CN108314112B - Method for treating waste water containing ammonium salt - Google Patents
Method for treating waste water containing ammonium salt Download PDFInfo
- Publication number
- CN108314112B CN108314112B CN201710034872.3A CN201710034872A CN108314112B CN 108314112 B CN108314112 B CN 108314112B CN 201710034872 A CN201710034872 A CN 201710034872A CN 108314112 B CN108314112 B CN 108314112B
- Authority
- CN
- China
- Prior art keywords
- wastewater
- heat exchange
- evaporation
- ammonia
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/048—Purification of waste water by evaporation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/02—Preparation, purification or separation of ammonia
- C01C1/022—Preparation of aqueous ammonia solutions, i.e. ammonia water
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
Abstract
The invention relates to the field of sewage treatment, and discloses a method for treating wastewater containing ammonium salt, which comprises the steps of introducing the wastewater into a first MVR evaporation device to carry out first evaporation to obtain first ammonia-containing steam and first concentrated solution, introducing the first concentrated solution into a second MVR evaporation device to carry out second evaporation to obtain second ammonia-containing steam and second concentrated solution, and adjusting the pH value of the wastewater to be more than 9 before introducing the wastewater into the first MVR evaporation device; before the wastewater is introduced into a first MVR evaporation device, carrying out first heat exchange on the first ammonia-containing steam and the wastewater to obtain first ammonia water; wherein the first evaporation is performed so that a solid content in the first concentrated solution is 50 mass% or less. The invention provides a low-cost and environment-friendly method for treating high-salinity wastewater containing ammonium, which can recover ammonium and salt in the wastewater, furthest recycle resources in the wastewater and realize near zero emission.
Description
Technical Field
The invention relates to the field of sewage treatment, in particular to a method for treating ammonium salt-containing wastewater, and particularly relates to a method for treating ammonium salt-containing wastewater.
Background
In the production process of the oil refining catalyst, a large amount of inorganic acid alkali salts such as sodium hydroxide, hydrochloric acid, sulfuric acid, ammonium salts, sulfates, hydrochlorides and the like are needed, and a large amount of mixed sewage containing ammonium, sodium sulfate, sodium chloride and aluminosilicate is generated. For such sewage, the common method in the prior art is that the pH value is adjusted to be within the range of 6-9, most of suspended matters are removed, then a biochemical method, a blow-off method or a steam stripping method is adopted to remove ammonium ions, then the salt-containing sewage is subjected to pH value adjustment, most of suspended matters are removed, hardness, silicon and part of organic matters are removed, most of organic matters are removed through ozone biological activated carbon adsorption oxidation or other advanced oxidation methods, then the salt-containing sewage enters an ion exchange device for further hardness removal, enters an enrichment device (such as reverse osmosis or electrodialysis) for concentration, and then MVR evaporative crystallization or multiple-effect evaporative crystallization is adopted to obtain mixed miscellaneous salt of sodium sulfate and sodium chloride containing a small amount of ammonium salt; or is; firstly, adjusting the pH value to be within the range of 6.5-7.5, removing most suspended matters, then removing hardness, silicon and part of organic matters, removing most of organic matters through ozone biological activated carbon adsorption oxidation or other advanced oxidation methods, then entering an ion exchange device for further removing hardness, entering a thickening device (such as reverse osmosis and/or electrodialysis) for concentration, and then adopting MVR (mechanical vapor recompression) evaporative crystallization or multiple-effect evaporative crystallization to obtain the mixed salt of sodium sulfate and sodium chloride containing ammonium salt. However, these ammonium-containing mixed salts are currently difficult to treat or expensive to treat, and the process of removing ammonium ions at the early stage additionally increases the cost of wastewater treatment.
In addition, the biochemical deamination can only treat wastewater with low ammonium content, and can not directly carry out biochemical treatment due to insufficient COD content in the catalyst sewage, and organic matters such as glucose or starch and the like are additionally added in the biochemical treatment process, so that the ammoniacal nitrogen can be treated by the biochemical method. The most important problem is that the total nitrogen of the wastewater after the biochemical deamination treatment is not up to the standard (the contents of nitrate ions and nitrite ions exceed the standard), the wastewater needs to be deeply treated, the salt content of the wastewater is not reduced (20000 mg/L-30000 mg/L), the wastewater cannot be directly discharged, and the wastewater needs to be further desalted.
In order to remove ammonia nitrogen from wastewater by gas stripping deamination, a large amount of alkali is needed to adjust the pH value, the alkali consumption is high, the alkali in the wastewater after deamination cannot be recovered, the pH value of the treated wastewater is high, the treatment cost is high, the COD content in the catalyst wastewater after gas stripping does not change greatly, the salt content in the wastewater is not reduced (20000 mg/L-30000 mg/L), the wastewater cannot be discharged directly, further desalting treatment is needed, the operation cost of wastewater treatment is high, a large amount of alkali remains in the treated wastewater, the pH value is high, the waste is large, and the treatment cost is up to 50 yuan/ton.
Disclosure of Invention
The invention aims to solve the problem of high treatment cost of the ammonium-containing high-salt wastewater in the prior art, and provides a low-cost and environment-friendly method for treating the ammonium-containing high-salt wastewater, which can recover ammonium and salt in the wastewater, furthest recycle resources in the wastewater and realize near zero emission.
In order to achieve the purpose, the invention provides a method for treating wastewater containing ammonium salt, which comprises the steps of introducing the wastewater into a first MVR evaporation device to carry out first evaporation to obtain first ammonia-containing steam and first concentrated solution, and then introducing the first concentrated solution into a second MVR evaporation device to carry out second evaporation to obtain second ammonia-containing steam and second concentrated solution, wherein before introducing the wastewater into the first MVR evaporation device, the pH value of the wastewater is adjusted to be more than 9; before the wastewater is introduced into a first MVR evaporation device, carrying out first heat exchange on the first ammonia-containing steam and the wastewater to obtain first ammonia water; before the first concentrated solution is introduced into a second MVR evaporation device, carrying out second heat exchange on the second ammonia-containing steam and the first concentrated solution to obtain second ammonia water; the first evaporation is performed so that the solid content in the first concentrated solution is 50 mass% or less.
Through the technical scheme, after the pH value of the wastewater is adjusted to a specific range in advance, the first MVR evaporation device and the second MVR evaporation device are reused for carrying out first evaporation and second evaporation on the wastewater, the process of separating ammonia and salt is completed, the wastewater is heated and cooled by ammonia-containing steam simultaneously in a heat exchange mode, a condenser is not needed, the heat in the evaporation process is reasonably utilized, the energy is saved, the wastewater treatment cost is reduced, ammonium in the wastewater is recovered in the form of ammonia water, the salt is recovered in the form of crystals of miscellaneous salts (pure salts when only chloride ions or sulfate ions are contained in the wastewater) which do not contain ammonium or a small amount of ammonium, no waste residues and waste liquid are generated in the whole process, the purpose of changing waste into valuables is realized, the value of the recovered resources is not counted, and the treatment cost of each ton of the wastewater is lower than that of a steam air stripping. In addition, according to the technical scheme, the wastewater is subjected to first evaporation and then second evaporation, so that ammonia water with higher concentration can be obtained in the first evaporation step, and the subsequent reutilization is facilitated.
Furthermore, the invention returns the waste water in the processes of crystal separation, crystal washing and the like to the evaporation process, and discharges the waste gas in the processes of heat exchange and the like after absorbing, thereby realizing near zero emission in the treatment process and reducing the environmental pollution to the maximum extent.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic flow diagram of a wastewater treatment process according to one embodiment of the present invention.
Description of the reference numerals
1. Second MVR evaporation plant 2, first MVR evaporation plant
31. First heat exchange device 32 and second heat exchange device
33. Third heat exchange device 34 and fourth heat exchange device
4. Vacuum degassing tank 51, first aqueous ammonia storage tank
52. Second ammonia storage tank 61, first pH value measuring device
62. Second pH value measuring device 71 and first circulating pump
72. Second circulating pump 73 and third circulating pump
74. Fourth and fifth circulating pumps 75 and 75
76. Sixth circulating pump 77 and seventh circulating pump
78. Eighth circulating pump 81, vacuum pump
82. Circulating water tank 83 and tail gas absorption tower
9. Solid-liquid separation device 101 and first compressor
102. Second compressor
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The present invention will be described below with reference to fig. 1, but the present invention is not limited to fig. 1.
The method for treating the wastewater containing the ammonium salt comprises the steps of introducing the wastewater into a first MVR evaporation device 2 to carry out first evaporation to obtain first ammonia-containing steam and first concentrated solution, and then introducing the first concentrated solution into a second MVR evaporation device 1 to carry out second evaporation to obtain second ammonia-containing steam and second concentrated solution, wherein before introducing the wastewater into the first MVR evaporation device 2, the pH value of the wastewater is adjusted to be more than 9; before the wastewater is introduced into a first MVR evaporation device 2, carrying out first heat exchange on the first ammonia-containing steam and the wastewater to obtain first ammonia water; before the first concentrated solution is introduced into a second MVR evaporation device 1, carrying out second heat exchange on the second ammonia-containing steam and the first concentrated solution to obtain second ammonia water; the first evaporation is performed so that the solid content in the first concentrated solution is 50 mass% or less.
Preferably, the pH of the wastewater is adjusted to be greater than 10.8 before passing the wastewater into the first MVR evaporation plant 2.
In the present invention, it is understood that the first ammonia-containing steam and the second ammonia-containing steam are secondary steam as referred to in the art.
According to the method, the pH value of the wastewater is adjusted to be strong alkaline, the first evaporation and the second evaporation are carried out through the first MVR evaporation device 2 and the second MVR evaporation device 1, ammonium ions contained in the wastewater are converted into ammonia and evaporated out, the obtained steam and the wastewater are subjected to heat exchange, the wastewater is heated, meanwhile, the steam is cooled to obtain ammonia water, the ammonia and the salt are simultaneously recovered, and the heat in the evaporation process is fully utilized.
In the present invention, the first MVR evaporation device 2 is not particularly limited, and may be various MVR evaporation devices conventionally used in the art. For example, it may be one or more selected from the group consisting of an MVR falling film evaporator, an MVR forced circulation evaporator, an MVR-FC continuous crystallization evaporator, and an MVR-OSLO continuous crystallization evaporator. Among them, preferred are an MVR forced circulation evaporator and an MVR-FC continuous crystallization evaporator, and more preferred is a falling film + forced circulation two-stage MVR evaporative crystallizer.
In the present invention, the first evaporation conditions of the first MVR evaporation device 2 are not particularly limited, and may be appropriately selected as needed. In order to improve the evaporation efficiency of the first evaporation, it is preferable that the conditions of the first evaporation include: the temperature is above 30 ℃ and the pressure is measured by gauge pressureIs above-98 kPa; more preferably, the conditions of the first evaporation include: the temperature is 50 ℃ to 130 ℃, and the pressure measured by gauge pressure is-93 kPa to 117 kPa; further preferably, the conditions of the first evaporation include: the temperature is 60-120 ℃, and the pressure measured by gauge pressure is-87 kPa-57 kPa; even more preferably, the conditions of the first evaporation include: the temperature is 95 ℃ to 115 ℃ and the pressure in gage pressure is-37 kPa to 33 kPa. The flow rate of the first evaporation may be appropriately selected depending on the capacity of the apparatus process, and may be, for example, 0.1m3More than h (e.g. 0.1 m)3/h～500m3/h)。
In the present invention, the first concentrated solution is not lost in fluidity by controlling the first evaporation so that the solid content in the first concentrated solution is 50 mass% or less (preferably 20 mass% or less, and more preferably no solid content), and the first concentrated solution can be directly sent to the second MVR evaporation device 1 by the circulation pump to perform the second evaporation. Preferably, the first evaporation does not make the first concentrated solution supersaturated (i.e. the solid content in the first concentrated solution is 0), and no crystallization occurs in the first concentrated solution, so that the first concentrated solution is more convenient to transport.
In the present invention, the degree of the first evaporation is not particularly limited, and the concentration ratio of the first evaporation is preferably 1.2 to 1.3 times, and more preferably 1.05 to 1.2 times, in order to obtain ammonia water having a high concentration. The concentration of the first aqueous ammonia solution obtained is preferably adjusted to 3 times or more the concentration of the ammonia in the wastewater before evaporation by appropriately adjusting the concentration ratio, and more preferably 5 to 20 times the concentration of the ammonia in the wastewater before evaporation by appropriately adjusting the concentration ratio. Through the adjustment concentration multiple of first evaporation, can adjust the concentration of first aqueous ammonia in certain extent, can be convenient for recycle of aqueous ammonia from this.
In the present invention, the method of adjusting the pH is not particularly limited, and the pH of the wastewater may be adjusted by adding an alkaline substance, for example. The alkaline substance is not particularly limited, and the purpose of adjusting the pH value may be achieved. In order not to introduce new impurities in the wastewater, the alkaline substance preferably has the same metal cation as the salt in the wastewater. For example, in the case where the wastewater contains a large amount of alkali metal cations, the alkali substance is preferably a hydroxide of an alkali metal (e.g., NaOH, KOH, etc.), and specifically, in the case where the wastewater contains a large amount of sodium ions, the alkali substance is preferably NaOH.
The alkaline substance may be added in a conventional manner in the art, but it is preferable to mix the alkaline substance with the wastewater in the form of an aqueous solution, and for example, an aqueous solution containing the alkaline substance may be introduced into a pipeline into which the wastewater is introduced and mixed. The content of the alkaline substance in the aqueous solution is not particularly limited as long as the above-mentioned purpose of adjusting the pH value can be achieved. However, in order to reduce the amount of water used and further reduce the cost, it is preferable to use a saturated aqueous solution of an alkaline substance. In order to monitor the pH of the wastewater, the pH of the wastewater may be measured after the pH adjustment described above.
According to the invention, before the wastewater is introduced into the first MVR evaporation plant 2, the first ammonia-containing steam and the wastewater are subjected to first heat exchange to obtain ammonia water. The first heat exchange method is not particularly limited, and may be performed by a heat exchange method that is conventional in the art. The number of heat exchanges may be one or more, preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2. Through the heat exchange, the output ammonia water is cooled, and the heat is circulated in the treatment device to the maximum extent, so that the energy is reasonably utilized, and the waste is reduced.
According to a preferred embodiment of the present invention, the first heat exchange is performed by a first heat exchange device 31 and a second heat exchange device 32, specifically, the first ammonia-containing steam obtained by evaporation in the first MVR evaporation device 2 is passed through the second heat exchange device 32 and the first heat exchange device 31 respectively, and the wastewater is passed through the first heat exchange device 31 and the second heat exchange device 32 respectively, and the first heat exchange is performed between the first ammonia-containing steam and the wastewater, so as to heat the wastewater for evaporation, and simultaneously cool the first ammonia-containing steam to obtain a first ammonia water, which can be stored in a first ammonia water storage tank 51.
According to a preferred embodiment of the present invention, as shown in fig. 1, the first evaporation process may be performed in the first MVR evaporation apparatus 2, and the first pH adjustment may be performed by introducing and mixing the aqueous solution containing the basic substance in the pipe for feeding the wastewater to the first heat exchange apparatus 31 before feeding the wastewater to the first heat exchange apparatus 31 for the first heat exchange; and the second pH adjustment is performed by introducing and mixing the aqueous solution containing the alkaline substance into the pipe for feeding the wastewater into the second heat exchange means 32 before feeding the wastewater into the second heat exchange means 32 for the first heat exchange. The pH of the wastewater prior to passing to the first MVR evaporator 2 may be greater than 9, preferably greater than 10.8, by two pH adjustments. Further, it is preferable that the first pH adjustment is performed so that the pH of the wastewater after adjustment is more than 7 (preferably 7 to 9), and the second pH adjustment is performed so that the pH is more than 9, preferably more than 10.8.
In order to detect the pH values after the first pH adjustment and the second pH adjustment, it is preferable that a first pH measuring device 61 is provided on a pipe for feeding the wastewater to the first heat exchange device 31 to measure the pH value after the first pH adjustment, and a second pH measuring device 62 is provided on a pipe for feeding the wastewater to the second heat exchange device 32 to measure the pH value after the second pH adjustment.
In the present invention, in order to increase the salt concentration of the liquid in the first MVR evaporation device 2 and to reduce the ammonia content of the liquid, it is preferred to return a portion of the wastewater concentrated by evaporation in the first MVR evaporation device 2 to the first MVR evaporation device 2. The above process of returning the wastewater evaporated and concentrated by the first MVR evaporation device 2 to the first MVR evaporation device 2 is preferably that the wastewater evaporated and concentrated by the first MVR evaporation device 2 is mixed with the wastewater after the first pH adjustment and before the second pH adjustment and then returned to the first MVR evaporation device 2, for example, the wastewater evaporated and concentrated by the first MVR evaporation device 2 may be returned to the wastewater conveying pipeline between the first heat exchange device 31 and the second heat exchange device 32 by the eighth circulation pump 78 to be mixed with the wastewater, and then after the second pH adjustment, the wastewater is heat-exchanged by the second heat exchange device 32 and then sent to the first MVR evaporation device 2.
In the present invention, the first heat exchange device 31 and the second heat exchange device 32 are not particularly limited, and various heat exchangers conventionally used in the art may be used to perform the first heat exchange between the first ammonia-containing steam and the wastewater. Specifically, a jacketed heat exchanger, a plate heat exchanger, a shell-and-tube heat exchanger, or the like may be mentioned, with the plate heat exchanger being preferred. The material of the heat exchanger can be specifically selected according to the needs, for example, in order to resist the corrosion of chloride ions, the heat exchanger of duplex stainless steel, titanium and titanium alloy, hastelloy can be selected as the material, and the heat exchanger containing plastic material can be selected when the temperature is lower.
According to the present invention, in order to fully utilize the heat energy of the first ammonia-containing steam condensate, it is preferable that the temperature of the wastewater after the first heat exchange by the first heat exchange device 31 is 30 ℃ or higher, and preferably 49 to 125 ℃.
According to the present invention, in order to fully utilize the heat energy of the first ammonia-containing steam, the temperature of the wastewater after the first heat exchange by the second heat exchange device 32 is preferably 49 to 139 ℃, and preferably 69 to 129 ℃.
According to the present invention, preferably, the method further comprises compressing the first ammonia-containing vapor before the first heat exchange. The compression of the first ammonia-containing vapor may be performed by a first compressor 101. Through right first ammonia vapor that contains compresses, for input energy among the MVR vaporization system, guarantee that waste water intensification-evaporation-cooling's process goes on in succession, need input start-up steam when MVR evaporation plant process starts, only through the compressor energy supply after reaching continuous running state, no longer need input other energy. The first compressor 101 may employ various compressors conventionally used in the art, such as a centrifugal fan, a turbine compressor, or a roots compressor. After compression by the first compressor 101, the temperature of the first ammonia-containing vapor is raised by 5 to 20 ℃.
In the present invention, the second MVR evaporation device 1 is not particularly limited, and may be various MVR evaporation devices conventionally used in the art. For example, it may be one or more selected from the group consisting of an MVR falling film evaporator, an MVR forced circulation evaporator, an MVR-FC continuous crystallization evaporator, and an MVR-OSLO continuous crystallization evaporator. Among them, preferred are an MVR forced circulation evaporator and an MVR-FC continuous crystallization evaporator, and more preferred is a falling film + forced circulation two-stage MVR evaporative crystallizer.
In the present invention, the evaporation conditions of the second MVR evaporation device 1 are not particularly limited, and may be appropriately selected as needed. In order to improve the evaporation efficiency, it is preferable that the conditions of the second evaporation include: the temperature is above 30 ℃, and the pressure in gage pressure is above-98 kPa; more preferably, the conditions of the second evaporation include: the temperature is 50 ℃ to 130 ℃, and the pressure measured by gauge pressure is-93 kPa to 117 kPa; further preferably, the conditions of the second evaporation include: the temperature is 60-110 ℃, and the pressure measured by gauge pressure is-87 kPa-12 kPa; even more preferably, the conditions of the second evaporation include: the temperature is 85-110 ℃, and the pressure measured by gauge pressure is-58 kPa-12 kPa. Further, the evaporation amount of the second evaporation may be appropriately selected depending on the capacity of the apparatus to treat and the amount of wastewater to be treated, and may be, for example, 0.1m3More than h (e.g. 0.1 m)3/h～500m3/h)。
According to the invention, before the first concentrated solution is introduced into the second MVR evaporation device 1, the second ammonia-containing steam and the first concentrated solution are subjected to second heat exchange to obtain second ammonia water. The second heat exchange method is not particularly limited, and may be performed by a heat exchange method that is conventional in the art. The number of heat exchanges may be one or more, preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2. Through the heat exchange, the output ammonia water is cooled, and the heat is circulated in the treatment device to the maximum extent, so that the energy is reasonably utilized, and the waste is reduced.
According to the present invention, preferably, the second heat exchange is performed by a fourth heat exchange device 34, specifically, the second ammonia-containing steam obtained by evaporation in the second MVR evaporation device 1 is passed through the fourth heat exchange device 34, and the first concentrated solution is passed through the fourth heat exchange device 34 to perform the second heat exchange between the second ammonia-containing steam and the first concentrated solution, so as to heat the first concentrated solution for evaporation, and simultaneously cool the second ammonia-containing steam.
According to a preferred embodiment of the present invention, the second heat exchange is performed by a third heat exchange device and a fourth heat exchange device, that is, the second heat exchange is performed by the fourth heat exchange device 34, and further performed by the third heat exchange device 33, specifically, the first concentrated solution and the second ammonia-containing steam perform the second heat exchange in the fourth heat exchange device 34, and the wastewater and the second ammonia-containing steam condensate obtained by condensing the second ammonia-containing steam through the fourth heat exchange device 34 perform the heat exchange in the third heat exchange device 33, so that the temperature of the second ammonia-containing steam condensate can be further reduced, the heat energy utilization rate can be improved, and the second ammonia can be stored in the second ammonia storage tank 52.
In the present invention, the third heat exchanger 33 and the fourth heat exchanger 34 are not particularly limited, and various heat exchangers conventionally used in the art may be used to perform the first heat exchange between the first ammonia-containing steam and the wastewater. Specifically, a jacketed heat exchanger, a plate heat exchanger, a shell-and-tube heat exchanger, or the like may be mentioned, with the plate heat exchanger being preferred. The material of the heat exchanger can be specifically selected according to the needs, for example, in order to resist the corrosion of chloride ions, the heat exchanger of duplex stainless steel, titanium and titanium alloy, hastelloy can be selected as the material, and the heat exchanger containing plastic material can be selected when the temperature is lower.
According to the present invention, in order to fully utilize the heat energy of the second ammonia-containing steam, the temperature of the wastewater after the second heat exchange by the fourth heat exchange device 34 is preferably 49 to 139 ℃, and preferably 59 to 119 ℃.
According to the present invention, in order to fully utilize the heat energy of the second ammonia-containing steam condensate, it is preferable that the temperature of the wastewater after the first heat exchange by the third heat exchange means 33 is 30 ℃ or higher, and preferably 49 to 125 ℃.
According to the present invention, preferably, the method further comprises compressing the second ammonia-containing vapor before the second heat exchange. The compression of the second ammonia-containing vapor may be performed by a second compressor 102. Through right the second contains ammonia steam and compresses, for input energy among the MVR vaporization system, guarantees that waste water intensification-evaporation-cooling's process goes on in succession, needs input start-up steam when MVR evaporation plant starts, only through the compressor energy supply after reaching continuous running state, no longer need input other energy. The second compressor 102 may be any one of various compressors conventionally used in the art, such as a centrifugal fan, a turbine compressor, a roots compressor, or the like. After compression by the second compressor 102, the temperature of the first ammonia-containing vapor is increased by 5 ℃ to 20 ℃.
In the present invention, in order to increase the salt concentration of the liquid in the second MVR evaporation device 1 and reduce the ammonia content in the liquid, it is preferable to return a part of the waste water evaporated and concentrated by the second MVR evaporation device 1 to the second MVR evaporation device 1. The above process of returning the first concentrated solution evaporated by the second MVR evaporation device 1 to the second MVR evaporation device 1 is preferably that after mixing a part of the first concentrated solution evaporated by the second MVR evaporation device 1 with the first concentrated solution evaporated by the first MVR evaporation device 2, the mixture is sent to the second MVR evaporation device 1 for second evaporation, for example, a part of the first concentrated solution evaporated by the second MVR evaporation device 1 may be returned to the first concentrated solution conveying pipeline between the first MVR evaporation device 1 and the fourth heat exchange device 34 by the seventh circulating pump 77 to be mixed with the first concentrated solution, and then heat exchange is performed in the fourth heat exchange device 34, and the mixture is sent to the first MVR evaporation device 2.
According to a preferred embodiment of the present invention, the evaporation process is carried out in the second MVR evaporation device 1. And introducing the first concentrated solution into the second MVR evaporation device 1 through a fifth circulating pump 75 to evaporate to obtain a second concentrated solution.
In the invention, the second concentrated solution is subjected to solid-liquid separation to obtain crystals and a liquid obtained by solid-liquid separation. The method of the solid-liquid separation is not particularly limited, and may be selected from one or more of centrifugation, filtration, and sedimentation.
In the present invention, preferably, at least a part or all of the liquid obtained by the solid-liquid separation of the second concentrated solution is returned to the first MVR evaporation apparatus 2 to perform the first evaporation again.
According to a preferred embodiment of the present invention, the solid-liquid separation can be performed by using a solid-liquid separation device 9 (preferably, a centrifuge), and specifically, the second concentrated solution is sent to the solid-liquid separation device 9 by a sixth circulation pump 76 to perform solid-liquid separation. After the solid-liquid separation, all the liquid obtained by the solid-liquid separation returns to the first MVR evaporation device 2 for the first evaporation again.
In addition, it is difficult to avoid adsorption of impurities such as free ammonia and hydroxide ions on the crystals, and in order to remove the adsorbed impurities, reduce the odor of solid salts, reduce corrosiveness, and improve the purity of the crystals, the crystals are preferably washed with water or brine and dried. The saline water is not particularly limited and may be appropriately selected as needed. In order to avoid dissolution of crystals during washing, it is preferred that the type of salt in the brine is selected according to the salt contained in the wastewater, preferably the same salt as the wastewater. More preferably, the brine is preferably saturated brine. To further reduce the cost of the process, the use of salt is reduced, the brine preferably being an aqueous solution of the wastewater or the crystals, more preferably a saturated aqueous solution of the crystals. Additionally, the washing liquid resulting from washing the crystals may be recycled to the second MVR evaporation device 1 or the first MVR evaporation device 2, preferably all to the second MVR evaporation device 1.
In the present invention, it is preferable to perform vacuum degassing before the wastewater is treated. The vacuum degassing may be performed using a vacuum degassing tank 4. Through the vacuum degassing, gases dissolved in the wastewater, such as air, ammonia gas and the like, can be removed, so that air resistance can be prevented, stability and reliability of the system during normal operation can be ensured, aerobic corrosion of the system is reduced, and the service life of the equipment is prolonged. The vacuum degassing conditions include: the vacuum degree can reach-90 kPa to-70 kPa by gauge pressure, the processing speed of vacuum degassing and the fresh raw material feeding quantity of the system are oneThus, it may be 0.1m3More than h (e.g. 0.1 m)3/h～500m3/h)。
In the present invention, preferably, the tail gas obtained by vacuum degassing, the tail gas remaining after the first ammonia-containing steam is condensed by the first heat exchange, and the tail gas remaining after the second ammonia-containing steam is condensed by the second heat exchange are discharged after ammonia removal. The tail gas obtained by vacuum degassing is the tail gas discharged from the vacuum degassing tank 4, the first ammonia-containing steam is the tail gas discharged from the second heat exchange device 32 after passing through the first heat exchange condensation, and the second steam is the tail gas discharged from the fourth heat exchange device 34 after passing through the second heat exchange condensation.
As the method of removing ammonia, absorption may be performed by the off-gas absorption tower 83. The off-gas absorption column 83 is not particularly limited, and may be any of various absorption columns conventionally used in the art, such as a plate-type absorption column, a packed absorption column, a falling film absorption column, or an empty column. Circulating water is arranged in the tail gas absorption tower 83, the circulating water circulates in the tail gas absorption tower 83 under the action of the fourth circulating pump 74, water can be supplemented into the tail gas absorption tower 83 from the circulating water tank 82 through the third circulating pump 73, fresh water can be supplemented into the circulating water tank 82, and meanwhile the temperature of working water of the vacuum pump 81 and the ammonia content can be reduced. The flow of the off-gas and the circulating water in the off-gas absorption tower 83 may be in a counter-current or co-current flow, preferably in a counter-current flow. The circulating water can be supplemented by additional fresh water. In order to ensure the sufficient absorption of the tail gas, dilute sulfuric acid may be further added to the tail gas absorption tower 83 to absorb a small amount of ammonia and the like in the tail gas. The circulating water can be used as ammonia water or ammonium sulfate solution for production or direct sale after absorbing tail gas. The off gas may be introduced into the off gas absorption tower 83 by a vacuum pump 81.
In the present invention, the wastewater is not particularly limited as long as it is an ammonium salt-containing wastewater. In addition, the wastewater of the invention is particularly suitable for treating the wastewater containing ammonium and high salt. The wastewater of the present invention may be specifically wastewater from a process for producing a molecular sieve, alumina or a refinery catalyst, or wastewater from a process for producing a molecular sieve, alumina or a refinery catalyst, which is subjected to the following impurity removal and concentration. It is preferable that the wastewater from the production of molecular sieves, alumina or refinery catalysts is subjected to the following impurity removal and concentration.
In the present invention, the inorganic salt ions contained in the wastewater are other than NH4 +In addition, Na may be contained+、SO4 2-、Cl-、NO3 -、NO2 -And (3) plasma.
As NH in said wastewater4 +May be 8mg/L or more, preferably 300mg/L or more.
As Na in the wastewater+May be 510mg/L or more, preferably 1000mg/L or more, more preferably 2000mg/L or more, further preferably 4000mg/L or more, further preferably 8000mg/L or more, further preferably 16000mg/L or more, further preferably 32000mg/L or more, further preferably 40000mg/L or more, further preferably 50000mg/L or more, further preferably 60000mg/L or more.
As SO in said wastewater4 2-May be 1000mg/L or more, preferably 2000mg/L or more, more preferably 4000mg/L or more, further preferably 8000mg/L or more, further preferably 16000mg/L or more, further preferably 32000mg/L or more, further preferably 40000mg/L or more, further preferably 50000mg/L or more, further preferably 60000mg/L or more, further preferably 70000mg/L or more.
As Cl in said wastewater-May be 970mg/L or more, more preferably 2000mg/L or more, further preferably 4000mg/L or more, further preferably 8000mg/L or more, further preferably 16000mg/L or more, further preferably 32000mg/L or more, further preferably 40000mg/L or more, further preferably 50000mg/L or more, further preferably 60000mg/L or more.
The TDS of the wastewater may be 1600mg/L or more, preferably 4000mg/L or more, more preferably 8000mg/L or more, further preferably 16000mg/L or more, further preferably 32000mg/L or more, further preferably 40000mg/L or more, further preferably 50000mg/L or more, further preferably 60000mg/L or more, further preferably 100000mg/L or more, further preferably 150000mg/L or more, further preferably 200000mg/L or more.
The upper limit of the inorganic salt ions contained in the wastewater is not particularly limited, and the treatment by the method of the present invention can be performed even when the inorganic salt ions contained in the wastewater are in a supersaturated state.
In the invention, the pH value of the wastewater is preferably 4-7.
In addition, since the COD of the wastewater may block a membrane at the time of concentration, affect the purity and color of salt at the time of evaporative crystallization, etc., the COD of the wastewater is preferably as small as possible, and is preferably removed by oxidation at the time of pretreatment, and specifically, it may be performed by, for example, a biological method, an advanced oxidation method, etc., and it is preferably oxidized by an oxidizing agent, which may be, for example, fenton's reagent, at the time of very high COD content. Preferably, the COD content is 20mg/L or less, more preferably 10mg/L or less.
In addition, the wastewater of the invention can also contain Mg2+、Ca2+、K+、Fe3+Rare earth element ions and COD, and the content of the impurities is usually 3mg/L to 50mg/L (preferably 10mg/L or less, more preferably 5mg/L or less), and the impurities can be removed by subsequent impurity removal.
In the invention, in order to ensure the continuous and stable operation of the treatment process and reduce the equipment operation and maintenance cost, the wastewater is preferably subjected to impurity removal before being treated by the treatment method. Preferably, the impurity removal is selected from one or more of solid-liquid separation, chemical precipitation, adsorption, ion exchange and oxidation.
As the solid-liquid separation, filtration, centrifugation, sedimentation, or the like may be mentioned; as the chemical precipitation, pH adjustment, carbonate precipitation, magnesium salt precipitation, and the like may be mentioned; the adsorption can be physical adsorption and/or chemical adsorption, and the specific adsorbent can be selected from activated carbon, silica gel, alumina, molecular sieve, natural clay and the like; as the ion exchange, any one of a strongly acidic cation resin and a weakly acidic cation resin can be used; as the oxidation, various oxidizing agents conventionally used in the art, for example, ozone, hydrogen peroxide, ammonium persulfate, fenton's reagent, potassium permanganate, and the like can be used, and in order to avoid introduction of new impurities, ozone, hydrogen peroxide, and the like are preferably used.
The specific impurity removal mode can be specifically selected according to the types of impurities contained in the wastewater. For suspended matters, a solid-liquid separation method can be selected for removing impurities; for inorganic matters and organic matters, chemical precipitation, ion exchange and adsorption methods can be selected for removing impurities, such as weak acid cation exchange, activated carbon adsorption and the like; for organic matters, impurities can be removed by adopting an adsorption and/or oxidation mode, wherein an ozone biological activated carbon adsorption oxidation method is preferred. According to a preferred embodiment of the invention, the wastewater is subjected to filtration, weak acid cation exchange method and ozone biological activated carbon adsorption oxidation method for removing impurities in sequence. Through the impurity removal process, most suspended matters, hardness, silicon and organic matters can be removed, the scaling risk of the device is reduced, and the continuous and stable operation of the wastewater treatment process is ensured.
In the present invention, the wastewater having a low salt content may be concentrated to have a salt content within a range required for the wastewater of the present invention before the wastewater is treated by the treatment method of the present invention (preferably, after the above-mentioned impurity removal). Preferably, the concentration is selected from ED membrane concentration and/or reverse osmosis; more preferably, the concentration is performed by ED membrane concentration and reverse osmosis, and the order of performing the ED membrane concentration and the reverse osmosis is not particularly limited. The ED membrane concentration and reverse osmosis treatment apparatus and conditions may be performed in a manner conventional in the art, and may be specifically selected according to the condition of wastewater to be treated. Specifically, as the concentration of the ED membrane, a one-way electrodialysis system or a reversed electrodialysis system can be selected for carrying out; as the reverse osmosis, a roll membrane, a plate membrane, a disc-tube membrane, a vibrating membrane or a combination thereof can be selected for use. Through the concentration can improve the efficiency of waste water treatment, avoid the energy waste that a large amount of evaporations caused.
In a preferred embodiment of the invention, the wastewater is wastewater obtained by performing chemical precipitation, filtration, weak acid cation exchange and ozone biological activated carbon adsorption oxidation on wastewater generated in the molecular sieve production process to remove impurities, and performing ED membrane concentration and reverse osmosis concentration on the wastewater.
The conditions for the above chemical precipitation are preferably: sodium carbonate is used as a treating agent, 1.2-1.4 mol of sodium carbonate is added relative to 1 mol of calcium ions in the wastewater, the pH value of the wastewater is adjusted to be more than 7, the reaction temperature is 20-35 ℃, and the reaction time is 0.5-4 h.
The conditions for the filtration are preferably: the filtering unit adopts a double-layer filtering material multi-medium filter consisting of anthracite and quartz sand, the grain diameter of the anthracite is 0.7 mm-1.7 mm, the grain diameter of the quartz sand is 0.5 mm-1.3 mm, and the filtering speed is 10 m/h-30 m/h. After the filter material is used, the regeneration method of 'gas back flushing-gas and water back flushing-water back flushing' is adopted to regenerate the filter material, and the regeneration period is 10-15 h.
The conditions for the weak acid cation exchange method are preferably: the pH value range is 6.5-7.5; the temperature is less than or equal to 40 ℃, the height of the resin layer is 1.5-3.0 m, the HCl concentration of the regeneration liquid is as follows: 4.5-5 mass%; the amount of the regenerant (calculated by 100%) was 50kg/m3～60kg/m3Wet resin; the flow rate of the regeneration liquid HCl is 4.5 m/h-5.5 m/h, and the regeneration contact time is 35 min-45 min; the forward washing flow rate is 18 m/h-22 m/h, and the forward washing time is 20 min-30 min; the running flow rate is 15 m/h-30 m/h; as the acidic cation exchange resin, for example, there can be used a Gallery Senno chemical Co., Ltd, SNT brand D113 acidic cation exchange resin.
The conditions of the above-mentioned ozone biological activated carbon adsorption oxidation method are preferably: the retention time of the ozone is 50min to 70min, and the empty bed filtration rate is 0.5m/h to 0.7 m/h.
The conditions for the concentration of the ED membrane are preferably: the current 145A to 155A and the voltage 45V to 65V. The ED membrane may be, for example, an ED membrane manufactured by astone corporation of japan.
The conditions for the reverse osmosis are preferably: the operation pressure is 5.4MPa to 5.6MPa, the water inlet temperature is 25 ℃ to 35 ℃, and the pH value is 6.5 to 7.5. The reverse osmosis membrane is, for example, a seawater desalination membrane TM810C manufactured by Dongli corporation of Lanxingdong.
The present invention will be described in detail below by way of examples.
In the following examples, the wastewater is obtained by sequentially removing impurities from wastewater generated in the production process of the molecular sieve by chemical precipitation, filtration, weak acid cation exchange method and ozone biological activated carbon adsorption oxidation method, and sequentially concentrating the wastewater by ED membrane concentration and reverse osmosis method.
Example 1
As shown in FIG. 1, wastewater (containing NaCl 55g/L, Na)2SO4142g/L、NH4Cl 20g/L、(NH4)2SO452.48g/L) at a feed rate of 120m3The wastewater is introduced into a vacuum degassing tank 4 at a rate of/h for degassing (the vacuum degree is-70 kPa in gauge pressure), and the wastewater after degassing is mixed with a liquid (containing NaCl288.3g/L, Na) obtained by a solid-liquid separation device before being fed into a first heat exchange device 31 (specifically, a titanium alloy plate heat exchanger)2SO465.2g/L, NaOH 9.94.94 g/L, flow rate 27m3H) mixing, introducing a sodium hydroxide aqueous solution with the concentration of 45.16 mass% into a pipeline to adjust the pH value for the first time, monitoring the adjusted pH value through a first pH value measuring device 61 (a pH meter) (the measured value is 8.0), sending one part of the wastewater subjected to the first pH value adjustment into a first heat exchange device 31 through a first circulating pump 71 to perform first heat exchange with the recovered first ammonia-containing steam condensate, and sending the other part of the wastewater into a third heat exchange device 33 to perform second heat exchange with the recovered second ammonia-containing steam condensate so as to heat the wastewater to 95 ℃; then, an aqueous sodium hydroxide solution having a concentration of 45.16 mass% was introduced into a pipe for feeding the wastewater subjected to the first heat exchange into a second heat exchange device 32 (specifically, a titanium alloy plate heat exchanger) to adjust the pH value for the second time, the adjusted pH value was monitored by a second pH value measuring device 62(pH meter) (measurement value 11), the wastewater subjected to the second pH value adjustment was fed into the second heat exchange device 32 to perform the first heat exchange with the recovered first ammonia-containing steam to raise the temperature of the wastewater to 112 ℃, and then the wastewater was fed into the first MVR evaporation device 2 to perform the first evaporation. Wherein the first steaming stepThe clockwork spring includes: the temperature was 107 ℃ and the pressure in gauge was 0kPa, the evaporation rate was 34.3m3H is used as the reference value. The first ammonia-containing steam obtained by the first evaporation is compressed by the first compressor 101 (the temperature rises by 12 ℃) and then sequentially passes through the second heat exchange device 32 and the first heat exchange device 31 to exchange heat with the wastewater, and is cooled to obtain first ammonia water which is stored in the first ammonia water storage tank 51. In order to increase the salt concentration of the liquid in the first MVR evaporator 2, part of the waste water after evaporation in the first MVR evaporator 2 is returned to the second pH adjustment process by the second circulation pump 72. The first MVR evaporation device 2 evaporates every hour to obtain 122m3Contains 139.4g/L, Na NaCl2SO4209.6g/L, NaOH 2.2.2 g/L NH31.56g/L (solid content 0).
The second evaporation process is performed in a second MVR evaporation device 1 (three-effect evaporation device). And sending the first concentrated solution to a second MVR evaporation device 1 through a fifth circulating pump 75 for second evaporation to obtain a second concentrated solution. Wherein the second evaporation conditions comprise: the temperature was 100 ℃, the pressure in gauge was-22.8 kPa, and the evaporation capacity was 96.4m3H is used as the reference value. After the second ammonia-containing steam obtained by evaporation of the second MVR evaporation device 1 is compressed by the second compressor 102 (the temperature is increased by 10 ℃), the second heat exchange is firstly carried out between the second ammonia-containing steam and the first concentrated solution through the fourth heat exchange device 34, and then the second heat exchange is carried out between the second ammonia-containing steam and the wastewater through the third heat exchange device 33, and the second ammonia water is obtained by cooling and stored in the second ammonia water storage tank 52. In order to improve the salt concentration of the liquid in the second MVR evaporation device 1, part of the first concentrated solution evaporated in the second MVR evaporation device 1 is combined with the first concentrated solution, and then returned to the fourth heat exchange device 34 through the seventh circulating pump 77 for heat exchange, and then sent to the second MVR evaporation device 1 for evaporation.
The first concentrated solution is subjected to second evaporation in a second MVR evaporation device 1 to obtain a second concentrated solution, the second concentrated solution is sent into a solid-liquid separation device 9 (centrifugal machine) through a sixth circulating pump 76 for solid-liquid separation, crystals (namely mixed salt crystallization filter cakes) and liquid obtained by solid-liquid separation are respectively obtained, after the mixed salt crystallization filter cakes are washed by the saturated mixed brine, part of the mixed salt crystallization filter cakes are used for preparing saturated mixed brine, and the water content of the mixed salt crystallization filter cakes is 28 substances per hour46.53 tons of mixed salt crystallization filter cake with the weight percent is dried in a drier, and 33.04 tons of mixed salt containing sodium chloride and sodium sulfate is obtained every hour; solid-liquid separation to obtain 27m per hour3Containing NaCl288.3g/L, Na2SO465.2g/L, NaOH 9.941g/L of liquid obtained by solid-liquid separation, and returning the liquid obtained by solid-liquid separation to be mixed with the wastewater before the second pH value adjustment through an eighth circulating pump 78; and washing water obtained by washing the filter cake is mixed with the first concentrated solution evaporated by the first MVR evaporation device 2 and then enters the second MVR evaporation device 1 through a seventh circulating pump 76.
In addition, the tail gas discharged by the vacuum degassing tank 4 and the second heat exchange device 32 is introduced into a tail gas absorption tower 83 through a vacuum pump 81 for absorption, circulating water is introduced into the tail gas absorption tower, the circulating water circulates in the tail gas absorption tower 83 under the action of a fourth circulating pump 74, water can be supplemented into the tail gas absorption tower 83 from a circulating water tank 82 through a third circulating pump 73, fresh water can be supplemented into the circulating water tank 82, and meanwhile, the temperature and the ammonia content of the working water of the vacuum pump 81 can be reduced. Dilute sulfuric acid is further introduced into the tail gas absorption tower to absorb ammonia and the like in the tail gas.
In the present embodiment, 34.3m of first aqueous ammonia having a concentration of 6.38 mass% was obtained per hour in the first aqueous ammonia tank 513The second ammonia water in the second ammonia water tank 52 was obtained at a concentration of 96.4 m/hr, at 0.197 mass%3The ammonia water can be reused in the production process of the molecular sieve.
In addition, the starting phase of the MVR evaporation was started by steam at a temperature of 143.3 ℃.
Example 2
The wastewater treatment was carried out in the same manner as in example 1 except that 230g/L, NH g of NaCl was added4And treating the wastewater with Cl 50 g/L. The first evaporation conditions of the first MVR evaporation device 2 include: the temperature was 100 ℃ and the pressure, as measured by gauge pressure, was-22.83 kPa, the evaporation being 28.4m3H is used as the reference value. The second evaporation conditions of the second MVR evaporation device 1 include: the temperature was 90 ℃ and the pressure, as measured by gauge pressure, was-47.9 kPa, the evaporation being 110m3/h。
The first MVR evaporation device 2 evaporates every hour to obtain 132m3Contains NaCl 230g/L, NaOH 2.2.2 g/L, NH31.155g/L of the first concentrated solution (solid content: 0). 28.4m of first aqueous ammonia having a concentration of 6.15 mass% was obtained in the first aqueous ammonia tank 51 every hour3。
The solid-liquid separation yielded 48.11 tons per hour of a sodium chloride crystal cake having a water content of 29 mass%, yielding 33m per hour3The liquid obtained by solid-liquid separation and containing 312.9g/L, NaOH 8.8.8 g/L NaCl finally yielded 34.16 tons of sodium chloride per hour, and 110 m/hour in the second ammonia water storage tank 523Second aqueous ammonia having a concentration of 0.137 mass%.
Example 3
The wastewater was treated in the same manner as in example 1 except that Na-containing wastewater was treated2SO4150g/L、(NH4)2SO450g/L of wastewater was treated. The first evaporation conditions of the first MVR evaporation device 2 include: the temperature was 95 ℃, the pressure in gauge was-36.36 kPa, and the evaporation capacity was 24.1m3H is used as the reference value. The second evaporation conditions of the second MVR evaporation device 1 include: the temperature was 85 ℃, the pressure as a gauge pressure was-57.65 kPa, and the evaporation capacity was 100m3/h。
The first MVR evaporation unit 2 evaporated to 24.1m per hour3Containing Na2SO4226.37g/L、NaOH2.2g/L、NH30.981g/L of the first concentrated solution (solid content: 0). The first aqueous ammonia tank 51 obtained 24.1m of first aqueous ammonia having a concentration of 5.91 mass% per hour.
Solid-liquid separation was carried out per hour to obtain 33.5 tons of a sodium sulfate crystal cake having a water content of 27 mass%, and 24m per hour3Containing Na2SO4169.5g/L, NaOH 11.55.11.55 g/L of the liquid obtained by solid-liquid separation, 24.45 tons of sodium sulfate were finally obtained per hour, and 100m of sodium sulfate was obtained per hour in the second ammonia water storage tank 523Aqueous ammonia having a concentration of 0.122 mass%.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (26)
1. A method for treating wastewater containing ammonium salt comprises the steps of introducing the wastewater into a first MVR evaporation device for first evaporation to obtain first ammonia-containing steam and first concentrated solution, introducing the first concentrated solution into a second MVR evaporation device for second evaporation to obtain second ammonia-containing steam and second concentrated solution,
adjusting the pH value of the wastewater to be greater than 9 before introducing the wastewater into the first MVR evaporation device;
before the wastewater is introduced into a first MVR evaporation device, carrying out first heat exchange on the first ammonia-containing steam and the wastewater to obtain first ammonia water;
before the first concentrated solution is introduced into a second MVR evaporation device, carrying out second heat exchange on the second ammonia-containing steam and the first concentrated solution to obtain second ammonia water;
wherein the first evaporation does not result in supersaturation of the first concentrate;
the conditions of the first evaporation include: the temperature is above 30 ℃, and the pressure in gage pressure is above-98 kPa; the conditions of the second evaporation include: the temperature is above 30 ℃, and the pressure in gage pressure is above-98 kPa;
the second concentrated solution is subjected to solid-liquid separation to obtain crystals and liquid obtained by solid-liquid separation, and the liquid obtained by solid-liquid separation is completely returned to the first MVR evaporation device;
NH in the wastewater4 +Is more than 8mg/L, TDS is 1600mg/LThe above step (1);
the wastewater also contains Na+、SO4 2-And Cl-，Na+The content of (B) is more than 510mg/L, SO4 2-Has a content of over 1000mg/L and Cl-The content of (b) is more than 970 mg/L.
2. The method of claim 1, wherein the pH of the wastewater is adjusted to greater than 10.8 prior to passing the wastewater to the first MVR evaporation device.
3. The method of claim 1, wherein the conditions of the first evaporation comprise: the temperature is 50 ℃ to 130 ℃, and the pressure in gauge pressure is-93 kPa to 117 kPa.
4. The method of claim 3, wherein the conditions of the first evaporation comprise: the temperature is 60 ℃ to 120 ℃, and the pressure measured by gauge pressure is-87 kPa to 57 kPa.
5. The method of claim 4, wherein the conditions of the first evaporation comprise: the temperature is 95 ℃ to 115 ℃ and the pressure in gage pressure is-37 kPa to 33 kPa.
6. The method of claim 1, wherein the conditions of the second evaporation comprise: the temperature is 50 ℃ to 130 ℃, and the pressure in gauge pressure is-93 kPa to 117 kPa.
7. The method of claim 6, wherein the conditions of the second evaporation comprise: the temperature is 60 ℃ to 110 ℃, and the pressure measured by gauge pressure is-87 kPa to 12 kPa.
8. The method of claim 7, wherein the conditions of the second evaporation comprise: the temperature is 85-110 ℃, and the pressure measured by gauge pressure is-58 kPa-12 kPa.
9. The method of claim 1, wherein the first heat exchange is performed by a first heat exchange device and a second heat exchange device.
10. The method according to claim 9, wherein the temperature of the wastewater after the first heat exchange by the first heat exchange means is 30 ℃ or higher.
11. The method of claim 10, wherein the temperature of the wastewater after the first heat exchange by the first heat exchange device is 49 ℃ to 125 ℃.
12. The method of claim 9, wherein the temperature of the wastewater after the first heat exchange by the second heat exchange device is 49 ℃ to 139 ℃.
13. The method of claim 12, wherein the temperature of the wastewater after the first heat exchange by the second heat exchange device is 69 ℃ to 129 ℃.
14. The process of claim 9 wherein the pH of the wastewater is adjusted to greater than 7 prior to entering the first heat exchange means.
15. The method of claim 1, wherein the second heat exchange is performed by a third heat exchange device and a fourth heat exchange device.
16. The process of claim 15, wherein the temperature of the first concentrate after the second heat exchange by the fourth heat exchange means is between 49 ℃ and 139 ℃.
17. The process of claim 16, wherein the temperature of the first concentrate after the second heat exchange by the fourth heat exchange means is between 59 ℃ and 119 ℃.
18. The method according to claim 15, wherein the temperature of the wastewater after the second heat exchange by the third heat exchange means is 30 ℃ or higher.
19. The method of claim 18, wherein the temperature of the wastewater after the second heat exchange by the third heat exchange device is between 49 ℃ and 125 ℃.
20. The process according to claim 1, wherein the process further comprises compressing the first ammonia-containing vapor before the first heat exchange and compressing the second ammonia-containing vapor before the second heat exchange.
21. The method of claim 20, wherein the wastewater is vacuum degassed prior to being passed to the first MVR evaporator for treatment.
22. The method according to claim 21, wherein the tail gas obtained by vacuum degassing, the tail gas left after the first ammonia-containing steam is condensed by first heat exchange, and the tail gas left after the second ammonia-containing steam is condensed by second heat exchange are discharged after ammonia removal.
23. The method of claim 1, wherein the crystals are washed with water or brine and dried.
24. The method of claim 23, wherein the washed liquid is returned to the second MVR evaporation device.
25. The method of claim 23, wherein the brine is an aqueous solution of the wastewater or the crystals.
26. The method of claim 1, further comprising removing impurities and concentrating the wastewater.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710034872.3A CN108314112B (en) | 2017-01-17 | 2017-01-17 | Method for treating waste water containing ammonium salt |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710034872.3A CN108314112B (en) | 2017-01-17 | 2017-01-17 | Method for treating waste water containing ammonium salt |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108314112A CN108314112A (en) | 2018-07-24 |
| CN108314112B true CN108314112B (en) | 2020-08-21 |
Family
ID=62892192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710034872.3A Active CN108314112B (en) | 2017-01-17 | 2017-01-17 | Method for treating waste water containing ammonium salt |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108314112B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110342720A (en) * | 2019-08-19 | 2019-10-18 | 常州中源工程技术有限公司 | Ammonium sulfate waste water MVR evaporates deamination processing system and its treatment process |
| CN112794546B (en) * | 2020-12-25 | 2022-09-13 | 江苏远洋药业股份有限公司 | Method for treating ammonium-containing wastewater generated in taurine production |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61234982A (en) * | 1985-04-09 | 1986-10-20 | Kawasaki Heavy Ind Ltd | Treatment of waste water containing ammonia, hydrogen sulfide, and so forth |
| CN101318752B (en) * | 2008-07-10 | 2010-09-08 | 浙江大学 | Treatment method and apparatus for recycling ammonia nitrogen wastewater |
| CN101475194B (en) * | 2009-01-22 | 2010-12-29 | 西安西骏新材料有限公司 | Method for recycling ammonia from low concentration ammonium chloride wastewater |
| CN103241887A (en) * | 2013-05-27 | 2013-08-14 | 兰州节能环保工程有限责任公司 | Method and device for treating and recycling high salinity wastewater |
| CN106186501A (en) * | 2016-09-19 | 2016-12-07 | 江苏泫槿环境科技有限公司 | A kind of high concentration ammonia nitrogen wastewater treatment system and processing method |
-
2017
- 2017-01-17 CN CN201710034872.3A patent/CN108314112B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN108314112A (en) | 2018-07-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108314114B (en) | Method for treating waste water containing ammonium salt | |
| CN109422409B (en) | Method for treating waste water containing ammonium salt | |
| CN108314112B (en) | Method for treating waste water containing ammonium salt | |
| CN105481160B (en) | Method and device for preparing industrial salt by strong brine with zero discharge | |
| CN108726756B (en) | Method for treating ammonium salt-containing wastewater | |
| CN108314115B (en) | Method for treating waste water containing ammonium salt | |
| CN109422407B (en) | Method for treating catalyst production wastewater | |
| CN109422402B (en) | Method for treating catalyst production wastewater | |
| CN216639187U (en) | Treatment system for salt-containing wastewater and CO 2-containing waste gas | |
| CN108726606B (en) | Treatment method of catalyst production wastewater | |
| CN108726603B (en) | Treatment method of catalyst production wastewater | |
| CN108314113B (en) | Method for treating waste water containing ammonium salt | |
| CN108726611B (en) | Treatment method of catalyst production wastewater | |
| CN108726604B (en) | Treatment method of catalyst production wastewater | |
| CN108726610B (en) | Method for treating waste water containing ammonium salt | |
| CN108726759B (en) | Method for treating ammonium salt-containing wastewater | |
| CN108726612B (en) | Method for treating waste water containing ammonium salt | |
| CN108726755B (en) | Treatment method of catalyst production wastewater | |
| CN108726605B (en) | Treatment method of catalyst production wastewater | |
| CN108726608B (en) | Treatment method of catalyst production wastewater | |
| CN109422398B (en) | Method for treating catalyst production wastewater | |
| CN109422396B (en) | Method for treating wastewater from catalyst production | |
| CN108726607B (en) | Method for treating catalyst production wastewater | |
| CN108726760B (en) | Treatment method of catalyst production wastewater | |
| CN108726764B (en) | Treatment method of catalyst production wastewater |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |