A sea water desalination plant for blending with reclaimed water

Abstract

This utility model relates to a seawater desalination device for mixing reclaimed water, belonging to the field of seawater desalination technology. The device includes a mixing tank, an ultrafiltration section, an ultrafiltration tank, a seawater reverse osmosis section, and a freshwater tank connected in sequence. The mixing tank is connected to both a pretreated seawater pipeline and a reclaimed water pipeline. The mixing tank has a reclaimed water inlet connected to the reclaimed water pipeline, with the inlet angle tangential to the mixing tank. Multiple turbulence columns are installed in the mixing tank, distributed circumferentially around the center of the mixing tank. This utility model connects the reclaimed water pipeline to the mixing tank, using qualified reclaimed water from a municipal wastewater treatment plant mixed with seawater that has undergone primary pretreatment, effectively diluting the salinity and impurity concentration of the seawater entering the ultrafiltration and reverse osmosis sections. Seawater with lower salinity and impurity concentration requires lower equipment operating pressure, significantly reducing equipment costs and thus lowering investment in seawater desalination projects and water production costs.

Description

Technical Field

[0001] This utility model belongs to the field of seawater desalination technology, specifically relating to a seawater desalination device for mixing with recycled water. Background Technology

[0002] Seawater desalination technology is developing towards larger-scale engineering, environmental friendliness, low energy consumption, and low cost. Current main technologies include multi-effect distillation and reverse osmosis. The membrane-based seawater desalination process within reverse osmosis involves treating seawater after removing suspended solids, microorganisms, and other impurities using reverse osmosis to obtain desalinated seawater. Reducing the water production cost of seawater desalination projects and ensuring water supply through multiple channels are the research directions for technical personnel. Summary of the Invention

[0003] In view of the current state of technology, the purpose of this utility model is to provide a seawater desalination device for mixing reclaimed water; by mixing qualified reclaimed water from municipal sewage treatment plants into seawater that has undergone primary pretreatment, the salinity of the seawater is reduced, thereby reducing engineering investment and water production costs, and improving process stability.

[0004] To achieve the above objectives, the technical solution of this utility model is as follows: A seawater desalination device for mixing greywater includes a mixing tank, an ultrafiltration unit, an ultrafiltration tank, a seawater reverse osmosis unit, and a freshwater tank connected in sequence. The mixing tank is connected to a pretreated seawater pipeline and a greywater pipeline. The mixing tank has a greywater inlet connected to the greywater pipeline, with the inlet angle being tangential to the mixing tank. The mixing tank also has multiple turbulence-inducing columns distributed circumferentially around the center of the mixing tank.

[0005] Optionally, the seawater inlet has the same inlet angle as the reclaimed water inlet, and the seawater inlet and the reclaimed water inlet are respectively connected to the seawater spiral guide channel and the reclaimed water spiral guide channel in the mixing tank; the seawater spiral guide channel and the reclaimed water spiral guide channel are respectively arranged on the inner wall of the mixing tank; the ends of the seawater spiral guide channel and the reclaimed water spiral guide channel have opposite directions.

[0006] Optionally, in the mixing tank, ultrafiltration tank, and freshwater tank, the inlet is positioned higher than the outlet; and the top of the mixing tank, ultrafiltration tank, and freshwater tank is respectively provided with an air vent pipe, which is a vertically upward straight pipe with a downward bend at the end and an opening facing downward.

[0007] Optionally, the turbulence column is vertically arranged in the mixing tank, with its top end connected to the top of the mixing tank and its bottom end connected to the bottom of the mixing tank.

[0008] Optionally, the ultrafiltration unit includes a self-cleaning filter and an ultrafiltration device connected in sequence. The ultrafiltration device is connected to an ultrafiltration water tank through an output pipeline, and the ultrafiltration water tank is further connected to the ultrafiltration device through an ultrafiltration backwash pipeline.

[0009] Optionally, the ultrafiltration backwash pipeline is sequentially equipped with a filter backwash pump, a first security filter, and a first dosing device; a pressure pump is installed between the mixing tank and the self-cleaning filter; and an aeration device is installed at the bottom of the ultrafiltration device, which is connected to the ultrafiltration blower.

[0010] Optionally, the ultrafiltration device is connected to the first CIP cleaning and dosing device.

[0011] Optionally, the seawater reverse osmosis section includes a reverse osmosis booster pump, a second dosing device, a second security filter, a high-pressure pump, and a reverse osmosis device connected in sequence, wherein the reverse osmosis device is connected to the freshwater tank.

[0012] Optionally, a cleaning device is provided between the second security filter and the reverse osmosis device, connected in parallel with the high-pressure water pump. The cleaning device includes a cleaning water tank and a cleaning water pump.

[0013] Optionally, the reverse osmosis unit is connected to a second CIP cleaning and dosing unit.

[0014] Optionally, the cleaning water tank is connected to both the reverse osmosis unit and the concentrate tank.

[0015] The beneficial effects of this utility model are as follows: This invention connects a reclaimed water pipeline to a mixing tank, utilizing qualified reclaimed water from municipal wastewater treatment plants to mix with seawater that has undergone primary pretreatment. This effectively dilutes the salinity and impurity concentration of the seawater entering the ultrafiltration and reverse osmosis sections. The reclaimed water enters tangentially, enabling mixing with seawater during the influent process. The mixing is further enhanced by a turbulence column inside the mixing tank, preventing stratification of the reclaimed water and seawater due to density and other factors. Therefore, this invention offers greater flexibility in selecting and configuring high-pressure pumps, seawater reverse osmosis membrane modules, and auxiliary facilities required for treating low-salinity seawater, reducing power consumption; decreasing the amount of chemicals used for membrane cleaning, thereby lowering investment in seawater desalination projects and water production costs; fully reusing reclaimed water from municipal wastewater treatment plants, increasing the overall water production of the seawater desalination unit; optimizing urban water use structure; and ensuring water resource supply through multiple channels. Attached Figure Description

[0016] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0017] Figure 1This is a schematic diagram of the seawater desalination device in a specific implementation.

[0018] Figure 2 The diagram below is a schematic diagram of the mixing tank in a specific implementation, wherein (a) is a top view, (b) is a front view showing the medium water spiral guide channel and the seawater spiral guide channel, and (c) is a front view showing the turbulence column.

[0019] Figure 3 This is a schematic diagram of the ultrafiltration section in a specific embodiment.

[0020] Figure 4 This is a schematic diagram of the seawater reverse osmosis section in a specific implementation.

[0021] The components include: 1. Mixing tank; 11. Reclaimed water inlet; 12. Seawater inlet; 13. Reclaimed water spiral guide channel; 14. Seawater spiral guide channel; 15. Turbulence column; 2. Ultrafiltration section; 20. Booster pump; 21. Self-cleaning filter; 22. Ultrafiltration blower; 23. Ultrafiltration device; 24. First security filter; 25. Filter backwash pump; 26. First dosing device; 27. First CIP cleaning dosing device; 3. Ultrafiltration tank; 4. Seawater reverse osmosis section; 41. Reverse osmosis device; 42. Cleaning water pump; 43. High-pressure pump; 44. Cleaning water tank; 45. Concentrate tank; 46. Second security filter; 47. Second CIP cleaning dosing device; 48. Second dosing device; 49. Reverse osmosis booster pump; 5. Freshwater tank; 6. Vent pipe. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] Example 1 A seawater desalination device that mixes water with other substances, such as Figure 1 As shown, it includes a mixing tank 1, an ultrafiltration unit 2, an ultrafiltration tank 3, a seawater reverse osmosis unit 4, and a freshwater tank 5 connected in sequence; The mixing tank 1 is connected to the pretreated seawater pipeline and the greywater pipeline.

[0024] Through the above setup, the treated municipal wastewater and pretreated seawater are mixed in mixing tank 1 to create low-salinity seawater. This allows the subsequent ultrafiltration unit 2 and seawater reverse osmosis unit 4 to treat seawater with even lower salinity and impurity concentrations. Consequently, the required high-pressure pump 43 and reverse osmosis membrane operate at lower pressures, significantly reducing equipment costs. The lower impurity concentration also results in less scaling, consuming fewer cleaning agents, further reducing investment and water production costs. Simultaneously, this achieves the effect of ensuring water resource supply through multiple channels.

[0025] like Figure 2As shown in (a), the mixing tank 1 is provided with a greywater inlet 11 that is connected to the greywater pipeline. The water inlet angle of the greywater inlet 11 is the tangential direction of the mixing tank 1. Since the specific gravity of greywater and seawater is different, they need to be stirred to achieve full mixing, so that the salinity of the seawater entering the ultrafiltration section 2 and the seawater reverse osmosis section 4 remains stable. The angle of the greywater inlet 11 is set to affect the flow state of greywater in the mixing tank 1, and stirring is achieved during the water intake process.

[0026] like Figure 2 As shown in (a), the water inlet angle of the seawater inlet 12 is the same as that of the reclaimed water inlet 11, and it is also a tangential water inlet; the seawater inlet 12 and the reclaimed water inlet 11 are respectively connected to the seawater spiral guide channel 14 and the reclaimed water spiral guide channel 13 in the mixing tank 1, as shown in (a). Figure 2 As shown in (b), the seawater spiral guide channel 14 and the reclaimed water spiral guide channel 13 are respectively installed on the inner wall of the mixing tank 1; Figure 2 As shown in (a), the ends of the seawater spiral guide channel 14 and the medium water spiral guide channel 13 are respectively located at the bottom of the mixing tank 1 and are oriented toward the center of the mixing tank 1 along the diameter direction of the bottom of the mixing tank 1. The ends of the seawater spiral guide channel 14 and the medium water spiral guide channel 13 are in opposite directions, so that the medium water and seawater flow and stimulate each other at the bottom of the mixing tank 1 in opposite directions, thereby promoting mixing.

[0027] like Figure 2 As shown in (a), the mixing tank 1 is provided with multiple turbulence columns 15. The turbulence columns 15 are distributed around the center of the mixing tank 1 and at a predetermined distance from the inner wall. In this embodiment, they are distributed on both sides of the line connecting the ends of the seawater spiral guide channel 14 and the medium water spiral guide channel 13. Specifically, it includes two sets of turbulence columns 15 arranged circumferentially around the center of the mixing tank 1. The first set of turbulence columns 15 has two columns, and the second set has six columns. The first set of turbulence columns 15 is located inside the second set of turbulence columns 15. The cross-section of the turbulence columns 15 is cylindrical. They are arranged vertically in the mixing tank 1 so that after the medium water and seawater flow at a predetermined angle are stimulated, they continue to mix further under the action of the surrounding turbulence columns 15. Figure 2 As shown in (c), the top of the turbulence column 15 is connected to the top of the mixing tank 1, and the bottom of the turbulence column 15 is connected to the bottom of the mixing tank 1, thus providing support for the mixing tank 1 inside.

[0028] The mixing tank 1, ultrafiltration tank 3, and freshwater tank 5 are each equipped with a vent pipe 6, such as Figure 2 As shown in (b), the vent pipe 6 is located at the top of the mixing tank 1. It is a vertically upward straight pipe used to balance the air pressure inside and outside the tank during the water inlet and outlet process. The end of the vent pipe 6 is bent downward so that the opening faces downward to prevent rainwater or dust from entering the tank and causing pollution.

[0029] like Figure 1 As shown, in the mixing tank 1, ultrafiltration tank 3 and freshwater tank 5, the inlet is positioned higher than the outlet; this allows the mixing tank 1, ultrafiltration tank 3 and freshwater tank 5 to store a set amount of water before outputting, reducing fluctuations in the output water quality.

[0030] like Figure 3 As shown, the ultrafiltration unit 2 includes a self-cleaning filter 21 and an ultrafiltration device 23 connected in sequence. The ultrafiltration device 23 is connected to the ultrafiltration water tank 3 through an output pipeline, and the ultrafiltration water tank 3 is also connected to the ultrafiltration device 23 through an ultrafiltration backwash pipeline. The self-cleaning filter 21 is a stacked disc type, which is used to intercept large particulate impurities and protect the ultrafiltration membrane. The ultrafiltration device 23 uses membrane separation technology to remove impurities such as suspended solids, colloids, bacteria, and macromolecular organic matter from the water, reducing the SDI value (stain index) of the effluent and providing high-quality feed water for the reverse osmosis system. The ultrafiltration backwash pipeline is used to backwash the ultrafiltration device 23, and the backwash water comes from the ultrafiltration water tank 3.

[0031] A booster pump 20 is installed between the mixing tank 1 and the self-cleaning filter 21 to increase the water pressure in the self-cleaning filter 21.

[0032] The ultrafiltration backwash pipeline is sequentially equipped with a filter backwash pump 25, a first security filter 24, and a first dosing device 26. The filter backwash pump 25 is used to transport backwash water, the first security filter 24 is used to filter particulate matter in the water to prevent particulate matter from damaging the filter membrane of the ultrafiltration device 23, and the first dosing device 26 is used to add chemical agents to enhance the backwashing effect, such as adding the agents required for chemical enhanced backwash (CEB) technology.

[0033] An aeration device is installed at the bottom of the ultrafiltration unit 23 to aerate the bottom and enhance the backwashing effect. The aeration device is connected to the ultrafiltration blower 22 to provide the gas required for aeration.

[0034] The inlet side of the ultrafiltration device 23 is connected to the first CIP cleaning dosing device 27, which is used to add CIP cleaning agent during the CIP cleaning process of the ultrafiltration device 23. The CIP cleaning process is a cleaning process independent of backwashing, which is used to deeply remove deposited inorganic salts or highly viscous organic matter that are difficult to remove from the ultrafiltration device 23 during backwashing. The interval of CIP cleaning is longer than the interval of backwashing.

[0035] The seawater reverse osmosis section 4 includes sequentially connected components. Figure 1 49. Reverse osmosis booster pump Figure 4The system includes a second chemical dosing device 48, a second security filter 46, a high-pressure pump 43, and a reverse osmosis device 41. The reverse osmosis device 41 is connected to the freshwater tank 5. The reverse osmosis booster pump 49 is used to ensure stable inlet water pressure. The second chemical dosing device 48 is used to add scale inhibitors, reducing agents, and bactericides to prevent water pollution and damage to the osmotic membrane in the reverse osmosis device 41. The second security filter 46 is used to further ensure water quality before the reverse osmosis device 41. The high-pressure pump 43 is used to provide pressure higher than that of seawater to ensure the realization of the reverse osmosis method. The reverse osmosis device 41 is equipped with a reverse osmosis membrane. Under the pressure provided by the high-pressure pump 43, it produces freshwater and transports it to the freshwater tank 5 for storage, and then from the freshwater tank 5 it is transported to the point of use.

[0036] like Figure 4 As shown, a cleaning device connected in parallel with the high-pressure water pump 43 is provided between the second security filter 46 and the reverse osmosis unit 41. The cleaning device is used to clean the internal structure of the reverse osmosis unit 41 during equipment maintenance. The cleaning device includes a cleaning water tank 44 and a cleaning water pump 42. The cleaning water pump 42 pumps the cleaning water in the cleaning water tank 44 to the reverse osmosis unit 41 to achieve cleaning.

[0037] The cleaning water tank 44 is connected to the reverse osmosis unit 41 and the concentrate tank 45 respectively. The cleaning water in the cleaning water tank 44 comes from the reverse osmosis unit 41 and the second security filter 46. The concentrated seawater output from the reverse osmosis unit 41 is sent into the cleaning water tank 44 to supplement the cleaning water. The excess concentrated seawater enters the concentrate tank 45 for centralized treatment.

[0038] The inlet side of the reverse osmosis unit 41 is connected to the second CIP cleaning dosing device 47, which is used to add CIP cleaning agent during the CIP cleaning process of the reverse osmosis unit 41; similarly, the CIP cleaning process is used to deeply clean the reverse osmosis unit 41, and the interval of CIP cleaning is longer than the interval of cleaning completed by only using the cleaning water pump 42.

[0039] The seawater desalination method implemented by the above device includes the following processes: The treated municipal greywater and the pretreated seawater are transported into the mixing tank 1 through greywater pipelines and pretreated seawater pipelines, respectively. The greywater pipeline enters the mixing tank 1 tangentially through multiple greywater inlets 11 and mixes evenly with the seawater under the action of the turbulence column 15 in the mixing tank 1, thus completing the process of blending greywater and becoming seawater with lower salinity. Seawater with low salinity is pumped into a self-cleaning filter 21 by a pressurizing pump 20 to remove large particles of impurities. Then it is pumped into an ultrafiltration device 23 to reduce the SDI value through membrane separation technology, and then pumped into an ultrafiltration water tank 3. The water in the ultrafiltration water tank 3 is filtered by the reverse osmosis booster pump 49 and then pressurized to the set pressure by the high pressure pump 43 before entering the reverse osmosis device 41. Fresh water and concentrated water are obtained through reverse osmosis technology. The fresh water is sent to the fresh water tank 5 and then further sent to the point of use. The concentrated water is sent to the cleaning water tank 44. Excess concentrated water is discharged to the concentrated water pool 45 for further treatment.

[0040] The backwashing process of the ultrafiltration unit 23 includes: water from the ultrafiltration unit 23 enters the ultrafiltration backwash pipeline, is transported by the filter backwash pump 25 to the first security filter 24 for filtration, and then the required chemical agent is added by the first dosing device 26 before being transported to the ultrafiltration unit 23 for backwashing to clean the ultrafiltration membrane in the ultrafiltration unit 23; during the backwashing process, the ultrafiltration blower 22 aerates from below the ultrafiltration unit 23 to improve the backwashing effect. After multiple backwashes, the residual deposited inorganic salts or sticky organic matter on the ultrafiltration membrane are removed by the CIP cleaning process, during which the first CIP cleaning dosing device 27 adds suitable CIP cleaning agents to the ultrafiltration unit 23.

[0041] The cleaning process of the reverse osmosis unit 41 includes: the concentrated seawater output from the reverse osmosis unit 41 is sent to the cleaning water tank 44; the water in the ultrafiltration water tank 3 is transported to the cleaning water tank 44 through a branch connected in parallel with the high-pressure water pump 43; the cleaning water in the cleaning water tank 44 is pressurized by the cleaning water pump 42 and then enters the reverse osmosis unit 41 to clean the internal structure of the reverse osmosis unit 41 and extend the service life of the seawater reverse osmosis membrane module. After multiple cleanings, the residual deposits in the reverse osmosis unit 41 are removed by the CIP cleaning process, during which the second CIP cleaning dosing device 47 adds suitable CIP cleaning agents to the reverse osmosis unit.

[0042] Example 2 A seawater desalination device for mixing greywater differs from Embodiment 1 in that: the mixing tank 1 is provided with two greywater inlets 11 and one seawater inlet 12, which are respectively connected to two greywater spiral guide channels 13 and seawater spiral guide channels 14 in the mixing tank 1; the greywater spiral guide channels 13 and seawater spiral guide channels 14 are spirally arranged downward in the inner wall of the mixing tank 1, and their ends are located at the bottom of the mixing tank 1; the outlet directions of the two greywater spiral guide channels 13 and the seawater spiral guide channel 14 are at a 120° angle to each other, which enables the greywater and seawater to flow and interact in opposite directions at the center of the bottom of the mixing tank 1, thus promoting mixing.

[0043] The turbulence column 15 is set around the center of the mixing tank 1 to turbulent the initially mixed water and seawater, and to prevent it from blocking the mixing process of the two streams of water and seawater flowing directly into each other. Corresponding to the three streams of water in this embodiment, the first group of turbulence columns 15 consists of 3 columns, which are distributed at intervals with the ends of the two water spiral guide channels 13 and the seawater spiral guide channel 14 in a circumferential direction centered on the center of the mixing tank 1.

[0044] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A seawater desalination plant for blending of water, characterized in that, The system includes a mixing tank, an ultrafiltration unit, an ultrafiltration tank, a seawater reverse osmosis unit, and a freshwater tank, which are connected in sequence. The mixing tank is connected to a pretreated seawater pipeline and a greywater pipeline. The mixing tank is equipped with a greywater inlet that is connected to the greywater pipeline, and the inlet angle of the greywater inlet is tangential to the mixing tank. The mixing tank is equipped with multiple turbulence columns, which are distributed circumferentially around the center of the mixing tank.

2. The seawater desalination apparatus for blending produced water as claimed in claim 1, wherein, The seawater inlet has the same inlet angle as the reclaimed water inlet. The seawater inlet and the reclaimed water inlet are respectively connected to the seawater spiral guide channel and the reclaimed water spiral guide channel in the mixing tank. The seawater spiral guide channel and the reclaimed water spiral guide channel are respectively installed on the inner wall of the mixing tank. The ends of the seawater spiral guide channel and the reclaimed water spiral guide channel have opposite directions.

3. The seawater desalination apparatus for blending produced water as claimed in claim 1, wherein, In the mixing tank, ultrafiltration tank, and freshwater tank, the inlet is positioned higher than the outlet; and each of the mixing tank, ultrafiltration tank, and freshwater tank is equipped with a vent pipe at its top. The vent pipe is a vertically upward straight pipe with a downward bend at the end and an opening facing downward.

4. The seawater desalination apparatus for blending produced water as claimed in claim 1, wherein, The turbulence column is vertically installed in the mixing tank, with its top end connected to the top of the mixing tank and its bottom end connected to the bottom of the mixing tank.

5. The seawater desalination apparatus for blending produced water as claimed in claim 1, wherein, The ultrafiltration unit includes a self-cleaning filter and an ultrafiltration device connected in sequence. The ultrafiltration device is connected to an ultrafiltration water tank through an output pipeline, and the ultrafiltration water tank is connected to the ultrafiltration device through an ultrafiltration backwash pipeline.

6. The seawater desalination apparatus for blending produced water as claimed in claim 5 wherein, The ultrafiltration backwash pipeline is sequentially equipped with a filter backwash pump, a first security filter, and a first dosing device; a pressure pump is installed between the mixing tank and the self-cleaning filter; an aeration device is installed at the bottom of the ultrafiltration device, and the aeration device is connected to the ultrafiltration blower.

7. The seawater desalination apparatus for blending produced water as claimed in claim 5 wherein, The ultrafiltration unit is connected to the first CIP cleaning and dosing unit.

8. The seawater desalination apparatus for blending reclaimed water as claimed in claim 1, wherein, The seawater reverse osmosis section includes a reverse osmosis booster pump, a second dosing device, a second security filter, a high-pressure pump, and a reverse osmosis device connected in sequence. The reverse osmosis device is connected to the freshwater tank. A cleaning device is provided between the second security filter and the reverse osmosis device, connected in parallel with the high-pressure pump. The cleaning device includes a cleaning water tank and a cleaning water pump.

9. The seawater desalination apparatus for blending produced water as claimed in claim 8 wherein, The cleaning water tank is connected to the reverse osmosis unit and the concentrate tank respectively.

10. The seawater desalination apparatus for blending produced water as claimed in claim 9 wherein, The reverse osmosis unit is connected to the second CIP cleaning and dosing unit.

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