Method and system for resource utilization of high-ammonium salt spray wastewater from chemical incineration flue gas by simultaneously recovering magnesium ammonium phosphate and ammonium sulfate

Abstract

The present invention discloses a method for recycling high ammonium salt spray wastewater from chemical incineration flue gas by simultaneously recovering magnesium ammonium phosphate and ammonium sulfate. The method comprises the following steps: S1, adding alkali for precipitation: Fe 3+ Ions and suspended particles are neutralized and precipitated to remove them; S2, O3 oxidation synergistic adsorption filtration purification: the O3 generator sprays the generated O3 into the adsorption filter inlet and fully mixes it with the wastewater; S3, magnesium ammonium phosphate precipitation: Mg is quantitatively added to the effluent of O3 oxidation synergistic adsorption filtration purification 2+ and phosphate, and the high concentration of NH4 in the spray wastewater + Reaction precipitation is carried out to generate magnesium ammonium phosphate precipitate; S4, aeration elution to remove NH3: a combination of microporous aeration and circulating elution is used to remove low concentration NH4 in the spray wastewater. + Removal; S5, ammonium sulfate pickling recovery; S6, flue gas waste heat cascade evaporation. This invention innovates the flue gas treatment spray wastewater zero discharge process, achieving deep purification and recycling of chemical incineration flue gas spray wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment wastewater resource utilization, and in particular to a method and system for simultaneously recovering magnesium ammonium phosphate and ammonium sulfate from chemical incineration flue gas high-ammonium salt spray wastewater resource utilization. Background Art

[0002] High-temperature incineration has become a primary method for treating toxic and hazardous waste in my country's chemical industry, and is now used by numerous chemical companies to effectively dispose of high-salt organic wastewater. For example, glyphosate, my country's most produced pesticide, produces over 3.2 million tons of high-salt organic wastewater (4-5 tons per ton of product) annually during its production. Currently, this high-salt organic wastewater, containing multiple elements such as phosphorus, nitrogen, and chlorine, is pre-concentrated through oxidation and then directly disposed of using "high-temperature incineration conversion." This process recovers the high-value phosphorus in the organic wastewater as phosphate products (such as sodium pyrophosphate and trisodium phosphate). This process has been implemented in over 80% of glyphosate production companies in my country.

[0003] As my country's pollution emission standards become increasingly stringent, the flue gas emitted during the incineration of chemical organic waste liquids urgently needs to be effectively treated. Chemical companies typically use wet treatment processes such as "quenching deacidification + bag dust removal + spray absorption" and "high-efficiency dust removal + spray absorption deacidification + wet electrostatic demisting." After the incineration flue gas is efficiently treated by wet processes, the pollutant emission concentrations can meet the limits of various emission standards. However, the current chemical incineration flue gas treatment system using wet deacidification technology has a problem with the circulating absorption liquid capturing a large amount of NH3, HCl, ammonium salts, and organic matter, resulting in its color, suspended solids content, salt content, COD, ammonia nitrogen and other pollution indicators gradually exceeding the standard, and the purification effect of the flue gas treatment system has deteriorated. To address this problem, the only effective solution for companies is to replace the absorption liquid with fresh water in a timely manner, which further leads to the discharge of large amounts of spray wastewater. The destination and disposal of high-salt and high-ammonia nitrogen wastewater are key technical difficulties affecting the stable operation of chemical incineration systems. Therefore, deep purification and recycling of high-salt spray wastewater from chemical incineration flue gas is an effective means to stabilize the operation of the current chemical incineration flue gas treatment system, reduce enterprise operating costs and achieve pollution reduction and carbon reduction.

[0004] It's worth noting that the flue gas spray wastewater used for high-efficiency incineration of glyphosate mother liquor contains large amounts of suspended solids, ammonium chloride, ammonium sulfate, water-soluble organic matter, small amounts of phosphate, and excessive amounts of water-soluble NH3, among other pollutants. Wastewater index testing shows that the concentrations of various indicators are significantly higher than those in conventional flue gas deacidification wastewater. Furthermore, the pollutant components are complex, making deep purification difficult.

[0005] The Chinese patent document with application number 202110807720.9 discloses a system for recovering acid and alkali from high-salt deacidification wastewater, comprising a homogenizing tank, a first reaction tank, a second reaction tank, a sedimentation tank, a concentration tank, an ultrafiltration device, an ultrafiltration water production tank, a nanofiltration device, a nanofiltration water production tank, a reverse osmosis device, a reverse osmosis concentrated water tank and a bipolar membrane electrodialysis device connected in sequence; a CaCl2 dosing device is provided above the first reaction tank, a Na2CO3 dosing device is provided above the second reaction tank, and a hydrochloric acid dosing device is provided above the ultrafiltration water production tank. This method uses the NaCl-containing solution obtained from the reverse osmosis concentrate to obtain NaOH and HCl through a bipolar membrane electrodialysis device. However, the overall process flow of the system is relatively long, and the investment and maintenance costs of nanofiltration, ultrafiltration, reverse osmosis and other devices are relatively high. In addition, the NaOH and HCl obtained by electrodialysis have low product value. This method is completely unsuitable for the resource utilization of high-salt wastewater containing ammonia nitrogen in chemical incineration flue gas.

[0006] Chinese patent document with application number 201811464493.9 discloses a method for resource utilization and zero-emission treatment of acidic, high-ammonia, and high-salt wastewater, comprising: the acidic, high-ammonia, and high-salt wastewater first enters an acid recovery system to recover hydrochloric acid in the wastewater, and the recovered acid is reused in the production process; the deacidified residual liquid obtained after acid recovery is added with excess iron powder for replacement and then enters a coagulation and sedimentation system, where alkali is added to undergo complex precipitation to remove precious and base metals, and the supernatant obtained enters a stable gas membrane system, and the precipitated sludge enters a sludge concentration and dehydration system for further concentration and dehydration, and the dehydrated sludge obtained is transported out; the supernatant is used in the stable gas membrane system with a 15-20% hydrochloric acid solution as an absorption liquid to recover ammonia nitrogen substances in the wastewater, and 15-20% ammonium chloride solution can be recovered. At the same time, the effluent from the stable gas membrane system is evaporated and crystallized in an evaporation and crystallization system to obtain condensed water and solid salt for reuse, thereby achieving resource utilization and zero emission. This method also uses diffusion dialysis and membrane treatment, which can lead to clogging issues. Direct evaporation and crystallization consumes a lot of energy and has high overall operating and maintenance costs. Furthermore, the use of hydrochloric acid solution to absorb ammonia nitrogen from wastewater results in incomplete purification and the generation of secondary pollution such as aerosols and acid mist. Summary of the Invention

[0007] The present invention addresses the technical difficulties of resource utilization and zero emission of high-ammonium salt and high-ammonia nitrogen spray wastewater during the incineration disposal of glyphosate mother liquor, and provides a resource utilization method for high-ammonium salt spray wastewater from chemical incineration flue gas, which simultaneously recovers magnesium ammonium phosphate and ammonium sulfate. The method achieves deep purification and recycling of chemical incineration flue gas spray wastewater, and directly converts high-concentration NH3, ammonium salt and other nitrogen elements captured in the flue gas into high-purity, high-value chemical fertilizer additive products (magnesium ammonium phosphate, ammonium sulfate). The method has technical advantages such as short process, high efficiency, resource utilization, energy saving and consumption reduction, meets the requirements of industrial application, and has significant benefits of industrial application.

[0008] The technical solution adopted by the present invention to solve its technical problem is:

[0009] A method for recycling wastewater from high-ammonium salt spraying of chemical incineration flue gas by simultaneously recovering magnesium ammonium phosphate and ammonium sulfate, characterized in that the method comprises the following steps:

[0010] S1, alkali precipitation: the spray wastewater of the flue gas spray equipment is fully mixed with 20-40% NaOH solution in the pipeline, the pH of the spray wastewater is controlled at 8-10, and the spray wastewater enters the inclined tube sedimentation tank to remove Fe 3+ Ions and suspended particles are neutralized and precipitated for removal;

[0011] S2, O3 oxidation synergistic adsorption filtration purification: The effluent from the inclined tube sedimentation tank enters the adsorption filter for O3 oxidation synergistic adsorption filtration purification process. The O3 generator sprays the generated O3 into the adsorption filter inlet for thorough mixing with the wastewater. The adsorption filter is filled with porous adsorption materials such as quartz sand, alumina balls, and activated carbon in layers from bottom to top, with a single layer of material filling thickness of 100mm to 500mm. This step is used to adsorb and oxidize water-soluble organic matter in the wastewater, while deeply filtering and purifying suspended particulate matter.

[0012] S3, magnesium ammonium phosphate precipitation: quantitatively add Mg to the water purified by O3 oxidation and adsorption filtration 2+ and phosphate, stir evenly, and spray the high concentration of NH4 in the wastewater + Performing reaction precipitation to generate magnesium ammonium phosphate precipitate, and allowing to stand to recover the magnesium ammonium phosphate;

[0013] S4, aeration leaching to remove NH3: the supernatant after the precipitation of magnesium ammonium phosphate enters the aeration leaching tank, and the low concentration of NH4 in the spray wastewater is removed by a combination of microporous aeration and circulating leaching. + Remove and generate gaseous NH3 for acid washing and recovery;

[0014] S5, ammonium sulfate pickling recovery: the NH3 removed from the spray wastewater is neutralized and absorbed with a sulfuric acid solution with a pH of 3 to 4 to obtain a 10% to 25% ammonium sulfate solution;

[0015] S6. Stepwise evaporation of flue gas waste heat: The deeply purified high-salt clarified wastewater obtained in the above steps, the recovered ammonium sulfate solution, and the magnesium ammonium phosphate precipitate are subjected to stepwise evaporation and drying, and the high-ammonium salt wastewater is deeply desalted, the ammonium sulfate is dried, and the magnesium ammonium phosphate is dried in sequence to obtain ammonium sulfate and magnesium ammonium phosphate products; wherein the stepwise evaporation comprises: providing at least three groups of evaporators connected in series, so that the flue gas with waste heat flows through the three groups of evaporators in sequence for heat exchange and the flue gas temperature gradually decreases, the first group of evaporators produces sodium salt, the second group of evaporators produces ammonium sulfate, and the third group of evaporators produces magnesium ammonium phosphate; the water vapor after evaporation and drying is condensed and reused in the flue gas spraying equipment.

[0016] The spray wastewater is alkali-added to adjust pH and precipitated to remove Fe 3+ After the suspended particles and O3 oxidation synergistic adsorption filtration purify COD, the wastewater is basically clear and colorless, and then Mg is added 2+ , phosphate to obtain magnesium ammonium phosphate precipitate; aeration leaching is used to deeply remove low-concentration NH3 in the wastewater, and sulfuric acid solution is neutralized and absorbed to obtain 10% to 25% ammonium sulfate solution; the salt-containing wastewater after multi-stage purification treatment enters the flue gas waste heat evaporation for deep desalination and then recycled; at the same time, the flue gas waste heat is used to cascade evaporate the ammonium sulfate solution and magnesium ammonium phosphate precipitate to obtain high-purity, high-value chemical fertilizer additive products; the flue gas waste heat cascade evaporation process uses high-temperature flue gas for heat exchange, and evaporates and dries the high-salt clarified wastewater, 10% to 25% ammonium sulfate solution, and magnesium ammonium phosphate precipitate in turn, realizing the recycling of spray wastewater and obtaining high-purity, high-value chemical fertilizer additive products (magnesium ammonium phosphate, ammonium sulfate).

[0017] Preferably, the spray wastewater of the flue gas spraying equipment is the high-salt and high-ammonia nitrogen spray wastewater discharged from the flue gas treatment spraying system of the glyphosate mother liquor incineration disposal.

[0018] Preferably, the wastewater sprayed by the flue gas spraying equipment has a water temperature of 80-100° C., a pH of 4-6, a salt content of 10-100 g / L, and an NH 3 -N content of 1000-5000 mg / L.

[0019] As a preference, the outflow rate of the spray wastewater of the flue gas spraying equipment is controlled at 3m 3 / h.

[0020] Preferably, in step S1, the concentration of the NaOH solution is 40%, the flow volume ratio of the NaOH solution to the spray wastewater is 1:300, and the pH of the spray wastewater is 9 to 9.5;

[0021] In step S2, the amount of O3 added is 0.1-0.5 g / L of spray wastewater; the filling ratio of quartz sand, alumina balls, and activated carbon in the adsorption filter is 50:100:100, and the single-layer filling thickness is 500 mm;

[0022] In step S3, Mg 2+ NH4 + , the molar ratio of phosphate addition is 1.2:1:0.8;

[0023] In step S4, the microporous aeration air volume is 0.1m 3 / L spray wastewater;

[0024] In step S5, a 5% sulfuric acid solution is added to control the system pH to be less than 3.5, and the concentration of the recovered ammonium sulfate solution to be greater than 15%;

[0025] In step S6, the evaporation and drying process, the flue gas waste heat temperature is greater than 150°C.

[0026] In step S1, the alkalinity of 40% NaOH solution is high, which is conducive to rapid neutralization and precipitation. The NaOH solution with a flow volume ratio of 1:300 to the spray wastewater can effectively control the pH of the mixed spray wastewater to 9-9.5, which is suitable for Fe 3+ Ion precipitation; in step S2, 0.1 ~ 0.5g / L spray wastewater dosage of O3 can fully oxidize water-soluble organic matter, the ratio and thickness of the adsorption filter filler can make the wastewater fully react with O3 and achieve deep filtration; in step S3, Mg 2+ NH4 + The addition molar ratio of phosphate can optimize the production of magnesium ammonium phosphate; in step S4, 0.1m 3 / L of microporous aeration air volume for spraying wastewater can provide sufficient gas-liquid contact area, thereby improving the removal rate of NH3; in step S5, acidity control can effectively absorb NH3 to generate ammonium sulfate, and the recovery concentration of ammonium sulfate solution above 15% can reduce the subsequent evaporation amount; in step S6, the flue gas with a temperature above 150°C can provide sufficient heat source for the evaporation process.

[0027] A chemical incineration flue gas high ammonium salt spray wastewater resource recovery system for simultaneously recovering magnesium ammonium phosphate and ammonium sulfate, the system comprising a flue gas spray device, an inclined tube sedimentation tank, an adsorption filter, a magnesium ammonium phosphate sedimentation tank, an aeration leaching tank, an acid wash recovery tank, and a flue gas waste heat cascade evaporation device connected in sequence by pipelines;

[0028] The water outlet of the flue gas spray equipment is connected to the inlet of the inclined tube sedimentation tank. A mud discharge pipeline is provided at the bottom of the inclined tube sedimentation tank. The water outlet of the inclined tube sedimentation tank is connected to the bottom of the adsorption filter, so that the incoming wastewater is adsorbed and filtered from bottom to top.

[0029] The top outlet pipe of the adsorption filter is connected to the water inlet of the magnesium ammonium phosphate precipitation tank;

[0030] The outlet of the magnesium ammonium phosphate precipitation tank is connected to the circulating elution device of the aeration elution tank to achieve circulating elution of the incoming wastewater. A microporous aeration device is installed at the bottom of the aeration elution tank to fully mix the wastewater sprayed from above with the air.

[0031] The gas phase outlet at the top of the aeration and leaching tank is connected to the lower part of the pickling recovery tank, and a spraying device for circulating and spraying sulfuric acid solution is provided in the aeration and leaching tank;

[0032] The flue gas waste heat cascade evaporation equipment includes at least three groups of evaporators connected in series, which are used to allow the flue gas with waste heat to flow through the three groups of evaporators in sequence for heat exchange and the flue gas temperature gradually decreases. The bottom outlet of the aeration and leaching tank is connected to the cold end inlet of the first group of evaporators, the bottom outlet of the pickling recovery tank is connected to the cold end inlet of the second group of evaporators, and the bottom outlet of the magnesium ammonium phosphate precipitation tank is connected to the cold end inlet of the third group of evaporators. The gas phase outlet of the flue gas waste heat cascade evaporation equipment is connected to the middle part of the flue gas spray equipment through a condenser.

[0033] Preferably, the adsorption filter is filled with porous adsorption materials such as quartz sand, alumina balls, activated carbon, etc. in layers from bottom to top, and the thickness of a single layer of material is 100mm to 500mm.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) Innovated the zero-discharge process of flue gas treatment spray wastewater, achieved deep purification and recycling of chemical incineration flue gas spray wastewater, and adopted the flue gas waste heat step evaporation method to carry out step evaporation and drying of salt solutions of different concentrations, thus obtaining more than two kinds of high-quality chemical products, with significant energy saving and consumption reduction;

[0036] (2) The nitrogen elements such as NH3 and ammonium salts captured in the flue gas are converted into high-purity, high-value magnesium ammonium phosphate and ammonium sulfate products. This method achieves the thorough purification of high-concentration ammonia nitrogen in the spray wastewater in an efficient resource-based manner and effectively avoids the problem of excessive flue gas pollution, with significant economic and environmental benefits.

[0037] (3) The process adopts a short process and continuous approach. The process equipment is simple to operate, has high disposal efficiency, and is easy to promote. It is effectively coupled with the flue gas treatment spray system to ensure the efficient and stable operation of the flue gas treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic structural diagram of the spray wastewater resource utilization system of the present invention;

[0039] Among them, 1. Inclined tube sedimentation tank, 2. Adsorption filter, 3. Magnesium ammonium phosphate sedimentation tank, 4. Aeration leaching tank, 5. Pickling recovery tank, 6. Flue gas waste heat cascade evaporation equipment, 7. Flue gas spray equipment. DETAILED DESCRIPTION

[0040] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] The present invention will now be further described in conjunction with specific examples. The following examples are only intended to explain the present invention but do not limit the present invention. The test samples and test procedures used in the following examples include the following (if the specific experimental conditions are not specified in the examples, they are usually based on conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources).

[0043] The source of the spray wastewater in the following examples is the high-ammonium salt and high-ammonia nitrogen spray wastewater generated during the incineration disposal of glyphosate by-products (mother liquor).

[0044] The present invention targets high-salt, high-ammonia nitrogen spray wastewater emitted from a flue gas treatment spray system for the incineration of glyphosate byproducts (mother liquor). The flue gas primarily captures and absorbs pollutants such as ammonium chloride, ammonium sulfate, water-soluble organic matter, and NH3. Specifically, the spray wastewater from the flue gas spray system has a temperature of 80-100°C, a pH of 4-8, a salt content of 10-200 g / L, and an NH3-N content of 1000-3000 mg / L. Five batches of spray wastewater were prepared in this embodiment of the present invention. The water quality indicators of the different batches of spray wastewater are shown in Table 1.

[0045] Table 1. Water quality indicators of different batches of spray wastewater

[0046] Spray wastewater indicators pH TDS, g / L COD, mg / L <![CDATA[NH3-N,mg / L]]> Batch 1 7.7 131.2 8800 1870 Batch 2 4.6 182.1 16000 2900 Batch 3 5.4 130.7 9000 1710 Batch 4 6.2 181.3 9800 2840 Batch 5 4.3 32.6 15840 1140

[0047] Example

[0048] A chemical incineration flue gas high ammonium salt spray wastewater resource recovery system for simultaneously recovering magnesium ammonium phosphate and ammonium sulfate, such as Figure 1 As shown, the system includes a flue gas spraying device 7, an inclined tube sedimentation tank 1, an adsorption filter 2, a magnesium ammonium phosphate sedimentation tank 3 and an aeration leaching tank 4, a pickling recovery tank 5 and a flue gas waste heat cascade evaporation device 6 connected in sequence by pipelines.

[0049] The outlet of flue gas spraying equipment 7 is connected to the inlet of inclined tube sedimentation tank 1. A sludge drainage pipeline is installed at the bottom of inclined tube sedimentation tank 1. The outlet of inclined tube sedimentation tank 1 is connected to the bottom of adsorption filter 2, so that the incoming wastewater is adsorbed and filtered from bottom to top. Adsorption filter 2 is filled with porous adsorption materials such as quartz sand, alumina beads, and activated carbon in layers from bottom to top. The thickness of each layer ranges from 100mm to 500mm.

[0050] The top water outlet pipeline of the adsorption filter 2 is connected to the water inlet of the magnesium ammonium phosphate precipitation tank 3.

[0051] The outlet of the magnesium ammonium phosphate precipitation tank 3 is connected to the circulating elution device of the aeration elution tank 4, so that the incoming wastewater can be circulated and eluted. A microporous aeration device is set at the bottom of the aeration elution tank 4 to fully mix the wastewater sprayed from above with the air.

[0052] The gas phase outlet at the top of the aeration and leaching tank 4 is connected to the lower part of the pickling recovery tank 5. A spraying device for circulating and spraying the sulfuric acid solution is provided in the aeration and leaching tank 4.

[0053] The flue gas waste heat cascade evaporation equipment 6 includes at least three groups of evaporators connected in series, which are used to allow the flue gas with waste heat to flow through the three groups of evaporators in sequence for heat exchange and the flue gas temperature gradually decreases. The bottom outlet of the aeration and leaching tank 4 is connected to the cold end inlet of the first group of evaporators, the bottom outlet of the pickling recovery tank 5 is connected to the cold end inlet of the second group of evaporators, and the bottom outlet of the magnesium ammonium phosphate precipitation tank 3 is connected to the cold end inlet of the third group of evaporators. The gas phase outlet of the flue gas waste heat cascade evaporation equipment 6 is connected to the middle part of the flue gas spray equipment 7 through a condenser.

[0054] A method for recycling high-ammonium salt spray wastewater from chemical incineration flue gas by simultaneously recovering magnesium ammonium phosphate and ammonium sulfate, the method comprising the following steps:

[0055] S1. Alkali precipitation: The spray wastewater of the above-mentioned flue gas treatment system is pumped out and the flow rate is controlled at 0.1~0.5m 3 / h and fully mixed with 20-40% NaOH solution in the pipeline, controlling the pH of the spray wastewater at 8-10, and entering the inclined tube sedimentation tank to remove Fe 3+ and complex precipitation of impurities such as suspended particles.

[0056] S2, O3 oxidation synergistic adsorption filtration purification: The effluent from the inclined tube sedimentation tank enters the adsorption filter for O3 oxidation synergistic adsorption filtration purification process. The O3 generator sprays the generated O3 into the inlet of the adsorption filter for thorough mixing with the wastewater. The water-soluble organic matter in the wastewater is adsorbed on quartz sand, activated carbon, and alumina ball materials. Under the oxidation action of O3 in the water, the water-soluble organic matter is completely mineralized, and suspended particulate matter is intercepted. The wastewater is basically clear and colorless, but still contains high concentrations of NH3-N and salt.

[0057] S3, magnesium ammonium phosphate precipitation: the pH of the wastewater is precisely controlled at about 9-9.5, and the wastewater enters the magnesium ammonium phosphate precipitation tank. According to the concentration of NH3-N and phosphate in the wastewater, magnesium sulfate and trisodium phosphate are accurately added to the wastewater to reduce the high concentration of NH4 + After the reaction precipitation, the magnesium ammonium phosphate precipitate is collected. After the secondary precipitation, the high concentration of NH4 + The removal rate is above 80%.

[0058] S4, aeration leaching to remove NH3: After the water is precipitated, it enters the aeration leaching process, using microporous enhanced air aeration and wastewater circulation leaching to remove low-concentration NH4 + Remove and generate gaseous NH3 for acid washing and recovery;

[0059] S5, ammonium sulfate pickling recovery: The gas phase product is sprayed and pickled in the pickling recovery tank 5 using a sulfuric acid solution with a pH of 3 to 4 to obtain a 10% to 25% ammonium sulfate solution.

[0060] S6. Step-by-step evaporation of flue gas waste heat: The spray wastewater after aeration and leaching is mainly composed of NaCl and a small amount of pollutants, that is, high-salt clarified wastewater. It is subjected to step-by-step evaporation and drying with ammonium sulfate solution and magnesium ammonium phosphate precipitate respectively, so that the high-ammonium salt wastewater is deeply desalted, the ammonium sulfate is dried, and the magnesium ammonium phosphate is dried in turn to obtain ammonium sulfate and magnesium ammonium phosphate products; wherein, the step-by-step evaporation includes: setting at least three groups of evaporators connected in series, so that the flue gas with waste heat flows through the three groups of evaporators in turn for heat exchange and the flue gas temperature gradually decreases, the first group of evaporators produces sodium salt, the second group of evaporators produces ammonium sulfate, and the third group of evaporators produces magnesium ammonium phosphate; the water vapor after evaporation and drying is condensed and reused in the flue gas spraying equipment.

[0061] Comparative Example: Pilot test on resource utilization of high ammonium salt spraying wastewater from chemical incineration flue gas

[0062] 0.1~0.5m 3 / h Chemical Incineration Flue Gas Spray Wastewater Resource Utilization Pilot Test Device Design Parameters: Inclined Tube Sedimentation Tank Effective Volume 1.15m 3 、The effective volume of adsorption filter is 0.25m 3 、The effective volume of magnesium ammonium phosphate precipitation tank is 0.8m 3 、The effective volume of aeration and leaching tank is 0.5m 3 , Pickling recovery gas volume 150m 3 / h.

[0063] The pH automatic control system is used to adjust the frequency of NaOH addition to ensure that the pH of the sedimentation tank is between 8 and 10. The wastewater undergoes reaction precipitation, adsorption filtration, and enters the magnesium ammonium phosphate precipitation tank to recover the magnesium ammonium phosphate precipitate. The NH3 in the wastewater is completely separated by aeration elution and enters the H2SO4 absorption tower (pH is controlled between 3 and 4) to recover the ammonium sulfate solution.

[0064] Test conditions:

[0065] (1) Spray wastewater treatment flow rate 0.33m 3 / h;

[0066] (2) In the alkali precipitation process, the concentration of NaOH is 20%, and the pH of the spray wastewater is controlled at 8-10;

[0067] (3) Adsorption and filtration process, the filling amount of quartz sand and activated carbon is 100L respectively, and no O3 is added:

[0068] (4) Magnesium ammonium phosphate precipitation process, Mg 2+ NH4 + , the molar ratio of phosphate addition is 1.2:1:0.8;

[0069] (6) Aeration and leaching process, the microporous aeration air volume is 100m 3 / h;

[0070] (7) In the ammonium sulfate pickling recovery process, a 5% sulfuric acid solution is added and the pH is controlled at 3-4.

[0071] Test results:

[0072] After continuous and stable operation for more than 1000 hours, the spray wastewater becomes clear and colorless after alkali precipitation and adsorption filtration; after magnesium ammonium phosphate precipitation, the magnesium ammonium phosphate precipitate is recovered, and the purity exceeds 95% after drying; and the recovery concentration of ammonium sulfate solution is >10%, and the ammonia nitrogen purification efficiency of the spray wastewater is more than 99%.

[0073] Application example: Verification of resource utilization project for high ammonium salt spraying wastewater from chemical incineration flue gas

[0074] At 30000m 3 / h gas processing volume: A pesticide chemical enterprise's glyphosate mother liquor incineration flue gas deep treatment system, the system uses 30m3 of spray absorption liquid 3 Build a spray wastewater external circulation treatment system, the wastewater design treatment flow is 3m 3 / h, the wastewater treatment cycle is about 10h, and the treatment frequency is once a day.

[0075] Design parameters: effective volume of inclined tube sedimentation tank 7.5m 3 、The effective volume of adsorption filter is 3.0m 3、The effective volume of magnesium ammonium phosphate precipitation tank is 5.0m 3 、Aeration leaching tank effective volume 3.0m 3 , Pickling recovery gas volume 1000m 3 / h.

[0076] Operating conditions:

[0077] In the alkali precipitation process, the concentration of NaOH solution is 40%, and the ratio of NaOH solution to wastewater flow is 1:300. The pH of wastewater is precisely controlled at 9-9.5.

[0078] In the adsorption and filtration process, the O3 dosage is 0.1-0.5g / L wastewater; the filling ratio of quartz sand, alumina balls, and activated carbon is 50:100:100, and the single-layer filling thickness is 500mm;

[0079] Magnesium ammonium phosphate precipitation process, Mg 2+ NH4 + , the molar ratio of phosphate addition is 1.2:1:0.8;

[0080] In the aeration and leaching process, the microporous aeration air volume is 0.1m 3 / L spray wastewater;

[0081] In the ammonium sulfate pickling recovery process, add 5% sulfuric acid solution, accurately control the pH <3.5, and the ammonium sulfate solution recovery concentration >15%;

[0082] In the evaporation and drying process, the flue gas waste heat temperature is >150℃.

[0083] Verification results: Continuous and stable operation for more than 3000 hours, far exceeding the control example. The spray wastewater is clear and colorless after alkali precipitation and adsorption filtration. After precipitation with magnesium ammonium phosphate, the magnesium ammonium phosphate precipitate is recovered, and the purity after drying is tested to be over 95%; the recovery concentration of ammonium sulfate solution is >15%, which is higher than the control example. After drying, no other impurities are detected, and the purity exceeds 98%; the comparison of data before and after purification of the spray wastewater is shown in Table 2; the salt-containing clarified wastewater is evaporated by 150℃ flue gas, and the condensed water is recovered and directly reused in the flue gas spray equipment.

[0084] Table 2. Comparison of data before and after spray wastewater purification

[0085] Test items Before treatment After processing Detection method <![CDATA[Chromaticity (Fe 3+ impurities)]]> brownish yellow Nearly colorless Colorimetry COD, mg / L 35500 5400 Hach water quality analyzer <![CDATA[NH3-N,mg / L]]> 1191 131 Hach water quality analyzer

[0086] In summary, the present invention achieves deep purification and recycling of chemical incineration flue gas spray wastewater, and directly converts high-concentration NH3, ammonium salts and other N elements captured in the flue gas into high-purity, high-value chemical fertilizer additive products (magnesium ammonium phosphate, ammonium sulfate). It has technical advantages such as short process, high efficiency, resource utilization, energy saving and consumption reduction, and has significant benefits in industrial application.

[0087] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0088] The above is a detailed introduction to the method and system for resource utilization of high ammonium salt spray wastewater from chemical incineration flue gas for simultaneously recovering magnesium ammonium phosphate and ammonium sulfate provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for recycling wastewater from chemical incineration flue gas high ammonium salt spraying by simultaneously recovering magnesium ammonium phosphate and ammonium sulfate, characterized by: The method comprises the following steps: S1, alkali precipitation: the spray wastewater of the flue gas spray equipment is fully mixed with 20-40% NaOH solution in the pipeline, the pH of the spray wastewater is controlled at 8-10, and the spray wastewater enters the inclined tube sedimentation tank to remove Fe 3+ Ions and suspended particles are neutralized and precipitated for removal; S2, O3 oxidation synergistic adsorption filtration purification: The effluent from the inclined tube sedimentation tank enters the adsorption filter for O3 oxidation synergistic adsorption filtration purification. The O3 generator sprays the generated O3 into the adsorption filter inlet for thorough mixing with the wastewater. The adsorption filter is filled with a porous adsorption material composed of quartz sand, alumina beads, and activated carbon in layers from bottom to top, with a single layer thickness of 100mm to 500mm. This step is used for the adsorption and oxidation of water-soluble organic matter in the wastewater, while also deeply filtering and purifying suspended particulate matter. S3, magnesium ammonium phosphate precipitation: quantitatively add Mg to the water purified by O3 oxidation and adsorption filtration 2+ and phosphate, stir evenly, and spray the high concentration of NH4 in the wastewater + Performing reaction precipitation to generate magnesium ammonium phosphate precipitate, and allowing to stand to recover the magnesium ammonium phosphate; S4, aeration leaching to remove NH3: the supernatant after the precipitation of magnesium ammonium phosphate enters the aeration leaching tank, and the low concentration of NH4 in the spray wastewater is removed by a combination of microporous aeration and circulating leaching. + Remove and generate gaseous NH3 for acid washing and recovery; S5, ammonium sulfate pickling recovery: the NH3 removed from the spray wastewater is neutralized and absorbed with a sulfuric acid solution with a pH of 3 to 4 to obtain a 10% to 25% ammonium sulfate solution; S6. Stepwise evaporation of flue gas waste heat: The deeply purified high ammonium salt wastewater, recovered ammonium sulfate solution, and magnesium ammonium phosphate precipitate obtained in the above steps are subjected to stepwise evaporation and drying, and the high ammonium salt wastewater is deeply desalted, the ammonium sulfate is dried, and the magnesium ammonium phosphate is dried in sequence to obtain ammonium sulfate and magnesium ammonium phosphate products; wherein the stepwise evaporation comprises: providing at least three groups of evaporators connected in series, so that the flue gas with waste heat flows through the three groups of evaporators in sequence for heat exchange and the flue gas temperature gradually decreases, the first group of evaporators produces sodium salt, the second group of evaporators produces ammonium sulfate, and the third group of evaporators produces magnesium ammonium phosphate; the water vapor after evaporation and drying is condensed and reused in the flue gas spraying equipment.

2. The method for recycling wastewater from chemical incineration flue gas high ammonium salt spraying for simultaneous recovery of magnesium ammonium phosphate and ammonium sulfate according to claim 1, characterized in that: The spray wastewater of the flue gas spray equipment is high-salt and high-ammonia nitrogen spray wastewater discharged from the flue gas treatment spray system of glyphosate mother liquor incineration disposal.

3. The method for recycling wastewater from chemical incineration flue gas high ammonium salt spraying for simultaneous recovery of magnesium ammonium phosphate and ammonium sulfate according to claim 1, characterized in that: The spray wastewater of the flue gas spray equipment has a water temperature of 80-100° C., a pH of 4-8, a salt content of 10-200 g / L, and an NH 3 -N content of 1000-3000 mg / L.

4. The method for recycling wastewater from chemical incineration flue gas high ammonium salt spraying for simultaneous recovery of magnesium ammonium phosphate and ammonium sulfate according to claim 1, characterized in that: The outflow rate of the spray wastewater of the flue gas spray equipment is controlled at 0.1~0.5m 3 / h.

5. The method for recycling wastewater from chemical incineration flue gas high ammonium salt spraying for simultaneous recovery of magnesium ammonium phosphate and ammonium sulfate according to claim 1, characterized in that: In step S1, the concentration of the NaOH solution is 40%, the flow volume ratio of the NaOH solution to the spray wastewater is 1:300, and the pH of the spray wastewater is 9-9.5; In step S2, the amount of O3 added is 0.1-0.5 g / L of spray wastewater; the filling ratio of quartz sand, alumina balls, and activated carbon in the adsorption filter is 50:100:100, and the single-layer filling thickness is 500 mm; In step S3, Mg 2+ NH4 + , the molar ratio of phosphate addition is 1.2:1:0.8; In step S4, the microporous aeration air volume is 0.1m 3 / L spray wastewater; In step S5, a 5% sulfuric acid solution is added to control the system pH to be less than 3.5, and the concentration of the recovered ammonium sulfate solution to be greater than 15%; In step S6, the evaporation and drying process, the flue gas waste heat temperature is greater than 150°C.

6. A chemical incineration flue gas high ammonium salt spray wastewater resource recovery system for simultaneously recovering magnesium ammonium phosphate and ammonium sulfate, characterized by: The system comprises a flue gas spray device (7), an inclined tube sedimentation tank (1), an adsorption filter (2), a magnesium ammonium phosphate sedimentation tank (3), an aeration leaching tank (4), an acid wash recovery tank (5), and a flue gas waste heat cascade evaporation device (6) connected in sequence by pipelines; The water outlet of the flue gas spraying device (7) is connected to the inlet of the inclined tube sedimentation tank (1), a mud discharge pipeline is provided at the bottom of the inclined tube sedimentation tank (1), and the water outlet of the inclined tube sedimentation tank (1) is connected to the bottom of the adsorption filter (2), so that the incoming wastewater is adsorbed and filtered from bottom to top; The top water outlet pipe of the adsorption filter (2) is connected to the water inlet of the magnesium ammonium phosphate precipitation tank (3); The outlet of the magnesium ammonium phosphate precipitation tank (3) is connected to the circulating elution device of the aeration elution tank (4) so ​​that the incoming wastewater can be eluted in a circulating manner. A microporous aeration device is provided at the bottom of the aeration elution tank (4) so ​​that the wastewater sprayed from above is fully mixed with the air. The gas phase outlet at the top of the aeration and leaching tank (4) is connected to the lower part of the pickling recovery tank (5), and a spraying device for circulating and spraying sulfuric acid solution is provided in the aeration and leaching tank (4); The flue gas waste heat cascade evaporation device (6) includes at least three groups of evaporators connected in series, which are used to allow the flue gas with waste heat to flow through the three groups of evaporators in sequence for heat exchange and gradually reduce the flue gas temperature. The bottom outlet of the aeration and leaching tank (4) is connected to the cold end inlet of the first group of evaporators, the bottom outlet of the pickling recovery tank (5) is connected to the cold end inlet of the second group of evaporators, and the bottom outlet of the magnesium ammonium phosphate precipitation tank (3) is connected to the cold end inlet of the third group of evaporators. The gas phase outlet of the flue gas waste heat cascade evaporation device (6) is connected to the middle part of the flue gas spraying device (7) through a condenser.

7. The chemical incineration flue gas high ammonium salt spray wastewater resource recovery system for simultaneously recovering magnesium ammonium phosphate and ammonium sulfate according to claim 6, characterized in that: The adsorption filter (2) is a porous adsorption material composed of quartz sand, alumina balls and activated carbon, which is filled in layers from bottom to top, and the thickness of a single layer of material is 100mm~500mm.

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