Treatment system for FPSO pipeline chemical cleaning waste liquid and application thereof

Abstract

The invention discloses a treatment system for FPSO pipeline chemical cleaning waste liquid and application of the treatment system. The system comprises a nitrous nitrogen reduction and removal device, a chemical precipitation defluorination device, a chemical deep precipitation defluorination device, a stripping ammonia nitrogen removal device, an ammonia gas absorption device, a circulating adsorption defluorination water tank, a first electrolytic circulating water tank and a second electrolytic circulating water tank which are sequentially connected, and the circulating adsorption defluorination water tank is connected with the adsorption defluorination device to synergistically remove fluorine. The first electrolytic circulating water tank is connected with the first electrochemical unit to synergistically degrade COD and ammonia nitrogen, the second electrolytic circulating water tank is connected with the ion exchange nitrate nitrogen removal device to synergistically secondarily degrade COD and ammonia nitrogen, and the ion exchange nitrate nitrogen removal device is connected with the ion resin reclaimed water-second electrochemical treatment unit. Through optimal combination of physical air stripping, chemical reduction, multi-stage precipitation, electrochemical oxidation and ion exchange, collaborative and deep removal of specific pollutants such as high ammonia nitrogen, high fluoride, high organic matters and high nitrogen-containing salts is realized, and the effluent of the system is stable and reaches the standard.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to a treatment system for chemical cleaning wastewater from FPSO pipelines and its application. Background Technology

[0002] During the construction and pre-commissioning phases of FPSO modules, chemical cleaning of the pipelines is required to remove contaminants such as grease, rust, and welding slag. The wastewater generated during the cleaning process has a complex composition, containing high concentrations of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, fluoride ions, organic matter (COD), and heavy metals (such as chromium and nickel). Direct discharge of such wastewater would cause serious environmental pollution and is difficult to treat efficiently using traditional wastewater treatment methods (such as biological methods and chemical flocculation).

[0003] Currently, treating complex wastewater containing multiple pollutants is a major technical challenge in the industry. Traditional single treatment methods or simple process cascading have significant drawbacks: high ammonia nitrogen inhibits biological treatment units, and physicochemical removal methods are costly; fluoride ions easily cause scaling and clogging of equipment and poison advanced oxidation electrode materials; various pollutants interfere with each other during treatment, for example, although high chloride ions can generate active chlorine to oxidize ammonia nitrogen during electrochemical processes, they may also produce harmful byproducts that interfere with COD measurement and degradation efficiency. Existing technologies lack an integrated process system that can comprehensively optimize and achieve efficient synergistic removal and full-process control of multiple pollutants, resulting in unstable treatment effects, high operating costs, and difficulty in meeting the stringent wastewater discharge standard "Integrated Wastewater Discharge Standard (DB12 / 356-2018)". Summary of the Invention

[0004] To overcome the shortcomings of existing technologies where chemical cleaning wastewater from FPSO pipelines cannot meet stringent discharge standards, the main objective of this invention is to provide a process treatment system for chemical cleaning wastewater from FPSO pipelines. This system, through modular functional unit design and optimized combination, solves the problem of synergistic treatment of chemical cleaning wastewater from FPSO pipelines with high ammonia nitrogen, high fluoride, high organic matter, and high nitrogen salt content.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: A process treatment system for chemical cleaning wastewater from FPSO pipelines, the system comprising a reduction denitrification unit 1, a chemical precipitation defluorination unit 2, a chemical deep precipitation defluorination unit 3, a stripping ammonia nitrogen removal unit 4, an ammonia absorption unit 5, a circulating adsorption defluorination tank 6, a first electrolytic circulating water tank 7, and a second electrolytic circulating water tank 8, the above devices being connected sequentially. The circulating adsorption defluorination tank 6 is connected to the adsorption defluorination unit 9, and the defluorination is controlled in a coordinated manner. The first electrolytic circulating water tank 7 is connected to the first electrochemical unit 10, and the degradation of COD and ammonia nitrogen is controlled in a coordinated manner. The second electrolytic circulating water tank 8 is connected to the ion exchange denitrification unit 11, and the secondary degradation of COD and ammonia nitrogen is controlled in a coordinated manner. The ion exchange denitrification unit 11 is connected to the ion exchange resin regenerated water-second electrochemical treatment unit 12. The second electrolytic circulating water tank 8 and the ion exchange resin regenerated water-second electrochemical treatment unit 12 are respectively provided with outlets.

[0006] The reducing agent used in the reduction and removal of nitrite in the device 1 is aminosulfonic acid, ferrous salt, sodium thiosulfate, or zero-valent iron material modified by one or more elements of sulfur, copper, boron, and nickel.

[0007] The calcium agent used in the chemical precipitation defluorination device 2 is a complex calcium salt composed of one or more of calcium chloride, calcium oxide, calcium hydroxide, calcium carbonate, and calcium nitrate.

[0008] The phosphorus agent added to the chemical deep precipitation defluorination device 3 is sodium dihydrogen phosphate.

[0009] The ammonia stripping device 4 uses a blower with a blowing speed of 100 ml / min, and the ammonia absorption device 5 contains a 1 mol / L dilute sulfuric acid solution.

[0010] The adsorption and defluorination device 6 is filled with any one of the following: activated alumina, hydroxyapatite, modified activated carbon supported on aluminum or lanthanum, or anion exchange resin alumina or ion exchange resin particles that selectively adsorb fluoride ions.

[0011] The first electrolytic circulating water tank 7 and the second electrolytic circulating water tank 8 are each an electrochemical system, each including a stainless steel anode and a stainless steel cathode, with a system current density of 50 mA / cm2 and an electrode-to-water ratio of 100 L / m2. The first electrochemical unit 10 and the ion-exchange resin regenerated water-second electrochemical unit 12 are each an electrochemical system, each including a size-stable anode and a stainless steel cathode, with a system current density of 30 mA / cm2 and an electrode-to-water ratio of 100 L / m2.

[0012] The adsorption and defluorination device 9 is filled with any one of the following: activated alumina, hydroxyapatite, modified activated carbon supported on aluminum or lanthanum, or anion exchange resin alumina or ion exchange resin particles that have selective adsorption function for fluoride ions.

[0013] The ion exchange denitrification device 11 is filled with anion exchange resin that has high selectivity for nitrate.

[0014] The process system is used in the treatment of chemical cleaning wastewater from FPSO pipelines.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves synergistic and deep removal of characteristic pollutants such as high ammonia nitrogen, high fluoride, high organic matter, and high nitrogen salts through an optimized combination of "physical stripping-chemical reduction-multi-stage precipitation-electrochemical oxidation-ion exchange," resulting in stable effluent compliance. The three-stage defluorination process balances effectiveness with reagent costs; electrochemical technology simultaneously degrades organic matter and ammonia nitrogen, reducing the need for external oxidant addition; and ion exchange provides precise and deep denitrification, with overall operating costs significantly lower than traditional treatment methods. Effective absorption of stripped ammonia and proper disposal of generated chemical sludge and saturated adsorbents minimize the risk of secondary environmental pollution. Attached Figure Description

[0016] Figure 1 : Process flow diagram of the system of this invention; Figure 1 The structures represented by the reference numerals in the attached figures are as follows: 1. Reduction denitrification unit; 2. Chemical precipitation defluorination unit; 3. Deep chemical precipitation defluorination unit; 4. Ammonia stripping unit; 5. Ammonia absorption unit; 6. Circulating adsorption defluorination tank; 7. First electrolysis circulating water tank; 8. Second electrolysis circulating water tank; 9. Adsorption defluorination unit; 10. First electrochemical unit; 11. Ion exchange denitrification unit; 12. Ion exchange resin regeneration water - second electrochemical unit; Figure 2 Example 2 of this invention: Changes in COD and ammonia nitrogen over time after electrochemical oxidation treatment; Figure 3 Example 3 of this invention: Changes in COD and ammonia nitrogen over time after electrochemical oxidation treatment; Figure 4 Example 4 of this invention: Changes in COD and ammonia nitrogen over time after electrochemical oxidation treatment. Detailed Implementation

[0017] The embodiments described below are exemplary descriptions of key experimental evidence and are not intended to limit the core content and application scope of this invention due to the amount of evidence. It should be noted that all the accompanying drawings and corresponding descriptions merely illustrate the concept, principles, and representative experimental evidence of the disclosed embodiments of this invention. Where the chain of evidence is complete, it is unnecessary to show all the specific details and extended details of the various embodiments listed in this invention.

[0018] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which this invention pertains.

[0019] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] Example 1 A process treatment system for chemical cleaning wastewater from FPSO pipelines, the process flow diagram is as follows: Figure 1 As shown, the system includes: a reduction denitrification unit 1, a chemical precipitation defluorination unit 2, a chemical deep precipitation defluorination unit 3, a stripping ammonia nitrogen removal unit 4, an ammonia absorption unit 5, a circulating adsorption defluorination tank 6, a first electrolysis circulating tank 7, and a second electrolysis circulating tank 8, which are connected sequentially by pipelines. The circulating adsorption defluorination tank 6 is connected to the adsorption defluorination unit 9 by pipelines, and the defluorination is controlled in a coordinated manner. The adsorption defluorination unit 9 is connected to the waste liquid tank by pipelines with valve control switches, so that a small amount of wastewater after defluorination is recycled from the unit 9 to the waste liquid tank to replenish the volume, and then re-adsorbed for defluorination. Wastewater from the combined use of water tank 6 and the adsorption defluorination device 9 flows from the circulating adsorption defluorination water tank 6 into the first electrolytic circulating water tank 7 via a pipeline. The first electrolytic circulating water tank 7 is connected to the first electrochemical unit 10 via a pipeline, and the interconnected systems work together to regulate and degrade COD and ammonia nitrogen. Wastewater from the combined use of the first electrolytic circulating water tank 7 and the first electrochemical unit 10 then flows from the first electrolytic circulating water tank 7 into the second electrolytic circulating water tank 8 via a pipeline. The second electrolytic circulating water tank 8 is connected to the ion exchange denitrification device 11 via a pipeline, and the interconnected systems work together to regulate and degrade COD and ammonia nitrogen again. The second electrolytic circulating water tank 8 has an outlet; water meeting the sewage discharge requirements is discharged directly from the second electrolytic circulating water tank 8. Water not meeting the sewage discharge requirements flows from the ion exchange denitrification device 11 into the ion exchange resin regenerated water-second electrochemical treatment unit 12 via a pipeline. The ion exchange resin regenerated water-second electrochemical treatment unit 12 has an outlet; water meeting the sewage discharge requirements is discharged from the ion exchange resin regenerated water-second electrochemical treatment unit 12.

[0021] The nitrite removal device 1 is used to add a reducing agent. In this embodiment, aminosulfonic acid is selected to preferentially reduce nitrite to nitrogen gas for removal. Aminosulfonic acid, ferrous salt, sodium thiosulfate, or zero-valent iron materials modified by sulfur, copper, boron, nickel or multiple elements are commonly used reducing agents in the field. Any one of them can achieve the same effect.

[0022] The chemical precipitation defluorination device 2 is used to add calcium agents. In this embodiment, a compound calcium agent of calcium oxide and calcium chloride is selected to perform primary defluorination by forming calcium fluoride precipitate. Commonly used calcium agents in this field include one or more compound calcium salts composed of calcium chloride, calcium oxide, calcium hydroxide, calcium carbonate, and calcium nitrate, all of which can achieve the same effect.

[0023] The chemical deep precipitation defluorination device 3 is used to add phosphorus agent. In this embodiment, sodium dihydrogen phosphate is selected to perform secondary enhanced defluorination by generating calcium fluorophosphate precipitate with lower solubility.

[0024] The ammonia stripping unit 4 uses a blower (blowing speed: 100 ml / min) connected to the ammonia absorption unit 5. The ammonia absorption unit 5 contains a 1 mol / L dilute sulfuric acid solution, which is used to convert free ammonia in wastewater into gaseous ammonia under alkaline conditions and then separate and recover it.

[0025] The circulating adsorption defluoridation tank 6 is filled with activated alumina for three-stage deep adsorption and removal of residual fluoride ions. Hydroxyapatite, modified activated carbon supported on aluminum or lanthanum, or anion exchange resin alumina or ion exchange resin particles with selective adsorption function for fluoride ions are conventional chemical fillers with selective adsorption function for fluoride ions in the field, and any one of them can be selected to replace activated alumina.

[0026] The adsorption defluorination unit 9 is filled with activated alumina with a particle size of 1-5 mm for deep defluorination before entering the next electrochemical unit. Additionally, a small amount of the wastewater after defluorination by the adsorption defluorination unit 9 is reused in the waste liquid tank to replenish its volume. Hydroxyapatite, aluminum- or lanthanum-loaded modified activated carbon, or anion exchange resin alumina or ion exchange resin particles with selective fluoride ion adsorption function are conventional chemical fillers with selective fluoride ion adsorption function in the art, and any one of them can be used to replace activated alumina.

[0027] The first electrolysis circulating water tank 7 is an electrochemical system, which includes a stainless steel anode and a stainless steel cathode, and the system current density is 50 mA / cm². 2 The polar water ratio is 100 L / m 2 It is used to degrade organic matter in water and remove residual ammonia nitrogen.

[0028] The first electrochemical unit 10 uses a size-stable anode (DSA) (Ti / RuO2-IrO2) as the anode and stainless steel as the cathode, with a current density of 30 mA / cm². 2 The polar water ratio is 100 L / m 2 It is used for the electrochemical oxidation of wastewater.

[0029] The second electrolysis circulating water tank 8 is the same as the first electrolysis circulating water tank 7, and is used for secondary degradation to remove residual ammonia nitrogen.

[0030] The ion exchange denitrification unit 11 is filled with anion exchange resin (model IRA402) that has high selectivity for nitrate ions, and is used for deep removal of nitrate nitrogen from wastewater.

[0031] Ion exchange resin regenerated water - second electrochemical treatment unit 12 is equipped with a size-stabilized anode (DSA) (Ti / RuO2-IrO2), a stainless steel cathode, and a current density of 30 mA / cm². 2 The polar water ratio is 100 L / m 2 It is used for centralized oxidation treatment of regenerated wastewater generated during the regeneration of ion exchange resins.

[0032] Example 2 The wastewater generated from cleaning agents used in carbon steel pipeline projects is the target for treatment. Its typical water quality is as follows: pH = 10.0, ammonia nitrogen = 8867 mg / L, fluoride ion = 1248 mg / L, COD = 32852 mg / L, nitrite nitrogen = 1708 mg / L, and nitrate nitrogen = 602 mg / L. The treatment process is as follows: (1) The wastewater first enters the reduction nitrite removal unit 1, where 0.5 mol / L aminosulfonic acid (dosage 10 mg / L) is added to preferentially reduce nitrite to nitrogen gas; then it enters the chemical precipitation fluoride removal unit 2, where a compound calcium agent of 0.3 mol / L calcium oxide and 0.3 mol / L calcium chloride (ratio 1:1, dosage 2000 mg / L) is added, and the pH is controlled to 7 ~ 8. After the reaction, precipitation is completed, and the first-stage fluoride removal is completed; the supernatant enters the chemical deep precipitation fluoride removal unit 3, where 0.3 mol / L sodium dihydrogen phosphate (dosage 300 mg / L) is added to generate calcium fluorophosphate precipitate for secondary enhanced fluoride removal; (2) The ammonia nitrogen is removed by air stripping device 4. Sodium hydroxide is added to adjust the pH to above 10.5. Free ammonia is stripped off by air aeration using a blower (air flow rate: 100 ml / min). The gaseous ammonia enters ammonia absorption device 5 and is absorbed by a 1 mol / L dilute sulfuric acid solution to generate ammonium sulfate solution for recovery. This stage can reduce the ammonia nitrogen concentration to below 1000 mg / L.

[0033] (3) Subsequently, the wastewater enters the circulating adsorption defluorination tank 6, which is filled with alumina particles with a particle size of 2-4 mm, and the adsorption defluorination device 9, which is filled with activated alumina with a particle size of 1-5 mm for deep defluorination. After this treatment, the fluoride ion concentration drops from 4452 mg / L to below 1 mg / L, effectively ensuring the lifespan of the downstream electrodes. After defluorination, the wastewater enters the first electrolysis circulating water tank 7. This system includes a stainless steel anode and a stainless steel cathode, and the system current density is 50 mA / cm². 2 The polar water ratio is 100 L / m 2 And a first electrochemical unit 10, the system comprising a size-stabilized DSA (Ti / RuO2-IrO2) as the anode, stainless steel as the cathode, and a controlled current density of 30 mA / cm². 2 The polar water ratio is 100 L / m 2It is used for electrochemical cyclic processing.

[0034] (4) Subsequently, the wastewater flows out from the first electrolytic circulating water tank 7 and enters the second electrolytic circulating water tank 8 and the ion exchange denitrification device 11, where the trace amounts of nitrile nitrogen that may be generated are deeply removed using the selective anion exchange resin IRA402. The small amount of high-salt wastewater generated during resin regeneration enters the ion resin regeneration water-second electrochemical unit 12 for centralized oxidation treatment.

[0035] Specifically, the changes in COD and ammonia nitrogen over time after the system finally passes through the ion exchange resin-regenerated water-second electrochemical unit 12 are as follows: Figure 2 As shown, COD = 469 mg / L and ammonia nitrogen = 23 mg / L, which meets the discharge standards (COD < 500 mg / L; ammonia nitrogen < 70 mg / L) of the Integrated Wastewater Discharge Standard (DB12 / 356-2018).

[0036] Example 3 This embodiment uses wastewater from carbon steel pipelines as the treatment target. Its typical water quality is: pH = 4.0, ammonia nitrogen = 1975 mg / L, nitrite nitrogen = 207 mg / L, nitrate nitrogen = 194 mg / L, fluoride ion = 1903 mg / L, COD = 11767 mg / L. The treatment process is as follows: (1) First, the wastewater enters the reduction and removal unit 1 for nitrite. 10 mg / L of 0.5 mol / L aminosulfonic acid is added to preferentially reduce nitrite to nitrogen gas; (2) Subsequently, 10 mg / L of sulfur-modified micro-nano zero-valent iron material was added, the pH was controlled at around 3.0, and the reaction was carried out for 1.5 hours to efficiently reduce nitrate nitrogen and residual nitrite nitrogen; (3) Subsequently, the solution enters the chemical precipitation defluorination device 2, where a compound calcium agent of 0.3 mol / L calcium oxide and 0.3 mol / L calcium chloride (ratio 1:1, dosage 2000 mg / L) is added, and the pH is controlled to 7-8. After the reaction, precipitation occurs, completing the first-stage defluorination. The supernatant enters the chemical deep precipitation defluorination device 3, where 0.5 mol / L sodium dihydrogen phosphate (dosage 300 mg / L) is added to generate calcium fluorophosphate precipitate for the second-stage enhanced defluorination. (4) Subsequently, the wastewater is subjected to ammonia nitrogen removal device 4, which uses a blower (blowing speed: 100 ml / min), and ammonia absorption device 5, which uses 1 mol / L dilute sulfuric acid to absorb the ammonia nitrogen, thereby reducing part of the ammonia nitrogen load. (5) Subsequently, the wastewater enters the circulating adsorption defluorination tank 6, which is filled with alumina particles with a particle size of 2-4 mm, and the adsorption defluorination device 9, which is filled with activated alumina with a particle size of 1-5 mm for deep defluorination. After this treatment, the fluoride ion concentration is reduced from 1903 mg / L to below 1 mg / L, effectively ensuring the lifespan of the downstream electrodes. After defluorination, the wastewater enters the first electrolysis circulating water tank 7. This system includes a stainless steel anode and a stainless steel cathode, and the system current density is 50 mA / cm². 2 The polar water ratio is 100 L / m 2 And a first electrochemical unit 10, the system comprising a size-stabilized DSA (Ti / RuO2-IrO2) as the anode, stainless steel as the cathode, and a controlled current density of 30 mA / cm². 2 The polar water ratio is 100 L / m 2 It is used for electrochemical cyclic processing.

[0037] (6) Subsequently, the wastewater flows out of the pool 7 and enters the second electrolytic circulating water pool 8 and the ion exchange denitrification device 11, where the trace amounts of nitrification nitrogen that may be generated are deeply removed using the selective anion exchange resin IRA402. The small amount of high-salt wastewater generated during resin regeneration enters the ion resin regeneration water-second electrochemical unit 12 for centralized oxidation treatment to ensure that the total nitrogen index is stably up to standard.

[0038] Specifically, the changes in COD and ammonia nitrogen over time after the system finally passes through the ion exchange resin-regenerated water-second electrochemical unit 12 are as follows: Figure 3 As shown, COD = 96 mg / L and ammonia nitrogen = 8 mg / L, which meets the discharge standards (COD < 500 mg / L; ammonia nitrogen < 70 mg / L) of the Integrated Wastewater Discharge Standard (DB12 / 356-2018).

[0039] Example 4 This embodiment uses highly acidic carbon steel pipeline wastewater as the treatment target. The typical water quality of this wastewater is: pH = 2.4, nitrite nitrogen = 17 mg / L, nitrate nitrogen = 13540 mg / L, fluoride ion = 3921 mg / L, COD = 1284 mg / L, and ammonia nitrogen = 98 mg / L. The treatment process is as follows: (1) This wastewater enters the reduction and nitrite removal unit 1. 0.5 mol / L aminosulfonic acid (dosage 10 mg / L) is added to preferentially reduce nitrite, followed by the addition of 10 mg / L sulfur-modified micro-nano zero-valent iron material. Then, sulfuric acid is used to adjust the pH to 3.0 for deep reduction of nitrite. Finally, the wastewater passes through the chemical precipitation and defluorination unit 2, where a compound calcium agent of 0.3 mol / L calcium oxide and 0.3 mol / L calcium chloride (ratio 1:1, dosage 2000 mg / L) is added to control the pH to 7-8. After the reaction, precipitation is completed, and the first-stage defluorination is completed. The supernatant enters the chemical deep precipitation and defluorination unit 3, where 0.3 mol / L sodium dihydrogen phosphate (dosage 300 mg / L) is added to generate calcium fluorophosphate precipitate for secondary enhanced defluorination to remove fluoride ions. (2) The wastewater treated above is subjected to ammonia nitrogen stripping device 4. A blower (blowing speed: 100ml / min) is used to pump the ammonia absorption device 5. The ammonia is absorbed by a 1 mol / L dilute sulfuric acid solution to generate ammonium sulfate solution for recovery. The gaseous ammonia generated in the ammonia nitrogen stripping device is introduced into the absorption tower, thus achieving efficient absorption and fixation of stripped ammonia. (3) Subsequently, the wastewater enters the circulating adsorption defluorination tank 6, which is filled with alumina particles with a particle size of 2-4 mm, and the adsorption defluorination device 9, which is filled with activated alumina with a particle size of 1-5 mm for deep defluorination. After this treatment, the fluoride ion concentration is reduced from 3921 mg / L to below 1 mg / L, effectively ensuring the lifespan of the downstream electrodes. After defluorination, the wastewater enters the first electrolysis circulating water tank 7. This system includes a stainless steel anode and a stainless steel cathode, and the system current density is 50 mA / cm². 2 The polar water ratio is 100 L / m 2 And a first electrochemical unit 10, the system comprising a size-stabilized DSA (Ti / RuO2-IrO2) as the anode, stainless steel as the cathode, and a controlled current density of 30 mA / cm². 2 The polar water ratio is 100 L / m 2 It is used for electrochemical cyclic processing.

[0040] (4) Subsequently, the wastewater flows out of the water tank 7 and enters the second electrolytic circulating water tank 8 and the ion exchange denitrification device 11, where the trace amounts of nitrile nitrogen that may be generated are deeply removed using the selective anion exchange resin IRA402. The small amount of high-salt wastewater generated during resin regeneration enters the ion resin regeneration water-second electrochemical unit 12 for centralized oxidation treatment.

[0041] Specifically, the changes in COD and ammonia nitrogen over time after the system finally passes through the ion exchange resin-regenerated water-second electrochemical unit 12 are as follows: Figure 4As shown, COD = 68 mg / L and ammonia nitrogen = 38 mg / L, which meets the discharge standards (COD < 500 mg / L; ammonia nitrogen < 70 mg / L) of the Integrated Wastewater Discharge Standard (DB12 / 356-2018).

[0042] The above embodiments only describe a portion of the specific implementation methods of the present invention in detail, and are not limited to the embodiments disclosed herein. Furthermore, the substantive content protected by the present invention is not limited thereto. Any other modifications, equivalent substitutions, improvements, etc., made based on the principles and techniques of the present invention without departing from its design scope are all within the protection scope of the present invention.

Claims

1. A process treatment system for FPSO pipeline chemical cleaning waste fluids, characterized by, The system comprises a reduction denitration device (1), a chemical precipitation defluorination device (2), a chemical deep precipitation defluorination device (3), a stripping ammonia nitrogen device (4), an ammonia gas absorption device (5), a circulating adsorption defluorination pool (6), a first electrolytic circulating pool (7), a second electrolytic circulating pool (8), the above devices are sequentially connected, the circulating adsorption defluorination pool (6) is connected with an adsorption defluorination device (9), the defluorination is cooperatively controlled, the first electrolytic circulating pool (7) is connected with a first electrochemical unit (10), the degradation of COD and ammonia nitrogen is cooperatively controlled, the second electrolytic circulating pool (8) is connected with an ion exchange denitration device (11), the secondary degradation of COD and ammonia nitrogen is cooperatively controlled, the ion exchange denitration device (11) is connected with an ion resin regenerated water-second electrochemical treatment unit (12), the second electrolytic circulating pool (8) and the ion resin regenerated water-second electrochemical treatment unit (12) are respectively provided with an outlet.

2. The process treatment system for FPSO pipeline chemical cleaning waste fluid according to claim 1, wherein, The reducing agent used in the reduction denitration device (1) is aminosulfonic acid, ferrous salt, sodium thiosulfate or zero-valent iron material modified by any one or more of sulfur, copper, boron and nickel.

3. The process treatment system for FPSO pipeline chemical cleaning waste fluid according to claim 1, wherein, The calcium agent used in the chemical precipitation defluorination device (2) is a composite calcium salt composed of one or more of calcium chloride, calcium oxide, calcium hydroxide, calcium carbonate and calcium nitrate.

4. The process treatment system for FPSO pipeline chemical cleaning waste fluid of claim 1, wherein, The phosphorus agent put into the chemical deep precipitation defluorination device (3) is sodium dihydrogen phosphate.

5. The process treatment system for FPSO pipeline chemical cleaning waste fluid of claim 1, wherein, The stripping ammonia nitrogen device (4) adopts a blowing equipment, the blowing flow rate is 100 ml / min, the ammonia gas absorption device (5) contains 1 mol / L dilute sulfuric acid solution.

6. The process treatment system for FPSO pipeline chemical cleaning waste fluid of claim 1, wherein, The adsorption defluorination device (6) is filled with any one of active alumina, hydroxyapatite, modified activated carbon loaded with aluminum or lanthanum or anion exchange resin alumina or ion exchange resin particles having selective adsorption function for fluoride ions.

7. The process treatment system for FPSO pipeline chemical cleaning waste fluid of claim 1, wherein, The first electrolytic circulating water pool (7), the second electrolytic circulating water pool (8) are two sets of same electrochemical systems, the electrochemical systems include stainless steel anode, stainless steel cathode, system current density is 50 mA / cm 2 , pole water ratio is 100 L / m 2 , the first electrochemical unit (10), ion resin regeneration water-second electrochemical unit (12) are two sets of same electrochemical systems, the system includes dimensionally stable anode, stainless steel cathode, system current density is 30 mA / cm 2 , pole water ratio is 100 L / m 2 .

8. The process treatment system for FPSO pipeline chemical cleaning waste fluid of claim 1, wherein, The adsorption defluorination device (9) is filled with any one of active alumina, hydroxyapatite, modified activated carbon loaded with aluminum or lanthanum or anion exchange resin alumina or ion exchange resin particles having selective adsorption function for fluoride ions.

9. The process treatment system for FPSO pipeline chemical cleaning waste fluid of claim 1, wherein, The ion exchange denitration device (11) is filled with anion exchange resin having high selectivity for nitrate.

10. Application of the process treatment system of any one of claims 1-9 to treatment of FPSO pipeline chemical cleaning waste liquid.

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