An ammonia-nitrogen treatment system and method for oilfield sour produced water

Abstract

The present application belongs to the technical field of oil and gas field produced water treatment, and particularly relates to an ammonia nitrogen treatment system and method for oil field sulfur-containing produced water. The method comprises the following steps: sending the oil field sulfur-containing produced water into a first buffer pool, reducing sulfides through two-stage aeration of a cyclone aerator and an aeration nozzle device, overflowing from the first buffer pool to a second buffer pool when the first buffer pool reaches a water outlet height, and removing ammonia nitrogen by adding an ammonia nitrogen remover through a conventional dosing port of a dosing device. The present application fully utilizes the characteristics of aeration sulfur removal, and through the addition of a targeted chemical agent and the control of key parameters, purifies and softens the oil field sulfur-containing produced water in one step. After treatment, the water quality only needs to be further filtered by two stages of fine filtration, and the outlet water quality directly meets the steam boiler feed water requirements.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field produced water treatment technology, specifically relating to an ammonia nitrogen treatment system and method for sulfur-containing produced water in oil fields. Background Technology

[0002] Oilfield produced water typically contains high concentrations of ammonia nitrogen, primarily due to the use of nitrogen-containing chemical additives during oilfield extraction and naturally occurring nitrogenous substances in formation water. Removing ammonia nitrogen from oilfield produced water is crucial for environmental protection and meeting emission standards. Treating ammonia nitrogen in produced water from sulfur-containing oilfields is a complex process, requiring the simultaneous treatment of both ammonia nitrogen and sulfides. The following are some methods for treating ammonia nitrogen in produced water from sulfur-containing oilfields:

[0003] I. Pretreatment (sulfide treatment methods)

[0004] Before treating ammonia nitrogen, pretreatment is usually required to remove sulfides and prevent them from having an adverse effect on subsequent treatment processes.

[0005] Air extraction: Hydrogen sulfide is released from water by reducing pressure or blowing in air.

[0006] Oxidation method: Using oxidizing agents (such as hydrogen peroxide, oxygen or ozone) to oxidize sulfides into harmless sulfates.

[0007] Biological pretreatment: Sulfate-reducing bacteria (SRB) are used to reduce sulfides to hydrogen sulfide, which is then removed by air stripping.

[0008] II. Ammonia Nitrogen Treatment Methods

[0009] Biological treatment

[0010] 1) Biological nitrification-denitrification:

[0011] During nitrification, ammonia nitrogen is oxidized to nitrate, requiring sufficient dissolved oxygen and a suitable pH level. During denitrification, nitrate is reduced to nitrogen gas, a process that requires an electron donor (such as an organic carbon source). It is important to note that sulfides can inhibit the activity of nitrifying bacteria, therefore pretreatment is necessary to remove sulfides.

[0012] 2) Sulfate Reduction-Nitrification (SRB-NR) Process:

[0013] Sulfate-reducing bacteria (SRB) are used to reduce sulfate to hydrogen sulfide, which is then removed by stripping or other methods. Nitrification is then performed to remove ammonia nitrogen.

[0014] Chemical treatment

[0015] 1) Chemical precipitation method:

[0016] Ammonia nitrogen is removed by adding chemical reagents (such as aluminum sulfate or ferric hydroxide) to form a precipitate. Subsequent solid-liquid separation steps are required.

[0017] 2) Breakpoint chlorination method:

[0018] Adding chlorine oxidizes ammonia nitrogen into nitrogen gas. Precise control of the chlorine dosage is necessary to avoid the formation of harmful chlorination byproducts.

[0019] Physical treatment method

[0020] 1) Air-blowing method:

[0021] Ammonia is released from the water by lowering the pH, and then removed by a stripping tower. This method is suitable for wastewater with high concentrations of ammonia nitrogen.

[0022] When choosing a treatment method, the following factors need to be considered:

[0023] 1. Concentrations of ammonia nitrogen and sulfides: High concentrations of pollutants may require more complex treatment processes.

[0024] 2. Water quality characteristics: including pH value, temperature, salinity, suspended solids, oil and other contaminants.

[0025] 3. Processing costs: including construction costs, operating costs and maintenance costs.

[0026] 4. Operating conditions: such as whether sufficient oxygen and carbon source can be provided.

[0027] 5. Discharge standards: Ensure that the treated water quality meets local environmental protection requirements.

[0028] Due to the unique characteristics of sulfur-containing wastewater from oil fields, multiple methods are usually required, such as pretreatment to remove sulfides followed by biological or chemical removal of ammonia nitrogen, in order to achieve effective treatment results.

[0029] In summary, researching and developing more adaptable treatment processes and technologies is key to solving the current problem of produced water discharge from oilfields and promoting the green and healthy development of oilfields. While researching the removal of sulfur and ammonia nitrogen from produced water, the inventors discovered that aeration combined with chemical oxidation can rapidly and effectively treat sulfides and ammonia nitrogen in produced water, reducing both indicators to low levels. Based on this, the inventors proposed the concept of an aeration + chemical ammonia nitrogen removal process. Through extensive experimental verification and optimization, a technological breakthrough was ultimately achieved, leading to this invention. Summary of the Invention

[0030] To address the shortcomings of existing technologies, this invention provides an ammonia nitrogen treatment system and method for sulfur-containing produced water from oil fields. This invention fully utilizes the characteristics of aeration desulfurization, achieving purification and softening of sulfur-containing produced water from oil fields in one step through the addition of targeted chemical agents and control of key parameters. The treated water only requires two more stages of fine filtration, and the outlet water quality directly meets the requirements for steam boiler feedwater. This invention features fewer types of chemicals required, stable treated water quality, high automation, and low overall water treatment costs.

[0031] The technical solution provided by this invention is as follows:

[0032] A system for treating ammonia nitrogen in sulfur-containing produced water from an oilfield includes:

[0033] The first and second buffer pools are connected sequentially.

[0034] A swirl aerator is installed at the bottom of the buffer tank, and the swirl aerator is close to the inlet of the buffer tank.

[0035] An aeration nozzle device is installed at the bottom of the middle section of the buffer pool, and the aeration nozzle device is close to the side wall of the buffer pool.

[0036] And a dosing device, the dosing device having a conventional dosing port facing the connecting area between the first-stage buffer tank and the second-stage buffer tank.

[0037] In the above technical solution:

[0038] The first-stage buffer tank is mainly used for the pretreatment of discharged wastewater, namely sulfide treatment. The two-stage aeration method using cyclone aerators and aeration nozzles can thoroughly remove sulfides, laying the groundwork for subsequent ammonia nitrogen removal.

[0039] Under sulfide conditions of 0-10 mg / L, the cyclone aerator performs pre-sulfurization in a buffer tank. This step can remove 95% of the sulfides, and the remaining sulfides can be desulfurized by the aeration nozzles.

[0040] In the case of sulfide concentrations of 10-60 mg / L, water in a buffer tank is lifted to a pipeline mixer. The pipeline mixer is vented by an air tank and aerated by aeration nozzles to remove sulfur. This step can remove sulfides that cannot be removed in the cyclone aerator step, and removes 95% of the sulfides in total.

[0041] The second-stage buffer tank has a conventional dosing point at the inlet, which uses the external drainage flow to mix the chemicals and utilizes the storage space to ensure that the chemicals and water react fully, thereby achieving the effect of removing ammonia nitrogen.

[0042] The inventors discovered that for sulfur-containing produced water from oil fields, aeration using only a cyclone aerator or aeration nozzle alone cannot completely remove high concentrations of sulfides. Only a combination of both can reduce sulfides while simultaneously providing an environment for ammonia nitrogen removal.

[0043] Specifically, the cyclone aerator includes:

[0044] The mounting frame is submerged at the bottom of the aforementioned buffer pool;

[0045] And several swirl aeration units fixedly mounted side by side on the mounting frame.

[0046] Specifically, the mounting frame is a horizontally arranged triangular prism structure, and the horizontal angle of one slope of the triangular prism is 25-35°, preferably 30°.

[0047] Based on the above technical solution, sulfide removal can be ensured. A smaller horizontal angle results in a longer contact time between the air and the water above the aeration point, leading to incomplete aeration by the time it overflows. A larger horizontal angle results in a smaller contact area between the air and water, also causing incomplete aeration.

[0048] Specifically, the swirl aeration units are arranged side by side and at equal intervals along the slope, with the distance between two adjacent swirl aeration units being 40-60cm, preferably 50cm.

[0049] Based on the above technical solution, sulfide removal can be ensured. Too small a spacing will result in an excessive number of aeration nozzles required, leading to poor economic efficiency. Too large a spacing will result in low aeration overlap and incomplete aeration.

[0050] Specifically, the aeration nozzle device includes:

[0051] A fixing frame fixed to the bottom of the buffer pool section;

[0052] And several aeration nozzle units fixedly mounted side by side on the fixed frame.

[0053] Specifically, the horizontal inclination angle of each aeration nozzle unit is 25-35°, preferably 30°.

[0054] Based on the above technical solution, sulfide removal can be ensured. A smaller horizontal angle results in a longer contact time between the air and the water above the aeration point, leading to incomplete aeration by the time it overflows. A larger horizontal angle results in a smaller contact area with the water, also causing incomplete aeration.

[0055] Specifically, the aeration nozzle units are arranged at equal intervals, with a spacing of 30-50cm, preferably 40cm.

[0056] Based on the above technical solution, sulfide removal can be ensured. Too small a spacing will result in an excessive number of aeration nozzles required, leading to poor economic efficiency. Too large a spacing will result in low aeration overlap and incomplete aeration.

[0057] Specifically:

[0058] The ammonia nitrogen treatment system for sulfur-containing produced water in the oilfield also includes a desulfurization skid;

[0059] The desulfurization skid includes an air compressor, a gas tank, a pipeline mixer, and a booster pump;

[0060] The air compressor is connected to the air tank;

[0061] The gas tank is equipped with a main gas pipeline, which is connected to a distribution gas pipeline and a pipeline mixer. The distribution gas pipeline is connected to each swirl aeration unit of the swirl aerator.

[0062] The inlet of the pipeline mixer is connected to the lift pump, and the lift pump is connected to the buffer tank through a lift pipe; the outlet of the pipeline mixer is connected to the aeration nozzle device.

[0063] Based on the above technical solution, a set of air compressor and air tank is used in the desulfurization skid to supply air to the cyclone aerator and aeration nozzle device, which simplifies the equipment and avoids the problem of insufficient air supply.

[0064] Specifically, the dosing device includes a dosing pump, which is connected to a dosing tank and a storage tank, and is also connected to a dosing pipeline. The dosing port of the dosing pipeline faces the connecting area between the first-stage buffer tank and the second-stage buffer tank.

[0065] Specifically, the first-stage buffer pool and the second-stage buffer pool are separated by a partition wall, which is equipped with an overflow outlet, serving as the outlet of the first-stage buffer pool and the inlet of the second-stage buffer pool.

[0066] Specifically, the inlet of the buffer pool and the overflow outlet are located at opposite ends of the pool.

[0067] Specifically, the overflow outlet and the outlet of the two-stage buffer pool are located at opposite ends of the pool.

[0068] Specifically, the outlet of the two-stage buffer pool is equipped with an emergency dosing port.

[0069] Based on the above technical solution, a 15m radius can be installed outside the device. 3 The medicine storage tank has a 1.5m depth inside. 3The system includes a dosing tank with one regular dosing point and one emergency dosing point. The regular dosing point is located at the overflow outlet, and the emergency dosing point is located at the outlet of the second-stage buffer tank. This dosing device allows for the addition of ammonia nitrogen removal agent to achieve the effect of removing ammonia nitrogen.

[0070] Meanwhile, an emergency dosing point is set up at the outlet of the second-stage buffer tank. In special circumstances (such as when the ammonia nitrogen content in the effluent is high), the emergency dosing point can be activated to achieve two-stage dosing, so as to better control the ammonia nitrogen content in the effluent.

[0071] This invention also provides a method for treating ammonia nitrogen in sulfur-containing produced water from oil fields, using the aforementioned ammonia nitrogen treatment system, comprising the following steps:

[0072] Sulfur-containing produced water from the oilfield is sent into the first-stage buffer tank, and after two stages of aeration by the cyclone aerator and the aeration nozzle device, the sulfides are reduced.

[0073] After the first buffer tank reaches the outlet height, it overflows into the second buffer tank;

[0074] Ammonia nitrogen removal agent is added through the conventional dosing port of the dosing device to remove ammonia nitrogen.

[0075] Specifically, the ammonia nitrogen removal agent is a reagent for chemically oxidizing and removing ammonia nitrogen;

[0076] Furthermore, the outlet of the second-stage buffer tank is equipped with an emergency dosing port for adding ammonia nitrogen removal agent.

[0077] The beneficial effects of this invention are as follows:

[0078] 1) This invention can quickly and effectively treat sulfides and ammonia nitrogen in produced water, and can reduce both indicators to a low level.

[0079] 2) Currently, the produced water from heavy oil fields in China with a salinity of ≤7000mg / L can meet the requirements for discharge after being treated by the technical solution provided by this invention, with ammonia nitrogen and sulfide indicators both meeting the requirements. Attached Figure Description

[0080] Figure 1 This is a schematic diagram of the overall structure of the ammonia nitrogen treatment system for sulfur-containing produced water in oil fields provided by the present invention.

[0081] Figure 2 This is a schematic diagram of the swirl aerator section.

[0082] Figure 3 This is a structural diagram of the aeration nozzle device.

[0083] Appendix Figure 1 , 2 In section 3, the structures represented by each label are listed below:

[0084] 1. Primary buffer tank; 2. Secondary buffer tank; 3. Swirl aerator; 31. Swirl aeration unit; 4. Aeration nozzle device; 41. Aeration nozzle unit; 5. Overflow port; 6. Mounting bracket; 7. Fixing bracket; 8. Air compressor; 9. Air tank; 10. Pipeline mixer; 11. Booster pump; 12. Dosing pump; 13. Dosing tank; 14. Storage tank. Detailed Implementation

[0085] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0086] Unless otherwise specified, the test methods used in the embodiments are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0087] Example 1

[0088] like Figure 1 As shown, the ammonia nitrogen treatment system for sulfur-containing produced water in an oilfield includes: a primary buffer tank 1 and a secondary buffer tank 2 connected in sequence; a swirl aerator 3 located at the bottom of the primary buffer tank 1; an aeration nozzle device 4 located at the bottom center of the primary buffer tank 1; and a chemical dosing device. The swirl aerator 3 is located near the inlet of the primary buffer tank 1. The aeration nozzle device 4 is located near the side wall of the primary buffer tank 1. The chemical dosing device has a conventional dosing port facing the connecting area between the primary buffer tank 1 and the secondary buffer tank 2.

[0089] A primary buffer pool 1 and a secondary buffer pool 2 are separated by a partition wall. The partition wall is equipped with an overflow outlet 5, which serves as the outlet of the primary buffer pool 1 and the inlet of the secondary buffer pool 2. The inlet of the primary buffer pool 1 and the overflow outlet 5 are located at opposite ends of the pool. The overflow outlet 5 and the outlet of the secondary buffer pool 2 are also located at opposite ends of the pool.

[0090] Overflow outlet 5 serves as the regular dosing port. The outlet of the second-stage buffer tank 2 serves as the emergency dosing port.

[0091] Based on the above technical solution, the combination of cyclone aerator, aeration nozzle and ammonia nitrogen removal agent can quickly and effectively treat sulfides and ammonia nitrogen in produced water, and can reduce both indicators to a low level.

[0092] Example 2

[0093] Based on Example 1, such as Figure 2 The system shown is equipped with a desulfurization skid. The desulfurization skid includes an air compressor 8, an air tank 9, a pipeline mixer 10, and a booster pump 11.

[0094] Air compressor 8 is connected to air tank 9. Air tank 9 is equipped with a main air pipeline, which is connected to the distribution air pipeline and the pipeline mixer 10. The distribution air pipeline is connected to each swirl aeration unit 31 of the swirl aerator 3. The inlet of the pipeline mixer 10 is connected to the lift pump 11, which is connected to a buffer tank 1 via a lift pipe. The outlet of the pipeline mixer 10 is connected to the aeration nozzle device 4.

[0095] The desulfurization skid can be equipped with a dosing pump 12 and a dosing tank 13. The dosing pump 12 is connected to the dosing tank 13 and the storage tank 14, respectively. The dosing pump 12 is also connected to a dosing pipeline, the dosing port of which faces the connecting area between the first-stage buffer tank 1 and the second-stage buffer tank 2. In addition, the system can have an external storage tank 14.

[0096] Example 3

[0097] Based on Example 2, such as Figure 3 As shown, the swirl aerator 3 includes: a mounting frame 6 submerged at the bottom of a buffer tank 1; and 4-6 swirl aeration units 31 fixedly mounted side-by-side on the mounting frame 6. The aeration nozzle device 4 includes: a fixing frame 7 fixed at the bottom of a buffer tank 1; and 6-10 aeration nozzle units 41 fixedly mounted side-by-side on the fixing frame 7. The swirl aerator can be installed and fixed using lifting lugs.

[0098] Example 4

[0099] Based on Example 3:

[0100] The mounting frame 6 is a horizontally arranged triangular prism structure with a horizontal angle of 30° on one slope of the triangular prism and a distance of 50cm between two adjacent swirl aeration units 31.

[0101] The horizontal inclination angle of each aeration nozzle unit 41 is 30°. Each aeration nozzle unit 41 is equally spaced, with a spacing of 40cm.

[0102] Based on this technical solution, it has the best removal efficiency and the best economic benefits.

[0103] In one specific implementation, sulfur-containing produced water from the oilfield is fed into a primary buffer tank 1, where it undergoes two stages of aeration via a cyclone aerator 3 and an aeration nozzle device 4 to reduce sulfides. After reaching the effluent height in the primary buffer tank 1, the water overflows into a secondary buffer tank 2. Ammonia nitrogen removal agent is then added through the conventional dosing port of the dosing device to remove ammonia nitrogen.

[0104] Example of effect 1

[0105] The ammonia nitrogen treatment system for sulfur-containing produced water from oilfields described in Example 4 was used to treat sulfides and ammonia nitrogen.

[0106] The discharge pond of a heavy oil processing station in Xinjiang Oilfield has the following water quality indicators: mineralization 6265 mg / L, total hardness 483 mg / L, total alkalinity 392 mg / L, pH value 7.16, ammonia nitrogen 7.8 mg / L, and sulfide 5 mg / L. Among these indicators, ammonia nitrogen and sulfide do not meet the requirements for external discharge.

[0107] The inlet flow velocity of buffer pool 1 is 400 m / s. 3 / h.

[0108] The gas in the gas tank is air. There are 5 swirl aeration units 31, and the flow rate of the swirl aerator 3 is 0.9 cubic meters per hour. There are 8 aeration nozzle units 41, and the flow rate of the aeration nozzle device 4 is 11 cubic meters per hour.

[0109] The ammonia nitrogen removal agent added to the conventional dosing port is sodium hypochlorite, at a dosage of 1000 mg / L.

[0110] The pH value of the effluent measured at outlet 2 of the second-stage buffer tank was 7.09, ammonia nitrogen was 0.86 mg / L, and sulfide was 0 mg / L. All indicators met the requirements for external discharge and the effluent was directly discharged into the evaporation tank.

[0111] Comparative Example 1

[0112] Refer to Example 1 for the effect, the difference is that: the swirl aerator 3 was stopped, and the pH value of the water measured at the outlet of the second-stage buffer tank 2 was 7.09, ammonia nitrogen was 0.86 mg / L, and sulfide was 0 mg / L.

[0113] Comparative Example 2

[0114] Refer to Example 1 for the effect, the difference is that: when the aeration nozzle device 4 is stopped, the pH value of the water measured at the outlet of the second-stage buffer tank 2 is 7.09, ammonia nitrogen is 0.86 mg / L, and sulfide is 0 mg / L.

[0115] Comparative Example 3

[0116] Referring to Example 1, the difference is that the horizontal angle of the swirl aeration unit 31 is changed to 40°, and the pH value of the water measured at the outlet of the second-stage buffer tank 2 is 7.11, ammonia nitrogen is 3.5 mg / L, and sulfide is 0.5 mg / L.

[0117] Comparative Example 4

[0118] Referring to Example 1, the difference is that the horizontal angle of the swirl aeration unit 31 is changed to 20°, and the pH value of the water measured at the outlet of the second-stage buffer tank is 7.09, ammonia nitrogen is 2.4 mg / L, and sulfide is 1 mg / L.

[0119] Comparative Example 5

[0120] Referring to Example 1, the difference is that the spacing of the swirl aeration unit 31 is changed to 40cm. At the outlet of the second-stage buffer tank 2, the water pH value is 7.09, ammonia nitrogen is 0.84mg / L, and sulfide is 0mg / L.

[0121] Comparative Example 6

[0122] Referring to Example 1, the difference is that the spacing of the swirl aeration unit 31 is changed to 60cm, and the pH value of the water measured at the outlet of the second-stage buffer tank 2 is 7.12, ammonia nitrogen is 3.2mg / L, and sulfide is 0.6mg / L.

[0123] Comparative Example 7

[0124] Referring to Example 1, the difference is that the horizontal angle of the aeration nozzle unit 41 is changed to 40°, and the pH value, ammonia nitrogen, and sulfide are measured at the outlet of the second-stage buffer tank 2 as 7.15, 3.8 mg / L, and 1.2 mg / L.

[0125] Comparative Example 8

[0126] Referring to Example 1, the difference is that the horizontal angle of the aeration nozzle unit 41 is changed to 20°, and the pH value of the water measured at the outlet of the second-stage buffer tank is 7.06, ammonia nitrogen is 2.2 mg / L, and sulfide is 1.1 mg / L.

[0127] Comparative Example 9

[0128] Referring to Example 1, the difference is that the spacing of the aeration nozzle unit 41 is changed to 30cm. The pH value of the water measured at the outlet of the second-stage buffer tank 2 is 7.08, ammonia nitrogen is 0.82mg / L, and sulfide is 0mg / L.

[0129] Comparative Example 10

[0130] Referring to Example 1, the difference is that the spacing of the aeration nozzle unit 41 is changed to 50cm, and the pH value of the water measured at the outlet of the second-stage buffer tank 2 is 7.1, ammonia nitrogen is 2.8mg / L, and sulfide is 0.7mg / L.

[0131] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ammonia nitrogen treatment system for sulfur-containing produced water from oil fields, characterized in that, include: The first buffer pool (1) and the second buffer pool (2) are connected in sequence; A swirl aerator (3) is installed at the bottom of the buffer tank (1) and the swirl aerator (3) is close to the inlet of the buffer tank (1). An aeration nozzle device (4) is installed at the bottom of the middle section of the buffer pool (1), and the aeration nozzle device (4) is close to the side wall of the buffer pool (1). And a dosing device, the dosing device having a conventional dosing port facing the connecting area of ​​the first-stage buffer pool (1) and the second-stage buffer pool (2).

2. The ammonia nitrogen treatment system for sulfur-containing produced water in oilfields according to claim 1, characterized in that, The swirl aerator (3) includes: The mounting frame (6) is submerged at the bottom of the buffer pool (1); And several swirl aeration units (31) are fixedly mounted side by side on the mounting frame (6).

3. The ammonia nitrogen treatment system for sulfur-containing produced water in oilfields according to claim 2, characterized in that: The mounting bracket (6) is a horizontally arranged triangular prism structure, and the horizontal angle of one slope of the triangular prism is 25-35°; The swirl aeration units (31) are arranged side by side and at equal intervals along the slope, with a spacing of 40-60cm between two adjacent swirl aeration units (31).

4. The ammonia nitrogen treatment system for sulfur-containing produced water in oilfields according to claim 1, characterized in that, The aeration nozzle device (4) includes: The fixing frame (7) is fixed at the bottom of the buffer pool (1); And several aeration nozzle units (41) are fixedly mounted side by side on the fixed frame (7).

5. The ammonia nitrogen treatment system for sulfur-containing produced water in oilfields according to claim 4, characterized in that: The horizontal inclination angle of each of the aeration nozzle units (41) is 25-35°; Each of the aeration nozzle units (41) is arranged at equal intervals, with a spacing of 30-50cm.

6. The ammonia nitrogen treatment system for sulfur-containing produced water in oilfields according to claim 1, characterized in that: The ammonia nitrogen treatment system for sulfur-containing produced water in the oilfield also includes a desulfurization skid; The desulfurization skid includes an air compressor (8), an air tank (9), a pipeline mixer (10), and a booster pump (11); The air compressor (8) is connected to the air tank (9); The gas tank (9) is equipped with a main gas pipeline, which is connected to the gas distribution pipeline and the pipeline mixer (10) respectively. The gas distribution pipeline is connected to each swirl aeration unit (31) of the swirl aerator (3) respectively. The inlet of the pipe mixer (10) is connected to the lift pump (11), and the lift pump (11) is connected to the buffer tank (1) through the lift pipe; the outlet of the pipe mixer (10) is connected to the aeration nozzle device (4).

7. The ammonia nitrogen treatment system for sulfur-containing produced water in oilfields according to claim 1, characterized in that: The dosing device includes a dosing pump (12), which is connected to a dosing tank (13) and a storage tank (14) respectively. The dosing pump (12) is also connected to a dosing pipeline, and the dosing port of the dosing pipeline faces the connecting area of ​​the first-stage buffer pool (1) and the second-stage buffer pool (2).

8. The ammonia nitrogen treatment system for sulfur-containing produced water from oilfields according to any one of claims 1 to 7, characterized in that: The first-stage buffer pool (1) and the second-stage buffer pool (2) are separated by a partition wall. The partition wall is provided with an overflow port (5), which serves as the outlet of the first-stage buffer pool (1) and the inlet of the second-stage buffer pool (2). The inlet of the buffer pool (1) and the overflow outlet (5) are located at opposite ends of the pool. The overflow outlet (5) and the outlet of the two-stage buffer pool (2) are located at opposite ends of the pool, respectively. The outlet of the two-stage buffer pool (2) is equipped with an emergency dosing port.

9. A method for treating ammonia nitrogen in sulfur-containing produced water from an oilfield, comprising using the ammonia nitrogen treatment system described in any one of claims 1 to 8, characterized in that, Includes the following steps: Sulfur-containing produced water from the oilfield is sent into the first-stage buffer tank (1), and after two stages of aeration by the cyclone aerator (3) and the aeration nozzle device (4), the sulfides are reduced. After the first-stage buffer pool (1) reaches the outlet height, it overflows into the second-stage buffer pool (2); Ammonia nitrogen removal agent is added through the conventional dosing port of the dosing device to remove ammonia nitrogen.

10. The method for treating ammonia nitrogen in sulfur-containing produced water from oilfields according to claim 9, characterized in that: The ammonia nitrogen removal agent is a reagent for chemically oxidizing and removing ammonia nitrogen; The outlet of the two-stage buffer tank (2) is equipped with an emergency dosing port for adding ammonia nitrogen removal agent.

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