Ammonia recovery system in harmless treatment of aluminum ash
By designing an ammonia recovery system during the aluminum ash recycling process, and using the combined technology of a gas-liquid separator and an ammonia absorption tower, the problem of the inability to effectively recover harmful components of ammonia gas is solved, the output and recycling efficiency of ammonia water products are improved, and the treatment cost and resource waste are reduced.
Patent Information
- Application Number
- CN202421530954.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-01
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2034-07-01
AI Technical Summary
During the aluminum ash recycling process, harmful components such as ammonia cannot be effectively recycled, resulting in increased aluminum ash treatment costs and waste of resources.
An ammonia recovery system is designed for harmless treatment of aluminum ash. By continuously extracting ammonia water at the bottom of the gas-liquid separator and using low-temperature frozen water as an absorber in the ammonia absorption tower, the recovery efficiency of ammonia gas is improved.
The production of ammonia water finished products is improved, the ammonia content in the tail gas at the top of the ammonia absorption tower is reduced, the circulating enrichment of harmful components in aluminum ash is avoided, and the amount of absorbents and operating costs are reduced.
Smart Images
Figure CN222766295U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of aluminum ash treatment, and in particular relates to an ammonia recovery system in the harmless treatment of aluminum ash. Background Art
[0002] Aluminum ash is divided into primary aluminum ash and secondary aluminum ash. The slag that is not soluble in aluminum liquid during the production or reprocessing of primary aluminum is called primary aluminum ash; the ash produced during the recovery of primary aluminum ash is called secondary aluminum ash. The main components of aluminum ash are metallic aluminum and its oxides, aluminum nitride (AlN), fluorides (such as NaF, KF, MgF 2 、Na 3 AlF 6 and LiF), chlorides (such as KCl, NaCl, and MgCl 2 ), etc., and have high recycling value.
[0003] like Figure 1 In the recycling process of aluminum ash shown in the figure, after the metal aluminum is screened, the remaining aluminum ash needs to react with water to remove ammonia and other harmful substances. After the water and aluminum ash are mixed in the batching tank, they enter the reaction tank. The high-temperature mixed gas generated by the water and aluminum ash in the reaction tank contains ammonia, methane, hydrogen, hydrogen sulfide and other components, and also contains a large amount of water vapor. The high-temperature mixed gas is cooled by the gas-liquid separator and sent to the ammonia absorption tower. The slurry at the bottom of the reaction tank is filtered by a vacuum belt filter to obtain concentrated brine, light brine and ash. The light brine goes to the light brine tank, and the ash is dried. The concentrated brine is precipitated in the concentrated brine precipitation tank to obtain pure brine, and then enters the MVR evaporator. After crystallization and centrifugation, the composite salt product is obtained. The ash-containing slurry at the bottom of the concentrated brine precipitation tank enters the vacuum belt filter again for filtration. When the high-temperature gas is cooled in the gas-liquid separator, the water vapor liquefies and enters the bottom of the gas-liquid separation tank and is then sent to the light brine tank, and then goes to the batching tank for mixing. However, when water vapor is liquefied, part of the ammonia will also be liquefied and turned into ammonia water, which will cause the harmful components in the aluminum ash to return to the batching tank again. On the one hand, the harmful components are enriched with the circulation, resulting in an increase in the cost of aluminum ash treatment. On the other hand, the ammonia water cannot be discharged in time, resulting in a waste of resources. Summary of the invention
[0004] The utility model aims at the technical problem that harmful components of ammonia gas cannot be effectively recovered in the recovery and treatment of aluminum ash, and provides an ammonia recovery system in the harmless treatment of aluminum ash, which continuously extracts ammonia water at the bottom of a gas-liquid separator, improves the output of ammonia water products, greatly increases economic benefits, avoids the cyclic enrichment of harmful components in aluminum ash, reduces the ammonia content in the tail gas at the top of the ammonia absorption tower, and uses low-temperature refrigerated water as an absorbent, thereby reducing the amount of absorbent used and reducing the operating cost.
[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0006] The invention discloses an ammonia recovery system for harmless treatment of aluminum ash, comprising a batching tank, a reaction tank, a gas-liquid separator and an ammonia absorption tower, wherein the liquid outlet at the bottom of the batching tank is connected to the liquid inlet of the reaction tank, the gas outlet at the top of the reaction tank is connected to the gas inlet of the gas-liquid separator, the liquid outlet at the bottom of the reaction tank is connected to a slurry treatment system, the gas outlet of the upper gas collecting cylinder of the gas-liquid separator is connected to the gas inlet of the ammonia absorption tower, the ammonia water outlet at the bottom of the ammonia absorption tower is connected to an ammonia water finished product tank via a first ammonia water pump, the absorbent inlet of the ammonia absorption tower is connected to a chilled water pipe, and the liquid outlet at the bottom of the gas-liquid separator is connected to the ammonia water finished product tank via a second ammonia water pump.
[0007] In one technical solution, the gas-liquid separator and the second ammonia water pump form a liquid level interlock control.
[0008] In one technical solution, the second aqueous ammonia pump is a multi-stage centrifugal pump.
[0009] Compared with the prior art, the beneficial effects of the present invention are:
[0010] The liquid outlet at the bottom of the gas-liquid separator of the utility model is connected to the ammonia finished product tank through the second ammonia pump. The continuous extraction of ammonia at the bottom of the gas-liquid separator increases the output of ammonia finished product by 10% compared with the process of returning the ammonia at the bottom of the gas-liquid separator to the desalted brine tank and then to the batching tank for batching, which greatly increases the economic benefits. The ammonia concentration in the ammonia finished product tank is 14.8%, which meets the standard for external sale.
[0011] The absorbent inlet of the ammonia absorption tower of the utility model is connected to a chilled water pipe, and the temperature of the mixed gas is further reduced by using low-temperature chilled water, the solubility of ammonia in water is increased, the absorption efficiency is improved, and the ammonia content in the tail gas at the top of the ammonia absorption tower is greatly reduced; in addition, with the continuous extraction of ammonia water at the bottom of the gas-liquid separator, the cyclic enrichment of harmful components in the aluminum ash is avoided, and the ammonia content in the tail gas at the top of the ammonia absorption tower is further reduced to 0.03%, thereby avoiding the problem of excessive ammonia content in the tail gas, while reducing the amount of absorbent used and reducing the operating cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 This is a schematic diagram of the structure of an ammonia recovery system in the harmless treatment of aluminum ash before modification.
[0013] Figure 2 The utility model is a schematic diagram of the structure of an ammonia recovery system after modification in the harmless treatment of aluminum ash.
[0014] Markings in the attached figure: 1 is a batching tank, 2 is a reaction tank, 3 is a gas-liquid separator, 4 is an ammonia absorption tower, 5 is an ammonia finished product tank, 6 is a vacuum belt filter, 7 is a concentrated brine precipitation tank, 8 is an MVR evaporator, and 9 is a desalinated brine tank. DETAILED DESCRIPTION
[0015] The following embodiments are used to illustrate the present invention, but are not used to limit the protection scope of the present invention.
[0016] like Figure 2 As shown, the utility model is an ammonia recovery system in harmless treatment of aluminum ash, comprising a batching tank 1, a three-stage reaction tank 2, a gas-liquid separator 3 and an ammonia absorption tower 4. The liquid outlet at the bottom of the batching tank 1 is connected to three liquid inlets of the reaction tank 2 in sequence, the gas outlet at the top of each reaction tank 2 is connected to the gas inlet of the gas-liquid separator 3, the liquid outlet at the bottom of the reaction tank 2 is connected to the slurry treatment system, the gas outlet of the upper gas collecting cylinder of the gas-liquid separator 3 is connected to the gas inlet of the ammonia absorption tower 4, the ammonia water outlet at the bottom of the ammonia absorption tower 4 is connected to the ammonia water finished product tank 5 through the first ammonia water pump, the absorbent inlet of the ammonia absorption tower 4 is connected to the chilled water pipe, and the liquid outlet at the bottom of the gas-liquid separator 3 is connected to the ammonia water finished product tank 5 through the second ammonia water pump.
[0017] In one embodiment, the second ammonia water pump is a multi-stage centrifugal pump, such as Figure 2 As shown, in order to conveniently control the liquid level of the gas-liquid separator 3, the gas-liquid separator 3 and the second ammonia water pump are set to interlock control, that is, when the liquid level of the gas-liquid separator 3 is less than 0.2m, the second ammonia water pump is automatically turned off; when the liquid level of the gas-liquid separator 3 is greater than 0.4m, the second ammonia water pump is automatically turned on to transport the ammonia water to the ammonia water finished product tank 5. Compared with the process of returning the ammonia water at the bottom of the gas-liquid separator 3 to the salt water tank 9 and then to the batching tank 1 for batching, the output of the ammonia water finished product is increased by 10%, which greatly increases the economic benefits. The ammonia concentration in the ammonia water finished product tank 5 is 14.8%, which meets the standard for external sales.
[0018] In the utility model, water and aluminum ash are mixed in the batching tank 1 and then enter the reaction tank 2, and the water and aluminum ash generate high-temperature mixed gas in the reaction tank 2. The high-temperature mixed gas is cooled from 85°C to 25°C by the gas-liquid separator 3, and then sent to the ammonia absorption tower 4. The ammonia absorption tower 4 fully recovers the ammonia with -3°C chilled water, and the ammonia water at the bottom of the tower enters the ammonia finished product tank 5 through the first ammonia water pump. The use of low-temperature chilled water further reduces the temperature of the mixed gas, increases the solubility of ammonia in water, improves the absorption efficiency, and greatly reduces the ammonia content in the tail gas at the top of the ammonia absorption tower 4; in addition, with the continuous extraction of ammonia water at the bottom of the gas-liquid separator 3, the cyclic enrichment of harmful components in the aluminum ash is avoided, and the ammonia content in the tail gas at the top of the ammonia absorption tower 4 is further reduced to 0.03%, avoiding the problem of excessive ammonia content in the tail gas, while reducing the amount of absorbent and reducing the operating cost.
[0019] In one embodiment, if Figure 2As shown, the slurry treatment system includes a vacuum belt filter 6, a three-stage concentrated brine precipitation tank 7, an MVR evaporator and a slurry storage tank 9. The slurry at the bottom of the reaction tank 2 is filtered through the vacuum belt filter 6 to obtain concentrated brine, dilute brine and ash. The dilute brine is sent to the dilute brine tank, and the ash is dried. The concentrated brine contains about 0.5% ash. After precipitation in the concentrated brine precipitation tank, the pure brine enters the MVR for evaporation, and then undergoes crystallization, centrifugation and other steps to obtain a composite salt product. The ash-containing slurry enters the vacuum belt filter 6 for filtration again.
[0020] The embodiments described above are only preferred embodiments of the present invention and are only used to explain the present invention, not to limit the scope of implementation of the present invention. For those skilled in the art, other implementation methods can certainly be easily made by replacement or modification based on the technical contents disclosed in this specification. Therefore, all changes and improvements made on the principles of the present invention should be included in the scope of the patent application of the present invention.
Claims
1. An ammonia recovery system for harmless treatment of aluminum ash, comprising a batching tank (1), a reaction tank (2), a gas-liquid separator (3) and an ammonia absorption tower (4), wherein the bottom liquid outlet of the batching tank (1) is connected to the liquid inlet of the reaction tank (2), the top gas outlet of the reaction tank (2) is connected to the gas inlet of the gas-liquid separator (3), the bottom liquid outlet of the reaction tank (2) is connected to a slurry treatment system, the upper gas collecting cylinder gas outlet of the gas-liquid separator (3) is connected to the gas inlet of the ammonia absorption tower (4), and the bottom ammonia water outlet of the ammonia absorption tower (4) is connected to an ammonia water finished product tank (5) through a first ammonia water pump, characterized in that: The absorbent inlet of the ammonia absorption tower (4) is connected to a chilled water pipe, and the liquid outlet at the bottom of the gas-liquid separator (3) is connected to an ammonia finished product tank (5) via a second ammonia pump.
2. The ammonia recovery system in the harmless treatment of aluminum ash according to claim 1 is characterized in that: The gas-liquid separator (3) forms a liquid level interlock control with the second ammonia water pump.
3. The ammonia recovery system in the harmless treatment of aluminum ash according to claim 1 is characterized in that: The second ammonia water pump is a multi-stage centrifugal pump.