Coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system

Abstract

The utility model provides a coal chemical industry wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system which comprises a front pretreatment system, a reverse osmosis water production system, a strong brine pretreatment system, a nanofiltration salt separation system and an evaporative crystallization system which are arranged in sequence, the front pretreatment system comprises a defluorination and hardness removal reaction tank, a clarification tank, a first ultrafiltration device and a first resin softener which are arranged in sequence; the reverse osmosis water production system comprises a reverse osmosis device; the strong brine pretreatment system comprises a COD (Chemical Oxygen Demand) removal device and a carbon removal tower; the nanofiltration salt separation system comprises a nanofiltration device; the evaporative crystallization system is used for evaporating and crystallizing the salt solution treated by the nanofiltration salt separation system. According to the coal chemical industry wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system, the fluorine and hardness removal reaction tank and the first resin softener form a one-time softening hardness removal technology, and compared with a multi-time softening hardness removal technology in the prior art, the problems that the cost of acid and alkali auxiliary materials is increased and the salt load is increased due to a multi-stage softening hardness removal technology can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of coal chemical wastewater treatment, in particular to a coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system. Background Art

[0002] As an important part of my country's energy structure, coal energy plays a vital role in ensuring the security of my country's energy supply. As a powerful means to achieve efficient utilization of coal resources, the coal chemical industry is directly related to the country's energy strategic development plan. With the implementation of the national "dual carbon" target plan and the continuous improvement of relevant laws and regulations on ecological and environmental protection, zero wastewater discharge in the coal chemical industry has become a basic requirement, especially in areas with dense coal chemical industries where water resources are scarce and water environment capacity is small, and zero wastewater discharge must be achieved.

[0003] However, existing wastewater zero-discharge processes generally have problems such as high operating reagent costs, which restrict the wastewater reuse rate and resource utilization of crystalline salts. Utility Model Content

[0004] The main purpose of the utility model is to provide a coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system, aiming to solve the problems of rising acid and alkali auxiliary material costs and rising salt load in existing wastewater discharge.

[0005] To achieve the above-mentioned purpose, the utility model provides a coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system, including a pre-pretreatment system, a reverse osmosis water production system, a concentrated brine pretreatment system, a nanofiltration salt separation system and an evaporation crystallization system arranged in sequence along the wastewater flow direction, wherein:

[0006] The pre-treatment system includes a defluorination and de-hardness reaction tank, a clarification tank, a first ultrafiltration device and a first resin softener which are arranged in sequence; the reverse osmosis water production system includes a reverse osmosis device; the concentrated brine pretreatment system includes a COD removal device and a carbon removal tower; the nanofiltration salt separation system is used to separate the anions in the reverse osmosis concentrated water; and the evaporation crystallization system is used to evaporate and crystallize the salt solution treated by the nanofiltration salt separation system.

[0007] Preferably, the reverse osmosis device comprises a primary reverse osmosis device and a secondary reverse osmosis device connected in series.

[0008] Preferably, the concentrated brine pretreatment system further comprises a second ultrafiltration device located between the COD removal device and the carbon removal tower.

[0009] Preferably, the concentrated brine pretreatment system further comprises an activated carbon filter and a second resin softener communicated with the outlet of the carbon removal tower.

[0010] Preferably, the nanofiltration salt separation system includes a primary nanofiltration device, a fresh water refining nanofiltration device and a concentrate water refining nanofiltration device respectively connected to the fresh water outlet and concentrate water outlet thereof, the fresh water outlet of the fresh water refining nanofiltration device is connected in sequence to a monovalent salt concentration reverse osmosis device and a fluorine and silicon removal tubular membrane, and the concentrate water outlet of the concentrate refining nanofiltration device is connected to a divalent salt concentrate water activated carbon filter.

[0011] Preferably, the concentrate outlet of the fresh water refining nanofiltration device is also connected to the inlet of the primary nanofiltration device, and the fresh water outlet of the concentrate refining nanofiltration device is connected to the pipeline between the primary nanofiltration device and the fresh water refining nanofiltration device.

[0012] Preferably, the evaporation crystallization system comprises a monovalent salt evaporation crystallizer, a divalent salt evaporation crystallizer, and a miscellaneous salt evaporation crystallizer connected to mother liquor outlets of the monovalent salt evaporation crystallizer and the divalent salt evaporation crystallizer.

[0013] Preferably, the outlet of the fluorine and silicon removal tubular membrane is connected to the inlet of the monovalent salt evaporation crystallizer, the outlet of the divalent salt concentrated water activated carbon filter is connected to the inlet of the divalent salt evaporation crystallizer, and the mother liquor outlets of the monovalent salt evaporation crystallizer and the divalent salt evaporation crystallizer are both connected to the mixed salt evaporation crystallizer.

[0014] Preferably, the first ultrafiltration device and the second ultrafiltration device are both submerged ultrafiltration devices, and the COD removal device is an ozone oxidation COD removal device.

[0015] Preferably, an acid adding mechanism for pH adjustment is installed between the first ultrafiltration device and the first resin softener.

[0016] The utility model proposes a coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation and crystallization treatment system, the pre-pretreatment system includes a defluorination and hardness removal reaction tank, a clarification tank, an ultrafiltration device and a first resin softener which are arranged in sequence, the defluorination and hardness removal reaction tank and the first resin softener constitute a one-time softening and hardness removal process, compared with the multiple softening and hardness removal technology in the prior art, the total hardness of the first-stage reverse osmosis inlet water can be controlled to be less than 5 mg / L, and at the same time, the problems of increased acid and alkali auxiliary material costs and increased salt load caused by the multi-stage softening and hardness removal process can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a preferred embodiment of the utility model of a coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system;

[0018] Figure 2 This is a schematic diagram of the structure of the pre-treatment system in the utility model of the coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system;

[0019] Figure 3It is a schematic diagram of the structure of the reverse osmosis water production system in the utility model of the coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system;

[0020] Figure 4 It is a structural schematic diagram of a concentrated brine pretreatment system in the utility model of the coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system;

[0021] Figure 5 It is a structural schematic diagram of the nanofiltration salt separation system in the utility model coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system;

[0022] Figure 6 It is a structural schematic diagram of the evaporation crystallization system in the utility model of the coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system.

[0023] In the figure, 1-pre-pretreatment system, 11-fluorine removal and hardness removal reaction tank, 12-clarification tank, 13-first ultrafiltration device, 14-first resin softener, 2-reverse osmosis water production system, 21-first reverse osmosis device, 22-second reverse osmosis device, 3-concentrated brine pretreatment system, 31-COD removal device, 32-second ultrafiltration device, 33-carbon removal tower, 34-activated carbon filter, 35-second resin softener, 4-nanofiltration salt separation system, 41-first nanofiltration device, 42-concentrated water refining nanofiltration device, 43-divalent salt concentrated water activated carbon filter, 44-fresh water refining nanofiltration device, 45-monovalent salt concentration reverse osmosis device, 46-fluorine removal and silicon removal tubular membrane, 5-evaporation crystallization system, 51-divalent salt evaporation crystallizer, 52-monovalent salt evaporation crystallizer, 53-miscellaneous salt evaporation crystallizer.

[0024] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] It should be noted that in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the 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 cannot be understood as limiting the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] In this preferred embodiment, refer to Figures 1 to 6 A coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system, comprising a pre-pretreatment system 1, a reverse osmosis water production system 2, a concentrated brine pretreatment system 3, a nanofiltration salt separation system 44 and an evaporation crystallization system 5 arranged in sequence along the wastewater flow direction, wherein:

[0028] The pre-pretreatment system 1 is used to remove large-particle impurities in the wastewater and calcium, magnesium and fluoride ion precipitates formed after the addition of drugs, and includes a defluorination and de-hardness removal reaction tank 11, a clarification tank 12, a first ultrafiltration device 13 and a first resin softener 14 arranged in sequence; the reverse osmosis water production system 2 is used to produce recycled water that meets the water quality standards of industrial circulating cooling water and make-up water, and includes a reverse osmosis device; the brine pretreatment system 3 is used to remove COD and free CO2 in the reverse osmosis brine, and includes a COD removal device 31 and a carbon removal tower 33; the nanofiltration salt separation system 44 is used to separate the anions in the reverse osmosis brine; the evaporation crystallization system 5 is used to evaporate and crystallize the salt solution treated by the nanofiltration salt separation system 44.

[0029] Specifically, in this embodiment, referring to Figure 3 The reverse osmosis device includes a primary reverse osmosis device 21 and a secondary reverse osmosis device 22 connected in series.

[0030] Further, refer to Figure 4 The concentrated brine pretreatment system 3 further includes a second ultrafiltration device 32 located between the COD removal device 31 and the carbon removal tower 33. The concentrated brine pretreatment system 3 further includes an activated carbon filter 34 connected to the outlet of the carbon removal tower 33 and a second resin softener 35.

[0031] In this embodiment, in order to ensure the stable operation of the nanofiltration membrane and the quality of the crystallized salt product, a concentrated brine pretreatment system 3 is designed before the nanofiltration salt separation system 44 .

[0032] Specifically, in this embodiment, referring to Figure 5 The nanofiltration salt separation system 4 includes a primary nanofiltration device 41, a fresh water refining nanofiltration device 44 and a concentrate refining nanofiltration device 42 respectively connected to the fresh water outlet and concentrate outlet thereof; the fresh water outlet of the fresh water refining nanofiltration device 44 is connected in sequence to a monovalent salt concentration reverse osmosis device 45 and a fluorine and silicon removal tubular membrane 46; the concentrate outlet of the concentrate refining nanofiltration device 42 is connected to a divalent salt concentrate activated carbon filter 43.

[0033] By designing a fluorine and silicon removal tubular membrane 46 and a divalent salt concentrated water activated carbon filter 43 at the end of the nanofiltration salt separation system 44, the COD, TOC and hardness indicators of the influent of the nanofiltration salt separation system 44 are controlled to meet the subsequent process requirements, and the problems of nanofiltration membrane scaling and blockage and excessive total organic carbon in the crystallized salt product are solved. At the same time, a fresh water refining nanofiltration device 44 and a concentrated water refining nanofiltration device 42 are designed after the primary nanofiltration device 41 to reduce the impurity salt content of the monovalent salt and divalent salt solutions, so as to improve the purity of the crystallized salt and reduce the impurity salt rate.

[0034] Furthermore, the concentrate outlet of the fresh water refining nanofiltration device 44 is also connected to the inlet of the primary nanofiltration device 41 , and the fresh water outlet of the concentrate refining nanofiltration device 42 is connected to the pipeline between the primary nanofiltration device 41 and the fresh water refining nanofiltration device 44 .

[0035] In this embodiment, refer to Figure 6 The evaporation crystallization system 5 includes a monovalent salt evaporation crystallizer 52, a divalent salt evaporation crystallizer 51, and a mixed salt evaporation crystallizer 53 connected to the mother liquid outlets of the monovalent salt evaporation crystallizer 52 and the divalent salt evaporation crystallizer 51. The outlet of the fluorine and silicon removal tubular membrane 46 is connected to the inlet of the monovalent salt evaporation crystallizer 52, the outlet of the divalent salt concentrated water activated carbon filter 43 is connected to the inlet of the divalent salt evaporation crystallizer 51, and the mother liquid outlets of the monovalent salt evaporation crystallizer 52 and the divalent salt evaporation crystallizer 51 are both connected to the mixed salt evaporation crystallizer 53. The first ultrafiltration device 13 and the second ultrafiltration device 32 are both submerged ultrafiltration devices, and the COD removal device 31 is an ozone oxidation COD removal device.

[0036] Furthermore, an acid adding mechanism for pH adjustment is installed between the first ultrafiltration device 13 and the first resin softener 14. The acid adding mechanism is arranged behind the ultrafiltration device, and the unsettled Ca(OH)2 and Mg(OH)2 colloids are intercepted by the ultrafiltration membrane, thereby solving the problem of scale and blockage of the reverse osmosis membrane in the reverse osmosis water production system 2.

[0037] The working process of this coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system is as follows.

[0038] Wastewater enters the pre-treatment system 1 to remove large-size impurities and calcium, magnesium, and fluoride ion precipitates formed after dosing. Sodium carbonate, sodium hydroxide, polyaluminum chloride, and polyacrylamide are added to the dosing reaction tank, and the main reactions are the precipitation reaction of calcium and magnesium ions and the polymerization and flocculation reaction of small particle precipitates. Then the wastewater enters the clarification tank 12 to remove the precipitate, and then enters the ultrafiltration device for physical filtration. Finally, the wastewater enters the first resin softener 14 for ion exchange, and the calcium and magnesium ions in the water are exchanged with the functional ions on the resin and adsorbed by the resin.

[0039] The solution from the pre-treatment system 1 enters the reverse osmosis water production system 2 for secondary filtration, thereby producing recycled water that meets the water quality standards for industrial circulating cooling water and make-up water.

[0040] The wastewater retained in the reverse osmosis water production system 2 enters the concentrated brine pretreatment system 3 to remove COD and free CO2, and reduce the total hardness of the concentrated water before entering the nanofiltration salt separation. Specifically, the ozone oxidation device is used to remove COD from the concentrated brine. Since the reverse osmosis treatment will simultaneously concentrate the COD on the concentrated brine side, in order to ensure the quality of the concentrated brine evaporation crystallization salt product, the COD needs to be reduced. The second ultrafiltration device 32 is used to filter the large particle impurities produced by the ozone oxidation device. The carbon removal tower 33 is used to remove carbonate ions in the concentrated brine to prevent subsequent scaling of the nanofiltration membrane. The activated carbon filter 34 is used to further adsorb and remove residual COD. The second resin softener 35 is used to further remove hardness, remove calcium and magnesium ions, and prevent subsequent scaling of the nanofiltration membrane. Because the reverse osmosis treatment will simultaneously concentrate the calcium and magnesium ions on the concentrated brine side, the hardness of the concentrated brine exceeds the process requirements.

[0041] The nanofiltration salt separation system 44 is used to separate the monovalent anions (chloride ions) and divalent anions (sulfate ions) in the reverse osmosis concentrate. The reverse osmosis concentrate first enters the primary nanofiltration device 41 for preliminary salt separation treatment. The primary nanofiltration permeate containing chloride ions is transported to the fresh water refining nanofiltration device 44 for further treatment, and then sent to the monovalent salt concentration reverse osmosis for concentration treatment, and then sent to the fluorine removal and silicon removal tubular membrane 46 for fluorine removal and silicon removal treatment. The primary nanofiltration concentrate containing sulfate ions is sent to the concentrate refining nanofiltration device 42 for further concentration treatment, and then sent to the divalent salt concentrate activated carbon filter 43 to remove COD, and the monovalent salt solution and the divalent salt solution are concentrated and reduced to the required indicators for evaporation and crystallization.

[0042] The evaporation crystallization system 5 is used to perform evaporation crystallization treatment on the concentrated and reduced monovalent salt solution (sodium chloride) and divalent salt solution (sodium sulfate) and evaporation mother liquor, so as to obtain crystallized salt products and impurity salts.

[0043] The coal chemical wastewater membrane concentration and concentrate nanofiltration salt separation and crystallization treatment system proposed in this embodiment, the pre-pretreatment system 1 includes a defluorination and hardness removal reaction tank 11, a clarification tank 12, an ultrafiltration device and a first resin softener 14 arranged in sequence, the defluorination and hardness removal reaction tank 11 and the first resin softener 14 constitute a one-time softening and hardness removal process. Compared with the multiple softening and hardness removal technology in the prior art, the total hardness of the first-stage reverse osmosis inlet water can be controlled to be less than 5 mg / L, and at the same time, the problems of increased acid and alkali auxiliary material costs and increased salt load caused by the multi-stage softening and hardness removal process can be solved.

[0044] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system, characterized in that: It includes a pre-treatment system, a reverse osmosis water production system, a concentrated brine pretreatment system, a nanofiltration salt separation system and an evaporation crystallization system, which are arranged in sequence along the wastewater flow direction. The pre-treatment system includes a defluorination and de-hardness reaction tank, a clarification tank, a first ultrafiltration device and a first resin softener which are arranged in sequence; the reverse osmosis water production system includes a reverse osmosis device; the concentrated brine pretreatment system includes a COD removal device and a carbon removal tower; the nanofiltration salt separation system is used to separate the anions in the reverse osmosis concentrated water; and the evaporation crystallization system is used to evaporate and crystallize the salt solution treated by the nanofiltration salt separation system.

2. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 1, characterized in that: The reverse osmosis device comprises a primary reverse osmosis device and a secondary reverse osmosis device connected in series.

3. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 1, characterized in that: The concentrated brine pretreatment system also includes a second ultrafiltration device located between the COD removal device and the carbon removal tower.

4. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 1, characterized in that: The concentrated brine pretreatment system also includes an activated carbon filter and a second resin softener communicated with the outlet of the carbon removal tower.

5. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 1, characterized in that: The nanofiltration salt separation system includes a primary nanofiltration device, a fresh water refining nanofiltration device and a concentrated water refining nanofiltration device respectively connected to the fresh water outlet and concentrated water outlet thereof, the fresh water outlet of the fresh water refining nanofiltration device is connected in sequence to a monovalent salt concentration reverse osmosis device and a fluorine and silicon removal tubular membrane, and the concentrated water outlet of the concentrated water refining nanofiltration device is connected to a divalent salt concentrated water activated carbon filter.

6. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 5, characterized in that: The concentrate outlet of the fresh water refining nanofiltration device is also connected to the inlet of the first-stage nanofiltration device, and the fresh water outlet of the concentrate refining nanofiltration device is connected to the pipeline between the first-stage nanofiltration device and the fresh water refining nanofiltration device.

7. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 6, characterized in that: The evaporation crystallization system comprises a monovalent salt evaporation crystallizer, a divalent salt evaporation crystallizer, and a miscellaneous salt evaporation crystallizer connected to mother liquor outlets of the monovalent salt evaporation crystallizer and the divalent salt evaporation crystallizer.

8. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 7, characterized in that: The outlet of the defluorination and desiliconization tubular membrane is connected to the inlet of the monovalent salt evaporation crystallizer, the outlet of the divalent salt concentrated water activated carbon filter is connected to the inlet of the divalent salt evaporation crystallizer, and the mother liquor outlets of the monovalent salt evaporation crystallizer and the divalent salt evaporation crystallizer are both connected to the mixed salt evaporation crystallizer.

9. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to claim 3, characterized in that: The first ultrafiltration device and the second ultrafiltration device are both submerged ultrafiltration devices, and the COD removal device is an ozone oxidation COD removal device.

10. The coal chemical wastewater membrane concentration and concentrated water nanofiltration salt separation crystallization treatment system according to any one of claims 1 to 9, characterized in that: An acid adding mechanism for pH adjustment is installed between the first ultrafiltration device and the first resin softener.

Images