CN215712392U - High-efficient sea water comprehensive utilization system - Google Patents
High-efficient sea water comprehensive utilization system Download PDFInfo
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- CN215712392U CN215712392U CN202121824972.4U CN202121824972U CN215712392U CN 215712392 U CN215712392 U CN 215712392U CN 202121824972 U CN202121824972 U CN 202121824972U CN 215712392 U CN215712392 U CN 215712392U
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Abstract
The utility model relates to a high-efficiency seawater comprehensive utilization system, which consists of a flat nanofiltration unit, an ion exchange unit, a rolled reverse osmosis membrane unit, a high-pressure flat reverse osmosis unit, an ultrahigh-pressure flat reverse osmosis unit and an evaporative crystallization unit which are sequentially connected. The fouling resistance is better than that of the conventional nanofiltration, so that the process can be simplified; the produced water can be highly concentrated without adding any scale inhibitor. By adopting the system, the seawater can be efficiently and comprehensively utilized, the concentration of the concentrated sodium chloride in the ultra-high pressure flat plate reverse osmosis unit can reach 15-18%, and the high-purity sodium chloride can be prepared by adopting MVR or multi-stage flash evaporation and enhanced crystallization.
Description
Technical Field
The utility model belongs to the technical field of water treatment, and relates to a high-efficiency comprehensive seawater utilization system.
Background
Seawater desalination is an effective method for solving the current shortage of water resources in coastal cities. At present, the most main seawater desalination methods are low-temperature multiple-effect, multi-stage flash evaporation and a reverse osmosis membrane method. The reverse osmosis membrane method has the advantages of low investment, small occupied area, low energy consumption and the like, gradually replaces low-temperature multiple-effect and multi-stage flash evaporation, and becomes the mainstream seawater desalination technology at present. In the process of treating seawater by adopting a reverse osmosis membrane method, because the seawater contains high-concentration sulfate radicals, calcium, magnesium and other ions which are easy to scale, the seawater desalination recovery rate is low, a large amount of scale inhibitor needs to be added into raw water, and the overall operation cost is still high. Because the concentrated water contains substances such as scale inhibitor and the like, the components are complex, and the comprehensive utilization of the subsequent concentrated brine is not facilitated. Compared with reverse osmosis, the nano-filtration device has the advantages that the driving pressure required by nano-filtration is low, the selective separation effect on monovalent divalent ions is realized, most of sulfate radicals and part of calcium and magnesium ions can be efficiently removed, and most of organic matters with the molecular weight of more than 200 daltons can be removed; the nanofiltration produced water is treated by sodium type cation exchange resin, most residual calcium and magnesium ions can be removed, and ions causing scaling in seawater are removed by coupling nanofiltration and ion exchange resin, so that favorable conditions are created for subsequent high-power concentration.
CN104817134A discloses an integrated system and an integrated process for seawater desalination by an all-membrane method adopting ultrafiltration-nanofiltration-reverse osmosis, wherein the system comprises an ultrafiltration system, a three-section nanofiltration system and a reverse osmosis system which are connected in sequence. The three-section nanofiltration system is characterized in that a first section nanofiltration membrane component and a second section nanofiltration membrane component are used for pretreatment of reverse osmosis, and a third section nanofiltration membrane component is used for further treating concentrated water subjected to nanofiltration of the first two sections so as to improve the seawater recovery rate and reduce the scaling tendency of nanofiltration membrane surfaces of the first section nanofiltration membrane component and the second section nanofiltration membrane component, so that the seawater desalination cost is reduced, and the scaling tendency existing when the third section nanofiltration membrane component is used for treating high-salinity concentrated water is reduced. The patent aims to improve the seawater softening recovery rate and reduce the scaling tendency of the membrane surface by using nanofiltration. However, the system needs to add an ultrafiltration system to treat the seawater, and the ultrafiltration system also needs to optionally add acid and/or scale inhibitor to prevent scale. The nanofiltration system needs to adopt three sections, wherein one section and the second section are reverse osmosis pretreatment, the three sections are used for further treating the nanofiltration concentrated water of the first two sections, the seawater softening recovery rate is improved simply by increasing the number of the sections of the nanofiltration system, and the scaling tendency of the membrane surface is reduced by adding seed crystals into the circulating concentrated water. The whole system is long, and the inorganic salt in the seawater is not effectively and selectively separated from the perspective of comprehensive utilization of seawater resources.
CN111423018A discloses a membrane method seawater high-efficiency desalination method, which aims to improve the water yield of fresh water and realize seawater high-efficiency membrane method desalination. The method reduces the scaling risk in the seawater desalination process by a reverse osmosis membrane method by selecting a proper seawater pretreatment process and combining a nanofiltration technology and a reverse osmosis technology. The pretreatment process comprises the steps of pre-precipitation, sterilization, a purifying agent feeding device, a reaction tank, a coagulating sedimentation/air floating device, a microfiltration/ultrafiltration device, a pH value adjusting device and seawater degassing, wherein the seawater can enter a nanofiltration device for filtration after being treated by a complicated and lengthy pretreatment process.
In the existing scheme aiming at seawater desalination treatment, in particular to a patent of coupling nanofiltration with reverse osmosis, ultrafiltration or a complex pretreatment process is needed to reduce the phenomena of fouling and scaling in the treatment process before seawater enters a nanofiltration device, so that the stable operation of the whole system is ensured. In the nanofiltration and reverse osmosis coupling process, the seawater still contains calcium and magnesium ions with higher concentration after nanofiltration treatment, and the scaling risk still exists in the subsequent high-power concentration process. After the nanofiltration produced water is treated by adopting the ion exchange resin, the scaling risk caused by calcium and magnesium ions can be completely eliminated. Since the ion exchange resin needs to be regenerated after being saturated by adsorption, how to realize low-cost regeneration of the ion exchange resin for ion desalination is a technical challenge. In the current seawater patent, no report is found that a reverse osmosis membrane is directly adopted to directly concentrate until the concentration of sodium chloride is 15% -18%, and then multi-stage flash evaporation or MVR evaporation crystallization is adopted.
SUMMERY OF THE UTILITY MODEL
The utility model provides a high-efficiency seawater comprehensive utilization system aiming at the technical defects of seawater desalination by a conventional double-membrane method, ions causing subsequent reverse osmosis membrane scaling are removed by a nanofiltration membrane and an ion exchange resin, the reverse osmosis membrane can realize high-power concentration of seawater under the condition of not adding any scale inhibitor, and the concentrated high-concentration seawater is used for regenerating the ion exchange resin, so that the regeneration cost of the ion exchange resin is greatly reduced, the scaling ions are efficiently removed by the nanofiltration and the ion exchange resin at low cost, and the stable operation of the subsequent reverse osmosis unit is ensured. The concentration of the reverse osmosis concentrated water is as high as 15-18%, the impurity content is extremely low, the treatment by the hair growing crystallization process is facilitated, and sodium chloride and fresh water are obtained simultaneously.
The technical scheme for solving the technical problems is as follows: the utility model provides a high-efficient sea water comprehensive utilization system, this system is by the dull and stereotyped unit of receiving of straining, ion exchange unit, formula of book reverse osmosis membrane unit, high-pressure dull and stereotyped reverse osmosis unit, the dull and stereotyped reverse osmosis unit of superhigh pressure and the evaporative crystallization unit that links up in proper order constitutes, wherein:
the membrane element structure of the flat nanofiltration unit adopts disc-tube nanofiltration DTNF or rotational flow disc-tube nanofiltration CDNF, and the nanofiltration membrane adopted by the flat nanofiltration unit is a piperazine system nanofiltration membrane;
the ion exchange unit adopts sodium type cation exchange resin;
the roll type reverse osmosis membrane unit adopts a roll type reverse osmosis membrane element, and a filtering membrane adopted by the roll type reverse osmosis membrane unit is a reverse osmosis membrane;
the filtering membranes adopted by the high-pressure flat plate membrane reverse osmosis unit and the ultrahigh-pressure flat plate reverse osmosis unit are reverse osmosis membranes;
the evaporative crystallization unit adopts an MVR evaporator or a multi-stage flash evaporator.
Furthermore, a self-cleaning filter and a security filter are arranged in front of the flat nanofiltration unit and are used for carrying out pretreatment on seawater to remove silt and impurities.
Furthermore, a shallow air flotation unit is arranged in front of the self-cleaning filter and used for removing algae in seawater.
Furthermore, the flat-plate nanofiltration unit is used for separating and treating seawater to remove most of sulfate radicals, partial calcium ions, partial magnesium ions and macromolecular suspended matters.
Furthermore, the nanofiltration membrane adopted by the flat plate nanofiltration unit is an electronegative nanofiltration membrane, seawater is treated by the electronegative nanofiltration membrane, and bivalent SO in the seawater is intercepted4 2-Ions.
Further, the ion exchange unit is used for removing residual calcium and magnesium ions in the water produced by the flat-plate nanofiltration unit.
Furthermore, the roll type reverse osmosis membrane unit is used for concentrating the produced water of the ion exchange unit until the content of sodium chloride is 6-7%, and the produced water enters the produced water collecting pipe.
Further, the high-pressure flat reverse osmosis unit is used for concentrating concentrated water of the roll reverse osmosis unit until the content of sodium chloride is 10-12%, and the produced water selectively enters a produced water collecting pipe according to water quality or enters a secondary reverse osmosis system for further treatment and then is converged into a produced water collecting pipe;
the ultrahigh pressure flat plate reverse osmosis unit is used for concentrating the concentrated water of the high pressure flat plate reverse osmosis unit until the content of sodium chloride is 15-18%, the produced water enters the secondary reverse osmosis system for further treatment and then flows into the produced water collecting pipe, and the secondary reverse osmosis concentrated water is mixed with the produced water of the ion exchange unit and then enters the roll type reverse osmosis;
the evaporation crystallization unit is used for evaporating and crystallizing the concentrated water of the ultrahigh pressure flat plate reverse osmosis unit to obtain sodium chloride with the purity of at least 99.1%.
Furthermore, the structure of the membrane element of the flat nanofiltration unit is a spiral-flow flat membrane, and the magnesium sulfate rejection rate is more than or equal to 94%;
the reverse osmosis membranes adopted by the roll type reverse osmosis membrane unit and the high-pressure flat reverse osmosis unit are high-desalination-rate seawater desalination membranes, and the rejection rate of sodium chloride is more than or equal to 99%;
the reverse osmosis membrane adopted by the ultrahigh pressure flat plate reverse osmosis unit is a high pressure resistant low desalting reverse osmosis membrane, and the rejection rate of sodium chloride is more than or equal to 80%;
and a second-stage reverse osmosis unit for the ultrahigh-pressure reverse osmosis produced water, wherein the second-stage reverse osmosis adopts a low-pressure reverse osmosis membrane, and the removal rate of sodium chloride is more than or equal to 95%.
Furthermore, the ion exchange units are divided into two or more paths which are connected in parallel, when one ion exchange unit works, the rest ion exchange units are in a regeneration state, the sodium chloride concentrated brine used for regenerating the ion exchange resin is the concentrated brine of the ultrahigh pressure flat plate reverse osmosis unit,
the concentrated water of the ultra-high pressure flat plate reverse osmosis unit is used as liquid salt or is subjected to evaporative crystallization to prepare high-purity sodium chloride.
The utility model has the following beneficial effects:
the first flat nanofiltration unit membrane element filtering membrane adopts a negatively charged nanofiltration membrane which can intercept most of SO in seawater4 2-The retention rate of ions and sulfate radicals is more than or equal to 96 percent, so that the concentrated water contains a large amount of MgSO4、CaSO4The sulfate with higher purity can be obtained by seed crystal treatment; the structural form of the membrane element adopted by the flat nanofiltration unit is flat plate type, the structural forms of the membrane element which can be adopted are disc tube type (DTNF) and rotational flow disc tube type (CDNF), and the rotational flow disc tube type is preferably selected due to smaller pressure drop of the CDNF; compared with the traditional roll-type nanofiltration membrane element, the membrane element has higher pollution blockage resistance, so that special pretreatment is not needed before seawater enters CDNF;
and secondly, sodium ion exchange resin is adopted to remove calcium and magnesium ions in the produced water of the flat nanofiltration unit, and as colloid and macromolecular organic matters in the seawater are removed by the nanofiltration membrane, the ion exchange resin has extremely high working efficiency and is not easy to reduce the adsorption efficiency due to the adsorption of the colloid and the macromolecular organic matters. The ion exchange resin can be regenerated by adopting concentrated water of an ultrahigh pressure flat plate unit, and the operation and maintenance cost is low;
thirdly, the water produced by the ion exchange unit does not contain sulfate radicals and calcium and magnesium ions basically, substances such as scale inhibitors and the like do not need to be added in the process of concentration by using the rolled reverse osmosis membrane unit and the flat reverse osmosis membrane, when the water produced by the ion exchange unit is concentrated to 15-18% of sodium chloride by the reverse osmosis membrane, the concentrated brine is very pure, the subsequent multi-stage flash evaporation and MVR (mechanical vapor recompression) evaporative crystallization are favorably adopted to prepare high-purity sodium chloride, and the evaporation efficiency is high;
compared with the prior art, the method has the advantages that the coupling mode of the flat nanofiltration membrane, the ion exchange resin, the roll type reverse osmosis, the high-pressure flat reverse osmosis, the ultrahigh-pressure flat reverse osmosis and the evaporative crystallization system is innovatively adopted, the seawater desalination and the comprehensive utilization of salt are realized, high-quality fresh water is obtained, high-quality sodium chloride can be obtained, the water production cost of the seawater desalination is greatly reduced, and the method is the seawater desalination method with great social benefit and economic benefit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.
Fig. 1 is a schematic view of a high-efficiency seawater comprehensive utilization system provided in an embodiment of the present invention.
In the figure, 1, a flat plate nanofiltration unit; 2. an ion exchange unit; 3. a roll-type reverse osmosis membrane unit; 4. a high pressure flat reverse osmosis unit; 5. an ultra-high pressure flat reverse osmosis unit; 6. an evaporative crystallization unit; 7. a self-cleaning filter; 8. a cartridge filter; 9. shallow layer air supporting unit.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, a high-efficiency seawater comprehensive utilization system is provided, which is composed of a flat nanofiltration unit 1, an ion exchange unit 2, a roll type reverse osmosis membrane unit 3, a high-pressure flat reverse osmosis unit 4, an ultrahigh-pressure flat reverse osmosis unit 5 and an evaporative crystallization unit 6, which are connected in sequence, wherein:
the membrane element structure of the flat nanofiltration unit 1 adopts disc-tube nanofiltration DTNF or rotational flow disc-tube nanofiltration CDNF, and the nanofiltration membrane adopted by the flat nanofiltration unit 1 is a piperazine system nanofiltration membrane;
the ion exchange unit 2 adopts sodium type cation exchange resin;
the roll type reverse osmosis membrane unit 3 adopts a roll type reverse osmosis membrane element, and a filtering membrane adopted by the roll type reverse osmosis membrane unit 3 is a reverse osmosis membrane;
the filtering membranes adopted by the high-pressure flat plate membrane reverse osmosis unit and the ultrahigh-pressure flat plate reverse osmosis unit 5 are reverse osmosis membranes;
the evaporative crystallization unit 6 adopts an MVR evaporator or a multi-stage flash evaporator.
In this embodiment, a self-cleaning filter 7 and a security filter 8 are arranged in front of the flat nanofiltration unit 1, and the self-cleaning filter 7 and the security filter 8 are used for performing seawater pretreatment to remove silt and impurities. A shallow air flotation unit 9 is arranged in front of the self-cleaning filter 7, and the shallow air flotation unit 9 is used for removing algae in seawater.
In this example, the flat nanofiltration sheetThe unit 1 is used for separating and treating seawater to remove most of sulfate radicals, partial calcium ions, partial magnesium ions and macromolecular suspended matters. The nanofiltration membrane adopted by the flat plate nanofiltration unit 1 is an electronegative nanofiltration membrane, the negative nanofiltration membrane is used for treating seawater and intercepting bivalent SO in the seawater4 2-Ions.
In this embodiment, the ion exchange unit 2 is used to remove calcium and magnesium ions remaining in the water produced by the flat nanofiltration unit 1. The roll type reverse osmosis membrane unit 3 is used for concentrating the water produced by the ion exchange unit 2 until the content of sodium chloride is 6-7%, and the produced water enters the produced water collecting pipe.
In the embodiment, the high-pressure flat reverse osmosis unit 4 is used for concentrating concentrated water of the roll reverse osmosis membrane unit 3 until the content of sodium chloride is 10-12%, and the produced water enters a produced water collecting pipe according to water quality selection or enters a secondary reverse osmosis system for further treatment and then is converged into the produced water collecting pipe;
the ultrahigh pressure flat plate reverse osmosis unit 5 is used for concentrating the concentrated water of the high pressure flat plate reverse osmosis unit 4 until the content of sodium chloride is 15-18%, the produced water enters a secondary reverse osmosis system for further treatment and then flows into a produced water collecting pipe, and the secondary reverse osmosis concentrated water is mixed with the produced water of the ion exchange unit 2 and then enters roll type reverse osmosis;
the evaporation crystallization unit 6 is used for evaporating and crystallizing the concentrated water of the ultrahigh pressure flat plate reverse osmosis unit 5 to obtain sodium chloride with the purity of at least 99.1%.
In the embodiment, the membrane element of the flat nanofiltration unit 1 is a spiral-flow flat membrane, and the magnesium sulfate rejection rate is not less than 94%;
the reverse osmosis membranes adopted by the roll type reverse osmosis membrane unit 3 and the high-pressure flat reverse osmosis unit 4 are high-desalination rate seawater desalination membranes, and the rejection rate of sodium chloride is more than or equal to 99%;
the reverse osmosis membrane adopted by the ultrahigh-pressure flat reverse osmosis unit 5 is a high-pressure-resistant low-desalination reverse osmosis membrane, and the rejection rate of sodium chloride is more than or equal to 80%;
and a second-stage reverse osmosis unit for the ultrahigh-pressure reverse osmosis produced water, wherein the second-stage reverse osmosis adopts a low-pressure reverse osmosis membrane, and the removal rate of sodium chloride is more than or equal to 95%.
In the embodiment, the ion exchange unit 2 is divided into two or more paths which are connected in parallel, when one ion exchange unit 2 works, the rest ion exchange units 2 are in a regeneration state, sodium chloride concentrated brine used for regenerating ion exchange resin is ultrahigh pressure flat reverse osmosis unit 5 concentrated water,
the concentrated water of the ultra-high pressure flat reverse osmosis unit 5 is used as liquid salt or is subjected to evaporative crystallization to prepare high-purity sodium chloride.
Specifically, the high-efficiency seawater desalination treatment method implemented by using the system comprises the following steps:
firstly, separating and treating seawater by using a flat plate nanofiltration unit 1 to obtain nanofiltration product water and nanofiltration concentrated water, wherein most sulfate radicals, partial calcium and magnesium ions, colloids and macromolecular organic matters are intercepted on the concentrated water side, and partial calcium and magnesium ions penetrate through the nanofiltration membrane and enter the water production side.
And step two, the nanofiltration produced water enters an ion exchange unit 2, calcium and magnesium ions are removed through exchange with sodium ions on ion exchange resin, the ion exchange resin is subjected to concentrated water regeneration through an ultrahigh pressure flat plate reverse osmosis unit 5 after being saturated in adsorption, and when one path of ion exchange resin is in a working state, the other paths of ion exchange resin are in a regeneration state.
Step three, concentrating the water produced by the ion exchange unit 2 to 6-7% in the concentrated water by using a roll type reverse osmosis membrane unit 3, and enabling the produced water to enter a produced water collecting pipe;
concentrating concentrated water of the roll type reverse osmosis membrane unit 3 by means of a high-pressure flat reverse osmosis unit 4 until the content of sodium chloride is 10-12%, and selectively allowing produced water to enter a produced water collecting pipe according to water quality or enter a secondary reverse osmosis system for further treatment and then converging the produced water into the produced water collecting pipe;
step five, concentrating the concentrated water of the high-pressure flat plate reverse osmosis unit 4 by using the ultrahigh-pressure flat plate reverse osmosis unit 5 until the content of sodium chloride is 15-18%, enabling the produced water to enter a secondary reverse osmosis system for further treatment and then flow into a produced water collecting pipe, and enabling the secondary reverse osmosis concentrated water to be mixed with the produced water of the ion exchange unit 2 and then enter roll type reverse osmosis;
and sixthly, enabling concentrated water of the ultrahigh pressure flat reverse osmosis unit 5 to enter an evaporation concentration unit, obtaining high-purity sodium chloride and fresh water through evaporation crystallization, and enabling produced water to flow into the rolled reverse osmosis membrane unit 3 and the high pressure flat reverse osmosis unit 4 to produce water.
In the embodiment, seawater in a smoke platform area is used as raw seawater for treatment, and the main components of the seawater are shown in table 1:
| principal Components | Content (mg/L) |
| Cl- | 18694 |
| SO4 2- | 2400 |
| Ca2+ | 412 |
| Mg2+ | 1276 |
| Na+ | 10430 |
TABLE 1 major constituents of seawater in the tobacco field
The original seawater is subjected to sand filtration to remove suspended matters, then is subjected to cartridge filter 8 to remove large-particle substances, and then enters flat nanofiltration unit 1, and the membrane element structure of flat nanofiltration unit 1 adopts a rotational flow disc tube type nanofiltration CDNF.
The original seawater enters the flat nanofiltration unit 1 for treatment, the recovery rate of the system can be controlled at 85 percent at most, most of sulfate radicals and part of calcium and magnesium ions are removed, and the main components of the water produced by the flat nanofiltration unit 1 are shown in the table 2:
| principal Components | Content (mg/L) |
| Cl- | 16545 719 |
| SO4 2- | 10 |
| Ca2+ | 304 7.6 |
| Mg2+ | 403 16.8 |
| Na+ | 9620 |
| TDS | 26900 |
TABLE 2 Flat nanofiltration Unit Water production principal Components
The nanofiltration produced water enters an ion exchange unit 2 and is passed through ion exchange resin to remove calcium and magnesium ions, and the main components of the produced water of the ion exchange unit 2 are shown in Table 3:
| principal Components | Content (mg/L) |
| Cl- | 17074 |
| SO4 2- | 10 |
| Ca2+ | 8 |
| Mg2+ | 11 |
| Na+ | 11047 |
| TDS | 28150 |
TABLE 3 Water production principal Components of the ion exchange Unit
The water produced by the ion exchange unit 2 enters the roll type reverse osmosis membrane unit 3, and because the contents of sulfate radicals and calcium and magnesium ions in the inlet water of the roll type reverse osmosis membrane unit 3 are extremely low, the system can realize a recovery rate as high as 55% under the condition of not adding a scale inhibitor, the unit desalination rate is 99.5%, and the quality of the concentrated water of the system is shown in a table 4:
| principal Components | Content (mg/L) |
| Cl- | 37752 |
| SO4 2- | 18 |
| Ca2+ | 17 |
| Mg2+ | 24 |
| Na+ | 24426 |
| TDS | 62237 |
TABLE 4 concentrated water quality by rolling reverse osmosis membrane unit
The roll type reverse osmosis membrane unit 3 is used for further concentrating the concentrated water high-pressure flat reverse osmosis unit 4, the recovery rate is 40%, the unit desalination rate is 99.5%, and the quality of the concentrated water of the system is shown in a table 5:
| principal Components | Content (mg/L) |
| Cl- | 62605 |
| SO4 2- | 30 |
| Ca2+ | 28 |
| Mg2+ | 40 |
| Na+ | 40507 |
| TDS | 103200 |
TABLE 5 quality of concentrated water by high pressure plate reverse osmosis unit
Concentrated water of the high-pressure flat plate reverse osmosis unit 4 enters the ultrahigh-pressure flat plate reverse osmosis unit 5 for further concentration, the recovery rate is 45%, the unit desalination rate is 73%, the TDS of produced water is 27860mg/L, the concentrated water directly flows back to an outlet of the ion exchange unit 2, the concentrated water is mixed with ion exchange resin produced water and then enters the roll type reverse osmosis membrane unit 3, the concentrated water of the system directly enters the next-stage evaporative crystallization unit 6, and the quality of the concentrated water of the system is shown in Table 6:
| principal Components | Content (mg/L) |
| Cl- | 99980 |
| SO4 2- | 50 |
| Ca2+ | 48 |
| Mg2+ | 65 |
| Na+ | 64684 |
| TDS | 165870 |
TABLE 6 quality of concentrated water by the ultra-high pressure flat reverse osmosis unit
The ultrahigh pressure flat reverse osmosis unit 5 enters an MVR evaporation crystallization unit 6, the evaporation produced water is converged into a produced water collecting pipe, and the purity of the obtained sodium chloride reaches 99.1%.
In conclusion, the membrane element of the flat nanofiltration unit 1 adopts the nanofiltration membrane with negative charge, and can intercept most of SO in seawater4 2-The retention rate of ions and sulfate radicals is more than or equal to 96 percent, so that the concentrated water contains a large amount of MgSO4、CaSO4The sulfate with higher purity can be obtained by seed crystal treatment; the structural form of the membrane element adopted by the flat nanofiltration unit 1 is a flat plate type, the structural forms of the membrane element which can be adopted are a disc tube type (DTNF) and a rotational flow disc tube type (CDNF), and the rotational flow disc tube type is preferably selected due to the small pressure drop of the CDNF; compared with the traditional roll-type nanofiltration membrane element, the membrane element has higher anti-fouling performance, so that special pretreatment is not needed before seawater enters CDNF. Sodium type ion exchange resin is adopted to remove calcium and magnesium ions in the water produced by the flat nanofiltration unit 1, and as colloid and macromolecular organic matters in seawater are removed by the nanofiltration membrane, the ion exchange resin has extremely high working efficiency, and is not easy to reduce the adsorption efficiency due to the adsorption of the colloid and the macromolecular organic matters. The ion exchange resin can adopt concentrated water inlet of an ultrahigh pressure flat plate unitThe regeneration is carried out, and the operation and maintenance cost is low; the water produced by the ion exchange unit 2 does not contain sulfate radicals and calcium and magnesium ions basically, and in the process of utilizing the rolled reverse osmosis membrane unit 3 and the flat reverse osmosis membrane for concentration, substances such as any scale inhibitor do not need to be added, when the water produced by the ion exchange unit 2 is concentrated to 15-18% of sodium chloride through the reverse osmosis membrane, the concentrated brine is very pure, the subsequent multistage flash evaporation and MVR evaporative crystallization are adopted to prepare high-purity sodium chloride, and the evaporation efficiency is high. Compared with the prior art, the method has the advantages that the coupling mode of the flat nanofiltration membrane, the ion exchange resin, the roll type reverse osmosis, the high-pressure flat reverse osmosis, the ultrahigh-pressure flat reverse osmosis and the evaporative crystallization system is innovatively adopted, the seawater desalination and the comprehensive utilization of salt are realized, high-quality fresh water is obtained, high-quality sodium chloride can be obtained, the water production cost of the seawater desalination is greatly reduced, and the method is the seawater desalination method with great social benefit and economic benefit.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the utility model. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The utility model provides a high-efficient sea water comprehensive utilization system which characterized in that: the system consists of a flat nanofiltration unit (1), an ion exchange unit (2), a roll type reverse osmosis membrane unit (3), a high-pressure flat reverse osmosis unit (4), an ultrahigh-pressure flat reverse osmosis unit (5) and an evaporative crystallization unit (6) which are sequentially connected, wherein:
the membrane element structure of the flat nanofiltration unit (1) adopts disc-tube nanofiltration DTNF or rotational flow disc-tube nanofiltration CDNF, and the nanofiltration membrane adopted by the flat nanofiltration unit (1) is a piperazine system nanofiltration membrane;
the ion exchange unit (2) adopts sodium type cation exchange resin;
the roll type reverse osmosis membrane unit (3) adopts a roll type reverse osmosis membrane element, and a filtering membrane adopted by the roll type reverse osmosis membrane unit (3) is a reverse osmosis membrane;
the filtering membranes adopted by the high-pressure flat plate membrane reverse osmosis unit and the ultrahigh-pressure flat plate reverse osmosis unit (5) are reverse osmosis membranes;
the evaporative crystallization unit (6) adopts an MVR evaporator or a multi-stage flash evaporator.
2. The efficient comprehensive seawater utilization system of claim 1, wherein: a self-cleaning filter (7) and a security filter (8) are arranged in front of the flat nanofiltration unit (1), and the self-cleaning filter (7) and the security filter (8) are used for carrying out pretreatment on seawater to remove silt and impurities.
3. The system of claim 2, wherein: a shallow air floating unit (9) is arranged in front of the self-cleaning filter (7), and the shallow air floating unit (9) is used for removing algae in seawater.
4. The efficient comprehensive seawater utilization system of claim 1, wherein: the flat nanofiltration unit (1) is used for separating and treating seawater to remove most of sulfate radicals, partial calcium ions, partial magnesium ions and macromolecular suspended matters.
5. The system of claim 4, wherein the system comprises: the nanofiltration membrane adopted by the flat plate nanofiltration unit (1) is an electronegative nanofiltration membrane, seawater is treated by the electronegative nanofiltration membrane, and bivalent SO in the seawater is intercepted4 2-Ions.
6. The system of claim 5, wherein: the ion exchange unit (2) is used for removing residual calcium and magnesium ions in the water produced by the flat nanofiltration unit (1).
7. The system of claim 6, wherein: the roll type reverse osmosis membrane unit (3) is used for concentrating the water produced by the ion exchange unit (2) until the content of sodium chloride is 6-7%, and the produced water enters the produced water collecting pipe.
8. The system of claim 7, wherein: the high-pressure flat reverse osmosis unit (4) is used for concentrating concentrated water of the roll reverse osmosis unit (3) until the content of sodium chloride is 10-12%, and the produced water enters a produced water collecting pipe according to water quality selection or enters a secondary reverse osmosis system for further treatment and then is converged into the produced water collecting pipe;
the ultrahigh-pressure flat reverse osmosis unit (5) is used for concentrating the concentrated water of the high-pressure flat reverse osmosis unit (4) until the content of sodium chloride is 15-18%, the produced water enters a secondary reverse osmosis system for further treatment and then is collected into a produced water collecting pipe, and the secondary reverse osmosis concentrated water is mixed with the produced water of the ion exchange unit (2) and then enters roll-type reverse osmosis;
the evaporation crystallization unit (6) is used for evaporating and crystallizing the concentrated water of the ultrahigh pressure flat plate reverse osmosis unit (5) to obtain sodium chloride with the purity of at least 99.1%.
9. The efficient comprehensive seawater utilization system of claim 1, wherein: the structure of the membrane element of the flat nanofiltration unit (1) is a spiral-flow flat membrane, and the magnesium sulfate rejection rate is more than or equal to 94%;
the reverse osmosis membranes adopted by the roll type reverse osmosis membrane unit (3) and the high-pressure flat reverse osmosis unit (4) are high-desalination-rate seawater desalination membranes, and the rejection rate of sodium chloride is more than or equal to 99%;
the reverse osmosis membrane adopted by the ultra-high pressure flat reverse osmosis unit (5) is a high pressure resistant low desalination reverse osmosis membrane, and the rejection rate of sodium chloride is more than or equal to 80%;
and a second-stage reverse osmosis unit for the ultrahigh-pressure reverse osmosis produced water, wherein the second-stage reverse osmosis adopts a low-pressure reverse osmosis membrane, and the removal rate of sodium chloride is more than or equal to 95%.
10. The efficient comprehensive seawater utilization system of claim 1, wherein: the ion exchange units (2) are divided into two or more paths which are connected in parallel, when one ion exchange unit (2) works, the rest ion exchange units (2) are in a regeneration state, sodium chloride concentrated brine used for regenerating ion exchange resin is ultrahigh-pressure flat plate reverse osmosis unit (5) concentrated water,
the concentrated water of the ultra-high pressure flat reverse osmosis unit (5) is used as liquid salt or is subjected to evaporative crystallization to prepare high-purity sodium chloride.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115925195A (en) * | 2023-01-11 | 2023-04-07 | 上海丰信环保科技有限公司 | Sodium sulfate wastewater concentration treatment and produced water recycling method and system in new energy lithium battery industry |
| CN117735791A (en) * | 2024-02-08 | 2024-03-22 | 威海天辰环保股份有限公司 | Multistage treatment device for industrial high-salinity water desalination |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115925195A (en) * | 2023-01-11 | 2023-04-07 | 上海丰信环保科技有限公司 | Sodium sulfate wastewater concentration treatment and produced water recycling method and system in new energy lithium battery industry |
| CN117735791A (en) * | 2024-02-08 | 2024-03-22 | 威海天辰环保股份有限公司 | Multistage treatment device for industrial high-salinity water desalination |
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