / s;

[0020] T1——C0 becomes C 10 time, s;

[0021] The distance between two subsequent adjacent injection points is calculated according to formula (ii):

[0022] L2=ν×T2 (ii)

[0023] Where:

[0024] L1——the distance between two adjacent dosing points, m;

[0025] v——seawater velocity, m / s;

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

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

[0028]

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

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

[0031] The initial effective chlorine addition amount is calculated according to formula (1):

[0032]

[0033] Where:

[0034] G0——initial effective chlorine requirement, kg / h;

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

[0036] Q——seawater flow, m 3 / h;

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

[0038]

[0039] Where:

[0040] Q——seawater flow, m 3 / h;

[0041] D——inner diameter of the pipe, m;

[0042] v——seawater velocity, m / s.

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

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

[0045]

[0046] Where:

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

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

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

[0050] Q——seawater flow, m 3 / h;

[0051] Among them, in the pipeline, the effective chlorine requirement of the second dosing point is G2, the effective chlorine requirement of the third dosing point is G3... The effective chlorine requirement of the Nth dosing point is G N , G1=G2=G3=......=G N .

[0052] The beneficial effects of the present invention are as follows: a plurality of in-situ electrolysis devices are dispersedly installed at the positions of the dosing points where chlorine addition is required, and when seawater flows through the device, the sea current is used to directly generate electricity to provide energy to electrolyze the seawater to produce sodium hypochlorite, and the sodium hypochlorite is transferred downstream along with the diffusion of the water flow, thereby solving the problems of the existing dosing pipelines and dosing pumps provided at multiple dosing points, which leads to complex engineering and inconvenient multi-point long-distance dosing, and improving the convenience of adding sodium hypochlorite in the pipeline; and because the amount of sodium hypochlorite produced is proportional to the flow rate of seawater, and the flow rate of seawater is also proportional to the flow rate of seawater, therefore, the greater the flow rate of seawater, the more sodium hypochlorite is produced, and the sodium hypochlorite produced is reduced as the flow rate of seawater decreases, thereby maintaining the stability of the sodium hypochlorite concentration in the seawater. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

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

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

[0056] Figure 3 Schematic diagram of the anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to Embodiment 1;

[0057] Figure 4 This is a concentration attenuation curve of available chlorine in seawater in Example 1.

[0058] In the figure: 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 chlorine production device; 4. water diversion channel; 5. ship-blocking net; 1#, the first dosing point; 2#, the second dosing point; 3#, the third dosing point; 4#, the fourth dosing point; 5#, the fifth dosing point. DETAILED DESCRIPTION

[0059] The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the description of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] In the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "install", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0061] The directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front”, “back”, “top”, “bottom”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of description and simplified description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0062] The terms "first", "second", "third" and the like are merely used to distinguish elements of similar nature, and do not indicate or imply relative importance or a particular order.

[0063] The terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of the elements listed and may also include additional elements not expressly listed.

[0064] The existing long-distance seawater transportation pipeline 1 adopts the anti-marine biofouling measure mainly by adding sodium hypochlorite bactericide. Due to the long distance of the transportation pipeline 1, it is often necessary to add the bactericide in multiple points and sections. Whether it is sodium hypochlorite prepared by electrolyzing seawater or finished sodium hypochlorite, the multi-point long-distance addition method is very inconvenient. Because the addition point needs to be equipped with a power supply or an addition pipeline, and it is difficult for the middle area of ​​the long-distance transportation pipeline 1 to have such conditions. Figures 1 to 3 As shown, the present invention provides a seawater electrolysis anti-fouling system for conveying seawater pipeline, comprising a pipeline 1 and a plurality of in-situ electrolysis devices 2, wherein the pipeline 1 is used to convey seawater, the pipeline 1 comprises a water intake head 11 connected to a water diversion channel 4, and sodium hypochlorite is fed into the water intake head 11; a ship interception net 5 is provided at the water diversion channel 4 to prevent ships from entering by mistake; a plurality of in-situ electrolysis devices 2 are sequentially installed in the pipeline 1 at intervals along the length direction of the pipeline 1, the in-situ electrolysis devices 2 utilize ocean currents to directly generate electricity to provide energy to electrolyze seawater to obtain sodium hypochlorite, which is then fed into the pipeline 1, and the effective chlorine concentration of the sodium hypochlorite at various locations in the pipeline 1 is C, and C>0.5ppm.

[0065] In this embodiment, after sodium hypochlorite is added to the water intake head 11 of the pipeline 1, as the seawater flows along the pipeline 1, after a distance from the water intake head 11, the effective chlorine concentration in the seawater decreases and it is difficult to achieve the sterilization effect, and sodium hypochlorite needs to be added again. The in-situ electrolysis device 2 is dispersedly installed at the addition point where chlorine needs to be added. When the seawater flows through the device, the sea current is used to directly generate electricity to provide energy to electrolyze the seawater to produce sodium hypochlorite, and the sodium hypochlorite is transferred downstream with the diffusion of the water flow, which solves the existing problem of complex engineering and inconvenient multi-point long-distance addition method by setting addition pipelines and addition pumps at multiple addition points, and improves the convenience of adding sodium hypochlorite in the pipeline 1; and because the amount of sodium hypochlorite produced is proportional to the flow rate of seawater, and the flow rate of seawater is also proportional to the flow rate of seawater, therefore, the greater the flow rate of seawater, the more sodium hypochlorite is produced, and the sodium hypochlorite produced is also reduced when the flow rate of seawater decreases, thereby maintaining the stability of the sodium hypochlorite concentration in the seawater; the present invention realizes providing an effective and reliable anti-marine biological fouling measure for the seawater delivery pipeline 1. Among them, the effective chlorine concentration of sodium hypochlorite at various locations in the pipeline 1 is C, C>0.5ppm, which can ensure that within the effective concentration range of sodium hypochlorite, biological fouling of the seawater transportation pipeline 1 can be effectively prevented, and the problem of incomplete sterilization caused by too low sodium hypochlorite concentration can be avoided.

[0066] As an implementation method, 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 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. In this embodiment, the flow of seawater drives the impeller 21 to rotate, thereby driving the rotating shaft 22 to rotate, and transmitting the kinetic energy to the power generation-electrolysis component 23. After the power generation-electrolysis component 23 converts the kinetic energy of seawater into electrical energy, the electrical energy is used to electrolyze the seawater to produce sodium hypochlorite and put it into the seawater in the pipeline 1. As the seawater flows, the sodium hypochlorite is driven to flow downstream to ensure the concentration of sodium hypochlorite at various locations in the pipeline 1.

[0067] As an implementation method, Figure 2 As shown, the power generation-electrolysis component 23 includes a generator (not shown), a rectifier (not shown) and an electrolysis electrode (not shown). The generator is connected to the impeller 21 through a 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. Specifically, the seawater in the pipeline 1 flows in a directional manner, driving the impeller 21 on the in-situ electrolysis device 2 to rotate, and the rotation of the impeller 21 drives the generator to generate electricity. The rectifier rectifies the generated electricity and supplies it to the electrolysis electrode. After the seawater flows through the electrode, sodium hypochlorite is generated and transferred downstream with the diffusion of the water flow to ensure that the sodium hypochlorite concentration in the seawater in the subsequent section of the pipeline 1 is within an effective range to prevent marine biofouling.

[0068] The generator includes 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 generates alternating current, which is converted into direct current through a rectifier to power the electrolysis electrodes. The structure of the rectifier includes a bridge circuit composed of multiple diodes. In each half cycle of the alternating current, only one diode is turned on, so that unidirectional direct current is obtained at the output end. The rectifier not only converts the alternating current into direct current, but also includes a filtering circuit to reduce the ripple of the output voltage and make the output smoother.

[0069] As an implementation method, the electrolysis electrode is a bipolar structure, the electrodes at both ends of the electrolysis electrode are respectively connected to the positive and negative electrodes of the rectifier, and one side of each middle electrode of the electrolysis electrode is an anode and the other side is a cathode.

[0070] As an implementation method, Figure 2 As shown, the power generation-electrolysis component 23 further includes a housing 231, and the generator, rectifier and electrolysis electrode are integrated and installed on the inner wall of the housing 231. The housing 231 is made of glass fiber reinforced plastic.

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

[0072] As an implementation method, Figure 3 As shown, the system also includes an electrolytic chlorine-making device 3, and the sodium hypochlorite prepared by the electrolytic chlorine-making device 3 is put into the water intake head 11. The electrolytic chlorine-making device 3 is arranged near the water intake head 11, and the electrolytic chlorine-making device 3 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 through the dosing pipeline by the dosing pump. Of course, the sodium hypochlorite storage tank can also be directly installed at the water intake head 11, and the sodium hypochlorite in the tank body can be directly pumped into the water intake head 11 of the pipeline by a pump.

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

[0074] S1. Design a dynamic simulation test to obtain the attenuation curve and kinetic equation of the effective chlorine concentration of sodium hypochlorite in seawater changing with time during the flow of seawater in the pipeline 1, and obtain the slow attenuation section of the sodium hypochlorite concentration, which includes the highest concentration point and the lowest concentration point. An in-situ electrolysis device 2 is set 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, another in-situ electrolysis device 2 is installed at the position where the effective chlorine concentration reaches the lowest concentration point again. In this way, multiple in-situ electrolysis devices 2 are installed in the pipeline 1;

[0075] 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, from the decay curve, C0 becomes C 10 The time is T1, C 11 Change to C 10 The time is T2;

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

[0077] L1=ν×T1 (i)

[0078] Where:

[0079] L1 - the distance between the first dosing point and the water intake head 11, m;

[0080] v——seawater velocity, m / s;

[0081] T1——C0 becomes C 10 time, s;

[0082] The distance between two subsequent adjacent injection points is calculated according to formula (ii):

[0083] L2=ν×T2 (ii)

[0084] Where:

[0085] L1——the distance between two adjacent dosing points, m;

[0086] v——seawater velocity, m / s;

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

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

[0089]

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

[0091] In this embodiment, if Figure 3 and Figure 4 As shown, a dynamic simulation test is designed. After sodium hypochlorite is added at the water intake head 11 of the pipeline 1, the C0 concentration is measured. Samples are taken at the corresponding positions downstream of the pipeline 1 at different time points to measure the concentration of effective chlorine of sodium hypochlorite in seawater at the position. For example, it is set to take samples every 0.5h, the first sampling position S1 = v*0.5, the second sampling position S2 = v*1, S3 = v*1.5, ..., v is the seawater flow rate, S1~Sn is the distance between the sampling point and the water intake head 11. Among them, the concentration of effective chlorine of sodium hypochlorite in seawater can be measured by an online chloride ion detector. A curve is drawn for the change of the concentration of effective chlorine over time, that is, the attenuation curve and kinetic equation of the change of the concentration of effective chlorine of sodium hypochlorite in the pipeline 1 over time are obtained. The decay curve is analyzed to find the slow decay section, that is, within this concentration range, the effective chlorine concentration changes the least over time and the line is gentle; keeping the effective chlorine concentration in pipeline 1 within this range can ensure that sodium chlorate inhibits fouling organisms, and at the same time can control the addition of sodium hypochlorite to the minimum, with good economic benefits. Therefore, the highest point of the slow decay section is 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, each time the effective chlorine concentration is C 10When the chlorine concentration is C0, an in-situ electrolysis device 2 is set at the corresponding position. 10 The time T1, then the distance between the first dosing point and the water intake head 11 is L1 = ν × T1, and the in-situ electrolysis device 2 is installed at this position, so that the chlorine concentration after chlorination becomes C again. 11 , the concentration change curve of the slow decay section appears again downstream of the first dosing point, and when the effective chlorine concentration becomes C 10 The position is the second dosing point, and an in-situ electrolysis device 2 is installed; thus, multiple in-situ electrolysis devices 2 are arranged and installed to ensure that the effective chlorine concentration at the outlet of the pipeline 1 is greater than 0.5ppm.

[0092] Furthermore, the calculation method of the initial effective chlorine requirement of sodium hypochlorite added at the water intake head 11 includes:

[0093] The initial effective chlorine addition amount is calculated according to formula (3):

[0094]

[0095] Where:

[0096] G0——initial effective chlorine requirement, kg / h;

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

[0098] Q——seawater flow, m 3 / h;

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

[0100]

[0101] Where:

[0102] Q——seawater flow, m 3 / h;

[0103] D——inner diameter of pipe 1, m;

[0104] v——seawater velocity, m / s.

[0105] Furthermore, the calculation method of the effective chlorine requirement of the first dosing point includes:

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

[0107]

[0108] Where:

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

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

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

[0112] Q——seawater flow, m 3 / h;

[0113] Among them, in pipeline 1, the effective chlorine requirement of the second dosing point is G2, the effective chlorine requirement of the third dosing point is G3... The effective chlorine requirement of the Nth dosing point is G N , G1=G2=G3=......=G N .

[0114] The present invention is further described below in conjunction with specific embodiments to increase the feasibility of the present invention.

[0115] Embodiment 1

[0116] In a certain project, seawater enters the water intake head 11 through the water diversion channel 4. The length of the pipeline is 19km, the inner diameter of the pipeline 1 is 2m, and the water flow rate is 0.85m / s. A dynamic simulation test is conducted to study and determine a suitable and effective prevention and control plan. The dynamic simulation test data are 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 decayed to 1.415 mg / L in 1 hour and decayed to 0 mg / L in 2 hours. The test water temperature was 24.8℃.

[0118] When the present invention is used for marine biological control, the attenuation curve and kinetic equation of sodium hypochlorite in seawater are determined based on dynamic simulation tests. Then, a comprehensive analysis is performed to determine the number of dosing points. To ensure that sodium hypochlorite inhibits the attachment of fouling organisms, the concentration of effective chlorine in seawater should be greater than 0.5 ppm.

[0119] from Figure 4 It can be seen from the curve in that when the initial dosing concentration is 10ppm, after 1.5 hours, the concentration of effective chlorine drops to about 0.5ppm. It can be seen from the curve in the figure that when the effective chlorine concentration is 3.325ppm, the chlorine decays slowly, so it is more economical to control the effective chlorine concentration at 3.325ppm at the middle dosing point. That is, the initial chlorine dosing concentration of sodium hypochlorite added at the water intake head 11 is C0, which is 10ppm, and the highest concentration point in the slow decay section is set as the chlorine concentration C after each chlorination. 11 The lowest concentration in the slow decay phase is set as the chlorine concentration C before each chlorination.10 , C 10 It should be selected as 0.5ppm, but in actual experiments, for the convenience of calculation, C 10 The decay time corresponding to 0.685ppm is 1h, which can simplify the calculation process. From the decay curve, we can get C0 to C 10 The time T1 is 1.5h, C 11 Change to C 10 The time T2 is 1h, that is, the time for decaying from 3.325ppm to 0.5ppm is about 1 hour.

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

[0121] L1=ν×T1 (i)

[0122] Where:

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

[0124] v——seawater velocity, m / s;

[0125] T1——C0 becomes C 10 time, s;

[0126] In the first embodiment, L1 = 0.85 × 1.5 × 3600 = 4590 m ≈ 4.5 km

[0127] The distance between two subsequent adjacent injection points is calculated according to formula (ii):

[0128] L2=ν×T2 (ii)

[0129] Where:

[0130] L1——the distance between two adjacent dosing points, m;

[0131] v——seawater velocity, m / s;

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

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

[0134]

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

[0136] In the first embodiment, L2 = ν × T2 = 0.85 × 1 × 3600 = 3060 m ≈ 3 km, that is, the distance between two subsequent adjacent dosing points is 3 km; the total dosing points That is, in the first embodiment, five in-situ electrolysis devices 2 are required to be installed at five dosing points respectively. The specific data of each dosing point are shown in Table 1.

[0137] Table 1: Location arrangement record table of each dosing point in embodiment 1

[0138] Dosing point location Time Flow rate m / S Distance km Total distance km First dosing point 1# 1.5 0.85 4.5 4.5 Second dosing point 2# 1 0.85 3 7.5 The third dosing point 3# 1 0.85 3 10.5 The fourth dosing point 4# 1 0.85 3 13.5 The fifth dosing point 5# 1 0.85 3 16.5

[0139] Therefore, the plan for this project is:

[0140] (1) The electrolytic chlorine production device 3 is arranged near the water intake head 11. The electrolytic chlorine production 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 pipeline by the dosing pump. The chlorine concentration at the water intake head 11 is 10ppm. The chlorine concentration of 10ppm can not only ensure that the facilities in contact with seawater are not damaged by chlorine, but also fully inhibit the growth of fouling organisms, and also has a killing effect on some fouling organisms, and can also reduce the number of subsequent dosing points.

[0141] The effective chlorine requirement is calculated according to formula (1):

[0142]

[0143] Where:

[0144] G0——initial effective chlorine requirement, kg / h;

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

[0146] Q——seawater flow, m 3 / h.

[0147] The seawater flow is calculated according to formula (2):

[0148]

[0149] Where:

[0150] Q——seawater flow, m 3 / h;

[0151] D——inner diameter of pipe 1, m;

[0152] v——seawater velocity, m / s.

[0153] In this first embodiment:

[0154] G0=C0×Q=10×2862×2 2 ×0.85÷1000=97kg / h

[0155] That is, the output of the electrolytic chlorine production device 3 of the first 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 suppression of seawater pollution (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, so that the concentration of sodium hypochlorite in the seawater in the pipeline increases 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]

[0159] Where:

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

[0161] C 11 ——The designed chlorine concentration after chlorination at point 1#, mg / L (3.325ppm in the first embodiment);

[0162] C 10 ——Chlorine concentration before adding chlorine at point 1#, mg / L (0.685ppm in the first embodiment);

[0163] Q——seawater flow, m 3 / h.

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

[0165]

[0166] (3) When the seawater flows to point 2#, it is already 7.5 km away from the water intake head 11, and the concentration of sodium hypochlorite drops again to a level that cannot guarantee the inhibition of seawater biofouling (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 sodium hypochlorite concentration of the seawater in the pipeline is increased to about 3.3 ppm again, and the sodium hypochlorite concentration of the seawater in the pipeline is continued to be maintained within the effective range that can inhibit marine biofouling, so as to ensure that the entire transmission pipeline is not fouled by marine organisms. After that, the seawater in the pipeline passes through point 3#, point 4#, and point 5# in turn. The design output of the in-situ electrolysis device 2 at point 3#, point 4#, and point 5# is 25.4kg / h. The in-situ electrolysis device 2 at point 5# produces a corresponding output of sodium hypochlorite according to the flow rate of the seawater in the pipeline, so that the sodium hypochlorite concentration of the seawater in the pipeline is increased to about 3.3ppm again. After that, the remaining distance is 2.5 kilometers (<3 kilometers), which can ensure that the concentration of effective chlorine at the outlet of pipeline 1 is greater than 0.5ppm, which plays a role in protecting the pipeline from marine biological fouling. Among them, the corresponding in-situ electrolysis device is designed according to the effective chlorine requirement of each addition point.

[0167] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to the technical contents disclosed above without departing from the scope of the technical solution of the present invention, which are equivalent embodiments of equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A seawater electrolysis anti-fouling system for transporting seawater pipelines, characterized in that: The invention comprises a pipeline (1) and a plurality of in-situ electrolysis devices (2), wherein the pipeline (1) is used to transport seawater, the pipeline (1) comprises a water intake head (11) connected to a water diversion channel (4), and sodium hypochlorite is added to the water intake head (11); the plurality of in-situ electrolysis devices (2) are sequentially installed in the pipeline (1) at intervals along the length direction of the pipeline (1), the in-situ electrolysis devices (2) utilize ocean currents to directly generate electricity to provide energy to electrolyze seawater to obtain sodium hypochlorite, which is then added to the pipeline (1), and the effective chlorine concentration of the sodium hypochlorite at each location in the pipeline (1) is C, and C>0.5ppm.

2. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 1, characterized in that: The in-situ electrolysis device (2) comprises 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 transmitted to the power generation-electrolysis component (23) via the rotating shaft (22).

3. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 2, characterized in that: The power generation-electrolysis component (23) comprises 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 the alternating current into direct current. The electrolysis electrode uses the direct current to electrolyze seawater into sodium hypochlorite.

4. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 3, characterized in that: The electrolysis electrode is a bipolar structure, the electrodes at both ends of the electrolysis electrode are respectively connected to the positive and negative electrodes of the rectifier, and one side of each middle electrode of the electrolysis electrode is an anode and the other side is a cathode.

5. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 3, characterized in that: The power generation-electrolysis component (23) further comprises a shell (231), and the generator, the rectifier and the electrolysis electrode are integrally mounted on the inner wall of the shell (231).

6. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 5, characterized in that: The shell (231) is configured as a mesh structure at both ends along the direction of coastal water flow.

7. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 1, characterized in that: The system also includes an electrolytic chlorine production device (3), and the sodium hypochlorite produced by the electrolytic chlorine production device (3) is fed into the water intake head (11).

8. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 1, characterized in that: The method for arranging the plurality of in-situ electrolysis devices (2) in the pipeline (1) specifically comprises: S1. Design a dynamic simulation test to obtain the attenuation curve and kinetic equation of the effective chlorine concentration of sodium hypochlorite in seawater changing with time during the flow of seawater in the pipeline (1), and obtain a slow attenuation section of the sodium hypochlorite concentration, wherein the slow attenuation section includes a maximum concentration point and a minimum concentration point, and an in-situ electrolysis device (2) is arranged at a position corresponding to the minimum concentration point so that the chlorine concentration after chlorination can reach the maximum concentration point again. As the seawater flows, another in-situ electrolysis device (2) is installed at a position where the effective chlorine concentration reaches the minimum concentration point again, and a plurality of the in-situ electrolysis devices (2) are installed 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 section is set as the chlorine concentration C before each chlorination. 10 , C 10 ≥0.5ppm, from the decay curve, C0 becomes C 10 The time is T1, C 11 Change to C 10 The time is T2; S2. N dosing points of the in-situ electrolysis device (2) are arranged in sequence along the flow direction of coastal water in the pipeline (1). The distance between the first dosing point and the water intake head (11) is calculated according to formula (i): L1=ν×T1 (i) Where: L1 - the distance between the first dosing point and the water intake head (11), m; v——seawater velocity, m / s; T1——C0 becomes C 10 time, s; The distance between two subsequent adjacent injection points is calculated according to formula (ii): L2=ν×T2 (ii) Where: L1——the distance between two adjacent injection points, m; v——seawater velocity, m / s; T2——C 11 Change to C 10 time, s; The number of dosing points is calculated according to formula (iii): In the formula, Take the integer part.

9. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 8, characterized in that: The method for calculating the initial effective chlorine requirement of sodium hypochlorite added at the water intake head (11) includes: The initial effective chlorine addition amount is calculated according to formula (1): Where: G0——initial effective chlorine requirement, kg / h; C0——designed initial chlorine dosage concentration, mg / L; Q——seawater flow, m 3 / h; The seawater flow is calculated according to formula (2): Where: Q——seawater flow, m 3 / h; D——inner diameter of the pipeline (1), m; v——seawater velocity, m / s.

10. The anti-fouling system for electrolyzing seawater in a seawater transport pipeline according to claim 9, characterized in that: The calculation method for the effective chlorine requirement at the first dosing point includes: The effective chlorine addition amount at the first dosing point is calculated according to formula (3): Where: G1——effective chlorine requirement at the first dosing point, kg / h; C 11 ——The designed chlorine concentration after chlorination at the first dosing point, mg / L; C 10 ——Chlorine concentration before chlorination at the first dosing point, mg / L; Q——seawater flow, m 3 / h; Among them, in pipeline (1), the effective chlorine requirement of the second dosing point is G2, the effective chlorine requirement of the third dosing point is G3... The effective chlorine requirement of the Nth dosing point is G N , G1=G2=G3=......=G N .

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