A method and system for simultaneously treating ammonia-containing exhaust gas and ammonia-nitrogen-containing waste liquid containing metal ions

Abstract

The application discloses a method and system for simultaneously treating ammonia-containing waste gas and ammonia-nitrogen waste liquid containing metal ions, and the method comprises the following steps: (1) crystallizing and concentrating the ammonia-nitrogen waste liquid containing metal ions to obtain concentrated waste liquid and ammonia-containing gas phase I; (2) cooling the ammonia-containing gas phase I to obtain ammonia-containing condensate; (3) using the ammonia-containing condensate and optional absorbent as a washing liquid to wash the ammonia-containing waste gas, absorbing ammonia in the ammonia-containing waste gas, and obtaining recovered ammonia liquid and ammonia-containing gas phase II; and (4) using an acid solution to wash the ammonia-containing gas phase II to obtain discharge waste liquid and direct discharge waste gas. The method and system can be used in the comprehensive treatment process of ammonia-containing waste gas and high-concentration ammonia-nitrogen waste liquid containing metal ions in industrial production processes, and have the advantages of low equipment investment, simple treatment device for high-concentration ammonia-nitrogen waste liquid containing metal ions and strong operability of the process flow.

Description

Technical Field

[0001] This invention belongs to the field of waste gas and waste liquid treatment, and particularly relates to the simultaneous treatment of waste gas and waste liquid. Specifically, it relates to a method and system for simultaneously treating ammonia-containing waste gas and ammonia nitrogen-containing waste liquid containing metal ions. Background Technology

[0002] Ammonia nitrogen is one of the major pollutants in water bodies. Large amounts of ammonia nitrogen-containing domestic sewage and industrial wastewater discharged into natural water bodies cause eutrophication, leading to red tides, excessive algal blooms, and seriously threatening ecosystem safety. Therefore, there are strict restrictions on the discharge of ammonia nitrogen wastewater in industry.

[0003] Currently, the treatment of ammonia nitrogen wastewater mainly involves biological and physicochemical methods. Biological methods primarily include nitrification-denitrification; physical methods mainly include reverse osmosis, distillation, and adsorption; and chemical methods mainly include ion exchange, ammonia stripping, chemical precipitation, electrochemical methods, breakpoint chlorination, and wet catalytic oxidation. Air stripping first adjusts the wastewater to alkaline conditions, reducing the NH4+ content. + The process involves converting ions into ammonia molecules, followed by stripping to remove ammonia. However, this method consumes a significant amount of steam and energy, resulting in high operating costs and generating large amounts of ammonia vapor, causing secondary pollution. Ammonia stripping requires substantial steam consumption, necessitates large equipment footprints, and incurs high operating costs, also contributing to secondary pollution. Resin exchange, breakpoint chlorination, and membrane filtration methods are susceptible to interference from other pollutants in the wastewater, leading to poor treatment efficiency and high costs. Chemical precipitation utilizes the reaction of ammonia with phosphates and magnesium oxide to generate sparingly soluble magnesium ammonium phosphate (MgNH4PO4) to remove ammonia nitrogen from wastewater. However, this process requires separate pH adjustment, making it complex and cumbersome, hindering its practical application. Biological methods are currently the primary method for treating low-concentration ammonia nitrogen wastewater, but they are less suitable for wastewater containing heavy metals and high salinity, cannot recover heavy metals and ammonia resources, and require a large land area. These methods all have drawbacks such as high investment, complex operation, and high operating costs. No single solution can efficiently, economically, and stably treat high-concentration ammonia nitrogen wastewater. Some processes introduce secondary pollution while removing ammonia nitrogen.

[0004] Large-scale discharge of wastewater containing metal ions, such as iron, copper, lead, zinc, cadmium, cobalt, and nickel, poses a significant threat to the environment and human health. Common methods for treating wastewater containing metal ions include chemical precipitation, extraction, flotation, adsorption, ion exchange, and electrochemical deposition. Chemical precipitation is the most mature and widely used method. It involves adding specific chemical reagents (such as hydroxides, sulfides, and flocculants) to react with the heavy metal ions in the wastewater, forming precipitates and thus removing them. However, the main drawback of chemical precipitation is the relatively long sedimentation time required in subsequent separation processes, leading to large land areas, high investment costs, and limited separation efficiency.

[0005] In actual industrial production, wastewater often contains not only ammonia nitrogen or metal ions, but both. Examples include wastewater from hydrometallurgy, electroplating, printed circuit boards, electrode materials, rare earth production, and landfill. Although extensive research has been conducted on the treatment of this complex wastewater, satisfactory results have yet to be achieved.

[0006] CN207581556U discloses a negative pressure ammonia stripping and recovery system, comprising a pH adjustment tank, a solid-liquid separation tank, a water tank, an alkali mixer, a preheater, a negative pressure ammonia stripping tower, a vacuum device, a gas-liquid separator, a condenser, an ammonia recovery unit, an ammonia washing recovery unit, and an ammonia chiller connected in sequence. A steam generator is connected to the lower part of the negative pressure ammonia stripping tower. Wastewater passes sequentially through the pH adjustment tank, solid-liquid separation tank, water tank, alkali mixer, preheater, negative pressure ammonia stripping tower, gas-liquid separator, condenser, ammonia recovery unit, ammonia washing recovery unit, and ammonia chiller. The steam generator introduces hot steam into the negative pressure ammonia stripping tower, and the vacuum device creates a vacuum, allowing ammonia gas in the negative pressure ammonia stripping tower to enter the upper part of the tower and then the condenser. The combination of the ammonia recovery unit and the vacuum device achieves an ammonia recovery rate of up to 98%. The required concentration and purity of ammonia water can be recovered simply by controlling the influent flow rate of the ammonia washing recovery unit.

[0007] CN101624248A discloses a method for treating wastewater from lithium nickel cobalt manganese oxide production, comprising the following steps: adding an alkaline solution to the wastewater containing nickel, cobalt, manganese metal ions, ammonia ions, and solid particles to raise the pH value to >12.5, so that the nickel, cobalt, and manganese metal ions in the wastewater are completely precipitated; passing the wastewater through a settling tank to allow the solid particles in the wastewater to settle; passing the wastewater through an ammonia evaporator to remove ammonia ions from the wastewater; passing the wastewater through a sand bed to filter out a small amount of precipitate; passing the wastewater through a pH adjustment tank, injecting an acidic solution into the tank to lower the pH value to between 6 and 9; and passing the wastewater through a three-stage RO membrane, with the purified water after filtration by the three-stage RO membrane being returned to the production cycle for reuse.

[0008] CN102068880A discloses a method for recovering and utilizing ammonia from industrial waste gas, relating to the treatment of industrial waste gas. The recovery and utilization device includes an absorbent tank, a water pump, a refrigeration unit, a membrane absorption module, an induced draft fan, and a tail gas absorption acid tank. An absorbent is injected into the absorbent tank. The absorbent in the absorbent tank is drawn out by the water pump, passes through the refrigeration unit, and enters the membrane absorption module through the absorbent inlet. Ammonia-containing industrial waste gas is pumped into the membrane absorption module by the induced draft fan. The absorbent absorbs the ammonia from the ammonia-containing industrial waste gas, becoming absorbent liquid. The absorbent liquid flows back to the absorbent tank through the absorbent outlet of the membrane absorption module, re-entering the absorbent circulation process. After absorption, the ammonia-containing industrial waste gas is transformed into ultra-low ammonia-containing waste gas, which is discharged from below the membrane absorption module and connected to the tail gas absorption acid tank. After passing through the absorption acid tank, the ultra-low ammonia-containing waste gas becomes ammonia-free waste gas and is directly discharged into the atmosphere. The absorbent liquid is recycled and drawn out as a finished product. The absorbent is then reinjected into the absorbent tank, and the above steps are repeated.

[0009] As mentioned above, it can be seen that existing technologies all have disadvantages such as large equipment investment, long process flow, complex operation, and high operating costs. Some processes also generate ammonia nitrogen waste gas while removing ammonia nitrogen, resulting in secondary pollution. However, there are no reports on comprehensive treatment methods for ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions. Summary of the Invention

[0010] To overcome the problems existing in the prior art, the present invention provides a method and system for simultaneously treating ammonia-containing waste gas and (high-concentration) ammonia nitrogen waste liquid containing metal ions. It can be used in the comprehensive treatment of ammonia-containing waste gas and high-concentration ammonia nitrogen waste liquid containing metal ions in industrial production processes. It has the advantages of low equipment investment, simple treatment device for high ammonia nitrogen waste liquid containing metal ions, strong operability of process flow, high ammonia recovery rate and treatment efficiency in ammonia-containing waste gas, and the ability to realize resource recycling and zero ammonia emission in waste gas. It is very easy to realize industrial production.

[0011] One objective of this invention is to provide a method for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions, comprising:

[0012] (1) Crystallize and concentrate the ammonia waste liquid containing metal ions to obtain concentrated waste liquid and ammonia gas phase I;

[0013] The ammonia nitrogen waste liquid containing metal ions is a high-concentration alkali metal salt waste liquid, wherein the ammonia nitrogen content is 0.1wt%~5wt%, preferably 0.2wt%~1.5wt%.

[0014] (2) Cooling the ammonia-containing gas phase I to obtain an ammonia-containing condensate;

[0015] The ammonia-containing condensate has a low concentration, making it a low-concentration ammonia condensate that can be used as an absorbent to absorb ammonia gas.

[0016] (3) The ammonia-containing condensate and the optional absorbent are used as washing liquid to wash the ammonia-containing waste gas, absorb the ammonia in the ammonia-containing waste gas, and obtain a recovered ammonia liquid and ammonia-containing gas phase II;

[0017] The absorbent is used as a supplementary or backup liquid, and it is preferable to add the absorbent to ensure the absorption effect, especially when the concentration of ammonia-containing condensate is abnormal, such as being too high. This is because if the absorbent is not added, the ammonia content in the ammonia-containing gas phase II will be too high, and the efficient recovery and utilization of ammonia in the gas phase I will not be achieved.

[0018] In step (3), ammonia gas in ammonia-containing waste gas is fully absorbed by a low-concentration ammonia-containing condensate and an optional absorbent to obtain nitrogen-rich recovered ammonia liquid (which can be recycled) and (low-concentration) ammonia-containing gas phase II; preferably, the ammonia concentration in the ammonia-containing condensate is 0.05wt%~5wt%, more preferably 0.2wt%~1.4wt%.

[0019] (4) The ammonia-containing gas phase II is washed with an acid solution to obtain the discharged waste liquid and the direct discharge waste gas;

[0020] In step (4), an acid solution is used to treat the ammonia gas in the low-concentration ammonia-containing gas phase II to form ammonium salt, which is then treated as an external waste liquid (which can be used as ammonium fertilizer, etc.). The direct discharge waste gas does not contain ammonia and meets the standard for direct discharge.

[0021] In a preferred embodiment, the metal ions include heavy metal ions and / or alkali metal ions. Preferably, the heavy metal ions include at least one of Ni, Zn, Co, Pb, Zn, Mn, etc., and / or the alkali metal ions include at least one of Li, Na, K.

[0022] In a further preferred embodiment, in the ammonia nitrogen waste liquid containing metal ions, the total content of heavy metal ions is 0.001wt%~0.3wt%, preferably 0.005wt%~0.1wt%; and / or, the total content of alkali metal ions is 1wt%~30wt%, preferably 5wt%~20wt%.

[0023] For example, in the concentrated ammonia nitrogen waste liquid containing metal ions, the total content of heavy metal ions is 0.001wt%, 0.005wt%, 0.01wt%, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, or 0.3wt%, and the total content of alkali metal ions is 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, or 30wt%.

[0024] In a preferred embodiment, the pH of the ammonia nitrogen waste liquid containing metal ions is >7.0.

[0025] In this invention, preferably, the ammonia nitrogen waste liquid containing metal ions originates from the production process of ternary cathode materials for lithium-ion batteries.

[0026] In a preferred embodiment, the crystallization concentration process is carried out by heating and evaporating the solvent.

[0027] In a further preferred embodiment, the crystallization concentration process is carried out by evaporating the solvent at 100-150°C, preferably 105-130°C. Preferably, the heating is stopped when the volume of the ammonia nitrogen waste liquid drops to 10-30%, preferably 15-25%, and then the temperature is lowered to 20-50°C, preferably 25-35°C.

[0028] In this process, the solvent is partially evaporated to allow crystallization, which results in the metal ions crystallizing out as salts and being discharged as waste slurry.

[0029] In a preferred embodiment, in step (1), when the solid content in the concentrated waste liquid reaches 55~95wt%, preferably 80~90wt%, the concentrated waste liquid is discharged.

[0030] The above range is controlled based on the solubility of alkali metal salts (25-40℃, solubility in the range of 20-35g / 100g). Specifically, when the solid content is too high, the discharge is difficult; when the solid content is too low, the amount of waste slurry is too large.

[0031] In a preferred embodiment, the crystallization concentration process is carried out in a crystallization tank.

[0032] Preferably, the crystallization tank is operated under normal or negative pressure, with negative pressure operation being preferred.

[0033] In a further preferred embodiment, the crystallization tank is provided with a stirring component and a heating component.

[0034] In a further preferred embodiment, the heating element is at least one of a jacket, an inner coil, and an external circulation heat exchanger, preferably a jacket and / or an inner coil, such as a combination of a jacket and an inner coil.

[0035] For example, the crystallization concentration process is carried out in a crystallization tank, which is equipped with a jacket and / or an inner coil. (1) The ammonia nitrogen waste liquid containing metal ions is sent into the crystallization tank and stirred; (2) Low-pressure steam is introduced into the jacket and the inner coil to control the temperature in the crystallization tank at 100~150℃, preferably 105~130℃, to heat and evaporate the solvent; (3) Heating is stopped when the liquid level in the crystallization tank drops to 10~30%, preferably 15-25%; (4) Circulating cooling water is introduced into the jacket and the inner coil to cool down the temperature in the tank to 20~50℃, preferably 25~35℃; (5) When multiple batches and / or continuous evaporation and concentration are carried out to a certain solid content, stirring is stopped and the material is discharged.

[0036] In this invention, when treating high-ammonia-nitrogen wastewater containing metal ions, the conventional method is to first adjust the solution to a high alkalinity to ensure complete precipitation of the metal ions before treating the ammonia nitrogen. However, under high alkalinity conditions, metal cations readily form stable complexes with ammonia nitrogen, thereby reducing the removal rates of both metal cations and ammonia nitrogen. Furthermore, while a high alkalinity solution can precipitate metal cations, ammonia nitrogen transforms into free ammonia in high alkalinity, which then precipitates from the liquid phase, leading to a significant escape of ammonia gas. Adjusting the solution to a lower alkalinity, however, is not conducive to the complete precipitation of metal cations.

[0037] Therefore, this invention employs heating components (such as a combination of a jacket and an inner coil) to heat the waste liquid. On the one hand, by directly concentrating the crystallized ammonia nitrogen waste liquid, water and free ammonia are gradually evaporated, increasing the alkalinity of the waste liquid. On the other hand, by heating at high temperature, the complex formed between metal cations and ammonia nitrogen is destroyed, causing the ammonia nitrogen in the ammonia nitrogen complex to become free ammonia, which is then evaporated from the waste liquid system along with water. This results in the concentrated waste liquid having an ammonia nitrogen content that meets emission standards.

[0038] In a preferred embodiment, in step (2), the temperature is lowered to 20~50°C, preferably to 30~40°C.

[0039] In a preferred embodiment, in step (3), the ammonia concentration in the ammonia-containing waste gas is 1wt% to 60wt%, preferably 15wt% to 55wt%, for example, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt% or 60wt%.

[0040] In this invention, preferably, the ammonia-containing waste gas originates from the production process of ternary cathode materials for lithium-ion batteries.

[0041] In a preferred embodiment, in step (3), the absorbent is water.

[0042] In a preferred embodiment, the washing in step (3) is performed at room temperature.

[0043] In a further preferred embodiment, in step (3), the ammonia concentration in the washing liquid at room temperature is controlled to be ≤10wt%, preferably ≤5wt%.

[0044] In a further preferred embodiment, in step (3), the ammonia content in the ammonia-containing gas phase II is controlled to be less than 4 wt%, preferably less than 3.5 wt%.

[0045] When the ammonia concentration is higher than the above range, the absorbent is introduced, and the amount of absorbent added is controlled by the ammonia concentration. Specifically, when the ammonia concentration in the washing liquid is too high, the absorption effect deteriorates, and the ammonia concentration in the ammonia-containing gas phase II increases. In this case, the amount of absorbent (pure water) supplied should be increased, and the discharge rate should be increased simultaneously.

[0046] In a further preferred embodiment, in step (3), the ammonia-containing waste gas enters the liquid phase of step (3) in the form of bubbling.

[0047] Bubbling can further promote the contact between ammonia gas and the liquid phase in ammonia-containing waste gas, thereby promoting the absorption of ammonia gas.

[0048] In a preferred embodiment, in step (3), the mass ratio of the washing liquid to the ammonia-containing waste gas is greater than 20:1, preferably greater than 30:1.

[0049] In a preferred embodiment, in step (4), the acid solution is selected from at least one of sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid.

[0050] In a preferred embodiment, in step (4), the pH value of the acid solution is <7.0, preferably 1.0~6.0, and more preferably 2.0~5.0.

[0051] In a preferred embodiment, the washing in step (4) is performed at 15°C to 30°C, preferably at room temperature.

[0052] In a preferred embodiment, the washing in step (4) is carried out in a washing tower.

[0053] In a further preferred embodiment, in step (4), the washing tower uses an acid solution for circulating absorption (or washing).

[0054] In a preferred embodiment, in step (4), the washing tower discharges material intermittently and discharges waste liquid.

[0055] In a further preferred embodiment, in step (4), the pH value of the bottom of the washing tower is monitored in real time. When the pH value of the bottom liquid is 6.5~7.0, the bottom liquid is discharged intermittently and fresh acid solution is added to ensure that the ammonia concentration in the direct discharge waste gas stream meets the emission standards.

[0056] In this invention, the ammonia nitrogen waste gas formed during the concentration and crystallization process is cooled and washed in two stages to recover ammonia from the waste gas: on the one hand, it realizes the efficient recovery and utilization of ammonia resources, and the recovered ammonia liquid can be returned to the upstream unit as a reaction raw material, such as the production of ternary cathode materials for lithium-ion batteries; on the other hand, it reduces the ammonia content in the waste gas and achieves zero emission of ammonia from the waste gas.

[0057] The second objective of this invention is to provide a system for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions, preferably for carrying out the method described in the first objective of this invention, wherein the system includes a crystallization concentration unit, a cooling unit, a primary washing unit, and a secondary washing unit connected in sequence.

[0058] In a preferred embodiment, the crystallization concentration unit is a crystallization tank.

[0059] In a further preferred embodiment, the crystallization tank is provided with a stirring component and a heating component.

[0060] In a further preferred embodiment, the heating element is at least one of a jacket, an inner coil, and an external circulation heat exchanger, preferably a jacket and / or an inner coil, such as a combination of a jacket and an inner coil.

[0061] In a preferred embodiment, the cooling unit is a heat exchange device.

[0062] In a preferred embodiment, the primary washing unit is provided with an ammonia-containing condensate inlet, an ammonia-containing waste gas inlet, a recovered ammonia liquid outlet, and an ammonia-containing gas phase II outlet.

[0063] In a further preferred embodiment, the ammonia-containing condensate inlet is connected to the cooling unit, and / or the ammonia-containing waste gas inlet is located below the liquid level of the primary scrubbing unit, and / or the ammonia-containing gas phase II outlet is connected to the secondary scrubbing unit.

[0064] The ammonia-containing waste gas enters the primary scrubbing unit in the form of bubbles, and the bubbles can further promote the contact between the ammonia gas and the liquid phase in the ammonia-containing waste gas, thus promoting the absorption of ammonia gas.

[0065] In a further preferred embodiment, an online ammonia detector is installed at the outlet of the ammonia-containing gas phase II.

[0066] In a preferred embodiment, the primary washing unit is a primary washer.

[0067] In a preferred embodiment, the secondary washing unit is provided with an ammonia-containing gas phase II inlet, an acid solution inlet, an external waste liquid outlet, and a direct waste gas outlet.

[0068] In a further preferred embodiment, the ammonia-containing gas phase II inlet is connected to the ammonia-containing gas phase II outlet of the primary washing unit.

[0069] In a further preferred embodiment, an online ammonia detector is installed at the direct exhaust gas outlet.

[0070] In a preferred embodiment, the secondary washing unit is a secondary washing tower, preferably a packed tower or a plate tower.

[0071] In a preferred embodiment, an acid solution inlet is provided in the middle, upper middle or top of the secondary scrubbing tower, an ammonia-containing gas phase II inlet is provided at the bottom or lower part of the secondary scrubbing tower, an external waste liquid outlet is provided at the bottom of the secondary scrubbing tower, and a direct exhaust gas outlet is provided at the top of the secondary scrubbing tower.

[0072] In a further preferred embodiment, an online pH meter is installed in the bottom of the secondary scrubbing tower.

[0073] The pH value of the acid solution in the bottom of the secondary scrubbing tower is monitored in real time by an online pH meter. When the pH value of the bottom liquid approaches 7.0 (preferably 6.5~7.0), the bottom liquid is intermittently discharged and fresh acid solution is added to ensure that the ammonia concentration in the direct discharge exhaust gas meets the emission standards. The bottom liquid intermittently discharged from the secondary scrubbing tower is a high-concentration ammonium-containing solution, which can be recycled as ammonium fertilizer.

[0074] In a preferred embodiment, the system further includes a waste liquid collection tank, preferably connected to the feed inlet of the crystallization unit.

[0075] In a further preferred embodiment, the waste liquid collection tank may be one or more, for example, two.

[0076] In this invention, the (high-concentration) ammonia nitrogen waste liquid containing metal ions from upstream is first sent to a waste liquid collection tank, and then continuously sent to a crystallization tank for concentration and crystallization. The concentrated liquid from the crystallization tank is discharged and centrally treated. The gaseous components are cooled by a heat exchange device and then sent to a primary scrubber to recover the ammonia liquid. The (high-concentration) ammonia-containing waste gas from upstream is sent to the primary scrubber by bubbling to wash and recover the ammonia liquid. The recovered ammonia liquid can be returned to the upstream unit as a reaction raw material. The waste gas after being washed by the primary scrubber is washed again by a secondary scrubbing tower. The waste gas that passes the washing test is directly discharged at high altitude.

[0077] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0078] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0079] Compared with the prior art, the present invention has the following beneficial effects:

[0080] (1) The method and system described in this invention can simultaneously treat ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions;

[0081] (2) The method and system described in this invention have the advantages of low equipment investment, simple treatment device for high ammonia nitrogen waste liquid containing metal ions, strong operability of process flow, high ammonia recovery rate and treatment efficiency in ammonia waste gas, and the ability to realize resource recycling and zero ammonia emission in waste gas, making it very easy to realize industrial production. Attached Figure Description

[0082] Figure 1 A schematic diagram of one embodiment of the system described in this invention is shown.

[0083] A - Waste liquid collection tank; B - Crystallization and concentration unit; C - Cooling unit; D - Primary washing unit; E - Secondary washing unit; S1 - (High concentration) ammonia nitrogen waste liquid containing metal ions; S2 - Crystallization and concentration unit; S3 - Ammonia gas phase I; S4 - Concentrated waste liquid; S5 - Ammonia condensate; S6 - Ammonia waste gas; S7 - Ammonia gas phase II; S8 - Recovered ammonia liquid; S9 - Absorbent (e.g., water); S10 - Acid solution; S11 - Waste liquid discharged externally; S12 - Direct waste gas discharge.

[0084] Figure 1In this process, high-concentration ammonia nitrogen wastewater S1 from upstream, containing metal ions, is first fed into wastewater collection tank A, and then continuously fed into a crystallization and concentration unit (e.g., a crystallization tank) B. Stirring is initiated, and the wastewater is heated and concentrated for crystallization. Once the solid content of the concentrated wastewater S4 in the crystallization and concentration unit reaches a certain value, it is discharged for centralized treatment. The ammonia-containing gas phase I S3 from the crystallization and concentration unit is condensed by a cooling unit (e.g., a heat exchanger) to obtain ammonia-containing condensate S5. Ammonia-containing condensate S5 is sent to a primary scrubbing unit D, where it is mixed with an absorbent (e.g., fresh pure water) S9 to serve as the ammonia absorbent for ammonia-containing waste gas S6. The high-concentration ammonia-containing waste gas S6 from upstream is fed into the primary scrubbing unit via bubbling to recover ammonia through scrubbing. An ammonia detector at the gas phase outlet of the primary scrubbing unit measures the ammonia concentration in the ammonia-containing gas phase II S7, thereby controlling the ammonia concentration in the scrubbing liquid of the primary scrubbing unit to achieve efficient ammonia recovery from the waste gas. The recovered ammonia liquid S8 can be returned to the upstream unit as a reaction feedstock. After being washed by the primary washing unit, the ammonia-containing gas phase IIS7 is then washed by the secondary washing unit with acid solution S10. The qualified exhaust gas S12 is then directly discharged at high altitude. Detailed Implementation

[0085] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0086] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0087] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0088] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0089]

Example 1

[0090] By weight percentage, the (high-concentration) ammonia nitrogen wastewater S1 containing metal ions has a heavy metal ion content of 0.01 wt%, an alkali metal ion content of 10 wt%, and a pH value of 11.2.

[0091] like Figure 1 As shown, the (high-concentration) ammonia nitrogen waste liquid S1 from upstream containing metal ions is first sent to a waste liquid collection tank, and then continuously sent to a crystallization tank. Stirring is started, and the liquid is heated and concentrated at 110℃ for crystallization. When the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 90%, it is discharged for centralized treatment. The ammonia nitrogen content in the concentrated waste liquid S4 is <20ppm. The ammonia-containing gas phase IS3 in the crystallization tank is cooled to 40℃ by a heat exchanger to obtain ammonia-containing condensate S5. The ammonia-containing condensate S5 is sent to a primary scrubber and optionally mixed with fresh pure water S9 to serve as the ammonia absorbent for ammonia-containing waste gas S6.

[0092] High-concentration ammonia-containing waste gas S6 from upstream is fed into a primary scrubber via bubbling to recover ammonia. The ratio of scrubbing liquid to ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in waste gas S6 is 20 wt%, and the ammonia concentration in the ammonia-containing condensate S5 fed into the primary scrubber is 0.5 wt%. At room temperature, the ammonia concentration in the scrubbing liquid is 0.5 wt% (at this point, the ammonia-containing condensate S5 is the scrubbing liquid). An ammonia detector installed at the outlet of ammonia-containing gas phase II (S7) of the primary scrubber detects the ammonia concentration in gas phase II, thereby controlling the ammonia concentration in the scrubbing liquid of the primary scrubber to achieve efficient ammonia recovery from the waste gas. The ammonia concentration in gas phase II is 0.32 wt%, eliminating the need for absorbent pure water; the feed rate of fresh pure water S9 is 0 kg / h. The recovered ammonia liquid S8 can be returned to the upstream unit as a reaction feedstock.

[0093] The ammonia-containing gas phase IIS7, after being washed by the primary scrubber, is then subjected to a secondary scrubber with a circulating acid solution S10 (specifically, sulfuric acid solution, pH 3) at room temperature. The qualified exhaust gas S12 is then directly discharged at high altitude. An online pH meter installed at the bottom of the secondary scrubber monitors the pH value of the acid solution in real time. When the pH value of the bottom liquid approaches 7.0, waste liquid S11 is intermittently discharged, and fresh acid solution S10 is added to ensure that the ammonia concentration in the exhaust gas S12 meets emission standards. The intermittently discharged waste liquid S11 (bottom liquid) from the secondary scrubber is a high-concentration ammonium-containing waste liquid, which can be recycled as ammonium fertilizer.

[0094] In this Example 1, the ammonia absorption rate of the primary scrubber is 98.68 wt%, the ammonia concentration in the ammonia-containing gas phase II is 0.32 wt%, and the ammonia content in the direct exhaust gas S12 is <30 ppm.

[0095]

Example 2

[0096] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0097] The mass ratio of washing liquid to ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in ammonia-containing waste gas S6 is 40wt%. The ammonia concentration in the ammonia-containing condensate feed of the primary scrubber is 0.5wt%. The ammonia concentration in the washing liquid at room temperature is 0.5wt%. The feed rate of fresh pure water S9 is 0kg / h. The ammonia absorption rate of the primary scrubber is 99.25wt%. The ammonia concentration in ammonia-containing gas phase II is 0.49wt%. The ammonia content in the direct discharge waste gas S12 is <30ppm.

[0098]

Example 3

[0099] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0100] The total feed rate of the washing liquid to the ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in the ammonia-containing waste gas S6 is 50wt%. The ammonia concentration in the feed of the ammonia-containing condensate in the primary scrubber is 0.5wt%. The ammonia concentration in the washing liquid at room temperature is 0.5wt%. The feed rate of fresh pure water S9 is 0kg / h. The ammonia absorption rate of the primary scrubber is 99.42wt%. The ammonia concentration in the ammonia-containing gas phase II is 0.57wt%. The ammonia content in the direct discharge waste gas S12 is <30ppm.

[0101]

Example 4

[0102] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0103] The total feed rate of the washing liquid to the ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in the ammonia-containing waste gas S6 is 60wt%. The ammonia concentration in the feed of the ammonia-containing condensate in the primary scrubber is 0.5wt%. The ammonia concentration in the washing liquid at room temperature is 0.5wt%. The feed rate of fresh pure water S9 is 0kg / h. The ammonia absorption rate of the primary scrubber is 99.55wt%. The ammonia concentration in the ammonia-containing gas phase II is 0.66wt%. The ammonia content in the direct discharge waste gas S12 is <30ppm.

[0104]

Example 5

[0105] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0106] The (high-concentration) ammonia nitrogen waste liquid S1 from upstream containing metal ions is first sent to the waste liquid collection tank, and then continuously sent to the crystallization tank. Stirring is started, and the liquid is heated and concentrated at 110°C. When the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 60%, it is discharged for centralized treatment. The ammonia nitrogen content in the concentrated waste liquid S4 is <20ppm.

[0107] The total feed rate of the washing liquid to the ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in the ammonia-containing waste gas S6 is 20wt%, the ammonia concentration in the feed of the ammonia-containing condensate in the primary scrubber is 5wt%, and the ammonia concentration in the washing liquid at room temperature is 5wt%. Therefore, the feed rate of fresh pure water S9 is 0kg / h, the ammonia absorption rate of the primary scrubber is 87.39wt%, the ammonia concentration in the ammonia-containing gas phase II is 3.0wt%, and the ammonia content in the direct discharge waste gas S12 is <30ppm.

[0108]

Example 6

[0109] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0110] The (high-concentration) ammonia nitrogen waste liquid S1 from upstream containing metal ions is first sent to the waste liquid collection tank, and then continuously sent to the crystallization tank. Stirring is started, and the liquid is heated and concentrated at 110°C. When the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 60%, it is discharged for centralized treatment. The ammonia nitrogen content in the concentrated waste liquid S4 is <20ppm.

[0111] The total feed rate of the washing liquid to the ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in the ammonia-containing waste gas S6 is 50wt%, the ammonia concentration in the feed of the ammonia-containing condensate in the primary scrubber is 5wt%, and the ammonia concentration in the washing liquid at room temperature is 5wt%. Therefore, the ammonia absorption rate of the primary scrubber is 96.3wt%, the ammonia concentration in the ammonia-containing gas phase II is 3.51wt%, and the ammonia content in the direct exhaust gas S12 is <30ppm.

[0112]

Example 7

[0113] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0114] The (high-concentration) ammonia nitrogen waste liquid S1 from upstream containing metal ions is first sent to the waste liquid collection tank, and then continuously sent to the crystallization tank. Stirring is started, and the liquid is heated and concentrated at 110°C. When the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 60%, it is discharged for centralized treatment. The ammonia nitrogen content in the concentrated waste liquid S4 is <20ppm.

[0115] The total feed rate of the primary scrubber washing liquid to the mass ratio of ammonia-containing waste gas is 100:1. The ammonia concentration in ammonia-containing waste gas S6 is 20wt%, the ammonia concentration in the feed of the primary scrubber ammonia-containing condensate is 5wt%, the ammonia concentration in the washing liquid at room temperature is 5wt%, the feed rate of fresh pure water S9 is 0kg / h, the ammonia absorption rate of the primary scrubber is 88wt%, the ammonia concentration in ammonia-containing gas phase II is 2.86wt%, and the ammonia content in the direct discharge waste gas S12 is <30ppm.

[0116]

Example 8

[0117] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0118] The (high-concentration) ammonia nitrogen waste liquid S1 from upstream containing metal ions is first sent to the waste liquid collection tank, and then continuously sent to the crystallization tank. Stirring is started, and the mixture is heated and concentrated at 110°C. When the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 86.5%, it is discharged for centralized treatment. The ammonia nitrogen content in the concentrated waste liquid S4 is <20ppm.

[0119] The ratio of the total feed rate of the washing liquid to the mass of the ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in the ammonia-containing waste gas S6 is 20wt%. The ratio of the feed rate of the ammonia-containing condensate to the mass of the ammonia-containing waste gas in the primary scrubber is 25:1. The ammonia concentration in the feed of the ammonia-containing condensate is 1wt%. The ratio of the feed rate of fresh pure water S9 to the mass of the ammonia-containing waste gas is 25:1. The ammonia concentration in the washing liquid at room temperature is 0.5wt%. That is, if fresh pure water is used as the absorbent, the ammonia absorption rate of the primary scrubber is 98.69wt%. The ammonia concentration in the ammonia-containing gas phase II is 0.31wt%. The ammonia content in the direct exhaust gas S12 is <30ppm.

[0120]

Comparative Example 1

[0121] The implementation method is the same as in Example 1, with other conditions remaining unchanged. The difference is that a primary water washing unit is provided, but a secondary acid washing unit is not provided. When the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 90%, it is discharged for centralized treatment, and the ammonia nitrogen content in the concentrated waste liquid S4 is <20ppm.

[0122] The total feed rate of the washing liquid to the mass ratio of ammonia-containing waste gas in the primary scrubber is 50:1. The ammonia concentration in the ammonia-containing waste gas S6 is 20wt%, the ammonia concentration in the feed of the ammonia-containing condensate in the primary scrubber is 0.5wt%, and the ammonia concentration in the washing liquid at room temperature is 0.5wt%. Therefore, the ammonia absorption rate of the primary scrubber is 98.67wt%, the ammonia concentration in the ammonia-containing gas phase II is 3.01wt%, and the direct discharge waste gas S12 does not meet the direct discharge standard.

[0123] [Comparative Example 2]

[0124] The implementation method is the same as in Example 1, except that when the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 50% (when the solid content is low, the ammonia concentration in the ammonia-containing condensate is high and the amount of condensate is reduced), it is discharged and centrally treated, and the ammonia nitrogen content in the concentrated waste liquid S4 is <1000ppm.

[0125] The total feed rate of the primary scrubber washing liquid to the mass ratio of ammonia-containing waste gas is 50:1. The ammonia concentration in ammonia-containing waste gas S6 is 20wt%, the ammonia concentration in the feed of the primary scrubber ammonia-containing condensate is 10wt%, the ammonia concentration in the washing liquid at room temperature is 10wt%, and the feed rate of fresh pure water S9 is 0wt%. Therefore, the ammonia absorption rate of the primary scrubber is 60.3wt%, the ammonia concentration in ammonia-containing gas phase II is 8.87wt%, and the ammonia content in the direct discharge waste gas S12 is <30ppm.

[0126] However, the ammonia recovery efficiency in the primary scrubber decreases, the acid solution circulation cycle in the secondary scrubber becomes shorter, the acid consumption increases, and the amount of waste liquid discharged increases.

[0127] [Comparative Example 3]

[0128] The implementation method is the same as in Example 1, with other conditions remaining unchanged, except that:

[0129] The (high-concentration) ammonia nitrogen waste liquid S1 from upstream containing metal ions is first sent to the waste liquid collection tank, and then continuously sent to the crystallization tank. Stirring is started, and the liquid is heated and concentrated at 110°C. When the solid content of the concentrated waste liquid S4 in the crystallization tank reaches 60%, it is discharged for centralized treatment. The ammonia nitrogen content in the concentrated waste liquid S4 is <20ppm.

[0130] The total feed rate of the primary scrubber washing liquid to the mass ratio of ammonia-containing waste gas is 10:1. The ammonia concentration in ammonia-containing waste gas S6 is 20wt%, the ammonia concentration in the primary scrubber ammonia-containing condensate feed is 5wt%, the ammonia concentration in the washing liquid at room temperature is 5wt%, and the feed rate of fresh pure water S9 is 0wt%. Therefore, the ammonia absorption rate of the primary scrubber is 82.44wt%, the ammonia concentration in ammonia-containing gas phase II is 4.13wt%, and the ammonia content in the direct discharge waste gas S12 is <30ppm.

[0131] However, the ammonia recovery efficiency in the primary scrubber decreases, the acid solution circulation cycle in the secondary scrubber becomes shorter, the acid consumption increases, and the amount of waste liquid discharged increases.

[0132] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions, comprising: (1) Crystallize and concentrate the ammonia nitrogen waste liquid containing metal ions to obtain concentrated waste liquid and ammonia gas phase I; The crystallization and concentration process is carried out by evaporating the solvent at 100-150°C in a crystallization tank equipped with a stirring and heating components. When the solid content in the concentrated waste liquid reaches 80-95 wt%, the concentrated waste liquid is discharged. (2) Cool the ammonia-containing gas phase I to 20~50℃ to obtain an ammonia-containing condensate; (3) The ammonia-containing condensate and optional absorbent are used as washing liquid to wash the ammonia-containing waste gas, absorb the ammonia in the ammonia-containing waste gas, and obtain a recovered ammonia liquid and ammonia-containing gas phase II; the ammonia-containing waste gas enters the liquid phase of step (3) in the form of bubbling; (4) The ammonia-containing gas phase II is washed with an acid solution to obtain the external waste liquid and the direct waste gas.

2. The method for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions according to claim 1, characterized in that, The metal ions include heavy metal ions and / or alkali metal ions.

3. The method according to claim 2, characterized in that, The heavy metal ions include at least one of Ni, Zn, Co, Pb, Zn, and Mn, and / or the alkali metal ions include at least one of Li, Na, and K.

4. The method for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions according to claim 2, characterized in that, In the ammonia nitrogen waste liquid containing metal ions, the total content of heavy metal ions is 0.001wt%~0.3wt%, and / or the total content of alkali metal ions is 1wt%~30wt%.

5. The method for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions according to claim 1, characterized in that, In step (3), The ammonia concentration in the ammonia-containing waste gas is 1wt%~60wt%; and / or, The absorbent is water; and / or, The ammonia concentration in the washing solution should be controlled to be ≤10wt% at room temperature.

6. The method for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions according to claim 1, characterized in that, In step (3), The mass ratio of the washing liquid to the ammonia-containing waste gas is greater than 20:

1.

7. The method for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions according to any one of claims 1 to 6, characterized in that, In step (4), The acid solution is selected from at least one of sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid; and / or, The pH value of the acid solution is <7.0; and / or, The washing is carried out at 15℃~30℃.

8. A system for simultaneously treating ammonia-containing waste gas and ammonia nitrogen waste liquid containing metal ions, used for carrying out the method described in any one of claims 1 to 7, wherein, The system includes a crystallization concentration unit, a cooling unit, a primary washing unit, and a secondary washing unit connected in sequence. The crystallization concentration unit is a crystallization tank, which is equipped with a stirring component and a heating component. The primary washing unit is equipped with an ammonia-containing condensate inlet, an ammonia-containing waste gas inlet, a recovered ammonia liquid outlet, and an ammonia-containing gas phase II outlet. The ammonia-containing condensate inlet is connected to the cooling unit, the ammonia-containing waste gas inlet is located below the liquid surface of the primary washing unit, and the ammonia-containing gas phase II outlet is connected to the secondary washing unit. The secondary washing unit is equipped with an ammonia-containing gas phase II inlet, an acid solution inlet, an external waste liquid outlet, and a direct waste gas outlet.

9. The system according to claim 8, characterized in that, The cooling unit is a heat exchange device.

10. The system according to claim 8, characterized in that, The secondary washing unit is a secondary washing tower. The acid solution inlet is provided in the middle, upper middle or top of the secondary washing tower. The ammonia-containing gas phase II inlet is provided at the bottom or lower part of the secondary washing tower. The bottom of the secondary washing tower is provided with an external waste liquid outlet. The top of the secondary washing tower is provided with a direct exhaust gas outlet.

11. The system according to any one of claims 8 to 10, characterized in that, The system further includes a waste liquid collection tank.

12. The system according to claim 11, characterized in that, The waste liquid collection tank is connected to the feed inlet of the crystallization unit.

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