Reverse osmosis device and seawater desalination system

Abstract

The invention discloses a reverse osmosis device which at least comprises a filter element, the filter element comprises a reverse osmosis main body, and the reverse osmosis main body comprises a membrane shell, a first reverse osmosis assembly and a second reverse osmosis assembly, the first reverse osmosis assembly comprises a first-stage reverse osmosis water collecting pipe and a first-stage reverse osmosis membrane wound on the periphery of the first-stage reverse osmosis water collecting pipe, the second reverse osmosis assembly comprises a second-stage reverse osmosis water collecting pipe and a second-stage reverse osmosis membrane wound on the periphery of the second-stage reverse osmosis water collecting pipe, and the second reverse osmosis assembly is embedded in the first-stage reverse osmosis water collecting pipe; an inlet of the first-stage reverse osmosis membrane is connected with incoming water, and an outlet of the second-stage reverse osmosis water collecting pipe is used for discharging purified water. The reverse osmosis device is simple in structure, compact in layout and small in occupied area. The invention also discloses a seawater desalination system.

Description

Technical Field

[0001] The invention relates to the technical field of seawater desalination, and in particular to a reverse osmosis device and a seawater desalination system. Background Art

[0002] As an open-source incremental technology for freshwater resources, seawater desalination has a water supply guarantee rate and water quality that are not affected by geographical location, environmental conditions, climate conditions, and social factors. In addition, as the seawater desalination process becomes more mature and its cost decreases, its application scope is becoming wider and wider. In particular, as the membrane production process becomes more mature, its scope of use continues to expand, which also promotes the maturity of membrane desalination technology. In addition, the market's demand for high-quality water sources is also a major driving force for the vigorous development of membrane desalination around the world. Among them, in membrane desalination, a structure in which multi-stage reverse osmosis membrane components are connected in series is generally adopted, which has the problems of complex structure and large footprint. 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 reverse osmosis device and a seawater desalination system, which solves the problems of complex structure and large floor space of the reverse osmosis device.

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

[0005] A reverse osmosis device comprises at least one filter element, wherein the filter element comprises a reverse osmosis body, the reverse osmosis body comprises a membrane shell and a first reverse osmosis component and a second reverse osmosis component installed in the membrane shell, the first reverse osmosis component comprises a primary reverse osmosis water collecting pipe and a primary reverse osmosis membrane wound around its outer circumference, the second reverse osmosis component comprises a secondary reverse osmosis water collecting pipe and a secondary reverse osmosis membrane wound around its outer circumference, the second reverse osmosis component is embedded in the primary reverse osmosis water collecting pipe, the inlet of the primary reverse osmosis membrane is connected to incoming water, and the outlet of the secondary reverse osmosis water collecting pipe discharges clean water.

[0006] Furthermore, the filter element also includes a pre-scale inhibition portion arranged at the water inlet end of the membrane shell; the pre-scale inhibition portion includes a scale inhibition body, and the two ends of the scale inhibition body are respectively provided with a first grid member and a second grid member, the second grid member is connected to at least the first-level reverse osmosis membrane, and at least one barrier grid member is provided in the scale inhibition body; the grid density of the first grid member is greater than the grid density of the barrier grid member and the second grid member.

[0007] Furthermore, the filter element also includes a post-mineralization part arranged at the water outlet end of the membrane shell, and a mineralization ejector connected to the secondary reverse osmosis water collecting pipe is arranged in the post-mineralization part.

[0008] Furthermore, the mineralized ejector is an umbrella-shaped structure with a cavity, and a plurality of ejection holes are provided on the mineralized ejector, and the aperture of the ejection holes is smaller than the aperture of the secondary reverse osmosis water collecting pipe.

[0009] Furthermore, the number of the filter elements is n, 2≤n≤8; the plurality of filter elements are connected in series in sequence, and the primary reverse osmosis membrane, the secondary reverse osmosis membrane and the secondary reverse osmosis water collecting pipe of adjacent filter elements are all connected one by one.

[0010] The present invention also provides a seawater desalination system, comprising a seawater desalination module, wherein the seawater desalination module comprises a pretreatment unit, a fine filtration unit and a reverse osmosis unit connected in sequence, and the reverse osmosis unit comprises the reverse osmosis device as described above.

[0011] Furthermore, the seawater desalination system also includes a chlorine production module for electrolyzing seawater to prepare a sodium hypochlorite solution; a water outlet of the chlorine production module is connected to a water inlet of the seawater desalination module.

[0012] Furthermore, the seawater desalination system also includes a seawater inlet pump; the seawater inlet pump is connected to the water inlet end of the chlorine production module and the water inlet end of the seawater desalination module, the chlorine production module includes a sodium hypochlorite storage tank, the water outlet end of the chlorine production module is connected to the water inlet end of the sodium hypochlorite storage tank, and the water outlet end of the sodium hypochlorite storage tank is connected to the water inlet end of the seawater desalination module through a dosing pipe to add sodium hypochlorite solution to the water inlet end of the seawater desalination module; or, the seawater inlet pump is connected to the water inlet end of the chlorine production module, and the water outlet end of the chlorine production module is directly connected to the water inlet end of the seawater desalination module to input seawater into the water inlet end of the seawater desalination module.

[0013] Furthermore, the pretreatment unit comprises a pretreatment filter and a reducing agent adding point, the water inlet end of the pretreatment filter is connected to the seawater to be desalinated, and the reducing agent adding point is arranged between the pretreatment filter and the fine filtration unit.

[0014] Furthermore, the reverse osmosis unit also includes a reverse osmosis water supply pump, a reverse osmosis safety filter and a high-pressure pump connected in sequence, the water inlet end of the reverse osmosis water supply pump is connected to the water outlet end of the fine filtration unit, and the water outlet end of the high-pressure pump is connected to the water inlet end of the reverse osmosis device.

[0015] The beneficial effects of the present invention are as follows: the first reverse osmosis component and the second reverse osmosis component are integrated in a membrane shell, and the second reverse osmosis component is embedded in the first-level reverse osmosis water collecting pipe of the first reverse osmosis component. Seawater enters the filter element through the inlet of the first-level reverse osmosis membrane, and the seawater enters the second-level reverse osmosis membrane through the first-level reverse osmosis water collecting pipe after being filtered through the first-level reverse osmosis membrane, and finally is discharged from the filter element through the outlet of the second-level reverse osmosis water collecting pipe, thereby realizing two-stage reverse osmosis filtration of seawater, more effectively removing various impurities in seawater, and solving the problem that the original multiple reverse osmosis membrane components are separately arranged, the structure is complex, and the occupation area is large. The present device has a simple structure and a compact and reasonable layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 is a schematic structural diagram of a first filter element of a reverse osmosis device according to an embodiment of the present invention;

[0018] Figure 2 yes Figure 1 A side view of the pre-scale inhibitor in FIG.

[0019] Figure 3 yes Figure 1 Side view of the rear mineralized part in the figure;

[0020] Figure 4 yes Figure 1 Schematic diagram of the decomposition of

[0021] Figure 5 yes Figure 4 Schematic diagram of the structure of the mineralized ejector;

[0022] Figure 6 is a schematic structural diagram of the 2-nth filter element of the reverse osmosis device according to one embodiment of the present invention;

[0023] Figure 7 yes Figure 6 Side view of the rear mineralized part in the figure;

[0024] Figure 8 yes Figure 6 Schematic diagram of the decomposition of

[0025] Fig. 9 is a schematic structural diagram of a first filter element of a reverse osmosis device according to another embodiment of the present invention;

[0026] Fig.10 is a schematic structural diagram of the 2-nth filter element of the reverse osmosis device of another embodiment of the present invention;

[0027] Fig.11 It is a schematic diagram of the structure of the reverse osmosis device of the present invention having two filter elements connected;

[0028] Fig.12 is a process flow chart of a seawater desalination system according to an embodiment of the present invention;

[0029] Fig.13 is a process flow chart of a seawater desalination system according to another embodiment of the present invention;

[0030] Fig.14 It is a process flow diagram of the connection between the seawater inlet pump and the seawater desalination module;

[0031] Fig.15 It is a process flow diagram of the connection between the seawater inlet pump and the chlorine production module.

[0032] In the figure:

[0033] A. Seawater inlet pump;

[0034] B. Seawater desalination module; B1. Seawater desalination unit;

[0035] 10. Pretreatment unit; 11. Pretreatment filter;

[0036] 20. Fine filtration unit; 21. Fine filtration safety filter; 22. Fine filtration water pump; 23. Fine filtration device; 24. Water storage tank;

[0037] 30. Reverse osmosis unit; 301. Reverse osmosis water pump; 302. Reverse osmosis security filter; 303. High-pressure pump; 304. Reverse osmosis device; 3. Filter element; 31. Reverse osmosis body; 311. Membrane shell; 312. First reverse osmosis assembly; 312a. First reverse osmosis water collecting pipe; 312b. First reverse osmosis membrane; 313. Second reverse osmosis assembly; 313a. Second reverse osmosis water collecting pipe; 313b. Second reverse osmosis membrane; 32. Pre-scale inhibitor; 321. Scale inhibitor body; 322. First grid piece; 323. Second grid piece; 324. Barrier grid piece; 33. Post-mineralization section; 331. Mineralization ejector; 34. Sealing ring;

[0038] 40. Energy recovery unit; 41. Energy recovery device; 42. Booster pump;

[0039] C, chlorine production module; C1, electrolytic chlorine production unit;

[0040] 51. Chlorine production filter; 52. Electrolytic cell; 53. Sodium hypochlorite storage tank; 54. Dosing pump; 55. Cooling unit; 551. Heat exchanger; 552. Cooling water pump; 56. Pickling unit; 561. Acid unloading pump; 562. Acid storage tank; 563. Acid mist absorber; 564. Pickling box; 565. Pickling pump. DETAILED DESCRIPTION

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] A reverse osmosis device 304, such as Figure 1As shown, at least one filter element 3 is included, the filter element 3 includes a reverse osmosis body 31, the reverse osmosis body 31 includes a membrane shell 311 and a first reverse osmosis component 312 and a second reverse osmosis component 313 installed in the membrane shell 311, the first reverse osmosis component 312 includes a primary reverse osmosis water collecting pipe 312a and a primary reverse osmosis membrane 312b wound around its outer circumference, the second reverse osmosis component 313 includes a secondary reverse osmosis water collecting pipe 313a and a secondary reverse osmosis membrane 313b wound around its outer circumference, the second reverse osmosis component 313 is embedded in the primary reverse osmosis water collecting pipe 312a, the inlet of the primary reverse osmosis membrane 312b is connected to the incoming water, and the outlet of the secondary reverse osmosis water collecting pipe 313a discharges clean water.

[0047] In this embodiment, the first reverse osmosis component 312 and the second reverse osmosis component 313 are integrated in a membrane shell 311, and the second reverse osmosis component 313 is embedded in the first reverse osmosis water collecting pipe 312a of the first reverse osmosis component 312, and the seawater enters the filter element 3 through the inlet of the first reverse osmosis membrane 312b, and the seawater is filtered through the first reverse osmosis membrane 312b and then enters the second reverse osmosis membrane 313b through the first reverse osmosis water collecting pipe 312a for filtration, and finally discharged from the filter element 3 through the outlet of the second reverse osmosis water collecting pipe 313a, realizing the double-stage reverse osmosis filtration of seawater, more effectively removing various impurities in seawater, solving the problem that the original multiple reverse osmosis membrane components are separately set, the structure is complex, and the occupation area is large. The present device has a simple structure and a compact and reasonable layout. Among them, the reverse osmosis device 304 is mainly used to filter and remove salt, microorganisms, suspended matter, colloidal substances and heavy metal ions.

[0048] Furthermore, if Figures 1 to 4 As shown, the filter element 3 also includes a pre-scaling part 32 arranged at the water inlet end of the membrane shell 311; the pre-scaling part 32 includes a scale inhibitor body 321 (with built-in scale inhibitor), and the two ends of the scale inhibitor body 321 are respectively provided with a first grid member 322 and a second grid member 323, and the second grid member 323 is at least connected to the primary reverse osmosis membrane 312b, so that the seawater can enter the primary reverse osmosis membrane 312b for primary reverse osmosis filtration after being filtered by the pre-scaling part 32; at least one barrier grid member 324 is provided in the scale inhibitor body 321, and the scale inhibitor is arranged in layers through the barrier grid members 324, so that the scale inhibitor is evenly distributed inside the scale inhibitor body 321, effectively ensuring the full release of the scale inhibitor; the grid density of the first grid member 322 is greater than the grid density of the barrier grid member 324 and the second grid member 323, that is, the outermost water inlet end uses a denser grid to wrap the scale inhibitor inside, while ensuring the passage of water, preventing the scale inhibitor from leaking. The pre-scale inhibitor 32 is mainly used to remove mineral deposits formed by metal ions such as calcium and magnesium.

[0049] Furthermore, if Figures 1 to 5As shown, the filter element 3 also includes a post-mineralization part 33 arranged at the water outlet end of the membrane shell 311, and a mineralization ejector 331 connected to the secondary reverse osmosis water collecting pipe 313a is arranged in the post-mineralization part 33; the post-mineralization part 33 is used to supplement the minerals and trace elements in the fresh water to improve the drinking taste, and the mineralization ejector 331 is used to disperse the fresh water discharged from the secondary reverse osmosis water collecting pipe 313a, so that the fresh water is evenly dispersed and fully contacted with the post-mineralization part 33, thereby improving the mineralization effect. If used for industrial purposes, such as steam conversion water, the post-mineralization part 33 can be cancelled.

[0050] Furthermore, if Figure 5 As shown, the mineralizing ejector 331 is an umbrella-shaped structure with a cavity, and a plurality of ejection holes are provided on the mineralizing ejector 331. The aperture of the ejection holes is smaller than the aperture of the secondary reverse osmosis water collecting pipe 313a. This structure can effectively ensure that the outlet flow rate of the purified water is increased and fully contacts with the rear mineralizing part 33. In addition, the impact velocity is large, so that effective mineralization can be achieved.

[0051] Furthermore, if Figures 9 to 11 As shown, the number of filter elements 3 is n, 2≤n≤8; multiple filter elements 3 are connected in series in sequence, and the primary reverse osmosis membrane 312b, secondary reverse osmosis membrane 313b and secondary reverse osmosis water collecting pipe 313a of adjacent filter elements 3 are connected one by one, that is, the outlet of the primary reverse osmosis membrane 312b of the previous filter element 3 is connected to the inlet of the secondary reverse osmosis membrane 313b of the next filter element 3, the outlet of the secondary reverse osmosis membrane 313b of the previous filter element 3 is connected to the inlet of the secondary reverse osmosis membrane 313b of the next filter element 3, and the outlet of the secondary reverse osmosis water collecting pipe 313a of the previous filter element 3 is connected to the inlet of the secondary reverse osmosis water collecting pipe 313a of the next filter element 3, so that the water in the same functional chamber of each filter element 3 is connected in series through multiple filter elements 3. Among them, Figures 9 to 11 Proposed and Figures 1 to 8 A different structure is provided, that is, the membrane shell 311 of the filter element 3 is extended at the tail of each filter element 3, a sleeve-like structure is added, and the next filter element 3 is matched through a rubber ring. This structure can increase the stability of the filter element 3 inside the membrane shell 311, forming a structure such as Fig.11 structure.

[0052] Specifically, Figure 1 and Figure 4 As shown, the filter element 3 is the first filter element 3 directly connected to the seawater, and a grid is provided on the outer periphery of the second grid member 323 of the pre-scale inhibitor 32, so that the pre-scale inhibitor 32 is connected to the primary reverse osmosis membrane 312b, and the seawater can enter the primary reverse osmosis membrane 312b for filtration after passing through the pre-scale inhibitor 32; Figure 6 and Figure 8As shown, the filter element 3 is the 2nd to nth filter element 3 connected in sequence to the first filter element 3, and the adjacent filter elements 3 are connected by pipelines through the rear mineralization part 33 of the adjacent previous filter element 3 and the front scale inhibition part 32 of the next filter element 3, so as to realize the water connection of the same functional chambers of each filter element 3.

[0053] In the above embodiment, the working process of the reverse osmosis device 304 is as follows:

[0054] The reverse osmosis device 304 is applied to the seawater desalination system. The reverse osmosis device 304 includes at least one filter element 3, which integrates the functions of pre-scale inhibition, two-stage reverse osmosis filtration, and post-mineralization. The pre-treated seawater first passes through the pre-scale inhibition part 32, and the scale inhibitor is slowly released into the raw seawater, enters the membrane shell 311, and is filtered by the first-level reverse osmosis membrane 312b and then enters the next-level second-level reverse osmosis membrane 313b for filtration through the first-level reverse osmosis water collection pipe 312a. The unfiltered seawater will enter the second to n-level filter element 3 for further filtration, and finally be discharged at the n-level filter element 3 in the form of first-level reverse osmosis wastewater. The seawater filtered by the first-level reverse osmosis membrane 312b will be used as the raw water of the second-level reverse osmosis membrane 313b for secondary filtration. The water after the second-level filtration is collected through the second-level reverse osmosis water collection pipe 313a. The effluent at this stage contains almost no ions. The unfiltered water of the second-level reverse osmosis membrane 313b will enter the second to n-level filter element 3 for further filtration. By analogy, the water in the same functional chamber of the filter element 3 mentioned in this embodiment is connected in series through multiple filter elements 3. In order to adapt to the membrane shell 311, the membrane element mentioned in this embodiment is fixed to the membrane shell 311 through a sealing ring 34 to prevent water leakage.

[0055] In the field of seawater desalination, the membrane shell 311 can generally have 1 to 8 filter elements 3. In order to meet the requirements of conventional working conditions, the integrated filter element 3 mentioned in this embodiment will be the first (such as Figures 1 to 4 as shown) and 2 to n (as shown Figures 6 to 8 The structure of the filter element 3 is shown in FIG. Figure 1 As shown, the water inlet end of the first filter element 3 only allows the pre-treated seawater to enter the primary reverse osmosis membrane 312b area for filtration; Figure 1 , Figure 6 and Fig.11 As shown, starting from the second filter element 3, the outlet of the primary reverse osmosis membrane 312b area of ​​the previous filter element 3 (corresponding to the discharge of raw water and primary reverse osmosis wastewater i), the outlet of the secondary reverse osmosis membrane 313b area (corresponding to the discharge of primary reverse osmosis produced water, i.e., secondary reverse osmosis raw water and wastewater j), and the outlet of the secondary reverse osmosis water collecting pipe 313a (corresponding to the discharge of secondary reverse osmosis produced water k) are connected to the inlet of the chamber corresponding to the function of the next adjacent filter element 3. The various levels of structure are sealed by rubber rings. If a filter element 3 membrane shell 311 is used, only the following method of this application is used. Figure 1 The first filter element 3 structure is shown.

[0056] It is further explained here that the seawater of the first filter element 3 is pressurized by the high-pressure pump 303 to complete the first-level reverse osmosis filtration; the second-level reverse osmosis adopts the form of being embedded in the first-level reverse osmosis, and the pressure after passing through the first-level reverse osmosis membrane 312b is used as the second-level reverse osmosis filtration pressure. In order to ensure that the secondary reverse osmosis effluent meets the requirements, a negative pressure pump or a vacuum pump (not shown) can be set at the outlet of the second-level reverse osmosis water outlet of the nth filter element 3, that is, the outlet of the second-level reverse osmosis water collecting pipe 313a of the nth filter element 3, according to different working conditions, to increase the transmembrane pressure difference of the second-level reverse osmosis membrane 313b. In addition, the desalination rate of the second-level reverse osmosis membrane 313b is generally selected to be higher than that of the first-level reverse osmosis membrane 312b.

[0057] The present invention also provides a seawater desalination system, such as Fig.12 and Fig.14 As shown, it includes a seawater desalination module B, which includes a pretreatment unit 10, a fine filtration unit 20 and a reverse osmosis unit 30 connected in sequence, and the reverse osmosis unit 30 includes the reverse osmosis device 304 as described above.

[0058] Furthermore, if Fig.12 and Fig.15 As shown, the seawater desalination system also includes a chlorine production module C, which is used to electrolyze seawater to prepare a sodium hypochlorite solution; the water outlet of the chlorine production module C is connected to the water inlet of the seawater desalination module B to inject the sodium hypochlorite solution into the water inlet of the seawater desalination module B to remove hydrogen sulfide in the inlet seawater.

[0059] Furthermore, the seawater desalination system further comprises a seawater inlet pump A; Fig.12 As shown, the seawater inlet pump A is connected to the water inlet end of the chlorine production module C and the water inlet end of the seawater desalination module B. The chlorine production module C includes a sodium hypochlorite storage tank 53. The water outlet end of the chlorine production module C is connected to the water inlet end of the sodium hypochlorite storage tank 53. The water outlet end of the sodium hypochlorite storage tank 53 is connected to the water inlet end of the seawater desalination module B through a dosing pipe to add sodium hypochlorite solution to the water inlet end of the seawater desalination module B; or, Fig.13 As shown, the seawater inlet pump A is connected to the chlorine production module C, and the water outlet end of the chlorine production module C is directly connected to the water inlet end of the seawater desalination module B to input seawater to the water inlet end of the seawater desalination module B.

[0060] Among them, the different seawater quality around the world has led to the desalination system being basically "customized". The desalination systems in various places need to be designed based on the local inlet water quality. In some areas, the inlet water quality of the seawater desalination system is acidic due to excessive hydrogen sulfide content. In a humid environment, it is easy to electrochemically react with steel equipment, causing corrosion to steel or gathering and transportation systems and equipment made of active metals. Specifically, Fig.12 As shown, the seawater inlet pump A pumps seawater into the water inlet of the seawater desalination module B, and the sodium hypochlorite solution prepared by the chlorine production module C is stored in the sodium hypochlorite storage tank 53. Then the sodium hypochlorite solution is added to the water inlet of the seawater desalination module B through the dosing pipe to mix with the seawater, so that the hydrogen sulfide in the seawater is oxidized into elemental sulfur by the sodium hypochlorite. When the concentration of sodium hypochlorite is high, the elemental sulfur can be further oxidized to form sodium sulfate, which solves the problem that the hydrogen sulfide content in the seawater quality in some areas is high, the equipment is prone to hydrogen sulfide corrosion, and the entire seawater desalination system has an irreversible negative impact. This embodiment combines the electrolysis of seawater chlorine production module C with the seawater desalination module B, and uses the effective chlorine produced by electrolysis of chlorine to oxidize the hydrogen sulfide in the water inlet of the seawater desalination system, further expanding the application scope of the chlorine production module C and simultaneously reducing the limited scope of the seawater desalination system. Among them, Fig.13 As shown, when the desalination seawater flow rate is low, the effluent from the chlorine production module C can be directly treated and then enter the seawater desalination system, that is, the seawater inlet pump A does not need to be directly connected to the water inlet end of the seawater desalination module B.

[0061] This embodiment can solve the problem of excessive hydrogen sulfide content in the water quality of the membrane desalination system. Hydrogen sulfide dissolves in water and makes the solution acidic, which causes corrosion of the system's main body containing steel or active metal gathering and transportation systems and equipment. The corrosion principle is as follows:

[0062] H2S→HS - +H + →S 2- +2H +

[0063] Fe-2e - →Fe 2+

[0064] 2H + +2e - →H2↑

[0065] xFe+yH2S→Fe x S y +yH2

[0066] The pre-chlorination module C produces sodium hypochlorite to degrade hydrogen sulfide to eliminate the corrosion of hydrogen sulfide solution on metal equipment and materials. At the same time, the electrolysis method can also degrade hydrogen sulfide in seawater. The anti-corrosion principle is as follows:

[0067] Anode plate: 2Cl - →Cl2↑+2e - ; S 2- →S↓+2e -

[0068] Cathode plate: 2H2O+2e- →H2↑+2OH - ;M n+ Cations in seawater +ne - →M

[0069] Reaction in seawater solution: Cl2+2OH - →ClO - +Cl - +H2O

[0070] The residual chlorine produced will undergo a redox reaction with hydrogen sulfide in water:

[0071] H2S+NaClO=NaCl+S↓+H2O

[0072] S+4NaClO=Na2SO4+NaCl

[0073] Through the above reaction, the effect of removing hydrogen sulfide in seawater is achieved.

[0074] Among them, Fig.12 , Fig.13 and Fig.15 As shown, the chlorine production module C includes a chlorine production filter 51 connected to the seawater inlet pump A. After filtration, the water enters the electrolytic chlorine production section C1, including an electrolytic cell 52, a sodium hypochlorite storage tank 53, a dosing pump 54, a cooling unit 55 composed of a heat exchanger 551, a cooling water pump 552 and supporting electrical equipment (not shown), and an acid cleaning unit 56 composed of an acid discharge pump 561, an acid storage tank 562, an acid mist absorber 563, an acid cleaning box 564, and an acid cleaning pump 565. Among them, the form of the electrolytic cell 52 is not limited, and a suitable plate-net electrolytic cell 52 or a tube-sheet electrolytic cell 52 is selected according to actual conditions.

[0075] The basic principle of producing chlorine by electrolyzing seawater is that when a certain voltage is applied to electrode plates made of special materials in seawater, the following electrolytic reaction will occur on the surface of the electrode plates.

[0076] Anode plate: 2Cl - →Cl2↑+2e -

[0077] Cathode plate: 2H2O+2e - →H2↑+2OH -

[0078] Reaction in seawater solution: Cl2+2OH - →ClO - +Cl - +H2O

[0079] The ClO produced in the above electrolysis reaction -, Cl2 both exist in the seawater after electrolysis, and both have oxidative killing capabilities, collectively referred to as effective chlorine.

[0080] The basic process of electrolyzing seawater to produce chlorine is: seawater inflow → seawater inlet pump → chlorine filter → electrolytic cell → sodium hypochlorite storage tank → dosing pump → circulating water. While electrolyzing seawater to produce sodium hypochlorite, hydrogen sulfide in seawater can also be electrolyzed and decomposed.

[0081] Furthermore, if Figure 12 to Figure 14 As shown, the pretreatment unit 10 includes a pretreatment filter 11 and a reducing agent adding point. The water inlet of the pretreatment filter 11 is connected to the seawater to be desalinated, and the reducing agent adding point is arranged between the pretreatment filter 11 and the fine filtration unit 20. In order to prevent the effective chlorine concentration in the seawater entering the seawater desalination module B from being too high, a reducing agent can be added to react and neutralize it. It is worth mentioning that the sodium hypochlorite solution produced after electrolysis by the chlorine production module C can be used as circulating cooling water in the plant area in addition to being used to oxidize hydrogen sulfide in the original seawater.

[0082] Furthermore, if Fig.14 As shown, the fine filtration unit 20 includes a fine filtration security filter 21, a fine filtration water pump 22, a fine filtration device 23, and a water storage tank 24 which are connected in sequence; wherein the water inlet end of the fine filtration security filter 21 is connected to the water outlet end of the pretreatment filter 11, the fine filtration device 23 is an ultrafiltration or nanofiltration device, and the water storage tank 24 is used to store seawater after ultrafiltration or nanofiltration.

[0083] Furthermore, if Fig.14 As shown, the reverse osmosis unit 30 also includes a reverse osmosis water pump 301, a reverse osmosis security filter 302 and a high-pressure pump 303 connected in sequence. The water inlet end of the reverse osmosis water pump 301 is connected to the water outlet end of the fine filtration unit 20, that is, connected to the water storage tank 24, and the water outlet end of the high-pressure pump 303 is connected to the water inlet end of the reverse osmosis device 304, so as to pump the seawater after ultrafiltration or nanofiltration into the reverse osmosis unit 30, and pressurize it through the high-pressure pump 303 to complete the first-level reverse osmosis filtration.

[0084] Furthermore, if Fig.14 As shown, the seawater desalination system also includes an energy recovery unit 40 connected to the concentrated seawater outlet of the reverse osmosis unit 30, and the energy recovery unit 40 includes a booster pump 42 and an energy recovery device 41. The concentrated water desalinated by the reverse osmosis unit 30 passes through the energy recovery device 41 and the booster pump 42, and then returns to the front of the reverse osmosis unit 30 membrane for energy recovery. The reverse osmosis concentrated water after energy recovery can be discharged from the seawater desalination module B, or returned to the chlorine production module C for water inlet to electrolyze the concentrated seawater.

[0085] It is explained here that the communication between the components is through pipe connection, such as Fig.11 As shown, the same functional components of two adjacent filter elements 3 are connected by pipelines.

[0086] Specifically, Fig.12 As shown, the working process of the seawater desalination system is:

[0087] The pretreated seawater is divided into two routes to the chlorine production module C and the seawater desalination module B through the seawater inlet pump A. Before entering the electrolytic chlorine production section C1, it is filtered through a higher precision electrolytic chlorine production filter 51. After the seawater to be electrolyzed is filtered, it is electrolyzed in the electrolytic cell 52 made of DSA anode and Hastelloy cathode to produce effective chlorine and enter the sodium hypochlorite storage tank 53. The seawater that needs to be desalinated at the same time is oxidized by the sodium hypochlorite in the sodium hypochlorite storage tank 53, and then the solid sulfur and other particulate objects in the seawater produced by the reaction are filtered through the pretreatment filter 11. In order to prevent the effective chlorine concentration in the seawater entering the seawater desalination module B from being too high, a reducing agent can be added to react and neutralize it before entering the seawater desalination section B1. It is worth mentioning that the sodium hypochlorite solution produced after electrolysis in the chlorine production module C can be used as circulating cooling water for the plant area in addition to oxidizing hydrogen sulfide in the original seawater.

[0088] Among them, Fig.15 As shown, the working process of the chlorine production module C is as follows: seawater enters the electrolytic cell 52 after being filtered by the chlorine production filter 51 through the seawater inlet pump A, and the electrolyzed seawater enters the sodium hypochlorite storage tank 53, and finally the chlorine-containing seawater is transported to the dosing point through the dosing pump 54. This process is supplemented by a cooling unit 55 and an acid washing unit 56. The cooling unit 55 is used to cool the system rectifier (not shown in the present invention). The water source is taken from the chlorine production filter 51 and pumped to the heat exchanger 551 through the cooling water pump 552. The cooled water is used for rectifier heat exchange, which plays a role in system protection. After the electrolytic cell 52 has been running for a period of time, the pickling unit 56 is started to clean the scale on the plates of the electrolytic cell 52. After the concentrated hydrochloric acid or the same type of cleaning agent arrives, it is unloaded to the acid storage tank 562 through the acid unloading pump 561. The pickling agent in the acid storage tank 562 can generally flow into the pickling tank 564 by gravity flow. After the pickling agent of a certain concentration is configured, the agent is pumped into the electrolytic cell 52 by the pickling pump 565 to clean the plates. In this process, the acid mist in the acid storage tank 562 and the pickling tank 564 is processed by the acid mist absorber 563, and the absorbed pickling agent flows back to the pickling tank 564 again.

[0089] like Fig.14As shown, the working process of the seawater desalination module B is as follows: after the sodium hypochlorite solution in the sodium hypochlorite storage tank 53 is added to the water inlet of the seawater desalination module B, it is pumped into the system through the seawater inlet pump A. After the seawater is pretreated by the pretreatment unit 10, the excess sulfur and residual chlorine in the water are removed. Then, it passes through the fine filtration security filter 21 in turn, and is pumped into the fine filtration device 23 through the fine filtration water supply pump 22 for fine filtration. The salinity of the seawater after fine filtration is still high, but large particles of solid impurities are basically removed; this part of water is stored in the water storage tank 24. The seawater after fine filtration enters the reverse osmosis security filter 302 through the reverse osmosis water supply pump 301, and then is pumped into the reverse osmosis device 304 through the high-pressure pump 303 for seawater desalination. The desalinated concentrated water passes through the energy recovery device 41 and the booster pump 42 and then returns to the reverse osmosis device 304 membrane for energy recovery. The reverse osmosis concentrated water after energy recovery can be discharged from the seawater desalination module B, or it can be returned to the chlorine production module C water inlet for electrolysis of concentrated seawater.

[0090] In the above-mentioned chlorine production module C, the sodium hypochlorite storage tank 53 can be eliminated. When the flow rate of desalinated seawater is low, the effluent of the chlorine production module C can be directly used as the inlet water of the seawater desalination module B.

[0091] To further prove the feasibility of the desalination system, a laboratory simulation experiment was conducted, using sodium sulfide instead of hydrogen sulfide. The results showed that NaClO can convert S 2- Oxidation, eventually converted into stable SO4 2- . The NaClO dosing concentration above 3mg / L can remove the S in the Na2S seawater solution of the desalination project. 2- Eliminate to a safe range of <0.01mg / L. 7mg / L NaClO dosing concentration will reduce the concentration of S in the Na2S seawater solution of the desalination project. 2- Oxidized to SO4 2- The efficiency is the highest and it is controlled at a lower concentration of 2.25×10 3 mg / L.

[0092] Beneficial effects of the present invention:

[0093] (1) The first reverse osmosis component 312 and the second reverse osmosis component 313 are integrated in a membrane shell 311, and the second reverse osmosis component 313 is embedded in the first-level reverse osmosis water collecting pipe 312a of the first reverse osmosis component 312. The seawater enters the filter element 3 through the inlet of the first-level reverse osmosis membrane 312b. After being filtered by the first-level reverse osmosis membrane 312b, the seawater enters the second-level reverse osmosis membrane 313b through the first-level reverse osmosis water collecting pipe 312a for filtration, and finally is discharged from the filter element 3 through the outlet of the second-level reverse osmosis water collecting pipe 313a, thereby realizing double-stage reverse osmosis filtration of seawater, more effectively removing various impurities in seawater, and solving the problem that the original multiple reverse osmosis membrane components are separately arranged, the structure is complex, and the footprint is large. The device has a simple structure and a compact and reasonable layout.

[0094] (2) The sodium hypochlorite solution prepared by the chlorine production module C is added to the water inlet of the seawater desalination module B and mixed with seawater or directly used as the incoming water for desalination of seawater, so that the hydrogen sulfide in the seawater is oxidized into elemental sulfur by the sodium hypochlorite. When the concentration of sodium hypochlorite is high, the elemental sulfur can be further oxidized to form sodium sulfate, thereby solving the problem that the hydrogen sulfide content in the seawater quality in some areas is high, the equipment is prone to hydrogen sulfide corrosion, and the entire seawater desalination system has an irreversible negative impact. In this embodiment, the electrolysis of seawater chlorine production module C is combined with the seawater desalination module B, and the effective chlorine produced by electrolysis of chlorine is used to oxidize the hydrogen sulfide in the inlet water of the seawater desalination system, thereby further expanding the application scope of the chlorine production module C and simultaneously reducing the limited scope of the seawater desalination system.

[0095] 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 reverse osmosis device, characterized in that: The invention comprises at least one filter element (3), wherein the filter element (3) comprises a reverse osmosis body (31), wherein the reverse osmosis body (31) comprises a membrane shell (311) and a first reverse osmosis component (312) and a second reverse osmosis component (313) installed in the membrane shell (311), wherein the first reverse osmosis component (312) comprises a primary reverse osmosis water collecting pipe (312a) and a primary reverse osmosis membrane (312b) wound around the outer circumference thereof, and the second reverse osmosis component (313) comprises a secondary reverse osmosis water collecting pipe (313a) and a secondary reverse osmosis membrane (313b) wound around the outer circumference thereof, and the second reverse osmosis component (313) is embedded in the primary reverse osmosis water collecting pipe (312a), the inlet of the primary reverse osmosis membrane (312b) is connected to incoming water, and the outlet of the secondary reverse osmosis water collecting pipe (313a) discharges purified water.

2. The reverse osmosis device according to claim 1, characterized in that: The filter element (3) also includes a pre-scale inhibitor (32) arranged at the water inlet end of the membrane shell (311); the pre-scale inhibitor (32) includes a scale inhibitor body (321), and the two ends of the scale inhibitor body (321) are respectively provided with a first grid member (322) and a second grid member (323), the second grid member (323) is connected to at least the first-level reverse osmosis membrane (312b), and at least one barrier grid member (324) is provided in the scale inhibitor body (321); the grid density of the first grid member (322) is greater than the grid density of the barrier grid member (324) and the second grid member (323).

3. The reverse osmosis device according to claim 1, characterized in that: The filter element (3) further comprises a post-mineralization section (33) arranged at the water outlet end of the membrane shell (311), wherein a mineralization ejector (331) connected to the secondary reverse osmosis water collecting pipe (313a) is arranged in the post-mineralization section (33).

4. The reverse osmosis device according to claim 3, characterized in that: The mineralized ejector (331) is an umbrella-shaped structure with a cavity. The mineralized ejector (331) is provided with a plurality of ejection holes, and the aperture of the ejection holes is smaller than the aperture of the secondary reverse osmosis water collecting pipe (313a).

5. The reverse osmosis device according to claim 1, characterized in that: The number of the filter elements (3) is n, 2≤n≤8; the plurality of filter elements (3) are connected in series in sequence, and the primary reverse osmosis membrane (312b), the secondary reverse osmosis membrane (313b) and the secondary reverse osmosis water collecting pipe (313a) of adjacent filter elements (3) are all connected in a one-to-one correspondence.

6. A seawater desalination system, characterized in that: The invention comprises a seawater desalination module (B), wherein the seawater desalination module (B) comprises a pretreatment unit (10), a fine filtration unit (20) and a reverse osmosis unit (30) which are connected in sequence, and the reverse osmosis unit (30) comprises a reverse osmosis device (304) according to any one of claims 1 to 5.

7. The seawater desalination system according to claim 6, characterized in that: The seawater desalination system further comprises a chlorine production module (C) for electrolyzing seawater to prepare a sodium hypochlorite solution; the water outlet of the chlorine production module (C) is connected to the water inlet of the seawater desalination module (B).

8. The seawater desalination system according to claim 7, characterized in that: The seawater desalination system further comprises a seawater inlet pump (A); the seawater inlet pump (A) is connected to the water inlet end of the chlorine production module (C) and the water inlet end of the seawater desalination module (B); the chlorine production module (C) comprises a sodium hypochlorite storage tank (53); the water outlet end of the chlorine production module (C) is connected to the water inlet end of the sodium hypochlorite storage tank (53); the water outlet end of the sodium hypochlorite storage tank (53) is connected to the water inlet end of the seawater desalination module (B) through a dosing pipe, so as to add sodium hypochlorite solution to the water inlet end of the seawater desalination module (B); or, the seawater inlet pump (A) is connected to the water inlet end of the chlorine production module (C), and the water outlet end of the chlorine production module (C) is directly connected to the water inlet end of the seawater desalination module (B), so as to input seawater into the water inlet end of the seawater desalination module (B).

9. The seawater desalination system according to claim 6, characterized in that: The pretreatment unit (10) comprises a pretreatment filter (11) and a reducing agent adding point, the water inlet end of the pretreatment filter (11) is connected to the seawater to be desalinated, and the reducing agent adding point is arranged between the pretreatment filter (11) and the fine filtration unit (20).

10. The seawater desalination system according to claim 6, characterized in that: The reverse osmosis unit (30) further comprises a reverse osmosis water supply pump (301), a reverse osmosis safety filter (302) and a high-pressure pump (303) which are connected in sequence, wherein the water inlet of the reverse osmosis water supply pump (301) is connected to the water outlet of the fine filtration unit (20), and the water outlet of the high-pressure pump (303) is connected to the water inlet of the reverse osmosis device (304).

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