Ammonia-nitrogen wastewater treatment device

Abstract

The utility model discloses an ammonia nitrogen wastewater treatment device which comprises a front rectifying tower and a rear rectifying tower which are connected in series, a tower kettle outlet of the front rectifying tower is connected with a feed port of the rear rectifying tower through a first connecting pipe, and a rear tower reboiler is arranged at the tower bottom of the rear rectifying tower. And a tower top outlet of the front rectifying tower is connected with a hot side inlet of the rear tower reboiler through a second connecting pipe. According to the ammonia-nitrogen wastewater treatment device disclosed by the utility model, ammonia nitrogen in high-salt and high-ammonia-nitrogen wastewater is recycled by double-effect downstream rectification of the front and rear rectifying towers, and heat carried by ammonia-water mixed steam at the top of the front rectifying tower is fully recycled as a heat source of a reboiler of the rear rectifying tower; and the amount of circulating cooling water required for cooling the condenser at the top of the rear rectifying tower is also reduced, the consumption of heating steam, circulating cooling water and electric energy is greatly reduced, and compared with the conventional single-tower steam stripping deamination, the energy consumption can be saved by 30-45%, and the energy-saving effect is remarkable.

Description

Technical Field

[0001] The utility model belongs to the field of waste treatment, and in particular relates to a wastewater treatment device. Background Art

[0002] In the production of metallurgy, chemical industry, new energy materials, lithium battery nickel-cobalt-manganese ternary precursors and other industries, a large amount of industrial wastewater containing high salt and high ammonia nitrogen is often produced. For example, in the lithium battery nickel-cobalt-manganese ternary precursor industry that has been booming in my country in recent years, according to statistics, for every ton of nickel-cobalt-manganese ternary precursor produced, 18-30 tons of high-salt and high-ammonia nitrogen wastewater is produced. The wastewater contains 60-120g / L of sodium sulfate and up to 2-15g / L of ammonia nitrogen. If this type of wastewater is directly discharged without treatment, it will cause great harm to the ecological environment.

[0003] At present, the more mature process methods for the treatment of ammonia nitrogen in high-salt and high-ammonia nitrogen wastewater are air stripping and steam stripping. Both methods use the fact that free ammonia is easy to volatilize from the liquid phase into the gas phase at different temperatures and pressures, thereby achieving separation from the liquid phase. However, they also have some defects and shortcomings: for example, after the air stripping method is used, the wastewater still contains 50-300 mg / L ammonia nitrogen, which does not meet the emission standards, and the residual ammonia nitrogen needs to be further treated in depth. In addition, this process will produce a large amount of secondary pollution such as tail gas, and has now been gradually eliminated. The steam stripping deamination method has a good effect in removing ammonia nitrogen, but it has the problems of low energy utilization efficiency and high energy consumption. According to statistics, its steam energy consumption can account for more than 90% of the energy consumption of the entire system, and the heat of the ammonia-water mixed steam at the top of the tower accounts for about 80% of the system energy consumption. This part of the heat is lost by the circulating cooling water, and a large amount of circulating cooling water and electricity are consumed in addition. Utility Model Content

[0004] The technical problem to be solved by the utility model is to overcome the deficiencies and defects mentioned in the above background technology and provide an ammonia nitrogen wastewater treatment device which can significantly reduce the consumption of heating steam, circulating cooling water and electric energy.

[0005] In order to solve the above technical problems, the technical solution proposed by the utility model is:

[0006] An ammonia nitrogen wastewater treatment device comprises a front distillation tower and a rear distillation tower connected in series, the bottom outlet of the front distillation tower is connected to the feed inlet of the rear distillation tower through a first connecting pipe, a rear tower reboiler is provided at the bottom of the rear distillation tower, and the top outlet of the front distillation tower is connected to the hot side inlet of the rear tower reboiler through a second connecting pipe.

[0007] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the hot side outlet branch of the rear tower reboiler is provided with a first branch and a second branch, the first branch is connected to the reflux port of the front distillation tower through the front tower reflux pump, and the second branch is connected to the ammonia water storage tank.

[0008] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the top outlet of the post-distillation tower is connected to the hot side inlet of the top condenser through a third connecting pipe, and the hot side outlet branch of the top condenser is provided with a third branch and a fourth branch, the third branch is connected to the reflux port of the post-distillation tower, and the fourth branch is connected to the ammonia water storage tank.

[0009] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the feed port of the front distillation tower is connected to a raw water feed pump through a fourth connecting pipe, and a raw water preheater is provided on the fourth connecting pipe. The raw water preheater is used to preheat the raw water to reduce the load in the front distillation tower.

[0010] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the bottom outlet of the post-rectification tower is connected to the hot side inlet of the raw water preheater through a fifth connecting pipe, and the fifth connecting pipe is also connected to the cold side inlet of the post-rectification tower reboiler through a fifth branch, and the cold side outlet of the post-rectification tower reboiler is connected to the post-rectification tower. The heat source of the above-mentioned raw water preheater can come from the bottom liquid of the post-rectification tower, which can make full use of the heat of the bottom liquid and reduce the energy consumption of the entire system.

[0011] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, a front tower reboiler is provided at the bottom of the front distillation tower, the first connecting pipe is also connected to the cold side inlet of the front tower reboiler through the sixth branch, and the cold side outlet of the front tower reboiler is connected to the front distillation tower.

[0012] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the front distillation tower and the rear distillation tower are plate towers or plate-type packed composite towers. More preferably, the front distillation tower and the rear distillation tower are plate-type packed composite towers, and the stripping section of the plate-type packed composite tower is provided with tower plates, and the distillation section is provided with packing. The front distillation tower and the rear distillation tower of the utility model adopt plate-type packed composite towers, which can play an energy-saving role, and can also reduce the tower height and save equipment investment costs.

[0013] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the front distillation tower is a pressure tower, and the rear distillation tower is a normal pressure tower. The front distillation tower is a pressure tower (high pressure tower), and the rear distillation tower is a normal pressure tower. The pressure difference between the front and rear towers can meet the heat exchange temperature difference requirement of the reboiler of the rear tower.

[0014] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the heat provided by the front distillation tower must be able to meet the normal operation of the rear distillation tower. This setting is based on the need for heat balance. The front distillation tower relies on consuming fresh steam for heating, and the rear distillation tower relies on the steam from the top of the front distillation tower for heating, which can ensure energy balance.

[0015] In the above-mentioned ammonia nitrogen wastewater treatment device, preferably, the raw water preheater is a shell and tube heat exchanger or a plate heat exchanger, more preferably a plate heat exchanger. The front tower reboiler and the rear tower reboiler are thermosyphon reboilers. The top condenser is a shell and tube heat exchanger or a plate heat exchanger, more preferably a plate heat exchanger, and further preferably a semi-welded plate heat exchanger.

[0016] The utility model also provides a treatment process of an ammonia nitrogen wastewater treatment device, comprising the following steps:

[0017] (1) The preheated high-salt and high-ammonia nitrogen wastewater is passed into the front distillation tower. The wastewater entering the bottom of the tower is further heated by the front tower reboiler to generate rising steam that transfers mass, heat and momentum with the downstream wastewater in the tower. The light component ammonia enters the gas phase and enters the rear tower reboiler as its heat source after being concentrated in the distillation section. The condensation latent heat of the ammonia-water mixed steam is used to heat the bottom material of the rear distillation tower. Part of the condensate flows back to the top of the front distillation tower, and the other part is extracted as a high-purity ammonia product.

[0018] (2) As the wastewater flows down the front distillation tower step by step, the light component ammonia continuously enters the gas phase, and the heavy component salt and residual ammonia enter the tower bottom with the liquid phase. Part of it is circulated and heated in the reboiler of the front tower, and the other part enters the rear distillation tower.

[0019] (3) The wastewater in the bottom of the post-rectification tower is further heated by the reboiler of the post-rectification tower. The rising steam generated transfers mass, heat and momentum with the downstream wastewater in the tower. The light component ammonia enters the gas phase and enters the top condenser after being concentrated in the distillation section. Part of the condensate flows back to the top of the post-rectification tower, and the other part is extracted as a high-purity ammonia product. The concentration of the recovered high-purity ammonia is 8-20%, and the concentration can be adjusted according to production requirements.

[0020] (4) As the wastewater enters the post-distillation tower, light ammonia components continuously enter the gas phase as it flows down the tower plates at each level. The ammonia nitrogen content in the liquid phase reaches below 10 mg / L before it reaches the bottom of the tower, meeting the current emission standards. Part of the bottom liquid is heated in a reboiler in the post-distillation tower, and the other part is discharged from the system as qualified liquid for deammoniation.

[0021] The typical components of the above-mentioned high-salt and high-ammonia nitrogen wastewater may be: sodium sulfate 60-120g / L, ammonia nitrogen 2-15g / L, suspended solids <0.5g / L, pH=11-13, COD <0.5g / L; preferably, ammonia nitrogen 6-12g / L, suspended solids <0.2g / L, pH>11.5, COD <0.2g / L.

[0022] The ammonia nitrogen wastewater treatment device of the present utility model adopts the mode of connecting the front and rear distillation towers in series, and regards the front and rear distillation towers as a whole to consider the quality and energy balance distribution. For the ammonia nitrogen wastewater treatment of the present utility model, compared with the situation where the double towers are separated independently, the energy saving is very obvious. In addition, the ammonia nitrogen wastewater treatment device of the present utility model needs to adopt the mode of connecting the double towers in series (i.e., the mode of downstream), which is more conducive to energy saving. Practice shows that when the same treatment is carried out, the downstream of the present utility model saves at least 10% of energy consumption compared with the parallel flow. At the same time, the mode of downstream can have fewer pipelines, fewer auxiliary equipment, and simpler processes. For example, the present utility model only needs to equip the rear distillation tower with a tower top condenser, and the front distillation tower does not need to be provided with a tower top condenser. For example, the present utility model only needs to equip the front distillation tower with a raw water preheater, and the liquid inlet of the rear distillation tower comes completely from the front distillation tower, and the rear distillation tower does not need to be provided with a raw water preheater. For example, the tower reactor of the front distillation tower is all sent to the rear distillation tower, and there is no need to set the tower reactor supporting facilities such as storage tanks.

[0023] Compared with the prior art, the advantages of the utility model are:

[0024] (1) The ammonia nitrogen wastewater treatment device of the utility model adopts a front and a rear distillation tower to double-effect downstream distillation to recover ammonia nitrogen from high-salt and high-ammonia nitrogen wastewater, fully recovers and utilizes the heat carried by the ammonia-water mixed steam at the top of the front distillation tower as the heat source of the reboiler of the rear distillation tower, and also reduces the amount of circulating cooling water required for cooling the condenser at the top of the rear distillation tower, greatly reducing the consumption of heating steam, circulating cooling water and electric energy. Compared with the conventional single-tower stripping deamination, it can save 30-45% of energy consumption, with significant energy saving effect.

[0025] (2) The ammonia nitrogen wastewater treatment device of the utility model adopts a double-effect co-current method of front and rear distillation towers, and regards the front and rear distillation towers as a whole to consider the quality and energy balance distribution, which is more energy-saving, can have fewer pipelines, fewer ancillary equipment, and a simpler process.

[0026] (3) The ammonia nitrogen wastewater treatment device of the utility model can use two small-diameter double-effect distillation towers. Compared with the conventional large-diameter single-tower stripping deammoniation process of the same scale, the primary equipment cost is only increased by about 20%, but the annual operating cost of the system is saved by 25-30%. In addition, the process flow is simple and easy to operate, the process is mature, and can be widely used in engineering practice.

[0027] (4) The ammonia nitrogen wastewater treatment device of the utility model can obtain 8-20% high-purity ammonia water. The concentration of liquid ammonia nitrogen after treatment and deammonification is less than 10 mg / L, which meets the current emission standards and achieves the standard treatment of ammonia nitrogen in wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a schematic diagram of the structure of the ammonia nitrogen wastewater treatment device in Example 1.

[0030] Figure 2 This is a schematic diagram of the structure of the ammonia nitrogen wastewater treatment device in Comparative Example 1.

[0031] Figure 3 This is a schematic diagram of the structure of the ammonia nitrogen wastewater treatment device in Comparative Example 2.

[0032] Legend

[0033] 1. Raw water feed pump; 2. Raw water preheater; 3. Front tower reboiler; 4. Front distillation tower; 5. Front tower reflux pump; 6. Rear tower reboiler; 7. Rear distillation tower; 8. Top condenser; 11. First connecting pipe; 12. Second connecting pipe; 13. Third connecting pipe; 14. Fourth connecting pipe; 15. Fifth connecting pipe; 21. First branch; 22. Second branch; 23. Third branch; 24. Fourth branch; 25. Fifth branch; 26. Sixth branch. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0035] It should be noted that when an element is described as being "fixed, fixed, connected or connected to" another element, it can be directly fixed, fixed, connected or connected to the other element, or it can be indirectly fixed, fixed, connected or connected to the other element through other intermediate connectors.

[0036] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present utility model.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0038] Example:

[0039] like Figure 1 As shown, the ammonia nitrogen wastewater treatment device of this embodiment includes a front distillation tower 4 and a rear distillation tower 7 connected in series, the bottom outlet of the front distillation tower 4 is connected to the feed inlet of the rear distillation tower 7 through a first connecting pipe 11, the bottom of the rear distillation tower 7 is provided with a rear tower reboiler 6, and the top outlet of the front distillation tower 4 is connected to the hot side inlet of the rear tower reboiler 6 through a second connecting pipe 12.

[0040] In this embodiment, the hot side outlet branch of the rear tower reboiler 6 is provided with a first branch 21 and a second branch 22. The first branch 21 is connected to the reflux port of the front distillation tower 4 through the front tower reflux pump 5, and the second branch 22 is connected to the ammonia water storage tank.

[0041] In this embodiment, the top outlet of the post-distillation tower 7 is connected to the hot side inlet of the top condenser 8 through the third connecting pipe 13, and the hot side outlet branch of the top condenser 8 is provided with a third branch 23 and a fourth branch 24, the third branch 23 is connected to the reflux port of the post-distillation tower 7, and the fourth branch 24 is connected to the ammonia water storage tank.

[0042] In this embodiment, the feed inlet of the front distillation tower 4 is connected to the raw water feed pump 1 through the fourth connecting pipe 14 , and the fourth connecting pipe 14 is provided with a raw water preheater 2 .

[0043] In this embodiment, the bottom outlet of the post-distillation tower 7 is connected to the hot side inlet of the raw water preheater 2 through the fifth connecting pipe 15, and the fifth connecting pipe 15 is also connected to the cold side inlet of the post-tower reboiler 6 through the fifth branch 25, and the cold side outlet of the post-tower reboiler 6 is connected to the post-distillation tower 7.

[0044] In this embodiment, a front tower reboiler 3 is provided at the bottom of the front distillation tower 4, and the first connecting pipe 11 is also connected to the cold side inlet of the front tower reboiler 3 through the sixth branch 26, and the cold side outlet of the front tower reboiler 3 is connected to the front distillation tower 4.

[0045] In this embodiment, the front distillation tower 4 and the rear distillation tower 7 are plate-type packed composite towers, and the stripping section of the plate-type packed composite tower is provided with tower plates, and the distillation section is provided with packing.

[0046] In this embodiment, the front distillation tower 4 is a pressure tower, and the rear distillation tower 7 is a normal pressure tower.

[0047] In this embodiment, the raw water preheater 2 is a plate heat exchanger, the front tower reboiler 3 and the rear tower reboiler 6 are thermosyphon reboilers, and the tower top condenser 8 is a shell and tube heat exchanger.

[0048] The ammonia nitrogen wastewater treatment device of this embodiment can be composed of only Figure 1 The components shown in the figure have a simpler structure, fewer pipelines and fewer auxiliary equipment.

[0049] The above-mentioned ammonia nitrogen wastewater treatment device is used to treat high-salt and high-ammonia nitrogen wastewater generated by the production of nickel-cobalt-manganese ternary precursors for lithium batteries of a new energy material, with a water volume of 1500m 3 / d, the wastewater composition is: sodium sulfate 80-100g / L, ammonia nitrogen 8-12g / L, suspended solids <0.2g / L, pH=13, COD <0.2g / L, including the following steps:

[0050] (1) The preheated high-salt and high-ammonia nitrogen wastewater is passed into the front distillation tower 4. The wastewater entering the tower bottom is further heated by the front tower reboiler 3 to generate rising steam that transfers mass, heat and momentum with the downstream wastewater in the tower. The light component ammonia enters the gas phase and enters the rear tower reboiler 6 as its heat source after being concentrated in the distillation section. Part of the condensate flows back to the top of the front distillation tower 4, and the other part is extracted as a product of 15% high-purity ammonia water.

[0051] (2) As the wastewater flows down the front distillation tower 4 step by step, the light component ammonia continuously enters the gas phase, and the heavy component salt and residual ammonia enter the tower kettle with the liquid phase. A part of it is circulated and heated in the front tower reboiler 3, and the other part enters the rear distillation tower 7.

[0052] (3) The wastewater entering the bottom of the post-rectification tower 7 is further heated by the post-rectification tower reboiler 6 to generate rising steam, which transfers mass, heat and momentum with the downstream wastewater in the tower. The light component ammonia enters the gas phase and enters the top condenser 8 after being concentrated in the distillation section. Part of the condensate flows back to the top of the post-rectification tower 7, and the other part is extracted as a product of 15% high-purity ammonia water.

[0053] (4) As the wastewater enters the post-rectification tower 7 and flows down the tower plates at each level, light ammonia components continuously enter the gas phase, and the ammonia nitrogen content in the liquid phase reaches below 10 mg / L before reaching the tower kettle. A portion of the kettle liquid is circulated and heated in the post-rectification tower reboiler 6, and the other portion is discharged from the system as deammoniation qualified liquid.

[0054] When the device is running, the diameter of the front distillation tower 4 is 900mm, and the diameter of the rear distillation tower 7 is 1400mm. 3 The steam consumption required for treating high-salt and high-ammonia nitrogen wastewater is 62kg (converted to 0.5MPa(A)), the low-pressure steam consumption is 3875kg / h, and the circulating cooling water consumption is 300m 3 / h. Compared with the traditional steam stripping deamination process, it can save 38% energy. Although the primary equipment cost is slightly increased, the annual operating cost of the entire system is reduced by 25% to 30%.

[0055] Comparative Example 1:

[0056] The water quality of the high-salt and high-ammonia nitrogen wastewater in this comparative example is the same as that in Example 1. Figure 2 The conventional steam stripping deamination process shown in the figure is used to treat the wastewater. The treatment process is as follows: the wastewater raw water and the deamination tower bottom liquid enter the deamination tower after heat exchange through a plate heat exchanger, and low-pressure saturated steam enters the tower from the bottom of the tower to transfer mass and heat with the wastewater flowing down from the tower plate, and the light component ammonia enters the gas phase. The ammonia-water mixed steam enters the condenser through the top of the tower and is condensed by heat exchange with the circulating cooling water. 60% of the condensate is returned to the top of the tower for reflux concentration, and the remaining condensate is extracted as a product to obtain ammonia water with a concentration of 15%; in the process of wastewater flowing down the tower plates at each level, the light component ammonia continuously enters the gas phase, and the ammonia nitrogen content of the liquid phase reaches less than 10 mg / L before the liquid phase reaches the tower bottom; when the treatment process is in operation, the diameter of the single tower is 1800 mm, and each treatment is 1m 3 The high-salt and high-ammonia nitrogen wastewater requires 100kg of low-pressure steam (0.5MPa(A)), the low-pressure steam consumption is 6250kg / h, and the circulating cooling water demand is 800m 3 / h.

[0057] Comparative Example 2:

[0058] The water quality of the high-salt and high-ammonia nitrogen wastewater in this comparative example is the same as that in Example 1. Figure 3 The wastewater is treated by the conventional steam stripping deamination process shown in the figure. The difference from comparative example 1 is that the heating method of this comparative example adopts the method of indirectly heating the bottom liquid with a reboiler. The treatment process is as follows: the wastewater raw water and the bottom liquid of the deamination tower enter the deamination tower after heat exchange through a plate heat exchanger. The low-pressure saturated steam indirectly heats the bottom liquid through a reboiler. The secondary steam generated enters the tower from the bottom of the tower and conducts mass and heat transfer with the wastewater flowing down from the tower plate. The light component ammonia enters the gas phase. The ammonia-water mixed steam enters the condenser through the top of the tower and is condensed by heat exchange with the circulating cooling water. 60% of the condensate is returned to the top of the tower for reflux concentration, and the remaining condensate is extracted as a product to obtain ammonia water with a concentration of 15%. In the process of wastewater flowing down the tower plates at each level, the light component ammonia continuously enters the gas phase, and the ammonia nitrogen content reaches less than 10 mg / L before the liquid phase reaches the bottom of the tower. When the treatment process is in operation, the diameter of the single tower is 1800 mm, and each treatment is 1m 3 The high-salt and high-ammonia nitrogen wastewater requires 120kg of low-pressure steam (0.5MPa(A)), the low-pressure steam consumption is 7500kg / h, and the circulating cooling water demand is 800m 3 / h.

Claims

1. An ammonia nitrogen wastewater treatment device, characterized in that: The invention comprises a front distillation tower (4) and a rear distillation tower (7) which are connected in series, wherein the bottom outlet of the front distillation tower (4) is connected to the feed inlet of the rear distillation tower (7) via a first connecting pipe (11), a rear tower reboiler (6) is provided at the bottom of the rear distillation tower (7), and the top outlet of the front distillation tower (4) is connected to the hot side inlet of the rear tower reboiler (6) via a second connecting pipe (12).

2. The ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: The hot side outlet branch of the rear tower reboiler (6) is provided with a first branch (21) and a second branch (22), wherein the first branch (21) is connected to the reflux port of the front distillation tower (4) through a front tower reflux pump (5), and the second branch (22) is connected to an ammonia water storage tank.

3. The ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: The top outlet of the post-rectification tower (7) is connected to the hot side inlet of the top condenser (8) through a third connecting pipe (13); the hot side outlet branch of the top condenser (8) is provided with a third branch (23) and a fourth branch (24); the third branch (23) is connected to the reflux port of the post-rectification tower (7); and the fourth branch (24) is connected to an ammonia water storage tank.

4. The ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: The feed inlet of the front distillation tower (4) is connected to a raw water feed pump (1) via a fourth connecting pipe (14), and a raw water preheater (2) is provided on the fourth connecting pipe (14).

5. The ammonia nitrogen wastewater treatment device according to claim 4, characterized in that: The bottom outlet of the post-rectification tower (7) is connected to the hot side inlet of the raw water preheater (2) via a fifth connecting pipe (15), and the fifth connecting pipe (15) is also connected to the cold side inlet of the post-rectification tower reboiler (6) via a fifth branch (25), and the cold side outlet of the post-rectification tower reboiler (6) is connected to the post-rectification tower (7).

6. The ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: A front-tower reboiler (3) is provided at the bottom of the front distillation tower (4), and the first connecting pipe (11) is also connected to the cold side inlet of the front-tower reboiler (3) through a sixth branch (26), and the cold side outlet of the front-tower reboiler (3) is connected to the front distillation tower (4).

7. The ammonia nitrogen wastewater treatment device according to any one of claims 1 to 6, characterized in that: The front distillation tower (4) and the rear distillation tower (7) are plate towers or plate-filled composite towers.

8. The ammonia nitrogen wastewater treatment device according to claim 7, characterized in that: The front distillation tower (4) and the rear distillation tower (7) are plate-type packed composite towers, and the stripping section of the plate-type packed composite tower is provided with tower plates, and the distillation section is provided with packing.

9. The ammonia nitrogen wastewater treatment device according to any one of claims 1 to 6, characterized in that: The front distillation tower (4) is a pressure tower, and the rear distillation tower (7) is a normal pressure tower.

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