High-efficiency ammonia-nitrogen wastewater treatment device

Abstract

The application discloses a high-efficiency ammonia-nitrogen wastewater treatment device, and belongs to the technical field of wastewater treatment. The device comprises a wastewater pretreatment unit, a stripping ammonia removal unit and an ammonia gas absorption unit which are connected in sequence. The wastewater pretreatment unit realizes efficient mixing of lye and wastewater through a pipeline reactor, and recycles waste heat by using an import / export heat exchanger. The stripping ammonia removal unit adopts a stripping ammonia removal tower, and efficiently removes ammonia-nitrogen in wastewater through steam stripping. The ammonia gas absorption unit realizes cyclic absorption of ammonia gas through an ammonia gas absorption tower, generates ammonium sulfate for recycling, and simultaneously returns tail gas to the stripping ammonia removal tower to realize steam circulation. The application realizes efficient removal of ammonia-nitrogen, and the ammonia-nitrogen removal rate reaches more than 95%. Through waste heat recovery and steam circulation, steam consumption is reduced by 20%-30%. The application realizes resource recycling of ammonia resources, has good environmental and economic benefits, and is suitable for treatment of high-concentration ammonia-nitrogen wastewater in the chemical industry, the pharmaceutical industry and the like.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a high-efficiency ammonia nitrogen wastewater treatment device. Background Technology

[0002] Ammonia nitrogen is one of the major pollutants in water bodies, originating from a wide range of industries including chemical, pharmaceutical, food processing, coking, and aquaculture. Direct discharge of ammonia nitrogen wastewater leads to eutrophication, causing ecological problems such as cyanobacterial blooms and severely damaging water quality. Furthermore, high concentrations of ammonia nitrogen are toxic to aquatic organisms, threatening ecosystem balance and even impacting human health through the food chain. Therefore, efficient treatment of ammonia nitrogen wastewater to achieve both removal and resource recovery is a crucial research topic and industrial need in the environmental protection field.

[0003] Currently, ammonia nitrogen wastewater treatment technologies mainly include biological methods, chemical precipitation, adsorption, and stripping. While biological methods have lower operating costs, they have long treatment cycles, are greatly affected by environmental factors such as water quality and temperature, and have limited effectiveness in treating high-concentration ammonia nitrogen wastewater, making it difficult to meet discharge standards. Chemical precipitation requires the addition of large amounts of chemical reagents, easily causing secondary pollution, and has high reagent costs and low ammonia nitrogen recovery rates. Adsorption methods suffer from rapid adsorbent saturation and frequent regeneration, limiting their treatment scale.

[0004] Steam stripping is widely used in the treatment of high-concentration ammonia nitrogen wastewater due to its advantages such as high treatment efficiency and wide applicability to ammonia nitrogen concentrations. However, existing steam stripping ammonia removal devices generally have the following drawbacks: First, the wastewater pretreatment effect is poor, and the alkaline solution is not mixed evenly with the wastewater, resulting in a decrease in subsequent ammonia removal efficiency; second, the energy utilization rate is low, as there is no effective heat exchange between the wastewater to be treated and the wastewater after ammonia removal, resulting in high steam consumption and high operating costs; third, the ammonia absorption system has insufficient stability, which easily leads to problems such as ammonia escape in the tail gas or waste of the absorbent. Utility Model Content

[0005] This utility model addresses the aforementioned problems in the existing technology by providing a highly efficient ammonia nitrogen wastewater treatment device.

[0006] The objective of this utility model is mainly achieved through the following solution:

[0007] The high-efficiency ammonia nitrogen wastewater treatment device includes a wastewater pretreatment unit, a stripping ammonia removal unit, and an ammonia absorption unit connected in sequence.

[0008] The wastewater pretreatment unit includes an ammonia nitrogen wastewater equalization tank, a first wastewater pipeline, an alkali addition device, and a pipeline reactor. The ammonia nitrogen wastewater equalization tank is connected to the stripping and ammonia removal unit through the first wastewater pipeline. An ammonia nitrogen wastewater pump, a pipeline reactor, and inlet and outlet heat exchangers are sequentially arranged along the water flow direction on the first wastewater pipeline. The outlet end of the alkali addition device is connected to the pipeline reactor.

[0009] The stripping ammonia removal unit includes a stripping ammonia removal tower; the upper part of the stripping ammonia removal tower is provided with a wastewater inlet, which is connected to the first wastewater pipeline; the lower part of the stripping ammonia removal tower is provided with a steam inlet, and the bottom of the stripping ammonia removal tower is provided with an ammonia removal wastewater outlet; the ammonia removal wastewater outlet is discharged through a second wastewater pipeline, and the second wastewater pipeline is equipped with an ammonia removal water pump and inlet and outlet heat exchangers;

[0010] The ammonia absorption unit includes an ammonia absorption tower; the top gas phase outlet of the stripping ammonia removal tower is connected to the lower part of the ammonia absorption tower through a second steam pipe, and a steam circulation pump is provided on the second steam pipe; the top of the ammonia absorption tower is provided with a tail gas outlet, and is connected to the steam inlet of the lower part of the stripping ammonia removal tower through a third steam pipe.

[0011] The ammonia absorption tower is provided with an acid inlet at the top, which is connected to a first acid pipe. The first acid pipe is connected to an acid supply device. The ammonia absorption tower is provided with an absorbent outlet at the bottom, which is connected to the inlet of a sulfuric acid circulation pump through a second acid pipe. The outlet of the sulfuric acid circulation pump is connected to the first acid pipe, and an ammonium sulfate recovery pipe is also provided on the second acid pipe.

[0012] Preferably, the alkali addition device includes an alkali tank and an alkali pipeline. One end of the alkali pipeline is connected to the alkali tank, and the other end is connected to the inlet of the pipeline reactor. A first shut-off valve, an alkali metering pump, a first check valve, a second shut-off valve, and a first flow meter are sequentially installed on the alkali pipeline along the flow direction of the alkali.

[0013] Preferably, the first wastewater pipeline is provided with a third shut-off valve, an ammonia nitrogen wastewater pump, a second check valve, a fourth shut-off valve, a pipeline reactor, a first pH sensor, a first electric valve, a first flow display controller, an inlet and outlet heat exchanger, and a first thermometer in sequence along the water flow direction.

[0014] The first electric valve and the first flow display controller are used together, and the first pH sensor is used together with the alkaline metering pump.

[0015] Preferably, the second wastewater pipeline is provided with a fifth shut-off valve, an ammonia removal pump, a third check valve, a sixth shut-off valve, a second electric valve, an inlet and outlet heat exchanger, and a second thermometer in sequence along the water flow direction.

[0016] The bottom of the stripping ammonia removal tower is equipped with a first liquid level controller, which is used in conjunction with a second electric valve.

[0017] Preferably, the inlet and outlet heat exchangers are shell and tube heat exchangers, with the first wastewater pipe passing through the shell side of the inlet and outlet heat exchangers and the second wastewater pipe passing through the tube side of the inlet and outlet heat exchangers, thereby realizing heat exchange between the ammonia nitrogen wastewater to be treated and the wastewater after ammonia removal.

[0018] Preferably, the steam inlet at the bottom of the stripping ammonia removal tower is also connected to a first steam pipe for introducing fresh external steam.

[0019] A third electric valve and a second flow display controller are installed sequentially along the steam flow direction on the first steam pipe, and the third electric valve and the second flow display controller are used in conjunction.

[0020] The lower part of the stripping ammonia removal tower is also connected to a vent pipe, and a seventh shut-off valve is installed on the vent pipe.

[0021] The top of the stripping ammonia removal tower is equipped with a third thermometer and a first pressure gauge, the upper part is equipped with a fourth thermometer, and the lower part is equipped with a fifth thermometer.

[0022] Preferably, the acid supply device includes a sulfuric acid tank, one end of the first acid pipeline is connected to the sulfuric acid tank, and the other end is connected to the acid inlet at the top of the ammonia absorption tower. A tap water pipeline is connected to the sulfuric acid tank, one end of which is a tap water inlet and the other end is connected to the sulfuric acid tank for replenishing the dilution water in the sulfuric acid tank.

[0023] Along the flow direction of the acid, the first acid pipeline is sequentially equipped with an eighth shut-off valve, a sulfuric acid dosing pump, a fourth check valve, a ninth shut-off valve, and a second flow meter.

[0024] The second acid pipeline is equipped with a tenth shut-off valve, a sulfuric acid circulation pump, a fifth check valve, an eleventh shut-off valve, a twelfth shut-off valve, and a second pH sensor in sequence along the flow direction of the acid. The second pH sensor is used in conjunction with the sulfuric acid dosing pump.

[0025] Preferably, the ammonium sulfate recovery pipeline is connected between the eleventh and twelfth shut-off valves, and a fourth electric valve and a sixth thermometer are sequentially installed on the ammonium sulfate recovery pipeline along the flow direction of the ammonium sulfate solution.

[0026] Preferably, the ammonia absorption tower is equipped with a seventh thermometer and a second pressure gauge at the top, an eighth thermometer at the top, and a ninth thermometer at the bottom.

[0027] A second liquid level controller is also installed at the bottom of the ammonia absorption tower, which works in conjunction with a fourth electric valve.

[0028] Preferably, the pipeline reactor is a static mixer or a dynamic mixing pump, used to mix the alkali solution from the alkali solution addition device with the ammonia-containing wastewater from the first wastewater pipeline.

[0029] In summary, compared with the prior art, the present invention has the following beneficial technical effects:

[0030] (1) The present invention sets up a pipeline reactor in the wastewater pretreatment unit to realize the efficient mixing of alkaline solution and wastewater, and ensure that the pH value of the wastewater is uniformly adjusted to the alkaline range so that ammonia nitrogen is fully converted into free ammonia; the steam and wastewater in the stripping deammoniation tower are in full counter-current contact, and the gas-liquid mass transfer efficiency is high, which can efficiently remove ammonia nitrogen from the wastewater; the ammonia absorption unit adopts the acid liquid circulation absorption mode, combined with the pH value control, to ensure that ammonia is fully absorbed, and finally the ammonia nitrogen content of the deammoniation wastewater is stably up to standard, and the ammonia nitrogen removal rate can reach more than 95%;

[0031] (2) This utility model is equipped with inlet and outlet heat exchangers, which use the residual heat of the high temperature wastewater after ammonia removal to heat the room temperature wastewater to be treated, thereby increasing the temperature of the wastewater to be treated. This not only reduces the steam consumption in the subsequent stripping ammonia removal process, but also reduces the discharge temperature of the ammonia removal wastewater, thus reducing energy waste and significantly reducing the operating cost of the device. At the same time, the tail gas reflux design of the ammonia absorption unit realizes the recycling of steam, further reducing energy consumption.

[0032] (3) In this utility model, the ammonia absorption unit generates ammonium sulfate by reacting sulfuric acid with ammonia. When the concentration of ammonium sulfate in the absorption liquid reaches the standard, it can be recovered through the ammonium sulfate recovery pipeline. This not only solves the environmental protection problem of ammonia emission, but also realizes the resource utilization of ammonia resources, creating additional economic benefits for enterprises, which is in line with the environmental protection concept of "pollution reduction and carbon reduction, resource recycling". Attached Figure Description

[0033] Figure 1 This is a process flow diagram of this utility model.

[0034] Reference numerals in the attached diagram: 1. Ammonia nitrogen wastewater equalization tank; 2. First wastewater pipeline; 3. Pipeline reactor; 4. Ammonia nitrogen wastewater pump; 5. Inlet and outlet heat exchangers; 6. Stripping ammonia removal tower; 7. Second wastewater pipeline; 8. Ammonia removal water pump; 9. Ammonia absorption tower; 10. Second steam pipeline; 11. Steam circulation pump; 12. Third steam pipeline; 13. First acid pipeline; 14. Second acid pipeline; 15. Sulfuric acid circulation pump; 16. Ammonium sulfate recovery pipeline; 17. Alkali tank; 18. Alkali pipeline; 19. First shut-off valve; 20. Alkali metering pump; 21. First check valve; 22. Second shut-off valve; 23. First flow meter; 24. Third shut-off valve; 25. Second check valve; 26. Fourth shut-off valve; 27. First pH sensor; 28. First electric valve; 29. ​​First flow display controller; 30. First thermometer; 31. Fifth shut-off valve; 32. Third check valve; 33. Sixth shut-off valve; 34. Second electric valve; 35. Second thermometer; 36. First liquid level controller; 37. First steam pipe; 38. Third electric valve; 39. Second flow display controller; 40. Vent pipe; 41. Seventh shut-off valve; 42. Third thermometer; 43. First pressure gauge; 44. Fourth thermometer; 45. Fifth thermometer; 46. Sulfuric acid tank; 47. Tap water pipe; 48. Eighth shut-off valve; 49. Sulfuric acid dosing pump; 50. Fourth check valve; 51. Ninth shut-off valve; 52. Second flow meter; 53. Tenth shut-off valve; 54. Fifth check valve; 55. Eleventh shut-off valve; 56. Twelfth shut-off valve; 57. Second pH sensor; 58. Fourth electric valve; 59. Sixth thermometer; 60. Seventh thermometer; 61. Second pressure gauge; 62. Eighth thermometer; 63. Ninth thermometer; 64. Second liquid level controller. Detailed Implementation

[0035] The technical solution of this utility model will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of this utility model is not limited to the following embodiments, and any modifications and / or alterations made to this utility model will fall within the protection scope of this utility model.

[0036] like Figure 1 As shown, this utility model discloses a technical solution: a high-efficiency ammonia nitrogen wastewater treatment device, comprising a wastewater pretreatment unit, a stripping ammonia removal unit, and an ammonia absorption unit connected in sequence. Each unit works synergistically to achieve efficient treatment of ammonia nitrogen wastewater and recovery of ammonia resources.

[0037] Wastewater pretreatment unit: includes ammonia nitrogen wastewater equalization tank 1, first wastewater pipeline 2, alkali solution addition device and pipeline reactor 3. Its core function is to adjust the quality and quantity of wastewater and achieve efficient mixing of alkali solution and wastewater, creating favorable conditions for subsequent stripping and ammonia removal.

[0038] The ammonia nitrogen wastewater equalization tank 1 is used to collect and buffer the ammonia nitrogen wastewater to be treated, so as to avoid the impact of fluctuations in wastewater quality and quantity on subsequent treatment units. The ammonia nitrogen wastewater equalization tank 1 is connected to the stripping ammonia removal unit through the first wastewater pipeline 2, providing a channel for wastewater transportation.

[0039] Along the flow direction, the first wastewater pipeline 2 is equipped with an ammonia nitrogen wastewater pump 4, a pipeline reactor 3, and inlet / outlet heat exchangers 5. The ammonia nitrogen wastewater pump 4 provides power for wastewater transport, ensuring a stable flow rate to subsequent units. The pipeline reactor 3 provides an efficient reaction space for mixing the alkali solution and wastewater, improving mixing uniformity. The inlet / outlet heat exchangers 5 facilitate heat exchange between the ammonia nitrogen wastewater to be treated and the deammoniation-treated wastewater, recovering residual heat.

[0040] The outlet of the alkali addition device is connected to the pipeline reactor 3 for precise addition of alkali solution to the wastewater, adjusting the pH value of the wastewater to the alkaline range so that ammonia nitrogen exists in the form of free ammonia, facilitating subsequent stripping removal. The alkali addition device includes an alkali tank 17 and an alkali pipeline 18. One end of the alkali pipeline 18 is connected to the alkali tank 17, and the other end is connected to the inlet of the pipeline reactor 3. Along the flow direction of the alkali solution, the alkali pipeline 18 is sequentially equipped with a first shut-off valve 19, an alkali metering pump 20, a first check valve 21, a second shut-off valve 22, and a first flow meter 23. The first shut-off valve 19 and the second shut-off valve 22 control the opening and closing of the alkali pipeline; the alkali metering pump 20 enables precise metering and addition of alkali solution, and its dosage can be adjusted in real time according to the pH value of the wastewater; the first check valve 21 prevents wastewater from flowing back into the alkali pipeline, avoiding pipeline blockage or contamination; the first flow meter 23 is used to monitor the alkali addition flow rate in real time, facilitating the adjustment of operating parameters.

[0041] Furthermore, to enhance the automation control level of the pretreatment unit, a third shut-off valve 24, a second check valve 25, a fourth shut-off valve 26, a first pH sensor 27, a first electric valve 28, and a first flow display controller 29 are sequentially installed along the water flow direction on the first wastewater pipeline 2. The third shut-off valve 24 and the fourth shut-off valve 26 are used to control the opening and closing of the first wastewater pipeline; the second check valve 25 prevents the fluid from flowing back into the subsequent units; the first pH sensor 27 monitors the pH value of the wastewater at the outlet of the pipeline reactor 3 in real time and transmits the monitoring signal to the control system. The control system automatically adjusts the dosage of the alkali metering pump 20 according to the pH value change to achieve closed-loop control of alkali addition; the first electric valve 28 and the first flow display controller 29 work together. The first flow display controller 29 monitors the wastewater flow rate in real time. When the flow rate deviates from the set value, it automatically controls the opening of the first electric valve 28 to ensure stable wastewater flow.

[0042] The ammonia stripping unit includes a steam stripping tower 6, whose core function is to remove free ammonia from wastewater by using steam stripping, thereby separating ammonia nitrogen from wastewater.

[0043] The upper part of the stripping ammonia removal tower 6 is equipped with a wastewater inlet, which is connected to the first wastewater pipeline 2. The pretreated alkaline wastewater enters the stripping ammonia removal tower through this inlet. The lower part of the tower is equipped with a steam inlet for introducing steam. The steam flows from bottom to top and comes into full contact with the wastewater flowing from top to bottom inside the tower. Through gas-liquid mass transfer, the free ammonia in the wastewater is carried into the gas phase. The bottom of the tower is equipped with a deammoniation wastewater outlet for discharging deammoniation wastewater whose ammonia nitrogen content has met the standards.

[0044] The deammonia removal wastewater is discharged through the second wastewater pipeline 7, which is equipped with a deammonia removal pump 8 and inlet / outlet heat exchangers 5. The deammonia removal pump 8 provides power for the discharge of the deammonia removal wastewater, while the inlet / outlet heat exchangers 5 are used to exchange heat with the wastewater to be treated and recover the waste heat from the deammonia removal wastewater. To achieve stable control of the deammonia removal wastewater discharge, the second wastewater pipeline 7 is sequentially equipped with a fifth shut-off valve 31, a deammonia removal pump 8, a third check valve 32, a sixth shut-off valve 33, a second electric valve 34, and a second thermometer 35 along the water flow direction. The fifth shut-off valve 31 and the sixth shut-off valve 33 are used to control the opening and closing of the second wastewater pipeline; the third check valve 32 prevents fluid backflow; a first liquid level controller 36 is installed at the bottom of the stripping ammonia removal tower 6, which works in conjunction with the second electric valve 34. The first liquid level controller 36 monitors the liquid level at the bottom of the tower in real time. When the liquid level deviates from the set range, it automatically controls the opening of the second electric valve 34 to ensure the stability of the liquid level at the bottom of the tower and avoid the liquid level being too high or too low, which would affect the stripping effect; the second thermometer 35 is used to monitor the temperature of the deammoniation wastewater after heat exchange, providing a basis for evaluating the operating status of the heat exchanger.

[0045] Regarding the inlet and outlet heat exchanger 5, it specifically adopts a shell-and-tube heat exchanger structure. The first wastewater pipe 2 passes through the shell side of the inlet and outlet heat exchanger 5, and the second wastewater pipe 7 passes through the tube side of the inlet and outlet heat exchanger 5. The ambient temperature ammonia nitrogen wastewater to be treated enters the shell side and exchanges heat with the high temperature deammoniation wastewater flowing in the tube side. This raises the temperature of the wastewater to be treated and lowers the temperature of the deammoniation wastewater, which not only improves the efficiency of subsequent stripping deammoniation (high temperature is conducive to ammonia volatilization) but also reduces the temperature of the deammoniation wastewater discharge, achieving efficient energy recovery and utilization and reducing steam consumption.

[0046] To ensure the stable operation of the stripping ammonia removal tower 6, a first steam pipe 37 is connected to its lower steam inlet for introducing fresh external steam to compensate for system steam losses. A third electric valve 38 and a second flow display controller 39 are sequentially installed on the first steam pipe 37 along the steam flow direction. The third electric valve 38 and the second flow display controller 39 work together. The second flow display controller 39 monitors the fresh steam inflow in real time. When the flow rate deviates from the set value, it automatically controls the opening of the third electric valve 38 to ensure a stable steam supply. In addition, a vent pipe 40 is connected to the lower part of the stripping ammonia removal tower 6. A seventh shut-off valve 41 is installed on the vent pipe 40. When abnormal pressure occurs inside the tower or maintenance is required, the seventh shut-off valve 41 can be opened to vent and reduce pressure. To comprehensively monitor the operating status inside the tower, a third thermometer 42 and a first pressure gauge 43 are installed at the top of the stripping ammonia removal tower 6, a fourth thermometer 44 is installed at the top, and a fifth thermometer 45 is installed at the bottom. These are used to monitor the gas phase temperature at the top of the tower, the pressure at the top of the tower, the liquid phase temperature at the top of the tower, and the steam temperature at the bottom of the tower, respectively, providing a basis for adjusting the operating parameters.

[0047] Ammonia absorption unit: including ammonia absorption tower 9, whose core function is to efficiently absorb the ammonia-containing gas phase generated by stripping ammonia removal tower 6 to generate ammonium sulfate product, realize the recovery and utilization of ammonia resources, and at the same time prevent ammonia escape from causing secondary pollution.

[0048] The top gas phase outlet of the stripping ammonia removal tower 6 is connected to the lower part of the ammonia absorption tower 9 via a second steam pipe 10. The ammonia-containing gas phase enters the tower from the lower part of the ammonia absorption tower 9. A steam circulation pump 11 is installed on the second steam pipe 10 to provide power for the gas phase transport, ensuring that the ammonia-containing gas phase enters the absorption tower at a set flow rate. The top of the ammonia absorption tower 9 is equipped with a tail gas outlet, which is connected to the steam inlet at the lower part of the stripping ammonia removal tower 6 via a third steam pipe 12. A small amount of gas phase (mainly steam) that is not completely absorbed flows back into the stripping ammonia removal tower 6 to participate in the stripping process again, which reduces tail gas emissions and realizes the recycling of steam.

[0049] The ammonia absorption tower 9 has an acid inlet at its upper part, connected to a first acid pipe 13. The first acid pipe 13 is connected to an acid supply device for adding sulfuric acid solution into the absorption tower. The sulfuric acid reacts with ammonia to produce ammonium sulfate. The acid supply device includes a sulfuric acid tank 46. One end of the first acid pipe 13 is connected to the sulfuric acid tank 46, and the other end is connected to the acid inlet at the upper part of the ammonia absorption tower 9. A tap water pipe 47 is connected to the sulfuric acid tank 46. One end of the tap water pipe 47 is a tap water inlet, and the other end is connected to the sulfuric acid tank 46 for replenishing the dilution water in the sulfuric acid tank 46. This dilutes the concentrated sulfuric acid to a suitable concentration before addition, preventing high-concentration sulfuric acid from corroding the pipes and equipment. The first acid pipeline 13 is equipped with an eighth shut-off valve 48, a sulfuric acid dosing pump 49, a fourth check valve 50, a ninth shut-off valve 51, and a second flow meter 52, which are installed sequentially along the flow direction of the acid. The eighth shut-off valve 48 and the ninth shut-off valve 51 are used to control the opening and closing of the first acid pipeline; the sulfuric acid dosing pump 49 realizes the accurate metering and dosing of acid; the fourth check valve 50 prevents ammonia-containing gas from flowing back into the acid pipeline; and the second flow meter 52 is used to monitor the acid dosing flow rate in real time.

[0050] The ammonia absorption tower 9 has an absorbent outlet at its bottom, which is connected to the inlet of the sulfuric acid circulation pump 15 via a second acid pipe 14. The outlet of the sulfuric acid circulation pump 15 is connected to the first acid pipe 13, forming an acid circulation system. The absorbent at the bottom of the absorption tower (containing unreacted sulfuric acid and generated ammonium sulfate) is returned to the top of the absorption tower by the sulfuric acid circulation pump 15 to participate in the absorption reaction again, improving the acid utilization rate and ensuring that ammonia is fully absorbed. Along the flow direction of the acid solution, the second acid solution pipeline 14 is equipped with a tenth shut-off valve 53, a sulfuric acid circulation pump 15, a fifth check valve 54, an eleventh shut-off valve 55, a twelfth shut-off valve 56, and a second pH sensor 57. The tenth shut-off valve 53, the eleventh shut-off valve 55, and the twelfth shut-off valve 56 are used to control the opening and closing of the second acid solution pipeline and the switching of the circulation path. The fifth check valve 54 prevents the absorption liquid from flowing back. The second pH sensor 57 monitors the pH value of the circulating absorption liquid in real time and transmits the monitoring signal to the control system. The control system automatically adjusts the dosage of the sulfuric acid dosing pump 49 according to the pH value change. When the pH value is too high (indicating insufficient sulfuric acid), the amount of sulfuric acid added is increased. When the pH value is too low (indicating excessive sulfuric acid), the amount of sulfuric acid added is reduced, thereby achieving precise control of acid addition.

[0051] To achieve ammonium sulfate recovery, an ammonium sulfate recovery pipeline 16 is also installed on the second acid pipeline 14, which connects the eleventh shut-off valve 55 and the twelfth shut-off valve 56. When the concentration of ammonium sulfate in the absorbent reaches the set value, it can be discharged and recovered through the ammonium sulfate recovery pipeline 16. A fourth electric valve 58 and a sixth thermometer 59 are installed sequentially along the flow direction of the ammonium sulfate solution on the ammonium sulfate recovery pipeline 16. The sixth thermometer 59 is used to monitor the temperature of the recovered solution. A second liquid level controller 64 is also installed at the bottom of the ammonia absorption tower 9, which works in conjunction with the fourth electric valve 58. The second liquid level controller 64 monitors the liquid level at the bottom of the absorption tower in real time. When the liquid level is too high and the ammonium sulfate concentration reaches the standard, it automatically controls the fourth electric valve 58 to open, discharging the ammonium sulfate solution and ensuring the stability of the liquid level at the bottom of the tower.

[0052] To comprehensively monitor the operating status of the ammonia absorption tower 9, a seventh thermometer 60 and a second pressure gauge 61 are installed at the top, an eighth thermometer 62 is installed at the top, and a ninth thermometer 63 is installed at the bottom. These are used to monitor the temperature of the tail gas at the top of the tower, the pressure at the top of the tower, the temperature of the absorbent liquid at the top of the tower, and the temperature of the gas phase at the bottom of the tower, respectively, to provide data support for the stable control of the absorption process.

[0053] The pipeline reactor 3 can be equipped with either a static mixer or a dynamic mixing pump. The static mixer uses a special internal structure to cause intense disturbance, separation, and mixing of the alkaline solution and wastewater during the flow process, without the need for additional power. It has a simple structure and is easy to maintain. The dynamic mixing pump achieves efficient mixing of the two through the stirring impeller inside the pump body, with higher mixing intensity. It is suitable for scenarios with high wastewater viscosity or large fluctuations in the amount of alkaline solution added, and can be flexibly selected according to actual treatment needs.

[0054] The automated control functions involved in this device can be realized through a conventional PLC control system. This PLC control system is mainly used to receive signals transmitted by various sensors and control the actions of various actuators according to a preset program. Its core protected object is the device structure of ammonia nitrogen wastewater treatment and the connection relationship of each unit. The PLC control system is only a conventional supporting equipment to cooperate with the operation of the device and is not within the scope of protection of this application. Therefore, the specific structure, working principle and other details of the control system will not be described here.

[0055] Taking high-concentration ammonia nitrogen wastewater from a chemical enterprise as the treatment target, the wastewater has an ammonia nitrogen concentration of 1500-2000 mg / L, a pH value of 6.5-7.5, a water temperature of 20-25℃, and a designed treatment capacity of 5 m³ / h. Based on the high-efficiency ammonia nitrogen wastewater treatment device of this application, the key parameters of each unit are set as follows:

[0056] Wastewater pretreatment unit: Pipeline reactor 3 uses an SK-type static mixer with a treatment capacity of 5-8 m³ / h; the alkaline solution is a 30% sodium hydroxide solution, which is added through alkaline solution metering pump 20 to control the pH value of the wastewater at the outlet of pipeline reactor 3 to 11.0-11.5; the first flow display controller 29 is set to a wastewater flow rate of 5 m³ / h, and the flow rate is automatically adjusted and stabilized through the first electric valve 28.

[0057] Stripping Ammonia Removal Unit: The stripping ammonia removal tower 6 adopts a sieve plate tower structure, with an operating pressure of 0.15 MPa (gauge pressure). The top temperature is controlled at 110-115℃, and the bottom steam temperature is controlled at 130-135℃. Fresh steam (pressure 0.3 MPa, temperature 143℃) is introduced through the first steam pipe 37, and the second flow display controller 39 sets the fresh steam flow rate to 0.8-1.0 t / h, which is automatically adjusted by the third electric valve 38. The first liquid level controller 36 sets the bottom liquid level to 1.5-2.0 m, and the ammonia removal wastewater discharge is automatically controlled by the second electric valve 34.

[0058] Ammonia absorption unit: Ammonia absorption tower 9 adopts a packed tower structure, and the packing is polypropylene stepped rings; the mass concentration of sulfuric acid solution in sulfuric acid tank 46 is controlled at 30%, and it is added through sulfuric acid dosing pump 49; the second pH sensor 57 sets the pH value of the circulating absorption liquid to 4.0-4.5, and the pH is maintained by automatically adjusting the amount of sulfuric acid added; the ammonium sulfate recovery is set at a concentration of 40%, and when the concentration of the absorption liquid reaches the set value and the liquid level at the bottom of the tower is higher than 2.0m, the fourth electric valve 58 automatically opens to discharge and recover the liquid.

[0059] Inlet and outlet heat exchanger 5: Shell and tube heat exchanger with a heat exchange area of ​​20m². 2 This ensures that the temperature of the wastewater to be treated is raised to 80-85℃ after heat exchange, and the temperature of the ammonia removal wastewater is reduced to 40-45℃ after heat exchange.

[0060] The operation process of the high-efficiency ammonia nitrogen wastewater treatment device in this embodiment is as follows:

[0061] 1. Wastewater Pretreatment: High-concentration ammonia nitrogen wastewater from the chemical plant first enters the ammonia nitrogen wastewater equalization tank 1. Then, under the action of the ammonia nitrogen wastewater pump 4, it flows through the third shut-off valve 24, the second check valve 25, and the fourth shut-off valve 26 into the first wastewater pipeline 2. The first flow display controller 29 monitors the wastewater flow rate in real time. When it deviates from the set value of 5 m³ / h, it automatically adjusts the opening of the first electric valve 28 to stabilize the flow rate. Simultaneously, the 30% sodium hydroxide solution in the alkali tank 17 enters the pipeline reactor 3 through the first shut-off valve 19, the alkali metering pump 20, the first check valve 21, the second shut-off valve 22, and the first flow meter 23, mixing with the wastewater. The first pH sensor 27 monitors the pH value of the mixed wastewater in real time. The control system automatically adjusts the dosage of the alkali metering pump 20 based on the monitored value to ensure the pH value remains stable between 11.0 and 11.5. The wastewater mixed in the pipeline reactor 3 enters the shell side of the inlet and outlet heat exchanger 5, where it exchanges heat with the high-temperature deammoniation wastewater flowing in the tube side. After the temperature is raised to 80-85℃, it enters the stripping deammoniation tower 6.

[0062] 2. Ammonia Stripping: Pretreated high-temperature alkaline wastewater enters the stripping ammonia removal tower 6 from the upper wastewater inlet, flowing downwards. Simultaneously, two portions of steam enter the tower: one portion is fresh external steam entering the lower steam inlet via the first steam pipe 37, the third electric valve 38, and the second flow display controller 39; the other portion is steam refluxed from the ammonia absorption tower 9 entering the lower steam inlet via the third steam pipe 12. The steam flows upwards, fully contacting the wastewater on the screen plates inside the tower, and carrying free ammonia from the wastewater into the gas phase through gas-liquid mass transfer. The ammonia-containing gas phase at the top of the tower enters the ammonia absorption tower 9 via the second steam pipeline 10 under the action of the steam circulation pump 11. The ammonia removal wastewater at the bottom of the tower enters the second wastewater pipeline 7 via the ammonia removal wastewater outlet, and flows through the fifth shut-off valve 31, the third check valve 32, and the sixth shut-off valve 33 under the action of the ammonia removal water pump 8, entering the tube side of the inlet and outlet heat exchanger 5. After heat exchange with the shell side wastewater, the temperature drops to 40-45℃, and it is discharged through the second electric valve 34 and the second thermometer 35, entering the subsequent deep treatment or standard discharge system. The first liquid level controller 36 monitors the liquid level at the bottom of the tower in real time and automatically adjusts the opening of the second electric valve 34 to ensure that the liquid level is stable at 1.5-2.0m.

[0063] 3. Ammonia Absorption and Resource Recovery: The ammonia-containing gas phase enters the ammonia absorption tower 9 from the bottom and flows upwards. The 30% sulfuric acid solution in the sulfuric acid tank 46 enters the upper part of the absorption tower through the eighth shut-off valve 48, sulfuric acid dosing pump 49, fourth check valve 50, ninth shut-off valve 51, and second flow meter 52, and is sprayed from top to bottom, reacting with the ammonia-containing gas phase in a counter-current manner to generate ammonium sulfate. The absorbent liquid at the bottom of the absorption tower flows back to the first acid liquid pipeline 13 through the second acid liquid pipeline 14 under the action of the sulfuric acid circulation pump 15, via the tenth shut-off valve 53, fifth check valve 54, eleventh shut-off valve 55, and twelfth shut-off valve 56, and re-enters the absorption tower to participate in the reaction, forming a circulating absorption system. The second pH sensor 57 monitors the pH value of the circulating absorbent liquid in real time, and the control system automatically adjusts the dosage of the sulfuric acid dosing pump 49 according to the monitoring value to ensure that the pH value is stable at 4.0-4.5. When the concentration of ammonium sulfate in the absorbent reaches 40% and the second level controller 64 detects that the bottom level of the tower is higher than 2.0m, the fourth electric valve 58 automatically opens, and the ammonium sulfate solution is discharged and recovered through the ammonium sulfate recovery pipeline 16 and the sixth thermometer 59; the small amount of steam that is not completely absorbed flows back from the tail gas outlet at the top of the absorbent tower to the stripping deammoniation tower 6 through the third steam pipeline 12 for reuse.

[0064] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-efficiency ammonia nitrogen wastewater treatment device, characterized in that: It includes a wastewater pretreatment unit, a stripping and ammonia removal unit, and an ammonia absorption unit connected in sequence; The wastewater pretreatment unit includes an ammonia nitrogen wastewater equalization tank (1), a first wastewater pipeline (2), an alkali addition device, and a pipeline reactor (3); the ammonia nitrogen wastewater equalization tank (1) is connected to the stripping and ammonia removal unit through the first wastewater pipeline (2), and the first wastewater pipeline (2) is equipped with an ammonia nitrogen wastewater pump (4), a pipeline reactor (3), and inlet and outlet heat exchangers (5) in sequence along the water flow direction; the outlet end of the alkali addition device is connected to the pipeline reactor (3). The stripping ammonia removal unit includes a stripping ammonia removal tower (6); the upper part of the stripping ammonia removal tower (6) is provided with a wastewater inlet, which is connected to the first wastewater pipe (2); the lower part of the stripping ammonia removal tower (6) is provided with a steam inlet, and the bottom of the stripping ammonia removal tower (6) is provided with an ammonia removal wastewater outlet; the ammonia removal wastewater outlet is discharged through a second wastewater pipe (7), and the second wastewater pipe (7) is provided with an ammonia removal water pump (8) and an inlet and outlet heat exchanger (5); The ammonia absorption unit includes an ammonia absorption tower (9); the top gas phase outlet of the stripping ammonia removal tower (6) is connected to the lower part of the ammonia absorption tower (9) through a second steam pipe (10), and a steam circulation pump (11) is provided on the second steam pipe (10); the top of the ammonia absorption tower (9) is provided with a tail gas outlet, and is connected to the steam inlet at the lower part of the stripping ammonia removal tower (6) through a third steam pipe (12); The ammonia absorption tower (9) is provided with an acid inlet at the top, which is connected to a first acid pipe (13). The first acid pipe (13) is connected to an acid supply device. The ammonia absorption tower (9) is provided with an absorbent outlet at the bottom, which is connected to the inlet of a sulfuric acid circulation pump (15) through a second acid pipe (14). The outlet of the sulfuric acid circulation pump (15) is connected to the first acid pipe (13), and an ammonium sulfate recovery pipe (16) is also provided on the second acid pipe (14).

2. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: The alkali addition device includes an alkali tank (17) and an alkali pipeline (18). One end of the alkali pipeline (18) is connected to the alkali tank (17), and the other end is connected to the inlet of the pipeline reactor (3). A first shut-off valve (19), an alkali metering pump (20), a first check valve (21), a second shut-off valve (22), and a first flow meter (23) are installed sequentially on the alkali pipeline (18) along the flow direction of the alkali.

3. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 2, characterized in that: The first wastewater pipeline (2) is provided with a third shut-off valve (24), an ammonia nitrogen wastewater pump (4), a second check valve (25), a fourth shut-off valve (26), a pipeline reactor (3), a first pH sensor (27), a first electric valve (28), a first flow display controller (29), an inlet and outlet heat exchanger (5), and a first thermometer (30) in sequence along the water flow direction. The first electric valve (28) and the first flow display controller (29) are used together, and the first pH sensor (27) is used together with the alkaline metering pump (20).

4. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 3, characterized in that: The second wastewater pipeline (7) is provided with a fifth shut-off valve (31), an ammonia removal pump (8), a third check valve (32), a sixth shut-off valve (33), a second electric valve (34), an inlet and outlet heat exchanger (5), and a second thermometer (35) in sequence along the water flow direction. The bottom of the stripping ammonia removal tower (6) is equipped with a first liquid level controller (36), which is used in conjunction with a second electric valve (34).

5. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 4, characterized in that: The inlet and outlet heat exchanger (5) is a shell and tube heat exchanger. The first wastewater pipe (2) passes through the shell side of the inlet and outlet heat exchanger (5), and the second wastewater pipe (7) passes through the tube side of the inlet and outlet heat exchanger (5) to realize the heat exchange between the ammonia nitrogen wastewater to be treated and the wastewater after ammonia removal.

6. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: The steam inlet at the bottom of the stripping ammonia removal tower (6) is also connected to a first steam pipe (37) for introducing fresh external steam. A third electric valve (38) and a second flow display controller (39) are sequentially installed on the first steam pipe (37) along the steam flow direction. The third electric valve (38) and the second flow display controller (39) are used in conjunction. The lower part of the stripping ammonia removal tower (6) is also connected to a vent pipe (40), and a seventh shut-off valve (41) is installed on the vent pipe (40). The top of the stripping ammonia removal tower (6) is equipped with a third thermometer (42) and a first pressure gauge (43), the upper part is equipped with a fourth thermometer (44), and the lower part is equipped with a fifth thermometer (45).

7. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: The acid supply device includes a sulfuric acid tank (46), one end of the first acid pipe (13) is connected to the sulfuric acid tank (46), and the other end is connected to the acid inlet at the top of the ammonia absorption tower (9). A tap water pipe (47) is connected to the sulfuric acid tank (46), one end of the tap water pipe (47) is a tap water inlet, and the other end is connected to the sulfuric acid tank (46) to replenish the dilution water of the sulfuric acid tank (46). The first acid pipeline (13) is sequentially equipped with the eighth shut-off valve (48), the sulfuric acid dosing pump (49), the fourth check valve (50), the ninth shut-off valve (51), and the second flow meter (52) along the flow direction of the acid. The second acid pipeline (14) is equipped with a tenth shut-off valve (53), a sulfuric acid circulation pump (15), a fifth check valve (54), an eleventh shut-off valve (55), a twelfth shut-off valve (56), and a second pH sensor (57) in sequence along the flow direction of the acid. The second pH sensor (57) is used in conjunction with the sulfuric acid dosing pump (49).

8. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 7, characterized in that: The ammonium sulfate recovery pipeline (16) is connected between the eleventh shut-off valve (55) and the twelfth shut-off valve (56), and the fourth electric valve (58) and the sixth thermometer (59) are installed sequentially on the ammonium sulfate recovery pipeline (16) along the flow direction of the ammonium sulfate solution.

9. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 8, characterized in that: The ammonia absorption tower (9) is equipped with a seventh thermometer (60) and a second pressure gauge (61) at the top, an eighth thermometer (62) at the top, and a ninth thermometer (63) at the bottom. The bottom of the ammonia absorption tower (9) is also equipped with a second liquid level controller (64), which is used in conjunction with the fourth electric valve (58).

10. The high-efficiency ammonia nitrogen wastewater treatment device according to claim 1, characterized in that: The pipeline reactor (3) is a static mixer or a dynamic mixing pump used to mix the alkali solution from the alkali solution addition device with the ammonia-containing wastewater from the first wastewater pipeline (2).

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