Ammonia gas absorbing and recycling system

Abstract

The utility model relates to an ammonia gas absorbing and recycling system which comprises a reaction unit capable of generating chemical reaction and generating ammonia gas, and further comprises an ammonia gas spraying and absorbing unit, and at least one solvent capable of dissolving the ammonia gas participates in the chemical reaction of the reaction unit. The ammonia gas input end of the ammonia gas spraying and absorbing unit is used for receiving ammonia gas generated by the reaction unit, and the spraying liquid input end of the ammonia gas spraying and absorbing unit is used for receiving a solvent output by the reaction unit. A solvent in an original reaction unit is used as an ammonia gas absorption liquid, so that introduction of a new absorption liquid is avoided, and the whole system is simplified; meanwhile, the solvent is the solvent of the original reaction unit and can be directly recycled after being absorbed, and the ammonia gas is not converted by any other substances in the process, so that secondary three wastes are prevented from being generated in the treatment process, the ammonia gas is more efficiently recycled, and the recycling rate of the ammonia gas is increased.

Description

Technical Field

[0001] The utility model relates to an ammonia absorption and recycling system. Background Art

[0002] Ammonia is a colorless gas with a pungent odor at room temperature. A large amount of ammonia tail gas is emitted in many chemical production processes, such as synthetic ammonia, urea pyrolysis production, alcohol-ammonia method to produce magnesium chloride and other reactions involving ammonia. If ammonia is not properly recovered, absorbed and treated, it will not only cause a waste of raw materials, but more seriously, it will cause environmental pollution and harm to human health. Therefore, it is a significant topic to properly absorb and treat ammonia in the production process.

[0003] At present, ammonia tail gas treatment generally adopts compression recovery (high concentration), water spraying, adsorption, chemical method and acid absorption method, for example:

[0004] (1) The compression recovery method is generally applicable to the case where the ammonia content in the tail gas is high. The ammonia tail gas is compressed and pressurized by a compressor and then cooled and condensed to recover the ammonia. For example, Chinese patents CN205868191U / CN203295210U use this method to liquefy ammonia and then recover it. Although this method can recover most of the ammonia for reuse, the recovery process involves pressurization. There are certain safety hazards in the ammonia compression process. In the actual production process, there are countless safety accidents caused by ammonia compression. Therefore, the high process conditions and great safety hazards are the disadvantages of the ammonia compression recovery method;

[0005] (2) Water spraying is one of the most widely used methods for absorbing ammonia. That is, ammonia is recovered by water spraying. For example, Chinese patents CN219630974U, CN217490328U and CN215428114U all use water spraying for ammonia absorption. However, due to the limited effect of ammonia absorption, the concentration of ammonia water can only reach 15%~20%. However, when the amount of ammonia in the tail gas is large, the amount of water consumed is greatly increased. In addition to the waste of water, the subsequent treatment of low-concentration ammonia water often becomes a problem.

[0006] (3) The absorption of ammonia by adsorption is to concentrate ammonia molecules and adsorb them on solid adsorbents such as activated carbon. Although this method has simple equipment and is easy to operate, the adsorbent used needs to be replaced regularly, which easily generates secondary solid waste. At the same time, the ammonia in the desorption process also faces the absorption treatment process again;

[0007] (4) Chemical treatment of ammonia is to remove ammonia by chemical reaction between chemical substances and ammonia. This technology is relatively mature and stable in operation, but the process requires washing ammonia with water and a decomposition device, which requires huge investment and production costs;

[0008] (5) The acid absorption method uses a dilute acid solution as an absorbent. Ammonia is absorbed in an aqueous solution by spraying and reacting to form salt. This method is an improvement on water absorption. The absorption efficiency is greatly improved by reacting to form salt, and the amount of water used for absorption is reduced. However, the ammonia is converted into ammonium salt as a by-product during the process. There are problems such as high requirements for absorption materials, ammonia loss that cannot be reused, and low added value of by-products.

[0009] However, the above-mentioned ammonia tail gas treatment methods have a series of disadvantages, such as high equipment requirements, high process risks, large absorption water consumption, complex process operations, generation of solid waste, high equipment investment costs, and low added value of by-products after treatment. Therefore, it is necessary to improve the above-mentioned technical problems, and this case was born. Utility Model Content

[0010] The present invention aims to improve the problems existing in the prior art, that is, the technical problem to be solved by the present invention is to provide an ammonia absorption and recycling system with reasonable design, which can recover ammonia more efficiently and improve the recovery rate of ammonia.

[0011] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: an ammonia absorption and recycling system, including a reaction unit that can undergo chemical reaction and produce ammonia, at least one solvent that can dissolve ammonia participates in the chemical reaction of the reaction unit, and also includes an ammonia spray absorption unit, the ammonia input end of the ammonia spray absorption unit receives the ammonia produced by the reaction unit, and the spray liquid input end of the ammonia spray absorption unit receives the solvent output by the reaction unit.

[0012] Furthermore, it also includes an absorption liquid reflux pipe connected to the ammonia spray absorption unit, and the absorption liquid output by the ammonia spray absorption unit is sent back to the reaction unit through the absorption liquid reflux pipe.

[0013] Furthermore, the ammonia spray absorption unit includes a plurality of spray absorption towers arranged in series, wherein between two adjacent spray absorption towers, the ammonia output end of the spray absorption tower at the upper level is connected to the ammonia input end of the spray absorption tower at the lower level, and the absorption liquid output end of the spray absorption tower at the lower level is connected to the spray liquid input end of the spray absorption tower at the upper level; the ammonia input end of the spray absorption tower at the first level is used for inputting ammonia generated by the reaction unit; and the spray liquid input end of the spray absorption tower at the last level is used for inputting the solvent of the reaction unit.

[0014] Furthermore, an absorption liquid circulation pipe is connected between the absorption liquid output end and the spray liquid input end of each stage of the spray absorption tower, and the absorption liquid circulation pipe is connected to an absorption liquid delivery pump, which pumps the absorption liquid from the absorption liquid output end of the spray absorption tower back to the spray liquid input end.

[0015] Furthermore, it also includes a heat exchanger, and the absorption liquid output from the absorption liquid output end of the spray absorption tower is heat-exchanged to a specified temperature range by the heat exchanger and then sent to the spray liquid input end.

[0016] Furthermore, an absorption liquid diversion pipe is connected to the absorption liquid circulation pipe of each stage of the spray absorption tower; between two adjacent spray absorption towers, the absorption liquid diversion pipe of the next spray absorption tower is connected to the spray liquid input end of the previous spray absorption tower; the absorption liquid diversion pipe of the spray absorption tower located in the first stage is connected to the absorption liquid reflux pipe.

[0017] Furthermore, the ammonia output end of the spray absorption tower at the last stage is connected to a tail gas fan, and the output end of the tail gas fan is connected to the terminal purification system.

[0018] Compared with the prior art, the utility model has the following effects: the utility model is reasonably designed, and the solvent in the original reaction unit is used as the ammonia absorption liquid, thereby avoiding the introduction of new absorption liquid and simplifying the entire system; at the same time, because the solvent is the solvent of the original reaction unit, it can be directly reused after absorption, and the ammonia is not converted into any other substances in this process, thereby avoiding the generation of secondary wastes during the treatment process, achieving more efficient recovery of ammonia, and improving the recovery and utilization rate of ammonia. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of an embodiment of the utility model. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0022] According to the properties of ammonia, it has a certain solubility in alcohol, ether and acid organic solvents except water. At the same time, one of these solvents is often used in the chemical reaction of the front-end reaction unit for ammonia production. Therefore, a scheme is proposed to use an organic solvent with a certain solubility in ammonia as an ammonia absorption liquid to absorb and reuse ammonia.

[0023] like Figure 1As shown, the utility model is an ammonia absorption and recycling system, including a reaction unit 10, in which a chemical reaction occurs and ammonia is generated, at least one solvent that can dissolve ammonia participates in the chemical reaction of the reaction unit 10, and the solubility of ammonia in the solvent is greater than the solubility in water; and also includes an ammonia spray absorption unit 11 for spraying and absorbing ammonia, wherein an ammonia input end of the ammonia spray absorption unit 11 receives the ammonia generated by the reaction unit 10, and a spray liquid input end of the ammonia spray absorption unit 11 receives the solvent output by the reaction unit 10, so that the solvent sprays and absorbs the ammonia.

[0024] In this embodiment, an absorption liquid reflux pipe 12 connected to the ammonia spray absorption unit 11 is further included, and the absorption liquid output by the ammonia spray absorption unit is sent back to the reaction unit 10 through the absorption liquid reflux pipe 12 .

[0025] In this embodiment, the ammonia spray absorption unit 11 includes a plurality of spray absorption towers 1 which are sequentially arranged and connected in series. The plurality of spray absorption towers 1 are connected in series along the flow direction of ammonia, that is, ammonia flows sequentially from the first-stage spray absorption tower to the last-stage spray absorption tower, and the absorption liquid contacts the ammonia in countercurrent and flows from the last-stage spray absorption tower to the first-stage spray absorption tower. Specifically, the ammonia input end of the spray absorption tower 1 located at the first stage is connected with a tail gas input pipe 2, and the tail gas input pipe 2 is connected with the tail gas output end of the reaction unit to facilitate the tail gas generated by the reaction unit to be input into the entire system; the spray liquid input end of the spray absorption tower 1 located at the last stage is connected with an absorption liquid input pipe 9, and the absorption liquid input pipe 9 is connected with the solvent output end of the reaction unit. The solvent used by the reaction unit is used as the ammonia absorption liquid and enters the entire system through the absorption liquid input pipe.

[0026] Furthermore, between two adjacent spray absorption towers 1, the ammonia output end of the spray absorption tower 1 at the upper level is connected to the ammonia input end of the spray absorption tower 1 at the lower level, that is, the ammonia treated by the spray absorption tower 1 is transported to the spray absorption tower at the lower level for further treatment; the absorption liquid output end of the spray absorption tower at the lower level is connected to the spray liquid input end of the spray absorption tower at the upper level, that is, the absorption liquid is transported to the spray absorption tower 1 at the upper level for reuse. By using the solvent used in the chemical reaction in the original reaction unit as the ammonia absorption liquid, the introduction of new absorption liquid is avoided, and the entire system is simplified; at the same time, because the solvent is the solvent of the original reaction unit, it can be directly reused after absorption, and the ammonia is not converted into any other substances in this process, avoiding the generation of secondary three wastes during the treatment process, achieving more efficient recovery of ammonia, and improving the recovery and utilization rate of ammonia.

[0027] In this embodiment, an absorption liquid circulation pipe 5 is connected between the absorption liquid output end and the spray liquid input end of each stage of the spray absorption tower 1, and the absorption liquid circulation pipe 5 is connected to an absorption liquid delivery pump 3, which pumps the absorption liquid from the absorption liquid output end of the spray absorption tower 1 back to the spray liquid input end.

[0028] In this embodiment, each spray absorption tower 1 further includes a heat exchanger 4. The absorption liquid output from the absorption liquid output end of the spray absorption tower 1 is sent to the spray liquid input end after heat exchange to a specified temperature range through the heat exchanger 4, so as to be reused for spraying. The heat exchanger is an existing mature product, which is used to transfer heat from a hot fluid to a cold fluid to achieve heat exchange. The heat exchanger is provided with a temperature detection unit, and the temperature of the absorption liquid after heat exchange by the heat exchanger is controlled by the temperature detection unit so that it can be within a specified temperature range. This part belongs to the prior art and will not be repeated here.

[0029] In this embodiment, the absorption liquid circulation pipe of each stage of the spray absorption tower 1 is connected with an absorption liquid diversion pipe 6, and the absorption liquid diversion pipe 6 is arranged in parallel with the absorption liquid circulation pipe. The absorption liquid diversion pipe 6 is used to divert the absorption liquid after heat exchange, and the absorption liquid diversion pipe 6 can be used to connect to the spray liquid input end of the previous spray absorption tower 1. Specifically: between two adjacent spray absorption towers 1, the absorption liquid diversion pipe 6 of the next spray absorption tower 1 is connected to the spray liquid input end of the previous spray absorption tower 1; the absorption liquid diversion pipe 6 of the first-stage spray absorption tower 1 is connected to the absorption liquid reflux pipe 12, so that the absorption liquid output by the whole system can be used as a front-end raw material to return to the original reaction unit 10. Considering the front-end process of ammonia tail gas production, the solvent used by the reaction unit is used as the absorption liquid, and after the absorption is completed, it is used as a front-end raw material to return to the original reaction unit, and the whole process forms a closed loop.

[0030] In this embodiment, each stage of absorption is provided with a heat exchanger, and the absorption temperature can be set and adjusted according to the different absorption liquids in the system (generally speaking, the lower the absorption temperature, the higher the ammonia solubility) and the ammonia reuse concentration requirements. While ensuring the absorption effect, the discharge concentration of the absorption liquid at each stage can be ensured to be stable, forming a stable closed loop with the front-end absorption liquid system.

[0031] In this embodiment, the enriched ammonia gas extraction end of the spray absorption tower 1 at the last stage is connected to a tail gas blower 7 , and the output end of the tail gas blower 7 is connected to a terminal purification system 8 .

[0032] In this embodiment, in actual use, different levels of spray absorption towers and absorption at different temperatures can be set according to different absorption systems, which reduces the residual ammonia in the exhaust gas while ensuring the ammonia absorption rate, and reduces the pressure of terminal purification. At the same time, different levels of absorption can be set in series according to the different solubility of ammonia in the solvents used in different systems, and the absorption system cooling can be set at the same time. The concentration of the discharged absorption liquid can be controlled according to the temperature adjustment to meet the needs of front-end use.

[0033] In this embodiment, ammonia in the tail gas is absorbed and recovered by spraying absorption liquid, thereby avoiding and solving the problems of high process conditions and great safety hazards in the compression recovery method of ammonia; by improving the conventional absorption liquid (water or dilute acid, etc.) and replacing it with alcohols, ethers or other organic solvents with a certain solubility for ammonia suitable for the chemical reaction in the reaction unit, the problems of large water consumption in conventional water absorption and subsequent application and treatment of the generated dilute ammonia water are solved, and the problems of by-product generation in the dilute acid absorption process and high requirements for system equipment materials are solved; the organic solvent of the reaction unit is used as the ammonia absorption liquid, and multi-stage absorption is set while absorption cooling and temperature adjustment are set to absorb and recover ammonia in the tail gas. The ammonia solution after absorption is then returned to the original reaction unit for reuse, thereby realizing a more efficient absorption recovery process with high ammonia recovery rate, and the absorption recovery conditions in the whole process are milder and the equipment material requirements are lower, simplifying the whole system, reducing the introduction and carryout of other substances in the recovery process, and reducing the generation of secondary waste.

[0034] If the present invention discloses or involves components or structures that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connection using bolts or screws), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by one-piece molding using a casting process) (except where it is obviously impossible to use an one-piece molding process).

[0035] In addition, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in the above utility model include states or shapes that are approximate, similar or close thereto.

[0036] Any component provided by the utility model can be assembled from multiple separate components, or can be a separate component manufactured by an integrated molding process.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the utility model can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the utility model, which should be included in the scope of the technical solution for protection of the utility model.

Claims

1. An ammonia absorption and recycling system, characterized in that: It includes a reaction unit that can undergo a chemical reaction and produce ammonia, wherein at least one solvent that can dissolve ammonia participates in the chemical reaction of the reaction unit; and it also includes an ammonia spray absorption unit, wherein an ammonia input end of the ammonia spray absorption unit receives the ammonia produced by the reaction unit, and a spray liquid input end of the ammonia spray absorption unit receives the solvent output by the reaction unit.

2. The ammonia absorption and recycling system according to claim 1, characterized in that: It also includes an absorption liquid reflux pipe connected to the ammonia spray absorption unit, and the absorption liquid output by the ammonia spray absorption unit is sent back to the reaction unit through the absorption liquid reflux pipe.

3. The ammonia absorption and recycling system according to claim 2, characterized in that: The ammonia spray absorption unit comprises a plurality of spray absorption towers arranged in series. Between two adjacent spray absorption towers, the ammonia output end of the spray absorption tower at the upper level is connected to the ammonia input end of the spray absorption tower at the lower level, and the absorption liquid output end of the spray absorption tower at the lower level is connected to the spray liquid input end of the spray absorption tower at the upper level; the ammonia input end of the spray absorption tower at the first level is used for inputting ammonia generated by the reaction unit; and the spray liquid input end of the spray absorption tower at the last level is used for inputting the solvent of the reaction unit.

4. The ammonia absorption and recycling system according to claim 3, characterized in that: An absorption liquid circulation pipe is connected between the absorption liquid output end and the spray liquid input end of each stage of the spray absorption tower. The absorption liquid circulation pipe is connected to an absorption liquid delivery pump, which pumps the absorption liquid from the absorption liquid output end of the spray absorption tower back to the spray liquid input end.

5. The ammonia absorption and recycling system according to claim 4, characterized in that: It also includes a heat exchanger. The absorption liquid output from the spray absorption tower is sent to the spray liquid input end after being heated to a specified temperature range through the heat exchanger.

6. The ammonia absorption and recycling system according to claim 5, characterized in that: The absorption liquid circulation pipe of each spray absorber is connected to an absorption liquid diversion pipe; between two adjacent spray absorbers, the absorption liquid diversion pipe of the next spray absorber is connected to the spray liquid input end of the previous spray absorber; the absorption liquid diversion pipe of the first spray absorber is connected to the absorption liquid reflux pipe.

7. The ammonia absorption and recycling system according to claim 3, characterized in that: The ammonia output end of the spray absorption tower at the last stage is connected to a tail gas fan, and the output end of the tail gas fan is connected to the terminal purification system.

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