CN214141977U - Treatment system for treating desulfurization wastewater by using de-hardening electrodialysis - Google Patents
Treatment system for treating desulfurization wastewater by using de-hardening electrodialysis Download PDFInfo
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- CN214141977U CN214141977U CN202022694842.5U CN202022694842U CN214141977U CN 214141977 U CN214141977 U CN 214141977U CN 202022694842 U CN202022694842 U CN 202022694842U CN 214141977 U CN214141977 U CN 214141977U
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Abstract
The utility model relates to an utilize processing system who removes hard electrodialysis and handle desulfurization waste water, including the equalizing basin, the triplex case, ultrafiltration device, the electrodialysis unit, sodium chloride circulation case, the desalination liquid case, the SWRO unit, the RO concentrate case, the chloride concentrate case, the evaporation crystallization unit, sodium salt concentrate case, freezing preparation facilities and receive the membrane unit, the equalizing basin, the triplex case, ultrafiltration device connects gradually, the electrodialysis unit is connected with ultrafiltration device respectively, the sodium chloride circulation case, the desalination liquid case is connected, the desalination liquid case, the SWRO unit is connected, the RO concentrate case connects gradually, the electrodialysis unit, the chloride concentrate case, the evaporation crystallization unit connects gradually, the electrodialysis unit, sodium salt concentrate case, freezing preparation facilities and receive the membrane unit and connect gradually. The utility model discloses a combined process of three headers, ultrafiltration device, electrodialysis unit makes calcium magnesium ion and sulfate radical ion with the enrichment of two kinds of concentrate forms through the electrodialysis unit and handles, avoids the scale deposit problem of electrodialysis unit.
Description
Technical Field
The utility model belongs to the technical field of industrial wastewater treatment, concretely relates to utilize processing system who removes hard electrodialysis and handle desulfurization waste water.
Background
With the rapid development of modern industry in China, environmental problems are continuously highlighted, and pollution events such as atmosphere, water, soil and the like are forbidden frequently. Due to the problem of shortage of water resources, zero discharge of wastewater is of great concern. In industrial development, economic benefits are obtained by sacrificing the environment, and national environmental protection departments advocate industrial enterprises to strictly implement the desulfurization wastewater technology and achieve the zero emission goal.
The flue gas desulfurization of the coal-fired power plant mainly adopts a limestone-gypsum wet process, and desulfurization wastewater which is acidic, high in salinity, high in hardness, strong in corrosivity, easy to scale and contains various heavy metals can be generated in the process. The wastewater pollutant composition is complex, and the fluctuation of water quality and water content is large. The power plant generally adopts traditional 'triple-box' (neutralization, precipitation, clarification) technology to handle it, but the treatment effeciency is lower, and is poor to the effect of getting rid of waste water total solubility solid (TDS), calcium magnesium scale formation factor, chloride, often is difficult to realize the steady operation of treatment process and handles up to standard discharge of waste water product.
With the gradual rise of zero discharge technologies such as membrane separation, evaporative crystallization and the like, the zero discharge of waste water of power plants is gradually promoted. However, the desulfurization waste water, one of the most difficult end waste water to treat and reuse in power plants, is still the key factor for restricting the zero discharge of the waste water in the whole plant. The power plant desulfurization wastewater has the characteristic of high magnesium content, the mass concentration of Mg2+ generally reaches more than 5000 Mg/L, and meanwhile, the wastewater contains a large amount of Ca2+, SO 42-and a certain amount of Ba2+, Sr2+ and SiO2, SO that the hardness is high, and equipment scaling is easily caused. The desulfurization wastewater is weakly acidic, TDS fluctuates within the range of 30000-50000 mg/L, and contains high-concentration Cl < - >, and the desulfurization wastewater is strong in corrosivity, wherein the contents of Hg, Pb, Ni, As, Cd, Cr and other heavy metal ions exceed the standard, and the desulfurization wastewater is strong in toxicity. The desulfurization wastewater also contains a certain amount of COD, which is caused by main organic matters and reducing inorganic matters (sulfite and thiosulfate). The characteristics of the desulfurization wastewater easily cause pollution, scaling, blockage, oxidation and the like of a filter material (membrane material), and provide high requirements for the corrosion resistance of equipment and pipeline (particularly evaporative crystallizer) materials. If hardness removal is not thorough, scaling is easy to form in the concentration section, so that the membrane system cannot normally operate. The existing treatment method is to convert the magnesium hardness into calcium hardness by adding lime into a pretreatment reaction tank, and then adding a sodium carbonate medicament into a coagulation tank to form calcium carbonate precipitate. However, the double-alkali softening treatment has high medicament cost, a large amount of softened sludge is generated and needs to be treated separately, the operation cost is increased, the flow of the whole process is complex, and a large amount of equipment investment is needed. Aiming at the high-magnesium hard desulfurization wastewater, a treatment system which does not need medicament softening is urgently needed.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to overcome the not enough of existence among the above-mentioned prior art to provide an utilize the processing system who removes hard electrodialysis and handle desulfurization waste water.
The utility model provides a technical scheme that its technical problem adopted is:
the utility model provides an utilize processing system who removes hard electrodialysis and handle desulfurization waste water, including the equalizing basin, the third header, ultrafiltration device, the electrodialysis unit, sodium chloride circulation case, the desalination liquid case, SWRO unit and RO dense water tank, the equalizing basin, the third header, ultrafiltration device connects gradually, be connected with first passageway on the electrodialysis unit respectively, the second passageway, the fifth passageway, first passageway one end is connected with ultrafiltration device, second passageway one end is connected with the sodium chloride circulation case, fifth passageway one end is connected with the desalination liquid case, the desalination liquid case passes through the overflow pipe with the SWRO unit and is connected, the SWRO unit is connected with the RO dense water tank, the RO dense water tank is connected with the equalizing basin.
Further, the treatment system also comprises a chloride concentrated solution tank and an evaporative crystallization unit connected with the chloride concentrated solution tank, and the chloride concentrated solution tank is connected with the electrodialysis unit through a third channel.
Furthermore, the treatment system also comprises a sodium salt concentrated solution tank, a freezing preparation device and a nanofiltration membrane unit which are connected in sequence, wherein the sodium salt concentrated solution tank is connected with the electrodialysis unit through a fourth channel, and the nanofiltration membrane unit is connected with the sodium chloride circulation tank.
Furthermore, a supplementary pipeline is connected to the sodium chloride circulation box.
Further, the treatment system includes a water production tank connected to the SWRO unit.
Compared with the prior art, the utility model, have following advantage and effect:
(1) by adopting a combined process of the three headers, the ultrafiltration device and the electrodialysis unit, the softening-free treatment of the high-magnesium hard desulfurization wastewater can be realized, the medicament cost and the sludge treatment cost can be obviously reduced, and the zero-emission process flow is realized.
(2) Calcium, magnesium ions and sulfate ions are enriched in two concentrated solution forms in the working process of the electrodialysis unit, so that the problem of sulfate scaling on the concentrated solution side of the electrodialysis unit can be further avoided.
Drawings
Fig. 1 is a schematic structural diagram of a processing system according to an embodiment of the present invention.
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application.
Detailed Description
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
In the following description, references to the terms "first \ second \ third \ fourth \ fifth" are only to distinguish between similar objects and do not denote a particular order, but rather "first \ second \ third \ fourth \ fifth" may, where permissible, be interchanged with a particular order or sequence so that embodiments of the invention described herein can be practiced in other than the order shown or described herein.
The embodiment of the utility model provides a desulfurization waste water's processing method, the method includes:
a) the desulfurization wastewater is pretreated by a triple box 2 and an ultrafiltration device 3 in sequence, so that the turbidity of the desulfurization wastewater is less than 1 NTU;
b) the pretreated desulfurization wastewater enters an electrodialysis unit 5, and a pre-configured sodium chloride solution is introduced at the same time;
c) after the electrodialysis unit 5 works, the salt content of the liquid in the electrodialysis unit 5 is reduced until the salt content reaches a preset target value, and the salt content overflows to the SWRO unit 7 through the desalting liquid tank 6; simultaneously, after ion exchange, concentrated chloride solution formed by combining chloride ions and various cations and concentrated sodium salt solution formed by combining sodium ions and various anions are respectively discharged from the electrodialysis unit 5;
d) the desulfurization wastewater is desalted by the SWRO unit 7 to form concentrated water and fresh water, the concentrated water is led into the triple box 2 again, and the fresh water is recycled;
e) preparing magnesium chloride salt by evaporating and crystallizing the discharged chloride concentrated solution; the discharged sodium salt concentrated solution is frozen to form mirabilite and clear solution, the clear solution is separated by a nanofiltration membrane unit 14 to obtain fresh water and concentrated water, and the fresh water is reintroduced into the electrodialysis unit 5.
In the step a, the triple box 2 comprises a neutralization box, a sedimentation box and a flocculation box which are connected in sequence. Specifically, adding alkaline lime into a neutralization tank, adjusting the pH value of the wastewater to 9.0-10.0, and converting the magnesium hardness into the calcium hardness; adding sodium carbonate agent to effectively reduce the hardness ions in the water to 1-2 mmol/L and removing most suspended matters in the wastewater in a settling tank; PAM medicament is put into the flocculation tank, so that suspended matters and colloid in the wastewater are flocculated, and mud and water are separated.
In step b of the above method, the concentration of the sodium chloride solution is maintained at about 10%.
In the step b of the method, the desulfurization wastewater is desalted by the SWRO unit 7 to form concentrated water and fresh water, the concentrated water possibly still has high salt content, the concentrated water is output to the triple box 2 for secondary treatment, and the fresh water can be recycled.
In the step c of the method, the SWRO unit 7, namely the reverse osmosis seawater desalination process, has extremely high salt content of the desulfurization wastewater, namely 1 ten thousand to 3 ten thousand mg/L, which is equivalent to the salt content of seawater, and adopts the seawater reverse osmosis technology for desalination, the recovery rate of the SWRO unit 7 can reach 40 to 45 percent, and the recovery rate of the desulfurization wastewater after softening treatment can be further improved.
In the step e of the method, the sodium salt concentrated solution is frozen to form mirabilite and clear liquid, namely, the solubility of Na2SO4 is greatly reduced along with the reduction of the temperature when the temperature is lower than 17.9 ℃ and the highest efficiency point is reached when the temperature is reduced to-5 ℃ by utilizing the difference of components of NaCl and Na2SO4 co-saturated solutions at different temperatures, and most of sodium sulfate is crystallized in a form of Na2SO 4.10H 2O to achieve the purpose of separation.
In the step e of the method, the clear water is separated by the nanofiltration membrane unit 14 to obtain fresh water and concentrated water, the fresh water mainly contains sodium chloride and can be supplemented into the sodium chloride circulation box 4, and the concentrated water mainly contains sodium sulfate.
Based on the above conception, the embodiment of the present invention provides a treatment system for treating desulfurization wastewater by using hard electrodialysis, as shown in fig. 1, comprising
The adjusting tank 1 is used for accumulating the desulfurization wastewater to be treated and adjusting the flow rate of the desulfurization wastewater to ensure the stable output of the desulfurization wastewater;
the triple box 2 is connected with the regulating tank 1 through a pipeline, the desulfurization wastewater is guided into the triple box 2 through the regulating tank 1, and the pH regulation, coagulation and precipitation filtration of the desulfurization wastewater are completed through the triple box 2 (a neutralization box, a settling box and a flocculation box which are sequentially connected);
the ultrafiltration device 3 is connected with the electrodialysis unit 5 through a first channel 91, the wastewater treated by the triple box 2 is introduced into the ultrafiltration device 3 through a pipeline, and the wastewater is filtered in a cross flow mode by utilizing an asymmetric microporous structure and a semipermeable membrane medium and relying on the pressure difference between two sides of the membrane as a driving force;
a sodium chloride circulation box 4 connected to the electrodialysis unit 5 through a second channel 92, for supplying anions and cations required for the filtration process by outputting the prepared sodium chloride solution to the electrodialysis unit 5;
the wastewater enters the electrodialysis unit 5 through the first channel 91, the prepared sodium chloride solution enters the electrodialysis unit 5 through the second channel 92, under the action of the electrodialysis unit 5, anions and cations introduced into the solution are subjected to ion migration, the purposes of desalting and concentrating are achieved through anion and cation exchange membranes respectively, and meanwhile, a chloride concentrated solution formed by combining chloride ions and various cations and a sodium salt concentrated solution formed by combining sodium ions and various anions are formed;
the desalted liquid tank 6 is connected with the electrodialysis unit 5 through a fifth channel 95, and when the salt content of the water liquid in the electrodialysis unit 5 gradually decreases to a preset target value, the water liquid is output from the electrodialysis unit 5 through the fifth channel 95 to the desalted liquid tank 6 for accumulation;
the SWRO unit 7 is connected with the desalted liquid tank 6 through an overflow pipe 96, and the water liquid overflowed from the desalted liquid tank 6 is desalted through the SWRO unit 7 (water desalination reverse osmosis) to obtain fresh water and concentrated water;
an RO concentrate tank 8 connected to the SWRO unit 7 through a pipe and to the adjusting tank 1 through a pipe, for accumulating concentrate treated by the SWRO unit 7 while outputting it to the adjusting tank 1 at a constant rate;
a water production tank 9 connected to the SWRO unit 7 through a pipe for accumulating fresh water processed by the SWRO unit 7 while outputting at a constant rate;
a chloride concentrated solution tank 10 connected to the electrodialysis unit 5 through a third channel 93 for accumulating the chloride concentrated solution treated by the electrodialysis unit 5 while being output at a constant rate;
the evaporative crystallization unit 11 is connected with the chloride concentrated solution tank 10 through an overflow pipe 96, and the chloride concentrated solution overflowing from the chloride concentrated solution tank 10 is subjected to evaporative crystallization through the evaporative crystallization unit 11 to prepare magnesium chloride salt;
a sodium salt concentrated solution tank 12 connected to the electrodialysis unit 5 through a fourth passage 94 for accumulating the sodium salt concentrated solution treated by the electrodialysis unit 5 while being output at a constant rate;
a freezing preparation device 13 which is connected with the sodium salt concentrated solution box 12 through a pipeline, and the chloride concentrated solution overflowed from the chloride concentrated solution box 10 is evaporated and crystallized through an evaporation crystallization unit 11 to prepare magnesium chloride salt and clear liquid;
and the nanofiltration membrane unit 14 is connected with the freezing preparation device 13 through a pipeline and is connected with the sodium chloride circulation box 4 through a pipeline, clear liquid is separated through the nanofiltration membrane unit 14 to obtain fresh water mainly containing sodium chloride and concentrated water mainly containing sodium sulfate, and the fresh water is led into the sodium chloride circulation box 4 through a pipeline for secondary use.
In some embodiments, a supplementary pipe 97 is further connected to the sodium chloride circulation tank 4, and the supplementary pipe 97 is configured to output the sodium chloride solution to the sodium chloride circulation tank 4 to maintain the concentration of the sodium chloride solution in the sodium chloride circulation tank 4 at 10%. The supplementary line 97 can also be replaced by a second channel 92 into which the sodium chloride solution can be fed back.
In some embodiments, a filter press connected to the triple box 2 is further provided for processing the sludge into a sludge cake and filter press water obtained after filter pressing, and the filter press water is returned to the conditioning tank 1 for secondary treatment.
In this treatment system, the overflow pipe 96 can be replaced by an overflow pipe provided with a height difference between the two structures.
According to the treatment system for treating the desulfurization wastewater by using the hardness-removing electrodialysis, on the premise that the investment cost is not remarkably increased, the combined process of the three headers 2, the ultrafiltration device 3 and the electrodialysis unit 5 is adopted, the softening-free treatment of the high-magnesium hard desulfurization wastewater can be realized, the medicament cost and the sludge treatment cost can be remarkably reduced, and the zero-emission process flow is realized. Meanwhile, calcium, magnesium ions and sulfate ions are enriched in two concentrated solution forms in the working process of the electrodialysis unit 5, so that the problem of sulfate scaling on the concentrated solution side of the electrodialysis unit 5 can be further avoided.
The above description in this specification is merely illustrative of the present invention. Various modifications, additions and substitutions may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.
Claims (3)
1. A treatment system for treating desulfurization wastewater by using hard electrodialysis is characterized by comprising an adjusting tank, a header, an ultrafiltration device, an electrodialysis unit, a sodium chloride circulation box, a desalination liquid box, an SWRO unit and an RO concentrated water box, wherein the desalination liquid box, the SWRO unit and the RO concentrated water box are arranged in the electrodialysis unit;
the chloride concentrated solution tank is connected with the electrodialysis unit through a third channel;
the sodium salt concentrated solution tank is connected with the electrodialysis unit through a fourth channel, and the nanofiltration membrane unit is connected with the sodium chloride circulation box.
2. The system for treating desulfurization wastewater by means of hardness-removing electrodialysis as set forth in claim 1, wherein the sodium chloride circulation tank is connected to a replenishment pipe.
3. The system for treating desulfurization wastewater by means of hardness-removing electrodialysis as set forth in claim 1, further comprising a water-producing tank connected to the SWRO unit.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114409160A (en) * | 2021-12-28 | 2022-04-29 | 国能铜陵发电有限公司 | Treatment method for preparing high-purity basic magnesium chloride whisker by removing ions from desulfurized slurry and recycling concentrated solution |
| CN114590932A (en) * | 2022-01-19 | 2022-06-07 | 国能朗新明南京环保科技有限公司 | Method for treating building material by desulfurization slurry ion removal and concentrated solution resource preparation magnesium chloride cement method |
| CN114790055A (en) * | 2022-03-21 | 2022-07-26 | 江苏海岳环境工程有限公司 | Zero-discharge system for cement desulfurization wastewater |
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2020
- 2020-11-19 CN CN202022694842.5U patent/CN214141977U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114409160A (en) * | 2021-12-28 | 2022-04-29 | 国能铜陵发电有限公司 | Treatment method for preparing high-purity basic magnesium chloride whisker by removing ions from desulfurized slurry and recycling concentrated solution |
| CN114409160B (en) * | 2021-12-28 | 2024-07-30 | 国能铜陵发电有限公司 | Treatment method for preparing high-purity basic magnesium chloride whisker by desulfurizing slurry ions and recycling concentrated solution |
| CN114590932A (en) * | 2022-01-19 | 2022-06-07 | 国能朗新明南京环保科技有限公司 | Method for treating building material by desulfurization slurry ion removal and concentrated solution resource preparation magnesium chloride cement method |
| CN114590932B (en) * | 2022-01-19 | 2024-09-06 | 国能朗新明南京环保科技有限公司 | Treatment method for preparing magnesium chloride cement-based building material by desulfurizing slurry and removing ions and recycling concentrated solution |
| CN114790055A (en) * | 2022-03-21 | 2022-07-26 | 江苏海岳环境工程有限公司 | Zero-discharge system for cement desulfurization wastewater |
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